diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2017-11-10 15:19:34 +0000 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2017-11-13 14:02:09 +0000 |
| commit | dc868fb03b9b829ed9d2ecdae0fcc12f3fe19b4f (patch) | |
| tree | 21130555d5c54a977907bd8e7e8e1fc836fc6874 | |
| parent | 632a77354317df32c7ff2d23424f0559c23fee51 (diff) | |
throttle-groups: drain before detaching ThrottleState
I/O requests hang after stop/cont commands at least since QEMU 2.10.0
with -drive iops=100:
(guest)$ dd if=/dev/zero of=/dev/vdb oflag=direct count=1000
(qemu) stop
(qemu) cont
...I/O is stuck...
This happens because blk_set_aio_context() detaches the ThrottleState
while requests may still be in flight:
if (tgm->throttle_state) {
throttle_group_detach_aio_context(tgm);
throttle_group_attach_aio_context(tgm, new_context);
}
This patch encloses the detach/attach calls in a drained region so no
I/O request is left hanging. Also add assertions so we don't make the
same mistake again in the future.
Reported-by: Yongxue Hong <yhong@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20171110151934.16883-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
| -rw-r--r-- | block/block-backend.c | 2 | ||||
| -rw-r--r-- | block/throttle-groups.c | 6 |
2 files changed, 8 insertions, 0 deletions
diff --git a/block/block-backend.c b/block/block-backend.c index 18e543780d..ab75da32c9 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1752,8 +1752,10 @@ void blk_set_aio_context(BlockBackend *blk, AioContext *new_context) if (bs) { if (tgm->throttle_state) { + bdrv_drained_begin(bs); throttle_group_detach_aio_context(tgm); throttle_group_attach_aio_context(tgm, new_context); + bdrv_drained_end(bs); } bdrv_set_aio_context(bs, new_context); } diff --git a/block/throttle-groups.c b/block/throttle-groups.c index b291a88481..2587f19ca3 100644 --- a/block/throttle-groups.c +++ b/block/throttle-groups.c @@ -594,6 +594,12 @@ void throttle_group_attach_aio_context(ThrottleGroupMember *tgm, void throttle_group_detach_aio_context(ThrottleGroupMember *tgm) { ThrottleTimers *tt = &tgm->throttle_timers; + + /* Requests must have been drained */ + assert(tgm->pending_reqs[0] == 0 && tgm->pending_reqs[1] == 0); + assert(qemu_co_queue_empty(&tgm->throttled_reqs[0])); + assert(qemu_co_queue_empty(&tgm->throttled_reqs[1])); + throttle_timers_detach_aio_context(tt); tgm->aio_context = NULL; } |