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[CONNECTOR]: Update documentation to match reality.
[linux-2.6/verdex.git] / drivers / md / raid5.c
blob4683ca24c0469d0fccbfb56d33396f78d1278baf
1 /*
2 * raid5.c : Multiple Devices driver for Linux
3 * Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4 * Copyright (C) 1999, 2000 Ingo Molnar
5 *
6 * RAID-5 management functions.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2, or (at your option)
11 * any later version.
12 *
13 * You should have received a copy of the GNU General Public License
14 * (for example /usr/src/linux/COPYING); if not, write to the Free
15 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
16 */
17
18
19 #include <linux/config.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <linux/raid/raid5.h>
23 #include <linux/highmem.h>
24 #include <linux/bitops.h>
25 #include <asm/atomic.h>
26
27 #include <linux/raid/bitmap.h>
28
29 /*
30 * Stripe cache
31 */
32
33 #define NR_STRIPES 256
34 #define STRIPE_SIZE PAGE_SIZE
35 #define STRIPE_SHIFT (PAGE_SHIFT - 9)
36 #define STRIPE_SECTORS (STRIPE_SIZE>>9)
37 #define IO_THRESHOLD 1
38 #define HASH_PAGES 1
39 #define HASH_PAGES_ORDER 0
40 #define NR_HASH (HASH_PAGES * PAGE_SIZE / sizeof(struct stripe_head *))
41 #define HASH_MASK (NR_HASH - 1)
42
43 #define stripe_hash(conf, sect) ((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK])
44
45 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
46 * order without overlap. There may be several bio's per stripe+device, and
47 * a bio could span several devices.
48 * When walking this list for a particular stripe+device, we must never proceed
49 * beyond a bio that extends past this device, as the next bio might no longer
50 * be valid.
51 * This macro is used to determine the 'next' bio in the list, given the sector
52 * of the current stripe+device
53 */
54 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
55 /*
56 * The following can be used to debug the driver
57 */
58 #define RAID5_DEBUG 0
59 #define RAID5_PARANOIA 1
60 #if RAID5_PARANOIA && defined(CONFIG_SMP)
61 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
62 #else
63 # define CHECK_DEVLOCK()
64 #endif
65
66 #define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
67 #if RAID5_DEBUG
68 #define inline
69 #define __inline__
70 #endif
71
72 static void print_raid5_conf (raid5_conf_t *conf);
73
74 static inline void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
75 {
76 if (atomic_dec_and_test(&sh->count)) {
77 if (!list_empty(&sh->lru))
78 BUG();
79 if (atomic_read(&conf->active_stripes)==0)
80 BUG();
81 if (test_bit(STRIPE_HANDLE, &sh->state)) {
82 if (test_bit(STRIPE_DELAYED, &sh->state))
83 list_add_tail(&sh->lru, &conf->delayed_list);
84 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
85 conf->seq_write == sh->bm_seq)
86 list_add_tail(&sh->lru, &conf->bitmap_list);
87 else {
88 clear_bit(STRIPE_BIT_DELAY, &sh->state);
89 list_add_tail(&sh->lru, &conf->handle_list);
90 }
91 md_wakeup_thread(conf->mddev->thread);
92 } else {
93 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
94 atomic_dec(&conf->preread_active_stripes);
95 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
96 md_wakeup_thread(conf->mddev->thread);
97 }
98 list_add_tail(&sh->lru, &conf->inactive_list);
99 atomic_dec(&conf->active_stripes);
100 if (!conf->inactive_blocked ||
101 atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4))
102 wake_up(&conf->wait_for_stripe);
103 }
104 }
105 }
106 static void release_stripe(struct stripe_head *sh)
107 {
108 raid5_conf_t *conf = sh->raid_conf;
109 unsigned long flags;
110
111 spin_lock_irqsave(&conf->device_lock, flags);
112 __release_stripe(conf, sh);
113 spin_unlock_irqrestore(&conf->device_lock, flags);
114 }
115
116 static void remove_hash(struct stripe_head *sh)
117 {
118 PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
119
120 if (sh->hash_pprev) {
121 if (sh->hash_next)
122 sh->hash_next->hash_pprev = sh->hash_pprev;
123 *sh->hash_pprev = sh->hash_next;
124 sh->hash_pprev = NULL;
125 }
126 }
127
128 static __inline__ void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
129 {
130 struct stripe_head **shp = &stripe_hash(conf, sh->sector);
131
132 PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
133
134 CHECK_DEVLOCK();
135 if ((sh->hash_next = *shp) != NULL)
136 (*shp)->hash_pprev = &sh->hash_next;
137 *shp = sh;
138 sh->hash_pprev = shp;
139 }
140
141
142 /* find an idle stripe, make sure it is unhashed, and return it. */
143 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
144 {
145 struct stripe_head *sh = NULL;
146 struct list_head *first;
147
148 CHECK_DEVLOCK();
149 if (list_empty(&conf->inactive_list))
150 goto out;
151 first = conf->inactive_list.next;
152 sh = list_entry(first, struct stripe_head, lru);
153 list_del_init(first);
154 remove_hash(sh);
155 atomic_inc(&conf->active_stripes);
156 out:
157 return sh;
158 }
159
160 static void shrink_buffers(struct stripe_head *sh, int num)
161 {
162 struct page *p;
163 int i;
164
165 for (i=0; i<num ; i++) {
166 p = sh->dev[i].page;
167 if (!p)
168 continue;
169 sh->dev[i].page = NULL;
170 page_cache_release(p);
171 }
172 }
173
174 static int grow_buffers(struct stripe_head *sh, int num)
175 {
176 int i;
177
178 for (i=0; i<num; i++) {
179 struct page *page;
180
181 if (!(page = alloc_page(GFP_KERNEL))) {
182 return 1;
183 }
184 sh->dev[i].page = page;
185 }
186 return 0;
187 }
188
189 static void raid5_build_block (struct stripe_head *sh, int i);
190
191 static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
192 {
193 raid5_conf_t *conf = sh->raid_conf;
194 int disks = conf->raid_disks, i;
195
196 if (atomic_read(&sh->count) != 0)
197 BUG();
198 if (test_bit(STRIPE_HANDLE, &sh->state))
199 BUG();
200
201 CHECK_DEVLOCK();
202 PRINTK("init_stripe called, stripe %llu\n",
203 (unsigned long long)sh->sector);
204
205 remove_hash(sh);
206
207 sh->sector = sector;
208 sh->pd_idx = pd_idx;
209 sh->state = 0;
210
211 for (i=disks; i--; ) {
212 struct r5dev *dev = &sh->dev[i];
213
214 if (dev->toread || dev->towrite || dev->written ||
215 test_bit(R5_LOCKED, &dev->flags)) {
216 printk("sector=%llx i=%d %p %p %p %d\n",
217 (unsigned long long)sh->sector, i, dev->toread,
218 dev->towrite, dev->written,
219 test_bit(R5_LOCKED, &dev->flags));
220 BUG();
221 }
222 dev->flags = 0;
223 raid5_build_block(sh, i);
224 }
225 insert_hash(conf, sh);
226 }
227
228 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector)
229 {
230 struct stripe_head *sh;
231
232 CHECK_DEVLOCK();
233 PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
234 for (sh = stripe_hash(conf, sector); sh; sh = sh->hash_next)
235 if (sh->sector == sector)
236 return sh;
237 PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
238 return NULL;
239 }
240
241 static void unplug_slaves(mddev_t *mddev);
242 static void raid5_unplug_device(request_queue_t *q);
243
244 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector,
245 int pd_idx, int noblock)
246 {
247 struct stripe_head *sh;
248
249 PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
250
251 spin_lock_irq(&conf->device_lock);
252
253 do {
254 wait_event_lock_irq(conf->wait_for_stripe,
255 conf->quiesce == 0,
256 conf->device_lock, /* nothing */);
257 sh = __find_stripe(conf, sector);
258 if (!sh) {
259 if (!conf->inactive_blocked)
260 sh = get_free_stripe(conf);
261 if (noblock && sh == NULL)
262 break;
263 if (!sh) {
264 conf->inactive_blocked = 1;
265 wait_event_lock_irq(conf->wait_for_stripe,
266 !list_empty(&conf->inactive_list) &&
267 (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4)
268 || !conf->inactive_blocked),
269 conf->device_lock,
270 unplug_slaves(conf->mddev);
271 );
272 conf->inactive_blocked = 0;
273 } else
274 init_stripe(sh, sector, pd_idx);
275 } else {
276 if (atomic_read(&sh->count)) {
277 if (!list_empty(&sh->lru))
278 BUG();
279 } else {
280 if (!test_bit(STRIPE_HANDLE, &sh->state))
281 atomic_inc(&conf->active_stripes);
282 if (list_empty(&sh->lru))
283 BUG();
284 list_del_init(&sh->lru);
285 }
286 }
287 } while (sh == NULL);
288
289 if (sh)
290 atomic_inc(&sh->count);
291
292 spin_unlock_irq(&conf->device_lock);
293 return sh;
294 }
295
296 static int grow_stripes(raid5_conf_t *conf, int num)
297 {
298 struct stripe_head *sh;
299 kmem_cache_t *sc;
300 int devs = conf->raid_disks;
301
302 sprintf(conf->cache_name, "raid5/%s", mdname(conf->mddev));
303
304 sc = kmem_cache_create(conf->cache_name,
305 sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
306 0, 0, NULL, NULL);
307 if (!sc)
308 return 1;
309 conf->slab_cache = sc;
310 while (num--) {
311 sh = kmem_cache_alloc(sc, GFP_KERNEL);
312 if (!sh)
313 return 1;
314 memset(sh, 0, sizeof(*sh) + (devs-1)*sizeof(struct r5dev));
315 sh->raid_conf = conf;
316 spin_lock_init(&sh->lock);
317
318 if (grow_buffers(sh, conf->raid_disks)) {
319 shrink_buffers(sh, conf->raid_disks);
320 kmem_cache_free(sc, sh);
321 return 1;
322 }
323 /* we just created an active stripe so... */
324 atomic_set(&sh->count, 1);
325 atomic_inc(&conf->active_stripes);
326 INIT_LIST_HEAD(&sh->lru);
327 release_stripe(sh);
328 }
329 return 0;
330 }
331
332 static void shrink_stripes(raid5_conf_t *conf)
333 {
334 struct stripe_head *sh;
335
336 while (1) {
337 spin_lock_irq(&conf->device_lock);
338 sh = get_free_stripe(conf);
339 spin_unlock_irq(&conf->device_lock);
340 if (!sh)
341 break;
342 if (atomic_read(&sh->count))
343 BUG();
344 shrink_buffers(sh, conf->raid_disks);
345 kmem_cache_free(conf->slab_cache, sh);
346 atomic_dec(&conf->active_stripes);
347 }
348 kmem_cache_destroy(conf->slab_cache);
349 conf->slab_cache = NULL;
350 }
351
352 static int raid5_end_read_request (struct bio * bi, unsigned int bytes_done,
353 int error)
354 {
355 struct stripe_head *sh = bi->bi_private;
356 raid5_conf_t *conf = sh->raid_conf;
357 int disks = conf->raid_disks, i;
358 int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
359
360 if (bi->bi_size)
361 return 1;
362
363 for (i=0 ; i<disks; i++)
364 if (bi == &sh->dev[i].req)
365 break;
366
367 PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
368 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
369 uptodate);
370 if (i == disks) {
371 BUG();
372 return 0;
373 }
374
375 if (uptodate) {
376 #if 0
377 struct bio *bio;
378 unsigned long flags;
379 spin_lock_irqsave(&conf->device_lock, flags);
380 /* we can return a buffer if we bypassed the cache or
381 * if the top buffer is not in highmem. If there are
382 * multiple buffers, leave the extra work to
383 * handle_stripe
384 */
385 buffer = sh->bh_read[i];
386 if (buffer &&
387 (!PageHighMem(buffer->b_page)
388 || buffer->b_page == bh->b_page )
389 ) {
390 sh->bh_read[i] = buffer->b_reqnext;
391 buffer->b_reqnext = NULL;
392 } else
393 buffer = NULL;
394 spin_unlock_irqrestore(&conf->device_lock, flags);
395 if (sh->bh_page[i]==bh->b_page)
396 set_buffer_uptodate(bh);
397 if (buffer) {
398 if (buffer->b_page != bh->b_page)
399 memcpy(buffer->b_data, bh->b_data, bh->b_size);
400 buffer->b_end_io(buffer, 1);
401 }
402 #else
403 set_bit(R5_UPTODATE, &sh->dev[i].flags);
404 #endif
405 } else {
406 md_error(conf->mddev, conf->disks[i].rdev);
407 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
408 }
409 rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
410 #if 0
411 /* must restore b_page before unlocking buffer... */
412 if (sh->bh_page[i] != bh->b_page) {
413 bh->b_page = sh->bh_page[i];
414 bh->b_data = page_address(bh->b_page);
415 clear_buffer_uptodate(bh);
416 }
417 #endif
418 clear_bit(R5_LOCKED, &sh->dev[i].flags);
419 set_bit(STRIPE_HANDLE, &sh->state);
420 release_stripe(sh);
421 return 0;
422 }
423
424 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
425 int error)
426 {
427 struct stripe_head *sh = bi->bi_private;
428 raid5_conf_t *conf = sh->raid_conf;
429 int disks = conf->raid_disks, i;
430 unsigned long flags;
431 int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
432
433 if (bi->bi_size)
434 return 1;
435
436 for (i=0 ; i<disks; i++)
437 if (bi == &sh->dev[i].req)
438 break;
439
440 PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
441 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
442 uptodate);
443 if (i == disks) {
444 BUG();
445 return 0;
446 }
447
448 spin_lock_irqsave(&conf->device_lock, flags);
449 if (!uptodate)
450 md_error(conf->mddev, conf->disks[i].rdev);
451
452 rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
453
454 clear_bit(R5_LOCKED, &sh->dev[i].flags);
455 set_bit(STRIPE_HANDLE, &sh->state);
456 __release_stripe(conf, sh);
457 spin_unlock_irqrestore(&conf->device_lock, flags);
458 return 0;
459 }
460
461
462 static sector_t compute_blocknr(struct stripe_head *sh, int i);
463
464 static void raid5_build_block (struct stripe_head *sh, int i)
465 {
466 struct r5dev *dev = &sh->dev[i];
467
468 bio_init(&dev->req);
469 dev->req.bi_io_vec = &dev->vec;
470 dev->req.bi_vcnt++;
471 dev->req.bi_max_vecs++;
472 dev->vec.bv_page = dev->page;
473 dev->vec.bv_len = STRIPE_SIZE;
474 dev->vec.bv_offset = 0;
475
476 dev->req.bi_sector = sh->sector;
477 dev->req.bi_private = sh;
478
479 dev->flags = 0;
480 if (i != sh->pd_idx)
481 dev->sector = compute_blocknr(sh, i);
482 }
483
484 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
485 {
486 char b[BDEVNAME_SIZE];
487 raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
488 PRINTK("raid5: error called\n");
489
490 if (!rdev->faulty) {
491 mddev->sb_dirty = 1;
492 if (rdev->in_sync) {
493 conf->working_disks--;
494 mddev->degraded++;
495 conf->failed_disks++;
496 rdev->in_sync = 0;
497 /*
498 * if recovery was running, make sure it aborts.
499 */
500 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
501 }
502 rdev->faulty = 1;
503 printk (KERN_ALERT
504 "raid5: Disk failure on %s, disabling device."
505 " Operation continuing on %d devices\n",
506 bdevname(rdev->bdev,b), conf->working_disks);
507 }
508 }
509
510 /*
511 * Input: a 'big' sector number,
512 * Output: index of the data and parity disk, and the sector # in them.
513 */
514 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
515 unsigned int data_disks, unsigned int * dd_idx,
516 unsigned int * pd_idx, raid5_conf_t *conf)
517 {
518 long stripe;
519 unsigned long chunk_number;
520 unsigned int chunk_offset;
521 sector_t new_sector;
522 int sectors_per_chunk = conf->chunk_size >> 9;
523
524 /* First compute the information on this sector */
525
526 /*
527 * Compute the chunk number and the sector offset inside the chunk
528 */
529 chunk_offset = sector_div(r_sector, sectors_per_chunk);
530 chunk_number = r_sector;
531 BUG_ON(r_sector != chunk_number);
532
533 /*
534 * Compute the stripe number
535 */
536 stripe = chunk_number / data_disks;
537
538 /*
539 * Compute the data disk and parity disk indexes inside the stripe
540 */
541 *dd_idx = chunk_number % data_disks;
542
543 /*
544 * Select the parity disk based on the user selected algorithm.
545 */
546 if (conf->level == 4)
547 *pd_idx = data_disks;
548 else switch (conf->algorithm) {
549 case ALGORITHM_LEFT_ASYMMETRIC:
550 *pd_idx = data_disks - stripe % raid_disks;
551 if (*dd_idx >= *pd_idx)
552 (*dd_idx)++;
553 break;
554 case ALGORITHM_RIGHT_ASYMMETRIC:
555 *pd_idx = stripe % raid_disks;
556 if (*dd_idx >= *pd_idx)
557 (*dd_idx)++;
558 break;
559 case ALGORITHM_LEFT_SYMMETRIC:
560 *pd_idx = data_disks - stripe % raid_disks;
561 *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
562 break;
563 case ALGORITHM_RIGHT_SYMMETRIC:
564 *pd_idx = stripe % raid_disks;
565 *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
566 break;
567 default:
568 printk("raid5: unsupported algorithm %d\n",
569 conf->algorithm);
570 }
571
572 /*
573 * Finally, compute the new sector number
574 */
575 new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
576 return new_sector;
577 }
578
579
580 static sector_t compute_blocknr(struct stripe_head *sh, int i)
581 {
582 raid5_conf_t *conf = sh->raid_conf;
583 int raid_disks = conf->raid_disks, data_disks = raid_disks - 1;
584 sector_t new_sector = sh->sector, check;
585 int sectors_per_chunk = conf->chunk_size >> 9;
586 sector_t stripe;
587 int chunk_offset;
588 int chunk_number, dummy1, dummy2, dd_idx = i;
589 sector_t r_sector;
590
591 chunk_offset = sector_div(new_sector, sectors_per_chunk);
592 stripe = new_sector;
593 BUG_ON(new_sector != stripe);
594
595
596 switch (conf->algorithm) {
597 case ALGORITHM_LEFT_ASYMMETRIC:
598 case ALGORITHM_RIGHT_ASYMMETRIC:
599 if (i > sh->pd_idx)
600 i--;
601 break;
602 case ALGORITHM_LEFT_SYMMETRIC:
603 case ALGORITHM_RIGHT_SYMMETRIC:
604 if (i < sh->pd_idx)
605 i += raid_disks;
606 i -= (sh->pd_idx + 1);
607 break;
608 default:
609 printk("raid5: unsupported algorithm %d\n",
610 conf->algorithm);
611 }
612
613 chunk_number = stripe * data_disks + i;
614 r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
615
616 check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
617 if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
618 printk("compute_blocknr: map not correct\n");
619 return 0;
620 }
621 return r_sector;
622 }
623
624
625
626 /*
627 * Copy data between a page in the stripe cache, and a bio.
628 * There are no alignment or size guarantees between the page or the
629 * bio except that there is some overlap.
630 * All iovecs in the bio must be considered.
631 */
632 static void copy_data(int frombio, struct bio *bio,
633 struct page *page,
634 sector_t sector)
635 {
636 char *pa = page_address(page);
637 struct bio_vec *bvl;
638 int i;
639 int page_offset;
640
641 if (bio->bi_sector >= sector)
642 page_offset = (signed)(bio->bi_sector - sector) * 512;
643 else
644 page_offset = (signed)(sector - bio->bi_sector) * -512;
645 bio_for_each_segment(bvl, bio, i) {
646 int len = bio_iovec_idx(bio,i)->bv_len;
647 int clen;
648 int b_offset = 0;
649
650 if (page_offset < 0) {
651 b_offset = -page_offset;
652 page_offset += b_offset;
653 len -= b_offset;
654 }
655
656 if (len > 0 && page_offset + len > STRIPE_SIZE)
657 clen = STRIPE_SIZE - page_offset;
658 else clen = len;
659
660 if (clen > 0) {
661 char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
662 if (frombio)
663 memcpy(pa+page_offset, ba+b_offset, clen);
664 else
665 memcpy(ba+b_offset, pa+page_offset, clen);
666 __bio_kunmap_atomic(ba, KM_USER0);
667 }
668 if (clen < len) /* hit end of page */
669 break;
670 page_offset += len;
671 }
672 }
673
674 #define check_xor() do { \
675 if (count == MAX_XOR_BLOCKS) { \
676 xor_block(count, STRIPE_SIZE, ptr); \
677 count = 1; \
678 } \
679 } while(0)
680
681
682 static void compute_block(struct stripe_head *sh, int dd_idx)
683 {
684 raid5_conf_t *conf = sh->raid_conf;
685 int i, count, disks = conf->raid_disks;
686 void *ptr[MAX_XOR_BLOCKS], *p;
687
688 PRINTK("compute_block, stripe %llu, idx %d\n",
689 (unsigned long long)sh->sector, dd_idx);
690
691 ptr[0] = page_address(sh->dev[dd_idx].page);
692 memset(ptr[0], 0, STRIPE_SIZE);
693 count = 1;
694 for (i = disks ; i--; ) {
695 if (i == dd_idx)
696 continue;
697 p = page_address(sh->dev[i].page);
698 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
699 ptr[count++] = p;
700 else
701 printk("compute_block() %d, stripe %llu, %d"
702 " not present\n", dd_idx,
703 (unsigned long long)sh->sector, i);
704
705 check_xor();
706 }
707 if (count != 1)
708 xor_block(count, STRIPE_SIZE, ptr);
709 set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
710 }
711
712 static void compute_parity(struct stripe_head *sh, int method)
713 {
714 raid5_conf_t *conf = sh->raid_conf;
715 int i, pd_idx = sh->pd_idx, disks = conf->raid_disks, count;
716 void *ptr[MAX_XOR_BLOCKS];
717 struct bio *chosen;
718
719 PRINTK("compute_parity, stripe %llu, method %d\n",
720 (unsigned long long)sh->sector, method);
721
722 count = 1;
723 ptr[0] = page_address(sh->dev[pd_idx].page);
724 switch(method) {
725 case READ_MODIFY_WRITE:
726 if (!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags))
727 BUG();
728 for (i=disks ; i-- ;) {
729 if (i==pd_idx)
730 continue;
731 if (sh->dev[i].towrite &&
732 test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
733 ptr[count++] = page_address(sh->dev[i].page);
734 chosen = sh->dev[i].towrite;
735 sh->dev[i].towrite = NULL;
736
737 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
738 wake_up(&conf->wait_for_overlap);
739
740 if (sh->dev[i].written) BUG();
741 sh->dev[i].written = chosen;
742 check_xor();
743 }
744 }
745 break;
746 case RECONSTRUCT_WRITE:
747 memset(ptr[0], 0, STRIPE_SIZE);
748 for (i= disks; i-- ;)
749 if (i!=pd_idx && sh->dev[i].towrite) {
750 chosen = sh->dev[i].towrite;
751 sh->dev[i].towrite = NULL;
752
753 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
754 wake_up(&conf->wait_for_overlap);
755
756 if (sh->dev[i].written) BUG();
757 sh->dev[i].written = chosen;
758 }
759 break;
760 case CHECK_PARITY:
761 break;
762 }
763 if (count>1) {
764 xor_block(count, STRIPE_SIZE, ptr);
765 count = 1;
766 }
767
768 for (i = disks; i--;)
769 if (sh->dev[i].written) {
770 sector_t sector = sh->dev[i].sector;
771 struct bio *wbi = sh->dev[i].written;
772 while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
773 copy_data(1, wbi, sh->dev[i].page, sector);
774 wbi = r5_next_bio(wbi, sector);
775 }
776
777 set_bit(R5_LOCKED, &sh->dev[i].flags);
778 set_bit(R5_UPTODATE, &sh->dev[i].flags);
779 }
780
781 switch(method) {
782 case RECONSTRUCT_WRITE:
783 case CHECK_PARITY:
784 for (i=disks; i--;)
785 if (i != pd_idx) {
786 ptr[count++] = page_address(sh->dev[i].page);
787 check_xor();
788 }
789 break;
790 case READ_MODIFY_WRITE:
791 for (i = disks; i--;)
792 if (sh->dev[i].written) {
793 ptr[count++] = page_address(sh->dev[i].page);
794 check_xor();
795 }
796 }
797 if (count != 1)
798 xor_block(count, STRIPE_SIZE, ptr);
799
800 if (method != CHECK_PARITY) {
801 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
802 set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
803 } else
804 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
805 }
806
807 /*
808 * Each stripe/dev can have one or more bion attached.
809 * toread/towrite point to the first in a chain.
810 * The bi_next chain must be in order.
811 */
812 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
813 {
814 struct bio **bip;
815 raid5_conf_t *conf = sh->raid_conf;
816 int firstwrite=0;
817
818 PRINTK("adding bh b#%llu to stripe s#%llu\n",
819 (unsigned long long)bi->bi_sector,
820 (unsigned long long)sh->sector);
821
822
823 spin_lock(&sh->lock);
824 spin_lock_irq(&conf->device_lock);
825 if (forwrite) {
826 bip = &sh->dev[dd_idx].towrite;
827 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
828 firstwrite = 1;
829 } else
830 bip = &sh->dev[dd_idx].toread;
831 while (*bip && (*bip)->bi_sector < bi->bi_sector) {
832 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
833 goto overlap;
834 bip = & (*bip)->bi_next;
835 }
836 if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
837 goto overlap;
838
839 if (*bip && bi->bi_next && (*bip) != bi->bi_next)
840 BUG();
841 if (*bip)
842 bi->bi_next = *bip;
843 *bip = bi;
844 bi->bi_phys_segments ++;
845 spin_unlock_irq(&conf->device_lock);
846 spin_unlock(&sh->lock);
847
848 PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
849 (unsigned long long)bi->bi_sector,
850 (unsigned long long)sh->sector, dd_idx);
851
852 if (conf->mddev->bitmap && firstwrite) {
853 sh->bm_seq = conf->seq_write;
854 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
855 STRIPE_SECTORS, 0);
856 set_bit(STRIPE_BIT_DELAY, &sh->state);
857 }
858
859 if (forwrite) {
860 /* check if page is covered */
861 sector_t sector = sh->dev[dd_idx].sector;
862 for (bi=sh->dev[dd_idx].towrite;
863 sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
864 bi && bi->bi_sector <= sector;
865 bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
866 if (bi->bi_sector + (bi->bi_size>>9) >= sector)
867 sector = bi->bi_sector + (bi->bi_size>>9);
868 }
869 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
870 set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
871 }
872 return 1;
873
874 overlap:
875 set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
876 spin_unlock_irq(&conf->device_lock);
877 spin_unlock(&sh->lock);
878 return 0;
879 }
880
881
882 /*
883 * handle_stripe - do things to a stripe.
884 *
885 * We lock the stripe and then examine the state of various bits
886 * to see what needs to be done.
887 * Possible results:
888 * return some read request which now have data
889 * return some write requests which are safely on disc
890 * schedule a read on some buffers
891 * schedule a write of some buffers
892 * return confirmation of parity correctness
893 *
894 * Parity calculations are done inside the stripe lock
895 * buffers are taken off read_list or write_list, and bh_cache buffers
896 * get BH_Lock set before the stripe lock is released.
897 *
898 */
899
900 static void handle_stripe(struct stripe_head *sh)
901 {
902 raid5_conf_t *conf = sh->raid_conf;
903 int disks = conf->raid_disks;
904 struct bio *return_bi= NULL;
905 struct bio *bi;
906 int i;
907 int syncing;
908 int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
909 int non_overwrite = 0;
910 int failed_num=0;
911 struct r5dev *dev;
912
913 PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n",
914 (unsigned long long)sh->sector, atomic_read(&sh->count),
915 sh->pd_idx);
916
917 spin_lock(&sh->lock);
918 clear_bit(STRIPE_HANDLE, &sh->state);
919 clear_bit(STRIPE_DELAYED, &sh->state);
920
921 syncing = test_bit(STRIPE_SYNCING, &sh->state);
922 /* Now to look around and see what can be done */
923
924 for (i=disks; i--; ) {
925 mdk_rdev_t *rdev;
926 dev = &sh->dev[i];
927 clear_bit(R5_Insync, &dev->flags);
928 clear_bit(R5_Syncio, &dev->flags);
929
930 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
931 i, dev->flags, dev->toread, dev->towrite, dev->written);
932 /* maybe we can reply to a read */
933 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
934 struct bio *rbi, *rbi2;
935 PRINTK("Return read for disc %d\n", i);
936 spin_lock_irq(&conf->device_lock);
937 rbi = dev->toread;
938 dev->toread = NULL;
939 if (test_and_clear_bit(R5_Overlap, &dev->flags))
940 wake_up(&conf->wait_for_overlap);
941 spin_unlock_irq(&conf->device_lock);
942 while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
943 copy_data(0, rbi, dev->page, dev->sector);
944 rbi2 = r5_next_bio(rbi, dev->sector);
945 spin_lock_irq(&conf->device_lock);
946 if (--rbi->bi_phys_segments == 0) {
947 rbi->bi_next = return_bi;
948 return_bi = rbi;
949 }
950 spin_unlock_irq(&conf->device_lock);
951 rbi = rbi2;
952 }
953 }
954
955 /* now count some things */
956 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
957 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
958
959
960 if (dev->toread) to_read++;
961 if (dev->towrite) {
962 to_write++;
963 if (!test_bit(R5_OVERWRITE, &dev->flags))
964 non_overwrite++;
965 }
966 if (dev->written) written++;
967 rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */
968 if (!rdev || !rdev->in_sync) {
969 failed++;
970 failed_num = i;
971 } else
972 set_bit(R5_Insync, &dev->flags);
973 }
974 PRINTK("locked=%d uptodate=%d to_read=%d"
975 " to_write=%d failed=%d failed_num=%d\n",
976 locked, uptodate, to_read, to_write, failed, failed_num);
977 /* check if the array has lost two devices and, if so, some requests might
978 * need to be failed
979 */
980 if (failed > 1 && to_read+to_write+written) {
981 for (i=disks; i--; ) {
982 int bitmap_end = 0;
983 spin_lock_irq(&conf->device_lock);
984 /* fail all writes first */
985 bi = sh->dev[i].towrite;
986 sh->dev[i].towrite = NULL;
987 if (bi) { to_write--; bitmap_end = 1; }
988
989 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
990 wake_up(&conf->wait_for_overlap);
991
992 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
993 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
994 clear_bit(BIO_UPTODATE, &bi->bi_flags);
995 if (--bi->bi_phys_segments == 0) {
996 md_write_end(conf->mddev);
997 bi->bi_next = return_bi;
998 return_bi = bi;
999 }
1000 bi = nextbi;
1001 }
1002 /* and fail all 'written' */
1003 bi = sh->dev[i].written;
1004 sh->dev[i].written = NULL;
1005 if (bi) bitmap_end = 1;
1006 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
1007 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1008 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1009 if (--bi->bi_phys_segments == 0) {
1010 md_write_end(conf->mddev);
1011 bi->bi_next = return_bi;
1012 return_bi = bi;
1013 }
1014 bi = bi2;
1015 }
1016
1017 /* fail any reads if this device is non-operational */
1018 if (!test_bit(R5_Insync, &sh->dev[i].flags)) {
1019 bi = sh->dev[i].toread;
1020 sh->dev[i].toread = NULL;
1021 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1022 wake_up(&conf->wait_for_overlap);
1023 if (bi) to_read--;
1024 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1025 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1026 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1027 if (--bi->bi_phys_segments == 0) {
1028 bi->bi_next = return_bi;
1029 return_bi = bi;
1030 }
1031 bi = nextbi;
1032 }
1033 }
1034 spin_unlock_irq(&conf->device_lock);
1035 if (bitmap_end)
1036 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1037 STRIPE_SECTORS, 0, 0);
1038 }
1039 }
1040 if (failed > 1 && syncing) {
1041 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1042 clear_bit(STRIPE_SYNCING, &sh->state);
1043 syncing = 0;
1044 }
1045
1046 /* might be able to return some write requests if the parity block
1047 * is safe, or on a failed drive
1048 */
1049 dev = &sh->dev[sh->pd_idx];
1050 if ( written &&
1051 ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) &&
1052 test_bit(R5_UPTODATE, &dev->flags))
1053 || (failed == 1 && failed_num == sh->pd_idx))
1054 ) {
1055 /* any written block on an uptodate or failed drive can be returned.
1056 * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
1057 * never LOCKED, so we don't need to test 'failed' directly.
1058 */
1059 for (i=disks; i--; )
1060 if (sh->dev[i].written) {
1061 dev = &sh->dev[i];
1062 if (!test_bit(R5_LOCKED, &dev->flags) &&
1063 test_bit(R5_UPTODATE, &dev->flags) ) {
1064 /* We can return any write requests */
1065 struct bio *wbi, *wbi2;
1066 int bitmap_end = 0;
1067 PRINTK("Return write for disc %d\n", i);
1068 spin_lock_irq(&conf->device_lock);
1069 wbi = dev->written;
1070 dev->written = NULL;
1071 while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1072 wbi2 = r5_next_bio(wbi, dev->sector);
1073 if (--wbi->bi_phys_segments == 0) {
1074 md_write_end(conf->mddev);
1075 wbi->bi_next = return_bi;
1076 return_bi = wbi;
1077 }
1078 wbi = wbi2;
1079 }
1080 if (dev->towrite == NULL)
1081 bitmap_end = 1;
1082 spin_unlock_irq(&conf->device_lock);
1083 if (bitmap_end)
1084 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1085 STRIPE_SECTORS,
1086 !test_bit(STRIPE_DEGRADED, &sh->state), 0);
1087 }
1088 }
1089 }
1090
1091 /* Now we might consider reading some blocks, either to check/generate
1092 * parity, or to satisfy requests
1093 * or to load a block that is being partially written.
1094 */
1095 if (to_read || non_overwrite || (syncing && (uptodate < disks))) {
1096 for (i=disks; i--;) {
1097 dev = &sh->dev[i];
1098 if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1099 (dev->toread ||
1100 (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1101 syncing ||
1102 (failed && (sh->dev[failed_num].toread ||
1103 (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
1104 )
1105 ) {
1106 /* we would like to get this block, possibly
1107 * by computing it, but we might not be able to
1108 */
1109 if (uptodate == disks-1) {
1110 PRINTK("Computing block %d\n", i);
1111 compute_block(sh, i);
1112 uptodate++;
1113 } else if (test_bit(R5_Insync, &dev->flags)) {
1114 set_bit(R5_LOCKED, &dev->flags);
1115 set_bit(R5_Wantread, &dev->flags);
1116 #if 0
1117 /* if I am just reading this block and we don't have
1118 a failed drive, or any pending writes then sidestep the cache */
1119 if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
1120 ! syncing && !failed && !to_write) {
1121 sh->bh_cache[i]->b_page = sh->bh_read[i]->b_page;
1122 sh->bh_cache[i]->b_data = sh->bh_read[i]->b_data;
1123 }
1124 #endif
1125 locked++;
1126 PRINTK("Reading block %d (sync=%d)\n",
1127 i, syncing);
1128 if (syncing)
1129 md_sync_acct(conf->disks[i].rdev->bdev,
1130 STRIPE_SECTORS);
1131 }
1132 }
1133 }
1134 set_bit(STRIPE_HANDLE, &sh->state);
1135 }
1136
1137 /* now to consider writing and what else, if anything should be read */
1138 if (to_write) {
1139 int rmw=0, rcw=0;
1140 for (i=disks ; i--;) {
1141 /* would I have to read this buffer for read_modify_write */
1142 dev = &sh->dev[i];
1143 if ((dev->towrite || i == sh->pd_idx) &&
1144 (!test_bit(R5_LOCKED, &dev->flags)
1145 #if 0
1146 || sh->bh_page[i]!=bh->b_page
1147 #endif
1148 ) &&
1149 !test_bit(R5_UPTODATE, &dev->flags)) {
1150 if (test_bit(R5_Insync, &dev->flags)
1151 /* && !(!mddev->insync && i == sh->pd_idx) */
1152 )
1153 rmw++;
1154 else rmw += 2*disks; /* cannot read it */
1155 }
1156 /* Would I have to read this buffer for reconstruct_write */
1157 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1158 (!test_bit(R5_LOCKED, &dev->flags)
1159 #if 0
1160 || sh->bh_page[i] != bh->b_page
1161 #endif
1162 ) &&
1163 !test_bit(R5_UPTODATE, &dev->flags)) {
1164 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1165 else rcw += 2*disks;
1166 }
1167 }
1168 PRINTK("for sector %llu, rmw=%d rcw=%d\n",
1169 (unsigned long long)sh->sector, rmw, rcw);
1170 set_bit(STRIPE_HANDLE, &sh->state);
1171 if (rmw < rcw && rmw > 0)
1172 /* prefer read-modify-write, but need to get some data */
1173 for (i=disks; i--;) {
1174 dev = &sh->dev[i];
1175 if ((dev->towrite || i == sh->pd_idx) &&
1176 !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1177 test_bit(R5_Insync, &dev->flags)) {
1178 if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1179 {
1180 PRINTK("Read_old block %d for r-m-w\n", i);
1181 set_bit(R5_LOCKED, &dev->flags);
1182 set_bit(R5_Wantread, &dev->flags);
1183 locked++;
1184 } else {
1185 set_bit(STRIPE_DELAYED, &sh->state);
1186 set_bit(STRIPE_HANDLE, &sh->state);
1187 }
1188 }
1189 }
1190 if (rcw <= rmw && rcw > 0)
1191 /* want reconstruct write, but need to get some data */
1192 for (i=disks; i--;) {
1193 dev = &sh->dev[i];
1194 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1195 !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1196 test_bit(R5_Insync, &dev->flags)) {
1197 if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1198 {
1199 PRINTK("Read_old block %d for Reconstruct\n", i);
1200 set_bit(R5_LOCKED, &dev->flags);
1201 set_bit(R5_Wantread, &dev->flags);
1202 locked++;
1203 } else {
1204 set_bit(STRIPE_DELAYED, &sh->state);
1205 set_bit(STRIPE_HANDLE, &sh->state);
1206 }
1207 }
1208 }
1209 /* now if nothing is locked, and if we have enough data, we can start a write request */
1210 if (locked == 0 && (rcw == 0 ||rmw == 0) &&
1211 !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
1212 PRINTK("Computing parity...\n");
1213 compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
1214 /* now every locked buffer is ready to be written */
1215 for (i=disks; i--;)
1216 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1217 PRINTK("Writing block %d\n", i);
1218 locked++;
1219 set_bit(R5_Wantwrite, &sh->dev[i].flags);
1220 if (!test_bit(R5_Insync, &sh->dev[i].flags)
1221 || (i==sh->pd_idx && failed == 0))
1222 set_bit(STRIPE_INSYNC, &sh->state);
1223 }
1224 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1225 atomic_dec(&conf->preread_active_stripes);
1226 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1227 md_wakeup_thread(conf->mddev->thread);
1228 }
1229 }
1230 }
1231
1232 /* maybe we need to check and possibly fix the parity for this stripe
1233 * Any reads will already have been scheduled, so we just see if enough data
1234 * is available
1235 */
1236 if (syncing && locked == 0 &&
1237 !test_bit(STRIPE_INSYNC, &sh->state) && failed <= 1) {
1238 set_bit(STRIPE_HANDLE, &sh->state);
1239 if (failed == 0) {
1240 char *pagea;
1241 if (uptodate != disks)
1242 BUG();
1243 compute_parity(sh, CHECK_PARITY);
1244 uptodate--;
1245 pagea = page_address(sh->dev[sh->pd_idx].page);
1246 if ((*(u32*)pagea) == 0 &&
1247 !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
1248 /* parity is correct (on disc, not in buffer any more) */
1249 set_bit(STRIPE_INSYNC, &sh->state);
1250 }
1251 }
1252 if (!test_bit(STRIPE_INSYNC, &sh->state)) {
1253 if (failed==0)
1254 failed_num = sh->pd_idx;
1255 /* should be able to compute the missing block and write it to spare */
1256 if (!test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)) {
1257 if (uptodate+1 != disks)
1258 BUG();
1259 compute_block(sh, failed_num);
1260 uptodate++;
1261 }
1262 if (uptodate != disks)
1263 BUG();
1264 dev = &sh->dev[failed_num];
1265 set_bit(R5_LOCKED, &dev->flags);
1266 set_bit(R5_Wantwrite, &dev->flags);
1267 clear_bit(STRIPE_DEGRADED, &sh->state);
1268 locked++;
1269 set_bit(STRIPE_INSYNC, &sh->state);
1270 set_bit(R5_Syncio, &dev->flags);
1271 }
1272 }
1273 if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1274 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1275 clear_bit(STRIPE_SYNCING, &sh->state);
1276 }
1277
1278 spin_unlock(&sh->lock);
1279
1280 while ((bi=return_bi)) {
1281 int bytes = bi->bi_size;
1282
1283 return_bi = bi->bi_next;
1284 bi->bi_next = NULL;
1285 bi->bi_size = 0;
1286 bi->bi_end_io(bi, bytes, 0);
1287 }
1288 for (i=disks; i-- ;) {
1289 int rw;
1290 struct bio *bi;
1291 mdk_rdev_t *rdev;
1292 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1293 rw = 1;
1294 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1295 rw = 0;
1296 else
1297 continue;
1298
1299 bi = &sh->dev[i].req;
1300
1301 bi->bi_rw = rw;
1302 if (rw)
1303 bi->bi_end_io = raid5_end_write_request;
1304 else
1305 bi->bi_end_io = raid5_end_read_request;
1306
1307 rcu_read_lock();
1308 rdev = conf->disks[i].rdev;
1309 if (rdev && rdev->faulty)
1310 rdev = NULL;
1311 if (rdev)
1312 atomic_inc(&rdev->nr_pending);
1313 rcu_read_unlock();
1314
1315 if (rdev) {
1316 if (test_bit(R5_Syncio, &sh->dev[i].flags))
1317 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1318
1319 bi->bi_bdev = rdev->bdev;
1320 PRINTK("for %llu schedule op %ld on disc %d\n",
1321 (unsigned long long)sh->sector, bi->bi_rw, i);
1322 atomic_inc(&sh->count);
1323 bi->bi_sector = sh->sector + rdev->data_offset;
1324 bi->bi_flags = 1 << BIO_UPTODATE;
1325 bi->bi_vcnt = 1;
1326 bi->bi_max_vecs = 1;
1327 bi->bi_idx = 0;
1328 bi->bi_io_vec = &sh->dev[i].vec;
1329 bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1330 bi->bi_io_vec[0].bv_offset = 0;
1331 bi->bi_size = STRIPE_SIZE;
1332 bi->bi_next = NULL;
1333 generic_make_request(bi);
1334 } else {
1335 if (rw == 1)
1336 set_bit(STRIPE_DEGRADED, &sh->state);
1337 PRINTK("skip op %ld on disc %d for sector %llu\n",
1338 bi->bi_rw, i, (unsigned long long)sh->sector);
1339 clear_bit(R5_LOCKED, &sh->dev[i].flags);
1340 set_bit(STRIPE_HANDLE, &sh->state);
1341 }
1342 }
1343 }
1344
1345 static inline void raid5_activate_delayed(raid5_conf_t *conf)
1346 {
1347 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
1348 while (!list_empty(&conf->delayed_list)) {
1349 struct list_head *l = conf->delayed_list.next;
1350 struct stripe_head *sh;
1351 sh = list_entry(l, struct stripe_head, lru);
1352 list_del_init(l);
1353 clear_bit(STRIPE_DELAYED, &sh->state);
1354 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1355 atomic_inc(&conf->preread_active_stripes);
1356 list_add_tail(&sh->lru, &conf->handle_list);
1357 }
1358 }
1359 }
1360
1361 static inline void activate_bit_delay(raid5_conf_t *conf)
1362 {
1363 /* device_lock is held */
1364 struct list_head head;
1365 list_add(&head, &conf->bitmap_list);
1366 list_del_init(&conf->bitmap_list);
1367 while (!list_empty(&head)) {
1368 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
1369 list_del_init(&sh->lru);
1370 atomic_inc(&sh->count);
1371 __release_stripe(conf, sh);
1372 }
1373 }
1374
1375 static void unplug_slaves(mddev_t *mddev)
1376 {
1377 raid5_conf_t *conf = mddev_to_conf(mddev);
1378 int i;
1379
1380 rcu_read_lock();
1381 for (i=0; i<mddev->raid_disks; i++) {
1382 mdk_rdev_t *rdev = conf->disks[i].rdev;
1383 if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
1384 request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
1385
1386 atomic_inc(&rdev->nr_pending);
1387 rcu_read_unlock();
1388
1389 if (r_queue->unplug_fn)
1390 r_queue->unplug_fn(r_queue);
1391
1392 rdev_dec_pending(rdev, mddev);
1393 rcu_read_lock();
1394 }
1395 }
1396 rcu_read_unlock();
1397 }
1398
1399 static void raid5_unplug_device(request_queue_t *q)
1400 {
1401 mddev_t *mddev = q->queuedata;
1402 raid5_conf_t *conf = mddev_to_conf(mddev);
1403 unsigned long flags;
1404
1405 spin_lock_irqsave(&conf->device_lock, flags);
1406
1407 if (blk_remove_plug(q)) {
1408 conf->seq_flush++;
1409 raid5_activate_delayed(conf);
1410 }
1411 md_wakeup_thread(mddev->thread);
1412
1413 spin_unlock_irqrestore(&conf->device_lock, flags);
1414
1415 unplug_slaves(mddev);
1416 }
1417
1418 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
1419 sector_t *error_sector)
1420 {
1421 mddev_t *mddev = q->queuedata;
1422 raid5_conf_t *conf = mddev_to_conf(mddev);
1423 int i, ret = 0;
1424
1425 rcu_read_lock();
1426 for (i=0; i<mddev->raid_disks && ret == 0; i++) {
1427 mdk_rdev_t *rdev = conf->disks[i].rdev;
1428 if (rdev && !rdev->faulty) {
1429 struct block_device *bdev = rdev->bdev;
1430 request_queue_t *r_queue = bdev_get_queue(bdev);
1431
1432 if (!r_queue->issue_flush_fn)
1433 ret = -EOPNOTSUPP;
1434 else {
1435 atomic_inc(&rdev->nr_pending);
1436 rcu_read_unlock();
1437 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
1438 error_sector);
1439 rdev_dec_pending(rdev, mddev);
1440 rcu_read_lock();
1441 }
1442 }
1443 }
1444 rcu_read_unlock();
1445 return ret;
1446 }
1447
1448 static inline void raid5_plug_device(raid5_conf_t *conf)
1449 {
1450 spin_lock_irq(&conf->device_lock);
1451 blk_plug_device(conf->mddev->queue);
1452 spin_unlock_irq(&conf->device_lock);
1453 }
1454
1455 static int make_request (request_queue_t *q, struct bio * bi)
1456 {
1457 mddev_t *mddev = q->queuedata;
1458 raid5_conf_t *conf = mddev_to_conf(mddev);
1459 const unsigned int raid_disks = conf->raid_disks;
1460 const unsigned int data_disks = raid_disks - 1;
1461 unsigned int dd_idx, pd_idx;
1462 sector_t new_sector;
1463 sector_t logical_sector, last_sector;
1464 struct stripe_head *sh;
1465
1466 if (unlikely(bio_barrier(bi))) {
1467 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
1468 return 0;
1469 }
1470
1471 md_write_start(mddev, bi);
1472
1473 if (bio_data_dir(bi)==WRITE) {
1474 disk_stat_inc(mddev->gendisk, writes);
1475 disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi));
1476 } else {
1477 disk_stat_inc(mddev->gendisk, reads);
1478 disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bi));
1479 }
1480
1481 logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
1482 last_sector = bi->bi_sector + (bi->bi_size>>9);
1483 bi->bi_next = NULL;
1484 bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
1485
1486 for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
1487 DEFINE_WAIT(w);
1488
1489 new_sector = raid5_compute_sector(logical_sector,
1490 raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1491
1492 PRINTK("raid5: make_request, sector %llu logical %llu\n",
1493 (unsigned long long)new_sector,
1494 (unsigned long long)logical_sector);
1495
1496 retry:
1497 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
1498 sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
1499 if (sh) {
1500 if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
1501 /* Add failed due to overlap. Flush everything
1502 * and wait a while
1503 */
1504 raid5_unplug_device(mddev->queue);
1505 release_stripe(sh);
1506 schedule();
1507 goto retry;
1508 }
1509 finish_wait(&conf->wait_for_overlap, &w);
1510 raid5_plug_device(conf);
1511 handle_stripe(sh);
1512 release_stripe(sh);
1513
1514 } else {
1515 /* cannot get stripe for read-ahead, just give-up */
1516 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1517 finish_wait(&conf->wait_for_overlap, &w);
1518 break;
1519 }
1520
1521 }
1522 spin_lock_irq(&conf->device_lock);
1523 if (--bi->bi_phys_segments == 0) {
1524 int bytes = bi->bi_size;
1525
1526 if ( bio_data_dir(bi) == WRITE )
1527 md_write_end(mddev);
1528 bi->bi_size = 0;
1529 bi->bi_end_io(bi, bytes, 0);
1530 }
1531 spin_unlock_irq(&conf->device_lock);
1532 return 0;
1533 }
1534
1535 /* FIXME go_faster isn't used */
1536 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1537 {
1538 raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1539 struct stripe_head *sh;
1540 int sectors_per_chunk = conf->chunk_size >> 9;
1541 sector_t x;
1542 unsigned long stripe;
1543 int chunk_offset;
1544 int dd_idx, pd_idx;
1545 sector_t first_sector;
1546 int raid_disks = conf->raid_disks;
1547 int data_disks = raid_disks-1;
1548 sector_t max_sector = mddev->size << 1;
1549 int sync_blocks;
1550
1551 if (sector_nr >= max_sector) {
1552 /* just being told to finish up .. nothing much to do */
1553 unplug_slaves(mddev);
1554
1555 if (mddev->curr_resync < max_sector) /* aborted */
1556 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1557 &sync_blocks, 1);
1558 else /* compelted sync */
1559 conf->fullsync = 0;
1560 bitmap_close_sync(mddev->bitmap);
1561
1562 return 0;
1563 }
1564 /* if there is 1 or more failed drives and we are trying
1565 * to resync, then assert that we are finished, because there is
1566 * nothing we can do.
1567 */
1568 if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1569 sector_t rv = (mddev->size << 1) - sector_nr;
1570 *skipped = 1;
1571 return rv;
1572 }
1573 if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1574 !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
1575 /* we can skip this block, and probably more */
1576 sync_blocks /= STRIPE_SECTORS;
1577 *skipped = 1;
1578 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
1579 }
1580
1581 x = sector_nr;
1582 chunk_offset = sector_div(x, sectors_per_chunk);
1583 stripe = x;
1584 BUG_ON(x != stripe);
1585
1586 first_sector = raid5_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
1587 + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1588 sh = get_active_stripe(conf, sector_nr, pd_idx, 1);
1589 if (sh == NULL) {
1590 sh = get_active_stripe(conf, sector_nr, pd_idx, 0);
1591 /* make sure we don't swamp the stripe cache if someone else
1592 * is trying to get access
1593 */
1594 set_current_state(TASK_UNINTERRUPTIBLE);
1595 schedule_timeout(1);
1596 }
1597 bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 0);
1598 spin_lock(&sh->lock);
1599 set_bit(STRIPE_SYNCING, &sh->state);
1600 clear_bit(STRIPE_INSYNC, &sh->state);
1601 spin_unlock(&sh->lock);
1602
1603 handle_stripe(sh);
1604 release_stripe(sh);
1605
1606 return STRIPE_SECTORS;
1607 }
1608
1609 /*
1610 * This is our raid5 kernel thread.
1611 *
1612 * We scan the hash table for stripes which can be handled now.
1613 * During the scan, completed stripes are saved for us by the interrupt
1614 * handler, so that they will not have to wait for our next wakeup.
1615 */
1616 static void raid5d (mddev_t *mddev)
1617 {
1618 struct stripe_head *sh;
1619 raid5_conf_t *conf = mddev_to_conf(mddev);
1620 int handled;
1621
1622 PRINTK("+++ raid5d active\n");
1623
1624 md_check_recovery(mddev);
1625
1626 handled = 0;
1627 spin_lock_irq(&conf->device_lock);
1628 while (1) {
1629 struct list_head *first;
1630
1631 if (conf->seq_flush - conf->seq_write > 0) {
1632 int seq = conf->seq_flush;
1633 bitmap_unplug(mddev->bitmap);
1634 conf->seq_write = seq;
1635 activate_bit_delay(conf);
1636 }
1637
1638 if (list_empty(&conf->handle_list) &&
1639 atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
1640 !blk_queue_plugged(mddev->queue) &&
1641 !list_empty(&conf->delayed_list))
1642 raid5_activate_delayed(conf);
1643
1644 if (list_empty(&conf->handle_list))
1645 break;
1646
1647 first = conf->handle_list.next;
1648 sh = list_entry(first, struct stripe_head, lru);
1649
1650 list_del_init(first);
1651 atomic_inc(&sh->count);
1652 if (atomic_read(&sh->count)!= 1)
1653 BUG();
1654 spin_unlock_irq(&conf->device_lock);
1655
1656 handled++;
1657 handle_stripe(sh);
1658 release_stripe(sh);
1659
1660 spin_lock_irq(&conf->device_lock);
1661 }
1662 PRINTK("%d stripes handled\n", handled);
1663
1664 spin_unlock_irq(&conf->device_lock);
1665
1666 unplug_slaves(mddev);
1667
1668 PRINTK("--- raid5d inactive\n");
1669 }
1670
1671 static int run(mddev_t *mddev)
1672 {
1673 raid5_conf_t *conf;
1674 int raid_disk, memory;
1675 mdk_rdev_t *rdev;
1676 struct disk_info *disk;
1677 struct list_head *tmp;
1678
1679 if (mddev->level != 5 && mddev->level != 4) {
1680 printk("raid5: %s: raid level not set to 4/5 (%d)\n", mdname(mddev), mddev->level);
1681 return -EIO;
1682 }
1683
1684 mddev->private = kmalloc (sizeof (raid5_conf_t)
1685 + mddev->raid_disks * sizeof(struct disk_info),
1686 GFP_KERNEL);
1687 if ((conf = mddev->private) == NULL)
1688 goto abort;
1689 memset (conf, 0, sizeof (*conf) + mddev->raid_disks * sizeof(struct disk_info) );
1690 conf->mddev = mddev;
1691
1692 if ((conf->stripe_hashtbl = (struct stripe_head **) __get_free_pages(GFP_ATOMIC, HASH_PAGES_ORDER)) == NULL)
1693 goto abort;
1694 memset(conf->stripe_hashtbl, 0, HASH_PAGES * PAGE_SIZE);
1695
1696 spin_lock_init(&conf->device_lock);
1697 init_waitqueue_head(&conf->wait_for_stripe);
1698 init_waitqueue_head(&conf->wait_for_overlap);
1699 INIT_LIST_HEAD(&conf->handle_list);
1700 INIT_LIST_HEAD(&conf->delayed_list);
1701 INIT_LIST_HEAD(&conf->bitmap_list);
1702 INIT_LIST_HEAD(&conf->inactive_list);
1703 atomic_set(&conf->active_stripes, 0);
1704 atomic_set(&conf->preread_active_stripes, 0);
1705
1706 PRINTK("raid5: run(%s) called.\n", mdname(mddev));
1707
1708 ITERATE_RDEV(mddev,rdev,tmp) {
1709 raid_disk = rdev->raid_disk;
1710 if (raid_disk >= mddev->raid_disks
1711 || raid_disk < 0)
1712 continue;
1713 disk = conf->disks + raid_disk;
1714
1715 disk->rdev = rdev;
1716
1717 if (rdev->in_sync) {
1718 char b[BDEVNAME_SIZE];
1719 printk(KERN_INFO "raid5: device %s operational as raid"
1720 " disk %d\n", bdevname(rdev->bdev,b),
1721 raid_disk);
1722 conf->working_disks++;
1723 }
1724 }
1725
1726 conf->raid_disks = mddev->raid_disks;
1727 /*
1728 * 0 for a fully functional array, 1 for a degraded array.
1729 */
1730 mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
1731 conf->mddev = mddev;
1732 conf->chunk_size = mddev->chunk_size;
1733 conf->level = mddev->level;
1734 conf->algorithm = mddev->layout;
1735 conf->max_nr_stripes = NR_STRIPES;
1736
1737 /* device size must be a multiple of chunk size */
1738 mddev->size &= ~(mddev->chunk_size/1024 -1);
1739 mddev->resync_max_sectors = mddev->size << 1;
1740
1741 if (!conf->chunk_size || conf->chunk_size % 4) {
1742 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
1743 conf->chunk_size, mdname(mddev));
1744 goto abort;
1745 }
1746 if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
1747 printk(KERN_ERR
1748 "raid5: unsupported parity algorithm %d for %s\n",
1749 conf->algorithm, mdname(mddev));
1750 goto abort;
1751 }
1752 if (mddev->degraded > 1) {
1753 printk(KERN_ERR "raid5: not enough operational devices for %s"
1754 " (%d/%d failed)\n",
1755 mdname(mddev), conf->failed_disks, conf->raid_disks);
1756 goto abort;
1757 }
1758
1759 if (mddev->degraded == 1 &&
1760 mddev->recovery_cp != MaxSector) {
1761 printk(KERN_ERR
1762 "raid5: cannot start dirty degraded array for %s\n",
1763 mdname(mddev));
1764 goto abort;
1765 }
1766
1767 {
1768 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
1769 if (!mddev->thread) {
1770 printk(KERN_ERR
1771 "raid5: couldn't allocate thread for %s\n",
1772 mdname(mddev));
1773 goto abort;
1774 }
1775 }
1776 memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
1777 conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
1778 if (grow_stripes(conf, conf->max_nr_stripes)) {
1779 printk(KERN_ERR
1780 "raid5: couldn't allocate %dkB for buffers\n", memory);
1781 shrink_stripes(conf);
1782 md_unregister_thread(mddev->thread);
1783 goto abort;
1784 } else
1785 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
1786 memory, mdname(mddev));
1787
1788 if (mddev->degraded == 0)
1789 printk("raid5: raid level %d set %s active with %d out of %d"
1790 " devices, algorithm %d\n", conf->level, mdname(mddev),
1791 mddev->raid_disks-mddev->degraded, mddev->raid_disks,
1792 conf->algorithm);
1793 else
1794 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
1795 " out of %d devices, algorithm %d\n", conf->level,
1796 mdname(mddev), mddev->raid_disks - mddev->degraded,
1797 mddev->raid_disks, conf->algorithm);
1798
1799 print_raid5_conf(conf);
1800
1801 /* read-ahead size must cover two whole stripes, which is
1802 * 2 * (n-1) * chunksize where 'n' is the number of raid devices
1803 */
1804 {
1805 int stripe = (mddev->raid_disks-1) * mddev->chunk_size
1806 / PAGE_CACHE_SIZE;
1807 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
1808 mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
1809 }
1810
1811 /* Ok, everything is just fine now */
1812
1813 if (mddev->bitmap)
1814 mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
1815
1816 mddev->queue->unplug_fn = raid5_unplug_device;
1817 mddev->queue->issue_flush_fn = raid5_issue_flush;
1818
1819 mddev->array_size = mddev->size * (mddev->raid_disks - 1);
1820 return 0;
1821 abort:
1822 if (conf) {
1823 print_raid5_conf(conf);
1824 if (conf->stripe_hashtbl)
1825 free_pages((unsigned long) conf->stripe_hashtbl,
1826 HASH_PAGES_ORDER);
1827 kfree(conf);
1828 }
1829 mddev->private = NULL;
1830 printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
1831 return -EIO;
1832 }
1833
1834
1835
1836 static int stop (mddev_t *mddev)
1837 {
1838 raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1839
1840 md_unregister_thread(mddev->thread);
1841 mddev->thread = NULL;
1842 shrink_stripes(conf);
1843 free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER);
1844 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
1845 kfree(conf);
1846 mddev->private = NULL;
1847 return 0;
1848 }
1849
1850 #if RAID5_DEBUG
1851 static void print_sh (struct stripe_head *sh)
1852 {
1853 int i;
1854
1855 printk("sh %llu, pd_idx %d, state %ld.\n",
1856 (unsigned long long)sh->sector, sh->pd_idx, sh->state);
1857 printk("sh %llu, count %d.\n",
1858 (unsigned long long)sh->sector, atomic_read(&sh->count));
1859 printk("sh %llu, ", (unsigned long long)sh->sector);
1860 for (i = 0; i < sh->raid_conf->raid_disks; i++) {
1861 printk("(cache%d: %p %ld) ",
1862 i, sh->dev[i].page, sh->dev[i].flags);
1863 }
1864 printk("\n");
1865 }
1866
1867 static void printall (raid5_conf_t *conf)
1868 {
1869 struct stripe_head *sh;
1870 int i;
1871
1872 spin_lock_irq(&conf->device_lock);
1873 for (i = 0; i < NR_HASH; i++) {
1874 sh = conf->stripe_hashtbl[i];
1875 for (; sh; sh = sh->hash_next) {
1876 if (sh->raid_conf != conf)
1877 continue;
1878 print_sh(sh);
1879 }
1880 }
1881 spin_unlock_irq(&conf->device_lock);
1882 }
1883 #endif
1884
1885 static void status (struct seq_file *seq, mddev_t *mddev)
1886 {
1887 raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1888 int i;
1889
1890 seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
1891 seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
1892 for (i = 0; i < conf->raid_disks; i++)
1893 seq_printf (seq, "%s",
1894 conf->disks[i].rdev &&
1895 conf->disks[i].rdev->in_sync ? "U" : "_");
1896 seq_printf (seq, "]");
1897 #if RAID5_DEBUG
1898 #define D(x) \
1899 seq_printf (seq, "<"#x":%d>", atomic_read(&conf->x))
1900 printall(conf);
1901 #endif
1902 }
1903
1904 static void print_raid5_conf (raid5_conf_t *conf)
1905 {
1906 int i;
1907 struct disk_info *tmp;
1908
1909 printk("RAID5 conf printout:\n");
1910 if (!conf) {
1911 printk("(conf==NULL)\n");
1912 return;
1913 }
1914 printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
1915 conf->working_disks, conf->failed_disks);
1916
1917 for (i = 0; i < conf->raid_disks; i++) {
1918 char b[BDEVNAME_SIZE];
1919 tmp = conf->disks + i;
1920 if (tmp->rdev)
1921 printk(" disk %d, o:%d, dev:%s\n",
1922 i, !tmp->rdev->faulty,
1923 bdevname(tmp->rdev->bdev,b));
1924 }
1925 }
1926
1927 static int raid5_spare_active(mddev_t *mddev)
1928 {
1929 int i;
1930 raid5_conf_t *conf = mddev->private;
1931 struct disk_info *tmp;
1932
1933 for (i = 0; i < conf->raid_disks; i++) {
1934 tmp = conf->disks + i;
1935 if (tmp->rdev
1936 && !tmp->rdev->faulty
1937 && !tmp->rdev->in_sync) {
1938 mddev->degraded--;
1939 conf->failed_disks--;
1940 conf->working_disks++;
1941 tmp->rdev->in_sync = 1;
1942 }
1943 }
1944 print_raid5_conf(conf);
1945 return 0;
1946 }
1947
1948 static int raid5_remove_disk(mddev_t *mddev, int number)
1949 {
1950 raid5_conf_t *conf = mddev->private;
1951 int err = 0;
1952 mdk_rdev_t *rdev;
1953 struct disk_info *p = conf->disks + number;
1954
1955 print_raid5_conf(conf);
1956 rdev = p->rdev;
1957 if (rdev) {
1958 if (rdev->in_sync ||
1959 atomic_read(&rdev->nr_pending)) {
1960 err = -EBUSY;
1961 goto abort;
1962 }
1963 p->rdev = NULL;
1964 synchronize_rcu();
1965 if (atomic_read(&rdev->nr_pending)) {
1966 /* lost the race, try later */
1967 err = -EBUSY;
1968 p->rdev = rdev;
1969 }
1970 }
1971 abort:
1972
1973 print_raid5_conf(conf);
1974 return err;
1975 }
1976
1977 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1978 {
1979 raid5_conf_t *conf = mddev->private;
1980 int found = 0;
1981 int disk;
1982 struct disk_info *p;
1983
1984 if (mddev->degraded > 1)
1985 /* no point adding a device */
1986 return 0;
1987
1988 /*
1989 * find the disk ...
1990 */
1991 for (disk=0; disk < mddev->raid_disks; disk++)
1992 if ((p=conf->disks + disk)->rdev == NULL) {
1993 rdev->in_sync = 0;
1994 rdev->raid_disk = disk;
1995 found = 1;
1996 if (rdev->saved_raid_disk != disk)
1997 conf->fullsync = 1;
1998 p->rdev = rdev;
1999 break;
2000 }
2001 print_raid5_conf(conf);
2002 return found;
2003 }
2004
2005 static int raid5_resize(mddev_t *mddev, sector_t sectors)
2006 {
2007 /* no resync is happening, and there is enough space
2008 * on all devices, so we can resize.
2009 * We need to make sure resync covers any new space.
2010 * If the array is shrinking we should possibly wait until
2011 * any io in the removed space completes, but it hardly seems
2012 * worth it.
2013 */
2014 sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
2015 mddev->array_size = (sectors * (mddev->raid_disks-1))>>1;
2016 set_capacity(mddev->gendisk, mddev->array_size << 1);
2017 mddev->changed = 1;
2018 if (sectors/2 > mddev->size && mddev->recovery_cp == MaxSector) {
2019 mddev->recovery_cp = mddev->size << 1;
2020 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2021 }
2022 mddev->size = sectors /2;
2023 mddev->resync_max_sectors = sectors;
2024 return 0;
2025 }
2026
2027 static void raid5_quiesce(mddev_t *mddev, int state)
2028 {
2029 raid5_conf_t *conf = mddev_to_conf(mddev);
2030
2031 switch(state) {
2032 case 1: /* stop all writes */
2033 spin_lock_irq(&conf->device_lock);
2034 conf->quiesce = 1;
2035 wait_event_lock_irq(conf->wait_for_stripe,
2036 atomic_read(&conf->active_stripes) == 0,
2037 conf->device_lock, /* nothing */);
2038 spin_unlock_irq(&conf->device_lock);
2039 break;
2040
2041 case 0: /* re-enable writes */
2042 spin_lock_irq(&conf->device_lock);
2043 conf->quiesce = 0;
2044 wake_up(&conf->wait_for_stripe);
2045 spin_unlock_irq(&conf->device_lock);
2046 break;
2047 }
2048 if (mddev->thread) {
2049 if (mddev->bitmap)
2050 mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
2051 else
2052 mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
2053 md_wakeup_thread(mddev->thread);
2054 }
2055 }
2056 static mdk_personality_t raid5_personality=
2057 {
2058 .name = "raid5",
2059 .owner = THIS_MODULE,
2060 .make_request = make_request,
2061 .run = run,
2062 .stop = stop,
2063 .status = status,
2064 .error_handler = error,
2065 .hot_add_disk = raid5_add_disk,
2066 .hot_remove_disk= raid5_remove_disk,
2067 .spare_active = raid5_spare_active,
2068 .sync_request = sync_request,
2069 .resize = raid5_resize,
2070 .quiesce = raid5_quiesce,
2071 };
2072
2073 static int __init raid5_init (void)
2074 {
2075 return register_md_personality (RAID5, &raid5_personality);
2076 }
2077
2078 static void raid5_exit (void)
2079 {
2080 unregister_md_personality (RAID5);
2081 }
2082
2083 module_init(raid5_init);
2084 module_exit(raid5_exit);
2085 MODULE_LICENSE("GPL");
2086 MODULE_ALIAS("md-personality-4"); /* RAID5 */
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