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linux-next/drivers/md/dm-zoned.h
Damien Le Moal 3b1a94c88b dm zoned: drive-managed zoned block device target 
The dm-zoned device mapper target provides transparent write access
to zoned block devices (ZBC and ZAC compliant block devices).
dm-zoned hides to the device user (a file system or an application
doing raw block device accesses) any constraint imposed on write
requests by the device, equivalent to a drive-managed zoned block
device model.

Write requests are processed using a combination of on-disk buffering
using the device conventional zones and direct in-place processing for
requests aligned to a zone sequential write pointer position.
A background reclaim process implemented using dm_kcopyd_copy ensures
that conventional zones are always available for executing unaligned
write requests. The reclaim process overhead is minimized by managing
buffer zones in a least-recently-written order and first targeting the
oldest buffer zones. Doing so, blocks under regular write access (such
as metadata blocks of a file system) remain stored in conventional
zones, resulting in no apparent overhead.

dm-zoned implementation focus on simplicity and on minimizing overhead
(CPU, memory and storage overhead). For a 14TB host-managed disk with
256 MB zones, dm-zoned memory usage per disk instance is at most about
3 MB and as little as 5 zones will be used internally for storing metadata
and performing buffer zone reclaim operations. This is achieved using
zone level indirection rather than a full block indirection system for
managing block movement between zones.

dm-zoned primary target is host-managed zoned block devices but it can
also be used with host-aware device models to mitigate potential
device-side performance degradation due to excessive random writing.

Zoned block devices can be formatted and checked for use with the dm-zoned
target using the dmzadm utility available at:

https://github.com/hgst/dm-zoned-tools

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
[Mike Snitzer partly refactored Damien's original work to cleanup the code]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-06-19 11:05:20 -04:00

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/*
* Copyright (C) 2017 Western Digital Corporation or its affiliates.
*
* This file is released under the GPL.
*/
#ifndef DM_ZONED_H
#define DM_ZONED_H
#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/device-mapper.h>
#include <linux/dm-kcopyd.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/rwsem.h>
#include <linux/rbtree.h>
#include <linux/radix-tree.h>
#include <linux/shrinker.h>
/*
* dm-zoned creates block devices with 4KB blocks, always.
*/
#define DMZ_BLOCK_SHIFT 12
#define DMZ_BLOCK_SIZE (1 << DMZ_BLOCK_SHIFT)
#define DMZ_BLOCK_MASK (DMZ_BLOCK_SIZE - 1)
#define DMZ_BLOCK_SHIFT_BITS (DMZ_BLOCK_SHIFT + 3)
#define DMZ_BLOCK_SIZE_BITS (1 << DMZ_BLOCK_SHIFT_BITS)
#define DMZ_BLOCK_MASK_BITS (DMZ_BLOCK_SIZE_BITS - 1)
#define DMZ_BLOCK_SECTORS_SHIFT (DMZ_BLOCK_SHIFT - SECTOR_SHIFT)
#define DMZ_BLOCK_SECTORS (DMZ_BLOCK_SIZE >> SECTOR_SHIFT)
#define DMZ_BLOCK_SECTORS_MASK (DMZ_BLOCK_SECTORS - 1)
/*
* 4KB block <-> 512B sector conversion.
*/
#define dmz_blk2sect(b) ((sector_t)(b) << DMZ_BLOCK_SECTORS_SHIFT)
#define dmz_sect2blk(s) ((sector_t)(s) >> DMZ_BLOCK_SECTORS_SHIFT)
#define dmz_bio_block(bio) dmz_sect2blk((bio)->bi_iter.bi_sector)
#define dmz_bio_blocks(bio) dmz_sect2blk(bio_sectors(bio))
/*
* Zoned block device information.
*/
struct dmz_dev {
struct block_device *bdev;
char name[BDEVNAME_SIZE];
sector_t capacity;
unsigned int nr_zones;
sector_t zone_nr_sectors;
unsigned int zone_nr_sectors_shift;
sector_t zone_nr_blocks;
sector_t zone_nr_blocks_shift;
};
#define dmz_bio_chunk(dev, bio) ((bio)->bi_iter.bi_sector >> \
(dev)->zone_nr_sectors_shift)
#define dmz_chunk_block(dev, b) ((b) & ((dev)->zone_nr_blocks - 1))
/*
* Zone descriptor.
*/
struct dm_zone {
/* For listing the zone depending on its state */
struct list_head link;
/* Zone type and state */
unsigned long flags;
/* Zone activation reference count */
atomic_t refcount;
/* Zone write pointer block (relative to the zone start block) */
unsigned int wp_block;
/* Zone weight (number of valid blocks in the zone) */
unsigned int weight;
/* The chunk that the zone maps */
unsigned int chunk;
/*
* For a sequential data zone, pointer to the random zone
* used as a buffer for processing unaligned writes.
* For a buffer zone, this points back to the data zone.
*/
struct dm_zone *bzone;
};
/*
* Zone flags.
*/
enum {
/* Zone write type */
DMZ_RND,
DMZ_SEQ,
/* Zone critical condition */
DMZ_OFFLINE,
DMZ_READ_ONLY,
/* How the zone is being used */
DMZ_META,
DMZ_DATA,
DMZ_BUF,
/* Zone internal state */
DMZ_ACTIVE,
DMZ_RECLAIM,
DMZ_SEQ_WRITE_ERR,
};
/*
* Zone data accessors.
*/
#define dmz_is_rnd(z) test_bit(DMZ_RND, &(z)->flags)
#define dmz_is_seq(z) test_bit(DMZ_SEQ, &(z)->flags)
#define dmz_is_empty(z) ((z)->wp_block == 0)
#define dmz_is_offline(z) test_bit(DMZ_OFFLINE, &(z)->flags)
#define dmz_is_readonly(z) test_bit(DMZ_READ_ONLY, &(z)->flags)
#define dmz_is_active(z) test_bit(DMZ_ACTIVE, &(z)->flags)
#define dmz_in_reclaim(z) test_bit(DMZ_RECLAIM, &(z)->flags)
#define dmz_seq_write_err(z) test_bit(DMZ_SEQ_WRITE_ERR, &(z)->flags)
#define dmz_is_meta(z) test_bit(DMZ_META, &(z)->flags)
#define dmz_is_buf(z) test_bit(DMZ_BUF, &(z)->flags)
#define dmz_is_data(z) test_bit(DMZ_DATA, &(z)->flags)
#define dmz_weight(z) ((z)->weight)
/*
* Message functions.
*/
#define dmz_dev_info(dev, format, args...) \
DMINFO("(%s): " format, (dev)->name, ## args)
#define dmz_dev_err(dev, format, args...) \
DMERR("(%s): " format, (dev)->name, ## args)
#define dmz_dev_warn(dev, format, args...) \
DMWARN("(%s): " format, (dev)->name, ## args)
#define dmz_dev_debug(dev, format, args...) \
DMDEBUG("(%s): " format, (dev)->name, ## args)
struct dmz_metadata;
struct dmz_reclaim;
/*
* Functions defined in dm-zoned-metadata.c
*/
int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **zmd);
void dmz_dtr_metadata(struct dmz_metadata *zmd);
int dmz_resume_metadata(struct dmz_metadata *zmd);
void dmz_lock_map(struct dmz_metadata *zmd);
void dmz_unlock_map(struct dmz_metadata *zmd);
void dmz_lock_metadata(struct dmz_metadata *zmd);
void dmz_unlock_metadata(struct dmz_metadata *zmd);
void dmz_lock_flush(struct dmz_metadata *zmd);
void dmz_unlock_flush(struct dmz_metadata *zmd);
int dmz_flush_metadata(struct dmz_metadata *zmd);
unsigned int dmz_id(struct dmz_metadata *zmd, struct dm_zone *zone);
sector_t dmz_start_sect(struct dmz_metadata *zmd, struct dm_zone *zone);
sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone);
unsigned int dmz_nr_chunks(struct dmz_metadata *zmd);
#define DMZ_ALLOC_RND 0x01
#define DMZ_ALLOC_RECLAIM 0x02
struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags);
void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *zone,
unsigned int chunk);
void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd);
unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd);
void dmz_activate_zone(struct dm_zone *zone);
void dmz_deactivate_zone(struct dm_zone *zone);
int dmz_lock_zone_reclaim(struct dm_zone *zone);
void dmz_unlock_zone_reclaim(struct dm_zone *zone);
struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd);
struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd,
unsigned int chunk, int op);
void dmz_put_chunk_mapping(struct dmz_metadata *zmd, struct dm_zone *zone);
struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
struct dm_zone *dzone);
int dmz_validate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t chunk_block, unsigned int nr_blocks);
int dmz_invalidate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t chunk_block, unsigned int nr_blocks);
int dmz_block_valid(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t chunk_block);
int dmz_first_valid_block(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t *chunk_block);
int dmz_copy_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
struct dm_zone *to_zone);
int dmz_merge_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
struct dm_zone *to_zone, sector_t chunk_block);
/*
* Functions defined in dm-zoned-reclaim.c
*/
int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
struct dmz_reclaim **zrc);
void dmz_dtr_reclaim(struct dmz_reclaim *zrc);
void dmz_suspend_reclaim(struct dmz_reclaim *zrc);
void dmz_resume_reclaim(struct dmz_reclaim *zrc);
void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc);
void dmz_schedule_reclaim(struct dmz_reclaim *zrc);
#endif /* DM_ZONED_H */
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