[PATCH 0/5] block-job: drop BlockJob.blk

[PATCH 0/5] block-job: drop BlockJob.blk

[Vladimir Sementsov-Ogievskiy]

Hi all!

Block jobs usually operate with several block nodes, and better to
handle them symmetrically, than use one from s->common.blk and one from
s->target (or something like this). Moreover, generic blockjob layer has
no use of BlockJob.blk. And more-moreover, most of block-jobs don't
really use this blk. Actually only block-stream use it.

I've started this thing (unbinding block-job and its main node) long
ago. First step was removing bs->job pointer in b23c580c946644b. Then
block_job_drain was dropped in bb0c94099382b5273.

Now let's finally drop job->blk pointer.

Vladimir Sementsov-Ogievskiy (5):
  blockjob: implement and use block_job_get_aio_context
  test-blockjob-txn: don't abuse job->blk
  block/stream: add own blk
  test-bdrv-drain: don't use BlockJob.blk
  blockjob: drop BlockJob.blk field

 include/block/blockjob.h       | 10 +++++++---
 block/mirror.c                 |  7 -------
 block/stream.c                 | 24 ++++++++++++++++++------
 blockdev.c                     |  6 +++---
 blockjob.c                     | 24 +++++++-----------------
 qemu-img.c                     |  2 +-
 tests/unit/test-bdrv-drain.c   | 12 ++++++++----
 tests/unit/test-blockjob-txn.c | 10 +---------
 tests/qemu-iotests/141.out     |  2 +-
 9 files changed, 46 insertions(+), 51 deletions(-)

-- 
2.29.2

[PATCH 1/5] blockjob: implement and use block_job_get_aio_context

[Vladimir Sementsov-Ogievskiy]

We are going to drop BlockJob.blk. So let's retrieve block job context
from underlying job instead of main node.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/blockjob.h | 7 +++++++
 blockdev.c               | 6 +++---
 blockjob.c               | 5 +++++
 qemu-img.c               | 2 +-
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index d200f33c10..3b84805140 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -173,4 +173,11 @@ bool block_job_is_internal(BlockJob *job);
  */
 const BlockJobDriver *block_job_driver(BlockJob *job);
 
+/*
+ * block_job_get_aio_context:
+ *
+ * Returns aio context associated with a block job.
+ */
+AioContext *block_job_get_aio_context(BlockJob *job);
+
 #endif
diff --git a/blockdev.c b/blockdev.c
index 834c2304a1..18ed8cd03f 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3328,7 +3328,7 @@ static BlockJob *find_block_job(const char *id, AioContext **aio_context,
         return NULL;
     }
 
-    *aio_context = blk_get_aio_context(job->blk);
+    *aio_context = block_job_get_aio_context(job);
     aio_context_acquire(*aio_context);
 
     return job;
@@ -3433,7 +3433,7 @@ void qmp_block_job_finalize(const char *id, Error **errp)
      * automatically acquires the new one), so make sure we release the correct
      * one.
      */
-    aio_context = blk_get_aio_context(job->blk);
+    aio_context = block_job_get_aio_context(job);
     job_unref(&job->job);
     aio_context_release(aio_context);
 }
@@ -3710,7 +3710,7 @@ BlockJobInfoList *qmp_query_block_jobs(Error **errp)
         if (block_job_is_internal(job)) {
             continue;
         }
-        aio_context = blk_get_aio_context(job->blk);
+        aio_context = block_job_get_aio_context(job);
         aio_context_acquire(aio_context);
         value = block_job_query(job, errp);
         aio_context_release(aio_context);
diff --git a/blockjob.c b/blockjob.c
index 2fe1d788ba..2c168b93b0 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -534,3 +534,8 @@ BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
     }
     return action;
 }
+
+AioContext *block_job_get_aio_context(BlockJob *job)
+{
+    return job->job.aio_context;
+}
diff --git a/qemu-img.c b/qemu-img.c
index a5993682aa..b690d3ae2b 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -900,7 +900,7 @@ static void common_block_job_cb(void *opaque, int ret)
 
 static void run_block_job(BlockJob *job, Error **errp)
 {
-    AioContext *aio_context = blk_get_aio_context(job->blk);
+    AioContext *aio_context = block_job_get_aio_context(job);
     int ret = 0;
 
     aio_context_acquire(aio_context);
-- 
2.29.2

[PATCH 2/5] test-blockjob-txn: don't abuse job->blk

[Vladimir Sementsov-Ogievskiy]

Here we use job->blk to drop our own reference in job cleanup. Let's do
simpler: drop our reference immediately after job creation.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 tests/unit/test-blockjob-txn.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/tests/unit/test-blockjob-txn.c b/tests/unit/test-blockjob-txn.c
index 8bd13b9949..c69028b450 100644
--- a/tests/unit/test-blockjob-txn.c
+++ b/tests/unit/test-blockjob-txn.c
@@ -25,14 +25,6 @@ typedef struct {
     int *result;
 } TestBlockJob;
 
-static void test_block_job_clean(Job *job)
-{
-    BlockJob *bjob = container_of(job, BlockJob, job);
-    BlockDriverState *bs = blk_bs(bjob->blk);
-
-    bdrv_unref(bs);
-}
-
 static int coroutine_fn test_block_job_run(Job *job, Error **errp)
 {
     TestBlockJob *s = container_of(job, TestBlockJob, common.job);
@@ -73,7 +65,6 @@ static const BlockJobDriver test_block_job_driver = {
         .free          = block_job_free,
         .user_resume   = block_job_user_resume,
         .run           = test_block_job_run,
-        .clean         = test_block_job_clean,
     },
 };
 
@@ -105,6 +96,7 @@ static BlockJob *test_block_job_start(unsigned int iterations,
     s = block_job_create(job_id, &test_block_job_driver, txn, bs,
                          0, BLK_PERM_ALL, 0, JOB_DEFAULT,
                          test_block_job_cb, data, &error_abort);
+    bdrv_unref(bs); /* referenced by job now */
     s->iterations = iterations;
     s->use_timer = use_timer;
     s->rc = rc;
-- 
2.29.2

[PATCH 3/5] block/stream: add own blk

[Vladimir Sementsov-Ogievskiy]

block-stream is the only block-job, that reasonably use BlockJob.blk.
We are going to drop BlockJob.blk soon. So, let block-stream have own
blk.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/stream.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index 97bee482dc..01a8afc48c 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -33,6 +33,7 @@ enum {
 
 typedef struct StreamBlockJob {
     BlockJob common;
+    BlockBackend *blk;
     BlockDriverState *base_overlay; /* COW overlay (stream from this) */
     BlockDriverState *above_base;   /* Node directly above the base */
     BlockDriverState *cor_filter_bs;
@@ -85,17 +86,18 @@ static int stream_prepare(Job *job)
 static void stream_clean(Job *job)
 {
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
-    BlockJob *bjob = &s->common;
 
     if (s->cor_filter_bs) {
         bdrv_cor_filter_drop(s->cor_filter_bs);
         s->cor_filter_bs = NULL;
     }
 
+    blk_unref(s->blk);
+    s->blk = NULL;
+
     /* Reopen the image back in read-only mode if necessary */
     if (s->bs_read_only) {
         /* Give up write permissions before making it read-only */
-        blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
         bdrv_reopen_set_read_only(s->target_bs, true, NULL);
     }
 
@@ -105,7 +107,6 @@ static void stream_clean(Job *job)
 static int coroutine_fn stream_run(Job *job, Error **errp)
 {
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
-    BlockBackend *blk = s->common.blk;
     BlockDriverState *unfiltered_bs = bdrv_skip_filters(s->target_bs);
     int64_t len;
     int64_t offset = 0;
@@ -156,7 +157,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         }
         trace_stream_one_iteration(s, offset, n, ret);
         if (copy) {
-            ret = stream_populate(blk, offset, n);
+            ret = stream_populate(s->blk, offset, n);
         }
         if (ret < 0) {
             BlockErrorAction action =
@@ -291,13 +292,24 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     }
 
     s = block_job_create(job_id, &stream_job_driver, NULL, cor_filter_bs,
-                         BLK_PERM_CONSISTENT_READ,
-                         basic_flags | BLK_PERM_WRITE,
+                         0, BLK_PERM_ALL,
                          speed, creation_flags, NULL, NULL, errp);
     if (!s) {
         goto fail;
     }
 
+    s->blk = blk_new_with_bs(cor_filter_bs, BLK_PERM_CONSISTENT_READ,
+                             basic_flags | BLK_PERM_WRITE, errp);
+    if (!s->blk) {
+        goto fail;
+    }
+    /*
+     * 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(s->blk, true);
+    blk_set_allow_aio_context_change(s->blk, true);
+
     /*
      * Prevent concurrent jobs trying to modify the graph structure here, we
      * already have our own plans. Also don't allow resize as the image size is
-- 
2.29.2

[PATCH 4/5] test-bdrv-drain: don't use BlockJob.blk

[Vladimir Sementsov-Ogievskiy]

We are going to drop BlockJob.blk in further commit. For tests it's
enough to simply pass bs pointer.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 tests/unit/test-bdrv-drain.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index 892f7f47d8..d7b155d13a 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -770,6 +770,7 @@ static void test_iothread_drain_subtree(void)
 
 typedef struct TestBlockJob {
     BlockJob common;
+    BlockDriverState *bs;
     int run_ret;
     int prepare_ret;
     bool running;
@@ -781,7 +782,7 @@ static int test_job_prepare(Job *job)
     TestBlockJob *s = container_of(job, TestBlockJob, common.job);
 
     /* Provoke an AIO_WAIT_WHILE() call to verify there is no deadlock */
-    blk_flush(s->common.blk);
+    bdrv_flush(s->bs);
     return s->prepare_ret;
 }
 
@@ -790,7 +791,7 @@ static void test_job_commit(Job *job)
     TestBlockJob *s = container_of(job, TestBlockJob, common.job);
 
     /* Provoke an AIO_WAIT_WHILE() call to verify there is no deadlock */
-    blk_flush(s->common.blk);
+    bdrv_flush(s->bs);
 }
 
 static void test_job_abort(Job *job)
@@ -798,7 +799,7 @@ static void test_job_abort(Job *job)
     TestBlockJob *s = container_of(job, TestBlockJob, common.job);
 
     /* Provoke an AIO_WAIT_WHILE() call to verify there is no deadlock */
-    blk_flush(s->common.blk);
+    bdrv_flush(s->bs);
 }
 
 static int coroutine_fn test_job_run(Job *job, Error **errp)
@@ -913,6 +914,7 @@ static void test_blockjob_common_drain_node(enum drain_type drain_type,
     tjob = block_job_create("job0", &test_job_driver, NULL, src,
                             0, BLK_PERM_ALL,
                             0, 0, NULL, NULL, &error_abort);
+    tjob->bs = src;
     job = &tjob->common;
     block_job_add_bdrv(job, "target", target, 0, BLK_PERM_ALL, &error_abort);
 
@@ -1535,6 +1537,7 @@ typedef struct TestDropBackingBlockJob {
     bool should_complete;
     bool *did_complete;
     BlockDriverState *detach_also;
+    BlockDriverState *bs;
 } TestDropBackingBlockJob;
 
 static int coroutine_fn test_drop_backing_job_run(Job *job, Error **errp)
@@ -1554,7 +1557,7 @@ static void test_drop_backing_job_commit(Job *job)
     TestDropBackingBlockJob *s =
         container_of(job, TestDropBackingBlockJob, common.job);
 
-    bdrv_set_backing_hd(blk_bs(s->common.blk), NULL, &error_abort);
+    bdrv_set_backing_hd(s->bs, NULL, &error_abort);
     bdrv_set_backing_hd(s->detach_also, NULL, &error_abort);
 
     *s->did_complete = true;
@@ -1654,6 +1657,7 @@ static void test_blockjob_commit_by_drained_end(void)
     job = block_job_create("job", &test_drop_backing_job_driver, NULL,
                            bs_parents[2], 0, BLK_PERM_ALL, 0, 0, NULL, NULL,
                            &error_abort);
+    job->bs = bs_parents[2];
 
     job->detach_also = bs_parents[0];
     job->did_complete = &job_has_completed;
-- 
2.29.2

[PATCH 5/5] blockjob: drop BlockJob.blk field

[Vladimir Sementsov-Ogievskiy]

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