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Release 4.14 drivers/md/dm-zoned-reclaim.c

Directory: drivers/md
/*
 * 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; }

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/* * 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); }

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/* * 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; }

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/* * 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; }

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/* * 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; }

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/* * 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; }

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/* * 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); }

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/* * 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)); }

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/* * 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); }

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/* * 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; }

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/* * 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); }

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/* * 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; }

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/* * 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); }

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

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

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

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/* * 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); }

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Directory: drivers/md
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