The "need_check_timer" is used to clear the "NEED_CHECK" flag in the image header after a grace period once metadata update has finished. In compliance to the bdrv_drain semantics we should make sure it remains deleted once .bdrv_drain is called.
We cannot reuse qed_need_check_timer_cb because it calls bdrv_aio_flush with a completion callback that starts more I/O, bdrv_drain cannot cope with this. Also the assertions in qed_need_check_timer_cb and qed_unplug_allocating_write_reqs are not guaranteed in the case of bdrv_qed_drain. Signed-off-by: Fam Zheng <f...@redhat.com> --- block/qed.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/block/qed.c b/block/qed.c index 5ea05d4..d63a7de 100644 --- a/block/qed.c +++ b/block/qed.c @@ -375,6 +375,20 @@ static void bdrv_qed_attach_aio_context(BlockDriverState *bs, } } +static void bdrv_qed_drain(BlockDriverState *bs) +{ + BDRVQEDState *s = bs->opaque; + int ret; + + /* Cancel timer and start doing I/O that were meant to happen when it + * fires, that way we get bdrv_drain() taking care of the requests + * correctly. */ + qed_cancel_need_check_timer(s); + qed_plug_allocating_write_reqs(s); + ret = bdrv_flush(s->bs); + qed_clear_need_check(s, ret); +} + static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { @@ -1676,6 +1690,7 @@ static BlockDriver bdrv_qed = { .bdrv_check = bdrv_qed_check, .bdrv_detach_aio_context = bdrv_qed_detach_aio_context, .bdrv_attach_aio_context = bdrv_qed_attach_aio_context, + .bdrv_drain = bdrv_qed_drain, }; static void bdrv_qed_init(void) -- 2.4.3