Merge tag 'for-6.0/dm-changes' of...

Merge tag 'for-6.0/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Refactor DM core's mempool allocation so that it clearer by not being
   split acorss files.

 - Improve DM core's BLK_STS_DM_REQUEUE and BLK_STS_AGAIN handling.

 - Optimize DM core's more common bio splitting by eliminating the use
   of bio cloning with bio_split+bio_chain. Shift that cloning cost to
   the relatively unlikely dm_io requeue case that only occurs during
   error handling. Introduces dm_io_rewind() that will clone a bio that
   reflects the subset of the original bio that must be requeued.

 - Remove DM core's dm_table_get_num_targets() wrapper and audit all
   dm_table_get_target() callers.

 - Fix potential for OOM with DM writecache target by setting a default
   MAX_WRITEBACK_JOBS (set to 256MiB or 1/16 of total system memory,
   whichever is smaller).

 - Fix DM writecache target's stats that are reported through
   DM-specific table info.

 - Fix use-after-free crash in dm_sm_register_threshold_callback().

 - Refine DM core's Persistent Reservation handling in preparation for
   broader work Mike Christie is doing to add compatibility with
   Microsoft Windows Failover Cluster.

 - Fix various KASAN reported bugs in the DM raid target.

 - Fix DM raid target crash due to md_handle_request() bio splitting
   that recurses to block core without properly initializing the bio's
   bi_dev.

 - Fix some code comment typos and fix some Documentation formatting.

* tag 'for-6.0/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (29 commits)
  dm: fix dm-raid crash if md_handle_request() splits bio
  dm raid: fix address sanitizer warning in raid_resume
  dm raid: fix address sanitizer warning in raid_status
  dm: Start pr_preempt from the same starting path
  dm: Fix PR release handling for non All Registrants
  dm: Start pr_reserve from the same starting path
  dm: Allow dm_call_pr to be used for path searches
  dm: return early from dm_pr_call() if DM device is suspended
  dm thin: fix use-after-free crash in dm_sm_register_threshold_callback
  dm writecache: count number of blocks discarded, not number of discard bios
  dm writecache: count number of blocks written, not number of write bios
  dm writecache: count number of blocks read, not number of read bios
  dm writecache: return void from functions
  dm kcopyd: use __GFP_HIGHMEM when allocating pages
  dm writecache: set a default MAX_WRITEBACK_JOBS
  Documentation: dm writecache: Render status list as list
  Documentation: dm writecache: add blank line before optional parameters
  dm snapshot: fix typo in snapshot_map() comment
  dm raid: remove redundant "the" in parse_raid_params() comment
  dm cache: fix typo in 2 comment blocks
  ...

Documentation/admin-guide/device-mapper/writecache.rst

@@ -20,6 +20,7 @@ Constructor parameters:
    size)
 5. the number of optional parameters (the parameters with an argument
    count as two)
+
 	start_sector n		(default: 0)
 		offset from the start of cache device in 512-byte sectors
 	high_watermark n	(default: 50)
@@ -74,20 +75,21 @@ Constructor parameters:
 		the origin volume in the last n milliseconds
 
 Status:
+
 1. error indicator - 0 if there was no error, otherwise error number
 2. the number of blocks
 3. the number of free blocks
 4. the number of blocks under writeback
-5. the number of read requests
-6. the number of read requests that hit the cache
-7. the number of write requests
-8. the number of write requests that hit uncommitted block
-9. the number of write requests that hit committed block
-10. the number of write requests that bypass the cache
-11. the number of write requests that are allocated in the cache
+5. the number of read blocks
+6. the number of read blocks that hit the cache
+7. the number of write blocks
+8. the number of write blocks that hit uncommitted block
+9. the number of write blocks that hit committed block
+10. the number of write blocks that bypass the cache
+11. the number of write blocks that are allocated in the cache
 12. the number of write requests that are blocked on the freelist
 13. the number of flush requests
-14. the number of discard requests
+14. the number of discarded blocks
 
 Messages:
 	flush

drivers/md/Makefile

@@ -5,7 +5,7 @@
 
 dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
 		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
-		   dm-rq.o
+		   dm-rq.o dm-io-rewind.o
 dm-multipath-y	+= dm-path-selector.o dm-mpath.o
 dm-historical-service-time-y += dm-ps-historical-service-time.o
 dm-io-affinity-y += dm-ps-io-affinity.o

drivers/md/dm-cache-metadata.h

@@ -131,7 +131,7 @@ void dm_cache_dump(struct dm_cache_metadata *cmd);
  * hints will be lost.
  *
  * The hints are indexed by the cblock, but many policies will not
- * neccessarily have a fast way of accessing efficiently via cblock.  So
+ * necessarily have a fast way of accessing efficiently via cblock.  So
  * rather than querying the policy for each cblock, we let it walk its data
  * structures and fill in the hints in whatever order it wishes.
  */

drivers/md/dm-cache-target.c

@@ -2775,7 +2775,7 @@ static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
 
 /*
  * The discard block size in the on disk metadata is not
- * neccessarily the same as we're currently using.  So we have to
+ * necessarily the same as we're currently using.  So we have to
  * be careful to only set the discarded attribute if we know it
  * covers a complete block of the new size.
  */

drivers/md/dm-core.h

@@ -22,6 +22,8 @@
 
 #define DM_RESERVED_MAX_IOS		1024
 
+struct dm_io;
+
 struct dm_kobject_holder {
 	struct kobject kobj;
 	struct completion completion;
@@ -91,6 +93,14 @@ struct mapped_device {
 	spinlock_t deferred_lock;
 	struct bio_list deferred;
 
+	/*
+	 * requeue work context is needed for cloning one new bio
+	 * to represent the dm_io to be requeued, since each
+	 * dm_io may point to the original bio from FS.
+	 */
+	struct work_struct requeue_work;
+	struct dm_io *requeue_list;
+
 	void *interface_ptr;
 
 	/*
@@ -216,6 +226,13 @@ struct dm_table {
 #endif
 };
 
+static inline struct dm_target *dm_table_get_target(struct dm_table *t,
+						    unsigned int index)
+{
+	BUG_ON(index >= t->num_targets);
+	return t->targets + index;
+}
+
 /*
  * One of these is allocated per clone bio.
  */
@@ -230,6 +247,9 @@ struct dm_target_io {
 	sector_t old_sector;
 	struct bio clone;
 };
+#define DM_TARGET_IO_BIO_OFFSET (offsetof(struct dm_target_io, clone))
+#define DM_IO_BIO_OFFSET \
+	(offsetof(struct dm_target_io, clone) + offsetof(struct dm_io, tio))
 
 /*
  * dm_target_io flags
@@ -272,7 +292,6 @@ struct dm_io {
 	atomic_t io_count;
 	struct mapped_device *md;
 
-	struct bio *split_bio;
 	/* The three fields represent mapped part of original bio */
 	struct bio *orig_bio;
 	unsigned int sector_offset; /* offset to end of orig_bio */
@@ -300,6 +319,8 @@ static inline void dm_io_set_flag(struct dm_io *io, unsigned int bit)
 	io->flags |= (1U << bit);
 }
 
+void dm_io_rewind(struct dm_io *io, struct bio_set *bs);
+
 static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
 {
 	return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;

drivers/md/dm-ima.c

@@ -208,7 +208,7 @@ void dm_ima_measure_on_table_load(struct dm_table *table, unsigned int status_fl
 	if (!target_data_buf)
 		goto error;
 
-	num_targets = dm_table_get_num_targets(table);
+	num_targets = table->num_targets;
 
 	if (dm_ima_alloc_and_copy_device_data(table->md, &device_data_buf, num_targets, noio))
 		goto error;
@@ -237,9 +237,6 @@ void dm_ima_measure_on_table_load(struct dm_table *table, unsigned int status_fl
 	for (i = 0; i < num_targets; i++) {
 		struct dm_target *ti = dm_table_get_target(table, i);
 
-		if (!ti)
-			goto error;
-
 		last_target_measured = 0;
 
 		/*

drivers/md/dm-io-rewind.c

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2022 Red Hat, Inc.
+ */
+
+#include <linux/bio.h>
+#include <linux/blk-crypto.h>
+#include <linux/blk-integrity.h>
+
+#include "dm-core.h"
+
+static inline bool dm_bvec_iter_rewind(const struct bio_vec *bv,
+				       struct bvec_iter *iter,
+				       unsigned int bytes)
+{
+	int idx;
+
+	iter->bi_size += bytes;
+	if (bytes <= iter->bi_bvec_done) {
+		iter->bi_bvec_done -= bytes;
+		return true;
+	}
+
+	bytes -= iter->bi_bvec_done;
+	idx = iter->bi_idx - 1;
+
+	while (idx >= 0 && bytes && bytes > bv[idx].bv_len) {
+		bytes -= bv[idx].bv_len;
+		idx--;
+	}
+
+	if (WARN_ONCE(idx < 0 && bytes,
+		      "Attempted to rewind iter beyond bvec's boundaries\n")) {
+		iter->bi_size -= bytes;
+		iter->bi_bvec_done = 0;
+		iter->bi_idx = 0;
+		return false;
+	}
+
+	iter->bi_idx = idx;
+	iter->bi_bvec_done = bv[idx].bv_len - bytes;
+	return true;
+}
+
+#if defined(CONFIG_BLK_DEV_INTEGRITY)
+
+/**
+ * dm_bio_integrity_rewind - Rewind integrity vector
+ * @bio:	bio whose integrity vector to update
+ * @bytes_done:	number of data bytes to rewind
+ *
+ * Description: This function calculates how many integrity bytes the
+ * number of completed data bytes correspond to and rewind the
+ * integrity vector accordingly.
+ */
+static void dm_bio_integrity_rewind(struct bio *bio, unsigned int bytes_done)
+{
+	struct bio_integrity_payload *bip = bio_integrity(bio);
+	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
+	unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
+
+	bip->bip_iter.bi_sector -= bio_integrity_intervals(bi, bytes_done >> 9);
+	dm_bvec_iter_rewind(bip->bip_vec, &bip->bip_iter, bytes);
+}
+
+#else /* CONFIG_BLK_DEV_INTEGRITY */
+
+static inline void dm_bio_integrity_rewind(struct bio *bio,
+					   unsigned int bytes_done)
+{
+	return;
+}
+
+#endif
+
+#if defined(CONFIG_BLK_INLINE_ENCRYPTION)
+
+/* Decrements @dun by @dec, treating @dun as a multi-limb integer. */
+static void dm_bio_crypt_dun_decrement(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
+				       unsigned int dec)
+{
+	int i;
+
+	for (i = 0; dec && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
+		u64 prev = dun[i];
+
+		dun[i] -= dec;
+		if (dun[i] > prev)
+			dec = 1;
+		else
+			dec = 0;
+	}
+}
+
+static void dm_bio_crypt_rewind(struct bio *bio, unsigned int bytes)
+{
+	struct bio_crypt_ctx *bc = bio->bi_crypt_context;
+
+	dm_bio_crypt_dun_decrement(bc->bc_dun,
+				   bytes >> bc->bc_key->data_unit_size_bits);
+}
+
+#else /* CONFIG_BLK_INLINE_ENCRYPTION */
+
+static inline void dm_bio_crypt_rewind(struct bio *bio, unsigned int bytes)
+{
+	return;
+}
+
+#endif
+
+static inline void dm_bio_rewind_iter(const struct bio *bio,
+				      struct bvec_iter *iter, unsigned int bytes)
+{
+	iter->bi_sector -= bytes >> 9;
+
+	/* No advance means no rewind */
+	if (bio_no_advance_iter(bio))
+		iter->bi_size += bytes;
+	else
+		dm_bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
+}
+
+/**
+ * dm_bio_rewind - update ->bi_iter of @bio by rewinding @bytes.
+ * @bio: bio to rewind
+ * @bytes: how many bytes to rewind
+ *
+ * WARNING:
+ * Caller must ensure that @bio has a fixed end sector, to allow
+ * rewinding from end of bio and restoring its original position.
+ * Caller is also responsibile for restoring bio's size.
+ */
+static void dm_bio_rewind(struct bio *bio, unsigned bytes)
+{
+	if (bio_integrity(bio))
+		dm_bio_integrity_rewind(bio, bytes);
+
+	if (bio_has_crypt_ctx(bio))
+		dm_bio_crypt_rewind(bio, bytes);
+
+	dm_bio_rewind_iter(bio, &bio->bi_iter, bytes);
+}
+
+void dm_io_rewind(struct dm_io *io, struct bio_set *bs)
+{
+	struct bio *orig = io->orig_bio;
+	struct bio *new_orig = bio_alloc_clone(orig->bi_bdev, orig,
+					       GFP_NOIO, bs);
+	/*
+	 * dm_bio_rewind can restore to previous position since the
+	 * end sector is fixed for original bio, but we still need
+	 * to restore bio's size manually (using io->sectors).
+	 */
+	dm_bio_rewind(new_orig, ((io->sector_offset << 9) -
+				 orig->bi_iter.bi_size));
+	bio_trim(new_orig, 0, io->sectors);
+
+	bio_chain(new_orig, orig);
+	/*
+	 * __bi_remaining was increased (by dm_split_and_process_bio),
+	 * so must drop the one added in bio_chain.
+	 */
+	atomic_dec(&orig->__bi_remaining);
+	io->orig_bio = new_orig;
+}

drivers/md/dm-ioctl.c

@@ -832,7 +832,7 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 		if (!(param->flags & DM_QUERY_INACTIVE_TABLE_FLAG)) {
 			if (get_disk_ro(disk))
 				param->flags |= DM_READONLY_FLAG;
-			param->target_count = dm_table_get_num_targets(table);
+			param->target_count = table->num_targets;
 		}
 
 		param->flags |= DM_ACTIVE_PRESENT_FLAG;
@@ -845,7 +845,7 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 		if (table) {
 			if (!(dm_table_get_mode(table) & FMODE_WRITE))
 				param->flags |= DM_READONLY_FLAG;
-			param->target_count = dm_table_get_num_targets(table);
+			param->target_count = table->num_targets;
 		}
 		dm_put_live_table(md, srcu_idx);
 	}
@@ -1248,7 +1248,7 @@ static void retrieve_status(struct dm_table *table,
 		type = STATUSTYPE_INFO;
 
 	/* Get all the target info */
-	num_targets = dm_table_get_num_targets(table);
+	num_targets = table->num_targets;
 	for (i = 0; i < num_targets; i++) {
 		struct dm_target *ti = dm_table_get_target(table, i);
 		size_t l;

drivers/md/dm-kcopyd.c

@@ -219,7 +219,7 @@ static struct page_list *alloc_pl(gfp_t gfp)
 	if (!pl)
 		return NULL;
 
-	pl->page = alloc_page(gfp);
+	pl->page = alloc_page(gfp | __GFP_HIGHMEM);
 	if (!pl->page) {
 		kfree(pl);
 		return NULL;

drivers/md/dm-raid.c

@@ -1369,7 +1369,7 @@ static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
 			}
 			rs->md.bitmap_info.daemon_sleep = value;
 		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET))) {
-			/* Userspace passes new data_offset after having extended the the data image LV */
+			/* Userspace passes new data_offset after having extended the data image LV */
 			if (test_and_set_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
 				rs->ti->error = "Only one data_offset argument pair allowed";
 				return -EINVAL;
@@ -3097,6 +3097,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	INIT_WORK(&rs->md.event_work, do_table_event);
 	ti->private = rs;
 	ti->num_flush_bios = 1;
+	ti->needs_bio_set_dev = true;
 
 	/* Restore any requested new layout for conversion decision */
 	rs_config_restore(rs, &rs_layout);
@@ -3509,7 +3510,7 @@ static void raid_status(struct dm_target *ti, status_type_t type,
 {
 	struct raid_set *rs = ti->private;
 	struct mddev *mddev = &rs->md;
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf = rs_is_raid456(rs) ? mddev->private : NULL;
 	int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
 	unsigned long recovery;
 	unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */
@@ -3819,7 +3820,7 @@ static void attempt_restore_of_faulty_devices(struct raid_set *rs)
 
 	memset(cleared_failed_devices, 0, sizeof(cleared_failed_devices));
 
-	for (i = 0; i < mddev->raid_disks; i++) {
+	for (i = 0; i < rs->raid_disks; i++) {
 		r = &rs->dev[i].rdev;
 		/* HM FIXME: enhance journal device recovery processing */
 		if (test_bit(Journal, &r->flags))

drivers/md/dm-rq.c

@@ -43,7 +43,6 @@ unsigned dm_get_reserved_rq_based_ios(void)
 	return __dm_get_module_param(&reserved_rq_based_ios,
 				     RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
 }
-EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
 
 static unsigned dm_get_blk_mq_nr_hw_queues(void)
 {

drivers/md/dm-snap.c

@@ -2026,7 +2026,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	/*
 	 * Write to snapshot - higher level takes care of RW/RO
 	 * flags so we should only get this if we are
-	 * writeable.
+	 * writable.
 	 */
 	if (bio_data_dir(bio) == WRITE) {
 		pe = __lookup_pending_exception(s, chunk);

drivers/md/dm-thin-metadata.c

@@ -2045,10 +2045,13 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 					dm_sm_threshold_fn fn,
 					void *context)
 {
-	int r;
+	int r = -EINVAL;
 
 	pmd_write_lock_in_core(pmd);
-	r = dm_sm_register_threshold_callback(pmd->metadata_sm, threshold, fn, context);
+	if (!pmd->fail_io) {
+		r = dm_sm_register_threshold_callback(pmd->metadata_sm,
+						      threshold, fn, context);
+	}
 	pmd_write_unlock(pmd);
 
 	return r;

drivers/md/dm-thin.c

@@ -3375,8 +3375,10 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
 						calc_metadata_threshold(pt),
 						metadata_low_callback,
 						pool);
-	if (r)
+	if (r) {
+		ti->error = "Error registering metadata threshold";
 		goto out_flags_changed;
+	}
 
 	dm_pool_register_pre_commit_callback(pool->pmd,
 					     metadata_pre_commit_callback, pool);

drivers/md/dm-verity-target.c

@@ -527,11 +527,10 @@ static int verity_verify_io(struct dm_verity_io *io)
 			if (v->validated_blocks)
 				set_bit(cur_block, v->validated_blocks);
 			continue;
-		}
-		else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
-					   cur_block, NULL, &start) == 0)
+		} else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
+					   cur_block, NULL, &start) == 0) {
 			continue;
-		else {
+		} else {
 			if (bio->bi_status) {
 				/*
 				 * Error correction failed; Just return error

drivers/md/dm-writecache.c

@@ -22,7 +22,7 @@
 
 #define HIGH_WATERMARK			50
 #define LOW_WATERMARK			45
-#define MAX_WRITEBACK_JOBS		0
+#define MAX_WRITEBACK_JOBS		min(0x10000000 / PAGE_SIZE, totalram_pages() / 16)
 #define ENDIO_LATENCY			16
 #define WRITEBACK_LATENCY		64
 #define AUTOCOMMIT_BLOCKS_SSD		65536
@@ -1325,8 +1325,8 @@ enum wc_map_op {
 	WC_MAP_ERROR,
 };
 
-static enum wc_map_op writecache_map_remap_origin(struct dm_writecache *wc, struct bio *bio,
-						  struct wc_entry *e)
+static void writecache_map_remap_origin(struct dm_writecache *wc, struct bio *bio,
+					struct wc_entry *e)
 {
 	if (e) {
 		sector_t next_boundary =
@@ -1334,8 +1334,6 @@ static enum wc_map_op writecache_map_remap_origin(struct dm_writecache *wc, stru
 		if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT)
 			dm_accept_partial_bio(bio, next_boundary);
 	}
-
-	return WC_MAP_REMAP_ORIGIN;
 }
 
 static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *bio)
@@ -1362,14 +1360,16 @@ static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *
 			map_op = WC_MAP_REMAP;
 		}
 	} else {
-		map_op = writecache_map_remap_origin(wc, bio, e);
+		writecache_map_remap_origin(wc, bio, e);
+		wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
+		map_op = WC_MAP_REMAP_ORIGIN;
 	}
 
 	return map_op;
 }
 
-static enum wc_map_op writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
-					      struct wc_entry *e, bool search_used)
+static void writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
+				    struct wc_entry *e, bool search_used)
 {
 	unsigned bio_size = wc->block_size;
 	sector_t start_cache_sec = cache_sector(wc, e);
@@ -1409,14 +1409,15 @@ static enum wc_map_op writecache_bio_copy_ssd(struct dm_writecache *wc, struct b
 	bio->bi_iter.bi_sector = start_cache_sec;
 	dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
 
+	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
+	wc->stats.writes_allocate += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
+
 	if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
 		wc->uncommitted_blocks = 0;
 		queue_work(wc->writeback_wq, &wc->flush_work);
 	} else {
 		writecache_schedule_autocommit(wc);
 	}
-
-	return WC_MAP_REMAP;
 }
 
 static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
@@ -1426,9 +1427,10 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
 	do {
 		bool found_entry = false;
 		bool search_used = false;
-		wc->stats.writes++;
-		if (writecache_has_error(wc))
+		if (writecache_has_error(wc)) {
+			wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
 			return WC_MAP_ERROR;
+		}
 		e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
 		if (e) {
 			if (!writecache_entry_is_committed(wc, e)) {
@@ -1452,9 +1454,11 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
 		if (unlikely(!e)) {
 			if (!WC_MODE_PMEM(wc) && !found_entry) {
 direct_write:
-				wc->stats.writes_around++;
 				e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
-				return writecache_map_remap_origin(wc, bio, e);
+				writecache_map_remap_origin(wc, bio, e);
+				wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
+				wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
+				return WC_MAP_REMAP_ORIGIN;
 			}
 			wc->stats.writes_blocked_on_freelist++;
 			writecache_wait_on_freelist(wc);
@@ -1465,10 +1469,13 @@ static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio
 		wc->uncommitted_blocks++;
 		wc->stats.writes_allocate++;
 bio_copy:
-		if (WC_MODE_PMEM(wc))
+		if (WC_MODE_PMEM(wc)) {
 			bio_copy_block(wc, bio, memory_data(wc, e));
-		else
-			return writecache_bio_copy_ssd(wc, bio, e, search_used);
+			wc->stats.writes++;
+		} else {
+			writecache_bio_copy_ssd(wc, bio, e, search_used);
+			return WC_MAP_REMAP;
+		}
 	} while (bio->bi_iter.bi_size);
 
 	if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks))
@@ -1503,7 +1510,7 @@ static enum wc_map_op writecache_map_flush(struct dm_writecache *wc, struct bio
 
 static enum wc_map_op writecache_map_discard(struct dm_writecache *wc, struct bio *bio)
 {
-	wc->stats.discards++;
+	wc->stats.discards += bio->bi_iter.bi_size >> wc->block_size_bits;
 
 	if (writecache_has_error(wc))
 		return WC_MAP_ERROR;

drivers/md/dm-zone.c

@@ -273,11 +273,8 @@ static int device_not_zone_append_capable(struct dm_target *ti,
 
 static bool dm_table_supports_zone_append(struct dm_table *t)
 {
-	struct dm_target *ti;
-	unsigned int i;
-
-	for (i = 0; i < dm_table_get_num_targets(t); i++) {
-		ti = dm_table_get_target(t, i);
+	for (unsigned int i = 0; i < t->num_targets; i++) {
+		struct dm_target *ti = dm_table_get_target(t, i);
 
 		if (ti->emulate_zone_append)
 			return false;

drivers/md/dm.h

@@ -53,7 +53,6 @@ struct dm_io;
  *---------------------------------------------------------------*/
 void dm_table_event_callback(struct dm_table *t,
 			     void (*fn)(void *), void *context);
-struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index);
 struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector);
 bool dm_table_has_no_data_devices(struct dm_table *table);
 int dm_calculate_queue_limits(struct dm_table *table,
@@ -218,9 +217,6 @@ void dm_kcopyd_exit(void);
 /*
  * Mempool operations
  */
-struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_queue_mode type,
-					    unsigned per_io_data_size, unsigned min_pool_size,
-					    bool integrity, bool poll);
 void dm_free_md_mempools(struct dm_md_mempools *pools);
 
 /*

include/linux/device-mapper.h

@@ -373,6 +373,12 @@ struct dm_target {
 	 * after returning DM_MAPIO_SUBMITTED from its map function.
 	 */
 	bool accounts_remapped_io:1;
+
+	/*
+	 * Set if the target will submit the DM bio without first calling
+	 * bio_set_dev(). NOTE: ideally a target should _not_ need this.
+	 */
+	bool needs_bio_set_dev:1;
 };
 
 void *dm_per_bio_data(struct bio *bio, size_t data_size);
@@ -561,7 +567,6 @@ void dm_sync_table(struct mapped_device *md);
  * Queries
  */
 sector_t dm_table_get_size(struct dm_table *t);
-unsigned int dm_table_get_num_targets(struct dm_table *t);
 fmode_t dm_table_get_mode(struct dm_table *t);
 struct mapped_device *dm_table_get_md(struct dm_table *t);
 const char *dm_table_device_name(struct dm_table *t);

include/uapi/linux/dm-ioctl.h

@@ -286,9 +286,9 @@ enum {
 #define DM_DEV_SET_GEOMETRY	_IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR	4
-#define DM_VERSION_MINOR	46
+#define DM_VERSION_MINOR	47
 #define DM_VERSION_PATCHLEVEL	0
-#define DM_VERSION_EXTRA	"-ioctl (2022-02-22)"
+#define DM_VERSION_EXTRA	"-ioctl (2022-07-28)"
 
 /* Status bits */
 #define DM_READONLY_FLAG	(1 << 0) /* In/Out */