/* * Copyright (C) 2012 Red Hat. All rights reserved. * * This file is released under the GPL. */ #include "dm.h" #include "dm-bio-prison.h" #include "dm-bio-record.h" #include "dm-cache-metadata.h" #include #include #include #include #include #include #include #include #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"); /*----------------------------------------------------------------*/ #define IOT_RESOLUTION 4 struct io_tracker { spinlock_t lock; /* * Sectors of in-flight IO. */ sector_t in_flight; /* * The time, in jiffies, when this device became idle (if it is * indeed idle). */ unsigned long idle_time; unsigned long last_update_time; }; static void iot_init(struct io_tracker *iot) { spin_lock_init(&iot->lock); iot->in_flight = 0ul; iot->idle_time = 0ul; iot->last_update_time = jiffies; } static bool __iot_idle_for(struct io_tracker *iot, unsigned long jifs) { if (iot->in_flight) return false; return time_after(jiffies, iot->idle_time + jifs); } static bool iot_idle_for(struct io_tracker *iot, unsigned long jifs) { bool r; unsigned long flags; spin_lock_irqsave(&iot->lock, flags); r = __iot_idle_for(iot, jifs); spin_unlock_irqrestore(&iot->lock, flags); return r; } static void iot_io_begin(struct io_tracker *iot, sector_t len) { unsigned long flags; spin_lock_irqsave(&iot->lock, flags); iot->in_flight += len; spin_unlock_irqrestore(&iot->lock, flags); } static void __iot_io_end(struct io_tracker *iot, sector_t len) { iot->in_flight -= len; if (!iot->in_flight) iot->idle_time = jiffies; } static void iot_io_end(struct io_tracker *iot, sector_t len) { unsigned long flags; spin_lock_irqsave(&iot->lock, flags); __iot_io_end(iot, len); spin_unlock_irqrestore(&iot->lock, flags); } /*----------------------------------------------------------------*/ /* * 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 */ /*----------------------------------------------------------------*/ /* * 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; }; 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 copies_avoided; atomic_t cache_cell_clash; atomic_t commit_count; atomic_t discard_count; }; /* * 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; }; struct invalidation_request { struct list_head list; struct cblock_range *cblocks; atomic_t complete; int err; wait_queue_head_t result_wait; }; struct cache { struct dm_target *ti; struct dm_target_callbacks callbacks; 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; /* * Fields for converting from sectors to blocks. */ sector_t sectors_per_block; int sectors_per_block_shift; spinlock_t lock; struct list_head deferred_cells; struct bio_list deferred_bios; struct bio_list deferred_flush_bios; struct bio_list deferred_writethrough_bios; struct list_head quiesced_migrations; struct list_head completed_migrations; struct list_head need_commit_migrations; 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; wait_queue_head_t quiescing_wait; atomic_t quiescing; atomic_t quiescing_ack; /* * cache_size entries, dirty if set */ atomic_t nr_dirty; unsigned long *dirty_bitset; /* * 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 nr_ctr_args; const char **ctr_args; struct dm_kcopyd_client *copier; struct workqueue_struct *wq; struct work_struct worker; struct delayed_work waker; unsigned long last_commit_jiffies; struct dm_bio_prison *prison; struct dm_deferred_set *all_io_ds; mempool_t *migration_pool; struct dm_cache_policy *policy; unsigned policy_nr_args; bool need_tick_bio:1; bool sized:1; bool invalidate:1; bool commit_requested:1; bool loaded_mappings:1; bool loaded_discards:1; /* * Cache features such as write-through. */ struct cache_features features; struct cache_stats stats; /* * Invalidation fields. */ spinlock_t invalidation_lock; struct list_head invalidation_requests; struct io_tracker origin_tracker; }; struct per_bio_data { bool tick:1; unsigned req_nr:2; struct dm_deferred_entry *all_io_entry; struct dm_hook_info hook_info; sector_t len; /* * writethrough fields. These MUST remain at the end of this * structure and the 'cache' member must be the first as it * is used to determine the offset of the writethrough fields. */ struct cache *cache; dm_cblock_t cblock; struct dm_bio_details bio_details; }; struct dm_cache_migration { struct list_head list; struct cache *cache; unsigned long start_jiffies; dm_oblock_t old_oblock; dm_oblock_t new_oblock; dm_cblock_t cblock; bool err:1; bool discard:1; bool writeback:1; bool demote:1; bool promote:1; bool requeue_holder:1; bool invalidate:1; struct dm_bio_prison_cell *old_ocell; struct dm_bio_prison_cell *new_ocell; }; /* * Processing a bio in the worker thread may require these memory * allocations. We prealloc to avoid deadlocks (the same worker thread * frees them back to the mempool). */ struct prealloc { struct dm_cache_migration *mg; struct dm_bio_prison_cell *cell1; struct dm_bio_prison_cell *cell2; }; static enum cache_metadata_mode get_cache_mode(struct cache *cache); static void wake_worker(struct cache *cache) { queue_work(cache->wq, &cache->worker); } /*----------------------------------------------------------------*/ static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache) { /* FIXME: change to use a local slab. */ return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT); } static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell) { dm_bio_prison_free_cell(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_NOWAIT); if (mg) { mg->cache = cache; atomic_inc(&mg->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 int prealloc_data_structs(struct cache *cache, struct prealloc *p) { if (!p->mg) { p->mg = alloc_migration(cache); if (!p->mg) return -ENOMEM; } if (!p->cell1) { p->cell1 = alloc_prison_cell(cache); if (!p->cell1) return -ENOMEM; } if (!p->cell2) { p->cell2 = alloc_prison_cell(cache); if (!p->cell2) return -ENOMEM; } return 0; } static void prealloc_free_structs(struct cache *cache, struct prealloc *p) { if (p->cell2) free_prison_cell(cache, p->cell2); if (p->cell1) free_prison_cell(cache, p->cell1); if (p->mg) free_migration(p->mg); } static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p) { struct dm_cache_migration *mg = p->mg; BUG_ON(!mg); p->mg = NULL; return mg; } /* * You must have a cell within the prealloc struct to return. If not this * function will BUG() rather than returning NULL. */ static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p) { struct dm_bio_prison_cell *r = NULL; if (p->cell1) { r = p->cell1; p->cell1 = NULL; } else if (p->cell2) { r = p->cell2; p->cell2 = NULL; } else BUG(); return r; } /* * You can't have more than two cells in a prealloc struct. BUG() will be * called if you try and overfill. */ static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell) { if (!p->cell2) p->cell2 = cell; else if (!p->cell1) p->cell1 = cell; else BUG(); } /*----------------------------------------------------------------*/ static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key *key) { key->virtual = 0; key->dev = 0; key->block_begin = from_oblock(begin); key->block_end = from_oblock(end); } /* * The caller hands in a preallocated cell, and a free function for it. * The cell will be freed if there's an error, or if it wasn't used because * a cell with that key already exists. */ typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell); static int bio_detain_range(struct cache *cache, dm_oblock_t oblock_begin, dm_oblock_t oblock_end, struct bio *bio, struct dm_bio_prison_cell *cell_prealloc, cell_free_fn free_fn, void *free_context, struct dm_bio_prison_cell **cell_result) { int r; struct dm_cell_key key; build_key(oblock_begin, oblock_end, &key); r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result); if (r) free_fn(free_context, cell_prealloc); return r; } static int bio_detain(struct cache *cache, dm_oblock_t oblock, struct bio *bio, struct dm_bio_prison_cell *cell_prealloc, cell_free_fn free_fn, void *free_context, struct dm_bio_prison_cell **cell_result) { dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL); return bio_detain_range(cache, oblock, end, bio, cell_prealloc, free_fn, free_context, cell_result); } static int get_cell(struct cache *cache, dm_oblock_t oblock, struct prealloc *structs, struct dm_bio_prison_cell **cell_result) { int r; struct dm_cell_key key; struct dm_bio_prison_cell *cell_prealloc; cell_prealloc = prealloc_get_cell(structs); build_key(oblock, to_oblock(from_oblock(oblock) + 1ULL), &key); r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result); if (r) prealloc_put_cell(structs, cell_prealloc); 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_oblock_t oblock, 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, oblock); } } static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock) { if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) { policy_clear_dirty(cache->policy, oblock); if (atomic_dec_return(&cache->nr_dirty) == 0) dm_table_event(cache->ti->table); } } /*----------------------------------------------------------------*/ static bool block_size_is_power_of_two(struct cache *cache) { return cache->sectors_per_block_shift >= 0; } /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */ #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6 __always_inline #endif 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 dm_oblock_t dblock_to_oblock(struct cache *cache, dm_dblock_t dblock) { return to_oblock(from_dblock(dblock) * oblocks_per_dblock(cache)); } static void set_discard(struct cache *cache, dm_dblock_t b) { unsigned long flags; BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks)); atomic_inc(&cache->stats.discard_count); spin_lock_irqsave(&cache->lock, flags); set_bit(from_dblock(b), cache->discard_bitset); spin_unlock_irqrestore(&cache->lock, flags); } static void clear_discard(struct cache *cache, dm_dblock_t b) { unsigned long flags; spin_lock_irqsave(&cache->lock, flags); clear_bit(from_dblock(b), cache->discard_bitset); spin_unlock_irqrestore(&cache->lock, flags); } static bool is_discarded(struct cache *cache, dm_dblock_t b) { int r; unsigned long flags; spin_lock_irqsave(&cache->lock, flags); r = test_bit(from_dblock(b), cache->discard_bitset); spin_unlock_irqrestore(&cache->lock, flags); return r; } static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b) { int r; unsigned long flags; spin_lock_irqsave(&cache->lock, flags); r = test_bit(from_dblock(oblock_to_dblock(cache, b)), cache->discard_bitset); spin_unlock_irqrestore(&cache->lock, flags); return r; } /*----------------------------------------------------------------*/ 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); } /*---------------------------------------------------------------- * Per bio data *--------------------------------------------------------------*/ /* * If using writeback, leave out struct per_bio_data's writethrough fields. */ #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache)) #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data)) static bool writethrough_mode(struct cache_features *f) { return f->io_mode == CM_IO_WRITETHROUGH; } static bool writeback_mode(struct cache_features *f) { return f->io_mode == CM_IO_WRITEBACK; } static bool passthrough_mode(struct cache_features *f) { return f->io_mode == CM_IO_PASSTHROUGH; } static size_t get_per_bio_data_size(struct cache *cache) { return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB; } static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size) { struct per_bio_data *pb = dm_per_bio_data(bio, data_size); BUG_ON(!pb); return pb; } static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size) { struct per_bio_data *pb = get_per_bio_data(bio, data_size); pb->tick = false; pb->req_nr = dm_bio_get_target_bio_nr(bio); pb->all_io_entry = NULL; pb->len = 0; return pb; } /*---------------------------------------------------------------- * Remapping *--------------------------------------------------------------*/ static void remap_to_origin(struct cache *cache, struct bio *bio) { bio->bi_bdev = 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->bi_bdev = 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) { unsigned long flags; size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); spin_lock_irqsave(&cache->lock, flags); if (cache->need_tick_bio && !(bio->bi_opf & (REQ_FUA | REQ_PREFLUSH)) && bio_op(bio) != REQ_OP_DISCARD) { pb->tick = true; cache->need_tick_bio = false; } spin_unlock_irqrestore(&cache->lock, flags); } static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio, dm_oblock_t oblock) { 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, oblock, 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 int bio_triggers_commit(struct cache *cache, struct bio *bio) { return bio->bi_opf & (REQ_PREFLUSH | REQ_FUA); } /* * You must increment the deferred set whilst the prison cell is held. To * encourage this, we ask for 'cell' to be passed in. */ static void inc_ds(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell *cell) { size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); BUG_ON(!cell); BUG_ON(pb->all_io_entry); pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); } static bool accountable_bio(struct cache *cache, struct bio *bio) { return ((bio->bi_bdev == cache->origin_dev->bdev) && bio_op(bio) != REQ_OP_DISCARD); } static void accounted_begin(struct cache *cache, struct bio *bio) { size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); if (accountable_bio(cache, bio)) { pb->len = bio_sectors(bio); iot_io_begin(&cache->origin_tracker, pb->len); } } static void accounted_complete(struct cache *cache, struct bio *bio) { size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); iot_io_end(&cache->origin_tracker, pb->len); } static void accounted_request(struct cache *cache, struct bio *bio) { accounted_begin(cache, bio); generic_make_request(bio); } static void issue(struct cache *cache, struct bio *bio) { unsigned long flags; if (!bio_triggers_commit(cache, bio)) { accounted_request(cache, bio); return; } /* * Batch together any bios that trigger commits and then issue a * single commit for them in do_worker(). */ spin_lock_irqsave(&cache->lock, flags); cache->commit_requested = true; bio_list_add(&cache->deferred_flush_bios, bio); spin_unlock_irqrestore(&cache->lock, flags); } static void inc_and_issue(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell *cell) { inc_ds(cache, bio, cell); issue(cache, bio); } static void defer_writethrough_bio(struct cache *cache, struct bio *bio) { unsigned long flags; spin_lock_irqsave(&cache->lock, flags); bio_list_add(&cache->deferred_writethrough_bios, bio); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void writethrough_endio(struct bio *bio) { struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT); dm_unhook_bio(&pb->hook_info, bio); if (bio->bi_error) { bio_endio(bio); return; } dm_bio_restore(&pb->bio_details, bio); remap_to_cache(pb->cache, bio, pb->cblock); /* * We can't issue this bio directly, since we're in interrupt * context. So it gets put on a bio list for processing by the * worker thread. */ defer_writethrough_bio(pb->cache, bio); } /* * When running in writethrough mode we need to send writes to clean blocks * to both the cache and origin devices. In future we'd like to clone the * bio and send them in parallel, but for now we're doing them in * series as this is easier. */ static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio, dm_oblock_t oblock, dm_cblock_t cblock) { struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT); pb->cache = cache; pb->cblock = cblock; dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL); dm_bio_record(&pb->bio_details, bio); remap_to_origin_clear_discard(pb->cache, bio, oblock); } /*---------------------------------------------------------------- * 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_device_name(dm_table_get_md(cache->ti->table)); } static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode) { 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; 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); } 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); } } 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); } /*---------------------------------------------------------------- * 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 || bio->bi_opf & (REQ_PREFLUSH | REQ_FUA); } static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell) { if (discard_or_flush(cell->holder)) { /* * We have to handle these bios individually. */ dm_cell_release(cache->prison, cell, &cache->deferred_bios); free_prison_cell(cache, cell); } else list_add_tail(&cell->user_list, &cache->deferred_cells); } static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, bool holder) { unsigned long flags; if (!holder && dm_cell_promote_or_release(cache->prison, cell)) { /* * There was no prisoner to promote to holder, the * cell has been released. */ free_prison_cell(cache, cell); return; } spin_lock_irqsave(&cache->lock, flags); __cell_defer(cache, cell); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void cell_error_with_code(struct cache *cache, struct dm_bio_prison_cell *cell, int err) { dm_cell_error(cache->prison, cell, err); free_prison_cell(cache, cell); } static void cell_requeue(struct cache *cache, struct dm_bio_prison_cell *cell) { cell_error_with_code(cache, cell, DM_ENDIO_REQUEUE); } static void free_io_migration(struct dm_cache_migration *mg) { struct cache *cache = mg->cache; dec_io_migrations(cache); free_migration(mg); wake_worker(cache); } static void migration_failure(struct dm_cache_migration *mg) { struct cache *cache = mg->cache; const char *dev_name = cache_device_name(cache); if (mg->writeback) { DMERR_LIMIT("%s: writeback failed; couldn't copy block", dev_name); set_dirty(cache, mg->old_oblock, mg->cblock); cell_defer(cache, mg->old_ocell, false); } else if (mg->demote) { DMERR_LIMIT("%s: demotion failed; couldn't copy block", dev_name); policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock); cell_defer(cache, mg->old_ocell, mg->promote ? false : true); if (mg->promote) cell_defer(cache, mg->new_ocell, true); } else { DMERR_LIMIT("%s: promotion failed; couldn't copy block", dev_name); policy_remove_mapping(cache->policy, mg->new_oblock); cell_defer(cache, mg->new_ocell, true); } free_io_migration(mg); } static void migration_success_pre_commit(struct dm_cache_migration *mg) { int r; unsigned long flags; struct cache *cache = mg->cache; if (mg->writeback) { clear_dirty(cache, mg->old_oblock, mg->cblock); cell_defer(cache, mg->old_ocell, false); free_io_migration(mg); return; } else if (mg->demote) { r = dm_cache_remove_mapping(cache->cmd, mg->cblock); if (r) { DMERR_LIMIT("%s: demotion failed; couldn't update on disk metadata", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_remove_mapping", r); policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock); if (mg->promote) cell_defer(cache, mg->new_ocell, true); free_io_migration(mg); return; } } else { r = dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock); if (r) { DMERR_LIMIT("%s: promotion failed; couldn't update on disk metadata", cache_device_name(cache)); metadata_operation_failed(cache, "dm_cache_insert_mapping", r); policy_remove_mapping(cache->policy, mg->new_oblock); free_io_migration(mg); return; } } spin_lock_irqsave(&cache->lock, flags); list_add_tail(&mg->list, &cache->need_commit_migrations); cache->commit_requested = true; spin_unlock_irqrestore(&cache->lock, flags); } static void migration_success_post_commit(struct dm_cache_migration *mg) { unsigned long flags; struct cache *cache = mg->cache; if (mg->writeback) { DMWARN_LIMIT("%s: writeback unexpectedly triggered commit", cache_device_name(cache)); return; } else if (mg->demote) { cell_defer(cache, mg->old_ocell, mg->promote ? false : true); if (mg->promote) { mg->demote = false; spin_lock_irqsave(&cache->lock, flags); list_add_tail(&mg->list, &cache->quiesced_migrations); spin_unlock_irqrestore(&cache->lock, flags); } else { if (mg->invalidate) policy_remove_mapping(cache->policy, mg->old_oblock); free_io_migration(mg); } } else { if (mg->requeue_holder) { clear_dirty(cache, mg->new_oblock, mg->cblock); cell_defer(cache, mg->new_ocell, true); } else { /* * The block was promoted via an overwrite, so it's dirty. */ set_dirty(cache, mg->new_oblock, mg->cblock); bio_endio(mg->new_ocell->holder); cell_defer(cache, mg->new_ocell, false); } free_io_migration(mg); } } static void copy_complete(int read_err, unsigned long write_err, void *context) { unsigned long flags; struct dm_cache_migration *mg = (struct dm_cache_migration *) context; struct cache *cache = mg->cache; if (read_err || write_err) mg->err = true; spin_lock_irqsave(&cache->lock, flags); list_add_tail(&mg->list, &cache->completed_migrations); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void issue_copy(struct dm_cache_migration *mg) { int r; struct dm_io_region o_region, c_region; struct cache *cache = mg->cache; sector_t cblock = from_cblock(mg->cblock); o_region.bdev = cache->origin_dev->bdev; o_region.count = cache->sectors_per_block; c_region.bdev = cache->cache_dev->bdev; c_region.sector = cblock * cache->sectors_per_block; c_region.count = cache->sectors_per_block; if (mg->writeback || mg->demote) { /* demote */ o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block; r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg); } else { /* promote */ o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block; r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg); } if (r < 0) { DMERR_LIMIT("%s: issuing migration failed", cache_device_name(cache)); migration_failure(mg); } } static void overwrite_endio(struct bio *bio) { struct dm_cache_migration *mg = bio->bi_private; struct cache *cache = mg->cache; size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); unsigned long flags; dm_unhook_bio(&pb->hook_info, bio); if (bio->bi_error) mg->err = true; mg->requeue_holder = false; spin_lock_irqsave(&cache->lock, flags); list_add_tail(&mg->list, &cache->completed_migrations); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio) { size_t pb_data_size = get_per_bio_data_size(mg->cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg); remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock); /* * No need to inc_ds() here, since the cell will be held for the * duration of the io. */ accounted_request(mg->cache, bio); } 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 void avoid_copy(struct dm_cache_migration *mg) { atomic_inc(&mg->cache->stats.copies_avoided); migration_success_pre_commit(mg); } 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 issue_discard(struct dm_cache_migration *mg) { dm_dblock_t b, e; struct bio *bio = mg->new_ocell->holder; struct cache *cache = mg->cache; calc_discard_block_range(cache, bio, &b, &e); while (b != e) { set_discard(cache, b); b = to_dblock(from_dblock(b) + 1); } bio_endio(bio); cell_defer(cache, mg->new_ocell, false); free_migration(mg); wake_worker(cache); } static void issue_copy_or_discard(struct dm_cache_migration *mg) { bool avoid; struct cache *cache = mg->cache; if (mg->discard) { issue_discard(mg); return; } if (mg->writeback || mg->demote) avoid = !is_dirty(cache, mg->cblock) || is_discarded_oblock(cache, mg->old_oblock); else { struct bio *bio = mg->new_ocell->holder; avoid = is_discarded_oblock(cache, mg->new_oblock); if (writeback_mode(&cache->features) && !avoid && bio_writes_complete_block(cache, bio)) { issue_overwrite(mg, bio); return; } } avoid ? avoid_copy(mg) : issue_copy(mg); } static void complete_migration(struct dm_cache_migration *mg) { if (mg->err) migration_failure(mg); else migration_success_pre_commit(mg); } static void process_migrations(struct cache *cache, struct list_head *head, void (*fn)(struct dm_cache_migration *)) { unsigned long flags; struct list_head list; struct dm_cache_migration *mg, *tmp; INIT_LIST_HEAD(&list); spin_lock_irqsave(&cache->lock, flags); list_splice_init(head, &list); spin_unlock_irqrestore(&cache->lock, flags); list_for_each_entry_safe(mg, tmp, &list, list) fn(mg); } static void __queue_quiesced_migration(struct dm_cache_migration *mg) { list_add_tail(&mg->list, &mg->cache->quiesced_migrations); } static void queue_quiesced_migration(struct dm_cache_migration *mg) { unsigned long flags; struct cache *cache = mg->cache; spin_lock_irqsave(&cache->lock, flags); __queue_quiesced_migration(mg); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void queue_quiesced_migrations(struct cache *cache, struct list_head *work) { unsigned long flags; struct dm_cache_migration *mg, *tmp; spin_lock_irqsave(&cache->lock, flags); list_for_each_entry_safe(mg, tmp, work, list) __queue_quiesced_migration(mg); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void check_for_quiesced_migrations(struct cache *cache, struct per_bio_data *pb) { struct list_head work; if (!pb->all_io_entry) return; INIT_LIST_HEAD(&work); dm_deferred_entry_dec(pb->all_io_entry, &work); if (!list_empty(&work)) queue_quiesced_migrations(cache, &work); } static void quiesce_migration(struct dm_cache_migration *mg) { if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list)) queue_quiesced_migration(mg); } static void promote(struct cache *cache, struct prealloc *structs, dm_oblock_t oblock, dm_cblock_t cblock, struct dm_bio_prison_cell *cell) { struct dm_cache_migration *mg = prealloc_get_migration(structs); mg->err = false; mg->discard = false; mg->writeback = false; mg->demote = false; mg->promote = true; mg->requeue_holder = true; mg->invalidate = false; mg->cache = cache; mg->new_oblock = oblock; mg->cblock = cblock; mg->old_ocell = NULL; mg->new_ocell = cell; mg->start_jiffies = jiffies; inc_io_migrations(cache); quiesce_migration(mg); } static void writeback(struct cache *cache, struct prealloc *structs, dm_oblock_t oblock, dm_cblock_t cblock, struct dm_bio_prison_cell *cell) { struct dm_cache_migration *mg = prealloc_get_migration(structs); mg->err = false; mg->discard = false; mg->writeback = true; mg->demote = false; mg->promote = false; mg->requeue_holder = true; mg->invalidate = false; mg->cache = cache; mg->old_oblock = oblock; mg->cblock = cblock; mg->old_ocell = cell; mg->new_ocell = NULL; mg->start_jiffies = jiffies; inc_io_migrations(cache); quiesce_migration(mg); } static void demote_then_promote(struct cache *cache, struct prealloc *structs, dm_oblock_t old_oblock, dm_oblock_t new_oblock, dm_cblock_t cblock, struct dm_bio_prison_cell *old_ocell, struct dm_bio_prison_cell *new_ocell) { struct dm_cache_migration *mg = prealloc_get_migration(structs); mg->err = false; mg->discard = false; mg->writeback = false; mg->demote = true; mg->promote = true; mg->requeue_holder = true; mg->invalidate = false; mg->cache = cache; mg->old_oblock = old_oblock; mg->new_oblock = new_oblock; mg->cblock = cblock; mg->old_ocell = old_ocell; mg->new_ocell = new_ocell; mg->start_jiffies = jiffies; inc_io_migrations(cache); quiesce_migration(mg); } /* * Invalidate a cache entry. No writeback occurs; any changes in the cache * block are thrown away. */ static void invalidate(struct cache *cache, struct prealloc *structs, dm_oblock_t oblock, dm_cblock_t cblock, struct dm_bio_prison_cell *cell) { struct dm_cache_migration *mg = prealloc_get_migration(structs); mg->err = false; mg->discard = false; mg->writeback = false; mg->demote = true; mg->promote = false; mg->requeue_holder = true; mg->invalidate = true; mg->cache = cache; mg->old_oblock = oblock; mg->cblock = cblock; mg->old_ocell = cell; mg->new_ocell = NULL; mg->start_jiffies = jiffies; inc_io_migrations(cache); quiesce_migration(mg); } static void discard(struct cache *cache, struct prealloc *structs, struct dm_bio_prison_cell *cell) { struct dm_cache_migration *mg = prealloc_get_migration(structs); mg->err = false; mg->discard = true; mg->writeback = false; mg->demote = false; mg->promote = false; mg->requeue_holder = false; mg->invalidate = false; mg->cache = cache; mg->old_ocell = NULL; mg->new_ocell = cell; mg->start_jiffies = jiffies; quiesce_migration(mg); } /*---------------------------------------------------------------- * bio processing *--------------------------------------------------------------*/ static void defer_bio(struct cache *cache, struct bio *bio) { unsigned long flags; spin_lock_irqsave(&cache->lock, flags); bio_list_add(&cache->deferred_bios, bio); spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); } static void process_flush_bio(struct cache *cache, struct bio *bio) { size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); BUG_ON(bio->bi_iter.bi_size); if (!pb->req_nr) remap_to_origin(cache, bio); else remap_to_cache(cache, bio, 0); /* * REQ_PREFLUSH is not directed at any particular block so we don't * need to inc_ds(). REQ_FUA's are split into a write + REQ_PREFLUSH * by dm-core. */ issue(cache, bio); } static void process_discard_bio(struct cache *cache, struct prealloc *structs, struct bio *bio) { int r; dm_dblock_t b, e; struct dm_bio_prison_cell *cell_prealloc, *new_ocell; calc_discard_block_range(cache, bio, &b, &e); if (b == e) { bio_endio(bio); return; } cell_prealloc = prealloc_get_cell(structs); r = bio_detain_range(cache, dblock_to_oblock(cache, b), dblock_to_oblock(cache, e), bio, cell_prealloc, (cell_free_fn) prealloc_put_cell, structs, &new_ocell); if (r > 0) return; discard(cache, structs, new_ocell); } static bool spare_migration_bandwidth(struct cache *cache) { sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) * cache->sectors_per_block; return current_volume < cache->migration_threshold; } 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); } /*----------------------------------------------------------------*/ struct inc_detail { struct cache *cache; struct bio_list bios_for_issue; struct bio_list unhandled_bios; bool any_writes; }; static void inc_fn(void *context, struct dm_bio_prison_cell *cell) { struct bio *bio; struct inc_detail *detail = context; struct cache *cache = detail->cache; inc_ds(cache, cell->holder, cell); if (bio_data_dir(cell->holder) == WRITE) detail->any_writes = true; while ((bio = bio_list_pop(&cell->bios))) { if (discard_or_flush(bio)) { bio_list_add(&detail->unhandled_bios, bio); continue; } if (bio_data_dir(bio) == WRITE) detail->any_writes = true; bio_list_add(&detail->bios_for_issue, bio); inc_ds(cache, bio, cell); } } // FIXME: refactor these two static void remap_cell_to_origin_clear_discard(struct cache *cache, struct dm_bio_prison_cell *cell, dm_oblock_t oblock, bool issue_holder) { struct bio *bio; unsigned long flags; struct inc_detail detail; detail.cache = cache; bio_list_init(&detail.bios_for_issue); bio_list_init(&detail.unhandled_bios); detail.any_writes = false; spin_lock_irqsave(&cache->lock, flags); dm_cell_visit_release(cache->prison, inc_fn, &detail, cell); bio_list_merge(&cache->deferred_bios, &detail.unhandled_bios); spin_unlock_irqrestore(&cache->lock, flags); remap_to_origin(cache, cell->holder); if (issue_holder) issue(cache, cell->holder); else accounted_begin(cache, cell->holder); if (detail.any_writes) clear_discard(cache, oblock_to_dblock(cache, oblock)); while ((bio = bio_list_pop(&detail.bios_for_issue))) { remap_to_origin(cache, bio); issue(cache, bio); } free_prison_cell(cache, cell); } static void remap_cell_to_cache_dirty(struct cache *cache, struct dm_bio_prison_cell *cell, dm_oblock_t oblock, dm_cblock_t cblock, bool issue_holder) { struct bio *bio; unsigned long flags; struct inc_detail detail; detail.cache = cache; bio_list_init(&detail.bios_for_issue); bio_list_init(&detail.unhandled_bios); detail.any_writes = false; spin_lock_irqsave(&cache->lock, flags); dm_cell_visit_release(cache->prison, inc_fn, &detail, cell); bio_list_merge(&cache->deferred_bios, &detail.unhandled_bios); spin_unlock_irqrestore(&cache->lock, flags); remap_to_cache(cache, cell->holder, cblock); if (issue_holder) issue(cache, cell->holder); else accounted_begin(cache, cell->holder); if (detail.any_writes) { set_dirty(cache, oblock, cblock); clear_discard(cache, oblock_to_dblock(cache, oblock)); } while ((bio = bio_list_pop(&detail.bios_for_issue))) { remap_to_cache(cache, bio, cblock); issue(cache, bio); } free_prison_cell(cache, cell); } /*----------------------------------------------------------------*/ struct old_oblock_lock { struct policy_locker locker; struct cache *cache; struct prealloc *structs; struct dm_bio_prison_cell *cell; }; static int null_locker(struct policy_locker *locker, dm_oblock_t b) { /* This should never be called */ BUG(); return 0; } static int cell_locker(struct policy_locker *locker, dm_oblock_t b) { struct old_oblock_lock *l = container_of(locker, struct old_oblock_lock, locker); struct dm_bio_prison_cell *cell_prealloc = prealloc_get_cell(l->structs); return bio_detain(l->cache, b, NULL, cell_prealloc, (cell_free_fn) prealloc_put_cell, l->structs, &l->cell); } static void process_cell(struct cache *cache, struct prealloc *structs, struct dm_bio_prison_cell *new_ocell) { int r; bool release_cell = true; struct bio *bio = new_ocell->holder; dm_oblock_t block = get_bio_block(cache, bio); struct policy_result lookup_result; bool passthrough = passthrough_mode(&cache->features); bool fast_promotion, can_migrate; struct old_oblock_lock ool; fast_promotion = is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio); can_migrate = !passthrough && (fast_promotion || spare_migration_bandwidth(cache)); ool.locker.fn = cell_locker; ool.cache = cache; ool.structs = structs; ool.cell = NULL; r = policy_map(cache->policy, block, true, can_migrate, fast_promotion, bio, &ool.locker, &lookup_result); if (r == -EWOULDBLOCK) /* migration has been denied */ lookup_result.op = POLICY_MISS; switch (lookup_result.op) { case POLICY_HIT: if (passthrough) { inc_miss_counter(cache, bio); /* * Passthrough always maps to the origin, * invalidating any cache blocks that are written * to. */ if (bio_data_dir(bio) == WRITE) { atomic_inc(&cache->stats.demotion); invalidate(cache, structs, block, lookup_result.cblock, new_ocell); release_cell = false; } else { /* FIXME: factor out issue_origin() */ remap_to_origin_clear_discard(cache, bio, block); inc_and_issue(cache, bio, new_ocell); } } else { inc_hit_counter(cache, bio); if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) && !is_dirty(cache, lookup_result.cblock)) { remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock); inc_and_issue(cache, bio, new_ocell); } else { remap_cell_to_cache_dirty(cache, new_ocell, block, lookup_result.cblock, true); release_cell = false; } } break; case POLICY_MISS: inc_miss_counter(cache, bio); remap_cell_to_origin_clear_discard(cache, new_ocell, block, true); release_cell = false; break; case POLICY_NEW: atomic_inc(&cache->stats.promotion); promote(cache, structs, block, lookup_result.cblock, new_ocell); release_cell = false; break; case POLICY_REPLACE: atomic_inc(&cache->stats.demotion); atomic_inc(&cache->stats.promotion); demote_then_promote(cache, structs, lookup_result.old_oblock, block, lookup_result.cblock, ool.cell, new_ocell); release_cell = false; break; default: DMERR_LIMIT("%s: %s: erroring bio, unknown policy op: %u", cache_device_name(cache), __func__, (unsigned) lookup_result.op); bio_io_error(bio); } if (release_cell) cell_defer(cache, new_ocell, false); } static void process_bio(struct cache *cache, struct prealloc *structs, struct bio *bio) { int r; dm_oblock_t block = get_bio_block(cache, bio); struct dm_bio_prison_cell *cell_prealloc, *new_ocell; /* * Check to see if that block is currently migrating. */ cell_prealloc = prealloc_get_cell(structs); r = bio_detain(cache, block, bio, cell_prealloc, (cell_free_fn) prealloc_put_cell, structs, &new_ocell); if (r > 0) return; process_cell(cache, structs, new_ocell); } static int need_commit_due_to_time(struct cache *cache) { return jiffies < cache->last_commit_jiffies || jiffies > cache->last_commit_jiffies + COMMIT_PERIOD; } /* * 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; } static int commit_if_needed(struct cache *cache) { int r = 0; if ((cache->commit_requested || need_commit_due_to_time(cache)) && dm_cache_changed_this_transaction(cache->cmd)) { r = commit(cache, false); cache->commit_requested = false; cache->last_commit_jiffies = jiffies; } return r; } static void process_deferred_bios(struct cache *cache) { bool prealloc_used = false; unsigned long flags; struct bio_list bios; struct bio *bio; struct prealloc structs; memset(&structs, 0, sizeof(structs)); bio_list_init(&bios); spin_lock_irqsave(&cache->lock, flags); bio_list_merge(&bios, &cache->deferred_bios); bio_list_init(&cache->deferred_bios); spin_unlock_irqrestore(&cache->lock, flags); while (!bio_list_empty(&bios)) { /* * If we've got no free migration structs, and processing * this bio might require one, we pause until there are some * prepared mappings to process. */ prealloc_used = true; if (prealloc_data_structs(cache, &structs)) { spin_lock_irqsave(&cache->lock, flags); bio_list_merge(&cache->deferred_bios, &bios); spin_unlock_irqrestore(&cache->lock, flags); break; } bio = bio_list_pop(&bios); if (bio->bi_opf & REQ_PREFLUSH) process_flush_bio(cache, bio); else if (bio_op(bio) == REQ_OP_DISCARD) process_discard_bio(cache, &structs, bio); else process_bio(cache, &structs, bio); } if (prealloc_used) prealloc_free_structs(cache, &structs); } static void process_deferred_cells(struct cache *cache) { bool prealloc_used = false; unsigned long flags; struct dm_bio_prison_cell *cell, *tmp; struct list_head cells; struct prealloc structs; memset(&structs, 0, sizeof(structs)); INIT_LIST_HEAD(&cells); spin_lock_irqsave(&cache->lock, flags); list_splice_init(&cache->deferred_cells, &cells); spin_unlock_irqrestore(&cache->lock, flags); list_for_each_entry_safe(cell, tmp, &cells, user_list) { /* * If we've got no free migration structs, and processing * this bio might require one, we pause until there are some * prepared mappings to process. */ prealloc_used = true; if (prealloc_data_structs(cache, &structs)) { spin_lock_irqsave(&cache->lock, flags); list_splice(&cells, &cache->deferred_cells); spin_unlock_irqrestore(&cache->lock, flags); break; } process_cell(cache, &structs, cell); } if (prealloc_used) prealloc_free_structs(cache, &structs); } static void process_deferred_flush_bios(struct cache *cache, bool submit_bios) { unsigned long flags; struct bio_list bios; struct bio *bio; bio_list_init(&bios); spin_lock_irqsave(&cache->lock, flags); bio_list_merge(&bios, &cache->deferred_flush_bios); bio_list_init(&cache->deferred_flush_bios); spin_unlock_irqrestore(&cache->lock, flags); /* * These bios have already been through inc_ds() */ while ((bio = bio_list_pop(&bios))) submit_bios ? accounted_request(cache, bio) : bio_io_error(bio); } static void process_deferred_writethrough_bios(struct cache *cache) { unsigned long flags; struct bio_list bios; struct bio *bio; bio_list_init(&bios); spin_lock_irqsave(&cache->lock, flags); bio_list_merge(&bios, &cache->deferred_writethrough_bios); bio_list_init(&cache->deferred_writethrough_bios); spin_unlock_irqrestore(&cache->lock, flags); /* * These bios have already been through inc_ds() */ while ((bio = bio_list_pop(&bios))) accounted_request(cache, bio); } static void writeback_some_dirty_blocks(struct cache *cache) { bool prealloc_used = false; dm_oblock_t oblock; dm_cblock_t cblock; struct prealloc structs; struct dm_bio_prison_cell *old_ocell; bool busy = !iot_idle_for(&cache->origin_tracker, HZ); memset(&structs, 0, sizeof(structs)); while (spare_migration_bandwidth(cache)) { if (policy_writeback_work(cache->policy, &oblock, &cblock, busy)) break; /* no work to do */ prealloc_used = true; if (prealloc_data_structs(cache, &structs) || get_cell(cache, oblock, &structs, &old_ocell)) { policy_set_dirty(cache->policy, oblock); break; } writeback(cache, &structs, oblock, cblock, old_ocell); } if (prealloc_used) prealloc_free_structs(cache, &structs); } /*---------------------------------------------------------------- * Invalidations. * Dropping something from the cache *without* writing back. *--------------------------------------------------------------*/ static void process_invalidation_request(struct cache *cache, struct invalidation_request *req) { int r = 0; uint64_t begin = from_cblock(req->cblocks->begin); uint64_t end = from_cblock(req->cblocks->end); while (begin != end) { r = policy_remove_cblock(cache->policy, to_cblock(begin)); if (!r) { r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin)); if (r) { metadata_operation_failed(cache, "dm_cache_remove_mapping", r); break; } } else if (r == -ENODATA) { /* harmless, already unmapped */ r = 0; } else { DMERR("%s: policy_remove_cblock failed", cache_device_name(cache)); break; } begin++; } cache->commit_requested = true; req->err = r; atomic_set(&req->complete, 1); wake_up(&req->result_wait); } static void process_invalidation_requests(struct cache *cache) { struct list_head list; struct invalidation_request *req, *tmp; INIT_LIST_HEAD(&list); spin_lock(&cache->invalidation_lock); list_splice_init(&cache->invalidation_requests, &list); spin_unlock(&cache->invalidation_lock); list_for_each_entry_safe (req, tmp, &list, list) process_invalidation_request(cache, req); } /*---------------------------------------------------------------- * Main worker loop *--------------------------------------------------------------*/ static bool is_quiescing(struct cache *cache) { return atomic_read(&cache->quiescing); } static void ack_quiescing(struct cache *cache) { if (is_quiescing(cache)) { atomic_inc(&cache->quiescing_ack); wake_up(&cache->quiescing_wait); } } static void wait_for_quiescing_ack(struct cache *cache) { wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack)); } static void start_quiescing(struct cache *cache) { atomic_inc(&cache->quiescing); wait_for_quiescing_ack(cache); } static void stop_quiescing(struct cache *cache) { atomic_set(&cache->quiescing, 0); atomic_set(&cache->quiescing_ack, 0); } static void wait_for_migrations(struct cache *cache) { wait_event(cache->migration_wait, !atomic_read(&cache->nr_allocated_migrations)); } static void stop_worker(struct cache *cache) { cancel_delayed_work(&cache->waker); flush_workqueue(cache->wq); } static void requeue_deferred_cells(struct cache *cache) { unsigned long flags; struct list_head cells; struct dm_bio_prison_cell *cell, *tmp; INIT_LIST_HEAD(&cells); spin_lock_irqsave(&cache->lock, flags); list_splice_init(&cache->deferred_cells, &cells); spin_unlock_irqrestore(&cache->lock, flags); list_for_each_entry_safe(cell, tmp, &cells, user_list) cell_requeue(cache, cell); } static void requeue_deferred_bios(struct cache *cache) { struct bio *bio; struct bio_list bios; bio_list_init(&bios); bio_list_merge(&bios, &cache->deferred_bios); bio_list_init(&cache->deferred_bios); while ((bio = bio_list_pop(&bios))) { bio->bi_error = DM_ENDIO_REQUEUE; bio_endio(bio); } } static int more_work(struct cache *cache) { if (is_quiescing(cache)) return !list_empty(&cache->quiesced_migrations) || !list_empty(&cache->completed_migrations) || !list_empty(&cache->need_commit_migrations); else return !bio_list_empty(&cache->deferred_bios) || !list_empty(&cache->deferred_cells) || !bio_list_empty(&cache->deferred_flush_bios) || !bio_list_empty(&cache->deferred_writethrough_bios) || !list_empty(&cache->quiesced_migrations) || !list_empty(&cache->completed_migrations) || !list_empty(&cache->need_commit_migrations) || cache->invalidate; } static void do_worker(struct work_struct *ws) { struct cache *cache = container_of(ws, struct cache, worker); do { if (!is_quiescing(cache)) { writeback_some_dirty_blocks(cache); process_deferred_writethrough_bios(cache); process_deferred_bios(cache); process_deferred_cells(cache); process_invalidation_requests(cache); } process_migrations(cache, &cache->quiesced_migrations, issue_copy_or_discard); process_migrations(cache, &cache->completed_migrations, complete_migration); if (commit_if_needed(cache)) { process_deferred_flush_bios(cache, false); process_migrations(cache, &cache->need_commit_migrations, migration_failure); } else { process_deferred_flush_bios(cache, true); process_migrations(cache, &cache->need_commit_migrations, migration_success_post_commit); } ack_quiescing(cache); } while (more_work(cache)); } /* * 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_worker(cache); queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD); } /*----------------------------------------------------------------*/ static int is_congested(struct dm_dev *dev, int bdi_bits) { struct request_queue *q = bdev_get_queue(dev->bdev); return bdi_congested(&q->backing_dev_info, bdi_bits); } static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits) { struct cache *cache = container_of(cb, struct cache, callbacks); return is_congested(cache->origin_dev, bdi_bits) || is_congested(cache->cache_dev, bdi_bits); } /*---------------------------------------------------------------- * 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 i; mempool_destroy(cache->migration_pool); if (cache->all_io_ds) dm_deferred_set_destroy(cache->all_io_ds); if (cache->prison) dm_bio_prison_destroy(cache->prison); 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); 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 i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT; } /*----------------------------------------------------------------*/ /* * Construct a cache device mapping. * * cache * <#feature args> []* * <#policy args> []* * * 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; char b[BDEVNAME_SIZE]; if (!at_least_one_arg(as, error)) return -EINVAL; r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_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 %s is larger than %u sectors: excess space will not be used.", bdevname(ca->metadata_dev->bdev, b), 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), FMODE_READ | FMODE_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), FMODE_READ | FMODE_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; } static int parse_features(struct cache_args *ca, struct dm_arg_set *as, char **error) { static struct dm_arg _args[] = { {0, 1, "Invalid number of cache feature arguments"}, }; int r; unsigned 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; else if (!strcasecmp(arg, "writethrough")) cf->io_mode = CM_IO_WRITETHROUGH; else if (!strcasecmp(arg, "passthrough")) cf->io_mode = CM_IO_PASSTHROUGH; else { *error = "Unrecognised cache feature requested"; return -EINVAL; } } return 0; } static int parse_policy(struct cache_args *ca, struct dm_arg_set *as, char **error) { static 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 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; 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->num_flush_bios = 2; ti->flush_supported = true; ti->num_discard_bios = 1; ti->discards_supported = true; ti->discard_zeroes_data_unsupported = true; ti->split_discard_bios = false; cache->features = ca->features; ti->per_io_data_size = get_per_bio_data_size(cache); cache->callbacks.congested_fn = cache_is_congested; dm_table_add_target_callbacks(ti->table, &cache->callbacks); 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; /* FIXME: factor out this whole section */ 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)); 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->features)) { 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; } } spin_lock_init(&cache->lock); INIT_LIST_HEAD(&cache->deferred_cells); bio_list_init(&cache->deferred_bios); bio_list_init(&cache->deferred_flush_bios); bio_list_init(&cache->deferred_writethrough_bios); INIT_LIST_HEAD(&cache->quiesced_migrations); INIT_LIST_HEAD(&cache->completed_migrations); INIT_LIST_HEAD(&cache->need_commit_migrations); atomic_set(&cache->nr_allocated_migrations, 0); atomic_set(&cache->nr_io_migrations, 0); init_waitqueue_head(&cache->migration_wait); init_waitqueue_head(&cache->quiescing_wait); atomic_set(&cache->quiescing, 0); atomic_set(&cache->quiescing_ack, 0); 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_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM); if (!cache->wq) { *error = "could not create workqueue for metadata object"; goto bad; } INIT_WORK(&cache->worker, do_worker); INIT_DELAYED_WORK(&cache->waker, do_waker); cache->last_commit_jiffies = jiffies; cache->prison = dm_bio_prison_create(); if (!cache->prison) { *error = "could not create bio prison"; goto bad; } cache->all_io_ds = dm_deferred_set_create(); if (!cache->all_io_ds) { *error = "could not create all_io deferred set"; goto bad; } cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE, migration_cache); if (!cache->migration_pool) { *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); iot_init(&cache->origin_tracker); *result = cache; return 0; bad: destroy(cache); return r; } static int copy_ctr_args(struct cache *cache, int argc, const char **argv) { unsigned 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 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; struct dm_bio_prison_cell *cell = NULL; dm_oblock_t block = get_bio_block(cache, bio); size_t pb_data_size = get_per_bio_data_size(cache); bool can_migrate = false; bool fast_promotion; struct policy_result lookup_result; struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size); struct old_oblock_lock ool; ool.locker.fn = null_locker; 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; } /* * Check to see if that block is currently migrating. */ cell = alloc_prison_cell(cache); if (!cell) { defer_bio(cache, bio); return DM_MAPIO_SUBMITTED; } r = bio_detain(cache, block, bio, cell, (cell_free_fn) free_prison_cell, cache, &cell); if (r) { if (r < 0) defer_bio(cache, bio); return DM_MAPIO_SUBMITTED; } fast_promotion = is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio); r = policy_map(cache->policy, block, false, can_migrate, fast_promotion, bio, &ool.locker, &lookup_result); if (r == -EWOULDBLOCK) { cell_defer(cache, cell, true); return DM_MAPIO_SUBMITTED; } else if (r) { DMERR_LIMIT("%s: Unexpected return from cache replacement policy: %d", cache_device_name(cache), r); cell_defer(cache, cell, false); bio_io_error(bio); return DM_MAPIO_SUBMITTED; } r = DM_MAPIO_REMAPPED; switch (lookup_result.op) { case POLICY_HIT: if (passthrough_mode(&cache->features)) { if (bio_data_dir(bio) == WRITE) { /* * We need to invalidate this block, so * defer for the worker thread. */ cell_defer(cache, cell, true); r = DM_MAPIO_SUBMITTED; } else { inc_miss_counter(cache, bio); remap_to_origin_clear_discard(cache, bio, block); accounted_begin(cache, bio); inc_ds(cache, bio, cell); // FIXME: we want to remap hits or misses straight // away rather than passing over to the worker. cell_defer(cache, cell, false); } } else { inc_hit_counter(cache, bio); if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) && !is_dirty(cache, lookup_result.cblock)) { remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock); accounted_begin(cache, bio); inc_ds(cache, bio, cell); cell_defer(cache, cell, false); } else remap_cell_to_cache_dirty(cache, cell, block, lookup_result.cblock, false); } break; case POLICY_MISS: inc_miss_counter(cache, bio); if (pb->req_nr != 0) { /* * This is a duplicate writethrough io that is no * longer needed because the block has been demoted. */ bio_endio(bio); // FIXME: remap everything as a miss cell_defer(cache, cell, false); r = DM_MAPIO_SUBMITTED; } else remap_cell_to_origin_clear_discard(cache, cell, block, false); break; default: DMERR_LIMIT("%s: %s: erroring bio: unknown policy op: %u", cache_device_name(cache), __func__, (unsigned) lookup_result.op); cell_defer(cache, cell, false); bio_io_error(bio); r = DM_MAPIO_SUBMITTED; } return r; } static int cache_end_io(struct dm_target *ti, struct bio *bio, int error) { struct cache *cache = ti->private; unsigned long flags; size_t pb_data_size = get_per_bio_data_size(cache); struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); 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); } check_for_quiesced_migrations(cache, pb); accounted_complete(cache, bio); return 0; } static int write_dirty_bitset(struct cache *cache) { unsigned i, r; if (get_cache_mode(cache) >= CM_READ_ONLY) return -EINVAL; for (i = 0; i < from_cblock(cache->cache_size); i++) { r = dm_cache_set_dirty(cache->cmd, to_cblock(i), is_dirty(cache, to_cblock(i))); if (r) { metadata_operation_failed(cache, "dm_cache_set_dirty", r); return r; } } return 0; } static int write_discard_bitset(struct cache *cache) { unsigned 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; start_quiescing(cache); wait_for_migrations(cache); stop_worker(cache); requeue_deferred_bios(cache); requeue_deferred_cells(cache); stop_quiescing(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) { int r; struct cache *cache = context; r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid); if (r) return r; if (dirty) set_dirty(cache, oblock, cblock); else clear_dirty(cache, oblock, cblock); return 0; } /* * The discard block size in the on disk metadata is not * neccessarily 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)) return true; /* * 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; do_waker(&cache->waker.work); } /* * Status format: * * <#used metadata blocks>/<#total metadata blocks> * <#used cache blocks>/<#total cache blocks> * <#read hits> <#read misses> <#write hits> <#write misses> * <#demotions> <#promotions> <#dirty> * <#features> * * <#core args> * <#policy args> * */ static void cache_status(struct dm_target *ti, status_type_t type, unsigned status_flags, char *result, unsigned maxlen) { int r = 0; unsigned 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)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) atomic_read(&cache->stats.read_hit), (unsigned) atomic_read(&cache->stats.read_miss), (unsigned) atomic_read(&cache->stats.write_hit), (unsigned) atomic_read(&cache->stats.write_miss), (unsigned) atomic_read(&cache->stats.demotion), (unsigned) atomic_read(&cache->stats.promotion), (unsigned long) atomic_read(&cache->nr_dirty)); if (writethrough_mode(&cache->features)) DMEMIT("1 writethrough "); else if (passthrough_mode(&cache->features)) DMEMIT("1 passthrough "); else if (writeback_mode(&cache->features)) DMEMIT("1 writeback "); else { DMERR("%s: internal error: unknown io mode: %d", cache_device_name(cache), (int) cache->features.io_mode); goto err; } 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]); } return; err: DMEMIT("Error"); } /* * A cache block range can take two forms: * * i) A single cblock, eg. '3456' * ii) A begin and end cblock with dots 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 int request_invalidation(struct cache *cache, struct cblock_range *range) { struct invalidation_request req; INIT_LIST_HEAD(&req.list); req.cblocks = range; atomic_set(&req.complete, 0); req.err = 0; init_waitqueue_head(&req.result_wait); spin_lock(&cache->invalidation_lock); list_add(&req.list, &cache->invalidation_requests); spin_unlock(&cache->invalidation_lock); wake_worker(cache); wait_event(req.result_wait, atomic_read(&req.complete)); return req.err; } static int process_invalidate_cblocks_message(struct cache *cache, unsigned count, const char **cblock_ranges) { int r = 0; unsigned i; struct cblock_range range; if (!passthrough_mode(&cache->features)) { 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 * " " * and * "invalidate_cblocks [()|(-)]* * * The key migration_threshold is supported by the cache target core. */ static int cache_message(struct dm_target *ti, unsigned argc, char **argv) { 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; } static void set_discard_limits(struct cache *cache, struct queue_limits *limits) { /* * FIXME: these limits may be incompatible with the cache device */ limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024, cache->origin_sectors); limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT; } 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); } set_discard_limits(cache, limits); } /*----------------------------------------------------------------*/ static struct target_type cache_target = { .name = "cache", .version = {1, 9, 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; r = dm_register_target(&cache_target); if (r) { DMERR("cache target registration failed: %d", r); return r; } migration_cache = KMEM_CACHE(dm_cache_migration, 0); if (!migration_cache) { dm_unregister_target(&cache_target); return -ENOMEM; } 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 "); MODULE_LICENSE("GPL");