drivers/md/dm-zoned-reclaim.c - arm/linux - Git at Google

 /*
  * 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 reclaim"

 struct dmz_reclaim {
 	struct dmz_metadata     *metadata;
 	struct dmz_dev		*dev;

 	struct delayed_work	work;
 	struct workqueue_struct *wq;

 	struct dm_kcopyd_client	*kc;
 	struct dm_kcopyd_throttle kc_throttle;
 	int			kc_err;

 	unsigned long		flags;

 	/* Last target access time */
 	unsigned long		atime;
 };

 /*
  * Reclaim state flags.
  */
 enum {
 	DMZ_RECLAIM_KCOPY,
 };

 /*
  * Number of seconds of target BIO inactivity to consider the target idle.
  */
 #define DMZ_IDLE_PERIOD		(10UL * HZ)

 /*
  * Percentage of unmapped (free) random zones below which reclaim starts
  * even if the target is busy.
  */
 #define DMZ_RECLAIM_LOW_UNMAP_RND	30

 /*
  * Percentage of unmapped (free) random zones above which reclaim will
  * stop if the target is busy.
  */
 #define DMZ_RECLAIM_HIGH_UNMAP_RND	50

 /*
  * Align a sequential zone write pointer to chunk_block.
  */
 static int dmz_reclaim_align_wp(struct dmz_reclaim *zrc, struct dm_zone *zone,
 				sector_t block)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
 	sector_t wp_block = zone->wp_block;
 	unsigned int nr_blocks;
 	int ret;

 	if (wp_block == block)
 		return 0;

 	if (wp_block > block)
 		return -EIO;

 	/*
 	 * Zeroout the space between the write
 	 * pointer and the requested position.
 	 */
 	nr_blocks = block - wp_block;
 	ret = blkdev_issue_zeroout(zrc->dev->bdev,
 				   dmz_start_sect(zmd, zone) + dmz_blk2sect(wp_block),
 				   dmz_blk2sect(nr_blocks), GFP_NOIO, 0);
 	if (ret) {
 		dmz_dev_err(zrc->dev,
 			    "Align zone %u wp %llu to %llu (wp+%u) blocks failed %d",
 			    dmz_id(zmd, zone), (unsigned long long)wp_block,
 			    (unsigned long long)block, nr_blocks, ret);
 		return ret;
 	}

 	zone->wp_block = block;

 	return 0;
 }

 /*
  * dm_kcopyd_copy end notification.
  */
 static void dmz_reclaim_kcopy_end(int read_err, unsigned long write_err,
 				  void *context)
 {
 	struct dmz_reclaim *zrc = context;

 	if (read_err || write_err)
 		zrc->kc_err = -EIO;
 	else
 		zrc->kc_err = 0;

 	clear_bit_unlock(DMZ_RECLAIM_KCOPY, &zrc->flags);
 	smp_mb__after_atomic();
 	wake_up_bit(&zrc->flags, DMZ_RECLAIM_KCOPY);
 }

 /*
  * Copy valid blocks of src_zone into dst_zone.
  */
 static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
 			    struct dm_zone *src_zone, struct dm_zone *dst_zone)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
 	struct dmz_dev *dev = zrc->dev;
 	struct dm_io_region src, dst;
 	sector_t block = 0, end_block;
 	sector_t nr_blocks;
 	sector_t src_zone_block;
 	sector_t dst_zone_block;
 	unsigned long flags = 0;
 	int ret;

 	if (dmz_is_seq(src_zone))
 		end_block = src_zone->wp_block;
 	else
 		end_block = dev->zone_nr_blocks;
 	src_zone_block = dmz_start_block(zmd, src_zone);
 	dst_zone_block = dmz_start_block(zmd, dst_zone);

 	if (dmz_is_seq(dst_zone))
 		set_bit(DM_KCOPYD_WRITE_SEQ, &flags);

 	while (block < end_block) {
 		/* Get a valid region from the source zone */
 		ret = dmz_first_valid_block(zmd, src_zone, &block);
 		if (ret <= 0)
 			return ret;
 		nr_blocks = ret;

 		/*
 		 * If we are writing in a sequential zone, we must make sure
 		 * that writes are sequential. So Zeroout any eventual hole
 		 * between writes.
 		 */
 		if (dmz_is_seq(dst_zone)) {
 			ret = dmz_reclaim_align_wp(zrc, dst_zone, block);
 			if (ret)
 				return ret;
 		}

 		src.bdev = dev->bdev;
 		src.sector = dmz_blk2sect(src_zone_block + block);
 		src.count = dmz_blk2sect(nr_blocks);

 		dst.bdev = dev->bdev;
 		dst.sector = dmz_blk2sect(dst_zone_block + block);
 		dst.count = src.count;

 		/* Copy the valid region */
 		set_bit(DMZ_RECLAIM_KCOPY, &zrc->flags);
 		ret = dm_kcopyd_copy(zrc->kc, &src, 1, &dst, flags,
 				     dmz_reclaim_kcopy_end, zrc);
 		if (ret)
 			return ret;

 		/* Wait for copy to complete */
 		wait_on_bit_io(&zrc->flags, DMZ_RECLAIM_KCOPY,
 			       TASK_UNINTERRUPTIBLE);
 		if (zrc->kc_err)
 			return zrc->kc_err;

 		block += nr_blocks;
 		if (dmz_is_seq(dst_zone))
 			dst_zone->wp_block = block;
 	}

 	return 0;
 }

 /*
  * Move valid blocks of dzone buffer zone into dzone (after its write pointer)
  * and free the buffer zone.
  */
 static int dmz_reclaim_buf(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 {
 	struct dm_zone *bzone = dzone->bzone;
 	sector_t chunk_block = dzone->wp_block;
 	struct dmz_metadata *zmd = zrc->metadata;
 	int ret;

 	dmz_dev_debug(zrc->dev,
 		      "Chunk %u, move buf zone %u (weight %u) to data zone %u (weight %u)",
 		      dzone->chunk, dmz_id(zmd, bzone), dmz_weight(bzone),
 		      dmz_id(zmd, dzone), dmz_weight(dzone));

 	/* Flush data zone into the buffer zone */
 	ret = dmz_reclaim_copy(zrc, bzone, dzone);
 	if (ret < 0)
 		return ret;

 	dmz_lock_flush(zmd);

 	/* Validate copied blocks */
 	ret = dmz_merge_valid_blocks(zmd, bzone, dzone, chunk_block);
 	if (ret == 0) {
 		/* Free the buffer zone */
 		dmz_invalidate_blocks(zmd, bzone, 0, zrc->dev->zone_nr_blocks);
 		dmz_lock_map(zmd);
 		dmz_unmap_zone(zmd, bzone);
 		dmz_unlock_zone_reclaim(dzone);
 		dmz_free_zone(zmd, bzone);
 		dmz_unlock_map(zmd);
 	}

 	dmz_unlock_flush(zmd);

 	return 0;
 }

 /*
  * Merge valid blocks of dzone into its buffer zone and free dzone.
  */
 static int dmz_reclaim_seq_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 {
 	unsigned int chunk = dzone->chunk;
 	struct dm_zone *bzone = dzone->bzone;
 	struct dmz_metadata *zmd = zrc->metadata;
 	int ret = 0;

 	dmz_dev_debug(zrc->dev,
 		      "Chunk %u, move data zone %u (weight %u) to buf zone %u (weight %u)",
 		      chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
 		      dmz_id(zmd, bzone), dmz_weight(bzone));

 	/* Flush data zone into the buffer zone */
 	ret = dmz_reclaim_copy(zrc, dzone, bzone);
 	if (ret < 0)
 		return ret;

 	dmz_lock_flush(zmd);

 	/* Validate copied blocks */
 	ret = dmz_merge_valid_blocks(zmd, dzone, bzone, 0);
 	if (ret == 0) {
 		/*
 		 * Free the data zone and remap the chunk to
 		 * the buffer zone.
 		 */
 		dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
 		dmz_lock_map(zmd);
 		dmz_unmap_zone(zmd, bzone);
 		dmz_unmap_zone(zmd, dzone);
 		dmz_unlock_zone_reclaim(dzone);
 		dmz_free_zone(zmd, dzone);
 		dmz_map_zone(zmd, bzone, chunk);
 		dmz_unlock_map(zmd);
 	}

 	dmz_unlock_flush(zmd);

 	return 0;
 }

 /*
  * Move valid blocks of the random data zone dzone into a free sequential zone.
  * Once blocks are moved, remap the zone chunk to the sequential zone.
  */
 static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 {
 	unsigned int chunk = dzone->chunk;
 	struct dm_zone *szone = NULL;
 	struct dmz_metadata *zmd = zrc->metadata;
 	int ret;

 	/* Get a free sequential zone */
 	dmz_lock_map(zmd);
 	szone = dmz_alloc_zone(zmd, DMZ_ALLOC_RECLAIM);
 	dmz_unlock_map(zmd);
 	if (!szone)
 		return -ENOSPC;

 	dmz_dev_debug(zrc->dev,
 		      "Chunk %u, move rnd zone %u (weight %u) to seq zone %u",
 		      chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
 		      dmz_id(zmd, szone));

 	/* Flush the random data zone into the sequential zone */
 	ret = dmz_reclaim_copy(zrc, dzone, szone);

 	dmz_lock_flush(zmd);

 	if (ret == 0) {
 		/* Validate copied blocks */
 		ret = dmz_copy_valid_blocks(zmd, dzone, szone);
 	}
 	if (ret) {
 		/* Free the sequential zone */
 		dmz_lock_map(zmd);
 		dmz_free_zone(zmd, szone);
 		dmz_unlock_map(zmd);
 	} else {
 		/* Free the data zone and remap the chunk */
 		dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
 		dmz_lock_map(zmd);
 		dmz_unmap_zone(zmd, dzone);
 		dmz_unlock_zone_reclaim(dzone);
 		dmz_free_zone(zmd, dzone);
 		dmz_map_zone(zmd, szone, chunk);
 		dmz_unlock_map(zmd);
 	}

 	dmz_unlock_flush(zmd);

 	return 0;
 }

 /*
  * Reclaim an empty zone.
  */
 static void dmz_reclaim_empty(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 {
 	struct dmz_metadata *zmd = zrc->metadata;

 	dmz_lock_flush(zmd);
 	dmz_lock_map(zmd);
 	dmz_unmap_zone(zmd, dzone);
 	dmz_unlock_zone_reclaim(dzone);
 	dmz_free_zone(zmd, dzone);
 	dmz_unlock_map(zmd);
 	dmz_unlock_flush(zmd);
 }

 /*
  * Find a candidate zone for reclaim and process it.
  */
 static void dmz_reclaim(struct dmz_reclaim *zrc)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
 	struct dm_zone *dzone;
 	struct dm_zone *rzone;
 	unsigned long start;
 	int ret;

 	/* Get a data zone */
 	dzone = dmz_get_zone_for_reclaim(zmd);
 	if (!dzone)
 		return;

 	start = jiffies;

 	if (dmz_is_rnd(dzone)) {
 		if (!dmz_weight(dzone)) {
 			/* Empty zone */
 			dmz_reclaim_empty(zrc, dzone);
 			ret = 0;
 		} else {
 			/*
 			 * Reclaim the random data zone by moving its
 			 * valid data blocks to a free sequential zone.
 			 */
 			ret = dmz_reclaim_rnd_data(zrc, dzone);
 		}
 		rzone = dzone;

 	} else {
 		struct dm_zone *bzone = dzone->bzone;
 		sector_t chunk_block = 0;

 		ret = dmz_first_valid_block(zmd, bzone, &chunk_block);
 		if (ret < 0)
 			goto out;

 		if (ret == 0 || chunk_block >= dzone->wp_block) {
 			/*
 			 * The buffer zone is empty or its valid blocks are
 			 * after the data zone write pointer.
 			 */
 			ret = dmz_reclaim_buf(zrc, dzone);
 			rzone = bzone;
 		} else {
 			/*
 			 * Reclaim the data zone by merging it into the
 			 * buffer zone so that the buffer zone itself can
 			 * be later reclaimed.
 			 */
 			ret = dmz_reclaim_seq_data(zrc, dzone);
 			rzone = dzone;
 		}
 	}
 out:
 	if (ret) {
 		dmz_unlock_zone_reclaim(dzone);
 		return;
 	}

 	(void) dmz_flush_metadata(zrc->metadata);

 	dmz_dev_debug(zrc->dev, "Reclaimed zone %u in %u ms",
 		      dmz_id(zmd, rzone), jiffies_to_msecs(jiffies - start));
 }

 /*
  * Test if the target device is idle.
  */
 static inline int dmz_target_idle(struct dmz_reclaim *zrc)
 {
 	return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
 }

 /*
  * Test if reclaim is necessary.
  */
 static bool dmz_should_reclaim(struct dmz_reclaim *zrc)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
 	unsigned int nr_rnd = dmz_nr_rnd_zones(zmd);
 	unsigned int nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
 	unsigned int p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;

 	/* Reclaim when idle */
 	if (dmz_target_idle(zrc) && nr_unmap_rnd < nr_rnd)
 		return true;

 	/* If there are still plenty of random zones, do not reclaim */
 	if (p_unmap_rnd >= DMZ_RECLAIM_HIGH_UNMAP_RND)
 		return false;

 	/*
 	 * If the percentage of unmappped random zones is low,
 	 * reclaim even if the target is busy.
 	 */
 	return p_unmap_rnd <= DMZ_RECLAIM_LOW_UNMAP_RND;
 }

 /*
  * Reclaim work function.
  */
 static void dmz_reclaim_work(struct work_struct *work)
 {
 	struct dmz_reclaim *zrc = container_of(work, struct dmz_reclaim, work.work);
 	struct dmz_metadata *zmd = zrc->metadata;
 	unsigned int nr_rnd, nr_unmap_rnd;
 	unsigned int p_unmap_rnd;

 	if (!dmz_should_reclaim(zrc)) {
 		mod_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
 		return;
 	}

 	/*
 	 * We need to start reclaiming random zones: set up zone copy
 	 * throttling to either go fast if we are very low on random zones
 	 * and slower if there are still some free random zones to avoid
 	 * as much as possible to negatively impact the user workload.
 	 */
 	nr_rnd = dmz_nr_rnd_zones(zmd);
 	nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
 	p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
 	if (dmz_target_idle(zrc) || p_unmap_rnd < DMZ_RECLAIM_LOW_UNMAP_RND / 2) {
 		/* Idle or very low percentage: go fast */
 		zrc->kc_throttle.throttle = 100;
 	} else {
 		/* Busy but we still have some random zone: throttle */
 		zrc->kc_throttle.throttle = min(75U, 100U - p_unmap_rnd / 2);
 	}

 	dmz_dev_debug(zrc->dev,
 		      "Reclaim (%u): %s, %u%% free rnd zones (%u/%u)",
 		      zrc->kc_throttle.throttle,
 		      (dmz_target_idle(zrc) ? "Idle" : "Busy"),
 		      p_unmap_rnd, nr_unmap_rnd, nr_rnd);

 	dmz_reclaim(zrc);

 	dmz_schedule_reclaim(zrc);
 }

 /*
  * Initialize reclaim.
  */
 int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
 		    struct dmz_reclaim **reclaim)
 {
 	struct dmz_reclaim *zrc;
 	int ret;

 	zrc = kzalloc(sizeof(struct dmz_reclaim), GFP_KERNEL);
 	if (!zrc)
 		return -ENOMEM;

 	zrc->dev = dev;
 	zrc->metadata = zmd;
 	zrc->atime = jiffies;

 	/* Reclaim kcopyd client */
 	zrc->kc = dm_kcopyd_client_create(&zrc->kc_throttle);
 	if (IS_ERR(zrc->kc)) {
 		ret = PTR_ERR(zrc->kc);
 		zrc->kc = NULL;
 		goto err;
 	}

 	/* Reclaim work */
 	INIT_DELAYED_WORK(&zrc->work, dmz_reclaim_work);
 	zrc->wq = alloc_ordered_workqueue("dmz_rwq_%s", WQ_MEM_RECLAIM,
 					  dev->name);
 	if (!zrc->wq) {
 		ret = -ENOMEM;
 		goto err;
 	}

 	*reclaim = zrc;
 	queue_delayed_work(zrc->wq, &zrc->work, 0);

 	return 0;
 err:
 	if (zrc->kc)
 		dm_kcopyd_client_destroy(zrc->kc);
 	kfree(zrc);

 	return ret;
 }

 /*
  * Terminate reclaim.
  */
 void dmz_dtr_reclaim(struct dmz_reclaim *zrc)
 {
 	cancel_delayed_work_sync(&zrc->work);
 	destroy_workqueue(zrc->wq);
 	dm_kcopyd_client_destroy(zrc->kc);
 	kfree(zrc);
 }

 /*
  * Suspend reclaim.
  */
 void dmz_suspend_reclaim(struct dmz_reclaim *zrc)
 {
 	cancel_delayed_work_sync(&zrc->work);
 }

 /*
  * Resume reclaim.
  */
 void dmz_resume_reclaim(struct dmz_reclaim *zrc)
 {
 	queue_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
 }

 /*
  * BIO accounting.
  */
 void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc)
 {
 	zrc->atime = jiffies;
 }

 /*
  * Start reclaim if necessary.
  */
 void dmz_schedule_reclaim(struct dmz_reclaim *zrc)
 {
 	if (dmz_should_reclaim(zrc))
 		mod_delayed_work(zrc->wq, &zrc->work, 0);
 }
	/*
	* 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 reclaim"

	struct dmz_reclaim {
	struct dmz_metadata *metadata;
	struct dmz_dev *dev;

	struct delayed_work work;
	struct workqueue_struct *wq;

	struct dm_kcopyd_client *kc;
	struct dm_kcopyd_throttle kc_throttle;
	int kc_err;

	unsigned long flags;

	/* Last target access time */
	unsigned long atime;
	};

	/*
	* Reclaim state flags.
	*/
	enum {
	DMZ_RECLAIM_KCOPY,
	};

	/*
	* Number of seconds of target BIO inactivity to consider the target idle.
	*/
	#define DMZ_IDLE_PERIOD (10UL * HZ)

	/*
	* Percentage of unmapped (free) random zones below which reclaim starts
	* even if the target is busy.
	*/
	#define DMZ_RECLAIM_LOW_UNMAP_RND 30

	/*
	* Percentage of unmapped (free) random zones above which reclaim will
	* stop if the target is busy.
	*/
	#define DMZ_RECLAIM_HIGH_UNMAP_RND 50

	/*
	* Align a sequential zone write pointer to chunk_block.
	*/
	static int dmz_reclaim_align_wp(struct dmz_reclaim zrc, struct dm_zone zone,
	sector_t block)
	{
	struct dmz_metadata *zmd = zrc->metadata;
	sector_t wp_block = zone->wp_block;
	unsigned int nr_blocks;
	int ret;

	if (wp_block == block)
	return 0;

	if (wp_block > block)
	return -EIO;

	/*
	* Zeroout the space between the write
	* pointer and the requested position.
	*/
	nr_blocks = block - wp_block;
	ret = blkdev_issue_zeroout(zrc->dev->bdev,
	dmz_start_sect(zmd, zone) + dmz_blk2sect(wp_block),
	dmz_blk2sect(nr_blocks), GFP_NOIO, 0);
	if (ret) {
	dmz_dev_err(zrc->dev,
	"Align zone %u wp %llu to %llu (wp+%u) blocks failed %d",
	dmz_id(zmd, zone), (unsigned long long)wp_block,
	(unsigned long long)block, nr_blocks, ret);
	return ret;
	}

	zone->wp_block = block;

	return 0;
	}

	/*
	* dm_kcopyd_copy end notification.
	*/
	static void dmz_reclaim_kcopy_end(int read_err, unsigned long write_err,
	void *context)
	{
	struct dmz_reclaim *zrc = context;

	if (read_err \|\| write_err)
	zrc->kc_err = -EIO;
	else
	zrc->kc_err = 0;

	clear_bit_unlock(DMZ_RECLAIM_KCOPY, &zrc->flags);
	smp_mb__after_atomic();
	wake_up_bit(&zrc->flags, DMZ_RECLAIM_KCOPY);
	}

	/*
	* Copy valid blocks of src_zone into dst_zone.
	*/
	static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
	struct dm_zone src_zone, struct dm_zone dst_zone)
	{
	struct dmz_metadata *zmd = zrc->metadata;
	struct dmz_dev *dev = zrc->dev;
	struct dm_io_region src, dst;
	sector_t block = 0, end_block;
	sector_t nr_blocks;
	sector_t src_zone_block;
	sector_t dst_zone_block;
	unsigned long flags = 0;
	int ret;

	if (dmz_is_seq(src_zone))
	end_block = src_zone->wp_block;
	else
	end_block = dev->zone_nr_blocks;
	src_zone_block = dmz_start_block(zmd, src_zone);
	dst_zone_block = dmz_start_block(zmd, dst_zone);

	if (dmz_is_seq(dst_zone))
	set_bit(DM_KCOPYD_WRITE_SEQ, &flags);

	while (block < end_block) {
	/* Get a valid region from the source zone */
	ret = dmz_first_valid_block(zmd, src_zone, &block);
	if (ret <= 0)
	return ret;
	nr_blocks = ret;

	/*
	* If we are writing in a sequential zone, we must make sure
	* that writes are sequential. So Zeroout any eventual hole
	* between writes.
	*/
	if (dmz_is_seq(dst_zone)) {
	ret = dmz_reclaim_align_wp(zrc, dst_zone, block);
	if (ret)
	return ret;
	}

	src.bdev = dev->bdev;
	src.sector = dmz_blk2sect(src_zone_block + block);
	src.count = dmz_blk2sect(nr_blocks);

	dst.bdev = dev->bdev;
	dst.sector = dmz_blk2sect(dst_zone_block + block);
	dst.count = src.count;

	/* Copy the valid region */
	set_bit(DMZ_RECLAIM_KCOPY, &zrc->flags);
	ret = dm_kcopyd_copy(zrc->kc, &src, 1, &dst, flags,
	dmz_reclaim_kcopy_end, zrc);
	if (ret)
	return ret;

	/* Wait for copy to complete */
	wait_on_bit_io(&zrc->flags, DMZ_RECLAIM_KCOPY,
	TASK_UNINTERRUPTIBLE);
	if (zrc->kc_err)
	return zrc->kc_err;

	block += nr_blocks;
	if (dmz_is_seq(dst_zone))
	dst_zone->wp_block = block;
	}

	return 0;
	}

	/*
	* Move valid blocks of dzone buffer zone into dzone (after its write pointer)
	* and free the buffer zone.
	*/
	static int dmz_reclaim_buf(struct dmz_reclaim zrc, struct dm_zone dzone)
	{
	struct dm_zone *bzone = dzone->bzone;
	sector_t chunk_block = dzone->wp_block;
	struct dmz_metadata *zmd = zrc->metadata;
	int ret;

	dmz_dev_debug(zrc->dev,
	"Chunk %u, move buf zone %u (weight %u) to data zone %u (weight %u)",
	dzone->chunk, dmz_id(zmd, bzone), dmz_weight(bzone),
	dmz_id(zmd, dzone), dmz_weight(dzone));

	/* Flush data zone into the buffer zone */
	ret = dmz_reclaim_copy(zrc, bzone, dzone);
	if (ret < 0)
	return ret;

	dmz_lock_flush(zmd);

	/* Validate copied blocks */
	ret = dmz_merge_valid_blocks(zmd, bzone, dzone, chunk_block);
	if (ret == 0) {
	/* Free the buffer zone */
	dmz_invalidate_blocks(zmd, bzone, 0, zrc->dev->zone_nr_blocks);
	dmz_lock_map(zmd);
	dmz_unmap_zone(zmd, bzone);
	dmz_unlock_zone_reclaim(dzone);
	dmz_free_zone(zmd, bzone);
	dmz_unlock_map(zmd);
	}

	dmz_unlock_flush(zmd);

	return 0;
	}

	/*
	* Merge valid blocks of dzone into its buffer zone and free dzone.
	*/
	static int dmz_reclaim_seq_data(struct dmz_reclaim zrc, struct dm_zone dzone)
	{
	unsigned int chunk = dzone->chunk;
	struct dm_zone *bzone = dzone->bzone;
	struct dmz_metadata *zmd = zrc->metadata;
	int ret = 0;

	dmz_dev_debug(zrc->dev,
	"Chunk %u, move data zone %u (weight %u) to buf zone %u (weight %u)",
	chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
	dmz_id(zmd, bzone), dmz_weight(bzone));

	/* Flush data zone into the buffer zone */
	ret = dmz_reclaim_copy(zrc, dzone, bzone);
	if (ret < 0)
	return ret;

	dmz_lock_flush(zmd);

	/* Validate copied blocks */
	ret = dmz_merge_valid_blocks(zmd, dzone, bzone, 0);
	if (ret == 0) {
	/*
	* Free the data zone and remap the chunk to
	* the buffer zone.
	*/
	dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
	dmz_lock_map(zmd);
	dmz_unmap_zone(zmd, bzone);
	dmz_unmap_zone(zmd, dzone);
	dmz_unlock_zone_reclaim(dzone);
	dmz_free_zone(zmd, dzone);
	dmz_map_zone(zmd, bzone, chunk);
	dmz_unlock_map(zmd);
	}

	dmz_unlock_flush(zmd);

	return 0;
	}

	/*
	* Move valid blocks of the random data zone dzone into a free sequential zone.
	* Once blocks are moved, remap the zone chunk to the sequential zone.
	*/
	static int dmz_reclaim_rnd_data(struct dmz_reclaim zrc, struct dm_zone dzone)
	{
	unsigned int chunk = dzone->chunk;
	struct dm_zone *szone = NULL;
	struct dmz_metadata *zmd = zrc->metadata;
	int ret;

	/* Get a free sequential zone */
	dmz_lock_map(zmd);
	szone = dmz_alloc_zone(zmd, DMZ_ALLOC_RECLAIM);
	dmz_unlock_map(zmd);
	if (!szone)
	return -ENOSPC;

	dmz_dev_debug(zrc->dev,
	"Chunk %u, move rnd zone %u (weight %u) to seq zone %u",
	chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
	dmz_id(zmd, szone));

	/* Flush the random data zone into the sequential zone */
	ret = dmz_reclaim_copy(zrc, dzone, szone);

	dmz_lock_flush(zmd);

	if (ret == 0) {
	/* Validate copied blocks */
	ret = dmz_copy_valid_blocks(zmd, dzone, szone);
	}
	if (ret) {
	/* Free the sequential zone */
	dmz_lock_map(zmd);
	dmz_free_zone(zmd, szone);
	dmz_unlock_map(zmd);
	} else {
	/* Free the data zone and remap the chunk */
	dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
	dmz_lock_map(zmd);
	dmz_unmap_zone(zmd, dzone);
	dmz_unlock_zone_reclaim(dzone);
	dmz_free_zone(zmd, dzone);
	dmz_map_zone(zmd, szone, chunk);
	dmz_unlock_map(zmd);
	}

	dmz_unlock_flush(zmd);

	return 0;
	}

	/*
	* Reclaim an empty zone.
	*/
	static void dmz_reclaim_empty(struct dmz_reclaim zrc, struct dm_zone dzone)
	{
	struct dmz_metadata *zmd = zrc->metadata;

	dmz_lock_flush(zmd);
	dmz_lock_map(zmd);
	dmz_unmap_zone(zmd, dzone);
	dmz_unlock_zone_reclaim(dzone);
	dmz_free_zone(zmd, dzone);
	dmz_unlock_map(zmd);
	dmz_unlock_flush(zmd);
	}

	/*
	* Find a candidate zone for reclaim and process it.
	*/
	static void dmz_reclaim(struct dmz_reclaim *zrc)
	{
	struct dmz_metadata *zmd = zrc->metadata;
	struct dm_zone *dzone;
	struct dm_zone *rzone;
	unsigned long start;
	int ret;

	/* Get a data zone */
	dzone = dmz_get_zone_for_reclaim(zmd);
	if (!dzone)
	return;

	start = jiffies;

	if (dmz_is_rnd(dzone)) {
	if (!dmz_weight(dzone)) {
	/* Empty zone */
	dmz_reclaim_empty(zrc, dzone);
	ret = 0;
	} else {
	/*
	* Reclaim the random data zone by moving its
	* valid data blocks to a free sequential zone.
	*/
	ret = dmz_reclaim_rnd_data(zrc, dzone);
	}
	rzone = dzone;

	} else {
	struct dm_zone *bzone = dzone->bzone;
	sector_t chunk_block = 0;

	ret = dmz_first_valid_block(zmd, bzone, &chunk_block);
	if (ret < 0)
	goto out;

	if (ret == 0 \|\| chunk_block >= dzone->wp_block) {
	/*
	* The buffer zone is empty or its valid blocks are
	* after the data zone write pointer.
	*/
	ret = dmz_reclaim_buf(zrc, dzone);
	rzone = bzone;
	} else {
	/*
	* Reclaim the data zone by merging it into the
	* buffer zone so that the buffer zone itself can
	* be later reclaimed.
	*/
	ret = dmz_reclaim_seq_data(zrc, dzone);
	rzone = dzone;
	}
	}
	out:
	if (ret) {
	dmz_unlock_zone_reclaim(dzone);
	return;
	}

	(void) dmz_flush_metadata(zrc->metadata);

	dmz_dev_debug(zrc->dev, "Reclaimed zone %u in %u ms",
	dmz_id(zmd, rzone), jiffies_to_msecs(jiffies - start));
	}

	/*
	* Test if the target device is idle.
	*/
	static inline int dmz_target_idle(struct dmz_reclaim *zrc)
	{
	return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
	}

	/*
	* Test if reclaim is necessary.
	*/
	static bool dmz_should_reclaim(struct dmz_reclaim *zrc)
	{
	struct dmz_metadata *zmd = zrc->metadata;
	unsigned int nr_rnd = dmz_nr_rnd_zones(zmd);
	unsigned int nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
	unsigned int p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;

	/* Reclaim when idle */
	if (dmz_target_idle(zrc) && nr_unmap_rnd < nr_rnd)
	return true;

	/* If there are still plenty of random zones, do not reclaim */
	if (p_unmap_rnd >= DMZ_RECLAIM_HIGH_UNMAP_RND)
	return false;

	/*
	* If the percentage of unmappped random zones is low,
	* reclaim even if the target is busy.
	*/
	return p_unmap_rnd <= DMZ_RECLAIM_LOW_UNMAP_RND;
	}

	/*
	* Reclaim work function.
	*/
	static void dmz_reclaim_work(struct work_struct *work)
	{
	struct dmz_reclaim *zrc = container_of(work, struct dmz_reclaim, work.work);
	struct dmz_metadata *zmd = zrc->metadata;
	unsigned int nr_rnd, nr_unmap_rnd;
	unsigned int p_unmap_rnd;

	if (!dmz_should_reclaim(zrc)) {
	mod_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
	return;
	}

	/*
	* We need to start reclaiming random zones: set up zone copy
	* throttling to either go fast if we are very low on random zones
	* and slower if there are still some free random zones to avoid
	* as much as possible to negatively impact the user workload.
	*/
	nr_rnd = dmz_nr_rnd_zones(zmd);
	nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
	p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
	if (dmz_target_idle(zrc) \|\| p_unmap_rnd < DMZ_RECLAIM_LOW_UNMAP_RND / 2) {
	/* Idle or very low percentage: go fast */
	zrc->kc_throttle.throttle = 100;
	} else {
	/* Busy but we still have some random zone: throttle */
	zrc->kc_throttle.throttle = min(75U, 100U - p_unmap_rnd / 2);
	}

	dmz_dev_debug(zrc->dev,
	"Reclaim (%u): %s, %u%% free rnd zones (%u/%u)",
	zrc->kc_throttle.throttle,
	(dmz_target_idle(zrc) ? "Idle" : "Busy"),
	p_unmap_rnd, nr_unmap_rnd, nr_rnd);

	dmz_reclaim(zrc);

	dmz_schedule_reclaim(zrc);
	}

	/*
	* Initialize reclaim.
	*/
	int dmz_ctr_reclaim(struct dmz_dev dev, struct dmz_metadata zmd,
	struct dmz_reclaim **reclaim)
	{
	struct dmz_reclaim *zrc;
	int ret;

	zrc = kzalloc(sizeof(struct dmz_reclaim), GFP_KERNEL);
	if (!zrc)
	return -ENOMEM;

	zrc->dev = dev;
	zrc->metadata = zmd;
	zrc->atime = jiffies;

	/* Reclaim kcopyd client */
	zrc->kc = dm_kcopyd_client_create(&zrc->kc_throttle);
	if (IS_ERR(zrc->kc)) {
	ret = PTR_ERR(zrc->kc);
	zrc->kc = NULL;
	goto err;
	}

	/* Reclaim work */
	INIT_DELAYED_WORK(&zrc->work, dmz_reclaim_work);
	zrc->wq = alloc_ordered_workqueue("dmz_rwq_%s", WQ_MEM_RECLAIM,
	dev->name);
	if (!zrc->wq) {
	ret = -ENOMEM;
	goto err;
	}

	*reclaim = zrc;
	queue_delayed_work(zrc->wq, &zrc->work, 0);

	return 0;
	err:
	if (zrc->kc)
	dm_kcopyd_client_destroy(zrc->kc);
	kfree(zrc);

	return ret;
	}

	/*
	* Terminate reclaim.
	*/
	void dmz_dtr_reclaim(struct dmz_reclaim *zrc)
	{
	cancel_delayed_work_sync(&zrc->work);
	destroy_workqueue(zrc->wq);
	dm_kcopyd_client_destroy(zrc->kc);
	kfree(zrc);
	}

	/*
	* Suspend reclaim.
	*/
	void dmz_suspend_reclaim(struct dmz_reclaim *zrc)
	{
	cancel_delayed_work_sync(&zrc->work);
	}

	/*
	* Resume reclaim.
	*/
	void dmz_resume_reclaim(struct dmz_reclaim *zrc)
	{
	queue_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
	}

	/*
	* BIO accounting.
	*/
	void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc)
	{
	zrc->atime = jiffies;
	}

	/*
	* Start reclaim if necessary.
	*/
	void dmz_schedule_reclaim(struct dmz_reclaim *zrc)
	{
	if (dmz_should_reclaim(zrc))
	mod_delayed_work(zrc->wq, &zrc->work, 0);
	}