1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8 #include "dm-bio-record.h"
9
10 #include <linux/init.h>
11 #include <linux/mempool.h>
12 #include <linux/module.h>
13 #include <linux/pagemap.h>
14 #include <linux/slab.h>
15 #include <linux/workqueue.h>
16 #include <linux/device-mapper.h>
17 #include <linux/dm-io.h>
18 #include <linux/dm-dirty-log.h>
19 #include <linux/dm-kcopyd.h>
20 #include <linux/dm-region-hash.h>
21
22 #define DM_MSG_PREFIX "raid1"
23
24 #define MAX_RECOVERY 1 /* Maximum number of regions recovered in parallel. */
25
26 #define DM_RAID1_HANDLE_ERRORS 0x01
27 #define errors_handled(p) ((p)->features & DM_RAID1_HANDLE_ERRORS)
28
29 static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
30
31 /*-----------------------------------------------------------------
32 * Mirror set structures.
33 *---------------------------------------------------------------*/
34 enum dm_raid1_error {
35 DM_RAID1_WRITE_ERROR,
36 DM_RAID1_FLUSH_ERROR,
37 DM_RAID1_SYNC_ERROR,
38 DM_RAID1_READ_ERROR
39 };
40
41 struct mirror {
42 struct mirror_set *ms;
43 atomic_t error_count;
44 unsigned long error_type;
45 struct dm_dev *dev;
46 sector_t offset;
47 };
48
49 struct mirror_set {
50 struct dm_target *ti;
51 struct list_head list;
52
53 uint64_t features;
54
55 spinlock_t lock; /* protects the lists */
56 struct bio_list reads;
57 struct bio_list writes;
58 struct bio_list failures;
59 struct bio_list holds; /* bios are waiting until suspend */
60
61 struct dm_region_hash *rh;
62 struct dm_kcopyd_client *kcopyd_client;
63 struct dm_io_client *io_client;
64
65 /* recovery */
66 region_t nr_regions;
67 int in_sync;
68 int log_failure;
69 int leg_failure;
70 atomic_t suspend;
71
72 atomic_t default_mirror; /* Default mirror */
73
74 struct workqueue_struct *kmirrord_wq;
75 struct work_struct kmirrord_work;
76 struct timer_list timer;
77 unsigned long timer_pending;
78
79 struct work_struct trigger_event;
80
81 unsigned nr_mirrors;
82 struct mirror mirror[0];
83 };
84
85 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle,
86 "A percentage of time allocated for raid resynchronization");
87
wakeup_mirrord(void * context)88 static void wakeup_mirrord(void *context)
89 {
90 struct mirror_set *ms = context;
91
92 queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
93 }
94
delayed_wake_fn(unsigned long data)95 static void delayed_wake_fn(unsigned long data)
96 {
97 struct mirror_set *ms = (struct mirror_set *) data;
98
99 clear_bit(0, &ms->timer_pending);
100 wakeup_mirrord(ms);
101 }
102
delayed_wake(struct mirror_set * ms)103 static void delayed_wake(struct mirror_set *ms)
104 {
105 if (test_and_set_bit(0, &ms->timer_pending))
106 return;
107
108 ms->timer.expires = jiffies + HZ / 5;
109 ms->timer.data = (unsigned long) ms;
110 ms->timer.function = delayed_wake_fn;
111 add_timer(&ms->timer);
112 }
113
wakeup_all_recovery_waiters(void * context)114 static void wakeup_all_recovery_waiters(void *context)
115 {
116 wake_up_all(&_kmirrord_recovery_stopped);
117 }
118
queue_bio(struct mirror_set * ms,struct bio * bio,int rw)119 static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
120 {
121 unsigned long flags;
122 int should_wake = 0;
123 struct bio_list *bl;
124
125 bl = (rw == WRITE) ? &ms->writes : &ms->reads;
126 spin_lock_irqsave(&ms->lock, flags);
127 should_wake = !(bl->head);
128 bio_list_add(bl, bio);
129 spin_unlock_irqrestore(&ms->lock, flags);
130
131 if (should_wake)
132 wakeup_mirrord(ms);
133 }
134
dispatch_bios(void * context,struct bio_list * bio_list)135 static void dispatch_bios(void *context, struct bio_list *bio_list)
136 {
137 struct mirror_set *ms = context;
138 struct bio *bio;
139
140 while ((bio = bio_list_pop(bio_list)))
141 queue_bio(ms, bio, WRITE);
142 }
143
144 struct dm_raid1_bio_record {
145 struct mirror *m;
146 /* if details->bi_bdev == NULL, details were not saved */
147 struct dm_bio_details details;
148 region_t write_region;
149 };
150
151 /*
152 * Every mirror should look like this one.
153 */
154 #define DEFAULT_MIRROR 0
155
156 /*
157 * This is yucky. We squirrel the mirror struct away inside
158 * bi_next for read/write buffers. This is safe since the bh
159 * doesn't get submitted to the lower levels of block layer.
160 */
bio_get_m(struct bio * bio)161 static struct mirror *bio_get_m(struct bio *bio)
162 {
163 return (struct mirror *) bio->bi_next;
164 }
165
bio_set_m(struct bio * bio,struct mirror * m)166 static void bio_set_m(struct bio *bio, struct mirror *m)
167 {
168 bio->bi_next = (struct bio *) m;
169 }
170
get_default_mirror(struct mirror_set * ms)171 static struct mirror *get_default_mirror(struct mirror_set *ms)
172 {
173 return &ms->mirror[atomic_read(&ms->default_mirror)];
174 }
175
set_default_mirror(struct mirror * m)176 static void set_default_mirror(struct mirror *m)
177 {
178 struct mirror_set *ms = m->ms;
179 struct mirror *m0 = &(ms->mirror[0]);
180
181 atomic_set(&ms->default_mirror, m - m0);
182 }
183
get_valid_mirror(struct mirror_set * ms)184 static struct mirror *get_valid_mirror(struct mirror_set *ms)
185 {
186 struct mirror *m;
187
188 for (m = ms->mirror; m < ms->mirror + ms->nr_mirrors; m++)
189 if (!atomic_read(&m->error_count))
190 return m;
191
192 return NULL;
193 }
194
195 /* fail_mirror
196 * @m: mirror device to fail
197 * @error_type: one of the enum's, DM_RAID1_*_ERROR
198 *
199 * If errors are being handled, record the type of
200 * error encountered for this device. If this type
201 * of error has already been recorded, we can return;
202 * otherwise, we must signal userspace by triggering
203 * an event. Additionally, if the device is the
204 * primary device, we must choose a new primary, but
205 * only if the mirror is in-sync.
206 *
207 * This function must not block.
208 */
fail_mirror(struct mirror * m,enum dm_raid1_error error_type)209 static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
210 {
211 struct mirror_set *ms = m->ms;
212 struct mirror *new;
213
214 ms->leg_failure = 1;
215
216 /*
217 * error_count is used for nothing more than a
218 * simple way to tell if a device has encountered
219 * errors.
220 */
221 atomic_inc(&m->error_count);
222
223 if (test_and_set_bit(error_type, &m->error_type))
224 return;
225
226 if (!errors_handled(ms))
227 return;
228
229 if (m != get_default_mirror(ms))
230 goto out;
231
232 if (!ms->in_sync) {
233 /*
234 * Better to issue requests to same failing device
235 * than to risk returning corrupt data.
236 */
237 DMERR("Primary mirror (%s) failed while out-of-sync: "
238 "Reads may fail.", m->dev->name);
239 goto out;
240 }
241
242 new = get_valid_mirror(ms);
243 if (new)
244 set_default_mirror(new);
245 else
246 DMWARN("All sides of mirror have failed.");
247
248 out:
249 schedule_work(&ms->trigger_event);
250 }
251
mirror_flush(struct dm_target * ti)252 static int mirror_flush(struct dm_target *ti)
253 {
254 struct mirror_set *ms = ti->private;
255 unsigned long error_bits;
256
257 unsigned int i;
258 struct dm_io_region io[ms->nr_mirrors];
259 struct mirror *m;
260 struct dm_io_request io_req = {
261 .bi_rw = WRITE_FLUSH,
262 .mem.type = DM_IO_KMEM,
263 .mem.ptr.addr = NULL,
264 .client = ms->io_client,
265 };
266
267 for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
268 io[i].bdev = m->dev->bdev;
269 io[i].sector = 0;
270 io[i].count = 0;
271 }
272
273 error_bits = -1;
274 dm_io(&io_req, ms->nr_mirrors, io, &error_bits);
275 if (unlikely(error_bits != 0)) {
276 for (i = 0; i < ms->nr_mirrors; i++)
277 if (test_bit(i, &error_bits))
278 fail_mirror(ms->mirror + i,
279 DM_RAID1_FLUSH_ERROR);
280 return -EIO;
281 }
282
283 return 0;
284 }
285
286 /*-----------------------------------------------------------------
287 * Recovery.
288 *
289 * When a mirror is first activated we may find that some regions
290 * are in the no-sync state. We have to recover these by
291 * recopying from the default mirror to all the others.
292 *---------------------------------------------------------------*/
recovery_complete(int read_err,unsigned long write_err,void * context)293 static void recovery_complete(int read_err, unsigned long write_err,
294 void *context)
295 {
296 struct dm_region *reg = context;
297 struct mirror_set *ms = dm_rh_region_context(reg);
298 int m, bit = 0;
299
300 if (read_err) {
301 /* Read error means the failure of default mirror. */
302 DMERR_LIMIT("Unable to read primary mirror during recovery");
303 fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR);
304 }
305
306 if (write_err) {
307 DMERR_LIMIT("Write error during recovery (error = 0x%lx)",
308 write_err);
309 /*
310 * Bits correspond to devices (excluding default mirror).
311 * The default mirror cannot change during recovery.
312 */
313 for (m = 0; m < ms->nr_mirrors; m++) {
314 if (&ms->mirror[m] == get_default_mirror(ms))
315 continue;
316 if (test_bit(bit, &write_err))
317 fail_mirror(ms->mirror + m,
318 DM_RAID1_SYNC_ERROR);
319 bit++;
320 }
321 }
322
323 dm_rh_recovery_end(reg, !(read_err || write_err));
324 }
325
recover(struct mirror_set * ms,struct dm_region * reg)326 static int recover(struct mirror_set *ms, struct dm_region *reg)
327 {
328 int r;
329 unsigned i;
330 struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest;
331 struct mirror *m;
332 unsigned long flags = 0;
333 region_t key = dm_rh_get_region_key(reg);
334 sector_t region_size = dm_rh_get_region_size(ms->rh);
335
336 /* fill in the source */
337 m = get_default_mirror(ms);
338 from.bdev = m->dev->bdev;
339 from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
340 if (key == (ms->nr_regions - 1)) {
341 /*
342 * The final region may be smaller than
343 * region_size.
344 */
345 from.count = ms->ti->len & (region_size - 1);
346 if (!from.count)
347 from.count = region_size;
348 } else
349 from.count = region_size;
350
351 /* fill in the destinations */
352 for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
353 if (&ms->mirror[i] == get_default_mirror(ms))
354 continue;
355
356 m = ms->mirror + i;
357 dest->bdev = m->dev->bdev;
358 dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
359 dest->count = from.count;
360 dest++;
361 }
362
363 /* hand to kcopyd */
364 if (!errors_handled(ms))
365 set_bit(DM_KCOPYD_IGNORE_ERROR, &flags);
366
367 r = dm_kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to,
368 flags, recovery_complete, reg);
369
370 return r;
371 }
372
do_recovery(struct mirror_set * ms)373 static void do_recovery(struct mirror_set *ms)
374 {
375 struct dm_region *reg;
376 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
377 int r;
378
379 /*
380 * Start quiescing some regions.
381 */
382 dm_rh_recovery_prepare(ms->rh);
383
384 /*
385 * Copy any already quiesced regions.
386 */
387 while ((reg = dm_rh_recovery_start(ms->rh))) {
388 r = recover(ms, reg);
389 if (r)
390 dm_rh_recovery_end(reg, 0);
391 }
392
393 /*
394 * Update the in sync flag.
395 */
396 if (!ms->in_sync &&
397 (log->type->get_sync_count(log) == ms->nr_regions)) {
398 /* the sync is complete */
399 dm_table_event(ms->ti->table);
400 ms->in_sync = 1;
401 }
402 }
403
404 /*-----------------------------------------------------------------
405 * Reads
406 *---------------------------------------------------------------*/
choose_mirror(struct mirror_set * ms,sector_t sector)407 static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
408 {
409 struct mirror *m = get_default_mirror(ms);
410
411 do {
412 if (likely(!atomic_read(&m->error_count)))
413 return m;
414
415 if (m-- == ms->mirror)
416 m += ms->nr_mirrors;
417 } while (m != get_default_mirror(ms));
418
419 return NULL;
420 }
421
default_ok(struct mirror * m)422 static int default_ok(struct mirror *m)
423 {
424 struct mirror *default_mirror = get_default_mirror(m->ms);
425
426 return !atomic_read(&default_mirror->error_count);
427 }
428
mirror_available(struct mirror_set * ms,struct bio * bio)429 static int mirror_available(struct mirror_set *ms, struct bio *bio)
430 {
431 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
432 region_t region = dm_rh_bio_to_region(ms->rh, bio);
433
434 if (log->type->in_sync(log, region, 0))
435 return choose_mirror(ms, bio->bi_sector) ? 1 : 0;
436
437 return 0;
438 }
439
440 /*
441 * remap a buffer to a particular mirror.
442 */
map_sector(struct mirror * m,struct bio * bio)443 static sector_t map_sector(struct mirror *m, struct bio *bio)
444 {
445 if (unlikely(!bio->bi_size))
446 return 0;
447 return m->offset + dm_target_offset(m->ms->ti, bio->bi_sector);
448 }
449
map_bio(struct mirror * m,struct bio * bio)450 static void map_bio(struct mirror *m, struct bio *bio)
451 {
452 bio->bi_bdev = m->dev->bdev;
453 bio->bi_sector = map_sector(m, bio);
454 }
455
map_region(struct dm_io_region * io,struct mirror * m,struct bio * bio)456 static void map_region(struct dm_io_region *io, struct mirror *m,
457 struct bio *bio)
458 {
459 io->bdev = m->dev->bdev;
460 io->sector = map_sector(m, bio);
461 io->count = bio_sectors(bio);
462 }
463
hold_bio(struct mirror_set * ms,struct bio * bio)464 static void hold_bio(struct mirror_set *ms, struct bio *bio)
465 {
466 /*
467 * Lock is required to avoid race condition during suspend
468 * process.
469 */
470 spin_lock_irq(&ms->lock);
471
472 if (atomic_read(&ms->suspend)) {
473 spin_unlock_irq(&ms->lock);
474
475 /*
476 * If device is suspended, complete the bio.
477 */
478 if (dm_noflush_suspending(ms->ti))
479 bio_endio(bio, DM_ENDIO_REQUEUE);
480 else
481 bio_endio(bio, -EIO);
482 return;
483 }
484
485 /*
486 * Hold bio until the suspend is complete.
487 */
488 bio_list_add(&ms->holds, bio);
489 spin_unlock_irq(&ms->lock);
490 }
491
492 /*-----------------------------------------------------------------
493 * Reads
494 *---------------------------------------------------------------*/
read_callback(unsigned long error,void * context)495 static void read_callback(unsigned long error, void *context)
496 {
497 struct bio *bio = context;
498 struct mirror *m;
499
500 m = bio_get_m(bio);
501 bio_set_m(bio, NULL);
502
503 if (likely(!error)) {
504 bio_endio(bio, 0);
505 return;
506 }
507
508 fail_mirror(m, DM_RAID1_READ_ERROR);
509
510 if (likely(default_ok(m)) || mirror_available(m->ms, bio)) {
511 DMWARN_LIMIT("Read failure on mirror device %s. "
512 "Trying alternative device.",
513 m->dev->name);
514 queue_bio(m->ms, bio, bio_rw(bio));
515 return;
516 }
517
518 DMERR_LIMIT("Read failure on mirror device %s. Failing I/O.",
519 m->dev->name);
520 bio_endio(bio, -EIO);
521 }
522
523 /* Asynchronous read. */
read_async_bio(struct mirror * m,struct bio * bio)524 static void read_async_bio(struct mirror *m, struct bio *bio)
525 {
526 struct dm_io_region io;
527 struct dm_io_request io_req = {
528 .bi_rw = READ,
529 .mem.type = DM_IO_BVEC,
530 .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
531 .notify.fn = read_callback,
532 .notify.context = bio,
533 .client = m->ms->io_client,
534 };
535
536 map_region(&io, m, bio);
537 bio_set_m(bio, m);
538 BUG_ON(dm_io(&io_req, 1, &io, NULL));
539 }
540
region_in_sync(struct mirror_set * ms,region_t region,int may_block)541 static inline int region_in_sync(struct mirror_set *ms, region_t region,
542 int may_block)
543 {
544 int state = dm_rh_get_state(ms->rh, region, may_block);
545 return state == DM_RH_CLEAN || state == DM_RH_DIRTY;
546 }
547
do_reads(struct mirror_set * ms,struct bio_list * reads)548 static void do_reads(struct mirror_set *ms, struct bio_list *reads)
549 {
550 region_t region;
551 struct bio *bio;
552 struct mirror *m;
553
554 while ((bio = bio_list_pop(reads))) {
555 region = dm_rh_bio_to_region(ms->rh, bio);
556 m = get_default_mirror(ms);
557
558 /*
559 * We can only read balance if the region is in sync.
560 */
561 if (likely(region_in_sync(ms, region, 1)))
562 m = choose_mirror(ms, bio->bi_sector);
563 else if (m && atomic_read(&m->error_count))
564 m = NULL;
565
566 if (likely(m))
567 read_async_bio(m, bio);
568 else
569 bio_endio(bio, -EIO);
570 }
571 }
572
573 /*-----------------------------------------------------------------
574 * Writes.
575 *
576 * We do different things with the write io depending on the
577 * state of the region that it's in:
578 *
579 * SYNC: increment pending, use kcopyd to write to *all* mirrors
580 * RECOVERING: delay the io until recovery completes
581 * NOSYNC: increment pending, just write to the default mirror
582 *---------------------------------------------------------------*/
583
584
write_callback(unsigned long error,void * context)585 static void write_callback(unsigned long error, void *context)
586 {
587 unsigned i, ret = 0;
588 struct bio *bio = (struct bio *) context;
589 struct mirror_set *ms;
590 int should_wake = 0;
591 unsigned long flags;
592
593 ms = bio_get_m(bio)->ms;
594 bio_set_m(bio, NULL);
595
596 /*
597 * NOTE: We don't decrement the pending count here,
598 * instead it is done by the targets endio function.
599 * This way we handle both writes to SYNC and NOSYNC
600 * regions with the same code.
601 */
602 if (likely(!error)) {
603 bio_endio(bio, ret);
604 return;
605 }
606
607 for (i = 0; i < ms->nr_mirrors; i++)
608 if (test_bit(i, &error))
609 fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
610
611 /*
612 * Need to raise event. Since raising
613 * events can block, we need to do it in
614 * the main thread.
615 */
616 spin_lock_irqsave(&ms->lock, flags);
617 if (!ms->failures.head)
618 should_wake = 1;
619 bio_list_add(&ms->failures, bio);
620 spin_unlock_irqrestore(&ms->lock, flags);
621 if (should_wake)
622 wakeup_mirrord(ms);
623 }
624
do_write(struct mirror_set * ms,struct bio * bio)625 static void do_write(struct mirror_set *ms, struct bio *bio)
626 {
627 unsigned int i;
628 struct dm_io_region io[ms->nr_mirrors], *dest = io;
629 struct mirror *m;
630 struct dm_io_request io_req = {
631 .bi_rw = WRITE | (bio->bi_rw & WRITE_FLUSH_FUA),
632 .mem.type = DM_IO_BVEC,
633 .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
634 .notify.fn = write_callback,
635 .notify.context = bio,
636 .client = ms->io_client,
637 };
638
639 if (bio->bi_rw & REQ_DISCARD) {
640 io_req.bi_rw |= REQ_DISCARD;
641 io_req.mem.type = DM_IO_KMEM;
642 io_req.mem.ptr.addr = NULL;
643 }
644
645 for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
646 map_region(dest++, m, bio);
647
648 /*
649 * Use default mirror because we only need it to retrieve the reference
650 * to the mirror set in write_callback().
651 */
652 bio_set_m(bio, get_default_mirror(ms));
653
654 BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL));
655 }
656
do_writes(struct mirror_set * ms,struct bio_list * writes)657 static void do_writes(struct mirror_set *ms, struct bio_list *writes)
658 {
659 int state;
660 struct bio *bio;
661 struct bio_list sync, nosync, recover, *this_list = NULL;
662 struct bio_list requeue;
663 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
664 region_t region;
665
666 if (!writes->head)
667 return;
668
669 /*
670 * Classify each write.
671 */
672 bio_list_init(&sync);
673 bio_list_init(&nosync);
674 bio_list_init(&recover);
675 bio_list_init(&requeue);
676
677 while ((bio = bio_list_pop(writes))) {
678 if ((bio->bi_rw & REQ_FLUSH) ||
679 (bio->bi_rw & REQ_DISCARD)) {
680 bio_list_add(&sync, bio);
681 continue;
682 }
683
684 region = dm_rh_bio_to_region(ms->rh, bio);
685
686 if (log->type->is_remote_recovering &&
687 log->type->is_remote_recovering(log, region)) {
688 bio_list_add(&requeue, bio);
689 continue;
690 }
691
692 state = dm_rh_get_state(ms->rh, region, 1);
693 switch (state) {
694 case DM_RH_CLEAN:
695 case DM_RH_DIRTY:
696 this_list = &sync;
697 break;
698
699 case DM_RH_NOSYNC:
700 this_list = &nosync;
701 break;
702
703 case DM_RH_RECOVERING:
704 this_list = &recover;
705 break;
706 }
707
708 bio_list_add(this_list, bio);
709 }
710
711 /*
712 * Add bios that are delayed due to remote recovery
713 * back on to the write queue
714 */
715 if (unlikely(requeue.head)) {
716 spin_lock_irq(&ms->lock);
717 bio_list_merge(&ms->writes, &requeue);
718 spin_unlock_irq(&ms->lock);
719 delayed_wake(ms);
720 }
721
722 /*
723 * Increment the pending counts for any regions that will
724 * be written to (writes to recover regions are going to
725 * be delayed).
726 */
727 dm_rh_inc_pending(ms->rh, &sync);
728 dm_rh_inc_pending(ms->rh, &nosync);
729
730 /*
731 * If the flush fails on a previous call and succeeds here,
732 * we must not reset the log_failure variable. We need
733 * userspace interaction to do that.
734 */
735 ms->log_failure = dm_rh_flush(ms->rh) ? 1 : ms->log_failure;
736
737 /*
738 * Dispatch io.
739 */
740 if (unlikely(ms->log_failure) && errors_handled(ms)) {
741 spin_lock_irq(&ms->lock);
742 bio_list_merge(&ms->failures, &sync);
743 spin_unlock_irq(&ms->lock);
744 wakeup_mirrord(ms);
745 } else
746 while ((bio = bio_list_pop(&sync)))
747 do_write(ms, bio);
748
749 while ((bio = bio_list_pop(&recover)))
750 dm_rh_delay(ms->rh, bio);
751
752 while ((bio = bio_list_pop(&nosync))) {
753 if (unlikely(ms->leg_failure) && errors_handled(ms)) {
754 spin_lock_irq(&ms->lock);
755 bio_list_add(&ms->failures, bio);
756 spin_unlock_irq(&ms->lock);
757 wakeup_mirrord(ms);
758 } else {
759 map_bio(get_default_mirror(ms), bio);
760 generic_make_request(bio);
761 }
762 }
763 }
764
do_failures(struct mirror_set * ms,struct bio_list * failures)765 static void do_failures(struct mirror_set *ms, struct bio_list *failures)
766 {
767 struct bio *bio;
768
769 if (likely(!failures->head))
770 return;
771
772 /*
773 * If the log has failed, unattempted writes are being
774 * put on the holds list. We can't issue those writes
775 * until a log has been marked, so we must store them.
776 *
777 * If a 'noflush' suspend is in progress, we can requeue
778 * the I/O's to the core. This give userspace a chance
779 * to reconfigure the mirror, at which point the core
780 * will reissue the writes. If the 'noflush' flag is
781 * not set, we have no choice but to return errors.
782 *
783 * Some writes on the failures list may have been
784 * submitted before the log failure and represent a
785 * failure to write to one of the devices. It is ok
786 * for us to treat them the same and requeue them
787 * as well.
788 */
789 while ((bio = bio_list_pop(failures))) {
790 if (!ms->log_failure) {
791 ms->in_sync = 0;
792 dm_rh_mark_nosync(ms->rh, bio);
793 }
794
795 /*
796 * If all the legs are dead, fail the I/O.
797 * If we have been told to handle errors, hold the bio
798 * and wait for userspace to deal with the problem.
799 * Otherwise pretend that the I/O succeeded. (This would
800 * be wrong if the failed leg returned after reboot and
801 * got replicated back to the good legs.)
802 */
803 if (!get_valid_mirror(ms))
804 bio_endio(bio, -EIO);
805 else if (errors_handled(ms))
806 hold_bio(ms, bio);
807 else
808 bio_endio(bio, 0);
809 }
810 }
811
trigger_event(struct work_struct * work)812 static void trigger_event(struct work_struct *work)
813 {
814 struct mirror_set *ms =
815 container_of(work, struct mirror_set, trigger_event);
816
817 dm_table_event(ms->ti->table);
818 }
819
820 /*-----------------------------------------------------------------
821 * kmirrord
822 *---------------------------------------------------------------*/
do_mirror(struct work_struct * work)823 static void do_mirror(struct work_struct *work)
824 {
825 struct mirror_set *ms = container_of(work, struct mirror_set,
826 kmirrord_work);
827 struct bio_list reads, writes, failures;
828 unsigned long flags;
829
830 spin_lock_irqsave(&ms->lock, flags);
831 reads = ms->reads;
832 writes = ms->writes;
833 failures = ms->failures;
834 bio_list_init(&ms->reads);
835 bio_list_init(&ms->writes);
836 bio_list_init(&ms->failures);
837 spin_unlock_irqrestore(&ms->lock, flags);
838
839 dm_rh_update_states(ms->rh, errors_handled(ms));
840 do_recovery(ms);
841 do_reads(ms, &reads);
842 do_writes(ms, &writes);
843 do_failures(ms, &failures);
844 }
845
846 /*-----------------------------------------------------------------
847 * Target functions
848 *---------------------------------------------------------------*/
alloc_context(unsigned int nr_mirrors,uint32_t region_size,struct dm_target * ti,struct dm_dirty_log * dl)849 static struct mirror_set *alloc_context(unsigned int nr_mirrors,
850 uint32_t region_size,
851 struct dm_target *ti,
852 struct dm_dirty_log *dl)
853 {
854 size_t len;
855 struct mirror_set *ms = NULL;
856
857 len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
858
859 ms = kzalloc(len, GFP_KERNEL);
860 if (!ms) {
861 ti->error = "Cannot allocate mirror context";
862 return NULL;
863 }
864
865 spin_lock_init(&ms->lock);
866 bio_list_init(&ms->reads);
867 bio_list_init(&ms->writes);
868 bio_list_init(&ms->failures);
869 bio_list_init(&ms->holds);
870
871 ms->ti = ti;
872 ms->nr_mirrors = nr_mirrors;
873 ms->nr_regions = dm_sector_div_up(ti->len, region_size);
874 ms->in_sync = 0;
875 ms->log_failure = 0;
876 ms->leg_failure = 0;
877 atomic_set(&ms->suspend, 0);
878 atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
879
880 ms->io_client = dm_io_client_create();
881 if (IS_ERR(ms->io_client)) {
882 ti->error = "Error creating dm_io client";
883 kfree(ms);
884 return NULL;
885 }
886
887 ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord,
888 wakeup_all_recovery_waiters,
889 ms->ti->begin, MAX_RECOVERY,
890 dl, region_size, ms->nr_regions);
891 if (IS_ERR(ms->rh)) {
892 ti->error = "Error creating dirty region hash";
893 dm_io_client_destroy(ms->io_client);
894 kfree(ms);
895 return NULL;
896 }
897
898 return ms;
899 }
900
free_context(struct mirror_set * ms,struct dm_target * ti,unsigned int m)901 static void free_context(struct mirror_set *ms, struct dm_target *ti,
902 unsigned int m)
903 {
904 while (m--)
905 dm_put_device(ti, ms->mirror[m].dev);
906
907 dm_io_client_destroy(ms->io_client);
908 dm_region_hash_destroy(ms->rh);
909 kfree(ms);
910 }
911
get_mirror(struct mirror_set * ms,struct dm_target * ti,unsigned int mirror,char ** argv)912 static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
913 unsigned int mirror, char **argv)
914 {
915 unsigned long long offset;
916 char dummy;
917
918 if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1) {
919 ti->error = "Invalid offset";
920 return -EINVAL;
921 }
922
923 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
924 &ms->mirror[mirror].dev)) {
925 ti->error = "Device lookup failure";
926 return -ENXIO;
927 }
928
929 ms->mirror[mirror].ms = ms;
930 atomic_set(&(ms->mirror[mirror].error_count), 0);
931 ms->mirror[mirror].error_type = 0;
932 ms->mirror[mirror].offset = offset;
933
934 return 0;
935 }
936
937 /*
938 * Create dirty log: log_type #log_params <log_params>
939 */
create_dirty_log(struct dm_target * ti,unsigned argc,char ** argv,unsigned * args_used)940 static struct dm_dirty_log *create_dirty_log(struct dm_target *ti,
941 unsigned argc, char **argv,
942 unsigned *args_used)
943 {
944 unsigned param_count;
945 struct dm_dirty_log *dl;
946 char dummy;
947
948 if (argc < 2) {
949 ti->error = "Insufficient mirror log arguments";
950 return NULL;
951 }
952
953 if (sscanf(argv[1], "%u%c", ¶m_count, &dummy) != 1) {
954 ti->error = "Invalid mirror log argument count";
955 return NULL;
956 }
957
958 *args_used = 2 + param_count;
959
960 if (argc < *args_used) {
961 ti->error = "Insufficient mirror log arguments";
962 return NULL;
963 }
964
965 dl = dm_dirty_log_create(argv[0], ti, mirror_flush, param_count,
966 argv + 2);
967 if (!dl) {
968 ti->error = "Error creating mirror dirty log";
969 return NULL;
970 }
971
972 return dl;
973 }
974
parse_features(struct mirror_set * ms,unsigned argc,char ** argv,unsigned * args_used)975 static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
976 unsigned *args_used)
977 {
978 unsigned num_features;
979 struct dm_target *ti = ms->ti;
980 char dummy;
981
982 *args_used = 0;
983
984 if (!argc)
985 return 0;
986
987 if (sscanf(argv[0], "%u%c", &num_features, &dummy) != 1) {
988 ti->error = "Invalid number of features";
989 return -EINVAL;
990 }
991
992 argc--;
993 argv++;
994 (*args_used)++;
995
996 if (num_features > argc) {
997 ti->error = "Not enough arguments to support feature count";
998 return -EINVAL;
999 }
1000
1001 if (!strcmp("handle_errors", argv[0]))
1002 ms->features |= DM_RAID1_HANDLE_ERRORS;
1003 else {
1004 ti->error = "Unrecognised feature requested";
1005 return -EINVAL;
1006 }
1007
1008 (*args_used)++;
1009
1010 return 0;
1011 }
1012
1013 /*
1014 * Construct a mirror mapping:
1015 *
1016 * log_type #log_params <log_params>
1017 * #mirrors [mirror_path offset]{2,}
1018 * [#features <features>]
1019 *
1020 * log_type is "core" or "disk"
1021 * #log_params is between 1 and 3
1022 *
1023 * If present, features must be "handle_errors".
1024 */
mirror_ctr(struct dm_target * ti,unsigned int argc,char ** argv)1025 static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1026 {
1027 int r;
1028 unsigned int nr_mirrors, m, args_used;
1029 struct mirror_set *ms;
1030 struct dm_dirty_log *dl;
1031 char dummy;
1032
1033 dl = create_dirty_log(ti, argc, argv, &args_used);
1034 if (!dl)
1035 return -EINVAL;
1036
1037 argv += args_used;
1038 argc -= args_used;
1039
1040 if (!argc || sscanf(argv[0], "%u%c", &nr_mirrors, &dummy) != 1 ||
1041 nr_mirrors < 2 || nr_mirrors > DM_KCOPYD_MAX_REGIONS + 1) {
1042 ti->error = "Invalid number of mirrors";
1043 dm_dirty_log_destroy(dl);
1044 return -EINVAL;
1045 }
1046
1047 argv++, argc--;
1048
1049 if (argc < nr_mirrors * 2) {
1050 ti->error = "Too few mirror arguments";
1051 dm_dirty_log_destroy(dl);
1052 return -EINVAL;
1053 }
1054
1055 ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
1056 if (!ms) {
1057 dm_dirty_log_destroy(dl);
1058 return -ENOMEM;
1059 }
1060
1061 /* Get the mirror parameter sets */
1062 for (m = 0; m < nr_mirrors; m++) {
1063 r = get_mirror(ms, ti, m, argv);
1064 if (r) {
1065 free_context(ms, ti, m);
1066 return r;
1067 }
1068 argv += 2;
1069 argc -= 2;
1070 }
1071
1072 ti->private = ms;
1073
1074 r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
1075 if (r)
1076 goto err_free_context;
1077
1078 ti->num_flush_bios = 1;
1079 ti->num_discard_bios = 1;
1080 ti->per_bio_data_size = sizeof(struct dm_raid1_bio_record);
1081 ti->discard_zeroes_data_unsupported = true;
1082
1083 ms->kmirrord_wq = alloc_workqueue("kmirrord",
1084 WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
1085 if (!ms->kmirrord_wq) {
1086 DMERR("couldn't start kmirrord");
1087 r = -ENOMEM;
1088 goto err_free_context;
1089 }
1090 INIT_WORK(&ms->kmirrord_work, do_mirror);
1091 init_timer(&ms->timer);
1092 ms->timer_pending = 0;
1093 INIT_WORK(&ms->trigger_event, trigger_event);
1094
1095 r = parse_features(ms, argc, argv, &args_used);
1096 if (r)
1097 goto err_destroy_wq;
1098
1099 argv += args_used;
1100 argc -= args_used;
1101
1102 /*
1103 * Any read-balancing addition depends on the
1104 * DM_RAID1_HANDLE_ERRORS flag being present.
1105 * This is because the decision to balance depends
1106 * on the sync state of a region. If the above
1107 * flag is not present, we ignore errors; and
1108 * the sync state may be inaccurate.
1109 */
1110
1111 if (argc) {
1112 ti->error = "Too many mirror arguments";
1113 r = -EINVAL;
1114 goto err_destroy_wq;
1115 }
1116
1117 ms->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
1118 if (IS_ERR(ms->kcopyd_client)) {
1119 r = PTR_ERR(ms->kcopyd_client);
1120 goto err_destroy_wq;
1121 }
1122
1123 wakeup_mirrord(ms);
1124 return 0;
1125
1126 err_destroy_wq:
1127 destroy_workqueue(ms->kmirrord_wq);
1128 err_free_context:
1129 free_context(ms, ti, ms->nr_mirrors);
1130 return r;
1131 }
1132
mirror_dtr(struct dm_target * ti)1133 static void mirror_dtr(struct dm_target *ti)
1134 {
1135 struct mirror_set *ms = (struct mirror_set *) ti->private;
1136
1137 del_timer_sync(&ms->timer);
1138 flush_workqueue(ms->kmirrord_wq);
1139 flush_work(&ms->trigger_event);
1140 dm_kcopyd_client_destroy(ms->kcopyd_client);
1141 destroy_workqueue(ms->kmirrord_wq);
1142 free_context(ms, ti, ms->nr_mirrors);
1143 }
1144
1145 /*
1146 * Mirror mapping function
1147 */
mirror_map(struct dm_target * ti,struct bio * bio)1148 static int mirror_map(struct dm_target *ti, struct bio *bio)
1149 {
1150 int r, rw = bio_rw(bio);
1151 struct mirror *m;
1152 struct mirror_set *ms = ti->private;
1153 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1154 struct dm_raid1_bio_record *bio_record =
1155 dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
1156
1157 bio_record->details.bi_bdev = NULL;
1158
1159 if (rw == WRITE) {
1160 /* Save region for mirror_end_io() handler */
1161 bio_record->write_region = dm_rh_bio_to_region(ms->rh, bio);
1162 queue_bio(ms, bio, rw);
1163 return DM_MAPIO_SUBMITTED;
1164 }
1165
1166 r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
1167 if (r < 0 && r != -EWOULDBLOCK)
1168 return r;
1169
1170 /*
1171 * If region is not in-sync queue the bio.
1172 */
1173 if (!r || (r == -EWOULDBLOCK)) {
1174 if (rw == READA)
1175 return -EWOULDBLOCK;
1176
1177 queue_bio(ms, bio, rw);
1178 return DM_MAPIO_SUBMITTED;
1179 }
1180
1181 /*
1182 * The region is in-sync and we can perform reads directly.
1183 * Store enough information so we can retry if it fails.
1184 */
1185 m = choose_mirror(ms, bio->bi_sector);
1186 if (unlikely(!m))
1187 return -EIO;
1188
1189 dm_bio_record(&bio_record->details, bio);
1190 bio_record->m = m;
1191
1192 map_bio(m, bio);
1193
1194 return DM_MAPIO_REMAPPED;
1195 }
1196
mirror_end_io(struct dm_target * ti,struct bio * bio,int error)1197 static int mirror_end_io(struct dm_target *ti, struct bio *bio, int error)
1198 {
1199 int rw = bio_rw(bio);
1200 struct mirror_set *ms = (struct mirror_set *) ti->private;
1201 struct mirror *m = NULL;
1202 struct dm_bio_details *bd = NULL;
1203 struct dm_raid1_bio_record *bio_record =
1204 dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
1205
1206 /*
1207 * We need to dec pending if this was a write.
1208 */
1209 if (rw == WRITE) {
1210 if (!(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD)))
1211 dm_rh_dec(ms->rh, bio_record->write_region);
1212 return error;
1213 }
1214
1215 if (error == -EOPNOTSUPP)
1216 goto out;
1217
1218 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
1219 goto out;
1220
1221 if (unlikely(error)) {
1222 if (!bio_record->details.bi_bdev) {
1223 /*
1224 * There wasn't enough memory to record necessary
1225 * information for a retry or there was no other
1226 * mirror in-sync.
1227 */
1228 DMERR_LIMIT("Mirror read failed.");
1229 return -EIO;
1230 }
1231
1232 m = bio_record->m;
1233
1234 DMERR("Mirror read failed from %s. Trying alternative device.",
1235 m->dev->name);
1236
1237 fail_mirror(m, DM_RAID1_READ_ERROR);
1238
1239 /*
1240 * A failed read is requeued for another attempt using an intact
1241 * mirror.
1242 */
1243 if (default_ok(m) || mirror_available(ms, bio)) {
1244 bd = &bio_record->details;
1245
1246 dm_bio_restore(bd, bio);
1247 bio_record->details.bi_bdev = NULL;
1248 queue_bio(ms, bio, rw);
1249 return DM_ENDIO_INCOMPLETE;
1250 }
1251 DMERR("All replicated volumes dead, failing I/O");
1252 }
1253
1254 out:
1255 bio_record->details.bi_bdev = NULL;
1256
1257 return error;
1258 }
1259
mirror_presuspend(struct dm_target * ti)1260 static void mirror_presuspend(struct dm_target *ti)
1261 {
1262 struct mirror_set *ms = (struct mirror_set *) ti->private;
1263 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1264
1265 struct bio_list holds;
1266 struct bio *bio;
1267
1268 atomic_set(&ms->suspend, 1);
1269
1270 /*
1271 * Process bios in the hold list to start recovery waiting
1272 * for bios in the hold list. After the process, no bio has
1273 * a chance to be added in the hold list because ms->suspend
1274 * is set.
1275 */
1276 spin_lock_irq(&ms->lock);
1277 holds = ms->holds;
1278 bio_list_init(&ms->holds);
1279 spin_unlock_irq(&ms->lock);
1280
1281 while ((bio = bio_list_pop(&holds)))
1282 hold_bio(ms, bio);
1283
1284 /*
1285 * We must finish up all the work that we've
1286 * generated (i.e. recovery work).
1287 */
1288 dm_rh_stop_recovery(ms->rh);
1289
1290 wait_event(_kmirrord_recovery_stopped,
1291 !dm_rh_recovery_in_flight(ms->rh));
1292
1293 if (log->type->presuspend && log->type->presuspend(log))
1294 /* FIXME: need better error handling */
1295 DMWARN("log presuspend failed");
1296
1297 /*
1298 * Now that recovery is complete/stopped and the
1299 * delayed bios are queued, we need to wait for
1300 * the worker thread to complete. This way,
1301 * we know that all of our I/O has been pushed.
1302 */
1303 flush_workqueue(ms->kmirrord_wq);
1304 }
1305
mirror_postsuspend(struct dm_target * ti)1306 static void mirror_postsuspend(struct dm_target *ti)
1307 {
1308 struct mirror_set *ms = ti->private;
1309 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1310
1311 if (log->type->postsuspend && log->type->postsuspend(log))
1312 /* FIXME: need better error handling */
1313 DMWARN("log postsuspend failed");
1314 }
1315
mirror_resume(struct dm_target * ti)1316 static void mirror_resume(struct dm_target *ti)
1317 {
1318 struct mirror_set *ms = ti->private;
1319 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1320
1321 atomic_set(&ms->suspend, 0);
1322 if (log->type->resume && log->type->resume(log))
1323 /* FIXME: need better error handling */
1324 DMWARN("log resume failed");
1325 dm_rh_start_recovery(ms->rh);
1326 }
1327
1328 /*
1329 * device_status_char
1330 * @m: mirror device/leg we want the status of
1331 *
1332 * We return one character representing the most severe error
1333 * we have encountered.
1334 * A => Alive - No failures
1335 * D => Dead - A write failure occurred leaving mirror out-of-sync
1336 * S => Sync - A sychronization failure occurred, mirror out-of-sync
1337 * R => Read - A read failure occurred, mirror data unaffected
1338 *
1339 * Returns: <char>
1340 */
device_status_char(struct mirror * m)1341 static char device_status_char(struct mirror *m)
1342 {
1343 if (!atomic_read(&(m->error_count)))
1344 return 'A';
1345
1346 return (test_bit(DM_RAID1_FLUSH_ERROR, &(m->error_type))) ? 'F' :
1347 (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' :
1348 (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' :
1349 (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
1350 }
1351
1352
mirror_status(struct dm_target * ti,status_type_t type,unsigned status_flags,char * result,unsigned maxlen)1353 static void mirror_status(struct dm_target *ti, status_type_t type,
1354 unsigned status_flags, char *result, unsigned maxlen)
1355 {
1356 unsigned int m, sz = 0;
1357 struct mirror_set *ms = (struct mirror_set *) ti->private;
1358 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1359 char buffer[ms->nr_mirrors + 1];
1360
1361 switch (type) {
1362 case STATUSTYPE_INFO:
1363 DMEMIT("%d ", ms->nr_mirrors);
1364 for (m = 0; m < ms->nr_mirrors; m++) {
1365 DMEMIT("%s ", ms->mirror[m].dev->name);
1366 buffer[m] = device_status_char(&(ms->mirror[m]));
1367 }
1368 buffer[m] = '\0';
1369
1370 DMEMIT("%llu/%llu 1 %s ",
1371 (unsigned long long)log->type->get_sync_count(log),
1372 (unsigned long long)ms->nr_regions, buffer);
1373
1374 sz += log->type->status(log, type, result+sz, maxlen-sz);
1375
1376 break;
1377
1378 case STATUSTYPE_TABLE:
1379 sz = log->type->status(log, type, result, maxlen);
1380
1381 DMEMIT("%d", ms->nr_mirrors);
1382 for (m = 0; m < ms->nr_mirrors; m++)
1383 DMEMIT(" %s %llu", ms->mirror[m].dev->name,
1384 (unsigned long long)ms->mirror[m].offset);
1385
1386 if (ms->features & DM_RAID1_HANDLE_ERRORS)
1387 DMEMIT(" 1 handle_errors");
1388 }
1389 }
1390
mirror_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)1391 static int mirror_iterate_devices(struct dm_target *ti,
1392 iterate_devices_callout_fn fn, void *data)
1393 {
1394 struct mirror_set *ms = ti->private;
1395 int ret = 0;
1396 unsigned i;
1397
1398 for (i = 0; !ret && i < ms->nr_mirrors; i++)
1399 ret = fn(ti, ms->mirror[i].dev,
1400 ms->mirror[i].offset, ti->len, data);
1401
1402 return ret;
1403 }
1404
1405 static struct target_type mirror_target = {
1406 .name = "mirror",
1407 .version = {1, 13, 2},
1408 .module = THIS_MODULE,
1409 .ctr = mirror_ctr,
1410 .dtr = mirror_dtr,
1411 .map = mirror_map,
1412 .end_io = mirror_end_io,
1413 .presuspend = mirror_presuspend,
1414 .postsuspend = mirror_postsuspend,
1415 .resume = mirror_resume,
1416 .status = mirror_status,
1417 .iterate_devices = mirror_iterate_devices,
1418 };
1419
dm_mirror_init(void)1420 static int __init dm_mirror_init(void)
1421 {
1422 int r;
1423
1424 r = dm_register_target(&mirror_target);
1425 if (r < 0) {
1426 DMERR("Failed to register mirror target");
1427 goto bad_target;
1428 }
1429
1430 return 0;
1431
1432 bad_target:
1433 return r;
1434 }
1435
dm_mirror_exit(void)1436 static void __exit dm_mirror_exit(void)
1437 {
1438 dm_unregister_target(&mirror_target);
1439 }
1440
1441 /* Module hooks */
1442 module_init(dm_mirror_init);
1443 module_exit(dm_mirror_exit);
1444
1445 MODULE_DESCRIPTION(DM_NAME " mirror target");
1446 MODULE_AUTHOR("Joe Thornber");
1447 MODULE_LICENSE("GPL");
1448