Merge tag 'for-5.10/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Improve DM core's bio splitting to use blk_max_size_offset(). Also
   fix bio splitting for bios that were deferred to the worker thread
   due to a DM device being suspended.

 - Remove DM core's special handling of NVMe devices now that block core
   has internalized efficiencies drivers previously needed to be
   concerned about (via now removed direct_make_request).

 - Fix request-based DM to not bounce through indirect dm_submit_bio;
   instead have block core make direct call to blk_mq_submit_bio().

 - Various DM core cleanups to simplify and improve code.

 - Update DM cryot to not use drivers that set
   CRYPTO_ALG_ALLOCATES_MEMORY.

 - Fix DM raid's raid1 and raid10 discard limits for the purposes of
   linux-stable. But then remove DM raid's discard limits settings now
   that MD raid can efficiently handle large discards.

 - A couple small cleanups across various targets.

* tag 'for-5.10/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: fix request-based DM to not bounce through indirect dm_submit_bio
  dm: remove special-casing of bio-based immutable singleton target on NVMe
  dm: export dm_copy_name_and_uuid
  dm: fix comment in __dm_suspend()
  dm: fold dm_process_bio() into dm_submit_bio()
  dm: fix missing imposition of queue_limits from dm_wq_work() thread
  dm snap persistent: simplify area_io()
  dm thin metadata: Remove unused local variable when create thin and snap
  dm raid: remove unnecessary discard limits for raid10
  dm raid: fix discard limits for raid1 and raid10
  dm crypt: don't use drivers that have CRYPTO_ALG_ALLOCATES_MEMORY
  dm: use dm_table_get_device_name() where appropriate in targets
  dm table: make 'struct dm_table' definition accessible to all of DM core
  dm: eliminate need for start_io_acct() forward declaration
  dm: simplify __process_abnormal_io()
  dm: push use of on-stack flush_bio down to __send_empty_flush()
  dm: optimize max_io_len() by inlining max_io_len_target_boundary()
  dm: push md->immutable_target optimization down to __process_bio()
  dm: change max_io_len() to use blk_max_size_offset()
  dm table: stack 'chunk_sectors' limit to account for target-specific splitting

13 files changed, 222 insertions, 393 deletions

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 96c93802ee4d..9644424591da 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -925,7 +925,7 @@ static enum cache_metadata_mode get_cache_mode(struct cache *cache)
 
 static const char *cache_device_name(struct cache *cache)
 {
-	return dm_device_name(dm_table_get_md(cache->ti->table));
+	return dm_table_device_name(cache->ti->table);
 }
 
 static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index c4ef1fceead6..d522093cb39d 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -11,6 +11,7 @@
 
 #include <linux/kthread.h>
 #include <linux/ktime.h>
+#include <linux/genhd.h>
 #include <linux/blk-mq.h>
 
 #include <trace/events/block.h>
@@ -25,9 +26,11 @@ struct dm_kobject_holder {
 };
 
 /*
- * DM core internal structure that used directly by dm.c and dm-rq.c
- * DM targets must _not_ deference a mapped_device to directly access its members!
+ * DM core internal structures used directly by dm.c, dm-rq.c and dm-table.c.
+ * DM targets must _not_ deference a mapped_device or dm_table to directly
+ * access their members!
  */
+
 struct mapped_device {
 	struct mutex suspend_lock;
 
@@ -119,6 +122,55 @@ void disable_discard(struct mapped_device *md);
 void disable_write_same(struct mapped_device *md);
 void disable_write_zeroes(struct mapped_device *md);
 
+static inline sector_t dm_get_size(struct mapped_device *md)
+{
+	return get_capacity(md->disk);
+}
+
+static inline struct dm_stats *dm_get_stats(struct mapped_device *md)
+{
+	return &md->stats;
+}
+
+#define DM_TABLE_MAX_DEPTH 16
+
+struct dm_table {
+	struct mapped_device *md;
+	enum dm_queue_mode type;
+
+	/* btree table */
+	unsigned int depth;
+	unsigned int counts[DM_TABLE_MAX_DEPTH]; /* in nodes */
+	sector_t *index[DM_TABLE_MAX_DEPTH];
+
+	unsigned int num_targets;
+	unsigned int num_allocated;
+	sector_t *highs;
+	struct dm_target *targets;
+
+	struct target_type *immutable_target_type;
+
+	bool integrity_supported:1;
+	bool singleton:1;
+	unsigned integrity_added:1;
+
+	/*
+	 * Indicates the rw permissions for the new logical
+	 * device.  This should be a combination of FMODE_READ
+	 * and FMODE_WRITE.
+	 */
+	fmode_t mode;
+
+	/* a list of devices used by this table */
+	struct list_head devices;
+
+	/* events get handed up using this callback */
+	void (*event_fn)(void *);
+	void *event_context;
+
+	struct dm_md_mempools *mempools;
+};
+
 static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
 {
 	return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 380386c36921..392337f16ecf 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -424,7 +424,8 @@ static int crypt_iv_lmk_ctr(struct crypt_config *cc, struct dm_target *ti,
 		return -EINVAL;
 	}
 
-	lmk->hash_tfm = crypto_alloc_shash("md5", 0, 0);
+	lmk->hash_tfm = crypto_alloc_shash("md5", 0,
+					   CRYPTO_ALG_ALLOCATES_MEMORY);
 	if (IS_ERR(lmk->hash_tfm)) {
 		ti->error = "Error initializing LMK hash";
 		return PTR_ERR(lmk->hash_tfm);
@@ -586,7 +587,8 @@ static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
 		return -EINVAL;
 	}
 
-	tcw->crc32_tfm = crypto_alloc_shash("crc32", 0, 0);
+	tcw->crc32_tfm = crypto_alloc_shash("crc32", 0,
+					    CRYPTO_ALG_ALLOCATES_MEMORY);
 	if (IS_ERR(tcw->crc32_tfm)) {
 		ti->error = "Error initializing CRC32 in TCW";
 		return PTR_ERR(tcw->crc32_tfm);
@@ -773,7 +775,8 @@ static int crypt_iv_elephant_ctr(struct crypt_config *cc, struct dm_target *ti,
 	struct iv_elephant_private *elephant = &cc->iv_gen_private.elephant;
 	int r;
 
-	elephant->tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
+	elephant->tfm = crypto_alloc_skcipher("ecb(aes)", 0,
+					      CRYPTO_ALG_ALLOCATES_MEMORY);
 	if (IS_ERR(elephant->tfm)) {
 		r = PTR_ERR(elephant->tfm);
 		elephant->tfm = NULL;
@@ -2154,7 +2157,8 @@ static int crypt_alloc_tfms_skcipher(struct crypt_config *cc, char *ciphermode)
 		return -ENOMEM;
 
 	for (i = 0; i < cc->tfms_count; i++) {
-		cc->cipher_tfm.tfms[i] = crypto_alloc_skcipher(ciphermode, 0, 0);
+		cc->cipher_tfm.tfms[i] = crypto_alloc_skcipher(ciphermode, 0,
+						CRYPTO_ALG_ALLOCATES_MEMORY);
 		if (IS_ERR(cc->cipher_tfm.tfms[i])) {
 			err = PTR_ERR(cc->cipher_tfm.tfms[i]);
 			crypt_free_tfms(cc);
@@ -2180,7 +2184,8 @@ static int crypt_alloc_tfms_aead(struct crypt_config *cc, char *ciphermode)
 	if (!cc->cipher_tfm.tfms)
 		return -ENOMEM;
 
-	cc->cipher_tfm.tfms_aead[0] = crypto_alloc_aead(ciphermode, 0, 0);
+	cc->cipher_tfm.tfms_aead[0] = crypto_alloc_aead(ciphermode, 0,
+						CRYPTO_ALG_ALLOCATES_MEMORY);
 	if (IS_ERR(cc->cipher_tfm.tfms_aead[0])) {
 		err = PTR_ERR(cc->cipher_tfm.tfms_aead[0]);
 		crypt_free_tfms(cc);
@@ -2667,7 +2672,7 @@ static int crypt_ctr_auth_cipher(struct crypt_config *cc, char *cipher_api)
 		return -ENOMEM;
 	strncpy(mac_alg, start, end - start);
 
-	mac = crypto_alloc_ahash(mac_alg, 0, 0);
+	mac = crypto_alloc_ahash(mac_alg, 0, CRYPTO_ALG_ALLOCATES_MEMORY);
 	kfree(mac_alg);
 
 	if (IS_ERR(mac))
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 28122e850ea1..cd0478d44058 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -2044,7 +2044,7 @@ out:
 
 	return r;
 }
-
+EXPORT_SYMBOL_GPL(dm_copy_name_and_uuid);
 
 /**
  * dm_early_create - create a mapped device in early boot.
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index de4da825ade6..bced42f082b0 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -466,10 +466,8 @@ failed:
  */
 #define dm_report_EIO(m)						\
 do {									\
-	struct mapped_device *md = dm_table_get_md((m)->ti->table);	\
-									\
 	DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
-		      dm_device_name(md),				\
+		      dm_table_device_name((m)->ti->table),		\
 		      test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags),	\
 		      test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
 		      dm_noflush_suspending((m)->ti));			\
@@ -736,7 +734,7 @@ static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
 {
 	unsigned long flags;
 	bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
-	const char *dm_dev_name = dm_device_name(dm_table_get_md(m->ti->table));
+	const char *dm_dev_name = dm_table_device_name(m->ti->table);
 
 	DMDEBUG("%s: %s caller=%s queue_if_no_path=%d save_old_value=%d",
 		dm_dev_name, __func__, caller, queue_if_no_path, save_old_value);
@@ -781,9 +779,9 @@ static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
 static void queue_if_no_path_timeout_work(struct timer_list *t)
 {
 	struct multipath *m = from_timer(m, t, nopath_timer);
-	struct mapped_device *md = dm_table_get_md(m->ti->table);
 
-	DMWARN("queue_if_no_path timeout on %s, failing queued IO", dm_device_name(md));
+	DMWARN("queue_if_no_path timeout on %s, failing queued IO",
+	       dm_table_device_name(m->ti->table));
 	queue_if_no_path(m, false, false, __func__);
 }
 
@@ -1334,7 +1332,7 @@ static int fail_path(struct pgpath *pgpath)
 		goto out;
 
 	DMWARN("%s: Failing path %s.",
-	       dm_device_name(dm_table_get_md(m->ti->table)),
+	       dm_table_device_name(m->ti->table),
 	       pgpath->path.dev->name);
 
 	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
@@ -1375,7 +1373,7 @@ static int reinstate_path(struct pgpath *pgpath)
 		goto out;
 
 	DMWARN("%s: Reinstating path %s.",
-	       dm_device_name(dm_table_get_md(m->ti->table)),
+	       dm_table_device_name(m->ti->table),
 	       pgpath->path.dev->name);
 
 	r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
@@ -1766,7 +1764,7 @@ static void multipath_resume(struct dm_target *ti)
 	}
 
 	DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
-		dm_device_name(dm_table_get_md(m->ti->table)), __func__,
+		dm_table_device_name(m->ti->table), __func__,
 		test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
 		test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
 
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 56b723d012ac..9c1f7c4de65b 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3728,15 +3728,6 @@ static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 	blk_limits_io_min(limits, chunk_size_bytes);
 	blk_limits_io_opt(limits, chunk_size_bytes * mddev_data_stripes(rs));
-
-	/*
-	 * RAID1 and RAID10 personalities require bio splitting,
-	 * RAID0/4/5/6 don't and process large discard bios properly.
-	 */
-	if (rs_is_raid1(rs) || rs_is_raid10(rs)) {
-		limits->discard_granularity = chunk_size_bytes;
-		limits->max_discard_sectors = rs->md.chunk_sectors;
-	}
 }
 
 static void raid_postsuspend(struct dm_target *ti)
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 6d743ff6a314..729a72ec30cc 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -175,7 +175,7 @@ static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long mse
 
 void dm_mq_kick_requeue_list(struct mapped_device *md)
 {
-	__dm_mq_kick_requeue_list(dm_get_md_queue(md), 0);
+	__dm_mq_kick_requeue_list(md->queue, 0);
 }
 EXPORT_SYMBOL(dm_mq_kick_requeue_list);
 
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 63fab7c769be..8e329c3f3a78 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -284,16 +284,9 @@ static void skip_metadata(struct pstore *ps)
  */
 static int area_io(struct pstore *ps, int op, int op_flags)
 {
-	int r;
-	chunk_t chunk;
-
-	chunk = area_location(ps, ps->current_area);
-
-	r = chunk_io(ps, ps->area, chunk, op, op_flags, 0);
-	if (r)
-		return r;
+	chunk_t chunk = area_location(ps, ps->current_area);
 
-	return 0;
+	return chunk_io(ps, ps->area, chunk, op, op_flags, 0);
 }
 
 static void zero_memory_area(struct pstore *ps)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index c3be7cb2570c..ce543b761be7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -18,54 +18,17 @@
 #include <linux/mutex.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
+#include <linux/lcm.h>
 #include <linux/blk-mq.h>
 #include <linux/mount.h>
 #include <linux/dax.h>
 
 #define DM_MSG_PREFIX "table"
 
-#define MAX_DEPTH 16
 #define NODE_SIZE L1_CACHE_BYTES
 #define KEYS_PER_NODE (NODE_SIZE / sizeof(sector_t))
 #define CHILDREN_PER_NODE (KEYS_PER_NODE + 1)
 
-struct dm_table {
-	struct mapped_device *md;
-	enum dm_queue_mode type;
-
-	/* btree table */
-	unsigned int depth;
-	unsigned int counts[MAX_DEPTH];	/* in nodes */
-	sector_t *index[MAX_DEPTH];
-
-	unsigned int num_targets;
-	unsigned int num_allocated;
-	sector_t *highs;
-	struct dm_target *targets;
-
-	struct target_type *immutable_target_type;
-
-	bool integrity_supported:1;
-	bool singleton:1;
-	unsigned integrity_added:1;
-
-	/*
-	 * Indicates the rw permissions for the new logical
-	 * device.  This should be a combination of FMODE_READ
-	 * and FMODE_WRITE.
-	 */
-	fmode_t mode;
-
-	/* a list of devices used by this table */
-	struct list_head devices;
-
-	/* events get handed up using this callback */
-	void (*event_fn)(void *);
-	void *event_context;
-
-	struct dm_md_mempools *mempools;
-};
-
 /*
  * Similar to ceiling(log_size(n))
  */
@@ -841,8 +804,7 @@ EXPORT_SYMBOL(dm_consume_args);
 static bool __table_type_bio_based(enum dm_queue_mode table_type)
 {
 	return (table_type == DM_TYPE_BIO_BASED ||
-		table_type == DM_TYPE_DAX_BIO_BASED ||
-		table_type == DM_TYPE_NVME_BIO_BASED);
+		table_type == DM_TYPE_DAX_BIO_BASED);
 }
 
 static bool __table_type_request_based(enum dm_queue_mode table_type)
@@ -898,8 +860,6 @@ bool dm_table_supports_dax(struct dm_table *t,
 	return true;
 }
 
-static bool dm_table_does_not_support_partial_completion(struct dm_table *t);
-
 static int device_is_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
 				  sector_t start, sector_t len, void *data)
 {
@@ -929,7 +889,6 @@ static int dm_table_determine_type(struct dm_table *t)
 			goto verify_bio_based;
 		}
 		BUG_ON(t->type == DM_TYPE_DAX_BIO_BASED);
-		BUG_ON(t->type == DM_TYPE_NVME_BIO_BASED);
 		goto verify_rq_based;
 	}
 
@@ -968,15 +927,6 @@ verify_bio_based:
 		if (dm_table_supports_dax(t, device_supports_dax, &page_size) ||
 		    (list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED)) {
 			t->type = DM_TYPE_DAX_BIO_BASED;
-		} else {
-			/* Check if upgrading to NVMe bio-based is valid or required */
-			tgt = dm_table_get_immutable_target(t);
-			if (tgt && !tgt->max_io_len && dm_table_does_not_support_partial_completion(t)) {
-				t->type = DM_TYPE_NVME_BIO_BASED;
-				goto verify_rq_based; /* must be stacked directly on NVMe (blk-mq) */
-			} else if (list_empty(devices) && live_md_type == DM_TYPE_NVME_BIO_BASED) {
-				t->type = DM_TYPE_NVME_BIO_BASED;
-			}
 		}
 		return 0;
 	}
@@ -993,8 +943,7 @@ verify_rq_based:
 	 * (e.g. request completion process for partial completion.)
 	 */
 	if (t->num_targets > 1) {
-		DMERR("%s DM doesn't support multiple targets",
-		      t->type == DM_TYPE_NVME_BIO_BASED ? "nvme bio-based" : "request-based");
+		DMERR("request-based DM doesn't support multiple targets");
 		return -EINVAL;
 	}
 
@@ -1506,6 +1455,10 @@ int dm_calculate_queue_limits(struct dm_table *table,
 			zone_sectors = ti_limits.chunk_sectors;
 		}
 
+		/* Stack chunk_sectors if target-specific splitting is required */
+		if (ti->max_io_len)
+			ti_limits.chunk_sectors = lcm_not_zero(ti->max_io_len,
+							       ti_limits.chunk_sectors);
 		/* Set I/O hints portion of queue limits */
 		if (ti->type->io_hints)
 			ti->type->io_hints(ti, &ti_limits);
@@ -1684,20 +1637,6 @@ static bool dm_table_all_devices_attribute(struct dm_table *t,
 	return true;
 }
 
-static int device_no_partial_completion(struct dm_target *ti, struct dm_dev *dev,
-					sector_t start, sector_t len, void *data)
-{
-	char b[BDEVNAME_SIZE];
-
-	/* For now, NVMe devices are the only devices of this class */
-	return (strncmp(bdevname(dev->bdev, b), "nvme", 4) == 0);
-}
-
-static bool dm_table_does_not_support_partial_completion(struct dm_table *t)
-{
-	return dm_table_all_devices_attribute(t, device_no_partial_completion);
-}
-
 static int device_not_write_same_capable(struct dm_target *ti, struct dm_dev *dev,
 					 sector_t start, sector_t len, void *data)
 {
@@ -2080,16 +2019,11 @@ EXPORT_SYMBOL_GPL(dm_table_device_name);
 
 void dm_table_run_md_queue_async(struct dm_table *t)
 {
-	struct mapped_device *md;
-	struct request_queue *queue;
-
 	if (!dm_table_request_based(t))
 		return;
 
-	md = dm_table_get_md(t);
-	queue = dm_get_md_queue(md);
-	if (queue)
-		blk_mq_run_hw_queues(queue, true);
+	if (t->md->queue)
+		blk_mq_run_hw_queues(t->md->queue, true);
 }
 EXPORT_SYMBOL(dm_table_run_md_queue_async);
 
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index b461836b6d26..6ebb2127f3e2 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1051,12 +1051,11 @@ static int __create_thin(struct dm_pool_metadata *pmd,
 	int r;
 	dm_block_t dev_root;
 	uint64_t key = dev;
-	struct disk_device_details details_le;
 	struct dm_thin_device *td;
 	__le64 value;
 
 	r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
-			    &key, &details_le);
+			    &key, NULL);
 	if (!r)
 		return -EEXIST;
 
@@ -1129,12 +1128,11 @@ static int __create_snap(struct dm_pool_metadata *pmd,
 	dm_block_t origin_root;
 	uint64_t key = origin, dev_key = dev;
 	struct dm_thin_device *td;
-	struct disk_device_details details_le;
 	__le64 value;
 
 	/* check this device is unused */
 	r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
-			    &dev_key, &details_le);
+			    &dev_key, NULL);
 	if (!r)
 		return -EEXIST;
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index cd2b3526c07b..c18fc2548518 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -422,21 +422,6 @@ static void do_deferred_remove(struct work_struct *w)
 	dm_deferred_remove();
 }
 
-sector_t dm_get_size(struct mapped_device *md)
-{
-	return get_capacity(md->disk);
-}
-
-struct request_queue *dm_get_md_queue(struct mapped_device *md)
-{
-	return md->queue;
-}
-
-struct dm_stats *dm_get_stats(struct mapped_device *md)
-{
-	return &md->stats;
-}
-
 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
 	struct mapped_device *md = bdev->bd_disk->private_data;
@@ -591,7 +576,44 @@ out:
 	return r;
 }
 
-static void start_io_acct(struct dm_io *io);
+u64 dm_start_time_ns_from_clone(struct bio *bio)
+{
+	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
+	struct dm_io *io = tio->io;
+
+	return jiffies_to_nsecs(io->start_time);
+}
+EXPORT_SYMBOL_GPL(dm_start_time_ns_from_clone);
+
+static void start_io_acct(struct dm_io *io)
+{
+	struct mapped_device *md = io->md;
+	struct bio *bio = io->orig_bio;
+
+	io->start_time = bio_start_io_acct(bio);
+	if (unlikely(dm_stats_used(&md->stats)))
+		dm_stats_account_io(&md->stats, bio_data_dir(bio),
+				    bio->bi_iter.bi_sector, bio_sectors(bio),
+				    false, 0, &io->stats_aux);
+}
+
+static void end_io_acct(struct dm_io *io)
+{
+	struct mapped_device *md = io->md;
+	struct bio *bio = io->orig_bio;
+	unsigned long duration = jiffies - io->start_time;
+
+	bio_end_io_acct(bio, io->start_time);
+
+	if (unlikely(dm_stats_used(&md->stats)))
+		dm_stats_account_io(&md->stats, bio_data_dir(bio),
+				    bio->bi_iter.bi_sector, bio_sectors(bio),
+				    true, duration, &io->stats_aux);
+
+	/* nudge anyone waiting on suspend queue */
+	if (unlikely(wq_has_sleeper(&md->wait)))
+		wake_up(&md->wait);
+}
 
 static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
 {
@@ -657,45 +679,6 @@ static void free_tio(struct dm_target_io *tio)
 	bio_put(&tio->clone);
 }
 
-u64 dm_start_time_ns_from_clone(struct bio *bio)
-{
-	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
-	struct dm_io *io = tio->io;
-
-	return jiffies_to_nsecs(io->start_time);
-}
-EXPORT_SYMBOL_GPL(dm_start_time_ns_from_clone);
-
-static void start_io_acct(struct dm_io *io)
-{
-	struct mapped_device *md = io->md;
-	struct bio *bio = io->orig_bio;
-
-	io->start_time = bio_start_io_acct(bio);
-	if (unlikely(dm_stats_used(&md->stats)))
-		dm_stats_account_io(&md->stats, bio_data_dir(bio),
-				    bio->bi_iter.bi_sector, bio_sectors(bio),
-				    false, 0, &io->stats_aux);
-}
-
-static void end_io_acct(struct dm_io *io)
-{
-	struct mapped_device *md = io->md;
-	struct bio *bio = io->orig_bio;
-	unsigned long duration = jiffies - io->start_time;
-
-	bio_end_io_acct(bio, io->start_time);
-
-	if (unlikely(dm_stats_used(&md->stats)))
-		dm_stats_account_io(&md->stats, bio_data_dir(bio),
-				    bio->bi_iter.bi_sector, bio_sectors(bio),
-				    true, duration, &io->stats_aux);
-
-	/* nudge anyone waiting on suspend queue */
-	if (unlikely(wq_has_sleeper(&md->wait)))
-		wake_up(&md->wait);
-}
-
 /*
  * Add the bio to the list of deferred io.
  */
@@ -992,7 +975,7 @@ static void clone_endio(struct bio *bio)
 	dm_endio_fn endio = tio->ti->type->end_io;
 	struct bio *orig_bio = io->orig_bio;
 
-	if (unlikely(error == BLK_STS_TARGET) && md->type != DM_TYPE_NVME_BIO_BASED) {
+	if (unlikely(error == BLK_STS_TARGET)) {
 		if (bio_op(bio) == REQ_OP_DISCARD &&
 		    !bio->bi_disk->queue->limits.max_discard_sectors)
 			disable_discard(md);
@@ -1041,32 +1024,28 @@ static void clone_endio(struct bio *bio)
  * Return maximum size of I/O possible at the supplied sector up to the current
  * target boundary.
  */
-static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
+static inline sector_t max_io_len_target_boundary(struct dm_target *ti,
+						  sector_t target_offset)
 {
-	sector_t target_offset = dm_target_offset(ti, sector);
-
 	return ti->len - target_offset;
 }
 
-static sector_t max_io_len(sector_t sector, struct dm_target *ti)
+static sector_t max_io_len(struct dm_target *ti, sector_t sector)
 {
-	sector_t len = max_io_len_target_boundary(sector, ti);
-	sector_t offset, max_len;
+	sector_t target_offset = dm_target_offset(ti, sector);
+	sector_t len = max_io_len_target_boundary(ti, target_offset);
+	sector_t max_len;
 
 	/*
 	 * Does the target need to split even further?
+	 * - q->limits.chunk_sectors reflects ti->max_io_len so
+	 *   blk_max_size_offset() provides required splitting.
+	 * - blk_max_size_offset() also respects q->limits.max_sectors
 	 */
-	if (ti->max_io_len) {
-		offset = dm_target_offset(ti, sector);
-		if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
-			max_len = sector_div(offset, ti->max_io_len);
-		else
-			max_len = offset & (ti->max_io_len - 1);
-		max_len = ti->max_io_len - max_len;
-
-		if (len > max_len)
-			len = max_len;
-	}
+	max_len = blk_max_size_offset(ti->table->md->queue,
+				      target_offset);
+	if (len > max_len)
+		len = max_len;
 
 	return len;
 }
@@ -1119,7 +1098,7 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 		goto out;
 	if (!ti->type->direct_access)
 		goto out;
-	len = max_io_len(sector, ti) / PAGE_SECTORS;
+	len = max_io_len(ti, sector) / PAGE_SECTORS;
 	if (len < 1)
 		goto out;
 	nr_pages = min(len, nr_pages);
@@ -1431,6 +1410,17 @@ static int __send_empty_flush(struct clone_info *ci)
 {
 	unsigned target_nr = 0;
 	struct dm_target *ti;
+	struct bio flush_bio;
+
+	/*
+	 * Use an on-stack bio for this, it's safe since we don't
+	 * need to reference it after submit. It's just used as
+	 * the basis for the clone(s).
+	 */
+	bio_init(&flush_bio, NULL, 0);
+	flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
+	ci->bio = &flush_bio;
+	ci->sector_count = 0;
 
 	/*
 	 * Empty flush uses a statically initialized bio, as the base for
@@ -1444,6 +1434,8 @@ static int __send_empty_flush(struct clone_info *ci)
 	BUG_ON(bio_has_data(ci->bio));
 	while ((ti = dm_table_get_target(ci->map, target_nr++)))
 		__send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
+
+	bio_uninit(ci->bio);
 	return 0;
 }
 
@@ -1466,28 +1458,6 @@ static int __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
 	return 0;
 }
 
-typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);
-
-static unsigned get_num_discard_bios(struct dm_target *ti)
-{
-	return ti->num_discard_bios;
-}
-
-static unsigned get_num_secure_erase_bios(struct dm_target *ti)
-{
-	return ti->num_secure_erase_bios;
-}
-
-static unsigned get_num_write_same_bios(struct dm_target *ti)
-{
-	return ti->num_write_same_bios;
-}
-
-static unsigned get_num_write_zeroes_bios(struct dm_target *ti)
-{
-	return ti->num_write_zeroes_bios;
-}
-
 static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
 				       unsigned num_bios)
 {
@@ -1502,7 +1472,8 @@ static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *
 	if (!num_bios)
 		return -EOPNOTSUPP;
 
-	len = min((sector_t)ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
+	len = min_t(sector_t, ci->sector_count,
+		    max_io_len_target_boundary(ti, dm_target_offset(ti, ci->sector)));
 
 	__send_duplicate_bios(ci, ti, num_bios, &len);
 
@@ -1512,26 +1483,6 @@ static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *
 	return 0;
 }
 
-static int __send_discard(struct clone_info *ci, struct dm_target *ti)
-{
-	return __send_changing_extent_only(ci, ti, get_num_discard_bios(ti));
-}
-
-static int __send_secure_erase(struct clone_info *ci, struct dm_target *ti)
-{
-	return __send_changing_extent_only(ci, ti, get_num_secure_erase_bios(ti));
-}
-
-static int __send_write_same(struct clone_info *ci, struct dm_target *ti)
-{
-	return __send_changing_extent_only(ci, ti, get_num_write_same_bios(ti));
-}
-
-static int __send_write_zeroes(struct clone_info *ci, struct dm_target *ti)
-{
-	return __send_changing_extent_only(ci, ti, get_num_write_zeroes_bios(ti));
-}
-
 static bool is_abnormal_io(struct bio *bio)
 {
 	bool r = false;
@@ -1552,18 +1503,26 @@ static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti,
 				  int *result)
 {
 	struct bio *bio = ci->bio;
+	unsigned num_bios = 0;
 
-	if (bio_op(bio) == REQ_OP_DISCARD)
-		*result = __send_discard(ci, ti);
-	else if (bio_op(bio) == REQ_OP_SECURE_ERASE)
-		*result = __send_secure_erase(ci, ti);
-	else if (bio_op(bio) == REQ_OP_WRITE_SAME)
-		*result = __send_write_same(ci, ti);
-	else if (bio_op(bio) == REQ_OP_WRITE_ZEROES)
-		*result = __send_write_zeroes(ci, ti);
-	else
+	switch (bio_op(bio)) {
+	case REQ_OP_DISCARD:
+		num_bios = ti->num_discard_bios;
+		break;
+	case REQ_OP_SECURE_ERASE:
+		num_bios = ti->num_secure_erase_bios;
+		break;
+	case REQ_OP_WRITE_SAME:
+		num_bios = ti->num_write_same_bios;
+		break;
+	case REQ_OP_WRITE_ZEROES:
+		num_bios = ti->num_write_zeroes_bios;
+		break;
+	default:
 		return false;
+	}
 
+	*result = __send_changing_extent_only(ci, ti, num_bios);
 	return true;
 }
 
@@ -1583,7 +1542,7 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 	if (__process_abnormal_io(ci, ti, &r))
 		return r;
 
-	len = min_t(sector_t, max_io_len(ci->sector, ti), ci->sector_count);
+	len = min_t(sector_t, max_io_len(ti, ci->sector), ci->sector_count);
 
 	r = __clone_and_map_data_bio(ci, ti, ci->sector, &len);
 	if (r < 0)
@@ -1619,19 +1578,7 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
 	init_clone_info(&ci, md, map, bio);
 
 	if (bio->bi_opf & REQ_PREFLUSH) {
-		struct bio flush_bio;
-
-		/*
-		 * Use an on-stack bio for this, it's safe since we don't
-		 * need to reference it after submit. It's just used as
-		 * the basis for the clone(s).
-		 */
-		bio_init(&flush_bio, NULL, 0);
-		flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
-		ci.bio = &flush_bio;
-		ci.sector_count = 0;
 		error = __send_empty_flush(&ci);
-		bio_uninit(ci.bio);
 		/* dec_pending submits any data associated with flush */
 	} else if (op_is_zone_mgmt(bio_op(bio))) {
 		ci.bio = bio;
@@ -1680,88 +1627,6 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
 	return ret;
 }
 
-/*
- * Optimized variant of __split_and_process_bio that leverages the
- * fact that targets that use it do _not_ have a need to split bios.
- */
-static blk_qc_t __process_bio(struct mapped_device *md, struct dm_table *map,
-			      struct bio *bio, struct dm_target *ti)
-{
-	struct clone_info ci;
-	blk_qc_t ret = BLK_QC_T_NONE;
-	int error = 0;
-
-	init_clone_info(&ci, md, map, bio);
-
-	if (bio->bi_opf & REQ_PREFLUSH) {
-		struct bio flush_bio;
-
-		/*
-		 * Use an on-stack bio for this, it's safe since we don't
-		 * need to reference it after submit. It's just used as
-		 * the basis for the clone(s).
-		 */
-		bio_init(&flush_bio, NULL, 0);
-		flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
-		ci.bio = &flush_bio;
-		ci.sector_count = 0;
-		error = __send_empty_flush(&ci);
-		bio_uninit(ci.bio);
-		/* dec_pending submits any data associated with flush */
-	} else {
-		struct dm_target_io *tio;
-
-		ci.bio = bio;
-		ci.sector_count = bio_sectors(bio);
-		if (__process_abnormal_io(&ci, ti, &error))
-			goto out;
-
-		tio = alloc_tio(&ci, ti, 0, GFP_NOIO);
-		ret = __clone_and_map_simple_bio(&ci, tio, NULL);
-	}
-out:
-	/* drop the extra reference count */
-	dec_pending(ci.io, errno_to_blk_status(error));
-	return ret;
-}
-
-static blk_qc_t dm_process_bio(struct mapped_device *md,
-			       struct dm_table *map, struct bio *bio)
-{
-	blk_qc_t ret = BLK_QC_T_NONE;
-	struct dm_target *ti = md->immutable_target;
-
-	if (unlikely(!map)) {
-		bio_io_error(bio);
-		return ret;
-	}
-
-	if (!ti) {
-		ti = dm_table_find_target(map, bio->bi_iter.bi_sector);
-		if (unlikely(!ti)) {
-			bio_io_error(bio);
-			return ret;
-		}
-	}
-
-	/*
-	 * If in ->submit_bio we need to use blk_queue_split(), otherwise
-	 * queue_limits for abnormal requests (e.g. discard, writesame, etc)
-	 * won't be imposed.
-	 * If called from dm_wq_work() for deferred bio processing, bio
-	 * was already handled by following code with previous ->submit_bio.
-	 */
-	if (current->bio_list) {
-		if (is_abnormal_io(bio))
-			blk_queue_split(&bio);
-		/* regular IO is split by __split_and_process_bio */
-	}
-
-	if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED)
-		return __process_bio(md, map, bio, ti);
-	return __split_and_process_bio(md, map, bio);
-}
-
 static blk_qc_t dm_submit_bio(struct bio *bio)
 {
 	struct mapped_device *md = bio->bi_disk->private_data;
@@ -1769,35 +1634,34 @@ static blk_qc_t dm_submit_bio(struct bio *bio)
 	int srcu_idx;
 	struct dm_table *map;
 
-	if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) {
-		/*
-		 * We are called with a live reference on q_usage_counter, but
-		 * that one will be released as soon as we return.  Grab an
-		 * extra one as blk_mq_submit_bio expects to be able to consume
-		 * a reference (which lives until the request is freed in case a
-		 * request is allocated).
-		 */
-		percpu_ref_get(&bio->bi_disk->queue->q_usage_counter);
-		return blk_mq_submit_bio(bio);
-	}
-
 	map = dm_get_live_table(md, &srcu_idx);
+	if (unlikely(!map)) {
+		DMERR_LIMIT("%s: mapping table unavailable, erroring io",
+			    dm_device_name(md));
+		bio_io_error(bio);
+		goto out;
+	}
 
-	/* if we're suspended, we have to queue this io for later */
+	/* If suspended, queue this IO for later */
 	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
-		dm_put_live_table(md, srcu_idx);
-
 		if (bio->bi_opf & REQ_NOWAIT)
 			bio_wouldblock_error(bio);
-		else if (!(bio->bi_opf & REQ_RAHEAD))
-			queue_io(md, bio);
-		else
+		else if (bio->bi_opf & REQ_RAHEAD)
 			bio_io_error(bio);
-		return ret;
+		else
+			queue_io(md, bio);
+		goto out;
 	}
 
-	ret = dm_process_bio(md, map, bio);
+	/*
+	 * Use blk_queue_split() for abnormal IO (e.g. discard, writesame, etc)
+	 * otherwise associated queue_limits won't be imposed.
+	 */
+	if (is_abnormal_io(bio))
+		blk_queue_split(&bio);
 
+	ret = __split_and_process_bio(md, map, bio);
+out:
 	dm_put_live_table(md, srcu_idx);
 	return ret;
 }
@@ -1852,6 +1716,7 @@ static int next_free_minor(int *minor)
 }
 
 static const struct block_device_operations dm_blk_dops;
+static const struct block_device_operations dm_rq_blk_dops;
 static const struct dax_operations dm_dax_ops;
 
 static void dm_wq_work(struct work_struct *work);
@@ -2121,12 +1986,10 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 	if (request_based)
 		dm_stop_queue(q);
 
-	if (request_based || md->type == DM_TYPE_NVME_BIO_BASED) {
+	if (request_based) {
 		/*
-		 * Leverage the fact that request-based DM targets and
-		 * NVMe bio based targets are immutable singletons
-		 * - used to optimize both dm_request_fn and dm_mq_queue_rq;
-		 *   and __process_bio.
+		 * Leverage the fact that request-based DM targets are
+		 * immutable singletons - used to optimize dm_mq_queue_rq.
 		 */
 		md->immutable_target = dm_table_get_immutable_target(t);
 	}
@@ -2240,15 +2103,15 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
 
 	switch (type) {
 	case DM_TYPE_REQUEST_BASED:
+		md->disk->fops = &dm_rq_blk_dops;
 		r = dm_mq_init_request_queue(md, t);
 		if (r) {
-			DMERR("Cannot initialize queue for request-based dm-mq mapped device");
+			DMERR("Cannot initialize queue for request-based dm mapped device");
 			return r;
 		}
 		break;
 	case DM_TYPE_BIO_BASED:
 	case DM_TYPE_DAX_BIO_BASED:
-	case DM_TYPE_NVME_BIO_BASED:
 		break;
 	case DM_TYPE_NONE:
 		WARN_ON_ONCE(true);
@@ -2453,29 +2316,19 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state)
  */
 static void dm_wq_work(struct work_struct *work)
 {
-	struct mapped_device *md = container_of(work, struct mapped_device,
-						work);
-	struct bio *c;
-	int srcu_idx;
-	struct dm_table *map;
-
-	map = dm_get_live_table(md, &srcu_idx);
+	struct mapped_device *md = container_of(work, struct mapped_device, work);
+	struct bio *bio;
 
 	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
 		spin_lock_irq(&md->deferred_lock);
-		c = bio_list_pop(&md->deferred);
+		bio = bio_list_pop(&md->deferred);
 		spin_unlock_irq(&md->deferred_lock);
 
-		if (!c)
+		if (!bio)
 			break;
 
-		if (dm_request_based(md))
-			(void) submit_bio_noacct(c);
-		else
-			(void) dm_process_bio(md, map, c);
+		submit_bio_noacct(bio);
 	}
-
-	dm_put_live_table(md, srcu_idx);
 }
 
 static void dm_queue_flush(struct mapped_device *md)
@@ -2612,13 +2465,12 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
 	/*
 	 * Here we must make sure that no processes are submitting requests
 	 * to target drivers i.e. no one may be executing
-	 * __split_and_process_bio. This is called from dm_request and
-	 * dm_wq_work.
+	 * __split_and_process_bio from dm_submit_bio.
 	 *
-	 * To get all processes out of __split_and_process_bio in dm_request,
+	 * To get all processes out of __split_and_process_bio in dm_submit_bio,
 	 * we take the write lock. To prevent any process from reentering
-	 * __split_and_process_bio from dm_request and quiesce the thread
-	 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
+	 * __split_and_process_bio from dm_submit_bio and quiesce the thread
+	 * (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND and call
 	 * flush_workqueue(md->wq).
 	 */
 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
@@ -2986,19 +2838,19 @@ int dm_test_deferred_remove_flag(struct mapped_device *md)
 
 int dm_suspended(struct dm_target *ti)
 {
-	return dm_suspended_md(dm_table_get_md(ti->table));
+	return dm_suspended_md(ti->table->md);
 }
 EXPORT_SYMBOL_GPL(dm_suspended);
 
 int dm_post_suspending(struct dm_target *ti)
 {
-	return dm_post_suspending_md(dm_table_get_md(ti->table));
+	return dm_post_suspending_md(ti->table->md);
 }
 EXPORT_SYMBOL_GPL(dm_post_suspending);
 
 int dm_noflush_suspending(struct dm_target *ti)
 {
-	return __noflush_suspending(dm_table_get_md(ti->table));
+	return __noflush_suspending(ti->table->md);
 }
 EXPORT_SYMBOL_GPL(dm_noflush_suspending);
 
@@ -3017,7 +2869,6 @@ struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_qu
 	switch (type) {
 	case DM_TYPE_BIO_BASED:
 	case DM_TYPE_DAX_BIO_BASED:
-	case DM_TYPE_NVME_BIO_BASED:
 		pool_size = max(dm_get_reserved_bio_based_ios(), min_pool_size);
 		front_pad = roundup(per_io_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
 		io_front_pad = roundup(front_pad,  __alignof__(struct dm_io)) + offsetof(struct dm_io, tio);
@@ -3235,6 +3086,15 @@ static const struct block_device_operations dm_blk_dops = {
 	.owner = THIS_MODULE
 };
 
+static const struct block_device_operations dm_rq_blk_dops = {
+	.open = dm_blk_open,
+	.release = dm_blk_close,
+	.ioctl = dm_blk_ioctl,
+	.getgeo = dm_blk_getgeo,
+	.pr_ops = &dm_pr_ops,
+	.owner = THIS_MODULE
+};
+
 static const struct dax_operations dm_dax_ops = {
 	.direct_access = dm_dax_direct_access,
 	.dax_supported = dm_dax_supported,
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 4f5fe664d05a..fffe1e289c53 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -179,12 +179,9 @@ int dm_open_count(struct mapped_device *md);
 int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred);
 int dm_cancel_deferred_remove(struct mapped_device *md);
 int dm_request_based(struct mapped_device *md);
-sector_t dm_get_size(struct mapped_device *md);
-struct request_queue *dm_get_md_queue(struct mapped_device *md);
 int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
 			struct dm_dev **result);
 void dm_put_table_device(struct mapped_device *md, struct dm_dev *d);
-struct dm_stats *dm_get_stats(struct mapped_device *md);
 
 int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
 		      unsigned cookie);
diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index 8aae0624a297..ef6e78d45d5b 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -366,7 +366,8 @@ static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
 	} while (!(flags & LEAF_NODE));
 
 	*result_key = le64_to_cpu(ro_node(s)->keys[i]);
-	memcpy(v, value_ptr(ro_node(s), i), value_size);
+	if (v)
+		memcpy(v, value_ptr(ro_node(s), i), value_size);
 
 	return 0;
 }