From 5fdee2127faa77c9c91862ad5e001dfab7013e92 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 5 Oct 2017 21:22:52 +0200
Subject: [PATCH] block: remove QUEUE_FLAG_STACKABLE
Git-commit: 5fdee2127faa77c9c91862ad5e001dfab7013e92
Patch-mainline: v4.15-rc1
References: bsc#1104967,FATE#325924,git fixes (block drivers)

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.

(Coly Li: rebased for SUSE 4.12 kernel code base)

Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>
---
 block/blk-mq-debugfs.c |    1 -
 block/elevator.c       |    2 +-
 drivers/md/dm-rq.c     |    2 +-
 drivers/md/dm-table.c  |   15 +--------------
 drivers/md/dm.c        |   11 -----------
 include/linux/blkdev.h |    5 -----
 6 files changed, 3 insertions(+), 33 deletions(-)

--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -56,7 +56,6 @@ static const char *const blk_queue_flag_
 	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),
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1118,7 +1118,7 @@ ssize_t elv_iosched_show(struct request_
 	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)
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -56,7 +56,7 @@ static unsigned dm_get_blk_mq_queue_dept
 
 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)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -999,7 +999,7 @@ 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;
@@ -1846,19 +1846,6 @@ void dm_table_set_restrictions(struct dm
 	 */
 	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)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1629,17 +1629,6 @@ static void dm_wq_work(struct work_struc
 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
 	 */
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -611,7 +611,6 @@ 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 */
@@ -635,12 +634,10 @@ 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))
 
@@ -717,8 +714,6 @@ static inline void queue_flag_clear(unsi
 #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))