[Qemu-devel] [PATCH] blockdev: no need to drain in qmp_block_commit

[Paolo Bonzini]

Draining is not necessary, I/O can happen as soon as the
commit coroutine yields.  Draining can be necessary before
reopening the file for read/write, or while modifying the
backing file chain, but that is done separately in
bdrv_reopen_multiple or bdrv_close; this particular
bdrv_drain_all does nothing for that.

Signed-off-by: Paolo Bonzini <address@hidden>
---
 blockdev.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index d506a70..aee0395 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2355,9 +2355,6 @@ void qmp_block_commit(const char *device,
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
-    /* drain all i/o before commits */
-    bdrv_drain_all();
-
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, errp)) {
         goto out;
     }
-- 
2.4.1