block: Introduce blk_exit_queue()

This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Alexandru Moise <00moses.alexander00@gmail.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 31 insertions, 24 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index f9ad73d8573c..49af34bf2119 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -715,6 +715,35 @@ void blk_set_queue_dying(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
 
+/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
+void blk_exit_queue(struct request_queue *q)
+{
+        /*
+         * Since the I/O scheduler exit code may access cgroup information,
+         * perform I/O scheduler exit before disassociating from the block
+         * cgroup controller.
+         */
+        if (q->elevator) {
+                ioc_clear_queue(q);
+                elevator_exit(q, q->elevator);
+                q->elevator = NULL;
+        }
+
+        /*
+         * Remove all references to @q from the block cgroup controller before
+         * restoring @q->queue_lock to avoid that restoring this pointer causes
+         * e.g. blkcg_print_blkgs() to crash.
+         */
+        blkcg_exit_queue(q);
+
+        /*
+         * Since the cgroup code may dereference the @q->backing_dev_info
+         * pointer, only decrease its reference count after having removed the
+         * association with the block cgroup controller.
+         */
+        bdi_put(q->backing_dev_info);
+}
+
 /**
  * blk_cleanup_queue - shutdown a request queue
  * @q: request queue to shutdown
@@ -784,30 +813,7 @@ void blk_cleanup_queue(struct request_queue *q)
          */
         WARN_ON_ONCE(q->kobj.state_in_sysfs);
 
-        /*
-         * Since the I/O scheduler exit code may access cgroup information,
-         * perform I/O scheduler exit before disassociating from the block
-         * cgroup controller.
-         */
-        if (q->elevator) {
-                ioc_clear_queue(q);
-                elevator_exit(q, q->elevator);
-                q->elevator = NULL;
-        }
-
-        /*
-         * Remove all references to @q from the block cgroup controller before
-         * restoring @q->queue_lock to avoid that restoring this pointer causes
-         * e.g. blkcg_print_blkgs() to crash.
-         */
-        blkcg_exit_queue(q);
-
-        /*
-         * Since the cgroup code may dereference the @q->backing_dev_info
-         * pointer, only decrease its reference count after having removed the
-         * association with the block cgroup controller.
-         */
-        bdi_put(q->backing_dev_info);
+        blk_exit_queue(q);
 
         if (q->mq_ops)
                 blk_mq_free_queue(q);
diff --git a/block/blk.h b/block/blk.h
index 69b14cd2bb22..d4d67e948920 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -130,6 +130,7 @@ void blk_free_flush_queue(struct blk_flush_queue *q);
 int blk_init_rl(struct request_list *rl, struct request_queue *q,
                 gfp_t gfp_mask);
 void blk_exit_rl(struct request_queue *q, struct request_list *rl);
+void blk_exit_queue(struct request_queue *q);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
                         struct bio *bio);
 void blk_queue_bypass_start(struct request_queue *q);