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[Qemu-devel] [PATCH v5 8/8] backup: follow AioContext change gracefully
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v5 8/8] backup: follow AioContext change gracefully |
Date: |
Thu, 16 Jun 2016 17:56:29 +0100 |
Move s->target to the new AioContext when there is an AioContext change.
The backup_run() coroutine does not use asynchronous I/O so there is no
need to wait for in-flight requests in a BlockJobDriver->pause()
callback.
Guest writes are intercepted by the backup job. Treat them as guest
activity and do it even while the job is paused. This is necessary
since the only alternative would be to fail a job that experienced guest
writes during pause once the job is resumed. In practice the guest
writes don't interfere with AioContext switching since bdrv_drain() is
used by bdrv_set_aio_context().
Loops already contain pause points because of block_job_sleep_ns() calls
in the yield_and_check() helper function. It is necessary to convert a
raw qemu_coroutine_yield() to block_job_yield() so the
MIRROR_SYNC_MODE_NONE case can pause.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/backup.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/block/backup.c b/block/backup.c
index feeb9f8..581269b 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -246,12 +246,20 @@ static void backup_abort(BlockJob *job)
}
}
+static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
+{
+ BackupBlockJob *s = container_of(job, BackupBlockJob, common);
+
+ blk_set_aio_context(s->target, aio_context);
+}
+
static const BlockJobDriver backup_job_driver = {
- .instance_size = sizeof(BackupBlockJob),
- .job_type = BLOCK_JOB_TYPE_BACKUP,
- .set_speed = backup_set_speed,
- .commit = backup_commit,
- .abort = backup_abort,
+ .instance_size = sizeof(BackupBlockJob),
+ .job_type = BLOCK_JOB_TYPE_BACKUP,
+ .set_speed = backup_set_speed,
+ .commit = backup_commit,
+ .abort = backup_abort,
+ .attached_aio_context = backup_attached_aio_context,
};
static BlockErrorAction backup_error_action(BackupBlockJob *job,
@@ -392,9 +400,7 @@ static void coroutine_fn backup_run(void *opaque)
while (!block_job_is_cancelled(&job->common)) {
/* Yield until the job is cancelled. We just let our before_write
* notify callback service CoW requests. */
- job->common.busy = false;
- qemu_coroutine_yield();
- job->common.busy = true;
+ block_job_yield(&job->common);
}
} else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
ret = backup_run_incremental(job);
--
2.5.5
- [Qemu-devel] [PATCH v5 0/8] blockjob: AioContext change support for mirror and backup, Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 4/8] blockjob: add block_job_get_aio_context(), Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 2/8] blockjob: rename block_job_is_paused(), Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 3/8] blockjob: add pause points, Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 6/8] blockjob: add AioContext attached callback, Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 1/8] blockjob: move iostatus reset out of block_job_enter(), Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 8/8] backup: follow AioContext change gracefully,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v5 7/8] mirror: follow AioContext change gracefully, Stefan Hajnoczi, 2016/06/16
- [Qemu-devel] [PATCH v5 5/8] block: use safe iteration over AioContext notifiers, Stefan Hajnoczi, 2016/06/16
- Re: [Qemu-devel] [PATCH v5 0/8] blockjob: AioContext change support for mirror and backup, Paolo Bonzini, 2016/06/16
- Re: [Qemu-devel] [PATCH v5 0/8] blockjob: AioContext change support for mirror and backup, Stefan Hajnoczi, 2016/06/17