diff options
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 1712 |
1 files changed, 1712 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c new file mode 100644 index 0000000..b798bd3 --- /dev/null +++ b/drivers/md/dm.c @@ -0,0 +1,1712 @@ +/* + * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. + * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved. + * + * This file is released under the GPL. + */ + +#include "dm.h" +#include "dm-bio-list.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/buffer_head.h> +#include <linux/mempool.h> +#include <linux/slab.h> +#include <linux/idr.h> +#include <linux/hdreg.h> +#include <linux/blktrace_api.h> + +#define DM_MSG_PREFIX "core" + +static const char *_name = DM_NAME; + +static unsigned int major = 0; +static unsigned int _major = 0; + +static DEFINE_SPINLOCK(_minor_lock); +/* + * 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; +}; + +/* + * 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; +}; + +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; +} + +#define MINOR_ALLOCED ((void *)-1) + +/* + * Bits for the md->flags field. + */ +#define DMF_BLOCK_IO 0 +#define DMF_SUSPENDED 1 +#define DMF_FROZEN 2 +#define DMF_FREEING 3 +#define DMF_DELETING 4 +#define DMF_NOFLUSH_SUSPENDING 5 + +/* + * Work processed by per-device workqueue. + */ +struct dm_wq_req { + enum { + DM_WQ_FLUSH_DEFERRED, + } type; + struct work_struct work; + struct mapped_device *md; + void *context; +}; + +struct mapped_device { + struct rw_semaphore io_lock; + struct mutex suspend_lock; + spinlock_t pushback_lock; + rwlock_t map_lock; + atomic_t holders; + atomic_t open_count; + + unsigned long flags; + + struct request_queue *queue; + struct gendisk *disk; + char name[16]; + + void *interface_ptr; + + /* + * A list of ios that arrived while we were suspended. + */ + atomic_t pending; + wait_queue_head_t wait; + struct bio_list deferred; + struct bio_list pushback; + + /* + * Processing queue (flush/barriers) + */ + 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 *suspended_bdev; + + /* forced geometry settings */ + struct hd_geometry geometry; +}; + +#define MIN_IOS 256 +static struct kmem_cache *_io_cache; +static struct kmem_cache *_tio_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; + + r = dm_uevent_init(); + if (r) + goto out_free_tio_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_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(_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_kcopyd_init, + dm_interface_init, +}; + +static void (*_exits[])(void) = { + local_exit, + dm_target_exit, + dm_linear_exit, + dm_stripe_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](); +} + +/* + * Block device functions + */ +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) || + test_bit(DMF_DELETING, &md->flags)) { + 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; + atomic_dec(&md->open_count); + dm_put(md); + 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_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)) { + 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 struct dm_target_io *alloc_tio(struct mapped_device *md) +{ + return mempool_alloc(md->tio_pool, GFP_NOIO); +} + +static void free_tio(struct mapped_device *md, struct dm_target_io *tio) +{ + mempool_free(tio, md->tio_pool); +} + +static void start_io_acct(struct dm_io *io) +{ + struct mapped_device *md = io->md; + int cpu; + + io->start_time = jiffies; + + cpu = part_stat_lock(); + part_round_stats(cpu, &dm_disk(md)->part0); + part_stat_unlock(); + dm_disk(md)->part0.in_flight = atomic_inc_return(&md->pending); +} + +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(); + + dm_disk(md)->part0.in_flight = pending = + atomic_dec_return(&md->pending); + + /* nudge anyone waiting on suspend queue */ + if (!pending) + wake_up(&md->wait); +} + +/* + * Add the bio to the list of deferred io. + */ +static int queue_io(struct mapped_device *md, struct bio *bio) +{ + down_write(&md->io_lock); + + if (!test_bit(DMF_BLOCK_IO, &md->flags)) { + up_write(&md->io_lock); + return 1; + } + + bio_list_add(&md->deferred, bio); + + up_write(&md->io_lock); + return 0; /* deferred successfully */ +} + +/* + * 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_table(struct mapped_device *md) +{ + struct dm_table *t; + + read_lock(&md->map_lock); + t = md->map; + if (t) + dm_table_get(t); + read_unlock(&md->map_lock); + + 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 (error && !(io->error > 0 && __noflush_suspending(md))) + io->error = error; + + if (atomic_dec_and_test(&io->io_count)) { + if (io->error == DM_ENDIO_REQUEUE) { + /* + * Target requested pushing back the I/O. + * This must be handled before the sleeper on + * suspend queue merges the pushback list. + */ + spin_lock_irqsave(&md->pushback_lock, flags); + if (__noflush_suspending(md)) + bio_list_add(&md->pushback, io->bio); + else + /* noflush suspend was interrupted. */ + io->error = -EIO; + spin_unlock_irqrestore(&md->pushback_lock, flags); + } + + end_io_acct(io); + + io_error = io->error; + bio = io->bio; + + free_io(md, io); + + if (io_error != DM_ENDIO_REQUEUE) { + blk_add_trace_bio(md->queue, io->bio, + BLK_TA_COMPLETE); + + 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); +} + +static sector_t max_io_len(struct mapped_device *md, + sector_t sector, struct dm_target *ti) +{ + sector_t offset = sector - ti->begin; + sector_t len = ti->len - offset; + + /* + * Does the target need to split even further ? + */ + if (ti->split_io) { + sector_t boundary; + 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; + + /* + * Sanity checks. + */ + BUG_ON(!clone->bi_size); + + 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 */ + + blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone, + tio->io->bio->bi_bdev->bd_dev, + clone->bi_sector, 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_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 is 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; + + 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); + + return clone; +} + +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; + + ti = dm_table_find_target(ci->map, ci->sector); + if (!dm_target_is_valid(ti)) + return -EIO; + + max = max_io_len(ci->md, ci->sector, ti); + + /* + * Allocate a target io object. + */ + tio = alloc_tio(ci->md); + tio->io = ci->io; + tio->ti = ti; + memset(&tio->info, 0, sizeof(tio->info)); + + if (ci->sector_count <= max) { + /* + * Optimise for the simple case where we can do all of + * the remaining io with a single clone. + */ + 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; + + } 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; + } + + 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->md, ci->sector, ti); + + tio = alloc_tio(ci->md); + tio->io = ci->io; + tio->ti = ti; + memset(&tio->info, 0, sizeof(tio->info)); + } + + len = min(remaining, max); + + 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. + */ +static int __split_bio(struct mapped_device *md, struct bio *bio) +{ + struct clone_info ci; + int error = 0; + + ci.map = dm_get_table(md); + if (unlikely(!ci.map)) + return -EIO; + + ci.md = md; + ci.bio = bio; + ci.io = alloc_io(md); + ci.io->error = 0; + atomic_set(&ci.io->io_count, 1); + ci.io->bio = bio; + ci.io->md = md; + ci.sector = bio->bi_sector; + ci.sector_count = bio_sectors(bio); + ci.idx = bio->bi_idx; + + start_io_acct(ci.io); + 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); + + return 0; +} +/*----------------------------------------------------------------- + * 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_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(md, 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); + +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 int dm_request(struct request_queue *q, struct bio *bio) +{ + int r = -EIO; + int rw = bio_data_dir(bio); + struct mapped_device *md = q->queuedata; + int cpu; + + /* + * There is no use in forwarding any barrier request since we can't + * guarantee it is (or can be) handled by the targets correctly. + */ + if (unlikely(bio_barrier(bio))) { + bio_endio(bio, -EOPNOTSUPP); + return 0; + } + + 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. + */ + while (test_bit(DMF_BLOCK_IO, &md->flags)) { + up_read(&md->io_lock); + + if (bio_rw(bio) != READA) + r = queue_io(md, bio); + + if (r <= 0) + goto out_req; + + /* + * We're in a while loop, because someone could suspend + * before we get to the following read lock. + */ + down_read(&md->io_lock); + } + + r = __split_bio(md, bio); + up_read(&md->io_lock); + +out_req: + if (r < 0) + bio_io_error(bio); + + return 0; +} + +static void dm_unplug_all(struct request_queue *q) +{ + struct mapped_device *md = q->queuedata; + struct dm_table *map = dm_get_table(md); + + if (map) { + dm_table_unplug_all(map); + dm_table_put(map); + } +} + +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; + + atomic_inc(&md->pending); + + if (!test_bit(DMF_BLOCK_IO, &md->flags)) { + map = dm_get_table(md); + if (map) { + r = dm_table_any_congested(map, bdi_bits); + dm_table_put(map); + } + } + + if (!atomic_dec_return(&md->pending)) + /* nudge anyone waiting on suspend queue */ + wake_up(&md->wait); + + return r; +} + +/*----------------------------------------------------------------- + * An IDR is used to keep track of allocated minor numbers. + *---------------------------------------------------------------*/ +static DEFINE_IDR(_minor_idr); + +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 struct block_device_operations dm_blk_dops; + +/* + * 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; + + init_rwsem(&md->io_lock); + mutex_init(&md->suspend_lock); + spin_lock_init(&md->pushback_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; + + 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); + md->queue->unplug_fn = dm_unplug_all; + blk_queue_merge_bvec(md->queue, dm_merge_bvec); + + md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache); + if (!md->io_pool) + goto bad_io_pool; + + md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache); + if (!md->tio_pool) + goto bad_tio_pool; + + md->bs = bioset_create(16, 16); + if (!md->bs) + goto bad_no_bioset; + + md->disk = alloc_disk(1); + if (!md->disk) + goto bad_disk; + + atomic_set(&md->pending, 0); + init_waitqueue_head(&md->wait); + 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 = create_singlethread_workqueue("kdmflush"); + if (!md->wq) + goto bad_thread; + + /* 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_thread: + put_disk(md->disk); +bad_disk: + bioset_free(md->bs); +bad_no_bioset: + mempool_destroy(md->tio_pool); +bad_tio_pool: + mempool_destroy(md->io_pool); +bad_io_pool: + 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)); + + if (md->suspended_bdev) { + unlock_fs(md); + bdput(md->suspended_bdev); + } + destroy_workqueue(md->wq); + mempool_destroy(md->tio_pool); + mempool_destroy(md->io_pool); + bioset_free(md->bs); + 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); +} + +/* + * 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); +} + +static void __set_size(struct mapped_device *md, sector_t size) +{ + set_capacity(md->disk, size); + + mutex_lock(&md->suspended_bdev->bd_inode->i_mutex); + i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); + mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex); +} + +static int __bind(struct mapped_device *md, struct dm_table *t) +{ + struct request_queue *q = md->queue; + sector_t size; + + 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)); + + if (md->suspended_bdev) + __set_size(md, size); + if (size == 0) + return 0; + + dm_table_get(t); + dm_table_event_callback(t, event_callback, md); + + write_lock(&md->map_lock); + md->map = t; + dm_table_set_restrictions(t, q); + write_unlock(&md->map_lock); + + return 0; +} + +static void __unbind(struct mapped_device *md) +{ + struct dm_table *map = md->map; + + if (!map) + return; + + dm_table_event_callback(map, NULL, NULL); + write_lock(&md->map_lock); + md->map = NULL; + write_unlock(&md->map_lock); + dm_table_put(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; + + *result = md; + 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) || + 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; +} + +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); +} + +const char *dm_device_name(struct mapped_device *md) +{ + return md->name; +} +EXPORT_SYMBOL_GPL(dm_device_name); + +void dm_put(struct mapped_device *md) +{ + struct dm_table *map; + + BUG_ON(test_bit(DMF_FREEING, &md->flags)); + + if (atomic_dec_and_lock(&md->holders, &_minor_lock)) { + map = dm_get_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)) { + dm_table_presuspend_targets(map); + dm_table_postsuspend_targets(map); + } + __unbind(md); + dm_table_put(map); + free_dev(md); + } +} +EXPORT_SYMBOL_GPL(dm_put); + +static int dm_wait_for_completion(struct mapped_device *md) +{ + int r = 0; + + while (1) { + set_current_state(TASK_INTERRUPTIBLE); + + smp_mb(); + if (!atomic_read(&md->pending)) + break; + + if (signal_pending(current)) { + r = -EINTR; + break; + } + + io_schedule(); + } + set_current_state(TASK_RUNNING); + + return r; +} + +/* + * Process the deferred bios + */ +static void __flush_deferred_io(struct mapped_device *md) +{ + struct bio *c; + + while ((c = bio_list_pop(&md->deferred))) { + if (__split_bio(md, c)) + bio_io_error(c); + } + + clear_bit(DMF_BLOCK_IO, &md->flags); +} + +static void __merge_pushback_list(struct mapped_device *md) +{ + unsigned long flags; + + spin_lock_irqsave(&md->pushback_lock, flags); + clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); + bio_list_merge_head(&md->deferred, &md->pushback); + bio_list_init(&md->pushback); + spin_unlock_irqrestore(&md->pushback_lock, flags); +} + +static void dm_wq_work(struct work_struct *work) +{ + struct dm_wq_req *req = container_of(work, struct dm_wq_req, work); + struct mapped_device *md = req->md; + + down_write(&md->io_lock); + switch (req->type) { + case DM_WQ_FLUSH_DEFERRED: + __flush_deferred_io(md); + break; + default: + DMERR("dm_wq_work: unrecognised work type %d", req->type); + BUG(); + } + up_write(&md->io_lock); +} + +static void dm_wq_queue(struct mapped_device *md, int type, void *context, + struct dm_wq_req *req) +{ + req->type = type; + req->md = md; + req->context = context; + INIT_WORK(&req->work, dm_wq_work); + queue_work(md->wq, &req->work); +} + +static void dm_queue_flush(struct mapped_device *md, int type, void *context) +{ + struct dm_wq_req req; + + dm_wq_queue(md, type, context, &req); + flush_workqueue(md->wq); +} + +/* + * Swap in a new table (destroying old one). + */ +int dm_swap_table(struct mapped_device *md, struct dm_table *table) +{ + int r = -EINVAL; + + mutex_lock(&md->suspend_lock); + + /* device must be suspended */ + if (!dm_suspended(md)) + goto out; + + /* without bdev, the device size cannot be changed */ + if (!md->suspended_bdev) + if (get_capacity(md->disk) != dm_table_get_size(table)) + goto out; + + __unbind(md); + r = __bind(md, table); + +out: + mutex_unlock(&md->suspend_lock); + return r; +} + +/* + * 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->suspended_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); + + /* don't bdput right now, we don't want the bdev + * to go away while it is locked. + */ + return 0; +} + +static void unlock_fs(struct mapped_device *md) +{ + if (!test_bit(DMF_FROZEN, &md->flags)) + return; + + thaw_bdev(md->suspended_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. + */ +int dm_suspend(struct mapped_device *md, unsigned suspend_flags) +{ + struct dm_table *map = NULL; + DECLARE_WAITQUEUE(wait, current); + 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)) { + r = -EINVAL; + goto out_unlock; + } + + map = dm_get_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); + + /* bdget() can stall if the pending I/Os are not flushed */ + if (!noflush) { + md->suspended_bdev = bdget_disk(md->disk, 0); + if (!md->suspended_bdev) { + DMWARN("bdget failed in dm_suspend"); + r = -ENOMEM; + goto out; + } + + /* + * Flush I/O to the device. noflush supersedes do_lockfs, + * because lock_fs() needs to flush I/Os. + */ + if (do_lockfs) { + r = lock_fs(md); + if (r) + goto out; + } + } + + /* + * First we set the BLOCK_IO flag so no more ios will be mapped. + */ + down_write(&md->io_lock); + set_bit(DMF_BLOCK_IO, &md->flags); + + add_wait_queue(&md->wait, &wait); + up_write(&md->io_lock); + + /* unplug */ + if (map) + dm_table_unplug_all(map); + + /* + * Wait for the already-mapped ios to complete. + */ + r = dm_wait_for_completion(md); + + down_write(&md->io_lock); + remove_wait_queue(&md->wait, &wait); + + if (noflush) + __merge_pushback_list(md); + up_write(&md->io_lock); + + /* were we interrupted ? */ + if (r < 0) { + dm_queue_flush(md, DM_WQ_FLUSH_DEFERRED, NULL); + + unlock_fs(md); + goto out; /* pushback list is already flushed, so skip flush */ + } + + dm_table_postsuspend_targets(map); + + set_bit(DMF_SUSPENDED, &md->flags); + +out: + if (r && md->suspended_bdev) { + bdput(md->suspended_bdev); + md->suspended_bdev = NULL; + } + + 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)) + goto out; + + map = dm_get_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, DM_WQ_FLUSH_DEFERRED, NULL); + + unlock_fs(md); + + if (md->suspended_bdev) { + bdput(md->suspended_bdev); + md->suspended_bdev = NULL; + } + + clear_bit(DMF_SUSPENDED, &md->flags); + + dm_table_unplug_all(map); + + dm_kobject_uevent(md); + + r = 0; + +out: + dm_table_put(map); + mutex_unlock(&md->suspend_lock); + + return r; +} + +/*----------------------------------------------------------------- + * Event notification. + *---------------------------------------------------------------*/ +void dm_kobject_uevent(struct mapped_device *md) +{ + kobject_uevent(&disk_to_dev(md->disk)->kobj, KOBJ_CHANGE); +} + +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; +} + +int dm_suspended(struct mapped_device *md) +{ + return test_bit(DMF_SUSPENDED, &md->flags); +} + +int dm_noflush_suspending(struct dm_target *ti) +{ + struct mapped_device *md = dm_table_get_md(ti->table); + int r = __noflush_suspending(md); + + dm_put(md); + + return r; +} +EXPORT_SYMBOL_GPL(dm_noflush_suspending); + +static 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"); |
