job.c: enable job lock/unlock and remove Aiocontext locks

Change the job_{lock/unlock} and macros to use job_mutex.

Now that they are not nop anymore, remove the aiocontext
to avoid deadlocks.

Therefore:
- when possible, remove completely the aiocontext lock/unlock pair
- if it is used by some other function too, reduce the locking
  section as much as possible, leaving the job API outside.
- change AIO_WAIT_WHILE in AIO_WAIT_WHILE_UNLOCKED, since we
  are not using the aiocontext lock anymore

The only functions that still need the aiocontext lock are:
- the JobDriver callbacks, already documented in job.h
- job_cancel_sync() in replication.c is called with aio_context_lock
  taken, but now job is using AIO_WAIT_WHILE_UNLOCKED so we need to
  release the lock.

Reduce the locking section to only cover the callback invocation
and document the functions that take the AioContext lock,
to avoid taking it twice.

Also remove real_job_{lock/unlock}, as they are replaced by the
public functions.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220926093214.506243-19-eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 0 insertions, 2 deletions

diff --git a/qemu-img.c b/qemu-img.c
index e0a30b1f4c..ace3adf8ae 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -911,7 +911,6 @@ static void run_block_job(BlockJob *job, Error **errp)
     AioContext *aio_context = block_job_get_aio_context(job);
     int ret = 0;
 
-    aio_context_acquire(aio_context);
     job_lock();
     job_ref_locked(&job->job);
     do {
@@ -936,7 +935,6 @@ static void run_block_job(BlockJob *job, Error **errp)
     }
     job_unref_locked(&job->job);
     job_unlock();
-    aio_context_release(aio_context);
 
     /* publish completion progress only when success */
     if (!ret) {