[PATCH v6 3/5] dm: Add block provisioning support

[Sarthak Kukreti <sarthakkukreti@chromium.org>]

Add block provisioning support for device-mapper targets.
dm-crypt, dm-snap and dm-linear will, by default, passthrough
REQ_OP_PROVISION requests to the underlying device, if
supported.

Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
---
 drivers/md/dm-crypt.c         |  4 +++-
 drivers/md/dm-linear.c        |  1 +
 drivers/md/dm-snap.c          |  7 +++++++
 drivers/md/dm-table.c         | 23 +++++++++++++++++++++++
 drivers/md/dm.c               |  6 ++++++
 include/linux/device-mapper.h | 17 +++++++++++++++++
 6 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 8b47b913ee83..5a7c475ce6fc 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -3336,6 +3336,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		cc->tag_pool_max_sectors <<= cc->sector_shift;
 	}
 
+	ti->num_provision_bios = 1;
+
 	ret = -ENOMEM;
 	cc->io_queue = alloc_workqueue("kcryptd_io/%s", WQ_MEM_RECLAIM, 1, devname);
 	if (!cc->io_queue) {
@@ -3390,7 +3392,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio)
 	 * - for REQ_OP_DISCARD caller must use flush if IO ordering matters
 	 */
 	if (unlikely(bio->bi_opf & REQ_PREFLUSH ||
-	    bio_op(bio) == REQ_OP_DISCARD)) {
+	    bio_op(bio) == REQ_OP_DISCARD || bio_op(bio) == REQ_OP_PROVISION)) {
 		bio_set_dev(bio, cc->dev->bdev);
 		if (bio_sectors(bio))
 			bio->bi_iter.bi_sector = cc->start +
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index f4448d520ee9..74ee27ca551a 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -62,6 +62,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_discard_bios = 1;
 	ti->num_secure_erase_bios = 1;
 	ti->num_write_zeroes_bios = 1;
+	ti->num_provision_bios = 1;
 	ti->private = lc;
 	return 0;
 
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 9c49f53760d0..0dfda50ac4e0 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1358,6 +1358,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	if (s->discard_zeroes_cow)
 		ti->num_discard_bios = (s->discard_passdown_origin ? 2 : 1);
 	ti->per_io_data_size = sizeof(struct dm_snap_tracked_chunk);
+	ti->num_provision_bios = 1;
 
 	/* Add snapshot to the list of snapshots for this origin */
 	/* Exceptions aren't triggered till snapshot_resume() is called */
@@ -2003,6 +2004,11 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	/* If the block is already remapped - use that, else remap it */
 	e = dm_lookup_exception(&s->complete, chunk);
 	if (e) {
+		if (unlikely(bio_op(bio) == REQ_OP_PROVISION)) {
+			bio_endio(bio);
+			r = DM_MAPIO_SUBMITTED;
+			goto out_unlock;
+		}
 		remap_exception(s, e, bio, chunk);
 		if (unlikely(bio_op(bio) == REQ_OP_DISCARD) &&
 		    io_overlaps_chunk(s, bio)) {
@@ -2413,6 +2419,7 @@ static void snapshot_io_hints(struct dm_target *ti, struct queue_limits *limits)
 		/* All discards are split on chunk_size boundary */
 		limits->discard_granularity = snap->store->chunk_size;
 		limits->max_discard_sectors = snap->store->chunk_size;
+		limits->max_provision_sectors = snap->store->chunk_size;
 
 		up_read(&_origins_lock);
 	}
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 119db5e01080..282c530b0685 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1854,6 +1854,26 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t)
 	return true;
 }
 
+static int device_provision_capable(struct dm_target *ti, struct dm_dev *dev,
+				    sector_t start, sector_t len, void *data)
+{
+	return bdev_max_provision_sectors(dev->bdev);
+}
+
+static bool dm_table_supports_provision(struct dm_table *t)
+{
+	for (unsigned int i = 0; i < t->num_targets; i++) {
+		struct dm_target *ti = dm_table_get_target(t, i);
+
+		if (ti->provision_supported ||
+		    (ti->type->iterate_devices &&
+		    ti->type->iterate_devices(ti, device_provision_capable, NULL)))
+			return true;
+	}
+
+	return false;
+}
+
 static int device_not_nowait_capable(struct dm_target *ti, struct dm_dev *dev,
 				     sector_t start, sector_t len, void *data)
 {
@@ -1987,6 +2007,9 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	if (!dm_table_supports_write_zeroes(t))
 		q->limits.max_write_zeroes_sectors = 0;
 
+	if (!dm_table_supports_provision(t))
+		q->limits.max_provision_sectors = 0;
+
 	dm_table_verify_integrity(t);
 
 	/*
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3b694ba3a106..9b94121b8d38 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1609,6 +1609,7 @@ static bool is_abnormal_io(struct bio *bio)
 		case REQ_OP_DISCARD:
 		case REQ_OP_SECURE_ERASE:
 		case REQ_OP_WRITE_ZEROES:
+		case REQ_OP_PROVISION:
 			return true;
 		default:
 			break;
@@ -1641,6 +1642,11 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
 		if (ti->max_write_zeroes_granularity)
 			max_granularity = limits->max_write_zeroes_sectors;
 		break;
+	case REQ_OP_PROVISION:
+		num_bios = ti->num_provision_bios;
+		if (ti->max_provision_granularity)
+			max_granularity = limits->max_provision_sectors;
+		break;
 	default:
 		break;
 	}
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index a52d2b9a6846..9981378457d2 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -334,6 +334,12 @@ struct dm_target {
 	 */
 	unsigned int num_write_zeroes_bios;
 
+	/*
+	 * The number of PROVISION bios that will be submitted to the target.
+	 * The bio number can be accessed with dm_bio_get_target_bio_nr.
+	 */
+	unsigned int num_provision_bios;
+
 	/*
 	 * The minimum number of extra bytes allocated in each io for the
 	 * target to use.
@@ -358,6 +364,11 @@ struct dm_target {
 	 */
 	bool discards_supported:1;
 
+	/* Set if this target needs to receive provision requests regardless of
+	 * whether or not its underlying devices have support.
+	 */
+	bool provision_supported:1;
+
 	/*
 	 * Set if this target requires that discards be split on
 	 * 'max_discard_sectors' boundaries.
@@ -376,6 +387,12 @@ struct dm_target {
 	 */
 	bool max_write_zeroes_granularity:1;
 
+	/*
+	 * Set if this target requires that provisions be split on
+	 * 'max_provision_sectors' boundaries.
+	 */
+	bool max_provision_granularity:1;
+
 	/*
 	 * Set if we need to limit the number of in-flight bios when swapping.
 	 */
-- 
2.40.1.521.gf1e218fcd8-goog