diff options
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 1194 |
1 files changed, 1194 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c new file mode 100644 index 000000000000..243ff6884e83 --- /dev/null +++ b/drivers/md/dm.c @@ -0,0 +1,1194 @@ +/* + * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. + * Copyright (C) 2004 Red Hat, Inc. All rights reserved. + * + * This file is released under the GPL. + */ + +#include "dm.h" +#include "dm-bio-list.h" + +#include <linux/init.h> +#include <linux/module.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> + +static const char *_name = DM_NAME; + +static unsigned int major = 0; +static unsigned int _major = 0; + +/* + * One of these is allocated per bio. + */ +struct dm_io { + struct mapped_device *md; + int error; + struct bio *bio; + atomic_t io_count; +}; + +/* + * One of these is allocated per target within a bio. Hopefully + * this will be simplified out one day. + */ +struct 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 target_io *)bio->bi_private)->info; + return NULL; +} + +/* + * Bits for the md->flags field. + */ +#define DMF_BLOCK_IO 0 +#define DMF_SUSPENDED 1 +#define DMF_FS_LOCKED 2 + +struct mapped_device { + struct rw_semaphore lock; + rwlock_t map_lock; + atomic_t holders; + + unsigned long flags; + + request_queue_t *queue; + struct gendisk *disk; + + 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; + + /* + * The current mapping. + */ + struct dm_table *map; + + /* + * io objects are allocated from here. + */ + mempool_t *io_pool; + mempool_t *tio_pool; + + /* + * Event handling. + */ + atomic_t event_nr; + wait_queue_head_t eventq; + + /* + * freeze/thaw support require holding onto a super block + */ + struct super_block *frozen_sb; +}; + +#define MIN_IOS 256 +static kmem_cache_t *_io_cache; +static kmem_cache_t *_tio_cache; + +static struct bio_set *dm_set; + +static int __init local_init(void) +{ + int r; + + dm_set = bioset_create(16, 16, 4); + if (!dm_set) + return -ENOMEM; + + /* allocate a slab for the dm_ios */ + _io_cache = kmem_cache_create("dm_io", + sizeof(struct dm_io), 0, 0, NULL, NULL); + if (!_io_cache) + return -ENOMEM; + + /* allocate a slab for the target ios */ + _tio_cache = kmem_cache_create("dm_tio", sizeof(struct target_io), + 0, 0, NULL, NULL); + if (!_tio_cache) { + kmem_cache_destroy(_io_cache); + return -ENOMEM; + } + + _major = major; + r = register_blkdev(_major, _name); + if (r < 0) { + kmem_cache_destroy(_tio_cache); + kmem_cache_destroy(_io_cache); + return r; + } + + if (!_major) + _major = r; + + return 0; +} + +static void local_exit(void) +{ + kmem_cache_destroy(_tio_cache); + kmem_cache_destroy(_io_cache); + + bioset_free(dm_set); + + if (unregister_blkdev(_major, _name) < 0) + DMERR("devfs_unregister_blkdev failed"); + + _major = 0; + + DMINFO("cleaned up"); +} + +int (*_inits[])(void) __initdata = { + local_init, + dm_target_init, + dm_linear_init, + dm_stripe_init, + dm_interface_init, +}; + +void (*_exits[])(void) = { + local_exit, + dm_target_exit, + dm_linear_exit, + dm_stripe_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 inode *inode, struct file *file) +{ + struct mapped_device *md; + + md = inode->i_bdev->bd_disk->private_data; + dm_get(md); + return 0; +} + +static int dm_blk_close(struct inode *inode, struct file *file) +{ + struct mapped_device *md; + + md = inode->i_bdev->bd_disk->private_data; + dm_put(md); + return 0; +} + +static inline struct dm_io *alloc_io(struct mapped_device *md) +{ + return mempool_alloc(md->io_pool, GFP_NOIO); +} + +static inline void free_io(struct mapped_device *md, struct dm_io *io) +{ + mempool_free(io, md->io_pool); +} + +static inline struct target_io *alloc_tio(struct mapped_device *md) +{ + return mempool_alloc(md->tio_pool, GFP_NOIO); +} + +static inline void free_tio(struct mapped_device *md, struct target_io *tio) +{ + mempool_free(tio, md->tio_pool); +} + +/* + * Add the bio to the list of deferred io. + */ +static int queue_io(struct mapped_device *md, struct bio *bio) +{ + down_write(&md->lock); + + if (!test_bit(DMF_BLOCK_IO, &md->flags)) { + up_write(&md->lock); + return 1; + } + + bio_list_add(&md->deferred, bio); + + up_write(&md->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; +} + +/*----------------------------------------------------------------- + * 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. + *---------------------------------------------------------------*/ + +/* + * Decrements the number of outstanding ios that a bio has been + * cloned into, completing the original io if necc. + */ +static inline void dec_pending(struct dm_io *io, int error) +{ + if (error) + io->error = error; + + if (atomic_dec_and_test(&io->io_count)) { + if (atomic_dec_and_test(&io->md->pending)) + /* nudge anyone waiting on suspend queue */ + wake_up(&io->md->wait); + + bio_endio(io->bio, io->bio->bi_size, io->error); + free_io(io->md, io); + } +} + +static int clone_endio(struct bio *bio, unsigned int done, int error) +{ + int r = 0; + struct target_io *tio = bio->bi_private; + struct dm_io *io = tio->io; + dm_endio_fn endio = tio->ti->type->end_io; + + if (bio->bi_size) + return 1; + + if (!bio_flagged(bio, BIO_UPTODATE) && !error) + error = -EIO; + + if (endio) { + r = endio(tio->ti, bio, error, &tio->info); + if (r < 0) + error = r; + + else if (r > 0) + /* the target wants another shot at the io */ + return 1; + } + + free_tio(io->md, tio); + dec_pending(io, error); + bio_put(bio); + return r; +} + +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 target_io *tio) +{ + int r; + + /* + * 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); + r = ti->type->map(ti, clone, &tio->info); + if (r > 0) + /* the bio has been remapped so dispatch it */ + generic_make_request(clone); + + else if (r < 0) { + /* error the io and bail out */ + struct dm_io *io = tio->io; + free_tio(tio->io->md, tio); + dec_pending(io, -EIO); + bio_put(clone); + } +} + +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; +}; + +/* + * 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 *clone; + struct bio_vec *bv = bio->bi_io_vec + idx; + + clone = bio_alloc_bioset(GFP_NOIO, 1, dm_set); + *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; + + 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 *clone; + + clone = bio_clone(bio, GFP_NOIO); + 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 void __clone_and_map(struct clone_info *ci) +{ + struct bio *clone, *bio = ci->bio; + struct dm_target *ti = dm_table_find_target(ci->map, ci->sector); + sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti); + struct target_io *tio; + + /* + * 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); + __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); + __map_bio(ti, clone, tio); + + ci->sector += len; + ci->sector_count -= len; + ci->idx = i; + + } else { + /* + * Create two copy bios to deal with io that has + * been split across a target. + */ + struct bio_vec *bv = bio->bi_io_vec + ci->idx; + + clone = split_bvec(bio, ci->sector, ci->idx, + bv->bv_offset, max); + __map_bio(ti, clone, tio); + + ci->sector += max; + ci->sector_count -= max; + ti = dm_table_find_target(ci->map, ci->sector); + + len = to_sector(bv->bv_len) - max; + clone = split_bvec(bio, ci->sector, ci->idx, + bv->bv_offset + to_bytes(max), len); + tio = alloc_tio(ci->md); + tio->io = ci->io; + tio->ti = ti; + memset(&tio->info, 0, sizeof(tio->info)); + __map_bio(ti, clone, tio); + + ci->sector += len; + ci->sector_count -= len; + ci->idx++; + } +} + +/* + * Split the bio into several clones. + */ +static void __split_bio(struct mapped_device *md, struct bio *bio) +{ + struct clone_info ci; + + ci.map = dm_get_table(md); + if (!ci.map) { + bio_io_error(bio, bio->bi_size); + return; + } + + 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; + + atomic_inc(&md->pending); + while (ci.sector_count) + __clone_and_map(&ci); + + /* drop the extra reference count */ + dec_pending(ci.io, 0); + dm_table_put(ci.map); +} +/*----------------------------------------------------------------- + * CRUD END + *---------------------------------------------------------------*/ + +/* + * The request function that just remaps the bio built up by + * dm_merge_bvec. + */ +static int dm_request(request_queue_t *q, struct bio *bio) +{ + int r; + struct mapped_device *md = q->queuedata; + + down_read(&md->lock); + + /* + * If we're suspended we have to queue + * this io for later. + */ + while (test_bit(DMF_BLOCK_IO, &md->flags)) { + up_read(&md->lock); + + if (bio_rw(bio) == READA) { + bio_io_error(bio, bio->bi_size); + return 0; + } + + r = queue_io(md, bio); + if (r < 0) { + bio_io_error(bio, bio->bi_size); + return 0; + + } else if (r == 0) + return 0; /* deferred successfully */ + + /* + * We're in a while loop, because someone could suspend + * before we get to the following read lock. + */ + down_read(&md->lock); + } + + __split_bio(md, bio); + up_read(&md->lock); + return 0; +} + +static int dm_flush_all(request_queue_t *q, struct gendisk *disk, + sector_t *error_sector) +{ + struct mapped_device *md = q->queuedata; + struct dm_table *map = dm_get_table(md); + int ret = -ENXIO; + + if (map) { + ret = dm_table_flush_all(md->map); + dm_table_put(map); + } + + return ret; +} + +static void dm_unplug_all(request_queue_t *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; + struct mapped_device *md = (struct mapped_device *) congested_data; + struct dm_table *map = dm_get_table(md); + + if (!map || test_bit(DMF_BLOCK_IO, &md->flags)) + r = 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 DECLARE_MUTEX(_minor_lock); +static DEFINE_IDR(_minor_idr); + +static void free_minor(unsigned int minor) +{ + down(&_minor_lock); + idr_remove(&_minor_idr, minor); + up(&_minor_lock); +} + +/* + * See if the device with a specific minor # is free. + */ +static int specific_minor(struct mapped_device *md, unsigned int minor) +{ + int r, m; + + if (minor >= (1 << MINORBITS)) + return -EINVAL; + + down(&_minor_lock); + + if (idr_find(&_minor_idr, minor)) { + r = -EBUSY; + goto out; + } + + r = idr_pre_get(&_minor_idr, GFP_KERNEL); + if (!r) { + r = -ENOMEM; + goto out; + } + + r = idr_get_new_above(&_minor_idr, md, minor, &m); + if (r) { + goto out; + } + + if (m != minor) { + idr_remove(&_minor_idr, m); + r = -EBUSY; + goto out; + } + +out: + up(&_minor_lock); + return r; +} + +static int next_free_minor(struct mapped_device *md, unsigned int *minor) +{ + int r; + unsigned int m; + + down(&_minor_lock); + + r = idr_pre_get(&_minor_idr, GFP_KERNEL); + if (!r) { + r = -ENOMEM; + goto out; + } + + r = idr_get_new(&_minor_idr, md, &m); + if (r) { + goto out; + } + + if (m >= (1 << MINORBITS)) { + idr_remove(&_minor_idr, m); + r = -ENOSPC; + goto out; + } + + *minor = m; + +out: + up(&_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(unsigned int minor, int persistent) +{ + int r; + struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL); + + if (!md) { + DMWARN("unable to allocate device, out of memory."); + return NULL; + } + + /* get a minor number for the dev */ + r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor); + if (r < 0) + goto bad1; + + memset(md, 0, sizeof(*md)); + init_rwsem(&md->lock); + rwlock_init(&md->map_lock); + atomic_set(&md->holders, 1); + atomic_set(&md->event_nr, 0); + + md->queue = blk_alloc_queue(GFP_KERNEL); + if (!md->queue) + goto bad1; + + 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); + md->queue->unplug_fn = dm_unplug_all; + md->queue->issue_flush_fn = dm_flush_all; + + md->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab, + mempool_free_slab, _io_cache); + if (!md->io_pool) + goto bad2; + + md->tio_pool = mempool_create(MIN_IOS, mempool_alloc_slab, + mempool_free_slab, _tio_cache); + if (!md->tio_pool) + goto bad3; + + md->disk = alloc_disk(1); + if (!md->disk) + goto bad4; + + 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); + + atomic_set(&md->pending, 0); + init_waitqueue_head(&md->wait); + init_waitqueue_head(&md->eventq); + + return md; + + bad4: + mempool_destroy(md->tio_pool); + bad3: + mempool_destroy(md->io_pool); + bad2: + blk_put_queue(md->queue); + free_minor(minor); + bad1: + kfree(md); + return NULL; +} + +static void free_dev(struct mapped_device *md) +{ + free_minor(md->disk->first_minor); + mempool_destroy(md->tio_pool); + mempool_destroy(md->io_pool); + del_gendisk(md->disk); + put_disk(md->disk); + blk_put_queue(md->queue); + kfree(md); +} + +/* + * Bind a table to the device. + */ +static void event_callback(void *context) +{ + struct mapped_device *md = (struct mapped_device *) context; + + atomic_inc(&md->event_nr); + wake_up(&md->eventq); +} + +static void __set_size(struct gendisk *disk, sector_t size) +{ + struct block_device *bdev; + + set_capacity(disk, size); + bdev = bdget_disk(disk, 0); + if (bdev) { + down(&bdev->bd_inode->i_sem); + i_size_write(bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); + up(&bdev->bd_inode->i_sem); + bdput(bdev); + } +} + +static int __bind(struct mapped_device *md, struct dm_table *t) +{ + request_queue_t *q = md->queue; + sector_t size; + + size = dm_table_get_size(t); + __set_size(md->disk, size); + if (size == 0) + return 0; + + write_lock(&md->map_lock); + md->map = t; + write_unlock(&md->map_lock); + + dm_table_get(t); + dm_table_event_callback(md->map, event_callback, md); + dm_table_set_restrictions(t, q); + 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. + */ +static int create_aux(unsigned int minor, int persistent, + struct mapped_device **result) +{ + struct mapped_device *md; + + md = alloc_dev(minor, persistent); + if (!md) + return -ENXIO; + + *result = md; + return 0; +} + +int dm_create(struct mapped_device **result) +{ + return create_aux(0, 0, result); +} + +int dm_create_with_minor(unsigned int minor, struct mapped_device **result) +{ + return create_aux(minor, 1, result); +} + +void *dm_get_mdptr(dev_t dev) +{ + struct mapped_device *md; + void *mdptr = NULL; + unsigned minor = MINOR(dev); + + if (MAJOR(dev) != _major || minor >= (1 << MINORBITS)) + return NULL; + + down(&_minor_lock); + + md = idr_find(&_minor_idr, minor); + + if (md && (dm_disk(md)->first_minor == minor)) + mdptr = md->interface_ptr; + + up(&_minor_lock); + + return mdptr; +} + +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); +} + +void dm_put(struct mapped_device *md) +{ + struct dm_table *map = dm_get_table(md); + + if (atomic_dec_and_test(&md->holders)) { + if (!test_bit(DMF_SUSPENDED, &md->flags) && map) { + dm_table_presuspend_targets(map); + dm_table_postsuspend_targets(map); + } + __unbind(md); + free_dev(md); + } + + dm_table_put(map); +} + +/* + * Process the deferred bios + */ +static void __flush_deferred_io(struct mapped_device *md, struct bio *c) +{ + struct bio *n; + + while (c) { + n = c->bi_next; + c->bi_next = NULL; + __split_bio(md, c); + c = n; + } +} + +/* + * Swap in a new table (destroying old one). + */ +int dm_swap_table(struct mapped_device *md, struct dm_table *table) +{ + int r; + + down_write(&md->lock); + + /* device must be suspended */ + if (!test_bit(DMF_SUSPENDED, &md->flags)) { + up_write(&md->lock); + return -EPERM; + } + + __unbind(md); + r = __bind(md, table); + if (r) + return r; + + up_write(&md->lock); + return 0; +} + +/* + * Functions to lock and unlock any filesystem running on the + * device. + */ +static int __lock_fs(struct mapped_device *md) +{ + struct block_device *bdev; + + if (test_and_set_bit(DMF_FS_LOCKED, &md->flags)) + return 0; + + bdev = bdget_disk(md->disk, 0); + if (!bdev) { + DMWARN("bdget failed in __lock_fs"); + return -ENOMEM; + } + + WARN_ON(md->frozen_sb); + md->frozen_sb = freeze_bdev(bdev); + /* don't bdput right now, we don't want the bdev + * to go away while it is locked. We'll bdput + * in __unlock_fs + */ + return 0; +} + +static int __unlock_fs(struct mapped_device *md) +{ + struct block_device *bdev; + + if (!test_and_clear_bit(DMF_FS_LOCKED, &md->flags)) + return 0; + + bdev = bdget_disk(md->disk, 0); + if (!bdev) { + DMWARN("bdget failed in __unlock_fs"); + return -ENOMEM; + } + + thaw_bdev(bdev, md->frozen_sb); + md->frozen_sb = NULL; + bdput(bdev); + bdput(bdev); + return 0; +} + +/* + * 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) +{ + struct dm_table *map; + DECLARE_WAITQUEUE(wait, current); + + /* Flush I/O to the device. */ + down_read(&md->lock); + if (test_bit(DMF_BLOCK_IO, &md->flags)) { + up_read(&md->lock); + return -EINVAL; + } + + map = dm_get_table(md); + if (map) + dm_table_presuspend_targets(map); + __lock_fs(md); + + up_read(&md->lock); + + /* + * First we set the BLOCK_IO flag so no more ios will be + * mapped. + */ + down_write(&md->lock); + if (test_bit(DMF_BLOCK_IO, &md->flags)) { + /* + * If we get here we know another thread is + * trying to suspend as well, so we leave the fs + * locked for this thread. + */ + up_write(&md->lock); + return -EINVAL; + } + + set_bit(DMF_BLOCK_IO, &md->flags); + add_wait_queue(&md->wait, &wait); + up_write(&md->lock); + + /* unplug */ + if (map) { + dm_table_unplug_all(map); + dm_table_put(map); + } + + /* + * Then we wait for the already mapped ios to + * complete. + */ + while (1) { + set_current_state(TASK_INTERRUPTIBLE); + + if (!atomic_read(&md->pending) || signal_pending(current)) + break; + + io_schedule(); + } + set_current_state(TASK_RUNNING); + + down_write(&md->lock); + remove_wait_queue(&md->wait, &wait); + + /* were we interrupted ? */ + if (atomic_read(&md->pending)) { + __unlock_fs(md); + clear_bit(DMF_BLOCK_IO, &md->flags); + up_write(&md->lock); + return -EINTR; + } + + set_bit(DMF_SUSPENDED, &md->flags); + + map = dm_get_table(md); + if (map) + dm_table_postsuspend_targets(map); + dm_table_put(map); + up_write(&md->lock); + + return 0; +} + +int dm_resume(struct mapped_device *md) +{ + struct bio *def; + struct dm_table *map = dm_get_table(md); + + down_write(&md->lock); + if (!map || + !test_bit(DMF_SUSPENDED, &md->flags) || + !dm_table_get_size(map)) { + up_write(&md->lock); + dm_table_put(map); + return -EINVAL; + } + + dm_table_resume_targets(map); + clear_bit(DMF_SUSPENDED, &md->flags); + clear_bit(DMF_BLOCK_IO, &md->flags); + + def = bio_list_get(&md->deferred); + __flush_deferred_io(md, def); + up_write(&md->lock); + __unlock_fs(md); + dm_table_unplug_all(map); + dm_table_put(map); + + return 0; +} + +/*----------------------------------------------------------------- + * Event notification. + *---------------------------------------------------------------*/ +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))); +} + +/* + * 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); +} + +static struct block_device_operations dm_blk_dops = { + .open = dm_blk_open, + .release = dm_blk_close, + .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"); |