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[PATCH] dm: fix mapped device ref counting
[linux-2.6/verdex.git] / drivers / md / raid6main.c
blobbc69355e0100ece2f803bd17bc6b6c44cf2bd074
1 /*
2 * raid6main.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 * Copyright (C) 2002, 2003 H. Peter Anvin
6 *
7 * RAID-6 management functions. This code is derived from raid5.c.
8 * Last merge from raid5.c bkcvs version 1.79 (kernel 2.6.1).
9 *
10 * Thanks to Penguin Computing for making the RAID-6 development possible
11 * by donating a test server!
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2, or (at your option)
16 * any later version.
17 *
18 * You should have received a copy of the GNU General Public License
19 * (for example /usr/src/linux/COPYING); if not, write to the Free
20 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23
24 #include <linux/config.h>
25 #include <linux/module.h>
26 #include <linux/slab.h>
27 #include <linux/highmem.h>
28 #include <linux/bitops.h>
29 #include <asm/atomic.h>
30 #include "raid6.h"
31
32 #include <linux/raid/bitmap.h>
33
34 /*
35 * Stripe cache
36 */
37
38 #define NR_STRIPES 256
39 #define STRIPE_SIZE PAGE_SIZE
40 #define STRIPE_SHIFT (PAGE_SHIFT - 9)
41 #define STRIPE_SECTORS (STRIPE_SIZE>>9)
42 #define IO_THRESHOLD 1
43 #define NR_HASH (PAGE_SIZE / sizeof(struct hlist_head))
44 #define HASH_MASK (NR_HASH - 1)
45
46 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
47
48 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
49 * order without overlap. There may be several bio's per stripe+device, and
50 * a bio could span several devices.
51 * When walking this list for a particular stripe+device, we must never proceed
52 * beyond a bio that extends past this device, as the next bio might no longer
53 * be valid.
54 * This macro is used to determine the 'next' bio in the list, given the sector
55 * of the current stripe+device
56 */
57 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
58 /*
59 * The following can be used to debug the driver
60 */
61 #define RAID6_DEBUG 0 /* Extremely verbose printk */
62 #define RAID6_PARANOIA 1 /* Check spinlocks */
63 #define RAID6_DUMPSTATE 0 /* Include stripe cache state in /proc/mdstat */
64 #if RAID6_PARANOIA && defined(CONFIG_SMP)
65 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
66 #else
67 # define CHECK_DEVLOCK()
68 #endif
69
70 #define PRINTK(x...) ((void)(RAID6_DEBUG && printk(KERN_DEBUG x)))
71 #if RAID6_DEBUG
72 #undef inline
73 #undef __inline__
74 #define inline
75 #define __inline__
76 #endif
77
78 #if !RAID6_USE_EMPTY_ZERO_PAGE
79 /* In .bss so it's zeroed */
80 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
81 #endif
82
83 static inline int raid6_next_disk(int disk, int raid_disks)
84 {
85 disk++;
86 return (disk < raid_disks) ? disk : 0;
87 }
88
89 static void print_raid6_conf (raid6_conf_t *conf);
90
91 static void __release_stripe(raid6_conf_t *conf, struct stripe_head *sh)
92 {
93 if (atomic_dec_and_test(&sh->count)) {
94 BUG_ON(!list_empty(&sh->lru));
95 BUG_ON(atomic_read(&conf->active_stripes)==0);
96 if (test_bit(STRIPE_HANDLE, &sh->state)) {
97 if (test_bit(STRIPE_DELAYED, &sh->state))
98 list_add_tail(&sh->lru, &conf->delayed_list);
99 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
100 conf->seq_write == sh->bm_seq)
101 list_add_tail(&sh->lru, &conf->bitmap_list);
102 else {
103 clear_bit(STRIPE_BIT_DELAY, &sh->state);
104 list_add_tail(&sh->lru, &conf->handle_list);
105 }
106 md_wakeup_thread(conf->mddev->thread);
107 } else {
108 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
109 atomic_dec(&conf->preread_active_stripes);
110 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
111 md_wakeup_thread(conf->mddev->thread);
112 }
113 list_add_tail(&sh->lru, &conf->inactive_list);
114 atomic_dec(&conf->active_stripes);
115 if (!conf->inactive_blocked ||
116 atomic_read(&conf->active_stripes) < (conf->max_nr_stripes*3/4))
117 wake_up(&conf->wait_for_stripe);
118 }
119 }
120 }
121 static void release_stripe(struct stripe_head *sh)
122 {
123 raid6_conf_t *conf = sh->raid_conf;
124 unsigned long flags;
125
126 spin_lock_irqsave(&conf->device_lock, flags);
127 __release_stripe(conf, sh);
128 spin_unlock_irqrestore(&conf->device_lock, flags);
129 }
130
131 static inline void remove_hash(struct stripe_head *sh)
132 {
133 PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
134
135 hlist_del_init(&sh->hash);
136 }
137
138 static inline void insert_hash(raid6_conf_t *conf, struct stripe_head *sh)
139 {
140 struct hlist_head *hp = stripe_hash(conf, sh->sector);
141
142 PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
143
144 CHECK_DEVLOCK();
145 hlist_add_head(&sh->hash, hp);
146 }
147
148
149 /* find an idle stripe, make sure it is unhashed, and return it. */
150 static struct stripe_head *get_free_stripe(raid6_conf_t *conf)
151 {
152 struct stripe_head *sh = NULL;
153 struct list_head *first;
154
155 CHECK_DEVLOCK();
156 if (list_empty(&conf->inactive_list))
157 goto out;
158 first = conf->inactive_list.next;
159 sh = list_entry(first, struct stripe_head, lru);
160 list_del_init(first);
161 remove_hash(sh);
162 atomic_inc(&conf->active_stripes);
163 out:
164 return sh;
165 }
166
167 static void shrink_buffers(struct stripe_head *sh, int num)
168 {
169 struct page *p;
170 int i;
171
172 for (i=0; i<num ; i++) {
173 p = sh->dev[i].page;
174 if (!p)
175 continue;
176 sh->dev[i].page = NULL;
177 put_page(p);
178 }
179 }
180
181 static int grow_buffers(struct stripe_head *sh, int num)
182 {
183 int i;
184
185 for (i=0; i<num; i++) {
186 struct page *page;
187
188 if (!(page = alloc_page(GFP_KERNEL))) {
189 return 1;
190 }
191 sh->dev[i].page = page;
192 }
193 return 0;
194 }
195
196 static void raid6_build_block (struct stripe_head *sh, int i);
197
198 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
199 {
200 raid6_conf_t *conf = sh->raid_conf;
201 int disks = conf->raid_disks, i;
202
203 BUG_ON(atomic_read(&sh->count) != 0);
204 BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
205
206 CHECK_DEVLOCK();
207 PRINTK("init_stripe called, stripe %llu\n",
208 (unsigned long long)sh->sector);
209
210 remove_hash(sh);
211
212 sh->sector = sector;
213 sh->pd_idx = pd_idx;
214 sh->state = 0;
215
216 for (i=disks; i--; ) {
217 struct r5dev *dev = &sh->dev[i];
218
219 if (dev->toread || dev->towrite || dev->written ||
220 test_bit(R5_LOCKED, &dev->flags)) {
221 PRINTK("sector=%llx i=%d %p %p %p %d\n",
222 (unsigned long long)sh->sector, i, dev->toread,
223 dev->towrite, dev->written,
224 test_bit(R5_LOCKED, &dev->flags));
225 BUG();
226 }
227 dev->flags = 0;
228 raid6_build_block(sh, i);
229 }
230 insert_hash(conf, sh);
231 }
232
233 static struct stripe_head *__find_stripe(raid6_conf_t *conf, sector_t sector)
234 {
235 struct stripe_head *sh;
236 struct hlist_node *hn;
237
238 CHECK_DEVLOCK();
239 PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
240 hlist_for_each_entry (sh, hn, stripe_hash(conf, sector), hash)
241 if (sh->sector == sector)
242 return sh;
243 PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
244 return NULL;
245 }
246
247 static void unplug_slaves(mddev_t *mddev);
248
249 static struct stripe_head *get_active_stripe(raid6_conf_t *conf, sector_t sector,
250 int pd_idx, int noblock)
251 {
252 struct stripe_head *sh;
253
254 PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
255
256 spin_lock_irq(&conf->device_lock);
257
258 do {
259 wait_event_lock_irq(conf->wait_for_stripe,
260 conf->quiesce == 0,
261 conf->device_lock, /* nothing */);
262 sh = __find_stripe(conf, sector);
263 if (!sh) {
264 if (!conf->inactive_blocked)
265 sh = get_free_stripe(conf);
266 if (noblock && sh == NULL)
267 break;
268 if (!sh) {
269 conf->inactive_blocked = 1;
270 wait_event_lock_irq(conf->wait_for_stripe,
271 !list_empty(&conf->inactive_list) &&
272 (atomic_read(&conf->active_stripes)
273 < (conf->max_nr_stripes *3/4)
274 || !conf->inactive_blocked),
275 conf->device_lock,
276 unplug_slaves(conf->mddev);
277 );
278 conf->inactive_blocked = 0;
279 } else
280 init_stripe(sh, sector, pd_idx);
281 } else {
282 if (atomic_read(&sh->count)) {
283 BUG_ON(!list_empty(&sh->lru));
284 } else {
285 if (!test_bit(STRIPE_HANDLE, &sh->state))
286 atomic_inc(&conf->active_stripes);
287 BUG_ON(list_empty(&sh->lru));
288 list_del_init(&sh->lru);
289 }
290 }
291 } while (sh == NULL);
292
293 if (sh)
294 atomic_inc(&sh->count);
295
296 spin_unlock_irq(&conf->device_lock);
297 return sh;
298 }
299
300 static int grow_one_stripe(raid6_conf_t *conf)
301 {
302 struct stripe_head *sh;
303 sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
304 if (!sh)
305 return 0;
306 memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
307 sh->raid_conf = conf;
308 spin_lock_init(&sh->lock);
309
310 if (grow_buffers(sh, conf->raid_disks)) {
311 shrink_buffers(sh, conf->raid_disks);
312 kmem_cache_free(conf->slab_cache, sh);
313 return 0;
314 }
315 /* we just created an active stripe so... */
316 atomic_set(&sh->count, 1);
317 atomic_inc(&conf->active_stripes);
318 INIT_LIST_HEAD(&sh->lru);
319 release_stripe(sh);
320 return 1;
321 }
322
323 static int grow_stripes(raid6_conf_t *conf, int num)
324 {
325 kmem_cache_t *sc;
326 int devs = conf->raid_disks;
327
328 sprintf(conf->cache_name[0], "raid6/%s", mdname(conf->mddev));
329
330 sc = kmem_cache_create(conf->cache_name[0],
331 sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
332 0, 0, NULL, NULL);
333 if (!sc)
334 return 1;
335 conf->slab_cache = sc;
336 while (num--)
337 if (!grow_one_stripe(conf))
338 return 1;
339 return 0;
340 }
341
342 static int drop_one_stripe(raid6_conf_t *conf)
343 {
344 struct stripe_head *sh;
345 spin_lock_irq(&conf->device_lock);
346 sh = get_free_stripe(conf);
347 spin_unlock_irq(&conf->device_lock);
348 if (!sh)
349 return 0;
350 BUG_ON(atomic_read(&sh->count));
351 shrink_buffers(sh, conf->raid_disks);
352 kmem_cache_free(conf->slab_cache, sh);
353 atomic_dec(&conf->active_stripes);
354 return 1;
355 }
356
357 static void shrink_stripes(raid6_conf_t *conf)
358 {
359 while (drop_one_stripe(conf))
360 ;
361
362 if (conf->slab_cache)
363 kmem_cache_destroy(conf->slab_cache);
364 conf->slab_cache = NULL;
365 }
366
367 static int raid6_end_read_request(struct bio * bi, unsigned int bytes_done,
368 int error)
369 {
370 struct stripe_head *sh = bi->bi_private;
371 raid6_conf_t *conf = sh->raid_conf;
372 int disks = conf->raid_disks, i;
373 int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
374
375 if (bi->bi_size)
376 return 1;
377
378 for (i=0 ; i<disks; i++)
379 if (bi == &sh->dev[i].req)
380 break;
381
382 PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
383 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
384 uptodate);
385 if (i == disks) {
386 BUG();
387 return 0;
388 }
389
390 if (uptodate) {
391 #if 0
392 struct bio *bio;
393 unsigned long flags;
394 spin_lock_irqsave(&conf->device_lock, flags);
395 /* we can return a buffer if we bypassed the cache or
396 * if the top buffer is not in highmem. If there are
397 * multiple buffers, leave the extra work to
398 * handle_stripe
399 */
400 buffer = sh->bh_read[i];
401 if (buffer &&
402 (!PageHighMem(buffer->b_page)
403 || buffer->b_page == bh->b_page )
404 ) {
405 sh->bh_read[i] = buffer->b_reqnext;
406 buffer->b_reqnext = NULL;
407 } else
408 buffer = NULL;
409 spin_unlock_irqrestore(&conf->device_lock, flags);
410 if (sh->bh_page[i]==bh->b_page)
411 set_buffer_uptodate(bh);
412 if (buffer) {
413 if (buffer->b_page != bh->b_page)
414 memcpy(buffer->b_data, bh->b_data, bh->b_size);
415 buffer->b_end_io(buffer, 1);
416 }
417 #else
418 set_bit(R5_UPTODATE, &sh->dev[i].flags);
419 #endif
420 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
421 printk(KERN_INFO "raid6: read error corrected!!\n");
422 clear_bit(R5_ReadError, &sh->dev[i].flags);
423 clear_bit(R5_ReWrite, &sh->dev[i].flags);
424 }
425 if (atomic_read(&conf->disks[i].rdev->read_errors))
426 atomic_set(&conf->disks[i].rdev->read_errors, 0);
427 } else {
428 int retry = 0;
429 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
430 atomic_inc(&conf->disks[i].rdev->read_errors);
431 if (conf->mddev->degraded)
432 printk(KERN_WARNING "raid6: read error not correctable.\n");
433 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
434 /* Oh, no!!! */
435 printk(KERN_WARNING "raid6: read error NOT corrected!!\n");
436 else if (atomic_read(&conf->disks[i].rdev->read_errors)
437 > conf->max_nr_stripes)
438 printk(KERN_WARNING
439 "raid6: Too many read errors, failing device.\n");
440 else
441 retry = 1;
442 if (retry)
443 set_bit(R5_ReadError, &sh->dev[i].flags);
444 else {
445 clear_bit(R5_ReadError, &sh->dev[i].flags);
446 clear_bit(R5_ReWrite, &sh->dev[i].flags);
447 md_error(conf->mddev, conf->disks[i].rdev);
448 }
449 }
450 rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
451 #if 0
452 /* must restore b_page before unlocking buffer... */
453 if (sh->bh_page[i] != bh->b_page) {
454 bh->b_page = sh->bh_page[i];
455 bh->b_data = page_address(bh->b_page);
456 clear_buffer_uptodate(bh);
457 }
458 #endif
459 clear_bit(R5_LOCKED, &sh->dev[i].flags);
460 set_bit(STRIPE_HANDLE, &sh->state);
461 release_stripe(sh);
462 return 0;
463 }
464
465 static int raid6_end_write_request (struct bio *bi, unsigned int bytes_done,
466 int error)
467 {
468 struct stripe_head *sh = bi->bi_private;
469 raid6_conf_t *conf = sh->raid_conf;
470 int disks = conf->raid_disks, i;
471 unsigned long flags;
472 int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
473
474 if (bi->bi_size)
475 return 1;
476
477 for (i=0 ; i<disks; i++)
478 if (bi == &sh->dev[i].req)
479 break;
480
481 PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
482 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
483 uptodate);
484 if (i == disks) {
485 BUG();
486 return 0;
487 }
488
489 spin_lock_irqsave(&conf->device_lock, flags);
490 if (!uptodate)
491 md_error(conf->mddev, conf->disks[i].rdev);
492
493 rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
494
495 clear_bit(R5_LOCKED, &sh->dev[i].flags);
496 set_bit(STRIPE_HANDLE, &sh->state);
497 __release_stripe(conf, sh);
498 spin_unlock_irqrestore(&conf->device_lock, flags);
499 return 0;
500 }
501
502
503 static sector_t compute_blocknr(struct stripe_head *sh, int i);
504
505 static void raid6_build_block (struct stripe_head *sh, int i)
506 {
507 struct r5dev *dev = &sh->dev[i];
508 int pd_idx = sh->pd_idx;
509 int qd_idx = raid6_next_disk(pd_idx, sh->raid_conf->raid_disks);
510
511 bio_init(&dev->req);
512 dev->req.bi_io_vec = &dev->vec;
513 dev->req.bi_vcnt++;
514 dev->req.bi_max_vecs++;
515 dev->vec.bv_page = dev->page;
516 dev->vec.bv_len = STRIPE_SIZE;
517 dev->vec.bv_offset = 0;
518
519 dev->req.bi_sector = sh->sector;
520 dev->req.bi_private = sh;
521
522 dev->flags = 0;
523 if (i != pd_idx && i != qd_idx)
524 dev->sector = compute_blocknr(sh, i);
525 }
526
527 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
528 {
529 char b[BDEVNAME_SIZE];
530 raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
531 PRINTK("raid6: error called\n");
532
533 if (!test_bit(Faulty, &rdev->flags)) {
534 mddev->sb_dirty = 1;
535 if (test_bit(In_sync, &rdev->flags)) {
536 conf->working_disks--;
537 mddev->degraded++;
538 conf->failed_disks++;
539 clear_bit(In_sync, &rdev->flags);
540 /*
541 * if recovery was running, make sure it aborts.
542 */
543 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
544 }
545 set_bit(Faulty, &rdev->flags);
546 printk (KERN_ALERT
547 "raid6: Disk failure on %s, disabling device."
548 " Operation continuing on %d devices\n",
549 bdevname(rdev->bdev,b), conf->working_disks);
550 }
551 }
552
553 /*
554 * Input: a 'big' sector number,
555 * Output: index of the data and parity disk, and the sector # in them.
556 */
557 static sector_t raid6_compute_sector(sector_t r_sector, unsigned int raid_disks,
558 unsigned int data_disks, unsigned int * dd_idx,
559 unsigned int * pd_idx, raid6_conf_t *conf)
560 {
561 long stripe;
562 unsigned long chunk_number;
563 unsigned int chunk_offset;
564 sector_t new_sector;
565 int sectors_per_chunk = conf->chunk_size >> 9;
566
567 /* First compute the information on this sector */
568
569 /*
570 * Compute the chunk number and the sector offset inside the chunk
571 */
572 chunk_offset = sector_div(r_sector, sectors_per_chunk);
573 chunk_number = r_sector;
574 if ( r_sector != chunk_number ) {
575 printk(KERN_CRIT "raid6: ERROR: r_sector = %llu, chunk_number = %lu\n",
576 (unsigned long long)r_sector, (unsigned long)chunk_number);
577 BUG();
578 }
579
580 /*
581 * Compute the stripe number
582 */
583 stripe = chunk_number / data_disks;
584
585 /*
586 * Compute the data disk and parity disk indexes inside the stripe
587 */
588 *dd_idx = chunk_number % data_disks;
589
590 /*
591 * Select the parity disk based on the user selected algorithm.
592 */
593
594 /**** FIX THIS ****/
595 switch (conf->algorithm) {
596 case ALGORITHM_LEFT_ASYMMETRIC:
597 *pd_idx = raid_disks - 1 - (stripe % raid_disks);
598 if (*pd_idx == raid_disks-1)
599 (*dd_idx)++; /* Q D D D P */
600 else if (*dd_idx >= *pd_idx)
601 (*dd_idx) += 2; /* D D P Q D */
602 break;
603 case ALGORITHM_RIGHT_ASYMMETRIC:
604 *pd_idx = stripe % raid_disks;
605 if (*pd_idx == raid_disks-1)
606 (*dd_idx)++; /* Q D D D P */
607 else if (*dd_idx >= *pd_idx)
608 (*dd_idx) += 2; /* D D P Q D */
609 break;
610 case ALGORITHM_LEFT_SYMMETRIC:
611 *pd_idx = raid_disks - 1 - (stripe % raid_disks);
612 *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
613 break;
614 case ALGORITHM_RIGHT_SYMMETRIC:
615 *pd_idx = stripe % raid_disks;
616 *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
617 break;
618 default:
619 printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
620 conf->algorithm);
621 }
622
623 PRINTK("raid6: chunk_number = %lu, pd_idx = %u, dd_idx = %u\n",
624 chunk_number, *pd_idx, *dd_idx);
625
626 /*
627 * Finally, compute the new sector number
628 */
629 new_sector = (sector_t) stripe * sectors_per_chunk + chunk_offset;
630 return new_sector;
631 }
632
633
634 static sector_t compute_blocknr(struct stripe_head *sh, int i)
635 {
636 raid6_conf_t *conf = sh->raid_conf;
637 int raid_disks = conf->raid_disks, data_disks = raid_disks - 2;
638 sector_t new_sector = sh->sector, check;
639 int sectors_per_chunk = conf->chunk_size >> 9;
640 sector_t stripe;
641 int chunk_offset;
642 int chunk_number, dummy1, dummy2, dd_idx = i;
643 sector_t r_sector;
644 int i0 = i;
645
646 chunk_offset = sector_div(new_sector, sectors_per_chunk);
647 stripe = new_sector;
648 if ( new_sector != stripe ) {
649 printk(KERN_CRIT "raid6: ERROR: new_sector = %llu, stripe = %lu\n",
650 (unsigned long long)new_sector, (unsigned long)stripe);
651 BUG();
652 }
653
654 switch (conf->algorithm) {
655 case ALGORITHM_LEFT_ASYMMETRIC:
656 case ALGORITHM_RIGHT_ASYMMETRIC:
657 if (sh->pd_idx == raid_disks-1)
658 i--; /* Q D D D P */
659 else if (i > sh->pd_idx)
660 i -= 2; /* D D P Q D */
661 break;
662 case ALGORITHM_LEFT_SYMMETRIC:
663 case ALGORITHM_RIGHT_SYMMETRIC:
664 if (sh->pd_idx == raid_disks-1)
665 i--; /* Q D D D P */
666 else {
667 /* D D P Q D */
668 if (i < sh->pd_idx)
669 i += raid_disks;
670 i -= (sh->pd_idx + 2);
671 }
672 break;
673 default:
674 printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
675 conf->algorithm);
676 }
677
678 PRINTK("raid6: compute_blocknr: pd_idx = %u, i0 = %u, i = %u\n", sh->pd_idx, i0, i);
679
680 chunk_number = stripe * data_disks + i;
681 r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
682
683 check = raid6_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
684 if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
685 printk(KERN_CRIT "raid6: compute_blocknr: map not correct\n");
686 return 0;
687 }
688 return r_sector;
689 }
690
691
692
693 /*
694 * Copy data between a page in the stripe cache, and one or more bion
695 * The page could align with the middle of the bio, or there could be
696 * several bion, each with several bio_vecs, which cover part of the page
697 * Multiple bion are linked together on bi_next. There may be extras
698 * at the end of this list. We ignore them.
699 */
700 static void copy_data(int frombio, struct bio *bio,
701 struct page *page,
702 sector_t sector)
703 {
704 char *pa = page_address(page);
705 struct bio_vec *bvl;
706 int i;
707 int page_offset;
708
709 if (bio->bi_sector >= sector)
710 page_offset = (signed)(bio->bi_sector - sector) * 512;
711 else
712 page_offset = (signed)(sector - bio->bi_sector) * -512;
713 bio_for_each_segment(bvl, bio, i) {
714 int len = bio_iovec_idx(bio,i)->bv_len;
715 int clen;
716 int b_offset = 0;
717
718 if (page_offset < 0) {
719 b_offset = -page_offset;
720 page_offset += b_offset;
721 len -= b_offset;
722 }
723
724 if (len > 0 && page_offset + len > STRIPE_SIZE)
725 clen = STRIPE_SIZE - page_offset;
726 else clen = len;
727
728 if (clen > 0) {
729 char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
730 if (frombio)
731 memcpy(pa+page_offset, ba+b_offset, clen);
732 else
733 memcpy(ba+b_offset, pa+page_offset, clen);
734 __bio_kunmap_atomic(ba, KM_USER0);
735 }
736 if (clen < len) /* hit end of page */
737 break;
738 page_offset += len;
739 }
740 }
741
742 #define check_xor() do { \
743 if (count == MAX_XOR_BLOCKS) { \
744 xor_block(count, STRIPE_SIZE, ptr); \
745 count = 1; \
746 } \
747 } while(0)
748
749 /* Compute P and Q syndromes */
750 static void compute_parity(struct stripe_head *sh, int method)
751 {
752 raid6_conf_t *conf = sh->raid_conf;
753 int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = conf->raid_disks, count;
754 struct bio *chosen;
755 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
756 void *ptrs[disks];
757
758 qd_idx = raid6_next_disk(pd_idx, disks);
759 d0_idx = raid6_next_disk(qd_idx, disks);
760
761 PRINTK("compute_parity, stripe %llu, method %d\n",
762 (unsigned long long)sh->sector, method);
763
764 switch(method) {
765 case READ_MODIFY_WRITE:
766 BUG(); /* READ_MODIFY_WRITE N/A for RAID-6 */
767 case RECONSTRUCT_WRITE:
768 for (i= disks; i-- ;)
769 if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
770 chosen = sh->dev[i].towrite;
771 sh->dev[i].towrite = NULL;
772
773 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
774 wake_up(&conf->wait_for_overlap);
775
776 BUG_ON(sh->dev[i].written);
777 sh->dev[i].written = chosen;
778 }
779 break;
780 case CHECK_PARITY:
781 BUG(); /* Not implemented yet */
782 }
783
784 for (i = disks; i--;)
785 if (sh->dev[i].written) {
786 sector_t sector = sh->dev[i].sector;
787 struct bio *wbi = sh->dev[i].written;
788 while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
789 copy_data(1, wbi, sh->dev[i].page, sector);
790 wbi = r5_next_bio(wbi, sector);
791 }
792
793 set_bit(R5_LOCKED, &sh->dev[i].flags);
794 set_bit(R5_UPTODATE, &sh->dev[i].flags);
795 }
796
797 // switch(method) {
798 // case RECONSTRUCT_WRITE:
799 // case CHECK_PARITY:
800 // case UPDATE_PARITY:
801 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
802 /* FIX: Is this ordering of drives even remotely optimal? */
803 count = 0;
804 i = d0_idx;
805 do {
806 ptrs[count++] = page_address(sh->dev[i].page);
807 if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
808 printk("block %d/%d not uptodate on parity calc\n", i,count);
809 i = raid6_next_disk(i, disks);
810 } while ( i != d0_idx );
811 // break;
812 // }
813
814 raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
815
816 switch(method) {
817 case RECONSTRUCT_WRITE:
818 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
819 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
820 set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
821 set_bit(R5_LOCKED, &sh->dev[qd_idx].flags);
822 break;
823 case UPDATE_PARITY:
824 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
825 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
826 break;
827 }
828 }
829
830 /* Compute one missing block */
831 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
832 {
833 raid6_conf_t *conf = sh->raid_conf;
834 int i, count, disks = conf->raid_disks;
835 void *ptr[MAX_XOR_BLOCKS], *p;
836 int pd_idx = sh->pd_idx;
837 int qd_idx = raid6_next_disk(pd_idx, disks);
838
839 PRINTK("compute_block_1, stripe %llu, idx %d\n",
840 (unsigned long long)sh->sector, dd_idx);
841
842 if ( dd_idx == qd_idx ) {
843 /* We're actually computing the Q drive */
844 compute_parity(sh, UPDATE_PARITY);
845 } else {
846 ptr[0] = page_address(sh->dev[dd_idx].page);
847 if (!nozero) memset(ptr[0], 0, STRIPE_SIZE);
848 count = 1;
849 for (i = disks ; i--; ) {
850 if (i == dd_idx || i == qd_idx)
851 continue;
852 p = page_address(sh->dev[i].page);
853 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
854 ptr[count++] = p;
855 else
856 printk("compute_block() %d, stripe %llu, %d"
857 " not present\n", dd_idx,
858 (unsigned long long)sh->sector, i);
859
860 check_xor();
861 }
862 if (count != 1)
863 xor_block(count, STRIPE_SIZE, ptr);
864 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
865 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
866 }
867 }
868
869 /* Compute two missing blocks */
870 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
871 {
872 raid6_conf_t *conf = sh->raid_conf;
873 int i, count, disks = conf->raid_disks;
874 int pd_idx = sh->pd_idx;
875 int qd_idx = raid6_next_disk(pd_idx, disks);
876 int d0_idx = raid6_next_disk(qd_idx, disks);
877 int faila, failb;
878
879 /* faila and failb are disk numbers relative to d0_idx */
880 /* pd_idx become disks-2 and qd_idx become disks-1 */
881 faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
882 failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
883
884 BUG_ON(faila == failb);
885 if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
886
887 PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
888 (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
889
890 if ( failb == disks-1 ) {
891 /* Q disk is one of the missing disks */
892 if ( faila == disks-2 ) {
893 /* Missing P+Q, just recompute */
894 compute_parity(sh, UPDATE_PARITY);
895 return;
896 } else {
897 /* We're missing D+Q; recompute D from P */
898 compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
899 compute_parity(sh, UPDATE_PARITY); /* Is this necessary? */
900 return;
901 }
902 }
903
904 /* We're missing D+P or D+D; build pointer table */
905 {
906 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
907 void *ptrs[disks];
908
909 count = 0;
910 i = d0_idx;
911 do {
912 ptrs[count++] = page_address(sh->dev[i].page);
913 i = raid6_next_disk(i, disks);
914 if (i != dd_idx1 && i != dd_idx2 &&
915 !test_bit(R5_UPTODATE, &sh->dev[i].flags))
916 printk("compute_2 with missing block %d/%d\n", count, i);
917 } while ( i != d0_idx );
918
919 if ( failb == disks-2 ) {
920 /* We're missing D+P. */
921 raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
922 } else {
923 /* We're missing D+D. */
924 raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
925 }
926
927 /* Both the above update both missing blocks */
928 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
929 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
930 }
931 }
932
933
934 /*
935 * Each stripe/dev can have one or more bion attached.
936 * toread/towrite point to the first in a chain.
937 * The bi_next chain must be in order.
938 */
939 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
940 {
941 struct bio **bip;
942 raid6_conf_t *conf = sh->raid_conf;
943 int firstwrite=0;
944
945 PRINTK("adding bh b#%llu to stripe s#%llu\n",
946 (unsigned long long)bi->bi_sector,
947 (unsigned long long)sh->sector);
948
949
950 spin_lock(&sh->lock);
951 spin_lock_irq(&conf->device_lock);
952 if (forwrite) {
953 bip = &sh->dev[dd_idx].towrite;
954 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
955 firstwrite = 1;
956 } else
957 bip = &sh->dev[dd_idx].toread;
958 while (*bip && (*bip)->bi_sector < bi->bi_sector) {
959 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
960 goto overlap;
961 bip = &(*bip)->bi_next;
962 }
963 if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
964 goto overlap;
965
966 BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
967 if (*bip)
968 bi->bi_next = *bip;
969 *bip = bi;
970 bi->bi_phys_segments ++;
971 spin_unlock_irq(&conf->device_lock);
972 spin_unlock(&sh->lock);
973
974 PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
975 (unsigned long long)bi->bi_sector,
976 (unsigned long long)sh->sector, dd_idx);
977
978 if (conf->mddev->bitmap && firstwrite) {
979 sh->bm_seq = conf->seq_write;
980 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
981 STRIPE_SECTORS, 0);
982 set_bit(STRIPE_BIT_DELAY, &sh->state);
983 }
984
985 if (forwrite) {
986 /* check if page is covered */
987 sector_t sector = sh->dev[dd_idx].sector;
988 for (bi=sh->dev[dd_idx].towrite;
989 sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
990 bi && bi->bi_sector <= sector;
991 bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
992 if (bi->bi_sector + (bi->bi_size>>9) >= sector)
993 sector = bi->bi_sector + (bi->bi_size>>9);
994 }
995 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
996 set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
997 }
998 return 1;
999
1000 overlap:
1001 set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1002 spin_unlock_irq(&conf->device_lock);
1003 spin_unlock(&sh->lock);
1004 return 0;
1005 }
1006
1007
1008 static int page_is_zero(struct page *p)
1009 {
1010 char *a = page_address(p);
1011 return ((*(u32*)a) == 0 &&
1012 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1013 }
1014 /*
1015 * handle_stripe - do things to a stripe.
1016 *
1017 * We lock the stripe and then examine the state of various bits
1018 * to see what needs to be done.
1019 * Possible results:
1020 * return some read request which now have data
1021 * return some write requests which are safely on disc
1022 * schedule a read on some buffers
1023 * schedule a write of some buffers
1024 * return confirmation of parity correctness
1025 *
1026 * Parity calculations are done inside the stripe lock
1027 * buffers are taken off read_list or write_list, and bh_cache buffers
1028 * get BH_Lock set before the stripe lock is released.
1029 *
1030 */
1031
1032 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
1033 {
1034 raid6_conf_t *conf = sh->raid_conf;
1035 int disks = conf->raid_disks;
1036 struct bio *return_bi= NULL;
1037 struct bio *bi;
1038 int i;
1039 int syncing;
1040 int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
1041 int non_overwrite = 0;
1042 int failed_num[2] = {0, 0};
1043 struct r5dev *dev, *pdev, *qdev;
1044 int pd_idx = sh->pd_idx;
1045 int qd_idx = raid6_next_disk(pd_idx, disks);
1046 int p_failed, q_failed;
1047
1048 PRINTK("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d, qd_idx=%d\n",
1049 (unsigned long long)sh->sector, sh->state, atomic_read(&sh->count),
1050 pd_idx, qd_idx);
1051
1052 spin_lock(&sh->lock);
1053 clear_bit(STRIPE_HANDLE, &sh->state);
1054 clear_bit(STRIPE_DELAYED, &sh->state);
1055
1056 syncing = test_bit(STRIPE_SYNCING, &sh->state);
1057 /* Now to look around and see what can be done */
1058
1059 rcu_read_lock();
1060 for (i=disks; i--; ) {
1061 mdk_rdev_t *rdev;
1062 dev = &sh->dev[i];
1063 clear_bit(R5_Insync, &dev->flags);
1064
1065 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
1066 i, dev->flags, dev->toread, dev->towrite, dev->written);
1067 /* maybe we can reply to a read */
1068 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
1069 struct bio *rbi, *rbi2;
1070 PRINTK("Return read for disc %d\n", i);
1071 spin_lock_irq(&conf->device_lock);
1072 rbi = dev->toread;
1073 dev->toread = NULL;
1074 if (test_and_clear_bit(R5_Overlap, &dev->flags))
1075 wake_up(&conf->wait_for_overlap);
1076 spin_unlock_irq(&conf->device_lock);
1077 while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1078 copy_data(0, rbi, dev->page, dev->sector);
1079 rbi2 = r5_next_bio(rbi, dev->sector);
1080 spin_lock_irq(&conf->device_lock);
1081 if (--rbi->bi_phys_segments == 0) {
1082 rbi->bi_next = return_bi;
1083 return_bi = rbi;
1084 }
1085 spin_unlock_irq(&conf->device_lock);
1086 rbi = rbi2;
1087 }
1088 }
1089
1090 /* now count some things */
1091 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
1092 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
1093
1094
1095 if (dev->toread) to_read++;
1096 if (dev->towrite) {
1097 to_write++;
1098 if (!test_bit(R5_OVERWRITE, &dev->flags))
1099 non_overwrite++;
1100 }
1101 if (dev->written) written++;
1102 rdev = rcu_dereference(conf->disks[i].rdev);
1103 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
1104 /* The ReadError flag will just be confusing now */
1105 clear_bit(R5_ReadError, &dev->flags);
1106 clear_bit(R5_ReWrite, &dev->flags);
1107 }
1108 if (!rdev || !test_bit(In_sync, &rdev->flags)
1109 || test_bit(R5_ReadError, &dev->flags)) {
1110 if ( failed < 2 )
1111 failed_num[failed] = i;
1112 failed++;
1113 } else
1114 set_bit(R5_Insync, &dev->flags);
1115 }
1116 rcu_read_unlock();
1117 PRINTK("locked=%d uptodate=%d to_read=%d"
1118 " to_write=%d failed=%d failed_num=%d,%d\n",
1119 locked, uptodate, to_read, to_write, failed,
1120 failed_num[0], failed_num[1]);
1121 /* check if the array has lost >2 devices and, if so, some requests might
1122 * need to be failed
1123 */
1124 if (failed > 2 && to_read+to_write+written) {
1125 for (i=disks; i--; ) {
1126 int bitmap_end = 0;
1127
1128 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1129 mdk_rdev_t *rdev;
1130 rcu_read_lock();
1131 rdev = rcu_dereference(conf->disks[i].rdev);
1132 if (rdev && test_bit(In_sync, &rdev->flags))
1133 /* multiple read failures in one stripe */
1134 md_error(conf->mddev, rdev);
1135 rcu_read_unlock();
1136 }
1137
1138 spin_lock_irq(&conf->device_lock);
1139 /* fail all writes first */
1140 bi = sh->dev[i].towrite;
1141 sh->dev[i].towrite = NULL;
1142 if (bi) { to_write--; bitmap_end = 1; }
1143
1144 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1145 wake_up(&conf->wait_for_overlap);
1146
1147 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1148 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1149 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1150 if (--bi->bi_phys_segments == 0) {
1151 md_write_end(conf->mddev);
1152 bi->bi_next = return_bi;
1153 return_bi = bi;
1154 }
1155 bi = nextbi;
1156 }
1157 /* and fail all 'written' */
1158 bi = sh->dev[i].written;
1159 sh->dev[i].written = NULL;
1160 if (bi) bitmap_end = 1;
1161 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
1162 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1163 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1164 if (--bi->bi_phys_segments == 0) {
1165 md_write_end(conf->mddev);
1166 bi->bi_next = return_bi;
1167 return_bi = bi;
1168 }
1169 bi = bi2;
1170 }
1171
1172 /* fail any reads if this device is non-operational */
1173 if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1174 test_bit(R5_ReadError, &sh->dev[i].flags)) {
1175 bi = sh->dev[i].toread;
1176 sh->dev[i].toread = NULL;
1177 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1178 wake_up(&conf->wait_for_overlap);
1179 if (bi) to_read--;
1180 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1181 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1182 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1183 if (--bi->bi_phys_segments == 0) {
1184 bi->bi_next = return_bi;
1185 return_bi = bi;
1186 }
1187 bi = nextbi;
1188 }
1189 }
1190 spin_unlock_irq(&conf->device_lock);
1191 if (bitmap_end)
1192 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1193 STRIPE_SECTORS, 0, 0);
1194 }
1195 }
1196 if (failed > 2 && syncing) {
1197 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1198 clear_bit(STRIPE_SYNCING, &sh->state);
1199 syncing = 0;
1200 }
1201
1202 /*
1203 * might be able to return some write requests if the parity blocks
1204 * are safe, or on a failed drive
1205 */
1206 pdev = &sh->dev[pd_idx];
1207 p_failed = (failed >= 1 && failed_num[0] == pd_idx)
1208 || (failed >= 2 && failed_num[1] == pd_idx);
1209 qdev = &sh->dev[qd_idx];
1210 q_failed = (failed >= 1 && failed_num[0] == qd_idx)
1211 || (failed >= 2 && failed_num[1] == qd_idx);
1212
1213 if ( written &&
1214 ( p_failed || ((test_bit(R5_Insync, &pdev->flags)
1215 && !test_bit(R5_LOCKED, &pdev->flags)
1216 && test_bit(R5_UPTODATE, &pdev->flags))) ) &&
1217 ( q_failed || ((test_bit(R5_Insync, &qdev->flags)
1218 && !test_bit(R5_LOCKED, &qdev->flags)
1219 && test_bit(R5_UPTODATE, &qdev->flags))) ) ) {
1220 /* any written block on an uptodate or failed drive can be
1221 * returned. Note that if we 'wrote' to a failed drive,
1222 * it will be UPTODATE, but never LOCKED, so we don't need
1223 * to test 'failed' directly.
1224 */
1225 for (i=disks; i--; )
1226 if (sh->dev[i].written) {
1227 dev = &sh->dev[i];
1228 if (!test_bit(R5_LOCKED, &dev->flags) &&
1229 test_bit(R5_UPTODATE, &dev->flags) ) {
1230 /* We can return any write requests */
1231 int bitmap_end = 0;
1232 struct bio *wbi, *wbi2;
1233 PRINTK("Return write for stripe %llu disc %d\n",
1234 (unsigned long long)sh->sector, i);
1235 spin_lock_irq(&conf->device_lock);
1236 wbi = dev->written;
1237 dev->written = NULL;
1238 while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1239 wbi2 = r5_next_bio(wbi, dev->sector);
1240 if (--wbi->bi_phys_segments == 0) {
1241 md_write_end(conf->mddev);
1242 wbi->bi_next = return_bi;
1243 return_bi = wbi;
1244 }
1245 wbi = wbi2;
1246 }
1247 if (dev->towrite == NULL)
1248 bitmap_end = 1;
1249 spin_unlock_irq(&conf->device_lock);
1250 if (bitmap_end)
1251 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1252 STRIPE_SECTORS,
1253 !test_bit(STRIPE_DEGRADED, &sh->state), 0);
1254 }
1255 }
1256 }
1257
1258 /* Now we might consider reading some blocks, either to check/generate
1259 * parity, or to satisfy requests
1260 * or to load a block that is being partially written.
1261 */
1262 if (to_read || non_overwrite || (to_write && failed) || (syncing && (uptodate < disks))) {
1263 for (i=disks; i--;) {
1264 dev = &sh->dev[i];
1265 if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1266 (dev->toread ||
1267 (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1268 syncing ||
1269 (failed >= 1 && (sh->dev[failed_num[0]].toread || to_write)) ||
1270 (failed >= 2 && (sh->dev[failed_num[1]].toread || to_write))
1271 )
1272 ) {
1273 /* we would like to get this block, possibly
1274 * by computing it, but we might not be able to
1275 */
1276 if (uptodate == disks-1) {
1277 PRINTK("Computing stripe %llu block %d\n",
1278 (unsigned long long)sh->sector, i);
1279 compute_block_1(sh, i, 0);
1280 uptodate++;
1281 } else if ( uptodate == disks-2 && failed >= 2 ) {
1282 /* Computing 2-failure is *very* expensive; only do it if failed >= 2 */
1283 int other;
1284 for (other=disks; other--;) {
1285 if ( other == i )
1286 continue;
1287 if ( !test_bit(R5_UPTODATE, &sh->dev[other].flags) )
1288 break;
1289 }
1290 BUG_ON(other < 0);
1291 PRINTK("Computing stripe %llu blocks %d,%d\n",
1292 (unsigned long long)sh->sector, i, other);
1293 compute_block_2(sh, i, other);
1294 uptodate += 2;
1295 } else if (test_bit(R5_Insync, &dev->flags)) {
1296 set_bit(R5_LOCKED, &dev->flags);
1297 set_bit(R5_Wantread, &dev->flags);
1298 #if 0
1299 /* if I am just reading this block and we don't have
1300 a failed drive, or any pending writes then sidestep the cache */
1301 if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
1302 ! syncing && !failed && !to_write) {
1303 sh->bh_cache[i]->b_page = sh->bh_read[i]->b_page;
1304 sh->bh_cache[i]->b_data = sh->bh_read[i]->b_data;
1305 }
1306 #endif
1307 locked++;
1308 PRINTK("Reading block %d (sync=%d)\n",
1309 i, syncing);
1310 }
1311 }
1312 }
1313 set_bit(STRIPE_HANDLE, &sh->state);
1314 }
1315
1316 /* now to consider writing and what else, if anything should be read */
1317 if (to_write) {
1318 int rcw=0, must_compute=0;
1319 for (i=disks ; i--;) {
1320 dev = &sh->dev[i];
1321 /* Would I have to read this buffer for reconstruct_write */
1322 if (!test_bit(R5_OVERWRITE, &dev->flags)
1323 && i != pd_idx && i != qd_idx
1324 && (!test_bit(R5_LOCKED, &dev->flags)
1325 #if 0
1326 || sh->bh_page[i] != bh->b_page
1327 #endif
1328 ) &&
1329 !test_bit(R5_UPTODATE, &dev->flags)) {
1330 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1331 else {
1332 PRINTK("raid6: must_compute: disk %d flags=%#lx\n", i, dev->flags);
1333 must_compute++;
1334 }
1335 }
1336 }
1337 PRINTK("for sector %llu, rcw=%d, must_compute=%d\n",
1338 (unsigned long long)sh->sector, rcw, must_compute);
1339 set_bit(STRIPE_HANDLE, &sh->state);
1340
1341 if (rcw > 0)
1342 /* want reconstruct write, but need to get some data */
1343 for (i=disks; i--;) {
1344 dev = &sh->dev[i];
1345 if (!test_bit(R5_OVERWRITE, &dev->flags)
1346 && !(failed == 0 && (i == pd_idx || i == qd_idx))
1347 && !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1348 test_bit(R5_Insync, &dev->flags)) {
1349 if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1350 {
1351 PRINTK("Read_old stripe %llu block %d for Reconstruct\n",
1352 (unsigned long long)sh->sector, i);
1353 set_bit(R5_LOCKED, &dev->flags);
1354 set_bit(R5_Wantread, &dev->flags);
1355 locked++;
1356 } else {
1357 PRINTK("Request delayed stripe %llu block %d for Reconstruct\n",
1358 (unsigned long long)sh->sector, i);
1359 set_bit(STRIPE_DELAYED, &sh->state);
1360 set_bit(STRIPE_HANDLE, &sh->state);
1361 }
1362 }
1363 }
1364 /* now if nothing is locked, and if we have enough data, we can start a write request */
1365 if (locked == 0 && rcw == 0 &&
1366 !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
1367 if ( must_compute > 0 ) {
1368 /* We have failed blocks and need to compute them */
1369 switch ( failed ) {
1370 case 0: BUG();
1371 case 1: compute_block_1(sh, failed_num[0], 0); break;
1372 case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break;
1373 default: BUG(); /* This request should have been failed? */
1374 }
1375 }
1376
1377 PRINTK("Computing parity for stripe %llu\n", (unsigned long long)sh->sector);
1378 compute_parity(sh, RECONSTRUCT_WRITE);
1379 /* now every locked buffer is ready to be written */
1380 for (i=disks; i--;)
1381 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1382 PRINTK("Writing stripe %llu block %d\n",
1383 (unsigned long long)sh->sector, i);
1384 locked++;
1385 set_bit(R5_Wantwrite, &sh->dev[i].flags);
1386 }
1387 /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
1388 set_bit(STRIPE_INSYNC, &sh->state);
1389
1390 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1391 atomic_dec(&conf->preread_active_stripes);
1392 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1393 md_wakeup_thread(conf->mddev->thread);
1394 }
1395 }
1396 }
1397
1398 /* maybe we need to check and possibly fix the parity for this stripe
1399 * Any reads will already have been scheduled, so we just see if enough data
1400 * is available
1401 */
1402 if (syncing && locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state)) {
1403 int update_p = 0, update_q = 0;
1404 struct r5dev *dev;
1405
1406 set_bit(STRIPE_HANDLE, &sh->state);
1407
1408 BUG_ON(failed>2);
1409 BUG_ON(uptodate < disks);
1410 /* Want to check and possibly repair P and Q.
1411 * However there could be one 'failed' device, in which
1412 * case we can only check one of them, possibly using the
1413 * other to generate missing data
1414 */
1415
1416 /* If !tmp_page, we cannot do the calculations,
1417 * but as we have set STRIPE_HANDLE, we will soon be called
1418 * by stripe_handle with a tmp_page - just wait until then.
1419 */
1420 if (tmp_page) {
1421 if (failed == q_failed) {
1422 /* The only possible failed device holds 'Q', so it makes
1423 * sense to check P (If anything else were failed, we would
1424 * have used P to recreate it).
1425 */
1426 compute_block_1(sh, pd_idx, 1);
1427 if (!page_is_zero(sh->dev[pd_idx].page)) {
1428 compute_block_1(sh,pd_idx,0);
1429 update_p = 1;
1430 }
1431 }
1432 if (!q_failed && failed < 2) {
1433 /* q is not failed, and we didn't use it to generate
1434 * anything, so it makes sense to check it
1435 */
1436 memcpy(page_address(tmp_page),
1437 page_address(sh->dev[qd_idx].page),
1438 STRIPE_SIZE);
1439 compute_parity(sh, UPDATE_PARITY);
1440 if (memcmp(page_address(tmp_page),
1441 page_address(sh->dev[qd_idx].page),
1442 STRIPE_SIZE)!= 0) {
1443 clear_bit(STRIPE_INSYNC, &sh->state);
1444 update_q = 1;
1445 }
1446 }
1447 if (update_p || update_q) {
1448 conf->mddev->resync_mismatches += STRIPE_SECTORS;
1449 if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
1450 /* don't try to repair!! */
1451 update_p = update_q = 0;
1452 }
1453
1454 /* now write out any block on a failed drive,
1455 * or P or Q if they need it
1456 */
1457
1458 if (failed == 2) {
1459 dev = &sh->dev[failed_num[1]];
1460 locked++;
1461 set_bit(R5_LOCKED, &dev->flags);
1462 set_bit(R5_Wantwrite, &dev->flags);
1463 }
1464 if (failed >= 1) {
1465 dev = &sh->dev[failed_num[0]];
1466 locked++;
1467 set_bit(R5_LOCKED, &dev->flags);
1468 set_bit(R5_Wantwrite, &dev->flags);
1469 }
1470
1471 if (update_p) {
1472 dev = &sh->dev[pd_idx];
1473 locked ++;
1474 set_bit(R5_LOCKED, &dev->flags);
1475 set_bit(R5_Wantwrite, &dev->flags);
1476 }
1477 if (update_q) {
1478 dev = &sh->dev[qd_idx];
1479 locked++;
1480 set_bit(R5_LOCKED, &dev->flags);
1481 set_bit(R5_Wantwrite, &dev->flags);
1482 }
1483 clear_bit(STRIPE_DEGRADED, &sh->state);
1484
1485 set_bit(STRIPE_INSYNC, &sh->state);
1486 }
1487 }
1488
1489 if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1490 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1491 clear_bit(STRIPE_SYNCING, &sh->state);
1492 }
1493
1494 /* If the failed drives are just a ReadError, then we might need
1495 * to progress the repair/check process
1496 */
1497 if (failed <= 2 && ! conf->mddev->ro)
1498 for (i=0; i<failed;i++) {
1499 dev = &sh->dev[failed_num[i]];
1500 if (test_bit(R5_ReadError, &dev->flags)
1501 && !test_bit(R5_LOCKED, &dev->flags)
1502 && test_bit(R5_UPTODATE, &dev->flags)
1503 ) {
1504 if (!test_bit(R5_ReWrite, &dev->flags)) {
1505 set_bit(R5_Wantwrite, &dev->flags);
1506 set_bit(R5_ReWrite, &dev->flags);
1507 set_bit(R5_LOCKED, &dev->flags);
1508 } else {
1509 /* let's read it back */
1510 set_bit(R5_Wantread, &dev->flags);
1511 set_bit(R5_LOCKED, &dev->flags);
1512 }
1513 }
1514 }
1515 spin_unlock(&sh->lock);
1516
1517 while ((bi=return_bi)) {
1518 int bytes = bi->bi_size;
1519
1520 return_bi = bi->bi_next;
1521 bi->bi_next = NULL;
1522 bi->bi_size = 0;
1523 bi->bi_end_io(bi, bytes, 0);
1524 }
1525 for (i=disks; i-- ;) {
1526 int rw;
1527 struct bio *bi;
1528 mdk_rdev_t *rdev;
1529 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1530 rw = 1;
1531 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1532 rw = 0;
1533 else
1534 continue;
1535
1536 bi = &sh->dev[i].req;
1537
1538 bi->bi_rw = rw;
1539 if (rw)
1540 bi->bi_end_io = raid6_end_write_request;
1541 else
1542 bi->bi_end_io = raid6_end_read_request;
1543
1544 rcu_read_lock();
1545 rdev = rcu_dereference(conf->disks[i].rdev);
1546 if (rdev && test_bit(Faulty, &rdev->flags))
1547 rdev = NULL;
1548 if (rdev)
1549 atomic_inc(&rdev->nr_pending);
1550 rcu_read_unlock();
1551
1552 if (rdev) {
1553 if (syncing)
1554 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1555
1556 bi->bi_bdev = rdev->bdev;
1557 PRINTK("for %llu schedule op %ld on disc %d\n",
1558 (unsigned long long)sh->sector, bi->bi_rw, i);
1559 atomic_inc(&sh->count);
1560 bi->bi_sector = sh->sector + rdev->data_offset;
1561 bi->bi_flags = 1 << BIO_UPTODATE;
1562 bi->bi_vcnt = 1;
1563 bi->bi_max_vecs = 1;
1564 bi->bi_idx = 0;
1565 bi->bi_io_vec = &sh->dev[i].vec;
1566 bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1567 bi->bi_io_vec[0].bv_offset = 0;
1568 bi->bi_size = STRIPE_SIZE;
1569 bi->bi_next = NULL;
1570 if (rw == WRITE &&
1571 test_bit(R5_ReWrite, &sh->dev[i].flags))
1572 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1573 generic_make_request(bi);
1574 } else {
1575 if (rw == 1)
1576 set_bit(STRIPE_DEGRADED, &sh->state);
1577 PRINTK("skip op %ld on disc %d for sector %llu\n",
1578 bi->bi_rw, i, (unsigned long long)sh->sector);
1579 clear_bit(R5_LOCKED, &sh->dev[i].flags);
1580 set_bit(STRIPE_HANDLE, &sh->state);
1581 }
1582 }
1583 }
1584
1585 static void raid6_activate_delayed(raid6_conf_t *conf)
1586 {
1587 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
1588 while (!list_empty(&conf->delayed_list)) {
1589 struct list_head *l = conf->delayed_list.next;
1590 struct stripe_head *sh;
1591 sh = list_entry(l, struct stripe_head, lru);
1592 list_del_init(l);
1593 clear_bit(STRIPE_DELAYED, &sh->state);
1594 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1595 atomic_inc(&conf->preread_active_stripes);
1596 list_add_tail(&sh->lru, &conf->handle_list);
1597 }
1598 }
1599 }
1600
1601 static void activate_bit_delay(raid6_conf_t *conf)
1602 {
1603 /* device_lock is held */
1604 struct list_head head;
1605 list_add(&head, &conf->bitmap_list);
1606 list_del_init(&conf->bitmap_list);
1607 while (!list_empty(&head)) {
1608 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
1609 list_del_init(&sh->lru);
1610 atomic_inc(&sh->count);
1611 __release_stripe(conf, sh);
1612 }
1613 }
1614
1615 static void unplug_slaves(mddev_t *mddev)
1616 {
1617 raid6_conf_t *conf = mddev_to_conf(mddev);
1618 int i;
1619
1620 rcu_read_lock();
1621 for (i=0; i<mddev->raid_disks; i++) {
1622 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
1623 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
1624 request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
1625
1626 atomic_inc(&rdev->nr_pending);
1627 rcu_read_unlock();
1628
1629 if (r_queue->unplug_fn)
1630 r_queue->unplug_fn(r_queue);
1631
1632 rdev_dec_pending(rdev, mddev);
1633 rcu_read_lock();
1634 }
1635 }
1636 rcu_read_unlock();
1637 }
1638
1639 static void raid6_unplug_device(request_queue_t *q)
1640 {
1641 mddev_t *mddev = q->queuedata;
1642 raid6_conf_t *conf = mddev_to_conf(mddev);
1643 unsigned long flags;
1644
1645 spin_lock_irqsave(&conf->device_lock, flags);
1646
1647 if (blk_remove_plug(q)) {
1648 conf->seq_flush++;
1649 raid6_activate_delayed(conf);
1650 }
1651 md_wakeup_thread(mddev->thread);
1652
1653 spin_unlock_irqrestore(&conf->device_lock, flags);
1654
1655 unplug_slaves(mddev);
1656 }
1657
1658 static int raid6_issue_flush(request_queue_t *q, struct gendisk *disk,
1659 sector_t *error_sector)
1660 {
1661 mddev_t *mddev = q->queuedata;
1662 raid6_conf_t *conf = mddev_to_conf(mddev);
1663 int i, ret = 0;
1664
1665 rcu_read_lock();
1666 for (i=0; i<mddev->raid_disks && ret == 0; i++) {
1667 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
1668 if (rdev && !test_bit(Faulty, &rdev->flags)) {
1669 struct block_device *bdev = rdev->bdev;
1670 request_queue_t *r_queue = bdev_get_queue(bdev);
1671
1672 if (!r_queue->issue_flush_fn)
1673 ret = -EOPNOTSUPP;
1674 else {
1675 atomic_inc(&rdev->nr_pending);
1676 rcu_read_unlock();
1677 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
1678 error_sector);
1679 rdev_dec_pending(rdev, mddev);
1680 rcu_read_lock();
1681 }
1682 }
1683 }
1684 rcu_read_unlock();
1685 return ret;
1686 }
1687
1688 static inline void raid6_plug_device(raid6_conf_t *conf)
1689 {
1690 spin_lock_irq(&conf->device_lock);
1691 blk_plug_device(conf->mddev->queue);
1692 spin_unlock_irq(&conf->device_lock);
1693 }
1694
1695 static int make_request (request_queue_t *q, struct bio * bi)
1696 {
1697 mddev_t *mddev = q->queuedata;
1698 raid6_conf_t *conf = mddev_to_conf(mddev);
1699 const unsigned int raid_disks = conf->raid_disks;
1700 const unsigned int data_disks = raid_disks - 2;
1701 unsigned int dd_idx, pd_idx;
1702 sector_t new_sector;
1703 sector_t logical_sector, last_sector;
1704 struct stripe_head *sh;
1705 const int rw = bio_data_dir(bi);
1706
1707 if (unlikely(bio_barrier(bi))) {
1708 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
1709 return 0;
1710 }
1711
1712 md_write_start(mddev, bi);
1713
1714 disk_stat_inc(mddev->gendisk, ios[rw]);
1715 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
1716
1717 logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
1718 last_sector = bi->bi_sector + (bi->bi_size>>9);
1719
1720 bi->bi_next = NULL;
1721 bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
1722
1723 for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
1724 DEFINE_WAIT(w);
1725
1726 new_sector = raid6_compute_sector(logical_sector,
1727 raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1728
1729 PRINTK("raid6: make_request, sector %llu logical %llu\n",
1730 (unsigned long long)new_sector,
1731 (unsigned long long)logical_sector);
1732
1733 retry:
1734 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
1735 sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
1736 if (sh) {
1737 if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
1738 /* Add failed due to overlap. Flush everything
1739 * and wait a while
1740 */
1741 raid6_unplug_device(mddev->queue);
1742 release_stripe(sh);
1743 schedule();
1744 goto retry;
1745 }
1746 finish_wait(&conf->wait_for_overlap, &w);
1747 raid6_plug_device(conf);
1748 handle_stripe(sh, NULL);
1749 release_stripe(sh);
1750 } else {
1751 /* cannot get stripe for read-ahead, just give-up */
1752 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1753 finish_wait(&conf->wait_for_overlap, &w);
1754 break;
1755 }
1756
1757 }
1758 spin_lock_irq(&conf->device_lock);
1759 if (--bi->bi_phys_segments == 0) {
1760 int bytes = bi->bi_size;
1761
1762 if (rw == WRITE )
1763 md_write_end(mddev);
1764 bi->bi_size = 0;
1765 bi->bi_end_io(bi, bytes, 0);
1766 }
1767 spin_unlock_irq(&conf->device_lock);
1768 return 0;
1769 }
1770
1771 /* FIXME go_faster isn't used */
1772 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1773 {
1774 raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
1775 struct stripe_head *sh;
1776 int sectors_per_chunk = conf->chunk_size >> 9;
1777 sector_t x;
1778 unsigned long stripe;
1779 int chunk_offset;
1780 int dd_idx, pd_idx;
1781 sector_t first_sector;
1782 int raid_disks = conf->raid_disks;
1783 int data_disks = raid_disks - 2;
1784 sector_t max_sector = mddev->size << 1;
1785 int sync_blocks;
1786 int still_degraded = 0;
1787 int i;
1788
1789 if (sector_nr >= max_sector) {
1790 /* just being told to finish up .. nothing much to do */
1791 unplug_slaves(mddev);
1792
1793 if (mddev->curr_resync < max_sector) /* aborted */
1794 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1795 &sync_blocks, 1);
1796 else /* completed sync */
1797 conf->fullsync = 0;
1798 bitmap_close_sync(mddev->bitmap);
1799
1800 return 0;
1801 }
1802 /* if there are 2 or more failed drives and we are trying
1803 * to resync, then assert that we are finished, because there is
1804 * nothing we can do.
1805 */
1806 if (mddev->degraded >= 2 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1807 sector_t rv = (mddev->size << 1) - sector_nr;
1808 *skipped = 1;
1809 return rv;
1810 }
1811 if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1812 !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
1813 !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
1814 /* we can skip this block, and probably more */
1815 sync_blocks /= STRIPE_SECTORS;
1816 *skipped = 1;
1817 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
1818 }
1819
1820 x = sector_nr;
1821 chunk_offset = sector_div(x, sectors_per_chunk);
1822 stripe = x;
1823 BUG_ON(x != stripe);
1824
1825 first_sector = raid6_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
1826 + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1827 sh = get_active_stripe(conf, sector_nr, pd_idx, 1);
1828 if (sh == NULL) {
1829 sh = get_active_stripe(conf, sector_nr, pd_idx, 0);
1830 /* make sure we don't swamp the stripe cache if someone else
1831 * is trying to get access
1832 */
1833 schedule_timeout_uninterruptible(1);
1834 }
1835 /* Need to check if array will still be degraded after recovery/resync
1836 * We don't need to check the 'failed' flag as when that gets set,
1837 * recovery aborts.
1838 */
1839 for (i=0; i<mddev->raid_disks; i++)
1840 if (conf->disks[i].rdev == NULL)
1841 still_degraded = 1;
1842
1843 bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
1844
1845 spin_lock(&sh->lock);
1846 set_bit(STRIPE_SYNCING, &sh->state);
1847 clear_bit(STRIPE_INSYNC, &sh->state);
1848 spin_unlock(&sh->lock);
1849
1850 handle_stripe(sh, NULL);
1851 release_stripe(sh);
1852
1853 return STRIPE_SECTORS;
1854 }
1855
1856 /*
1857 * This is our raid6 kernel thread.
1858 *
1859 * We scan the hash table for stripes which can be handled now.
1860 * During the scan, completed stripes are saved for us by the interrupt
1861 * handler, so that they will not have to wait for our next wakeup.
1862 */
1863 static void raid6d (mddev_t *mddev)
1864 {
1865 struct stripe_head *sh;
1866 raid6_conf_t *conf = mddev_to_conf(mddev);
1867 int handled;
1868
1869 PRINTK("+++ raid6d active\n");
1870
1871 md_check_recovery(mddev);
1872
1873 handled = 0;
1874 spin_lock_irq(&conf->device_lock);
1875 while (1) {
1876 struct list_head *first;
1877
1878 if (conf->seq_flush - conf->seq_write > 0) {
1879 int seq = conf->seq_flush;
1880 spin_unlock_irq(&conf->device_lock);
1881 bitmap_unplug(mddev->bitmap);
1882 spin_lock_irq(&conf->device_lock);
1883 conf->seq_write = seq;
1884 activate_bit_delay(conf);
1885 }
1886
1887 if (list_empty(&conf->handle_list) &&
1888 atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
1889 !blk_queue_plugged(mddev->queue) &&
1890 !list_empty(&conf->delayed_list))
1891 raid6_activate_delayed(conf);
1892
1893 if (list_empty(&conf->handle_list))
1894 break;
1895
1896 first = conf->handle_list.next;
1897 sh = list_entry(first, struct stripe_head, lru);
1898
1899 list_del_init(first);
1900 atomic_inc(&sh->count);
1901 BUG_ON(atomic_read(&sh->count)!= 1);
1902 spin_unlock_irq(&conf->device_lock);
1903
1904 handled++;
1905 handle_stripe(sh, conf->spare_page);
1906 release_stripe(sh);
1907
1908 spin_lock_irq(&conf->device_lock);
1909 }
1910 PRINTK("%d stripes handled\n", handled);
1911
1912 spin_unlock_irq(&conf->device_lock);
1913
1914 unplug_slaves(mddev);
1915
1916 PRINTK("--- raid6d inactive\n");
1917 }
1918
1919 static ssize_t
1920 raid6_show_stripe_cache_size(mddev_t *mddev, char *page)
1921 {
1922 raid6_conf_t *conf = mddev_to_conf(mddev);
1923 if (conf)
1924 return sprintf(page, "%d\n", conf->max_nr_stripes);
1925 else
1926 return 0;
1927 }
1928
1929 static ssize_t
1930 raid6_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
1931 {
1932 raid6_conf_t *conf = mddev_to_conf(mddev);
1933 char *end;
1934 int new;
1935 if (len >= PAGE_SIZE)
1936 return -EINVAL;
1937 if (!conf)
1938 return -ENODEV;
1939
1940 new = simple_strtoul(page, &end, 10);
1941 if (!*page || (*end && *end != '\n') )
1942 return -EINVAL;
1943 if (new <= 16 || new > 32768)
1944 return -EINVAL;
1945 while (new < conf->max_nr_stripes) {
1946 if (drop_one_stripe(conf))
1947 conf->max_nr_stripes--;
1948 else
1949 break;
1950 }
1951 while (new > conf->max_nr_stripes) {
1952 if (grow_one_stripe(conf))
1953 conf->max_nr_stripes++;
1954 else break;
1955 }
1956 return len;
1957 }
1958
1959 static struct md_sysfs_entry
1960 raid6_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
1961 raid6_show_stripe_cache_size,
1962 raid6_store_stripe_cache_size);
1963
1964 static ssize_t
1965 stripe_cache_active_show(mddev_t *mddev, char *page)
1966 {
1967 raid6_conf_t *conf = mddev_to_conf(mddev);
1968 if (conf)
1969 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
1970 else
1971 return 0;
1972 }
1973
1974 static struct md_sysfs_entry
1975 raid6_stripecache_active = __ATTR_RO(stripe_cache_active);
1976
1977 static struct attribute *raid6_attrs[] = {
1978 &raid6_stripecache_size.attr,
1979 &raid6_stripecache_active.attr,
1980 NULL,
1981 };
1982 static struct attribute_group raid6_attrs_group = {
1983 .name = NULL,
1984 .attrs = raid6_attrs,
1985 };
1986
1987 static int run(mddev_t *mddev)
1988 {
1989 raid6_conf_t *conf;
1990 int raid_disk, memory;
1991 mdk_rdev_t *rdev;
1992 struct disk_info *disk;
1993 struct list_head *tmp;
1994
1995 if (mddev->level != 6) {
1996 PRINTK("raid6: %s: raid level not set to 6 (%d)\n", mdname(mddev), mddev->level);
1997 return -EIO;
1998 }
1999
2000 mddev->private = kzalloc(sizeof (raid6_conf_t), GFP_KERNEL);
2001 if ((conf = mddev->private) == NULL)
2002 goto abort;
2003 conf->disks = kzalloc(mddev->raid_disks * sizeof(struct disk_info),
2004 GFP_KERNEL);
2005 if (!conf->disks)
2006 goto abort;
2007
2008 conf->mddev = mddev;
2009
2010 if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
2011 goto abort;
2012
2013 conf->spare_page = alloc_page(GFP_KERNEL);
2014 if (!conf->spare_page)
2015 goto abort;
2016
2017 spin_lock_init(&conf->device_lock);
2018 init_waitqueue_head(&conf->wait_for_stripe);
2019 init_waitqueue_head(&conf->wait_for_overlap);
2020 INIT_LIST_HEAD(&conf->handle_list);
2021 INIT_LIST_HEAD(&conf->delayed_list);
2022 INIT_LIST_HEAD(&conf->bitmap_list);
2023 INIT_LIST_HEAD(&conf->inactive_list);
2024 atomic_set(&conf->active_stripes, 0);
2025 atomic_set(&conf->preread_active_stripes, 0);
2026
2027 PRINTK("raid6: run(%s) called.\n", mdname(mddev));
2028
2029 ITERATE_RDEV(mddev,rdev,tmp) {
2030 raid_disk = rdev->raid_disk;
2031 if (raid_disk >= mddev->raid_disks
2032 || raid_disk < 0)
2033 continue;
2034 disk = conf->disks + raid_disk;
2035
2036 disk->rdev = rdev;
2037
2038 if (test_bit(In_sync, &rdev->flags)) {
2039 char b[BDEVNAME_SIZE];
2040 printk(KERN_INFO "raid6: device %s operational as raid"
2041 " disk %d\n", bdevname(rdev->bdev,b),
2042 raid_disk);
2043 conf->working_disks++;
2044 }
2045 }
2046
2047 conf->raid_disks = mddev->raid_disks;
2048
2049 /*
2050 * 0 for a fully functional array, 1 or 2 for a degraded array.
2051 */
2052 mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
2053 conf->mddev = mddev;
2054 conf->chunk_size = mddev->chunk_size;
2055 conf->level = mddev->level;
2056 conf->algorithm = mddev->layout;
2057 conf->max_nr_stripes = NR_STRIPES;
2058
2059 /* device size must be a multiple of chunk size */
2060 mddev->size &= ~(mddev->chunk_size/1024 -1);
2061 mddev->resync_max_sectors = mddev->size << 1;
2062
2063 if (conf->raid_disks < 4) {
2064 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
2065 mdname(mddev), conf->raid_disks);
2066 goto abort;
2067 }
2068 if (!conf->chunk_size || conf->chunk_size % 4) {
2069 printk(KERN_ERR "raid6: invalid chunk size %d for %s\n",
2070 conf->chunk_size, mdname(mddev));
2071 goto abort;
2072 }
2073 if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
2074 printk(KERN_ERR
2075 "raid6: unsupported parity algorithm %d for %s\n",
2076 conf->algorithm, mdname(mddev));
2077 goto abort;
2078 }
2079 if (mddev->degraded > 2) {
2080 printk(KERN_ERR "raid6: not enough operational devices for %s"
2081 " (%d/%d failed)\n",
2082 mdname(mddev), conf->failed_disks, conf->raid_disks);
2083 goto abort;
2084 }
2085
2086 if (mddev->degraded > 0 &&
2087 mddev->recovery_cp != MaxSector) {
2088 if (mddev->ok_start_degraded)
2089 printk(KERN_WARNING "raid6: starting dirty degraded array:%s"
2090 "- data corruption possible.\n",
2091 mdname(mddev));
2092 else {
2093 printk(KERN_ERR "raid6: cannot start dirty degraded array"
2094 " for %s\n", mdname(mddev));
2095 goto abort;
2096 }
2097 }
2098
2099 {
2100 mddev->thread = md_register_thread(raid6d, mddev, "%s_raid6");
2101 if (!mddev->thread) {
2102 printk(KERN_ERR
2103 "raid6: couldn't allocate thread for %s\n",
2104 mdname(mddev));
2105 goto abort;
2106 }
2107 }
2108
2109 memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
2110 conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
2111 if (grow_stripes(conf, conf->max_nr_stripes)) {
2112 printk(KERN_ERR
2113 "raid6: couldn't allocate %dkB for buffers\n", memory);
2114 shrink_stripes(conf);
2115 md_unregister_thread(mddev->thread);
2116 goto abort;
2117 } else
2118 printk(KERN_INFO "raid6: allocated %dkB for %s\n",
2119 memory, mdname(mddev));
2120
2121 if (mddev->degraded == 0)
2122 printk(KERN_INFO "raid6: raid level %d set %s active with %d out of %d"
2123 " devices, algorithm %d\n", conf->level, mdname(mddev),
2124 mddev->raid_disks-mddev->degraded, mddev->raid_disks,
2125 conf->algorithm);
2126 else
2127 printk(KERN_ALERT "raid6: raid level %d set %s active with %d"
2128 " out of %d devices, algorithm %d\n", conf->level,
2129 mdname(mddev), mddev->raid_disks - mddev->degraded,
2130 mddev->raid_disks, conf->algorithm);
2131
2132 print_raid6_conf(conf);
2133
2134 /* read-ahead size must cover two whole stripes, which is
2135 * 2 * (n-2) * chunksize where 'n' is the number of raid devices
2136 */
2137 {
2138 int stripe = (mddev->raid_disks-2) * mddev->chunk_size
2139 / PAGE_SIZE;
2140 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
2141 mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
2142 }
2143
2144 /* Ok, everything is just fine now */
2145 sysfs_create_group(&mddev->kobj, &raid6_attrs_group);
2146
2147 mddev->array_size = mddev->size * (mddev->raid_disks - 2);
2148
2149 mddev->queue->unplug_fn = raid6_unplug_device;
2150 mddev->queue->issue_flush_fn = raid6_issue_flush;
2151 return 0;
2152 abort:
2153 if (conf) {
2154 print_raid6_conf(conf);
2155 safe_put_page(conf->spare_page);
2156 kfree(conf->stripe_hashtbl);
2157 kfree(conf->disks);
2158 kfree(conf);
2159 }
2160 mddev->private = NULL;
2161 printk(KERN_ALERT "raid6: failed to run raid set %s\n", mdname(mddev));
2162 return -EIO;
2163 }
2164
2165
2166
2167 static int stop (mddev_t *mddev)
2168 {
2169 raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
2170
2171 md_unregister_thread(mddev->thread);
2172 mddev->thread = NULL;
2173 shrink_stripes(conf);
2174 kfree(conf->stripe_hashtbl);
2175 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2176 sysfs_remove_group(&mddev->kobj, &raid6_attrs_group);
2177 kfree(conf);
2178 mddev->private = NULL;
2179 return 0;
2180 }
2181
2182 #if RAID6_DUMPSTATE
2183 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
2184 {
2185 int i;
2186
2187 seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
2188 (unsigned long long)sh->sector, sh->pd_idx, sh->state);
2189 seq_printf(seq, "sh %llu, count %d.\n",
2190 (unsigned long long)sh->sector, atomic_read(&sh->count));
2191 seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
2192 for (i = 0; i < sh->raid_conf->raid_disks; i++) {
2193 seq_printf(seq, "(cache%d: %p %ld) ",
2194 i, sh->dev[i].page, sh->dev[i].flags);
2195 }
2196 seq_printf(seq, "\n");
2197 }
2198
2199 static void printall (struct seq_file *seq, raid6_conf_t *conf)
2200 {
2201 struct stripe_head *sh;
2202 struct hlist_node *hn;
2203 int i;
2204
2205 spin_lock_irq(&conf->device_lock);
2206 for (i = 0; i < NR_HASH; i++) {
2207 sh = conf->stripe_hashtbl[i];
2208 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
2209 if (sh->raid_conf != conf)
2210 continue;
2211 print_sh(seq, sh);
2212 }
2213 }
2214 spin_unlock_irq(&conf->device_lock);
2215 }
2216 #endif
2217
2218 static void status (struct seq_file *seq, mddev_t *mddev)
2219 {
2220 raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
2221 int i;
2222
2223 seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
2224 seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
2225 for (i = 0; i < conf->raid_disks; i++)
2226 seq_printf (seq, "%s",
2227 conf->disks[i].rdev &&
2228 test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
2229 seq_printf (seq, "]");
2230 #if RAID6_DUMPSTATE
2231 seq_printf (seq, "\n");
2232 printall(seq, conf);
2233 #endif
2234 }
2235
2236 static void print_raid6_conf (raid6_conf_t *conf)
2237 {
2238 int i;
2239 struct disk_info *tmp;
2240
2241 printk("RAID6 conf printout:\n");
2242 if (!conf) {
2243 printk("(conf==NULL)\n");
2244 return;
2245 }
2246 printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
2247 conf->working_disks, conf->failed_disks);
2248
2249 for (i = 0; i < conf->raid_disks; i++) {
2250 char b[BDEVNAME_SIZE];
2251 tmp = conf->disks + i;
2252 if (tmp->rdev)
2253 printk(" disk %d, o:%d, dev:%s\n",
2254 i, !test_bit(Faulty, &tmp->rdev->flags),
2255 bdevname(tmp->rdev->bdev,b));
2256 }
2257 }
2258
2259 static int raid6_spare_active(mddev_t *mddev)
2260 {
2261 int i;
2262 raid6_conf_t *conf = mddev->private;
2263 struct disk_info *tmp;
2264
2265 for (i = 0; i < conf->raid_disks; i++) {
2266 tmp = conf->disks + i;
2267 if (tmp->rdev
2268 && !test_bit(Faulty, &tmp->rdev->flags)
2269 && !test_bit(In_sync, &tmp->rdev->flags)) {
2270 mddev->degraded--;
2271 conf->failed_disks--;
2272 conf->working_disks++;
2273 set_bit(In_sync, &tmp->rdev->flags);
2274 }
2275 }
2276 print_raid6_conf(conf);
2277 return 0;
2278 }
2279
2280 static int raid6_remove_disk(mddev_t *mddev, int number)
2281 {
2282 raid6_conf_t *conf = mddev->private;
2283 int err = 0;
2284 mdk_rdev_t *rdev;
2285 struct disk_info *p = conf->disks + number;
2286
2287 print_raid6_conf(conf);
2288 rdev = p->rdev;
2289 if (rdev) {
2290 if (test_bit(In_sync, &rdev->flags) ||
2291 atomic_read(&rdev->nr_pending)) {
2292 err = -EBUSY;
2293 goto abort;
2294 }
2295 p->rdev = NULL;
2296 synchronize_rcu();
2297 if (atomic_read(&rdev->nr_pending)) {
2298 /* lost the race, try later */
2299 err = -EBUSY;
2300 p->rdev = rdev;
2301 }
2302 }
2303
2304 abort:
2305
2306 print_raid6_conf(conf);
2307 return err;
2308 }
2309
2310 static int raid6_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
2311 {
2312 raid6_conf_t *conf = mddev->private;
2313 int found = 0;
2314 int disk;
2315 struct disk_info *p;
2316
2317 if (mddev->degraded > 2)
2318 /* no point adding a device */
2319 return 0;
2320 /*
2321 * find the disk ... but prefer rdev->saved_raid_disk
2322 * if possible.
2323 */
2324 if (rdev->saved_raid_disk >= 0 &&
2325 conf->disks[rdev->saved_raid_disk].rdev == NULL)
2326 disk = rdev->saved_raid_disk;
2327 else
2328 disk = 0;
2329 for ( ; disk < mddev->raid_disks; disk++)
2330 if ((p=conf->disks + disk)->rdev == NULL) {
2331 clear_bit(In_sync, &rdev->flags);
2332 rdev->raid_disk = disk;
2333 found = 1;
2334 if (rdev->saved_raid_disk != disk)
2335 conf->fullsync = 1;
2336 rcu_assign_pointer(p->rdev, rdev);
2337 break;
2338 }
2339 print_raid6_conf(conf);
2340 return found;
2341 }
2342
2343 static int raid6_resize(mddev_t *mddev, sector_t sectors)
2344 {
2345 /* no resync is happening, and there is enough space
2346 * on all devices, so we can resize.
2347 * We need to make sure resync covers any new space.
2348 * If the array is shrinking we should possibly wait until
2349 * any io in the removed space completes, but it hardly seems
2350 * worth it.
2351 */
2352 sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
2353 mddev->array_size = (sectors * (mddev->raid_disks-2))>>1;
2354 set_capacity(mddev->gendisk, mddev->array_size << 1);
2355 mddev->changed = 1;
2356 if (sectors/2 > mddev->size && mddev->recovery_cp == MaxSector) {
2357 mddev->recovery_cp = mddev->size << 1;
2358 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2359 }
2360 mddev->size = sectors /2;
2361 mddev->resync_max_sectors = sectors;
2362 return 0;
2363 }
2364
2365 static void raid6_quiesce(mddev_t *mddev, int state)
2366 {
2367 raid6_conf_t *conf = mddev_to_conf(mddev);
2368
2369 switch(state) {
2370 case 1: /* stop all writes */
2371 spin_lock_irq(&conf->device_lock);
2372 conf->quiesce = 1;
2373 wait_event_lock_irq(conf->wait_for_stripe,
2374 atomic_read(&conf->active_stripes) == 0,
2375 conf->device_lock, /* nothing */);
2376 spin_unlock_irq(&conf->device_lock);
2377 break;
2378
2379 case 0: /* re-enable writes */
2380 spin_lock_irq(&conf->device_lock);
2381 conf->quiesce = 0;
2382 wake_up(&conf->wait_for_stripe);
2383 spin_unlock_irq(&conf->device_lock);
2384 break;
2385 }
2386 }
2387
2388 static struct mdk_personality raid6_personality =
2389 {
2390 .name = "raid6",
2391 .level = 6,
2392 .owner = THIS_MODULE,
2393 .make_request = make_request,
2394 .run = run,
2395 .stop = stop,
2396 .status = status,
2397 .error_handler = error,
2398 .hot_add_disk = raid6_add_disk,
2399 .hot_remove_disk= raid6_remove_disk,
2400 .spare_active = raid6_spare_active,
2401 .sync_request = sync_request,
2402 .resize = raid6_resize,
2403 .quiesce = raid6_quiesce,
2404 };
2405
2406 static int __init raid6_init(void)
2407 {
2408 int e;
2409
2410 e = raid6_select_algo();
2411 if ( e )
2412 return e;
2413
2414 return register_md_personality(&raid6_personality);
2415 }
2416
2417 static void raid6_exit (void)
2418 {
2419 unregister_md_personality(&raid6_personality);
2420 }
2421
2422 module_init(raid6_init);
2423 module_exit(raid6_exit);
2424 MODULE_LICENSE("GPL");
2425 MODULE_ALIAS("md-personality-8"); /* RAID6 */
2426 MODULE_ALIAS("md-raid6");
2427 MODULE_ALIAS("md-level-6");
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