[PATCH 5/5] blockjob: drop BlockJob.blk field - Vladimir Sementsov-Ogievskiy

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, armbru@redhat.com, mreitz@redhat.com,
	kwolf@redhat.com, vsementsov@virtuozzo.com, jsnow@redhat.com
Subject: [PATCH 5/5] blockjob: drop BlockJob.blk field
Date: Thu,  6 May 2021 17:13:57 +0300	[thread overview]
Message-ID: <20210506141357.314257-6-vsementsov@virtuozzo.com> (raw)
In-Reply-To: <20210506141357.314257-1-vsementsov@virtuozzo.com>

It's unused now (except for permission handling)[*]. The only reasonable
user of it was block-stream job, recently updated to use own blk. And
other block jobs prefer to use own source node related objects.

So, the arguments of dropping the field are:

 - block jobs prefer not to use it
 - block jobs usually has more then one node to operate on, and better
   to operate symmetrically (for example has both source and target
   blk's in specific block-job state structure)

*: BlockJob.blk is used to keep some permissions. We simply move
permissions to block-job child created in block_job_create() together
with blk.

In mirror, we just should not care anymore about restoring state of
blk. Most probably this code could be dropped long ago, after dropping
bs->job pointer. Now it finally goes away together with BlockJob.blk
itself.

iotest 141 output is updated, as "bdrv_has_blk(bs)" check in
qmp_blockdev_del() doesn't fail (we don't have blk now). Still, new
error message looks even better.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/blockjob.h   |  3 ---
 block/mirror.c             |  7 -------
 blockjob.c                 | 19 ++-----------------
 tests/qemu-iotests/141.out |  2 +-
 4 files changed, 3 insertions(+), 28 deletions(-)

diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index 3b84805140..87fbb3985f 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -43,9 +43,6 @@ typedef struct BlockJob {
     /** Data belonging to the generic Job infrastructure */
     Job job;
 
-    /** The block device on which the job is operating.  */
-    BlockBackend *blk;
-
     /** Status that is published by the query-block-jobs QMP API */
     BlockDeviceIoStatus iostatus;
 
diff --git a/block/mirror.c b/block/mirror.c
index 840b8e8c15..cbebcf8798 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -754,13 +754,6 @@ static int mirror_exit_common(Job *job)
     block_job_remove_all_bdrv(bjob);
     bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
 
-    /* We just changed the BDS the job BB refers to (with either or both of the
-     * bdrv_replace_node() calls), so switch the BB back so the cleanup does
-     * the right thing. We don't need any permissions any more now. */
-    blk_remove_bs(bjob->blk);
-    blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
-    blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort);
-
     bs_opaque->job = NULL;
 
     bdrv_drained_end(src);
diff --git a/blockjob.c b/blockjob.c
index 2c168b93b0..70f3220ffd 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -86,7 +86,6 @@ void block_job_free(Job *job)
     BlockJob *bjob = container_of(job, BlockJob, job);
 
     block_job_remove_all_bdrv(bjob);
-    blk_unref(bjob->blk);
     error_free(bjob->blocker);
 }
 
@@ -419,22 +418,15 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
                        uint64_t shared_perm, int64_t speed, int flags,
                        BlockCompletionFunc *cb, void *opaque, Error **errp)
 {
-    BlockBackend *blk;
     BlockJob *job;
 
     if (job_id == NULL && !(flags & JOB_INTERNAL)) {
         job_id = bdrv_get_device_name(bs);
     }
 
-    blk = blk_new_with_bs(bs, perm, shared_perm, errp);
-    if (!blk) {
-        return NULL;
-    }
-
-    job = job_create(job_id, &driver->job_driver, txn, blk_get_aio_context(blk),
+    job = job_create(job_id, &driver->job_driver, txn, bdrv_get_aio_context(bs),
                      flags, cb, opaque, errp);
     if (job == NULL) {
-        blk_unref(blk);
         return NULL;
     }
 
@@ -442,8 +434,6 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
     assert(job->job.driver->free == &block_job_free);
     assert(job->job.driver->user_resume == &block_job_user_resume);
 
-    job->blk = blk;
-
     job->finalize_cancelled_notifier.notify = block_job_event_cancelled;
     job->finalize_completed_notifier.notify = block_job_event_completed;
     job->pending_notifier.notify = block_job_event_pending;
@@ -460,15 +450,10 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 
     error_setg(&job->blocker, "block device is in use by block job: %s",
                job_type_str(&job->job));
-    block_job_add_bdrv(job, "main node", bs, 0, BLK_PERM_ALL, &error_abort);
+    block_job_add_bdrv(job, "main node", bs, perm, shared_perm, &error_abort);
 
     bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
 
-    /* Disable request queuing in the BlockBackend to avoid deadlocks on drain:
-     * The job reports that it's busy until it reaches a pause point. */
-    blk_set_disable_request_queuing(blk, true);
-    blk_set_allow_aio_context_change(blk, true);
-
     /* Only set speed when necessary to avoid NotSupported error */
     if (speed != 0) {
         if (!block_job_set_speed(job, speed, errp)) {
diff --git a/tests/qemu-iotests/141.out b/tests/qemu-iotests/141.out
index c4c15fb275..63203d9944 100644
--- a/tests/qemu-iotests/141.out
+++ b/tests/qemu-iotests/141.out
@@ -132,7 +132,7 @@ wrote 1048576/1048576 bytes at offset 0
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "running", "id": "job0"}}
 {'execute': 'blockdev-del',
           'arguments': {'node-name': 'drv0'}}
-{"error": {"class": "GenericError", "desc": "Node drv0 is in use"}}
+{"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: commit"}}
 {'execute': 'block-job-cancel',
           'arguments': {'device': 'job0'}}
 {"return": {}}
-- 
2.29.2


