block: remove QUEUE_FLAG_DISCARD

Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> [drbd]
Acked-by: Jan Höppner <hoeppner@linux.ibm.com> [s390]
Acked-by: Coly Li <colyli@suse.de> [bcache]
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220415045258.199825-25-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

16 files changed, 22 insertions, 106 deletions

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index fdd0194f84dd..e27f67f06a42 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -1005,7 +1005,7 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
 		bio_get(s->iop.bio);
 
 		if (bio_op(bio) == REQ_OP_DISCARD &&
-		    !blk_queue_discard(bdev_get_queue(dc->bdev)))
+		    !bdev_max_discard_sectors(dc->bdev))
 			goto insert_data;
 
 		/* I/O request sent to backing device */
@@ -1115,7 +1115,7 @@ static void detached_dev_do_request(struct bcache_device *d, struct bio *bio,
 	bio->bi_private = ddip;
 
 	if ((bio_op(bio) == REQ_OP_DISCARD) &&
-	    !blk_queue_discard(bdev_get_queue(dc->bdev)))
+	    !bdev_max_discard_sectors(dc->bdev))
 		bio->bi_end_io(bio);
 	else
 		submit_bio_noacct(bio);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index bf3de149d3c9..2f49e31142f6 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -973,7 +973,6 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
 
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, d->disk->queue);
 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, d->disk->queue);
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, d->disk->queue);
 
 	blk_queue_write_cache(q, true, true);
 
@@ -2350,7 +2349,7 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 	ca->bdev->bd_holder = ca;
 	ca->sb_disk = sb_disk;
 
-	if (blk_queue_discard(bdev_get_queue(bdev)))
+	if (bdev_max_discard_sectors((bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
 
 	ret = cache_alloc(ca);
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index d1029d71ff3b..c6f677059214 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -1151,7 +1151,7 @@ STORE(__bch_cache)
 	if (attr == &sysfs_discard) {
 		bool v = strtoul_or_return(buf);
 
-		if (blk_queue_discard(bdev_get_queue(ca->bdev)))
+		if (bdev_max_discard_sectors(ca->bdev))
 			ca->discard = v;
 
 		if (v != CACHE_DISCARD(&ca->sb)) {
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 780a61bc6cc0..28c5de8eca4a 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -3329,13 +3329,6 @@ static int cache_iterate_devices(struct dm_target *ti,
 	return r;
 }
 
-static bool origin_dev_supports_discard(struct block_device *origin_bdev)
-{
-	struct request_queue *q = bdev_get_queue(origin_bdev);
-
-	return blk_queue_discard(q);
-}
-
 /*
  * If discard_passdown was enabled verify that the origin device
  * supports discards.  Disable discard_passdown if not.
@@ -3349,7 +3342,7 @@ static void disable_passdown_if_not_supported(struct cache *cache)
 	if (!cache->features.discard_passdown)
 		return;
 
-	if (!origin_dev_supports_discard(origin_bdev))
+	if (!bdev_max_discard_sectors(origin_bdev))
 		reason = "discard unsupported";
 
 	else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
diff --git a/drivers/md/dm-clone-target.c b/drivers/md/dm-clone-target.c
index 128316a73d01..811b0a5379d0 100644
--- a/drivers/md/dm-clone-target.c
+++ b/drivers/md/dm-clone-target.c
@@ -2016,13 +2016,6 @@ static void clone_resume(struct dm_target *ti)
 	do_waker(&clone->waker.work);
 }
 
-static bool bdev_supports_discards(struct block_device *bdev)
-{
-	struct request_queue *q = bdev_get_queue(bdev);
-
-	return (q && blk_queue_discard(q));
-}
-
 /*
  * If discard_passdown was enabled verify that the destination device supports
  * discards. Disable discard_passdown if not.
@@ -2036,7 +2029,7 @@ static void disable_passdown_if_not_supported(struct clone *clone)
 	if (!test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags))
 		return;
 
-	if (!bdev_supports_discards(dest_dev))
+	if (!bdev_max_discard_sectors(dest_dev))
 		reason = "discard unsupported";
 	else if (dest_limits->max_discard_sectors < clone->region_size)
 		reason = "max discard sectors smaller than a region";
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index c9d036d6bb2e..e194226c89e5 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -866,9 +866,8 @@ static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv,
 static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct log_writes_c *lc = ti->private;
-	struct request_queue *q = bdev_get_queue(lc->dev->bdev);
 
-	if (!q || !blk_queue_discard(q)) {
+	if (!bdev_max_discard_sectors(lc->dev->bdev)) {
 		lc->device_supports_discard = false;
 		limits->discard_granularity = lc->sectorsize;
 		limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT);
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 2b26435a6946..9526ccbedafb 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -2963,13 +2963,8 @@ static void configure_discard_support(struct raid_set *rs)
 	raid456 = rs_is_raid456(rs);
 
 	for (i = 0; i < rs->raid_disks; i++) {
-		struct request_queue *q;
-
-		if (!rs->dev[i].rdev.bdev)
-			continue;
-
-		q = bdev_get_queue(rs->dev[i].rdev.bdev);
-		if (!q || !blk_queue_discard(q))
+		if (!rs->dev[i].rdev.bdev ||
+		    !bdev_max_discard_sectors(rs->dev[i].rdev.bdev))
 			return;
 
 		if (raid456) {
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index d46839faa0ca..0dff6907fd00 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1888,9 +1888,7 @@ static bool dm_table_supports_nowait(struct dm_table *t)
 static int device_not_discard_capable(struct dm_target *ti, struct dm_dev *dev,
 				      sector_t start, sector_t len, void *data)
 {
-	struct request_queue *q = bdev_get_queue(dev->bdev);
-
-	return !blk_queue_discard(q);
+	return !bdev_max_discard_sectors(dev->bdev);
 }
 
 static bool dm_table_supports_discards(struct dm_table *t)
@@ -1970,15 +1968,12 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 		blk_queue_flag_clear(QUEUE_FLAG_NOWAIT, q);
 
 	if (!dm_table_supports_discards(t)) {
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
-		/* Must also clear discard limits... */
 		q->limits.max_discard_sectors = 0;
 		q->limits.max_hw_discard_sectors = 0;
 		q->limits.discard_granularity = 0;
 		q->limits.discard_alignment = 0;
 		q->limits.discard_misaligned = 0;
-	} else
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
+	}
 
 	if (dm_table_supports_secure_erase(t))
 		blk_queue_flag_set(QUEUE_FLAG_SECERASE, q);
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 4d25d0e27031..eded4bcc4545 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2802,13 +2802,6 @@ static void requeue_bios(struct pool *pool)
 /*----------------------------------------------------------------
  * Binding of control targets to a pool object
  *--------------------------------------------------------------*/
-static bool data_dev_supports_discard(struct pool_c *pt)
-{
-	struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
-
-	return blk_queue_discard(q);
-}
-
 static bool is_factor(sector_t block_size, uint32_t n)
 {
 	return !sector_div(block_size, n);
@@ -2828,7 +2821,7 @@ static void disable_passdown_if_not_supported(struct pool_c *pt)
 	if (!pt->adjusted_pf.discard_passdown)
 		return;
 
-	if (!data_dev_supports_discard(pt))
+	if (!bdev_max_discard_sectors(pt->data_dev->bdev))
 		reason = "discard unsupported";
 
 	else if (data_limits->max_discard_sectors < pool->sectors_per_block)
@@ -4057,8 +4050,6 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
 		/*
 		 * Must explicitly disallow stacking discard limits otherwise the
 		 * block layer will stack them if pool's data device has support.
-		 * QUEUE_FLAG_DISCARD wouldn't be set but there is no way for the
-		 * user to see that, so make sure to set all discard limits to 0.
 		 */
 		limits->discard_granularity = 0;
 		return;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 82957bd460e8..39081338ca61 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -955,7 +955,6 @@ void disable_discard(struct mapped_device *md)
 
 	/* device doesn't really support DISCARD, disable it */
 	limits->max_discard_sectors = 0;
-	blk_queue_flag_clear(QUEUE_FLAG_DISCARD, md->queue);
 }
 
 void disable_write_zeroes(struct mapped_device *md)
@@ -982,7 +981,7 @@ static void clone_endio(struct bio *bio)
 
 	if (unlikely(error == BLK_STS_TARGET)) {
 		if (bio_op(bio) == REQ_OP_DISCARD &&
-		    !q->limits.max_discard_sectors)
+		    !bdev_max_discard_sectors(bio->bi_bdev))
 			disable_discard(md);
 		else if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
 			 !q->limits.max_write_zeroes_sectors)
diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
index 0f55b079371b..138a3b25c5c8 100644
--- a/drivers/md/md-linear.c
+++ b/drivers/md/md-linear.c
@@ -64,7 +64,6 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
 	struct linear_conf *conf;
 	struct md_rdev *rdev;
 	int i, cnt;
-	bool discard_supported = false;
 
 	conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
 	if (!conf)
@@ -96,9 +95,6 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
 
 		conf->array_sectors += rdev->sectors;
 		cnt++;
-
-		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
-			discard_supported = true;
 	}
 	if (cnt != raid_disks) {
 		pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
@@ -106,11 +102,6 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
 		goto out;
 	}
 
-	if (!discard_supported)
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
-	else
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
-
 	/*
 	 * Here we calculate the device offsets.
 	 */
@@ -252,7 +243,7 @@ static bool linear_make_request(struct mddev *mddev, struct bio *bio)
 		start_sector + data_offset;
 
 	if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
-		     !blk_queue_discard(bio->bi_bdev->bd_disk->queue))) {
+		     !bdev_max_discard_sectors(bio->bi_bdev))) {
 		/* Just ignore it */
 		bio_endio(bio);
 	} else {
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index b21e101183f4..7231f5e1eaa7 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -399,7 +399,6 @@ static int raid0_run(struct mddev *mddev)
 	conf = mddev->private;
 	if (mddev->queue) {
 		struct md_rdev *rdev;
-		bool discard_supported = false;
 
 		blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
@@ -412,13 +411,7 @@ static int raid0_run(struct mddev *mddev)
 		rdev_for_each(rdev, mddev) {
 			disk_stack_limits(mddev->gendisk, rdev->bdev,
 					  rdev->data_offset << 9);
-			if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
-				discard_supported = true;
 		}
-		if (!discard_supported)
-			blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
-		else
-			blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
 	}
 
 	/* calculate array device size */
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b7b21a4793d4..5aed2c8b746e 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -806,7 +806,7 @@ static void flush_bio_list(struct r1conf *conf, struct bio *bio)
 		if (test_bit(Faulty, &rdev->flags)) {
 			bio_io_error(bio);
 		} else if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
-				    !blk_queue_discard(bio->bi_bdev->bd_disk->queue)))
+				    !bdev_max_discard_sectors(bio->bi_bdev)))
 			/* Just ignore it */
 			bio_endio(bio);
 		else
@@ -1830,8 +1830,6 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 			break;
 		}
 	}
-	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
 	print_conf(conf);
 	return err;
 }
@@ -3110,7 +3108,6 @@ static int raid1_run(struct mddev *mddev)
 	int i;
 	struct md_rdev *rdev;
 	int ret;
-	bool discard_supported = false;
 
 	if (mddev->level != 1) {
 		pr_warn("md/raid1:%s: raid level not set to mirroring (%d)\n",
@@ -3145,8 +3142,6 @@ static int raid1_run(struct mddev *mddev)
 			continue;
 		disk_stack_limits(mddev->gendisk, rdev->bdev,
 				  rdev->data_offset << 9);
-		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
-			discard_supported = true;
 	}
 
 	mddev->degraded = 0;
@@ -3183,15 +3178,6 @@ static int raid1_run(struct mddev *mddev)
 
 	md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
 
-	if (mddev->queue) {
-		if (discard_supported)
-			blk_queue_flag_set(QUEUE_FLAG_DISCARD,
-						mddev->queue);
-		else
-			blk_queue_flag_clear(QUEUE_FLAG_DISCARD,
-						  mddev->queue);
-	}
-
 	ret = md_integrity_register(mddev);
 	if (ret) {
 		md_unregister_thread(&mddev->thread);
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 0987916066f2..834eb3ba95a6 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -895,7 +895,7 @@ static void flush_pending_writes(struct r10conf *conf)
 			if (test_bit(Faulty, &rdev->flags)) {
 				bio_io_error(bio);
 			} else if (unlikely((bio_op(bio) ==  REQ_OP_DISCARD) &&
-					    !blk_queue_discard(bio->bi_bdev->bd_disk->queue)))
+					    !bdev_max_discard_sectors(bio->bi_bdev)))
 				/* Just ignore it */
 				bio_endio(bio);
 			else
@@ -1090,7 +1090,7 @@ static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
 		if (test_bit(Faulty, &rdev->flags)) {
 			bio_io_error(bio);
 		} else if (unlikely((bio_op(bio) ==  REQ_OP_DISCARD) &&
-				    !blk_queue_discard(bio->bi_bdev->bd_disk->queue)))
+				    !bdev_max_discard_sectors(bio->bi_bdev)))
 			/* Just ignore it */
 			bio_endio(bio);
 		else
@@ -2151,8 +2151,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 		rcu_assign_pointer(p->rdev, rdev);
 		break;
 	}
-	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
 
 	print_conf(conf);
 	return err;
@@ -4076,7 +4074,6 @@ static int raid10_run(struct mddev *mddev)
 	sector_t size;
 	sector_t min_offset_diff = 0;
 	int first = 1;
-	bool discard_supported = false;
 
 	if (mddev_init_writes_pending(mddev) < 0)
 		return -ENOMEM;
@@ -4147,20 +4144,9 @@ static int raid10_run(struct mddev *mddev)
 					  rdev->data_offset << 9);
 
 		disk->head_position = 0;
-
-		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
-			discard_supported = true;
 		first = 0;
 	}
 
-	if (mddev->queue) {
-		if (discard_supported)
-			blk_queue_flag_set(QUEUE_FLAG_DISCARD,
-						mddev->queue);
-		else
-			blk_queue_flag_clear(QUEUE_FLAG_DISCARD,
-						  mddev->queue);
-	}
 	/* need to check that every block has at least one working mirror */
 	if (!enough(conf, -1)) {
 		pr_err("md/raid10:%s: not enough operational mirrors.\n",
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index a7d50ff9020a..c3cbf9a574a3 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1318,7 +1318,7 @@ static void r5l_write_super_and_discard_space(struct r5l_log *log,
 
 	r5l_write_super(log, end);
 
-	if (!blk_queue_discard(bdev_get_queue(bdev)))
+	if (!bdev_max_discard_sectors(bdev))
 		return;
 
 	mddev = log->rdev->mddev;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0bbae0e63866..59f91e392a2a 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7776,14 +7776,10 @@ static int raid5_run(struct mddev *mddev)
 		 * A better idea might be to turn DISCARD into WRITE_ZEROES
 		 * requests, as that is required to be safe.
 		 */
-		if (devices_handle_discard_safely &&
-		    mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
-		    mddev->queue->limits.discard_granularity >= stripe)
-			blk_queue_flag_set(QUEUE_FLAG_DISCARD,
-						mddev->queue);
-		else
-			blk_queue_flag_clear(QUEUE_FLAG_DISCARD,
-						mddev->queue);
+		if (!devices_handle_discard_safely ||
+		    mddev->queue->limits.max_discard_sectors < (stripe >> 9) ||
+		    mddev->queue->limits.discard_granularity < stripe)
+			blk_queue_max_discard_sectors(mddev->queue, 0);
 
 		blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
 	}