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 <sarthakkukr...@chromium.org>
---
 drivers/md/dm-crypt.c         |  5 ++++-
 drivers/md/dm-linear.c        |  2 ++
 drivers/md/dm-snap.c          |  8 ++++++++
 drivers/md/dm-table.c         | 23 +++++++++++++++++++++++
 drivers/md/dm.c               |  6 ++++++
 include/linux/device-mapper.h | 17 +++++++++++++++++
 6 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 8b47b913ee83..aa8072d6d7bf 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -3336,6 +3336,9 @@ 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;
+       ti->provision_supported = true;
+
        ret = -ENOMEM;
        cc->io_queue = alloc_workqueue("kcryptd_io/%s", WQ_MEM_RECLAIM, 1, 
devname);
        if (!cc->io_queue) {
@@ -3390,7 +3393,7 @@ 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..66e50f5b0665 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -62,6 +62,8 @@ 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->provision_supported = true;
        ti->private = lc;
        return 0;
 
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 9c49f53760d0..07927bb1e711 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1358,6 +1358,8 @@ 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;
+       ti->provision_supported = true;
 
        /* Add snapshot to the list of snapshots for this origin */
        /* Exceptions aren't triggered till snapshot_resume() is called */
@@ -2003,6 +2005,11 @@ 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 +2420,7 @@ 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..9301f050529f 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.
         */
-- 
2.40.0.634.g4ca3ef3211-goog

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