Series comparison

The following changes since commit 344744e148e6e865f5a57e745b02a87e5ea534ad:

Merge tag 'dump-pull-request' of https://gitlab.com/marcandre.lureau/qemu into staging (2022-10-26 10:53:49 -0400)

are available in the Git repository at:

git://repo.or.cz/qemu/kevin.git tags/for-upstream

for you to fetch changes up to be8da05b5ed8fb546731b9edb997f303f272bad8:

block/block-backend: blk_set_enable_write_cache is IO_CODE (2022-10-27 20:27:37 +0200)

----------------------------------------------------------------
Block layer patches

- Cleanup bs->backing and bs->file handling
- Refactor bdrv_try_set_aio_context using transactions
- Changes for improved coroutine_fn consistency
- vhost-user-blk: fix the resize crash
- io_uring: Use of io_uring_register_ring_fd() led to breakage, revert
- vvfat: Fix some problems with r/w mode
- Code cleanup
- MAINTAINERS: Fold "Block QAPI, monitor, ..." into "Block layer core"

----------------------------------------------------------------
Alberto Faria (20):
      backup: remove incorrect coroutine_fn annotation
      block: remove incorrect coroutine_fn annotation
      monitor: add missing coroutine_fn annotation
      ssh: add missing coroutine_fn annotation
      block: add missing coroutine_fn annotation to prototypes
      coroutine-lock: add missing coroutine_fn annotation to prototypes
      coroutine-io: add missing coroutine_fn annotation to prototypes
      block: add missing coroutine_fn annotation to BlockDriverState callbacks
      qcow2: add coroutine_fn annotation for indirect-called functions
      commit: switch to *_co_* functions
      block: switch to *_co_* functions
      mirror: switch to *_co_* functions
      parallels: switch to *_co_* functions
      qcow: switch to *_co_* functions
      qcow2: switch to *_co_* functions
      qed: switch to *_co_* functions
      vdi: switch to *_co_* functions
      vhdx: switch to *_co_* functions
      vmdk: switch to *_co_* functions
      monitor: switch to *_co_* functions

Bin Meng (3):
      block: Ignore close() failure in get_tmp_filename()
      block: Refactor get_tmp_filename()
      block/nfs: Fix 32-bit Windows build

Emanuele Giuseppe Esposito (11):
      block.c: assert bs->aio_context is written under BQL and drains
      block: use transactions as a replacement of ->{can_}set_aio_context()
      bdrv_change_aio_context: use hash table instead of list of visited nodes
      blockjob: implement .change_aio_ctx in child_job
      block: implement .change_aio_ctx in child_of_bds
      block-backend: implement .change_aio_ctx in child_root
      block: use the new _change_ API instead of _can_set_ and _set_
      block: remove all unused ->can_set_aio_ctx and ->set_aio_ctx callbacks
      block: rename bdrv_child_try_change_aio_context in bdrv_try_change_aio_context
      block: remove bdrv_try_set_aio_context and replace it with bdrv_try_change_aio_context
      block/block-backend: blk_set_enable_write_cache is IO_CODE

Hervé Poussineau (2):
      vvfat: allow some writes to bootsector
      vvfat: allow spaces in file names

Li Feng (1):
      vhost-user-blk: fix the resize crash

Markus Armbruster (1):
      MAINTAINERS: Fold "Block QAPI, monitor, ..." into "Block layer core"

Paolo Bonzini (4):
      blkdebug: add missing coroutine_fn annotation for indirect-called functions
      qcow: manually add more coroutine_fn annotations
      qcow2: manually add more coroutine_fn annotations
      vmdk: manually add more coroutine_fn annotations

Sam Li (1):
      block/io_uring: revert "Use io_uring_register_ring_fd() to skip fd operations"

Vladimir Sementsov-Ogievskiy (15):
      block: BlockDriver: add .filtered_child_is_backing field
      block: introduce bdrv_open_file_child() helper
      block/blklogwrites: don't care to remove bs->file child on failure
      test-bdrv-graph-mod: update test_parallel_perm_update test case
      tests-bdrv-drain: bdrv_replace_test driver: declare supports_backing
      test-bdrv-graph-mod: fix filters to be filters
      block: document connection between child roles and bs->backing/bs->file
      block/snapshot: stress that we fallback to primary child
      Revert "block: Let replace_child_noperm free children"
      Revert "block: Let replace_child_tran keep indirect pointer"
      Revert "block: Restructure remove_file_or_backing_child()"
      Revert "block: Pass BdrvChild ** to replace_child_noperm"
      block: Manipulate bs->file / bs->backing pointers in .attach/.detach
      block/snapshot: drop indirection around bdrv_snapshot_fallback_ptr
      block: refactor bdrv_remove_file_or_backing_child to bdrv_remove_child

From: Markus Armbruster <armbru@redhat.com>

Section "Block QAPI, monitor, command line" is about the external
interfaces we provide for block devices.  It covers the relevant QAPI
schema parts, monitor and command line code, more or less.

The section's files are also covered by section "Block layer core",
except for the QAPI schema files.

I haven't acted as maintainer in this area for a long time.  Make it
official: add the QAPI schema files to section "Block layer core", and
delete section "Block QAPI, monitor, command line".

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221020120541.80757-1-armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 MAINTAINERS | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index XXXXXXX..XXXXXXX 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -XXX,XX +XXX,XX @@ S: Supported
 F: block*
 F: block/
 F: hw/block/
+F: qapi/block*.json
+F: qapi/transaction.json
 F: include/block/
 F: qemu-img*
 F: docs/tools/qemu-img.rst
@@ -XXX,XX +XXX,XX @@ F: include/qemu/co-shared-resource.h
 T: git https://gitlab.com/jsnow/qemu.git jobs
 T: git https://gitlab.com/vsementsov/qemu.git block
 
-Block QAPI, monitor, command line
-M: Markus Armbruster <armbru@redhat.com>
-S: Supported
-F: blockdev.c
-F: blockdev-hmp-cmds.c
-F: block/qapi.c
-F: qapi/block*.json
-F: qapi/transaction.json
-T: git https://repo.or.cz/qemu/armbru.git block-next
-
 Compute Express Link
 M: Ben Widawsky <ben.widawsky@intel.com>
 M: Jonathan Cameron <jonathan.cameron@huawei.com>
-- 
2.37.3

From: Bin Meng <bin.meng@windriver.com>

The temporary file has been created and is ready for use. Checking
return value of close() does not seem useful. The file descriptor
is almost certainly closed; see close(2) under "Dealing with error
returns from close()".

Let's simply ignore close() failure here.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221010040432.3380478-1-bin.meng@windriver.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ int get_tmp_filename(char *filename, int size)
     if (fd < 0) {
         return -errno;
     }
-    if (close(fd) != 0) {
-        unlink(filename);
-        return -errno;
-    }
+    close(fd);
     return 0;
 #endif
 }
-- 
2.37.3

From: Bin Meng <bin.meng@windriver.com>

At present there are two callers of get_tmp_filename() and they are
inconsistent.

One does:

/* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
    char *tmp_filename = g_malloc0(PATH_MAX + 1);
    ...
    ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);

while the other does:

s->qcow_filename = g_malloc(PATH_MAX);
    ret = get_tmp_filename(s->qcow_filename, PATH_MAX);

As we can see different 'size' arguments are passed. There are also
platform specific implementations inside the function, and the use
of snprintf is really undesirable.

The function name is also misleading. It creates a temporary file,
not just a filename.

Refactor this routine by changing its name and signature to:

char *create_tmp_file(Error **errp)

and use g_get_tmp_dir() / g_mkstemp() for a consistent implementation.

While we are here, add some comments to mention that /var/tmp is
preferred over /tmp on non-win32 hosts.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20221010040432.3380478-2-bin.meng@windriver.com>
[kwolf: Fixed incorrect errno negation and iotest 051]
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h |  2 +-
 block.c                          | 56 +++++++++++++++++---------------
 block/vvfat.c                    |  7 ++--
 tests/qemu-iotests/051           |  3 +-
 tests/qemu-iotests/051.out       |  2 +-
 tests/qemu-iotests/051.pc.out    |  2 +-
 6 files changed, 38 insertions(+), 34 deletions(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ static inline BlockDriverState *child_bs(BdrvChild *child)
 }
 
 int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp);
-int get_tmp_filename(char *filename, int size);
+char *create_tmp_file(Error **errp);
 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
                                       QDict *options);
 
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
 
 /*
  * Create a uniquely-named empty temporary file.
- * Return 0 upon success, otherwise a negative errno value.
+ * Return the actual file name used upon success, otherwise NULL.
+ * This string should be freed with g_free() when not needed any longer.
+ *
+ * Note: creating a temporary file for the caller to (re)open is
+ * inherently racy. Use g_file_open_tmp() instead whenever practical.
  */
-int get_tmp_filename(char *filename, int size)
+char *create_tmp_file(Error **errp)
 {
-#ifdef _WIN32
-    char temp_dir[MAX_PATH];
-    /* GetTempFileName requires that its output buffer (4th param)
-       have length MAX_PATH or greater.  */
-    assert(size >= MAX_PATH);
-    return (GetTempPath(MAX_PATH, temp_dir)
-            && GetTempFileName(temp_dir, "qem", 0, filename)
-            ? 0 : -GetLastError());
-#else
     int fd;
     const char *tmpdir;
-    tmpdir = getenv("TMPDIR");
-    if (!tmpdir) {
+    g_autofree char *filename = NULL;
+
+    tmpdir = g_get_tmp_dir();
+#ifndef _WIN32
+    /*
+     * See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot")
+     *
+     * This function is used to create temporary disk images (like -snapshot),
+     * so the files can become very large. /tmp is often a tmpfs where as
+     * /var/tmp is usually on a disk, so more appropriate for disk images.
+     */
+    if (!g_strcmp0(tmpdir, "/tmp")) {
         tmpdir = "/var/tmp";
     }
-    if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) {
-        return -EOVERFLOW;
-    }
-    fd = mkstemp(filename);
+#endif
+
+    filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir);
+    fd = g_mkstemp(filename);
     if (fd < 0) {
-        return -errno;
+        error_setg_errno(errp, errno, "Could not open temporary file '%s'",
+                         filename);
+        return NULL;
     }
     close(fd);
-    return 0;
-#endif
+
+    return g_steal_pointer(&filename);
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
                                                    QDict *snapshot_options,
                                                    Error **errp)
 {
-    /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
-    char *tmp_filename = g_malloc0(PATH_MAX + 1);
+    g_autofree char *tmp_filename = NULL;
     int64_t total_size;
     QemuOpts *opts = NULL;
     BlockDriverState *bs_snapshot = NULL;
@@ -XXX,XX +XXX,XX @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
     }
 
     /* Create the temporary image */
-    ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
-    if (ret < 0) {
-        error_setg_errno(errp, -ret, "Could not get temporary filename");
+    tmp_filename = create_tmp_file(errp);
+    if (!tmp_filename) {
         goto out;
     }
 
@@ -XXX,XX +XXX,XX @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
 
 out:
     qobject_unref(snapshot_options);
-    g_free(tmp_filename);
     return bs_snapshot;
 }
 
diff --git a/block/vvfat.c b/block/vvfat.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -XXX,XX +XXX,XX @@ static int enable_write_target(BlockDriverState *bs, Error **errp)
 
     array_init(&(s->commits), sizeof(commit_t));
 
-    s->qcow_filename = g_malloc(PATH_MAX);
-    ret = get_tmp_filename(s->qcow_filename, PATH_MAX);
-    if (ret < 0) {
-        error_setg_errno(errp, -ret, "can't create temporary file");
+    s->qcow_filename = create_tmp_file(errp);
+    if (!s->qcow_filename) {
+        ret = -ENOENT;
         goto err;
     }
 
diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index XXXXXXX..XXXXXXX 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -XXX,XX +XXX,XX @@ if [ "${VALGRIND_QEMU_VM}" == "y" ]; then
     _casenotrun "Valgrind needs a valid TMPDIR for itself"
 fi
 VALGRIND_QEMU_VM= \
-TMPDIR=/nonexistent run_qemu -drive driver=null-co,snapshot=on
+TMPDIR=/nonexistent run_qemu -drive driver=null-co,snapshot=on |
+    sed -e "s#'[^']*/vl\.[A-Za-z0-9]\{6\}'#SNAPSHOT_PATH#g"
 
 # Using snapshot=on together with read-only=on
 echo "info block" |
diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
index XXXXXXX..XXXXXXX 100644
--- a/tests/qemu-iotests/051.out
+++ b/tests/qemu-iotests/051.out
@@ -XXX,XX +XXX,XX @@ wrote 4096/4096 bytes at offset 0
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Testing: -drive driver=null-co,snapshot=on
-QEMU_PROG: -drive driver=null-co,snapshot=on: Could not get temporary filename: No such file or directory
+QEMU_PROG: -drive driver=null-co,snapshot=on: Could not open temporary file SNAPSHOT_PATH: No such file or directory
 
 Testing: -drive file=TEST_DIR/t.qcow2,snapshot=on,read-only=on,if=none,id=drive0
 QEMU X.Y.Z monitor - type 'help' for more information
diff --git a/tests/qemu-iotests/051.pc.out b/tests/qemu-iotests/051.pc.out
index XXXXXXX..XXXXXXX 100644
--- a/tests/qemu-iotests/051.pc.out
+++ b/tests/qemu-iotests/051.pc.out
@@ -XXX,XX +XXX,XX @@ wrote 4096/4096 bytes at offset 0
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Testing: -drive driver=null-co,snapshot=on
-QEMU_PROG: -drive driver=null-co,snapshot=on: Could not get temporary filename: No such file or directory
+QEMU_PROG: -drive driver=null-co,snapshot=on: Could not open temporary file SNAPSHOT_PATH: No such file or directory
 
 Testing: -drive file=TEST_DIR/t.qcow2,snapshot=on,read-only=on,if=none,id=drive0
 QEMU X.Y.Z monitor - type 'help' for more information
-- 
2.37.3

From: Hervé Poussineau <hpoussin@reactos.org>

'reserved1' field in bootsector is used to mark volume dirty, or need to verify.
Allow writes to bootsector which only changes the 'reserved1' field.

This fixes I/O errors on Windows guests.

Resolves: https://bugs.launchpad.net/qemu/+bug/1889421
Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Message-Id: <20221010175511.3414357-2-hpoussin@reactos.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vvfat.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -XXX,XX +XXX,XX @@ DLOG(checkpoint());
 
     vvfat_close_current_file(s);
 
+    if (sector_num == s->offset_to_bootsector && nb_sectors == 1) {
+        /*
+         * Write on bootsector. Allow only changing the reserved1 field,
+         * used to mark volume dirtiness
+         */
+        unsigned char *bootsector = s->first_sectors
+                                    + s->offset_to_bootsector * 0x200;
+        /*
+         * LATER TODO: if FAT32, this is wrong (see init_directories(),
+         * which always creates a FAT16 bootsector)
+         */
+        const int reserved1_offset = offsetof(bootsector_t, u.fat16.reserved1);
+
+        for (i = 0; i < 0x200; i++) {
+            if (i != reserved1_offset && bootsector[i] != buf[i]) {
+                fprintf(stderr, "Tried to write to protected bootsector\n");
+                return -1;
+            }
+        }
+
+        /* Update bootsector with the only updatable byte, and return success */
+        bootsector[reserved1_offset] = buf[reserved1_offset];
+        return 0;
+    }
+
     /*
      * Some sanity checks:
      * - do not allow writing to the boot sector
      */
-
     if (sector_num < s->offset_to_fat)
         return -1;
 
-- 
2.37.3

From: Hervé Poussineau <hpoussin@reactos.org>

In R/W mode, files with spaces were never created on host side.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1176
Fixes: c79e243ed67683d6d06692bd7040f7394da178b0
Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221010175511.3414357-3-hpoussin@reactos.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vvfat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -XXX,XX +XXX,XX @@ static bool valid_filename(const unsigned char *name)
               (c >= 'A' && c <= 'Z') ||
               (c >= 'a' && c <= 'z') ||
               c > 127 ||
-              strchr("$%'-_@~`!(){}^#&.+,;=[]", c) != NULL))
+              strchr(" $%'-_@~`!(){}^#&.+,;=[]", c) != NULL))
         {
             return false;
         }
-- 
2.37.3

From: Sam Li <faithilikerun@gmail.com>

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1193

The commit "Use io_uring_register_ring_fd() to skip fd operations" broke
when booting a guest with iothread and io_uring. That is because the
io_uring_register_ring_fd() call is made from the main thread instead of
IOThread where io_uring_submit() is called. It can not be guaranteed
to register the ring fd in the correct thread or unregister the same ring
fd if the IOThread is disabled. This optimization is not critical so we
will revert previous commit.

This reverts commit e2848bc574fe2715c694bf8fe9a1ba7f78a1125a
and 77e3f038af1764983087e3551a0fde9951952c4d.

Cc: qemu-stable@nongnu.org
Signed-off-by: Sam Li <faithilikerun@gmail.com>
Message-Id: <20220924144815.5591-1-faithilikerun@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Tested-by: Dario Faggioli <dfaggioli@suse.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/io_uring.c | 13 +------------
 meson.build      |  1 -
 2 files changed, 1 insertion(+), 13 deletions(-)

diff --git a/block/io_uring.c b/block/io_uring.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io_uring.c
+++ b/block/io_uring.c
@@ -XXX,XX +XXX,XX @@
 #include "qemu/osdep.h"
 #include <liburing.h>
 #include "block/aio.h"
-#include "qemu/error-report.h"
 #include "qemu/queue.h"
 #include "block/block.h"
 #include "block/raw-aio.h"
@@ -XXX,XX +XXX,XX @@
 #include "qapi/error.h"
 #include "trace.h"
 
-
 /* io_uring ring size */
 #define MAX_ENTRIES 128
 
@@ -XXX,XX +XXX,XX @@ LuringState *luring_init(Error **errp)
     }
 
     ioq_init(&s->io_q);
-#ifdef CONFIG_LIBURING_REGISTER_RING_FD
-    if (io_uring_register_ring_fd(&s->ring) < 0) {
-        /*
-         * Only warn about this error: we will fallback to the non-optimized
-         * io_uring operations.
-         */
-        warn_report("failed to register linux io_uring ring file descriptor");
-    }
-#endif
-
     return s;
+
 }
 
 void luring_cleanup(LuringState *s)
diff --git a/meson.build b/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/meson.build
+++ b/meson.build
@@ -XXX,XX +XXX,XX @@ config_host_data.set('CONFIG_LIBNFS', libnfs.found())
 config_host_data.set('CONFIG_LIBSSH', libssh.found())
 config_host_data.set('CONFIG_LINUX_AIO', libaio.found())
 config_host_data.set('CONFIG_LINUX_IO_URING', linux_io_uring.found())
-config_host_data.set('CONFIG_LIBURING_REGISTER_RING_FD', cc.has_function('io_uring_register_ring_fd', prefix: '#include <liburing.h>', dependencies:linux_io_uring))
 config_host_data.set('CONFIG_LIBPMEM', libpmem.found())
 config_host_data.set('CONFIG_NUMA', numa.found())
 config_host_data.set('CONFIG_OPENGL', opengl.found())
-- 
2.37.3

From: Li Feng <fengli@smartx.com>

If the os is not installed and doesn't have the virtio guest driver,
the vhost dev isn't started, so the dev->vdev is NULL.

Reproduce: mount a Win 2019 iso, go into the install ui, then resize
the virtio-blk device, qemu crash.

Signed-off-by: Li Feng <fengli@smartx.com>
Message-Id: <20220919121816.3252223-1-fengli@smartx.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/block/vhost-user-blk.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -XXX,XX +XXX,XX @@ static int vhost_user_blk_handle_config_change(struct vhost_dev *dev)
     VHostUserBlk *s = VHOST_USER_BLK(dev->vdev);
     Error *local_err = NULL;
 
+    if (!dev->started) {
+        return 0;
+    }
+
     ret = vhost_dev_get_config(dev, (uint8_t *)&blkcfg,
                                vdev->config_len, &local_err);
     if (ret < 0) {
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Unfortunately not all filters use .file child as filtered child. Two
exclusions are mirror_top and commit_top. Happily they both are private
filters. Bad thing is that this inconsistency is observable through qmp
commands query-block / query-named-block-nodes. So, could we just
change mirror_top and commit_top to use file child as all other filter
driver is an open question. Probably, we could do that with some kind
of deprecation period, but how to warn users during it?

For now, let's just add a field so we can distinguish them in generic
code, it will be used in further commits.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-2-vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h | 13 +++++++++++++
 block/commit.c                   |  1 +
 block/mirror.c                   |  1 +
 3 files changed, 15 insertions(+)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BlockDriver {
      * (And this filtered child must then be bs->file or bs->backing.)
      */
     bool is_filter;
+    /*
+     * Only make sense for filter drivers, for others must be false.
+     * If true, filtered child is bs->backing. Otherwise it's bs->file.
+     * Only two internal filters use bs->backing as filtered child and has this
+     * field set to true: mirror_top and commit_top.
+     *
+     * Never create any more such filters!
+     *
+     * TODO: imagine how to deprecate this behavior and make all filters work
+     * similarly using bs->file as filtered child.
+     */
+    bool filtered_child_is_backing;
+
     /*
      * Set to true if the BlockDriver is a format driver.  Format nodes
      * generally do not expect their children to be other format nodes
diff --git a/block/commit.c b/block/commit.c
index XXXXXXX..XXXXXXX 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_commit_top = {
     .bdrv_child_perm            = bdrv_commit_top_child_perm,
 
     .is_filter                  = true,
+    .filtered_child_is_backing  = true,
 };
 
 void commit_start(const char *job_id, BlockDriverState *bs,
diff --git a/block/mirror.c b/block/mirror.c
index XXXXXXX..XXXXXXX 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_mirror_top = {
     .bdrv_child_perm            = bdrv_mirror_top_child_perm,
 
     .is_filter                  = true,
+    .filtered_child_is_backing  = true,
 };
 
 static BlockJob *mirror_start_job(
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Almost all drivers call bdrv_open_child() similarly. Let's create a
helper for this.

The only not updated drivers that call bdrv_open_child() to set
bs->file are raw-format and snapshot-access:
    raw-format sometimes want to have filtered child but
        don't set drv->is_filter to true.
    snapshot-access wants only DATA | PRIMARY

Possibly we should implement drv->is_filter_func() handler, to consider
raw-format as filter when it works as filter.. But it's another story.

Note also, that we decrease assignments to bs->file in code: it helps
us restrict modifying this field in further commit.

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -XXX,XX +XXX,XX @@ BdrvChild *bdrv_open_child(const char *filename,
                            const BdrvChildClass *child_class,
                            BdrvChildRole child_role,
                            bool allow_none, Error **errp);
+int bdrv_open_file_child(const char *filename,
+                         QDict *options, const char *bdref_key,
+                         BlockDriverState *parent, Error **errp);
 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp);
 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
                         Error **errp);
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ BdrvChild *bdrv_open_child(const char *filename,
                              errp);
 }
 
+/*
+ * Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
+ */
+int bdrv_open_file_child(const char *filename,
+                         QDict *options, const char *bdref_key,
+                         BlockDriverState *parent, Error **errp)
+{
+    BdrvChildRole role;
+
+    /* commit_top and mirror_top don't use this function */
+    assert(!parent->drv->filtered_child_is_backing);
+
+    role = parent->drv->is_filter ?
+        (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
+
+    parent->file = bdrv_open_child(filename, options, bdref_key, parent,
+                                   &child_of_bds, role, false, errp);
+
+    return parent->file ? 0 : -EINVAL;
+}
+
 /*
  * TODO Future callers may need to specify parent/child_class in order for
  * option inheritance to work. Existing callers use it for the root node.
diff --git a/block/blkdebug.c b/block/blkdebug.c
index XXXXXXX..XXXXXXX 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -XXX,XX +XXX,XX @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Open the image file */
-    bs->file = bdrv_open_child(qemu_opt_get(opts, "x-image"), options, "image",
-                               bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(qemu_opt_get(opts, "x-image"), options, "image",
+                               bs, errp);
+    if (ret < 0) {
         goto out;
     }
 
diff --git a/block/blklogwrites.c b/block/blklogwrites.c
index XXXXXXX..XXXXXXX 100644
--- a/block/blklogwrites.c
+++ b/block/blklogwrites.c
@@ -XXX,XX +XXX,XX @@ static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Open the file */
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false,
-                               errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/blkreplay.c b/block/blkreplay.c
index XXXXXXX..XXXXXXX 100644
--- a/block/blkreplay.c
+++ b/block/blkreplay.c
@@ -XXX,XX +XXX,XX @@ static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
 
     /* Open the image file */
-    bs->file = bdrv_open_child(NULL, options, "image", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "image", bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/blkverify.c b/block/blkverify.c
index XXXXXXX..XXXXXXX 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -XXX,XX +XXX,XX @@ static int blkverify_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Open the raw file */
-    bs->file = bdrv_open_child(qemu_opt_get(opts, "x-raw"), options, "raw",
-                               bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(qemu_opt_get(opts, "x-raw"), options, "raw",
+                               bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/bochs.c b/block/bochs.c
index XXXXXXX..XXXXXXX 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -XXX,XX +XXX,XX @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
         return ret;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     ret = bdrv_pread(bs->file, 0, sizeof(bochs), &bochs, 0);
diff --git a/block/cloop.c b/block/cloop.c
index XXXXXXX..XXXXXXX 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -XXX,XX +XXX,XX @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
         return ret;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     /* read header */
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index XXXXXXX..XXXXXXX 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -XXX,XX +XXX,XX @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
     int64_t cluster_size;
     g_autoptr(BlockdevOptions) full_opts = NULL;
     BlockdevOptionsCbw *opts;
+    int ret;
 
     full_opts = cbw_parse_options(options, errp);
     if (!full_opts) {
@@ -XXX,XX +XXX,XX @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
     assert(full_opts->driver == BLOCKDEV_DRIVER_COPY_BEFORE_WRITE);
     opts = &full_opts->u.copy_before_write;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     s->target = bdrv_open_child(NULL, options, "target", bs, &child_of_bds,
diff --git a/block/copy-on-read.c b/block/copy-on-read.c
index XXXXXXX..XXXXXXX 100644
--- a/block/copy-on-read.c
+++ b/block/copy-on-read.c
@@ -XXX,XX +XXX,XX @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
     BDRVStateCOR *state = bs->opaque;
     /* Find a bottom node name, if any */
     const char *bottom_node = qdict_get_try_str(options, "bottom");
+    int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     bs->supported_read_flags = BDRV_REQ_PREFETCH;
diff --git a/block/crypto.c b/block/crypto.c
index XXXXXXX..XXXXXXX 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -XXX,XX +XXX,XX @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
 {
     BlockCrypto *crypto = bs->opaque;
     QemuOpts *opts = NULL;
-    int ret = -EINVAL;
+    int ret;
     QCryptoBlockOpenOptions *open_opts = NULL;
     unsigned int cflags = 0;
     QDict *cryptoopts = NULL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     bs->supported_write_flags = BDRV_REQ_FUA &
@@ -XXX,XX +XXX,XX @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
 
     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
+        ret = -EINVAL;
         goto cleanup;
     }
 
@@ -XXX,XX +XXX,XX @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
 
     open_opts = block_crypto_open_opts_init(cryptoopts, errp);
     if (!open_opts) {
+        ret = -EINVAL;
         goto cleanup;
     }
 
diff --git a/block/dmg.c b/block/dmg.c
index XXXXXXX..XXXXXXX 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -XXX,XX +XXX,XX @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
         return ret;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     block_module_load_one("dmg-bz2");
diff --git a/block/filter-compress.c b/block/filter-compress.c
index XXXXXXX..XXXXXXX 100644
--- a/block/filter-compress.c
+++ b/block/filter-compress.c
@@ -XXX,XX +XXX,XX @@
 static int compress_open(BlockDriverState *bs, QDict *options, int flags,
                          Error **errp)
 {
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    int ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv)) {
diff --git a/block/parallels.c b/block/parallels.c
index XXXXXXX..XXXXXXX 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -XXX,XX +XXX,XX @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
     Error *local_err = NULL;
     char *buf;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     ret = bdrv_pread(bs->file, 0, sizeof(ph), &ph, 0);
diff --git a/block/preallocate.c b/block/preallocate.c
index XXXXXXX..XXXXXXX 100644
--- a/block/preallocate.c
+++ b/block/preallocate.c
@@ -XXX,XX +XXX,XX @@ static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
                             Error **errp)
 {
     BDRVPreallocateState *s = bs->opaque;
+    int ret;
 
     /*
      * s->data_end and friends should be initialized on permission update.
@@ -XXX,XX +XXX,XX @@ static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
      */
     s->file_end = s->zero_start = s->data_end = -EINVAL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     if (!preallocate_absorb_opts(&s->opts, options, bs->file->bs, errp)) {
diff --git a/block/qcow.c b/block/qcow.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -XXX,XX +XXX,XX @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
     encryptfmt = qdict_get_try_str(encryptopts, "format");
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -XXX,XX +XXX,XX @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
         .errp = errp,
         .ret = -EINPROGRESS
     };
+    int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     /* Initialise locks */
diff --git a/block/qed.c b/block/qed.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -XXX,XX +XXX,XX @@ static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
         .errp = errp,
         .ret = -EINPROGRESS
     };
+    int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     bdrv_qed_init_state(bs);
diff --git a/block/replication.c b/block/replication.c
index XXXXXXX..XXXXXXX 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -XXX,XX +XXX,XX @@ static int replication_open(BlockDriverState *bs, QDict *options,
     const char *mode;
     const char *top_id;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     ret = -EINVAL;
diff --git a/block/throttle.c b/block/throttle.c
index XXXXXXX..XXXXXXX 100644
--- a/block/throttle.c
+++ b/block/throttle.c
@@ -XXX,XX +XXX,XX @@ static int throttle_open(BlockDriverState *bs, QDict *options,
     char *group;
     int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
     bs->supported_write_flags = bs->file->bs->supported_write_flags |
                                 BDRV_REQ_WRITE_UNCHANGED;
diff --git a/block/vdi.c b/block/vdi.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -XXX,XX +XXX,XX @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
     QemuUUID uuid_link, uuid_parent;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     logout("\n");
diff --git a/block/vhdx.c b/block/vhdx.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -XXX,XX +XXX,XX @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
     uint64_t signature;
     Error *local_err = NULL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     s->bat = NULL;
diff --git a/block/vmdk.c b/block/vmdk.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -XXX,XX +XXX,XX @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
     BDRVVmdkState *s = bs->opaque;
     uint32_t magic;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     buf = vmdk_read_desc(bs->file, 0, errp);
diff --git a/block/vpc.c b/block/vpc.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -XXX,XX +XXX,XX @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
     int64_t bs_size;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     opts = qemu_opts_create(&vpc_runtime_opts, NULL, 0, &error_abort);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

test_parallel_perm_update() does two things that we are going to
restrict in the near future:

1. It updates bs->file field by hand. bs->file will be managed
   automatically by generic code (together with bs->children list).

Let's better refactor our "tricky" bds to have own state where one
   of children is linked as "selected".
   This also looks less "tricky", so avoid using this word.

2. It create FILTERED children that are not PRIMARY. Except for tests
   all FILTERED children in the Qemu block layer are always PRIMARY as
   well.  We are going to formalize this rule, so let's better use DATA
   children here.

3. It creates more than one FILTERED child, which is already abandoned
   in BDRV_CHILD_FILTERED's description.

While being here, update the picture to better correspond to the test
code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-5-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/unit/test-bdrv-graph-mod.c | 80 +++++++++++++++++++-------------
 1 file changed, 49 insertions(+), 31 deletions(-)

diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -XXX,XX +XXX,XX @@ static void test_parallel_exclusive_write(void)
     bdrv_unref(top);
 }
 
-static void write_to_file_perms(BlockDriverState *bs, BdrvChild *c,
-                                     BdrvChildRole role,
-                                     BlockReopenQueue *reopen_queue,
-                                     uint64_t perm, uint64_t shared,
-                                     uint64_t *nperm, uint64_t *nshared)
+/*
+ * write-to-selected node may have several DATA children, one of them may be
+ * "selected". Exclusive write permission is taken on selected child.
+ *
+ * We don't realize write handler itself, as we need only to test how permission
+ * update works.
+ */
+typedef struct BDRVWriteToSelectedState {
+    BdrvChild *selected;
+} BDRVWriteToSelectedState;
+
+static void write_to_selected_perms(BlockDriverState *bs, BdrvChild *c,
+                                    BdrvChildRole role,
+                                    BlockReopenQueue *reopen_queue,
+                                    uint64_t perm, uint64_t shared,
+                                    uint64_t *nperm, uint64_t *nshared)
 {
-    if (bs->file && c == bs->file) {
+    BDRVWriteToSelectedState *s = bs->opaque;
+
+    if (s->selected && c == s->selected) {
         *nperm = BLK_PERM_WRITE;
         *nshared = BLK_PERM_ALL & ~BLK_PERM_WRITE;
     } else {
@@ -XXX,XX +XXX,XX @@ static void write_to_file_perms(BlockDriverState *bs, BdrvChild *c,
     }
 }
 
-static BlockDriver bdrv_write_to_file = {
-    .format_name = "tricky-perm",
-    .bdrv_child_perm = write_to_file_perms,
+static BlockDriver bdrv_write_to_selected = {
+    .format_name = "write-to-selected",
+    .instance_size = sizeof(BDRVWriteToSelectedState),
+    .bdrv_child_perm = write_to_selected_perms,
 };
 
 
@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_write_to_file = {
  * The following test shows that topological-sort order is required for
  * permission update, simple DFS is not enough.
  *
- * Consider the block driver which has two filter children: one active
- * with exclusive write access and one inactive with no specific
- * permissions.
+ * Consider the block driver (write-to-selected) which has two children: one is
+ * selected so we have exclusive write access to it and for the other one we
+ * don't need any specific permissions.
  *
  * And, these two children has a common base child, like this:
+ *   (additional "top" on top is used in test just because the only public
+ *    function to update permission should get a specific child to update.
+ *    Making bdrv_refresh_perms() public just for this test isn't worth it)
  *
- * ┌─────┐     ┌──────┐
- * │ fl2 │ ◀── │ top  │
- * └─────┘     └──────┘
+ * ┌─────┐     ┌───────────────────┐     ┌─────┐
+ * │ fl2 │ ◀── │ write-to-selected │ ◀── │ top │
+ * └─────┘     └───────────────────┘     └─────┘
  *   │           │
  *   │           │ w
  *   │           ▼
@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_write_to_file = {
  *
  * So, exclusive write is propagated.
  *
- * Assume, we want to make fl2 active instead of fl1.
- * So, we set some option for top driver and do permission update.
+ * Assume, we want to select fl2 instead of fl1.
+ * So, we set some option for write-to-selected driver and do permission update.
  *
  * With simple DFS, if permission update goes first through
- * top->fl1->base branch it will succeed: it firstly drop exclusive write
- * permissions and than apply them for another BdrvChildren.
- * But if permission update goes first through top->fl2->base branch it
- * will fail, as when we try to update fl2->base child, old not yet
+ * write-to-selected -> fl1 -> base branch it will succeed: it firstly drop
+ * exclusive write permissions and than apply them for another BdrvChildren.
+ * But if permission update goes first through write-to-selected -> fl2 -> base
+ * branch it will fail, as when we try to update fl2->base child, old not yet
  * updated fl1->base child will be in conflict.
  *
  * With topological-sort order we always update parents before children, so fl1
@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_write_to_file = {
 static void test_parallel_perm_update(void)
 {
     BlockDriverState *top = no_perm_node("top");
-    BlockDriverState *tricky =
-            bdrv_new_open_driver(&bdrv_write_to_file, "tricky", BDRV_O_RDWR,
+    BlockDriverState *ws =
+            bdrv_new_open_driver(&bdrv_write_to_selected, "ws", BDRV_O_RDWR,
                                  &error_abort);
+    BDRVWriteToSelectedState *s = ws->opaque;
     BlockDriverState *base = no_perm_node("base");
     BlockDriverState *fl1 = pass_through_node("fl1");
     BlockDriverState *fl2 = pass_through_node("fl2");
@@ -XXX,XX +XXX,XX @@ static void test_parallel_perm_update(void)
      */
     bdrv_ref(base);
 
-    bdrv_attach_child(top, tricky, "file", &child_of_bds, BDRV_CHILD_DATA,
+    bdrv_attach_child(top, ws, "file", &child_of_bds, BDRV_CHILD_DATA,
                       &error_abort);
-    c_fl1 = bdrv_attach_child(tricky, fl1, "first", &child_of_bds,
-                              BDRV_CHILD_FILTERED, &error_abort);
-    c_fl2 = bdrv_attach_child(tricky, fl2, "second", &child_of_bds,
-                              BDRV_CHILD_FILTERED, &error_abort);
+    c_fl1 = bdrv_attach_child(ws, fl1, "first", &child_of_bds,
+                              BDRV_CHILD_DATA, &error_abort);
+    c_fl2 = bdrv_attach_child(ws, fl2, "second", &child_of_bds,
+                              BDRV_CHILD_DATA, &error_abort);
     bdrv_attach_child(fl1, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
                       &error_abort);
     bdrv_attach_child(fl2, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
                       &error_abort);
 
     /* Select fl1 as first child to be active */
-    tricky->file = c_fl1;
+    s->selected = c_fl1;
     bdrv_child_refresh_perms(top, top->children.lh_first, &error_abort);
 
     assert(c_fl1->perm & BLK_PERM_WRITE);
     assert(!(c_fl2->perm & BLK_PERM_WRITE));
 
     /* Now, try to switch active child and update permissions */
-    tricky->file = c_fl2;
+    s->selected = c_fl2;
     bdrv_child_refresh_perms(top, top->children.lh_first, &error_abort);
 
     assert(c_fl2->perm & BLK_PERM_WRITE);
     assert(!(c_fl1->perm & BLK_PERM_WRITE));
 
     /* Switch once more, to not care about real child order in the list */
-    tricky->file = c_fl1;
+    s->selected = c_fl1;
     bdrv_child_refresh_perms(top, top->children.lh_first, &error_abort);
 
     assert(c_fl1->perm & BLK_PERM_WRITE);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

We do add COW child to the node.  In future we are going to forbid
adding COW child to the node that doesn't support backing. So, fix it
here now.

Don't worry about setting bs->backing itself: in further commit we'll
update the block-layer to automatically set/unset this field in generic
code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-6-vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/unit/test-bdrv-drain.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn bdrv_replace_test_co_drain_end(BlockDriverState *bs)
 static BlockDriver bdrv_replace_test = {
     .format_name            = "replace_test",
     .instance_size          = sizeof(BDRVReplaceTestState),
+    .supports_backing       = true,
 
     .bdrv_close             = bdrv_replace_test_close,
     .bdrv_co_preadv         = bdrv_replace_test_co_preadv,
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

bdrv_pass_through is used as filter, even all node variables has
corresponding names. We want to append it, so it should be
backing-child-based filter like mirror_top.
So, in test_update_perm_tree, first child should be DATA, as we don't
want filters with two filtered children.

bdrv_exclusive_writer is used as a filter once. So it should be filter
anyway. We want to append it, so it should be backing-child-based
fitler too.

Make all FILTERED children to be PRIMARY as well. We are going to force
this rule by assertion soon.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-7-vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h |  5 +++--
 tests/unit/test-bdrv-graph-mod.c | 24 +++++++++++++++++-------
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BlockDriver {
     /*
      * Only make sense for filter drivers, for others must be false.
      * If true, filtered child is bs->backing. Otherwise it's bs->file.
-     * Only two internal filters use bs->backing as filtered child and has this
-     * field set to true: mirror_top and commit_top.
+     * Two internal filters use bs->backing as filtered child and has this
+     * field set to true: mirror_top and commit_top. There also two such test
+     * filters in tests/unit/test-bdrv-graph-mod.c.
      *
      * Never create any more such filters!
      *
diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -XXX,XX +XXX,XX @@
 
 static BlockDriver bdrv_pass_through = {
     .format_name = "pass-through",
+    .is_filter = true,
+    .filtered_child_is_backing = true,
     .bdrv_child_perm = bdrv_default_perms,
 };
 
@@ -XXX,XX +XXX,XX @@ static void exclusive_write_perms(BlockDriverState *bs, BdrvChild *c,
 
 static BlockDriver bdrv_exclusive_writer = {
     .format_name = "exclusive-writer",
+    .is_filter = true,
+    .filtered_child_is_backing = true,
     .bdrv_child_perm = exclusive_write_perms,
 };
 
@@ -XXX,XX +XXX,XX @@ static void test_update_perm_tree(void)
     blk_insert_bs(root, bs, &error_abort);
 
     bdrv_attach_child(filter, bs, "child", &child_of_bds,
-                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, &error_abort);
+                      BDRV_CHILD_DATA, &error_abort);
 
     ret = bdrv_append(filter, bs, NULL);
     g_assert_cmpint(ret, <, 0);
@@ -XXX,XX +XXX,XX @@ static void test_parallel_exclusive_write(void)
      */
     bdrv_ref(base);
 
-    bdrv_attach_child(top, fl1, "backing", &child_of_bds, BDRV_CHILD_DATA,
+    bdrv_attach_child(top, fl1, "backing", &child_of_bds,
+                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
-    bdrv_attach_child(fl1, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
+    bdrv_attach_child(fl1, base, "backing", &child_of_bds,
+                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
-    bdrv_attach_child(fl2, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
+    bdrv_attach_child(fl2, base, "backing", &child_of_bds,
+                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
 
     bdrv_replace_node(fl1, fl2, &error_abort);
@@ -XXX,XX +XXX,XX @@ static void test_parallel_perm_update(void)
                               BDRV_CHILD_DATA, &error_abort);
     c_fl2 = bdrv_attach_child(ws, fl2, "second", &child_of_bds,
                               BDRV_CHILD_DATA, &error_abort);
-    bdrv_attach_child(fl1, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
+    bdrv_attach_child(fl1, base, "backing", &child_of_bds,
+                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
-    bdrv_attach_child(fl2, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
+    bdrv_attach_child(fl2, base, "backing", &child_of_bds,
+                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
 
     /* Select fl1 as first child to be active */
@@ -XXX,XX +XXX,XX @@ static void test_append_greedy_filter(void)
     BlockDriverState *base = no_perm_node("base");
     BlockDriverState *fl = exclusive_writer_node("fl1");
 
-    bdrv_attach_child(top, base, "backing", &child_of_bds, BDRV_CHILD_COW,
+    bdrv_attach_child(top, base, "backing", &child_of_bds,
+                      BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
 
     bdrv_append(fl, base, &error_abort);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Make the informal rules formal. In further commit we'll add
corresponding assertions.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-8-vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-common.h | 39 ++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/include/block/block-common.h b/include/block/block-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -XXX,XX +XXX,XX @@ enum {
  *
  * At least one of DATA, METADATA, FILTERED, or COW must be set for
  * every child.
+ *
+ *
+ * = Connection with bs->children, bs->file and bs->backing fields =
+ *
+ * 1. Filters
+ *
+ * Filter drivers have drv->is_filter = true.
+ *
+ * Filter node has exactly one FILTERED|PRIMARY child, and may have other
+ * children which must not have these bits (one example is the
+ * copy-before-write filter, which also has its target DATA child).
+ *
+ * Filter nodes never have COW children.
+ *
+ * For most filters, the filtered child is linked in bs->file, bs->backing is
+ * NULL.  For some filters (as an exception), it is the other way around; those
+ * drivers will have drv->filtered_child_is_backing set to true (see that
+ * field’s documentation for what drivers this concerns)
+ *
+ * 2. "raw" driver (block/raw-format.c)
+ *
+ * Formally it's not a filter (drv->is_filter = false)
+ *
+ * bs->backing is always NULL
+ *
+ * Only has one child, linked in bs->file. Its role is either FILTERED|PRIMARY
+ * (like filter) or DATA|PRIMARY depending on options.
+ *
+ * 3. Other drivers
+ *
+ * Don't have any FILTERED children.
+ *
+ * May have at most one COW child. In this case it's linked in bs->backing.
+ * Otherwise bs->backing is NULL. COW child is never PRIMARY.
+ *
+ * May have at most one PRIMARY child. In this case it's linked in bs->file.
+ * Otherwise bs->file is NULL.
+ *
+ * May also have some other children that don't have the PRIMARY or COW bit set.
  */
 enum BdrvChildRoleBits {
     /*
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Actually what we chose is a primary child. Let's stress it in the code.

We are going to drop indirect pointer logic here in future. Actually
this commit simplifies the future work: we drop use of indirection in
the assertion now.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-9-vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/snapshot.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index XXXXXXX..XXXXXXX 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -XXX,XX +XXX,XX @@ bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
 static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs)
 {
     BdrvChild **fallback;
-    BdrvChild *child;
+    BdrvChild *child = bdrv_primary_child(bs);
 
-    /*
-     * The only BdrvChild pointers that are safe to modify (and which
-     * we can thus return a reference to) are bs->file and
-     * bs->backing.
-     */
-    fallback = &bs->file;
-    if (!*fallback && bs->drv && bs->drv->is_filter) {
-        fallback = &bs->backing;
-    }
-
-    if (!*fallback) {
+    /* We allow fallback only to primary child */
+    if (!child) {
         return NULL;
     }
+    fallback = (child == bs->file ? &bs->file : &bs->backing);
+    assert(*fallback == child);
 
     /*
      * Check that there are no other children that would need to be
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
         }
 
         /*
-         * fallback_ptr is &bs->file or &bs->backing.  *fallback_ptr
-         * was closed above and set to NULL, but the .bdrv_open() call
-         * has opened it again, because we set the respective option
-         * (with the qdict_put_str() call above).
-         * Assert that .bdrv_open() has attached some child on
-         * *fallback_ptr, and that it has attached the one we wanted
-         * it to (i.e., fallback_bs).
+         * fallback was a primary child. It was closed above and set to NULL,
+         * but the .bdrv_open() call has opened it again, because we set the
+         * respective option (with the qdict_put_str() call above).
+         * Assert that .bdrv_open() has attached the right BDS as primary child.
          */
-        assert(*fallback_ptr && fallback_bs == (*fallback_ptr)->bs);
+        assert(bdrv_primary_bs(bs) == fallback_bs);
         bdrv_unref(fallback_bs);
         return ret;
     }
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

We are going to reimplement this behavior (clear bs->file / bs->backing
pointers automatically when child->bs is cleared) in a nicer way, see
further commit
"block: Manipulate bs->file / bs->backing pointers in .attach/.detach".

With this revert we bring back a problem that was fixed by b0a9f6fed3d8.
Still the problem was mostly theoretical, we don't have concrete bugs
fixed by b0a9f6fed3d8, we don't have a specific test. Probably some
accidental failures of iotests are related.

Alternatively, we may merge this and following three reverts into final
"block: Manipulate ..." to avoid any kind of regression. But seems that
in this case having separate clear revert commits is better.

This reverts commit b0a9f6fed3d80de610dcd04a7e66f9f30a04174f.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-10-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 102 +++++++++++++-------------------------------------------
 1 file changed, 23 insertions(+), 79 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
 static bool bdrv_recurse_has_child(BlockDriverState *bs,
                                    BlockDriverState *child);
 
-static void bdrv_child_free(BdrvChild *child);
 static void bdrv_replace_child_noperm(BdrvChild **child,
-                                      BlockDriverState *new_bs,
-                                      bool free_empty_child);
+                                      BlockDriverState *new_bs);
 static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
                                               BdrvChild *child,
                                               Transaction *tran);
@@ -XXX,XX +XXX,XX @@ typedef struct BdrvReplaceChildState {
     BdrvChild *child;
     BdrvChild **childp;
     BlockDriverState *old_bs;
-    bool free_empty_child;
 } BdrvReplaceChildState;
 
 static void bdrv_replace_child_commit(void *opaque)
@@ -XXX,XX +XXX,XX @@ static void bdrv_replace_child_commit(void *opaque)
     BdrvReplaceChildState *s = opaque;
     GLOBAL_STATE_CODE();
 
-    if (s->free_empty_child && !s->child->bs) {
-        bdrv_child_free(s->child);
-    }
     bdrv_unref(s->old_bs);
 }
 
@@ -XXX,XX +XXX,XX @@ static void bdrv_replace_child_abort(void *opaque)
      *     modify the BdrvChild * pointer we indirectly pass to it, i.e. it
      *     will not modify s->child.  From that perspective, it does not matter
      *     whether we pass s->childp or &s->child.
+     *     (TODO: Right now, bdrv_replace_child_noperm() never modifies that
+     *     pointer anyway (though it will in the future), so at this point it
+     *     absolutely does not matter whether we pass s->childp or &s->child.)
      * (2) If new_bs is not NULL, s->childp will be NULL.  We then cannot use
      *     it here.
      * (3) If new_bs is NULL, *s->childp will have been NULLed by
      *     bdrv_replace_child_tran()'s bdrv_replace_child_noperm() call, and we
      *     must not pass a NULL *s->childp here.
+     *     (TODO: In its current state, bdrv_replace_child_noperm() will not
+     *     have NULLed *s->childp, so this does not apply yet.  It will in the
+     *     future.)
      *
      * So whether new_bs was NULL or not, we cannot pass s->childp here; and in
      * any case, there is no reason to pass it anyway.
      */
-    bdrv_replace_child_noperm(&s->child, s->old_bs, true);
-    /*
-     * The child was pre-existing, so s->old_bs must be non-NULL, and
-     * s->child thus must not have been freed
-     */
-    assert(s->child != NULL);
-    if (!new_bs) {
-        /* As described above, *s->childp was cleared, so restore it */
-        assert(s->childp != NULL);
-        *s->childp = s->child;
-    }
+    bdrv_replace_child_noperm(&s->child, s->old_bs);
     bdrv_unref(new_bs);
 }
 
@@ -XXX,XX +XXX,XX @@ static TransactionActionDrv bdrv_replace_child_drv = {
  *
  * The function doesn't update permissions, caller is responsible for this.
  *
- * (*childp)->bs must not be NULL.
- *
  * Note that if new_bs == NULL, @childp is stored in a state object attached
  * to @tran, so that the old child can be reinstated in the abort handler.
  * Therefore, if @new_bs can be NULL, @childp must stay valid until the
  * transaction is committed or aborted.
  *
- * If @free_empty_child is true and @new_bs is NULL, the BdrvChild is
- * freed (on commit).  @free_empty_child should only be false if the
- * caller will free the BDrvChild themselves (which may be important
- * if this is in turn called in another transactional context).
+ * (TODO: The reinstating does not happen yet, but it will once
+ * bdrv_replace_child_noperm() NULLs *childp when new_bs is NULL.)
  */
 static void bdrv_replace_child_tran(BdrvChild **childp,
                                     BlockDriverState *new_bs,
-                                    Transaction *tran,
-                                    bool free_empty_child)
+                                    Transaction *tran)
 {
     BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
     *s = (BdrvReplaceChildState) {
         .child = *childp,
         .childp = new_bs == NULL ? childp : NULL,
         .old_bs = (*childp)->bs,
-        .free_empty_child = free_empty_child,
     };
     tran_add(tran, &bdrv_replace_child_drv, s);
 
-    /* The abort handler relies on this */
-    assert(s->old_bs != NULL);
-
     if (new_bs) {
         bdrv_ref(new_bs);
     }
-    /*
-     * Pass free_empty_child=false, we will free the child (if
-     * necessary) in bdrv_replace_child_commit() (if our
-     * @free_empty_child parameter was true).
-     */
-    bdrv_replace_child_noperm(childp, new_bs, false);
+    bdrv_replace_child_noperm(childp, new_bs);
     /* old_bs reference is transparently moved from *childp to @s */
 }
 
@@ -XXX,XX +XXX,XX @@ uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
     return permissions[qapi_perm];
 }
 
-/**
- * Replace (*childp)->bs by @new_bs.
- *
- * If @new_bs is NULL, *childp will be set to NULL, too: BDS parents
- * generally cannot handle a BdrvChild with .bs == NULL, so clearing
- * BdrvChild.bs should generally immediately be followed by the
- * BdrvChild pointer being cleared as well.
- *
- * If @free_empty_child is true and @new_bs is NULL, the BdrvChild is
- * freed.  @free_empty_child should only be false if the caller will
- * free the BdrvChild themselves (this may be important in a
- * transactional context, where it may only be freed on commit).
- */
 static void bdrv_replace_child_noperm(BdrvChild **childp,
-                                      BlockDriverState *new_bs,
-                                      bool free_empty_child)
+                                      BlockDriverState *new_bs)
 {
     BdrvChild *child = *childp;
     BlockDriverState *old_bs = child->bs;
@@ -XXX,XX +XXX,XX @@ static void bdrv_replace_child_noperm(BdrvChild **childp,
     }
 
     child->bs = new_bs;
-    if (!new_bs) {
-        *childp = NULL;
-    }
 
     if (new_bs) {
         assert_bdrv_graph_writable(new_bs);
@@ -XXX,XX +XXX,XX @@ static void bdrv_replace_child_noperm(BdrvChild **childp,
         bdrv_parent_drained_end_single(child);
         drain_saldo++;
     }
-
-    if (free_empty_child && !child->bs) {
-        bdrv_child_free(child);
-    }
 }
 
 /**
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_child_common_abort(void *opaque)
     BlockDriverState *bs = child->bs;
 
     GLOBAL_STATE_CODE();
-    /*
-     * Pass free_empty_child=false, because we still need the child
-     * for the AioContext operations on the parent below; those
-     * BdrvChildClass methods all work on a BdrvChild object, so we
-     * need to keep it as an empty shell (after this function, it will
-     * not be attached to any parent, and it will not have a .bs).
-     */
-    bdrv_replace_child_noperm(s->child, NULL, false);
+    bdrv_replace_child_noperm(s->child, NULL);
 
     if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
         bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort);
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_child_common_abort(void *opaque)
 
     bdrv_unref(bs);
     bdrv_child_free(child);
+    *s->child = NULL;
 }
 
 static TransactionActionDrv bdrv_attach_child_common_drv = {
@@ -XXX,XX +XXX,XX @@ static int bdrv_attach_child_common(BlockDriverState *child_bs,
     }
 
     bdrv_ref(child_bs);
-    bdrv_replace_child_noperm(&new_child, child_bs, true);
-    /* child_bs was non-NULL, so new_child must not have been freed */
-    assert(new_child != NULL);
+    bdrv_replace_child_noperm(&new_child, child_bs);
 
     *child = new_child;
 
@@ -XXX,XX +XXX,XX @@ static void bdrv_detach_child(BdrvChild **childp)
     BlockDriverState *old_bs = (*childp)->bs;
 
     GLOBAL_STATE_CODE();
-    bdrv_replace_child_noperm(childp, NULL, true);
+    bdrv_replace_child_noperm(childp, NULL);
+    bdrv_child_free(*childp);
 
     if (old_bs) {
         /*
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
     }
 
     if (child->bs) {
-        /*
-         * Pass free_empty_child=false, we will free the child in
-         * bdrv_remove_filter_or_cow_child_commit()
-         */
-        bdrv_replace_child_tran(childp, NULL, tran, false);
+        bdrv_replace_child_tran(childp, NULL, tran);
     }
 
     s = g_new(BdrvRemoveFilterOrCowChild, 1);
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
         .is_backing = (childp == &bs->backing),
     };
     tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
+
+    *childp = NULL;
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
          * Passing a pointer to the local variable @c is fine here, because
          * @to is not NULL, and so &c will not be attached to the transaction.
          */
-        bdrv_replace_child_tran(&c, to, tran, true);
+        bdrv_replace_child_tran(&c, to, tran);
     }
 
     return 0;
@@ -XXX,XX +XXX,XX @@ int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
     bdrv_drained_begin(old_bs);
     bdrv_drained_begin(new_bs);
 
-    bdrv_replace_child_tran(&child, new_bs, tran, true);
-    /* @new_bs must have been non-NULL, so @child must not have been freed */
-    assert(child != NULL);
+    bdrv_replace_child_tran(&child, new_bs, tran);
 
     found = g_hash_table_new(NULL, NULL);
     refresh_list = bdrv_topological_dfs(refresh_list, found, old_bs);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

That's a preparation to previously reverted
"block: Let replace_child_noperm free children". Drop it too, we don't
need it for a new approach.

This reverts commit 82b54cf51656bf3cd5ed1ac549e8a1085a0e3290.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-11-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 81 +++++++--------------------------------------------------
 1 file changed, 10 insertions(+), 71 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm,
 
 typedef struct BdrvReplaceChildState {
     BdrvChild *child;
-    BdrvChild **childp;
     BlockDriverState *old_bs;
 } BdrvReplaceChildState;
 
@@ -XXX,XX +XXX,XX @@ static void bdrv_replace_child_abort(void *opaque)
     BlockDriverState *new_bs = s->child->bs;
 
     GLOBAL_STATE_CODE();
-    /*
-     * old_bs reference is transparently moved from @s to s->child.
-     *
-     * Pass &s->child here instead of s->childp, because:
-     * (1) s->old_bs must be non-NULL, so bdrv_replace_child_noperm() will not
-     *     modify the BdrvChild * pointer we indirectly pass to it, i.e. it
-     *     will not modify s->child.  From that perspective, it does not matter
-     *     whether we pass s->childp or &s->child.
-     *     (TODO: Right now, bdrv_replace_child_noperm() never modifies that
-     *     pointer anyway (though it will in the future), so at this point it
-     *     absolutely does not matter whether we pass s->childp or &s->child.)
-     * (2) If new_bs is not NULL, s->childp will be NULL.  We then cannot use
-     *     it here.
-     * (3) If new_bs is NULL, *s->childp will have been NULLed by
-     *     bdrv_replace_child_tran()'s bdrv_replace_child_noperm() call, and we
-     *     must not pass a NULL *s->childp here.
-     *     (TODO: In its current state, bdrv_replace_child_noperm() will not
-     *     have NULLed *s->childp, so this does not apply yet.  It will in the
-     *     future.)
-     *
-     * So whether new_bs was NULL or not, we cannot pass s->childp here; and in
-     * any case, there is no reason to pass it anyway.
-     */
+    /* old_bs reference is transparently moved from @s to @s->child */
     bdrv_replace_child_noperm(&s->child, s->old_bs);
     bdrv_unref(new_bs);
 }
@@ -XXX,XX +XXX,XX @@ static TransactionActionDrv bdrv_replace_child_drv = {
  * Note: real unref of old_bs is done only on commit.
  *
  * The function doesn't update permissions, caller is responsible for this.
- *
- * Note that if new_bs == NULL, @childp is stored in a state object attached
- * to @tran, so that the old child can be reinstated in the abort handler.
- * Therefore, if @new_bs can be NULL, @childp must stay valid until the
- * transaction is committed or aborted.
- *
- * (TODO: The reinstating does not happen yet, but it will once
- * bdrv_replace_child_noperm() NULLs *childp when new_bs is NULL.)
  */
-static void bdrv_replace_child_tran(BdrvChild **childp,
-                                    BlockDriverState *new_bs,
+static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
                                     Transaction *tran)
 {
     BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
     *s = (BdrvReplaceChildState) {
-        .child = *childp,
-        .childp = new_bs == NULL ? childp : NULL,
-        .old_bs = (*childp)->bs,
+        .child = child,
+        .old_bs = child->bs,
     };
     tran_add(tran, &bdrv_replace_child_drv, s);
 
     if (new_bs) {
         bdrv_ref(new_bs);
     }
-    bdrv_replace_child_noperm(childp, new_bs);
-    /* old_bs reference is transparently moved from *childp to @s */
+    bdrv_replace_child_noperm(&child, new_bs);
+    /* old_bs reference is transparently moved from @child to @s */
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to)
 
 typedef struct BdrvRemoveFilterOrCowChild {
     BdrvChild *child;
-    BlockDriverState *bs;
     bool is_backing;
 } BdrvRemoveFilterOrCowChild;
 
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_filter_or_cow_child_commit(void *opaque)
     bdrv_child_free(s->child);
 }
 
-static void bdrv_remove_filter_or_cow_child_clean(void *opaque)
-{
-    BdrvRemoveFilterOrCowChild *s = opaque;
-
-    /* Drop the bs reference after the transaction is done */
-    bdrv_unref(s->bs);
-    g_free(s);
-}
-
 static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = {
     .abort = bdrv_remove_filter_or_cow_child_abort,
     .commit = bdrv_remove_filter_or_cow_child_commit,
-    .clean = bdrv_remove_filter_or_cow_child_clean,
+    .clean = g_free,
 };
 
 /*
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
         return;
     }
 
-    /*
-     * Keep a reference to @bs so @childp will stay valid throughout the
-     * transaction (required by bdrv_replace_child_tran())
-     */
-    bdrv_ref(bs);
     if (child == bs->backing) {
         childp = &bs->backing;
     } else if (child == bs->file) {
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
     }
 
     if (child->bs) {
-        bdrv_replace_child_tran(childp, NULL, tran);
+        bdrv_replace_child_tran(*childp, NULL, tran);
     }
 
     s = g_new(BdrvRemoveFilterOrCowChild, 1);
     *s = (BdrvRemoveFilterOrCowChild) {
         .child = child,
-        .bs = bs,
         .is_backing = (childp == &bs->backing),
     };
     tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
@@ -XXX,XX +XXX,XX @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
 {
     BdrvChild *c, *next;
 
-    assert(to != NULL);
     GLOBAL_STATE_CODE();
 
     QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
@@ -XXX,XX +XXX,XX @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
                        c->name, from->node_name);
             return -EPERM;
         }
-
-        /*
-         * Passing a pointer to the local variable @c is fine here, because
-         * @to is not NULL, and so &c will not be attached to the transaction.
-         */
-        bdrv_replace_child_tran(&c, to, tran);
+        bdrv_replace_child_tran(c, to, tran);
     }
 
     return 0;
@@ -XXX,XX +XXX,XX @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
  *
  * With @detach_subchain=true @to must be in a backing chain of @from. In this
  * case backing link of the cow-parent of @to is removed.
- *
- * @to must not be NULL.
  */
 static int bdrv_replace_node_common(BlockDriverState *from,
                                     BlockDriverState *to,
@@ -XXX,XX +XXX,XX @@ static int bdrv_replace_node_common(BlockDriverState *from,
     int ret;
 
     GLOBAL_STATE_CODE();
-    assert(to != NULL);
 
     if (detach_subchain) {
         assert(bdrv_chain_contains(from, to));
@@ -XXX,XX +XXX,XX @@ out:
     return ret;
 }
 
-/**
- * Replace node @from by @to (where neither may be NULL).
- */
 int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
                       Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
     bdrv_drained_begin(old_bs);
     bdrv_drained_begin(new_bs);
 
-    bdrv_replace_child_tran(&child, new_bs, tran);
+    bdrv_replace_child_tran(child, new_bs, tran);
 
     found = g_hash_table_new(NULL, NULL);
     refresh_list = bdrv_topological_dfs(refresh_list, found, old_bs);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

That's a preparation to previously reverted
"block: Let replace_child_noperm free children". Drop it too, we don't
need it for a new approach.

This reverts commit 562bda8bb41879eeda0bd484dd3d55134579b28e.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-12-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
                                               BdrvChild *child,
                                               Transaction *tran)
 {
-    BdrvChild **childp;
     BdrvRemoveFilterOrCowChild *s;
 
+    assert(child == bs->backing || child == bs->file);
+
     if (!child) {
         return;
     }
 
-    if (child == bs->backing) {
-        childp = &bs->backing;
-    } else if (child == bs->file) {
-        childp = &bs->file;
-    } else {
-        g_assert_not_reached();
-    }
-
     if (child->bs) {
-        bdrv_replace_child_tran(*childp, NULL, tran);
+        bdrv_replace_child_tran(child, NULL, tran);
     }
 
     s = g_new(BdrvRemoveFilterOrCowChild, 1);
     *s = (BdrvRemoveFilterOrCowChild) {
         .child = child,
-        .is_backing = (childp == &bs->backing),
+        .is_backing = (child == bs->backing),
     };
     tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
 
-    *childp = NULL;
+    if (s->is_backing) {
+        bs->backing = NULL;
+    } else {
+        bs->file = NULL;
+    }
 }
 
 /*
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

That's a preparation to previously reverted
"block: Let replace_child_noperm free children". Drop it too, we don't
need it for a new approach.

This reverts commit be64bbb0149748f3999c49b13976aafb8330ea86.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-13-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

bs->file and bs->backing are a kind of duplication of part of
bs->children. But very useful diplication, so let's not drop them at
all:)

We should manage bs->file and bs->backing in same place, where we
manage bs->children, to keep them in sync.

Moreover, generic io paths are unprepared to BdrvChild without a bs, so
it's double good to clear bs->file / bs->backing when we detach the
child.

Detach is simple: if we detach bs->file or bs->backing child, just
set corresponding field to NULL.

Attach is a bit more complicated. But we still can precisely detect
should we set one of bs->file / bs->backing or not:

- if role is BDRV_CHILD_COW, we definitely deal with bs->backing
- else, if role is BDRV_CHILD_FILTERED (it must be also
  BDRV_CHILD_PRIMARY), it's a filtered child. Use
  bs->drv->filtered_child_is_backing to chose the pointer field to
  modify.
- else, if role is BDRV_CHILD_PRIMARY, we deal with bs->file
- in all other cases, it's neither bs->backing nor bs->file. It's some
  other child and we shouldn't care

OK. This change brings one more good thing: we can (and should) get rid
of all indirect pointers in the block-graph-change transactions:

bdrv_attach_child_common() stores BdrvChild** into transaction to clear
it on abort.

bdrv_attach_child_common() has two callers: bdrv_attach_child_noperm()
just pass-through this feature, bdrv_root_attach_child() doesn't need
the feature.

Look at bdrv_attach_child_noperm() callers:
  - bdrv_attach_child() doesn't need the feature
  - bdrv_set_file_or_backing_noperm() uses the feature to manage
    bs->file and bs->backing, we don't want it anymore
  - bdrv_append() uses the feature to manage bs->backing, again we
    don't want it anymore

So, we should drop this stuff! Great!

We could probably keep BdrvChild** argument to keep the int return
value, but it seems not worth the complexity.

Finally, we now set .file / .backing automatically in generic code and
want to restring setting them by hand outside of .attach/.detach.
So, this patch cleanups all remaining places where they were set.
To find such places I use:

git grep '\->file ='
  git grep '\->backing ='
  git grep '&.*\<backing\>'
  git grep '&.*\<file\>'

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-14-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h |  15 +-
 block.c                          | 234 ++++++++++++++-----------------
 block/raw-format.c               |   4 +-
 block/snapshot-access.c          |   6 +-
 block/snapshot.c                 |   1 -
 tests/unit/test-bdrv-drain.c     |  10 +-
 6 files changed, 126 insertions(+), 144 deletions(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BlockDriverState {
     QDict *full_open_options;
     char exact_filename[PATH_MAX];
 
-    BdrvChild *backing;
-    BdrvChild *file;
-
     /* I/O Limits */
     BlockLimits bl;
 
@@ -XXX,XX +XXX,XX @@ struct BlockDriverState {
      * parent node of this node.
      */
     BlockDriverState *inherits_from;
+
+    /*
+     * @backing and @file are some of @children or NULL. All these three fields
+     * (@file, @backing and @children) are modified only in
+     * bdrv_child_cb_attach() and bdrv_child_cb_detach().
+     *
+     * See also comment in include/block/block.h, to learn how backing and file
+     * are connected with BdrvChildRole.
+     */
     QLIST_HEAD(, BdrvChild) children;
+    BdrvChild *backing;
+    BdrvChild *file;
+
     QLIST_HEAD(, BdrvChild) parents;
 
     QDict *options;
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_child_cb_attach(BdrvChild *child)
 
     assert_bdrv_graph_writable(bs);
     QLIST_INSERT_HEAD(&bs->children, child, next);
-
-    if (child->role & BDRV_CHILD_COW) {
+    if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) {
+        /*
+         * Here we handle filters and block/raw-format.c when it behave like
+         * filter. They generally have a single PRIMARY child, which is also the
+         * FILTERED child, and that they may have multiple more children, which
+         * are neither PRIMARY nor FILTERED. And never we have a COW child here.
+         * So bs->file will be the PRIMARY child, unless the PRIMARY child goes
+         * into bs->backing on exceptional cases; and bs->backing will be
+         * nothing else.
+         */
+        assert(!(child->role & BDRV_CHILD_COW));
+        if (child->role & BDRV_CHILD_PRIMARY) {
+            assert(child->role & BDRV_CHILD_FILTERED);
+            assert(!bs->backing);
+            assert(!bs->file);
+
+            if (bs->drv->filtered_child_is_backing) {
+                bs->backing = child;
+            } else {
+                bs->file = child;
+            }
+        } else {
+            assert(!(child->role & BDRV_CHILD_FILTERED));
+        }
+    } else if (child->role & BDRV_CHILD_COW) {
+        assert(bs->drv->supports_backing);
+        assert(!(child->role & BDRV_CHILD_PRIMARY));
+        assert(!bs->backing);
+        bs->backing = child;
         bdrv_backing_attach(child);
+    } else if (child->role & BDRV_CHILD_PRIMARY) {
+        assert(!bs->file);
+        bs->file = child;
     }
 
     bdrv_apply_subtree_drain(child, bs);
@@ -XXX,XX +XXX,XX @@ static void bdrv_child_cb_detach(BdrvChild *child)
 
     assert_bdrv_graph_writable(bs);
     QLIST_REMOVE(child, next);
+    if (child == bs->backing) {
+        assert(child != bs->file);
+        bs->backing = NULL;
+    } else if (child == bs->file) {
+        bs->file = NULL;
+    }
 }
 
 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
@@ -XXX,XX +XXX,XX @@ open_failed:
     bs->drv = NULL;
     if (bs->file != NULL) {
         bdrv_unref_child(bs, bs->file);
-        bs->file = NULL;
+        assert(!bs->file);
     }
     g_free(bs->opaque);
     bs->opaque = NULL;
@@ -XXX,XX +XXX,XX @@ static void bdrv_child_free(BdrvChild *child)
 }
 
 typedef struct BdrvAttachChildCommonState {
-    BdrvChild **child;
+    BdrvChild *child;
     AioContext *old_parent_ctx;
     AioContext *old_child_ctx;
 } BdrvAttachChildCommonState;
@@ -XXX,XX +XXX,XX @@ typedef struct BdrvAttachChildCommonState {
 static void bdrv_attach_child_common_abort(void *opaque)
 {
     BdrvAttachChildCommonState *s = opaque;
-    BdrvChild *child = *s->child;
-    BlockDriverState *bs = child->bs;
+    BlockDriverState *bs = s->child->bs;
 
     GLOBAL_STATE_CODE();
-    bdrv_replace_child_noperm(child, NULL);
+    bdrv_replace_child_noperm(s->child, NULL);
 
     if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
         bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort);
     }
 
-    if (bdrv_child_get_parent_aio_context(child) != s->old_parent_ctx) {
+    if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) {
         GSList *ignore;
 
         /* No need to ignore `child`, because it has been detached already */
         ignore = NULL;
-        child->klass->can_set_aio_ctx(child, s->old_parent_ctx, &ignore,
-                                      &error_abort);
+        s->child->klass->can_set_aio_ctx(s->child, s->old_parent_ctx, &ignore,
+                                         &error_abort);
         g_slist_free(ignore);
 
         ignore = NULL;
-        child->klass->set_aio_ctx(child, s->old_parent_ctx, &ignore);
+        s->child->klass->set_aio_ctx(s->child, s->old_parent_ctx, &ignore);
         g_slist_free(ignore);
     }
 
     bdrv_unref(bs);
-    bdrv_child_free(child);
-    *s->child = NULL;
+    bdrv_child_free(s->child);
 }
 
 static TransactionActionDrv bdrv_attach_child_common_drv = {
@@ -XXX,XX +XXX,XX @@ static TransactionActionDrv bdrv_attach_child_common_drv = {
 /*
  * Common part of attaching bdrv child to bs or to blk or to job
  *
- * Resulting new child is returned through @child.
- * At start *@child must be NULL.
- * @child is saved to a new entry of @tran, so that *@child could be reverted to
- * NULL on abort(). So referenced variable must live at least until transaction
- * end.
- *
  * Function doesn't update permissions, caller is responsible for this.
+ *
+ * Returns new created child.
  */
-static int bdrv_attach_child_common(BlockDriverState *child_bs,
-                                    const char *child_name,
-                                    const BdrvChildClass *child_class,
-                                    BdrvChildRole child_role,
-                                    uint64_t perm, uint64_t shared_perm,
-                                    void *opaque, BdrvChild **child,
-                                    Transaction *tran, Error **errp)
+static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
+                                           const char *child_name,
+                                           const BdrvChildClass *child_class,
+                                           BdrvChildRole child_role,
+                                           uint64_t perm, uint64_t shared_perm,
+                                           void *opaque,
+                                           Transaction *tran, Error **errp)
 {
     BdrvChild *new_child;
     AioContext *parent_ctx;
     AioContext *child_ctx = bdrv_get_aio_context(child_bs);
 
-    assert(child);
-    assert(*child == NULL);
     assert(child_class->get_parent_desc);
     GLOBAL_STATE_CODE();
 
@@ -XXX,XX +XXX,XX @@ static int bdrv_attach_child_common(BlockDriverState *child_bs,
         if (ret < 0) {
             error_propagate(errp, local_err);
             bdrv_child_free(new_child);
-            return ret;
+            return NULL;
         }
     }
 
     bdrv_ref(child_bs);
     bdrv_replace_child_noperm(new_child, child_bs);
 
-    *child = new_child;
-
     BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
     *s = (BdrvAttachChildCommonState) {
-        .child = child,
+        .child = new_child,
         .old_parent_ctx = parent_ctx,
         .old_child_ctx = child_ctx,
     };
     tran_add(tran, &bdrv_attach_child_common_drv, s);
 
-    return 0;
+    return new_child;
 }
 
 /*
- * Variable referenced by @child must live at least until transaction end.
- * (see bdrv_attach_child_common() doc for details)
- *
  * Function doesn't update permissions, caller is responsible for this.
  */
-static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
-                                    BlockDriverState *child_bs,
-                                    const char *child_name,
-                                    const BdrvChildClass *child_class,
-                                    BdrvChildRole child_role,
-                                    BdrvChild **child,
-                                    Transaction *tran,
-                                    Error **errp)
+static BdrvChild *bdrv_attach_child_noperm(BlockDriverState *parent_bs,
+                                           BlockDriverState *child_bs,
+                                           const char *child_name,
+                                           const BdrvChildClass *child_class,
+                                           BdrvChildRole child_role,
+                                           Transaction *tran,
+                                           Error **errp)
 {
-    int ret;
     uint64_t perm, shared_perm;
 
     assert(parent_bs->drv);
@@ -XXX,XX +XXX,XX @@ static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
     if (bdrv_recurse_has_child(child_bs, parent_bs)) {
         error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle",
                    child_bs->node_name, child_name, parent_bs->node_name);
-        return -EINVAL;
+        return NULL;
     }
 
     bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
     bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
                     perm, shared_perm, &perm, &shared_perm);
 
-    ret = bdrv_attach_child_common(child_bs, child_name, child_class,
-                                   child_role, perm, shared_perm, parent_bs,
-                                   child, tran, errp);
-    if (ret < 0) {
-        return ret;
-    }
-
-    return 0;
+    return bdrv_attach_child_common(child_bs, child_name, child_class,
+                                    child_role, perm, shared_perm, parent_bs,
+                                    tran, errp);
 }
 
 static void bdrv_detach_child(BdrvChild *child)
@@ -XXX,XX +XXX,XX @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
                                   void *opaque, Error **errp)
 {
     int ret;
-    BdrvChild *child = NULL;
+    BdrvChild *child;
     Transaction *tran = tran_new();
 
     GLOBAL_STATE_CODE();
 
-    ret = bdrv_attach_child_common(child_bs, child_name, child_class,
+    child = bdrv_attach_child_common(child_bs, child_name, child_class,
                                    child_role, perm, shared_perm, opaque,
-                                   &child, tran, errp);
-    if (ret < 0) {
+                                   tran, errp);
+    if (!child) {
+        ret = -EINVAL;
         goto out;
     }
 
@@ -XXX,XX +XXX,XX @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
 
 out:
     tran_finalize(tran, ret);
-    /* child is unset on failure by bdrv_attach_child_common_abort() */
-    assert((ret < 0) == !child);
 
     bdrv_unref(child_bs);
-    return child;
+
+    return ret < 0 ? NULL : child;
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
                              Error **errp)
 {
     int ret;
-    BdrvChild *child = NULL;
+    BdrvChild *child;
     Transaction *tran = tran_new();
 
     GLOBAL_STATE_CODE();
 
-    ret = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, child_class,
-                                   child_role, &child, tran, errp);
-    if (ret < 0) {
+    child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name,
+                                     child_class, child_role, tran, errp);
+    if (!child) {
+        ret = -EINVAL;
         goto out;
     }
 
@@ -XXX,XX +XXX,XX @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
 
 out:
     tran_finalize(tran, ret);
-    /* child is unset on failure by bdrv_attach_child_common_abort() */
-    assert((ret < 0) == !child);
 
     bdrv_unref(child_bs);
 
-    return child;
+    return ret < 0 ? NULL : child;
 }
 
 /* Callers must ensure that child->frozen is false. */
@@ -XXX,XX +XXX,XX @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
                                            bool is_backing,
                                            Transaction *tran, Error **errp)
 {
-    int ret = 0;
     bool update_inherits_from =
         bdrv_inherits_from_recursive(child_bs, parent_bs);
     BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file;
@@ -XXX,XX +XXX,XX @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
         goto out;
     }
 
-    ret = bdrv_attach_child_noperm(parent_bs, child_bs,
-                                   is_backing ? "backing" : "file",
-                                   &child_of_bds, role,
-                                   is_backing ? &parent_bs->backing :
-                                                &parent_bs->file,
-                                   tran, errp);
-    if (ret < 0) {
-        return ret;
+    child = bdrv_attach_child_noperm(parent_bs, child_bs,
+                                     is_backing ? "backing" : "file",
+                                     &child_of_bds, role,
+                                     tran, errp);
+    if (!child) {
+        return -EINVAL;
     }
 
 
@@ -XXX,XX +XXX,XX @@ int bdrv_open_file_child(const char *filename,
 
     /* commit_top and mirror_top don't use this function */
     assert(!parent->drv->filtered_child_is_backing);
-
     role = parent->drv->is_filter ?
         (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
 
-    parent->file = bdrv_open_child(filename, options, bdref_key, parent,
-                                   &child_of_bds, role, false, errp);
+    if (!bdrv_open_child(filename, options, bdref_key, parent,
+                         &child_of_bds, role, false, errp))
+    {
+        return -EINVAL;
+    }
 
-    return parent->file ? 0 : -EINVAL;
+    return 0;
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ static void bdrv_close(BlockDriverState *bs)
         bdrv_unref_child(bs, child);
     }
 
-    bs->backing = NULL;
-    bs->file = NULL;
+    assert(!bs->backing);
+    assert(!bs->file);
     g_free(bs->opaque);
     bs->opaque = NULL;
     qatomic_set(&bs->copy_on_read, 0);
@@ -XXX,XX +XXX,XX @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to)
     return ret;
 }
 
-typedef struct BdrvRemoveFilterOrCowChild {
-    BdrvChild *child;
-    bool is_backing;
-} BdrvRemoveFilterOrCowChild;
-
-static void bdrv_remove_filter_or_cow_child_abort(void *opaque)
-{
-    BdrvRemoveFilterOrCowChild *s = opaque;
-    BlockDriverState *parent_bs = s->child->opaque;
-
-    if (s->is_backing) {
-        parent_bs->backing = s->child;
-    } else {
-        parent_bs->file = s->child;
-    }
-
-    /*
-     * We don't have to restore child->bs here to undo bdrv_replace_child_tran()
-     * because that function is transactionable and it registered own completion
-     * entries in @tran, so .abort() for bdrv_replace_child_safe() will be
-     * called automatically.
-     */
-}
-
 static void bdrv_remove_filter_or_cow_child_commit(void *opaque)
 {
-    BdrvRemoveFilterOrCowChild *s = opaque;
     GLOBAL_STATE_CODE();
-    bdrv_child_free(s->child);
+    bdrv_child_free(opaque);
 }
 
 static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = {
-    .abort = bdrv_remove_filter_or_cow_child_abort,
     .commit = bdrv_remove_filter_or_cow_child_commit,
-    .clean = g_free,
 };
 
 /*
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
                                               BdrvChild *child,
                                               Transaction *tran)
 {
-    BdrvRemoveFilterOrCowChild *s;
-
     assert(child == bs->backing || child == bs->file);
 
     if (!child) {
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
         bdrv_replace_child_tran(child, NULL, tran);
     }
 
-    s = g_new(BdrvRemoveFilterOrCowChild, 1);
-    *s = (BdrvRemoveFilterOrCowChild) {
-        .child = child,
-        .is_backing = (child == bs->backing),
-    };
-    tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
-
-    if (s->is_backing) {
-        bs->backing = NULL;
-    } else {
-        bs->file = NULL;
-    }
+    tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, child);
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
                 Error **errp)
 {
     int ret;
+    BdrvChild *child;
     Transaction *tran = tran_new();
 
     GLOBAL_STATE_CODE();
 
     assert(!bs_new->backing);
 
-    ret = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
-                                   &child_of_bds, bdrv_backing_role(bs_new),
-                                   &bs_new->backing, tran, errp);
-    if (ret < 0) {
+    child = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
+                                     &child_of_bds, bdrv_backing_role(bs_new),
+                                     tran, errp);
+    if (!child) {
+        ret = -EINVAL;
         goto out;
     }
 
diff --git a/block/raw-format.c b/block/raw-format.c
index XXXXXXX..XXXXXXX 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -XXX,XX +XXX,XX @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
         file_role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               file_role, false, errp);
+    bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
+                    file_role, false, errp);
     if (!bs->file) {
         return -EINVAL;
     }
diff --git a/block/snapshot-access.c b/block/snapshot-access.c
index XXXXXXX..XXXXXXX 100644
--- a/block/snapshot-access.c
+++ b/block/snapshot-access.c
@@ -XXX,XX +XXX,XX @@ static void snapshot_access_refresh_filename(BlockDriverState *bs)
 static int snapshot_access_open(BlockDriverState *bs, QDict *options, int flags,
                                 Error **errp)
 {
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY,
-                               false, errp);
+    bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
+                    BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY,
+                    false, errp);
     if (!bs->file) {
         return -EINVAL;
     }
diff --git a/block/snapshot.c b/block/snapshot.c
index XXXXXXX..XXXXXXX 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
 
         /* .bdrv_open() will re-attach it */
         bdrv_unref_child(bs, *fallback_ptr);
-        *fallback_ptr = NULL;
 
         ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -XXX,XX +XXX,XX @@ static void test_drop_intermediate_poll(void)
     for (i = 0; i < 3; i++) {
         if (i) {
             /* Takes the reference to chain[i - 1] */
-            chain[i]->backing = bdrv_attach_child(chain[i], chain[i - 1],
-                                                  "chain", &chain_child_class,
-                                                  BDRV_CHILD_COW, &error_abort);
+            bdrv_attach_child(chain[i], chain[i - 1], "chain",
+                              &chain_child_class, BDRV_CHILD_COW, &error_abort);
         }
     }
 
@@ -XXX,XX +XXX,XX @@ static void do_test_replace_child_mid_drain(int old_drain_count,
     new_child_bs->total_sectors = 1;
 
     bdrv_ref(old_child_bs);
-    parent_bs->backing = bdrv_attach_child(parent_bs, old_child_bs, "child",
-                                           &child_of_bds, BDRV_CHILD_COW,
-                                           &error_abort);
+    bdrv_attach_child(parent_bs, old_child_bs, "child", &child_of_bds,
+                      BDRV_CHILD_COW, &error_abort);
 
     for (i = 0; i < old_drain_count; i++) {
         bdrv_drained_begin(old_child_bs);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Now the indirection is not actually used, we can safely reduce it to
simple pointer. For consistency do a bit of refactoring to get rid of
_ptr suffixes that become meaningless.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-15-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/snapshot.c | 38 ++++++++++++++++----------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index XXXXXXX..XXXXXXX 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -XXX,XX +XXX,XX @@ bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
 }
 
 /**
- * Return a pointer to the child BDS pointer to which we can fall
+ * Return a pointer to child of given BDS to which we can fall
  * back if the given BDS does not support snapshots.
  * Return NULL if there is no BDS to (safely) fall back to.
- *
- * We need to return an indirect pointer because bdrv_snapshot_goto()
- * has to modify the BdrvChild pointer.
  */
-static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs)
+static BdrvChild *bdrv_snapshot_fallback_child(BlockDriverState *bs)
 {
-    BdrvChild **fallback;
-    BdrvChild *child = bdrv_primary_child(bs);
+    BdrvChild *fallback = bdrv_primary_child(bs);
+    BdrvChild *child;
 
     /* We allow fallback only to primary child */
-    if (!child) {
+    if (!fallback) {
         return NULL;
     }
-    fallback = (child == bs->file ? &bs->file : &bs->backing);
-    assert(*fallback == child);
 
     /*
      * Check that there are no other children that would need to be
      * snapshotted.  If there are, it is not safe to fall back to
-     * *fallback.
+     * fallback.
      */
     QLIST_FOREACH(child, &bs->children, next) {
         if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
                            BDRV_CHILD_FILTERED) &&
-            child != *fallback)
+            child != fallback)
         {
             return NULL;
         }
@@ -XXX,XX +XXX,XX @@ static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs)
 
 static BlockDriverState *bdrv_snapshot_fallback(BlockDriverState *bs)
 {
-    BdrvChild **child_ptr = bdrv_snapshot_fallback_ptr(bs);
-    return child_ptr ? (*child_ptr)->bs : NULL;
+    return child_bs(bdrv_snapshot_fallback_child(bs));
 }
 
 int bdrv_can_snapshot(BlockDriverState *bs)
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
                        Error **errp)
 {
     BlockDriver *drv = bs->drv;
-    BdrvChild **fallback_ptr;
+    BdrvChild *fallback;
     int ret, open_ret;
 
     GLOBAL_STATE_CODE();
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
         return ret;
     }
 
-    fallback_ptr = bdrv_snapshot_fallback_ptr(bs);
-    if (fallback_ptr) {
+    fallback = bdrv_snapshot_fallback_child(bs);
+    if (fallback) {
         QDict *options;
         QDict *file_options;
         Error *local_err = NULL;
-        BlockDriverState *fallback_bs = (*fallback_ptr)->bs;
-        char *subqdict_prefix = g_strdup_printf("%s.", (*fallback_ptr)->name);
+        BlockDriverState *fallback_bs = fallback->bs;
+        char *subqdict_prefix = g_strdup_printf("%s.", fallback->name);
 
         options = qdict_clone_shallow(bs->options);
 
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
         qobject_unref(file_options);
         g_free(subqdict_prefix);
 
-        /* Force .bdrv_open() below to re-attach fallback_bs on *fallback_ptr */
-        qdict_put_str(options, (*fallback_ptr)->name,
+        /* Force .bdrv_open() below to re-attach fallback_bs on fallback */
+        qdict_put_str(options, fallback->name,
                       bdrv_get_node_name(fallback_bs));
 
         /* Now close bs, apply the snapshot on fallback_bs, and re-open bs */
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
         }
 
         /* .bdrv_open() will re-attach it */
-        bdrv_unref_child(bs, *fallback_ptr);
+        bdrv_unref_child(bs, fallback);
 
         ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
-- 
2.37.3

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Now the function can remove any child, so give it more common name.
Drop assertions and drop bs argument which becomes unused. Function
would be reused in a further commit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-16-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static bool bdrv_recurse_has_child(BlockDriverState *bs,
 
 static void bdrv_replace_child_noperm(BdrvChild *child,
                                       BlockDriverState *new_bs);
-static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
-                                              BdrvChild *child,
-                                              Transaction *tran);
+static void bdrv_remove_child(BdrvChild *child, Transaction *tran);
 static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs,
                                             Transaction *tran);
 
@@ -XXX,XX +XXX,XX @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
 
     if (child) {
         bdrv_unset_inherits_from(parent_bs, child, tran);
-        bdrv_remove_file_or_backing_child(parent_bs, child, tran);
+        bdrv_remove_child(child, tran);
     }
 
     if (!child_bs) {
@@ -XXX,XX +XXX,XX @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to)
     return ret;
 }
 
-static void bdrv_remove_filter_or_cow_child_commit(void *opaque)
+static void bdrv_remove_child_commit(void *opaque)
 {
     GLOBAL_STATE_CODE();
     bdrv_child_free(opaque);
 }
 
-static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = {
-    .commit = bdrv_remove_filter_or_cow_child_commit,
+static TransactionActionDrv bdrv_remove_child_drv = {
+    .commit = bdrv_remove_child_commit,
 };
 
-/*
- * A function to remove backing or file child of @bs.
- * Function doesn't update permissions, caller is responsible for this.
- */
-static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
-                                              BdrvChild *child,
-                                              Transaction *tran)
+/* Function doesn't update permissions, caller is responsible for this. */
+static void bdrv_remove_child(BdrvChild *child, Transaction *tran)
 {
-    assert(child == bs->backing || child == bs->file);
-
     if (!child) {
         return;
     }
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
         bdrv_replace_child_tran(child, NULL, tran);
     }
 
-    tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, child);
+    tran_add(tran, &bdrv_remove_child_drv, child);
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
 static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs,
                                             Transaction *tran)
 {
-    bdrv_remove_file_or_backing_child(bs, bdrv_filter_or_cow_child(bs), tran);
+    bdrv_remove_child(bdrv_filter_or_cow_child(bs), tran);
 }
 
 static int bdrv_replace_node_noperm(BlockDriverState *from,
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Also here ->aio_context is read by I/O threads and written
under BQL.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20221025084952.2139888-2-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_detach_aio_context(BlockDriverState *bs)
     if (bs->quiesce_counter) {
         aio_enable_external(bs->aio_context);
     }
+    assert_bdrv_graph_writable(bs);
     bs->aio_context = NULL;
 }
 
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
         aio_disable_external(new_context);
     }
 
+    assert_bdrv_graph_writable(bs);
     bs->aio_context = new_context;
 
     if (bs->drv && bs->drv->bdrv_attach_aio_context) {
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Simplify the way the aiocontext can be changed in a BDS graph.
There are currently two problems in bdrv_try_set_aio_context:
- There is a confusion of AioContext locks taken and released, because
  we assume that old aiocontext is always taken and new one is
  taken inside.

- It doesn't look very safe to call bdrv_drained_begin while some
  nodes have already switched to the new aiocontext and others haven't.
  This could be especially dangerous because bdrv_drained_begin polls, so
  something else could be executed while graph is in an inconsistent
  state.

Additional minor nitpick: can_set and set_ callbacks both traverse the
graph, both using the ignored list of visited nodes in a different way.

Therefore, get rid of all of this and introduce a new callback,
change_aio_context, that uses transactions to efficiently, cleanly
and most importantly safely change the aiocontext of a graph.

This new callback is a "merge" of the two previous ones:
- Just like can_set_aio_context, recursively traverses the graph.
  Marks all nodes that are visited using a GList, and checks if
  they *could* change the aio_context.
- For each node that passes the above check, drain it and add a new transaction
  that implements a callback that effectively changes the aiocontext.
- Once done, the recursive function returns if *all* nodes can change
  the AioContext. If so, commit the above transactions.
  Regardless of the outcome, call transaction.clean() to undo all drains
  done in the recursion.
- The transaction list is scanned only after all nodes are being drained, so
  we are sure that they all are in the same context, and then
  we switch their AioContext, concluding the drain only after all nodes
  switched to the new AioContext. In this way we make sure that
  bdrv_drained_begin() is always called under the old AioContext, and
  bdrv_drained_end() under the new one.
- Because of the above, we don't need to release and re-acquire the
  old AioContext every time, as everything is done once (and not
  per-node drain and aiocontext change).

Note that the "change" API is not yet invoked anywhere.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20221025084952.2139888-3-eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h |   6 +
 include/block/block_int-common.h   |   3 +
 block.c                            | 220 ++++++++++++++++++++++++++++-
 3 files changed, 228 insertions(+), 1 deletion(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -XXX,XX +XXX,XX @@ bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
                               GSList **ignore, Error **errp);
 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
 
+bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
+                                   GSList **visited, Transaction *tran,
+                                   Error **errp);
+int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
+                                      BdrvChild *ignore_child, Error **errp);
+
 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz);
 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo);
 
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BdrvChildClass {
                         GSList **ignore, Error **errp);
     void (*set_aio_ctx)(BdrvChild *child, AioContext *ctx, GSList **ignore);
 
+    bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx,
+                           GSList **visited, Transaction *tran, Error **errp);
+
     AioContext *(*get_parent_aio_context)(BdrvChild *child);
 
     /*
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
 
 static bool bdrv_backing_overridden(BlockDriverState *bs);
 
+static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
+                                    GSList **visited, Transaction *tran,
+                                    Error **errp);
+
 /* If non-zero, use only whitelisted block drivers */
 static int use_bdrv_whitelist;
 
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
  * must not own the AioContext lock for new_context (unless new_context is the
  * same as the current context of bs).
  *
- * @ignore will accumulate all visited BdrvChild object. The caller is
+ * @ignore will accumulate all visited BdrvChild objects. The caller is
  * responsible for freeing the list afterwards.
  */
 void bdrv_set_aio_context_ignore(BlockDriverState *bs,
@@ -XXX,XX +XXX,XX @@ static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
     return true;
 }
 
+typedef struct BdrvStateSetAioContext {
+    AioContext *new_ctx;
+    BlockDriverState *bs;
+} BdrvStateSetAioContext;
+
+static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx,
+                                           GSList **visited, Transaction *tran,
+                                           Error **errp)
+{
+    GLOBAL_STATE_CODE();
+    if (g_slist_find(*visited, c)) {
+        return true;
+    }
+    *visited = g_slist_prepend(*visited, c);
+
+    /*
+     * A BdrvChildClass that doesn't handle AioContext changes cannot
+     * tolerate any AioContext changes
+     */
+    if (!c->klass->change_aio_ctx) {
+        char *user = bdrv_child_user_desc(c);
+        error_setg(errp, "Changing iothreads is not supported by %s", user);
+        g_free(user);
+        return false;
+    }
+    if (!c->klass->change_aio_ctx(c, ctx, visited, tran, errp)) {
+        assert(!errp || *errp);
+        return false;
+    }
+    return true;
+}
+
 bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
                                     GSList **ignore, Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
     return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp);
 }
 
+bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
+                                   GSList **visited, Transaction *tran,
+                                   Error **errp)
+{
+    GLOBAL_STATE_CODE();
+    if (g_slist_find(*visited, c)) {
+        return true;
+    }
+    *visited = g_slist_prepend(*visited, c);
+    return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp);
+}
+
 /* @ignore will accumulate all visited BdrvChild object. The caller is
  * responsible for freeing the list afterwards. */
 bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
@@ -XXX,XX +XXX,XX @@ bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
     return true;
 }
 
+static void bdrv_set_aio_context_clean(void *opaque)
+{
+    BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
+    BlockDriverState *bs = (BlockDriverState *) state->bs;
+
+    /* Paired with bdrv_drained_begin in bdrv_change_aio_context() */
+    bdrv_drained_end(bs);
+
+    g_free(state);
+}
+
+static void bdrv_set_aio_context_commit(void *opaque)
+{
+    BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
+    BlockDriverState *bs = (BlockDriverState *) state->bs;
+    AioContext *new_context = state->new_ctx;
+    AioContext *old_context = bdrv_get_aio_context(bs);
+    assert_bdrv_graph_writable(bs);
+
+    /*
+     * Take the old AioContex when detaching it from bs.
+     * At this point, new_context lock is already acquired, and we are now
+     * also taking old_context. This is safe as long as bdrv_detach_aio_context
+     * does not call AIO_POLL_WHILE().
+     */
+    if (old_context != qemu_get_aio_context()) {
+        aio_context_acquire(old_context);
+    }
+    bdrv_detach_aio_context(bs);
+    if (old_context != qemu_get_aio_context()) {
+        aio_context_release(old_context);
+    }
+    bdrv_attach_aio_context(bs, new_context);
+}
+
+static TransactionActionDrv set_aio_context = {
+    .commit = bdrv_set_aio_context_commit,
+    .clean = bdrv_set_aio_context_clean,
+};
+
+/*
+ * Changes the AioContext used for fd handlers, timers, and BHs by this
+ * BlockDriverState and all its children and parents.
+ *
+ * Must be called from the main AioContext.
+ *
+ * The caller must own the AioContext lock for the old AioContext of bs, but it
+ * must not own the AioContext lock for new_context (unless new_context is the
+ * same as the current context of bs).
+ *
+ * @visited will accumulate all visited BdrvChild objects. The caller is
+ * responsible for freeing the list afterwards.
+ */
+static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
+                                    GSList **visited, Transaction *tran,
+                                    Error **errp)
+{
+    BdrvChild *c;
+    BdrvStateSetAioContext *state;
+
+    GLOBAL_STATE_CODE();
+
+    if (bdrv_get_aio_context(bs) == ctx) {
+        return true;
+    }
+
+    QLIST_FOREACH(c, &bs->parents, next_parent) {
+        if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) {
+            return false;
+        }
+    }
+
+    QLIST_FOREACH(c, &bs->children, next) {
+        if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) {
+            return false;
+        }
+    }
+
+    state = g_new(BdrvStateSetAioContext, 1);
+    *state = (BdrvStateSetAioContext) {
+        .new_ctx = ctx,
+        .bs = bs,
+    };
+
+    /* Paired with bdrv_drained_end in bdrv_set_aio_context_clean() */
+    bdrv_drained_begin(bs);
+
+    tran_add(tran, &set_aio_context, state);
+
+    return true;
+}
+
 int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
                                    BdrvChild *ignore_child, Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
     return 0;
 }
 
+/*
+ * Change bs's and recursively all of its parents' and children's AioContext
+ * to the given new context, returning an error if that isn't possible.
+ *
+ * If ignore_child is not NULL, that child (and its subgraph) will not
+ * be touched.
+ *
+ * This function still requires the caller to take the bs current
+ * AioContext lock, otherwise draining will fail since AIO_WAIT_WHILE
+ * assumes the lock is always held if bs is in another AioContext.
+ * For the same reason, it temporarily also holds the new AioContext, since
+ * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too.
+ * Therefore the new AioContext lock must not be taken by the caller.
+ */
+int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
+                                      BdrvChild *ignore_child, Error **errp)
+{
+    Transaction *tran;
+    GSList *visited;
+    int ret;
+    AioContext *old_context = bdrv_get_aio_context(bs);
+    GLOBAL_STATE_CODE();
+
+    /*
+     * Recursion phase: go through all nodes of the graph.
+     * Take care of checking that all nodes support changing AioContext
+     * and drain them, builing a linear list of callbacks to run if everything
+     * is successful (the transaction itself).
+     */
+    tran = tran_new();
+    visited = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
+    ret = bdrv_change_aio_context(bs, ctx, &visited, tran, errp);
+    g_slist_free(visited);
+
+    /*
+     * Linear phase: go through all callbacks collected in the transaction.
+     * Run all callbacks collected in the recursion to switch all nodes
+     * AioContext lock (transaction commit), or undo all changes done in the
+     * recursion (transaction abort).
+     */
+
+    if (!ret) {
+        /* Just run clean() callbacks. No AioContext changed. */
+        tran_abort(tran);
+        return -EPERM;
+    }
+
+    /*
+     * Release old AioContext, it won't be needed anymore, as all
+     * bdrv_drained_begin() have been called already.
+     */
+    if (qemu_get_aio_context() != old_context) {
+        aio_context_release(old_context);
+    }
+
+    /*
+     * Acquire new AioContext since bdrv_drained_end() is going to be called
+     * after we switched all nodes in the new AioContext, and the function
+     * assumes that the lock of the bs is always taken.
+     */
+    if (qemu_get_aio_context() != ctx) {
+        aio_context_acquire(ctx);
+    }
+
+    tran_commit(tran);
+
+    if (qemu_get_aio_context() != ctx) {
+        aio_context_release(ctx);
+    }
+
+    /* Re-acquire the old AioContext, since the caller takes and releases it. */
+    if (qemu_get_aio_context() != old_context) {
+        aio_context_acquire(old_context);
+    }
+
+    return 0;
+}
+
 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
                              Error **errp)
 {
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Minor performance improvement, but given that we have hash tables
available, avoid iterating in the visited nodes list every time just
to check if a node has been already visited.

The data structure is not actually a proper hash map, but an hash set,
as we are just adding nodes and not key,value pairs.

Suggested-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-4-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h |  2 +-
 include/block/block_int-common.h   |  3 ++-
 block.c                            | 28 ++++++++++++++++------------
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -XXX,XX +XXX,XX @@ bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
 
 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
-                                   GSList **visited, Transaction *tran,
+                                   GHashTable *visited, Transaction *tran,
                                    Error **errp);
 int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
                                       BdrvChild *ignore_child, Error **errp);
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BdrvChildClass {
     void (*set_aio_ctx)(BdrvChild *child, AioContext *ctx, GSList **ignore);
 
     bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx,
-                           GSList **visited, Transaction *tran, Error **errp);
+                           GHashTable *visited, Transaction *tran,
+                           Error **errp);
 
     AioContext *(*get_parent_aio_context)(BdrvChild *child);
 
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
 static bool bdrv_backing_overridden(BlockDriverState *bs);
 
 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
-                                    GSList **visited, Transaction *tran,
+                                    GHashTable *visited, Transaction *tran,
                                     Error **errp);
 
 /* If non-zero, use only whitelisted block drivers */
@@ -XXX,XX +XXX,XX @@ typedef struct BdrvStateSetAioContext {
 } BdrvStateSetAioContext;
 
 static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx,
-                                           GSList **visited, Transaction *tran,
+                                           GHashTable *visited,
+                                           Transaction *tran,
                                            Error **errp)
 {
     GLOBAL_STATE_CODE();
-    if (g_slist_find(*visited, c)) {
+    if (g_hash_table_contains(visited, c)) {
         return true;
     }
-    *visited = g_slist_prepend(*visited, c);
+    g_hash_table_add(visited, c);
 
     /*
      * A BdrvChildClass that doesn't handle AioContext changes cannot
@@ -XXX,XX +XXX,XX @@ bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
 }
 
 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
-                                   GSList **visited, Transaction *tran,
+                                   GHashTable *visited, Transaction *tran,
                                    Error **errp)
 {
     GLOBAL_STATE_CODE();
-    if (g_slist_find(*visited, c)) {
+    if (g_hash_table_contains(visited, c)) {
         return true;
     }
-    *visited = g_slist_prepend(*visited, c);
+    g_hash_table_add(visited, c);
     return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp);
 }
 
@@ -XXX,XX +XXX,XX @@ static TransactionActionDrv set_aio_context = {
  * responsible for freeing the list afterwards.
  */
 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
-                                    GSList **visited, Transaction *tran,
+                                    GHashTable *visited, Transaction *tran,
                                     Error **errp)
 {
     BdrvChild *c;
@@ -XXX,XX +XXX,XX @@ int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
                                       BdrvChild *ignore_child, Error **errp)
 {
     Transaction *tran;
-    GSList *visited;
+    GHashTable *visited;
     int ret;
     AioContext *old_context = bdrv_get_aio_context(bs);
     GLOBAL_STATE_CODE();
@@ -XXX,XX +XXX,XX @@ int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
      * is successful (the transaction itself).
      */
     tran = tran_new();
-    visited = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
-    ret = bdrv_change_aio_context(bs, ctx, &visited, tran, errp);
-    g_slist_free(visited);
+    visited = g_hash_table_new(NULL, NULL);
+    if (ignore_child) {
+        g_hash_table_add(visited, ignore_child);
+    }
+    ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp);
+    g_hash_table_destroy(visited);
 
     /*
      * Linear phase: go through all callbacks collected in the transaction.
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

child_job_change_aio_ctx() is very similar to
child_job_can_set_aio_ctx(), but it implements a new transaction
so that if all check pass, the new transaction's .commit()
will take care of changin the BlockJob AioContext.
child_job_set_aio_ctx_commit() is similar to child_job_set_aio_ctx(),
but it doesn't need to invoke the recursion, as this is already
taken care by child_job_change_aio_ctx().

Note: bdrv_child_try_change_aio_context() is not called by
anyone at this point.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-5-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 blockjob.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/blockjob.c b/blockjob.c
index XXXXXXX..XXXXXXX 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -XXX,XX +XXX,XX @@ static void child_job_drained_end(BdrvChild *c, int *drained_end_counter)
     job_resume(&job->job);
 }
 
+typedef struct BdrvStateChildJobContext {
+    AioContext *new_ctx;
+    BlockJob *job;
+} BdrvStateChildJobContext;
+
+static void child_job_set_aio_ctx_commit(void *opaque)
+{
+    BdrvStateChildJobContext *s = opaque;
+    BlockJob *job = s->job;
+
+    job_set_aio_context(&job->job, s->new_ctx);
+}
+
+static TransactionActionDrv change_child_job_context = {
+    .commit = child_job_set_aio_ctx_commit,
+    .clean = g_free,
+};
+
+static bool child_job_change_aio_ctx(BdrvChild *c, AioContext *ctx,
+                                     GHashTable *visited, Transaction *tran,
+                                     Error **errp)
+{
+    BlockJob *job = c->opaque;
+    BdrvStateChildJobContext *s;
+    GSList *l;
+
+    for (l = job->nodes; l; l = l->next) {
+        BdrvChild *sibling = l->data;
+        if (!bdrv_child_change_aio_context(sibling, ctx, visited,
+                                           tran, errp)) {
+            return false;
+        }
+    }
+
+    s = g_new(BdrvStateChildJobContext, 1);
+    *s = (BdrvStateChildJobContext) {
+        .new_ctx = ctx,
+        .job = job,
+    };
+
+    tran_add(tran, &change_child_job_context, s);
+    return true;
+}
+
 static bool child_job_can_set_aio_ctx(BdrvChild *c, AioContext *ctx,
                                       GSList **ignore, Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ static const BdrvChildClass child_job = {
     .drained_end        = child_job_drained_end,
     .can_set_aio_ctx    = child_job_can_set_aio_ctx,
     .set_aio_ctx        = child_job_set_aio_ctx,
+    .change_aio_ctx     = child_job_change_aio_ctx,
     .stay_at_node       = true,
     .get_parent_aio_context = child_job_get_parent_aio_context,
 };
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

bdrv_child_cb_change_aio_ctx() is identical to
bdrv_child_cb_can_set_aio_ctx(), as we only need
to recursively go on the parent bs.

Note: bdrv_child_try_change_aio_context() is not called by
anyone at this point.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-6-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static int bdrv_child_cb_inactivate(BdrvChild *child)
     return 0;
 }
 
+static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+                                         GHashTable *visited, Transaction *tran,
+                                         Error **errp)
+{
+    BlockDriverState *bs = child->opaque;
+    return bdrv_change_aio_context(bs, ctx, visited, tran, errp);
+}
+
 static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
                                           GSList **ignore, Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ const BdrvChildClass child_of_bds = {
     .inactivate      = bdrv_child_cb_inactivate,
     .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
     .set_aio_ctx     = bdrv_child_cb_set_aio_ctx,
+    .change_aio_ctx  = bdrv_child_cb_change_aio_ctx,
     .update_filename = bdrv_child_cb_update_filename,
     .get_parent_aio_context = child_of_bds_get_parent_aio_context,
 };
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

blk_root_change_aio_ctx() is very similar to blk_root_can_set_aio_ctx(),
but implements a new transaction so that if all check pass, the new
transaction's .commit will take care of changing the BlockBackend
AioContext. blk_root_set_aio_ctx_commit() is the same as
blk_root_set_aio_ctx().

Note: bdrv_child_try_change_aio_context() is not called by
anyone at this point.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-7-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/block-backend.c | 52 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index XXXXXXX..XXXXXXX 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -XXX,XX +XXX,XX @@ static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
                                      GSList **ignore, Error **errp);
 static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
                                  GSList **ignore);
+static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+                                    GHashTable *visited, Transaction *tran,
+                                    Error **errp);
 
 static char *blk_root_get_parent_desc(BdrvChild *child)
 {
@@ -XXX,XX +XXX,XX @@ static const BdrvChildClass child_root = {
 
     .can_set_aio_ctx    = blk_root_can_set_aio_ctx,
     .set_aio_ctx        = blk_root_set_aio_ctx,
+    .change_aio_ctx     = blk_root_change_aio_ctx,
 
     .get_parent_aio_context = blk_root_get_parent_aio_context,
 };
@@ -XXX,XX +XXX,XX @@ int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
     return blk_do_set_aio_context(blk, new_context, true, errp);
 }
 
+typedef struct BdrvStateBlkRootContext {
+    AioContext *new_ctx;
+    BlockBackend *blk;
+} BdrvStateBlkRootContext;
+
+static void blk_root_set_aio_ctx_commit(void *opaque)
+{
+    BdrvStateBlkRootContext *s = opaque;
+    BlockBackend *blk = s->blk;
+
+    blk_do_set_aio_context(blk, s->new_ctx, false, &error_abort);
+}
+
+static TransactionActionDrv set_blk_root_context = {
+    .commit = blk_root_set_aio_ctx_commit,
+    .clean = g_free,
+};
+
+static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+                                    GHashTable *visited, Transaction *tran,
+                                    Error **errp)
+{
+    BlockBackend *blk = child->opaque;
+    BdrvStateBlkRootContext *s;
+
+    if (!blk->allow_aio_context_change) {
+        /*
+         * Manually created BlockBackends (those with a name) that are not
+         * attached to anything can change their AioContext without updating
+         * their user; return an error for others.
+         */
+        if (!blk->name || blk->dev) {
+            /* TODO Add BB name/QOM path */
+            error_setg(errp, "Cannot change iothread of active block backend");
+            return false;
+        }
+    }
+
+    s = g_new(BdrvStateBlkRootContext, 1);
+    *s = (BdrvStateBlkRootContext) {
+        .new_ctx = ctx,
+        .blk = blk,
+    };
+
+    tran_add(tran, &set_blk_root_context, s);
+    return true;
+}
+
 static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
                                      GSList **ignore, Error **errp)
 {
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Replace all direct usage of ->can_set_aio_ctx and ->set_aio_ctx,
and call bdrv_child_try_change_aio_context() in
bdrv_try_set_aio_context(), the main function called through
the whole block layer.

From this point onwards, ->can_set_aio_ctx and ->set_aio_ctx
won't be used anymore.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-8-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c               | 44 ++++++++++++++++++++++++-------------------
 block/block-backend.c |  8 ++++++--
 2 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_child_common_abort(void *opaque)
     }
 
     if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) {
-        GSList *ignore;
+        Transaction *tran;
+        GHashTable *visited;
+        bool ret;
 
-        /* No need to ignore `child`, because it has been detached already */
-        ignore = NULL;
-        s->child->klass->can_set_aio_ctx(s->child, s->old_parent_ctx, &ignore,
-                                         &error_abort);
-        g_slist_free(ignore);
+        tran = tran_new();
 
-        ignore = NULL;
-        s->child->klass->set_aio_ctx(s->child, s->old_parent_ctx, &ignore);
-        g_slist_free(ignore);
+        /* No need to visit `child`, because it has been detached already */
+        visited = g_hash_table_new(NULL, NULL);
+        ret = s->child->klass->change_aio_ctx(s->child, s->old_parent_ctx,
+                                              visited, tran, &error_abort);
+        g_hash_table_destroy(visited);
+
+        /* transaction is supposed to always succeed */
+        assert(ret == true);
+        tran_commit(tran);
     }
 
     bdrv_unref(bs);
@@ -XXX,XX +XXX,XX @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
         Error *local_err = NULL;
         int ret = bdrv_try_set_aio_context(child_bs, parent_ctx, &local_err);
 
-        if (ret < 0 && child_class->can_set_aio_ctx) {
-            GSList *ignore = g_slist_prepend(NULL, new_child);
-            if (child_class->can_set_aio_ctx(new_child, child_ctx, &ignore,
-                                             NULL))
-            {
+        if (ret < 0 && child_class->change_aio_ctx) {
+            Transaction *tran = tran_new();
+            GHashTable *visited = g_hash_table_new(NULL, NULL);
+            bool ret_child;
+
+            g_hash_table_add(visited, new_child);
+            ret_child = child_class->change_aio_ctx(new_child, child_ctx,
+                                                    visited, tran, NULL);
+            if (ret_child == true) {
                 error_free(local_err);
                 ret = 0;
-                g_slist_free(ignore);
-                ignore = g_slist_prepend(NULL, new_child);
-                child_class->set_aio_ctx(new_child, child_ctx, &ignore);
             }
-            g_slist_free(ignore);
+            tran_finalize(tran, ret_child == true ? 0 : -1);
+            g_hash_table_destroy(visited);
         }
 
         if (ret < 0) {
@@ -XXX,XX +XXX,XX @@ int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
                              Error **errp)
 {
     GLOBAL_STATE_CODE();
-    return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp);
+    return bdrv_child_try_change_aio_context(bs, ctx, NULL, errp);
 }
 
 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
diff --git a/block/block-backend.c b/block/block-backend.c
index XXXXXXX..XXXXXXX 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -XXX,XX +XXX,XX @@ static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
         bdrv_ref(bs);
 
         if (update_root_node) {
-            ret = bdrv_child_try_set_aio_context(bs, new_context, blk->root,
-                                                 errp);
+            /*
+             * update_root_node MUST be false for blk_root_set_aio_ctx_commit(),
+             * as we are already in the commit function of a transaction.
+             */
+            ret = bdrv_child_try_change_aio_context(bs, new_context, blk->root,
+                                                    errp);
             if (ret < 0) {
                 bdrv_unref(bs);
                 return ret;
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Together with all _can_set_ and _set_ APIs, as they are not needed
anymore.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-9-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h |   9 --
 include/block/block_int-common.h   |   4 -
 block.c                            | 196 -----------------------------
 block/block-backend.c              |  33 -----
 blockjob.c                         |  35 ------
 5 files changed, 277 deletions(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -XXX,XX +XXX,XX @@ void coroutine_fn bdrv_co_lock(BlockDriverState *bs);
  */
 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs);
 
-void bdrv_set_aio_context_ignore(BlockDriverState *bs,
-                                 AioContext *new_context, GSList **ignore);
 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
                              Error **errp);
-int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
-                                   BdrvChild *ignore_child, Error **errp);
-bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
-                                    GSList **ignore, Error **errp);
-bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
-                              GSList **ignore, Error **errp);
 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
-
 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
                                    GHashTable *visited, Transaction *tran,
                                    Error **errp);
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BdrvChildClass {
     int (*update_filename)(BdrvChild *child, BlockDriverState *new_base,
                            const char *filename, Error **errp);
 
-    bool (*can_set_aio_ctx)(BdrvChild *child, AioContext *ctx,
-                        GSList **ignore, Error **errp);
-    void (*set_aio_ctx)(BdrvChild *child, AioContext *ctx, GSList **ignore);
-
     bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx,
                            GHashTable *visited, Transaction *tran,
                            Error **errp);
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx,
     return bdrv_change_aio_context(bs, ctx, visited, tran, errp);
 }
 
-static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                          GSList **ignore, Error **errp)
-{
-    BlockDriverState *bs = child->opaque;
-    return bdrv_can_set_aio_context(bs, ctx, ignore, errp);
-}
-
-static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                      GSList **ignore)
-{
-    BlockDriverState *bs = child->opaque;
-    return bdrv_set_aio_context_ignore(bs, ctx, ignore);
-}
-
 /*
  * Returns the options and flags that a temporary snapshot should get, based on
  * the originally requested flags (the originally requested image will have
@@ -XXX,XX +XXX,XX @@ const BdrvChildClass child_of_bds = {
     .attach          = bdrv_child_cb_attach,
     .detach          = bdrv_child_cb_detach,
     .inactivate      = bdrv_child_cb_inactivate,
-    .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
-    .set_aio_ctx     = bdrv_child_cb_set_aio_ctx,
     .change_aio_ctx  = bdrv_child_cb_change_aio_ctx,
     .update_filename = bdrv_child_cb_update_filename,
     .get_parent_aio_context = child_of_bds_get_parent_aio_context,
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
     bs->walking_aio_notifiers = false;
 }
 
-/*
- * Changes the AioContext used for fd handlers, timers, and BHs by this
- * BlockDriverState and all its children and parents.
- *
- * Must be called from the main AioContext.
- *
- * The caller must own the AioContext lock for the old AioContext of bs, but it
- * must not own the AioContext lock for new_context (unless new_context is the
- * same as the current context of bs).
- *
- * @ignore will accumulate all visited BdrvChild objects. The caller is
- * responsible for freeing the list afterwards.
- */
-void bdrv_set_aio_context_ignore(BlockDriverState *bs,
-                                 AioContext *new_context, GSList **ignore)
-{
-    AioContext *old_context = bdrv_get_aio_context(bs);
-    GSList *children_to_process = NULL;
-    GSList *parents_to_process = NULL;
-    GSList *entry;
-    BdrvChild *child, *parent;
-
-    g_assert(qemu_get_current_aio_context() == qemu_get_aio_context());
-    GLOBAL_STATE_CODE();
-
-    if (old_context == new_context) {
-        return;
-    }
-
-    bdrv_drained_begin(bs);
-
-    QLIST_FOREACH(child, &bs->children, next) {
-        if (g_slist_find(*ignore, child)) {
-            continue;
-        }
-        *ignore = g_slist_prepend(*ignore, child);
-        children_to_process = g_slist_prepend(children_to_process, child);
-    }
-
-    QLIST_FOREACH(parent, &bs->parents, next_parent) {
-        if (g_slist_find(*ignore, parent)) {
-            continue;
-        }
-        *ignore = g_slist_prepend(*ignore, parent);
-        parents_to_process = g_slist_prepend(parents_to_process, parent);
-    }
-
-    for (entry = children_to_process;
-         entry != NULL;
-         entry = g_slist_next(entry)) {
-        child = entry->data;
-        bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
-    }
-    g_slist_free(children_to_process);
-
-    for (entry = parents_to_process;
-         entry != NULL;
-         entry = g_slist_next(entry)) {
-        parent = entry->data;
-        assert(parent->klass->set_aio_ctx);
-        parent->klass->set_aio_ctx(parent, new_context, ignore);
-    }
-    g_slist_free(parents_to_process);
-
-    bdrv_detach_aio_context(bs);
-
-    /* Acquire the new context, if necessary */
-    if (qemu_get_aio_context() != new_context) {
-        aio_context_acquire(new_context);
-    }
-
-    bdrv_attach_aio_context(bs, new_context);
-
-    /*
-     * If this function was recursively called from
-     * bdrv_set_aio_context_ignore(), there may be nodes in the
-     * subtree that have not yet been moved to the new AioContext.
-     * Release the old one so bdrv_drained_end() can poll them.
-     */
-    if (qemu_get_aio_context() != old_context) {
-        aio_context_release(old_context);
-    }
-
-    bdrv_drained_end(bs);
-
-    if (qemu_get_aio_context() != old_context) {
-        aio_context_acquire(old_context);
-    }
-    if (qemu_get_aio_context() != new_context) {
-        aio_context_release(new_context);
-    }
-}
-
-static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
-                                            GSList **ignore, Error **errp)
-{
-    GLOBAL_STATE_CODE();
-    if (g_slist_find(*ignore, c)) {
-        return true;
-    }
-    *ignore = g_slist_prepend(*ignore, c);
-
-    /*
-     * A BdrvChildClass that doesn't handle AioContext changes cannot
-     * tolerate any AioContext changes
-     */
-    if (!c->klass->can_set_aio_ctx) {
-        char *user = bdrv_child_user_desc(c);
-        error_setg(errp, "Changing iothreads is not supported by %s", user);
-        g_free(user);
-        return false;
-    }
-    if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) {
-        assert(!errp || *errp);
-        return false;
-    }
-    return true;
-}
-
 typedef struct BdrvStateSetAioContext {
     AioContext *new_ctx;
     BlockDriverState *bs;
@@ -XXX,XX +XXX,XX @@ static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx,
     return true;
 }
 
-bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
-                                    GSList **ignore, Error **errp)
-{
-    GLOBAL_STATE_CODE();
-    if (g_slist_find(*ignore, c)) {
-        return true;
-    }
-    *ignore = g_slist_prepend(*ignore, c);
-    return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp);
-}
-
 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
                                    GHashTable *visited, Transaction *tran,
                                    Error **errp)
@@ -XXX,XX +XXX,XX @@ bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
     return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp);
 }
 
-/* @ignore will accumulate all visited BdrvChild object. The caller is
- * responsible for freeing the list afterwards. */
-bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
-                              GSList **ignore, Error **errp)
-{
-    BdrvChild *c;
-
-    if (bdrv_get_aio_context(bs) == ctx) {
-        return true;
-    }
-
-    GLOBAL_STATE_CODE();
-
-    QLIST_FOREACH(c, &bs->parents, next_parent) {
-        if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) {
-            return false;
-        }
-    }
-    QLIST_FOREACH(c, &bs->children, next) {
-        if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
 static void bdrv_set_aio_context_clean(void *opaque)
 {
     BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
@@ -XXX,XX +XXX,XX @@ static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
     return true;
 }
 
-int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
-                                   BdrvChild *ignore_child, Error **errp)
-{
-    GSList *ignore;
-    bool ret;
-
-    GLOBAL_STATE_CODE();
-
-    ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
-    ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp);
-    g_slist_free(ignore);
-
-    if (!ret) {
-        return -EPERM;
-    }
-
-    ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
-    bdrv_set_aio_context_ignore(bs, ctx, &ignore);
-    g_slist_free(ignore);
-
-    return 0;
-}
-
 /*
  * Change bs's and recursively all of its parents' and children's AioContext
  * to the given new context, returning an error if that isn't possible.
diff --git a/block/block-backend.c b/block/block-backend.c
index XXXXXXX..XXXXXXX 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -XXX,XX +XXX,XX @@ static void blk_root_drained_end(BdrvChild *child, int *drained_end_counter);
 static void blk_root_change_media(BdrvChild *child, bool load);
 static void blk_root_resize(BdrvChild *child);
 
-static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                     GSList **ignore, Error **errp);
-static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                 GSList **ignore);
 static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
                                     GHashTable *visited, Transaction *tran,
                                     Error **errp);
@@ -XXX,XX +XXX,XX @@ static const BdrvChildClass child_root = {
     .attach             = blk_root_attach,
     .detach             = blk_root_detach,
 
-    .can_set_aio_ctx    = blk_root_can_set_aio_ctx,
-    .set_aio_ctx        = blk_root_set_aio_ctx,
     .change_aio_ctx     = blk_root_change_aio_ctx,
 
     .get_parent_aio_context = blk_root_get_parent_aio_context,
@@ -XXX,XX +XXX,XX @@ static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
     return true;
 }
 
-static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                     GSList **ignore, Error **errp)
-{
-    BlockBackend *blk = child->opaque;
-
-    if (blk->allow_aio_context_change) {
-        return true;
-    }
-
-    /* Only manually created BlockBackends that are not attached to anything
-     * can change their AioContext without updating their user. */
-    if (!blk->name || blk->dev) {
-        /* TODO Add BB name/QOM path */
-        error_setg(errp, "Cannot change iothread of active block backend");
-        return false;
-    }
-
-    return true;
-}
-
-static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                 GSList **ignore)
-{
-    BlockBackend *blk = child->opaque;
-    blk_do_set_aio_context(blk, ctx, false, &error_abort);
-}
-
 void blk_add_aio_context_notifier(BlockBackend *blk,
         void (*attached_aio_context)(AioContext *new_context, void *opaque),
         void (*detach_aio_context)(void *opaque), void *opaque)
diff --git a/blockjob.c b/blockjob.c
index XXXXXXX..XXXXXXX 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -XXX,XX +XXX,XX @@ static bool child_job_change_aio_ctx(BdrvChild *c, AioContext *ctx,
     return true;
 }
 
-static bool child_job_can_set_aio_ctx(BdrvChild *c, AioContext *ctx,
-                                      GSList **ignore, Error **errp)
-{
-    BlockJob *job = c->opaque;
-    GSList *l;
-
-    for (l = job->nodes; l; l = l->next) {
-        BdrvChild *sibling = l->data;
-        if (!bdrv_child_can_set_aio_context(sibling, ctx, ignore, errp)) {
-            return false;
-        }
-    }
-    return true;
-}
-
-static void child_job_set_aio_ctx(BdrvChild *c, AioContext *ctx,
-                                  GSList **ignore)
-{
-    BlockJob *job = c->opaque;
-    GSList *l;
-
-    for (l = job->nodes; l; l = l->next) {
-        BdrvChild *sibling = l->data;
-        if (g_slist_find(*ignore, sibling)) {
-            continue;
-        }
-        *ignore = g_slist_prepend(*ignore, sibling);
-        bdrv_set_aio_context_ignore(sibling->bs, ctx, ignore);
-    }
-
-    job_set_aio_context(&job->job, ctx);
-}
-
 static AioContext *child_job_get_parent_aio_context(BdrvChild *c)
 {
     BlockJob *job = c->opaque;
@@ -XXX,XX +XXX,XX @@ static const BdrvChildClass child_job = {
     .drained_begin      = child_job_drained_begin,
     .drained_poll       = child_job_drained_poll,
     .drained_end        = child_job_drained_end,
-    .can_set_aio_ctx    = child_job_can_set_aio_ctx,
-    .set_aio_ctx        = child_job_set_aio_ctx,
     .change_aio_ctx     = child_job_change_aio_ctx,
     .stay_at_node       = true,
     .get_parent_aio_context = child_job_get_parent_aio_context,
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

No functional changes intended.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-10-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h | 4 ++--
 block.c                            | 6 +++---
 block/block-backend.c              | 3 +--
 3 files changed, 6 insertions(+), 7 deletions(-)

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

No functional change intended.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221025084952.2139888-11-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 docs/devel/multiple-iothreads.txt  |  4 ++--
 include/block/block-global-state.h |  2 --
 block.c                            | 14 ++++----------
 block/export/export.c              |  2 +-
 blockdev.c                         | 22 +++++++++++-----------
 job.c                              |  2 +-
 tests/unit/test-bdrv-drain.c       |  6 +++---
 tests/unit/test-block-iothread.c   | 10 +++++-----
 8 files changed, 27 insertions(+), 35 deletions(-)

diff --git a/docs/devel/multiple-iothreads.txt b/docs/devel/multiple-iothreads.txt
index XXXXXXX..XXXXXXX 100644
--- a/docs/devel/multiple-iothreads.txt
+++ b/docs/devel/multiple-iothreads.txt
@@ -XXX,XX +XXX,XX @@ The AioContext originates from the QEMU block layer, even though nowadays
 AioContext is a generic event loop that can be used by any QEMU subsystem.
 
 The block layer has support for AioContext integrated.  Each BlockDriverState
-is associated with an AioContext using bdrv_try_set_aio_context() and
+is associated with an AioContext using bdrv_try_change_aio_context() and
 bdrv_get_aio_context().  This allows block layer code to process I/O inside the
 right AioContext.  Other subsystems may wish to follow a similar approach.
 
@@ -XXX,XX +XXX,XX @@ Long-running jobs (usually in the form of coroutines) are best scheduled in
 the BlockDriverState's AioContext to avoid the need to acquire/release around
 each bdrv_*() call.  The functions bdrv_add/remove_aio_context_notifier,
 or alternatively blk_add/remove_aio_context_notifier if you use BlockBackends,
-can be used to get a notification whenever bdrv_try_set_aio_context() moves a
+can be used to get a notification whenever bdrv_try_change_aio_context() moves a
 BlockDriverState to a different AioContext.
diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -XXX,XX +XXX,XX @@ void coroutine_fn bdrv_co_lock(BlockDriverState *bs);
  */
 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs);
 
-int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
-                             Error **errp);
 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
                                    GHashTable *visited, Transaction *tran,
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ static void bdrv_attach_child_common_abort(void *opaque)
     bdrv_replace_child_noperm(s->child, NULL);
 
     if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
-        bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort);
+        bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort);
     }
 
     if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) {
@@ -XXX,XX +XXX,XX @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
     parent_ctx = bdrv_child_get_parent_aio_context(new_child);
     if (child_ctx != parent_ctx) {
         Error *local_err = NULL;
-        int ret = bdrv_try_set_aio_context(child_bs, parent_ctx, &local_err);
+        int ret = bdrv_try_change_aio_context(child_bs, parent_ctx, NULL,
+                                              &local_err);
 
         if (ret < 0 && child_class->change_aio_ctx) {
             Transaction *tran = tran_new();
@@ -XXX,XX +XXX,XX @@ static void bdrv_detach_child(BdrvChild *child)
          * When the parent requiring a non-default AioContext is removed, the
          * node moves back to the main AioContext
          */
-        bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);
+        bdrv_try_change_aio_context(old_bs, qemu_get_aio_context(), NULL, NULL);
     }
 }
 
@@ -XXX,XX +XXX,XX @@ int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
     return 0;
 }
 
-int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
-                             Error **errp)
-{
-    GLOBAL_STATE_CODE();
-    return bdrv_try_change_aio_context(bs, ctx, NULL, errp);
-}
-
 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
         void (*attached_aio_context)(AioContext *new_context, void *opaque),
         void (*detach_aio_context)(void *opaque), void *opaque)
diff --git a/block/export/export.c b/block/export/export.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -XXX,XX +XXX,XX @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
 
         /* Ignore errors with fixed-iothread=false */
         set_context_errp = fixed_iothread ? errp : NULL;
-        ret = bdrv_try_set_aio_context(bs, new_ctx, set_context_errp);
+        ret = bdrv_try_change_aio_context(bs, new_ctx, NULL, set_context_errp);
         if (ret == 0) {
             aio_context_release(ctx);
             aio_context_acquire(new_ctx);
diff --git a/blockdev.c b/blockdev.c
index XXXXXXX..XXXXXXX 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -XXX,XX +XXX,XX @@ static void external_snapshot_abort(BlkActionState *common)
                 aio_context_release(aio_context);
                 aio_context_acquire(tmp_context);
 
-                ret = bdrv_try_set_aio_context(state->old_bs,
-                                               aio_context, NULL);
+                ret = bdrv_try_change_aio_context(state->old_bs,
+                                                  aio_context, NULL, NULL);
                 assert(ret == 0);
 
                 aio_context_release(tmp_context);
@@ -XXX,XX +XXX,XX @@ static void drive_backup_prepare(BlkActionState *common, Error **errp)
         goto out;
     }
 
-    /* Honor bdrv_try_set_aio_context() context acquisition requirements. */
+    /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     old_context = bdrv_get_aio_context(target_bs);
     aio_context_release(aio_context);
     aio_context_acquire(old_context);
 
-    ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
+    ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
     if (ret < 0) {
         bdrv_unref(target_bs);
         aio_context_release(old_context);
@@ -XXX,XX +XXX,XX @@ static void blockdev_backup_prepare(BlkActionState *common, Error **errp)
         return;
     }
 
-    /* Honor bdrv_try_set_aio_context() context acquisition requirements. */
+    /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     aio_context = bdrv_get_aio_context(bs);
     old_context = bdrv_get_aio_context(target_bs);
     aio_context_acquire(old_context);
 
-    ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
+    ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
     if (ret < 0) {
         aio_context_release(old_context);
         return;
@@ -XXX,XX +XXX,XX @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
                     !bdrv_has_zero_init(target_bs)));
 
 
-    /* Honor bdrv_try_set_aio_context() context acquisition requirements. */
+    /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     old_context = bdrv_get_aio_context(target_bs);
     aio_context_release(aio_context);
     aio_context_acquire(old_context);
 
-    ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
+    ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
     if (ret < 0) {
         bdrv_unref(target_bs);
         aio_context_release(old_context);
@@ -XXX,XX +XXX,XX @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
 
     zero_target = (sync == MIRROR_SYNC_MODE_FULL);
 
-    /* Honor bdrv_try_set_aio_context() context acquisition requirements. */
+    /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     old_context = bdrv_get_aio_context(target_bs);
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(old_context);
 
-    ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
+    ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
 
     aio_context_release(old_context);
     aio_context_acquire(aio_context);
@@ -XXX,XX +XXX,XX @@ void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
     old_context = bdrv_get_aio_context(bs);
     aio_context_acquire(old_context);
 
-    bdrv_try_set_aio_context(bs, new_context, errp);
+    bdrv_try_change_aio_context(bs, new_context, NULL, errp);
 
     aio_context_release(old_context);
 }
diff --git a/job.c b/job.c
index XXXXXXX..XXXXXXX 100644
--- a/job.c
+++ b/job.c
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn job_do_yield_locked(Job *job, uint64_t ns)
     next_aio_context = job->aio_context;
     /*
      * Coroutine has resumed, but in the meanwhile the job AioContext
-     * might have changed via bdrv_try_set_aio_context(), so we need to move
+     * might have changed via bdrv_try_change_aio_context(), so we need to move
      * the coroutine too in the new aiocontext.
      */
     while (qemu_get_current_aio_context() != next_aio_context) {
diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -XXX,XX +XXX,XX @@ static void test_set_aio_context(void)
                               &error_abort);
 
     bdrv_drained_begin(bs);
-    bdrv_try_set_aio_context(bs, ctx_a, &error_abort);
+    bdrv_try_change_aio_context(bs, ctx_a, NULL, &error_abort);
 
     aio_context_acquire(ctx_a);
     bdrv_drained_end(bs);
 
     bdrv_drained_begin(bs);
-    bdrv_try_set_aio_context(bs, ctx_b, &error_abort);
+    bdrv_try_change_aio_context(bs, ctx_b, NULL, &error_abort);
     aio_context_release(ctx_a);
     aio_context_acquire(ctx_b);
-    bdrv_try_set_aio_context(bs, qemu_get_aio_context(), &error_abort);
+    bdrv_try_change_aio_context(bs, qemu_get_aio_context(), NULL, &error_abort);
     aio_context_release(ctx_b);
     bdrv_drained_end(bs);
 
diff --git a/tests/unit/test-block-iothread.c b/tests/unit/test-block-iothread.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/unit/test-block-iothread.c
+++ b/tests/unit/test-block-iothread.c
@@ -XXX,XX +XXX,XX @@ static void test_propagate_mirror(void)
     filter = bdrv_find_node("filter_node");
 
     /* Change the AioContext of src */
-    bdrv_try_set_aio_context(src, ctx, &error_abort);
+    bdrv_try_change_aio_context(src, ctx, NULL, &error_abort);
     g_assert(bdrv_get_aio_context(src) == ctx);
     g_assert(bdrv_get_aio_context(target) == ctx);
     g_assert(bdrv_get_aio_context(filter) == ctx);
@@ -XXX,XX +XXX,XX @@ static void test_propagate_mirror(void)
 
     /* Change the AioContext of target */
     aio_context_acquire(ctx);
-    bdrv_try_set_aio_context(target, main_ctx, &error_abort);
+    bdrv_try_change_aio_context(target, main_ctx, NULL, &error_abort);
     aio_context_release(ctx);
     g_assert(bdrv_get_aio_context(src) == main_ctx);
     g_assert(bdrv_get_aio_context(target) == main_ctx);
@@ -XXX,XX +XXX,XX @@ static void test_propagate_mirror(void)
     blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
     blk_insert_bs(blk, src, &error_abort);
 
-    bdrv_try_set_aio_context(target, ctx, &local_err);
+    bdrv_try_change_aio_context(target, ctx, NULL, &local_err);
     error_free_or_abort(&local_err);
 
     g_assert(blk_get_aio_context(blk) == main_ctx);
@@ -XXX,XX +XXX,XX @@ static void test_propagate_mirror(void)
     /* ...unless we explicitly allow it */
     aio_context_acquire(ctx);
     blk_set_allow_aio_context_change(blk, true);
-    bdrv_try_set_aio_context(target, ctx, &error_abort);
+    bdrv_try_change_aio_context(target, ctx, NULL, &error_abort);
     aio_context_release(ctx);
 
     g_assert(blk_get_aio_context(blk) == ctx);
@@ -XXX,XX +XXX,XX @@ static void test_propagate_mirror(void)
 
     aio_context_acquire(ctx);
     blk_set_aio_context(blk, main_ctx, &error_abort);
-    bdrv_try_set_aio_context(target, main_ctx, &error_abort);
+    bdrv_try_change_aio_context(target, main_ctx, NULL, &error_abort);
     aio_context_release(ctx);
 
     blk_unref(blk);
-- 
2.37.3

From: Bin Meng <bin.meng@windriver.com>

libnfs.h declares nfs_fstat() as the following for win32:

int nfs_fstat(struct nfs_context *nfs, struct nfsfh *nfsfh,
                struct __stat64 *st);

The 'st' parameter should be of type 'struct __stat64'. The
codes happen to build successfully for 64-bit Windows, but it
does not build for 32-bit Windows.

Fixes: 6542aa9c75bc ("block: add native support for NFS")
Fixes: 18a8056e0bc7 ("block/nfs: cache allocated filesize for read-only files")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20220908132817.1831008-6-bmeng.cn@gmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/nfs.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/nfs.c b/block/nfs.c
index XXXXXXX..XXXXXXX 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -XXX,XX +XXX,XX @@ static int64_t nfs_client_open(NFSClient *client, BlockdevOptionsNfs *opts,
                                int flags, int open_flags, Error **errp)
 {
     int64_t ret = -EINVAL;
+#ifdef _WIN32
+    struct __stat64 st;
+#else
     struct stat st;
+#endif
     char *file = NULL, *strp = NULL;
 
     qemu_mutex_init(&client->mutex);
@@ -XXX,XX +XXX,XX @@ static int nfs_reopen_prepare(BDRVReopenState *state,
                               BlockReopenQueue *queue, Error **errp)
 {
     NFSClient *client = state->bs->opaque;
+#ifdef _WIN32
+    struct __stat64 st;
+#else
     struct stat st;
+#endif
     int ret = 0;
 
     if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

hmp_block_resize and hmp_screendump are defined as a ".coroutine = true" command,
so they must be coroutine_fn.

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-4-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-hmp-cmds.h | 2 +-
 include/monitor/hmp.h          | 3 ++-
 block/monitor/block-hmp-cmds.c | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/block/block-hmp-cmds.h b/include/block/block-hmp-cmds.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-hmp-cmds.h
+++ b/include/block/block-hmp-cmds.h
@@ -XXX,XX +XXX,XX @@ void hmp_nbd_server_add(Monitor *mon, const QDict *qdict);
 void hmp_nbd_server_remove(Monitor *mon, const QDict *qdict);
 void hmp_nbd_server_stop(Monitor *mon, const QDict *qdict);
 
-void hmp_block_resize(Monitor *mon, const QDict *qdict);
+void coroutine_fn hmp_block_resize(Monitor *mon, const QDict *qdict);
 void hmp_block_stream(Monitor *mon, const QDict *qdict);
 void hmp_block_passwd(Monitor *mon, const QDict *qdict);
 void hmp_block_set_io_throttle(Monitor *mon, const QDict *qdict);
diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
index XXXXXXX..XXXXXXX 100644
--- a/include/monitor/hmp.h
+++ b/include/monitor/hmp.h
@@ -XXX,XX +XXX,XX @@
 #define HMP_H
 
 #include "qemu/readline.h"
+#include "qemu/coroutine.h"
 #include "qapi/qapi-types-common.h"
 
 bool hmp_handle_error(Monitor *mon, Error *err);
@@ -XXX,XX +XXX,XX @@ void hmp_netdev_del(Monitor *mon, const QDict *qdict);
 void hmp_getfd(Monitor *mon, const QDict *qdict);
 void hmp_closefd(Monitor *mon, const QDict *qdict);
 void hmp_sendkey(Monitor *mon, const QDict *qdict);
-void hmp_screendump(Monitor *mon, const QDict *qdict);
+void coroutine_fn hmp_screendump(Monitor *mon, const QDict *qdict);
 void hmp_chardev_add(Monitor *mon, const QDict *qdict);
 void hmp_chardev_change(Monitor *mon, const QDict *qdict);
 void hmp_chardev_remove(Monitor *mon, const QDict *qdict);
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index XXXXXXX..XXXXXXX 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -XXX,XX +XXX,XX @@ void hmp_nbd_server_stop(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, err);
 }
 
-void hmp_block_resize(Monitor *mon, const QDict *qdict)
+void coroutine_fn hmp_block_resize(Monitor *mon, const QDict *qdict)
 {
     const char *device = qdict_get_str(qdict, "device");
     int64_t size = qdict_get_int(qdict, "size");
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

ssh_write is only called from ssh_co_writev.

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-5-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/ssh.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/ssh.c b/block/ssh.c
index XXXXXXX..XXXXXXX 100644
--- a/block/ssh.c
+++ b/block/ssh.c
@@ -XXX,XX +XXX,XX @@ static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
     return ret;
 }
 
-static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
-                     int64_t offset, size_t size,
-                     QEMUIOVector *qiov)
+static coroutine_fn int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
+                                  int64_t offset, size_t size,
+                                  QEMUIOVector *qiov)
 {
     ssize_t r;
     size_t written;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

The functions are marked coroutine_fn in the definition.

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-6-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-io.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/block/block-io.h b/include/block/block-io.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -XXX,XX +XXX,XX @@ void bdrv_aio_cancel(BlockAIOCB *acb);
 void bdrv_aio_cancel_async(BlockAIOCB *acb);
 
 /* sg packet commands */
-int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf);
+int coroutine_fn bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf);
 
 /* Ensure contents are flushed to disk.  */
 int coroutine_fn bdrv_co_flush(BlockDriverState *bs);
 
-int bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
+int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
+                                  int64_t bytes);
 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
 int bdrv_block_status(BlockDriverState *bs, int64_t offset,
                       int64_t bytes, int64_t *pnum, int64_t *map,
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

The functions are marked coroutine_fn in the definition.

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-7-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/qemu/coroutine.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h
index XXXXXXX..XXXXXXX 100644
--- a/include/qemu/coroutine.h
+++ b/include/qemu/coroutine.h
@@ -XXX,XX +XXX,XX @@ void qemu_co_rwlock_init(CoRwlock *lock);
  * of a parallel writer, control is transferred to the caller of the current
  * coroutine.
  */
-void qemu_co_rwlock_rdlock(CoRwlock *lock);
+void coroutine_fn qemu_co_rwlock_rdlock(CoRwlock *lock);
 
 /**
  * Write Locks the CoRwlock from a reader.  This is a bit more efficient than
@@ -XXX,XX +XXX,XX @@ void qemu_co_rwlock_rdlock(CoRwlock *lock);
  * to the caller of the current coroutine; another writer might run while
  * @qemu_co_rwlock_upgrade blocks.
  */
-void qemu_co_rwlock_upgrade(CoRwlock *lock);
+void coroutine_fn qemu_co_rwlock_upgrade(CoRwlock *lock);
 
 /**
  * Downgrades a write-side critical section to a reader.  Downgrading with
@@ -XXX,XX +XXX,XX @@ void qemu_co_rwlock_upgrade(CoRwlock *lock);
  * followed by @qemu_co_rwlock_rdlock.  This makes it more efficient, but
  * may also sometimes be necessary for correctness.
  */
-void qemu_co_rwlock_downgrade(CoRwlock *lock);
+void coroutine_fn qemu_co_rwlock_downgrade(CoRwlock *lock);
 
 /**
  * Write Locks the mutex. If the lock cannot be taken immediately because
  * of a parallel reader, control is transferred to the caller of the current
  * coroutine.
  */
-void qemu_co_rwlock_wrlock(CoRwlock *lock);
+void coroutine_fn qemu_co_rwlock_wrlock(CoRwlock *lock);
 
 /**
  * Unlocks the read/write lock and schedules the next coroutine that was
  * waiting for this lock to be run.
  */
-void qemu_co_rwlock_unlock(CoRwlock *lock);
+void coroutine_fn qemu_co_rwlock_unlock(CoRwlock *lock);
 
 typedef struct QemuCoSleep {
     Coroutine *to_wake;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-8-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/qemu/coroutine.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h
index XXXXXXX..XXXXXXX 100644
--- a/include/qemu/coroutine.h
+++ b/include/qemu/coroutine.h
@@ -XXX,XX +XXX,XX @@ void qemu_coroutine_dec_pool_size(unsigned int additional_pool_size);
  * The same interface as qemu_sendv_recvv(), with added yielding.
  * XXX should mark these as coroutine_fn
  */
-ssize_t qemu_co_sendv_recvv(int sockfd, struct iovec *iov, unsigned iov_cnt,
-                            size_t offset, size_t bytes, bool do_send);
+ssize_t coroutine_fn qemu_co_sendv_recvv(int sockfd, struct iovec *iov,
+                                         unsigned iov_cnt, size_t offset,
+                                         size_t bytes, bool do_send);
 #define qemu_co_recvv(sockfd, iov, iov_cnt, offset, bytes) \
   qemu_co_sendv_recvv(sockfd, iov, iov_cnt, offset, bytes, false)
 #define qemu_co_sendv(sockfd, iov, iov_cnt, offset, bytes) \
@@ -XXX,XX +XXX,XX @@ ssize_t qemu_co_sendv_recvv(int sockfd, struct iovec *iov, unsigned iov_cnt,
 /**
  * The same as above, but with just a single buffer
  */
-ssize_t qemu_co_send_recv(int sockfd, void *buf, size_t bytes, bool do_send);
+ssize_t coroutine_fn qemu_co_send_recv(int sockfd, void *buf, size_t bytes,
+                                       bool do_send);
 #define qemu_co_recv(sockfd, buf, bytes) \
   qemu_co_send_recv(sockfd, buf, bytes, false)
 #define qemu_co_send(sockfd, buf, bytes) \
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-9-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.h                    | 14 +++++++-------
 include/block/block_int-common.h | 12 +++++-------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -XXX,XX +XXX,XX @@ int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp);
 bool qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
                                           bool release_stored, Error **errp);
 int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp);
-bool qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
-                                         const char *name,
-                                         uint32_t granularity,
-                                         Error **errp);
-int qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs,
-                                            const char *name,
-                                            Error **errp);
+bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
+                                                      const char *name,
+                                                      uint32_t granularity,
+                                                      Error **errp);
+int coroutine_fn qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs,
+                                                         const char *name,
+                                                         Error **errp);
 bool qcow2_supports_persistent_dirty_bitmap(BlockDriverState *bs);
 uint64_t qcow2_get_persistent_dirty_bitmap_size(BlockDriverState *bs,
                                                 uint32_t cluster_size);
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -XXX,XX +XXX,XX @@ struct BlockDriver {
     void coroutine_fn (*bdrv_co_drain_end)(BlockDriverState *bs);
 
     bool (*bdrv_supports_persistent_dirty_bitmap)(BlockDriverState *bs);
-    bool (*bdrv_co_can_store_new_dirty_bitmap)(BlockDriverState *bs,
-                                               const char *name,
-                                               uint32_t granularity,
-                                               Error **errp);
-    int (*bdrv_co_remove_persistent_dirty_bitmap)(BlockDriverState *bs,
-                                                  const char *name,
-                                                  Error **errp);
+    bool coroutine_fn (*bdrv_co_can_store_new_dirty_bitmap)(
+        BlockDriverState *bs, const char *name, uint32_t granularity,
+        Error **errp);
+    int coroutine_fn (*bdrv_co_remove_persistent_dirty_bitmap)(
+        BlockDriverState *bs, const char *name, Error **errp);
 };
 
 static inline bool block_driver_can_compress(BlockDriver *drv)
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-10-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -XXX,XX +XXX,XX @@ static int64_t qcow2_check_vmstate_request(BlockDriverState *bs,
     return pos;
 }
 
-static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
-                              int64_t pos)
+static coroutine_fn int qcow2_save_vmstate(BlockDriverState *bs,
+                                           QEMUIOVector *qiov, int64_t pos)
 {
     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
     if (offset < 0) {
@@ -XXX,XX +XXX,XX @@ static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
     return bs->drv->bdrv_co_pwritev_part(bs, offset, qiov->size, qiov, 0, 0);
 }
 
-static int qcow2_load_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
-                              int64_t pos)
+static coroutine_fn int qcow2_load_vmstate(BlockDriverState *bs,
+                                           QEMUIOVector *qiov, int64_t pos)
 {
     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
     if (offset < 0) {
-- 
2.37.3

From: Paolo Bonzini <pbonzini@redhat.com>

get_cluster_offset() and decompress_cluster() are only called from
the read and write paths.

The validity of these was double-checked with Alberto Faria's static analyzer.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-12-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/block/qcow.c b/block/qcow.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -XXX,XX +XXX,XX @@ typedef struct BDRVQcowState {
 
 static QemuOptsList qcow_create_opts;
 
-static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
+static int coroutine_fn decompress_cluster(BlockDriverState *bs,
+                                           uint64_t cluster_offset);
 
 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
@@ -XXX,XX +XXX,XX @@ static int qcow_reopen_prepare(BDRVReopenState *state,
  * return 0 if not allocated, 1 if *result is assigned, and negative
  * errno on failure.
  */
-static int get_cluster_offset(BlockDriverState *bs,
-                              uint64_t offset, int allocate,
-                              int compressed_size,
-                              int n_start, int n_end, uint64_t *result)
+static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
+                                           uint64_t offset, int allocate,
+                                           int compressed_size,
+                                           int n_start, int n_end,
+                                           uint64_t *result)
 {
     BDRVQcowState *s = bs->opaque;
     int min_index, i, j, l1_index, l2_index, ret;
@@ -XXX,XX +XXX,XX @@ static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
     return 0;
 }
 
-static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
+static int coroutine_fn decompress_cluster(BlockDriverState *bs,
+                                           uint64_t cluster_offset)
 {
     BDRVQcowState *s = bs->opaque;
     int ret, csize;
-- 
2.37.3

From: Paolo Bonzini <pbonzini@redhat.com>

The validity of these was double-checked with Alberto Faria's static
analyzer.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-13-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.h          | 18 +++++++++---------
 block/qcow2-bitmap.c   |  4 ++--
 block/qcow2-cluster.c  | 21 ++++++++++++---------
 block/qcow2-refcount.c |  8 ++++----
 4 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -XXX,XX +XXX,XX @@ int qcow2_validate_table(BlockDriverState *bs, uint64_t offset,
                          Error **errp);
 
 /* qcow2-refcount.c functions */
-int qcow2_refcount_init(BlockDriverState *bs);
+int coroutine_fn qcow2_refcount_init(BlockDriverState *bs);
 void qcow2_refcount_close(BlockDriverState *bs);
 
 int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index,
@@ -XXX,XX +XXX,XX @@ int qcow2_inc_refcounts_imrt(BlockDriverState *bs, BdrvCheckResult *res,
 int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
                                 BlockDriverAmendStatusCB *status_cb,
                                 void *cb_opaque, Error **errp);
-int qcow2_shrink_reftable(BlockDriverState *bs);
+int coroutine_fn qcow2_shrink_reftable(BlockDriverState *bs);
 int64_t qcow2_get_last_cluster(BlockDriverState *bs, int64_t size);
 int coroutine_fn qcow2_detect_metadata_preallocation(BlockDriverState *bs);
 
 /* qcow2-cluster.c functions */
 int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
                         bool exact_size);
-int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t max_size);
+int coroutine_fn qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t max_size);
 int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
 int qcow2_encrypt_sectors(BDRVQcow2State *s, int64_t sector_num,
                           uint8_t *buf, int nb_sectors, bool enc, Error **errp);
@@ -XXX,XX +XXX,XX @@ int qcow2_get_host_offset(BlockDriverState *bs, uint64_t offset,
 int coroutine_fn qcow2_alloc_host_offset(BlockDriverState *bs, uint64_t offset,
                                          unsigned int *bytes,
                                          uint64_t *host_offset, QCowL2Meta **m);
-int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
-                                          uint64_t offset,
-                                          int compressed_size,
-                                          uint64_t *host_offset);
+int coroutine_fn qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
+                                                       uint64_t offset,
+                                                       int compressed_size,
+                                                       uint64_t *host_offset);
 void qcow2_parse_compressed_l2_entry(BlockDriverState *bs, uint64_t l2_entry,
                                      uint64_t *coffset, int *csize);
 
@@ -XXX,XX +XXX,XX @@ void qcow2_cache_discard(Qcow2Cache *c, void *table);
 int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
                                   void **refcount_table,
                                   int64_t *refcount_table_size);
-bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, bool *header_updated,
-                              Error **errp);
+bool coroutine_fn qcow2_load_dirty_bitmaps(BlockDriverState *bs,
+                                           bool *header_updated, Error **errp);
 bool qcow2_get_bitmap_info_list(BlockDriverState *bs,
                                 Qcow2BitmapInfoList **info_list, Error **errp);
 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -XXX,XX +XXX,XX @@ static void set_readonly_helper(gpointer bitmap, gpointer value)
  * If header_updated is not NULL then it is set appropriately regardless of
  * the return value.
  */
-bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, bool *header_updated,
-                              Error **errp)
+bool coroutine_fn qcow2_load_dirty_bitmaps(BlockDriverState *bs,
+                                           bool *header_updated, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     Qcow2BitmapList *bm_list;
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -XXX,XX +XXX,XX @@
 #include "qemu/memalign.h"
 #include "trace.h"
 
-int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size)
+int coroutine_fn qcow2_shrink_l1_table(BlockDriverState *bs,
+                                       uint64_t exact_size)
 {
     BDRVQcow2State *s = bs->opaque;
     int new_l1_size, i, ret;
@@ -XXX,XX +XXX,XX @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
  *
  * Return 0 on success and -errno in error cases
  */
-int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
-                                          uint64_t offset,
-                                          int compressed_size,
-                                          uint64_t *host_offset)
+int coroutine_fn qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
+                                                       uint64_t offset,
+                                                       int compressed_size,
+                                                       uint64_t *host_offset)
 {
     BDRVQcow2State *s = bs->opaque;
     int l2_index, ret;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn handle_dependencies(BlockDriverState *bs,
  *
  *  -errno: in error cases
  */
-static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
-    uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
+static int coroutine_fn handle_copied(BlockDriverState *bs,
+    uint64_t guest_offset, uint64_t *host_offset, uint64_t *bytes,
+    QCowL2Meta **m)
 {
     BDRVQcow2State *s = bs->opaque;
     int l2_index;
@@ -XXX,XX +XXX,XX @@ static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
  *
  *  -errno: in error cases
  */
-static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
-    uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
+static int coroutine_fn handle_alloc(BlockDriverState *bs,
+    uint64_t guest_offset, uint64_t *host_offset, uint64_t *bytes,
+    QCowL2Meta **m)
 {
     BDRVQcow2State *s = bs->opaque;
     int l2_index;
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -XXX,XX +XXX,XX @@ static void update_max_refcount_table_index(BDRVQcow2State *s)
     s->max_refcount_table_index = i;
 }
 
-int qcow2_refcount_init(BlockDriverState *bs)
+int coroutine_fn qcow2_refcount_init(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     unsigned int refcount_table_size2, i;
@@ -XXX,XX +XXX,XX @@ static int64_t get_refblock_offset(BlockDriverState *bs, uint64_t offset)
     return covering_refblock_offset;
 }
 
-static int qcow2_discard_refcount_block(BlockDriverState *bs,
-                                        uint64_t discard_block_offs)
+static int coroutine_fn
+qcow2_discard_refcount_block(BlockDriverState *bs, uint64_t discard_block_offs)
 {
     BDRVQcow2State *s = bs->opaque;
     int64_t refblock_offs;
@@ -XXX,XX +XXX,XX @@ static int qcow2_discard_refcount_block(BlockDriverState *bs,
     return 0;
 }
 
-int qcow2_shrink_reftable(BlockDriverState *bs)
+int coroutine_fn qcow2_shrink_reftable(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t *reftable_tmp =
-- 
2.37.3

From: Paolo Bonzini <pbonzini@redhat.com>

The validity of these was double-checked with Alberto Faria's static analyzer.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-14-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vmdk.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -XXX,XX +XXX,XX @@ static void vmdk_refresh_limits(BlockDriverState *bs, Error **errp)
  * [@skip_start_sector, @skip_end_sector) is not copied or written, and leave
  * it for call to write user data in the request.
  */
-static int get_whole_cluster(BlockDriverState *bs,
-                             VmdkExtent *extent,
-                             uint64_t cluster_offset,
-                             uint64_t offset,
-                             uint64_t skip_start_bytes,
-                             uint64_t skip_end_bytes,
-                             bool zeroed)
+static int coroutine_fn get_whole_cluster(BlockDriverState *bs,
+                                          VmdkExtent *extent,
+                                          uint64_t cluster_offset,
+                                          uint64_t offset,
+                                          uint64_t skip_start_bytes,
+                                          uint64_t skip_end_bytes,
+                                          bool zeroed)
 {
     int ret = VMDK_OK;
     int64_t cluster_bytes;
@@ -XXX,XX +XXX,XX @@ exit:
     return ret;
 }
 
-static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data,
-                         uint32_t offset)
+static int coroutine_fn vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data,
+                                      uint32_t offset)
 {
     offset = cpu_to_le32(offset);
     /* update L2 table */
@@ -XXX,XX +XXX,XX @@ static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data,
  *          VMDK_UNALLOC if cluster is not mapped and @allocate is false.
  *          VMDK_ERROR if failed.
  */
-static int get_cluster_offset(BlockDriverState *bs,
-                              VmdkExtent *extent,
-                              VmdkMetaData *m_data,
-                              uint64_t offset,
-                              bool allocate,
-                              uint64_t *cluster_offset,
-                              uint64_t skip_start_bytes,
-                              uint64_t skip_end_bytes)
+static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
+                                           VmdkExtent *extent,
+                                           VmdkMetaData *m_data,
+                                           uint64_t offset,
+                                           bool allocate,
+                                           uint64_t *cluster_offset,
+                                           uint64_t skip_start_bytes,
+                                           uint64_t skip_end_bytes)
 {
     unsigned int l1_index, l2_offset, l2_index;
     int min_index, i, j;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-16-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c    | 2 +-
 block/io.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ create_file_fallback_zero_first_sector(BlockBackend *blk,
 
     bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
     if (bytes_to_clear) {
-        ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
+        ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
         if (ret < 0) {
             error_setg_errno(errp, -ret,
                              "Failed to clear the new image's first sector");
diff --git a/block/io.c b/block/io.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io.c
+++ b/block/io.c
@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset,
         return 1;
     }
 
-    ret = bdrv_common_block_status_above(bs, NULL, false, false, offset,
-                                         bytes, &pnum, NULL, NULL, NULL);
+    ret = bdrv_co_common_block_status_above(bs, NULL, false, false, offset,
+                                            bytes, &pnum, NULL, NULL, NULL);
 
     if (ret < 0) {
         return ret;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-17-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/mirror.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index XXXXXXX..XXXXXXX 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
      * active layer. */
     if (s->base == blk_bs(s->target)) {
         if (s->bdev_length > target_length) {
-            ret = blk_truncate(s->target, s->bdev_length, false,
-                               PREALLOC_MODE_OFF, 0, NULL);
+            ret = blk_co_truncate(s->target, s->bdev_length, false,
+                                  PREALLOC_MODE_OFF, 0, NULL);
             if (ret < 0) {
                 goto immediate_exit;
             }
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-18-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/parallels.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/block/parallels.c b/block/parallels.c
index XXXXXXX..XXXXXXX 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -XXX,XX +XXX,XX @@ static coroutine_fn int64_t allocate_clusters(BlockDriverState *bs,
          * force the safer-but-slower fallocate.
          */
         if (s->prealloc_mode == PRL_PREALLOC_MODE_TRUNCATE) {
-            ret = bdrv_truncate(bs->file,
-                                (s->data_end + space) << BDRV_SECTOR_BITS,
-                                false, PREALLOC_MODE_OFF, BDRV_REQ_ZERO_WRITE,
-                                NULL);
+            ret = bdrv_co_truncate(bs->file,
+                                   (s->data_end + space) << BDRV_SECTOR_BITS,
+                                   false, PREALLOC_MODE_OFF,
+                                   BDRV_REQ_ZERO_WRITE, NULL);
             if (ret == -ENOTSUP) {
                 s->prealloc_mode = PRL_PREALLOC_MODE_FALLOCATE;
             }
         }
         if (s->prealloc_mode == PRL_PREALLOC_MODE_FALLOCATE) {
-            ret = bdrv_pwrite_zeroes(bs->file,
-                                     s->data_end << BDRV_SECTOR_BITS,
-                                     space << BDRV_SECTOR_BITS, 0);
+            ret = bdrv_co_pwrite_zeroes(bs->file,
+                                        s->data_end << BDRV_SECTOR_BITS,
+                                        space << BDRV_SECTOR_BITS, 0);
         }
         if (ret < 0) {
             return ret;
@@ -XXX,XX +XXX,XX @@ static coroutine_fn int parallels_co_flush_to_os(BlockDriverState *bs)
         if (off + to_write > s->header_size) {
             to_write = s->header_size - off;
         }
-        ret = bdrv_pwrite(bs->file, off, to_write, (uint8_t *)s->header + off,
-                          0);
+        ret = bdrv_co_pwrite(bs->file, off, to_write,
+                             (uint8_t *)s->header + off, 0);
         if (ret < 0) {
             qemu_co_mutex_unlock(&s->lock);
             return ret;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn parallels_co_check(BlockDriverState *bs,
              * In order to really repair the image, we must shrink it.
              * That means we have to pass exact=true.
              */
-            ret = bdrv_truncate(bs->file, res->image_end_offset, true,
-                                PREALLOC_MODE_OFF, 0, &local_err);
+            ret = bdrv_co_truncate(bs->file, res->image_end_offset, true,
+                                   PREALLOC_MODE_OFF, 0, &local_err);
             if (ret < 0) {
                 error_report_err(local_err);
                 res->check_errors++;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn parallels_co_create(BlockdevCreateOptions* opts,
     memset(tmp, 0, sizeof(tmp));
     memcpy(tmp, &header, sizeof(header));
 
-    ret = blk_pwrite(blk, 0, BDRV_SECTOR_SIZE, tmp, 0);
+    ret = blk_co_pwrite(blk, 0, BDRV_SECTOR_SIZE, tmp, 0);
     if (ret < 0) {
         goto exit;
     }
-    ret = blk_pwrite_zeroes(blk, BDRV_SECTOR_SIZE,
-                            (bat_sectors - 1) << BDRV_SECTOR_BITS, 0);
+    ret = blk_co_pwrite_zeroes(blk, BDRV_SECTOR_SIZE,
+                               (bat_sectors - 1) << BDRV_SECTOR_BITS, 0);
     if (ret < 0) {
         goto exit;
     }
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-19-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow.c | 45 +++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/block/qcow.c b/block/qcow.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
         s->l1_table[l1_index] = l2_offset;
         tmp = cpu_to_be64(l2_offset);
         BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
-        ret = bdrv_pwrite_sync(bs->file,
-                               s->l1_table_offset + l1_index * sizeof(tmp),
-                               sizeof(tmp), &tmp, 0);
+        ret = bdrv_co_pwrite_sync(bs->file,
+                                  s->l1_table_offset + l1_index * sizeof(tmp),
+                                  sizeof(tmp), &tmp, 0);
         if (ret < 0) {
             return ret;
         }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
     BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
     if (new_l2_table) {
         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
-        ret = bdrv_pwrite_sync(bs->file, l2_offset,
-                               s->l2_size * sizeof(uint64_t), l2_table, 0);
+        ret = bdrv_co_pwrite_sync(bs->file, l2_offset,
+                                  s->l2_size * sizeof(uint64_t), l2_table, 0);
         if (ret < 0) {
             return ret;
         }
     } else {
-        ret = bdrv_pread(bs->file, l2_offset, s->l2_size * sizeof(uint64_t),
-                         l2_table, 0);
+        ret = bdrv_co_pread(bs->file, l2_offset,
+                            s->l2_size * sizeof(uint64_t), l2_table, 0);
         if (ret < 0) {
             return ret;
         }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
             cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
             /* write the cluster content */
             BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
-            ret = bdrv_pwrite(bs->file, cluster_offset, s->cluster_size,
-                              s->cluster_cache, 0);
+            ret = bdrv_co_pwrite(bs->file, cluster_offset, s->cluster_size,
+                                 s->cluster_cache, 0);
             if (ret < 0) {
                 return ret;
             }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
                 if (cluster_offset + s->cluster_size > INT64_MAX) {
                     return -E2BIG;
                 }
-                ret = bdrv_truncate(bs->file, cluster_offset + s->cluster_size,
-                                    false, PREALLOC_MODE_OFF, 0, NULL);
+                ret = bdrv_co_truncate(bs->file,
+                                       cluster_offset + s->cluster_size,
+                                       false, PREALLOC_MODE_OFF, 0, NULL);
                 if (ret < 0) {
                     return ret;
                 }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
                                 return -EIO;
                             }
                             BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
-                            ret = bdrv_pwrite(bs->file, cluster_offset + i,
-                                              BDRV_SECTOR_SIZE,
-                                              s->cluster_data, 0);
+                            ret = bdrv_co_pwrite(bs->file, cluster_offset + i,
+                                                 BDRV_SECTOR_SIZE,
+                                                 s->cluster_data, 0);
                             if (ret < 0) {
                                 return ret;
                             }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
         } else {
             BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
         }
-        ret = bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
-                               sizeof(tmp), &tmp, 0);
+        ret = bdrv_co_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
+                                  sizeof(tmp), &tmp, 0);
         if (ret < 0) {
             return ret;
         }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn decompress_cluster(BlockDriverState *bs,
         csize = cluster_offset >> (63 - s->cluster_bits);
         csize &= (s->cluster_size - 1);
         BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
-        ret = bdrv_pread(bs->file, coffset, csize, s->cluster_data, 0);
+        ret = bdrv_co_pread(bs->file, coffset, csize, s->cluster_data, 0);
         if (ret < 0)
             return -1;
         if (decompress_buffer(s->cluster_cache, s->cluster_size,
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow_co_create(BlockdevCreateOptions *opts,
     }
 
     /* write all the data */
-    ret = blk_pwrite(qcow_blk, 0, sizeof(header), &header, 0);
+    ret = blk_co_pwrite(qcow_blk, 0, sizeof(header), &header, 0);
     if (ret < 0) {
         goto exit;
     }
 
     if (qcow_opts->has_backing_file) {
-        ret = blk_pwrite(qcow_blk, sizeof(header), backing_filename_len,
-                         qcow_opts->backing_file, 0);
+        ret = blk_co_pwrite(qcow_blk, sizeof(header), backing_filename_len,
+                            qcow_opts->backing_file, 0);
         if (ret < 0) {
             goto exit;
         }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow_co_create(BlockdevCreateOptions *opts,
     tmp = g_malloc0(BDRV_SECTOR_SIZE);
     for (i = 0; i < DIV_ROUND_UP(sizeof(uint64_t) * l1_size, BDRV_SECTOR_SIZE);
          i++) {
-        ret = blk_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
-                         BDRV_SECTOR_SIZE, tmp, 0);
+        ret = blk_co_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
+                            BDRV_SECTOR_SIZE, tmp, 0);
         if (ret < 0) {
             g_free(tmp);
             goto exit;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-20-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-cluster.c  |  8 ++++----
 block/qcow2-refcount.c | 10 +++++-----
 block/qcow2-snapshot.c |  6 +++---
 block/qcow2.c          | 24 ++++++++++++------------
 4 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -XXX,XX +XXX,XX @@ int coroutine_fn qcow2_shrink_l1_table(BlockDriverState *bs,
 #endif
 
     BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE);
-    ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset +
-                                       new_l1_size * L1E_SIZE,
-                             (s->l1_size - new_l1_size) * L1E_SIZE, 0);
+    ret = bdrv_co_pwrite_zeroes(bs->file,
+                                s->l1_table_offset + new_l1_size * L1E_SIZE,
+                                (s->l1_size - new_l1_size) * L1E_SIZE, 0);
     if (ret < 0) {
         goto fail;
     }
 
-    ret = bdrv_flush(bs->file->bs);
+    ret = bdrv_co_flush(bs->file->bs);
     if (ret < 0) {
         goto fail;
     }
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -XXX,XX +XXX,XX @@ int coroutine_fn qcow2_refcount_init(BlockDriverState *bs)
             goto fail;
         }
         BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD);
-        ret = bdrv_pread(bs->file, s->refcount_table_offset,
-                         refcount_table_size2, s->refcount_table, 0);
+        ret = bdrv_co_pread(bs->file, s->refcount_table_offset,
+                            refcount_table_size2, s->refcount_table, 0);
         if (ret < 0) {
             goto fail;
         }
@@ -XXX,XX +XXX,XX @@ int coroutine_fn qcow2_shrink_reftable(BlockDriverState *bs)
         reftable_tmp[i] = unused_block ? 0 : cpu_to_be64(s->refcount_table[i]);
     }
 
-    ret = bdrv_pwrite_sync(bs->file, s->refcount_table_offset,
-                           s->refcount_table_size * REFTABLE_ENTRY_SIZE,
-                           reftable_tmp, 0);
+    ret = bdrv_co_pwrite_sync(bs->file, s->refcount_table_offset,
+                              s->refcount_table_size * REFTABLE_ENTRY_SIZE,
+                              reftable_tmp, 0);
     /*
      * If the write in the reftable failed the image may contain a partially
      * overwritten reftable. In this case it would be better to clear the
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -XXX,XX +XXX,XX @@ int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs,
     } QEMU_PACKED snapshot_table_pointer;
 
     /* qcow2_do_open() discards this information in check mode */
-    ret = bdrv_pread(bs->file, offsetof(QCowHeader, nb_snapshots),
-                     sizeof(snapshot_table_pointer), &snapshot_table_pointer,
-                     0);
+    ret = bdrv_co_pread(bs->file, offsetof(QCowHeader, nb_snapshots),
+                        sizeof(snapshot_table_pointer), &snapshot_table_pointer,
+                        0);
     if (ret < 0) {
         result->check_errors++;
         fprintf(stderr, "ERROR failed to read the snapshot table pointer from "
diff --git a/block/qcow2.c b/block/qcow2.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
     uint64_t l1_vm_state_index;
     bool update_header = false;
 
-    ret = bdrv_pread(bs->file, 0, sizeof(header), &header, 0);
+    ret = bdrv_co_pread(bs->file, 0, sizeof(header), &header, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not read qcow2 header");
         goto fail;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
     if (header.header_length > sizeof(header)) {
         s->unknown_header_fields_size = header.header_length - sizeof(header);
         s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
-        ret = bdrv_pread(bs->file, sizeof(header),
-                         s->unknown_header_fields_size,
-                         s->unknown_header_fields, 0);
+        ret = bdrv_co_pread(bs->file, sizeof(header),
+                            s->unknown_header_fields_size,
+                            s->unknown_header_fields, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not read unknown qcow2 header "
                              "fields");
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
             ret = -ENOMEM;
             goto fail;
         }
-        ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_size * L1E_SIZE,
-                         s->l1_table, 0);
+        ret = bdrv_co_pread(bs->file, s->l1_table_offset, s->l1_size * L1E_SIZE,
+                            s->l1_table, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not read L1 table");
             goto fail;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
         }
 
         s->image_backing_file = g_malloc(len + 1);
-        ret = bdrv_pread(bs->file, header.backing_file_offset, len,
-                         s->image_backing_file, 0);
+        ret = bdrv_co_pread(bs->file, header.backing_file_offset, len,
+                            s->image_backing_file, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not read backing file name");
             goto fail;
@@ -XXX,XX +XXX,XX @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
             cpu_to_be64(QCOW2_INCOMPAT_EXTL2);
     }
 
-    ret = blk_pwrite(blk, 0, cluster_size, header, 0);
+    ret = blk_co_pwrite(blk, 0, cluster_size, header, 0);
     g_free(header);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write qcow2 header");
@@ -XXX,XX +XXX,XX @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
     /* Write a refcount table with one refcount block */
     refcount_table = g_malloc0(2 * cluster_size);
     refcount_table[0] = cpu_to_be64(2 * cluster_size);
-    ret = blk_pwrite(blk, cluster_size, 2 * cluster_size, refcount_table, 0);
+    ret = blk_co_pwrite(blk, cluster_size, 2 * cluster_size, refcount_table, 0);
     g_free(refcount_table);
 
     if (ret < 0) {
@@ -XXX,XX +XXX,XX @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
     }
 
     /* Okay, now that we have a valid image, let's give it the right size */
-    ret = blk_truncate(blk, qcow2_opts->size, false, qcow2_opts->preallocation,
-                       0, errp);
+    ret = blk_co_truncate(blk, qcow2_opts->size, false,
+                          qcow2_opts->preallocation, 0, errp);
     if (ret < 0) {
         error_prepend(errp, "Could not resize image: ");
         goto out;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-21-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qed-table.c |  2 +-
 block/qed.c       | 12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/block/qed-table.c b/block/qed-table.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qed-table.c
+++ b/block/qed-table.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qed_write_table(BDRVQEDState *s, uint64_t offset,
     }
 
     if (flush) {
-        ret = bdrv_flush(s->bs);
+        ret = bdrv_co_flush(s->bs);
         if (ret < 0) {
             goto out;
         }
diff --git a/block/qed.c b/block/qed.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,
     int64_t file_size;
     int ret;
 
-    ret = bdrv_pread(bs->file, 0, sizeof(le_header), &le_header, 0);
+    ret = bdrv_co_pread(bs->file, 0, sizeof(le_header), &le_header, 0);
     if (ret < 0) {
         error_setg(errp, "Failed to read QED header");
         return ret;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,
         }
 
         /* From here on only known autoclear feature bits are valid */
-        bdrv_flush(bs->file->bs);
+        bdrv_co_flush(bs->file->bs);
     }
 
     s->l1_table = qed_alloc_table(s);
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn bdrv_qed_co_create(BlockdevCreateOptions *opts,
      * The QED format associates file length with allocation status,
      * so a new file (which is empty) must have a length of 0.
      */
-    ret = blk_truncate(blk, 0, true, PREALLOC_MODE_OFF, 0, errp);
+    ret = blk_co_truncate(blk, 0, true, PREALLOC_MODE_OFF, 0, errp);
     if (ret < 0) {
         goto out;
     }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn bdrv_qed_co_create(BlockdevCreateOptions *opts,
     }
 
     qed_header_cpu_to_le(&header, &le_header);
-    ret = blk_pwrite(blk, 0, sizeof(le_header), &le_header, 0);
+    ret = blk_co_pwrite(blk, 0, sizeof(le_header), &le_header, 0);
     if (ret < 0) {
         goto out;
     }
-    ret = blk_pwrite(blk, sizeof(le_header), header.backing_filename_size,
+    ret = blk_co_pwrite(blk, sizeof(le_header), header.backing_filename_size,
                      qed_opts->backing_file, 0);
     if (ret < 0) {
         goto out;
     }
 
     l1_table = g_malloc0(l1_size);
-    ret = blk_pwrite(blk, header.l1_table_offset, l1_size, l1_table, 0);
+    ret = blk_co_pwrite(blk, header.l1_table_offset, l1_size, l1_table, 0);
     if (ret < 0) {
         goto out;
     }
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-22-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vdi.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -XXX,XX +XXX,XX @@ vdi_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
              * so this full-cluster write does not overlap a partial write
              * of the same cluster, issued from the "else" branch.
              */
-            ret = bdrv_pwrite(bs->file, data_offset, s->block_size, block, 0);
+            ret = bdrv_co_pwrite(bs->file, data_offset, s->block_size, block,
+                                 0);
             qemu_co_rwlock_unlock(&s->bmap_lock);
         } else {
 nonallocating_write:
@@ -XXX,XX +XXX,XX @@ nonallocating_write:
         assert(VDI_IS_ALLOCATED(bmap_first));
         *header = s->header;
         vdi_header_to_le(header);
-        ret = bdrv_pwrite(bs->file, 0, sizeof(*header), header, 0);
+        ret = bdrv_co_pwrite(bs->file, 0, sizeof(*header), header, 0);
         g_free(header);
 
         if (ret < 0) {
@@ -XXX,XX +XXX,XX @@ nonallocating_write:
         base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
         logout("will write %u block map sectors starting from entry %u\n",
                n_sectors, bmap_first);
-        ret = bdrv_pwrite(bs->file, offset * SECTOR_SIZE,
-                          n_sectors * SECTOR_SIZE, base, 0);
+        ret = bdrv_co_pwrite(bs->file, offset * SECTOR_SIZE,
+                             n_sectors * SECTOR_SIZE, base, 0);
     }
 
     return ret;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
         vdi_header_print(&header);
     }
     vdi_header_to_le(&header);
-    ret = blk_pwrite(blk, offset, sizeof(header), &header, 0);
+    ret = blk_co_pwrite(blk, offset, sizeof(header), &header, 0);
     if (ret < 0) {
         error_setg(errp, "Error writing header");
         goto exit;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
                 bmap[i] = VDI_UNALLOCATED;
             }
         }
-        ret = blk_pwrite(blk, offset, bmap_size, bmap, 0);
+        ret = blk_co_pwrite(blk, offset, bmap_size, bmap, 0);
         if (ret < 0) {
             error_setg(errp, "Error writing bmap");
             goto exit;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
     }
 
     if (image_type == VDI_TYPE_STATIC) {
-        ret = blk_truncate(blk, offset + blocks * block_size, false,
-                           PREALLOC_MODE_OFF, 0, errp);
+        ret = blk_co_truncate(blk, offset + blocks * block_size, false,
+                              PREALLOC_MODE_OFF, 0, errp);
         if (ret < 0) {
             error_prepend(errp, "Failed to statically allocate file");
             goto exit;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-23-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vhdx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/vhdx.c b/block/vhdx.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
     creator = g_utf8_to_utf16("QEMU v" QEMU_VERSION, -1, NULL,
                               &creator_items, NULL);
     signature = cpu_to_le64(VHDX_FILE_SIGNATURE);
-    ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET, sizeof(signature), &signature,
-                     0);
+    ret = blk_co_pwrite(blk, VHDX_FILE_ID_OFFSET, sizeof(signature), &signature,
+                        0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to write file signature");
         goto delete_and_exit;
     }
     if (creator) {
-        ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET + sizeof(signature),
-                         creator_items * sizeof(gunichar2), creator, 0);
+        ret = blk_co_pwrite(blk, VHDX_FILE_ID_OFFSET + sizeof(signature),
+                            creator_items * sizeof(gunichar2), creator, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to write creator field");
             goto delete_and_exit;
-- 
2.37.3

From: Alberto Faria <afaria@redhat.com>

Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-24-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vmdk.c | 54 ++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index XXXXXXX..XXXXXXX 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_whole_cluster(BlockDriverState *bs,
         if (copy_from_backing) {
             /* qcow2 emits this on bs->file instead of bs->backing */
             BLKDBG_EVENT(extent->file, BLKDBG_COW_READ);
-            ret = bdrv_pread(bs->backing, offset, skip_start_bytes,
-                             whole_grain, 0);
+            ret = bdrv_co_pread(bs->backing, offset, skip_start_bytes,
+                                whole_grain, 0);
             if (ret < 0) {
                 ret = VMDK_ERROR;
                 goto exit;
             }
         }
         BLKDBG_EVENT(extent->file, BLKDBG_COW_WRITE);
-        ret = bdrv_pwrite(extent->file, cluster_offset, skip_start_bytes,
-                          whole_grain, 0);
+        ret = bdrv_co_pwrite(extent->file, cluster_offset, skip_start_bytes,
+                             whole_grain, 0);
         if (ret < 0) {
             ret = VMDK_ERROR;
             goto exit;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_whole_cluster(BlockDriverState *bs,
         if (copy_from_backing) {
             /* qcow2 emits this on bs->file instead of bs->backing */
             BLKDBG_EVENT(extent->file, BLKDBG_COW_READ);
-            ret = bdrv_pread(bs->backing, offset + skip_end_bytes,
-                             cluster_bytes - skip_end_bytes,
-                             whole_grain + skip_end_bytes, 0);
+            ret = bdrv_co_pread(bs->backing, offset + skip_end_bytes,
+                                cluster_bytes - skip_end_bytes,
+                                whole_grain + skip_end_bytes, 0);
             if (ret < 0) {
                 ret = VMDK_ERROR;
                 goto exit;
             }
         }
         BLKDBG_EVENT(extent->file, BLKDBG_COW_WRITE);
-        ret = bdrv_pwrite(extent->file, cluster_offset + skip_end_bytes,
-                          cluster_bytes - skip_end_bytes,
-                          whole_grain + skip_end_bytes, 0);
+        ret = bdrv_co_pwrite(extent->file, cluster_offset + skip_end_bytes,
+                             cluster_bytes - skip_end_bytes,
+                             whole_grain + skip_end_bytes, 0);
         if (ret < 0) {
             ret = VMDK_ERROR;
             goto exit;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data,
     offset = cpu_to_le32(offset);
     /* update L2 table */
     BLKDBG_EVENT(extent->file, BLKDBG_L2_UPDATE);
-    if (bdrv_pwrite(extent->file,
-                ((int64_t)m_data->l2_offset * 512)
-                    + (m_data->l2_index * sizeof(offset)),
-                sizeof(offset), &offset, 0) < 0) {
+    if (bdrv_co_pwrite(extent->file,
+                       ((int64_t)m_data->l2_offset * 512)
+                           + (m_data->l2_index * sizeof(offset)),
+                       sizeof(offset), &offset, 0) < 0) {
         return VMDK_ERROR;
     }
     /* update backup L2 table */
     if (extent->l1_backup_table_offset != 0) {
         m_data->l2_offset = extent->l1_backup_table[m_data->l1_index];
-        if (bdrv_pwrite(extent->file,
-                    ((int64_t)m_data->l2_offset * 512)
-                        + (m_data->l2_index * sizeof(offset)),
-                    sizeof(offset), &offset, 0) < 0) {
+        if (bdrv_co_pwrite(extent->file,
+                           ((int64_t)m_data->l2_offset * 512)
+                               + (m_data->l2_index * sizeof(offset)),
+                           sizeof(offset), &offset, 0) < 0) {
             return VMDK_ERROR;
         }
     }
-    if (bdrv_flush(extent->file->bs) < 0) {
+    if (bdrv_co_flush(extent->file->bs) < 0) {
         return VMDK_ERROR;
     }
     if (m_data->l2_cache_entry) {
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
     }
     l2_table = (char *)extent->l2_cache + (min_index * l2_size_bytes);
     BLKDBG_EVENT(extent->file, BLKDBG_L2_LOAD);
-    if (bdrv_pread(extent->file,
+    if (bdrv_co_pread(extent->file,
                 (int64_t)l2_offset * 512,
                 l2_size_bytes,
-                l2_table,
-                0
+                l2_table, 0
             ) < 0) {
         return VMDK_ERROR;
     }
@@ -XXX,XX +XXX,XX @@ vmdk_read_extent(VmdkExtent *extent, int64_t cluster_offset,
     cluster_buf = g_malloc(buf_bytes);
     uncomp_buf = g_malloc(cluster_bytes);
     BLKDBG_EVENT(extent->file, BLKDBG_READ_COMPRESSED);
-    ret = bdrv_pread(extent->file, cluster_offset, buf_bytes, cluster_buf, 0);
+    ret = bdrv_co_pread(extent->file, cluster_offset, buf_bytes, cluster_buf,
+                        0);
     if (ret < 0) {
         goto out;
     }
@@ -XXX,XX +XXX,XX @@ vmdk_co_pwritev_compressed(BlockDriverState *bs, int64_t offset, int64_t bytes,
                 return length;
             }
             length = QEMU_ALIGN_UP(length, BDRV_SECTOR_SIZE);
-            ret = bdrv_truncate(s->extents[i].file, length, false,
-                                PREALLOC_MODE_OFF, 0, NULL);
+            ret = bdrv_co_truncate(s->extents[i].file, length, false,
+                                   PREALLOC_MODE_OFF, 0, NULL);
             if (ret < 0) {
                 return ret;
             }
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vmdk_co_do_create(int64_t size,
         desc_offset = 0x200;
     }
 
-    ret = blk_pwrite(blk, desc_offset, desc_len, desc, 0);
+    ret = blk_co_pwrite(blk, desc_offset, desc_len, desc, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write description");
         goto exit;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn vmdk_co_do_create(int64_t size,
     /* bdrv_pwrite write padding zeros to align to sector, we don't need that
      * for description file */
     if (desc_offset == 0) {
-        ret = blk_truncate(blk, desc_len, false, PREALLOC_MODE_OFF, 0, errp);
+        ret = blk_co_truncate(blk, desc_len, false, PREALLOC_MODE_OFF, 0, errp);
         if (ret < 0) {
             goto exit;
         }
-- 
2.37.3

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

blk_set_enable_write_cache() is defined as GLOBAL_STATE_CODE
but can be invoked from iothreads when handling scsi requests.
This triggers an assertion failure:

0x00007fd6c3515ce1 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 0x00007fd6c34ff537 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 0x00007fd6c34ff40f in ?? () from /lib/x86_64-linux-gnu/libc.so.6
 0x00007fd6c350e662 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
 0x000056149e2cea03 in blk_set_enable_write_cache (wce=true, blk=0x5614a01c27f0)
   at ../src/block/block-backend.c:1949
 0x000056149e2d0a67 in blk_set_enable_write_cache (blk=0x5614a01c27f0,
   wce=<optimized out>) at ../src/block/block-backend.c:1951
 0x000056149dfe9c59 in scsi_disk_apply_mode_select (p=0x7fd6b400c00e "\004",
   page=<optimized out>, s=<optimized out>) at ../src/hw/scsi/scsi-disk.c:1520
 mode_select_pages (change=true, len=18, p=0x7fd6b400c00e "\004", r=0x7fd6b4001ff0)
   at ../src/hw/scsi/scsi-disk.c:1570
 scsi_disk_emulate_mode_select (inbuf=<optimized out>, r=0x7fd6b4001ff0) at
   ../src/hw/scsi/scsi-disk.c:1640
 scsi_disk_emulate_write_data (req=0x7fd6b4001ff0) at ../src/hw/scsi/scsi-disk.c:1934
 0x000056149e18ff16 in virtio_scsi_handle_cmd_req_submit (req=<optimized out>,
   req=<optimized out>, s=0x5614a12f16b0) at ../src/hw/scsi/virtio-scsi.c:719
 virtio_scsi_handle_cmd_vq (vq=0x7fd6bab92140, s=0x5614a12f16b0) at
   ../src/hw/scsi/virtio-scsi.c:761
 virtio_scsi_handle_cmd (vq=<optimized out>, vdev=<optimized out>) at
   ../src/hw/scsi/virtio-scsi.c:775
 virtio_scsi_handle_cmd (vdev=0x5614a12f16b0, vq=0x7fd6bab92140) at
   ../src/hw/scsi/virtio-scsi.c:765
 0x000056149e1a8aa6 in virtio_queue_notify_vq (vq=0x7fd6bab92140) at
   ../src/hw/virtio/virtio.c:2365
 0x000056149e3ccea5 in aio_dispatch_handler (ctx=ctx@entry=0x5614a01babe0,
   node=<optimized out>) at ../src/util/aio-posix.c:369
 0x000056149e3cd868 in aio_dispatch_ready_handlers (ready_list=0x7fd6c09b2680,
   ctx=0x5614a01babe0) at ../src/util/aio-posix.c:399
 aio_poll (ctx=0x5614a01babe0, blocking=blocking@entry=true) at
   ../src/util/aio-posix.c:713
 0x000056149e2a7796 in iothread_run (opaque=opaque@entry=0x56149ffde500) at
   ../src/iothread.c:67
 0x000056149e3d0859 in qemu_thread_start (args=0x7fd6c09b26f0) at
   ../src/util/qemu-thread-posix.c:504
 0x00007fd6c36b9ea7 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
 0x00007fd6c35d9aef in clone () from /lib/x86_64-linux-gnu/libc.so.6

Changing GLOBAL_STATE_CODE in IO_CODE is allowed, since GSC callers are
allowed to call IO_CODE.

Resolves: #1272

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20221027072726.2681500-1-eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Tested-by: Antoine Damhet <antoine.damhet@shadow.tech>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/block-backend.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index XXXXXXX..XXXXXXX 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -XXX,XX +XXX,XX @@ bool blk_enable_write_cache(BlockBackend *blk)
 
 void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
 {
-    GLOBAL_STATE_CODE();
+    IO_CODE();
     blk->enable_write_cache = wce;
 }
 
-- 
2.37.3

The following changes since commit 13356edb87506c148b163b8c7eb0695647d00c2a:

Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging (2023-01-24 09:45:33 +0000)

are available in the Git repository at:

https://repo.or.cz/qemu/kevin.git tags/for-upstream

for you to fetch changes up to d570177b50c389f379f93183155a27d44856ab46:

qemu-img: Change info key names for protocol nodes (2023-02-01 16:52:33 +0100)

v4:
- Fixed the 'qemu-img-close-errors' test case to run only on Linux and
  only with the file protocol, use qemu-io instead of truncate

v3:
- Make the compiler happier on BSD and CentOS Stream 8

v2:
- Rebased to resolve merge conflicts in coroutine.h

----------------------------------------------------------------
Block layer patches

- qemu-img info: Show protocol-level information
- Move more functions to coroutines
- Make coroutine annotations ready for static analysis
- qemu-img: Fix exit code for errors closing the image
- qcow2 bitmaps: Fix theoretical corruption in error path
- pflash: Only load non-zero parts of backend image to save memory
- Code cleanup and test case improvements

----------------------------------------------------------------
Alberto Faria (2):
      coroutine: annotate coroutine_fn for libclang
      block: Add no_coroutine_fn and coroutine_mixed_fn marker

Emanuele Giuseppe Esposito (14):
      block-coroutine-wrapper: support void functions
      block: Convert bdrv_io_plug() to co_wrapper
      block: Convert bdrv_io_unplug() to co_wrapper
      block: Convert bdrv_is_inserted() to co_wrapper
      block: Rename refresh_total_sectors to bdrv_refresh_total_sectors
      block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed
      block-backend: use bdrv_getlength instead of blk_getlength
      block: use bdrv_co_refresh_total_sectors when possible
      block: Convert bdrv_get_allocated_file_size() to co_wrapper
      block: Convert bdrv_get_info() to co_wrapper_mixed
      block: Convert bdrv_eject() to co_wrapper
      block: Convert bdrv_lock_medium() to co_wrapper
      block: Convert bdrv_debug_event() to co_wrapper_mixed
      block: Rename bdrv_load/save_vmstate() to bdrv_co_load/save_vmstate()

Hanna Reitz (12):
      block: Improve empty format-specific info dump
      block/file: Add file-specific image info
      block/vmdk: Change extent info type
      block: Split BlockNodeInfo off of ImageInfo
      qemu-img: Use BlockNodeInfo
      block/qapi: Let bdrv_query_image_info() recurse
      block/qapi: Introduce BlockGraphInfo
      block/qapi: Add indentation to bdrv_node_info_dump()
      iotests: Filter child node information
      iotests/106, 214, 308: Read only one size line
      qemu-img: Let info print block graph
      qemu-img: Change info key names for protocol nodes

Kevin Wolf (4):
      qcow2: Fix theoretical corruption in store_bitmap() error path
      qemu-img commit: Report errors while closing the image
      qemu-img bitmap: Report errors while closing the image
      qemu-iotests: Test qemu-img bitmap/commit exit code on error

Paolo Bonzini (2):
      qemu-io: do not reinvent the blk_pwrite_zeroes wheel
      block: remove bdrv_coroutine_enter

Philippe Mathieu-Daudé (1):
      block/nbd: Add missing <qemu/bswap.h> include

Thomas Huth (2):
      tests/qemu-iotests/312: Mark "quorum" as required driver
      tests/qemu-iotests/262: Check for availability of "blkverify" first

Xiang Zheng (1):
      pflash: Only read non-zero parts of backend image