| /* |
| * 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 <linux/dm-io.h> |
| #include <linux/dm-kcopyd.h> |
| #include <linux/init.h> |
| #include <linux/mempool.h> |
| #include <linux/module.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 |
| */ |
| |
| /*----------------------------------------------------------------*/ |
| |
| static size_t bitset_size_in_bytes(unsigned nr_entries) |
| { |
| return sizeof(unsigned long) * dm_div_up(nr_entries, BITS_PER_LONG); |
| } |
| |
| static unsigned long *alloc_bitset(unsigned nr_entries) |
| { |
| size_t s = bitset_size_in_bytes(nr_entries); |
| return vzalloc(s); |
| } |
| |
| static void clear_bitset(void *bitset, unsigned nr_entries) |
| { |
| size_t s = bitset_size_in_bytes(nr_entries); |
| memset(bitset, 0, s); |
| } |
| |
| static void free_bitset(unsigned long *bits) |
| { |
| vfree(bits); |
| } |
| |
| /*----------------------------------------------------------------*/ |
| |
| /* |
| * 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; |
| void *bi_private; |
| }; |
| |
| 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; |
| h->bi_private = bio->bi_private; |
| |
| 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; |
| bio->bi_private = h->bi_private; |
| } |
| |
| /*----------------------------------------------------------------*/ |
| |
| #define PRISON_CELLS 1024 |
| #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) |
| |
| /* |
| * FIXME: the cache is read/write for the time being. |
| */ |
| enum cache_metadata_mode { |
| CM_WRITE, /* metadata may be changed */ |
| CM_READ_ONLY, /* metadata may not be changed */ |
| }; |
| |
| 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. |
| */ |
| uint32_t sectors_per_block; |
| int sectors_per_block_shift; |
| |
| spinlock_t lock; |
| 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_migrations; |
| |
| wait_queue_head_t quiescing_wait; |
| atomic_t quiescing; |
| atomic_t quiescing_ack; |
| |
| /* |
| * cache_size entries, dirty if set |
| */ |
| dm_cblock_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_migration *next_migration; |
| |
| 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 per_bio_data { |
| bool tick:1; |
| unsigned req_nr:2; |
| struct dm_deferred_entry *all_io_entry; |
| |
| /* |
| * 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_hook_info hook_info; |
| 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 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 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 int prealloc_data_structs(struct cache *cache, struct prealloc *p) |
| { |
| if (!p->mg) { |
| p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT); |
| 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) |
| mempool_free(p->mg, cache->migration_pool); |
| } |
| |
| 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 oblock, struct dm_cell_key *key) |
| { |
| key->virtual = 0; |
| key->dev = 0; |
| key->block = from_oblock(oblock); |
| } |
| |
| /* |
| * 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(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) |
| { |
| int r; |
| struct dm_cell_key key; |
| |
| build_key(oblock, &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 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, &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)) { |
| cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) + 1); |
| 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); |
| cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) - 1); |
| if (!from_cblock(cache->nr_dirty)) |
| 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_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock) |
| { |
| uint32_t discard_blocks = cache->discard_block_size; |
| dm_block_t b = from_oblock(oblock); |
| |
| if (!block_size_is_power_of_two(cache)) |
| discard_blocks = discard_blocks / cache->sectors_per_block; |
| else |
| discard_blocks >>= cache->sectors_per_block_shift; |
| |
| b = block_div(b, discard_blocks); |
| |
| return to_dblock(b); |
| } |
| |
| static void set_discard(struct cache *cache, dm_dblock_t b) |
| { |
| unsigned long flags; |
| |
| 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; |
| |
| 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; |
| |
| 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; |
| |
| bio->bi_bdev = cache->cache_dev->bdev; |
| if (!block_size_is_power_of_two(cache)) |
| bio->bi_iter.bi_sector = |
| (from_cblock(cblock) * cache->sectors_per_block) + |
| sector_div(bi_sector, cache->sectors_per_block); |
| else |
| bio->bi_iter.bi_sector = |
| (from_cblock(cblock) << 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_rw & (REQ_FUA | REQ_FLUSH | REQ_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_rw & (REQ_FLUSH | REQ_FUA); |
| } |
| |
| static void issue(struct cache *cache, struct bio *bio) |
| { |
| unsigned long flags; |
| |
| if (!bio_triggers_commit(cache, bio)) { |
| generic_make_request(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 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, int err) |
| { |
| struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT); |
| |
| dm_unhook_bio(&pb->hook_info, bio); |
| |
| /* |
| * Must bump bi_remaining to allow bio to complete with |
| * restored bi_end_io. |
| */ |
| atomic_inc(&bio->bi_remaining); |
| |
| if (err) { |
| bio_endio(bio, err); |
| 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); |
| } |
| |
| /*---------------------------------------------------------------- |
| * Migration processing |
| * |
| * Migration covers moving data from the origin device to the cache, or |
| * vice versa. |
| *--------------------------------------------------------------*/ |
| static void free_migration(struct dm_cache_migration *mg) |
| { |
| mempool_free(mg, mg->cache->migration_pool); |
| } |
| |
| static void inc_nr_migrations(struct cache *cache) |
| { |
| atomic_inc(&cache->nr_migrations); |
| } |
| |
| static void dec_nr_migrations(struct cache *cache) |
| { |
| atomic_dec(&cache->nr_migrations); |
| |
| /* |
| * Wake the worker in case we're suspending the target. |
| */ |
| wake_up(&cache->migration_wait); |
| } |
| |
| static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, |
| bool holder) |
| { |
| (holder ? dm_cell_release : dm_cell_release_no_holder) |
| (cache->prison, cell, &cache->deferred_bios); |
| free_prison_cell(cache, cell); |
| } |
| |
| static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, |
| bool holder) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&cache->lock, flags); |
| __cell_defer(cache, cell, holder); |
| spin_unlock_irqrestore(&cache->lock, flags); |
| |
| wake_worker(cache); |
| } |
| |
| static void cleanup_migration(struct dm_cache_migration *mg) |
| { |
| struct cache *cache = mg->cache; |
| free_migration(mg); |
| dec_nr_migrations(cache); |
| } |
| |
| static void migration_failure(struct dm_cache_migration *mg) |
| { |
| struct cache *cache = mg->cache; |
| |
| if (mg->writeback) { |
| DMWARN_LIMIT("writeback failed; couldn't copy block"); |
| set_dirty(cache, mg->old_oblock, mg->cblock); |
| cell_defer(cache, mg->old_ocell, false); |
| |
| } else if (mg->demote) { |
| DMWARN_LIMIT("demotion failed; couldn't copy block"); |
| 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 { |
| DMWARN_LIMIT("promotion failed; couldn't copy block"); |
| policy_remove_mapping(cache->policy, mg->new_oblock); |
| cell_defer(cache, mg->new_ocell, true); |
| } |
| |
| cleanup_migration(mg); |
| } |
| |
| static void migration_success_pre_commit(struct dm_cache_migration *mg) |
| { |
| unsigned long flags; |
| struct cache *cache = mg->cache; |
| |
| if (mg->writeback) { |
| cell_defer(cache, mg->old_ocell, false); |
| clear_dirty(cache, mg->old_oblock, mg->cblock); |
| cleanup_migration(mg); |
| return; |
| |
| } else if (mg->demote) { |
| if (dm_cache_remove_mapping(cache->cmd, mg->cblock)) { |
| DMWARN_LIMIT("demotion failed; couldn't update on disk metadata"); |
| policy_force_mapping(cache->policy, mg->new_oblock, |
| mg->old_oblock); |
| if (mg->promote) |
| cell_defer(cache, mg->new_ocell, true); |
| cleanup_migration(mg); |
| return; |
| } |
| } else { |
| if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) { |
| DMWARN_LIMIT("promotion failed; couldn't update on disk metadata"); |
| policy_remove_mapping(cache->policy, mg->new_oblock); |
| cleanup_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("writeback unexpectedly triggered commit"); |
| 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); |
| cleanup_migration(mg); |
| } |
| |
| } else { |
| if (mg->requeue_holder) |
| cell_defer(cache, mg->new_ocell, true); |
| else { |
| bio_endio(mg->new_ocell->holder, 0); |
| cell_defer(cache, mg->new_ocell, false); |
| } |
| clear_dirty(cache, mg->new_oblock, mg->cblock); |
| cleanup_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_real(struct dm_cache_migration *mg) |
| { |
| int r; |
| struct dm_io_region o_region, c_region; |
| struct cache *cache = mg->cache; |
| |
| o_region.bdev = cache->origin_dev->bdev; |
| o_region.count = cache->sectors_per_block; |
| |
| c_region.bdev = cache->cache_dev->bdev; |
| c_region.sector = from_cblock(mg->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("issuing migration failed"); |
| migration_failure(mg); |
| } |
| } |
| |
| static void overwrite_endio(struct bio *bio, int err) |
| { |
| 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; |
| |
| if (err) |
| mg->err = true; |
| |
| spin_lock_irqsave(&cache->lock, flags); |
| list_add_tail(&mg->list, &cache->completed_migrations); |
| dm_unhook_bio(&pb->hook_info, bio); |
| mg->requeue_holder = false; |
| 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); |
| generic_make_request(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 issue_copy(struct dm_cache_migration *mg) |
| { |
| bool avoid; |
| struct cache *cache = mg->cache; |
| |
| 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 (!avoid && bio_writes_complete_block(cache, bio)) { |
| issue_overwrite(mg, bio); |
| return; |
| } |
| } |
| |
| avoid ? avoid_copy(mg) : issue_copy_real(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); |
| if (pb->all_io_entry) |
| 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->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_nr_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->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_nr_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->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_nr_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->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_nr_migrations(cache); |
| 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); |
| |
| issue(cache, bio); |
| } |
| |
| /* |
| * People generally discard large parts of a device, eg, the whole device |
| * when formatting. Splitting these large discards up into cache block |
| * sized ios and then quiescing (always neccessary for discard) takes too |
| * long. |
| * |
| * We keep it simple, and allow any size of discard to come in, and just |
| * mark off blocks on the discard bitset. No passdown occurs! |
| * |
| * To implement passdown we need to change the bio_prison such that a cell |
| * can have a key that spans many blocks. |
| */ |
| static void process_discard_bio(struct cache *cache, struct bio *bio) |
| { |
| dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector, |
| cache->discard_block_size); |
| dm_block_t end_block = bio_end_sector(bio); |
| dm_block_t b; |
| |
| end_block = block_div(end_block, cache->discard_block_size); |
| |
| for (b = start_block; b < end_block; b++) |
| set_discard(cache, to_dblock(b)); |
| |
| bio_endio(bio, 0); |
| } |
| |
| static bool spare_migration_bandwidth(struct cache *cache) |
| { |
| sector_t current_volume = (atomic_read(&cache->nr_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); |
| } |
| |
| static void issue_cache_bio(struct cache *cache, struct bio *bio, |
| struct per_bio_data *pb, |
| dm_oblock_t oblock, dm_cblock_t cblock) |
| { |
| pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); |
| remap_to_cache_dirty(cache, bio, oblock, cblock); |
| issue(cache, bio); |
| } |
| |
| static void process_bio(struct cache *cache, struct prealloc *structs, |
| struct bio *bio) |
| { |
| int r; |
| bool release_cell = true; |
| dm_oblock_t block = get_bio_block(cache, bio); |
| struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell; |
| struct policy_result lookup_result; |
| size_t pb_data_size = get_per_bio_data_size(cache); |
| struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); |
| bool discarded_block = is_discarded_oblock(cache, block); |
| bool passthrough = passthrough_mode(&cache->features); |
| bool can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache)); |
| |
| /* |
| * 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; |
| |
| r = policy_map(cache->policy, block, true, can_migrate, discarded_block, |
| bio, &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() */ |
| pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); |
| remap_to_origin_clear_discard(cache, bio, block); |
| issue(cache, bio); |
| } |
| } else { |
| inc_hit_counter(cache, bio); |
| |
| if (bio_data_dir(bio) == WRITE && |
| writethrough_mode(&cache->features) && |
| !is_dirty(cache, lookup_result.cblock)) { |
| pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); |
| remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock); |
| issue(cache, bio); |
| } else |
| issue_cache_bio(cache, bio, pb, block, lookup_result.cblock); |
| } |
| |
| break; |
| |
| case POLICY_MISS: |
| inc_miss_counter(cache, bio); |
| pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); |
| remap_to_origin_clear_discard(cache, bio, block); |
| issue(cache, bio); |
| 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: |
| cell_prealloc = prealloc_get_cell(structs); |
| r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc, |
| (cell_free_fn) prealloc_put_cell, |
| structs, &old_ocell); |
| if (r > 0) { |
| /* |
| * We have to be careful to avoid lock inversion of |
| * the cells. So we back off, and wait for the |
| * old_ocell to become free. |
| */ |
| policy_force_mapping(cache->policy, block, |
| lookup_result.old_oblock); |
| atomic_inc(&cache->stats.cache_cell_clash); |
| break; |
| } |
| atomic_inc(&cache->stats.demotion); |
| atomic_inc(&cache->stats.promotion); |
| |
| demote_then_promote(cache, structs, lookup_result.old_oblock, |
| block, lookup_result.cblock, |
| old_ocell, new_ocell); |
| release_cell = false; |
| break; |
| |
| default: |
| DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__, |
| (unsigned) lookup_result.op); |
| bio_io_error(bio); |
| } |
| |
| if (release_cell) |
| cell_defer(cache, new_ocell, false); |
| } |
| |
| static int need_commit_due_to_time(struct cache *cache) |
| { |
| return jiffies < cache->last_commit_jiffies || |
| jiffies > cache->last_commit_jiffies + COMMIT_PERIOD; |
| } |
| |
| 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)) { |
| atomic_inc(&cache->stats.commit_count); |
| cache->commit_requested = false; |
| r = dm_cache_commit(cache->cmd, false); |
| cache->last_commit_jiffies = jiffies; |
| } |
| |
| return r; |
| } |
| |
| static void process_deferred_bios(struct cache *cache) |
| { |
| 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. |
| */ |
| 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_rw & REQ_FLUSH) |
| process_flush_bio(cache, bio); |
| else if (bio->bi_rw & REQ_DISCARD) |
| process_discard_bio(cache, bio); |
| else |
| process_bio(cache, &structs, bio); |
| } |
| |
| 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); |
| |
| while ((bio = bio_list_pop(&bios))) |
| submit_bios ? generic_make_request(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); |
| |
| while ((bio = bio_list_pop(&bios))) |
| generic_make_request(bio); |
| } |
| |
| static void writeback_some_dirty_blocks(struct cache *cache) |
| { |
| int r = 0; |
| dm_oblock_t oblock; |
| dm_cblock_t cblock; |
| struct prealloc structs; |
| struct dm_bio_prison_cell *old_ocell; |
| |
| memset(&structs, 0, sizeof(structs)); |
| |
| while (spare_migration_bandwidth(cache)) { |
| if (prealloc_data_structs(cache, &structs)) |
| break; |
| |
| r = policy_writeback_work(cache->policy, &oblock, &cblock); |
| if (r) |
| break; |
| |
| r = get_cell(cache, oblock, &structs, &old_ocell); |
| if (r) { |
| policy_set_dirty(cache->policy, oblock); |
| break; |
| } |
| |
| writeback(cache, &structs, oblock, cblock, old_ocell); |
| } |
| |
| 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) |
| break; |
| |
| } else if (r == -ENODATA) { |
| /* harmless, already unmapped */ |
| r = 0; |
| |
| } else { |
| DMERR("policy_remove_cblock failed"); |
| 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_migrations)); |
| } |
| |
| static void stop_worker(struct cache *cache) |
| { |
| cancel_delayed_work(&cache->waker); |
| flush_workqueue(cache->wq); |
| } |
| |
| static void requeue_deferred_io(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_endio(bio, DM_ENDIO_REQUEUE); |
| } |
| |
| 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) || |
| !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_invalidation_requests(cache); |
| } |
| |
| process_migrations(cache, &cache->quiesced_migrations, issue_copy); |
| process_migrations(cache, &cache->completed_migrations, complete_migration); |
| |
| if (commit_if_needed(cache)) { |
| process_deferred_flush_bios(cache, false); |
| |
| /* |
| * FIXME: rollback metadata or just go into a |
| * failure mode and error everything |
| */ |
| } 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); |
| 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; |
| |
| if (cache->next_migration) |
| mempool_free(cache->next_migration, cache->migration_pool); |
| |
| if (cache->migration_pool) |
| 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 <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; |
| 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 <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; |
| |
| return 0; |
| } |
| |
| /* |
| * We want the discard block size to be a power of two, 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; |
| |
| discard_block_size = roundup_pow_of_two(cache_block_size); |
| |
| if (origin_size) |
| while (too_many_discard_blocks(discard_block_size, origin_size)) |
| discard_block_size *= 2; |
| |
| return discard_block_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; |
| |
| cache->features = ca->features; |
| ti->per_bio_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); |
| cache->cache_size = to_cblock(cache_size); |
| } else { |
| cache->sectors_per_block_shift = __ffs(ca->block_size); |
| cache->cache_size = 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; |
| |
| 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); |
| 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_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; |
| 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 = oblock_to_dblock(cache, cache->origin_blocks); |
| 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(PRISON_CELLS); |
| 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->next_migration = NULL; |
| |
| 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); |
| |
| *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; |
| 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 discarded_block; |
| struct dm_bio_prison_cell *cell; |
| struct policy_result lookup_result; |
| struct per_bio_data *pb; |
| |
| if (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_clear_discard(cache, bio, block); |
| return DM_MAPIO_REMAPPED; |
| } |
| |
| pb = init_per_bio_data(bio, pb_data_size); |
| |
| if (bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD)) { |
| 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; |
| } |
| |
| discarded_block = is_discarded_oblock(cache, block); |
| |
| r = policy_map(cache->policy, block, false, can_migrate, discarded_block, |
| bio, &lookup_result); |
| if (r == -EWOULDBLOCK) { |
| cell_defer(cache, cell, true); |
| return DM_MAPIO_SUBMITTED; |
| |
| } else if (r) { |
| DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r); |
| 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 { |
| pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); |
| inc_miss_counter(cache, bio); |
| remap_to_origin_clear_discard(cache, bio, block); |
| |
| 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); |
| else |
| remap_to_cache_dirty(cache, bio, block, lookup_result.cblock); |
| |
| cell_defer(cache, cell, false); |
| } |
| break; |
| |
| case POLICY_MISS: |
| inc_miss_counter(cache, bio); |
| pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); |
| |
| 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, 0); |
| cell_defer(cache, cell, false); |
| return DM_MAPIO_SUBMITTED; |
| } else { |
| remap_to_origin_clear_discard(cache, bio, block); |
| cell_defer(cache, cell, false); |
| } |
| break; |
| |
| default: |
| DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__, |
| (unsigned) lookup_result.op); |
| 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); |
| |
| spin_lock_irqsave(&cache->lock, flags); |
| cache->need_tick_bio = true; |
| spin_unlock_irqrestore(&cache->lock, flags); |
| } |
| |
| check_for_quiesced_migrations(cache, pb); |
| |
| return 0; |
| } |
| |
| static int write_dirty_bitset(struct cache *cache) |
| { |
| unsigned i, r; |
| |
| 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) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| static int write_discard_bitset(struct cache *cache) |
| { |
| unsigned i, r; |
| |
| r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size, |
| cache->discard_nr_blocks); |
| if (r) { |
| DMERR("could not resize on-disk discard bitset"); |
| 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) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, |
| uint32_t hint) |
| { |
| struct cache *cache = context; |
| return dm_cache_save_hint(cache->cmd, cblock, hint); |
| } |
| |
| static int write_hints(struct cache *cache) |
| { |
| int r; |
| |
| r = dm_cache_begin_hints(cache->cmd, cache->policy); |
| if (r) { |
| DMERR("dm_cache_begin_hints failed"); |
| return r; |
| } |
| |
| r = policy_walk_mappings(cache->policy, save_hint, cache); |
| if (r) |
| DMERR("policy_walk_mappings failed"); |
| |
| return r; |
| } |
| |
| /* |
| * returns true on success |
| */ |
| static bool sync_metadata(struct cache *cache) |
| { |
| int r1, r2, r3, r4; |
| |
| r1 = write_dirty_bitset(cache); |
| if (r1) |
| DMERR("could not write dirty bitset"); |
| |
| r2 = write_discard_bitset(cache); |
| if (r2) |
| DMERR("could not write discard bitset"); |
| |
| save_stats(cache); |
| |
| r3 = write_hints(cache); |
| if (r3) |
| DMERR("could not write hints"); |
| |
| /* |
| * 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 = dm_cache_commit(cache->cmd, !r1 && !r2 && !r3); |
| if (r4) |
| DMERR("could not write cache metadata. Data loss may occur."); |
| |
| 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_io(cache); |
| stop_quiescing(cache); |
| |
| (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; |
| } |
| |
| static int load_discard(void *context, sector_t discard_block_size, |
| dm_dblock_t dblock, bool discard) |
| { |
| struct cache *cache = context; |
| |
| /* FIXME: handle mis-matched block size */ |
| |
| if (discard) |
| set_discard(cache, dblock); |
| else |
| clear_discard(cache, dblock); |
| |
| 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("unable to shrink cache; cache block %llu is dirty", |
| (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, cache->cache_size); |
| if (r) { |
| DMERR("could not resize cache metadata"); |
| return r; |
| } |
| |
| cache->cache_size = 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("could not load cache mappings"); |
| return r; |
| } |
| |
| cache->loaded_mappings = true; |
| } |
| |
| if (!cache->loaded_discards) { |
| r = dm_cache_load_discards(cache->cmd, load_discard, cache); |
| if (r) { |
| DMERR("could not load origin discards"); |
| return r; |
| } |
| |
| 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> |
| * <#read hits> <#read misses> <#write hits> <#write misses> |
| * <#demotions> <#promotions> <#blocks in cache> <#dirty> |
| * <#features> <features>* |
| * <#core args> <core args> |
| * <#policy 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; |
| |
| switch (type) { |
| case STATUSTYPE_INFO: |
| /* Commit to ensure statistics aren't out-of-date */ |
| if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) { |
| r = dm_cache_commit(cache->cmd, false); |
| if (r) |
| DMERR("could not commit metadata for accurate status"); |
| } |
| |
| r = dm_cache_get_free_metadata_block_count(cache->cmd, |
| &nr_free_blocks_metadata); |
| if (r) { |
| DMERR("could not get metadata free block count"); |
| goto err; |
| } |
| |
| r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata); |
| if (r) { |
| DMERR("could not get metadata device size"); |
| goto err; |
| } |
| |
| residency = policy_residency(cache->policy); |
| |
| DMEMIT("%llu/%llu %u %u %u %u %u %u %llu %u ", |
| (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata), |
| (unsigned long long)nr_blocks_metadata, |
| (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 long) from_cblock(residency), |
| 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("internal error: unknown io mode: %d", (int) cache->features.io_mode); |
| goto err; |
| } |
| |
| DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold); |
| if (sz < maxlen) { |
| r = policy_emit_config_values(cache->policy, result + sz, maxlen - sz); |
| if (r) |
| DMERR("policy_emit_config_values returned %d", r); |
| } |
| |
| 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("invalid cblock range '%s'", 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("begin cblock out of range: %llu >= %llu", b, n); |
| return -EINVAL; |
| } |
| |
| if (e > n) { |
| DMERR("end cblock out of range: %llu > %llu", e, n); |
| return -EINVAL; |
| } |
| |
| if (b >= e) { |
| DMERR("invalid cblock range: %llu >= %llu", 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("cache has to be in passthrough mode for invalidation"); |
| 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 argc, char **argv) |
| { |
| struct cache *cache = ti->private; |
| |
| if (!argc) |
| return -EINVAL; |
| |
| 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; |
| } |
| |
| /* |
| * We assume I/O is going to the origin (which is the volume |
| * more likely to have restrictions e.g. by being striped). |
| * (Looking up the exact location of the data would be expensive |
| * and could always be out of date by the time the bio is submitted.) |
| */ |
| static int cache_bvec_merge(struct dm_target *ti, |
| struct bvec_merge_data *bvm, |
| struct bio_vec *biovec, int max_size) |
| { |
| struct cache *cache = ti->private; |
| struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev); |
| |
| if (!q->merge_bvec_fn) |
| return max_size; |
| |
| bvm->bi_bdev = cache->origin_dev->bdev; |
| return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); |
| } |
| |
| 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 = cache->discard_block_size * 1024; |
| 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, 0); |
| 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, 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, |
| .merge = cache_bvec_merge, |
| .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 <ejt@redhat.com>"); |
| MODULE_LICENSE("GPL"); |