bdrv_co_drain() has not been used since commit 9a0cec664eef ("mirror:
use bdrv_drained_begin/bdrv_drained_end") in 2016. Remove it so there
are fewer drain scenarios to worry about.

Use bdrv_drained_begin()/bdrv_drained_end() instead. They are "mixed"
functions that can be called from coroutine context. Unlike
bdrv_co_drain(), these functions provide control of the length of the
drained section, which is usually the right thing.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/block/block-io.h |  1 -
 block/io.c               | 15 ---------------
 2 files changed, 16 deletions(-)

diff --git a/include/block/block-io.h b/include/block/block-io.h
index 62c84f0519..053a27141a 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -270,7 +270,6 @@ void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter);
                    cond); })
 
 void bdrv_drain(BlockDriverState *bs);
-void coroutine_fn bdrv_co_drain(BlockDriverState *bs);
 
 int generated_co_wrapper
 bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
diff --git a/block/io.c b/block/io.c
index 789e6373d5..1e9bf09a49 100644
--- a/block/io.c
+++ b/block/io.c
@@ -588,21 +588,6 @@ void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent)
     BDRV_POLL_WHILE(child->bs, qatomic_read(&drained_end_counter) > 0);
 }
 
-/*
- * Wait for pending requests to complete on a single BlockDriverState subtree,
- * and suspend block driver's internal I/O until next request arrives.
- *
- * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
- * AioContext.
- */
-void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
-{
-    IO_OR_GS_CODE();
-    assert(qemu_in_coroutine());
-    bdrv_drained_begin(bs);
-    bdrv_drained_end(bs);
-}
-
 void bdrv_drain(BlockDriverState *bs)
 {
     IO_OR_GS_CODE();
-- 
2.36.1

Am 21.05.2022 um 14:27 hat Stefan Hajnoczi geschrieben:
> bdrv_co_drain() has not been used since commit 9a0cec664eef ("mirror:
> use bdrv_drained_begin/bdrv_drained_end") in 2016. Remove it so there
> are fewer drain scenarios to worry about.
> 
> Use bdrv_drained_begin()/bdrv_drained_end() instead. They are "mixed"
> functions that can be called from coroutine context. Unlike
> bdrv_co_drain(), these functions provide control of the length of the
> drained section, which is usually the right thing.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Thanks, applied to the block branch.

Kevin

On Sat, May 21, 2022 at 1:27 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
> bdrv_co_drain() has not been used since commit 9a0cec664eef ("mirror:
> use bdrv_drained_begin/bdrv_drained_end") in 2016. Remove it so there
> are fewer drain scenarios to worry about.
>
> Use bdrv_drained_begin()/bdrv_drained_end() instead. They are "mixed"
> functions that can be called from coroutine context. Unlike
> bdrv_co_drain(), these functions provide control of the length of the
> drained section, which is usually the right thing.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Alberto Faria <afaria@redhat.com>

Am 21/05/2022 um 14:27 schrieb Stefan Hajnoczi:
> bdrv_co_drain() has not been used since commit 9a0cec664eef ("mirror:
> use bdrv_drained_begin/bdrv_drained_end") in 2016. Remove it so there
> are fewer drain scenarios to worry about.
> 
> Use bdrv_drained_begin()/bdrv_drained_end() instead. They are "mixed"
> functions that can be called from coroutine context. Unlike
> bdrv_co_drain(), these functions provide control of the length of the
> drained section, which is usually the right thing.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Thank you,
Emanuele

> ---
>  include/block/block-io.h |  1 -
>  block/io.c               | 15 ---------------
>  2 files changed, 16 deletions(-)
> 
> diff --git a/include/block/block-io.h b/include/block/block-io.h
> index 62c84f0519..053a27141a 100644
> --- a/include/block/block-io.h
> +++ b/include/block/block-io.h
> @@ -270,7 +270,6 @@ void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter);
>                     cond); })
>  
>  void bdrv_drain(BlockDriverState *bs);
> -void coroutine_fn bdrv_co_drain(BlockDriverState *bs);
>  
>  int generated_co_wrapper
>  bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
> diff --git a/block/io.c b/block/io.c
> index 789e6373d5..1e9bf09a49 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -588,21 +588,6 @@ void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent)
>      BDRV_POLL_WHILE(child->bs, qatomic_read(&drained_end_counter) > 0);
>  }
>  
> -/*
> - * Wait for pending requests to complete on a single BlockDriverState subtree,
> - * and suspend block driver's internal I/O until next request arrives.
> - *
> - * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
> - * AioContext.
> - */
> -void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
> -{
> -    IO_OR_GS_CODE();
> -    assert(qemu_in_coroutine());
> -    bdrv_drained_begin(bs);
> -    bdrv_drained_end(bs);
> -}
> -
>  void bdrv_drain(BlockDriverState *bs)
>  {
>      IO_OR_GS_CODE();
>