| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Joe Thornber | 13254 | 90.42% | 48 | 36.92% |
| Mike Snitzer | 913 | 6.23% | 35 | 26.92% |
| Tushar Sugandhi | 130 | 0.89% | 1 | 0.77% |
| Christoph Hellwig | 91 | 0.62% | 12 | 9.23% |
| Heinz Mauelshagen | 80 | 0.55% | 11 | 8.46% |
| Mikulas Patocka | 48 | 0.33% | 4 | 3.08% |
| John Pittman | 36 | 0.25% | 1 | 0.77% |
| Kent Overstreet | 25 | 0.17% | 2 | 1.54% |
| Anssi Hannula | 16 | 0.11% | 2 | 1.54% |
| monty_pavel@sina.com | 15 | 0.10% | 1 | 0.77% |
| Hannes Reinecke | 8 | 0.05% | 1 | 0.77% |
| Luo Meng | 8 | 0.05% | 1 | 0.77% |
| Alasdair G. Kergon | 7 | 0.05% | 2 | 1.54% |
| Darrick J. Wong | 6 | 0.04% | 1 | 0.77% |
| Wei Yongjun | 5 | 0.03% | 1 | 0.77% |
| Michael Christie | 5 | 0.03% | 1 | 0.77% |
| Manuel Schölling | 3 | 0.02% | 1 | 0.77% |
| Alan Cox | 3 | 0.02% | 1 | 0.77% |
| Eric Biggers | 2 | 0.01% | 1 | 0.77% |
| Vincent Pelletier | 1 | 0.01% | 1 | 0.77% |
| Steven Lung | 1 | 0.01% | 1 | 0.77% |
| Zheng Yongjun | 1 | 0.01% | 1 | 0.77% |
| Total | 14658 | 130 |
// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2012 Red Hat. All rights reserved. * * This file is released under the GPL. */ #include "dm.h" #include "dm-bio-prison-v2.h" #include "dm-bio-record.h" #include "dm-cache-metadata.h" #include "dm-io-tracker.h" #include <linux/dm-io.h> #include <linux/dm-kcopyd.h> #include <linux/jiffies.h> #include <linux/init.h> #include <linux/mempool.h> #include <linux/module.h> #include <linux/rwsem.h> #include <linux/slab.h> #include <linux/vmalloc.h> #define DM_MSG_PREFIX "cache" DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle, "A percentage of time allocated for copying to and/or from cache"); /*----------------------------------------------------------------*/ /* * Glossary: * * oblock: index of an origin block * cblock: index of a cache block * promotion: movement of a block from origin to cache * demotion: movement of a block from cache to origin * migration: movement of a block between the origin and cache device, * either direction */ /*----------------------------------------------------------------*/ /* * Represents a chunk of future work. 'input' allows continuations to pass * values between themselves, typically error values. */ struct continuation { struct work_struct ws; blk_status_t input; }; static inline void init_continuation(struct continuation *k, void (*fn)(struct work_struct *)) { INIT_WORK(&k->ws, fn); k->input = 0; } static inline void queue_continuation(struct workqueue_struct *wq, struct continuation *k) { queue_work(wq, &k->ws); } /*----------------------------------------------------------------*/ /* * The batcher collects together pieces of work that need a particular * operation to occur before they can proceed (typically a commit). */ struct batcher { /* * The operation that everyone is waiting for. */ blk_status_t (*commit_op)(void *context); void *commit_context; /* * This is how bios should be issued once the commit op is complete * (accounted_request). */ void (*issue_op)(struct bio *bio, void *context); void *issue_context; /* * Queued work gets put on here after commit. */ struct workqueue_struct *wq; spinlock_t lock; struct list_head work_items; struct bio_list bios; struct work_struct commit_work; bool commit_scheduled; }; static void __commit(struct work_struct *_ws) { struct batcher *b = container_of(_ws, struct batcher, commit_work); blk_status_t r; struct list_head work_items; struct work_struct *ws, *tmp; struct continuation *k; struct bio *bio; struct bio_list bios; INIT_LIST_HEAD(&work_items); bio_list_init(&bios); /* * We have to grab these before the commit_op to avoid a race * condition. */ spin_lock_irq(&b->lock); list_splice_init(&b->work_items, &work_items); bio_list_merge_init(&bios, &b->bios); b->commit_scheduled = false; spin_unlock_irq(&b->lock); r = b->commit_op(b->commit_context); list_for_each_entry_safe(ws, tmp, &work_items, entry) { k = container_of(ws, struct continuation, ws); k->input = r; INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */ queue_work(b->wq, ws); } while ((bio = bio_list_pop(&bios))) { if (r) { bio->bi_status = r; bio_endio(bio); } else b->issue_op(bio, b->issue_context); } } static void batcher_init(struct batcher *b, blk_status_t (*commit_op)(void *), void *commit_context, void (*issue_op)(struct bio *bio, void *), void *issue_context, struct workqueue_struct *wq) { b->commit_op = commit_op; b->commit_context = commit_context; b->issue_op = issue_op; b->issue_context = issue_context; b->wq = wq; spin_lock_init(&b->lock); INIT_LIST_HEAD(&b->work_items); bio_list_init(&b->bios); INIT_WORK(&b->commit_work, __commit); b->commit_scheduled = false; } static void async_commit(struct batcher *b) { queue_work(b->wq, &b->commit_work); } static void continue_after_commit(struct batcher *b, struct continuation *k) { bool commit_scheduled; spin_lock_irq(&b->lock); commit_scheduled = b->commit_scheduled; list_add_tail(&k->ws.entry, &b->work_items); spin_unlock_irq(&b->lock); if (commit_scheduled) async_commit(b); } /* * Bios are errored if commit failed. */ static void issue_after_commit(struct batcher *b, struct bio *bio) { bool commit_scheduled; spin_lock_irq(&b->lock); commit_scheduled = b->commit_scheduled; bio_list_add(&b->bios, bio); spin_unlock_irq(&b->lock); if (commit_scheduled) async_commit(b); } /* * Call this if some urgent work is waiting for the commit to complete. */ static void schedule_commit(struct batcher *b) { bool immediate; spin_lock_irq(&b->lock); immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios); b->commit_scheduled = true; spin_unlock_irq(&b->lock); if (immediate) async_commit(b); } /* * There are a couple of places where we let a bio run, but want to do some * work before calling its endio function. We do this by temporarily * changing the endio fn. */ struct dm_hook_info { bio_end_io_t *bi_end_io; }; static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio, bio_end_io_t *bi_end_io, void *bi_private) { h->bi_end_io = bio->bi_end_io; bio->bi_end_io = bi_end_io; bio->bi_private = bi_private; } static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio) { bio->bi_end_io = h->bi_end_io; } /*----------------------------------------------------------------*/ #define MIGRATION_POOL_SIZE 128 #define COMMIT_PERIOD HZ #define MIGRATION_COUNT_WINDOW 10 /* * The block size of the device holding cache data must be * between 32KB and 1GB. */ #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT) #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT) enum cache_metadata_mode { CM_WRITE, /* metadata may be changed */ CM_READ_ONLY, /* metadata may not be changed */ CM_FAIL }; enum cache_io_mode { /* * Data is written to cached blocks only. These blocks are marked * dirty. If you lose the cache device you will lose data. * Potential performance increase for both reads and writes. */ CM_IO_WRITEBACK, /* * Data is written to both cache and origin. Blocks are never * dirty. Potential performance benfit for reads only. */ CM_IO_WRITETHROUGH, /* * A degraded mode useful for various cache coherency situations * (eg, rolling back snapshots). Reads and writes always go to the * origin. If a write goes to a cached oblock, then the cache * block is invalidated. */ CM_IO_PASSTHROUGH }; struct cache_features { enum cache_metadata_mode mode; enum cache_io_mode io_mode; unsigned int metadata_version; bool discard_passdown:1; }; struct cache_stats { atomic_t read_hit; atomic_t read_miss; atomic_t write_hit; atomic_t write_miss; atomic_t demotion; atomic_t promotion; atomic_t writeback; atomic_t copies_avoided; atomic_t cache_cell_clash; atomic_t commit_count; atomic_t discard_count; }; struct cache { struct dm_target *ti; spinlock_t lock; /* * Fields for converting from sectors to blocks. */ int sectors_per_block_shift; sector_t sectors_per_block; struct dm_cache_metadata *cmd; /* * Metadata is written to this device. */ struct dm_dev *metadata_dev; /* * The slower of the two data devices. Typically a spindle. */ struct dm_dev *origin_dev; /* * The faster of the two data devices. Typically an SSD. */ struct dm_dev *cache_dev; /* * Size of the origin device in _complete_ blocks and native sectors. */ dm_oblock_t origin_blocks; sector_t origin_sectors; /* * Size of the cache device in blocks. */ dm_cblock_t cache_size; /* * Invalidation fields. */ spinlock_t invalidation_lock; struct list_head invalidation_requests; sector_t migration_threshold; wait_queue_head_t migration_wait; atomic_t nr_allocated_migrations; /* * The number of in flight migrations that are performing * background io. eg, promotion, writeback. */ atomic_t nr_io_migrations; struct bio_list deferred_bios; struct rw_semaphore quiesce_lock; /* * origin_blocks entries, discarded if set. */ dm_dblock_t discard_nr_blocks; unsigned long *discard_bitset; uint32_t discard_block_size; /* a power of 2 times sectors per block */ /* * Rather than reconstructing the table line for the status we just * save it and regurgitate. */ unsigned int nr_ctr_args; const char **ctr_args; struct dm_kcopyd_client *copier; struct work_struct deferred_bio_worker; struct work_struct migration_worker; struct workqueue_struct *wq; struct delayed_work waker; struct dm_bio_prison_v2 *prison; /* * cache_size entries, dirty if set */ unsigned long *dirty_bitset; atomic_t nr_dirty; unsigned int policy_nr_args; struct dm_cache_policy *policy; /* * Cache features such as write-through. */ struct cache_features features; struct cache_stats stats; bool need_tick_bio:1; bool sized:1; bool invalidate:1; bool commit_requested:1; bool loaded_mappings:1; bool loaded_discards:1; struct rw_semaphore background_work_lock; struct batcher committer; struct work_struct commit_ws; struct dm_io_tracker tracker; mempool_t migration_pool; struct bio_set bs; }; struct per_bio_data { bool tick:1; unsigned int req_nr:2; struct dm_bio_prison_cell_v2 *cell; struct dm_hook_info hook_info; sector_t len; }; struct dm_cache_migration { struct continuation k; struct cache *cache; struct policy_work *op; struct bio *overwrite_bio; struct dm_bio_prison_cell_v2 *cell; dm_cblock_t invalidate_cblock; dm_oblock_t invalidate_oblock; }; /*----------------------------------------------------------------*/ static bool writethrough_mode(struct cache *cache) { return cache->features.io_mode == CM_IO_WRITETHROUGH; } static bool writeback_mode(struct cache *cache) { return cache->features.io_mode == CM_IO_WRITEBACK; } static inline bool passthrough_mode(struct cache *cache) { return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH); } /*----------------------------------------------------------------*/ static void wake_deferred_bio_worker(struct cache *cache) { queue_work(cache->wq, &cache->deferred_bio_worker); } static void wake_migration_worker(struct cache *cache) { if (passthrough_mode(cache)) return; queue_work(cache->wq, &cache->migration_worker); } /*----------------------------------------------------------------*/ static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache) { return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOIO); } static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell) { dm_bio_prison_free_cell_v2(cache->prison, cell); } static struct dm_cache_migration *alloc_migration(struct cache *cache) { struct dm_cache_migration *mg; mg = mempool_alloc(&cache->migration_pool, GFP_NOIO); memset(mg, 0, sizeof(*mg)); mg->cache = cache; atomic_inc(&cache->nr_allocated_migrations); return mg; } static void free_migration(struct dm_cache_migration *mg) { struct cache *cache = mg->cache; if (atomic_dec_and_test(&cache->nr_allocated_migrations)) wake_up(&cache->migration_wait); mempool_free(mg, &cache->migration_pool); } /*----------------------------------------------------------------*/ static inline dm_oblock_t oblock_succ(dm_oblock_t b) { return to_oblock(from_oblock(b) + 1ull); } static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key) { key->virtual = 0; key->dev = 0; key->block_begin = from_oblock(begin); key->block_end = from_oblock(end); } /* * We have two lock levels. Level 0, which is used to prevent WRITEs, and * level 1 which prevents *both* READs and WRITEs. */ #define WRITE_LOCK_LEVEL 0 #define READ_WRITE_LOCK_LEVEL 1 static unsigned int lock_level(struct bio *bio) { return bio_data_dir(bio) == WRITE ? WRITE_LOCK_LEVEL : READ_WRITE_LOCK_LEVEL; } /* *-------------------------------------------------------------- * Per bio data *-------------------------------------------------------------- */ static struct per_bio_data *get_per_bio_data(struct bio *bio) { struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); BUG_ON(!pb); return pb; } static struct per_bio_data *init_per_bio_data(struct bio *bio) { struct per_bio_data *pb = get_per_bio_data(bio); pb->tick = false; pb->req_nr = dm_bio_get_target_bio_nr(bio); pb->cell = NULL; pb->len = 0; return pb; } /*----------------------------------------------------------------*/ static void defer_bio(struct cache *cache, struct bio *bio) { spin_lock_irq(&cache->lock); bio_list_add(&cache->deferred_bios, bio); spin_unlock_irq(&cache->lock); wake_deferred_bio_worker(cache); } static void defer_bios(struct cache *cache, struct bio_list *bios) { spin_lock_irq(&cache->lock); bio_list_merge_init(&cache->deferred_bios, bios); spin_unlock_irq(&cache->lock); wake_deferred_bio_worker(cache); } /*----------------------------------------------------------------*/ static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio) { bool r; struct per_bio_data *pb; struct dm_cell_key_v2 key; dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL); struct dm_bio_prison_cell_v2 *cell_prealloc, *cell; cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */ build_key(oblock, end, &key); r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell); if (!r) { /* * Failed to get the lock. */ free_prison_cell(cache, cell_prealloc); return r; } if (cell != cell_prealloc) free_prison_cell(cache, cell_prealloc); pb = get_per_bio_data(bio); pb->cell = cell; return r; } /*----------------------------------------------------------------*/ static bool is_dirty(struct cache *cache, dm_cblock_t b) { return test_bit(from_cblock(b), cache->dirty_bitset); } static void set_dirty(struct cache *cache, dm_cblock_t cblock) { if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) { atomic_inc(&cache->nr_dirty); policy_set_dirty(cache->policy, cblock); } } /* * These two are called when setting after migrations to force the policy * and dirty bitset to be in sync. */ static void force_set_dirty(struct cache *cache, dm_cblock_t cblock) { if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) atomic_inc(&cache->nr_dirty); policy_set_dirty(cache->policy, cblock); } static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock) { if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) { if (atomic_dec_return(&cache->nr_dirty) == 0) dm_table_event(cache->ti->table); } policy_clear_dirty(cache->policy, cblock); } /*----------------------------------------------------------------*/ static bool block_size_is_power_of_two(struct cache *cache) { return cache->sectors_per_block_shift >= 0; } static dm_block_t block_div(dm_block_t b, uint32_t n) { do_div(b, n); return b; } static dm_block_t oblocks_per_dblock(struct cache *cache) { dm_block_t oblocks = cache->discard_block_size; if (block_size_is_power_of_two(cache)) oblocks >>= cache->sectors_per_block_shift; else oblocks = block_div(oblocks, cache->sectors_per_block); return oblocks; } static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock) { return to_dblock(block_div(from_oblock(oblock), oblocks_per_dblock(cache))); } static void set_discard(struct cache *cache, dm_dblock_t b) { BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks)); atomic_inc(&cache->stats.discard_count); spin_lock_irq(&cache->lock); set_bit(from_dblock(b), cache->discard_bitset); spin_unlock_irq(&cache->lock); } static void clear_discard(struct cache *cache, dm_dblock_t b) { spin_lock_irq(&cache->lock); clear_bit(from_dblock(b), cache->discard_bitset); spin_unlock_irq(&cache->lock); } static bool is_discarded(struct cache *cache, dm_dblock_t b) { int r; spin_lock_irq(&cache->lock); r = test_bit(from_dblock(b), cache->discard_bitset); spin_unlock_irq(&cache->lock); return r; } static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b) { int r; spin_lock_irq(&cache->lock); r = test_bit(from_dblock(oblock_to_dblock(cache, b)), cache->discard_bitset); spin_unlock_irq(&cache->lock); return r; } /* * ------------------------------------------------------------- * Remapping *-------------------------------------------------------------- */ static void remap_to_origin(struct cache *cache, struct bio *bio) { bio_set_dev(bio, cache->origin_dev->bdev); } static void remap_to_cache(struct cache *cache, struct bio *bio, dm_cblock_t cblock) { sector_t bi_sector = bio->bi_iter.bi_sector; sector_t block = from_cblock(cblock); bio_set_dev(bio, cache->cache_dev->bdev); if (!block_size_is_power_of_two(cache)) bio->bi_iter.bi_sector = (block * cache->sectors_per_block) + sector_div(bi_sector, cache->sectors_per_block); else bio->bi_iter.bi_sector = (block << cache->sectors_per_block_shift) | (bi_sector & (cache->sectors_per_block - 1)); } static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio) { struct per_bio_data *pb; spin_lock_irq(&cache->lock); if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) && bio_op(bio) != REQ_OP_DISCARD) { pb = get_per_bio_data(bio); pb->tick = true; cache->need_tick_bio = false; } spin_unlock_irq(&cache->lock); } static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio, dm_oblock_t oblock) { // FIXME: check_if_tick_bio_needed() is called way too much through this interface check_if_tick_bio_needed(cache, bio); remap_to_origin(cache, bio); if (bio_data_dir(bio) == WRITE) clear_discard(cache, oblock_to_dblock(cache, oblock)); } static void remap_to_cache_dirty(struct cache *cache, struct bio *bio, dm_oblock_t oblock, dm_cblock_t cblock) { check_if_tick_bio_needed(cache, bio); remap_to_cache(cache, bio, cblock); if (bio_data_dir(bio) == WRITE) { set_dirty(cache, cblock); clear_discard(cache, oblock_to_dblock(cache, oblock)); } } static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio) { sector_t block_nr = bio->bi_iter.bi_sector; if (!block_size_is_power_of_two(cache)) (void) sector_div(block_nr, cache->sectors_per_block); else block_nr >>= cache->sectors_per_block_shift; return to_oblock(block_nr); } static bool accountable_bio(struct cache *cache, struct bio *bio) { return bio_op(bio) != REQ_OP_DISCARD; } static void accounted_begin(struct cache *cache, struct bio *bio) { struct per_bio_data *pb; if (accountable_bio(cache, bio)) { pb = get_per_bio_data(bio); pb->len = bio_sectors(bio); dm_iot_io_begin(&cache->tracker, pb->len); } } static void accounted_complete(struct cache *cache, struct bio *bio) { struct per_bio_data *pb = get_per_bio_data(bio); dm_iot_io_end(&cache->tracker, pb->len); } static void accounted_request(struct cache *cache, struct bio *bio) { accounted_begin(cache, bio); dm_submit_bio_remap(bio, NULL); } static void issue_op(struct bio *bio, void *context) { struct cache *cache = context; accounted_request(cache, bio); } /* * When running in writethrough mode we need to send writes to clean blocks * to both the cache and origin devices. Clone the bio and send them in parallel. */ static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio, dm_oblock_t oblock, dm_cblock_t cblock) { struct bio *origin_bio = bio_alloc_clone(cache->origin_dev->bdev, bio, GFP_NOIO, &cache->bs); BUG_ON(!origin_bio); bio_chain(origin_bio, bio); if (bio_data_dir(origin_bio) == WRITE) clear_discard(cache, oblock_to_dblock(cache, oblock)); submit_bio(origin_bio); remap_to_cache(cache, bio, cblock); } /* *-------------------------------------------------------------- * Failure modes *-------------------------------------------------------------- */ static enum cache_metadata_mode get_cache_mode(struct cache *cache) { return cache->features.mode; } static const char *cache_device_name(struct cache *cache) { return dm_table_device_name(cache->ti->table); } static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode) { static const char *descs[] = { "write", "read-only", "fail" }; dm_table_event(cache->ti->table); DMINFO("%s: switching cache to %s mode", cache_device_name(cache), descs[(int)mode]); } static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode) { bool needs_check; enum cache_metadata_mode old_mode = get_cache_mode(cache); if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) { DMERR("%s: unable to read needs_check flag, setting failure mode.", cache_device_name(cache)); new_mode = CM_FAIL; } if (new_mode == CM_WRITE && needs_check) { DMERR("%s: unable to switch cache to write mode until repaired.", cache_device_name(cache)); if (old_mode != new_mode) new_mode = old_mode; else new_mode = CM_READ_ONLY; } /* Never move out of fail mode */ if (old_mode == CM_FAIL) new_mode = CM_FAIL; switch (new_mode) { case CM_FAIL: case CM_READ_ONLY: dm_cache_metadata_set_read_only(cache->cmd); break; case CM_WRITE: dm_cache_metadata_set_read_write(cache->cmd); break; } cache->features.mode = new_mode; if (new_mode != old_mode) notify_mode_switch(cache, new_mode); } static void abort_transaction(struct cache *cache) { const char *dev_name = cache_device_name(cache); if (get_cache_mode(cache) >= CM_READ_ONLY) return; DMERR_LIMIT("%s: aborting current metadata transaction", dev_name); if (dm_cache_metadata_abort(cache->cmd)) { DMERR("%s: failed to abort metadata transaction", dev_name); set_cache_mode(cache, CM_FAIL); } if (dm_cache_metadata_set_needs_check(cache->cmd)) { DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name); set_cache_mode(cache, CM_FAIL); } } static void metadata_operation_failed(struct cache *cache, const char *op, int r) { DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d", cache_device_name(cache), op, r); abort_transaction(cache); set_cache_mode(cache, CM_READ_ONLY); } /*----------------------------------------------------------------*/ static void load_stats(struct cache *cache) { struct dm_cache_statistics stats; dm_cache_metadata_get_stats(cache->cmd, &stats); atomic_set(&cache->stats.read_hit, stats.read_hits); atomic_set(&cache->stats.read_miss, stats.read_misses); atomic_set(&cache->stats.write_hit, stats.write_hits); atomic_set(&cache->stats.write_miss, stats.write_misses); } static void save_stats(struct cache *cache) { struct dm_cache_statistics stats; if (get_cache_mode(cache) >= CM_READ_ONLY) return; stats.read_hits = atomic_read(&cache->stats.read_hit); stats.read_misses = atomic_read(&cache->stats.read_miss); stats.write_hits = atomic_read(&cache->stats.write_hit); stats.write_misses = atomic_read(&cache->stats.write_miss); dm_cache_metadata_set_stats(cache->cmd, &stats); } static void update_stats(struct cache_stats *stats, enum policy_operation op) { switch (op) { case POLICY_PROMOTE: atomic_inc(&stats->promotion); break; case POLICY_DEMOTE: atomic_inc(&stats->demotion); break; case POLICY_WRITEBACK: atomic_inc(&stats->writeback); break; } } /* *--------------------------------------------------------------------- * Migration processing * * Migration covers moving data from the origin device to the cache, or * vice versa. *--------------------------------------------------------------------- */ static void inc_io_migrations(struct cache *cache) { atomic_inc(&cache->nr_io_migrations); } static void dec_io_migrations(struct cache *cache) { atomic_dec(&cache->nr_io_migrations); } static bool discard_or_flush(struct bio *bio) { return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf); } static void calc_discard_block_range(struct cache *cache, struct bio *bio, dm_dblock_t *b, dm_dblock_t *e) { sector_t sb = bio->bi_iter.bi_sector; sector_t se = bio_end_sector(bio); *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size)); if (se - sb < cache->discard_block_size) *e = *b; else *e = to_dblock(block_div(se, cache->discard_block_size)); } /*----------------------------------------------------------------*/ static void prevent_background_work(struct cache *cache) { lockdep_off(); down_write(&cache->background_work_lock); lockdep_on(); } static void allow_background_work(struct cache *cache) { lockdep_off(); up_write(&cache->background_work_lock); lockdep_on(); } static bool background_work_begin(struct cache *cache) { bool r; lockdep_off(); r = down_read_trylock(&cache->background_work_lock); lockdep_on(); return r; } static void background_work_end(struct cache *cache) { lockdep_off(); up_read(&cache->background_work_lock); lockdep_on(); } /*----------------------------------------------------------------*/ static bool bio_writes_complete_block(struct cache *cache, struct bio *bio) { return (bio_data_dir(bio) == WRITE) && (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT)); } static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block) { return writeback_mode(cache) && (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio)); } static void quiesce(struct dm_cache_migration *mg, void (*continuation)(struct work_struct *)) { init_continuation(&mg->k, continuation); dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws); } static struct dm_cache_migration *ws_to_mg(struct work_struct *ws) { struct continuation *k = container_of(ws, struct continuation, ws); return container_of(k, struct dm_cache_migration, k); } static void copy_complete(int read_err, unsigned long write_err, void *context) { struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k); if (read_err || write_err) mg->k.input = BLK_STS_IOERR; queue_continuation(mg->cache->wq, &mg->k); } static void copy(struct dm_cache_migration *mg, bool promote) { struct dm_io_region o_region, c_region; struct cache *cache = mg->cache; o_region.bdev = cache->origin_dev->bdev; o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block; o_region.count = cache->sectors_per_block; c_region.bdev = cache->cache_dev->bdev; c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block; c_region.count = cache->sectors_per_block; if (promote) dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k); else dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k); } static void bio_drop_shared_lock(struct cache *cache, struct bio *bio) { struct per_bio_data *pb = get_per_bio_data(bio); if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell)) free_prison_cell(cache, pb->cell); pb->cell = NULL; } static void overwrite_endio(struct bio *bio) { struct dm_cache_migration *mg = bio->bi_private; struct cache *cache = mg->cache; struct per_bio_data *pb = get_per_bio_data(bio); dm_unhook_bio(&pb->hook_info, bio); if (bio->bi_status) mg->k.input = bio->bi_status; queue_continuation(cache->wq, &mg->k); } static void overwrite(struct dm_cache_migration *mg, void (*continuation)(struct work_struct *)) { struct bio *bio = mg->overwrite_bio; struct per_bio_data *pb = get_per_bio_data(bio); dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg); /* * The overwrite bio is part of the copy operation, as such it does * not set/clear discard or dirty flags. */ if (mg->op->op == POLICY_PROMOTE) remap_to_cache(mg->cache, bio, mg->op->cblock); else remap_to_origin(mg->cache, bio); init_continuation(&mg->k, continuation); accounted_request(mg->cache, bio); } /* * Migration steps: * * 1) exclusive lock preventing WRITEs * 2) quiesce * 3) copy or issue overwrite bio * 4) upgrade to exclusive lock preventing READs and WRITEs * 5) quiesce * 6) update metadata and commit * 7) unlock */ static void mg_complete(struct dm_cache_migration *mg, bool success) { struct bio_list bios; struct cache *cache = mg->cache; struct policy_work *op = mg->op; dm_cblock_t cblock = op->cblock; if (success) update_stats(&cache->stats, op->op); switch (op->op) { case POLICY_PROMOTE: clear_discard(cache, oblock_to_dblock(cache, op->oblock)); policy_complete_background_work(cache->policy, op, success); if (mg->overwrite_bio) { if (success) force_set_dirty(cache, cblock); else if (mg->k.input) mg->overwrite_bio->bi_status = mg->k.input; else mg->overwrite_bio->bi_status = BLK_STS_IOERR; bio_endio(mg->overwrite_bio); } else { if (success) force_clear_dirty(cache, cblock); dec_io_migrations(cache); } break; case POLICY_DEMOTE: /* * We clear dirty here to update the nr_dirty counter. */ if (success) force_clear_dirty(cache, cblock); policy_complete_background_work(cache->policy, op, success); dec_io_migrations(cache); break; case POLICY_WRITEBACK: if (success) force_clear_dirty(cache, cblock); policy_complete_background_work(cache->policy, op, success); dec_io_migrations(cache); break; } bio_list_init(&bios); if (mg->cell) { if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios)) free_prison_cell(cache, mg->cell); } free_migration(mg); defer_bios(cache, &bios); wake_migration_worker(cache); background_work_end(cache); } static void mg_success(struct work_struct *ws) { struct dm_cache_migration *mg = ws_to_mg(ws); mg_complete(mg, mg->k.input == 0); } static void mg_update_metadata(struct work_struct *ws) { int r; struct dm_cache_migration *mg = ws_to_mg(ws); struct cache *cache = mg->cache; struct policy_work *op = mg->op; switch (op->op) { case POLICY_PROMOTE: r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock); if (r) { DMERR_LIMIT("%s: migration failed; couldn't insert mapping", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_insert_mapping", r); mg_complete(mg, false); return; } mg_complete(mg, true); break; case POLICY_DEMOTE: r = dm_cache_remove_mapping(cache->cmd, op->cblock); if (r) { DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_remove_mapping", r); mg_complete(mg, false); return; } /* * It would be nice if we only had to commit when a REQ_FLUSH * comes through. But there's one scenario that we have to * look out for: * * - vblock x in a cache block * - domotion occurs * - cache block gets reallocated and over written * - crash * * When we recover, because there was no commit the cache will * rollback to having the data for vblock x in the cache block. * But the cache block has since been overwritten, so it'll end * up pointing to data that was never in 'x' during the history * of the device. * * To avoid this issue we require a commit as part of the * demotion operation. */ init_continuation(&mg->k, mg_success); continue_after_commit(&cache->committer, &mg->k); schedule_commit(&cache->committer); break; case POLICY_WRITEBACK: mg_complete(mg, true); break; } } static void mg_update_metadata_after_copy(struct work_struct *ws) { struct dm_cache_migration *mg = ws_to_mg(ws); /* * Did the copy succeed? */ if (mg->k.input) mg_complete(mg, false); else mg_update_metadata(ws); } static void mg_upgrade_lock(struct work_struct *ws) { int r; struct dm_cache_migration *mg = ws_to_mg(ws); /* * Did the copy succeed? */ if (mg->k.input) mg_complete(mg, false); else { /* * Now we want the lock to prevent both reads and writes. */ r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell, READ_WRITE_LOCK_LEVEL); if (r < 0) mg_complete(mg, false); else if (r) quiesce(mg, mg_update_metadata); else mg_update_metadata(ws); } } static void mg_full_copy(struct work_struct *ws) { struct dm_cache_migration *mg = ws_to_mg(ws); struct cache *cache = mg->cache; struct policy_work *op = mg->op; bool is_policy_promote = (op->op == POLICY_PROMOTE); if ((!is_policy_promote && !is_dirty(cache, op->cblock)) || is_discarded_oblock(cache, op->oblock)) { mg_upgrade_lock(ws); return; } init_continuation(&mg->k, mg_upgrade_lock); copy(mg, is_policy_promote); } static void mg_copy(struct work_struct *ws) { struct dm_cache_migration *mg = ws_to_mg(ws); if (mg->overwrite_bio) { /* * No exclusive lock was held when we last checked if the bio * was optimisable. So we have to check again in case things * have changed (eg, the block may no longer be discarded). */ if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) { /* * Fallback to a real full copy after doing some tidying up. */ bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio); BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */ mg->overwrite_bio = NULL; inc_io_migrations(mg->cache); mg_full_copy(ws); return; } /* * It's safe to do this here, even though it's new data * because all IO has been locked out of the block. * * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL * so _not_ using mg_upgrade_lock() as continutation. */ overwrite(mg, mg_update_metadata_after_copy); } else mg_full_copy(ws); } static int mg_lock_writes(struct dm_cache_migration *mg) { int r; struct dm_cell_key_v2 key; struct cache *cache = mg->cache; struct dm_bio_prison_cell_v2 *prealloc; prealloc = alloc_prison_cell(cache); /* * Prevent writes to the block, but allow reads to continue. * Unless we're using an overwrite bio, in which case we lock * everything. */ build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key); r = dm_cell_lock_v2(cache->prison, &key, mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL, prealloc, &mg->cell); if (r < 0) { free_prison_cell(cache, prealloc); mg_complete(mg, false); return r; } if (mg->cell != prealloc) free_prison_cell(cache, prealloc); if (r == 0) mg_copy(&mg->k.ws); else quiesce(mg, mg_copy); return 0; } static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio) { struct dm_cache_migration *mg; if (!background_work_begin(cache)) { policy_complete_background_work(cache->policy, op, false); return -EPERM; } mg = alloc_migration(cache); mg->op = op; mg->overwrite_bio = bio; if (!bio) inc_io_migrations(cache); return mg_lock_writes(mg); } /* *-------------------------------------------------------------- * invalidation processing *-------------------------------------------------------------- */ static void invalidate_complete(struct dm_cache_migration *mg, bool success) { struct bio_list bios; struct cache *cache = mg->cache; bio_list_init(&bios); if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios)) free_prison_cell(cache, mg->cell); if (!success && mg->overwrite_bio) bio_io_error(mg->overwrite_bio); free_migration(mg); defer_bios(cache, &bios); background_work_end(cache); } static void invalidate_completed(struct work_struct *ws) { struct dm_cache_migration *mg = ws_to_mg(ws); invalidate_complete(mg, !mg->k.input); } static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock) { int r; r = policy_invalidate_mapping(cache->policy, cblock); if (!r) { r = dm_cache_remove_mapping(cache->cmd, cblock); if (r) { DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_remove_mapping", r); } } else if (r == -ENODATA) { /* * Harmless, already unmapped. */ r = 0; } else DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache)); return r; } static void invalidate_remove(struct work_struct *ws) { int r; struct dm_cache_migration *mg = ws_to_mg(ws); struct cache *cache = mg->cache; r = invalidate_cblock(cache, mg->invalidate_cblock); if (r) { invalidate_complete(mg, false); return; } init_continuation(&mg->k, invalidate_completed); continue_after_commit(&cache->committer, &mg->k); remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock); mg->overwrite_bio = NULL; schedule_commit(&cache->committer); } static int invalidate_lock(struct dm_cache_migration *mg) { int r; struct dm_cell_key_v2 key; struct cache *cache = mg->cache; struct dm_bio_prison_cell_v2 *prealloc; prealloc = alloc_prison_cell(cache); build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key); r = dm_cell_lock_v2(cache->prison, &key, READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell); if (r < 0) { free_prison_cell(cache, prealloc); invalidate_complete(mg, false); return r; } if (mg->cell != prealloc) free_prison_cell(cache, prealloc); if (r) quiesce(mg, invalidate_remove); else { /* * We can't call invalidate_remove() directly here because we * might still be in request context. */ init_continuation(&mg->k, invalidate_remove); queue_work(cache->wq, &mg->k.ws); } return 0; } static int invalidate_start(struct cache *cache, dm_cblock_t cblock, dm_oblock_t oblock, struct bio *bio) { struct dm_cache_migration *mg; if (!background_work_begin(cache)) return -EPERM; mg = alloc_migration(cache); mg->overwrite_bio = bio; mg->invalidate_cblock = cblock; mg->invalidate_oblock = oblock; return invalidate_lock(mg); } /* *-------------------------------------------------------------- * bio processing *-------------------------------------------------------------- */ enum busy { IDLE, BUSY }; static enum busy spare_migration_bandwidth(struct cache *cache) { bool idle = dm_iot_idle_for(&cache->tracker, HZ); sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) * cache->sectors_per_block; if (idle && current_volume <= cache->migration_threshold) return IDLE; else return BUSY; } static void inc_hit_counter(struct cache *cache, struct bio *bio) { atomic_inc(bio_data_dir(bio) == READ ? &cache->stats.read_hit : &cache->stats.write_hit); } static void inc_miss_counter(struct cache *cache, struct bio *bio) { atomic_inc(bio_data_dir(bio) == READ ? &cache->stats.read_miss : &cache->stats.write_miss); } /*----------------------------------------------------------------*/ static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block, bool *commit_needed) { int r, data_dir; bool rb, background_queued; dm_cblock_t cblock; *commit_needed = false; rb = bio_detain_shared(cache, block, bio); if (!rb) { /* * An exclusive lock is held for this block, so we have to * wait. We set the commit_needed flag so the current * transaction will be committed asap, allowing this lock * to be dropped. */ *commit_needed = true; return DM_MAPIO_SUBMITTED; } data_dir = bio_data_dir(bio); if (optimisable_bio(cache, bio, block)) { struct policy_work *op = NULL; r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op); if (unlikely(r && r != -ENOENT)) { DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d", cache_device_name(cache), r); bio_io_error(bio); return DM_MAPIO_SUBMITTED; } if (r == -ENOENT && op) { bio_drop_shared_lock(cache, bio); BUG_ON(op->op != POLICY_PROMOTE); mg_start(cache, op, bio); return DM_MAPIO_SUBMITTED; } } else { r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued); if (unlikely(r && r != -ENOENT)) { DMERR_LIMIT("%s: policy_lookup() failed with r = %d", cache_device_name(cache), r); bio_io_error(bio); return DM_MAPIO_SUBMITTED; } if (background_queued) wake_migration_worker(cache); } if (r == -ENOENT) { struct per_bio_data *pb = get_per_bio_data(bio); /* * Miss. */ inc_miss_counter(cache, bio); if (pb->req_nr == 0) { accounted_begin(cache, bio); remap_to_origin_clear_discard(cache, bio, block); } else { /* * This is a duplicate writethrough io that is no * longer needed because the block has been demoted. */ bio_endio(bio); return DM_MAPIO_SUBMITTED; } } else { /* * Hit. */ inc_hit_counter(cache, bio); /* * Passthrough always maps to the origin, invalidating any * cache blocks that are written to. */ if (passthrough_mode(cache)) { if (bio_data_dir(bio) == WRITE) { bio_drop_shared_lock(cache, bio); atomic_inc(&cache->stats.demotion); invalidate_start(cache, cblock, block, bio); } else remap_to_origin_clear_discard(cache, bio, block); } else { if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) && !is_dirty(cache, cblock)) { remap_to_origin_and_cache(cache, bio, block, cblock); accounted_begin(cache, bio); } else remap_to_cache_dirty(cache, bio, block, cblock); } } /* * dm core turns FUA requests into a separate payload and FLUSH req. */ if (bio->bi_opf & REQ_FUA) { /* * issue_after_commit will call accounted_begin a second time. So * we call accounted_complete() to avoid double accounting. */ accounted_complete(cache, bio); issue_after_commit(&cache->committer, bio); *commit_needed = true; return DM_MAPIO_SUBMITTED; } return DM_MAPIO_REMAPPED; } static bool process_bio(struct cache *cache, struct bio *bio) { bool commit_needed; if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED) dm_submit_bio_remap(bio, NULL); return commit_needed; } /* * A non-zero return indicates read_only or fail_io mode. */ static int commit(struct cache *cache, bool clean_shutdown) { int r; if (get_cache_mode(cache) >= CM_READ_ONLY) return -EINVAL; atomic_inc(&cache->stats.commit_count); r = dm_cache_commit(cache->cmd, clean_shutdown); if (r) metadata_operation_failed(cache, "dm_cache_commit", r); return r; } /* * Used by the batcher. */ static blk_status_t commit_op(void *context) { struct cache *cache = context; if (dm_cache_changed_this_transaction(cache->cmd)) return errno_to_blk_status(commit(cache, false)); return 0; } /*----------------------------------------------------------------*/ static bool process_flush_bio(struct cache *cache, struct bio *bio) { struct per_bio_data *pb = get_per_bio_data(bio); if (!pb->req_nr) remap_to_origin(cache, bio); else remap_to_cache(cache, bio, 0); issue_after_commit(&cache->committer, bio); return true; } static bool process_discard_bio(struct cache *cache, struct bio *bio) { dm_dblock_t b, e; /* * FIXME: do we need to lock the region? Or can we just assume the * user wont be so foolish as to issue discard concurrently with * other IO? */ calc_discard_block_range(cache, bio, &b, &e); while (b != e) { set_discard(cache, b); b = to_dblock(from_dblock(b) + 1); } if (cache->features.discard_passdown) { remap_to_origin(cache, bio); dm_submit_bio_remap(bio, NULL); } else bio_endio(bio); return false; } static void process_deferred_bios(struct work_struct *ws) { struct cache *cache = container_of(ws, struct cache, deferred_bio_worker); bool commit_needed = false; struct bio_list bios; struct bio *bio; bio_list_init(&bios); spin_lock_irq(&cache->lock); bio_list_merge_init(&bios, &cache->deferred_bios); spin_unlock_irq(&cache->lock); while ((bio = bio_list_pop(&bios))) { if (bio->bi_opf & REQ_PREFLUSH) commit_needed = process_flush_bio(cache, bio) || commit_needed; else if (bio_op(bio) == REQ_OP_DISCARD) commit_needed = process_discard_bio(cache, bio) || commit_needed; else commit_needed = process_bio(cache, bio) || commit_needed; cond_resched(); } if (commit_needed) schedule_commit(&cache->committer); } /* *-------------------------------------------------------------- * Main worker loop *-------------------------------------------------------------- */ static void requeue_deferred_bios(struct cache *cache) { struct bio *bio; struct bio_list bios; bio_list_init(&bios); bio_list_merge_init(&bios, &cache->deferred_bios); while ((bio = bio_list_pop(&bios))) { bio->bi_status = BLK_STS_DM_REQUEUE; bio_endio(bio); cond_resched(); } } /* * We want to commit periodically so that not too much * unwritten metadata builds up. */ static void do_waker(struct work_struct *ws) { struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker); policy_tick(cache->policy, true); wake_migration_worker(cache); schedule_commit(&cache->committer); queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD); } static void check_migrations(struct work_struct *ws) { int r; struct policy_work *op; struct cache *cache = container_of(ws, struct cache, migration_worker); enum busy b; for (;;) { b = spare_migration_bandwidth(cache); r = policy_get_background_work(cache->policy, b == IDLE, &op); if (r == -ENODATA) break; if (r) { DMERR_LIMIT("%s: policy_background_work failed", cache_device_name(cache)); break; } r = mg_start(cache, op, NULL); if (r) break; cond_resched(); } } /* *-------------------------------------------------------------- * Target methods *-------------------------------------------------------------- */ /* * This function gets called on the error paths of the constructor, so we * have to cope with a partially initialised struct. */ static void destroy(struct cache *cache) { unsigned int i; mempool_exit(&cache->migration_pool); if (cache->prison) dm_bio_prison_destroy_v2(cache->prison); cancel_delayed_work_sync(&cache->waker); if (cache->wq) destroy_workqueue(cache->wq); if (cache->dirty_bitset) free_bitset(cache->dirty_bitset); if (cache->discard_bitset) free_bitset(cache->discard_bitset); if (cache->copier) dm_kcopyd_client_destroy(cache->copier); if (cache->cmd) dm_cache_metadata_close(cache->cmd); if (cache->metadata_dev) dm_put_device(cache->ti, cache->metadata_dev); if (cache->origin_dev) dm_put_device(cache->ti, cache->origin_dev); if (cache->cache_dev) dm_put_device(cache->ti, cache->cache_dev); if (cache->policy) dm_cache_policy_destroy(cache->policy); for (i = 0; i < cache->nr_ctr_args ; i++) kfree(cache->ctr_args[i]); kfree(cache->ctr_args); bioset_exit(&cache->bs); kfree(cache); } static void cache_dtr(struct dm_target *ti) { struct cache *cache = ti->private; destroy(cache); } static sector_t get_dev_size(struct dm_dev *dev) { return bdev_nr_sectors(dev->bdev); } /*----------------------------------------------------------------*/ /* * Construct a cache device mapping. * * cache <metadata dev> <cache dev> <origin dev> <block size> * <#feature args> [<feature arg>]* * <policy> <#policy args> [<policy arg>]* * * metadata dev : fast device holding the persistent metadata * cache dev : fast device holding cached data blocks * origin dev : slow device holding original data blocks * block size : cache unit size in sectors * * #feature args : number of feature arguments passed * feature args : writethrough. (The default is writeback.) * * policy : the replacement policy to use * #policy args : an even number of policy arguments corresponding * to key/value pairs passed to the policy * policy args : key/value pairs passed to the policy * E.g. 'sequential_threshold 1024' * See cache-policies.txt for details. * * Optional feature arguments are: * writethrough : write through caching that prohibits cache block * content from being different from origin block content. * Without this argument, the default behaviour is to write * back cache block contents later for performance reasons, * so they may differ from the corresponding origin blocks. */ struct cache_args { struct dm_target *ti; struct dm_dev *metadata_dev; struct dm_dev *cache_dev; sector_t cache_sectors; struct dm_dev *origin_dev; sector_t origin_sectors; uint32_t block_size; const char *policy_name; int policy_argc; const char **policy_argv; struct cache_features features; }; static void destroy_cache_args(struct cache_args *ca) { if (ca->metadata_dev) dm_put_device(ca->ti, ca->metadata_dev); if (ca->cache_dev) dm_put_device(ca->ti, ca->cache_dev); if (ca->origin_dev) dm_put_device(ca->ti, ca->origin_dev); kfree(ca); } static bool at_least_one_arg(struct dm_arg_set *as, char **error) { if (!as->argc) { *error = "Insufficient args"; return false; } return true; } static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as, char **error) { int r; sector_t metadata_dev_size; if (!at_least_one_arg(as, error)) return -EINVAL; r = dm_get_device(ca->ti, dm_shift_arg(as), BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->metadata_dev); if (r) { *error = "Error opening metadata device"; return r; } metadata_dev_size = get_dev_size(ca->metadata_dev); if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING) DMWARN("Metadata device %pg is larger than %u sectors: excess space will not be used.", ca->metadata_dev->bdev, THIN_METADATA_MAX_SECTORS); return 0; } static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as, char **error) { int r; if (!at_least_one_arg(as, error)) return -EINVAL; r = dm_get_device(ca->ti, dm_shift_arg(as), BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->cache_dev); if (r) { *error = "Error opening cache device"; return r; } ca->cache_sectors = get_dev_size(ca->cache_dev); return 0; } static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as, char **error) { int r; if (!at_least_one_arg(as, error)) return -EINVAL; r = dm_get_device(ca->ti, dm_shift_arg(as), BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->origin_dev); if (r) { *error = "Error opening origin device"; return r; } ca->origin_sectors = get_dev_size(ca->origin_dev); if (ca->ti->len > ca->origin_sectors) { *error = "Device size larger than cached device"; return -EINVAL; } return 0; } static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as, char **error) { unsigned long block_size; if (!at_least_one_arg(as, error)) return -EINVAL; if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size || block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS || block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS || block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) { *error = "Invalid data block size"; return -EINVAL; } if (block_size > ca->cache_sectors) { *error = "Data block size is larger than the cache device"; return -EINVAL; } ca->block_size = block_size; return 0; } static void init_features(struct cache_features *cf) { cf->mode = CM_WRITE; cf->io_mode = CM_IO_WRITEBACK; cf->metadata_version = 1; cf->discard_passdown = true; } static int parse_features(struct cache_args *ca, struct dm_arg_set *as, char **error) { static const struct dm_arg _args[] = { {0, 3, "Invalid number of cache feature arguments"}, }; int r, mode_ctr = 0; unsigned int argc; const char *arg; struct cache_features *cf = &ca->features; init_features(cf); r = dm_read_arg_group(_args, as, &argc, error); if (r) return -EINVAL; while (argc--) { arg = dm_shift_arg(as); if (!strcasecmp(arg, "writeback")) { cf->io_mode = CM_IO_WRITEBACK; mode_ctr++; } else if (!strcasecmp(arg, "writethrough")) { cf->io_mode = CM_IO_WRITETHROUGH; mode_ctr++; } else if (!strcasecmp(arg, "passthrough")) { cf->io_mode = CM_IO_PASSTHROUGH; mode_ctr++; } else if (!strcasecmp(arg, "metadata2")) cf->metadata_version = 2; else if (!strcasecmp(arg, "no_discard_passdown")) cf->discard_passdown = false; else { *error = "Unrecognised cache feature requested"; return -EINVAL; } } if (mode_ctr > 1) { *error = "Duplicate cache io_mode features requested"; return -EINVAL; } return 0; } static int parse_policy(struct cache_args *ca, struct dm_arg_set *as, char **error) { static const struct dm_arg _args[] = { {0, 1024, "Invalid number of policy arguments"}, }; int r; if (!at_least_one_arg(as, error)) return -EINVAL; ca->policy_name = dm_shift_arg(as); r = dm_read_arg_group(_args, as, &ca->policy_argc, error); if (r) return -EINVAL; ca->policy_argv = (const char **)as->argv; dm_consume_args(as, ca->policy_argc); return 0; } static int parse_cache_args(struct cache_args *ca, int argc, char **argv, char **error) { int r; struct dm_arg_set as; as.argc = argc; as.argv = argv; r = parse_metadata_dev(ca, &as, error); if (r) return r; r = parse_cache_dev(ca, &as, error); if (r) return r; r = parse_origin_dev(ca, &as, error); if (r) return r; r = parse_block_size(ca, &as, error); if (r) return r; r = parse_features(ca, &as, error); if (r) return r; r = parse_policy(ca, &as, error); if (r) return r; return 0; } /*----------------------------------------------------------------*/ static struct kmem_cache *migration_cache; #define NOT_CORE_OPTION 1 static int process_config_option(struct cache *cache, const char *key, const char *value) { unsigned long tmp; if (!strcasecmp(key, "migration_threshold")) { if (kstrtoul(value, 10, &tmp)) return -EINVAL; cache->migration_threshold = tmp; return 0; } return NOT_CORE_OPTION; } static int set_config_value(struct cache *cache, const char *key, const char *value) { int r = process_config_option(cache, key, value); if (r == NOT_CORE_OPTION) r = policy_set_config_value(cache->policy, key, value); if (r) DMWARN("bad config value for %s: %s", key, value); return r; } static int set_config_values(struct cache *cache, int argc, const char **argv) { int r = 0; if (argc & 1) { DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs."); return -EINVAL; } while (argc) { r = set_config_value(cache, argv[0], argv[1]); if (r) break; argc -= 2; argv += 2; } return r; } static int create_cache_policy(struct cache *cache, struct cache_args *ca, char **error) { struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name, cache->cache_size, cache->origin_sectors, cache->sectors_per_block); if (IS_ERR(p)) { *error = "Error creating cache's policy"; return PTR_ERR(p); } cache->policy = p; BUG_ON(!cache->policy); return 0; } /* * We want the discard block size to be at least the size of the cache * block size and have no more than 2^14 discard blocks across the origin. */ #define MAX_DISCARD_BLOCKS (1 << 14) static bool too_many_discard_blocks(sector_t discard_block_size, sector_t origin_size) { (void) sector_div(origin_size, discard_block_size); return origin_size > MAX_DISCARD_BLOCKS; } static sector_t calculate_discard_block_size(sector_t cache_block_size, sector_t origin_size) { sector_t discard_block_size = cache_block_size; if (origin_size) while (too_many_discard_blocks(discard_block_size, origin_size)) discard_block_size *= 2; return discard_block_size; } static void set_cache_size(struct cache *cache, dm_cblock_t size) { dm_block_t nr_blocks = from_cblock(size); if (nr_blocks > (1 << 20) && cache->cache_size != size) DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n" "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n" "Please consider increasing the cache block size to reduce the overall cache block count.", (unsigned long long) nr_blocks); cache->cache_size = size; } #define DEFAULT_MIGRATION_THRESHOLD 2048 static int cache_create(struct cache_args *ca, struct cache **result) { int r = 0; char **error = &ca->ti->error; struct cache *cache; struct dm_target *ti = ca->ti; dm_block_t origin_blocks; struct dm_cache_metadata *cmd; bool may_format = ca->features.mode == CM_WRITE; cache = kzalloc(sizeof(*cache), GFP_KERNEL); if (!cache) return -ENOMEM; cache->ti = ca->ti; ti->private = cache; ti->accounts_remapped_io = true; ti->num_flush_bios = 2; ti->flush_supported = true; ti->num_discard_bios = 1; ti->discards_supported = true; ti->per_io_data_size = sizeof(struct per_bio_data); cache->features = ca->features; if (writethrough_mode(cache)) { /* Create bioset for writethrough bios issued to origin */ r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0); if (r) goto bad; } cache->metadata_dev = ca->metadata_dev; cache->origin_dev = ca->origin_dev; cache->cache_dev = ca->cache_dev; ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL; origin_blocks = cache->origin_sectors = ca->origin_sectors; origin_blocks = block_div(origin_blocks, ca->block_size); cache->origin_blocks = to_oblock(origin_blocks); cache->sectors_per_block = ca->block_size; if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) { r = -EINVAL; goto bad; } if (ca->block_size & (ca->block_size - 1)) { dm_block_t cache_size = ca->cache_sectors; cache->sectors_per_block_shift = -1; cache_size = block_div(cache_size, ca->block_size); set_cache_size(cache, to_cblock(cache_size)); } else { cache->sectors_per_block_shift = __ffs(ca->block_size); set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift)); } r = create_cache_policy(cache, ca, error); if (r) goto bad; cache->policy_nr_args = ca->policy_argc; cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD; r = set_config_values(cache, ca->policy_argc, ca->policy_argv); if (r) { *error = "Error setting cache policy's config values"; goto bad; } cmd = dm_cache_metadata_open(cache->metadata_dev->bdev, ca->block_size, may_format, dm_cache_policy_get_hint_size(cache->policy), ca->features.metadata_version); if (IS_ERR(cmd)) { *error = "Error creating metadata object"; r = PTR_ERR(cmd); goto bad; } cache->cmd = cmd; set_cache_mode(cache, CM_WRITE); if (get_cache_mode(cache) != CM_WRITE) { *error = "Unable to get write access to metadata, please check/repair metadata."; r = -EINVAL; goto bad; } if (passthrough_mode(cache)) { bool all_clean; r = dm_cache_metadata_all_clean(cache->cmd, &all_clean); if (r) { *error = "dm_cache_metadata_all_clean() failed"; goto bad; } if (!all_clean) { *error = "Cannot enter passthrough mode unless all blocks are clean"; r = -EINVAL; goto bad; } policy_allow_migrations(cache->policy, false); } spin_lock_init(&cache->lock); bio_list_init(&cache->deferred_bios); atomic_set(&cache->nr_allocated_migrations, 0); atomic_set(&cache->nr_io_migrations, 0); init_waitqueue_head(&cache->migration_wait); r = -ENOMEM; atomic_set(&cache->nr_dirty, 0); cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size)); if (!cache->dirty_bitset) { *error = "could not allocate dirty bitset"; goto bad; } clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size)); cache->discard_block_size = calculate_discard_block_size(cache->sectors_per_block, cache->origin_sectors); cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors, cache->discard_block_size)); cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks)); if (!cache->discard_bitset) { *error = "could not allocate discard bitset"; goto bad; } clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks)); cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle); if (IS_ERR(cache->copier)) { *error = "could not create kcopyd client"; r = PTR_ERR(cache->copier); goto bad; } cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0); if (!cache->wq) { *error = "could not create workqueue for metadata object"; goto bad; } INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios); INIT_WORK(&cache->migration_worker, check_migrations); INIT_DELAYED_WORK(&cache->waker, do_waker); cache->prison = dm_bio_prison_create_v2(cache->wq); if (!cache->prison) { *error = "could not create bio prison"; goto bad; } r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE, migration_cache); if (r) { *error = "Error creating cache's migration mempool"; goto bad; } cache->need_tick_bio = true; cache->sized = false; cache->invalidate = false; cache->commit_requested = false; cache->loaded_mappings = false; cache->loaded_discards = false; load_stats(cache); atomic_set(&cache->stats.demotion, 0); atomic_set(&cache->stats.promotion, 0); atomic_set(&cache->stats.copies_avoided, 0); atomic_set(&cache->stats.cache_cell_clash, 0); atomic_set(&cache->stats.commit_count, 0); atomic_set(&cache->stats.discard_count, 0); spin_lock_init(&cache->invalidation_lock); INIT_LIST_HEAD(&cache->invalidation_requests); batcher_init(&cache->committer, commit_op, cache, issue_op, cache, cache->wq); dm_iot_init(&cache->tracker); init_rwsem(&cache->background_work_lock); prevent_background_work(cache); *result = cache; return 0; bad: destroy(cache); return r; } static int copy_ctr_args(struct cache *cache, int argc, const char **argv) { unsigned int i; const char **copy; copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL); if (!copy) return -ENOMEM; for (i = 0; i < argc; i++) { copy[i] = kstrdup(argv[i], GFP_KERNEL); if (!copy[i]) { while (i--) kfree(copy[i]); kfree(copy); return -ENOMEM; } } cache->nr_ctr_args = argc; cache->ctr_args = copy; return 0; } static int cache_ctr(struct dm_target *ti, unsigned int argc, char **argv) { int r = -EINVAL; struct cache_args *ca; struct cache *cache = NULL; ca = kzalloc(sizeof(*ca), GFP_KERNEL); if (!ca) { ti->error = "Error allocating memory for cache"; return -ENOMEM; } ca->ti = ti; r = parse_cache_args(ca, argc, argv, &ti->error); if (r) goto out; r = cache_create(ca, &cache); if (r) goto out; r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3); if (r) { destroy(cache); goto out; } ti->private = cache; out: destroy_cache_args(ca); return r; } /*----------------------------------------------------------------*/ static int cache_map(struct dm_target *ti, struct bio *bio) { struct cache *cache = ti->private; int r; bool commit_needed; dm_oblock_t block = get_bio_block(cache, bio); init_per_bio_data(bio); if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) { /* * This can only occur if the io goes to a partial block at * the end of the origin device. We don't cache these. * Just remap to the origin and carry on. */ remap_to_origin(cache, bio); accounted_begin(cache, bio); return DM_MAPIO_REMAPPED; } if (discard_or_flush(bio)) { defer_bio(cache, bio); return DM_MAPIO_SUBMITTED; } r = map_bio(cache, bio, block, &commit_needed); if (commit_needed) schedule_commit(&cache->committer); return r; } static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error) { struct cache *cache = ti->private; unsigned long flags; struct per_bio_data *pb = get_per_bio_data(bio); if (pb->tick) { policy_tick(cache->policy, false); spin_lock_irqsave(&cache->lock, flags); cache->need_tick_bio = true; spin_unlock_irqrestore(&cache->lock, flags); } bio_drop_shared_lock(cache, bio); accounted_complete(cache, bio); return DM_ENDIO_DONE; } static int write_dirty_bitset(struct cache *cache) { int r; if (get_cache_mode(cache) >= CM_READ_ONLY) return -EINVAL; r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset); if (r) metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r); return r; } static int write_discard_bitset(struct cache *cache) { unsigned int i, r; if (get_cache_mode(cache) >= CM_READ_ONLY) return -EINVAL; r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size, cache->discard_nr_blocks); if (r) { DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r); return r; } for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) { r = dm_cache_set_discard(cache->cmd, to_dblock(i), is_discarded(cache, to_dblock(i))); if (r) { metadata_operation_failed(cache, "dm_cache_set_discard", r); return r; } } return 0; } static int write_hints(struct cache *cache) { int r; if (get_cache_mode(cache) >= CM_READ_ONLY) return -EINVAL; r = dm_cache_write_hints(cache->cmd, cache->policy); if (r) { metadata_operation_failed(cache, "dm_cache_write_hints", r); return r; } return 0; } /* * returns true on success */ static bool sync_metadata(struct cache *cache) { int r1, r2, r3, r4; r1 = write_dirty_bitset(cache); if (r1) DMERR("%s: could not write dirty bitset", cache_device_name(cache)); r2 = write_discard_bitset(cache); if (r2) DMERR("%s: could not write discard bitset", cache_device_name(cache)); save_stats(cache); r3 = write_hints(cache); if (r3) DMERR("%s: could not write hints", cache_device_name(cache)); /* * If writing the above metadata failed, we still commit, but don't * set the clean shutdown flag. This will effectively force every * dirty bit to be set on reload. */ r4 = commit(cache, !r1 && !r2 && !r3); if (r4) DMERR("%s: could not write cache metadata", cache_device_name(cache)); return !r1 && !r2 && !r3 && !r4; } static void cache_postsuspend(struct dm_target *ti) { struct cache *cache = ti->private; prevent_background_work(cache); BUG_ON(atomic_read(&cache->nr_io_migrations)); cancel_delayed_work_sync(&cache->waker); drain_workqueue(cache->wq); WARN_ON(cache->tracker.in_flight); /* * If it's a flush suspend there won't be any deferred bios, so this * call is harmless. */ requeue_deferred_bios(cache); if (get_cache_mode(cache) == CM_WRITE) (void) sync_metadata(cache); } static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock, bool dirty, uint32_t hint, bool hint_valid) { struct cache *cache = context; if (dirty) { set_bit(from_cblock(cblock), cache->dirty_bitset); atomic_inc(&cache->nr_dirty); } else clear_bit(from_cblock(cblock), cache->dirty_bitset); return policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid); } /* * The discard block size in the on disk metadata is not * 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. */ struct discard_load_info { struct cache *cache; /* * These blocks are sized using the on disk dblock size, rather * than the current one. */ dm_block_t block_size; dm_block_t discard_begin, discard_end; }; static void discard_load_info_init(struct cache *cache, struct discard_load_info *li) { li->cache = cache; li->discard_begin = li->discard_end = 0; } static void set_discard_range(struct discard_load_info *li) { sector_t b, e; if (li->discard_begin == li->discard_end) return; /* * Convert to sectors. */ b = li->discard_begin * li->block_size; e = li->discard_end * li->block_size; /* * Then convert back to the current dblock size. */ b = dm_sector_div_up(b, li->cache->discard_block_size); sector_div(e, li->cache->discard_block_size); /* * The origin may have shrunk, so we need to check we're still in * bounds. */ if (e > from_dblock(li->cache->discard_nr_blocks)) e = from_dblock(li->cache->discard_nr_blocks); for (; b < e; b++) set_discard(li->cache, to_dblock(b)); } static int load_discard(void *context, sector_t discard_block_size, dm_dblock_t dblock, bool discard) { struct discard_load_info *li = context; li->block_size = discard_block_size; if (discard) { if (from_dblock(dblock) == li->discard_end) /* * We're already in a discard range, just extend it. */ li->discard_end = li->discard_end + 1ULL; else { /* * Emit the old range and start a new one. */ set_discard_range(li); li->discard_begin = from_dblock(dblock); li->discard_end = li->discard_begin + 1ULL; } } else { set_discard_range(li); li->discard_begin = li->discard_end = 0; } return 0; } static dm_cblock_t get_cache_dev_size(struct cache *cache) { sector_t size = get_dev_size(cache->cache_dev); (void) sector_div(size, cache->sectors_per_block); return to_cblock(size); } static bool can_resize(struct cache *cache, dm_cblock_t new_size) { if (from_cblock(new_size) > from_cblock(cache->cache_size)) { if (cache->sized) { DMERR("%s: unable to extend cache due to missing cache table reload", cache_device_name(cache)); return false; } } /* * We can't drop a dirty block when shrinking the cache. */ while (from_cblock(new_size) < from_cblock(cache->cache_size)) { new_size = to_cblock(from_cblock(new_size) + 1); if (is_dirty(cache, new_size)) { DMERR("%s: unable to shrink cache; cache block %llu is dirty", cache_device_name(cache), (unsigned long long) from_cblock(new_size)); return false; } } return true; } static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size) { int r; r = dm_cache_resize(cache->cmd, new_size); if (r) { DMERR("%s: could not resize cache metadata", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_resize", r); return r; } set_cache_size(cache, new_size); return 0; } static int cache_preresume(struct dm_target *ti) { int r = 0; struct cache *cache = ti->private; dm_cblock_t csize = get_cache_dev_size(cache); /* * Check to see if the cache has resized. */ if (!cache->sized) { r = resize_cache_dev(cache, csize); if (r) return r; cache->sized = true; } else if (csize != cache->cache_size) { if (!can_resize(cache, csize)) return -EINVAL; r = resize_cache_dev(cache, csize); if (r) return r; } if (!cache->loaded_mappings) { r = dm_cache_load_mappings(cache->cmd, cache->policy, load_mapping, cache); if (r) { DMERR("%s: could not load cache mappings", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_load_mappings", r); return r; } cache->loaded_mappings = true; } if (!cache->loaded_discards) { struct discard_load_info li; /* * The discard bitset could have been resized, or the * discard block size changed. To be safe we start by * setting every dblock to not discarded. */ clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks)); discard_load_info_init(cache, &li); r = dm_cache_load_discards(cache->cmd, load_discard, &li); if (r) { DMERR("%s: could not load origin discards", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_load_discards", r); return r; } set_discard_range(&li); cache->loaded_discards = true; } return r; } static void cache_resume(struct dm_target *ti) { struct cache *cache = ti->private; cache->need_tick_bio = true; allow_background_work(cache); do_waker(&cache->waker.work); } static void emit_flags(struct cache *cache, char *result, unsigned int maxlen, ssize_t *sz_ptr) { ssize_t sz = *sz_ptr; struct cache_features *cf = &cache->features; unsigned int count = (cf->metadata_version == 2) + !cf->discard_passdown + 1; DMEMIT("%u ", count); if (cf->metadata_version == 2) DMEMIT("metadata2 "); if (writethrough_mode(cache)) DMEMIT("writethrough "); else if (passthrough_mode(cache)) DMEMIT("passthrough "); else if (writeback_mode(cache)) DMEMIT("writeback "); else { DMEMIT("unknown "); DMERR("%s: internal error: unknown io mode: %d", cache_device_name(cache), (int) cf->io_mode); } if (!cf->discard_passdown) DMEMIT("no_discard_passdown "); *sz_ptr = sz; } /* * Status format: * * <metadata block size> <#used metadata blocks>/<#total metadata blocks> * <cache block size> <#used cache blocks>/<#total cache blocks> * <#read hits> <#read misses> <#write hits> <#write misses> * <#demotions> <#promotions> <#dirty> * <#features> <features>* * <#core args> <core args> * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check> */ static void cache_status(struct dm_target *ti, status_type_t type, unsigned int status_flags, char *result, unsigned int maxlen) { int r = 0; unsigned int i; ssize_t sz = 0; dm_block_t nr_free_blocks_metadata = 0; dm_block_t nr_blocks_metadata = 0; char buf[BDEVNAME_SIZE]; struct cache *cache = ti->private; dm_cblock_t residency; bool needs_check; switch (type) { case STATUSTYPE_INFO: if (get_cache_mode(cache) == CM_FAIL) { DMEMIT("Fail"); break; } /* Commit to ensure statistics aren't out-of-date */ if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) (void) commit(cache, false); r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata); if (r) { DMERR("%s: dm_cache_get_free_metadata_block_count returned %d", cache_device_name(cache), r); goto err; } r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata); if (r) { DMERR("%s: dm_cache_get_metadata_dev_size returned %d", cache_device_name(cache), r); goto err; } residency = policy_residency(cache->policy); DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ", (unsigned int)DM_CACHE_METADATA_BLOCK_SIZE, (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata), (unsigned long long)nr_blocks_metadata, (unsigned long long)cache->sectors_per_block, (unsigned long long) from_cblock(residency), (unsigned long long) from_cblock(cache->cache_size), (unsigned int) atomic_read(&cache->stats.read_hit), (unsigned int) atomic_read(&cache->stats.read_miss), (unsigned int) atomic_read(&cache->stats.write_hit), (unsigned int) atomic_read(&cache->stats.write_miss), (unsigned int) atomic_read(&cache->stats.demotion), (unsigned int) atomic_read(&cache->stats.promotion), (unsigned long) atomic_read(&cache->nr_dirty)); emit_flags(cache, result, maxlen, &sz); DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold); DMEMIT("%s ", dm_cache_policy_get_name(cache->policy)); if (sz < maxlen) { r = policy_emit_config_values(cache->policy, result, maxlen, &sz); if (r) DMERR("%s: policy_emit_config_values returned %d", cache_device_name(cache), r); } if (get_cache_mode(cache) == CM_READ_ONLY) DMEMIT("ro "); else DMEMIT("rw "); r = dm_cache_metadata_needs_check(cache->cmd, &needs_check); if (r || needs_check) DMEMIT("needs_check "); else DMEMIT("- "); break; case STATUSTYPE_TABLE: format_dev_t(buf, cache->metadata_dev->bdev->bd_dev); DMEMIT("%s ", buf); format_dev_t(buf, cache->cache_dev->bdev->bd_dev); DMEMIT("%s ", buf); format_dev_t(buf, cache->origin_dev->bdev->bd_dev); DMEMIT("%s", buf); for (i = 0; i < cache->nr_ctr_args - 1; i++) DMEMIT(" %s", cache->ctr_args[i]); if (cache->nr_ctr_args) DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]); break; case STATUSTYPE_IMA: DMEMIT_TARGET_NAME_VERSION(ti->type); if (get_cache_mode(cache) == CM_FAIL) DMEMIT(",metadata_mode=fail"); else if (get_cache_mode(cache) == CM_READ_ONLY) DMEMIT(",metadata_mode=ro"); else DMEMIT(",metadata_mode=rw"); format_dev_t(buf, cache->metadata_dev->bdev->bd_dev); DMEMIT(",cache_metadata_device=%s", buf); format_dev_t(buf, cache->cache_dev->bdev->bd_dev); DMEMIT(",cache_device=%s", buf); format_dev_t(buf, cache->origin_dev->bdev->bd_dev); DMEMIT(",cache_origin_device=%s", buf); DMEMIT(",writethrough=%c", writethrough_mode(cache) ? 'y' : 'n'); DMEMIT(",writeback=%c", writeback_mode(cache) ? 'y' : 'n'); DMEMIT(",passthrough=%c", passthrough_mode(cache) ? 'y' : 'n'); DMEMIT(",metadata2=%c", cache->features.metadata_version == 2 ? 'y' : 'n'); DMEMIT(",no_discard_passdown=%c", cache->features.discard_passdown ? 'n' : 'y'); DMEMIT(";"); break; } return; err: DMEMIT("Error"); } /* * Defines a range of cblocks, begin to (end - 1) are in the range. end is * the one-past-the-end value. */ struct cblock_range { dm_cblock_t begin; dm_cblock_t end; }; /* * A cache block range can take two forms: * * i) A single cblock, eg. '3456' * ii) A begin and end cblock with a dash between, eg. 123-234 */ static int parse_cblock_range(struct cache *cache, const char *str, struct cblock_range *result) { char dummy; uint64_t b, e; int r; /* * Try and parse form (ii) first. */ r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy); if (r < 0) return r; if (r == 2) { result->begin = to_cblock(b); result->end = to_cblock(e); return 0; } /* * That didn't work, try form (i). */ r = sscanf(str, "%llu%c", &b, &dummy); if (r < 0) return r; if (r == 1) { result->begin = to_cblock(b); result->end = to_cblock(from_cblock(result->begin) + 1u); return 0; } DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str); return -EINVAL; } static int validate_cblock_range(struct cache *cache, struct cblock_range *range) { uint64_t b = from_cblock(range->begin); uint64_t e = from_cblock(range->end); uint64_t n = from_cblock(cache->cache_size); if (b >= n) { DMERR("%s: begin cblock out of range: %llu >= %llu", cache_device_name(cache), b, n); return -EINVAL; } if (e > n) { DMERR("%s: end cblock out of range: %llu > %llu", cache_device_name(cache), e, n); return -EINVAL; } if (b >= e) { DMERR("%s: invalid cblock range: %llu >= %llu", cache_device_name(cache), b, e); return -EINVAL; } return 0; } static inline dm_cblock_t cblock_succ(dm_cblock_t b) { return to_cblock(from_cblock(b) + 1); } static int request_invalidation(struct cache *cache, struct cblock_range *range) { int r = 0; /* * We don't need to do any locking here because we know we're in * passthrough mode. There's is potential for a race between an * invalidation triggered by an io and an invalidation message. This * is harmless, we must not worry if the policy call fails. */ while (range->begin != range->end) { r = invalidate_cblock(cache, range->begin); if (r) return r; range->begin = cblock_succ(range->begin); } cache->commit_requested = true; return r; } static int process_invalidate_cblocks_message(struct cache *cache, unsigned int count, const char **cblock_ranges) { int r = 0; unsigned int i; struct cblock_range range; if (!passthrough_mode(cache)) { DMERR("%s: cache has to be in passthrough mode for invalidation", cache_device_name(cache)); return -EPERM; } for (i = 0; i < count; i++) { r = parse_cblock_range(cache, cblock_ranges[i], &range); if (r) break; r = validate_cblock_range(cache, &range); if (r) break; /* * Pass begin and end origin blocks to the worker and wake it. */ r = request_invalidation(cache, &range); if (r) break; } return r; } /* * Supports * "<key> <value>" * and * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]* * * The key migration_threshold is supported by the cache target core. */ static int cache_message(struct dm_target *ti, unsigned int argc, char **argv, char *result, unsigned int maxlen) { struct cache *cache = ti->private; if (!argc) return -EINVAL; if (get_cache_mode(cache) >= CM_READ_ONLY) { DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode", cache_device_name(cache)); return -EOPNOTSUPP; } if (!strcasecmp(argv[0], "invalidate_cblocks")) return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1); if (argc != 2) return -EINVAL; return set_config_value(cache, argv[0], argv[1]); } static int cache_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data) { int r = 0; struct cache *cache = ti->private; r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data); if (!r) r = fn(ti, cache->origin_dev, 0, ti->len, data); return r; } /* * If discard_passdown was enabled verify that the origin device * supports discards. Disable discard_passdown if not. */ static void disable_passdown_if_not_supported(struct cache *cache) { struct block_device *origin_bdev = cache->origin_dev->bdev; struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits; const char *reason = NULL; if (!cache->features.discard_passdown) return; if (!bdev_max_discard_sectors(origin_bdev)) reason = "discard unsupported"; else if (origin_limits->max_discard_sectors < cache->sectors_per_block) reason = "max discard sectors smaller than a block"; if (reason) { DMWARN("Origin device (%pg) %s: Disabling discard passdown.", origin_bdev, reason); cache->features.discard_passdown = false; } } static void set_discard_limits(struct cache *cache, struct queue_limits *limits) { struct block_device *origin_bdev = cache->origin_dev->bdev; struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits; if (!cache->features.discard_passdown) { /* No passdown is done so setting own virtual limits */ limits->max_hw_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024, cache->origin_sectors); limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT; return; } /* * cache_iterate_devices() is stacking both origin and fast device limits * but discards aren't passed to fast device, so inherit origin's limits. */ limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors; limits->discard_granularity = origin_limits->discard_granularity; limits->discard_alignment = origin_limits->discard_alignment; limits->discard_misaligned = origin_limits->discard_misaligned; } static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits) { struct cache *cache = ti->private; uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT; /* * If the system-determined stacked limits are compatible with the * cache's blocksize (io_opt is a factor) do not override them. */ if (io_opt_sectors < cache->sectors_per_block || do_div(io_opt_sectors, cache->sectors_per_block)) { blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT); blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT); } disable_passdown_if_not_supported(cache); set_discard_limits(cache, limits); } /*----------------------------------------------------------------*/ static struct target_type cache_target = { .name = "cache", .version = {2, 2, 0}, .module = THIS_MODULE, .ctr = cache_ctr, .dtr = cache_dtr, .map = cache_map, .end_io = cache_end_io, .postsuspend = cache_postsuspend, .preresume = cache_preresume, .resume = cache_resume, .status = cache_status, .message = cache_message, .iterate_devices = cache_iterate_devices, .io_hints = cache_io_hints, }; static int __init dm_cache_init(void) { int r; migration_cache = KMEM_CACHE(dm_cache_migration, 0); if (!migration_cache) return -ENOMEM; r = dm_register_target(&cache_target); if (r) { kmem_cache_destroy(migration_cache); return r; } return 0; } static void __exit dm_cache_exit(void) { dm_unregister_target(&cache_target); kmem_cache_destroy(migration_cache); } module_init(dm_cache_init); module_exit(dm_cache_exit); MODULE_DESCRIPTION(DM_NAME " cache target"); MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>"); MODULE_LICENSE("GPL");
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