- 根目录:
- drivers
- md
- dm-thin.c
/*
* 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 1024
#define DEFERRED_SET_SIZE 64
#define MAPPING_POOL_SIZE 1024
#define PRISON_CELLS 1024
#define COMMIT_PERIOD HZ
/*
* 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)
/*
* 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_mapping). 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;
struct bio *holder;
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 1 if the cell was already held, 0 if @inmate is the new holder.
*/
static int bio_detain(struct bio_prison *prison, struct cell_key *key,
struct bio *inmate, struct cell **ref)
{
int r = 1;
unsigned long flags;
uint32_t hash = hash_key(prison, key);
struct cell *cell, *cell2;
BUG_ON(hash > prison->nr_buckets);
spin_lock_irqsave(&prison->lock, flags);
cell = __search_bucket(prison->cells + hash, key);
if (cell) {
bio_list_add(&cell->bios, inmate);
goto out;
}
/*
* 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) {
mempool_free(cell2, prison->cell_pool);
bio_list_add(&cell->bios, inmate);
goto out;
}
/*
* Use new cell.
*/
cell = cell2;
cell->prison = prison;
memcpy(&cell->key, key, sizeof(cell->key));
cell->holder = inmate;
bio_list_init(&cell->bios);
hlist_add_head(&cell->list, prison->cells + hash);
r = 0;
out:
spin_unlock_irqrestore(&prison->lock, flags);
*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_add(inmates, cell->holder);
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)
{
BUG_ON(cell->holder != bio);
BUG_ON(!bio_list_empty(&cell->bios));
__cell_release(cell, NULL);
}
static void cell_release_singleton(struct cell *cell, struct bio *bio)
{
unsigned long flags;
struct bio_prison *prison = cell->prison;
spin_lock_irqsave(&prison->lock, flags);
__cell_release_singleton(cell, bio);
spin_unlock_irqrestore(&prison->lock, flags);
}
/*
* Sometimes we don't want the holder, just the additional bios.
*/
static void __cell_release_no_holder(struct cell *cell, struct bio_list *inmates)
{
struct bio_prison *prison = cell->prison;
hlist_del(&cell->list);
bio_list_merge(inmates, &cell->bios);
mempool_free(cell, prison->cell_pool);
}
static void cell_release_no_holder(struct cell *cell, struct bio_list *inmates)
{
unsigned long flags;
struct bio_prison *prison = cell->prison;
spin_lock_irqsave(&prison->lock, flags);
__cell_release_no_holder(cell, inmates);
spin_unlock_irqrestore(&prison->lock, flags);
}
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_features {
unsigned zero_new_blocks:1;
unsigned discard_enabled:1;
unsigned discard_passdown:1;
};
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;
struct pool_features pf;
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;
struct delayed_work waker;
unsigned ref_count;
unsigned long last_commit_jiffies;
spinlock_t lock;
struct bio_list deferred_bios;
struct bio_list deferred_flush_bios;
struct list_head prepared_mappings;
struct list_head prepared_discards;
struct bio_list retry_on_resume_list;
struct deferred_set shared_read_ds;
struct deferred_set all_io_ds;
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;
struct pool_features pf;
};
/*
* Target context for a thin.
*/
struct thin_c {
struct dm_dev *pool_dev;
struct dm_dev *origin_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;
}
/*----------------------------------------------------------------*/
struct endio_hook {
struct thin_c *tc;
struct deferred_entry *shared_read_entry;
struct deferred_entry *all_io_entry;
struct new_mapping *overwrite_mapping;
};
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))) {
struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
if (h->tc == 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_to_origin(struct thin_c *tc, struct bio *bio)
{
bio->bi_bdev = tc->origin_dev->bdev;
}
static void issue(struct thin_c *tc, struct bio *bio)
{
struct pool *pool = tc->pool;
unsigned long flags;
/*
* 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);
}
static void remap_to_origin_and_issue(struct thin_c *tc, struct bio *bio)
{
remap_to_origin(tc, bio);
issue(tc, bio);
}
static void remap_and_issue(struct thin_c *tc, struct bio *bio,
dm_block_t block)
{
remap(tc, bio, block);
issue(tc, 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 new_mapping {
struct list_head list;
unsigned quiesced:1;
unsigned prepared:1;
unsigned pass_discard:1;
struct thin_c *tc;
dm_block_t virt_block;
dm_block_t data_block;
struct cell *cell, *cell2;
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 (m->quiesced && 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 endio_hook *h = dm_get_mapinfo(bio)->ptr;
struct new_mapping *m = h->overwrite_mapping;
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);
}
/*----------------------------------------------------------------*/
/*
* 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_list bios;
struct pool *pool = tc->pool;
unsigned long flags;
bio_list_init(&bios);
spin_lock_irqsave(&pool->lock, flags);
cell_release_no_holder(cell, &pool->deferred_bios);
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);
goto out;
}
/*
* 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);
goto out;
}
/*
* 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_endio(bio, 0);
} else
cell_defer(tc, m->cell, m->data_block);
out:
list_del(&m->list);
mempool_free(m, tc->pool->mapping_pool);
}
static void process_prepared_discard(struct new_mapping *m)
{
int r;
struct thin_c *tc = m->tc;
r = dm_thin_remove_block(tc->td, m->virt_block);
if (r)
DMERR("dm_thin_remove_block() failed");
/*
* Pass the discard down to the underlying device?
*/
if (m->pass_discard)
remap_and_issue(tc, m->bio, m->data_block);
else
bio_endio(m->bio, 0);
cell_defer_except(tc, m->cell);
cell_defer_except(tc, m->cell2);
mempool_free(m, tc->pool->mapping_pool);
}
static void process_prepared(struct pool *pool, struct list_head *head,
void (*fn)(struct new_mapping *))
{
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(head, &maps);
spin_unlock_irqrestore(&pool->lock, flags);
list_for_each_entry_safe(m, tmp, &maps, list)
fn(m);
}
/*
* Deferred bio jobs.
*/
static int io_overlaps_block(struct pool *pool, struct bio *bio)
{
return !(bio->bi_sector & pool->offset_mask) &&
(bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT));
}
static int io_overwrites_block(struct pool *pool, struct bio *bio)
{
return (bio_data_dir(bio) == WRITE) &&
io_overlaps_block(pool, bio);
}
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,
struct dm_dev *origin, 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->quiesced = 0;
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;
if (!ds_add_work(&pool->shared_read_ds, &m->list))
m->quiesced = 1;
/*
* 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)) {
struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
h->overwrite_mapping = m;
m->bio = bio;
save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
remap_and_issue(tc, bio, data_dest);
} else {
struct dm_io_region from, to;
from.bdev = origin->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_internal_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)
{
schedule_copy(tc, virt_block, tc->pool_dev,
data_origin, data_dest, cell, bio);
}
static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,
dm_block_t data_dest,
struct cell *cell, struct bio *bio)
{
schedule_copy(tc, virt_block, tc->origin_dev,
virt_block, data_dest, cell, bio);
}
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->quiesced = 1;
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->pf.zero_new_blocks)
process_prepared_mapping(m);
else if (io_overwrites_block(pool, bio)) {
struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
h->overwrite_mapping = m;
m->bio = bio;
save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
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 endio_hook *h = dm_get_mapinfo(bio)->ptr;
struct thin_c *tc = h->tc;
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 process_discard(struct thin_c *tc, struct bio *bio)
{
int r;
unsigned long flags;
struct pool *pool = tc->pool;
struct cell *cell, *cell2;
struct cell_key key, key2;
dm_block_t block = get_bio_block(tc, bio);
struct dm_thin_lookup_result lookup_result;
struct new_mapping *m;
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:
/*
* Check nobody is fiddling with this pool block. This can
* happen if someone's in the process of breaking sharing
* on this block.
*/
build_data_key(tc->td, lookup_result.block, &key2);
if (bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
cell_release_singleton(cell, bio);
break;
}
if (io_overlaps_block(pool, bio)) {
/*
* IO may still be going to the destination block. We must
* quiesce before we can do the removal.
*/
m = get_next_mapping(pool);
m->tc = tc;
m->pass_discard = (!lookup_result.shared) & pool->pf.discard_passdown;
m->virt_block = block;
m->data_block = lookup_result.block;
m->cell = cell;
m->cell2 = cell2;
m->err = 0;
m->bio = bio;
if (!ds_add_work(&pool->all_io_ds, &m->list)) {
spin_lock_irqsave(&pool->lock, flags);
list_add(&m->list, &pool->prepared_discards);
spin_unlock_irqrestore(&pool->lock, flags);
wake_worker(pool);
}
} else {
/*
* This path is hit if people are ignoring
* limits->discard_granularity. It ignores any
* part of the discard that is in a subsequent
* block.
*/
sector_t offset = bio->bi_sector - (block << pool->block_shift);
unsigned remaining = (pool->sectors_per_block - offset) << 9;
bio->bi_size = min(bio->bi_size, remaining);
cell_release_singleton(cell, bio);
cell_release_singleton(cell2, bio);
if ((!lookup_result.shared) && pool->pf.discard_passdown)
remap_and_issue(tc, bio, lookup_result.block);
else
bio_endio(bio, 0);
}
break;
case -ENODATA:
/*
* It isn't provisioned, just forget it.
*/
cell_release_singleton(cell, bio);
bio_endio(bio, 0);
break;
default:
DMERR("discard: find block unexpectedly returned %d", r);
cell_release_singleton(cell, bio);
bio_io_error(bio);
break;
}
}
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_internal_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 = dm_get_mapinfo(bio)->ptr;
h->shared_read_entry = ds_inc(&pool->shared_read_ds);
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:
if (tc->origin_dev)
schedule_external_copy(tc, block, data_block, cell, bio);
else
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:
if (bio_data_dir(bio) == READ && tc->origin_dev) {
cell_release_singleton(cell, bio);
remap_to_origin_and_issue(tc, bio);
} else
provision_block(tc, bio, block, cell);
break;
default:
DMERR("dm_thin_find_block() failed, error = %d", r);
cell_release_singleton(cell, bio);
bio_io_error(bio);
break;
}
}
static int need_commit_due_to_time(struct pool *pool)
{
return jiffies < pool->last_commit_jiffies ||
jiffies > pool->last_commit_jiffies + COMMIT_PERIOD;
}
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 endio_hook *h = dm_get_mapinfo(bio)->ptr;
struct thin_c *tc = h->tc;
/*
* 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;
}
if (bio->bi_rw & REQ_DISCARD)
process_discard(tc, bio);
else
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) && !need_commit_due_to_time(pool))
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;
}
pool->last_commit_jiffies = jiffies;
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(pool, &pool->prepared_mappings, process_prepared_mapping);
process_prepared(pool, &pool->prepared_discards, process_prepared_discard);
process_deferred_bios(pool);
}
/*
* We want to commit periodically so that not too much
* unwritten data builds up.
*/
static void do_waker(struct work_struct *ws)
{
struct pool *pool = container_of(to_delayed_work(ws), struct pool, waker);
wake_worker(pool);
queue_delayed_work(pool->wq, &pool->waker, COMMIT_PERIOD);
}
/*----------------------------------------------------------------*/
/*
* 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);
}
static struct endio_hook *thin_hook_bio(struct thin_c *tc, struct bio *bio)
{
struct pool *pool = tc->pool;
struct endio_hook *h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);
h->tc = tc;
h->shared_read_entry = NULL;
h->all_io_entry = bio->bi_rw & REQ_DISCARD ? NULL : ds_inc(&pool->all_io_ds);
h->overwrite_mapping = NULL;
return h;
}
/*
* 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;
map_context->ptr = thin_hook_bio(tc, bio);
if (bio->bi_rw & (REQ_DISCARD | 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->pf = pt->pf;
/*
* If discard_passdown was enabled verify that the data device
* supports discards. Disable discard_passdown if not; otherwise
* -EOPNOTSUPP will be returned.
*/
if (pt->pf.discard_passdown) {
struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
if (!q || !blk_queue_discard(q)) {
char buf[BDEVNAME_SIZE];
DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",
bdevname(pt->data_dev->bdev, buf));
pool->pf.discard_passdown = 0;
}
}
return 0;
}
static void unbind_control_target(struct pool *pool, struct dm_target *ti)
{
if (pool->ti == ti)
pool->ti = NULL;
}
/*----------------------------------------------------------------
* Pool creation
*--------------------------------------------------------------*/
/* Initialize pool features. */
static void pool_features_init(struct pool_features *pf)
{
pf->zero_new_blocks = 1;
pf->discard_enabled = 1;
pf->discard_passdown = 1;
}
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_features_init(&pool->pf);
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);
INIT_DELAYED_WORK(&pool->waker, do_waker);
spin_lock_init(&pool->lock);
bio_list_init(&pool->deferred_bios);
bio_list_init(&pool->deferred_flush_bios);
INIT_LIST_HEAD(&pool->prepared_mappings);
INIT_LIST_HEAD(&pool->prepared_discards);
pool->low_water_triggered = 0;
pool->no_free_space = 0;
bio_list_init(&pool->retry_on_resume_list);
ds_init(&pool->shared_read_ds);
ds_init(&pool->all_io_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->last_commit_jiffies = jiffies;
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,
int *created)
{
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);
*created = 1;
}
}
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);
}
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, 3, "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;
} else if (!strcasecmp(arg_name, "ignore_discard")) {
pf->discard_enabled = 0;
continue;
} else if (!strcasecmp(arg_name, "no_discard_passdown")) {
pf->discard_passdown = 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.
* ignore_discard: disable discard
* no_discard_passdown: don't pass discards down to the data device
*/
static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
int r, pool_created = 0;
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;
char b[BDEVNAME_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 > THIN_METADATA_MAX_SECTORS_WARNING)
DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
bdevname(metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
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.
*/
pool_features_init(&pf);
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, &pool_created);
if (IS_ERR(pool)) {
r = PTR_ERR(pool);
goto out_free_pt;
}
/*
* 'pool_created' reflects whether this is the first table load.
* Top level discard support is not allowed to be changed after
* initial load. This would require a pool reload to trigger thin
* device changes.
*/
if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
ti->error = "Discard support cannot be disabled once enabled";
r = -EINVAL;
goto out_flags_changed;
}
pt->pool = pool;
pt->ti = ti;
pt->metadata_dev = metadata_dev;
pt->data_dev = data_dev;
pt->low_water_blocks = low_water_blocks;
pt->pf = pf;
ti->num_flush_requests = 1;
/*
* Only need to enable discards if the pool should pass
* them down to the data device. The thin device's discard
* processing will cause mappings to be removed from the btree.
*/
if (pf.discard_enabled && pf.discard_passdown) {
ti->num_discard_requests = 1;
/*
* Setting 'discards_supported' circumvents the normal
* stacking of discard limits (this keeps the pool and
* thin devices' discard limits consistent).
*/
ti->discards_supported = 1;
ti->discard_zeroes_data_unsupported = 1;
}
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_flags_changed:
__pool_dec(pool);
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);
do_waker(&pool->waker.work);
}
static void pool_postsuspend(struct dm_target *ti)
{
int r;
struct pool_c *pt = ti->private;
struct pool *pool = pt->pool;
cancel_delayed_work(&pool->waker);
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, count;
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);
count = !pool->pf.zero_new_blocks + !pool->pf.discard_enabled +
!pt->pf.discard_passdown;
DMEMIT("%u ", count);
if (!pool->pf.zero_new_blocks)
DMEMIT("skip_block_zeroing ");
if (!pool->pf.discard_enabled)
DMEMIT("ignore_discard ");
if (!pt->pf.discard_passdown)
DMEMIT("no_discard_passdown ");
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 set_discard_limits(struct pool *pool, struct queue_limits *limits)
{
/*
* FIXME: these limits may be incompatible with the pool's data device
*/
limits->max_discard_sectors = pool->sectors_per_block;
/*
* This is just a hint, and not enforced. We have to cope with
* bios that overlap 2 blocks.
*/
limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
}
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);
if (pool->pf.discard_enabled)
set_discard_limits(pool, limits);
}
static struct target_type pool_target = {
.name = "thin-pool",
.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
DM_TARGET_IMMUTABLE,
.version = {1, 1, 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);
if (tc->origin_dev)
dm_put_device(ti, tc->origin_dev);
kfree(tc);
mutex_unlock(&dm_thin_pool_table.mutex);
}
/*
* Thin target parameters:
*
* <pool_dev> <dev_id> [origin_dev]
*
* pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
* dev_id: the internal device identifier
* origin_dev: a device external to the pool that should act as the origin
*
* If the pool device has discards disabled, they get disabled for the thin
* device as well.
*/
static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
int r;
struct thin_c *tc;
struct dm_dev *pool_dev, *origin_dev;
struct mapped_device *pool_md;
mutex_lock(&dm_thin_pool_table.mutex);
if (argc != 2 && argc != 3) {
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;
}
if (argc == 3) {
r = dm_get_device(ti, argv[2], FMODE_READ, &origin_dev);
if (r) {
ti->error = "Error opening origin device";
goto bad_origin_dev;
}
tc->origin_dev = origin_dev;
}
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;
/* In case the pool supports discards, pass them on. */
if (tc->pool->pf.discard_enabled) {
ti->discards_supported = 1;
ti->num_discard_requests = 1;
ti->discard_zeroes_data_unsupported = 1;
}
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:
if (tc->origin_dev)
dm_put_device(ti, tc->origin_dev);
bad_origin_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 = dm_target_offset(ti, bio->bi_sector);
return thin_bio_map(ti, bio, map_context);
}
static int thin_endio(struct dm_target *ti,
struct bio *bio, int err,
union map_info *map_context)
{
unsigned long flags;
struct endio_hook *h = map_context->ptr;
struct list_head work;
struct new_mapping *m, *tmp;
struct pool *pool = h->tc->pool;
if (h->shared_read_entry) {
INIT_LIST_HEAD(&work);
ds_dec(h->shared_read_entry, &work);
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry_safe(m, tmp, &work, list) {
list_del(&m->list);
m->quiesced = 1;
__maybe_add_mapping(m);
}
spin_unlock_irqrestore(&pool->lock, flags);
}
if (h->all_io_entry) {
INIT_LIST_HEAD(&work);
ds_dec(h->all_io_entry, &work);
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry_safe(m, tmp, &work, list)
list_add(&m->list, &pool->prepared_discards);
spin_unlock_irqrestore(&pool->lock, flags);
}
mempool_free(h, pool->endio_hook_pool);
return 0;
}
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);
if (tc->origin_dev)
DMEMIT(" %s", format_dev_t(buf, tc->origin_dev->bdev->bd_dev));
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;
struct pool *pool = tc->pool;
blk_limits_io_min(limits, 0);
blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
set_discard_limits(pool, limits);
}
static struct target_type thin_target = {
.name = "thin",
.version = {1, 1, 0},
.module = THIS_MODULE,
.ctr = thin_ctr,
.dtr = thin_dtr,
.map = thin_map,
.end_io = thin_endio,
.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 " thin provisioning target");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");