v4.19.13 snapshot.
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
new file mode 100644
index 0000000..b29a832
--- /dev/null
+++ b/drivers/md/dm-cache-target.c
@@ -0,0 +1,3511 @@
+/*
+ * Copyright (C) 2012 Red Hat. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include "dm-bio-prison-v2.h"
+#include "dm-bio-record.h"
+#include "dm-cache-metadata.h"
+
+#include <linux/dm-io.h>
+#include <linux/dm-kcopyd.h>
+#include <linux/jiffies.h>
+#include <linux/init.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/rwsem.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#define DM_MSG_PREFIX "cache"
+
+DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
+ "A percentage of time allocated for copying to and/or from cache");
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Glossary:
+ *
+ * oblock: index of an origin block
+ * cblock: index of a cache block
+ * promotion: movement of a block from origin to cache
+ * demotion: movement of a block from cache to origin
+ * migration: movement of a block between the origin and cache device,
+ * either direction
+ */
+
+/*----------------------------------------------------------------*/
+
+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)
+{
+ if (!len)
+ return;
+
+ 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);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Represents a chunk of future work. 'input' allows continuations to pass
+ * values between themselves, typically error values.
+ */
+struct continuation {
+ struct work_struct ws;
+ blk_status_t input;
+};
+
+static inline void init_continuation(struct continuation *k,
+ void (*fn)(struct work_struct *))
+{
+ INIT_WORK(&k->ws, fn);
+ k->input = 0;
+}
+
+static inline void queue_continuation(struct workqueue_struct *wq,
+ struct continuation *k)
+{
+ queue_work(wq, &k->ws);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * The batcher collects together pieces of work that need a particular
+ * operation to occur before they can proceed (typically a commit).
+ */
+struct batcher {
+ /*
+ * The operation that everyone is waiting for.
+ */
+ blk_status_t (*commit_op)(void *context);
+ void *commit_context;
+
+ /*
+ * This is how bios should be issued once the commit op is complete
+ * (accounted_request).
+ */
+ void (*issue_op)(struct bio *bio, void *context);
+ void *issue_context;
+
+ /*
+ * Queued work gets put on here after commit.
+ */
+ struct workqueue_struct *wq;
+
+ spinlock_t lock;
+ struct list_head work_items;
+ struct bio_list bios;
+ struct work_struct commit_work;
+
+ bool commit_scheduled;
+};
+
+static void __commit(struct work_struct *_ws)
+{
+ struct batcher *b = container_of(_ws, struct batcher, commit_work);
+ blk_status_t r;
+ unsigned long flags;
+ struct list_head work_items;
+ struct work_struct *ws, *tmp;
+ struct continuation *k;
+ struct bio *bio;
+ struct bio_list bios;
+
+ INIT_LIST_HEAD(&work_items);
+ bio_list_init(&bios);
+
+ /*
+ * We have to grab these before the commit_op to avoid a race
+ * condition.
+ */
+ spin_lock_irqsave(&b->lock, flags);
+ list_splice_init(&b->work_items, &work_items);
+ bio_list_merge(&bios, &b->bios);
+ bio_list_init(&b->bios);
+ b->commit_scheduled = false;
+ spin_unlock_irqrestore(&b->lock, flags);
+
+ r = b->commit_op(b->commit_context);
+
+ list_for_each_entry_safe(ws, tmp, &work_items, entry) {
+ k = container_of(ws, struct continuation, ws);
+ k->input = r;
+ INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
+ queue_work(b->wq, ws);
+ }
+
+ while ((bio = bio_list_pop(&bios))) {
+ if (r) {
+ bio->bi_status = r;
+ bio_endio(bio);
+ } else
+ b->issue_op(bio, b->issue_context);
+ }
+}
+
+static void batcher_init(struct batcher *b,
+ blk_status_t (*commit_op)(void *),
+ void *commit_context,
+ void (*issue_op)(struct bio *bio, void *),
+ void *issue_context,
+ struct workqueue_struct *wq)
+{
+ b->commit_op = commit_op;
+ b->commit_context = commit_context;
+ b->issue_op = issue_op;
+ b->issue_context = issue_context;
+ b->wq = wq;
+
+ spin_lock_init(&b->lock);
+ INIT_LIST_HEAD(&b->work_items);
+ bio_list_init(&b->bios);
+ INIT_WORK(&b->commit_work, __commit);
+ b->commit_scheduled = false;
+}
+
+static void async_commit(struct batcher *b)
+{
+ queue_work(b->wq, &b->commit_work);
+}
+
+static void continue_after_commit(struct batcher *b, struct continuation *k)
+{
+ unsigned long flags;
+ bool commit_scheduled;
+
+ spin_lock_irqsave(&b->lock, flags);
+ commit_scheduled = b->commit_scheduled;
+ list_add_tail(&k->ws.entry, &b->work_items);
+ spin_unlock_irqrestore(&b->lock, flags);
+
+ if (commit_scheduled)
+ async_commit(b);
+}
+
+/*
+ * Bios are errored if commit failed.
+ */
+static void issue_after_commit(struct batcher *b, struct bio *bio)
+{
+ unsigned long flags;
+ bool commit_scheduled;
+
+ spin_lock_irqsave(&b->lock, flags);
+ commit_scheduled = b->commit_scheduled;
+ bio_list_add(&b->bios, bio);
+ spin_unlock_irqrestore(&b->lock, flags);
+
+ if (commit_scheduled)
+ async_commit(b);
+}
+
+/*
+ * Call this if some urgent work is waiting for the commit to complete.
+ */
+static void schedule_commit(struct batcher *b)
+{
+ bool immediate;
+ unsigned long flags;
+
+ spin_lock_irqsave(&b->lock, flags);
+ immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
+ b->commit_scheduled = true;
+ spin_unlock_irqrestore(&b->lock, flags);
+
+ if (immediate)
+ async_commit(b);
+}
+
+/*
+ * There are a couple of places where we let a bio run, but want to do some
+ * work before calling its endio function. We do this by temporarily
+ * changing the endio fn.
+ */
+struct dm_hook_info {
+ bio_end_io_t *bi_end_io;
+};
+
+static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
+ bio_end_io_t *bi_end_io, void *bi_private)
+{
+ h->bi_end_io = bio->bi_end_io;
+
+ bio->bi_end_io = bi_end_io;
+ bio->bi_private = bi_private;
+}
+
+static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
+{
+ bio->bi_end_io = h->bi_end_io;
+}
+
+/*----------------------------------------------------------------*/
+
+#define MIGRATION_POOL_SIZE 128
+#define COMMIT_PERIOD HZ
+#define MIGRATION_COUNT_WINDOW 10
+
+/*
+ * The block size of the device holding cache data must be
+ * between 32KB and 1GB.
+ */
+#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
+#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
+
+enum cache_metadata_mode {
+ CM_WRITE, /* metadata may be changed */
+ CM_READ_ONLY, /* metadata may not be changed */
+ CM_FAIL
+};
+
+enum cache_io_mode {
+ /*
+ * Data is written to cached blocks only. These blocks are marked
+ * dirty. If you lose the cache device you will lose data.
+ * Potential performance increase for both reads and writes.
+ */
+ CM_IO_WRITEBACK,
+
+ /*
+ * Data is written to both cache and origin. Blocks are never
+ * dirty. Potential performance benfit for reads only.
+ */
+ CM_IO_WRITETHROUGH,
+
+ /*
+ * A degraded mode useful for various cache coherency situations
+ * (eg, rolling back snapshots). Reads and writes always go to the
+ * origin. If a write goes to a cached oblock, then the cache
+ * block is invalidated.
+ */
+ CM_IO_PASSTHROUGH
+};
+
+struct cache_features {
+ enum cache_metadata_mode mode;
+ enum cache_io_mode io_mode;
+ unsigned metadata_version;
+};
+
+struct cache_stats {
+ atomic_t read_hit;
+ atomic_t read_miss;
+ atomic_t write_hit;
+ atomic_t write_miss;
+ atomic_t demotion;
+ atomic_t promotion;
+ atomic_t writeback;
+ atomic_t copies_avoided;
+ atomic_t cache_cell_clash;
+ atomic_t commit_count;
+ atomic_t discard_count;
+};
+
+struct cache {
+ struct dm_target *ti;
+ spinlock_t lock;
+
+ /*
+ * Fields for converting from sectors to blocks.
+ */
+ int sectors_per_block_shift;
+ sector_t sectors_per_block;
+
+ struct dm_cache_metadata *cmd;
+
+ /*
+ * Metadata is written to this device.
+ */
+ struct dm_dev *metadata_dev;
+
+ /*
+ * The slower of the two data devices. Typically a spindle.
+ */
+ struct dm_dev *origin_dev;
+
+ /*
+ * The faster of the two data devices. Typically an SSD.
+ */
+ struct dm_dev *cache_dev;
+
+ /*
+ * Size of the origin device in _complete_ blocks and native sectors.
+ */
+ dm_oblock_t origin_blocks;
+ sector_t origin_sectors;
+
+ /*
+ * Size of the cache device in blocks.
+ */
+ dm_cblock_t cache_size;
+
+ /*
+ * Invalidation fields.
+ */
+ spinlock_t invalidation_lock;
+ struct list_head invalidation_requests;
+
+ sector_t migration_threshold;
+ wait_queue_head_t migration_wait;
+ atomic_t nr_allocated_migrations;
+
+ /*
+ * The number of in flight migrations that are performing
+ * background io. eg, promotion, writeback.
+ */
+ atomic_t nr_io_migrations;
+
+ struct bio_list deferred_bios;
+
+ struct rw_semaphore quiesce_lock;
+
+ struct dm_target_callbacks callbacks;
+
+ /*
+ * 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 work_struct deferred_bio_worker;
+ struct work_struct migration_worker;
+ struct workqueue_struct *wq;
+ struct delayed_work waker;
+ struct dm_bio_prison_v2 *prison;
+
+ /*
+ * cache_size entries, dirty if set
+ */
+ unsigned long *dirty_bitset;
+ atomic_t nr_dirty;
+
+ unsigned policy_nr_args;
+ struct dm_cache_policy *policy;
+
+ /*
+ * Cache features such as write-through.
+ */
+ struct cache_features features;
+
+ struct cache_stats stats;
+
+ bool need_tick_bio:1;
+ bool sized:1;
+ bool invalidate:1;
+ bool commit_requested:1;
+ bool loaded_mappings:1;
+ bool loaded_discards:1;
+
+ struct rw_semaphore background_work_lock;
+
+ struct batcher committer;
+ struct work_struct commit_ws;
+
+ struct io_tracker tracker;
+
+ mempool_t migration_pool;
+
+ struct bio_set bs;
+};
+
+struct per_bio_data {
+ bool tick:1;
+ unsigned req_nr:2;
+ struct dm_bio_prison_cell_v2 *cell;
+ struct dm_hook_info hook_info;
+ sector_t len;
+};
+
+struct dm_cache_migration {
+ struct continuation k;
+ struct cache *cache;
+
+ struct policy_work *op;
+ struct bio *overwrite_bio;
+ struct dm_bio_prison_cell_v2 *cell;
+
+ dm_cblock_t invalidate_cblock;
+ dm_oblock_t invalidate_oblock;
+};
+
+/*----------------------------------------------------------------*/
+
+static bool writethrough_mode(struct cache *cache)
+{
+ return cache->features.io_mode == CM_IO_WRITETHROUGH;
+}
+
+static bool writeback_mode(struct cache *cache)
+{
+ return cache->features.io_mode == CM_IO_WRITEBACK;
+}
+
+static inline bool passthrough_mode(struct cache *cache)
+{
+ return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
+}
+
+/*----------------------------------------------------------------*/
+
+static void wake_deferred_bio_worker(struct cache *cache)
+{
+ queue_work(cache->wq, &cache->deferred_bio_worker);
+}
+
+static void wake_migration_worker(struct cache *cache)
+{
+ if (passthrough_mode(cache))
+ return;
+
+ queue_work(cache->wq, &cache->migration_worker);
+}
+
+/*----------------------------------------------------------------*/
+
+static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
+{
+ return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOWAIT);
+}
+
+static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
+{
+ dm_bio_prison_free_cell_v2(cache->prison, cell);
+}
+
+static struct dm_cache_migration *alloc_migration(struct cache *cache)
+{
+ struct dm_cache_migration *mg;
+
+ mg = mempool_alloc(&cache->migration_pool, GFP_NOWAIT);
+ if (!mg)
+ return NULL;
+
+ memset(mg, 0, sizeof(*mg));
+
+ mg->cache = cache;
+ atomic_inc(&cache->nr_allocated_migrations);
+
+ return mg;
+}
+
+static void free_migration(struct dm_cache_migration *mg)
+{
+ struct cache *cache = mg->cache;
+
+ if (atomic_dec_and_test(&cache->nr_allocated_migrations))
+ wake_up(&cache->migration_wait);
+
+ mempool_free(mg, &cache->migration_pool);
+}
+
+/*----------------------------------------------------------------*/
+
+static inline dm_oblock_t oblock_succ(dm_oblock_t b)
+{
+ return to_oblock(from_oblock(b) + 1ull);
+}
+
+static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
+{
+ key->virtual = 0;
+ key->dev = 0;
+ key->block_begin = from_oblock(begin);
+ key->block_end = from_oblock(end);
+}
+
+/*
+ * We have two lock levels. Level 0, which is used to prevent WRITEs, and
+ * level 1 which prevents *both* READs and WRITEs.
+ */
+#define WRITE_LOCK_LEVEL 0
+#define READ_WRITE_LOCK_LEVEL 1
+
+static unsigned lock_level(struct bio *bio)
+{
+ return bio_data_dir(bio) == WRITE ?
+ WRITE_LOCK_LEVEL :
+ READ_WRITE_LOCK_LEVEL;
+}
+
+/*----------------------------------------------------------------
+ * Per bio data
+ *--------------------------------------------------------------*/
+
+static struct per_bio_data *get_per_bio_data(struct bio *bio)
+{
+ struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
+ BUG_ON(!pb);
+ return pb;
+}
+
+static struct per_bio_data *init_per_bio_data(struct bio *bio)
+{
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ pb->tick = false;
+ pb->req_nr = dm_bio_get_target_bio_nr(bio);
+ pb->cell = NULL;
+ pb->len = 0;
+
+ return pb;
+}
+
+/*----------------------------------------------------------------*/
+
+static void defer_bio(struct cache *cache, struct bio *bio)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cache->lock, flags);
+ bio_list_add(&cache->deferred_bios, bio);
+ spin_unlock_irqrestore(&cache->lock, flags);
+
+ wake_deferred_bio_worker(cache);
+}
+
+static void defer_bios(struct cache *cache, struct bio_list *bios)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cache->lock, flags);
+ bio_list_merge(&cache->deferred_bios, bios);
+ bio_list_init(bios);
+ spin_unlock_irqrestore(&cache->lock, flags);
+
+ wake_deferred_bio_worker(cache);
+}
+
+/*----------------------------------------------------------------*/
+
+static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
+{
+ bool r;
+ struct per_bio_data *pb;
+ struct dm_cell_key_v2 key;
+ dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
+ struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
+
+ cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
+ if (!cell_prealloc) {
+ defer_bio(cache, bio);
+ return false;
+ }
+
+ build_key(oblock, end, &key);
+ r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
+ if (!r) {
+ /*
+ * Failed to get the lock.
+ */
+ free_prison_cell(cache, cell_prealloc);
+ return r;
+ }
+
+ if (cell != cell_prealloc)
+ free_prison_cell(cache, cell_prealloc);
+
+ pb = get_per_bio_data(bio);
+ pb->cell = cell;
+
+ return r;
+}
+
+/*----------------------------------------------------------------*/
+
+static bool is_dirty(struct cache *cache, dm_cblock_t b)
+{
+ return test_bit(from_cblock(b), cache->dirty_bitset);
+}
+
+static void set_dirty(struct cache *cache, dm_cblock_t cblock)
+{
+ if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
+ atomic_inc(&cache->nr_dirty);
+ policy_set_dirty(cache->policy, cblock);
+ }
+}
+
+/*
+ * These two are called when setting after migrations to force the policy
+ * and dirty bitset to be in sync.
+ */
+static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
+{
+ if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
+ atomic_inc(&cache->nr_dirty);
+ policy_set_dirty(cache->policy, cblock);
+}
+
+static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
+{
+ if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
+ if (atomic_dec_return(&cache->nr_dirty) == 0)
+ dm_table_event(cache->ti->table);
+ }
+
+ policy_clear_dirty(cache->policy, cblock);
+}
+
+/*----------------------------------------------------------------*/
+
+static bool block_size_is_power_of_two(struct cache *cache)
+{
+ return cache->sectors_per_block_shift >= 0;
+}
+
+/* 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 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;
+}
+
+/*----------------------------------------------------------------
+ * Remapping
+ *--------------------------------------------------------------*/
+static void remap_to_origin(struct cache *cache, struct bio *bio)
+{
+ bio_set_dev(bio, cache->origin_dev->bdev);
+}
+
+static void remap_to_cache(struct cache *cache, struct bio *bio,
+ dm_cblock_t cblock)
+{
+ sector_t bi_sector = bio->bi_iter.bi_sector;
+ sector_t block = from_cblock(cblock);
+
+ bio_set_dev(bio, cache->cache_dev->bdev);
+ if (!block_size_is_power_of_two(cache))
+ bio->bi_iter.bi_sector =
+ (block * cache->sectors_per_block) +
+ sector_div(bi_sector, cache->sectors_per_block);
+ else
+ bio->bi_iter.bi_sector =
+ (block << cache->sectors_per_block_shift) |
+ (bi_sector & (cache->sectors_per_block - 1));
+}
+
+static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
+{
+ unsigned long flags;
+ struct per_bio_data *pb;
+
+ spin_lock_irqsave(&cache->lock, flags);
+ if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
+ bio_op(bio) != REQ_OP_DISCARD) {
+ pb = get_per_bio_data(bio);
+ pb->tick = true;
+ cache->need_tick_bio = false;
+ }
+ spin_unlock_irqrestore(&cache->lock, flags);
+}
+
+static void __remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
+ dm_oblock_t oblock, bool bio_has_pbd)
+{
+ if (bio_has_pbd)
+ 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_origin_clear_discard(struct cache *cache, struct bio *bio,
+ dm_oblock_t oblock)
+{
+ // FIXME: check_if_tick_bio_needed() is called way too much through this interface
+ __remap_to_origin_clear_discard(cache, bio, oblock, true);
+}
+
+static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
+ dm_oblock_t oblock, dm_cblock_t cblock)
+{
+ check_if_tick_bio_needed(cache, bio);
+ remap_to_cache(cache, bio, cblock);
+ if (bio_data_dir(bio) == WRITE) {
+ set_dirty(cache, cblock);
+ clear_discard(cache, oblock_to_dblock(cache, oblock));
+ }
+}
+
+static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
+{
+ sector_t block_nr = bio->bi_iter.bi_sector;
+
+ if (!block_size_is_power_of_two(cache))
+ (void) sector_div(block_nr, cache->sectors_per_block);
+ else
+ block_nr >>= cache->sectors_per_block_shift;
+
+ return to_oblock(block_nr);
+}
+
+static bool accountable_bio(struct cache *cache, struct bio *bio)
+{
+ return bio_op(bio) != REQ_OP_DISCARD;
+}
+
+static void accounted_begin(struct cache *cache, struct bio *bio)
+{
+ struct per_bio_data *pb;
+
+ if (accountable_bio(cache, bio)) {
+ pb = get_per_bio_data(bio);
+ pb->len = bio_sectors(bio);
+ iot_io_begin(&cache->tracker, pb->len);
+ }
+}
+
+static void accounted_complete(struct cache *cache, struct bio *bio)
+{
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ iot_io_end(&cache->tracker, pb->len);
+}
+
+static void accounted_request(struct cache *cache, struct bio *bio)
+{
+ accounted_begin(cache, bio);
+ generic_make_request(bio);
+}
+
+static void issue_op(struct bio *bio, void *context)
+{
+ struct cache *cache = context;
+ accounted_request(cache, bio);
+}
+
+/*
+ * When running in writethrough mode we need to send writes to clean blocks
+ * to both the cache and origin devices. Clone the bio and send them in parallel.
+ */
+static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
+ dm_oblock_t oblock, dm_cblock_t cblock)
+{
+ struct bio *origin_bio = bio_clone_fast(bio, GFP_NOIO, &cache->bs);
+
+ BUG_ON(!origin_bio);
+
+ bio_chain(origin_bio, bio);
+ /*
+ * Passing false to __remap_to_origin_clear_discard() skips
+ * all code that might use per_bio_data (since clone doesn't have it)
+ */
+ __remap_to_origin_clear_discard(cache, origin_bio, oblock, false);
+ submit_bio(origin_bio);
+
+ remap_to_cache(cache, bio, cblock);
+}
+
+/*----------------------------------------------------------------
+ * Failure modes
+ *--------------------------------------------------------------*/
+static enum cache_metadata_mode get_cache_mode(struct cache *cache)
+{
+ return cache->features.mode;
+}
+
+static const char *cache_device_name(struct cache *cache)
+{
+ return dm_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);
+}
+
+/*----------------------------------------------------------------*/
+
+static void load_stats(struct cache *cache)
+{
+ struct dm_cache_statistics stats;
+
+ dm_cache_metadata_get_stats(cache->cmd, &stats);
+ atomic_set(&cache->stats.read_hit, stats.read_hits);
+ atomic_set(&cache->stats.read_miss, stats.read_misses);
+ atomic_set(&cache->stats.write_hit, stats.write_hits);
+ atomic_set(&cache->stats.write_miss, stats.write_misses);
+}
+
+static void save_stats(struct cache *cache)
+{
+ struct dm_cache_statistics stats;
+
+ if (get_cache_mode(cache) >= CM_READ_ONLY)
+ return;
+
+ stats.read_hits = atomic_read(&cache->stats.read_hit);
+ stats.read_misses = atomic_read(&cache->stats.read_miss);
+ stats.write_hits = atomic_read(&cache->stats.write_hit);
+ stats.write_misses = atomic_read(&cache->stats.write_miss);
+
+ dm_cache_metadata_set_stats(cache->cmd, &stats);
+}
+
+static void update_stats(struct cache_stats *stats, enum policy_operation op)
+{
+ switch (op) {
+ case POLICY_PROMOTE:
+ atomic_inc(&stats->promotion);
+ break;
+
+ case POLICY_DEMOTE:
+ atomic_inc(&stats->demotion);
+ break;
+
+ case POLICY_WRITEBACK:
+ atomic_inc(&stats->writeback);
+ break;
+ }
+}
+
+/*----------------------------------------------------------------
+ * Migration processing
+ *
+ * Migration covers moving data from the origin device to the cache, or
+ * vice versa.
+ *--------------------------------------------------------------*/
+
+static void inc_io_migrations(struct cache *cache)
+{
+ atomic_inc(&cache->nr_io_migrations);
+}
+
+static void dec_io_migrations(struct cache *cache)
+{
+ atomic_dec(&cache->nr_io_migrations);
+}
+
+static bool discard_or_flush(struct bio *bio)
+{
+ return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
+}
+
+static void calc_discard_block_range(struct cache *cache, struct bio *bio,
+ dm_dblock_t *b, dm_dblock_t *e)
+{
+ sector_t sb = bio->bi_iter.bi_sector;
+ sector_t se = bio_end_sector(bio);
+
+ *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
+
+ if (se - sb < cache->discard_block_size)
+ *e = *b;
+ else
+ *e = to_dblock(block_div(se, cache->discard_block_size));
+}
+
+/*----------------------------------------------------------------*/
+
+static void prevent_background_work(struct cache *cache)
+{
+ lockdep_off();
+ down_write(&cache->background_work_lock);
+ lockdep_on();
+}
+
+static void allow_background_work(struct cache *cache)
+{
+ lockdep_off();
+ up_write(&cache->background_work_lock);
+ lockdep_on();
+}
+
+static bool background_work_begin(struct cache *cache)
+{
+ bool r;
+
+ lockdep_off();
+ r = down_read_trylock(&cache->background_work_lock);
+ lockdep_on();
+
+ return r;
+}
+
+static void background_work_end(struct cache *cache)
+{
+ lockdep_off();
+ up_read(&cache->background_work_lock);
+ lockdep_on();
+}
+
+/*----------------------------------------------------------------*/
+
+static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
+{
+ return (bio_data_dir(bio) == WRITE) &&
+ (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
+}
+
+static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
+{
+ return writeback_mode(cache) &&
+ (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
+}
+
+static void quiesce(struct dm_cache_migration *mg,
+ void (*continuation)(struct work_struct *))
+{
+ init_continuation(&mg->k, continuation);
+ dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
+}
+
+static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
+{
+ struct continuation *k = container_of(ws, struct continuation, ws);
+ return container_of(k, struct dm_cache_migration, k);
+}
+
+static void copy_complete(int read_err, unsigned long write_err, void *context)
+{
+ struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
+
+ if (read_err || write_err)
+ mg->k.input = BLK_STS_IOERR;
+
+ queue_continuation(mg->cache->wq, &mg->k);
+}
+
+static void copy(struct dm_cache_migration *mg, bool promote)
+{
+ struct dm_io_region o_region, c_region;
+ struct cache *cache = mg->cache;
+
+ o_region.bdev = cache->origin_dev->bdev;
+ o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
+ o_region.count = cache->sectors_per_block;
+
+ c_region.bdev = cache->cache_dev->bdev;
+ c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
+ c_region.count = cache->sectors_per_block;
+
+ if (promote)
+ dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
+ else
+ dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
+}
+
+static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
+{
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
+ free_prison_cell(cache, pb->cell);
+ pb->cell = NULL;
+}
+
+static void overwrite_endio(struct bio *bio)
+{
+ struct dm_cache_migration *mg = bio->bi_private;
+ struct cache *cache = mg->cache;
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ dm_unhook_bio(&pb->hook_info, bio);
+
+ if (bio->bi_status)
+ mg->k.input = bio->bi_status;
+
+ queue_continuation(cache->wq, &mg->k);
+}
+
+static void overwrite(struct dm_cache_migration *mg,
+ void (*continuation)(struct work_struct *))
+{
+ struct bio *bio = mg->overwrite_bio;
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
+
+ /*
+ * The overwrite bio is part of the copy operation, as such it does
+ * not set/clear discard or dirty flags.
+ */
+ if (mg->op->op == POLICY_PROMOTE)
+ remap_to_cache(mg->cache, bio, mg->op->cblock);
+ else
+ remap_to_origin(mg->cache, bio);
+
+ init_continuation(&mg->k, continuation);
+ accounted_request(mg->cache, bio);
+}
+
+/*
+ * Migration steps:
+ *
+ * 1) exclusive lock preventing WRITEs
+ * 2) quiesce
+ * 3) copy or issue overwrite bio
+ * 4) upgrade to exclusive lock preventing READs and WRITEs
+ * 5) quiesce
+ * 6) update metadata and commit
+ * 7) unlock
+ */
+static void mg_complete(struct dm_cache_migration *mg, bool success)
+{
+ struct bio_list bios;
+ struct cache *cache = mg->cache;
+ struct policy_work *op = mg->op;
+ dm_cblock_t cblock = op->cblock;
+
+ if (success)
+ update_stats(&cache->stats, op->op);
+
+ switch (op->op) {
+ case POLICY_PROMOTE:
+ clear_discard(cache, oblock_to_dblock(cache, op->oblock));
+ policy_complete_background_work(cache->policy, op, success);
+
+ if (mg->overwrite_bio) {
+ if (success)
+ force_set_dirty(cache, cblock);
+ else if (mg->k.input)
+ mg->overwrite_bio->bi_status = mg->k.input;
+ else
+ mg->overwrite_bio->bi_status = BLK_STS_IOERR;
+ bio_endio(mg->overwrite_bio);
+ } else {
+ if (success)
+ force_clear_dirty(cache, cblock);
+ dec_io_migrations(cache);
+ }
+ break;
+
+ case POLICY_DEMOTE:
+ /*
+ * We clear dirty here to update the nr_dirty counter.
+ */
+ if (success)
+ force_clear_dirty(cache, cblock);
+ policy_complete_background_work(cache->policy, op, success);
+ dec_io_migrations(cache);
+ break;
+
+ case POLICY_WRITEBACK:
+ if (success)
+ force_clear_dirty(cache, cblock);
+ policy_complete_background_work(cache->policy, op, success);
+ dec_io_migrations(cache);
+ break;
+ }
+
+ bio_list_init(&bios);
+ if (mg->cell) {
+ if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
+ free_prison_cell(cache, mg->cell);
+ }
+
+ free_migration(mg);
+ defer_bios(cache, &bios);
+ wake_migration_worker(cache);
+
+ background_work_end(cache);
+}
+
+static void mg_success(struct work_struct *ws)
+{
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+ mg_complete(mg, mg->k.input == 0);
+}
+
+static void mg_update_metadata(struct work_struct *ws)
+{
+ int r;
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+ struct cache *cache = mg->cache;
+ struct policy_work *op = mg->op;
+
+ switch (op->op) {
+ case POLICY_PROMOTE:
+ r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
+ if (r) {
+ DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
+ cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
+
+ mg_complete(mg, false);
+ return;
+ }
+ mg_complete(mg, true);
+ break;
+
+ case POLICY_DEMOTE:
+ r = dm_cache_remove_mapping(cache->cmd, op->cblock);
+ if (r) {
+ DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
+ cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
+
+ mg_complete(mg, false);
+ return;
+ }
+
+ /*
+ * It would be nice if we only had to commit when a REQ_FLUSH
+ * comes through. But there's one scenario that we have to
+ * look out for:
+ *
+ * - vblock x in a cache block
+ * - domotion occurs
+ * - cache block gets reallocated and over written
+ * - crash
+ *
+ * When we recover, because there was no commit the cache will
+ * rollback to having the data for vblock x in the cache block.
+ * But the cache block has since been overwritten, so it'll end
+ * up pointing to data that was never in 'x' during the history
+ * of the device.
+ *
+ * To avoid this issue we require a commit as part of the
+ * demotion operation.
+ */
+ init_continuation(&mg->k, mg_success);
+ continue_after_commit(&cache->committer, &mg->k);
+ schedule_commit(&cache->committer);
+ break;
+
+ case POLICY_WRITEBACK:
+ mg_complete(mg, true);
+ break;
+ }
+}
+
+static void mg_update_metadata_after_copy(struct work_struct *ws)
+{
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+
+ /*
+ * Did the copy succeed?
+ */
+ if (mg->k.input)
+ mg_complete(mg, false);
+ else
+ mg_update_metadata(ws);
+}
+
+static void mg_upgrade_lock(struct work_struct *ws)
+{
+ int r;
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+
+ /*
+ * Did the copy succeed?
+ */
+ if (mg->k.input)
+ mg_complete(mg, false);
+
+ else {
+ /*
+ * Now we want the lock to prevent both reads and writes.
+ */
+ r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
+ READ_WRITE_LOCK_LEVEL);
+ if (r < 0)
+ mg_complete(mg, false);
+
+ else if (r)
+ quiesce(mg, mg_update_metadata);
+
+ else
+ mg_update_metadata(ws);
+ }
+}
+
+static void mg_full_copy(struct work_struct *ws)
+{
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+ struct cache *cache = mg->cache;
+ struct policy_work *op = mg->op;
+ bool is_policy_promote = (op->op == POLICY_PROMOTE);
+
+ if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
+ is_discarded_oblock(cache, op->oblock)) {
+ mg_upgrade_lock(ws);
+ return;
+ }
+
+ init_continuation(&mg->k, mg_upgrade_lock);
+ copy(mg, is_policy_promote);
+}
+
+static void mg_copy(struct work_struct *ws)
+{
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+
+ if (mg->overwrite_bio) {
+ /*
+ * No exclusive lock was held when we last checked if the bio
+ * was optimisable. So we have to check again in case things
+ * have changed (eg, the block may no longer be discarded).
+ */
+ if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
+ /*
+ * Fallback to a real full copy after doing some tidying up.
+ */
+ bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
+ BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
+ mg->overwrite_bio = NULL;
+ inc_io_migrations(mg->cache);
+ mg_full_copy(ws);
+ return;
+ }
+
+ /*
+ * It's safe to do this here, even though it's new data
+ * because all IO has been locked out of the block.
+ *
+ * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
+ * so _not_ using mg_upgrade_lock() as continutation.
+ */
+ overwrite(mg, mg_update_metadata_after_copy);
+
+ } else
+ mg_full_copy(ws);
+}
+
+static int mg_lock_writes(struct dm_cache_migration *mg)
+{
+ int r;
+ struct dm_cell_key_v2 key;
+ struct cache *cache = mg->cache;
+ struct dm_bio_prison_cell_v2 *prealloc;
+
+ prealloc = alloc_prison_cell(cache);
+ if (!prealloc) {
+ DMERR_LIMIT("%s: alloc_prison_cell failed", cache_device_name(cache));
+ mg_complete(mg, false);
+ return -ENOMEM;
+ }
+
+ /*
+ * Prevent writes to the block, but allow reads to continue.
+ * Unless we're using an overwrite bio, in which case we lock
+ * everything.
+ */
+ build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
+ r = dm_cell_lock_v2(cache->prison, &key,
+ mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
+ prealloc, &mg->cell);
+ if (r < 0) {
+ free_prison_cell(cache, prealloc);
+ mg_complete(mg, false);
+ return r;
+ }
+
+ if (mg->cell != prealloc)
+ free_prison_cell(cache, prealloc);
+
+ if (r == 0)
+ mg_copy(&mg->k.ws);
+ else
+ quiesce(mg, mg_copy);
+
+ return 0;
+}
+
+static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
+{
+ struct dm_cache_migration *mg;
+
+ if (!background_work_begin(cache)) {
+ policy_complete_background_work(cache->policy, op, false);
+ return -EPERM;
+ }
+
+ mg = alloc_migration(cache);
+ if (!mg) {
+ policy_complete_background_work(cache->policy, op, false);
+ background_work_end(cache);
+ return -ENOMEM;
+ }
+
+ mg->op = op;
+ mg->overwrite_bio = bio;
+
+ if (!bio)
+ inc_io_migrations(cache);
+
+ return mg_lock_writes(mg);
+}
+
+/*----------------------------------------------------------------
+ * invalidation processing
+ *--------------------------------------------------------------*/
+
+static void invalidate_complete(struct dm_cache_migration *mg, bool success)
+{
+ struct bio_list bios;
+ struct cache *cache = mg->cache;
+
+ bio_list_init(&bios);
+ if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
+ free_prison_cell(cache, mg->cell);
+
+ if (!success && mg->overwrite_bio)
+ bio_io_error(mg->overwrite_bio);
+
+ free_migration(mg);
+ defer_bios(cache, &bios);
+
+ background_work_end(cache);
+}
+
+static void invalidate_completed(struct work_struct *ws)
+{
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+ invalidate_complete(mg, !mg->k.input);
+}
+
+static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
+{
+ int r = policy_invalidate_mapping(cache->policy, cblock);
+ if (!r) {
+ r = dm_cache_remove_mapping(cache->cmd, cblock);
+ if (r) {
+ DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
+ cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
+ }
+
+ } else if (r == -ENODATA) {
+ /*
+ * Harmless, already unmapped.
+ */
+ r = 0;
+
+ } else
+ DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
+
+ return r;
+}
+
+static void invalidate_remove(struct work_struct *ws)
+{
+ int r;
+ struct dm_cache_migration *mg = ws_to_mg(ws);
+ struct cache *cache = mg->cache;
+
+ r = invalidate_cblock(cache, mg->invalidate_cblock);
+ if (r) {
+ invalidate_complete(mg, false);
+ return;
+ }
+
+ init_continuation(&mg->k, invalidate_completed);
+ continue_after_commit(&cache->committer, &mg->k);
+ remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
+ mg->overwrite_bio = NULL;
+ schedule_commit(&cache->committer);
+}
+
+static int invalidate_lock(struct dm_cache_migration *mg)
+{
+ int r;
+ struct dm_cell_key_v2 key;
+ struct cache *cache = mg->cache;
+ struct dm_bio_prison_cell_v2 *prealloc;
+
+ prealloc = alloc_prison_cell(cache);
+ if (!prealloc) {
+ invalidate_complete(mg, false);
+ return -ENOMEM;
+ }
+
+ build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
+ r = dm_cell_lock_v2(cache->prison, &key,
+ READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
+ if (r < 0) {
+ free_prison_cell(cache, prealloc);
+ invalidate_complete(mg, false);
+ return r;
+ }
+
+ if (mg->cell != prealloc)
+ free_prison_cell(cache, prealloc);
+
+ if (r)
+ quiesce(mg, invalidate_remove);
+
+ else {
+ /*
+ * We can't call invalidate_remove() directly here because we
+ * might still be in request context.
+ */
+ init_continuation(&mg->k, invalidate_remove);
+ queue_work(cache->wq, &mg->k.ws);
+ }
+
+ return 0;
+}
+
+static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
+ dm_oblock_t oblock, struct bio *bio)
+{
+ struct dm_cache_migration *mg;
+
+ if (!background_work_begin(cache))
+ return -EPERM;
+
+ mg = alloc_migration(cache);
+ if (!mg) {
+ background_work_end(cache);
+ return -ENOMEM;
+ }
+
+ mg->overwrite_bio = bio;
+ mg->invalidate_cblock = cblock;
+ mg->invalidate_oblock = oblock;
+
+ return invalidate_lock(mg);
+}
+
+/*----------------------------------------------------------------
+ * bio processing
+ *--------------------------------------------------------------*/
+
+enum busy {
+ IDLE,
+ BUSY
+};
+
+static enum busy spare_migration_bandwidth(struct cache *cache)
+{
+ bool idle = iot_idle_for(&cache->tracker, HZ);
+ sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
+ cache->sectors_per_block;
+
+ if (idle && current_volume <= cache->migration_threshold)
+ return IDLE;
+ else
+ return BUSY;
+}
+
+static void inc_hit_counter(struct cache *cache, struct bio *bio)
+{
+ atomic_inc(bio_data_dir(bio) == READ ?
+ &cache->stats.read_hit : &cache->stats.write_hit);
+}
+
+static void inc_miss_counter(struct cache *cache, struct bio *bio)
+{
+ atomic_inc(bio_data_dir(bio) == READ ?
+ &cache->stats.read_miss : &cache->stats.write_miss);
+}
+
+/*----------------------------------------------------------------*/
+
+static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
+ bool *commit_needed)
+{
+ int r, data_dir;
+ bool rb, background_queued;
+ dm_cblock_t cblock;
+
+ *commit_needed = false;
+
+ rb = bio_detain_shared(cache, block, bio);
+ if (!rb) {
+ /*
+ * An exclusive lock is held for this block, so we have to
+ * wait. We set the commit_needed flag so the current
+ * transaction will be committed asap, allowing this lock
+ * to be dropped.
+ */
+ *commit_needed = true;
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ data_dir = bio_data_dir(bio);
+
+ if (optimisable_bio(cache, bio, block)) {
+ struct policy_work *op = NULL;
+
+ r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
+ if (unlikely(r && r != -ENOENT)) {
+ DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
+ cache_device_name(cache), r);
+ bio_io_error(bio);
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ if (r == -ENOENT && op) {
+ bio_drop_shared_lock(cache, bio);
+ BUG_ON(op->op != POLICY_PROMOTE);
+ mg_start(cache, op, bio);
+ return DM_MAPIO_SUBMITTED;
+ }
+ } else {
+ r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
+ if (unlikely(r && r != -ENOENT)) {
+ DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
+ cache_device_name(cache), r);
+ bio_io_error(bio);
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ if (background_queued)
+ wake_migration_worker(cache);
+ }
+
+ if (r == -ENOENT) {
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ /*
+ * Miss.
+ */
+ inc_miss_counter(cache, bio);
+ if (pb->req_nr == 0) {
+ accounted_begin(cache, bio);
+ remap_to_origin_clear_discard(cache, bio, block);
+ } else {
+ /*
+ * This is a duplicate writethrough io that is no
+ * longer needed because the block has been demoted.
+ */
+ bio_endio(bio);
+ return DM_MAPIO_SUBMITTED;
+ }
+ } else {
+ /*
+ * Hit.
+ */
+ inc_hit_counter(cache, bio);
+
+ /*
+ * Passthrough always maps to the origin, invalidating any
+ * cache blocks that are written to.
+ */
+ if (passthrough_mode(cache)) {
+ if (bio_data_dir(bio) == WRITE) {
+ bio_drop_shared_lock(cache, bio);
+ atomic_inc(&cache->stats.demotion);
+ invalidate_start(cache, cblock, block, bio);
+ } else
+ remap_to_origin_clear_discard(cache, bio, block);
+ } else {
+ if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
+ !is_dirty(cache, cblock)) {
+ remap_to_origin_and_cache(cache, bio, block, cblock);
+ accounted_begin(cache, bio);
+ } else
+ remap_to_cache_dirty(cache, bio, block, cblock);
+ }
+ }
+
+ /*
+ * dm core turns FUA requests into a separate payload and FLUSH req.
+ */
+ if (bio->bi_opf & REQ_FUA) {
+ /*
+ * issue_after_commit will call accounted_begin a second time. So
+ * we call accounted_complete() to avoid double accounting.
+ */
+ accounted_complete(cache, bio);
+ issue_after_commit(&cache->committer, bio);
+ *commit_needed = true;
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ return DM_MAPIO_REMAPPED;
+}
+
+static bool process_bio(struct cache *cache, struct bio *bio)
+{
+ bool commit_needed;
+
+ if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
+ generic_make_request(bio);
+
+ return commit_needed;
+}
+
+/*
+ * A non-zero return indicates read_only or fail_io mode.
+ */
+static int commit(struct cache *cache, bool clean_shutdown)
+{
+ int r;
+
+ if (get_cache_mode(cache) >= CM_READ_ONLY)
+ return -EINVAL;
+
+ atomic_inc(&cache->stats.commit_count);
+ r = dm_cache_commit(cache->cmd, clean_shutdown);
+ if (r)
+ metadata_operation_failed(cache, "dm_cache_commit", r);
+
+ return r;
+}
+
+/*
+ * Used by the batcher.
+ */
+static blk_status_t commit_op(void *context)
+{
+ struct cache *cache = context;
+
+ if (dm_cache_changed_this_transaction(cache->cmd))
+ return errno_to_blk_status(commit(cache, false));
+
+ return 0;
+}
+
+/*----------------------------------------------------------------*/
+
+static bool process_flush_bio(struct cache *cache, struct bio *bio)
+{
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ if (!pb->req_nr)
+ remap_to_origin(cache, bio);
+ else
+ remap_to_cache(cache, bio, 0);
+
+ issue_after_commit(&cache->committer, bio);
+ return true;
+}
+
+static bool process_discard_bio(struct cache *cache, struct bio *bio)
+{
+ dm_dblock_t b, e;
+
+ // FIXME: do we need to lock the region? Or can we just assume the
+ // user wont be so foolish as to issue discard concurrently with
+ // other IO?
+ calc_discard_block_range(cache, bio, &b, &e);
+ while (b != e) {
+ set_discard(cache, b);
+ b = to_dblock(from_dblock(b) + 1);
+ }
+
+ bio_endio(bio);
+
+ return false;
+}
+
+static void process_deferred_bios(struct work_struct *ws)
+{
+ struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
+
+ unsigned long flags;
+ bool commit_needed = false;
+ struct bio_list bios;
+ struct bio *bio;
+
+ 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 = bio_list_pop(&bios))) {
+ if (bio->bi_opf & REQ_PREFLUSH)
+ commit_needed = process_flush_bio(cache, bio) || commit_needed;
+
+ else if (bio_op(bio) == REQ_OP_DISCARD)
+ commit_needed = process_discard_bio(cache, bio) || commit_needed;
+
+ else
+ commit_needed = process_bio(cache, bio) || commit_needed;
+ }
+
+ if (commit_needed)
+ schedule_commit(&cache->committer);
+}
+
+/*----------------------------------------------------------------
+ * Main worker loop
+ *--------------------------------------------------------------*/
+
+static void requeue_deferred_bios(struct cache *cache)
+{
+ struct bio *bio;
+ struct bio_list bios;
+
+ bio_list_init(&bios);
+ bio_list_merge(&bios, &cache->deferred_bios);
+ bio_list_init(&cache->deferred_bios);
+
+ while ((bio = bio_list_pop(&bios))) {
+ bio->bi_status = BLK_STS_DM_REQUEUE;
+ bio_endio(bio);
+ }
+}
+
+/*
+ * We want to commit periodically so that not too much
+ * unwritten metadata builds up.
+ */
+static void do_waker(struct work_struct *ws)
+{
+ struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
+
+ policy_tick(cache->policy, true);
+ wake_migration_worker(cache);
+ schedule_commit(&cache->committer);
+ queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
+}
+
+static void check_migrations(struct work_struct *ws)
+{
+ int r;
+ struct policy_work *op;
+ struct cache *cache = container_of(ws, struct cache, migration_worker);
+ enum busy b;
+
+ for (;;) {
+ b = spare_migration_bandwidth(cache);
+
+ r = policy_get_background_work(cache->policy, b == IDLE, &op);
+ if (r == -ENODATA)
+ break;
+
+ if (r) {
+ DMERR_LIMIT("%s: policy_background_work failed",
+ cache_device_name(cache));
+ break;
+ }
+
+ r = mg_start(cache, op, NULL);
+ if (r)
+ break;
+ }
+}
+
+/*----------------------------------------------------------------
+ * 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_exit(&cache->migration_pool);
+
+ if (cache->prison)
+ dm_bio_prison_destroy_v2(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);
+
+ bioset_exit(&cache->bs);
+
+ kfree(cache);
+}
+
+static void cache_dtr(struct dm_target *ti)
+{
+ struct cache *cache = ti->private;
+
+ destroy(cache);
+}
+
+static sector_t get_dev_size(struct dm_dev *dev)
+{
+ return 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;
+ cf->metadata_version = 1;
+}
+
+static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
+ char **error)
+{
+ static const struct dm_arg _args[] = {
+ {0, 2, "Invalid number of cache feature arguments"},
+ };
+
+ int r, mode_ctr = 0;
+ 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;
+ mode_ctr++;
+ }
+
+ else if (!strcasecmp(arg, "writethrough")) {
+ cf->io_mode = CM_IO_WRITETHROUGH;
+ mode_ctr++;
+ }
+
+ else if (!strcasecmp(arg, "passthrough")) {
+ cf->io_mode = CM_IO_PASSTHROUGH;
+ mode_ctr++;
+ }
+
+ else if (!strcasecmp(arg, "metadata2"))
+ cf->metadata_version = 2;
+
+ else {
+ *error = "Unrecognised cache feature requested";
+ return -EINVAL;
+ }
+ }
+
+ if (mode_ctr > 1) {
+ *error = "Duplicate cache io_mode features requested";
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
+ char **error)
+{
+ static const struct dm_arg _args[] = {
+ {0, 1024, "Invalid number of policy arguments"},
+ };
+
+ int r;
+
+ if (!at_least_one_arg(as, error))
+ return -EINVAL;
+
+ ca->policy_name = dm_shift_arg(as);
+
+ r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
+ if (r)
+ return -EINVAL;
+
+ ca->policy_argv = (const char **)as->argv;
+ dm_consume_args(as, ca->policy_argc);
+
+ return 0;
+}
+
+static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
+ char **error)
+{
+ int r;
+ struct dm_arg_set as;
+
+ as.argc = argc;
+ as.argv = argv;
+
+ r = parse_metadata_dev(ca, &as, error);
+ if (r)
+ return r;
+
+ r = parse_cache_dev(ca, &as, error);
+ if (r)
+ return r;
+
+ r = parse_origin_dev(ca, &as, error);
+ if (r)
+ return r;
+
+ r = parse_block_size(ca, &as, error);
+ if (r)
+ return r;
+
+ r = parse_features(ca, &as, error);
+ if (r)
+ return r;
+
+ r = parse_policy(ca, &as, error);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+/*----------------------------------------------------------------*/
+
+static struct kmem_cache *migration_cache;
+
+#define NOT_CORE_OPTION 1
+
+static int process_config_option(struct cache *cache, const char *key, const char *value)
+{
+ unsigned long tmp;
+
+ if (!strcasecmp(key, "migration_threshold")) {
+ if (kstrtoul(value, 10, &tmp))
+ return -EINVAL;
+
+ cache->migration_threshold = tmp;
+ return 0;
+ }
+
+ return NOT_CORE_OPTION;
+}
+
+static int set_config_value(struct cache *cache, const char *key, const char *value)
+{
+ int r = process_config_option(cache, key, value);
+
+ if (r == NOT_CORE_OPTION)
+ r = policy_set_config_value(cache->policy, key, value);
+
+ if (r)
+ DMWARN("bad config value for %s: %s", key, value);
+
+ return r;
+}
+
+static int set_config_values(struct cache *cache, int argc, const char **argv)
+{
+ int r = 0;
+
+ if (argc & 1) {
+ DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
+ return -EINVAL;
+ }
+
+ while (argc) {
+ r = set_config_value(cache, argv[0], argv[1]);
+ if (r)
+ break;
+
+ argc -= 2;
+ argv += 2;
+ }
+
+ return r;
+}
+
+static int create_cache_policy(struct cache *cache, struct cache_args *ca,
+ char **error)
+{
+ struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
+ cache->cache_size,
+ cache->origin_sectors,
+ cache->sectors_per_block);
+ if (IS_ERR(p)) {
+ *error = "Error creating cache's policy";
+ return PTR_ERR(p);
+ }
+ cache->policy = p;
+ BUG_ON(!cache->policy);
+
+ return 0;
+}
+
+/*
+ * We want the discard block size to be at least the size of the cache
+ * block size and have no more than 2^14 discard blocks across the origin.
+ */
+#define MAX_DISCARD_BLOCKS (1 << 14)
+
+static bool too_many_discard_blocks(sector_t discard_block_size,
+ sector_t origin_size)
+{
+ (void) sector_div(origin_size, discard_block_size);
+
+ return origin_size > MAX_DISCARD_BLOCKS;
+}
+
+static sector_t calculate_discard_block_size(sector_t cache_block_size,
+ sector_t origin_size)
+{
+ sector_t discard_block_size = cache_block_size;
+
+ if (origin_size)
+ while (too_many_discard_blocks(discard_block_size, origin_size))
+ discard_block_size *= 2;
+
+ return discard_block_size;
+}
+
+static void set_cache_size(struct cache *cache, dm_cblock_t size)
+{
+ dm_block_t nr_blocks = from_cblock(size);
+
+ if (nr_blocks > (1 << 20) && cache->cache_size != size)
+ DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
+ "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
+ "Please consider increasing the cache block size to reduce the overall cache block count.",
+ (unsigned long long) nr_blocks);
+
+ cache->cache_size = size;
+}
+
+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);
+}
+
+#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->split_discard_bios = false;
+
+ ti->per_io_data_size = sizeof(struct per_bio_data);
+
+ cache->features = ca->features;
+ if (writethrough_mode(cache)) {
+ /* Create bioset for writethrough bios issued to origin */
+ r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
+ if (r)
+ goto bad;
+ }
+
+ cache->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;
+
+ origin_blocks = cache->origin_sectors = ca->origin_sectors;
+ origin_blocks = block_div(origin_blocks, ca->block_size);
+ cache->origin_blocks = to_oblock(origin_blocks);
+
+ cache->sectors_per_block = ca->block_size;
+ if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
+ r = -EINVAL;
+ goto bad;
+ }
+
+ if (ca->block_size & (ca->block_size - 1)) {
+ dm_block_t cache_size = ca->cache_sectors;
+
+ cache->sectors_per_block_shift = -1;
+ cache_size = block_div(cache_size, ca->block_size);
+ set_cache_size(cache, to_cblock(cache_size));
+ } else {
+ cache->sectors_per_block_shift = __ffs(ca->block_size);
+ set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
+ }
+
+ r = create_cache_policy(cache, ca, error);
+ if (r)
+ goto bad;
+
+ cache->policy_nr_args = ca->policy_argc;
+ cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
+
+ r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
+ if (r) {
+ *error = "Error setting cache policy's config values";
+ goto bad;
+ }
+
+ cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
+ ca->block_size, may_format,
+ dm_cache_policy_get_hint_size(cache->policy),
+ ca->features.metadata_version);
+ if (IS_ERR(cmd)) {
+ *error = "Error creating metadata object";
+ r = PTR_ERR(cmd);
+ goto bad;
+ }
+ cache->cmd = cmd;
+ set_cache_mode(cache, CM_WRITE);
+ if (get_cache_mode(cache) != CM_WRITE) {
+ *error = "Unable to get write access to metadata, please check/repair metadata.";
+ r = -EINVAL;
+ goto bad;
+ }
+
+ if (passthrough_mode(cache)) {
+ bool all_clean;
+
+ r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
+ if (r) {
+ *error = "dm_cache_metadata_all_clean() failed";
+ goto bad;
+ }
+
+ if (!all_clean) {
+ *error = "Cannot enter passthrough mode unless all blocks are clean";
+ r = -EINVAL;
+ goto bad;
+ }
+
+ policy_allow_migrations(cache->policy, false);
+ }
+
+ spin_lock_init(&cache->lock);
+ bio_list_init(&cache->deferred_bios);
+ atomic_set(&cache->nr_allocated_migrations, 0);
+ atomic_set(&cache->nr_io_migrations, 0);
+ init_waitqueue_head(&cache->migration_wait);
+
+ r = -ENOMEM;
+ atomic_set(&cache->nr_dirty, 0);
+ cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
+ if (!cache->dirty_bitset) {
+ *error = "could not allocate dirty bitset";
+ goto bad;
+ }
+ clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
+
+ cache->discard_block_size =
+ calculate_discard_block_size(cache->sectors_per_block,
+ cache->origin_sectors);
+ cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
+ cache->discard_block_size));
+ cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
+ if (!cache->discard_bitset) {
+ *error = "could not allocate discard bitset";
+ goto bad;
+ }
+ clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
+
+ cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
+ if (IS_ERR(cache->copier)) {
+ *error = "could not create kcopyd client";
+ r = PTR_ERR(cache->copier);
+ goto bad;
+ }
+
+ cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
+ if (!cache->wq) {
+ *error = "could not create workqueue for metadata object";
+ goto bad;
+ }
+ INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
+ INIT_WORK(&cache->migration_worker, check_migrations);
+ INIT_DELAYED_WORK(&cache->waker, do_waker);
+
+ cache->prison = dm_bio_prison_create_v2(cache->wq);
+ if (!cache->prison) {
+ *error = "could not create bio prison";
+ goto bad;
+ }
+
+ r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
+ migration_cache);
+ if (r) {
+ *error = "Error creating cache's migration mempool";
+ goto bad;
+ }
+
+ cache->need_tick_bio = true;
+ cache->sized = false;
+ cache->invalidate = false;
+ cache->commit_requested = false;
+ cache->loaded_mappings = false;
+ cache->loaded_discards = false;
+
+ load_stats(cache);
+
+ atomic_set(&cache->stats.demotion, 0);
+ atomic_set(&cache->stats.promotion, 0);
+ atomic_set(&cache->stats.copies_avoided, 0);
+ atomic_set(&cache->stats.cache_cell_clash, 0);
+ atomic_set(&cache->stats.commit_count, 0);
+ atomic_set(&cache->stats.discard_count, 0);
+
+ spin_lock_init(&cache->invalidation_lock);
+ INIT_LIST_HEAD(&cache->invalidation_requests);
+
+ batcher_init(&cache->committer, commit_op, cache,
+ issue_op, cache, cache->wq);
+ iot_init(&cache->tracker);
+
+ init_rwsem(&cache->background_work_lock);
+ prevent_background_work(cache);
+
+ *result = cache;
+ return 0;
+bad:
+ destroy(cache);
+ return r;
+}
+
+static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
+{
+ unsigned 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;
+ bool commit_needed;
+ dm_oblock_t block = get_bio_block(cache, bio);
+
+ init_per_bio_data(bio);
+ if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
+ /*
+ * This can only occur if the io goes to a partial block at
+ * the end of the origin device. We don't cache these.
+ * Just remap to the origin and carry on.
+ */
+ remap_to_origin(cache, bio);
+ accounted_begin(cache, bio);
+ return DM_MAPIO_REMAPPED;
+ }
+
+ if (discard_or_flush(bio)) {
+ defer_bio(cache, bio);
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ r = map_bio(cache, bio, block, &commit_needed);
+ if (commit_needed)
+ schedule_commit(&cache->committer);
+
+ return r;
+}
+
+static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
+{
+ struct cache *cache = ti->private;
+ unsigned long flags;
+ struct per_bio_data *pb = get_per_bio_data(bio);
+
+ if (pb->tick) {
+ policy_tick(cache->policy, false);
+
+ spin_lock_irqsave(&cache->lock, flags);
+ cache->need_tick_bio = true;
+ spin_unlock_irqrestore(&cache->lock, flags);
+ }
+
+ bio_drop_shared_lock(cache, bio);
+ accounted_complete(cache, bio);
+
+ return DM_ENDIO_DONE;
+}
+
+static int write_dirty_bitset(struct cache *cache)
+{
+ int r;
+
+ if (get_cache_mode(cache) >= CM_READ_ONLY)
+ return -EINVAL;
+
+ r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
+ if (r)
+ metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
+
+ return r;
+}
+
+static int write_discard_bitset(struct cache *cache)
+{
+ unsigned i, r;
+
+ if (get_cache_mode(cache) >= CM_READ_ONLY)
+ return -EINVAL;
+
+ r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
+ cache->discard_nr_blocks);
+ if (r) {
+ DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
+ return r;
+ }
+
+ for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
+ r = dm_cache_set_discard(cache->cmd, to_dblock(i),
+ is_discarded(cache, to_dblock(i)));
+ if (r) {
+ metadata_operation_failed(cache, "dm_cache_set_discard", r);
+ return r;
+ }
+ }
+
+ return 0;
+}
+
+static int write_hints(struct cache *cache)
+{
+ int r;
+
+ if (get_cache_mode(cache) >= CM_READ_ONLY)
+ return -EINVAL;
+
+ r = dm_cache_write_hints(cache->cmd, cache->policy);
+ if (r) {
+ metadata_operation_failed(cache, "dm_cache_write_hints", r);
+ return r;
+ }
+
+ return 0;
+}
+
+/*
+ * returns true on success
+ */
+static bool sync_metadata(struct cache *cache)
+{
+ int r1, r2, r3, r4;
+
+ r1 = write_dirty_bitset(cache);
+ if (r1)
+ DMERR("%s: could not write dirty bitset", cache_device_name(cache));
+
+ r2 = write_discard_bitset(cache);
+ if (r2)
+ DMERR("%s: could not write discard bitset", cache_device_name(cache));
+
+ save_stats(cache);
+
+ r3 = write_hints(cache);
+ if (r3)
+ DMERR("%s: could not write hints", cache_device_name(cache));
+
+ /*
+ * If writing the above metadata failed, we still commit, but don't
+ * set the clean shutdown flag. This will effectively force every
+ * dirty bit to be set on reload.
+ */
+ r4 = commit(cache, !r1 && !r2 && !r3);
+ if (r4)
+ DMERR("%s: could not write cache metadata", cache_device_name(cache));
+
+ return !r1 && !r2 && !r3 && !r4;
+}
+
+static void cache_postsuspend(struct dm_target *ti)
+{
+ struct cache *cache = ti->private;
+
+ prevent_background_work(cache);
+ BUG_ON(atomic_read(&cache->nr_io_migrations));
+
+ cancel_delayed_work(&cache->waker);
+ flush_workqueue(cache->wq);
+ WARN_ON(cache->tracker.in_flight);
+
+ /*
+ * If it's a flush suspend there won't be any deferred bios, so this
+ * call is harmless.
+ */
+ requeue_deferred_bios(cache);
+
+ if (get_cache_mode(cache) == CM_WRITE)
+ (void) sync_metadata(cache);
+}
+
+static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
+ bool dirty, uint32_t hint, bool hint_valid)
+{
+ int r;
+ struct cache *cache = context;
+
+ if (dirty) {
+ set_bit(from_cblock(cblock), cache->dirty_bitset);
+ atomic_inc(&cache->nr_dirty);
+ } else
+ clear_bit(from_cblock(cblock), cache->dirty_bitset);
+
+ r = policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
+ if (r)
+ return r;
+
+ 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)) {
+ if (cache->sized) {
+ DMERR("%s: unable to extend cache due to missing cache table reload",
+ cache_device_name(cache));
+ return false;
+ }
+ }
+
+ /*
+ * We can't drop a dirty block when shrinking the cache.
+ */
+ while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
+ new_size = to_cblock(from_cblock(new_size) + 1);
+ if (is_dirty(cache, new_size)) {
+ DMERR("%s: unable to shrink cache; cache block %llu is dirty",
+ cache_device_name(cache),
+ (unsigned long long) from_cblock(new_size));
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
+{
+ int r;
+
+ r = dm_cache_resize(cache->cmd, new_size);
+ if (r) {
+ DMERR("%s: could not resize cache metadata", cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_resize", r);
+ return r;
+ }
+
+ set_cache_size(cache, new_size);
+
+ return 0;
+}
+
+static int cache_preresume(struct dm_target *ti)
+{
+ int r = 0;
+ struct cache *cache = ti->private;
+ dm_cblock_t csize = get_cache_dev_size(cache);
+
+ /*
+ * Check to see if the cache has resized.
+ */
+ if (!cache->sized) {
+ r = resize_cache_dev(cache, csize);
+ if (r)
+ return r;
+
+ cache->sized = true;
+
+ } else if (csize != cache->cache_size) {
+ if (!can_resize(cache, csize))
+ return -EINVAL;
+
+ r = resize_cache_dev(cache, csize);
+ if (r)
+ return r;
+ }
+
+ if (!cache->loaded_mappings) {
+ r = dm_cache_load_mappings(cache->cmd, cache->policy,
+ load_mapping, cache);
+ if (r) {
+ DMERR("%s: could not load cache mappings", cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_load_mappings", r);
+ return r;
+ }
+
+ cache->loaded_mappings = true;
+ }
+
+ if (!cache->loaded_discards) {
+ struct discard_load_info li;
+
+ /*
+ * The discard bitset could have been resized, or the
+ * discard block size changed. To be safe we start by
+ * setting every dblock to not discarded.
+ */
+ clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
+
+ discard_load_info_init(cache, &li);
+ r = dm_cache_load_discards(cache->cmd, load_discard, &li);
+ if (r) {
+ DMERR("%s: could not load origin discards", cache_device_name(cache));
+ metadata_operation_failed(cache, "dm_cache_load_discards", r);
+ return r;
+ }
+ set_discard_range(&li);
+
+ cache->loaded_discards = true;
+ }
+
+ return r;
+}
+
+static void cache_resume(struct dm_target *ti)
+{
+ struct cache *cache = ti->private;
+
+ cache->need_tick_bio = true;
+ allow_background_work(cache);
+ do_waker(&cache->waker.work);
+}
+
+/*
+ * Status format:
+ *
+ * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
+ * <cache block size> <#used cache blocks>/<#total cache blocks>
+ * <#read hits> <#read misses> <#write hits> <#write misses>
+ * <#demotions> <#promotions> <#dirty>
+ * <#features> <features>*
+ * <#core args> <core args>
+ * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
+ */
+static void cache_status(struct dm_target *ti, status_type_t type,
+ unsigned 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 (cache->features.metadata_version == 2)
+ DMEMIT("2 metadata2 ");
+ else
+ DMEMIT("1 ");
+
+ if (writethrough_mode(cache))
+ DMEMIT("writethrough ");
+
+ else if (passthrough_mode(cache))
+ DMEMIT("passthrough ");
+
+ else if (writeback_mode(cache))
+ DMEMIT("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");
+}
+
+/*
+ * Defines a range of cblocks, begin to (end - 1) are in the range. end is
+ * the one-past-the-end value.
+ */
+struct cblock_range {
+ dm_cblock_t begin;
+ dm_cblock_t end;
+};
+
+/*
+ * A cache block range can take two forms:
+ *
+ * i) A single cblock, eg. '3456'
+ * ii) A begin and end cblock with a dash between, eg. 123-234
+ */
+static int parse_cblock_range(struct cache *cache, const char *str,
+ struct cblock_range *result)
+{
+ char dummy;
+ uint64_t b, e;
+ int r;
+
+ /*
+ * Try and parse form (ii) first.
+ */
+ r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
+ if (r < 0)
+ return r;
+
+ if (r == 2) {
+ result->begin = to_cblock(b);
+ result->end = to_cblock(e);
+ return 0;
+ }
+
+ /*
+ * That didn't work, try form (i).
+ */
+ r = sscanf(str, "%llu%c", &b, &dummy);
+ if (r < 0)
+ return r;
+
+ if (r == 1) {
+ result->begin = to_cblock(b);
+ result->end = to_cblock(from_cblock(result->begin) + 1u);
+ return 0;
+ }
+
+ DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
+ return -EINVAL;
+}
+
+static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
+{
+ uint64_t b = from_cblock(range->begin);
+ uint64_t e = from_cblock(range->end);
+ uint64_t n = from_cblock(cache->cache_size);
+
+ if (b >= n) {
+ DMERR("%s: begin cblock out of range: %llu >= %llu",
+ cache_device_name(cache), b, n);
+ return -EINVAL;
+ }
+
+ if (e > n) {
+ DMERR("%s: end cblock out of range: %llu > %llu",
+ cache_device_name(cache), e, n);
+ return -EINVAL;
+ }
+
+ if (b >= e) {
+ DMERR("%s: invalid cblock range: %llu >= %llu",
+ cache_device_name(cache), b, e);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static inline dm_cblock_t cblock_succ(dm_cblock_t b)
+{
+ return to_cblock(from_cblock(b) + 1);
+}
+
+static int request_invalidation(struct cache *cache, struct cblock_range *range)
+{
+ int r = 0;
+
+ /*
+ * We don't need to do any locking here because we know we're in
+ * passthrough mode. There's is potential for a race between an
+ * invalidation triggered by an io and an invalidation message. This
+ * is harmless, we must not worry if the policy call fails.
+ */
+ while (range->begin != range->end) {
+ r = invalidate_cblock(cache, range->begin);
+ if (r)
+ return r;
+
+ range->begin = cblock_succ(range->begin);
+ }
+
+ cache->commit_requested = true;
+ return r;
+}
+
+static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
+ const char **cblock_ranges)
+{
+ int r = 0;
+ unsigned i;
+ struct cblock_range range;
+
+ if (!passthrough_mode(cache)) {
+ DMERR("%s: cache has to be in passthrough mode for invalidation",
+ cache_device_name(cache));
+ return -EPERM;
+ }
+
+ for (i = 0; i < count; i++) {
+ r = parse_cblock_range(cache, cblock_ranges[i], &range);
+ if (r)
+ break;
+
+ r = validate_cblock_range(cache, &range);
+ if (r)
+ break;
+
+ /*
+ * Pass begin and end origin blocks to the worker and wake it.
+ */
+ r = request_invalidation(cache, &range);
+ if (r)
+ break;
+ }
+
+ return r;
+}
+
+/*
+ * Supports
+ * "<key> <value>"
+ * and
+ * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
+ *
+ * The key migration_threshold is supported by the cache target core.
+ */
+static int cache_message(struct dm_target *ti, unsigned argc, char **argv,
+ char *result, unsigned maxlen)
+{
+ struct cache *cache = ti->private;
+
+ if (!argc)
+ return -EINVAL;
+
+ if (get_cache_mode(cache) >= CM_READ_ONLY) {
+ DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
+ cache_device_name(cache));
+ return -EOPNOTSUPP;
+ }
+
+ if (!strcasecmp(argv[0], "invalidate_cblocks"))
+ return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
+
+ if (argc != 2)
+ return -EINVAL;
+
+ return set_config_value(cache, argv[0], argv[1]);
+}
+
+static int cache_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ int r = 0;
+ struct cache *cache = ti->private;
+
+ r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
+ if (!r)
+ r = fn(ti, cache->origin_dev, 0, ti->len, data);
+
+ return r;
+}
+
+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 = {2, 0, 0},
+ .module = THIS_MODULE,
+ .ctr = cache_ctr,
+ .dtr = cache_dtr,
+ .map = cache_map,
+ .end_io = cache_end_io,
+ .postsuspend = cache_postsuspend,
+ .preresume = cache_preresume,
+ .resume = cache_resume,
+ .status = cache_status,
+ .message = cache_message,
+ .iterate_devices = cache_iterate_devices,
+ .io_hints = cache_io_hints,
+};
+
+static int __init dm_cache_init(void)
+{
+ int r;
+
+ migration_cache = KMEM_CACHE(dm_cache_migration, 0);
+ if (!migration_cache)
+ return -ENOMEM;
+
+ r = dm_register_target(&cache_target);
+ if (r) {
+ DMERR("cache target registration failed: %d", r);
+ kmem_cache_destroy(migration_cache);
+ return r;
+ }
+
+ return 0;
+}
+
+static void __exit dm_cache_exit(void)
+{
+ dm_unregister_target(&cache_target);
+ kmem_cache_destroy(migration_cache);
+}
+
+module_init(dm_cache_init);
+module_exit(dm_cache_exit);
+
+MODULE_DESCRIPTION(DM_NAME " cache target");
+MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
+MODULE_LICENSE("GPL");