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>

35 files changed, 35 insertions, 159 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 7b501c8d5992..912560f611c3 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -942,7 +942,7 @@ int drbd_send_sizes(struct drbd_peer_device *peer_device, int trigger_reply, enu
 			cpu_to_be32(bdev_alignment_offset(bdev));
 		p->qlim->io_min = cpu_to_be32(bdev_io_min(bdev));
 		p->qlim->io_opt = cpu_to_be32(bdev_io_opt(bdev));
-		p->qlim->discard_enabled = blk_queue_discard(q);
+		p->qlim->discard_enabled = !!bdev_max_discard_sectors(bdev);
 		put_ldev(device);
 	} else {
 		struct request_queue *q = device->rq_queue;
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index a0a06e238e91..0678ceb50579 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1210,7 +1210,7 @@ static void decide_on_discard_support(struct drbd_device *device,
 		first_peer_device(device)->connection;
 	struct request_queue *q = device->rq_queue;
 
-	if (bdev && !blk_queue_discard(bdev->backing_bdev->bd_disk->queue))
+	if (bdev && !bdev_max_discard_sectors(bdev->backing_bdev))
 		goto not_supported;
 
 	if (connection->cstate >= C_CONNECTED &&
@@ -1230,30 +1230,16 @@ static void decide_on_discard_support(struct drbd_device *device,
 	 */
 	blk_queue_discard_granularity(q, 512);
 	q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 	q->limits.max_write_zeroes_sectors =
 		drbd_max_discard_sectors(connection);
 	return;
 
 not_supported:
-	blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
 	blk_queue_discard_granularity(q, 0);
 	q->limits.max_discard_sectors = 0;
 	q->limits.max_write_zeroes_sectors = 0;
 }
 
-static void fixup_discard_if_not_supported(struct request_queue *q)
-{
-	/* To avoid confusion, if this queue does not support discard, clear
-	 * max_discard_sectors, which is what lsblk -D reports to the user.
-	 * Older kernels got this wrong in "stack limits".
-	 * */
-	if (!blk_queue_discard(q)) {
-		blk_queue_max_discard_sectors(q, 0);
-		blk_queue_discard_granularity(q, 0);
-	}
-}
-
 static void fixup_write_zeroes(struct drbd_device *device, struct request_queue *q)
 {
 	/* Fixup max_write_zeroes_sectors after blk_stack_limits():
@@ -1300,7 +1286,6 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 		blk_stack_limits(&q->limits, &b->limits, 0);
 		disk_update_readahead(device->vdisk);
 	}
-	fixup_discard_if_not_supported(q);
 	fixup_write_zeroes(device, q);
 }
 
@@ -1447,7 +1432,7 @@ static void sanitize_disk_conf(struct drbd_device *device, struct disk_conf *dis
 	if (disk_conf->al_extents > drbd_al_extents_max(nbc))
 		disk_conf->al_extents = drbd_al_extents_max(nbc);
 
-	if (!blk_queue_discard(q)) {
+	if (!bdev_max_discard_sectors(bdev)) {
 		if (disk_conf->rs_discard_granularity) {
 			disk_conf->rs_discard_granularity = 0; /* disable feature */
 			drbd_info(device, "rs_discard_granularity feature disabled\n");
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 0b4c7de46398..8a4a47da56fe 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1575,11 +1575,10 @@ int drbd_issue_discard_or_zero_out(struct drbd_device *device, sector_t start, u
 
 static bool can_do_reliable_discards(struct drbd_device *device)
 {
-	struct request_queue *q = bdev_get_queue(device->ldev->backing_bdev);
 	struct disk_conf *dc;
 	bool can_do;
 
-	if (!blk_queue_discard(q))
+	if (!bdev_max_discard_sectors(device->ldev->backing_bdev))
 		return false;
 
 	rcu_read_lock();
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 8d800d46e498..0e061c9896ef 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -314,15 +314,12 @@ static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
 
 	mode |= FALLOC_FL_KEEP_SIZE;
 
-	if (!blk_queue_discard(lo->lo_queue)) {
-		ret = -EOPNOTSUPP;
-		goto out;
-	}
+	if (!bdev_max_discard_sectors(lo->lo_device))
+		return -EOPNOTSUPP;
 
 	ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
 	if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
-		ret = -EIO;
- out:
+		return -EIO;
 	return ret;
 }
 
@@ -787,12 +784,10 @@ static void loop_config_discard(struct loop_device *lo)
 		q->limits.discard_granularity = granularity;
 		blk_queue_max_discard_sectors(q, max_discard_sectors);
 		blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 	} else {
 		q->limits.discard_granularity = 0;
 		blk_queue_max_discard_sectors(q, 0);
 		blk_queue_max_write_zeroes_sectors(q, 0);
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
 	}
 	q->limits.discard_alignment = 0;
 }
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 5a1f98494ddd..4729aef8c646 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1231,8 +1231,6 @@ static void nbd_parse_flags(struct nbd_device *nbd)
 		set_disk_ro(nbd->disk, true);
 	else
 		set_disk_ro(nbd->disk, false);
-	if (config->flags & NBD_FLAG_SEND_TRIM)
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 	if (config->flags & NBD_FLAG_SEND_FLUSH) {
 		if (config->flags & NBD_FLAG_SEND_FUA)
 			blk_queue_write_cache(nbd->disk->queue, true, true);
@@ -1319,8 +1317,7 @@ static void nbd_config_put(struct nbd_device *nbd)
 		nbd->tag_set.timeout = 0;
 		nbd->disk->queue->limits.discard_granularity = 0;
 		nbd->disk->queue->limits.discard_alignment = 0;
-		blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
+		blk_queue_max_discard_sectors(nbd->disk->queue, 0);
 
 		mutex_unlock(&nbd->config_lock);
 		nbd_put(nbd);
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index c441a4972064..5cb4c92cdffe 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1767,7 +1767,6 @@ static void null_config_discard(struct nullb *nullb)
 	nullb->q->limits.discard_granularity = nullb->dev->blocksize;
 	nullb->q->limits.discard_alignment = nullb->dev->blocksize;
 	blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
 }
 
 static const struct block_device_operations null_bio_ops = {
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b844432bad20..2b21f717cce1 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4942,7 +4942,6 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 	blk_queue_io_opt(q, rbd_dev->opts->alloc_size);
 
 	if (rbd_dev->opts->trim) {
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 		q->limits.discard_granularity = rbd_dev->opts->alloc_size;
 		blk_queue_max_discard_sectors(q, objset_bytes >> SECTOR_SHIFT);
 		blk_queue_max_write_zeroes_sectors(q, objset_bytes >> SECTOR_SHIFT);
diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
index b66e8840b94b..efa99a388450 100644
--- a/drivers/block/rnbd/rnbd-clt.c
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -1364,8 +1364,6 @@ static void setup_request_queue(struct rnbd_clt_dev *dev)
 	blk_queue_max_discard_sectors(dev->queue, dev->max_discard_sectors);
 	dev->queue->limits.discard_granularity	= dev->discard_granularity;
 	dev->queue->limits.discard_alignment	= dev->discard_alignment;
-	if (dev->max_discard_sectors)
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, dev->queue);
 	if (dev->secure_discard)
 		blk_queue_flag_set(QUEUE_FLAG_SECERASE, dev->queue);
 
diff --git a/drivers/block/rnbd/rnbd-srv-dev.h b/drivers/block/rnbd/rnbd-srv-dev.h
index f82fbb4bbda8..1f7e1c8fd4d9 100644
--- a/drivers/block/rnbd/rnbd-srv-dev.h
+++ b/drivers/block/rnbd/rnbd-srv-dev.h
@@ -49,9 +49,6 @@ static inline int rnbd_dev_get_secure_discard(const struct rnbd_dev *dev)
 
 static inline int rnbd_dev_get_max_discard_sects(const struct rnbd_dev *dev)
 {
-	if (!blk_queue_discard(bdev_get_queue(dev->bdev)))
-		return 0;
-
 	return bdev_max_discard_sectors(dev->bdev);
 }
 
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index a8bcf3f664af..6ccf15253dee 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -888,8 +888,6 @@ static int virtblk_probe(struct virtio_device *vdev)
 			v = sg_elems;
 		blk_queue_max_discard_segments(q,
 					       min(v, MAX_DISCARD_SEGMENTS));
-
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 	}
 
 	if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 8b691fe50475..83cd08041e6b 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -583,7 +583,7 @@ static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info
 	if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1))
 		return;
 
-	if (blk_queue_discard(q)) {
+	if (bdev_max_discard_sectors(bdev)) {
 		err = xenbus_printf(xbt, dev->nodename,
 			"discard-granularity", "%u",
 			q->limits.discard_granularity);
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 003056d4f7f5..e13cb4d48f1e 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -944,7 +944,6 @@ static void blkif_set_queue_limits(struct blkfront_info *info)
 	blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
 
 	if (info->feature_discard) {
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
 		blk_queue_max_discard_sectors(rq, get_capacity(gd));
 		rq->limits.discard_granularity = info->discard_granularity ?:
 						 info->physical_sector_size;
@@ -1606,7 +1605,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 				blkif_req(req)->error = BLK_STS_NOTSUPP;
 				info->feature_discard = 0;
 				info->feature_secdiscard = 0;
-				blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
+				blk_queue_max_discard_sectors(rq, 0);
 				blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
 			}
 			break;
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e9474b02012d..59ff444bf6c7 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1952,7 +1952,6 @@ static int zram_add(void)
 	blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 	zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
 	blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, zram->disk->queue);
 
 	/*
 	 * zram_bio_discard() will clear all logical blocks if logical block
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);
 	}
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index c69b2d9df6f1..cac6315010a3 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -183,7 +183,6 @@ static void mmc_queue_setup_discard(struct request_queue *q,
 	if (!max_discard)
 		return;
 
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 	blk_queue_max_discard_sectors(q, max_discard);
 	q->limits.discard_granularity = card->pref_erase << 9;
 	/* granularity must not be greater than max. discard */
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 64d2b093f114..f73172111465 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -377,7 +377,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
 
 	if (tr->discard) {
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq);
 		blk_queue_max_discard_sectors(new->rq, UINT_MAX);
 		new->rq->limits.discard_granularity = tr->blksize;
 	}
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e1846d04817f..b9b0fbde97c8 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1621,7 +1621,7 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 	u32 size = queue_logical_block_size(queue);
 
 	if (ctrl->max_discard_sectors == 0) {
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, queue);
+		blk_queue_max_discard_sectors(queue, 0);
 		return;
 	}
 
@@ -1632,7 +1632,7 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 	queue->limits.discard_granularity = size;
 
 	/* If discard is already enabled, don't reset queue limits */
-	if (blk_queue_flag_test_and_set(QUEUE_FLAG_DISCARD, queue))
+	if (queue->limits.max_discard_sectors)
 		return;
 
 	blk_queue_max_discard_sectors(queue, ctrl->max_discard_sectors);
diff --git a/drivers/s390/block/dasd_fba.c b/drivers/s390/block/dasd_fba.c
index e084f4dedddd..8bd5665db919 100644
--- a/drivers/s390/block/dasd_fba.c
+++ b/drivers/s390/block/dasd_fba.c
@@ -791,7 +791,6 @@ static void dasd_fba_setup_blk_queue(struct dasd_block *block)
 
 	blk_queue_max_discard_sectors(q, max_discard_sectors);
 	blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 }
 
 static int dasd_fba_pe_handler(struct dasd_device *device,
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index dc6e55761fd1..9694e2cfaf9a 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -797,7 +797,6 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
 	case SD_LBP_FULL:
 	case SD_LBP_DISABLE:
 		blk_queue_max_discard_sectors(q, 0);
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
 		return;
 
 	case SD_LBP_UNMAP:
@@ -830,7 +829,6 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
 	}
 
 	blk_queue_max_discard_sectors(q, max_blocks * (logical_block_size >> 9));
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 }
 
 static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index c3e25bac90d5..6cb9f8784327 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -838,7 +838,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
 	struct request_queue *q = bdev_get_queue(bdev);
 	int block_size = bdev_logical_block_size(bdev);
 
-	if (!blk_queue_discard(q))
+	if (!bdev_max_discard_sectors(bdev))
 		return false;
 
 	attrib->max_unmap_lba_count =