@@ -242,6 +242,13 @@ static void backup_abort(BlockJob *job)
}
}
+static void backup_clean(BlockJob *job)
+{
+ BackupBlockJob *s = container_of(job, BackupBlockJob, common);
+ assert(s->target);
+ blk_unref(s->target);
+}
+
static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common);
@@ -306,6 +313,7 @@ static const BlockJobDriver backup_job_driver = {
.set_speed = backup_set_speed,
.commit = backup_commit,
.abort = backup_abort,
+ .clean = backup_clean,
.attached_aio_context = backup_attached_aio_context,
};
@@ -327,11 +335,8 @@ typedef struct {
static void backup_complete(BlockJob *job, void *opaque)
{
- BackupBlockJob *s = container_of(job, BackupBlockJob, common);
BackupCompleteData *data = opaque;
- blk_unref(s->target);
-
block_job_completed(job, data->ret);
g_free(data);
}
@@ -642,7 +647,7 @@ void backup_start(const char *job_id, BlockDriverState *bs,
bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
}
if (job) {
- blk_unref(job->target);
+ backup_clean(&job->common);
block_job_unref(&job->common);
}
}
@@ -232,6 +232,9 @@ static void block_job_completed_single(BlockJob *job)
job->driver->abort(job);
}
}
+ if (job->driver->clean) {
+ job->driver->clean(job);
+ }
if (job->cb) {
job->cb(job->opaque, job->ret);
@@ -74,6 +74,14 @@ struct BlockJobDriver {
void (*abort)(BlockJob *job);
/**
+ * If the callback is not NULL, it will be invoked after a call to either
+ * .commit() or .abort(). Regardless of which callback is invoked after
+ * completion, .clean() will always be called, even if the job does not
+ * belong to a transaction group.
+ */
+ void (*clean)(BlockJob *job);
+
+ /**
* If the callback is not NULL, it will be invoked when the job transitions
* into the paused state. Paused jobs must not perform any asynchronous
* I/O or event loop activity. This callback is used to quiesce jobs.
Cleaning up after we have deferred to the main thread but before the transaction has converged can be dangerous and result in deadlocks if the job cleanup invokes any BH polling loops. A job may attempt to begin cleaning up, but may induce another job to enter its cleanup routine. The second job, part of our same transaction, will block waiting for the first job to finish, so neither job may now make progress. To rectify this, allow jobs to register a cleanup operation that will always run regardless of if the job was in a transaction or not, and if the transaction job group completed successfully or not. Move sensitive cleanup to this callback instead which is guaranteed to be run only after the transaction has converged, which removes sensitive timing constraints from said cleanup. Furthermore, in future patches these cleanup operations will be performed regardless of whether or not we actually started the job. Therefore, cleanup callbacks should essentially confine themselves to undoing create operations, e.g. setup actions taken in what is now backup_start. Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: John Snow <jsnow@redhat.com> --- block/backup.c | 13 +++++++++---- blockjob.c | 3 +++ include/block/blockjob_int.h | 8 ++++++++ 3 files changed, 20 insertions(+), 4 deletions(-)