https://bugzilla.redhat.com/show_bug.cgi?id=1632711

GlusterFS is typically safe when it comes to migration. It's a
network FS after all. However, it can be mounted via FUSE driver
they provide. If that is the case we fail to identify it and
think migration is not safe and require VIR_MIGRATE_UNSAFE flag.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---

diff to v1:
- fixed the function name
- switched from for() loop into virStringListHasString
- ignoring retval of the function in the caller

 src/util/virfile.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 75 insertions(+), 2 deletions(-)

diff --git a/src/util/virfile.c b/src/util/virfile.c
index f8ae07fe4a..2a7e87102a 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -3458,6 +3458,76 @@ int virFilePrintf(FILE *fp, const char *msg, ...)
 # ifndef HUGETLBFS_MAGIC
 #  define HUGETLBFS_MAGIC 0x958458f6
 # endif
+# ifndef FUSE_SUPER_MAGIC
+#  define FUSE_SUPER_MAGIC 0x65735546
+# endif
+
+# define PROC_MOUNTS "/proc/mounts"
+
+static int
+virFileIsSharedFixFUSE(const char *path,
+                       long *f_type)
+{
+    char *dirpath = NULL;
+    const char **mounts = NULL;
+    size_t nmounts = 0;
+    char *p;
+    FILE *f = NULL;
+    struct mntent mb;
+    char mntbuf[1024];
+    int ret = -1;
+
+    if (VIR_STRDUP(dirpath, path) < 0)
+        return -1;
+
+    if (!(f = setmntent(PROC_MOUNTS, "r"))) {
+        virReportSystemError(errno,
+                             _("Unable to open %s"),
+                             PROC_MOUNTS);
+        goto cleanup;
+    }
+
+    while (getmntent_r(f, &mb, mntbuf, sizeof(mntbuf))) {
+        if (STRNEQ("fuse.glusterfs", mb.mnt_type))
+            continue;
+
+        if (VIR_APPEND_ELEMENT_COPY(mounts, nmounts, mb.mnt_dir) < 0)
+            goto cleanup;
+    }
+
+    /* Add NULL sentinel so that this is a virStringList */
+    if (VIR_REALLOC_N(mounts, nmounts + 1) < 0)
+        goto cleanup;
+    mounts[nmounts] = NULL;
+
+    do {
+        if ((p = strrchr(dirpath, '/')) == NULL) {
+            virReportSystemError(EINVAL,
+                                 _("Invalid relative path '%s'"), path);
+            goto cleanup;
+        }
+
+        if (p == dirpath)
+            *(p+1) = '\0';
+        else
+            *p = '\0';
+
+        if (virStringListHasString(mounts, dirpath)) {
+            VIR_DEBUG("Found gluster FUSE mountpoint=%s for path=%s. "
+                      "Fixing shared FS type", dirpath, path);
+            *f_type = GFS2_MAGIC;
+            break;
+        }
+    } while (p != dirpath);
+
+    ret = 0;
+ cleanup:
+    endmntent(f);
+    VIR_FREE(mounts);
+    VIR_FREE(dirpath);
+    return ret;
+}
+
 
 int
 virFileIsSharedFSType(const char *path,
@@ -3503,6 +3573,11 @@ virFileIsSharedFSType(const char *path,
         return -1;
     }
 
+    if (sb.f_type == FUSE_SUPER_MAGIC) {
+        VIR_DEBUG("Found FUSE mount for path=%s. Trying to fix it", path);
+        virFileIsSharedFixFUSE(path, (long *) &sb.f_type);
+    }
+
     VIR_DEBUG("Check if path %s with FS magic %lld is shared",
               path, (long long int)sb.f_type);
 
@@ -3594,8 +3669,6 @@ virFileGetDefaultHugepageSize(unsigned long long *size)
     return 0;
 }
 
-# define PROC_MOUNTS "/proc/mounts"
-
 int
 virFileFindHugeTLBFS(virHugeTLBFSPtr *ret_fs,
                      size_t *ret_nfs)
-- 
2.16.4

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On Wed, Oct 03, 2018 at 13:16:35 +0200, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1632711
> 
> GlusterFS is typically safe when it comes to migration. It's a
> network FS after all. However, it can be mounted via FUSE driver
> they provide. If that is the case we fail to identify it and
> think migration is not safe and require VIR_MIGRATE_UNSAFE flag.
> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
> 
> diff to v1:
> - fixed the function name
> - switched from for() loop into virStringListHasString
> - ignoring retval of the function in the caller
> 
>  src/util/virfile.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 75 insertions(+), 2 deletions(-)

Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

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