[Qemu-devel] [PATCH v7 05/14] blockjob: Introduce reference count

[Fam Zheng <famz@redhat.com>]

So that block_job_complete_sync can be simplified.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/mirror.c           |  2 +-
 blockjob.c               | 22 ++++++++++++++--------
 include/block/blockjob.h | 18 +++++++++++++++---
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index a258926..3472ad4 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -736,7 +736,7 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
     s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
     if (!s->dirty_bitmap) {
         g_free(s->replaces);
-        block_job_release(bs);
+        block_job_unref(&s->common);
         return;
     }
     bdrv_set_enable_write_cache(s->target, true);
diff --git a/blockjob.c b/blockjob.c
index 62bb906..ec12887 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -58,6 +58,7 @@ void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
     job->cb            = cb;
     job->opaque        = opaque;
     job->busy          = true;
+    job->refcnt        = 1;
     bs->job = job;
 
     /* Only set speed when necessary to avoid NotSupported error */
@@ -66,7 +67,7 @@ void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 
         block_job_set_speed(job, speed, &local_err);
         if (local_err) {
-            block_job_release(bs);
+            block_job_unref(job);
             error_propagate(errp, local_err);
             return NULL;
         }
@@ -74,14 +75,19 @@ void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
     return job;
 }
 
-void block_job_release(BlockDriverState *bs)
+void block_job_ref(BlockJob *job)
 {
-    BlockJob *job = bs->job;
+    ++job->refcnt;
+}
 
-    bs->job = NULL;
-    bdrv_op_unblock_all(bs, job->blocker);
-    error_free(job->blocker);
-    g_free(job);
+void block_job_unref(BlockJob *job)
+{
+    if (--job->refcnt == 0) {
+        job->bs->job = NULL;
+        bdrv_op_unblock_all(job->bs, job->blocker);
+        error_free(job->blocker);
+        g_free(job);
+    }
 }
 
 void block_job_completed(BlockJob *job, int ret)
@@ -90,7 +96,7 @@ void block_job_completed(BlockJob *job, int ret)
 
     assert(bs->job == job);
     job->cb(job->opaque, ret);
-    block_job_release(bs);
+    block_job_unref(job);
 }
 
 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index dd9d5e6..3e7ad21 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -122,6 +122,9 @@ struct BlockJob {
 
     /** The opaque value that is passed to the completion function.  */
     void *opaque;
+
+    /** Reference count of the block job */
+    int refcnt;
 };
 
 /**
@@ -166,12 +169,21 @@ void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 void block_job_yield(BlockJob *job);
 
 /**
- * block_job_release:
+ * block_job_ref:
  * @bs: The block device.
  *
- * Release job resources when an error occurred or job completed.
+ * Grab a reference to the block job. Should be paired with block_job_unref.
  */
-void block_job_release(BlockDriverState *bs);
+void block_job_ref(BlockJob *job);
+
+/**
+ * block_job_unref:
+ * @bs: The block device.
+ *
+ * Release reference to the block job and release resources if it is the last
+ * reference.
+ */
+void block_job_unref(BlockJob *job);
 
 /**
  * block_job_completed:
-- 
2.4.3