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>

diff --git a/block/blk-core.c b/block/blk-core.c
index f9ad73d..49af34b 100644 (file)
--- 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 69b14cd..d4d67e9 100644 (file)
--- 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);