drivers/md/dm-zone.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2021 Western Digital Corporation or its affiliates.
  */

 #include <linux/blkdev.h>
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
 #include <linux/bitmap.h>

 #include "dm-core.h"

 #define DM_MSG_PREFIX "zone"

 /*
  * For internal zone reports bypassing the top BIO submission path.
  */
 static int dm_blk_do_report_zones(struct mapped_device *md, struct dm_table *t,
 				  sector_t sector, unsigned int nr_zones,
 				  report_zones_cb cb, void *data)
 {
 	struct gendisk *disk = md->disk;
 	int ret;
 	struct dm_report_zones_args args = {
 		.next_sector = sector,
 		.orig_data = data,
 		.orig_cb = cb,
 	};

 	do {
 		struct dm_target *tgt;

 		tgt = dm_table_find_target(t, args.next_sector);
 		if (WARN_ON_ONCE(!tgt->type->report_zones))
 			return -EIO;

 		args.tgt = tgt;
 		ret = tgt->type->report_zones(tgt, &args,
 					      nr_zones - args.zone_idx);
 		if (ret < 0)
 			return ret;
 	} while (args.zone_idx < nr_zones &&
 		 args.next_sector < get_capacity(disk));

 	return args.zone_idx;
 }

 /*
  * User facing dm device block device report zone operation. This calls the
  * report_zones operation for each target of a device table. This operation is
  * generally implemented by targets using dm_report_zones().
  */
 int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
 			unsigned int nr_zones, report_zones_cb cb, void *data)
 {
 	struct mapped_device *md = disk->private_data;
 	struct dm_table *map;
 	int srcu_idx, ret;

 	if (!md->zone_revalidate_map) {
 		/* Regular user context */
 		if (dm_suspended_md(md))
 			return -EAGAIN;

 		map = dm_get_live_table(md, &srcu_idx);
 		if (!map)
 			return -EIO;
 	} else {
 		/* Zone revalidation during __bind() */
 		map = md->zone_revalidate_map;
 	}

 	ret = dm_blk_do_report_zones(md, map, sector, nr_zones, cb, data);

 	if (!md->zone_revalidate_map)
 		dm_put_live_table(md, srcu_idx);

 	return ret;
 }

 static int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx,
 			      void *data)
 {
 	struct dm_report_zones_args *args = data;
 	sector_t sector_diff = args->tgt->begin - args->start;

 	/*
 	 * Ignore zones beyond the target range.
 	 */
 	if (zone->start >= args->start + args->tgt->len)
 		return 0;

 	/*
 	 * Remap the start sector and write pointer position of the zone
 	 * to match its position in the target range.
 	 */
 	zone->start += sector_diff;
 	if (zone->type != BLK_ZONE_TYPE_CONVENTIONAL) {
 		if (zone->cond == BLK_ZONE_COND_FULL)
 			zone->wp = zone->start + zone->len;
 		else if (zone->cond == BLK_ZONE_COND_EMPTY)
 			zone->wp = zone->start;
 		else
 			zone->wp += sector_diff;
 	}

 	args->next_sector = zone->start + zone->len;
 	return args->orig_cb(zone, args->zone_idx++, args->orig_data);
 }

 /*
  * Helper for drivers of zoned targets to implement struct target_type
  * report_zones operation.
  */
 int dm_report_zones(struct block_device *bdev, sector_t start, sector_t sector,
 		    struct dm_report_zones_args *args, unsigned int nr_zones)
 {
 	/*
 	 * Set the target mapping start sector first so that
 	 * dm_report_zones_cb() can correctly remap zone information.
 	 */
 	args->start = start;

 	return blkdev_report_zones(bdev, sector, nr_zones,
 				   dm_report_zones_cb, args);
 }
 EXPORT_SYMBOL_GPL(dm_report_zones);

 bool dm_is_zone_write(struct mapped_device *md, struct bio *bio)
 {
 	struct request_queue *q = md->queue;

 	if (!blk_queue_is_zoned(q))
 		return false;

 	switch (bio_op(bio)) {
 	case REQ_OP_WRITE_ZEROES:
 	case REQ_OP_WRITE:
 		return !op_is_flush(bio->bi_opf) && bio_sectors(bio);
 	default:
 		return false;
 	}
 }

 /*
  * Revalidate the zones of a mapped device to initialize resource necessary
  * for zone append emulation. Note that we cannot simply use the block layer
  * blk_revalidate_disk_zones() function here as the mapped device is suspended
  * (this is called from __bind() context).
  */
 int dm_revalidate_zones(struct dm_table *t, struct request_queue *q)
 {
 	struct mapped_device *md = t->md;
 	struct gendisk *disk = md->disk;
 	int ret;

 	if (!get_capacity(disk))
 		return 0;

 	/* Revalidate only if something changed. */
 	if (!disk->nr_zones || disk->nr_zones != md->nr_zones) {
 		DMINFO("%s using %s zone append",
 		       disk->disk_name,
 		       queue_emulates_zone_append(q) ? "emulated" : "native");
 		md->nr_zones = 0;
 	}

 	if (md->nr_zones)
 		return 0;

 	/*
 	 * Our table is not live yet. So the call to dm_get_live_table()
 	 * in dm_blk_report_zones() will fail. Set a temporary pointer to
 	 * our table for dm_blk_report_zones() to use directly.
 	 */
 	md->zone_revalidate_map = t;
 	ret = blk_revalidate_disk_zones(disk);
 	md->zone_revalidate_map = NULL;

 	if (ret) {
 		DMERR("Revalidate zones failed %d", ret);
 		return ret;
 	}

 	md->nr_zones = disk->nr_zones;

 	return 0;
 }

 static int device_not_zone_append_capable(struct dm_target *ti,
 					  struct dm_dev *dev, sector_t start,
 					  sector_t len, void *data)
 {
 	return !bdev_is_zoned(dev->bdev);
 }

 static bool dm_table_supports_zone_append(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->emulate_zone_append)
 			return false;

 		if (!ti->type->iterate_devices ||
 		    ti->type->iterate_devices(ti, device_not_zone_append_capable, NULL))
 			return false;
 	}

 	return true;
 }

 struct dm_device_zone_count {
 	sector_t start;
 	sector_t len;
 	unsigned int total_nr_seq_zones;
 	unsigned int target_nr_seq_zones;
 };

 /*
  * Count the total number of and the number of mapped sequential zones of a
  * target zoned device.
  */
 static int dm_device_count_zones_cb(struct blk_zone *zone,
 				    unsigned int idx, void *data)
 {
 	struct dm_device_zone_count *zc = data;

 	if (zone->type != BLK_ZONE_TYPE_CONVENTIONAL) {
 		zc->total_nr_seq_zones++;
 		if (zone->start >= zc->start &&
 		    zone->start < zc->start + zc->len)
 			zc->target_nr_seq_zones++;
 	}

 	return 0;
 }

 static int dm_device_count_zones(struct dm_dev *dev,
 				 struct dm_device_zone_count *zc)
 {
 	int ret;

 	ret = blkdev_report_zones(dev->bdev, 0, BLK_ALL_ZONES,
 				  dm_device_count_zones_cb, zc);
 	if (ret < 0)
 		return ret;
 	if (!ret)
 		return -EIO;
 	return 0;
 }

 struct dm_zone_resource_limits {
 	unsigned int mapped_nr_seq_zones;
 	struct queue_limits *lim;
 	bool reliable_limits;
 };

 static int device_get_zone_resource_limits(struct dm_target *ti,
 					   struct dm_dev *dev, sector_t start,
 					   sector_t len, void *data)
 {
 	struct dm_zone_resource_limits *zlim = data;
 	struct gendisk *disk = dev->bdev->bd_disk;
 	unsigned int max_open_zones, max_active_zones;
 	int ret;
 	struct dm_device_zone_count zc = {
 		.start = start,
 		.len = len,
 	};

 	/*
 	 * If the target is not the whole device, the device zone resources may
 	 * be shared between different targets. Check this by counting the
 	 * number of mapped sequential zones: if this number is smaller than the
 	 * total number of sequential zones of the target device, then resource
 	 * sharing may happen and the zone limits will not be reliable.
 	 */
 	ret = dm_device_count_zones(dev, &zc);
 	if (ret) {
 		DMERR("Count %s zones failed %d", disk->disk_name, ret);
 		return ret;
 	}

 	/*
 	 * If the target does not map any sequential zones, then we do not need
 	 * any zone resource limits.
 	 */
 	if (!zc.target_nr_seq_zones)
 		return 0;

 	/*
 	 * If the target does not map all sequential zones, the limits
 	 * will not be reliable and we cannot use REQ_OP_ZONE_RESET_ALL.
 	 */
 	if (zc.target_nr_seq_zones < zc.total_nr_seq_zones) {
 		zlim->reliable_limits = false;
 		ti->zone_reset_all_supported = false;
 	}

 	/*
 	 * If the target maps less sequential zones than the limit values, then
 	 * we do not have limits for this target.
 	 */
 	max_active_zones = disk->queue->limits.max_active_zones;
 	if (max_active_zones >= zc.target_nr_seq_zones)
 		max_active_zones = 0;
 	zlim->lim->max_active_zones =
 		min_not_zero(max_active_zones, zlim->lim->max_active_zones);

 	max_open_zones = disk->queue->limits.max_open_zones;
 	if (max_open_zones >= zc.target_nr_seq_zones)
 		max_open_zones = 0;
 	zlim->lim->max_open_zones =
 		min_not_zero(max_open_zones, zlim->lim->max_open_zones);

 	/*
 	 * Also count the total number of sequential zones for the mapped
 	 * device so that when we are done inspecting all its targets, we are
 	 * able to check if the mapped device actually has any sequential zones.
 	 */
 	zlim->mapped_nr_seq_zones += zc.target_nr_seq_zones;

 	return 0;
 }

 int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
 		struct queue_limits *lim)
 {
 	struct mapped_device *md = t->md;
 	struct gendisk *disk = md->disk;
 	struct dm_zone_resource_limits zlim = {
 		.reliable_limits = true,
 		.lim = lim,
 	};

 	/*
 	 * Check if zone append is natively supported, and if not, set the
 	 * mapped device queue as needing zone append emulation.
 	 */
 	WARN_ON_ONCE(queue_is_mq(q));
 	if (dm_table_supports_zone_append(t)) {
 		clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
 	} else {
 		set_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
 		lim->max_hw_zone_append_sectors = 0;
 	}

 	/*
 	 * Determine the max open and max active zone limits for the mapped
 	 * device by inspecting the zone resource limits and the zones mapped
 	 * by each target.
 	 */
 	for (unsigned int i = 0; i < t->num_targets; i++) {
 		struct dm_target *ti = dm_table_get_target(t, i);

 		/*
 		 * Assume that the target can accept REQ_OP_ZONE_RESET_ALL.
 		 * device_get_zone_resource_limits() may adjust this if one of
 		 * the device used by the target does not have all its
 		 * sequential write required zones mapped.
 		 */
 		ti->zone_reset_all_supported = true;

 		if (!ti->type->iterate_devices ||
 		    ti->type->iterate_devices(ti,
 				device_get_zone_resource_limits, &zlim)) {
 			DMERR("Could not determine %s zone resource limits",
 			      disk->disk_name);
 			return -ENODEV;
 		}
 	}

 	/*
 	 * If we only have conventional zones mapped, expose the mapped device
 	 + as a regular device.
 	 */
 	if (!zlim.mapped_nr_seq_zones) {
 		lim->max_open_zones = 0;
 		lim->max_active_zones = 0;
 		lim->max_hw_zone_append_sectors = 0;
 		lim->zone_write_granularity = 0;
 		lim->chunk_sectors = 0;
 		lim->features &= ~BLK_FEAT_ZONED;
 		clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
 		md->nr_zones = 0;
 		disk->nr_zones = 0;
 		return 0;
 	}

 	/*
 	 * Warn once (when the capacity is not yet set) if the mapped device is
 	 * partially using zone resources of the target devices as that leads to
 	 * unreliable limits, i.e. if another mapped device uses the same
 	 * underlying devices, we cannot enforce zone limits to guarantee that
 	 * writing will not lead to errors. Note that we really should return
 	 * an error for such case but there is no easy way to find out if
 	 * another mapped device uses the same underlying zoned devices.
 	 */
 	if (!get_capacity(disk) && !zlim.reliable_limits)
 		DMWARN("%s zone resource limits may be unreliable",
 		       disk->disk_name);

 	if (lim->features & BLK_FEAT_ZONED &&
 	    !static_key_enabled(&zoned_enabled.key))
 		static_branch_enable(&zoned_enabled);
 	return 0;
 }

 /*
  * IO completion callback called from clone_endio().
  */
 void dm_zone_endio(struct dm_io *io, struct bio *clone)
 {
 	struct mapped_device *md = io->md;
 	struct gendisk *disk = md->disk;
 	struct bio *orig_bio = io->orig_bio;

 	/*
 	 * Get the offset within the zone of the written sector
 	 * and add that to the original bio sector position.
 	 */
 	if (clone->bi_status == BLK_STS_OK &&
 	    bio_op(clone) == REQ_OP_ZONE_APPEND) {
 		sector_t mask = bdev_zone_sectors(disk->part0) - 1;

 		orig_bio->bi_iter.bi_sector += clone->bi_iter.bi_sector & mask;
 	}

 	return;
 }

 static int dm_zone_need_reset_cb(struct blk_zone *zone, unsigned int idx,
 				 void *data)
 {
 	/*
 	 * For an all-zones reset, ignore conventional, empty, read-only
 	 * and offline zones.
 	 */
 	switch (zone->cond) {
 	case BLK_ZONE_COND_NOT_WP:
 	case BLK_ZONE_COND_EMPTY:
 	case BLK_ZONE_COND_READONLY:
 	case BLK_ZONE_COND_OFFLINE:
 		return 0;
 	default:
 		set_bit(idx, (unsigned long *)data);
 		return 0;
 	}
 }

 int dm_zone_get_reset_bitmap(struct mapped_device *md, struct dm_table *t,
 			     sector_t sector, unsigned int nr_zones,
 			     unsigned long *need_reset)
 {
 	int ret;

 	ret = dm_blk_do_report_zones(md, t, sector, nr_zones,
 				     dm_zone_need_reset_cb, need_reset);
 	if (ret != nr_zones) {
 		DMERR("Get %s zone reset bitmap failed\n",
 		      md->disk->disk_name);
 		return -EIO;
 	}

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2021 Western Digital Corporation or its affiliates.
	*/

	#include <linux/blkdev.h>
	#include <linux/mm.h>
	#include <linux/sched/mm.h>
	#include <linux/slab.h>
	#include <linux/bitmap.h>

	#include "dm-core.h"

	#define DM_MSG_PREFIX "zone"

	/*
	* For internal zone reports bypassing the top BIO submission path.
	*/
	static int dm_blk_do_report_zones(struct mapped_device md, struct dm_table t,
	sector_t sector, unsigned int nr_zones,
	report_zones_cb cb, void *data)
	{
	struct gendisk *disk = md->disk;
	int ret;
	struct dm_report_zones_args args = {
	.next_sector = sector,
	.orig_data = data,
	.orig_cb = cb,
	};

	do {
	struct dm_target *tgt;

	tgt = dm_table_find_target(t, args.next_sector);
	if (WARN_ON_ONCE(!tgt->type->report_zones))
	return -EIO;

	args.tgt = tgt;
	ret = tgt->type->report_zones(tgt, &args,
	nr_zones - args.zone_idx);
	if (ret < 0)
	return ret;
	} while (args.zone_idx < nr_zones &&
	args.next_sector < get_capacity(disk));

	return args.zone_idx;
	}

	/*
	* User facing dm device block device report zone operation. This calls the
	* report_zones operation for each target of a device table. This operation is
	* generally implemented by targets using dm_report_zones().
	*/
	int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
	unsigned int nr_zones, report_zones_cb cb, void *data)
	{
	struct mapped_device *md = disk->private_data;
	struct dm_table *map;
	int srcu_idx, ret;

	if (!md->zone_revalidate_map) {
	/* Regular user context */
	if (dm_suspended_md(md))
	return -EAGAIN;

	map = dm_get_live_table(md, &srcu_idx);
	if (!map)
	return -EIO;
	} else {
	/* Zone revalidation during __bind() */
	map = md->zone_revalidate_map;
	}

	ret = dm_blk_do_report_zones(md, map, sector, nr_zones, cb, data);

	if (!md->zone_revalidate_map)
	dm_put_live_table(md, srcu_idx);

	return ret;
	}

	static int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx,
	void *data)
	{
	struct dm_report_zones_args *args = data;
	sector_t sector_diff = args->tgt->begin - args->start;

	/*
	* Ignore zones beyond the target range.
	*/
	if (zone->start >= args->start + args->tgt->len)
	return 0;

	/*
	* Remap the start sector and write pointer position of the zone
	* to match its position in the target range.
	*/
	zone->start += sector_diff;
	if (zone->type != BLK_ZONE_TYPE_CONVENTIONAL) {
	if (zone->cond == BLK_ZONE_COND_FULL)
	zone->wp = zone->start + zone->len;
	else if (zone->cond == BLK_ZONE_COND_EMPTY)
	zone->wp = zone->start;
	else
	zone->wp += sector_diff;
	}

	args->next_sector = zone->start + zone->len;
	return args->orig_cb(zone, args->zone_idx++, args->orig_data);
	}

	/*
	* Helper for drivers of zoned targets to implement struct target_type
	* report_zones operation.
	*/
	int dm_report_zones(struct block_device *bdev, sector_t start, sector_t sector,
	struct dm_report_zones_args *args, unsigned int nr_zones)
	{
	/*
	* Set the target mapping start sector first so that
	* dm_report_zones_cb() can correctly remap zone information.
	*/
	args->start = start;

	return blkdev_report_zones(bdev, sector, nr_zones,
	dm_report_zones_cb, args);
	}
	EXPORT_SYMBOL_GPL(dm_report_zones);

	bool dm_is_zone_write(struct mapped_device md, struct bio bio)
	{
	struct request_queue *q = md->queue;

	if (!blk_queue_is_zoned(q))
	return false;

	switch (bio_op(bio)) {
	case REQ_OP_WRITE_ZEROES:
	case REQ_OP_WRITE:
	return !op_is_flush(bio->bi_opf) && bio_sectors(bio);
	default:
	return false;
	}
	}

	/*
	* Revalidate the zones of a mapped device to initialize resource necessary
	* for zone append emulation. Note that we cannot simply use the block layer
	* blk_revalidate_disk_zones() function here as the mapped device is suspended
	* (this is called from __bind() context).
	*/
	int dm_revalidate_zones(struct dm_table t, struct request_queue q)
	{
	struct mapped_device *md = t->md;
	struct gendisk *disk = md->disk;
	int ret;

	if (!get_capacity(disk))
	return 0;

	/* Revalidate only if something changed. */
	if (!disk->nr_zones \|\| disk->nr_zones != md->nr_zones) {
	DMINFO("%s using %s zone append",
	disk->disk_name,
	queue_emulates_zone_append(q) ? "emulated" : "native");
	md->nr_zones = 0;
	}

	if (md->nr_zones)
	return 0;

	/*
	* Our table is not live yet. So the call to dm_get_live_table()
	* in dm_blk_report_zones() will fail. Set a temporary pointer to
	* our table for dm_blk_report_zones() to use directly.
	*/
	md->zone_revalidate_map = t;
	ret = blk_revalidate_disk_zones(disk);
	md->zone_revalidate_map = NULL;

	if (ret) {
	DMERR("Revalidate zones failed %d", ret);
	return ret;
	}

	md->nr_zones = disk->nr_zones;

	return 0;
	}

	static int device_not_zone_append_capable(struct dm_target *ti,
	struct dm_dev *dev, sector_t start,
	sector_t len, void *data)
	{
	return !bdev_is_zoned(dev->bdev);
	}

	static bool dm_table_supports_zone_append(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->emulate_zone_append)
	return false;

	if (!ti->type->iterate_devices \|\|
	ti->type->iterate_devices(ti, device_not_zone_append_capable, NULL))
	return false;
	}

	return true;
	}

	struct dm_device_zone_count {
	sector_t start;
	sector_t len;
	unsigned int total_nr_seq_zones;
	unsigned int target_nr_seq_zones;
	};

	/*
	* Count the total number of and the number of mapped sequential zones of a
	* target zoned device.
	*/
	static int dm_device_count_zones_cb(struct blk_zone *zone,
	unsigned int idx, void *data)
	{
	struct dm_device_zone_count *zc = data;

	if (zone->type != BLK_ZONE_TYPE_CONVENTIONAL) {
	zc->total_nr_seq_zones++;
	if (zone->start >= zc->start &&
	zone->start < zc->start + zc->len)
	zc->target_nr_seq_zones++;
	}

	return 0;
	}

	static int dm_device_count_zones(struct dm_dev *dev,
	struct dm_device_zone_count *zc)
	{
	int ret;

	ret = blkdev_report_zones(dev->bdev, 0, BLK_ALL_ZONES,
	dm_device_count_zones_cb, zc);
	if (ret < 0)
	return ret;
	if (!ret)
	return -EIO;
	return 0;
	}

	struct dm_zone_resource_limits {
	unsigned int mapped_nr_seq_zones;
	struct queue_limits *lim;
	bool reliable_limits;
	};

	static int device_get_zone_resource_limits(struct dm_target *ti,
	struct dm_dev *dev, sector_t start,
	sector_t len, void *data)
	{
	struct dm_zone_resource_limits *zlim = data;
	struct gendisk *disk = dev->bdev->bd_disk;
	unsigned int max_open_zones, max_active_zones;
	int ret;
	struct dm_device_zone_count zc = {
	.start = start,
	.len = len,
	};

	/*
	* If the target is not the whole device, the device zone resources may
	* be shared between different targets. Check this by counting the
	* number of mapped sequential zones: if this number is smaller than the
	* total number of sequential zones of the target device, then resource
	* sharing may happen and the zone limits will not be reliable.
	*/
	ret = dm_device_count_zones(dev, &zc);
	if (ret) {
	DMERR("Count %s zones failed %d", disk->disk_name, ret);
	return ret;
	}

	/*
	* If the target does not map any sequential zones, then we do not need
	* any zone resource limits.
	*/
	if (!zc.target_nr_seq_zones)
	return 0;

	/*
	* If the target does not map all sequential zones, the limits
	* will not be reliable and we cannot use REQ_OP_ZONE_RESET_ALL.
	*/
	if (zc.target_nr_seq_zones < zc.total_nr_seq_zones) {
	zlim->reliable_limits = false;
	ti->zone_reset_all_supported = false;
	}

	/*
	* If the target maps less sequential zones than the limit values, then
	* we do not have limits for this target.
	*/
	max_active_zones = disk->queue->limits.max_active_zones;
	if (max_active_zones >= zc.target_nr_seq_zones)
	max_active_zones = 0;
	zlim->lim->max_active_zones =
	min_not_zero(max_active_zones, zlim->lim->max_active_zones);

	max_open_zones = disk->queue->limits.max_open_zones;
	if (max_open_zones >= zc.target_nr_seq_zones)
	max_open_zones = 0;
	zlim->lim->max_open_zones =
	min_not_zero(max_open_zones, zlim->lim->max_open_zones);

	/*
	* Also count the total number of sequential zones for the mapped
	* device so that when we are done inspecting all its targets, we are
	* able to check if the mapped device actually has any sequential zones.
	*/
	zlim->mapped_nr_seq_zones += zc.target_nr_seq_zones;

	return 0;
	}

	int dm_set_zones_restrictions(struct dm_table t, struct request_queue q,
	struct queue_limits *lim)
	{
	struct mapped_device *md = t->md;
	struct gendisk *disk = md->disk;
	struct dm_zone_resource_limits zlim = {
	.reliable_limits = true,
	.lim = lim,
	};

	/*
	* Check if zone append is natively supported, and if not, set the
	* mapped device queue as needing zone append emulation.
	*/
	WARN_ON_ONCE(queue_is_mq(q));
	if (dm_table_supports_zone_append(t)) {
	clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
	} else {
	set_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
	lim->max_hw_zone_append_sectors = 0;
	}

	/*
	* Determine the max open and max active zone limits for the mapped
	* device by inspecting the zone resource limits and the zones mapped
	* by each target.
	*/
	for (unsigned int i = 0; i < t->num_targets; i++) {
	struct dm_target *ti = dm_table_get_target(t, i);

	/*
	* Assume that the target can accept REQ_OP_ZONE_RESET_ALL.
	* device_get_zone_resource_limits() may adjust this if one of
	* the device used by the target does not have all its
	* sequential write required zones mapped.
	*/
	ti->zone_reset_all_supported = true;

	if (!ti->type->iterate_devices \|\|
	ti->type->iterate_devices(ti,
	device_get_zone_resource_limits, &zlim)) {
	DMERR("Could not determine %s zone resource limits",
	disk->disk_name);
	return -ENODEV;
	}
	}

	/*
	* If we only have conventional zones mapped, expose the mapped device
	+ as a regular device.
	*/
	if (!zlim.mapped_nr_seq_zones) {
	lim->max_open_zones = 0;
	lim->max_active_zones = 0;
	lim->max_hw_zone_append_sectors = 0;
	lim->zone_write_granularity = 0;
	lim->chunk_sectors = 0;
	lim->features &= ~BLK_FEAT_ZONED;
	clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
	md->nr_zones = 0;
	disk->nr_zones = 0;
	return 0;
	}

	/*
	* Warn once (when the capacity is not yet set) if the mapped device is
	* partially using zone resources of the target devices as that leads to
	* unreliable limits, i.e. if another mapped device uses the same
	* underlying devices, we cannot enforce zone limits to guarantee that
	* writing will not lead to errors. Note that we really should return
	* an error for such case but there is no easy way to find out if
	* another mapped device uses the same underlying zoned devices.
	*/
	if (!get_capacity(disk) && !zlim.reliable_limits)
	DMWARN("%s zone resource limits may be unreliable",
	disk->disk_name);

	if (lim->features & BLK_FEAT_ZONED &&
	!static_key_enabled(&zoned_enabled.key))
	static_branch_enable(&zoned_enabled);
	return 0;
	}

	/*
	* IO completion callback called from clone_endio().
	*/
	void dm_zone_endio(struct dm_io io, struct bio clone)
	{
	struct mapped_device *md = io->md;
	struct gendisk *disk = md->disk;
	struct bio *orig_bio = io->orig_bio;

	/*
	* Get the offset within the zone of the written sector
	* and add that to the original bio sector position.
	*/
	if (clone->bi_status == BLK_STS_OK &&
	bio_op(clone) == REQ_OP_ZONE_APPEND) {
	sector_t mask = bdev_zone_sectors(disk->part0) - 1;

	orig_bio->bi_iter.bi_sector += clone->bi_iter.bi_sector & mask;
	}

	return;
	}

	static int dm_zone_need_reset_cb(struct blk_zone *zone, unsigned int idx,
	void *data)
	{
	/*
	* For an all-zones reset, ignore conventional, empty, read-only
	* and offline zones.
	*/
	switch (zone->cond) {
	case BLK_ZONE_COND_NOT_WP:
	case BLK_ZONE_COND_EMPTY:
	case BLK_ZONE_COND_READONLY:
	case BLK_ZONE_COND_OFFLINE:
	return 0;
	default:
	set_bit(idx, (unsigned long *)data);
	return 0;
	}
	}

	int dm_zone_get_reset_bitmap(struct mapped_device md, struct dm_table t,
	sector_t sector, unsigned int nr_zones,
	unsigned long *need_reset)
	{
	int ret;

	ret = dm_blk_do_report_zones(md, t, sector, nr_zones,
	dm_zone_need_reset_cb, need_reset);
	if (ret != nr_zones) {
	DMERR("Get %s zone reset bitmap failed\n",
	md->disk->disk_name);
	return -EIO;
	}

	return 0;
	}