ublk_drv: fix request queue leak

Call blk_cleanup_queue() in release code path for fixing request
queue leak.

Also for-5.20/block has cleaned up blk_cleanup_queue(), which is
basically merged to del_gendisk() if blk_mq_alloc_disk() is used
for allocating disk and queue.

However, ublk may not add disk in case of starting device failure, then
del_gendisk() won't be called when removing ublk device, so blk_mq_exit_queue
will not be callsed, and it can be bit hard to deal with this kind of
merge conflict.

Turns out ublk's queue/disk use model is very similar with scsi, so switch
to scsi's model by allocating disk and queue independently, then it can be
quite easy to handle v5.20 merge conflict by replacing blk_cleanup_queue
with blk_mq_destroy_queue.
Reported-by: Jens Axboe <axboe@kernel.dk>
Fixes: 71f28f31 ("ublk_drv: add io_uring based userspace block driver")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220714103201.131648-1-ming.lei@redhat.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/ublk_drv.c

@@ -155,6 +155,8 @@ static DEFINE_MUTEX(ublk_ctl_mutex);
 
 static struct miscdevice ublk_misc;
 
+static struct lock_class_key ublk_bio_compl_lkclass;
+
 static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)
 {
 	if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&
@@ -634,7 +636,7 @@ static void ublk_commit_rqs(struct blk_mq_hw_ctx *hctx)
 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 		unsigned int hctx_idx)
 {
-	struct ublk_device *ub = hctx->queue->queuedata;
+	struct ublk_device *ub = driver_data;
 	struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 
 	hctx->driver_data = ubq;
@@ -1076,6 +1078,8 @@ static void ublk_cdev_rel(struct device *dev)
 {
 	struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
 
+	blk_mq_destroy_queue(ub->ub_queue);
+
 	put_disk(ub->ub_disk);
 
 	blk_mq_free_tag_set(&ub->tag_set);
@@ -1165,14 +1169,17 @@ static int ublk_add_dev(struct ublk_device *ub)
 	if (err)
 		goto out_deinit_queues;
 
-	disk = ub->ub_disk = blk_mq_alloc_disk(&ub->tag_set, ub);
+	ub->ub_queue = blk_mq_init_queue(&ub->tag_set);
+	if (IS_ERR(ub->ub_queue))
+		goto out_cleanup_tags;
+	ub->ub_queue->queuedata = ub;
+
+	disk = ub->ub_disk = blk_mq_alloc_disk_for_queue(ub->ub_queue,
+						 &ublk_bio_compl_lkclass);
 	if (IS_ERR(disk)) {
 		err = PTR_ERR(disk);
-		goto out_cleanup_tags;
+		goto out_free_request_queue;
 	}
-	ub->ub_queue = ub->ub_disk->queue;
-
-	ub->ub_queue->queuedata = ub;
 
 	blk_queue_logical_block_size(ub->ub_queue, bsize);
 	blk_queue_physical_block_size(ub->ub_queue, bsize);
@@ -1204,6 +1211,8 @@ static int ublk_add_dev(struct ublk_device *ub)
 
 	return 0;
 
+out_free_request_queue:
+	blk_mq_destroy_queue(ub->ub_queue);
 out_cleanup_tags:
 	blk_mq_free_tag_set(&ub->tag_set);
 out_deinit_queues: