The current implementation of bdrv_qed_drain can cause a double
completion of a request.
The problem is that bdrv_qed_drain calls qed_plug_allocating_write_reqs
unconditionally, but this is not correct if an allocating write
is queued. In this case, qed_unplug_allocating_write_reqs will
restart the allocating write and possibly cause it to complete.
The aiocb however is still in use for the L2/L1 table writes,
and will then be completed again as soon as the table writes
are stable.
The fix is to only call qed_plug_allocating_write_reqs and
bdrv_aio_flush (which is the same as the timer callback---the patch
makes this explicit) only if the timer was scheduled in the first
place. This fixes qemu-iotests test 011.
Cc: qemu-sta...@nongnu.org
Cc: qemu-bl...@nongnu.org
Cc: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block/qed.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/block/qed.c b/block/qed.c
index 404be1e..ebba220 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -380,12 +380,13 @@ static void bdrv_qed_drain(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
- /* Cancel timer and start doing I/O that were meant to happen as if it
- * fired, that way we get bdrv_drain() taking care of the ongoing requests
- * correctly. */
- qed_cancel_need_check_timer(s);
- qed_plug_allocating_write_reqs(s);
- bdrv_aio_flush(s->bs, qed_clear_need_check, s);
+ /* Fire the timer immediately in order to start doing I/O as soon as the
+ * header is flushed.
+ */
+ if (s->need_check_timer && timer_pending(s->need_check_timer)) {
+ qed_cancel_need_check_timer(s);
+ qed_need_check_timer_cb(s);
+ }
}
static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
--
2.5.0
