block: remove QUEUE_FLAG_STACKABLE

We already have a queue_is_rq_based helper to check if a request_queue
is request based, so we can remove the flag for it.

Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-debugfs.c

@@ -54,7 +54,6 @@ static const char *const blk_queue_flag_name[] = {
 	QUEUE_FLAG_NAME(NOMERGES),
 	QUEUE_FLAG_NAME(SAME_COMP),
 	QUEUE_FLAG_NAME(FAIL_IO),
-	QUEUE_FLAG_NAME(STACKABLE),
 	QUEUE_FLAG_NAME(NONROT),
 	QUEUE_FLAG_NAME(IO_STAT),
 	QUEUE_FLAG_NAME(DISCARD),

block/elevator.c

@@ -1118,7 +1118,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
 	struct elevator_type *__e;
 	int len = 0;
 
-	if (!blk_queue_stackable(q))
+	if (!queue_is_rq_based(q))
 		return sprintf(name, "none\n");
 
 	if (!q->elevator)

drivers/md/dm-rq.c

@@ -56,7 +56,7 @@ static unsigned dm_get_blk_mq_queue_depth(void)
 
 int dm_request_based(struct mapped_device *md)
 {
-	return blk_queue_stackable(md->queue);
+	return queue_is_rq_based(md->queue);
 }
 
 static void dm_old_start_queue(struct request_queue *q)

drivers/md/dm-table.c

@@ -1000,7 +1000,7 @@ verify_rq_based:
 	list_for_each_entry(dd, devices, list) {
 		struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
 
-		if (!blk_queue_stackable(q)) {
+		if (!queue_is_rq_based(q)) {
 			DMERR("table load rejected: including"
 			      " non-request-stackable devices");
 			return -EINVAL;
@@ -1847,19 +1847,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	 */
 	if (blk_queue_add_random(q) && dm_table_all_devices_attribute(t, device_is_not_random))
 		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q);
-
-	/*
-	 * QUEUE_FLAG_STACKABLE must be set after all queue settings are
-	 * visible to other CPUs because, once the flag is set, incoming bios
-	 * are processed by request-based dm, which refers to the queue
-	 * settings.
-	 * Until the flag set, bios are passed to bio-based dm and queued to
-	 * md->deferred where queue settings are not needed yet.
-	 * Those bios are passed to request-based dm at the resume time.
-	 */
-	smp_mb();
-	if (dm_table_request_based(t))
-		queue_flag_set_unlocked(QUEUE_FLAG_STACKABLE, q);
 }
 
 unsigned int dm_table_get_num_targets(struct dm_table *t)

drivers/md/dm.c

@@ -1612,17 +1612,6 @@ static void dm_wq_work(struct work_struct *work);
 
 void dm_init_md_queue(struct mapped_device *md)
 {
-	/*
-	 * Request-based dm devices cannot be stacked on top of bio-based dm
-	 * devices.  The type of this dm device may not have been decided yet.
-	 * The type is decided at the first table loading time.
-	 * To prevent problematic device stacking, clear the queue flag
-	 * for request stacking support until then.
-	 *
-	 * This queue is new, so no concurrency on the queue_flags.
-	 */
-	queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
-
 	/*
 	 * Initialize data that will only be used by a non-blk-mq DM queue
 	 * - must do so here (in alloc_dev callchain) before queue is used

include/linux/blkdev.h

@@ -609,7 +609,6 @@ struct request_queue {
 #define QUEUE_FLAG_NOMERGES     5	/* disable merge attempts */
 #define QUEUE_FLAG_SAME_COMP	6	/* complete on same CPU-group */
 #define QUEUE_FLAG_FAIL_IO	7	/* fake timeout */
-#define QUEUE_FLAG_STACKABLE	8	/* supports request stacking */
 #define QUEUE_FLAG_NONROT	9	/* non-rotational device (SSD) */
 #define QUEUE_FLAG_VIRT        QUEUE_FLAG_NONROT /* paravirt device */
 #define QUEUE_FLAG_IO_STAT     10	/* do IO stats */
@@ -633,12 +632,10 @@ struct request_queue {
 #define QUEUE_FLAG_QUIESCED    28	/* queue has been quiesced */
 
 #define QUEUE_FLAG_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
-				 (1 << QUEUE_FLAG_STACKABLE)	|	\
 				 (1 << QUEUE_FLAG_SAME_COMP)	|	\
 				 (1 << QUEUE_FLAG_ADD_RANDOM))
 
 #define QUEUE_FLAG_MQ_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
-				 (1 << QUEUE_FLAG_STACKABLE)	|	\
 				 (1 << QUEUE_FLAG_SAME_COMP)	|	\
 				 (1 << QUEUE_FLAG_POLL))
 
@@ -722,8 +719,6 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 #define blk_queue_nonrot(q)	test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
 #define blk_queue_io_stat(q)	test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
 #define blk_queue_add_random(q)	test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
-#define blk_queue_stackable(q)	\
-	test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
 #define blk_queue_discard(q)	test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
 #define blk_queue_secure_erase(q) \
 	(test_bit(QUEUE_FLAG_SECERASE, &(q)->queue_flags))