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[PATCH] W1: w1_netlink: New init/fini netlink callbacks.
[linux-2.6/verdex.git] / drivers / md / dm-raid1.c
blobb08df8b9b2cad8994a8d5c739c3943f1548cc17d
1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 *
4 * This file is released under the GPL.
5 */
6
7 #include "dm.h"
8 #include "dm-bio-list.h"
9 #include "dm-io.h"
10 #include "dm-log.h"
11 #include "kcopyd.h"
12
13 #include <linux/ctype.h>
14 #include <linux/init.h>
15 #include <linux/mempool.h>
16 #include <linux/module.h>
17 #include <linux/pagemap.h>
18 #include <linux/slab.h>
19 #include <linux/time.h>
20 #include <linux/vmalloc.h>
21 #include <linux/workqueue.h>
22
23 static struct workqueue_struct *_kmirrord_wq;
24 static struct work_struct _kmirrord_work;
25
26 static inline void wake(void)
27 {
28 queue_work(_kmirrord_wq, &_kmirrord_work);
29 }
30
31 /*-----------------------------------------------------------------
32 * Region hash
33 *
34 * The mirror splits itself up into discrete regions. Each
35 * region can be in one of three states: clean, dirty,
36 * nosync. There is no need to put clean regions in the hash.
37 *
38 * In addition to being present in the hash table a region _may_
39 * be present on one of three lists.
40 *
41 * clean_regions: Regions on this list have no io pending to
42 * them, they are in sync, we are no longer interested in them,
43 * they are dull. rh_update_states() will remove them from the
44 * hash table.
45 *
46 * quiesced_regions: These regions have been spun down, ready
47 * for recovery. rh_recovery_start() will remove regions from
48 * this list and hand them to kmirrord, which will schedule the
49 * recovery io with kcopyd.
50 *
51 * recovered_regions: Regions that kcopyd has successfully
52 * recovered. rh_update_states() will now schedule any delayed
53 * io, up the recovery_count, and remove the region from the
54 * hash.
55 *
56 * There are 2 locks:
57 * A rw spin lock 'hash_lock' protects just the hash table,
58 * this is never held in write mode from interrupt context,
59 * which I believe means that we only have to disable irqs when
60 * doing a write lock.
61 *
62 * An ordinary spin lock 'region_lock' that protects the three
63 * lists in the region_hash, with the 'state', 'list' and
64 * 'bhs_delayed' fields of the regions. This is used from irq
65 * context, so all other uses will have to suspend local irqs.
66 *---------------------------------------------------------------*/
67 struct mirror_set;
68 struct region_hash {
69 struct mirror_set *ms;
70 uint32_t region_size;
71 unsigned region_shift;
72
73 /* holds persistent region state */
74 struct dirty_log *log;
75
76 /* hash table */
77 rwlock_t hash_lock;
78 mempool_t *region_pool;
79 unsigned int mask;
80 unsigned int nr_buckets;
81 struct list_head *buckets;
82
83 spinlock_t region_lock;
84 struct semaphore recovery_count;
85 struct list_head clean_regions;
86 struct list_head quiesced_regions;
87 struct list_head recovered_regions;
88 };
89
90 enum {
91 RH_CLEAN,
92 RH_DIRTY,
93 RH_NOSYNC,
94 RH_RECOVERING
95 };
96
97 struct region {
98 struct region_hash *rh; /* FIXME: can we get rid of this ? */
99 region_t key;
100 int state;
101
102 struct list_head hash_list;
103 struct list_head list;
104
105 atomic_t pending;
106 struct bio_list delayed_bios;
107 };
108
109 /*
110 * Conversion fns
111 */
112 static inline region_t bio_to_region(struct region_hash *rh, struct bio *bio)
113 {
114 return bio->bi_sector >> rh->region_shift;
115 }
116
117 static inline sector_t region_to_sector(struct region_hash *rh, region_t region)
118 {
119 return region << rh->region_shift;
120 }
121
122 /* FIXME move this */
123 static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw);
124
125 static void *region_alloc(unsigned int __nocast gfp_mask, void *pool_data)
126 {
127 return kmalloc(sizeof(struct region), gfp_mask);
128 }
129
130 static void region_free(void *element, void *pool_data)
131 {
132 kfree(element);
133 }
134
135 #define MIN_REGIONS 64
136 #define MAX_RECOVERY 1
137 static int rh_init(struct region_hash *rh, struct mirror_set *ms,
138 struct dirty_log *log, uint32_t region_size,
139 region_t nr_regions)
140 {
141 unsigned int nr_buckets, max_buckets;
142 size_t i;
143
144 /*
145 * Calculate a suitable number of buckets for our hash
146 * table.
147 */
148 max_buckets = nr_regions >> 6;
149 for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1)
150 ;
151 nr_buckets >>= 1;
152
153 rh->ms = ms;
154 rh->log = log;
155 rh->region_size = region_size;
156 rh->region_shift = ffs(region_size) - 1;
157 rwlock_init(&rh->hash_lock);
158 rh->mask = nr_buckets - 1;
159 rh->nr_buckets = nr_buckets;
160
161 rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
162 if (!rh->buckets) {
163 DMERR("unable to allocate region hash memory");
164 return -ENOMEM;
165 }
166
167 for (i = 0; i < nr_buckets; i++)
168 INIT_LIST_HEAD(rh->buckets + i);
169
170 spin_lock_init(&rh->region_lock);
171 sema_init(&rh->recovery_count, 0);
172 INIT_LIST_HEAD(&rh->clean_regions);
173 INIT_LIST_HEAD(&rh->quiesced_regions);
174 INIT_LIST_HEAD(&rh->recovered_regions);
175
176 rh->region_pool = mempool_create(MIN_REGIONS, region_alloc,
177 region_free, NULL);
178 if (!rh->region_pool) {
179 vfree(rh->buckets);
180 rh->buckets = NULL;
181 return -ENOMEM;
182 }
183
184 return 0;
185 }
186
187 static void rh_exit(struct region_hash *rh)
188 {
189 unsigned int h;
190 struct region *reg, *nreg;
191
192 BUG_ON(!list_empty(&rh->quiesced_regions));
193 for (h = 0; h < rh->nr_buckets; h++) {
194 list_for_each_entry_safe(reg, nreg, rh->buckets + h, hash_list) {
195 BUG_ON(atomic_read(&reg->pending));
196 mempool_free(reg, rh->region_pool);
197 }
198 }
199
200 if (rh->log)
201 dm_destroy_dirty_log(rh->log);
202 if (rh->region_pool)
203 mempool_destroy(rh->region_pool);
204 vfree(rh->buckets);
205 }
206
207 #define RH_HASH_MULT 2654435387U
208
209 static inline unsigned int rh_hash(struct region_hash *rh, region_t region)
210 {
211 return (unsigned int) ((region * RH_HASH_MULT) >> 12) & rh->mask;
212 }
213
214 static struct region *__rh_lookup(struct region_hash *rh, region_t region)
215 {
216 struct region *reg;
217
218 list_for_each_entry (reg, rh->buckets + rh_hash(rh, region), hash_list)
219 if (reg->key == region)
220 return reg;
221
222 return NULL;
223 }
224
225 static void __rh_insert(struct region_hash *rh, struct region *reg)
226 {
227 unsigned int h = rh_hash(rh, reg->key);
228 list_add(&reg->hash_list, rh->buckets + h);
229 }
230
231 static struct region *__rh_alloc(struct region_hash *rh, region_t region)
232 {
233 struct region *reg, *nreg;
234
235 read_unlock(&rh->hash_lock);
236 nreg = mempool_alloc(rh->region_pool, GFP_NOIO);
237 nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
238 RH_CLEAN : RH_NOSYNC;
239 nreg->rh = rh;
240 nreg->key = region;
241
242 INIT_LIST_HEAD(&nreg->list);
243
244 atomic_set(&nreg->pending, 0);
245 bio_list_init(&nreg->delayed_bios);
246 write_lock_irq(&rh->hash_lock);
247
248 reg = __rh_lookup(rh, region);
249 if (reg)
250 /* we lost the race */
251 mempool_free(nreg, rh->region_pool);
252
253 else {
254 __rh_insert(rh, nreg);
255 if (nreg->state == RH_CLEAN) {
256 spin_lock(&rh->region_lock);
257 list_add(&nreg->list, &rh->clean_regions);
258 spin_unlock(&rh->region_lock);
259 }
260 reg = nreg;
261 }
262 write_unlock_irq(&rh->hash_lock);
263 read_lock(&rh->hash_lock);
264
265 return reg;
266 }
267
268 static inline struct region *__rh_find(struct region_hash *rh, region_t region)
269 {
270 struct region *reg;
271
272 reg = __rh_lookup(rh, region);
273 if (!reg)
274 reg = __rh_alloc(rh, region);
275
276 return reg;
277 }
278
279 static int rh_state(struct region_hash *rh, region_t region, int may_block)
280 {
281 int r;
282 struct region *reg;
283
284 read_lock(&rh->hash_lock);
285 reg = __rh_lookup(rh, region);
286 read_unlock(&rh->hash_lock);
287
288 if (reg)
289 return reg->state;
290
291 /*
292 * The region wasn't in the hash, so we fall back to the
293 * dirty log.
294 */
295 r = rh->log->type->in_sync(rh->log, region, may_block);
296
297 /*
298 * Any error from the dirty log (eg. -EWOULDBLOCK) gets
299 * taken as a RH_NOSYNC
300 */
301 return r == 1 ? RH_CLEAN : RH_NOSYNC;
302 }
303
304 static inline int rh_in_sync(struct region_hash *rh,
305 region_t region, int may_block)
306 {
307 int state = rh_state(rh, region, may_block);
308 return state == RH_CLEAN || state == RH_DIRTY;
309 }
310
311 static void dispatch_bios(struct mirror_set *ms, struct bio_list *bio_list)
312 {
313 struct bio *bio;
314
315 while ((bio = bio_list_pop(bio_list))) {
316 queue_bio(ms, bio, WRITE);
317 }
318 }
319
320 static void rh_update_states(struct region_hash *rh)
321 {
322 struct region *reg, *next;
323
324 LIST_HEAD(clean);
325 LIST_HEAD(recovered);
326
327 /*
328 * Quickly grab the lists.
329 */
330 write_lock_irq(&rh->hash_lock);
331 spin_lock(&rh->region_lock);
332 if (!list_empty(&rh->clean_regions)) {
333 list_splice(&rh->clean_regions, &clean);
334 INIT_LIST_HEAD(&rh->clean_regions);
335
336 list_for_each_entry (reg, &clean, list) {
337 rh->log->type->clear_region(rh->log, reg->key);
338 list_del(&reg->hash_list);
339 }
340 }
341
342 if (!list_empty(&rh->recovered_regions)) {
343 list_splice(&rh->recovered_regions, &recovered);
344 INIT_LIST_HEAD(&rh->recovered_regions);
345
346 list_for_each_entry (reg, &recovered, list)
347 list_del(&reg->hash_list);
348 }
349 spin_unlock(&rh->region_lock);
350 write_unlock_irq(&rh->hash_lock);
351
352 /*
353 * All the regions on the recovered and clean lists have
354 * now been pulled out of the system, so no need to do
355 * any more locking.
356 */
357 list_for_each_entry_safe (reg, next, &recovered, list) {
358 rh->log->type->clear_region(rh->log, reg->key);
359 rh->log->type->complete_resync_work(rh->log, reg->key, 1);
360 dispatch_bios(rh->ms, &reg->delayed_bios);
361 up(&rh->recovery_count);
362 mempool_free(reg, rh->region_pool);
363 }
364
365 if (!list_empty(&recovered))
366 rh->log->type->flush(rh->log);
367
368 list_for_each_entry_safe (reg, next, &clean, list)
369 mempool_free(reg, rh->region_pool);
370 }
371
372 static void rh_inc(struct region_hash *rh, region_t region)
373 {
374 struct region *reg;
375
376 read_lock(&rh->hash_lock);
377 reg = __rh_find(rh, region);
378 if (reg->state == RH_CLEAN) {
379 rh->log->type->mark_region(rh->log, reg->key);
380
381 spin_lock_irq(&rh->region_lock);
382 reg->state = RH_DIRTY;
383 list_del_init(&reg->list); /* take off the clean list */
384 spin_unlock_irq(&rh->region_lock);
385 }
386
387 atomic_inc(&reg->pending);
388 read_unlock(&rh->hash_lock);
389 }
390
391 static void rh_inc_pending(struct region_hash *rh, struct bio_list *bios)
392 {
393 struct bio *bio;
394
395 for (bio = bios->head; bio; bio = bio->bi_next)
396 rh_inc(rh, bio_to_region(rh, bio));
397 }
398
399 static void rh_dec(struct region_hash *rh, region_t region)
400 {
401 unsigned long flags;
402 struct region *reg;
403 int should_wake = 0;
404
405 read_lock(&rh->hash_lock);
406 reg = __rh_lookup(rh, region);
407 read_unlock(&rh->hash_lock);
408
409 if (atomic_dec_and_test(&reg->pending)) {
410 spin_lock_irqsave(&rh->region_lock, flags);
411 if (reg->state == RH_RECOVERING) {
412 list_add_tail(&reg->list, &rh->quiesced_regions);
413 } else {
414 reg->state = RH_CLEAN;
415 list_add(&reg->list, &rh->clean_regions);
416 }
417 spin_unlock_irqrestore(&rh->region_lock, flags);
418 should_wake = 1;
419 }
420
421 if (should_wake)
422 wake();
423 }
424
425 /*
426 * Starts quiescing a region in preparation for recovery.
427 */
428 static int __rh_recovery_prepare(struct region_hash *rh)
429 {
430 int r;
431 struct region *reg;
432 region_t region;
433
434 /*
435 * Ask the dirty log what's next.
436 */
437 r = rh->log->type->get_resync_work(rh->log, &region);
438 if (r <= 0)
439 return r;
440
441 /*
442 * Get this region, and start it quiescing by setting the
443 * recovering flag.
444 */
445 read_lock(&rh->hash_lock);
446 reg = __rh_find(rh, region);
447 read_unlock(&rh->hash_lock);
448
449 spin_lock_irq(&rh->region_lock);
450 reg->state = RH_RECOVERING;
451
452 /* Already quiesced ? */
453 if (atomic_read(&reg->pending))
454 list_del_init(&reg->list);
455
456 else {
457 list_del_init(&reg->list);
458 list_add(&reg->list, &rh->quiesced_regions);
459 }
460 spin_unlock_irq(&rh->region_lock);
461
462 return 1;
463 }
464
465 static void rh_recovery_prepare(struct region_hash *rh)
466 {
467 while (!down_trylock(&rh->recovery_count))
468 if (__rh_recovery_prepare(rh) <= 0) {
469 up(&rh->recovery_count);
470 break;
471 }
472 }
473
474 /*
475 * Returns any quiesced regions.
476 */
477 static struct region *rh_recovery_start(struct region_hash *rh)
478 {
479 struct region *reg = NULL;
480
481 spin_lock_irq(&rh->region_lock);
482 if (!list_empty(&rh->quiesced_regions)) {
483 reg = list_entry(rh->quiesced_regions.next,
484 struct region, list);
485 list_del_init(&reg->list); /* remove from the quiesced list */
486 }
487 spin_unlock_irq(&rh->region_lock);
488
489 return reg;
490 }
491
492 /* FIXME: success ignored for now */
493 static void rh_recovery_end(struct region *reg, int success)
494 {
495 struct region_hash *rh = reg->rh;
496
497 spin_lock_irq(&rh->region_lock);
498 list_add(&reg->list, &reg->rh->recovered_regions);
499 spin_unlock_irq(&rh->region_lock);
500
501 wake();
502 }
503
504 static void rh_flush(struct region_hash *rh)
505 {
506 rh->log->type->flush(rh->log);
507 }
508
509 static void rh_delay(struct region_hash *rh, struct bio *bio)
510 {
511 struct region *reg;
512
513 read_lock(&rh->hash_lock);
514 reg = __rh_find(rh, bio_to_region(rh, bio));
515 bio_list_add(&reg->delayed_bios, bio);
516 read_unlock(&rh->hash_lock);
517 }
518
519 static void rh_stop_recovery(struct region_hash *rh)
520 {
521 int i;
522
523 /* wait for any recovering regions */
524 for (i = 0; i < MAX_RECOVERY; i++)
525 down(&rh->recovery_count);
526 }
527
528 static void rh_start_recovery(struct region_hash *rh)
529 {
530 int i;
531
532 for (i = 0; i < MAX_RECOVERY; i++)
533 up(&rh->recovery_count);
534
535 wake();
536 }
537
538 /*-----------------------------------------------------------------
539 * Mirror set structures.
540 *---------------------------------------------------------------*/
541 struct mirror {
542 atomic_t error_count;
543 struct dm_dev *dev;
544 sector_t offset;
545 };
546
547 struct mirror_set {
548 struct dm_target *ti;
549 struct list_head list;
550 struct region_hash rh;
551 struct kcopyd_client *kcopyd_client;
552
553 spinlock_t lock; /* protects the next two lists */
554 struct bio_list reads;
555 struct bio_list writes;
556
557 /* recovery */
558 region_t nr_regions;
559 int in_sync;
560
561 unsigned int nr_mirrors;
562 struct mirror mirror[0];
563 };
564
565 /*
566 * Every mirror should look like this one.
567 */
568 #define DEFAULT_MIRROR 0
569
570 /*
571 * This is yucky. We squirrel the mirror_set struct away inside
572 * bi_next for write buffers. This is safe since the bh
573 * doesn't get submitted to the lower levels of block layer.
574 */
575 static struct mirror_set *bio_get_ms(struct bio *bio)
576 {
577 return (struct mirror_set *) bio->bi_next;
578 }
579
580 static void bio_set_ms(struct bio *bio, struct mirror_set *ms)
581 {
582 bio->bi_next = (struct bio *) ms;
583 }
584
585 /*-----------------------------------------------------------------
586 * Recovery.
587 *
588 * When a mirror is first activated we may find that some regions
589 * are in the no-sync state. We have to recover these by
590 * recopying from the default mirror to all the others.
591 *---------------------------------------------------------------*/
592 static void recovery_complete(int read_err, unsigned int write_err,
593 void *context)
594 {
595 struct region *reg = (struct region *) context;
596
597 /* FIXME: better error handling */
598 rh_recovery_end(reg, read_err || write_err);
599 }
600
601 static int recover(struct mirror_set *ms, struct region *reg)
602 {
603 int r;
604 unsigned int i;
605 struct io_region from, to[KCOPYD_MAX_REGIONS], *dest;
606 struct mirror *m;
607 unsigned long flags = 0;
608
609 /* fill in the source */
610 m = ms->mirror + DEFAULT_MIRROR;
611 from.bdev = m->dev->bdev;
612 from.sector = m->offset + region_to_sector(reg->rh, reg->key);
613 if (reg->key == (ms->nr_regions - 1)) {
614 /*
615 * The final region may be smaller than
616 * region_size.
617 */
618 from.count = ms->ti->len & (reg->rh->region_size - 1);
619 if (!from.count)
620 from.count = reg->rh->region_size;
621 } else
622 from.count = reg->rh->region_size;
623
624 /* fill in the destinations */
625 for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
626 if (i == DEFAULT_MIRROR)
627 continue;
628
629 m = ms->mirror + i;
630 dest->bdev = m->dev->bdev;
631 dest->sector = m->offset + region_to_sector(reg->rh, reg->key);
632 dest->count = from.count;
633 dest++;
634 }
635
636 /* hand to kcopyd */
637 set_bit(KCOPYD_IGNORE_ERROR, &flags);
638 r = kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to, flags,
639 recovery_complete, reg);
640
641 return r;
642 }
643
644 static void do_recovery(struct mirror_set *ms)
645 {
646 int r;
647 struct region *reg;
648 struct dirty_log *log = ms->rh.log;
649
650 /*
651 * Start quiescing some regions.
652 */
653 rh_recovery_prepare(&ms->rh);
654
655 /*
656 * Copy any already quiesced regions.
657 */
658 while ((reg = rh_recovery_start(&ms->rh))) {
659 r = recover(ms, reg);
660 if (r)
661 rh_recovery_end(reg, 0);
662 }
663
664 /*
665 * Update the in sync flag.
666 */
667 if (!ms->in_sync &&
668 (log->type->get_sync_count(log) == ms->nr_regions)) {
669 /* the sync is complete */
670 dm_table_event(ms->ti->table);
671 ms->in_sync = 1;
672 }
673 }
674
675 /*-----------------------------------------------------------------
676 * Reads
677 *---------------------------------------------------------------*/
678 static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
679 {
680 /* FIXME: add read balancing */
681 return ms->mirror + DEFAULT_MIRROR;
682 }
683
684 /*
685 * remap a buffer to a particular mirror.
686 */
687 static void map_bio(struct mirror_set *ms, struct mirror *m, struct bio *bio)
688 {
689 bio->bi_bdev = m->dev->bdev;
690 bio->bi_sector = m->offset + (bio->bi_sector - ms->ti->begin);
691 }
692
693 static void do_reads(struct mirror_set *ms, struct bio_list *reads)
694 {
695 region_t region;
696 struct bio *bio;
697 struct mirror *m;
698
699 while ((bio = bio_list_pop(reads))) {
700 region = bio_to_region(&ms->rh, bio);
701
702 /*
703 * We can only read balance if the region is in sync.
704 */
705 if (rh_in_sync(&ms->rh, region, 0))
706 m = choose_mirror(ms, bio->bi_sector);
707 else
708 m = ms->mirror + DEFAULT_MIRROR;
709
710 map_bio(ms, m, bio);
711 generic_make_request(bio);
712 }
713 }
714
715 /*-----------------------------------------------------------------
716 * Writes.
717 *
718 * We do different things with the write io depending on the
719 * state of the region that it's in:
720 *
721 * SYNC: increment pending, use kcopyd to write to *all* mirrors
722 * RECOVERING: delay the io until recovery completes
723 * NOSYNC: increment pending, just write to the default mirror
724 *---------------------------------------------------------------*/
725 static void write_callback(unsigned long error, void *context)
726 {
727 unsigned int i;
728 int uptodate = 1;
729 struct bio *bio = (struct bio *) context;
730 struct mirror_set *ms;
731
732 ms = bio_get_ms(bio);
733 bio_set_ms(bio, NULL);
734
735 /*
736 * NOTE: We don't decrement the pending count here,
737 * instead it is done by the targets endio function.
738 * This way we handle both writes to SYNC and NOSYNC
739 * regions with the same code.
740 */
741
742 if (error) {
743 /*
744 * only error the io if all mirrors failed.
745 * FIXME: bogus
746 */
747 uptodate = 0;
748 for (i = 0; i < ms->nr_mirrors; i++)
749 if (!test_bit(i, &error)) {
750 uptodate = 1;
751 break;
752 }
753 }
754 bio_endio(bio, bio->bi_size, 0);
755 }
756
757 static void do_write(struct mirror_set *ms, struct bio *bio)
758 {
759 unsigned int i;
760 struct io_region io[KCOPYD_MAX_REGIONS+1];
761 struct mirror *m;
762
763 for (i = 0; i < ms->nr_mirrors; i++) {
764 m = ms->mirror + i;
765
766 io[i].bdev = m->dev->bdev;
767 io[i].sector = m->offset + (bio->bi_sector - ms->ti->begin);
768 io[i].count = bio->bi_size >> 9;
769 }
770
771 bio_set_ms(bio, ms);
772 dm_io_async_bvec(ms->nr_mirrors, io, WRITE,
773 bio->bi_io_vec + bio->bi_idx,
774 write_callback, bio);
775 }
776
777 static void do_writes(struct mirror_set *ms, struct bio_list *writes)
778 {
779 int state;
780 struct bio *bio;
781 struct bio_list sync, nosync, recover, *this_list = NULL;
782
783 if (!writes->head)
784 return;
785
786 /*
787 * Classify each write.
788 */
789 bio_list_init(&sync);
790 bio_list_init(&nosync);
791 bio_list_init(&recover);
792
793 while ((bio = bio_list_pop(writes))) {
794 state = rh_state(&ms->rh, bio_to_region(&ms->rh, bio), 1);
795 switch (state) {
796 case RH_CLEAN:
797 case RH_DIRTY:
798 this_list = &sync;
799 break;
800
801 case RH_NOSYNC:
802 this_list = &nosync;
803 break;
804
805 case RH_RECOVERING:
806 this_list = &recover;
807 break;
808 }
809
810 bio_list_add(this_list, bio);
811 }
812
813 /*
814 * Increment the pending counts for any regions that will
815 * be written to (writes to recover regions are going to
816 * be delayed).
817 */
818 rh_inc_pending(&ms->rh, &sync);
819 rh_inc_pending(&ms->rh, &nosync);
820 rh_flush(&ms->rh);
821
822 /*
823 * Dispatch io.
824 */
825 while ((bio = bio_list_pop(&sync)))
826 do_write(ms, bio);
827
828 while ((bio = bio_list_pop(&recover)))
829 rh_delay(&ms->rh, bio);
830
831 while ((bio = bio_list_pop(&nosync))) {
832 map_bio(ms, ms->mirror + DEFAULT_MIRROR, bio);
833 generic_make_request(bio);
834 }
835 }
836
837 /*-----------------------------------------------------------------
838 * kmirrord
839 *---------------------------------------------------------------*/
840 static LIST_HEAD(_mirror_sets);
841 static DECLARE_RWSEM(_mirror_sets_lock);
842
843 static void do_mirror(struct mirror_set *ms)
844 {
845 struct bio_list reads, writes;
846
847 spin_lock(&ms->lock);
848 reads = ms->reads;
849 writes = ms->writes;
850 bio_list_init(&ms->reads);
851 bio_list_init(&ms->writes);
852 spin_unlock(&ms->lock);
853
854 rh_update_states(&ms->rh);
855 do_recovery(ms);
856 do_reads(ms, &reads);
857 do_writes(ms, &writes);
858 }
859
860 static void do_work(void *ignored)
861 {
862 struct mirror_set *ms;
863
864 down_read(&_mirror_sets_lock);
865 list_for_each_entry (ms, &_mirror_sets, list)
866 do_mirror(ms);
867 up_read(&_mirror_sets_lock);
868 }
869
870 /*-----------------------------------------------------------------
871 * Target functions
872 *---------------------------------------------------------------*/
873 static struct mirror_set *alloc_context(unsigned int nr_mirrors,
874 uint32_t region_size,
875 struct dm_target *ti,
876 struct dirty_log *dl)
877 {
878 size_t len;
879 struct mirror_set *ms = NULL;
880
881 if (array_too_big(sizeof(*ms), sizeof(ms->mirror[0]), nr_mirrors))
882 return NULL;
883
884 len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
885
886 ms = kmalloc(len, GFP_KERNEL);
887 if (!ms) {
888 ti->error = "dm-mirror: Cannot allocate mirror context";
889 return NULL;
890 }
891
892 memset(ms, 0, len);
893 spin_lock_init(&ms->lock);
894
895 ms->ti = ti;
896 ms->nr_mirrors = nr_mirrors;
897 ms->nr_regions = dm_sector_div_up(ti->len, region_size);
898 ms->in_sync = 0;
899
900 if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
901 ti->error = "dm-mirror: Error creating dirty region hash";
902 kfree(ms);
903 return NULL;
904 }
905
906 return ms;
907 }
908
909 static void free_context(struct mirror_set *ms, struct dm_target *ti,
910 unsigned int m)
911 {
912 while (m--)
913 dm_put_device(ti, ms->mirror[m].dev);
914
915 rh_exit(&ms->rh);
916 kfree(ms);
917 }
918
919 static inline int _check_region_size(struct dm_target *ti, uint32_t size)
920 {
921 return !(size % (PAGE_SIZE >> 9) || (size & (size - 1)) ||
922 size > ti->len);
923 }
924
925 static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
926 unsigned int mirror, char **argv)
927 {
928 sector_t offset;
929
930 if (sscanf(argv[1], SECTOR_FORMAT, &offset) != 1) {
931 ti->error = "dm-mirror: Invalid offset";
932 return -EINVAL;
933 }
934
935 if (dm_get_device(ti, argv[0], offset, ti->len,
936 dm_table_get_mode(ti->table),
937 &ms->mirror[mirror].dev)) {
938 ti->error = "dm-mirror: Device lookup failure";
939 return -ENXIO;
940 }
941
942 ms->mirror[mirror].offset = offset;
943
944 return 0;
945 }
946
947 static int add_mirror_set(struct mirror_set *ms)
948 {
949 down_write(&_mirror_sets_lock);
950 list_add_tail(&ms->list, &_mirror_sets);
951 up_write(&_mirror_sets_lock);
952 wake();
953
954 return 0;
955 }
956
957 static void del_mirror_set(struct mirror_set *ms)
958 {
959 down_write(&_mirror_sets_lock);
960 list_del(&ms->list);
961 up_write(&_mirror_sets_lock);
962 }
963
964 /*
965 * Create dirty log: log_type #log_params <log_params>
966 */
967 static struct dirty_log *create_dirty_log(struct dm_target *ti,
968 unsigned int argc, char **argv,
969 unsigned int *args_used)
970 {
971 unsigned int param_count;
972 struct dirty_log *dl;
973
974 if (argc < 2) {
975 ti->error = "dm-mirror: Insufficient mirror log arguments";
976 return NULL;
977 }
978
979 if (sscanf(argv[1], "%u", &param_count) != 1) {
980 ti->error = "dm-mirror: Invalid mirror log argument count";
981 return NULL;
982 }
983
984 *args_used = 2 + param_count;
985
986 if (argc < *args_used) {
987 ti->error = "dm-mirror: Insufficient mirror log arguments";
988 return NULL;
989 }
990
991 dl = dm_create_dirty_log(argv[0], ti, param_count, argv + 2);
992 if (!dl) {
993 ti->error = "dm-mirror: Error creating mirror dirty log";
994 return NULL;
995 }
996
997 if (!_check_region_size(ti, dl->type->get_region_size(dl))) {
998 ti->error = "dm-mirror: Invalid region size";
999 dm_destroy_dirty_log(dl);
1000 return NULL;
1001 }
1002
1003 return dl;
1004 }
1005
1006 /*
1007 * Construct a mirror mapping:
1008 *
1009 * log_type #log_params <log_params>
1010 * #mirrors [mirror_path offset]{2,}
1011 *
1012 * log_type is "core" or "disk"
1013 * #log_params is between 1 and 3
1014 */
1015 #define DM_IO_PAGES 64
1016 static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1017 {
1018 int r;
1019 unsigned int nr_mirrors, m, args_used;
1020 struct mirror_set *ms;
1021 struct dirty_log *dl;
1022
1023 dl = create_dirty_log(ti, argc, argv, &args_used);
1024 if (!dl)
1025 return -EINVAL;
1026
1027 argv += args_used;
1028 argc -= args_used;
1029
1030 if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 ||
1031 nr_mirrors < 2 || nr_mirrors > KCOPYD_MAX_REGIONS + 1) {
1032 ti->error = "dm-mirror: Invalid number of mirrors";
1033 dm_destroy_dirty_log(dl);
1034 return -EINVAL;
1035 }
1036
1037 argv++, argc--;
1038
1039 if (argc != nr_mirrors * 2) {
1040 ti->error = "dm-mirror: Wrong number of mirror arguments";
1041 dm_destroy_dirty_log(dl);
1042 return -EINVAL;
1043 }
1044
1045 ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
1046 if (!ms) {
1047 dm_destroy_dirty_log(dl);
1048 return -ENOMEM;
1049 }
1050
1051 /* Get the mirror parameter sets */
1052 for (m = 0; m < nr_mirrors; m++) {
1053 r = get_mirror(ms, ti, m, argv);
1054 if (r) {
1055 free_context(ms, ti, m);
1056 return r;
1057 }
1058 argv += 2;
1059 argc -= 2;
1060 }
1061
1062 ti->private = ms;
1063 ti->split_io = ms->rh.region_size;
1064
1065 r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
1066 if (r) {
1067 free_context(ms, ti, ms->nr_mirrors);
1068 return r;
1069 }
1070
1071 add_mirror_set(ms);
1072 return 0;
1073 }
1074
1075 static void mirror_dtr(struct dm_target *ti)
1076 {
1077 struct mirror_set *ms = (struct mirror_set *) ti->private;
1078
1079 del_mirror_set(ms);
1080 kcopyd_client_destroy(ms->kcopyd_client);
1081 free_context(ms, ti, ms->nr_mirrors);
1082 }
1083
1084 static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
1085 {
1086 int should_wake = 0;
1087 struct bio_list *bl;
1088
1089 bl = (rw == WRITE) ? &ms->writes : &ms->reads;
1090 spin_lock(&ms->lock);
1091 should_wake = !(bl->head);
1092 bio_list_add(bl, bio);
1093 spin_unlock(&ms->lock);
1094
1095 if (should_wake)
1096 wake();
1097 }
1098
1099 /*
1100 * Mirror mapping function
1101 */
1102 static int mirror_map(struct dm_target *ti, struct bio *bio,
1103 union map_info *map_context)
1104 {
1105 int r, rw = bio_rw(bio);
1106 struct mirror *m;
1107 struct mirror_set *ms = ti->private;
1108
1109 map_context->ll = bio->bi_sector >> ms->rh.region_shift;
1110
1111 if (rw == WRITE) {
1112 queue_bio(ms, bio, rw);
1113 return 0;
1114 }
1115
1116 r = ms->rh.log->type->in_sync(ms->rh.log,
1117 bio_to_region(&ms->rh, bio), 0);
1118 if (r < 0 && r != -EWOULDBLOCK)
1119 return r;
1120
1121 if (r == -EWOULDBLOCK) /* FIXME: ugly */
1122 r = 0;
1123
1124 /*
1125 * We don't want to fast track a recovery just for a read
1126 * ahead. So we just let it silently fail.
1127 * FIXME: get rid of this.
1128 */
1129 if (!r && rw == READA)
1130 return -EIO;
1131
1132 if (!r) {
1133 /* Pass this io over to the daemon */
1134 queue_bio(ms, bio, rw);
1135 return 0;
1136 }
1137
1138 m = choose_mirror(ms, bio->bi_sector);
1139 if (!m)
1140 return -EIO;
1141
1142 map_bio(ms, m, bio);
1143 return 1;
1144 }
1145
1146 static int mirror_end_io(struct dm_target *ti, struct bio *bio,
1147 int error, union map_info *map_context)
1148 {
1149 int rw = bio_rw(bio);
1150 struct mirror_set *ms = (struct mirror_set *) ti->private;
1151 region_t region = map_context->ll;
1152
1153 /*
1154 * We need to dec pending if this was a write.
1155 */
1156 if (rw == WRITE)
1157 rh_dec(&ms->rh, region);
1158
1159 return 0;
1160 }
1161
1162 static void mirror_postsuspend(struct dm_target *ti)
1163 {
1164 struct mirror_set *ms = (struct mirror_set *) ti->private;
1165 struct dirty_log *log = ms->rh.log;
1166
1167 rh_stop_recovery(&ms->rh);
1168 if (log->type->suspend && log->type->suspend(log))
1169 /* FIXME: need better error handling */
1170 DMWARN("log suspend failed");
1171 }
1172
1173 static void mirror_resume(struct dm_target *ti)
1174 {
1175 struct mirror_set *ms = (struct mirror_set *) ti->private;
1176 struct dirty_log *log = ms->rh.log;
1177 if (log->type->resume && log->type->resume(log))
1178 /* FIXME: need better error handling */
1179 DMWARN("log resume failed");
1180 rh_start_recovery(&ms->rh);
1181 }
1182
1183 static int mirror_status(struct dm_target *ti, status_type_t type,
1184 char *result, unsigned int maxlen)
1185 {
1186 unsigned int m, sz;
1187 struct mirror_set *ms = (struct mirror_set *) ti->private;
1188
1189 sz = ms->rh.log->type->status(ms->rh.log, type, result, maxlen);
1190
1191 switch (type) {
1192 case STATUSTYPE_INFO:
1193 DMEMIT("%d ", ms->nr_mirrors);
1194 for (m = 0; m < ms->nr_mirrors; m++)
1195 DMEMIT("%s ", ms->mirror[m].dev->name);
1196
1197 DMEMIT(SECTOR_FORMAT "/" SECTOR_FORMAT,
1198 ms->rh.log->type->get_sync_count(ms->rh.log),
1199 ms->nr_regions);
1200 break;
1201
1202 case STATUSTYPE_TABLE:
1203 DMEMIT("%d ", ms->nr_mirrors);
1204 for (m = 0; m < ms->nr_mirrors; m++)
1205 DMEMIT("%s " SECTOR_FORMAT " ",
1206 ms->mirror[m].dev->name, ms->mirror[m].offset);
1207 }
1208
1209 return 0;
1210 }
1211
1212 static struct target_type mirror_target = {
1213 .name = "mirror",
1214 .version = {1, 0, 1},
1215 .module = THIS_MODULE,
1216 .ctr = mirror_ctr,
1217 .dtr = mirror_dtr,
1218 .map = mirror_map,
1219 .end_io = mirror_end_io,
1220 .postsuspend = mirror_postsuspend,
1221 .resume = mirror_resume,
1222 .status = mirror_status,
1223 };
1224
1225 static int __init dm_mirror_init(void)
1226 {
1227 int r;
1228
1229 r = dm_dirty_log_init();
1230 if (r)
1231 return r;
1232
1233 _kmirrord_wq = create_singlethread_workqueue("kmirrord");
1234 if (!_kmirrord_wq) {
1235 DMERR("couldn't start kmirrord");
1236 dm_dirty_log_exit();
1237 return r;
1238 }
1239 INIT_WORK(&_kmirrord_work, do_work, NULL);
1240
1241 r = dm_register_target(&mirror_target);
1242 if (r < 0) {
1243 DMERR("%s: Failed to register mirror target",
1244 mirror_target.name);
1245 dm_dirty_log_exit();
1246 destroy_workqueue(_kmirrord_wq);
1247 }
1248
1249 return r;
1250 }
1251
1252 static void __exit dm_mirror_exit(void)
1253 {
1254 int r;
1255
1256 r = dm_unregister_target(&mirror_target);
1257 if (r < 0)
1258 DMERR("%s: unregister failed %d", mirror_target.name, r);
1259
1260 destroy_workqueue(_kmirrord_wq);
1261 dm_dirty_log_exit();
1262 }
1263
1264 /* Module hooks */
1265 module_init(dm_mirror_init);
1266 module_exit(dm_mirror_exit);
1267
1268 MODULE_DESCRIPTION(DM_NAME " mirror target");
1269 MODULE_AUTHOR("Joe Thornber");
1270 MODULE_LICENSE("GPL");
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