diff options
Diffstat (limited to 'drivers/md/dm-thin.c')
| -rw-r--r-- | drivers/md/dm-thin.c | 2428 |
1 files changed, 2428 insertions, 0 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c new file mode 100644 index 0000000..c308757 --- /dev/null +++ b/drivers/md/dm-thin.c @@ -0,0 +1,2428 @@ +/* + * Copyright (C) 2011 Red Hat UK. + * + * This file is released under the GPL. + */ + +#include "dm-thin-metadata.h" + +#include <linux/device-mapper.h> +#include <linux/dm-io.h> +#include <linux/dm-kcopyd.h> +#include <linux/list.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/slab.h> + +#define DM_MSG_PREFIX "thin" + +/* + * Tunable constants + */ +#define ENDIO_HOOK_POOL_SIZE 10240 +#define DEFERRED_SET_SIZE 64 +#define MAPPING_POOL_SIZE 1024 +#define PRISON_CELLS 1024 + +/* + * The block size of the device holding pool data must be + * between 64KB and 1GB. + */ +#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (64 * 1024 >> SECTOR_SHIFT) +#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT) + +/* + * The metadata device is currently limited in size. The limitation is + * checked lower down in dm-space-map-metadata, but we also check it here + * so we can fail early. + * + * We have one block of index, which can hold 255 index entries. Each + * index entry contains allocation info about 16k metadata blocks. + */ +#define METADATA_DEV_MAX_SECTORS (255 * (1 << 14) * (THIN_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT))) + +/* + * Device id is restricted to 24 bits. + */ +#define MAX_DEV_ID ((1 << 24) - 1) + +/* + * How do we handle breaking sharing of data blocks? + * ================================================= + * + * We use a standard copy-on-write btree to store the mappings for the + * devices (note I'm talking about copy-on-write of the metadata here, not + * the data). When you take an internal snapshot you clone the root node + * of the origin btree. After this there is no concept of an origin or a + * snapshot. They are just two device trees that happen to point to the + * same data blocks. + * + * When we get a write in we decide if it's to a shared data block using + * some timestamp magic. If it is, we have to break sharing. + * + * Let's say we write to a shared block in what was the origin. The + * steps are: + * + * i) plug io further to this physical block. (see bio_prison code). + * + * ii) quiesce any read io to that shared data block. Obviously + * including all devices that share this block. (see deferred_set code) + * + * iii) copy the data block to a newly allocate block. This step can be + * missed out if the io covers the block. (schedule_copy). + * + * iv) insert the new mapping into the origin's btree + * (process_prepared_mappings). This act of inserting breaks some + * sharing of btree nodes between the two devices. Breaking sharing only + * effects the btree of that specific device. Btrees for the other + * devices that share the block never change. The btree for the origin + * device as it was after the last commit is untouched, ie. we're using + * persistent data structures in the functional programming sense. + * + * v) unplug io to this physical block, including the io that triggered + * the breaking of sharing. + * + * Steps (ii) and (iii) occur in parallel. + * + * The metadata _doesn't_ need to be committed before the io continues. We + * get away with this because the io is always written to a _new_ block. + * If there's a crash, then: + * + * - The origin mapping will point to the old origin block (the shared + * one). This will contain the data as it was before the io that triggered + * the breaking of sharing came in. + * + * - The snap mapping still points to the old block. As it would after + * the commit. + * + * The downside of this scheme is the timestamp magic isn't perfect, and + * will continue to think that data block in the snapshot device is shared + * even after the write to the origin has broken sharing. I suspect data + * blocks will typically be shared by many different devices, so we're + * breaking sharing n + 1 times, rather than n, where n is the number of + * devices that reference this data block. At the moment I think the + * benefits far, far outweigh the disadvantages. + */ + +/*----------------------------------------------------------------*/ + +/* + * Sometimes we can't deal with a bio straight away. We put them in prison + * where they can't cause any mischief. Bios are put in a cell identified + * by a key, multiple bios can be in the same cell. When the cell is + * subsequently unlocked the bios become available. + */ +struct bio_prison; + +struct cell_key { + int virtual; + dm_thin_id dev; + dm_block_t block; +}; + +struct cell { + struct hlist_node list; + struct bio_prison *prison; + struct cell_key key; + unsigned count; + struct bio_list bios; +}; + +struct bio_prison { + spinlock_t lock; + mempool_t *cell_pool; + + unsigned nr_buckets; + unsigned hash_mask; + struct hlist_head *cells; +}; + +static uint32_t calc_nr_buckets(unsigned nr_cells) +{ + uint32_t n = 128; + + nr_cells /= 4; + nr_cells = min(nr_cells, 8192u); + + while (n < nr_cells) + n <<= 1; + + return n; +} + +/* + * @nr_cells should be the number of cells you want in use _concurrently_. + * Don't confuse it with the number of distinct keys. + */ +static struct bio_prison *prison_create(unsigned nr_cells) +{ + unsigned i; + uint32_t nr_buckets = calc_nr_buckets(nr_cells); + size_t len = sizeof(struct bio_prison) + + (sizeof(struct hlist_head) * nr_buckets); + struct bio_prison *prison = kmalloc(len, GFP_KERNEL); + + if (!prison) + return NULL; + + spin_lock_init(&prison->lock); + prison->cell_pool = mempool_create_kmalloc_pool(nr_cells, + sizeof(struct cell)); + if (!prison->cell_pool) { + kfree(prison); + return NULL; + } + + prison->nr_buckets = nr_buckets; + prison->hash_mask = nr_buckets - 1; + prison->cells = (struct hlist_head *) (prison + 1); + for (i = 0; i < nr_buckets; i++) + INIT_HLIST_HEAD(prison->cells + i); + + return prison; +} + +static void prison_destroy(struct bio_prison *prison) +{ + mempool_destroy(prison->cell_pool); + kfree(prison); +} + +static uint32_t hash_key(struct bio_prison *prison, struct cell_key *key) +{ + const unsigned long BIG_PRIME = 4294967291UL; + uint64_t hash = key->block * BIG_PRIME; + + return (uint32_t) (hash & prison->hash_mask); +} + +static int keys_equal(struct cell_key *lhs, struct cell_key *rhs) +{ + return (lhs->virtual == rhs->virtual) && + (lhs->dev == rhs->dev) && + (lhs->block == rhs->block); +} + +static struct cell *__search_bucket(struct hlist_head *bucket, + struct cell_key *key) +{ + struct cell *cell; + struct hlist_node *tmp; + + hlist_for_each_entry(cell, tmp, bucket, list) + if (keys_equal(&cell->key, key)) + return cell; + + return NULL; +} + +/* + * This may block if a new cell needs allocating. You must ensure that + * cells will be unlocked even if the calling thread is blocked. + * + * Returns the number of entries in the cell prior to the new addition + * or < 0 on failure. + */ +static int bio_detain(struct bio_prison *prison, struct cell_key *key, + struct bio *inmate, struct cell **ref) +{ + int r; + unsigned long flags; + uint32_t hash = hash_key(prison, key); + struct cell *uninitialized_var(cell), *cell2 = NULL; + + BUG_ON(hash > prison->nr_buckets); + + spin_lock_irqsave(&prison->lock, flags); + cell = __search_bucket(prison->cells + hash, key); + + if (!cell) { + /* + * Allocate a new cell + */ + spin_unlock_irqrestore(&prison->lock, flags); + cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO); + spin_lock_irqsave(&prison->lock, flags); + + /* + * We've been unlocked, so we have to double check that + * nobody else has inserted this cell in the meantime. + */ + cell = __search_bucket(prison->cells + hash, key); + + if (!cell) { + cell = cell2; + cell2 = NULL; + + cell->prison = prison; + memcpy(&cell->key, key, sizeof(cell->key)); + cell->count = 0; + bio_list_init(&cell->bios); + hlist_add_head(&cell->list, prison->cells + hash); + } + } + + r = cell->count++; + bio_list_add(&cell->bios, inmate); + spin_unlock_irqrestore(&prison->lock, flags); + + if (cell2) + mempool_free(cell2, prison->cell_pool); + + *ref = cell; + + return r; +} + +/* + * @inmates must have been initialised prior to this call + */ +static void __cell_release(struct cell *cell, struct bio_list *inmates) +{ + struct bio_prison *prison = cell->prison; + + hlist_del(&cell->list); + + if (inmates) + bio_list_merge(inmates, &cell->bios); + + mempool_free(cell, prison->cell_pool); +} + +static void cell_release(struct cell *cell, struct bio_list *bios) +{ + unsigned long flags; + struct bio_prison *prison = cell->prison; + + spin_lock_irqsave(&prison->lock, flags); + __cell_release(cell, bios); + spin_unlock_irqrestore(&prison->lock, flags); +} + +/* + * There are a couple of places where we put a bio into a cell briefly + * before taking it out again. In these situations we know that no other + * bio may be in the cell. This function releases the cell, and also does + * a sanity check. + */ +static void cell_release_singleton(struct cell *cell, struct bio *bio) +{ + struct bio_prison *prison = cell->prison; + struct bio_list bios; + struct bio *b; + unsigned long flags; + + bio_list_init(&bios); + + spin_lock_irqsave(&prison->lock, flags); + __cell_release(cell, &bios); + spin_unlock_irqrestore(&prison->lock, flags); + + b = bio_list_pop(&bios); + BUG_ON(b != bio); + BUG_ON(!bio_list_empty(&bios)); +} + +static void cell_error(struct cell *cell) +{ + struct bio_prison *prison = cell->prison; + struct bio_list bios; + struct bio *bio; + unsigned long flags; + + bio_list_init(&bios); + + spin_lock_irqsave(&prison->lock, flags); + __cell_release(cell, &bios); + spin_unlock_irqrestore(&prison->lock, flags); + + while ((bio = bio_list_pop(&bios))) + bio_io_error(bio); +} + +/*----------------------------------------------------------------*/ + +/* + * We use the deferred set to keep track of pending reads to shared blocks. + * We do this to ensure the new mapping caused by a write isn't performed + * until these prior reads have completed. Otherwise the insertion of the + * new mapping could free the old block that the read bios are mapped to. + */ + +struct deferred_set; +struct deferred_entry { + struct deferred_set *ds; + unsigned count; + struct list_head work_items; +}; + +struct deferred_set { + spinlock_t lock; + unsigned current_entry; + unsigned sweeper; + struct deferred_entry entries[DEFERRED_SET_SIZE]; +}; + +static void ds_init(struct deferred_set *ds) +{ + int i; + + spin_lock_init(&ds->lock); + ds->current_entry = 0; + ds->sweeper = 0; + for (i = 0; i < DEFERRED_SET_SIZE; i++) { + ds->entries[i].ds = ds; + ds->entries[i].count = 0; + INIT_LIST_HEAD(&ds->entries[i].work_items); + } +} + +static struct deferred_entry *ds_inc(struct deferred_set *ds) +{ + unsigned long flags; + struct deferred_entry *entry; + + spin_lock_irqsave(&ds->lock, flags); + entry = ds->entries + ds->current_entry; + entry->count++; + spin_unlock_irqrestore(&ds->lock, flags); + + return entry; +} + +static unsigned ds_next(unsigned index) +{ + return (index + 1) % DEFERRED_SET_SIZE; +} + +static void __sweep(struct deferred_set *ds, struct list_head *head) +{ + while ((ds->sweeper != ds->current_entry) && + !ds->entries[ds->sweeper].count) { + list_splice_init(&ds->entries[ds->sweeper].work_items, head); + ds->sweeper = ds_next(ds->sweeper); + } + + if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count) + list_splice_init(&ds->entries[ds->sweeper].work_items, head); +} + +static void ds_dec(struct deferred_entry *entry, struct list_head *head) +{ + unsigned long flags; + + spin_lock_irqsave(&entry->ds->lock, flags); + BUG_ON(!entry->count); + --entry->count; + __sweep(entry->ds, head); + spin_unlock_irqrestore(&entry->ds->lock, flags); +} + +/* + * Returns 1 if deferred or 0 if no pending items to delay job. + */ +static int ds_add_work(struct deferred_set *ds, struct list_head *work) +{ + int r = 1; + unsigned long flags; + unsigned next_entry; + + spin_lock_irqsave(&ds->lock, flags); + if ((ds->sweeper == ds->current_entry) && + !ds->entries[ds->current_entry].count) + r = 0; + else { + list_add(work, &ds->entries[ds->current_entry].work_items); + next_entry = ds_next(ds->current_entry); + if (!ds->entries[next_entry].count) + ds->current_entry = next_entry; + } + spin_unlock_irqrestore(&ds->lock, flags); + + return r; +} + +/*----------------------------------------------------------------*/ + +/* + * Key building. + */ +static void build_data_key(struct dm_thin_device *td, + dm_block_t b, struct cell_key *key) +{ + key->virtual = 0; + key->dev = dm_thin_dev_id(td); + key->block = b; +} + +static void build_virtual_key(struct dm_thin_device *td, dm_block_t b, + struct cell_key *key) +{ + key->virtual = 1; + key->dev = dm_thin_dev_id(td); + key->block = b; +} + +/*----------------------------------------------------------------*/ + +/* + * A pool device ties together a metadata device and a data device. It + * also provides the interface for creating and destroying internal + * devices. + */ +struct new_mapping; +struct pool { + struct list_head list; + struct dm_target *ti; /* Only set if a pool target is bound */ + + struct mapped_device *pool_md; + struct block_device *md_dev; + struct dm_pool_metadata *pmd; + + uint32_t sectors_per_block; + unsigned block_shift; + dm_block_t offset_mask; + dm_block_t low_water_blocks; + + unsigned zero_new_blocks:1; + unsigned low_water_triggered:1; /* A dm event has been sent */ + unsigned no_free_space:1; /* A -ENOSPC warning has been issued */ + + struct bio_prison *prison; + struct dm_kcopyd_client *copier; + + struct workqueue_struct *wq; + struct work_struct worker; + + unsigned ref_count; + + spinlock_t lock; + struct bio_list deferred_bios; + struct bio_list deferred_flush_bios; + struct list_head prepared_mappings; + + struct bio_list retry_on_resume_list; + + struct deferred_set ds; /* FIXME: move to thin_c */ + + struct new_mapping *next_mapping; + mempool_t *mapping_pool; + mempool_t *endio_hook_pool; +}; + +/* + * Target context for a pool. + */ +struct pool_c { + struct dm_target *ti; + struct pool *pool; + struct dm_dev *data_dev; + struct dm_dev *metadata_dev; + struct dm_target_callbacks callbacks; + + dm_block_t low_water_blocks; + unsigned zero_new_blocks:1; +}; + +/* + * Target context for a thin. + */ +struct thin_c { + struct dm_dev *pool_dev; + dm_thin_id dev_id; + + struct pool *pool; + struct dm_thin_device *td; +}; + +/*----------------------------------------------------------------*/ + +/* + * A global list of pools that uses a struct mapped_device as a key. + */ +static struct dm_thin_pool_table { + struct mutex mutex; + struct list_head pools; +} dm_thin_pool_table; + +static void pool_table_init(void) +{ + mutex_init(&dm_thin_pool_table.mutex); + INIT_LIST_HEAD(&dm_thin_pool_table.pools); +} + +static void __pool_table_insert(struct pool *pool) +{ + BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex)); + list_add(&pool->list, &dm_thin_pool_table.pools); +} + +static void __pool_table_remove(struct pool *pool) +{ + BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex)); + list_del(&pool->list); +} + +static struct pool *__pool_table_lookup(struct mapped_device *md) +{ + struct pool *pool = NULL, *tmp; + + BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex)); + + list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) { + if (tmp->pool_md == md) { + pool = tmp; + break; + } + } + + return pool; +} + +static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev) +{ + struct pool *pool = NULL, *tmp; + + BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex)); + + list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) { + if (tmp->md_dev == md_dev) { + pool = tmp; + break; + } + } + + return pool; +} + +/*----------------------------------------------------------------*/ + +static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master) +{ + struct bio *bio; + struct bio_list bios; + + bio_list_init(&bios); + bio_list_merge(&bios, master); + bio_list_init(master); + + while ((bio = bio_list_pop(&bios))) { + if (dm_get_mapinfo(bio)->ptr == tc) + bio_endio(bio, DM_ENDIO_REQUEUE); + else + bio_list_add(master, bio); + } +} + +static void requeue_io(struct thin_c *tc) +{ + struct pool *pool = tc->pool; + unsigned long flags; + + spin_lock_irqsave(&pool->lock, flags); + __requeue_bio_list(tc, &pool->deferred_bios); + __requeue_bio_list(tc, &pool->retry_on_resume_list); + spin_unlock_irqrestore(&pool->lock, flags); +} + +/* + * This section of code contains the logic for processing a thin device's IO. + * Much of the code depends on pool object resources (lists, workqueues, etc) + * but most is exclusively called from the thin target rather than the thin-pool + * target. + */ + +static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio) +{ + return bio->bi_sector >> tc->pool->block_shift; +} + +static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block) +{ + struct pool *pool = tc->pool; + + bio->bi_bdev = tc->pool_dev->bdev; + bio->bi_sector = (block << pool->block_shift) + + (bio->bi_sector & pool->offset_mask); +} + +static void remap_and_issue(struct thin_c *tc, struct bio *bio, + dm_block_t block) +{ + struct pool *pool = tc->pool; + unsigned long flags; + + remap(tc, bio, block); + + /* + * Batch together any FUA/FLUSH bios we find and then issue + * a single commit for them in process_deferred_bios(). + */ + if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { + spin_lock_irqsave(&pool->lock, flags); + bio_list_add(&pool->deferred_flush_bios, bio); + spin_unlock_irqrestore(&pool->lock, flags); + } else + generic_make_request(bio); +} + +/* + * wake_worker() is used when new work is queued and when pool_resume is + * ready to continue deferred IO processing. + */ +static void wake_worker(struct pool *pool) +{ + queue_work(pool->wq, &pool->worker); +} + +/*----------------------------------------------------------------*/ + +/* + * Bio endio functions. + */ +struct endio_hook { + struct thin_c *tc; + bio_end_io_t *saved_bi_end_io; + struct deferred_entry *entry; +}; + +struct new_mapping { + struct list_head list; + + int prepared; + + struct thin_c *tc; + dm_block_t virt_block; + dm_block_t data_block; + struct cell *cell; + int err; + + /* + * If the bio covers the whole area of a block then we can avoid + * zeroing or copying. Instead this bio is hooked. The bio will + * still be in the cell, so care has to be taken to avoid issuing + * the bio twice. + */ + struct bio *bio; + bio_end_io_t *saved_bi_end_io; +}; + +static void __maybe_add_mapping(struct new_mapping *m) +{ + struct pool *pool = m->tc->pool; + + if (list_empty(&m->list) && m->prepared) { + list_add(&m->list, &pool->prepared_mappings); + wake_worker(pool); + } +} + +static void copy_complete(int read_err, unsigned long write_err, void *context) +{ + unsigned long flags; + struct new_mapping *m = context; + struct pool *pool = m->tc->pool; + + m->err = read_err || write_err ? -EIO : 0; + + spin_lock_irqsave(&pool->lock, flags); + m->prepared = 1; + __maybe_add_mapping(m); + spin_unlock_irqrestore(&pool->lock, flags); +} + +static void overwrite_endio(struct bio *bio, int err) +{ + unsigned long flags; + struct new_mapping *m = dm_get_mapinfo(bio)->ptr; + struct pool *pool = m->tc->pool; + + m->err = err; + + spin_lock_irqsave(&pool->lock, flags); + m->prepared = 1; + __maybe_add_mapping(m); + spin_unlock_irqrestore(&pool->lock, flags); +} + +static void shared_read_endio(struct bio *bio, int err) +{ + struct list_head mappings; + struct new_mapping *m, *tmp; + struct endio_hook *h = dm_get_mapinfo(bio)->ptr; + unsigned long flags; + struct pool *pool = h->tc->pool; + + bio->bi_end_io = h->saved_bi_end_io; + bio_endio(bio, err); + + INIT_LIST_HEAD(&mappings); + ds_dec(h->entry, &mappings); + + spin_lock_irqsave(&pool->lock, flags); + list_for_each_entry_safe(m, tmp, &mappings, list) { + list_del(&m->list); + INIT_LIST_HEAD(&m->list); + __maybe_add_mapping(m); + } + spin_unlock_irqrestore(&pool->lock, flags); + + mempool_free(h, pool->endio_hook_pool); +} + +/*----------------------------------------------------------------*/ + +/* + * Workqueue. + */ + +/* + * Prepared mapping jobs. + */ + +/* + * This sends the bios in the cell back to the deferred_bios list. + */ +static void cell_defer(struct thin_c *tc, struct cell *cell, + dm_block_t data_block) +{ + struct pool *pool = tc->pool; + unsigned long flags; + + spin_lock_irqsave(&pool->lock, flags); + cell_release(cell, &pool->deferred_bios); + spin_unlock_irqrestore(&tc->pool->lock, flags); + + wake_worker(pool); +} + +/* + * Same as cell_defer above, except it omits one particular detainee, + * a write bio that covers the block and has already been processed. + */ +static void cell_defer_except(struct thin_c *tc, struct cell *cell, + struct bio *exception) +{ + struct bio_list bios; + struct bio *bio; + struct pool *pool = tc->pool; + unsigned long flags; + + bio_list_init(&bios); + cell_release(cell, &bios); + + spin_lock_irqsave(&pool->lock, flags); + while ((bio = bio_list_pop(&bios))) + if (bio != exception) + bio_list_add(&pool->deferred_bios, bio); + spin_unlock_irqrestore(&pool->lock, flags); + + wake_worker(pool); +} + +static void process_prepared_mapping(struct new_mapping *m) +{ + struct thin_c *tc = m->tc; + struct bio *bio; + int r; + + bio = m->bio; + if (bio) + bio->bi_end_io = m->saved_bi_end_io; + + if (m->err) { + cell_error(m->cell); + return; + } + + /* + * Commit the prepared block into the mapping btree. + * Any I/O for this block arriving after this point will get + * remapped to it directly. + */ + r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block); + if (r) { + DMERR("dm_thin_insert_block() failed"); + cell_error(m->cell); + return; + } + + /* + * Release any bios held while the block was being provisioned. + * If we are processing a write bio that completely covers the block, + * we already processed it so can ignore it now when processing + * the bios in the cell. + */ + if (bio) { + cell_defer_except(tc, m->cell, bio); + bio_endio(bio, 0); + } else + cell_defer(tc, m->cell, m->data_block); + + list_del(&m->list); + mempool_free(m, tc->pool->mapping_pool); +} + +static void process_prepared_mappings(struct pool *pool) +{ + unsigned long flags; + struct list_head maps; + struct new_mapping *m, *tmp; + + INIT_LIST_HEAD(&maps); + spin_lock_irqsave(&pool->lock, flags); + list_splice_init(&pool->prepared_mappings, &maps); + spin_unlock_irqrestore(&pool->lock, flags); + + list_for_each_entry_safe(m, tmp, &maps, list) + process_prepared_mapping(m); +} + +/* + * Deferred bio jobs. + */ +static int io_overwrites_block(struct pool *pool, struct bio *bio) +{ + return ((bio_data_dir(bio) == WRITE) && + !(bio->bi_sector & pool->offset_mask)) && + (bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT)); +} + +static void save_and_set_endio(struct bio *bio, bio_end_io_t **save, + bio_end_io_t *fn) +{ + *save = bio->bi_end_io; + bio->bi_end_io = fn; +} + +static int ensure_next_mapping(struct pool *pool) +{ + if (pool->next_mapping) + return 0; + + pool->next_mapping = mempool_alloc(pool->mapping_pool, GFP_ATOMIC); + + return pool->next_mapping ? 0 : -ENOMEM; +} + +static struct new_mapping *get_next_mapping(struct pool *pool) +{ + struct new_mapping *r = pool->next_mapping; + + BUG_ON(!pool->next_mapping); + + pool->next_mapping = NULL; + + return r; +} + +static void schedule_copy(struct thin_c *tc, dm_block_t virt_block, + dm_block_t data_origin, dm_block_t data_dest, + struct cell *cell, struct bio *bio) +{ + int r; + struct pool *pool = tc->pool; + struct new_mapping *m = get_next_mapping(pool); + + INIT_LIST_HEAD(&m->list); + m->prepared = 0; + m->tc = tc; + m->virt_block = virt_block; + m->data_block = data_dest; + m->cell = cell; + m->err = 0; + m->bio = NULL; + + ds_add_work(&pool->ds, &m->list); + + /* + * IO to pool_dev remaps to the pool target's data_dev. + * + * If the whole block of data is being overwritten, we can issue the + * bio immediately. Otherwise we use kcopyd to clone the data first. + */ + if (io_overwrites_block(pool, bio)) { + m->bio = bio; + save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio); + dm_get_mapinfo(bio)->ptr = m; + remap_and_issue(tc, bio, data_dest); + } else { + struct dm_io_region from, to; + + from.bdev = tc->pool_dev->bdev; + from.sector = data_origin * pool->sectors_per_block; + from.count = pool->sectors_per_block; + + to.bdev = tc->pool_dev->bdev; + to.sector = data_dest * pool->sectors_per_block; + to.count = pool->sectors_per_block; + + r = dm_kcopyd_copy(pool->copier, &from, 1, &to, + 0, copy_complete, m); + if (r < 0) { + mempool_free(m, pool->mapping_pool); + DMERR("dm_kcopyd_copy() failed"); + cell_error(cell); + } + } +} + +static void schedule_zero(struct thin_c *tc, dm_block_t virt_block, + dm_block_t data_block, struct cell *cell, + struct bio *bio) +{ + struct pool *pool = tc->pool; + struct new_mapping *m = get_next_mapping(pool); + + INIT_LIST_HEAD(&m->list); + m->prepared = 0; + m->tc = tc; + m->virt_block = virt_block; + m->data_block = data_block; + m->cell = cell; + m->err = 0; + m->bio = NULL; + + /* + * If the whole block of data is being overwritten or we are not + * zeroing pre-existing data, we can issue the bio immediately. + * Otherwise we use kcopyd to zero the data first. + */ + if (!pool->zero_new_blocks) + process_prepared_mapping(m); + + else if (io_overwrites_block(pool, bio)) { + m->bio = bio; + save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio); + dm_get_mapinfo(bio)->ptr = m; + remap_and_issue(tc, bio, data_block); + + } else { + int r; + struct dm_io_region to; + + to.bdev = tc->pool_dev->bdev; + to.sector = data_block * pool->sectors_per_block; + to.count = pool->sectors_per_block; + + r = dm_kcopyd_zero(pool->copier, 1, &to, 0, copy_complete, m); + if (r < 0) { + mempool_free(m, pool->mapping_pool); + DMERR("dm_kcopyd_zero() failed"); + cell_error(cell); + } + } +} + +static int alloc_data_block(struct thin_c *tc, dm_block_t *result) +{ + int r; + dm_block_t free_blocks; + unsigned long flags; + struct pool *pool = tc->pool; + + r = dm_pool_get_free_block_count(pool->pmd, &free_blocks); + if (r) + return r; + + if (free_blocks <= pool->low_water_blocks && !pool->low_water_triggered) { + DMWARN("%s: reached low water mark, sending event.", + dm_device_name(pool->pool_md)); + spin_lock_irqsave(&pool->lock, flags); + pool->low_water_triggered = 1; + spin_unlock_irqrestore(&pool->lock, flags); + dm_table_event(pool->ti->table); + } + + if (!free_blocks) { + if (pool->no_free_space) + return -ENOSPC; + else { + /* + * Try to commit to see if that will free up some + * more space. + */ + r = dm_pool_commit_metadata(pool->pmd); + if (r) { + DMERR("%s: dm_pool_commit_metadata() failed, error = %d", + __func__, r); + return r; + } + + r = dm_pool_get_free_block_count(pool->pmd, &free_blocks); + if (r) + return r; + + /* + * If we still have no space we set a flag to avoid + * doing all this checking and return -ENOSPC. + */ + if (!free_blocks) { + DMWARN("%s: no free space available.", + dm_device_name(pool->pool_md)); + spin_lock_irqsave(&pool->lock, flags); + pool->no_free_space = 1; + spin_unlock_irqrestore(&pool->lock, flags); + return -ENOSPC; + } + } + } + + r = dm_pool_alloc_data_block(pool->pmd, result); + if (r) + return r; + + return 0; +} + +/* + * If we have run out of space, queue bios until the device is + * resumed, presumably after having been reloaded with more space. + */ +static void retry_on_resume(struct bio *bio) +{ + struct thin_c *tc = dm_get_mapinfo(bio)->ptr; + struct pool *pool = tc->pool; + unsigned long flags; + + spin_lock_irqsave(&pool->lock, flags); + bio_list_add(&pool->retry_on_resume_list, bio); + spin_unlock_irqrestore(&pool->lock, flags); +} + +static void no_space(struct cell *cell) +{ + struct bio *bio; + struct bio_list bios; + + bio_list_init(&bios); + cell_release(cell, &bios); + + while ((bio = bio_list_pop(&bios))) + retry_on_resume(bio); +} + +static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block, + struct cell_key *key, + struct dm_thin_lookup_result *lookup_result, + struct cell *cell) +{ + int r; + dm_block_t data_block; + + r = alloc_data_block(tc, &data_block); + switch (r) { + case 0: + schedule_copy(tc, block, lookup_result->block, + data_block, cell, bio); + break; + + case -ENOSPC: + no_space(cell); + break; + + default: + DMERR("%s: alloc_data_block() failed, error = %d", __func__, r); + cell_error(cell); + break; + } +} + +static void process_shared_bio(struct thin_c *tc, struct bio *bio, + dm_block_t block, + struct dm_thin_lookup_result *lookup_result) +{ + struct cell *cell; + struct pool *pool = tc->pool; + struct cell_key key; + + /* + * If cell is already occupied, then sharing is already in the process + * of being broken so we have nothing further to do here. + */ + build_data_key(tc->td, lookup_result->block, &key); + if (bio_detain(pool->prison, &key, bio, &cell)) + return; + + if (bio_data_dir(bio) == WRITE) + break_sharing(tc, bio, block, &key, lookup_result, cell); + else { + struct endio_hook *h; + h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO); + + h->tc = tc; + h->entry = ds_inc(&pool->ds); + save_and_set_endio(bio, &h->saved_bi_end_io, shared_read_endio); + dm_get_mapinfo(bio)->ptr = h; + + cell_release_singleton(cell, bio); + remap_and_issue(tc, bio, lookup_result->block); + } +} + +static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block, + struct cell *cell) +{ + int r; + dm_block_t data_block; + + /* + * Remap empty bios (flushes) immediately, without provisioning. + */ + if (!bio->bi_size) { + cell_release_singleton(cell, bio); + remap_and_issue(tc, bio, 0); + return; + } + + /* + * Fill read bios with zeroes and complete them immediately. + */ + if (bio_data_dir(bio) == READ) { + zero_fill_bio(bio); + cell_release_singleton(cell, bio); + bio_endio(bio, 0); + return; + } + + r = alloc_data_block(tc, &data_block); + switch (r) { + case 0: + schedule_zero(tc, block, data_block, cell, bio); + break; + + case -ENOSPC: + no_space(cell); + break; + + default: + DMERR("%s: alloc_data_block() failed, error = %d", __func__, r); + cell_error(cell); + break; + } +} + +static void process_bio(struct thin_c *tc, struct bio *bio) +{ + int r; + dm_block_t block = get_bio_block(tc, bio); + struct cell *cell; + struct cell_key key; + struct dm_thin_lookup_result lookup_result; + + /* + * If cell is already occupied, then the block is already + * being provisioned so we have nothing further to do here. + */ + build_virtual_key(tc->td, block, &key); + if (bio_detain(tc->pool->prison, &key, bio, &cell)) + return; + + r = dm_thin_find_block(tc->td, block, 1, &lookup_result); + switch (r) { + case 0: + /* + * We can release this cell now. This thread is the only + * one that puts bios into a cell, and we know there were + * no preceding bios. + */ + /* + * TODO: this will probably have to change when discard goes + * back in. + */ + cell_release_singleton(cell, bio); + + if (lookup_result.shared) + process_shared_bio(tc, bio, block, &lookup_result); + else + remap_and_issue(tc, bio, lookup_result.block); + break; + + case -ENODATA: + provision_block(tc, bio, block, cell); + break; + + default: + DMERR("dm_thin_find_block() failed, error = %d", r); + bio_io_error(bio); + break; + } +} + +static void process_deferred_bios(struct pool *pool) +{ + unsigned long flags; + struct bio *bio; + struct bio_list bios; + int r; + + bio_list_init(&bios); + + spin_lock_irqsave(&pool->lock, flags); + bio_list_merge(&bios, &pool->deferred_bios); + bio_list_init(&pool->deferred_bios); + spin_unlock_irqrestore(&pool->lock, flags); + + while ((bio = bio_list_pop(&bios))) { + struct thin_c *tc = dm_get_mapinfo(bio)->ptr; + /* + * If we've got no free new_mapping structs, and processing + * this bio might require one, we pause until there are some + * prepared mappings to process. + */ + if (ensure_next_mapping(pool)) { + spin_lock_irqsave(&pool->lock, flags); + bio_list_merge(&pool->deferred_bios, &bios); + spin_unlock_irqrestore(&pool->lock, flags); + + break; + } + process_bio(tc, bio); + } + + /* + * If there are any deferred flush bios, we must commit + * the metadata before issuing them. + */ + bio_list_init(&bios); + spin_lock_irqsave(&pool->lock, flags); + bio_list_merge(&bios, &pool->deferred_flush_bios); + bio_list_init(&pool->deferred_flush_bios); + spin_unlock_irqrestore(&pool->lock, flags); + + if (bio_list_empty(&bios)) + return; + + r = dm_pool_commit_metadata(pool->pmd); + if (r) { + DMERR("%s: dm_pool_commit_metadata() failed, error = %d", + __func__, r); + while ((bio = bio_list_pop(&bios))) + bio_io_error(bio); + return; + } + + while ((bio = bio_list_pop(&bios))) + generic_make_request(bio); +} + +static void do_worker(struct work_struct *ws) +{ + struct pool *pool = container_of(ws, struct pool, worker); + + process_prepared_mappings(pool); + process_deferred_bios(pool); +} + +/*----------------------------------------------------------------*/ + +/* + * Mapping functions. + */ + +/* + * Called only while mapping a thin bio to hand it over to the workqueue. + */ +static void thin_defer_bio(struct thin_c *tc, struct bio *bio) +{ + unsigned long flags; + struct pool *pool = tc->pool; + + spin_lock_irqsave(&pool->lock, flags); + bio_list_add(&pool->deferred_bios, bio); + spin_unlock_irqrestore(&pool->lock, flags); + + wake_worker(pool); +} + +/* + * Non-blocking function called from the thin target's map function. + */ +static int thin_bio_map(struct dm_target *ti, struct bio *bio, + union map_info *map_context) +{ + int r; + struct thin_c *tc = ti->private; + dm_block_t block = get_bio_block(tc, bio); + struct dm_thin_device *td = tc->td; + struct dm_thin_lookup_result result; + + /* + * Save the thin context for easy access from the deferred bio later. + */ + map_context->ptr = tc; + + if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { + thin_defer_bio(tc, bio); + return DM_MAPIO_SUBMITTED; + } + + r = dm_thin_find_block(td, block, 0, &result); + + /* + * Note that we defer readahead too. + */ + switch (r) { + case 0: + if (unlikely(result.shared)) { + /* + * We have a race condition here between the + * result.shared value returned by the lookup and + * snapshot creation, which may cause new + * sharing. + * + * To avoid this always quiesce the origin before + * taking the snap. You want to do this anyway to + * ensure a consistent application view + * (i.e. lockfs). + * + * More distant ancestors are irrelevant. The + * shared flag will be set in their case. + */ + thin_defer_bio(tc, bio); + r = DM_MAPIO_SUBMITTED; + } else { + remap(tc, bio, result.block); + r = DM_MAPIO_REMAPPED; + } + break; + + case -ENODATA: + /* + * In future, the failed dm_thin_find_block above could + * provide the hint to load the metadata into cache. + */ + case -EWOULDBLOCK: + thin_defer_bio(tc, bio); + r = DM_MAPIO_SUBMITTED; + break; + } + + return r; +} + +static int pool_is_congested(struct dm_target_callbacks *cb, int bdi_bits) +{ + int r; + unsigned long flags; + struct pool_c *pt = container_of(cb, struct pool_c, callbacks); + + spin_lock_irqsave(&pt->pool->lock, flags); + r = !bio_list_empty(&pt->pool->retry_on_resume_list); + spin_unlock_irqrestore(&pt->pool->lock, flags); + + if (!r) { + struct request_queue *q = bdev_get_queue(pt->data_dev->bdev); + r = bdi_congested(&q->backing_dev_info, bdi_bits); + } + + return r; +} + +static void __requeue_bios(struct pool *pool) +{ + bio_list_merge(&pool->deferred_bios, &pool->retry_on_resume_list); + bio_list_init(&pool->retry_on_resume_list); +} + +/*---------------------------------------------------------------- + * Binding of control targets to a pool object + *--------------------------------------------------------------*/ +static int bind_control_target(struct pool *pool, struct dm_target *ti) +{ + struct pool_c *pt = ti->private; + + pool->ti = ti; + pool->low_water_blocks = pt->low_water_blocks; + pool->zero_new_blocks = pt->zero_new_blocks; + + return 0; +} + +static void unbind_control_target(struct pool *pool, struct dm_target *ti) +{ + if (pool->ti == ti) + pool->ti = NULL; +} + +/*---------------------------------------------------------------- + * Pool creation + *--------------------------------------------------------------*/ +static void __pool_destroy(struct pool *pool) +{ + __pool_table_remove(pool); + + if (dm_pool_metadata_close(pool->pmd) < 0) + DMWARN("%s: dm_pool_metadata_close() failed.", __func__); + + prison_destroy(pool->prison); + dm_kcopyd_client_destroy(pool->copier); + + if (pool->wq) + destroy_workqueue(pool->wq); + + if (pool->next_mapping) + mempool_free(pool->next_mapping, pool->mapping_pool); + mempool_destroy(pool->mapping_pool); + mempool_destroy(pool->endio_hook_pool); + kfree(pool); +} + +static struct pool *pool_create(struct mapped_device *pool_md, + struct block_device *metadata_dev, + unsigned long block_size, char **error) +{ + int r; + void *err_p; + struct pool *pool; + struct dm_pool_metadata *pmd; + + pmd = dm_pool_metadata_open(metadata_dev, block_size); + if (IS_ERR(pmd)) { + *error = "Error creating metadata object"; + return (struct pool *)pmd; + } + + pool = kmalloc(sizeof(*pool), GFP_KERNEL); + if (!pool) { + *error = "Error allocating memory for pool"; + err_p = ERR_PTR(-ENOMEM); + goto bad_pool; + } + + pool->pmd = pmd; + pool->sectors_per_block = block_size; + pool->block_shift = ffs(block_size) - 1; + pool->offset_mask = block_size - 1; + pool->low_water_blocks = 0; + pool->zero_new_blocks = 1; + pool->prison = prison_create(PRISON_CELLS); + if (!pool->prison) { + *error = "Error creating pool's bio prison"; + err_p = ERR_PTR(-ENOMEM); + goto bad_prison; + } + + pool->copier = dm_kcopyd_client_create(); + if (IS_ERR(pool->copier)) { + r = PTR_ERR(pool->copier); + *error = "Error creating pool's kcopyd client"; + err_p = ERR_PTR(r); + goto bad_kcopyd_client; + } + + /* + * Create singlethreaded workqueue that will service all devices + * that use this metadata. + */ + pool->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM); + if (!pool->wq) { + *error = "Error creating pool's workqueue"; + err_p = ERR_PTR(-ENOMEM); + goto bad_wq; + } + + INIT_WORK(&pool->worker, do_worker); + spin_lock_init(&pool->lock); + bio_list_init(&pool->deferred_bios); + bio_list_init(&pool->deferred_flush_bios); + INIT_LIST_HEAD(&pool->prepared_mappings); + pool->low_water_triggered = 0; + pool->no_free_space = 0; + bio_list_init(&pool->retry_on_resume_list); + ds_init(&pool->ds); + + pool->next_mapping = NULL; + pool->mapping_pool = + mempool_create_kmalloc_pool(MAPPING_POOL_SIZE, sizeof(struct new_mapping)); + if (!pool->mapping_pool) { + *error = "Error creating pool's mapping mempool"; + err_p = ERR_PTR(-ENOMEM); + goto bad_mapping_pool; + } + + pool->endio_hook_pool = + mempool_create_kmalloc_pool(ENDIO_HOOK_POOL_SIZE, sizeof(struct endio_hook)); + if (!pool->endio_hook_pool) { + *error = "Error creating pool's endio_hook mempool"; + err_p = ERR_PTR(-ENOMEM); + goto bad_endio_hook_pool; + } + pool->ref_count = 1; + pool->pool_md = pool_md; + pool->md_dev = metadata_dev; + __pool_table_insert(pool); + + return pool; + +bad_endio_hook_pool: + mempool_destroy(pool->mapping_pool); +bad_mapping_pool: + destroy_workqueue(pool->wq); +bad_wq: + dm_kcopyd_client_destroy(pool->copier); +bad_kcopyd_client: + prison_destroy(pool->prison); +bad_prison: + kfree(pool); +bad_pool: + if (dm_pool_metadata_close(pmd)) + DMWARN("%s: dm_pool_metadata_close() failed.", __func__); + + return err_p; +} + +static void __pool_inc(struct pool *pool) +{ + BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex)); + pool->ref_count++; +} + +static void __pool_dec(struct pool *pool) +{ + BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex)); + BUG_ON(!pool->ref_count); + if (!--pool->ref_count) + __pool_destroy(pool); +} + +static struct pool *__pool_find(struct mapped_device *pool_md, + struct block_device *metadata_dev, + unsigned long block_size, char **error) +{ + struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev); + + if (pool) { + if (pool->pool_md != pool_md) + return ERR_PTR(-EBUSY); + __pool_inc(pool); + + } else { + pool = __pool_table_lookup(pool_md); + if (pool) { + if (pool->md_dev != metadata_dev) + return ERR_PTR(-EINVAL); + __pool_inc(pool); + + } else + pool = pool_create(pool_md, metadata_dev, block_size, error); + } + + return pool; +} + +/*---------------------------------------------------------------- + * Pool target methods + *--------------------------------------------------------------*/ +static void pool_dtr(struct dm_target *ti) +{ + struct pool_c *pt = ti->private; + + mutex_lock(&dm_thin_pool_table.mutex); + + unbind_control_target(pt->pool, ti); + __pool_dec(pt->pool); + dm_put_device(ti, pt->metadata_dev); + dm_put_device(ti, pt->data_dev); + kfree(pt); + + mutex_unlock(&dm_thin_pool_table.mutex); +} + +struct pool_features { + unsigned zero_new_blocks:1; +}; + +static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf, + struct dm_target *ti) +{ + int r; + unsigned argc; + const char *arg_name; + + static struct dm_arg _args[] = { + {0, 1, "Invalid number of pool feature arguments"}, + }; + + /* + * No feature arguments supplied. + */ + if (!as->argc) + return 0; + + r = dm_read_arg_group(_args, as, &argc, &ti->error); + if (r) + return -EINVAL; + + while (argc && !r) { + arg_name = dm_shift_arg(as); + argc--; + + if (!strcasecmp(arg_name, "skip_block_zeroing")) { + pf->zero_new_blocks = 0; + continue; + } + + ti->error = "Unrecognised pool feature requested"; + r = -EINVAL; + } + + return r; +} + +/* + * thin-pool <metadata dev> <data dev> + * <data block size (sectors)> + * <low water mark (blocks)> + * [<#feature args> [<arg>]*] + * + * Optional feature arguments are: + * skip_block_zeroing: skips the zeroing of newly-provisioned blocks. + */ +static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) +{ + int r; + struct pool_c *pt; + struct pool *pool; + struct pool_features pf; + struct dm_arg_set as; + struct dm_dev *data_dev; + unsigned long block_size; + dm_block_t low_water_blocks; + struct dm_dev *metadata_dev; + sector_t metadata_dev_size; + + /* + * FIXME Remove validation from scope of lock. + */ + mutex_lock(&dm_thin_pool_table.mutex); + + if (argc < 4) { + ti->error = "Invalid argument count"; + r = -EINVAL; + goto out_unlock; + } + as.argc = argc; + as.argv = argv; + + r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &metadata_dev); + if (r) { + ti->error = "Error opening metadata block device"; + goto out_unlock; + } + + metadata_dev_size = i_size_read(metadata_dev->bdev->bd_inode) >> SECTOR_SHIFT; + if (metadata_dev_size > METADATA_DEV_MAX_SECTORS) { + ti->error = "Metadata device is too large"; + r = -EINVAL; + goto out_metadata; + } + + r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev); + if (r) { + ti->error = "Error getting data device"; + goto out_metadata; + } + + if (kstrtoul(argv[2], 10, &block_size) || !block_size || + block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS || + block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS || + !is_power_of_2(block_size)) { + ti->error = "Invalid block size"; + r = -EINVAL; + goto out; + } + + if (kstrtoull(argv[3], 10, (unsigned long long *)&low_water_blocks)) { + ti->error = "Invalid low water mark"; + r = -EINVAL; + goto out; + } + + /* + * Set default pool features. + */ + memset(&pf, 0, sizeof(pf)); + pf.zero_new_blocks = 1; + + dm_consume_args(&as, 4); + r = parse_pool_features(&as, &pf, ti); + if (r) + goto out; + + pt = kzalloc(sizeof(*pt), GFP_KERNEL); + if (!pt) { + r = -ENOMEM; + goto out; + } + + pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev, + block_size, &ti->error); + if (IS_ERR(pool)) { + r = PTR_ERR(pool); + goto out_free_pt; + } + + pt->pool = pool; + pt->ti = ti; + pt->metadata_dev = metadata_dev; + pt->data_dev = data_dev; + pt->low_water_blocks = low_water_blocks; + pt->zero_new_blocks = pf.zero_new_blocks; + ti->num_flush_requests = 1; + ti->num_discard_requests = 0; + ti->private = pt; + + pt->callbacks.congested_fn = pool_is_congested; + dm_table_add_target_callbacks(ti->table, &pt->callbacks); + + mutex_unlock(&dm_thin_pool_table.mutex); + + return 0; + +out_free_pt: + kfree(pt); +out: + dm_put_device(ti, data_dev); +out_metadata: + dm_put_device(ti, metadata_dev); +out_unlock: + mutex_unlock(&dm_thin_pool_table.mutex); + + return r; +} + +static int pool_map(struct dm_target *ti, struct bio *bio, + union map_info *map_context) +{ + int r; + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + unsigned long flags; + + /* + * As this is a singleton target, ti->begin is always zero. + */ + spin_lock_irqsave(&pool->lock, flags); + bio->bi_bdev = pt->data_dev->bdev; + r = DM_MAPIO_REMAPPED; + spin_unlock_irqrestore(&pool->lock, flags); + + return r; +} + +/* + * Retrieves the number of blocks of the data device from + * the superblock and compares it to the actual device size, + * thus resizing the data device in case it has grown. + * + * This both copes with opening preallocated data devices in the ctr + * being followed by a resume + * -and- + * calling the resume method individually after userspace has + * grown the data device in reaction to a table event. + */ +static int pool_preresume(struct dm_target *ti) +{ + int r; + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + dm_block_t data_size, sb_data_size; + + /* + * Take control of the pool object. + */ + r = bind_control_target(pool, ti); + if (r) + return r; + + data_size = ti->len >> pool->block_shift; + r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size); + if (r) { + DMERR("failed to retrieve data device size"); + return r; + } + + if (data_size < sb_data_size) { + DMERR("pool target too small, is %llu blocks (expected %llu)", + data_size, sb_data_size); + return -EINVAL; + + } else if (data_size > sb_data_size) { + r = dm_pool_resize_data_dev(pool->pmd, data_size); + if (r) { + DMERR("failed to resize data device"); + return r; + } + + r = dm_pool_commit_metadata(pool->pmd); + if (r) { + DMERR("%s: dm_pool_commit_metadata() failed, error = %d", + __func__, r); + return r; + } + } + + return 0; +} + +static void pool_resume(struct dm_target *ti) +{ + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + unsigned long flags; + + spin_lock_irqsave(&pool->lock, flags); + pool->low_water_triggered = 0; + pool->no_free_space = 0; + __requeue_bios(pool); + spin_unlock_irqrestore(&pool->lock, flags); + + wake_worker(pool); +} + +static void pool_postsuspend(struct dm_target *ti) +{ + int r; + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + + flush_workqueue(pool->wq); + + r = dm_pool_commit_metadata(pool->pmd); + if (r < 0) { + DMERR("%s: dm_pool_commit_metadata() failed, error = %d", + __func__, r); + /* FIXME: invalidate device? error the next FUA or FLUSH bio ?*/ + } +} + +static int check_arg_count(unsigned argc, unsigned args_required) +{ + if (argc != args_required) { + DMWARN("Message received with %u arguments instead of %u.", + argc, args_required); + return -EINVAL; + } + + return 0; +} + +static int read_dev_id(char *arg, dm_thin_id *dev_id, int warning) +{ + if (!kstrtoull(arg, 10, (unsigned long long *)dev_id) && + *dev_id <= MAX_DEV_ID) + return 0; + + if (warning) + DMWARN("Message received with invalid device id: %s", arg); + + return -EINVAL; +} + +static int process_create_thin_mesg(unsigned argc, char **argv, struct pool *pool) +{ + dm_thin_id dev_id; + int r; + + r = check_arg_count(argc, 2); + if (r) + return r; + + r = read_dev_id(argv[1], &dev_id, 1); + if (r) + return r; + + r = dm_pool_create_thin(pool->pmd, dev_id); + if (r) { + DMWARN("Creation of new thinly-provisioned device with id %s failed.", + argv[1]); + return r; + } + + return 0; +} + +static int process_create_snap_mesg(unsigned argc, char **argv, struct pool *pool) +{ + dm_thin_id dev_id; + dm_thin_id origin_dev_id; + int r; + + r = check_arg_count(argc, 3); + if (r) + return r; + + r = read_dev_id(argv[1], &dev_id, 1); + if (r) + return r; + + r = read_dev_id(argv[2], &origin_dev_id, 1); + if (r) + return r; + + r = dm_pool_create_snap(pool->pmd, dev_id, origin_dev_id); + if (r) { + DMWARN("Creation of new snapshot %s of device %s failed.", + argv[1], argv[2]); + return r; + } + + return 0; +} + +static int process_delete_mesg(unsigned argc, char **argv, struct pool *pool) +{ + dm_thin_id dev_id; + int r; + + r = check_arg_count(argc, 2); + if (r) + return r; + + r = read_dev_id(argv[1], &dev_id, 1); + if (r) + return r; + + r = dm_pool_delete_thin_device(pool->pmd, dev_id); + if (r) + DMWARN("Deletion of thin device %s failed.", argv[1]); + + return r; +} + +static int process_set_transaction_id_mesg(unsigned argc, char **argv, struct pool *pool) +{ + dm_thin_id old_id, new_id; + int r; + + r = check_arg_count(argc, 3); + if (r) + return r; + + if (kstrtoull(argv[1], 10, (unsigned long long *)&old_id)) { + DMWARN("set_transaction_id message: Unrecognised id %s.", argv[1]); + return -EINVAL; + } + + if (kstrtoull(argv[2], 10, (unsigned long long *)&new_id)) { + DMWARN("set_transaction_id message: Unrecognised new id %s.", argv[2]); + return -EINVAL; + } + + r = dm_pool_set_metadata_transaction_id(pool->pmd, old_id, new_id); + if (r) { + DMWARN("Failed to change transaction id from %s to %s.", + argv[1], argv[2]); + return r; + } + + return 0; +} + +/* + * Messages supported: + * create_thin <dev_id> + * create_snap <dev_id> <origin_id> + * delete <dev_id> + * trim <dev_id> <new_size_in_sectors> + * set_transaction_id <current_trans_id> <new_trans_id> + */ +static int pool_message(struct dm_target *ti, unsigned argc, char **argv) +{ + int r = -EINVAL; + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + + if (!strcasecmp(argv[0], "create_thin")) + r = process_create_thin_mesg(argc, argv, pool); + + else if (!strcasecmp(argv[0], "create_snap")) + r = process_create_snap_mesg(argc, argv, pool); + + else if (!strcasecmp(argv[0], "delete")) + r = process_delete_mesg(argc, argv, pool); + + else if (!strcasecmp(argv[0], "set_transaction_id")) + r = process_set_transaction_id_mesg(argc, argv, pool); + + else + DMWARN("Unrecognised thin pool target message received: %s", argv[0]); + + if (!r) { + r = dm_pool_commit_metadata(pool->pmd); + if (r) + DMERR("%s message: dm_pool_commit_metadata() failed, error = %d", + argv[0], r); + } + + return r; +} + +/* + * Status line is: + * <transaction id> <used metadata sectors>/<total metadata sectors> + * <used data sectors>/<total data sectors> <held metadata root> + */ +static int pool_status(struct dm_target *ti, status_type_t type, + char *result, unsigned maxlen) +{ + int r; + unsigned sz = 0; + uint64_t transaction_id; + dm_block_t nr_free_blocks_data; + dm_block_t nr_free_blocks_metadata; + dm_block_t nr_blocks_data; + dm_block_t nr_blocks_metadata; + dm_block_t held_root; + char buf[BDEVNAME_SIZE]; + char buf2[BDEVNAME_SIZE]; + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + + switch (type) { + case STATUSTYPE_INFO: + r = dm_pool_get_metadata_transaction_id(pool->pmd, + &transaction_id); + if (r) + return r; + + r = dm_pool_get_free_metadata_block_count(pool->pmd, + &nr_free_blocks_metadata); + if (r) + return r; + + r = dm_pool_get_metadata_dev_size(pool->pmd, &nr_blocks_metadata); + if (r) + return r; + + r = dm_pool_get_free_block_count(pool->pmd, + &nr_free_blocks_data); + if (r) + return r; + + r = dm_pool_get_data_dev_size(pool->pmd, &nr_blocks_data); + if (r) + return r; + + r = dm_pool_get_held_metadata_root(pool->pmd, &held_root); + if (r) + return r; + + DMEMIT("%llu %llu/%llu %llu/%llu ", + (unsigned long long)transaction_id, + (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata), + (unsigned long long)nr_blocks_metadata, + (unsigned long long)(nr_blocks_data - nr_free_blocks_data), + (unsigned long long)nr_blocks_data); + + if (held_root) + DMEMIT("%llu", held_root); + else + DMEMIT("-"); + + break; + + case STATUSTYPE_TABLE: + DMEMIT("%s %s %lu %llu ", + format_dev_t(buf, pt->metadata_dev->bdev->bd_dev), + format_dev_t(buf2, pt->data_dev->bdev->bd_dev), + (unsigned long)pool->sectors_per_block, + (unsigned long long)pt->low_water_blocks); + + DMEMIT("%u ", !pool->zero_new_blocks); + + if (!pool->zero_new_blocks) + DMEMIT("skip_block_zeroing "); + break; + } + + return 0; +} + +static int pool_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + struct pool_c *pt = ti->private; + + return fn(ti, pt->data_dev, 0, ti->len, data); +} + +static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm, + struct bio_vec *biovec, int max_size) +{ + struct pool_c *pt = ti->private; + struct request_queue *q = bdev_get_queue(pt->data_dev->bdev); + + if (!q->merge_bvec_fn) + return max_size; + + bvm->bi_bdev = pt->data_dev->bdev; + + return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); +} + +static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits) +{ + struct pool_c *pt = ti->private; + struct pool *pool = pt->pool; + + blk_limits_io_min(limits, 0); + blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT); +} + +static struct target_type pool_target = { + .name = "thin-pool", + .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE | + DM_TARGET_IMMUTABLE, + .version = {1, 0, 0}, + .module = THIS_MODULE, + .ctr = pool_ctr, + .dtr = pool_dtr, + .map = pool_map, + .postsuspend = pool_postsuspend, + .preresume = pool_preresume, + .resume = pool_resume, + .message = pool_message, + .status = pool_status, + .merge = pool_merge, + .iterate_devices = pool_iterate_devices, + .io_hints = pool_io_hints, +}; + +/*---------------------------------------------------------------- + * Thin target methods + *--------------------------------------------------------------*/ +static void thin_dtr(struct dm_target *ti) +{ + struct thin_c *tc = ti->private; + + mutex_lock(&dm_thin_pool_table.mutex); + + __pool_dec(tc->pool); + dm_pool_close_thin_device(tc->td); + dm_put_device(ti, tc->pool_dev); + kfree(tc); + + mutex_unlock(&dm_thin_pool_table.mutex); +} + +/* + * Thin target parameters: + * + * <pool_dev> <dev_id> + * + * pool_dev: the path to the pool (eg, /dev/mapper/my_pool) + * dev_id: the internal device identifier + */ +static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv) +{ + int r; + struct thin_c *tc; + struct dm_dev *pool_dev; + struct mapped_device *pool_md; + + mutex_lock(&dm_thin_pool_table.mutex); + + if (argc != 2) { + ti->error = "Invalid argument count"; + r = -EINVAL; + goto out_unlock; + } + + tc = ti->private = kzalloc(sizeof(*tc), GFP_KERNEL); + if (!tc) { + ti->error = "Out of memory"; + r = -ENOMEM; + goto out_unlock; + } + + r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &pool_dev); + if (r) { + ti->error = "Error opening pool device"; + goto bad_pool_dev; + } + tc->pool_dev = pool_dev; + + if (read_dev_id(argv[1], (unsigned long long *)&tc->dev_id, 0)) { + ti->error = "Invalid device id"; + r = -EINVAL; + goto bad_common; + } + + pool_md = dm_get_md(tc->pool_dev->bdev->bd_dev); + if (!pool_md) { + ti->error = "Couldn't get pool mapped device"; + r = -EINVAL; + goto bad_common; + } + + tc->pool = __pool_table_lookup(pool_md); + if (!tc->pool) { + ti->error = "Couldn't find pool object"; + r = -EINVAL; + goto bad_pool_lookup; + } + __pool_inc(tc->pool); + + r = dm_pool_open_thin_device(tc->pool->pmd, tc->dev_id, &tc->td); + if (r) { + ti->error = "Couldn't open thin internal device"; + goto bad_thin_open; + } + + ti->split_io = tc->pool->sectors_per_block; + ti->num_flush_requests = 1; + ti->num_discard_requests = 0; + ti->discards_supported = 0; + + dm_put(pool_md); + + mutex_unlock(&dm_thin_pool_table.mutex); + + return 0; + +bad_thin_open: + __pool_dec(tc->pool); +bad_pool_lookup: + dm_put(pool_md); +bad_common: + dm_put_device(ti, tc->pool_dev); +bad_pool_dev: + kfree(tc); +out_unlock: + mutex_unlock(&dm_thin_pool_table.mutex); + + return r; +} + +static int thin_map(struct dm_target *ti, struct bio *bio, + union map_info *map_context) +{ + bio->bi_sector -= ti->begin; + + return thin_bio_map(ti, bio, map_context); +} + +static void thin_postsuspend(struct dm_target *ti) +{ + if (dm_noflush_suspending(ti)) + requeue_io((struct thin_c *)ti->private); +} + +/* + * <nr mapped sectors> <highest mapped sector> + */ +static int thin_status(struct dm_target *ti, status_type_t type, + char *result, unsigned maxlen) +{ + int r; + ssize_t sz = 0; + dm_block_t mapped, highest; + char buf[BDEVNAME_SIZE]; + struct thin_c *tc = ti->private; + + if (!tc->td) + DMEMIT("-"); + else { + switch (type) { + case STATUSTYPE_INFO: + r = dm_thin_get_mapped_count(tc->td, &mapped); + if (r) + return r; + + r = dm_thin_get_highest_mapped_block(tc->td, &highest); + if (r < 0) + return r; + + DMEMIT("%llu ", mapped * tc->pool->sectors_per_block); + if (r) + DMEMIT("%llu", ((highest + 1) * + tc->pool->sectors_per_block) - 1); + else + DMEMIT("-"); + break; + + case STATUSTYPE_TABLE: + DMEMIT("%s %lu", + format_dev_t(buf, tc->pool_dev->bdev->bd_dev), + (unsigned long) tc->dev_id); + break; + } + } + + return 0; +} + +static int thin_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + dm_block_t blocks; + struct thin_c *tc = ti->private; + + /* + * We can't call dm_pool_get_data_dev_size() since that blocks. So + * we follow a more convoluted path through to the pool's target. + */ + if (!tc->pool->ti) + return 0; /* nothing is bound */ + + blocks = tc->pool->ti->len >> tc->pool->block_shift; + if (blocks) + return fn(ti, tc->pool_dev, 0, tc->pool->sectors_per_block * blocks, data); + + return 0; +} + +static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits) +{ + struct thin_c *tc = ti->private; + + blk_limits_io_min(limits, 0); + blk_limits_io_opt(limits, tc->pool->sectors_per_block << SECTOR_SHIFT); +} + +static struct target_type thin_target = { + .name = "thin", + .version = {1, 0, 0}, + .module = THIS_MODULE, + .ctr = thin_ctr, + .dtr = thin_dtr, + .map = thin_map, + .postsuspend = thin_postsuspend, + .status = thin_status, + .iterate_devices = thin_iterate_devices, + .io_hints = thin_io_hints, +}; + +/*----------------------------------------------------------------*/ + +static int __init dm_thin_init(void) +{ + int r; + + pool_table_init(); + + r = dm_register_target(&thin_target); + if (r) + return r; + + r = dm_register_target(&pool_target); + if (r) + dm_unregister_target(&thin_target); + + return r; +} + +static void dm_thin_exit(void) +{ + dm_unregister_target(&thin_target); + dm_unregister_target(&pool_target); +} + +module_init(dm_thin_init); +module_exit(dm_thin_exit); + +MODULE_DESCRIPTION(DM_NAME "device-mapper thin provisioning target"); +MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); +MODULE_LICENSE("GPL"); |
