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mirror: follow AioContext change gracefully 

Add block_job_pause_point() calls to mark quiescent points and make sure
to complete in-flight requests when switching AioContexts.

This patch solves undefined behavior in the mirror block job when the
BDS AioContext is changed by dataplane.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1466096189-6477-8-git-send-email-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2016-06-16 17:56:28 +01:00
parent 463e0be101
commit 565ac01f8d
1 changed files with 35 additions and 8 deletions
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43
block/mirror.c
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@ -331,6 +331,8 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
mirror_wait_for_io(s);
}
block_job_pause_point(&s->common);
/* Find the number of consective dirty chunks following the first dirty
* one, and wait for in flight requests in them. */
while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
@ -582,6 +584,8 @@ static void coroutine_fn mirror_run(void *opaque)
if (now - last_pause_ns > SLICE_TIME) {
last_pause_ns = now;
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0);
} else {
block_job_pause_point(&s->common);
}
if (block_job_is_cancelled(&s->common)) {
@ -613,6 +617,8 @@ static void coroutine_fn mirror_run(void *opaque)
goto immediate_exit;
}
block_job_pause_point(&s->common);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
/* s->common.offset contains the number of bytes already processed so
* far, cnt is the number of dirty sectors remaining and
@ -795,18 +801,39 @@ static void mirror_complete(BlockJob *job, Error **errp)
block_job_enter(&s->common);
}
/* There is no matching mirror_resume() because mirror_run() will begin
* iterating again when the job is resumed.
*/
static void coroutine_fn mirror_pause(BlockJob *job)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
mirror_drain(s);
}
static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
blk_set_aio_context(s->target, new_context);
}
static const BlockJobDriver mirror_job_driver = {
.instance_size = sizeof(MirrorBlockJob),
.job_type = BLOCK_JOB_TYPE_MIRROR,
.set_speed = mirror_set_speed,
.complete = mirror_complete,
.instance_size = sizeof(MirrorBlockJob),
.job_type = BLOCK_JOB_TYPE_MIRROR,
.set_speed = mirror_set_speed,
.complete = mirror_complete,
.pause = mirror_pause,
.attached_aio_context = mirror_attached_aio_context,
};
static const BlockJobDriver commit_active_job_driver = {
.instance_size = sizeof(MirrorBlockJob),
.job_type = BLOCK_JOB_TYPE_COMMIT,
.set_speed = mirror_set_speed,
.complete = mirror_complete,
.instance_size = sizeof(MirrorBlockJob),
.job_type = BLOCK_JOB_TYPE_COMMIT,
.set_speed = mirror_set_speed,
.complete = mirror_complete,
.pause = mirror_pause,
.attached_aio_context = mirror_attached_aio_context,
};
static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,