dm zoned: drive-managed zoned block device target

The dm-zoned device mapper target provides transparent write access
to zoned block devices (ZBC and ZAC compliant block devices).
dm-zoned hides to the device user (a file system or an application
doing raw block device accesses) any constraint imposed on write
requests by the device, equivalent to a drive-managed zoned block
device model.

Write requests are processed using a combination of on-disk buffering
using the device conventional zones and direct in-place processing for
requests aligned to a zone sequential write pointer position.
A background reclaim process implemented using dm_kcopyd_copy ensures
that conventional zones are always available for executing unaligned
write requests. The reclaim process overhead is minimized by managing
buffer zones in a least-recently-written order and first targeting the
oldest buffer zones. Doing so, blocks under regular write access (such
as metadata blocks of a file system) remain stored in conventional
zones, resulting in no apparent overhead.

dm-zoned implementation focus on simplicity and on minimizing overhead
(CPU, memory and storage overhead). For a 14TB host-managed disk with
256 MB zones, dm-zoned memory usage per disk instance is at most about
3 MB and as little as 5 zones will be used internally for storing metadata
and performing buffer zone reclaim operations. This is achieved using
zone level indirection rather than a full block indirection system for
managing block movement between zones.

dm-zoned primary target is host-managed zoned block devices but it can
also be used with host-aware device models to mitigate potential
device-side performance degradation due to excessive random writing.

Zoned block devices can be formatted and checked for use with the dm-zoned
target using the dmzadm utility available at:

https://github.com/hgst/dm-zoned-tools

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
[Mike Snitzer partly refactored Damien's original work to cleanup the code]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 967 insertions, 0 deletions

diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
new file mode 100644
index 000000000000..2b538fa817f4
--- /dev/null
+++ b/drivers/md/dm-zoned-target.c
@@ -0,0 +1,967 @@
+/*
+ * Copyright (C) 2017 Western Digital Corporation or its affiliates.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-zoned.h"
+
+#include <linux/module.h>
+
+#define	DM_MSG_PREFIX		"zoned"
+
+#define DMZ_MIN_BIOS		8192
+
+/*
+ * Zone BIO context.
+ */
+struct dmz_bioctx {
+	struct dmz_target	*target;
+	struct dm_zone		*zone;
+	struct bio		*bio;
+	atomic_t		ref;
+	blk_status_t		status;
+};
+
+/*
+ * Chunk work descriptor.
+ */
+struct dm_chunk_work {
+	struct work_struct	work;
+	atomic_t		refcount;
+	struct dmz_target	*target;
+	unsigned int		chunk;
+	struct bio_list		bio_list;
+};
+
+/*
+ * Target descriptor.
+ */
+struct dmz_target {
+	struct dm_dev		*ddev;
+
+	unsigned long		flags;
+
+	/* Zoned block device information */
+	struct dmz_dev		*dev;
+
+	/* For metadata handling */
+	struct dmz_metadata     *metadata;
+
+	/* For reclaim */
+	struct dmz_reclaim	*reclaim;
+
+	/* For chunk work */
+	struct mutex		chunk_lock;
+	struct radix_tree_root	chunk_rxtree;
+	struct workqueue_struct *chunk_wq;
+
+	/* For cloned BIOs to zones */
+	struct bio_set		*bio_set;
+
+	/* For flush */
+	spinlock_t		flush_lock;
+	struct bio_list		flush_list;
+	struct delayed_work	flush_work;
+	struct workqueue_struct *flush_wq;
+};
+
+/*
+ * Flush intervals (seconds).
+ */
+#define DMZ_FLUSH_PERIOD	(10 * HZ)
+
+/*
+ * Target BIO completion.
+ */
+static inline void dmz_bio_endio(struct bio *bio, blk_status_t status)
+{
+	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+
+	if (bioctx->status == BLK_STS_OK && status != BLK_STS_OK)
+		bioctx->status = status;
+	bio_endio(bio);
+}
+
+/*
+ * Partial clone read BIO completion callback. This terminates the
+ * target BIO when there are no more references to its context.
+ */
+static void dmz_read_bio_end_io(struct bio *bio)
+{
+	struct dmz_bioctx *bioctx = bio->bi_private;
+	blk_status_t status = bio->bi_status;
+
+	bio_put(bio);
+	dmz_bio_endio(bioctx->bio, status);
+}
+
+/*
+ * Issue a BIO to a zone. The BIO may only partially process the
+ * original target BIO.
+ */
+static int dmz_submit_read_bio(struct dmz_target *dmz, struct dm_zone *zone,
+			       struct bio *bio, sector_t chunk_block,
+			       unsigned int nr_blocks)
+{
+	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	sector_t sector;
+	struct bio *clone;
+
+	/* BIO remap sector */
+	sector = dmz_start_sect(dmz->metadata, zone) + dmz_blk2sect(chunk_block);
+
+	/* If the read is not partial, there is no need to clone the BIO */
+	if (nr_blocks == dmz_bio_blocks(bio)) {
+		/* Setup and submit the BIO */
+		bio->bi_iter.bi_sector = sector;
+		atomic_inc(&bioctx->ref);
+		generic_make_request(bio);
+		return 0;
+	}
+
+	/* Partial BIO: we need to clone the BIO */
+	clone = bio_clone_fast(bio, GFP_NOIO, dmz->bio_set);
+	if (!clone)
+		return -ENOMEM;
+
+	/* Setup the clone */
+	clone->bi_iter.bi_sector = sector;
+	clone->bi_iter.bi_size = dmz_blk2sect(nr_blocks) << SECTOR_SHIFT;
+	clone->bi_end_io = dmz_read_bio_end_io;
+	clone->bi_private = bioctx;
+
+	bio_advance(bio, clone->bi_iter.bi_size);
+
+	/* Submit the clone */
+	atomic_inc(&bioctx->ref);
+	generic_make_request(clone);
+
+	return 0;
+}
+
+/*
+ * Zero out pages of discarded blocks accessed by a read BIO.
+ */
+static void dmz_handle_read_zero(struct dmz_target *dmz, struct bio *bio,
+				 sector_t chunk_block, unsigned int nr_blocks)
+{
+	unsigned int size = nr_blocks << DMZ_BLOCK_SHIFT;
+
+	/* Clear nr_blocks */
+	swap(bio->bi_iter.bi_size, size);
+	zero_fill_bio(bio);
+	swap(bio->bi_iter.bi_size, size);
+
+	bio_advance(bio, size);
+}
+
+/*
+ * Process a read BIO.
+ */
+static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
+			   struct bio *bio)
+{
+	sector_t chunk_block = dmz_chunk_block(dmz->dev, dmz_bio_block(bio));
+	unsigned int nr_blocks = dmz_bio_blocks(bio);
+	sector_t end_block = chunk_block + nr_blocks;
+	struct dm_zone *rzone, *bzone;
+	int ret;
+
+	/* Read into unmapped chunks need only zeroing the BIO buffer */
+	if (!zone) {
+		zero_fill_bio(bio);
+		return 0;
+	}
+
+	dmz_dev_debug(dmz->dev, "READ chunk %llu -> %s zone %u, block %llu, %u blocks",
+		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
+		      (dmz_is_rnd(zone) ? "RND" : "SEQ"),
+		      dmz_id(dmz->metadata, zone),
+		      (unsigned long long)chunk_block, nr_blocks);
+
+	/* Check block validity to determine the read location */
+	bzone = zone->bzone;
+	while (chunk_block < end_block) {
+		nr_blocks = 0;
+		if (dmz_is_rnd(zone) || chunk_block < zone->wp_block) {
+			/* Test block validity in the data zone */
+			ret = dmz_block_valid(dmz->metadata, zone, chunk_block);
+			if (ret < 0)
+				return ret;
+			if (ret > 0) {
+				/* Read data zone blocks */
+				nr_blocks = ret;
+				rzone = zone;
+			}
+		}
+
+		/*
+		 * No valid blocks found in the data zone.
+		 * Check the buffer zone, if there is one.
+		 */
+		if (!nr_blocks && bzone) {
+			ret = dmz_block_valid(dmz->metadata, bzone, chunk_block);
+			if (ret < 0)
+				return ret;
+			if (ret > 0) {
+				/* Read buffer zone blocks */
+				nr_blocks = ret;
+				rzone = bzone;
+			}
+		}
+
+		if (nr_blocks) {
+			/* Valid blocks found: read them */
+			nr_blocks = min_t(unsigned int, nr_blocks, end_block - chunk_block);
+			ret = dmz_submit_read_bio(dmz, rzone, bio, chunk_block, nr_blocks);
+			if (ret)
+				return ret;
+			chunk_block += nr_blocks;
+		} else {
+			/* No valid block: zeroout the current BIO block */
+			dmz_handle_read_zero(dmz, bio, chunk_block, 1);
+			chunk_block++;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Issue a write BIO to a zone.
+ */
+static void dmz_submit_write_bio(struct dmz_target *dmz, struct dm_zone *zone,
+				 struct bio *bio, sector_t chunk_block,
+				 unsigned int nr_blocks)
+{
+	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+
+	/* Setup and submit the BIO */
+	bio->bi_bdev = dmz->dev->bdev;
+	bio->bi_iter.bi_sector = dmz_start_sect(dmz->metadata, zone) + dmz_blk2sect(chunk_block);
+	atomic_inc(&bioctx->ref);
+	generic_make_request(bio);
+
+	if (dmz_is_seq(zone))
+		zone->wp_block += nr_blocks;
+}
+
+/*
+ * Write blocks directly in a data zone, at the write pointer.
+ * If a buffer zone is assigned, invalidate the blocks written
+ * in place.
+ */
+static int dmz_handle_direct_write(struct dmz_target *dmz,
+				   struct dm_zone *zone, struct bio *bio,
+				   sector_t chunk_block,
+				   unsigned int nr_blocks)
+{
+	struct dmz_metadata *zmd = dmz->metadata;
+	struct dm_zone *bzone = zone->bzone;
+	int ret;
+
+	if (dmz_is_readonly(zone))
+		return -EROFS;
+
+	/* Submit write */
+	dmz_submit_write_bio(dmz, zone, bio, chunk_block, nr_blocks);
+
+	/*
+	 * Validate the blocks in the data zone and invalidate
+	 * in the buffer zone, if there is one.
+	 */
+	ret = dmz_validate_blocks(zmd, zone, chunk_block, nr_blocks);
+	if (ret == 0 && bzone)
+		ret = dmz_invalidate_blocks(zmd, bzone, chunk_block, nr_blocks);
+
+	return ret;
+}
+
+/*
+ * Write blocks in the buffer zone of @zone.
+ * If no buffer zone is assigned yet, get one.
+ * Called with @zone write locked.
+ */
+static int dmz_handle_buffered_write(struct dmz_target *dmz,
+				     struct dm_zone *zone, struct bio *bio,
+				     sector_t chunk_block,
+				     unsigned int nr_blocks)
+{
+	struct dmz_metadata *zmd = dmz->metadata;
+	struct dm_zone *bzone;
+	int ret;
+
+	/* Get the buffer zone. One will be allocated if needed */
+	bzone = dmz_get_chunk_buffer(zmd, zone);
+	if (!bzone)
+		return -ENOSPC;
+
+	if (dmz_is_readonly(bzone))
+		return -EROFS;
+
+	/* Submit write */
+	dmz_submit_write_bio(dmz, bzone, bio, chunk_block, nr_blocks);
+
+	/*
+	 * Validate the blocks in the buffer zone
+	 * and invalidate in the data zone.
+	 */
+	ret = dmz_validate_blocks(zmd, bzone, chunk_block, nr_blocks);
+	if (ret == 0 && chunk_block < zone->wp_block)
+		ret = dmz_invalidate_blocks(zmd, zone, chunk_block, nr_blocks);
+
+	return ret;
+}
+
+/*
+ * Process a write BIO.
+ */
+static int dmz_handle_write(struct dmz_target *dmz, struct dm_zone *zone,
+			    struct bio *bio)
+{
+	sector_t chunk_block = dmz_chunk_block(dmz->dev, dmz_bio_block(bio));
+	unsigned int nr_blocks = dmz_bio_blocks(bio);
+
+	if (!zone)
+		return -ENOSPC;
+
+	dmz_dev_debug(dmz->dev, "WRITE chunk %llu -> %s zone %u, block %llu, %u blocks",
+		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
+		      (dmz_is_rnd(zone) ? "RND" : "SEQ"),
+		      dmz_id(dmz->metadata, zone),
+		      (unsigned long long)chunk_block, nr_blocks);
+
+	if (dmz_is_rnd(zone) || chunk_block == zone->wp_block) {
+		/*
+		 * zone is a random zone or it is a sequential zone
+		 * and the BIO is aligned to the zone write pointer:
+		 * direct write the zone.
+		 */
+		return dmz_handle_direct_write(dmz, zone, bio, chunk_block, nr_blocks);
+	}
+
+	/*
+	 * This is an unaligned write in a sequential zone:
+	 * use buffered write.
+	 */
+	return dmz_handle_buffered_write(dmz, zone, bio, chunk_block, nr_blocks);
+}
+
+/*
+ * Process a discard BIO.
+ */
+static int dmz_handle_discard(struct dmz_target *dmz, struct dm_zone *zone,
+			      struct bio *bio)
+{
+	struct dmz_metadata *zmd = dmz->metadata;
+	sector_t block = dmz_bio_block(bio);
+	unsigned int nr_blocks = dmz_bio_blocks(bio);
+	sector_t chunk_block = dmz_chunk_block(dmz->dev, block);
+	int ret = 0;
+
+	/* For unmapped chunks, there is nothing to do */
+	if (!zone)
+		return 0;
+
+	if (dmz_is_readonly(zone))
+		return -EROFS;
+
+	dmz_dev_debug(dmz->dev, "DISCARD chunk %llu -> zone %u, block %llu, %u blocks",
+		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
+		      dmz_id(zmd, zone),
+		      (unsigned long long)chunk_block, nr_blocks);
+
+	/*
+	 * Invalidate blocks in the data zone and its
+	 * buffer zone if one is mapped.
+	 */
+	if (dmz_is_rnd(zone) || chunk_block < zone->wp_block)
+		ret = dmz_invalidate_blocks(zmd, zone, chunk_block, nr_blocks);
+	if (ret == 0 && zone->bzone)
+		ret = dmz_invalidate_blocks(zmd, zone->bzone,
+					    chunk_block, nr_blocks);
+	return ret;
+}
+
+/*
+ * Process a BIO.
+ */
+static void dmz_handle_bio(struct dmz_target *dmz, struct dm_chunk_work *cw,
+			   struct bio *bio)
+{
+	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	struct dmz_metadata *zmd = dmz->metadata;
+	struct dm_zone *zone;
+	int ret;
+
+	/*
+	 * Write may trigger a zone allocation. So make sure the
+	 * allocation can succeed.
+	 */
+	if (bio_op(bio) == REQ_OP_WRITE)
+		dmz_schedule_reclaim(dmz->reclaim);
+
+	dmz_lock_metadata(zmd);
+
+	/*
+	 * Get the data zone mapping the chunk. There may be no
+	 * mapping for read and discard. If a mapping is obtained,
+	 + the zone returned will be set to active state.
+	 */
+	zone = dmz_get_chunk_mapping(zmd, dmz_bio_chunk(dmz->dev, bio),
+				     bio_op(bio));
+	if (IS_ERR(zone)) {
+		ret = PTR_ERR(zone);
+		goto out;
+	}
+
+	/* Process the BIO */
+	if (zone) {
+		dmz_activate_zone(zone);
+		bioctx->zone = zone;
+	}
+
+	switch (bio_op(bio)) {
+	case REQ_OP_READ:
+		ret = dmz_handle_read(dmz, zone, bio);
+		break;
+	case REQ_OP_WRITE:
+		ret = dmz_handle_write(dmz, zone, bio);
+		break;
+	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
+		ret = dmz_handle_discard(dmz, zone, bio);
+		break;
+	default:
+		dmz_dev_err(dmz->dev, "Unsupported BIO operation 0x%x",
+			    bio_op(bio));
+		ret = -EIO;
+	}
+
+	/*
+	 * Release the chunk mapping. This will check that the mapping
+	 * is still valid, that is, that the zone used still has valid blocks.
+	 */
+	if (zone)
+		dmz_put_chunk_mapping(zmd, zone);
+out:
+	dmz_bio_endio(bio, errno_to_blk_status(ret));
+
+	dmz_unlock_metadata(zmd);
+}
+
+/*
+ * Increment a chunk reference counter.
+ */
+static inline void dmz_get_chunk_work(struct dm_chunk_work *cw)
+{
+	atomic_inc(&cw->refcount);
+}
+
+/*
+ * Decrement a chunk work reference count and
+ * free it if it becomes 0.
+ */
+static void dmz_put_chunk_work(struct dm_chunk_work *cw)
+{
+	if (atomic_dec_and_test(&cw->refcount)) {
+		WARN_ON(!bio_list_empty(&cw->bio_list));
+		radix_tree_delete(&cw->target->chunk_rxtree, cw->chunk);
+		kfree(cw);
+	}
+}
+
+/*
+ * Chunk BIO work function.
+ */
+static void dmz_chunk_work(struct work_struct *work)
+{
+	struct dm_chunk_work *cw = container_of(work, struct dm_chunk_work, work);
+	struct dmz_target *dmz = cw->target;
+	struct bio *bio;
+
+	mutex_lock(&dmz->chunk_lock);
+
+	/* Process the chunk BIOs */
+	while ((bio = bio_list_pop(&cw->bio_list))) {
+		mutex_unlock(&dmz->chunk_lock);
+		dmz_handle_bio(dmz, cw, bio);
+		mutex_lock(&dmz->chunk_lock);
+		dmz_put_chunk_work(cw);
+	}
+
+	/* Queueing the work incremented the work refcount */
+	dmz_put_chunk_work(cw);
+
+	mutex_unlock(&dmz->chunk_lock);
+}
+
+/*
+ * Flush work.
+ */
+static void dmz_flush_work(struct work_struct *work)
+{
+	struct dmz_target *dmz = container_of(work, struct dmz_target, flush_work.work);
+	struct bio *bio;
+	int ret;
+
+	/* Flush dirty metadata blocks */
+	ret = dmz_flush_metadata(dmz->metadata);
+
+	/* Process queued flush requests */
+	while (1) {
+		spin_lock(&dmz->flush_lock);
+		bio = bio_list_pop(&dmz->flush_list);
+		spin_unlock(&dmz->flush_lock);
+
+		if (!bio)
+			break;
+
+		dmz_bio_endio(bio, errno_to_blk_status(ret));
+	}
+
+	queue_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
+}
+
+/*
+ * Get a chunk work and start it to process a new BIO.
+ * If the BIO chunk has no work yet, create one.
+ */
+static void dmz_queue_chunk_work(struct dmz_target *dmz, struct bio *bio)
+{
+	unsigned int chunk = dmz_bio_chunk(dmz->dev, bio);
+	struct dm_chunk_work *cw;
+
+	mutex_lock(&dmz->chunk_lock);
+
+	/* Get the BIO chunk work. If one is not active yet, create one */
+	cw = radix_tree_lookup(&dmz->chunk_rxtree, chunk);
+	if (!cw) {
+		int ret;
+
+		/* Create a new chunk work */
+		cw = kmalloc(sizeof(struct dm_chunk_work), GFP_NOFS);
+		if (!cw)
+			goto out;
+
+		INIT_WORK(&cw->work, dmz_chunk_work);
+		atomic_set(&cw->refcount, 0);
+		cw->target = dmz;
+		cw->chunk = chunk;
+		bio_list_init(&cw->bio_list);
+
+		ret = radix_tree_insert(&dmz->chunk_rxtree, chunk, cw);
+		if (unlikely(ret)) {
+			kfree(cw);
+			cw = NULL;
+			goto out;
+		}
+	}
+
+	bio_list_add(&cw->bio_list, bio);
+	dmz_get_chunk_work(cw);
+
+	if (queue_work(dmz->chunk_wq, &cw->work))
+		dmz_get_chunk_work(cw);
+out:
+	mutex_unlock(&dmz->chunk_lock);
+}
+
+/*
+ * Process a new BIO.
+ */
+static int dmz_map(struct dm_target *ti, struct bio *bio)
+{
+	struct dmz_target *dmz = ti->private;
+	struct dmz_dev *dev = dmz->dev;
+	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+	sector_t sector = bio->bi_iter.bi_sector;
+	unsigned int nr_sectors = bio_sectors(bio);
+	sector_t chunk_sector;
+
+	dmz_dev_debug(dev, "BIO op %d sector %llu + %u => chunk %llu, block %llu, %u blocks",
+		      bio_op(bio), (unsigned long long)sector, nr_sectors,
+		      (unsigned long long)dmz_bio_chunk(dmz->dev, bio),
+		      (unsigned long long)dmz_chunk_block(dmz->dev, dmz_bio_block(bio)),
+		      (unsigned int)dmz_bio_blocks(bio));
+
+	bio->bi_bdev = dev->bdev;
+
+	if (!nr_sectors && (bio_op(bio) != REQ_OP_FLUSH) && (bio_op(bio) != REQ_OP_WRITE))
+		return DM_MAPIO_REMAPPED;
+
+	/* The BIO should be block aligned */
+	if ((nr_sectors & DMZ_BLOCK_SECTORS_MASK) || (sector & DMZ_BLOCK_SECTORS_MASK))
+		return DM_MAPIO_KILL;
+
+	/* Initialize the BIO context */
+	bioctx->target = dmz;
+	bioctx->zone = NULL;
+	bioctx->bio = bio;
+	atomic_set(&bioctx->ref, 1);
+	bioctx->status = BLK_STS_OK;
+
+	/* Set the BIO pending in the flush list */
+	if (bio_op(bio) == REQ_OP_FLUSH || (!nr_sectors && bio_op(bio) == REQ_OP_WRITE)) {
+		spin_lock(&dmz->flush_lock);
+		bio_list_add(&dmz->flush_list, bio);
+		spin_unlock(&dmz->flush_lock);
+		mod_delayed_work(dmz->flush_wq, &dmz->flush_work, 0);
+		return DM_MAPIO_SUBMITTED;
+	}
+
+	/* Split zone BIOs to fit entirely into a zone */
+	chunk_sector = sector & (dev->zone_nr_sectors - 1);
+	if (chunk_sector + nr_sectors > dev->zone_nr_sectors)
+		dm_accept_partial_bio(bio, dev->zone_nr_sectors - chunk_sector);
+
+	/* Now ready to handle this BIO */
+	dmz_reclaim_bio_acc(dmz->reclaim);
+	dmz_queue_chunk_work(dmz, bio);
+
+	return DM_MAPIO_SUBMITTED;
+}
+
+/*
+ * Completed target BIO processing.
+ */
+static int dmz_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
+{
+	struct dmz_bioctx *bioctx = dm_per_bio_data(bio, sizeof(struct dmz_bioctx));
+
+	if (bioctx->status == BLK_STS_OK && *error)
+		bioctx->status = *error;
+
+	if (!atomic_dec_and_test(&bioctx->ref))
+		return DM_ENDIO_INCOMPLETE;
+
+	/* Done */
+	bio->bi_status = bioctx->status;
+
+	if (bioctx->zone) {
+		struct dm_zone *zone = bioctx->zone;
+
+		if (*error && bio_op(bio) == REQ_OP_WRITE) {
+			if (dmz_is_seq(zone))
+				set_bit(DMZ_SEQ_WRITE_ERR, &zone->flags);
+		}
+		dmz_deactivate_zone(zone);
+	}
+
+	return DM_ENDIO_DONE;
+}
+
+/*
+ * Get zoned device information.
+ */
+static int dmz_get_zoned_device(struct dm_target *ti, char *path)
+{
+	struct dmz_target *dmz = ti->private;
+	struct request_queue *q;
+	struct dmz_dev *dev;
+	int ret;
+
+	/* Get the target device */
+	ret = dm_get_device(ti, path, dm_table_get_mode(ti->table), &dmz->ddev);
+	if (ret) {
+		ti->error = "Get target device failed";
+		dmz->ddev = NULL;
+		return ret;
+	}
+
+	dev = kzalloc(sizeof(struct dmz_dev), GFP_KERNEL);
+	if (!dev) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	dev->bdev = dmz->ddev->bdev;
+	(void)bdevname(dev->bdev, dev->name);
+
+	if (bdev_zoned_model(dev->bdev) == BLK_ZONED_NONE) {
+		ti->error = "Not a zoned block device";
+		ret = -EINVAL;
+		goto err;
+	}
+
+	dev->capacity = i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
+	if (ti->begin || (ti->len != dev->capacity)) {
+		ti->error = "Partial mapping not supported";
+		ret = -EINVAL;
+		goto err;
+	}
+
+	q = bdev_get_queue(dev->bdev);
+	dev->zone_nr_sectors = q->limits.chunk_sectors;
+	dev->zone_nr_sectors_shift = ilog2(dev->zone_nr_sectors);
+
+	dev->zone_nr_blocks = dmz_sect2blk(dev->zone_nr_sectors);
+	dev->zone_nr_blocks_shift = ilog2(dev->zone_nr_blocks);
+
+	dev->nr_zones = (dev->capacity + dev->zone_nr_sectors - 1)
+		>> dev->zone_nr_sectors_shift;
+
+	dmz->dev = dev;
+
+	return 0;
+err:
+	dm_put_device(ti, dmz->ddev);
+	kfree(dev);
+
+	return ret;
+}
+
+/*
+ * Cleanup zoned device information.
+ */
+static void dmz_put_zoned_device(struct dm_target *ti)
+{
+	struct dmz_target *dmz = ti->private;
+
+	dm_put_device(ti, dmz->ddev);
+	kfree(dmz->dev);
+	dmz->dev = NULL;
+}
+
+/*
+ * Setup target.
+ */
+static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	struct dmz_target *dmz;
+	struct dmz_dev *dev;
+	int ret;
+
+	/* Check arguments */
+	if (argc != 1) {
+		ti->error = "Invalid argument count";
+		return -EINVAL;
+	}
+
+	/* Allocate and initialize the target descriptor */
+	dmz = kzalloc(sizeof(struct dmz_target), GFP_KERNEL);
+	if (!dmz) {
+		ti->error = "Unable to allocate the zoned target descriptor";
+		return -ENOMEM;
+	}
+	ti->private = dmz;
+
+	/* Get the target zoned block device */
+	ret = dmz_get_zoned_device(ti, argv[0]);
+	if (ret) {
+		dmz->ddev = NULL;
+		goto err;
+	}
+
+	/* Initialize metadata */
+	dev = dmz->dev;
+	ret = dmz_ctr_metadata(dev, &dmz->metadata);
+	if (ret) {
+		ti->error = "Metadata initialization failed";
+		goto err_dev;
+	}
+
+	/* Set target (no write same support) */
+	ti->max_io_len = dev->zone_nr_sectors << 9;
+	ti->num_flush_bios = 1;
+	ti->num_discard_bios = 1;
+	ti->num_write_zeroes_bios = 1;
+	ti->per_io_data_size = sizeof(struct dmz_bioctx);
+	ti->flush_supported = true;
+	ti->discards_supported = true;
+	ti->split_discard_bios = true;
+
+	/* The exposed capacity is the number of chunks that can be mapped */
+	ti->len = (sector_t)dmz_nr_chunks(dmz->metadata) << dev->zone_nr_sectors_shift;
+
+	/* Zone BIO */
+	dmz->bio_set = bioset_create(DMZ_MIN_BIOS, 0, 0);
+	if (!dmz->bio_set) {
+		ti->error = "Create BIO set failed";
+		ret = -ENOMEM;
+		goto err_meta;
+	}
+
+	/* Chunk BIO work */
+	mutex_init(&dmz->chunk_lock);
+	INIT_RADIX_TREE(&dmz->chunk_rxtree, GFP_NOFS);
+	dmz->chunk_wq = alloc_workqueue("dmz_cwq_%s", WQ_MEM_RECLAIM | WQ_UNBOUND,
+					0, dev->name);
+	if (!dmz->chunk_wq) {
+		ti->error = "Create chunk workqueue failed";
+		ret = -ENOMEM;
+		goto err_bio;
+	}
+
+	/* Flush work */
+	spin_lock_init(&dmz->flush_lock);
+	bio_list_init(&dmz->flush_list);
+	INIT_DELAYED_WORK(&dmz->flush_work, dmz_flush_work);
+	dmz->flush_wq = alloc_ordered_workqueue("dmz_fwq_%s", WQ_MEM_RECLAIM,
+						dev->name);
+	if (!dmz->flush_wq) {
+		ti->error = "Create flush workqueue failed";
+		ret = -ENOMEM;
+		goto err_cwq;
+	}
+	mod_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
+
+	/* Initialize reclaim */
+	ret = dmz_ctr_reclaim(dev, dmz->metadata, &dmz->reclaim);
+	if (ret) {
+		ti->error = "Zone reclaim initialization failed";
+		goto err_fwq;
+	}
+
+	dmz_dev_info(dev, "Target device: %llu 512-byte logical sectors (%llu blocks)",
+		     (unsigned long long)ti->len,
+		     (unsigned long long)dmz_sect2blk(ti->len));
+
+	return 0;
+err_fwq:
+	destroy_workqueue(dmz->flush_wq);
+err_cwq:
+	destroy_workqueue(dmz->chunk_wq);
+err_bio:
+	bioset_free(dmz->bio_set);
+err_meta:
+	dmz_dtr_metadata(dmz->metadata);
+err_dev:
+	dmz_put_zoned_device(ti);
+err:
+	kfree(dmz);
+
+	return ret;
+}
+
+/*
+ * Cleanup target.
+ */
+static void dmz_dtr(struct dm_target *ti)
+{
+	struct dmz_target *dmz = ti->private;
+
+	flush_workqueue(dmz->chunk_wq);
+	destroy_workqueue(dmz->chunk_wq);
+
+	dmz_dtr_reclaim(dmz->reclaim);
+
+	cancel_delayed_work_sync(&dmz->flush_work);
+	destroy_workqueue(dmz->flush_wq);
+
+	(void) dmz_flush_metadata(dmz->metadata);
+
+	dmz_dtr_metadata(dmz->metadata);
+
+	bioset_free(dmz->bio_set);
+
+	dmz_put_zoned_device(ti);
+
+	kfree(dmz);
+}
+
+/*
+ * Setup target request queue limits.
+ */
+static void dmz_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+	struct dmz_target *dmz = ti->private;
+	unsigned int chunk_sectors = dmz->dev->zone_nr_sectors;
+
+	limits->logical_block_size = DMZ_BLOCK_SIZE;
+	limits->physical_block_size = DMZ_BLOCK_SIZE;
+
+	blk_limits_io_min(limits, DMZ_BLOCK_SIZE);
+	blk_limits_io_opt(limits, DMZ_BLOCK_SIZE);
+
+	limits->discard_alignment = DMZ_BLOCK_SIZE;
+	limits->discard_granularity = DMZ_BLOCK_SIZE;
+	limits->max_discard_sectors = chunk_sectors;
+	limits->max_hw_discard_sectors = chunk_sectors;
+	limits->max_write_zeroes_sectors = chunk_sectors;
+
+	/* FS hint to try to align to the device zone size */
+	limits->chunk_sectors = chunk_sectors;
+	limits->max_sectors = chunk_sectors;
+
+	/* We are exposing a drive-managed zoned block device */
+	limits->zoned = BLK_ZONED_NONE;
+}
+
+/*
+ * Pass on ioctl to the backend device.
+ */
+static int dmz_prepare_ioctl(struct dm_target *ti,
+			     struct block_device **bdev, fmode_t *mode)
+{
+	struct dmz_target *dmz = ti->private;
+
+	*bdev = dmz->dev->bdev;
+
+	return 0;
+}
+
+/*
+ * Stop works on suspend.
+ */
+static void dmz_suspend(struct dm_target *ti)
+{
+	struct dmz_target *dmz = ti->private;
+
+	flush_workqueue(dmz->chunk_wq);
+	dmz_suspend_reclaim(dmz->reclaim);
+	cancel_delayed_work_sync(&dmz->flush_work);
+}
+
+/*
+ * Restart works on resume or if suspend failed.
+ */
+static void dmz_resume(struct dm_target *ti)
+{
+	struct dmz_target *dmz = ti->private;
+
+	queue_delayed_work(dmz->flush_wq, &dmz->flush_work, DMZ_FLUSH_PERIOD);
+	dmz_resume_reclaim(dmz->reclaim);
+}
+
+static int dmz_iterate_devices(struct dm_target *ti,
+			       iterate_devices_callout_fn fn, void *data)
+{
+	struct dmz_target *dmz = ti->private;
+
+	return fn(ti, dmz->ddev, 0, dmz->dev->capacity, data);
+}
+
+static struct target_type dmz_type = {
+	.name		 = "zoned",
+	.version	 = {1, 0, 0},
+	.features	 = DM_TARGET_SINGLETON | DM_TARGET_ZONED_HM,
+	.module		 = THIS_MODULE,
+	.ctr		 = dmz_ctr,
+	.dtr		 = dmz_dtr,
+	.map		 = dmz_map,
+	.end_io		 = dmz_end_io,
+	.io_hints	 = dmz_io_hints,
+	.prepare_ioctl	 = dmz_prepare_ioctl,
+	.postsuspend	 = dmz_suspend,
+	.resume		 = dmz_resume,
+	.iterate_devices = dmz_iterate_devices,
+};
+
+static int __init dmz_init(void)
+{
+	return dm_register_target(&dmz_type);
+}
+
+static void __exit dmz_exit(void)
+{
+	dm_unregister_target(&dmz_type);
+}
+
+module_init(dmz_init);
+module_exit(dmz_exit);
+
+MODULE_DESCRIPTION(DM_NAME " target for zoned block devices");
+MODULE_AUTHOR("Damien Le Moal <damien.lemoal@wdc.com>");
+MODULE_LICENSE("GPL");