diff options
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 2780 |
1 files changed, 2780 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c new file mode 100644 index 00000000..e24143cc --- /dev/null +++ b/drivers/md/dm.c @@ -0,0 +1,2780 @@ +/* + * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. + * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved. + * + * This file is released under the GPL. + */ + +#include "dm.h" +#include "dm-uevent.h" + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/moduleparam.h> +#include <linux/blkpg.h> +#include <linux/bio.h> +#include <linux/mempool.h> +#include <linux/slab.h> +#include <linux/idr.h> +#include <linux/hdreg.h> +#include <linux/delay.h> + +#include <trace/events/block.h> + +#define DM_MSG_PREFIX "core" + +#ifdef CONFIG_PRINTK +/* + * ratelimit state to be used in DMXXX_LIMIT(). + */ +DEFINE_RATELIMIT_STATE(dm_ratelimit_state, + DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); +EXPORT_SYMBOL(dm_ratelimit_state); +#endif + +/* + * Cookies are numeric values sent with CHANGE and REMOVE + * uevents while resuming, removing or renaming the device. + */ +#define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE" +#define DM_COOKIE_LENGTH 24 + +static const char *_name = DM_NAME; + +static unsigned int major = 0; +static unsigned int _major = 0; + +static DEFINE_IDR(_minor_idr); + +static DEFINE_SPINLOCK(_minor_lock); +/* + * For bio-based dm. + * One of these is allocated per bio. + */ +struct dm_io { + struct mapped_device *md; + int error; + atomic_t io_count; + struct bio *bio; + unsigned long start_time; + spinlock_t endio_lock; +}; + +/* + * For bio-based dm. + * One of these is allocated per target within a bio. Hopefully + * this will be simplified out one day. + */ +struct dm_target_io { + struct dm_io *io; + struct dm_target *ti; + union map_info info; +}; + +/* + * For request-based dm. + * One of these is allocated per request. + */ +struct dm_rq_target_io { + struct mapped_device *md; + struct dm_target *ti; + struct request *orig, clone; + int error; + union map_info info; +}; + +/* + * For request-based dm. + * One of these is allocated per bio. + */ +struct dm_rq_clone_bio_info { + struct bio *orig; + struct dm_rq_target_io *tio; +}; + +union map_info *dm_get_mapinfo(struct bio *bio) +{ + if (bio && bio->bi_private) + return &((struct dm_target_io *)bio->bi_private)->info; + return NULL; +} + +union map_info *dm_get_rq_mapinfo(struct request *rq) +{ + if (rq && rq->end_io_data) + return &((struct dm_rq_target_io *)rq->end_io_data)->info; + return NULL; +} +EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo); + +#define MINOR_ALLOCED ((void *)-1) + +/* + * Bits for the md->flags field. + */ +#define DMF_BLOCK_IO_FOR_SUSPEND 0 +#define DMF_SUSPENDED 1 +#define DMF_FROZEN 2 +#define DMF_FREEING 3 +#define DMF_DELETING 4 +#define DMF_NOFLUSH_SUSPENDING 5 +#define DMF_MERGE_IS_OPTIONAL 6 + +/* + * Work processed by per-device workqueue. + */ +struct mapped_device { + struct rw_semaphore io_lock; + struct mutex suspend_lock; + rwlock_t map_lock; + atomic_t holders; + atomic_t open_count; + + unsigned long flags; + + struct request_queue *queue; + unsigned type; + /* Protect queue and type against concurrent access. */ + struct mutex type_lock; + + struct target_type *immutable_target_type; + + struct gendisk *disk; + char name[16]; + + void *interface_ptr; + + /* + * A list of ios that arrived while we were suspended. + */ + atomic_t pending[2]; + wait_queue_head_t wait; + struct work_struct work; + struct bio_list deferred; + spinlock_t deferred_lock; + + /* + * Processing queue (flush) + */ + struct workqueue_struct *wq; + + /* + * The current mapping. + */ + struct dm_table *map; + + /* + * io objects are allocated from here. + */ + mempool_t *io_pool; + mempool_t *tio_pool; + + struct bio_set *bs; + + /* + * Event handling. + */ + atomic_t event_nr; + wait_queue_head_t eventq; + atomic_t uevent_seq; + struct list_head uevent_list; + spinlock_t uevent_lock; /* Protect access to uevent_list */ + + /* + * freeze/thaw support require holding onto a super block + */ + struct super_block *frozen_sb; + struct block_device *bdev; + + /* forced geometry settings */ + struct hd_geometry geometry; + + /* sysfs handle */ + struct kobject kobj; + + /* zero-length flush that will be cloned and submitted to targets */ + struct bio flush_bio; +}; + +/* + * For mempools pre-allocation at the table loading time. + */ +struct dm_md_mempools { + mempool_t *io_pool; + mempool_t *tio_pool; + struct bio_set *bs; +}; + +#define MIN_IOS 256 +static struct kmem_cache *_io_cache; +static struct kmem_cache *_tio_cache; +static struct kmem_cache *_rq_tio_cache; +static struct kmem_cache *_rq_bio_info_cache; + +static int __init local_init(void) +{ + int r = -ENOMEM; + + /* allocate a slab for the dm_ios */ + _io_cache = KMEM_CACHE(dm_io, 0); + if (!_io_cache) + return r; + + /* allocate a slab for the target ios */ + _tio_cache = KMEM_CACHE(dm_target_io, 0); + if (!_tio_cache) + goto out_free_io_cache; + + _rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0); + if (!_rq_tio_cache) + goto out_free_tio_cache; + + _rq_bio_info_cache = KMEM_CACHE(dm_rq_clone_bio_info, 0); + if (!_rq_bio_info_cache) + goto out_free_rq_tio_cache; + + r = dm_uevent_init(); + if (r) + goto out_free_rq_bio_info_cache; + + _major = major; + r = register_blkdev(_major, _name); + if (r < 0) + goto out_uevent_exit; + + if (!_major) + _major = r; + + return 0; + +out_uevent_exit: + dm_uevent_exit(); +out_free_rq_bio_info_cache: + kmem_cache_destroy(_rq_bio_info_cache); +out_free_rq_tio_cache: + kmem_cache_destroy(_rq_tio_cache); +out_free_tio_cache: + kmem_cache_destroy(_tio_cache); +out_free_io_cache: + kmem_cache_destroy(_io_cache); + + return r; +} + +static void local_exit(void) +{ + kmem_cache_destroy(_rq_bio_info_cache); + kmem_cache_destroy(_rq_tio_cache); + kmem_cache_destroy(_tio_cache); + kmem_cache_destroy(_io_cache); + unregister_blkdev(_major, _name); + dm_uevent_exit(); + + _major = 0; + + DMINFO("cleaned up"); +} + +static int (*_inits[])(void) __initdata = { + local_init, + dm_target_init, + dm_linear_init, + dm_stripe_init, + dm_io_init, + dm_kcopyd_init, + dm_interface_init, +}; + +static void (*_exits[])(void) = { + local_exit, + dm_target_exit, + dm_linear_exit, + dm_stripe_exit, + dm_io_exit, + dm_kcopyd_exit, + dm_interface_exit, +}; + +static int __init dm_init(void) +{ + const int count = ARRAY_SIZE(_inits); + + int r, i; + + for (i = 0; i < count; i++) { + r = _inits[i](); + if (r) + goto bad; + } + + return 0; + + bad: + while (i--) + _exits[i](); + + return r; +} + +static void __exit dm_exit(void) +{ + int i = ARRAY_SIZE(_exits); + + while (i--) + _exits[i](); + + /* + * Should be empty by this point. + */ + idr_remove_all(&_minor_idr); + idr_destroy(&_minor_idr); +} + +/* + * Block device functions + */ +int dm_deleting_md(struct mapped_device *md) +{ + return test_bit(DMF_DELETING, &md->flags); +} + +static int dm_blk_open(struct block_device *bdev, fmode_t mode) +{ + struct mapped_device *md; + + spin_lock(&_minor_lock); + + md = bdev->bd_disk->private_data; + if (!md) + goto out; + + if (test_bit(DMF_FREEING, &md->flags) || + dm_deleting_md(md)) { + md = NULL; + goto out; + } + + dm_get(md); + atomic_inc(&md->open_count); + +out: + spin_unlock(&_minor_lock); + + return md ? 0 : -ENXIO; +} + +static int dm_blk_close(struct gendisk *disk, fmode_t mode) +{ + struct mapped_device *md = disk->private_data; + + spin_lock(&_minor_lock); + + atomic_dec(&md->open_count); + dm_put(md); + + spin_unlock(&_minor_lock); + + return 0; +} + +int dm_open_count(struct mapped_device *md) +{ + return atomic_read(&md->open_count); +} + +/* + * Guarantees nothing is using the device before it's deleted. + */ +int dm_lock_for_deletion(struct mapped_device *md) +{ + int r = 0; + + spin_lock(&_minor_lock); + + if (dm_open_count(md)) + r = -EBUSY; + else + set_bit(DMF_DELETING, &md->flags); + + spin_unlock(&_minor_lock); + + return r; +} + +static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo) +{ + struct mapped_device *md = bdev->bd_disk->private_data; + + return dm_get_geometry(md, geo); +} + +static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode, + unsigned int cmd, unsigned long arg) +{ + struct mapped_device *md = bdev->bd_disk->private_data; + struct dm_table *map = dm_get_live_table(md); + struct dm_target *tgt; + int r = -ENOTTY; + + if (!map || !dm_table_get_size(map)) + goto out; + + /* We only support devices that have a single target */ + if (dm_table_get_num_targets(map) != 1) + goto out; + + tgt = dm_table_get_target(map, 0); + + if (dm_suspended_md(md)) { + r = -EAGAIN; + goto out; + } + + if (tgt->type->ioctl) + r = tgt->type->ioctl(tgt, cmd, arg); + +out: + dm_table_put(map); + + return r; +} + +static struct dm_io *alloc_io(struct mapped_device *md) +{ + return mempool_alloc(md->io_pool, GFP_NOIO); +} + +static void free_io(struct mapped_device *md, struct dm_io *io) +{ + mempool_free(io, md->io_pool); +} + +static void free_tio(struct mapped_device *md, struct dm_target_io *tio) +{ + mempool_free(tio, md->tio_pool); +} + +static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md, + gfp_t gfp_mask) +{ + return mempool_alloc(md->tio_pool, gfp_mask); +} + +static void free_rq_tio(struct dm_rq_target_io *tio) +{ + mempool_free(tio, tio->md->tio_pool); +} + +static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md) +{ + return mempool_alloc(md->io_pool, GFP_ATOMIC); +} + +static void free_bio_info(struct dm_rq_clone_bio_info *info) +{ + mempool_free(info, info->tio->md->io_pool); +} + +static int md_in_flight(struct mapped_device *md) +{ + return atomic_read(&md->pending[READ]) + + atomic_read(&md->pending[WRITE]); +} + +static void start_io_acct(struct dm_io *io) +{ + struct mapped_device *md = io->md; + int cpu; + int rw = bio_data_dir(io->bio); + + io->start_time = jiffies; + + cpu = part_stat_lock(); + part_round_stats(cpu, &dm_disk(md)->part0); + part_stat_unlock(); + atomic_set(&dm_disk(md)->part0.in_flight[rw], + atomic_inc_return(&md->pending[rw])); +} + +static void end_io_acct(struct dm_io *io) +{ + struct mapped_device *md = io->md; + struct bio *bio = io->bio; + unsigned long duration = jiffies - io->start_time; + int pending, cpu; + int rw = bio_data_dir(bio); + + cpu = part_stat_lock(); + part_round_stats(cpu, &dm_disk(md)->part0); + part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration); + part_stat_unlock(); + + /* + * After this is decremented the bio must not be touched if it is + * a flush. + */ + pending = atomic_dec_return(&md->pending[rw]); + atomic_set(&dm_disk(md)->part0.in_flight[rw], pending); + pending += atomic_read(&md->pending[rw^0x1]); + + /* nudge anyone waiting on suspend queue */ + if (!pending) + wake_up(&md->wait); +} + +/* + * Add the bio to the list of deferred io. + */ +static void queue_io(struct mapped_device *md, struct bio *bio) +{ + unsigned long flags; + + spin_lock_irqsave(&md->deferred_lock, flags); + bio_list_add(&md->deferred, bio); + spin_unlock_irqrestore(&md->deferred_lock, flags); + queue_work(md->wq, &md->work); +} + +/* + * Everyone (including functions in this file), should use this + * function to access the md->map field, and make sure they call + * dm_table_put() when finished. + */ +struct dm_table *dm_get_live_table(struct mapped_device *md) +{ + struct dm_table *t; + unsigned long flags; + + read_lock_irqsave(&md->map_lock, flags); + t = md->map; + if (t) + dm_table_get(t); + read_unlock_irqrestore(&md->map_lock, flags); + + return t; +} + +/* + * Get the geometry associated with a dm device + */ +int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo) +{ + *geo = md->geometry; + + return 0; +} + +/* + * Set the geometry of a device. + */ +int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo) +{ + sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors; + + if (geo->start > sz) { + DMWARN("Start sector is beyond the geometry limits."); + return -EINVAL; + } + + md->geometry = *geo; + + return 0; +} + +/*----------------------------------------------------------------- + * CRUD START: + * A more elegant soln is in the works that uses the queue + * merge fn, unfortunately there are a couple of changes to + * the block layer that I want to make for this. So in the + * interests of getting something for people to use I give + * you this clearly demarcated crap. + *---------------------------------------------------------------*/ + +static int __noflush_suspending(struct mapped_device *md) +{ + return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); +} + +/* + * Decrements the number of outstanding ios that a bio has been + * cloned into, completing the original io if necc. + */ +static void dec_pending(struct dm_io *io, int error) +{ + unsigned long flags; + int io_error; + struct bio *bio; + struct mapped_device *md = io->md; + + /* Push-back supersedes any I/O errors */ + if (unlikely(error)) { + spin_lock_irqsave(&io->endio_lock, flags); + if (!(io->error > 0 && __noflush_suspending(md))) + io->error = error; + spin_unlock_irqrestore(&io->endio_lock, flags); + } + + if (atomic_dec_and_test(&io->io_count)) { + if (io->error == DM_ENDIO_REQUEUE) { + /* + * Target requested pushing back the I/O. + */ + spin_lock_irqsave(&md->deferred_lock, flags); + if (__noflush_suspending(md)) + bio_list_add_head(&md->deferred, io->bio); + else + /* noflush suspend was interrupted. */ + io->error = -EIO; + spin_unlock_irqrestore(&md->deferred_lock, flags); + } + + io_error = io->error; + bio = io->bio; + end_io_acct(io); + free_io(md, io); + + if (io_error == DM_ENDIO_REQUEUE) + return; + + if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) { + /* + * Preflush done for flush with data, reissue + * without REQ_FLUSH. + */ + bio->bi_rw &= ~REQ_FLUSH; + queue_io(md, bio); + } else { + /* done with normal IO or empty flush */ + trace_block_bio_complete(md->queue, bio, io_error); + bio_endio(bio, io_error); + } + } +} + +static void clone_endio(struct bio *bio, int error) +{ + int r = 0; + struct dm_target_io *tio = bio->bi_private; + struct dm_io *io = tio->io; + struct mapped_device *md = tio->io->md; + dm_endio_fn endio = tio->ti->type->end_io; + + if (!bio_flagged(bio, BIO_UPTODATE) && !error) + error = -EIO; + + if (endio) { + r = endio(tio->ti, bio, error, &tio->info); + if (r < 0 || r == DM_ENDIO_REQUEUE) + /* + * error and requeue request are handled + * in dec_pending(). + */ + error = r; + else if (r == DM_ENDIO_INCOMPLETE) + /* The target will handle the io */ + return; + else if (r) { + DMWARN("unimplemented target endio return value: %d", r); + BUG(); + } + } + + /* + * Store md for cleanup instead of tio which is about to get freed. + */ + bio->bi_private = md->bs; + + free_tio(md, tio); + bio_put(bio); + dec_pending(io, error); +} + +/* + * Partial completion handling for request-based dm + */ +static void end_clone_bio(struct bio *clone, int error) +{ + struct dm_rq_clone_bio_info *info = clone->bi_private; + struct dm_rq_target_io *tio = info->tio; + struct bio *bio = info->orig; + unsigned int nr_bytes = info->orig->bi_size; + + bio_put(clone); + + if (tio->error) + /* + * An error has already been detected on the request. + * Once error occurred, just let clone->end_io() handle + * the remainder. + */ + return; + else if (error) { + /* + * Don't notice the error to the upper layer yet. + * The error handling decision is made by the target driver, + * when the request is completed. + */ + tio->error = error; + return; + } + + /* + * I/O for the bio successfully completed. + * Notice the data completion to the upper layer. + */ + + /* + * bios are processed from the head of the list. + * So the completing bio should always be rq->bio. + * If it's not, something wrong is happening. + */ + if (tio->orig->bio != bio) + DMERR("bio completion is going in the middle of the request"); + + /* + * Update the original request. + * Do not use blk_end_request() here, because it may complete + * the original request before the clone, and break the ordering. + */ + blk_update_request(tio->orig, 0, nr_bytes); +} + +/* + * Don't touch any member of the md after calling this function because + * the md may be freed in dm_put() at the end of this function. + * Or do dm_get() before calling this function and dm_put() later. + */ +static void rq_completed(struct mapped_device *md, int rw, int run_queue) +{ + atomic_dec(&md->pending[rw]); + + /* nudge anyone waiting on suspend queue */ + if (!md_in_flight(md)) + wake_up(&md->wait); + + if (run_queue) + blk_run_queue(md->queue); + + /* + * dm_put() must be at the end of this function. See the comment above + */ + dm_put(md); +} + +static void free_rq_clone(struct request *clone) +{ + struct dm_rq_target_io *tio = clone->end_io_data; + + blk_rq_unprep_clone(clone); + free_rq_tio(tio); +} + +/* + * Complete the clone and the original request. + * Must be called without queue lock. + */ +static void dm_end_request(struct request *clone, int error) +{ + int rw = rq_data_dir(clone); + struct dm_rq_target_io *tio = clone->end_io_data; + struct mapped_device *md = tio->md; + struct request *rq = tio->orig; + + if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { + rq->errors = clone->errors; + rq->resid_len = clone->resid_len; + + if (rq->sense) + /* + * We are using the sense buffer of the original + * request. + * So setting the length of the sense data is enough. + */ + rq->sense_len = clone->sense_len; + } + + free_rq_clone(clone); + blk_end_request_all(rq, error); + rq_completed(md, rw, true); +} + +static void dm_unprep_request(struct request *rq) +{ + struct request *clone = rq->special; + + rq->special = NULL; + rq->cmd_flags &= ~REQ_DONTPREP; + + free_rq_clone(clone); +} + +/* + * Requeue the original request of a clone. + */ +void dm_requeue_unmapped_request(struct request *clone) +{ + int rw = rq_data_dir(clone); + struct dm_rq_target_io *tio = clone->end_io_data; + struct mapped_device *md = tio->md; + struct request *rq = tio->orig; + struct request_queue *q = rq->q; + unsigned long flags; + + dm_unprep_request(rq); + + spin_lock_irqsave(q->queue_lock, flags); + blk_requeue_request(q, rq); + spin_unlock_irqrestore(q->queue_lock, flags); + + rq_completed(md, rw, 0); +} +EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request); + +static void __stop_queue(struct request_queue *q) +{ + blk_stop_queue(q); +} + +static void stop_queue(struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + __stop_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +static void __start_queue(struct request_queue *q) +{ + if (blk_queue_stopped(q)) + blk_start_queue(q); +} + +static void start_queue(struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + __start_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +static void dm_done(struct request *clone, int error, bool mapped) +{ + int r = error; + struct dm_rq_target_io *tio = clone->end_io_data; + dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io; + + if (mapped && rq_end_io) + r = rq_end_io(tio->ti, clone, error, &tio->info); + + if (r <= 0) + /* The target wants to complete the I/O */ + dm_end_request(clone, r); + else if (r == DM_ENDIO_INCOMPLETE) + /* The target will handle the I/O */ + return; + else if (r == DM_ENDIO_REQUEUE) + /* The target wants to requeue the I/O */ + dm_requeue_unmapped_request(clone); + else { + DMWARN("unimplemented target endio return value: %d", r); + BUG(); + } +} + +/* + * Request completion handler for request-based dm + */ +static void dm_softirq_done(struct request *rq) +{ + bool mapped = true; + struct request *clone = rq->completion_data; + struct dm_rq_target_io *tio = clone->end_io_data; + + if (rq->cmd_flags & REQ_FAILED) + mapped = false; + + dm_done(clone, tio->error, mapped); +} + +/* + * Complete the clone and the original request with the error status + * through softirq context. + */ +static void dm_complete_request(struct request *clone, int error) +{ + struct dm_rq_target_io *tio = clone->end_io_data; + struct request *rq = tio->orig; + + tio->error = error; + rq->completion_data = clone; + blk_complete_request(rq); +} + +/* + * Complete the not-mapped clone and the original request with the error status + * through softirq context. + * Target's rq_end_io() function isn't called. + * This may be used when the target's map_rq() function fails. + */ +void dm_kill_unmapped_request(struct request *clone, int error) +{ + struct dm_rq_target_io *tio = clone->end_io_data; + struct request *rq = tio->orig; + + rq->cmd_flags |= REQ_FAILED; + dm_complete_request(clone, error); +} +EXPORT_SYMBOL_GPL(dm_kill_unmapped_request); + +/* + * Called with the queue lock held + */ +static void end_clone_request(struct request *clone, int error) +{ + /* + * For just cleaning up the information of the queue in which + * the clone was dispatched. + * The clone is *NOT* freed actually here because it is alloced from + * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags. + */ + __blk_put_request(clone->q, clone); + + /* + * Actual request completion is done in a softirq context which doesn't + * hold the queue lock. Otherwise, deadlock could occur because: + * - another request may be submitted by the upper level driver + * of the stacking during the completion + * - the submission which requires queue lock may be done + * against this queue + */ + dm_complete_request(clone, error); +} + +/* + * Return maximum size of I/O possible at the supplied sector up to the current + * target boundary. + */ +static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti) +{ + sector_t target_offset = dm_target_offset(ti, sector); + + return ti->len - target_offset; +} + +static sector_t max_io_len(sector_t sector, struct dm_target *ti) +{ + sector_t len = max_io_len_target_boundary(sector, ti); + + /* + * Does the target need to split even further ? + */ + if (ti->split_io) { + sector_t boundary; + sector_t offset = dm_target_offset(ti, sector); + boundary = ((offset + ti->split_io) & ~(ti->split_io - 1)) + - offset; + if (len > boundary) + len = boundary; + } + + return len; +} + +static void __map_bio(struct dm_target *ti, struct bio *clone, + struct dm_target_io *tio) +{ + int r; + sector_t sector; + struct mapped_device *md; + + clone->bi_end_io = clone_endio; + clone->bi_private = tio; + + /* + * Map the clone. If r == 0 we don't need to do + * anything, the target has assumed ownership of + * this io. + */ + atomic_inc(&tio->io->io_count); + sector = clone->bi_sector; + r = ti->type->map(ti, clone, &tio->info); + if (r == DM_MAPIO_REMAPPED) { + /* the bio has been remapped so dispatch it */ + + trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone, + tio->io->bio->bi_bdev->bd_dev, sector); + + generic_make_request(clone); + } else if (r < 0 || r == DM_MAPIO_REQUEUE) { + /* error the io and bail out, or requeue it if needed */ + md = tio->io->md; + dec_pending(tio->io, r); + /* + * Store bio_set for cleanup. + */ + clone->bi_end_io = NULL; + clone->bi_private = md->bs; + bio_put(clone); + free_tio(md, tio); + } else if (r) { + DMWARN("unimplemented target map return value: %d", r); + BUG(); + } +} + +struct clone_info { + struct mapped_device *md; + struct dm_table *map; + struct bio *bio; + struct dm_io *io; + sector_t sector; + sector_t sector_count; + unsigned short idx; +}; + +static void dm_bio_destructor(struct bio *bio) +{ + struct bio_set *bs = bio->bi_private; + + bio_free(bio, bs); +} + +/* + * Creates a little bio that just does part of a bvec. + */ +static struct bio *split_bvec(struct bio *bio, sector_t sector, + unsigned short idx, unsigned int offset, + unsigned int len, struct bio_set *bs) +{ + struct bio *clone; + struct bio_vec *bv = bio->bi_io_vec + idx; + + clone = bio_alloc_bioset(GFP_NOIO, 1, bs); + clone->bi_destructor = dm_bio_destructor; + *clone->bi_io_vec = *bv; + + clone->bi_sector = sector; + clone->bi_bdev = bio->bi_bdev; + clone->bi_rw = bio->bi_rw; + clone->bi_vcnt = 1; + clone->bi_size = to_bytes(len); + clone->bi_io_vec->bv_offset = offset; + clone->bi_io_vec->bv_len = clone->bi_size; + clone->bi_flags |= 1 << BIO_CLONED; + + if (bio_integrity(bio)) { + bio_integrity_clone(clone, bio, GFP_NOIO, bs); + bio_integrity_trim(clone, + bio_sector_offset(bio, idx, offset), len); + } + + return clone; +} + +/* + * Creates a bio that consists of range of complete bvecs. + */ +static struct bio *clone_bio(struct bio *bio, sector_t sector, + unsigned short idx, unsigned short bv_count, + unsigned int len, struct bio_set *bs) +{ + struct bio *clone; + + clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs); + __bio_clone(clone, bio); + clone->bi_destructor = dm_bio_destructor; + clone->bi_sector = sector; + clone->bi_idx = idx; + clone->bi_vcnt = idx + bv_count; + clone->bi_size = to_bytes(len); + clone->bi_flags &= ~(1 << BIO_SEG_VALID); + + if (bio_integrity(bio)) { + bio_integrity_clone(clone, bio, GFP_NOIO, bs); + + if (idx != bio->bi_idx || clone->bi_size < bio->bi_size) + bio_integrity_trim(clone, + bio_sector_offset(bio, idx, 0), len); + } + + return clone; +} + +static struct dm_target_io *alloc_tio(struct clone_info *ci, + struct dm_target *ti) +{ + struct dm_target_io *tio = mempool_alloc(ci->md->tio_pool, GFP_NOIO); + + tio->io = ci->io; + tio->ti = ti; + memset(&tio->info, 0, sizeof(tio->info)); + + return tio; +} + +static void __issue_target_request(struct clone_info *ci, struct dm_target *ti, + unsigned request_nr, sector_t len) +{ + struct dm_target_io *tio = alloc_tio(ci, ti); + struct bio *clone; + + tio->info.target_request_nr = request_nr; + + /* + * Discard requests require the bio's inline iovecs be initialized. + * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush + * and discard, so no need for concern about wasted bvec allocations. + */ + clone = bio_alloc_bioset(GFP_NOIO, ci->bio->bi_max_vecs, ci->md->bs); + __bio_clone(clone, ci->bio); + clone->bi_destructor = dm_bio_destructor; + if (len) { + clone->bi_sector = ci->sector; + clone->bi_size = to_bytes(len); + } + + __map_bio(ti, clone, tio); +} + +static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti, + unsigned num_requests, sector_t len) +{ + unsigned request_nr; + + for (request_nr = 0; request_nr < num_requests; request_nr++) + __issue_target_request(ci, ti, request_nr, len); +} + +static int __clone_and_map_empty_flush(struct clone_info *ci) +{ + unsigned target_nr = 0; + struct dm_target *ti; + + BUG_ON(bio_has_data(ci->bio)); + while ((ti = dm_table_get_target(ci->map, target_nr++))) + __issue_target_requests(ci, ti, ti->num_flush_requests, 0); + + return 0; +} + +/* + * Perform all io with a single clone. + */ +static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti) +{ + struct bio *clone, *bio = ci->bio; + struct dm_target_io *tio; + + tio = alloc_tio(ci, ti); + clone = clone_bio(bio, ci->sector, ci->idx, + bio->bi_vcnt - ci->idx, ci->sector_count, + ci->md->bs); + __map_bio(ti, clone, tio); + ci->sector_count = 0; +} + +static int __clone_and_map_discard(struct clone_info *ci) +{ + struct dm_target *ti; + sector_t len; + + do { + ti = dm_table_find_target(ci->map, ci->sector); + if (!dm_target_is_valid(ti)) + return -EIO; + + /* + * Even though the device advertised discard support, + * that does not mean every target supports it, and + * reconfiguration might also have changed that since the + * check was performed. + */ + if (!ti->num_discard_requests) + return -EOPNOTSUPP; + + len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti)); + + __issue_target_requests(ci, ti, ti->num_discard_requests, len); + + ci->sector += len; + } while (ci->sector_count -= len); + + return 0; +} + +static int __clone_and_map(struct clone_info *ci) +{ + struct bio *clone, *bio = ci->bio; + struct dm_target *ti; + sector_t len = 0, max; + struct dm_target_io *tio; + + if (unlikely(bio->bi_rw & REQ_DISCARD)) + return __clone_and_map_discard(ci); + + ti = dm_table_find_target(ci->map, ci->sector); + if (!dm_target_is_valid(ti)) + return -EIO; + + max = max_io_len(ci->sector, ti); + + if (ci->sector_count <= max) { + /* + * Optimise for the simple case where we can do all of + * the remaining io with a single clone. + */ + __clone_and_map_simple(ci, ti); + + } else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) { + /* + * There are some bvecs that don't span targets. + * Do as many of these as possible. + */ + int i; + sector_t remaining = max; + sector_t bv_len; + + for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) { + bv_len = to_sector(bio->bi_io_vec[i].bv_len); + + if (bv_len > remaining) + break; + + remaining -= bv_len; + len += bv_len; + } + + tio = alloc_tio(ci, ti); + clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len, + ci->md->bs); + __map_bio(ti, clone, tio); + + ci->sector += len; + ci->sector_count -= len; + ci->idx = i; + + } else { + /* + * Handle a bvec that must be split between two or more targets. + */ + struct bio_vec *bv = bio->bi_io_vec + ci->idx; + sector_t remaining = to_sector(bv->bv_len); + unsigned int offset = 0; + + do { + if (offset) { + ti = dm_table_find_target(ci->map, ci->sector); + if (!dm_target_is_valid(ti)) + return -EIO; + + max = max_io_len(ci->sector, ti); + } + + len = min(remaining, max); + + tio = alloc_tio(ci, ti); + clone = split_bvec(bio, ci->sector, ci->idx, + bv->bv_offset + offset, len, + ci->md->bs); + + __map_bio(ti, clone, tio); + + ci->sector += len; + ci->sector_count -= len; + offset += to_bytes(len); + } while (remaining -= len); + + ci->idx++; + } + + return 0; +} + +/* + * Split the bio into several clones and submit it to targets. + */ +static void __split_and_process_bio(struct mapped_device *md, struct bio *bio) +{ + struct clone_info ci; + int error = 0; + + ci.map = dm_get_live_table(md); + if (unlikely(!ci.map)) { + bio_io_error(bio); + return; + } + + ci.md = md; + ci.io = alloc_io(md); + ci.io->error = 0; + atomic_set(&ci.io->io_count, 1); + ci.io->bio = bio; + ci.io->md = md; + spin_lock_init(&ci.io->endio_lock); + ci.sector = bio->bi_sector; + ci.idx = bio->bi_idx; + + start_io_acct(ci.io); + if (bio->bi_rw & REQ_FLUSH) { + ci.bio = &ci.md->flush_bio; + ci.sector_count = 0; + error = __clone_and_map_empty_flush(&ci); + /* dec_pending submits any data associated with flush */ + } else { + ci.bio = bio; + ci.sector_count = bio_sectors(bio); + while (ci.sector_count && !error) + error = __clone_and_map(&ci); + } + + /* drop the extra reference count */ + dec_pending(ci.io, error); + dm_table_put(ci.map); +} +/*----------------------------------------------------------------- + * CRUD END + *---------------------------------------------------------------*/ + +static int dm_merge_bvec(struct request_queue *q, + struct bvec_merge_data *bvm, + struct bio_vec *biovec) +{ + struct mapped_device *md = q->queuedata; + struct dm_table *map = dm_get_live_table(md); + struct dm_target *ti; + sector_t max_sectors; + int max_size = 0; + + if (unlikely(!map)) + goto out; + + ti = dm_table_find_target(map, bvm->bi_sector); + if (!dm_target_is_valid(ti)) + goto out_table; + + /* + * Find maximum amount of I/O that won't need splitting + */ + max_sectors = min(max_io_len(bvm->bi_sector, ti), + (sector_t) BIO_MAX_SECTORS); + max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size; + if (max_size < 0) + max_size = 0; + + /* + * merge_bvec_fn() returns number of bytes + * it can accept at this offset + * max is precomputed maximal io size + */ + if (max_size && ti->type->merge) + max_size = ti->type->merge(ti, bvm, biovec, max_size); + /* + * If the target doesn't support merge method and some of the devices + * provided their merge_bvec method (we know this by looking at + * queue_max_hw_sectors), then we can't allow bios with multiple vector + * entries. So always set max_size to 0, and the code below allows + * just one page. + */ + else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9) + + max_size = 0; + +out_table: + dm_table_put(map); + +out: + /* + * Always allow an entire first page + */ + if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT)) + max_size = biovec->bv_len; + + return max_size; +} + +/* + * The request function that just remaps the bio built up by + * dm_merge_bvec. + */ +static void _dm_request(struct request_queue *q, struct bio *bio) +{ + int rw = bio_data_dir(bio); + struct mapped_device *md = q->queuedata; + int cpu; + + down_read(&md->io_lock); + + cpu = part_stat_lock(); + part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]); + part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio)); + part_stat_unlock(); + + /* if we're suspended, we have to queue this io for later */ + if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) { + up_read(&md->io_lock); + + if (bio_rw(bio) != READA) + queue_io(md, bio); + else + bio_io_error(bio); + return; + } + + __split_and_process_bio(md, bio); + up_read(&md->io_lock); + return; +} + +static int dm_request_based(struct mapped_device *md) +{ + return blk_queue_stackable(md->queue); +} + +static void dm_request(struct request_queue *q, struct bio *bio) +{ + struct mapped_device *md = q->queuedata; + + if (dm_request_based(md)) + blk_queue_bio(q, bio); + else + _dm_request(q, bio); +} + +void dm_dispatch_request(struct request *rq) +{ + int r; + + if (blk_queue_io_stat(rq->q)) + rq->cmd_flags |= REQ_IO_STAT; + + rq->start_time = jiffies; + r = blk_insert_cloned_request(rq->q, rq); + if (r) + dm_complete_request(rq, r); +} +EXPORT_SYMBOL_GPL(dm_dispatch_request); + +static void dm_rq_bio_destructor(struct bio *bio) +{ + struct dm_rq_clone_bio_info *info = bio->bi_private; + struct mapped_device *md = info->tio->md; + + free_bio_info(info); + bio_free(bio, md->bs); +} + +static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig, + void *data) +{ + struct dm_rq_target_io *tio = data; + struct mapped_device *md = tio->md; + struct dm_rq_clone_bio_info *info = alloc_bio_info(md); + + if (!info) + return -ENOMEM; + + info->orig = bio_orig; + info->tio = tio; + bio->bi_end_io = end_clone_bio; + bio->bi_private = info; + bio->bi_destructor = dm_rq_bio_destructor; + + return 0; +} + +static int setup_clone(struct request *clone, struct request *rq, + struct dm_rq_target_io *tio) +{ + int r; + + r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC, + dm_rq_bio_constructor, tio); + if (r) + return r; + + clone->cmd = rq->cmd; + clone->cmd_len = rq->cmd_len; + clone->sense = rq->sense; + clone->buffer = rq->buffer; + clone->end_io = end_clone_request; + clone->end_io_data = tio; + + return 0; +} + +static struct request *clone_rq(struct request *rq, struct mapped_device *md, + gfp_t gfp_mask) +{ + struct request *clone; + struct dm_rq_target_io *tio; + + tio = alloc_rq_tio(md, gfp_mask); + if (!tio) + return NULL; + + tio->md = md; + tio->ti = NULL; + tio->orig = rq; + tio->error = 0; + memset(&tio->info, 0, sizeof(tio->info)); + + clone = &tio->clone; + if (setup_clone(clone, rq, tio)) { + /* -ENOMEM */ + free_rq_tio(tio); + return NULL; + } + + return clone; +} + +/* + * Called with the queue lock held. + */ +static int dm_prep_fn(struct request_queue *q, struct request *rq) +{ + struct mapped_device *md = q->queuedata; + struct request *clone; + + if (unlikely(rq->special)) { + DMWARN("Already has something in rq->special."); + return BLKPREP_KILL; + } + + clone = clone_rq(rq, md, GFP_ATOMIC); + if (!clone) + return BLKPREP_DEFER; + + rq->special = clone; + rq->cmd_flags |= REQ_DONTPREP; + + return BLKPREP_OK; +} + +/* + * Returns: + * 0 : the request has been processed (not requeued) + * !0 : the request has been requeued + */ +static int map_request(struct dm_target *ti, struct request *clone, + struct mapped_device *md) +{ + int r, requeued = 0; + struct dm_rq_target_io *tio = clone->end_io_data; + + /* + * Hold the md reference here for the in-flight I/O. + * We can't rely on the reference count by device opener, + * because the device may be closed during the request completion + * when all bios are completed. + * See the comment in rq_completed() too. + */ + dm_get(md); + + tio->ti = ti; + r = ti->type->map_rq(ti, clone, &tio->info); + switch (r) { + case DM_MAPIO_SUBMITTED: + /* The target has taken the I/O to submit by itself later */ + break; + case DM_MAPIO_REMAPPED: + /* The target has remapped the I/O so dispatch it */ + trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)), + blk_rq_pos(tio->orig)); + dm_dispatch_request(clone); + break; + case DM_MAPIO_REQUEUE: + /* The target wants to requeue the I/O */ + dm_requeue_unmapped_request(clone); + requeued = 1; + break; + default: + if (r > 0) { + DMWARN("unimplemented target map return value: %d", r); + BUG(); + } + + /* The target wants to complete the I/O */ + dm_kill_unmapped_request(clone, r); + break; + } + + return requeued; +} + +/* + * q->request_fn for request-based dm. + * Called with the queue lock held. + */ +static void dm_request_fn(struct request_queue *q) +{ + struct mapped_device *md = q->queuedata; + struct dm_table *map = dm_get_live_table(md); + struct dm_target *ti; + struct request *rq, *clone; + sector_t pos; + + /* + * For suspend, check blk_queue_stopped() and increment + * ->pending within a single queue_lock not to increment the + * number of in-flight I/Os after the queue is stopped in + * dm_suspend(). + */ + while (!blk_queue_stopped(q)) { + rq = blk_peek_request(q); + if (!rq) + goto delay_and_out; + + /* always use block 0 to find the target for flushes for now */ + pos = 0; + if (!(rq->cmd_flags & REQ_FLUSH)) + pos = blk_rq_pos(rq); + + ti = dm_table_find_target(map, pos); + BUG_ON(!dm_target_is_valid(ti)); + + if (ti->type->busy && ti->type->busy(ti)) + goto delay_and_out; + + blk_start_request(rq); + clone = rq->special; + atomic_inc(&md->pending[rq_data_dir(clone)]); + + spin_unlock(q->queue_lock); + if (map_request(ti, clone, md)) + goto requeued; + + BUG_ON(!irqs_disabled()); + spin_lock(q->queue_lock); + } + + goto out; + +requeued: + BUG_ON(!irqs_disabled()); + spin_lock(q->queue_lock); + +delay_and_out: + blk_delay_queue(q, HZ / 10); +out: + dm_table_put(map); + + return; +} + +int dm_underlying_device_busy(struct request_queue *q) +{ + return blk_lld_busy(q); +} +EXPORT_SYMBOL_GPL(dm_underlying_device_busy); + +static int dm_lld_busy(struct request_queue *q) +{ + int r; + struct mapped_device *md = q->queuedata; + struct dm_table *map = dm_get_live_table(md); + + if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) + r = 1; + else + r = dm_table_any_busy_target(map); + + dm_table_put(map); + + return r; +} + +static int dm_any_congested(void *congested_data, int bdi_bits) +{ + int r = bdi_bits; + struct mapped_device *md = congested_data; + struct dm_table *map; + + if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) { + map = dm_get_live_table(md); + if (map) { + /* + * Request-based dm cares about only own queue for + * the query about congestion status of request_queue + */ + if (dm_request_based(md)) + r = md->queue->backing_dev_info.state & + bdi_bits; + else + r = dm_table_any_congested(map, bdi_bits); + + dm_table_put(map); + } + } + + return r; +} + +/*----------------------------------------------------------------- + * An IDR is used to keep track of allocated minor numbers. + *---------------------------------------------------------------*/ +static void free_minor(int minor) +{ + spin_lock(&_minor_lock); + idr_remove(&_minor_idr, minor); + spin_unlock(&_minor_lock); +} + +/* + * See if the device with a specific minor # is free. + */ +static int specific_minor(int minor) +{ + int r, m; + + if (minor >= (1 << MINORBITS)) + return -EINVAL; + + r = idr_pre_get(&_minor_idr, GFP_KERNEL); + if (!r) + return -ENOMEM; + + spin_lock(&_minor_lock); + + if (idr_find(&_minor_idr, minor)) { + r = -EBUSY; + goto out; + } + + r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m); + if (r) + goto out; + + if (m != minor) { + idr_remove(&_minor_idr, m); + r = -EBUSY; + goto out; + } + +out: + spin_unlock(&_minor_lock); + return r; +} + +static int next_free_minor(int *minor) +{ + int r, m; + + r = idr_pre_get(&_minor_idr, GFP_KERNEL); + if (!r) + return -ENOMEM; + + spin_lock(&_minor_lock); + + r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m); + if (r) + goto out; + + if (m >= (1 << MINORBITS)) { + idr_remove(&_minor_idr, m); + r = -ENOSPC; + goto out; + } + + *minor = m; + +out: + spin_unlock(&_minor_lock); + return r; +} + +static const struct block_device_operations dm_blk_dops; + +static void dm_wq_work(struct work_struct *work); + +static void dm_init_md_queue(struct mapped_device *md) +{ + /* + * Request-based dm devices cannot be stacked on top of bio-based dm + * devices. The type of this dm device has not been decided yet. + * The type is decided at the first table loading time. + * To prevent problematic device stacking, clear the queue flag + * for request stacking support until then. + * + * This queue is new, so no concurrency on the queue_flags. + */ + queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue); + + md->queue->queuedata = md; + md->queue->backing_dev_info.congested_fn = dm_any_congested; + md->queue->backing_dev_info.congested_data = md; + blk_queue_make_request(md->queue, dm_request); + blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); + blk_queue_merge_bvec(md->queue, dm_merge_bvec); +} + +/* + * Allocate and initialise a blank device with a given minor. + */ +static struct mapped_device *alloc_dev(int minor) +{ + int r; + struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL); + void *old_md; + + if (!md) { + DMWARN("unable to allocate device, out of memory."); + return NULL; + } + + if (!try_module_get(THIS_MODULE)) + goto bad_module_get; + + /* get a minor number for the dev */ + if (minor == DM_ANY_MINOR) + r = next_free_minor(&minor); + else + r = specific_minor(minor); + if (r < 0) + goto bad_minor; + + md->type = DM_TYPE_NONE; + init_rwsem(&md->io_lock); + mutex_init(&md->suspend_lock); + mutex_init(&md->type_lock); + spin_lock_init(&md->deferred_lock); + rwlock_init(&md->map_lock); + atomic_set(&md->holders, 1); + atomic_set(&md->open_count, 0); + atomic_set(&md->event_nr, 0); + atomic_set(&md->uevent_seq, 0); + INIT_LIST_HEAD(&md->uevent_list); + spin_lock_init(&md->uevent_lock); + + md->queue = blk_alloc_queue(GFP_KERNEL); + if (!md->queue) + goto bad_queue; + + dm_init_md_queue(md); + + md->disk = alloc_disk(1); + if (!md->disk) + goto bad_disk; + + atomic_set(&md->pending[0], 0); + atomic_set(&md->pending[1], 0); + init_waitqueue_head(&md->wait); + INIT_WORK(&md->work, dm_wq_work); + init_waitqueue_head(&md->eventq); + + md->disk->major = _major; + md->disk->first_minor = minor; + md->disk->fops = &dm_blk_dops; + md->disk->queue = md->queue; + md->disk->private_data = md; + sprintf(md->disk->disk_name, "dm-%d", minor); + add_disk(md->disk); + format_dev_t(md->name, MKDEV(_major, minor)); + + md->wq = alloc_workqueue("kdmflush", + WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0); + if (!md->wq) + goto bad_thread; + + md->bdev = bdget_disk(md->disk, 0); + if (!md->bdev) + goto bad_bdev; + + bio_init(&md->flush_bio); + md->flush_bio.bi_bdev = md->bdev; + md->flush_bio.bi_rw = WRITE_FLUSH; + + /* Populate the mapping, nobody knows we exist yet */ + spin_lock(&_minor_lock); + old_md = idr_replace(&_minor_idr, md, minor); + spin_unlock(&_minor_lock); + + BUG_ON(old_md != MINOR_ALLOCED); + + return md; + +bad_bdev: + destroy_workqueue(md->wq); +bad_thread: + del_gendisk(md->disk); + put_disk(md->disk); +bad_disk: + blk_cleanup_queue(md->queue); +bad_queue: + free_minor(minor); +bad_minor: + module_put(THIS_MODULE); +bad_module_get: + kfree(md); + return NULL; +} + +static void unlock_fs(struct mapped_device *md); + +static void free_dev(struct mapped_device *md) +{ + int minor = MINOR(disk_devt(md->disk)); + + unlock_fs(md); + bdput(md->bdev); + destroy_workqueue(md->wq); + if (md->tio_pool) + mempool_destroy(md->tio_pool); + if (md->io_pool) + mempool_destroy(md->io_pool); + if (md->bs) + bioset_free(md->bs); + blk_integrity_unregister(md->disk); + del_gendisk(md->disk); + free_minor(minor); + + spin_lock(&_minor_lock); + md->disk->private_data = NULL; + spin_unlock(&_minor_lock); + + put_disk(md->disk); + blk_cleanup_queue(md->queue); + module_put(THIS_MODULE); + kfree(md); +} + +static void __bind_mempools(struct mapped_device *md, struct dm_table *t) +{ + struct dm_md_mempools *p; + + if (md->io_pool && md->tio_pool && md->bs) + /* the md already has necessary mempools */ + goto out; + + p = dm_table_get_md_mempools(t); + BUG_ON(!p || md->io_pool || md->tio_pool || md->bs); + + md->io_pool = p->io_pool; + p->io_pool = NULL; + md->tio_pool = p->tio_pool; + p->tio_pool = NULL; + md->bs = p->bs; + p->bs = NULL; + +out: + /* mempool bind completed, now no need any mempools in the table */ + dm_table_free_md_mempools(t); +} + +/* + * Bind a table to the device. + */ +static void event_callback(void *context) +{ + unsigned long flags; + LIST_HEAD(uevents); + struct mapped_device *md = (struct mapped_device *) context; + + spin_lock_irqsave(&md->uevent_lock, flags); + list_splice_init(&md->uevent_list, &uevents); + spin_unlock_irqrestore(&md->uevent_lock, flags); + + dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj); + + atomic_inc(&md->event_nr); + wake_up(&md->eventq); +} + +/* + * Protected by md->suspend_lock obtained by dm_swap_table(). + */ +static void __set_size(struct mapped_device *md, sector_t size) +{ + set_capacity(md->disk, size); + + i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); +} + +/* + * Return 1 if the queue has a compulsory merge_bvec_fn function. + * + * If this function returns 0, then the device is either a non-dm + * device without a merge_bvec_fn, or it is a dm device that is + * able to split any bios it receives that are too big. + */ +int dm_queue_merge_is_compulsory(struct request_queue *q) +{ + struct mapped_device *dev_md; + + if (!q->merge_bvec_fn) + return 0; + + if (q->make_request_fn == dm_request) { + dev_md = q->queuedata; + if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags)) + return 0; + } + + return 1; +} + +static int dm_device_merge_is_compulsory(struct dm_target *ti, + struct dm_dev *dev, sector_t start, + sector_t len, void *data) +{ + struct block_device *bdev = dev->bdev; + struct request_queue *q = bdev_get_queue(bdev); + + return dm_queue_merge_is_compulsory(q); +} + +/* + * Return 1 if it is acceptable to ignore merge_bvec_fn based + * on the properties of the underlying devices. + */ +static int dm_table_merge_is_optional(struct dm_table *table) +{ + unsigned i = 0; + struct dm_target *ti; + + while (i < dm_table_get_num_targets(table)) { + ti = dm_table_get_target(table, i++); + + if (ti->type->iterate_devices && + ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL)) + return 0; + } + + return 1; +} + +/* + * Returns old map, which caller must destroy. + */ +static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, + struct queue_limits *limits) +{ + struct dm_table *old_map; + struct request_queue *q = md->queue; + sector_t size; + unsigned long flags; + int merge_is_optional; + + size = dm_table_get_size(t); + + /* + * Wipe any geometry if the size of the table changed. + */ + if (size != get_capacity(md->disk)) + memset(&md->geometry, 0, sizeof(md->geometry)); + + __set_size(md, size); + + dm_table_event_callback(t, event_callback, md); + + /* + * The queue hasn't been stopped yet, if the old table type wasn't + * for request-based during suspension. So stop it to prevent + * I/O mapping before resume. + * This must be done before setting the queue restrictions, + * because request-based dm may be run just after the setting. + */ + if (dm_table_request_based(t) && !blk_queue_stopped(q)) + stop_queue(q); + + __bind_mempools(md, t); + + merge_is_optional = dm_table_merge_is_optional(t); + + write_lock_irqsave(&md->map_lock, flags); + old_map = md->map; + md->map = t; + md->immutable_target_type = dm_table_get_immutable_target_type(t); + + dm_table_set_restrictions(t, q, limits); + if (merge_is_optional) + set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags); + else + clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags); + write_unlock_irqrestore(&md->map_lock, flags); + + return old_map; +} + +/* + * Returns unbound table for the caller to free. + */ +static struct dm_table *__unbind(struct mapped_device *md) +{ + struct dm_table *map = md->map; + unsigned long flags; + + if (!map) + return NULL; + + dm_table_event_callback(map, NULL, NULL); + write_lock_irqsave(&md->map_lock, flags); + md->map = NULL; + write_unlock_irqrestore(&md->map_lock, flags); + + return map; +} + +/* + * Constructor for a new device. + */ +int dm_create(int minor, struct mapped_device **result) +{ + struct mapped_device *md; + + md = alloc_dev(minor); + if (!md) + return -ENXIO; + + dm_sysfs_init(md); + + *result = md; + return 0; +} + +/* + * Functions to manage md->type. + * All are required to hold md->type_lock. + */ +void dm_lock_md_type(struct mapped_device *md) +{ + mutex_lock(&md->type_lock); +} + +void dm_unlock_md_type(struct mapped_device *md) +{ + mutex_unlock(&md->type_lock); +} + +void dm_set_md_type(struct mapped_device *md, unsigned type) +{ + md->type = type; +} + +unsigned dm_get_md_type(struct mapped_device *md) +{ + return md->type; +} + +struct target_type *dm_get_immutable_target_type(struct mapped_device *md) +{ + return md->immutable_target_type; +} + +/* + * Fully initialize a request-based queue (->elevator, ->request_fn, etc). + */ +static int dm_init_request_based_queue(struct mapped_device *md) +{ + struct request_queue *q = NULL; + + if (md->queue->elevator) + return 1; + + /* Fully initialize the queue */ + q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL); + if (!q) + return 0; + + md->queue = q; + dm_init_md_queue(md); + blk_queue_softirq_done(md->queue, dm_softirq_done); + blk_queue_prep_rq(md->queue, dm_prep_fn); + blk_queue_lld_busy(md->queue, dm_lld_busy); + + elv_register_queue(md->queue); + + return 1; +} + +/* + * Setup the DM device's queue based on md's type + */ +int dm_setup_md_queue(struct mapped_device *md) +{ + if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) && + !dm_init_request_based_queue(md)) { + DMWARN("Cannot initialize queue for request-based mapped device"); + return -EINVAL; + } + + return 0; +} + +static struct mapped_device *dm_find_md(dev_t dev) +{ + struct mapped_device *md; + unsigned minor = MINOR(dev); + + if (MAJOR(dev) != _major || minor >= (1 << MINORBITS)) + return NULL; + + spin_lock(&_minor_lock); + + md = idr_find(&_minor_idr, minor); + if (md && (md == MINOR_ALLOCED || + (MINOR(disk_devt(dm_disk(md))) != minor) || + dm_deleting_md(md) || + test_bit(DMF_FREEING, &md->flags))) { + md = NULL; + goto out; + } + +out: + spin_unlock(&_minor_lock); + + return md; +} + +struct mapped_device *dm_get_md(dev_t dev) +{ + struct mapped_device *md = dm_find_md(dev); + + if (md) + dm_get(md); + + return md; +} +EXPORT_SYMBOL_GPL(dm_get_md); + +void *dm_get_mdptr(struct mapped_device *md) +{ + return md->interface_ptr; +} + +void dm_set_mdptr(struct mapped_device *md, void *ptr) +{ + md->interface_ptr = ptr; +} + +void dm_get(struct mapped_device *md) +{ + atomic_inc(&md->holders); + BUG_ON(test_bit(DMF_FREEING, &md->flags)); +} + +const char *dm_device_name(struct mapped_device *md) +{ + return md->name; +} +EXPORT_SYMBOL_GPL(dm_device_name); + +static void __dm_destroy(struct mapped_device *md, bool wait) +{ + struct dm_table *map; + + might_sleep(); + + spin_lock(&_minor_lock); + map = dm_get_live_table(md); + idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md)))); + set_bit(DMF_FREEING, &md->flags); + spin_unlock(&_minor_lock); + + if (!dm_suspended_md(md)) { + dm_table_presuspend_targets(map); + dm_table_postsuspend_targets(map); + } + + /* + * Rare, but there may be I/O requests still going to complete, + * for example. Wait for all references to disappear. + * No one should increment the reference count of the mapped_device, + * after the mapped_device state becomes DMF_FREEING. + */ + if (wait) + while (atomic_read(&md->holders)) + msleep(1); + else if (atomic_read(&md->holders)) + DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)", + dm_device_name(md), atomic_read(&md->holders)); + + dm_sysfs_exit(md); + dm_table_put(map); + dm_table_destroy(__unbind(md)); + free_dev(md); +} + +void dm_destroy(struct mapped_device *md) +{ + __dm_destroy(md, true); +} + +void dm_destroy_immediate(struct mapped_device *md) +{ + __dm_destroy(md, false); +} + +void dm_put(struct mapped_device *md) +{ + atomic_dec(&md->holders); +} +EXPORT_SYMBOL_GPL(dm_put); + +static int dm_wait_for_completion(struct mapped_device *md, int interruptible) +{ + int r = 0; + DECLARE_WAITQUEUE(wait, current); + + add_wait_queue(&md->wait, &wait); + + while (1) { + set_current_state(interruptible); + + if (!md_in_flight(md)) + break; + + if (interruptible == TASK_INTERRUPTIBLE && + signal_pending(current)) { + r = -EINTR; + break; + } + + io_schedule(); + } + set_current_state(TASK_RUNNING); + + remove_wait_queue(&md->wait, &wait); + + return r; +} + +/* + * Process the deferred bios + */ +static void dm_wq_work(struct work_struct *work) +{ + struct mapped_device *md = container_of(work, struct mapped_device, + work); + struct bio *c; + + down_read(&md->io_lock); + + while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) { + spin_lock_irq(&md->deferred_lock); + c = bio_list_pop(&md->deferred); + spin_unlock_irq(&md->deferred_lock); + + if (!c) + break; + + up_read(&md->io_lock); + + if (dm_request_based(md)) + generic_make_request(c); + else + __split_and_process_bio(md, c); + + down_read(&md->io_lock); + } + + up_read(&md->io_lock); +} + +static void dm_queue_flush(struct mapped_device *md) +{ + clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); + smp_mb__after_clear_bit(); + queue_work(md->wq, &md->work); +} + +/* + * Swap in a new table, returning the old one for the caller to destroy. + */ +struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table) +{ + struct dm_table *map = ERR_PTR(-EINVAL); + struct queue_limits limits; + int r; + + mutex_lock(&md->suspend_lock); + + /* device must be suspended */ + if (!dm_suspended_md(md)) + goto out; + + r = dm_calculate_queue_limits(table, &limits); + if (r) { + map = ERR_PTR(r); + goto out; + } + + map = __bind(md, table, &limits); + +out: + mutex_unlock(&md->suspend_lock); + return map; +} + +/* + * Functions to lock and unlock any filesystem running on the + * device. + */ +static int lock_fs(struct mapped_device *md) +{ + int r; + + WARN_ON(md->frozen_sb); + + md->frozen_sb = freeze_bdev(md->bdev); + if (IS_ERR(md->frozen_sb)) { + r = PTR_ERR(md->frozen_sb); + md->frozen_sb = NULL; + return r; + } + + set_bit(DMF_FROZEN, &md->flags); + + return 0; +} + +static void unlock_fs(struct mapped_device *md) +{ + if (!test_bit(DMF_FROZEN, &md->flags)) + return; + + thaw_bdev(md->bdev, md->frozen_sb); + md->frozen_sb = NULL; + clear_bit(DMF_FROZEN, &md->flags); +} + +/* + * We need to be able to change a mapping table under a mounted + * filesystem. For example we might want to move some data in + * the background. Before the table can be swapped with + * dm_bind_table, dm_suspend must be called to flush any in + * flight bios and ensure that any further io gets deferred. + */ +/* + * Suspend mechanism in request-based dm. + * + * 1. Flush all I/Os by lock_fs() if needed. + * 2. Stop dispatching any I/O by stopping the request_queue. + * 3. Wait for all in-flight I/Os to be completed or requeued. + * + * To abort suspend, start the request_queue. + */ +int dm_suspend(struct mapped_device *md, unsigned suspend_flags) +{ + struct dm_table *map = NULL; + int r = 0; + int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0; + int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0; + + mutex_lock(&md->suspend_lock); + + if (dm_suspended_md(md)) { + r = -EINVAL; + goto out_unlock; + } + + map = dm_get_live_table(md); + + /* + * DMF_NOFLUSH_SUSPENDING must be set before presuspend. + * This flag is cleared before dm_suspend returns. + */ + if (noflush) + set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); + + /* This does not get reverted if there's an error later. */ + dm_table_presuspend_targets(map); + + /* + * Flush I/O to the device. + * Any I/O submitted after lock_fs() may not be flushed. + * noflush takes precedence over do_lockfs. + * (lock_fs() flushes I/Os and waits for them to complete.) + */ + if (!noflush && do_lockfs) { + r = lock_fs(md); + if (r) + goto out; + } + + /* + * Here we must make sure that no processes are submitting requests + * to target drivers i.e. no one may be executing + * __split_and_process_bio. This is called from dm_request and + * dm_wq_work. + * + * To get all processes out of __split_and_process_bio in dm_request, + * we take the write lock. To prevent any process from reentering + * __split_and_process_bio from dm_request and quiesce the thread + * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call + * flush_workqueue(md->wq). + */ + down_write(&md->io_lock); + set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); + up_write(&md->io_lock); + + /* + * Stop md->queue before flushing md->wq in case request-based + * dm defers requests to md->wq from md->queue. + */ + if (dm_request_based(md)) + stop_queue(md->queue); + + flush_workqueue(md->wq); + + /* + * At this point no more requests are entering target request routines. + * We call dm_wait_for_completion to wait for all existing requests + * to finish. + */ + r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE); + + down_write(&md->io_lock); + if (noflush) + clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); + up_write(&md->io_lock); + + /* were we interrupted ? */ + if (r < 0) { + dm_queue_flush(md); + + if (dm_request_based(md)) + start_queue(md->queue); + + unlock_fs(md); + goto out; /* pushback list is already flushed, so skip flush */ + } + + /* + * If dm_wait_for_completion returned 0, the device is completely + * quiescent now. There is no request-processing activity. All new + * requests are being added to md->deferred list. + */ + + set_bit(DMF_SUSPENDED, &md->flags); + + dm_table_postsuspend_targets(map); + +out: + dm_table_put(map); + +out_unlock: + mutex_unlock(&md->suspend_lock); + return r; +} + +int dm_resume(struct mapped_device *md) +{ + int r = -EINVAL; + struct dm_table *map = NULL; + + mutex_lock(&md->suspend_lock); + if (!dm_suspended_md(md)) + goto out; + + map = dm_get_live_table(md); + if (!map || !dm_table_get_size(map)) + goto out; + + r = dm_table_resume_targets(map); + if (r) + goto out; + + dm_queue_flush(md); + + /* + * Flushing deferred I/Os must be done after targets are resumed + * so that mapping of targets can work correctly. + * Request-based dm is queueing the deferred I/Os in its request_queue. + */ + if (dm_request_based(md)) + start_queue(md->queue); + + unlock_fs(md); + + clear_bit(DMF_SUSPENDED, &md->flags); + + r = 0; +out: + dm_table_put(map); + mutex_unlock(&md->suspend_lock); + + return r; +} + +/*----------------------------------------------------------------- + * Event notification. + *---------------------------------------------------------------*/ +int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, + unsigned cookie) +{ + char udev_cookie[DM_COOKIE_LENGTH]; + char *envp[] = { udev_cookie, NULL }; + + if (!cookie) + return kobject_uevent(&disk_to_dev(md->disk)->kobj, action); + else { + snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u", + DM_COOKIE_ENV_VAR_NAME, cookie); + return kobject_uevent_env(&disk_to_dev(md->disk)->kobj, + action, envp); + } +} + +uint32_t dm_next_uevent_seq(struct mapped_device *md) +{ + return atomic_add_return(1, &md->uevent_seq); +} + +uint32_t dm_get_event_nr(struct mapped_device *md) +{ + return atomic_read(&md->event_nr); +} + +int dm_wait_event(struct mapped_device *md, int event_nr) +{ + return wait_event_interruptible(md->eventq, + (event_nr != atomic_read(&md->event_nr))); +} + +void dm_uevent_add(struct mapped_device *md, struct list_head *elist) +{ + unsigned long flags; + + spin_lock_irqsave(&md->uevent_lock, flags); + list_add(elist, &md->uevent_list); + spin_unlock_irqrestore(&md->uevent_lock, flags); +} + +/* + * The gendisk is only valid as long as you have a reference + * count on 'md'. + */ +struct gendisk *dm_disk(struct mapped_device *md) +{ + return md->disk; +} + +struct kobject *dm_kobject(struct mapped_device *md) +{ + return &md->kobj; +} + +/* + * struct mapped_device should not be exported outside of dm.c + * so use this check to verify that kobj is part of md structure + */ +struct mapped_device *dm_get_from_kobject(struct kobject *kobj) +{ + struct mapped_device *md; + + md = container_of(kobj, struct mapped_device, kobj); + if (&md->kobj != kobj) + return NULL; + + if (test_bit(DMF_FREEING, &md->flags) || + dm_deleting_md(md)) + return NULL; + + dm_get(md); + return md; +} + +int dm_suspended_md(struct mapped_device *md) +{ + return test_bit(DMF_SUSPENDED, &md->flags); +} + +int dm_suspended(struct dm_target *ti) +{ + return dm_suspended_md(dm_table_get_md(ti->table)); +} +EXPORT_SYMBOL_GPL(dm_suspended); + +int dm_noflush_suspending(struct dm_target *ti) +{ + return __noflush_suspending(dm_table_get_md(ti->table)); +} +EXPORT_SYMBOL_GPL(dm_noflush_suspending); + +struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity) +{ + struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL); + unsigned int pool_size = (type == DM_TYPE_BIO_BASED) ? 16 : MIN_IOS; + + if (!pools) + return NULL; + + pools->io_pool = (type == DM_TYPE_BIO_BASED) ? + mempool_create_slab_pool(MIN_IOS, _io_cache) : + mempool_create_slab_pool(MIN_IOS, _rq_bio_info_cache); + if (!pools->io_pool) + goto free_pools_and_out; + + pools->tio_pool = (type == DM_TYPE_BIO_BASED) ? + mempool_create_slab_pool(MIN_IOS, _tio_cache) : + mempool_create_slab_pool(MIN_IOS, _rq_tio_cache); + if (!pools->tio_pool) + goto free_io_pool_and_out; + + pools->bs = bioset_create(pool_size, 0); + if (!pools->bs) + goto free_tio_pool_and_out; + + if (integrity && bioset_integrity_create(pools->bs, pool_size)) + goto free_bioset_and_out; + + return pools; + +free_bioset_and_out: + bioset_free(pools->bs); + +free_tio_pool_and_out: + mempool_destroy(pools->tio_pool); + +free_io_pool_and_out: + mempool_destroy(pools->io_pool); + +free_pools_and_out: + kfree(pools); + + return NULL; +} + +void dm_free_md_mempools(struct dm_md_mempools *pools) +{ + if (!pools) + return; + + if (pools->io_pool) + mempool_destroy(pools->io_pool); + + if (pools->tio_pool) + mempool_destroy(pools->tio_pool); + + if (pools->bs) + bioset_free(pools->bs); + + kfree(pools); +} + +static const struct block_device_operations dm_blk_dops = { + .open = dm_blk_open, + .release = dm_blk_close, + .ioctl = dm_blk_ioctl, + .getgeo = dm_blk_getgeo, + .owner = THIS_MODULE +}; + +EXPORT_SYMBOL(dm_get_mapinfo); + +/* + * module hooks + */ +module_init(dm_init); +module_exit(dm_exit); + +module_param(major, uint, 0); +MODULE_PARM_DESC(major, "The major number of the device mapper"); +MODULE_DESCRIPTION(DM_NAME " driver"); +MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); +MODULE_LICENSE("GPL"); |