diff mbox

[55/88] snapshot: add bdrv_drain_all() to bdrv_snapshot_delete() to avoid concurrency problem

Message ID 1420738472-23267-56-git-send-email-mdroth@linux.vnet.ibm.com
State New
Headers show

Commit Message

Michael Roth Jan. 8, 2015, 5:33 p.m. UTC 
From: Zhang Haoyu <zhanghy@sangfor.com>

If there are still pending i/o while deleting snapshot,
because deleting snapshot is done in non-coroutine context, and
the pending i/o read/write (bdrv_co_do_rw) is done in coroutine context,
so it's possible to cause concurrency problem between above two operations.
Add bdrv_drain_all() to bdrv_snapshot_delete() to avoid this problem.

Signed-off-by: Zhang Haoyu <zhanghy@sangfor.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 201410211637596311287@sangfor.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 3432a1929ee18e08787ce35476abd74f2c93a17c)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 block/snapshot.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/block/snapshot.c b/block/snapshot.c
index 85c52ff..698e1a1 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -236,6 +236,10 @@  int bdrv_snapshot_delete(BlockDriverState *bs,
         error_setg(errp, "snapshot_id and name are both NULL");
         return -EINVAL;
     }
+
+    /* drain all pending i/o before deleting snapshot */
+    bdrv_drain_all();
+
     if (drv->bdrv_snapshot_delete) {
         return drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
     }