2 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
5 * This file is released under the GPL.
9 #include "dm-bio-list.h"
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/blkpg.h>
15 #include <linux/bio.h>
16 #include <linux/buffer_head.h>
17 #include <linux/mempool.h>
18 #include <linux/slab.h>
19 #include <linux/idr.h>
20 #include <linux/blktrace_api.h>
22 static const char *_name = DM_NAME;
24 static unsigned int major = 0;
25 static unsigned int _major = 0;
28 * One of these is allocated per bio.
31 struct mapped_device *md;
35 unsigned long start_time;
39 * One of these is allocated per target within a bio. Hopefully
40 * this will be simplified out one day.
48 union map_info *dm_get_mapinfo(struct bio *bio)
50 if (bio && bio->bi_private)
51 return &((struct target_io *)bio->bi_private)->info;
56 * Bits for the md->flags field.
58 #define DMF_BLOCK_IO 0
59 #define DMF_SUSPENDED 1
62 struct mapped_device {
63 struct rw_semaphore io_lock;
64 struct semaphore suspend_lock;
70 request_queue_t *queue;
77 * A list of ios that arrived while we were suspended.
80 wait_queue_head_t wait;
81 struct bio_list deferred;
84 * The current mapping.
89 * io objects are allocated from here.
98 wait_queue_head_t eventq;
101 * freeze/thaw support require holding onto a super block
103 struct super_block *frozen_sb;
104 struct block_device *suspended_bdev;
108 static kmem_cache_t *_io_cache;
109 static kmem_cache_t *_tio_cache;
111 static struct bio_set *dm_set;
113 static int __init local_init(void)
117 dm_set = bioset_create(16, 16, 4);
121 /* allocate a slab for the dm_ios */
122 _io_cache = kmem_cache_create("dm_io",
123 sizeof(struct dm_io), 0, 0, NULL, NULL);
127 /* allocate a slab for the target ios */
128 _tio_cache = kmem_cache_create("dm_tio", sizeof(struct target_io),
131 kmem_cache_destroy(_io_cache);
136 r = register_blkdev(_major, _name);
138 kmem_cache_destroy(_tio_cache);
139 kmem_cache_destroy(_io_cache);
149 static void local_exit(void)
151 kmem_cache_destroy(_tio_cache);
152 kmem_cache_destroy(_io_cache);
156 if (unregister_blkdev(_major, _name) < 0)
157 DMERR("devfs_unregister_blkdev failed");
161 DMINFO("cleaned up");
164 int (*_inits[])(void) __initdata = {
172 void (*_exits[])(void) = {
180 static int __init dm_init(void)
182 const int count = ARRAY_SIZE(_inits);
186 for (i = 0; i < count; i++) {
201 static void __exit dm_exit(void)
203 int i = ARRAY_SIZE(_exits);
210 * Block device functions
212 static int dm_blk_open(struct inode *inode, struct file *file)
214 struct mapped_device *md;
216 md = inode->i_bdev->bd_disk->private_data;
221 static int dm_blk_close(struct inode *inode, struct file *file)
223 struct mapped_device *md;
225 md = inode->i_bdev->bd_disk->private_data;
230 static inline struct dm_io *alloc_io(struct mapped_device *md)
232 return mempool_alloc(md->io_pool, GFP_NOIO);
235 static inline void free_io(struct mapped_device *md, struct dm_io *io)
237 mempool_free(io, md->io_pool);
240 static inline struct target_io *alloc_tio(struct mapped_device *md)
242 return mempool_alloc(md->tio_pool, GFP_NOIO);
245 static inline void free_tio(struct mapped_device *md, struct target_io *tio)
247 mempool_free(tio, md->tio_pool);
250 static void start_io_acct(struct dm_io *io)
252 struct mapped_device *md = io->md;
254 io->start_time = jiffies;
257 disk_round_stats(dm_disk(md));
259 dm_disk(md)->in_flight = atomic_inc_return(&md->pending);
262 static int end_io_acct(struct dm_io *io)
264 struct mapped_device *md = io->md;
265 struct bio *bio = io->bio;
266 unsigned long duration = jiffies - io->start_time;
268 int rw = bio_data_dir(bio);
271 disk_round_stats(dm_disk(md));
273 dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);
275 disk_stat_add(dm_disk(md), ticks[rw], duration);
281 * Add the bio to the list of deferred io.
283 static int queue_io(struct mapped_device *md, struct bio *bio)
285 down_write(&md->io_lock);
287 if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
288 up_write(&md->io_lock);
292 bio_list_add(&md->deferred, bio);
294 up_write(&md->io_lock);
295 return 0; /* deferred successfully */
299 * Everyone (including functions in this file), should use this
300 * function to access the md->map field, and make sure they call
301 * dm_table_put() when finished.
303 struct dm_table *dm_get_table(struct mapped_device *md)
307 read_lock(&md->map_lock);
311 read_unlock(&md->map_lock);
316 /*-----------------------------------------------------------------
318 * A more elegant soln is in the works that uses the queue
319 * merge fn, unfortunately there are a couple of changes to
320 * the block layer that I want to make for this. So in the
321 * interests of getting something for people to use I give
322 * you this clearly demarcated crap.
323 *---------------------------------------------------------------*/
326 * Decrements the number of outstanding ios that a bio has been
327 * cloned into, completing the original io if necc.
329 static void dec_pending(struct dm_io *io, int error)
334 if (atomic_dec_and_test(&io->io_count)) {
336 /* nudge anyone waiting on suspend queue */
337 wake_up(&io->md->wait);
339 blk_add_trace_bio(io->md->queue, io->bio, BLK_TA_COMPLETE);
341 bio_endio(io->bio, io->bio->bi_size, io->error);
346 static int clone_endio(struct bio *bio, unsigned int done, int error)
349 struct target_io *tio = bio->bi_private;
350 struct dm_io *io = tio->io;
351 dm_endio_fn endio = tio->ti->type->end_io;
356 if (!bio_flagged(bio, BIO_UPTODATE) && !error)
360 r = endio(tio->ti, bio, error, &tio->info);
365 /* the target wants another shot at the io */
369 free_tio(io->md, tio);
370 dec_pending(io, error);
375 static sector_t max_io_len(struct mapped_device *md,
376 sector_t sector, struct dm_target *ti)
378 sector_t offset = sector - ti->begin;
379 sector_t len = ti->len - offset;
382 * Does the target need to split even further ?
386 boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
395 static void __map_bio(struct dm_target *ti, struct bio *clone,
396 struct target_io *tio)
404 BUG_ON(!clone->bi_size);
406 clone->bi_end_io = clone_endio;
407 clone->bi_private = tio;
410 * Map the clone. If r == 0 we don't need to do
411 * anything, the target has assumed ownership of
414 atomic_inc(&tio->io->io_count);
415 sector = clone->bi_sector;
416 r = ti->type->map(ti, clone, &tio->info);
418 /* the bio has been remapped so dispatch it */
420 blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
421 tio->io->bio->bi_bdev->bd_dev, sector,
424 generic_make_request(clone);
428 /* error the io and bail out */
429 struct dm_io *io = tio->io;
430 free_tio(tio->io->md, tio);
437 struct mapped_device *md;
438 struct dm_table *map;
442 sector_t sector_count;
446 static void dm_bio_destructor(struct bio *bio)
448 bio_free(bio, dm_set);
452 * Creates a little bio that is just does part of a bvec.
454 static struct bio *split_bvec(struct bio *bio, sector_t sector,
455 unsigned short idx, unsigned int offset,
459 struct bio_vec *bv = bio->bi_io_vec + idx;
461 clone = bio_alloc_bioset(GFP_NOIO, 1, dm_set);
462 clone->bi_destructor = dm_bio_destructor;
463 *clone->bi_io_vec = *bv;
465 clone->bi_sector = sector;
466 clone->bi_bdev = bio->bi_bdev;
467 clone->bi_rw = bio->bi_rw;
469 clone->bi_size = to_bytes(len);
470 clone->bi_io_vec->bv_offset = offset;
471 clone->bi_io_vec->bv_len = clone->bi_size;
477 * Creates a bio that consists of range of complete bvecs.
479 static struct bio *clone_bio(struct bio *bio, sector_t sector,
480 unsigned short idx, unsigned short bv_count,
485 clone = bio_clone(bio, GFP_NOIO);
486 clone->bi_sector = sector;
488 clone->bi_vcnt = idx + bv_count;
489 clone->bi_size = to_bytes(len);
490 clone->bi_flags &= ~(1 << BIO_SEG_VALID);
495 static void __clone_and_map(struct clone_info *ci)
497 struct bio *clone, *bio = ci->bio;
498 struct dm_target *ti = dm_table_find_target(ci->map, ci->sector);
499 sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti);
500 struct target_io *tio;
503 * Allocate a target io object.
505 tio = alloc_tio(ci->md);
508 memset(&tio->info, 0, sizeof(tio->info));
510 if (ci->sector_count <= max) {
512 * Optimise for the simple case where we can do all of
513 * the remaining io with a single clone.
515 clone = clone_bio(bio, ci->sector, ci->idx,
516 bio->bi_vcnt - ci->idx, ci->sector_count);
517 __map_bio(ti, clone, tio);
518 ci->sector_count = 0;
520 } else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
522 * There are some bvecs that don't span targets.
523 * Do as many of these as possible.
526 sector_t remaining = max;
529 for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) {
530 bv_len = to_sector(bio->bi_io_vec[i].bv_len);
532 if (bv_len > remaining)
539 clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len);
540 __map_bio(ti, clone, tio);
543 ci->sector_count -= len;
548 * Handle a bvec that must be split between two or more targets.
550 struct bio_vec *bv = bio->bi_io_vec + ci->idx;
551 sector_t remaining = to_sector(bv->bv_len);
552 unsigned int offset = 0;
556 ti = dm_table_find_target(ci->map, ci->sector);
557 max = max_io_len(ci->md, ci->sector, ti);
559 tio = alloc_tio(ci->md);
562 memset(&tio->info, 0, sizeof(tio->info));
565 len = min(remaining, max);
567 clone = split_bvec(bio, ci->sector, ci->idx,
568 bv->bv_offset + offset, len);
570 __map_bio(ti, clone, tio);
573 ci->sector_count -= len;
574 offset += to_bytes(len);
575 } while (remaining -= len);
582 * Split the bio into several clones.
584 static void __split_bio(struct mapped_device *md, struct bio *bio)
586 struct clone_info ci;
588 ci.map = dm_get_table(md);
590 bio_io_error(bio, bio->bi_size);
596 ci.io = alloc_io(md);
598 atomic_set(&ci.io->io_count, 1);
601 ci.sector = bio->bi_sector;
602 ci.sector_count = bio_sectors(bio);
603 ci.idx = bio->bi_idx;
605 start_io_acct(ci.io);
606 while (ci.sector_count)
607 __clone_and_map(&ci);
609 /* drop the extra reference count */
610 dec_pending(ci.io, 0);
611 dm_table_put(ci.map);
613 /*-----------------------------------------------------------------
615 *---------------------------------------------------------------*/
618 * The request function that just remaps the bio built up by
621 static int dm_request(request_queue_t *q, struct bio *bio)
624 int rw = bio_data_dir(bio);
625 struct mapped_device *md = q->queuedata;
627 down_read(&md->io_lock);
629 disk_stat_inc(dm_disk(md), ios[rw]);
630 disk_stat_add(dm_disk(md), sectors[rw], bio_sectors(bio));
633 * If we're suspended we have to queue
636 while (test_bit(DMF_BLOCK_IO, &md->flags)) {
637 up_read(&md->io_lock);
639 if (bio_rw(bio) == READA) {
640 bio_io_error(bio, bio->bi_size);
644 r = queue_io(md, bio);
646 bio_io_error(bio, bio->bi_size);
650 return 0; /* deferred successfully */
653 * We're in a while loop, because someone could suspend
654 * before we get to the following read lock.
656 down_read(&md->io_lock);
659 __split_bio(md, bio);
660 up_read(&md->io_lock);
664 static int dm_flush_all(request_queue_t *q, struct gendisk *disk,
665 sector_t *error_sector)
667 struct mapped_device *md = q->queuedata;
668 struct dm_table *map = dm_get_table(md);
672 ret = dm_table_flush_all(map);
679 static void dm_unplug_all(request_queue_t *q)
681 struct mapped_device *md = q->queuedata;
682 struct dm_table *map = dm_get_table(md);
685 dm_table_unplug_all(map);
690 static int dm_any_congested(void *congested_data, int bdi_bits)
693 struct mapped_device *md = (struct mapped_device *) congested_data;
694 struct dm_table *map = dm_get_table(md);
696 if (!map || test_bit(DMF_BLOCK_IO, &md->flags))
699 r = dm_table_any_congested(map, bdi_bits);
705 /*-----------------------------------------------------------------
706 * An IDR is used to keep track of allocated minor numbers.
707 *---------------------------------------------------------------*/
708 static DECLARE_MUTEX(_minor_lock);
709 static DEFINE_IDR(_minor_idr);
711 static void free_minor(unsigned int minor)
714 idr_remove(&_minor_idr, minor);
719 * See if the device with a specific minor # is free.
721 static int specific_minor(struct mapped_device *md, unsigned int minor)
725 if (minor >= (1 << MINORBITS))
730 if (idr_find(&_minor_idr, minor)) {
735 r = idr_pre_get(&_minor_idr, GFP_KERNEL);
741 r = idr_get_new_above(&_minor_idr, md, minor, &m);
747 idr_remove(&_minor_idr, m);
757 static int next_free_minor(struct mapped_device *md, unsigned int *minor)
764 r = idr_pre_get(&_minor_idr, GFP_KERNEL);
770 r = idr_get_new(&_minor_idr, md, &m);
775 if (m >= (1 << MINORBITS)) {
776 idr_remove(&_minor_idr, m);
788 static struct block_device_operations dm_blk_dops;
791 * Allocate and initialise a blank device with a given minor.
793 static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
796 struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
799 DMWARN("unable to allocate device, out of memory.");
803 /* get a minor number for the dev */
804 r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
808 memset(md, 0, sizeof(*md));
809 init_rwsem(&md->io_lock);
810 init_MUTEX(&md->suspend_lock);
811 rwlock_init(&md->map_lock);
812 atomic_set(&md->holders, 1);
813 atomic_set(&md->event_nr, 0);
815 md->queue = blk_alloc_queue(GFP_KERNEL);
819 md->queue->queuedata = md;
820 md->queue->backing_dev_info.congested_fn = dm_any_congested;
821 md->queue->backing_dev_info.congested_data = md;
822 blk_queue_make_request(md->queue, dm_request);
823 blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
824 md->queue->unplug_fn = dm_unplug_all;
825 md->queue->issue_flush_fn = dm_flush_all;
827 md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
831 md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache);
835 md->disk = alloc_disk(1);
839 md->disk->major = _major;
840 md->disk->first_minor = minor;
841 md->disk->fops = &dm_blk_dops;
842 md->disk->queue = md->queue;
843 md->disk->private_data = md;
844 sprintf(md->disk->disk_name, "dm-%d", minor);
846 format_dev_t(md->name, MKDEV(_major, minor));
848 atomic_set(&md->pending, 0);
849 init_waitqueue_head(&md->wait);
850 init_waitqueue_head(&md->eventq);
855 mempool_destroy(md->tio_pool);
857 mempool_destroy(md->io_pool);
859 blk_cleanup_queue(md->queue);
866 static void free_dev(struct mapped_device *md)
868 unsigned int minor = md->disk->first_minor;
870 if (md->suspended_bdev) {
871 thaw_bdev(md->suspended_bdev, NULL);
872 bdput(md->suspended_bdev);
874 mempool_destroy(md->tio_pool);
875 mempool_destroy(md->io_pool);
876 del_gendisk(md->disk);
879 blk_cleanup_queue(md->queue);
884 * Bind a table to the device.
886 static void event_callback(void *context)
888 struct mapped_device *md = (struct mapped_device *) context;
890 atomic_inc(&md->event_nr);
891 wake_up(&md->eventq);
894 static void __set_size(struct mapped_device *md, sector_t size)
896 set_capacity(md->disk, size);
898 mutex_lock(&md->suspended_bdev->bd_inode->i_mutex);
899 i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
900 mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex);
903 static int __bind(struct mapped_device *md, struct dm_table *t)
905 request_queue_t *q = md->queue;
908 size = dm_table_get_size(t);
909 __set_size(md, size);
914 dm_table_event_callback(t, event_callback, md);
916 write_lock(&md->map_lock);
918 dm_table_set_restrictions(t, q);
919 write_unlock(&md->map_lock);
924 static void __unbind(struct mapped_device *md)
926 struct dm_table *map = md->map;
931 dm_table_event_callback(map, NULL, NULL);
932 write_lock(&md->map_lock);
934 write_unlock(&md->map_lock);
939 * Constructor for a new device.
941 static int create_aux(unsigned int minor, int persistent,
942 struct mapped_device **result)
944 struct mapped_device *md;
946 md = alloc_dev(minor, persistent);
954 int dm_create(struct mapped_device **result)
956 return create_aux(0, 0, result);
959 int dm_create_with_minor(unsigned int minor, struct mapped_device **result)
961 return create_aux(minor, 1, result);
964 static struct mapped_device *dm_find_md(dev_t dev)
966 struct mapped_device *md;
967 unsigned minor = MINOR(dev);
969 if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
974 md = idr_find(&_minor_idr, minor);
975 if (!md || (dm_disk(md)->first_minor != minor))
983 struct mapped_device *dm_get_md(dev_t dev)
985 struct mapped_device *md = dm_find_md(dev);
993 void *dm_get_mdptr(dev_t dev)
995 struct mapped_device *md;
998 md = dm_find_md(dev);
1000 mdptr = md->interface_ptr;
1004 void dm_set_mdptr(struct mapped_device *md, void *ptr)
1006 md->interface_ptr = ptr;
1009 void dm_get(struct mapped_device *md)
1011 atomic_inc(&md->holders);
1014 void dm_put(struct mapped_device *md)
1016 struct dm_table *map = dm_get_table(md);
1018 if (atomic_dec_and_test(&md->holders)) {
1019 if (!dm_suspended(md)) {
1020 dm_table_presuspend_targets(map);
1021 dm_table_postsuspend_targets(map);
1031 * Process the deferred bios
1033 static void __flush_deferred_io(struct mapped_device *md, struct bio *c)
1046 * Swap in a new table (destroying old one).
1048 int dm_swap_table(struct mapped_device *md, struct dm_table *table)
1052 down(&md->suspend_lock);
1054 /* device must be suspended */
1055 if (!dm_suspended(md))
1059 r = __bind(md, table);
1062 up(&md->suspend_lock);
1067 * Functions to lock and unlock any filesystem running on the
1070 static int lock_fs(struct mapped_device *md)
1074 WARN_ON(md->frozen_sb);
1076 md->frozen_sb = freeze_bdev(md->suspended_bdev);
1077 if (IS_ERR(md->frozen_sb)) {
1078 r = PTR_ERR(md->frozen_sb);
1079 md->frozen_sb = NULL;
1083 set_bit(DMF_FROZEN, &md->flags);
1085 /* don't bdput right now, we don't want the bdev
1086 * to go away while it is locked.
1091 static void unlock_fs(struct mapped_device *md)
1093 if (!test_bit(DMF_FROZEN, &md->flags))
1096 thaw_bdev(md->suspended_bdev, md->frozen_sb);
1097 md->frozen_sb = NULL;
1098 clear_bit(DMF_FROZEN, &md->flags);
1102 * We need to be able to change a mapping table under a mounted
1103 * filesystem. For example we might want to move some data in
1104 * the background. Before the table can be swapped with
1105 * dm_bind_table, dm_suspend must be called to flush any in
1106 * flight bios and ensure that any further io gets deferred.
1108 int dm_suspend(struct mapped_device *md, int do_lockfs)
1110 struct dm_table *map = NULL;
1111 DECLARE_WAITQUEUE(wait, current);
1115 down(&md->suspend_lock);
1117 if (dm_suspended(md))
1120 map = dm_get_table(md);
1122 /* This does not get reverted if there's an error later. */
1123 dm_table_presuspend_targets(map);
1125 md->suspended_bdev = bdget_disk(md->disk, 0);
1126 if (!md->suspended_bdev) {
1127 DMWARN("bdget failed in dm_suspend");
1132 /* Flush I/O to the device. */
1140 * First we set the BLOCK_IO flag so no more ios will be mapped.
1142 down_write(&md->io_lock);
1143 set_bit(DMF_BLOCK_IO, &md->flags);
1145 add_wait_queue(&md->wait, &wait);
1146 up_write(&md->io_lock);
1150 dm_table_unplug_all(map);
1153 * Then we wait for the already mapped ios to
1157 set_current_state(TASK_INTERRUPTIBLE);
1159 if (!atomic_read(&md->pending) || signal_pending(current))
1164 set_current_state(TASK_RUNNING);
1166 down_write(&md->io_lock);
1167 remove_wait_queue(&md->wait, &wait);
1169 /* were we interrupted ? */
1171 if (atomic_read(&md->pending)) {
1172 clear_bit(DMF_BLOCK_IO, &md->flags);
1173 def = bio_list_get(&md->deferred);
1174 __flush_deferred_io(md, def);
1175 up_write(&md->io_lock);
1179 up_write(&md->io_lock);
1181 dm_table_postsuspend_targets(map);
1183 set_bit(DMF_SUSPENDED, &md->flags);
1188 if (r && md->suspended_bdev) {
1189 bdput(md->suspended_bdev);
1190 md->suspended_bdev = NULL;
1194 up(&md->suspend_lock);
1198 int dm_resume(struct mapped_device *md)
1202 struct dm_table *map = NULL;
1204 down(&md->suspend_lock);
1205 if (!dm_suspended(md))
1208 map = dm_get_table(md);
1209 if (!map || !dm_table_get_size(map))
1212 dm_table_resume_targets(map);
1214 down_write(&md->io_lock);
1215 clear_bit(DMF_BLOCK_IO, &md->flags);
1217 def = bio_list_get(&md->deferred);
1218 __flush_deferred_io(md, def);
1219 up_write(&md->io_lock);
1223 bdput(md->suspended_bdev);
1224 md->suspended_bdev = NULL;
1226 clear_bit(DMF_SUSPENDED, &md->flags);
1228 dm_table_unplug_all(map);
1234 up(&md->suspend_lock);
1239 /*-----------------------------------------------------------------
1240 * Event notification.
1241 *---------------------------------------------------------------*/
1242 uint32_t dm_get_event_nr(struct mapped_device *md)
1244 return atomic_read(&md->event_nr);
1247 int dm_wait_event(struct mapped_device *md, int event_nr)
1249 return wait_event_interruptible(md->eventq,
1250 (event_nr != atomic_read(&md->event_nr)));
1254 * The gendisk is only valid as long as you have a reference
1257 struct gendisk *dm_disk(struct mapped_device *md)
1262 int dm_suspended(struct mapped_device *md)
1264 return test_bit(DMF_SUSPENDED, &md->flags);
1267 static struct block_device_operations dm_blk_dops = {
1268 .open = dm_blk_open,
1269 .release = dm_blk_close,
1270 .owner = THIS_MODULE
1273 EXPORT_SYMBOL(dm_get_mapinfo);
1278 module_init(dm_init);
1279 module_exit(dm_exit);
1281 module_param(major, uint, 0);
1282 MODULE_PARM_DESC(major, "The major number of the device mapper");
1283 MODULE_DESCRIPTION(DM_NAME " driver");
1284 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
1285 MODULE_LICENSE("GPL");