dbae459fb02d7171291e1d8dcc3d7fa538ab02f4
[linux-3.10.git] / drivers / md / raid5.c
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  *         Copyright (C) 2002, 2003 H. Peter Anvin
6  *
7  * RAID-4/5/6 management functions.
8  * Thanks to Penguin Computing for making the RAID-6 development possible
9  * by donating a test server!
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20
21 /*
22  * BITMAP UNPLUGGING:
23  *
24  * The sequencing for updating the bitmap reliably is a little
25  * subtle (and I got it wrong the first time) so it deserves some
26  * explanation.
27  *
28  * We group bitmap updates into batches.  Each batch has a number.
29  * We may write out several batches at once, but that isn't very important.
30  * conf->seq_write is the number of the last batch successfully written.
31  * conf->seq_flush is the number of the last batch that was closed to
32  *    new additions.
33  * When we discover that we will need to write to any block in a stripe
34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35  * the number of the batch it will be in. This is seq_flush+1.
36  * When we are ready to do a write, if that batch hasn't been written yet,
37  *   we plug the array and queue the stripe for later.
38  * When an unplug happens, we increment bm_flush, thus closing the current
39  *   batch.
40  * When we notice that bm_flush > bm_write, we write out all pending updates
41  * to the bitmap, and advance bm_write to where bm_flush was.
42  * This may occasionally write a bit out twice, but is sure never to
43  * miss any bits.
44  */
45
46 #include <linux/blkdev.h>
47 #include <linux/kthread.h>
48 #include <linux/raid/pq.h>
49 #include <linux/async_tx.h>
50 #include <linux/async.h>
51 #include <linux/seq_file.h>
52 #include <linux/cpu.h>
53 #include <linux/slab.h>
54 #include <linux/ratelimit.h>
55 #include "md.h"
56 #include "raid5.h"
57 #include "raid0.h"
58 #include "bitmap.h"
59
60 /*
61  * Stripe cache
62  */
63
64 #define NR_STRIPES              256
65 #define STRIPE_SIZE             PAGE_SIZE
66 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
67 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
68 #define IO_THRESHOLD            1
69 #define BYPASS_THRESHOLD        1
70 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
71 #define HASH_MASK               (NR_HASH - 1)
72
73 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
74
75 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
76  * order without overlap.  There may be several bio's per stripe+device, and
77  * a bio could span several devices.
78  * When walking this list for a particular stripe+device, we must never proceed
79  * beyond a bio that extends past this device, as the next bio might no longer
80  * be valid.
81  * This macro is used to determine the 'next' bio in the list, given the sector
82  * of the current stripe+device
83  */
84 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
85 /*
86  * The following can be used to debug the driver
87  */
88 #define RAID5_PARANOIA  1
89 #if RAID5_PARANOIA && defined(CONFIG_SMP)
90 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
91 #else
92 # define CHECK_DEVLOCK()
93 #endif
94
95 #ifdef DEBUG
96 #define inline
97 #define __inline__
98 #endif
99
100 /*
101  * We maintain a biased count of active stripes in the bottom 16 bits of
102  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
103  */
104 static inline int raid5_bi_phys_segments(struct bio *bio)
105 {
106         return bio->bi_phys_segments & 0xffff;
107 }
108
109 static inline int raid5_bi_hw_segments(struct bio *bio)
110 {
111         return (bio->bi_phys_segments >> 16) & 0xffff;
112 }
113
114 static inline int raid5_dec_bi_phys_segments(struct bio *bio)
115 {
116         --bio->bi_phys_segments;
117         return raid5_bi_phys_segments(bio);
118 }
119
120 static inline int raid5_dec_bi_hw_segments(struct bio *bio)
121 {
122         unsigned short val = raid5_bi_hw_segments(bio);
123
124         --val;
125         bio->bi_phys_segments = (val << 16) | raid5_bi_phys_segments(bio);
126         return val;
127 }
128
129 static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
130 {
131         bio->bi_phys_segments = raid5_bi_phys_segments(bio) | (cnt << 16);
132 }
133
134 /* Find first data disk in a raid6 stripe */
135 static inline int raid6_d0(struct stripe_head *sh)
136 {
137         if (sh->ddf_layout)
138                 /* ddf always start from first device */
139                 return 0;
140         /* md starts just after Q block */
141         if (sh->qd_idx == sh->disks - 1)
142                 return 0;
143         else
144                 return sh->qd_idx + 1;
145 }
146 static inline int raid6_next_disk(int disk, int raid_disks)
147 {
148         disk++;
149         return (disk < raid_disks) ? disk : 0;
150 }
151
152 /* When walking through the disks in a raid5, starting at raid6_d0,
153  * We need to map each disk to a 'slot', where the data disks are slot
154  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
155  * is raid_disks-1.  This help does that mapping.
156  */
157 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
158                              int *count, int syndrome_disks)
159 {
160         int slot = *count;
161
162         if (sh->ddf_layout)
163                 (*count)++;
164         if (idx == sh->pd_idx)
165                 return syndrome_disks;
166         if (idx == sh->qd_idx)
167                 return syndrome_disks + 1;
168         if (!sh->ddf_layout)
169                 (*count)++;
170         return slot;
171 }
172
173 static void return_io(struct bio *return_bi)
174 {
175         struct bio *bi = return_bi;
176         while (bi) {
177
178                 return_bi = bi->bi_next;
179                 bi->bi_next = NULL;
180                 bi->bi_size = 0;
181                 bio_endio(bi, 0);
182                 bi = return_bi;
183         }
184 }
185
186 static void print_raid5_conf (raid5_conf_t *conf);
187
188 static int stripe_operations_active(struct stripe_head *sh)
189 {
190         return sh->check_state || sh->reconstruct_state ||
191                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
192                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
193 }
194
195 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
196 {
197         if (atomic_dec_and_test(&sh->count)) {
198                 BUG_ON(!list_empty(&sh->lru));
199                 BUG_ON(atomic_read(&conf->active_stripes)==0);
200                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
201                         if (test_bit(STRIPE_DELAYED, &sh->state))
202                                 list_add_tail(&sh->lru, &conf->delayed_list);
203                         else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
204                                    sh->bm_seq - conf->seq_write > 0)
205                                 list_add_tail(&sh->lru, &conf->bitmap_list);
206                         else {
207                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
208                                 list_add_tail(&sh->lru, &conf->handle_list);
209                         }
210                         md_wakeup_thread(conf->mddev->thread);
211                 } else {
212                         BUG_ON(stripe_operations_active(sh));
213                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
214                                 atomic_dec(&conf->preread_active_stripes);
215                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
216                                         md_wakeup_thread(conf->mddev->thread);
217                         }
218                         atomic_dec(&conf->active_stripes);
219                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
220                                 list_add_tail(&sh->lru, &conf->inactive_list);
221                                 wake_up(&conf->wait_for_stripe);
222                                 if (conf->retry_read_aligned)
223                                         md_wakeup_thread(conf->mddev->thread);
224                         }
225                 }
226         }
227 }
228
229 static void release_stripe(struct stripe_head *sh)
230 {
231         raid5_conf_t *conf = sh->raid_conf;
232         unsigned long flags;
233
234         spin_lock_irqsave(&conf->device_lock, flags);
235         __release_stripe(conf, sh);
236         spin_unlock_irqrestore(&conf->device_lock, flags);
237 }
238
239 static inline void remove_hash(struct stripe_head *sh)
240 {
241         pr_debug("remove_hash(), stripe %llu\n",
242                 (unsigned long long)sh->sector);
243
244         hlist_del_init(&sh->hash);
245 }
246
247 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
248 {
249         struct hlist_head *hp = stripe_hash(conf, sh->sector);
250
251         pr_debug("insert_hash(), stripe %llu\n",
252                 (unsigned long long)sh->sector);
253
254         CHECK_DEVLOCK();
255         hlist_add_head(&sh->hash, hp);
256 }
257
258
259 /* find an idle stripe, make sure it is unhashed, and return it. */
260 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
261 {
262         struct stripe_head *sh = NULL;
263         struct list_head *first;
264
265         CHECK_DEVLOCK();
266         if (list_empty(&conf->inactive_list))
267                 goto out;
268         first = conf->inactive_list.next;
269         sh = list_entry(first, struct stripe_head, lru);
270         list_del_init(first);
271         remove_hash(sh);
272         atomic_inc(&conf->active_stripes);
273 out:
274         return sh;
275 }
276
277 static void shrink_buffers(struct stripe_head *sh)
278 {
279         struct page *p;
280         int i;
281         int num = sh->raid_conf->pool_size;
282
283         for (i = 0; i < num ; i++) {
284                 p = sh->dev[i].page;
285                 if (!p)
286                         continue;
287                 sh->dev[i].page = NULL;
288                 put_page(p);
289         }
290 }
291
292 static int grow_buffers(struct stripe_head *sh)
293 {
294         int i;
295         int num = sh->raid_conf->pool_size;
296
297         for (i = 0; i < num; i++) {
298                 struct page *page;
299
300                 if (!(page = alloc_page(GFP_KERNEL))) {
301                         return 1;
302                 }
303                 sh->dev[i].page = page;
304         }
305         return 0;
306 }
307
308 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
309 static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
310                             struct stripe_head *sh);
311
312 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
313 {
314         raid5_conf_t *conf = sh->raid_conf;
315         int i;
316
317         BUG_ON(atomic_read(&sh->count) != 0);
318         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
319         BUG_ON(stripe_operations_active(sh));
320
321         CHECK_DEVLOCK();
322         pr_debug("init_stripe called, stripe %llu\n",
323                 (unsigned long long)sh->sector);
324
325         remove_hash(sh);
326
327         sh->generation = conf->generation - previous;
328         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
329         sh->sector = sector;
330         stripe_set_idx(sector, conf, previous, sh);
331         sh->state = 0;
332
333
334         for (i = sh->disks; i--; ) {
335                 struct r5dev *dev = &sh->dev[i];
336
337                 if (dev->toread || dev->read || dev->towrite || dev->written ||
338                     test_bit(R5_LOCKED, &dev->flags)) {
339                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
340                                (unsigned long long)sh->sector, i, dev->toread,
341                                dev->read, dev->towrite, dev->written,
342                                test_bit(R5_LOCKED, &dev->flags));
343                         WARN_ON(1);
344                 }
345                 dev->flags = 0;
346                 raid5_build_block(sh, i, previous);
347         }
348         insert_hash(conf, sh);
349 }
350
351 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector,
352                                          short generation)
353 {
354         struct stripe_head *sh;
355         struct hlist_node *hn;
356
357         CHECK_DEVLOCK();
358         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
359         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
360                 if (sh->sector == sector && sh->generation == generation)
361                         return sh;
362         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
363         return NULL;
364 }
365
366 /*
367  * Need to check if array has failed when deciding whether to:
368  *  - start an array
369  *  - remove non-faulty devices
370  *  - add a spare
371  *  - allow a reshape
372  * This determination is simple when no reshape is happening.
373  * However if there is a reshape, we need to carefully check
374  * both the before and after sections.
375  * This is because some failed devices may only affect one
376  * of the two sections, and some non-in_sync devices may
377  * be insync in the section most affected by failed devices.
378  */
379 static int has_failed(raid5_conf_t *conf)
380 {
381         int degraded;
382         int i;
383         if (conf->mddev->reshape_position == MaxSector)
384                 return conf->mddev->degraded > conf->max_degraded;
385
386         rcu_read_lock();
387         degraded = 0;
388         for (i = 0; i < conf->previous_raid_disks; i++) {
389                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
390                 if (!rdev || test_bit(Faulty, &rdev->flags))
391                         degraded++;
392                 else if (test_bit(In_sync, &rdev->flags))
393                         ;
394                 else
395                         /* not in-sync or faulty.
396                          * If the reshape increases the number of devices,
397                          * this is being recovered by the reshape, so
398                          * this 'previous' section is not in_sync.
399                          * If the number of devices is being reduced however,
400                          * the device can only be part of the array if
401                          * we are reverting a reshape, so this section will
402                          * be in-sync.
403                          */
404                         if (conf->raid_disks >= conf->previous_raid_disks)
405                                 degraded++;
406         }
407         rcu_read_unlock();
408         if (degraded > conf->max_degraded)
409                 return 1;
410         rcu_read_lock();
411         degraded = 0;
412         for (i = 0; i < conf->raid_disks; i++) {
413                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
414                 if (!rdev || test_bit(Faulty, &rdev->flags))
415                         degraded++;
416                 else if (test_bit(In_sync, &rdev->flags))
417                         ;
418                 else
419                         /* not in-sync or faulty.
420                          * If reshape increases the number of devices, this
421                          * section has already been recovered, else it
422                          * almost certainly hasn't.
423                          */
424                         if (conf->raid_disks <= conf->previous_raid_disks)
425                                 degraded++;
426         }
427         rcu_read_unlock();
428         if (degraded > conf->max_degraded)
429                 return 1;
430         return 0;
431 }
432
433 static struct stripe_head *
434 get_active_stripe(raid5_conf_t *conf, sector_t sector,
435                   int previous, int noblock, int noquiesce)
436 {
437         struct stripe_head *sh;
438
439         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
440
441         spin_lock_irq(&conf->device_lock);
442
443         do {
444                 wait_event_lock_irq(conf->wait_for_stripe,
445                                     conf->quiesce == 0 || noquiesce,
446                                     conf->device_lock, /* nothing */);
447                 sh = __find_stripe(conf, sector, conf->generation - previous);
448                 if (!sh) {
449                         if (!conf->inactive_blocked)
450                                 sh = get_free_stripe(conf);
451                         if (noblock && sh == NULL)
452                                 break;
453                         if (!sh) {
454                                 conf->inactive_blocked = 1;
455                                 wait_event_lock_irq(conf->wait_for_stripe,
456                                                     !list_empty(&conf->inactive_list) &&
457                                                     (atomic_read(&conf->active_stripes)
458                                                      < (conf->max_nr_stripes *3/4)
459                                                      || !conf->inactive_blocked),
460                                                     conf->device_lock,
461                                                     );
462                                 conf->inactive_blocked = 0;
463                         } else
464                                 init_stripe(sh, sector, previous);
465                 } else {
466                         if (atomic_read(&sh->count)) {
467                                 BUG_ON(!list_empty(&sh->lru)
468                                     && !test_bit(STRIPE_EXPANDING, &sh->state));
469                         } else {
470                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
471                                         atomic_inc(&conf->active_stripes);
472                                 if (list_empty(&sh->lru) &&
473                                     !test_bit(STRIPE_EXPANDING, &sh->state))
474                                         BUG();
475                                 list_del_init(&sh->lru);
476                         }
477                 }
478         } while (sh == NULL);
479
480         if (sh)
481                 atomic_inc(&sh->count);
482
483         spin_unlock_irq(&conf->device_lock);
484         return sh;
485 }
486
487 static void
488 raid5_end_read_request(struct bio *bi, int error);
489 static void
490 raid5_end_write_request(struct bio *bi, int error);
491
492 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
493 {
494         raid5_conf_t *conf = sh->raid_conf;
495         int i, disks = sh->disks;
496
497         might_sleep();
498
499         for (i = disks; i--; ) {
500                 int rw;
501                 struct bio *bi;
502                 mdk_rdev_t *rdev;
503                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
504                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
505                                 rw = WRITE_FUA;
506                         else
507                                 rw = WRITE;
508                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
509                         rw = READ;
510                 else
511                         continue;
512
513                 bi = &sh->dev[i].req;
514
515                 bi->bi_rw = rw;
516                 if (rw & WRITE)
517                         bi->bi_end_io = raid5_end_write_request;
518                 else
519                         bi->bi_end_io = raid5_end_read_request;
520
521                 rcu_read_lock();
522                 rdev = rcu_dereference(conf->disks[i].rdev);
523                 if (rdev && test_bit(Faulty, &rdev->flags))
524                         rdev = NULL;
525                 if (rdev)
526                         atomic_inc(&rdev->nr_pending);
527                 rcu_read_unlock();
528
529                 /* We have already checked bad blocks for reads.  Now
530                  * need to check for writes.
531                  */
532                 while ((rw & WRITE) && rdev &&
533                        test_bit(WriteErrorSeen, &rdev->flags)) {
534                         sector_t first_bad;
535                         int bad_sectors;
536                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
537                                               &first_bad, &bad_sectors);
538                         if (!bad)
539                                 break;
540
541                         if (bad < 0) {
542                                 set_bit(BlockedBadBlocks, &rdev->flags);
543                                 if (!conf->mddev->external &&
544                                     conf->mddev->flags) {
545                                         /* It is very unlikely, but we might
546                                          * still need to write out the
547                                          * bad block log - better give it
548                                          * a chance*/
549                                         md_check_recovery(conf->mddev);
550                                 }
551                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
552                         } else {
553                                 /* Acknowledged bad block - skip the write */
554                                 rdev_dec_pending(rdev, conf->mddev);
555                                 rdev = NULL;
556                         }
557                 }
558
559                 if (rdev) {
560                         if (s->syncing || s->expanding || s->expanded)
561                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
562
563                         set_bit(STRIPE_IO_STARTED, &sh->state);
564
565                         bi->bi_bdev = rdev->bdev;
566                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
567                                 __func__, (unsigned long long)sh->sector,
568                                 bi->bi_rw, i);
569                         atomic_inc(&sh->count);
570                         bi->bi_sector = sh->sector + rdev->data_offset;
571                         bi->bi_flags = 1 << BIO_UPTODATE;
572                         bi->bi_vcnt = 1;
573                         bi->bi_max_vecs = 1;
574                         bi->bi_idx = 0;
575                         bi->bi_io_vec = &sh->dev[i].vec;
576                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
577                         bi->bi_io_vec[0].bv_offset = 0;
578                         bi->bi_size = STRIPE_SIZE;
579                         bi->bi_next = NULL;
580                         generic_make_request(bi);
581                 } else {
582                         if (rw & WRITE)
583                                 set_bit(STRIPE_DEGRADED, &sh->state);
584                         pr_debug("skip op %ld on disc %d for sector %llu\n",
585                                 bi->bi_rw, i, (unsigned long long)sh->sector);
586                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
587                         set_bit(STRIPE_HANDLE, &sh->state);
588                 }
589         }
590 }
591
592 static struct dma_async_tx_descriptor *
593 async_copy_data(int frombio, struct bio *bio, struct page *page,
594         sector_t sector, struct dma_async_tx_descriptor *tx)
595 {
596         struct bio_vec *bvl;
597         struct page *bio_page;
598         int i;
599         int page_offset;
600         struct async_submit_ctl submit;
601         enum async_tx_flags flags = 0;
602
603         if (bio->bi_sector >= sector)
604                 page_offset = (signed)(bio->bi_sector - sector) * 512;
605         else
606                 page_offset = (signed)(sector - bio->bi_sector) * -512;
607
608         if (frombio)
609                 flags |= ASYNC_TX_FENCE;
610         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
611
612         bio_for_each_segment(bvl, bio, i) {
613                 int len = bvl->bv_len;
614                 int clen;
615                 int b_offset = 0;
616
617                 if (page_offset < 0) {
618                         b_offset = -page_offset;
619                         page_offset += b_offset;
620                         len -= b_offset;
621                 }
622
623                 if (len > 0 && page_offset + len > STRIPE_SIZE)
624                         clen = STRIPE_SIZE - page_offset;
625                 else
626                         clen = len;
627
628                 if (clen > 0) {
629                         b_offset += bvl->bv_offset;
630                         bio_page = bvl->bv_page;
631                         if (frombio)
632                                 tx = async_memcpy(page, bio_page, page_offset,
633                                                   b_offset, clen, &submit);
634                         else
635                                 tx = async_memcpy(bio_page, page, b_offset,
636                                                   page_offset, clen, &submit);
637                 }
638                 /* chain the operations */
639                 submit.depend_tx = tx;
640
641                 if (clen < len) /* hit end of page */
642                         break;
643                 page_offset +=  len;
644         }
645
646         return tx;
647 }
648
649 static void ops_complete_biofill(void *stripe_head_ref)
650 {
651         struct stripe_head *sh = stripe_head_ref;
652         struct bio *return_bi = NULL;
653         raid5_conf_t *conf = sh->raid_conf;
654         int i;
655
656         pr_debug("%s: stripe %llu\n", __func__,
657                 (unsigned long long)sh->sector);
658
659         /* clear completed biofills */
660         spin_lock_irq(&conf->device_lock);
661         for (i = sh->disks; i--; ) {
662                 struct r5dev *dev = &sh->dev[i];
663
664                 /* acknowledge completion of a biofill operation */
665                 /* and check if we need to reply to a read request,
666                  * new R5_Wantfill requests are held off until
667                  * !STRIPE_BIOFILL_RUN
668                  */
669                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
670                         struct bio *rbi, *rbi2;
671
672                         BUG_ON(!dev->read);
673                         rbi = dev->read;
674                         dev->read = NULL;
675                         while (rbi && rbi->bi_sector <
676                                 dev->sector + STRIPE_SECTORS) {
677                                 rbi2 = r5_next_bio(rbi, dev->sector);
678                                 if (!raid5_dec_bi_phys_segments(rbi)) {
679                                         rbi->bi_next = return_bi;
680                                         return_bi = rbi;
681                                 }
682                                 rbi = rbi2;
683                         }
684                 }
685         }
686         spin_unlock_irq(&conf->device_lock);
687         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
688
689         return_io(return_bi);
690
691         set_bit(STRIPE_HANDLE, &sh->state);
692         release_stripe(sh);
693 }
694
695 static void ops_run_biofill(struct stripe_head *sh)
696 {
697         struct dma_async_tx_descriptor *tx = NULL;
698         raid5_conf_t *conf = sh->raid_conf;
699         struct async_submit_ctl submit;
700         int i;
701
702         pr_debug("%s: stripe %llu\n", __func__,
703                 (unsigned long long)sh->sector);
704
705         for (i = sh->disks; i--; ) {
706                 struct r5dev *dev = &sh->dev[i];
707                 if (test_bit(R5_Wantfill, &dev->flags)) {
708                         struct bio *rbi;
709                         spin_lock_irq(&conf->device_lock);
710                         dev->read = rbi = dev->toread;
711                         dev->toread = NULL;
712                         spin_unlock_irq(&conf->device_lock);
713                         while (rbi && rbi->bi_sector <
714                                 dev->sector + STRIPE_SECTORS) {
715                                 tx = async_copy_data(0, rbi, dev->page,
716                                         dev->sector, tx);
717                                 rbi = r5_next_bio(rbi, dev->sector);
718                         }
719                 }
720         }
721
722         atomic_inc(&sh->count);
723         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
724         async_trigger_callback(&submit);
725 }
726
727 static void mark_target_uptodate(struct stripe_head *sh, int target)
728 {
729         struct r5dev *tgt;
730
731         if (target < 0)
732                 return;
733
734         tgt = &sh->dev[target];
735         set_bit(R5_UPTODATE, &tgt->flags);
736         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
737         clear_bit(R5_Wantcompute, &tgt->flags);
738 }
739
740 static void ops_complete_compute(void *stripe_head_ref)
741 {
742         struct stripe_head *sh = stripe_head_ref;
743
744         pr_debug("%s: stripe %llu\n", __func__,
745                 (unsigned long long)sh->sector);
746
747         /* mark the computed target(s) as uptodate */
748         mark_target_uptodate(sh, sh->ops.target);
749         mark_target_uptodate(sh, sh->ops.target2);
750
751         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
752         if (sh->check_state == check_state_compute_run)
753                 sh->check_state = check_state_compute_result;
754         set_bit(STRIPE_HANDLE, &sh->state);
755         release_stripe(sh);
756 }
757
758 /* return a pointer to the address conversion region of the scribble buffer */
759 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
760                                  struct raid5_percpu *percpu)
761 {
762         return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
763 }
764
765 static struct dma_async_tx_descriptor *
766 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
767 {
768         int disks = sh->disks;
769         struct page **xor_srcs = percpu->scribble;
770         int target = sh->ops.target;
771         struct r5dev *tgt = &sh->dev[target];
772         struct page *xor_dest = tgt->page;
773         int count = 0;
774         struct dma_async_tx_descriptor *tx;
775         struct async_submit_ctl submit;
776         int i;
777
778         pr_debug("%s: stripe %llu block: %d\n",
779                 __func__, (unsigned long long)sh->sector, target);
780         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
781
782         for (i = disks; i--; )
783                 if (i != target)
784                         xor_srcs[count++] = sh->dev[i].page;
785
786         atomic_inc(&sh->count);
787
788         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
789                           ops_complete_compute, sh, to_addr_conv(sh, percpu));
790         if (unlikely(count == 1))
791                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
792         else
793                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
794
795         return tx;
796 }
797
798 /* set_syndrome_sources - populate source buffers for gen_syndrome
799  * @srcs - (struct page *) array of size sh->disks
800  * @sh - stripe_head to parse
801  *
802  * Populates srcs in proper layout order for the stripe and returns the
803  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
804  * destination buffer is recorded in srcs[count] and the Q destination
805  * is recorded in srcs[count+1]].
806  */
807 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
808 {
809         int disks = sh->disks;
810         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
811         int d0_idx = raid6_d0(sh);
812         int count;
813         int i;
814
815         for (i = 0; i < disks; i++)
816                 srcs[i] = NULL;
817
818         count = 0;
819         i = d0_idx;
820         do {
821                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
822
823                 srcs[slot] = sh->dev[i].page;
824                 i = raid6_next_disk(i, disks);
825         } while (i != d0_idx);
826
827         return syndrome_disks;
828 }
829
830 static struct dma_async_tx_descriptor *
831 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
832 {
833         int disks = sh->disks;
834         struct page **blocks = percpu->scribble;
835         int target;
836         int qd_idx = sh->qd_idx;
837         struct dma_async_tx_descriptor *tx;
838         struct async_submit_ctl submit;
839         struct r5dev *tgt;
840         struct page *dest;
841         int i;
842         int count;
843
844         if (sh->ops.target < 0)
845                 target = sh->ops.target2;
846         else if (sh->ops.target2 < 0)
847                 target = sh->ops.target;
848         else
849                 /* we should only have one valid target */
850                 BUG();
851         BUG_ON(target < 0);
852         pr_debug("%s: stripe %llu block: %d\n",
853                 __func__, (unsigned long long)sh->sector, target);
854
855         tgt = &sh->dev[target];
856         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
857         dest = tgt->page;
858
859         atomic_inc(&sh->count);
860
861         if (target == qd_idx) {
862                 count = set_syndrome_sources(blocks, sh);
863                 blocks[count] = NULL; /* regenerating p is not necessary */
864                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
865                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
866                                   ops_complete_compute, sh,
867                                   to_addr_conv(sh, percpu));
868                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
869         } else {
870                 /* Compute any data- or p-drive using XOR */
871                 count = 0;
872                 for (i = disks; i-- ; ) {
873                         if (i == target || i == qd_idx)
874                                 continue;
875                         blocks[count++] = sh->dev[i].page;
876                 }
877
878                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
879                                   NULL, ops_complete_compute, sh,
880                                   to_addr_conv(sh, percpu));
881                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
882         }
883
884         return tx;
885 }
886
887 static struct dma_async_tx_descriptor *
888 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
889 {
890         int i, count, disks = sh->disks;
891         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
892         int d0_idx = raid6_d0(sh);
893         int faila = -1, failb = -1;
894         int target = sh->ops.target;
895         int target2 = sh->ops.target2;
896         struct r5dev *tgt = &sh->dev[target];
897         struct r5dev *tgt2 = &sh->dev[target2];
898         struct dma_async_tx_descriptor *tx;
899         struct page **blocks = percpu->scribble;
900         struct async_submit_ctl submit;
901
902         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
903                  __func__, (unsigned long long)sh->sector, target, target2);
904         BUG_ON(target < 0 || target2 < 0);
905         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
906         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
907
908         /* we need to open-code set_syndrome_sources to handle the
909          * slot number conversion for 'faila' and 'failb'
910          */
911         for (i = 0; i < disks ; i++)
912                 blocks[i] = NULL;
913         count = 0;
914         i = d0_idx;
915         do {
916                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
917
918                 blocks[slot] = sh->dev[i].page;
919
920                 if (i == target)
921                         faila = slot;
922                 if (i == target2)
923                         failb = slot;
924                 i = raid6_next_disk(i, disks);
925         } while (i != d0_idx);
926
927         BUG_ON(faila == failb);
928         if (failb < faila)
929                 swap(faila, failb);
930         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
931                  __func__, (unsigned long long)sh->sector, faila, failb);
932
933         atomic_inc(&sh->count);
934
935         if (failb == syndrome_disks+1) {
936                 /* Q disk is one of the missing disks */
937                 if (faila == syndrome_disks) {
938                         /* Missing P+Q, just recompute */
939                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
940                                           ops_complete_compute, sh,
941                                           to_addr_conv(sh, percpu));
942                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
943                                                   STRIPE_SIZE, &submit);
944                 } else {
945                         struct page *dest;
946                         int data_target;
947                         int qd_idx = sh->qd_idx;
948
949                         /* Missing D+Q: recompute D from P, then recompute Q */
950                         if (target == qd_idx)
951                                 data_target = target2;
952                         else
953                                 data_target = target;
954
955                         count = 0;
956                         for (i = disks; i-- ; ) {
957                                 if (i == data_target || i == qd_idx)
958                                         continue;
959                                 blocks[count++] = sh->dev[i].page;
960                         }
961                         dest = sh->dev[data_target].page;
962                         init_async_submit(&submit,
963                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
964                                           NULL, NULL, NULL,
965                                           to_addr_conv(sh, percpu));
966                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
967                                        &submit);
968
969                         count = set_syndrome_sources(blocks, sh);
970                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
971                                           ops_complete_compute, sh,
972                                           to_addr_conv(sh, percpu));
973                         return async_gen_syndrome(blocks, 0, count+2,
974                                                   STRIPE_SIZE, &submit);
975                 }
976         } else {
977                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
978                                   ops_complete_compute, sh,
979                                   to_addr_conv(sh, percpu));
980                 if (failb == syndrome_disks) {
981                         /* We're missing D+P. */
982                         return async_raid6_datap_recov(syndrome_disks+2,
983                                                        STRIPE_SIZE, faila,
984                                                        blocks, &submit);
985                 } else {
986                         /* We're missing D+D. */
987                         return async_raid6_2data_recov(syndrome_disks+2,
988                                                        STRIPE_SIZE, faila, failb,
989                                                        blocks, &submit);
990                 }
991         }
992 }
993
994
995 static void ops_complete_prexor(void *stripe_head_ref)
996 {
997         struct stripe_head *sh = stripe_head_ref;
998
999         pr_debug("%s: stripe %llu\n", __func__,
1000                 (unsigned long long)sh->sector);
1001 }
1002
1003 static struct dma_async_tx_descriptor *
1004 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1005                struct dma_async_tx_descriptor *tx)
1006 {
1007         int disks = sh->disks;
1008         struct page **xor_srcs = percpu->scribble;
1009         int count = 0, pd_idx = sh->pd_idx, i;
1010         struct async_submit_ctl submit;
1011
1012         /* existing parity data subtracted */
1013         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1014
1015         pr_debug("%s: stripe %llu\n", __func__,
1016                 (unsigned long long)sh->sector);
1017
1018         for (i = disks; i--; ) {
1019                 struct r5dev *dev = &sh->dev[i];
1020                 /* Only process blocks that are known to be uptodate */
1021                 if (test_bit(R5_Wantdrain, &dev->flags))
1022                         xor_srcs[count++] = dev->page;
1023         }
1024
1025         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1026                           ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1027         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1028
1029         return tx;
1030 }
1031
1032 static struct dma_async_tx_descriptor *
1033 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1034 {
1035         int disks = sh->disks;
1036         int i;
1037
1038         pr_debug("%s: stripe %llu\n", __func__,
1039                 (unsigned long long)sh->sector);
1040
1041         for (i = disks; i--; ) {
1042                 struct r5dev *dev = &sh->dev[i];
1043                 struct bio *chosen;
1044
1045                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1046                         struct bio *wbi;
1047
1048                         spin_lock_irq(&sh->raid_conf->device_lock);
1049                         chosen = dev->towrite;
1050                         dev->towrite = NULL;
1051                         BUG_ON(dev->written);
1052                         wbi = dev->written = chosen;
1053                         spin_unlock_irq(&sh->raid_conf->device_lock);
1054
1055                         while (wbi && wbi->bi_sector <
1056                                 dev->sector + STRIPE_SECTORS) {
1057                                 if (wbi->bi_rw & REQ_FUA)
1058                                         set_bit(R5_WantFUA, &dev->flags);
1059                                 tx = async_copy_data(1, wbi, dev->page,
1060                                         dev->sector, tx);
1061                                 wbi = r5_next_bio(wbi, dev->sector);
1062                         }
1063                 }
1064         }
1065
1066         return tx;
1067 }
1068
1069 static void ops_complete_reconstruct(void *stripe_head_ref)
1070 {
1071         struct stripe_head *sh = stripe_head_ref;
1072         int disks = sh->disks;
1073         int pd_idx = sh->pd_idx;
1074         int qd_idx = sh->qd_idx;
1075         int i;
1076         bool fua = false;
1077
1078         pr_debug("%s: stripe %llu\n", __func__,
1079                 (unsigned long long)sh->sector);
1080
1081         for (i = disks; i--; )
1082                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1083
1084         for (i = disks; i--; ) {
1085                 struct r5dev *dev = &sh->dev[i];
1086
1087                 if (dev->written || i == pd_idx || i == qd_idx) {
1088                         set_bit(R5_UPTODATE, &dev->flags);
1089                         if (fua)
1090                                 set_bit(R5_WantFUA, &dev->flags);
1091                 }
1092         }
1093
1094         if (sh->reconstruct_state == reconstruct_state_drain_run)
1095                 sh->reconstruct_state = reconstruct_state_drain_result;
1096         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1097                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1098         else {
1099                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1100                 sh->reconstruct_state = reconstruct_state_result;
1101         }
1102
1103         set_bit(STRIPE_HANDLE, &sh->state);
1104         release_stripe(sh);
1105 }
1106
1107 static void
1108 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1109                      struct dma_async_tx_descriptor *tx)
1110 {
1111         int disks = sh->disks;
1112         struct page **xor_srcs = percpu->scribble;
1113         struct async_submit_ctl submit;
1114         int count = 0, pd_idx = sh->pd_idx, i;
1115         struct page *xor_dest;
1116         int prexor = 0;
1117         unsigned long flags;
1118
1119         pr_debug("%s: stripe %llu\n", __func__,
1120                 (unsigned long long)sh->sector);
1121
1122         /* check if prexor is active which means only process blocks
1123          * that are part of a read-modify-write (written)
1124          */
1125         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1126                 prexor = 1;
1127                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1128                 for (i = disks; i--; ) {
1129                         struct r5dev *dev = &sh->dev[i];
1130                         if (dev->written)
1131                                 xor_srcs[count++] = dev->page;
1132                 }
1133         } else {
1134                 xor_dest = sh->dev[pd_idx].page;
1135                 for (i = disks; i--; ) {
1136                         struct r5dev *dev = &sh->dev[i];
1137                         if (i != pd_idx)
1138                                 xor_srcs[count++] = dev->page;
1139                 }
1140         }
1141
1142         /* 1/ if we prexor'd then the dest is reused as a source
1143          * 2/ if we did not prexor then we are redoing the parity
1144          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1145          * for the synchronous xor case
1146          */
1147         flags = ASYNC_TX_ACK |
1148                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1149
1150         atomic_inc(&sh->count);
1151
1152         init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1153                           to_addr_conv(sh, percpu));
1154         if (unlikely(count == 1))
1155                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1156         else
1157                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1158 }
1159
1160 static void
1161 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1162                      struct dma_async_tx_descriptor *tx)
1163 {
1164         struct async_submit_ctl submit;
1165         struct page **blocks = percpu->scribble;
1166         int count;
1167
1168         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1169
1170         count = set_syndrome_sources(blocks, sh);
1171
1172         atomic_inc(&sh->count);
1173
1174         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1175                           sh, to_addr_conv(sh, percpu));
1176         async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1177 }
1178
1179 static void ops_complete_check(void *stripe_head_ref)
1180 {
1181         struct stripe_head *sh = stripe_head_ref;
1182
1183         pr_debug("%s: stripe %llu\n", __func__,
1184                 (unsigned long long)sh->sector);
1185
1186         sh->check_state = check_state_check_result;
1187         set_bit(STRIPE_HANDLE, &sh->state);
1188         release_stripe(sh);
1189 }
1190
1191 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1192 {
1193         int disks = sh->disks;
1194         int pd_idx = sh->pd_idx;
1195         int qd_idx = sh->qd_idx;
1196         struct page *xor_dest;
1197         struct page **xor_srcs = percpu->scribble;
1198         struct dma_async_tx_descriptor *tx;
1199         struct async_submit_ctl submit;
1200         int count;
1201         int i;
1202
1203         pr_debug("%s: stripe %llu\n", __func__,
1204                 (unsigned long long)sh->sector);
1205
1206         count = 0;
1207         xor_dest = sh->dev[pd_idx].page;
1208         xor_srcs[count++] = xor_dest;
1209         for (i = disks; i--; ) {
1210                 if (i == pd_idx || i == qd_idx)
1211                         continue;
1212                 xor_srcs[count++] = sh->dev[i].page;
1213         }
1214
1215         init_async_submit(&submit, 0, NULL, NULL, NULL,
1216                           to_addr_conv(sh, percpu));
1217         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1218                            &sh->ops.zero_sum_result, &submit);
1219
1220         atomic_inc(&sh->count);
1221         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1222         tx = async_trigger_callback(&submit);
1223 }
1224
1225 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1226 {
1227         struct page **srcs = percpu->scribble;
1228         struct async_submit_ctl submit;
1229         int count;
1230
1231         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1232                 (unsigned long long)sh->sector, checkp);
1233
1234         count = set_syndrome_sources(srcs, sh);
1235         if (!checkp)
1236                 srcs[count] = NULL;
1237
1238         atomic_inc(&sh->count);
1239         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1240                           sh, to_addr_conv(sh, percpu));
1241         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1242                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1243 }
1244
1245 static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1246 {
1247         int overlap_clear = 0, i, disks = sh->disks;
1248         struct dma_async_tx_descriptor *tx = NULL;
1249         raid5_conf_t *conf = sh->raid_conf;
1250         int level = conf->level;
1251         struct raid5_percpu *percpu;
1252         unsigned long cpu;
1253
1254         cpu = get_cpu();
1255         percpu = per_cpu_ptr(conf->percpu, cpu);
1256         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1257                 ops_run_biofill(sh);
1258                 overlap_clear++;
1259         }
1260
1261         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1262                 if (level < 6)
1263                         tx = ops_run_compute5(sh, percpu);
1264                 else {
1265                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1266                                 tx = ops_run_compute6_1(sh, percpu);
1267                         else
1268                                 tx = ops_run_compute6_2(sh, percpu);
1269                 }
1270                 /* terminate the chain if reconstruct is not set to be run */
1271                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1272                         async_tx_ack(tx);
1273         }
1274
1275         if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1276                 tx = ops_run_prexor(sh, percpu, tx);
1277
1278         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1279                 tx = ops_run_biodrain(sh, tx);
1280                 overlap_clear++;
1281         }
1282
1283         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1284                 if (level < 6)
1285                         ops_run_reconstruct5(sh, percpu, tx);
1286                 else
1287                         ops_run_reconstruct6(sh, percpu, tx);
1288         }
1289
1290         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1291                 if (sh->check_state == check_state_run)
1292                         ops_run_check_p(sh, percpu);
1293                 else if (sh->check_state == check_state_run_q)
1294                         ops_run_check_pq(sh, percpu, 0);
1295                 else if (sh->check_state == check_state_run_pq)
1296                         ops_run_check_pq(sh, percpu, 1);
1297                 else
1298                         BUG();
1299         }
1300
1301         if (overlap_clear)
1302                 for (i = disks; i--; ) {
1303                         struct r5dev *dev = &sh->dev[i];
1304                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1305                                 wake_up(&sh->raid_conf->wait_for_overlap);
1306                 }
1307         put_cpu();
1308 }
1309
1310 #ifdef CONFIG_MULTICORE_RAID456
1311 static void async_run_ops(void *param, async_cookie_t cookie)
1312 {
1313         struct stripe_head *sh = param;
1314         unsigned long ops_request = sh->ops.request;
1315
1316         clear_bit_unlock(STRIPE_OPS_REQ_PENDING, &sh->state);
1317         wake_up(&sh->ops.wait_for_ops);
1318
1319         __raid_run_ops(sh, ops_request);
1320         release_stripe(sh);
1321 }
1322
1323 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1324 {
1325         /* since handle_stripe can be called outside of raid5d context
1326          * we need to ensure sh->ops.request is de-staged before another
1327          * request arrives
1328          */
1329         wait_event(sh->ops.wait_for_ops,
1330                    !test_and_set_bit_lock(STRIPE_OPS_REQ_PENDING, &sh->state));
1331         sh->ops.request = ops_request;
1332
1333         atomic_inc(&sh->count);
1334         async_schedule(async_run_ops, sh);
1335 }
1336 #else
1337 #define raid_run_ops __raid_run_ops
1338 #endif
1339
1340 static int grow_one_stripe(raid5_conf_t *conf)
1341 {
1342         struct stripe_head *sh;
1343         sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1344         if (!sh)
1345                 return 0;
1346
1347         sh->raid_conf = conf;
1348         #ifdef CONFIG_MULTICORE_RAID456
1349         init_waitqueue_head(&sh->ops.wait_for_ops);
1350         #endif
1351
1352         if (grow_buffers(sh)) {
1353                 shrink_buffers(sh);
1354                 kmem_cache_free(conf->slab_cache, sh);
1355                 return 0;
1356         }
1357         /* we just created an active stripe so... */
1358         atomic_set(&sh->count, 1);
1359         atomic_inc(&conf->active_stripes);
1360         INIT_LIST_HEAD(&sh->lru);
1361         release_stripe(sh);
1362         return 1;
1363 }
1364
1365 static int grow_stripes(raid5_conf_t *conf, int num)
1366 {
1367         struct kmem_cache *sc;
1368         int devs = max(conf->raid_disks, conf->previous_raid_disks);
1369
1370         if (conf->mddev->gendisk)
1371                 sprintf(conf->cache_name[0],
1372                         "raid%d-%s", conf->level, mdname(conf->mddev));
1373         else
1374                 sprintf(conf->cache_name[0],
1375                         "raid%d-%p", conf->level, conf->mddev);
1376         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1377
1378         conf->active_name = 0;
1379         sc = kmem_cache_create(conf->cache_name[conf->active_name],
1380                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1381                                0, 0, NULL);
1382         if (!sc)
1383                 return 1;
1384         conf->slab_cache = sc;
1385         conf->pool_size = devs;
1386         while (num--)
1387                 if (!grow_one_stripe(conf))
1388                         return 1;
1389         return 0;
1390 }
1391
1392 /**
1393  * scribble_len - return the required size of the scribble region
1394  * @num - total number of disks in the array
1395  *
1396  * The size must be enough to contain:
1397  * 1/ a struct page pointer for each device in the array +2
1398  * 2/ room to convert each entry in (1) to its corresponding dma
1399  *    (dma_map_page()) or page (page_address()) address.
1400  *
1401  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1402  * calculate over all devices (not just the data blocks), using zeros in place
1403  * of the P and Q blocks.
1404  */
1405 static size_t scribble_len(int num)
1406 {
1407         size_t len;
1408
1409         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1410
1411         return len;
1412 }
1413
1414 static int resize_stripes(raid5_conf_t *conf, int newsize)
1415 {
1416         /* Make all the stripes able to hold 'newsize' devices.
1417          * New slots in each stripe get 'page' set to a new page.
1418          *
1419          * This happens in stages:
1420          * 1/ create a new kmem_cache and allocate the required number of
1421          *    stripe_heads.
1422          * 2/ gather all the old stripe_heads and tranfer the pages across
1423          *    to the new stripe_heads.  This will have the side effect of
1424          *    freezing the array as once all stripe_heads have been collected,
1425          *    no IO will be possible.  Old stripe heads are freed once their
1426          *    pages have been transferred over, and the old kmem_cache is
1427          *    freed when all stripes are done.
1428          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1429          *    we simple return a failre status - no need to clean anything up.
1430          * 4/ allocate new pages for the new slots in the new stripe_heads.
1431          *    If this fails, we don't bother trying the shrink the
1432          *    stripe_heads down again, we just leave them as they are.
1433          *    As each stripe_head is processed the new one is released into
1434          *    active service.
1435          *
1436          * Once step2 is started, we cannot afford to wait for a write,
1437          * so we use GFP_NOIO allocations.
1438          */
1439         struct stripe_head *osh, *nsh;
1440         LIST_HEAD(newstripes);
1441         struct disk_info *ndisks;
1442         unsigned long cpu;
1443         int err;
1444         struct kmem_cache *sc;
1445         int i;
1446
1447         if (newsize <= conf->pool_size)
1448                 return 0; /* never bother to shrink */
1449
1450         err = md_allow_write(conf->mddev);
1451         if (err)
1452                 return err;
1453
1454         /* Step 1 */
1455         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1456                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1457                                0, 0, NULL);
1458         if (!sc)
1459                 return -ENOMEM;
1460
1461         for (i = conf->max_nr_stripes; i; i--) {
1462                 nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1463                 if (!nsh)
1464                         break;
1465
1466                 nsh->raid_conf = conf;
1467                 #ifdef CONFIG_MULTICORE_RAID456
1468                 init_waitqueue_head(&nsh->ops.wait_for_ops);
1469                 #endif
1470
1471                 list_add(&nsh->lru, &newstripes);
1472         }
1473         if (i) {
1474                 /* didn't get enough, give up */
1475                 while (!list_empty(&newstripes)) {
1476                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1477                         list_del(&nsh->lru);
1478                         kmem_cache_free(sc, nsh);
1479                 }
1480                 kmem_cache_destroy(sc);
1481                 return -ENOMEM;
1482         }
1483         /* Step 2 - Must use GFP_NOIO now.
1484          * OK, we have enough stripes, start collecting inactive
1485          * stripes and copying them over
1486          */
1487         list_for_each_entry(nsh, &newstripes, lru) {
1488                 spin_lock_irq(&conf->device_lock);
1489                 wait_event_lock_irq(conf->wait_for_stripe,
1490                                     !list_empty(&conf->inactive_list),
1491                                     conf->device_lock,
1492                                     );
1493                 osh = get_free_stripe(conf);
1494                 spin_unlock_irq(&conf->device_lock);
1495                 atomic_set(&nsh->count, 1);
1496                 for(i=0; i<conf->pool_size; i++)
1497                         nsh->dev[i].page = osh->dev[i].page;
1498                 for( ; i<newsize; i++)
1499                         nsh->dev[i].page = NULL;
1500                 kmem_cache_free(conf->slab_cache, osh);
1501         }
1502         kmem_cache_destroy(conf->slab_cache);
1503
1504         /* Step 3.
1505          * At this point, we are holding all the stripes so the array
1506          * is completely stalled, so now is a good time to resize
1507          * conf->disks and the scribble region
1508          */
1509         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1510         if (ndisks) {
1511                 for (i=0; i<conf->raid_disks; i++)
1512                         ndisks[i] = conf->disks[i];
1513                 kfree(conf->disks);
1514                 conf->disks = ndisks;
1515         } else
1516                 err = -ENOMEM;
1517
1518         get_online_cpus();
1519         conf->scribble_len = scribble_len(newsize);
1520         for_each_present_cpu(cpu) {
1521                 struct raid5_percpu *percpu;
1522                 void *scribble;
1523
1524                 percpu = per_cpu_ptr(conf->percpu, cpu);
1525                 scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1526
1527                 if (scribble) {
1528                         kfree(percpu->scribble);
1529                         percpu->scribble = scribble;
1530                 } else {
1531                         err = -ENOMEM;
1532                         break;
1533                 }
1534         }
1535         put_online_cpus();
1536
1537         /* Step 4, return new stripes to service */
1538         while(!list_empty(&newstripes)) {
1539                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1540                 list_del_init(&nsh->lru);
1541
1542                 for (i=conf->raid_disks; i < newsize; i++)
1543                         if (nsh->dev[i].page == NULL) {
1544                                 struct page *p = alloc_page(GFP_NOIO);
1545                                 nsh->dev[i].page = p;
1546                                 if (!p)
1547                                         err = -ENOMEM;
1548                         }
1549                 release_stripe(nsh);
1550         }
1551         /* critical section pass, GFP_NOIO no longer needed */
1552
1553         conf->slab_cache = sc;
1554         conf->active_name = 1-conf->active_name;
1555         conf->pool_size = newsize;
1556         return err;
1557 }
1558
1559 static int drop_one_stripe(raid5_conf_t *conf)
1560 {
1561         struct stripe_head *sh;
1562
1563         spin_lock_irq(&conf->device_lock);
1564         sh = get_free_stripe(conf);
1565         spin_unlock_irq(&conf->device_lock);
1566         if (!sh)
1567                 return 0;
1568         BUG_ON(atomic_read(&sh->count));
1569         shrink_buffers(sh);
1570         kmem_cache_free(conf->slab_cache, sh);
1571         atomic_dec(&conf->active_stripes);
1572         return 1;
1573 }
1574
1575 static void shrink_stripes(raid5_conf_t *conf)
1576 {
1577         while (drop_one_stripe(conf))
1578                 ;
1579
1580         if (conf->slab_cache)
1581                 kmem_cache_destroy(conf->slab_cache);
1582         conf->slab_cache = NULL;
1583 }
1584
1585 static void raid5_end_read_request(struct bio * bi, int error)
1586 {
1587         struct stripe_head *sh = bi->bi_private;
1588         raid5_conf_t *conf = sh->raid_conf;
1589         int disks = sh->disks, i;
1590         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1591         char b[BDEVNAME_SIZE];
1592         mdk_rdev_t *rdev;
1593
1594
1595         for (i=0 ; i<disks; i++)
1596                 if (bi == &sh->dev[i].req)
1597                         break;
1598
1599         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1600                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1601                 uptodate);
1602         if (i == disks) {
1603                 BUG();
1604                 return;
1605         }
1606
1607         if (uptodate) {
1608                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1609                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1610                         rdev = conf->disks[i].rdev;
1611                         printk_ratelimited(
1612                                 KERN_INFO
1613                                 "md/raid:%s: read error corrected"
1614                                 " (%lu sectors at %llu on %s)\n",
1615                                 mdname(conf->mddev), STRIPE_SECTORS,
1616                                 (unsigned long long)(sh->sector
1617                                                      + rdev->data_offset),
1618                                 bdevname(rdev->bdev, b));
1619                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1620                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1621                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1622                 }
1623                 if (atomic_read(&conf->disks[i].rdev->read_errors))
1624                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
1625         } else {
1626                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1627                 int retry = 0;
1628                 rdev = conf->disks[i].rdev;
1629
1630                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1631                 atomic_inc(&rdev->read_errors);
1632                 if (conf->mddev->degraded >= conf->max_degraded)
1633                         printk_ratelimited(
1634                                 KERN_WARNING
1635                                 "md/raid:%s: read error not correctable "
1636                                 "(sector %llu on %s).\n",
1637                                 mdname(conf->mddev),
1638                                 (unsigned long long)(sh->sector
1639                                                      + rdev->data_offset),
1640                                 bdn);
1641                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1642                         /* Oh, no!!! */
1643                         printk_ratelimited(
1644                                 KERN_WARNING
1645                                 "md/raid:%s: read error NOT corrected!! "
1646                                 "(sector %llu on %s).\n",
1647                                 mdname(conf->mddev),
1648                                 (unsigned long long)(sh->sector
1649                                                      + rdev->data_offset),
1650                                 bdn);
1651                 else if (atomic_read(&rdev->read_errors)
1652                          > conf->max_nr_stripes)
1653                         printk(KERN_WARNING
1654                                "md/raid:%s: Too many read errors, failing device %s.\n",
1655                                mdname(conf->mddev), bdn);
1656                 else
1657                         retry = 1;
1658                 if (retry)
1659                         set_bit(R5_ReadError, &sh->dev[i].flags);
1660                 else {
1661                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1662                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1663                         md_error(conf->mddev, rdev);
1664                 }
1665         }
1666         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1667         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1668         set_bit(STRIPE_HANDLE, &sh->state);
1669         release_stripe(sh);
1670 }
1671
1672 static void raid5_end_write_request(struct bio *bi, int error)
1673 {
1674         struct stripe_head *sh = bi->bi_private;
1675         raid5_conf_t *conf = sh->raid_conf;
1676         int disks = sh->disks, i;
1677         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1678         sector_t first_bad;
1679         int bad_sectors;
1680
1681         for (i=0 ; i<disks; i++)
1682                 if (bi == &sh->dev[i].req)
1683                         break;
1684
1685         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1686                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1687                 uptodate);
1688         if (i == disks) {
1689                 BUG();
1690                 return;
1691         }
1692
1693         if (!uptodate) {
1694                 set_bit(WriteErrorSeen, &conf->disks[i].rdev->flags);
1695                 set_bit(R5_WriteError, &sh->dev[i].flags);
1696         } else if (is_badblock(conf->disks[i].rdev, sh->sector, STRIPE_SECTORS,
1697                                &first_bad, &bad_sectors))
1698                 set_bit(R5_MadeGood, &sh->dev[i].flags);
1699
1700         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1701         
1702         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1703         set_bit(STRIPE_HANDLE, &sh->state);
1704         release_stripe(sh);
1705 }
1706
1707
1708 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1709         
1710 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1711 {
1712         struct r5dev *dev = &sh->dev[i];
1713
1714         bio_init(&dev->req);
1715         dev->req.bi_io_vec = &dev->vec;
1716         dev->req.bi_vcnt++;
1717         dev->req.bi_max_vecs++;
1718         dev->vec.bv_page = dev->page;
1719         dev->vec.bv_len = STRIPE_SIZE;
1720         dev->vec.bv_offset = 0;
1721
1722         dev->req.bi_sector = sh->sector;
1723         dev->req.bi_private = sh;
1724
1725         dev->flags = 0;
1726         dev->sector = compute_blocknr(sh, i, previous);
1727 }
1728
1729 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1730 {
1731         char b[BDEVNAME_SIZE];
1732         raid5_conf_t *conf = mddev->private;
1733         pr_debug("raid456: error called\n");
1734
1735         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1736                 unsigned long flags;
1737                 spin_lock_irqsave(&conf->device_lock, flags);
1738                 mddev->degraded++;
1739                 spin_unlock_irqrestore(&conf->device_lock, flags);
1740                 /*
1741                  * if recovery was running, make sure it aborts.
1742                  */
1743                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1744         }
1745         set_bit(Blocked, &rdev->flags);
1746         set_bit(Faulty, &rdev->flags);
1747         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1748         printk(KERN_ALERT
1749                "md/raid:%s: Disk failure on %s, disabling device.\n"
1750                "md/raid:%s: Operation continuing on %d devices.\n",
1751                mdname(mddev),
1752                bdevname(rdev->bdev, b),
1753                mdname(mddev),
1754                conf->raid_disks - mddev->degraded);
1755 }
1756
1757 /*
1758  * Input: a 'big' sector number,
1759  * Output: index of the data and parity disk, and the sector # in them.
1760  */
1761 static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
1762                                      int previous, int *dd_idx,
1763                                      struct stripe_head *sh)
1764 {
1765         sector_t stripe, stripe2;
1766         sector_t chunk_number;
1767         unsigned int chunk_offset;
1768         int pd_idx, qd_idx;
1769         int ddf_layout = 0;
1770         sector_t new_sector;
1771         int algorithm = previous ? conf->prev_algo
1772                                  : conf->algorithm;
1773         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1774                                          : conf->chunk_sectors;
1775         int raid_disks = previous ? conf->previous_raid_disks
1776                                   : conf->raid_disks;
1777         int data_disks = raid_disks - conf->max_degraded;
1778
1779         /* First compute the information on this sector */
1780
1781         /*
1782          * Compute the chunk number and the sector offset inside the chunk
1783          */
1784         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1785         chunk_number = r_sector;
1786
1787         /*
1788          * Compute the stripe number
1789          */
1790         stripe = chunk_number;
1791         *dd_idx = sector_div(stripe, data_disks);
1792         stripe2 = stripe;
1793         /*
1794          * Select the parity disk based on the user selected algorithm.
1795          */
1796         pd_idx = qd_idx = -1;
1797         switch(conf->level) {
1798         case 4:
1799                 pd_idx = data_disks;
1800                 break;
1801         case 5:
1802                 switch (algorithm) {
1803                 case ALGORITHM_LEFT_ASYMMETRIC:
1804                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
1805                         if (*dd_idx >= pd_idx)
1806                                 (*dd_idx)++;
1807                         break;
1808                 case ALGORITHM_RIGHT_ASYMMETRIC:
1809                         pd_idx = sector_div(stripe2, raid_disks);
1810                         if (*dd_idx >= pd_idx)
1811                                 (*dd_idx)++;
1812                         break;
1813                 case ALGORITHM_LEFT_SYMMETRIC:
1814                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
1815                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
1816                         break;
1817                 case ALGORITHM_RIGHT_SYMMETRIC:
1818                         pd_idx = sector_div(stripe2, raid_disks);
1819                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
1820                         break;
1821                 case ALGORITHM_PARITY_0:
1822                         pd_idx = 0;
1823                         (*dd_idx)++;
1824                         break;
1825                 case ALGORITHM_PARITY_N:
1826                         pd_idx = data_disks;
1827                         break;
1828                 default:
1829                         BUG();
1830                 }
1831                 break;
1832         case 6:
1833
1834                 switch (algorithm) {
1835                 case ALGORITHM_LEFT_ASYMMETRIC:
1836                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1837                         qd_idx = pd_idx + 1;
1838                         if (pd_idx == raid_disks-1) {
1839                                 (*dd_idx)++;    /* Q D D D P */
1840                                 qd_idx = 0;
1841                         } else if (*dd_idx >= pd_idx)
1842                                 (*dd_idx) += 2; /* D D P Q D */
1843                         break;
1844                 case ALGORITHM_RIGHT_ASYMMETRIC:
1845                         pd_idx = sector_div(stripe2, raid_disks);
1846                         qd_idx = pd_idx + 1;
1847                         if (pd_idx == raid_disks-1) {
1848                                 (*dd_idx)++;    /* Q D D D P */
1849                                 qd_idx = 0;
1850                         } else if (*dd_idx >= pd_idx)
1851                                 (*dd_idx) += 2; /* D D P Q D */
1852                         break;
1853                 case ALGORITHM_LEFT_SYMMETRIC:
1854                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1855                         qd_idx = (pd_idx + 1) % raid_disks;
1856                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
1857                         break;
1858                 case ALGORITHM_RIGHT_SYMMETRIC:
1859                         pd_idx = sector_div(stripe2, raid_disks);
1860                         qd_idx = (pd_idx + 1) % raid_disks;
1861                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
1862                         break;
1863
1864                 case ALGORITHM_PARITY_0:
1865                         pd_idx = 0;
1866                         qd_idx = 1;
1867                         (*dd_idx) += 2;
1868                         break;
1869                 case ALGORITHM_PARITY_N:
1870                         pd_idx = data_disks;
1871                         qd_idx = data_disks + 1;
1872                         break;
1873
1874                 case ALGORITHM_ROTATING_ZERO_RESTART:
1875                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
1876                          * of blocks for computing Q is different.
1877                          */
1878                         pd_idx = sector_div(stripe2, raid_disks);
1879                         qd_idx = pd_idx + 1;
1880                         if (pd_idx == raid_disks-1) {
1881                                 (*dd_idx)++;    /* Q D D D P */
1882                                 qd_idx = 0;
1883                         } else if (*dd_idx >= pd_idx)
1884                                 (*dd_idx) += 2; /* D D P Q D */
1885                         ddf_layout = 1;
1886                         break;
1887
1888                 case ALGORITHM_ROTATING_N_RESTART:
1889                         /* Same a left_asymmetric, by first stripe is
1890                          * D D D P Q  rather than
1891                          * Q D D D P
1892                          */
1893                         stripe2 += 1;
1894                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1895                         qd_idx = pd_idx + 1;
1896                         if (pd_idx == raid_disks-1) {
1897                                 (*dd_idx)++;    /* Q D D D P */
1898                                 qd_idx = 0;
1899                         } else if (*dd_idx >= pd_idx)
1900                                 (*dd_idx) += 2; /* D D P Q D */
1901                         ddf_layout = 1;
1902                         break;
1903
1904                 case ALGORITHM_ROTATING_N_CONTINUE:
1905                         /* Same as left_symmetric but Q is before P */
1906                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1907                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
1908                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
1909                         ddf_layout = 1;
1910                         break;
1911
1912                 case ALGORITHM_LEFT_ASYMMETRIC_6:
1913                         /* RAID5 left_asymmetric, with Q on last device */
1914                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
1915                         if (*dd_idx >= pd_idx)
1916                                 (*dd_idx)++;
1917                         qd_idx = raid_disks - 1;
1918                         break;
1919
1920                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
1921                         pd_idx = sector_div(stripe2, raid_disks-1);
1922                         if (*dd_idx >= pd_idx)
1923                                 (*dd_idx)++;
1924                         qd_idx = raid_disks - 1;
1925                         break;
1926
1927                 case ALGORITHM_LEFT_SYMMETRIC_6:
1928                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
1929                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
1930                         qd_idx = raid_disks - 1;
1931                         break;
1932
1933                 case ALGORITHM_RIGHT_SYMMETRIC_6:
1934                         pd_idx = sector_div(stripe2, raid_disks-1);
1935                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
1936                         qd_idx = raid_disks - 1;
1937                         break;
1938
1939                 case ALGORITHM_PARITY_0_6:
1940                         pd_idx = 0;
1941                         (*dd_idx)++;
1942                         qd_idx = raid_disks - 1;
1943                         break;
1944
1945                 default:
1946                         BUG();
1947                 }
1948                 break;
1949         }
1950
1951         if (sh) {
1952                 sh->pd_idx = pd_idx;
1953                 sh->qd_idx = qd_idx;
1954                 sh->ddf_layout = ddf_layout;
1955         }
1956         /*
1957          * Finally, compute the new sector number
1958          */
1959         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1960         return new_sector;
1961 }
1962
1963
1964 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
1965 {
1966         raid5_conf_t *conf = sh->raid_conf;
1967         int raid_disks = sh->disks;
1968         int data_disks = raid_disks - conf->max_degraded;
1969         sector_t new_sector = sh->sector, check;
1970         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1971                                          : conf->chunk_sectors;
1972         int algorithm = previous ? conf->prev_algo
1973                                  : conf->algorithm;
1974         sector_t stripe;
1975         int chunk_offset;
1976         sector_t chunk_number;
1977         int dummy1, dd_idx = i;
1978         sector_t r_sector;
1979         struct stripe_head sh2;
1980
1981
1982         chunk_offset = sector_div(new_sector, sectors_per_chunk);
1983         stripe = new_sector;
1984
1985         if (i == sh->pd_idx)
1986                 return 0;
1987         switch(conf->level) {
1988         case 4: break;
1989         case 5:
1990                 switch (algorithm) {
1991                 case ALGORITHM_LEFT_ASYMMETRIC:
1992                 case ALGORITHM_RIGHT_ASYMMETRIC:
1993                         if (i > sh->pd_idx)
1994                                 i--;
1995                         break;
1996                 case ALGORITHM_LEFT_SYMMETRIC:
1997                 case ALGORITHM_RIGHT_SYMMETRIC:
1998                         if (i < sh->pd_idx)
1999                                 i += raid_disks;
2000                         i -= (sh->pd_idx + 1);
2001                         break;
2002                 case ALGORITHM_PARITY_0:
2003                         i -= 1;
2004                         break;
2005                 case ALGORITHM_PARITY_N:
2006                         break;
2007                 default:
2008                         BUG();
2009                 }
2010                 break;
2011         case 6:
2012                 if (i == sh->qd_idx)
2013                         return 0; /* It is the Q disk */
2014                 switch (algorithm) {
2015                 case ALGORITHM_LEFT_ASYMMETRIC:
2016                 case ALGORITHM_RIGHT_ASYMMETRIC:
2017                 case ALGORITHM_ROTATING_ZERO_RESTART:
2018                 case ALGORITHM_ROTATING_N_RESTART:
2019                         if (sh->pd_idx == raid_disks-1)
2020                                 i--;    /* Q D D D P */
2021                         else if (i > sh->pd_idx)
2022                                 i -= 2; /* D D P Q D */
2023                         break;
2024                 case ALGORITHM_LEFT_SYMMETRIC:
2025                 case ALGORITHM_RIGHT_SYMMETRIC:
2026                         if (sh->pd_idx == raid_disks-1)
2027                                 i--; /* Q D D D P */
2028                         else {
2029                                 /* D D P Q D */
2030                                 if (i < sh->pd_idx)
2031                                         i += raid_disks;
2032                                 i -= (sh->pd_idx + 2);
2033                         }
2034                         break;
2035                 case ALGORITHM_PARITY_0:
2036                         i -= 2;
2037                         break;
2038                 case ALGORITHM_PARITY_N:
2039                         break;
2040                 case ALGORITHM_ROTATING_N_CONTINUE:
2041                         /* Like left_symmetric, but P is before Q */
2042                         if (sh->pd_idx == 0)
2043                                 i--;    /* P D D D Q */
2044                         else {
2045                                 /* D D Q P D */
2046                                 if (i < sh->pd_idx)
2047                                         i += raid_disks;
2048                                 i -= (sh->pd_idx + 1);
2049                         }
2050                         break;
2051                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2052                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2053                         if (i > sh->pd_idx)
2054                                 i--;
2055                         break;
2056                 case ALGORITHM_LEFT_SYMMETRIC_6:
2057                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2058                         if (i < sh->pd_idx)
2059                                 i += data_disks + 1;
2060                         i -= (sh->pd_idx + 1);
2061                         break;
2062                 case ALGORITHM_PARITY_0_6:
2063                         i -= 1;
2064                         break;
2065                 default:
2066                         BUG();
2067                 }
2068                 break;
2069         }
2070
2071         chunk_number = stripe * data_disks + i;
2072         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2073
2074         check = raid5_compute_sector(conf, r_sector,
2075                                      previous, &dummy1, &sh2);
2076         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2077                 || sh2.qd_idx != sh->qd_idx) {
2078                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2079                        mdname(conf->mddev));
2080                 return 0;
2081         }
2082         return r_sector;
2083 }
2084
2085
2086 static void
2087 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2088                          int rcw, int expand)
2089 {
2090         int i, pd_idx = sh->pd_idx, disks = sh->disks;
2091         raid5_conf_t *conf = sh->raid_conf;
2092         int level = conf->level;
2093
2094         if (rcw) {
2095                 /* if we are not expanding this is a proper write request, and
2096                  * there will be bios with new data to be drained into the
2097                  * stripe cache
2098                  */
2099                 if (!expand) {
2100                         sh->reconstruct_state = reconstruct_state_drain_run;
2101                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2102                 } else
2103                         sh->reconstruct_state = reconstruct_state_run;
2104
2105                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2106
2107                 for (i = disks; i--; ) {
2108                         struct r5dev *dev = &sh->dev[i];
2109
2110                         if (dev->towrite) {
2111                                 set_bit(R5_LOCKED, &dev->flags);
2112                                 set_bit(R5_Wantdrain, &dev->flags);
2113                                 if (!expand)
2114                                         clear_bit(R5_UPTODATE, &dev->flags);
2115                                 s->locked++;
2116                         }
2117                 }
2118                 if (s->locked + conf->max_degraded == disks)
2119                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2120                                 atomic_inc(&conf->pending_full_writes);
2121         } else {
2122                 BUG_ON(level == 6);
2123                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2124                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2125
2126                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2127                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2128                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2129                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2130
2131                 for (i = disks; i--; ) {
2132                         struct r5dev *dev = &sh->dev[i];
2133                         if (i == pd_idx)
2134                                 continue;
2135
2136                         if (dev->towrite &&
2137                             (test_bit(R5_UPTODATE, &dev->flags) ||
2138                              test_bit(R5_Wantcompute, &dev->flags))) {
2139                                 set_bit(R5_Wantdrain, &dev->flags);
2140                                 set_bit(R5_LOCKED, &dev->flags);
2141                                 clear_bit(R5_UPTODATE, &dev->flags);
2142                                 s->locked++;
2143                         }
2144                 }
2145         }
2146
2147         /* keep the parity disk(s) locked while asynchronous operations
2148          * are in flight
2149          */
2150         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2151         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2152         s->locked++;
2153
2154         if (level == 6) {
2155                 int qd_idx = sh->qd_idx;
2156                 struct r5dev *dev = &sh->dev[qd_idx];
2157
2158                 set_bit(R5_LOCKED, &dev->flags);
2159                 clear_bit(R5_UPTODATE, &dev->flags);
2160                 s->locked++;
2161         }
2162
2163         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2164                 __func__, (unsigned long long)sh->sector,
2165                 s->locked, s->ops_request);
2166 }
2167
2168 /*
2169  * Each stripe/dev can have one or more bion attached.
2170  * toread/towrite point to the first in a chain.
2171  * The bi_next chain must be in order.
2172  */
2173 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2174 {
2175         struct bio **bip;
2176         raid5_conf_t *conf = sh->raid_conf;
2177         int firstwrite=0;
2178
2179         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2180                 (unsigned long long)bi->bi_sector,
2181                 (unsigned long long)sh->sector);
2182
2183
2184         spin_lock_irq(&conf->device_lock);
2185         if (forwrite) {
2186                 bip = &sh->dev[dd_idx].towrite;
2187                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
2188                         firstwrite = 1;
2189         } else
2190                 bip = &sh->dev[dd_idx].toread;
2191         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2192                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
2193                         goto overlap;
2194                 bip = & (*bip)->bi_next;
2195         }
2196         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
2197                 goto overlap;
2198
2199         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2200         if (*bip)
2201                 bi->bi_next = *bip;
2202         *bip = bi;
2203         bi->bi_phys_segments++;
2204
2205         if (forwrite) {
2206                 /* check if page is covered */
2207                 sector_t sector = sh->dev[dd_idx].sector;
2208                 for (bi=sh->dev[dd_idx].towrite;
2209                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2210                              bi && bi->bi_sector <= sector;
2211                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2212                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
2213                                 sector = bi->bi_sector + (bi->bi_size>>9);
2214                 }
2215                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2216                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2217         }
2218         spin_unlock_irq(&conf->device_lock);
2219
2220         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2221                 (unsigned long long)(*bip)->bi_sector,
2222                 (unsigned long long)sh->sector, dd_idx);
2223
2224         if (conf->mddev->bitmap && firstwrite) {
2225                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2226                                   STRIPE_SECTORS, 0);
2227                 sh->bm_seq = conf->seq_flush+1;
2228                 set_bit(STRIPE_BIT_DELAY, &sh->state);
2229         }
2230         return 1;
2231
2232  overlap:
2233         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2234         spin_unlock_irq(&conf->device_lock);
2235         return 0;
2236 }
2237
2238 static void end_reshape(raid5_conf_t *conf);
2239
2240 static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
2241                             struct stripe_head *sh)
2242 {
2243         int sectors_per_chunk =
2244                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2245         int dd_idx;
2246         int chunk_offset = sector_div(stripe, sectors_per_chunk);
2247         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2248
2249         raid5_compute_sector(conf,
2250                              stripe * (disks - conf->max_degraded)
2251                              *sectors_per_chunk + chunk_offset,
2252                              previous,
2253                              &dd_idx, sh);
2254 }
2255
2256 static void
2257 handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
2258                                 struct stripe_head_state *s, int disks,
2259                                 struct bio **return_bi)
2260 {
2261         int i;
2262         for (i = disks; i--; ) {
2263                 struct bio *bi;
2264                 int bitmap_end = 0;
2265
2266                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2267                         mdk_rdev_t *rdev;
2268                         rcu_read_lock();
2269                         rdev = rcu_dereference(conf->disks[i].rdev);
2270                         if (rdev && test_bit(In_sync, &rdev->flags))
2271                                 atomic_inc(&rdev->nr_pending);
2272                         else
2273                                 rdev = NULL;
2274                         rcu_read_unlock();
2275                         if (rdev) {
2276                                 if (!rdev_set_badblocks(
2277                                             rdev,
2278                                             sh->sector,
2279                                             STRIPE_SECTORS, 0))
2280                                         md_error(conf->mddev, rdev);
2281                                 rdev_dec_pending(rdev, conf->mddev);
2282                         }
2283                 }
2284                 spin_lock_irq(&conf->device_lock);
2285                 /* fail all writes first */
2286                 bi = sh->dev[i].towrite;
2287                 sh->dev[i].towrite = NULL;
2288                 if (bi) {
2289                         s->to_write--;
2290                         bitmap_end = 1;
2291                 }
2292
2293                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2294                         wake_up(&conf->wait_for_overlap);
2295
2296                 while (bi && bi->bi_sector <
2297                         sh->dev[i].sector + STRIPE_SECTORS) {
2298                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2299                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2300                         if (!raid5_dec_bi_phys_segments(bi)) {
2301                                 md_write_end(conf->mddev);
2302                                 bi->bi_next = *return_bi;
2303                                 *return_bi = bi;
2304                         }
2305                         bi = nextbi;
2306                 }
2307                 /* and fail all 'written' */
2308                 bi = sh->dev[i].written;
2309                 sh->dev[i].written = NULL;
2310                 if (bi) bitmap_end = 1;
2311                 while (bi && bi->bi_sector <
2312                        sh->dev[i].sector + STRIPE_SECTORS) {
2313                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2314                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2315                         if (!raid5_dec_bi_phys_segments(bi)) {
2316                                 md_write_end(conf->mddev);
2317                                 bi->bi_next = *return_bi;
2318                                 *return_bi = bi;
2319                         }
2320                         bi = bi2;
2321                 }
2322
2323                 /* fail any reads if this device is non-operational and
2324                  * the data has not reached the cache yet.
2325                  */
2326                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2327                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2328                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2329                         bi = sh->dev[i].toread;
2330                         sh->dev[i].toread = NULL;
2331                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2332                                 wake_up(&conf->wait_for_overlap);
2333                         if (bi) s->to_read--;
2334                         while (bi && bi->bi_sector <
2335                                sh->dev[i].sector + STRIPE_SECTORS) {
2336                                 struct bio *nextbi =
2337                                         r5_next_bio(bi, sh->dev[i].sector);
2338                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2339                                 if (!raid5_dec_bi_phys_segments(bi)) {
2340                                         bi->bi_next = *return_bi;
2341                                         *return_bi = bi;
2342                                 }
2343                                 bi = nextbi;
2344                         }
2345                 }
2346                 spin_unlock_irq(&conf->device_lock);
2347                 if (bitmap_end)
2348                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2349                                         STRIPE_SECTORS, 0, 0);
2350                 /* If we were in the middle of a write the parity block might
2351                  * still be locked - so just clear all R5_LOCKED flags
2352                  */
2353                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2354         }
2355
2356         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2357                 if (atomic_dec_and_test(&conf->pending_full_writes))
2358                         md_wakeup_thread(conf->mddev->thread);
2359 }
2360
2361 static void
2362 handle_failed_sync(raid5_conf_t *conf, struct stripe_head *sh,
2363                    struct stripe_head_state *s)
2364 {
2365         int abort = 0;
2366         int i;
2367
2368         md_done_sync(conf->mddev, STRIPE_SECTORS, 0);
2369         clear_bit(STRIPE_SYNCING, &sh->state);
2370         s->syncing = 0;
2371         /* There is nothing more to do for sync/check/repair.
2372          * For recover we need to record a bad block on all
2373          * non-sync devices, or abort the recovery
2374          */
2375         if (!test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery))
2376                 return;
2377         /* During recovery devices cannot be removed, so locking and
2378          * refcounting of rdevs is not needed
2379          */
2380         for (i = 0; i < conf->raid_disks; i++) {
2381                 mdk_rdev_t *rdev = conf->disks[i].rdev;
2382                 if (!rdev
2383                     || test_bit(Faulty, &rdev->flags)
2384                     || test_bit(In_sync, &rdev->flags))
2385                         continue;
2386                 if (!rdev_set_badblocks(rdev, sh->sector,
2387                                         STRIPE_SECTORS, 0))
2388                         abort = 1;
2389         }
2390         if (abort) {
2391                 conf->recovery_disabled = conf->mddev->recovery_disabled;
2392                 set_bit(MD_RECOVERY_INTR, &conf->mddev->recovery);
2393         }
2394 }
2395
2396 /* fetch_block - checks the given member device to see if its data needs
2397  * to be read or computed to satisfy a request.
2398  *
2399  * Returns 1 when no more member devices need to be checked, otherwise returns
2400  * 0 to tell the loop in handle_stripe_fill to continue
2401  */
2402 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2403                        int disk_idx, int disks)
2404 {
2405         struct r5dev *dev = &sh->dev[disk_idx];
2406         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2407                                   &sh->dev[s->failed_num[1]] };
2408
2409         /* is the data in this block needed, and can we get it? */
2410         if (!test_bit(R5_LOCKED, &dev->flags) &&
2411             !test_bit(R5_UPTODATE, &dev->flags) &&
2412             (dev->toread ||
2413              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2414              s->syncing || s->expanding ||
2415              (s->failed >= 1 && fdev[0]->toread) ||
2416              (s->failed >= 2 && fdev[1]->toread) ||
2417              (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2418               !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2419              (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2420                 /* we would like to get this block, possibly by computing it,
2421                  * otherwise read it if the backing disk is insync
2422                  */
2423                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2424                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
2425                 if ((s->uptodate == disks - 1) &&
2426                     (s->failed && (disk_idx == s->failed_num[0] ||
2427                                    disk_idx == s->failed_num[1]))) {
2428                         /* have disk failed, and we're requested to fetch it;
2429                          * do compute it
2430                          */
2431                         pr_debug("Computing stripe %llu block %d\n",
2432                                (unsigned long long)sh->sector, disk_idx);
2433                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2434                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2435                         set_bit(R5_Wantcompute, &dev->flags);
2436                         sh->ops.target = disk_idx;
2437                         sh->ops.target2 = -1; /* no 2nd target */
2438                         s->req_compute = 1;
2439                         /* Careful: from this point on 'uptodate' is in the eye
2440                          * of raid_run_ops which services 'compute' operations
2441                          * before writes. R5_Wantcompute flags a block that will
2442                          * be R5_UPTODATE by the time it is needed for a
2443                          * subsequent operation.
2444                          */
2445                         s->uptodate++;
2446                         return 1;
2447                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
2448                         /* Computing 2-failure is *very* expensive; only
2449                          * do it if failed >= 2
2450                          */
2451                         int other;
2452                         for (other = disks; other--; ) {
2453                                 if (other == disk_idx)
2454                                         continue;
2455                                 if (!test_bit(R5_UPTODATE,
2456                                       &sh->dev[other].flags))
2457                                         break;
2458                         }
2459                         BUG_ON(other < 0);
2460                         pr_debug("Computing stripe %llu blocks %d,%d\n",
2461                                (unsigned long long)sh->sector,
2462                                disk_idx, other);
2463                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2464                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2465                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2466                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
2467                         sh->ops.target = disk_idx;
2468                         sh->ops.target2 = other;
2469                         s->uptodate += 2;
2470                         s->req_compute = 1;
2471                         return 1;
2472                 } else if (test_bit(R5_Insync, &dev->flags)) {
2473                         set_bit(R5_LOCKED, &dev->flags);
2474                         set_bit(R5_Wantread, &dev->flags);
2475                         s->locked++;
2476                         pr_debug("Reading block %d (sync=%d)\n",
2477                                 disk_idx, s->syncing);
2478                 }
2479         }
2480
2481         return 0;
2482 }
2483
2484 /**
2485  * handle_stripe_fill - read or compute data to satisfy pending requests.
2486  */
2487 static void handle_stripe_fill(struct stripe_head *sh,
2488                                struct stripe_head_state *s,
2489                                int disks)
2490 {
2491         int i;
2492
2493         /* look for blocks to read/compute, skip this if a compute
2494          * is already in flight, or if the stripe contents are in the
2495          * midst of changing due to a write
2496          */
2497         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2498             !sh->reconstruct_state)
2499                 for (i = disks; i--; )
2500                         if (fetch_block(sh, s, i, disks))
2501                                 break;
2502         set_bit(STRIPE_HANDLE, &sh->state);
2503 }
2504
2505
2506 /* handle_stripe_clean_event
2507  * any written block on an uptodate or failed drive can be returned.
2508  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2509  * never LOCKED, so we don't need to test 'failed' directly.
2510  */
2511 static void handle_stripe_clean_event(raid5_conf_t *conf,
2512         struct stripe_head *sh, int disks, struct bio **return_bi)
2513 {
2514         int i;
2515         struct r5dev *dev;
2516
2517         for (i = disks; i--; )
2518                 if (sh->dev[i].written) {
2519                         dev = &sh->dev[i];
2520                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2521                                 test_bit(R5_UPTODATE, &dev->flags)) {
2522                                 /* We can return any write requests */
2523                                 struct bio *wbi, *wbi2;
2524                                 int bitmap_end = 0;
2525                                 pr_debug("Return write for disc %d\n", i);
2526                                 spin_lock_irq(&conf->device_lock);
2527                                 wbi = dev->written;
2528                                 dev->written = NULL;
2529                                 while (wbi && wbi->bi_sector <
2530                                         dev->sector + STRIPE_SECTORS) {
2531                                         wbi2 = r5_next_bio(wbi, dev->sector);
2532                                         if (!raid5_dec_bi_phys_segments(wbi)) {
2533                                                 md_write_end(conf->mddev);
2534                                                 wbi->bi_next = *return_bi;
2535                                                 *return_bi = wbi;
2536                                         }
2537                                         wbi = wbi2;
2538                                 }
2539                                 if (dev->towrite == NULL)
2540                                         bitmap_end = 1;
2541                                 spin_unlock_irq(&conf->device_lock);
2542                                 if (bitmap_end)
2543                                         bitmap_endwrite(conf->mddev->bitmap,
2544                                                         sh->sector,
2545                                                         STRIPE_SECTORS,
2546                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2547                                                         0);
2548                         }
2549                 }
2550
2551         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2552                 if (atomic_dec_and_test(&conf->pending_full_writes))
2553                         md_wakeup_thread(conf->mddev->thread);
2554 }
2555
2556 static void handle_stripe_dirtying(raid5_conf_t *conf,
2557                                    struct stripe_head *sh,
2558                                    struct stripe_head_state *s,
2559                                    int disks)
2560 {
2561         int rmw = 0, rcw = 0, i;
2562         if (conf->max_degraded == 2) {
2563                 /* RAID6 requires 'rcw' in current implementation
2564                  * Calculate the real rcw later - for now fake it
2565                  * look like rcw is cheaper
2566                  */
2567                 rcw = 1; rmw = 2;
2568         } else for (i = disks; i--; ) {
2569                 /* would I have to read this buffer for read_modify_write */
2570                 struct r5dev *dev = &sh->dev[i];
2571                 if ((dev->towrite || i == sh->pd_idx) &&
2572                     !test_bit(R5_LOCKED, &dev->flags) &&
2573                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2574                       test_bit(R5_Wantcompute, &dev->flags))) {
2575                         if (test_bit(R5_Insync, &dev->flags))
2576                                 rmw++;
2577                         else
2578                                 rmw += 2*disks;  /* cannot read it */
2579                 }
2580                 /* Would I have to read this buffer for reconstruct_write */
2581                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2582                     !test_bit(R5_LOCKED, &dev->flags) &&
2583                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2584                     test_bit(R5_Wantcompute, &dev->flags))) {
2585                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2586                         else
2587                                 rcw += 2*disks;
2588                 }
2589         }
2590         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2591                 (unsigned long long)sh->sector, rmw, rcw);
2592         set_bit(STRIPE_HANDLE, &sh->state);
2593         if (rmw < rcw && rmw > 0)
2594                 /* prefer read-modify-write, but need to get some data */
2595                 for (i = disks; i--; ) {
2596                         struct r5dev *dev = &sh->dev[i];
2597                         if ((dev->towrite || i == sh->pd_idx) &&
2598                             !test_bit(R5_LOCKED, &dev->flags) &&
2599                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2600                             test_bit(R5_Wantcompute, &dev->flags)) &&
2601                             test_bit(R5_Insync, &dev->flags)) {
2602                                 if (
2603                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2604                                         pr_debug("Read_old block "
2605                                                 "%d for r-m-w\n", i);
2606                                         set_bit(R5_LOCKED, &dev->flags);
2607                                         set_bit(R5_Wantread, &dev->flags);
2608                                         s->locked++;
2609                                 } else {
2610                                         set_bit(STRIPE_DELAYED, &sh->state);
2611                                         set_bit(STRIPE_HANDLE, &sh->state);
2612                                 }
2613                         }
2614                 }
2615         if (rcw <= rmw && rcw > 0) {
2616                 /* want reconstruct write, but need to get some data */
2617                 rcw = 0;
2618                 for (i = disks; i--; ) {
2619                         struct r5dev *dev = &sh->dev[i];
2620                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2621                             i != sh->pd_idx && i != sh->qd_idx &&
2622                             !test_bit(R5_LOCKED, &dev->flags) &&
2623                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2624                               test_bit(R5_Wantcompute, &dev->flags))) {
2625                                 rcw++;
2626                                 if (!test_bit(R5_Insync, &dev->flags))
2627                                         continue; /* it's a failed drive */
2628                                 if (
2629                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2630                                         pr_debug("Read_old block "
2631                                                 "%d for Reconstruct\n", i);
2632                                         set_bit(R5_LOCKED, &dev->flags);
2633                                         set_bit(R5_Wantread, &dev->flags);
2634                                         s->locked++;
2635                                 } else {
2636                                         set_bit(STRIPE_DELAYED, &sh->state);
2637                                         set_bit(STRIPE_HANDLE, &sh->state);
2638                                 }
2639                         }
2640                 }
2641         }
2642         /* now if nothing is locked, and if we have enough data,
2643          * we can start a write request
2644          */
2645         /* since handle_stripe can be called at any time we need to handle the
2646          * case where a compute block operation has been submitted and then a
2647          * subsequent call wants to start a write request.  raid_run_ops only
2648          * handles the case where compute block and reconstruct are requested
2649          * simultaneously.  If this is not the case then new writes need to be
2650          * held off until the compute completes.
2651          */
2652         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2653             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2654             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2655                 schedule_reconstruction(sh, s, rcw == 0, 0);
2656 }
2657
2658 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2659                                 struct stripe_head_state *s, int disks)
2660 {
2661         struct r5dev *dev = NULL;
2662
2663         set_bit(STRIPE_HANDLE, &sh->state);
2664
2665         switch (sh->check_state) {
2666         case check_state_idle:
2667                 /* start a new check operation if there are no failures */
2668                 if (s->failed == 0) {
2669                         BUG_ON(s->uptodate != disks);
2670                         sh->check_state = check_state_run;
2671                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2672                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2673                         s->uptodate--;
2674                         break;
2675                 }
2676                 dev = &sh->dev[s->failed_num[0]];
2677                 /* fall through */
2678         case check_state_compute_result:
2679                 sh->check_state = check_state_idle;
2680                 if (!dev)
2681                         dev = &sh->dev[sh->pd_idx];
2682
2683                 /* check that a write has not made the stripe insync */
2684                 if (test_bit(STRIPE_INSYNC, &sh->state))
2685                         break;
2686
2687                 /* either failed parity check, or recovery is happening */
2688                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2689                 BUG_ON(s->uptodate != disks);
2690
2691                 set_bit(R5_LOCKED, &dev->flags);
2692                 s->locked++;
2693                 set_bit(R5_Wantwrite, &dev->flags);
2694
2695                 clear_bit(STRIPE_DEGRADED, &sh->state);
2696                 set_bit(STRIPE_INSYNC, &sh->state);
2697                 break;
2698         case check_state_run:
2699                 break; /* we will be called again upon completion */
2700         case check_state_check_result:
2701                 sh->check_state = check_state_idle;
2702
2703                 /* if a failure occurred during the check operation, leave
2704                  * STRIPE_INSYNC not set and let the stripe be handled again
2705                  */
2706                 if (s->failed)
2707                         break;
2708
2709                 /* handle a successful check operation, if parity is correct
2710                  * we are done.  Otherwise update the mismatch count and repair
2711                  * parity if !MD_RECOVERY_CHECK
2712                  */
2713                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2714                         /* parity is correct (on disc,
2715                          * not in buffer any more)
2716                          */
2717                         set_bit(STRIPE_INSYNC, &sh->state);
2718                 else {
2719                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2720                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2721                                 /* don't try to repair!! */
2722                                 set_bit(STRIPE_INSYNC, &sh->state);
2723                         else {
2724                                 sh->check_state = check_state_compute_run;
2725                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2726                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2727                                 set_bit(R5_Wantcompute,
2728                                         &sh->dev[sh->pd_idx].flags);
2729                                 sh->ops.target = sh->pd_idx;
2730                                 sh->ops.target2 = -1;
2731                                 s->uptodate++;
2732                         }
2733                 }
2734                 break;
2735         case check_state_compute_run:
2736                 break;
2737         default:
2738                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2739                        __func__, sh->check_state,
2740                        (unsigned long long) sh->sector);
2741                 BUG();
2742         }
2743 }
2744
2745
2746 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2747                                   struct stripe_head_state *s,
2748                                   int disks)
2749 {
2750         int pd_idx = sh->pd_idx;
2751         int qd_idx = sh->qd_idx;
2752         struct r5dev *dev;
2753
2754         set_bit(STRIPE_HANDLE, &sh->state);
2755
2756         BUG_ON(s->failed > 2);
2757
2758         /* Want to check and possibly repair P and Q.
2759          * However there could be one 'failed' device, in which
2760          * case we can only check one of them, possibly using the
2761          * other to generate missing data
2762          */
2763
2764         switch (sh->check_state) {
2765         case check_state_idle:
2766                 /* start a new check operation if there are < 2 failures */
2767                 if (s->failed == s->q_failed) {
2768                         /* The only possible failed device holds Q, so it
2769                          * makes sense to check P (If anything else were failed,
2770                          * we would have used P to recreate it).
2771                          */
2772                         sh->check_state = check_state_run;
2773                 }
2774                 if (!s->q_failed && s->failed < 2) {
2775                         /* Q is not failed, and we didn't use it to generate
2776                          * anything, so it makes sense to check it
2777                          */
2778                         if (sh->check_state == check_state_run)
2779                                 sh->check_state = check_state_run_pq;
2780                         else
2781                                 sh->check_state = check_state_run_q;
2782                 }
2783
2784                 /* discard potentially stale zero_sum_result */
2785                 sh->ops.zero_sum_result = 0;
2786
2787                 if (sh->check_state == check_state_run) {
2788                         /* async_xor_zero_sum destroys the contents of P */
2789                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2790                         s->uptodate--;
2791                 }
2792                 if (sh->check_state >= check_state_run &&
2793                     sh->check_state <= check_state_run_pq) {
2794                         /* async_syndrome_zero_sum preserves P and Q, so
2795                          * no need to mark them !uptodate here
2796                          */
2797                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2798                         break;
2799                 }
2800
2801                 /* we have 2-disk failure */
2802                 BUG_ON(s->failed != 2);
2803                 /* fall through */
2804         case check_state_compute_result:
2805                 sh->check_state = check_state_idle;
2806
2807                 /* check that a write has not made the stripe insync */
2808                 if (test_bit(STRIPE_INSYNC, &sh->state))
2809                         break;
2810
2811                 /* now write out any block on a failed drive,
2812                  * or P or Q if they were recomputed
2813                  */
2814                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
2815                 if (s->failed == 2) {
2816                         dev = &sh->dev[s->failed_num[1]];
2817                         s->locked++;
2818                         set_bit(R5_LOCKED, &dev->flags);
2819                         set_bit(R5_Wantwrite, &dev->flags);
2820                 }
2821                 if (s->failed >= 1) {
2822                         dev = &sh->dev[s->failed_num[0]];
2823                         s->locked++;
2824                         set_bit(R5_LOCKED, &dev->flags);
2825                         set_bit(R5_Wantwrite, &dev->flags);
2826                 }
2827                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
2828                         dev = &sh->dev[pd_idx];
2829                         s->locked++;
2830                         set_bit(R5_LOCKED, &dev->flags);
2831                         set_bit(R5_Wantwrite, &dev->flags);
2832                 }
2833                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
2834                         dev = &sh->dev[qd_idx];
2835                         s->locked++;
2836                         set_bit(R5_LOCKED, &dev->flags);
2837                         set_bit(R5_Wantwrite, &dev->flags);
2838                 }
2839                 clear_bit(STRIPE_DEGRADED, &sh->state);
2840
2841                 set_bit(STRIPE_INSYNC, &sh->state);
2842                 break;
2843         case check_state_run:
2844         case check_state_run_q:
2845         case check_state_run_pq:
2846                 break; /* we will be called again upon completion */
2847         case check_state_check_result:
2848                 sh->check_state = check_state_idle;
2849
2850                 /* handle a successful check operation, if parity is correct
2851                  * we are done.  Otherwise update the mismatch count and repair
2852                  * parity if !MD_RECOVERY_CHECK
2853                  */
2854                 if (sh->ops.zero_sum_result == 0) {
2855                         /* both parities are correct */
2856                         if (!s->failed)
2857                                 set_bit(STRIPE_INSYNC, &sh->state);
2858                         else {
2859                                 /* in contrast to the raid5 case we can validate
2860                                  * parity, but still have a failure to write
2861                                  * back
2862                                  */
2863                                 sh->check_state = check_state_compute_result;
2864                                 /* Returning at this point means that we may go
2865                                  * off and bring p and/or q uptodate again so
2866                                  * we make sure to check zero_sum_result again
2867                                  * to verify if p or q need writeback
2868                                  */
2869                         }
2870                 } else {
2871                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2872                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2873                                 /* don't try to repair!! */
2874                                 set_bit(STRIPE_INSYNC, &sh->state);
2875                         else {
2876                                 int *target = &sh->ops.target;
2877
2878                                 sh->ops.target = -1;
2879                                 sh->ops.target2 = -1;
2880                                 sh->check_state = check_state_compute_run;
2881                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2882                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2883                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
2884                                         set_bit(R5_Wantcompute,
2885                                                 &sh->dev[pd_idx].flags);
2886                                         *target = pd_idx;
2887                                         target = &sh->ops.target2;
2888                                         s->uptodate++;
2889                                 }
2890                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
2891                                         set_bit(R5_Wantcompute,
2892                                                 &sh->dev[qd_idx].flags);
2893                                         *target = qd_idx;
2894                                         s->uptodate++;
2895                                 }
2896                         }
2897                 }
2898                 break;
2899         case check_state_compute_run:
2900                 break;
2901         default:
2902                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2903                        __func__, sh->check_state,
2904                        (unsigned long long) sh->sector);
2905                 BUG();
2906         }
2907 }
2908
2909 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh)
2910 {
2911         int i;
2912
2913         /* We have read all the blocks in this stripe and now we need to
2914          * copy some of them into a target stripe for expand.
2915          */
2916         struct dma_async_tx_descriptor *tx = NULL;
2917         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2918         for (i = 0; i < sh->disks; i++)
2919                 if (i != sh->pd_idx && i != sh->qd_idx) {
2920                         int dd_idx, j;
2921                         struct stripe_head *sh2;
2922                         struct async_submit_ctl submit;
2923
2924                         sector_t bn = compute_blocknr(sh, i, 1);
2925                         sector_t s = raid5_compute_sector(conf, bn, 0,
2926                                                           &dd_idx, NULL);
2927                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
2928                         if (sh2 == NULL)
2929                                 /* so far only the early blocks of this stripe
2930                                  * have been requested.  When later blocks
2931                                  * get requested, we will try again
2932                                  */
2933                                 continue;
2934                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2935                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2936                                 /* must have already done this block */
2937                                 release_stripe(sh2);
2938                                 continue;
2939                         }
2940
2941                         /* place all the copies on one channel */
2942                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
2943                         tx = async_memcpy(sh2->dev[dd_idx].page,
2944                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
2945                                           &submit);
2946
2947                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2948                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2949                         for (j = 0; j < conf->raid_disks; j++)
2950                                 if (j != sh2->pd_idx &&
2951                                     j != sh2->qd_idx &&
2952                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
2953                                         break;
2954                         if (j == conf->raid_disks) {
2955                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
2956                                 set_bit(STRIPE_HANDLE, &sh2->state);
2957                         }
2958                         release_stripe(sh2);
2959
2960                 }
2961         /* done submitting copies, wait for them to complete */
2962         if (tx) {
2963                 async_tx_ack(tx);
2964                 dma_wait_for_async_tx(tx);
2965         }
2966 }
2967
2968
2969 /*
2970  * handle_stripe - do things to a stripe.
2971  *
2972  * We lock the stripe and then examine the state of various bits
2973  * to see what needs to be done.
2974  * Possible results:
2975  *    return some read request which now have data
2976  *    return some write requests which are safely on disc
2977  *    schedule a read on some buffers
2978  *    schedule a write of some buffers
2979  *    return confirmation of parity correctness
2980  *
2981  * buffers are taken off read_list or write_list, and bh_cache buffers
2982  * get BH_Lock set before the stripe lock is released.
2983  *
2984  */
2985
2986 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
2987 {
2988         raid5_conf_t *conf = sh->raid_conf;
2989         int disks = sh->disks;
2990         struct r5dev *dev;
2991         int i;
2992
2993         memset(s, 0, sizeof(*s));
2994
2995         s->syncing = test_bit(STRIPE_SYNCING, &sh->state);
2996         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2997         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2998         s->failed_num[0] = -1;
2999         s->failed_num[1] = -1;
3000
3001         /* Now to look around and see what can be done */
3002         rcu_read_lock();
3003         spin_lock_irq(&conf->device_lock);
3004         for (i=disks; i--; ) {
3005                 mdk_rdev_t *rdev;
3006                 sector_t first_bad;
3007                 int bad_sectors;
3008                 int is_bad = 0;
3009
3010                 dev = &sh->dev[i];
3011
3012                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3013                         i, dev->flags, dev->toread, dev->towrite, dev->written);
3014                 /* maybe we can reply to a read
3015                  *
3016                  * new wantfill requests are only permitted while
3017                  * ops_complete_biofill is guaranteed to be inactive
3018                  */
3019                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3020                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3021                         set_bit(R5_Wantfill, &dev->flags);
3022
3023                 /* now count some things */
3024                 if (test_bit(R5_LOCKED, &dev->flags))
3025                         s->locked++;
3026                 if (test_bit(R5_UPTODATE, &dev->flags))
3027                         s->uptodate++;
3028                 if (test_bit(R5_Wantcompute, &dev->flags)) {
3029                         s->compute++;
3030                         BUG_ON(s->compute > 2);
3031                 }
3032
3033                 if (test_bit(R5_Wantfill, &dev->flags))
3034                         s->to_fill++;
3035                 else if (dev->toread)
3036                         s->to_read++;
3037                 if (dev->towrite) {
3038                         s->to_write++;
3039                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3040                                 s->non_overwrite++;
3041                 }
3042                 if (dev->written)
3043                         s->written++;
3044                 rdev = rcu_dereference(conf->disks[i].rdev);
3045                 if (rdev) {
3046                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3047                                              &first_bad, &bad_sectors);
3048                         if (s->blocked_rdev == NULL
3049                             && (test_bit(Blocked, &rdev->flags)
3050                                 || is_bad < 0)) {
3051                                 if (is_bad < 0)
3052                                         set_bit(BlockedBadBlocks,
3053                                                 &rdev->flags);
3054                                 s->blocked_rdev = rdev;
3055                                 atomic_inc(&rdev->nr_pending);
3056                         }
3057                 }
3058                 clear_bit(R5_Insync, &dev->flags);
3059                 if (!rdev)
3060                         /* Not in-sync */;
3061                 else if (is_bad) {
3062                         /* also not in-sync */
3063                         if (!test_bit(WriteErrorSeen, &rdev->flags)) {
3064                                 /* treat as in-sync, but with a read error
3065                                  * which we can now try to correct
3066                                  */
3067                                 set_bit(R5_Insync, &dev->flags);
3068                                 set_bit(R5_ReadError, &dev->flags);
3069                         }
3070                 } else if (test_bit(In_sync, &rdev->flags))
3071                         set_bit(R5_Insync, &dev->flags);
3072                 else {
3073                         /* in sync if before recovery_offset */
3074                         if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3075                                 set_bit(R5_Insync, &dev->flags);
3076                 }
3077                 if (test_bit(R5_WriteError, &dev->flags)) {
3078                         clear_bit(R5_Insync, &dev->flags);
3079                         if (!test_bit(Faulty, &rdev->flags)) {
3080                                 s->handle_bad_blocks = 1;
3081                                 atomic_inc(&rdev->nr_pending);
3082                         } else
3083                                 clear_bit(R5_WriteError, &dev->flags);
3084                 }
3085                 if (test_bit(R5_MadeGood, &dev->flags)) {
3086                         if (!test_bit(Faulty, &rdev->flags)) {
3087                                 s->handle_bad_blocks = 1;
3088                                 atomic_inc(&rdev->nr_pending);
3089                         } else
3090                                 clear_bit(R5_MadeGood, &dev->flags);
3091                 }
3092                 if (!test_bit(R5_Insync, &dev->flags)) {
3093                         /* The ReadError flag will just be confusing now */
3094                         clear_bit(R5_ReadError, &dev->flags);
3095                         clear_bit(R5_ReWrite, &dev->flags);
3096                 }
3097                 if (test_bit(R5_ReadError, &dev->flags))
3098                         clear_bit(R5_Insync, &dev->flags);
3099                 if (!test_bit(R5_Insync, &dev->flags)) {
3100                         if (s->failed < 2)
3101                                 s->failed_num[s->failed] = i;
3102                         s->failed++;
3103                 }
3104         }
3105         spin_unlock_irq(&conf->device_lock);
3106         rcu_read_unlock();
3107 }
3108
3109 static void handle_stripe(struct stripe_head *sh)
3110 {
3111         struct stripe_head_state s;
3112         raid5_conf_t *conf = sh->raid_conf;
3113         int i;
3114         int prexor;
3115         int disks = sh->disks;
3116         struct r5dev *pdev, *qdev;
3117
3118         clear_bit(STRIPE_HANDLE, &sh->state);
3119         if (test_and_set_bit(STRIPE_ACTIVE, &sh->state)) {
3120                 /* already being handled, ensure it gets handled
3121                  * again when current action finishes */
3122                 set_bit(STRIPE_HANDLE, &sh->state);
3123                 return;
3124         }
3125
3126         if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3127                 set_bit(STRIPE_SYNCING, &sh->state);
3128                 clear_bit(STRIPE_INSYNC, &sh->state);
3129         }
3130         clear_bit(STRIPE_DELAYED, &sh->state);
3131
3132         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3133                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3134                (unsigned long long)sh->sector, sh->state,
3135                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3136                sh->check_state, sh->reconstruct_state);
3137
3138         analyse_stripe(sh, &s);
3139
3140         if (s.handle_bad_blocks) {
3141                 set_bit(STRIPE_HANDLE, &sh->state);
3142                 goto finish;
3143         }
3144
3145         if (unlikely(s.blocked_rdev)) {
3146                 if (s.syncing || s.expanding || s.expanded ||
3147                     s.to_write || s.written) {
3148                         set_bit(STRIPE_HANDLE, &sh->state);
3149                         goto finish;
3150                 }
3151                 /* There is nothing for the blocked_rdev to block */
3152                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
3153                 s.blocked_rdev = NULL;
3154         }
3155
3156         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3157                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3158                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3159         }
3160
3161         pr_debug("locked=%d uptodate=%d to_read=%d"
3162                " to_write=%d failed=%d failed_num=%d,%d\n",
3163                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3164                s.failed_num[0], s.failed_num[1]);
3165         /* check if the array has lost more than max_degraded devices and,
3166          * if so, some requests might need to be failed.
3167          */
3168         if (s.failed > conf->max_degraded && s.to_read+s.to_write+s.written)
3169                 handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3170         if (s.failed > conf->max_degraded && s.syncing)
3171                 handle_failed_sync(conf, sh, &s);
3172
3173         /*
3174          * might be able to return some write requests if the parity blocks
3175          * are safe, or on a failed drive
3176          */
3177         pdev = &sh->dev[sh->pd_idx];
3178         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3179                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3180         qdev = &sh->dev[sh->qd_idx];
3181         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3182                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3183                 || conf->level < 6;
3184
3185         if (s.written &&
3186             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3187                              && !test_bit(R5_LOCKED, &pdev->flags)
3188                              && test_bit(R5_UPTODATE, &pdev->flags)))) &&
3189             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3190                              && !test_bit(R5_LOCKED, &qdev->flags)
3191                              && test_bit(R5_UPTODATE, &qdev->flags)))))
3192                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3193
3194         /* Now we might consider reading some blocks, either to check/generate
3195          * parity, or to satisfy requests
3196          * or to load a block that is being partially written.
3197          */
3198         if (s.to_read || s.non_overwrite
3199             || (conf->level == 6 && s.to_write && s.failed)
3200             || (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
3201                 handle_stripe_fill(sh, &s, disks);
3202
3203         /* Now we check to see if any write operations have recently
3204          * completed
3205          */
3206         prexor = 0;
3207         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3208                 prexor = 1;
3209         if (sh->reconstruct_state == reconstruct_state_drain_result ||
3210             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3211                 sh->reconstruct_state = reconstruct_state_idle;
3212
3213                 /* All the 'written' buffers and the parity block are ready to
3214                  * be written back to disk
3215                  */
3216                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
3217                 BUG_ON(sh->qd_idx >= 0 &&
3218                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags));
3219                 for (i = disks; i--; ) {
3220                         struct r5dev *dev = &sh->dev[i];
3221                         if (test_bit(R5_LOCKED, &dev->flags) &&
3222                                 (i == sh->pd_idx || i == sh->qd_idx ||
3223                                  dev->written)) {
3224                                 pr_debug("Writing block %d\n", i);
3225                                 set_bit(R5_Wantwrite, &dev->flags);
3226                                 if (prexor)
3227                                         continue;
3228                                 if (!test_bit(R5_Insync, &dev->flags) ||
3229                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
3230                                      s.failed == 0))
3231                                         set_bit(STRIPE_INSYNC, &sh->state);
3232                         }
3233                 }
3234                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3235                         s.dec_preread_active = 1;
3236         }
3237
3238         /* Now to consider new write requests and what else, if anything
3239          * should be read.  We do not handle new writes when:
3240          * 1/ A 'write' operation (copy+xor) is already in flight.
3241          * 2/ A 'check' operation is in flight, as it may clobber the parity
3242          *    block.
3243          */
3244         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3245                 handle_stripe_dirtying(conf, sh, &s, disks);
3246
3247         /* maybe we need to check and possibly fix the parity for this stripe
3248          * Any reads will already have been scheduled, so we just see if enough
3249          * data is available.  The parity check is held off while parity
3250          * dependent operations are in flight.
3251          */
3252         if (sh->check_state ||
3253             (s.syncing && s.locked == 0 &&
3254              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3255              !test_bit(STRIPE_INSYNC, &sh->state))) {
3256                 if (conf->level == 6)
3257                         handle_parity_checks6(conf, sh, &s, disks);
3258                 else
3259                         handle_parity_checks5(conf, sh, &s, disks);
3260         }
3261
3262         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
3263                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3264                 clear_bit(STRIPE_SYNCING, &sh->state);
3265         }
3266
3267         /* If the failed drives are just a ReadError, then we might need
3268          * to progress the repair/check process
3269          */
3270         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3271                 for (i = 0; i < s.failed; i++) {
3272                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
3273                         if (test_bit(R5_ReadError, &dev->flags)
3274                             && !test_bit(R5_LOCKED, &dev->flags)
3275                             && test_bit(R5_UPTODATE, &dev->flags)
3276                                 ) {
3277                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3278                                         set_bit(R5_Wantwrite, &dev->flags);
3279                                         set_bit(R5_ReWrite, &dev->flags);
3280                                         set_bit(R5_LOCKED, &dev->flags);
3281                                         s.locked++;
3282                                 } else {
3283                                         /* let's read it back */
3284                                         set_bit(R5_Wantread, &dev->flags);
3285                                         set_bit(R5_LOCKED, &dev->flags);
3286                                         s.locked++;
3287                                 }
3288                         }
3289                 }
3290
3291
3292         /* Finish reconstruct operations initiated by the expansion process */
3293         if (sh->reconstruct_state == reconstruct_state_result) {
3294                 struct stripe_head *sh_src
3295                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3296                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3297                         /* sh cannot be written until sh_src has been read.
3298                          * so arrange for sh to be delayed a little
3299                          */
3300                         set_bit(STRIPE_DELAYED, &sh->state);
3301                         set_bit(STRIPE_HANDLE, &sh->state);
3302                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3303                                               &sh_src->state))
3304                                 atomic_inc(&conf->preread_active_stripes);
3305                         release_stripe(sh_src);
3306                         goto finish;
3307                 }
3308                 if (sh_src)
3309                         release_stripe(sh_src);
3310
3311                 sh->reconstruct_state = reconstruct_state_idle;
3312                 clear_bit(STRIPE_EXPANDING, &sh->state);
3313                 for (i = conf->raid_disks; i--; ) {
3314                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3315                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3316                         s.locked++;
3317                 }
3318         }
3319
3320         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3321             !sh->reconstruct_state) {
3322                 /* Need to write out all blocks after computing parity */
3323                 sh->disks = conf->raid_disks;
3324                 stripe_set_idx(sh->sector, conf, 0, sh);
3325                 schedule_reconstruction(sh, &s, 1, 1);
3326         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3327                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3328                 atomic_dec(&conf->reshape_stripes);
3329                 wake_up(&conf->wait_for_overlap);
3330                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3331         }
3332
3333         if (s.expanding && s.locked == 0 &&
3334             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3335                 handle_stripe_expansion(conf, sh);
3336
3337 finish:
3338         /* wait for this device to become unblocked */
3339         if (unlikely(s.blocked_rdev))
3340                 md_wait_for_blocked_rdev(s.blocked_rdev, conf->mddev);
3341
3342         if (s.handle_bad_blocks)
3343                 for (i = disks; i--; ) {
3344                         mdk_rdev_t *rdev;
3345                         struct r5dev *dev = &sh->dev[i];
3346                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3347                                 /* We own a safe reference to the rdev */
3348                                 rdev = conf->disks[i].rdev;
3349                                 if (!rdev_set_badblocks(rdev, sh->sector,
3350                                                         STRIPE_SECTORS, 0))
3351                                         md_error(conf->mddev, rdev);
3352                                 rdev_dec_pending(rdev, conf->mddev);
3353                         }
3354                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3355                                 rdev = conf->disks[i].rdev;
3356                                 rdev_clear_badblocks(rdev, sh->sector,
3357                                                      STRIPE_SECTORS);
3358                                 rdev_dec_pending(rdev, conf->mddev);
3359                         }
3360                 }
3361
3362         if (s.ops_request)
3363                 raid_run_ops(sh, s.ops_request);
3364
3365         ops_run_io(sh, &s);
3366
3367         if (s.dec_preread_active) {
3368                 /* We delay this until after ops_run_io so that if make_request
3369                  * is waiting on a flush, it won't continue until the writes
3370                  * have actually been submitted.
3371                  */
3372                 atomic_dec(&conf->preread_active_stripes);
3373                 if (atomic_read(&conf->preread_active_stripes) <
3374                     IO_THRESHOLD)
3375                         md_wakeup_thread(conf->mddev->thread);
3376         }
3377
3378         return_io(s.return_bi);
3379
3380         clear_bit(STRIPE_ACTIVE, &sh->state);
3381 }
3382
3383 static void raid5_activate_delayed(raid5_conf_t *conf)
3384 {
3385         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3386                 while (!list_empty(&conf->delayed_list)) {
3387                         struct list_head *l = conf->delayed_list.next;
3388                         struct stripe_head *sh;
3389                         sh = list_entry(l, struct stripe_head, lru);
3390                         list_del_init(l);
3391                         clear_bit(STRIPE_DELAYED, &sh->state);
3392                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3393                                 atomic_inc(&conf->preread_active_stripes);
3394                         list_add_tail(&sh->lru, &conf->hold_list);
3395                 }
3396         }
3397 }
3398
3399 static void activate_bit_delay(raid5_conf_t *conf)
3400 {
3401         /* device_lock is held */
3402         struct list_head head;
3403         list_add(&head, &conf->bitmap_list);
3404         list_del_init(&conf->bitmap_list);
3405         while (!list_empty(&head)) {
3406                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3407                 list_del_init(&sh->lru);
3408                 atomic_inc(&sh->count);
3409                 __release_stripe(conf, sh);
3410         }
3411 }
3412
3413 int md_raid5_congested(mddev_t *mddev, int bits)
3414 {
3415         raid5_conf_t *conf = mddev->private;
3416
3417         /* No difference between reads and writes.  Just check
3418          * how busy the stripe_cache is
3419          */
3420
3421         if (conf->inactive_blocked)
3422                 return 1;
3423         if (conf->quiesce)
3424                 return 1;
3425         if (list_empty_careful(&conf->inactive_list))
3426                 return 1;
3427
3428         return 0;
3429 }
3430 EXPORT_SYMBOL_GPL(md_raid5_congested);
3431
3432 static int raid5_congested(void *data, int bits)
3433 {
3434         mddev_t *mddev = data;
3435
3436         return mddev_congested(mddev, bits) ||
3437                 md_raid5_congested(mddev, bits);
3438 }
3439
3440 /* We want read requests to align with chunks where possible,
3441  * but write requests don't need to.
3442  */
3443 static int raid5_mergeable_bvec(struct request_queue *q,
3444                                 struct bvec_merge_data *bvm,
3445                                 struct bio_vec *biovec)
3446 {
3447         mddev_t *mddev = q->queuedata;
3448         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3449         int max;
3450         unsigned int chunk_sectors = mddev->chunk_sectors;
3451         unsigned int bio_sectors = bvm->bi_size >> 9;
3452
3453         if ((bvm->bi_rw & 1) == WRITE)
3454                 return biovec->bv_len; /* always allow writes to be mergeable */
3455
3456         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3457                 chunk_sectors = mddev->new_chunk_sectors;
3458         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3459         if (max < 0) max = 0;
3460         if (max <= biovec->bv_len && bio_sectors == 0)
3461                 return biovec->bv_len;
3462         else
3463                 return max;
3464 }
3465
3466
3467 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3468 {
3469         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3470         unsigned int chunk_sectors = mddev->chunk_sectors;
3471         unsigned int bio_sectors = bio->bi_size >> 9;
3472
3473         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3474                 chunk_sectors = mddev->new_chunk_sectors;
3475         return  chunk_sectors >=
3476                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3477 }
3478
3479 /*
3480  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3481  *  later sampled by raid5d.
3482  */
3483 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3484 {
3485         unsigned long flags;
3486
3487         spin_lock_irqsave(&conf->device_lock, flags);
3488
3489         bi->bi_next = conf->retry_read_aligned_list;
3490         conf->retry_read_aligned_list = bi;
3491
3492         spin_unlock_irqrestore(&conf->device_lock, flags);
3493         md_wakeup_thread(conf->mddev->thread);
3494 }
3495
3496
3497 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3498 {
3499         struct bio *bi;
3500
3501         bi = conf->retry_read_aligned;
3502         if (bi) {
3503                 conf->retry_read_aligned = NULL;
3504                 return bi;
3505         }
3506         bi = conf->retry_read_aligned_list;
3507         if(bi) {
3508                 conf->retry_read_aligned_list = bi->bi_next;
3509                 bi->bi_next = NULL;
3510                 /*
3511                  * this sets the active strip count to 1 and the processed
3512                  * strip count to zero (upper 8 bits)
3513                  */
3514                 bi->bi_phys_segments = 1; /* biased count of active stripes */
3515         }
3516
3517         return bi;
3518 }
3519
3520
3521 /*
3522  *  The "raid5_align_endio" should check if the read succeeded and if it
3523  *  did, call bio_endio on the original bio (having bio_put the new bio
3524  *  first).
3525  *  If the read failed..
3526  */
3527 static void raid5_align_endio(struct bio *bi, int error)
3528 {
3529         struct bio* raid_bi  = bi->bi_private;
3530         mddev_t *mddev;
3531         raid5_conf_t *conf;
3532         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3533         mdk_rdev_t *rdev;
3534
3535         bio_put(bi);
3536
3537         rdev = (void*)raid_bi->bi_next;
3538         raid_bi->bi_next = NULL;
3539         mddev = rdev->mddev;
3540         conf = mddev->private;
3541
3542         rdev_dec_pending(rdev, conf->mddev);
3543
3544         if (!error && uptodate) {
3545                 bio_endio(raid_bi, 0);
3546                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3547                         wake_up(&conf->wait_for_stripe);
3548                 return;
3549         }
3550
3551
3552         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3553
3554         add_bio_to_retry(raid_bi, conf);
3555 }
3556
3557 static int bio_fits_rdev(struct bio *bi)
3558 {
3559         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3560
3561         if ((bi->bi_size>>9) > queue_max_sectors(q))
3562                 return 0;
3563         blk_recount_segments(q, bi);
3564         if (bi->bi_phys_segments > queue_max_segments(q))
3565                 return 0;
3566
3567         if (q->merge_bvec_fn)
3568                 /* it's too hard to apply the merge_bvec_fn at this stage,
3569                  * just just give up
3570                  */
3571                 return 0;
3572
3573         return 1;
3574 }
3575
3576
3577 static int chunk_aligned_read(mddev_t *mddev, struct bio * raid_bio)
3578 {
3579         raid5_conf_t *conf = mddev->private;
3580         int dd_idx;
3581         struct bio* align_bi;
3582         mdk_rdev_t *rdev;
3583
3584         if (!in_chunk_boundary(mddev, raid_bio)) {
3585                 pr_debug("chunk_aligned_read : non aligned\n");
3586                 return 0;
3587         }
3588         /*
3589          * use bio_clone_mddev to make a copy of the bio
3590          */
3591         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3592         if (!align_bi)
3593                 return 0;
3594         /*
3595          *   set bi_end_io to a new function, and set bi_private to the
3596          *     original bio.
3597          */
3598         align_bi->bi_end_io  = raid5_align_endio;
3599         align_bi->bi_private = raid_bio;
3600         /*
3601          *      compute position
3602          */
3603         align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
3604                                                     0,
3605                                                     &dd_idx, NULL);
3606
3607         rcu_read_lock();
3608         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3609         if (rdev && test_bit(In_sync, &rdev->flags)) {
3610                 sector_t first_bad;
3611                 int bad_sectors;
3612
3613                 atomic_inc(&rdev->nr_pending);
3614                 rcu_read_unlock();
3615                 raid_bio->bi_next = (void*)rdev;
3616                 align_bi->bi_bdev =  rdev->bdev;
3617                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3618                 align_bi->bi_sector += rdev->data_offset;
3619
3620                 if (!bio_fits_rdev(align_bi) ||
3621                     is_badblock(rdev, align_bi->bi_sector, align_bi->bi_size>>9,
3622                                 &first_bad, &bad_sectors)) {
3623                         /* too big in some way, or has a known bad block */
3624                         bio_put(align_bi);
3625                         rdev_dec_pending(rdev, mddev);
3626                         return 0;
3627                 }
3628
3629                 spin_lock_irq(&conf->device_lock);
3630                 wait_event_lock_irq(conf->wait_for_stripe,
3631                                     conf->quiesce == 0,
3632                                     conf->device_lock, /* nothing */);
3633                 atomic_inc(&conf->active_aligned_reads);
3634                 spin_unlock_irq(&conf->device_lock);
3635
3636                 generic_make_request(align_bi);
3637                 return 1;
3638         } else {
3639                 rcu_read_unlock();
3640                 bio_put(align_bi);
3641                 return 0;
3642         }
3643 }
3644
3645 /* __get_priority_stripe - get the next stripe to process
3646  *
3647  * Full stripe writes are allowed to pass preread active stripes up until
3648  * the bypass_threshold is exceeded.  In general the bypass_count
3649  * increments when the handle_list is handled before the hold_list; however, it
3650  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
3651  * stripe with in flight i/o.  The bypass_count will be reset when the
3652  * head of the hold_list has changed, i.e. the head was promoted to the
3653  * handle_list.
3654  */
3655 static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
3656 {
3657         struct stripe_head *sh;
3658
3659         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
3660                   __func__,
3661                   list_empty(&conf->handle_list) ? "empty" : "busy",
3662                   list_empty(&conf->hold_list) ? "empty" : "busy",
3663                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
3664
3665         if (!list_empty(&conf->handle_list)) {
3666                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
3667
3668                 if (list_empty(&conf->hold_list))
3669                         conf->bypass_count = 0;
3670                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
3671                         if (conf->hold_list.next == conf->last_hold)
3672                                 conf->bypass_count++;
3673                         else {
3674                                 conf->last_hold = conf->hold_list.next;
3675                                 conf->bypass_count -= conf->bypass_threshold;
3676                                 if (conf->bypass_count < 0)
3677                                         conf->bypass_count = 0;
3678                         }
3679                 }
3680         } else if (!list_empty(&conf->hold_list) &&
3681                    ((conf->bypass_threshold &&
3682                      conf->bypass_count > conf->bypass_threshold) ||
3683                     atomic_read(&conf->pending_full_writes) == 0)) {
3684                 sh = list_entry(conf->hold_list.next,
3685                                 typeof(*sh), lru);
3686                 conf->bypass_count -= conf->bypass_threshold;
3687                 if (conf->bypass_count < 0)
3688                         conf->bypass_count = 0;
3689         } else
3690                 return NULL;
3691
3692         list_del_init(&sh->lru);
3693         atomic_inc(&sh->count);
3694         BUG_ON(atomic_read(&sh->count) != 1);
3695         return sh;
3696 }
3697
3698 static int make_request(mddev_t *mddev, struct bio * bi)
3699 {
3700         raid5_conf_t *conf = mddev->private;
3701         int dd_idx;
3702         sector_t new_sector;
3703         sector_t logical_sector, last_sector;
3704         struct stripe_head *sh;
3705         const int rw = bio_data_dir(bi);
3706         int remaining;
3707         int plugged;
3708
3709         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
3710                 md_flush_request(mddev, bi);
3711                 return 0;
3712         }
3713
3714         md_write_start(mddev, bi);
3715
3716         if (rw == READ &&
3717              mddev->reshape_position == MaxSector &&
3718              chunk_aligned_read(mddev,bi))
3719                 return 0;
3720
3721         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3722         last_sector = bi->bi_sector + (bi->bi_size>>9);
3723         bi->bi_next = NULL;
3724         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
3725
3726         plugged = mddev_check_plugged(mddev);
3727         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
3728                 DEFINE_WAIT(w);
3729                 int disks, data_disks;
3730                 int previous;
3731
3732         retry:
3733                 previous = 0;
3734                 disks = conf->raid_disks;
3735                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
3736                 if (unlikely(conf->reshape_progress != MaxSector)) {
3737                         /* spinlock is needed as reshape_progress may be
3738                          * 64bit on a 32bit platform, and so it might be
3739                          * possible to see a half-updated value
3740                          * Of course reshape_progress could change after
3741                          * the lock is dropped, so once we get a reference
3742                          * to the stripe that we think it is, we will have
3743                          * to check again.
3744                          */
3745                         spin_lock_irq(&conf->device_lock);
3746                         if (mddev->delta_disks < 0
3747                             ? logical_sector < conf->reshape_progress
3748                             : logical_sector >= conf->reshape_progress) {
3749                                 disks = conf->previous_raid_disks;
3750                                 previous = 1;
3751                         } else {
3752                                 if (mddev->delta_disks < 0
3753                                     ? logical_sector < conf->reshape_safe
3754                                     : logical_sector >= conf->reshape_safe) {
3755                                         spin_unlock_irq(&conf->device_lock);
3756                                         schedule();
3757                                         goto retry;
3758                                 }
3759                         }
3760                         spin_unlock_irq(&conf->device_lock);
3761                 }
3762                 data_disks = disks - conf->max_degraded;
3763
3764                 new_sector = raid5_compute_sector(conf, logical_sector,
3765                                                   previous,
3766                                                   &dd_idx, NULL);
3767                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
3768                         (unsigned long long)new_sector, 
3769                         (unsigned long long)logical_sector);
3770
3771                 sh = get_active_stripe(conf, new_sector, previous,
3772                                        (bi->bi_rw&RWA_MASK), 0);
3773                 if (sh) {
3774                         if (unlikely(previous)) {
3775                                 /* expansion might have moved on while waiting for a
3776                                  * stripe, so we must do the range check again.
3777                                  * Expansion could still move past after this
3778                                  * test, but as we are holding a reference to
3779                                  * 'sh', we know that if that happens,
3780                                  *  STRIPE_EXPANDING will get set and the expansion
3781                                  * won't proceed until we finish with the stripe.
3782                                  */
3783                                 int must_retry = 0;
3784                                 spin_lock_irq(&conf->device_lock);
3785                                 if (mddev->delta_disks < 0
3786                                     ? logical_sector >= conf->reshape_progress
3787                                     : logical_sector < conf->reshape_progress)
3788                                         /* mismatch, need to try again */
3789                                         must_retry = 1;
3790                                 spin_unlock_irq(&conf->device_lock);
3791                                 if (must_retry) {
3792                                         release_stripe(sh);
3793                                         schedule();
3794                                         goto retry;
3795                                 }
3796                         }
3797
3798                         if (rw == WRITE &&
3799                             logical_sector >= mddev->suspend_lo &&
3800                             logical_sector < mddev->suspend_hi) {
3801                                 release_stripe(sh);
3802                                 /* As the suspend_* range is controlled by
3803                                  * userspace, we want an interruptible
3804                                  * wait.
3805                                  */
3806                                 flush_signals(current);
3807                                 prepare_to_wait(&conf->wait_for_overlap,
3808                                                 &w, TASK_INTERRUPTIBLE);
3809                                 if (logical_sector >= mddev->suspend_lo &&
3810                                     logical_sector < mddev->suspend_hi)
3811                                         schedule();
3812                                 goto retry;
3813                         }
3814
3815                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
3816                             !add_stripe_bio(sh, bi, dd_idx, rw)) {
3817                                 /* Stripe is busy expanding or
3818                                  * add failed due to overlap.  Flush everything
3819                                  * and wait a while
3820                                  */
3821                                 md_wakeup_thread(mddev->thread);
3822                                 release_stripe(sh);
3823                                 schedule();
3824                                 goto retry;
3825                         }
3826                         finish_wait(&conf->wait_for_overlap, &w);
3827                         set_bit(STRIPE_HANDLE, &sh->state);
3828                         clear_bit(STRIPE_DELAYED, &sh->state);
3829                         if ((bi->bi_rw & REQ_SYNC) &&
3830                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3831                                 atomic_inc(&conf->preread_active_stripes);
3832                         release_stripe(sh);
3833                 } else {
3834                         /* cannot get stripe for read-ahead, just give-up */
3835                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3836                         finish_wait(&conf->wait_for_overlap, &w);
3837                         break;
3838                 }
3839                         
3840         }
3841         if (!plugged)
3842                 md_wakeup_thread(mddev->thread);
3843
3844         spin_lock_irq(&conf->device_lock);
3845         remaining = raid5_dec_bi_phys_segments(bi);
3846         spin_unlock_irq(&conf->device_lock);
3847         if (remaining == 0) {
3848
3849                 if ( rw == WRITE )
3850                         md_write_end(mddev);
3851
3852                 bio_endio(bi, 0);
3853         }
3854
3855         return 0;
3856 }
3857
3858 static sector_t raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks);
3859
3860 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
3861 {
3862         /* reshaping is quite different to recovery/resync so it is
3863          * handled quite separately ... here.
3864          *
3865          * On each call to sync_request, we gather one chunk worth of
3866          * destination stripes and flag them as expanding.
3867          * Then we find all the source stripes and request reads.
3868          * As the reads complete, handle_stripe will copy the data
3869          * into the destination stripe and release that stripe.
3870          */
3871         raid5_conf_t *conf = mddev->private;
3872         struct stripe_head *sh;
3873         sector_t first_sector, last_sector;
3874         int raid_disks = conf->previous_raid_disks;
3875         int data_disks = raid_disks - conf->max_degraded;
3876         int new_data_disks = conf->raid_disks - conf->max_degraded;
3877         int i;
3878         int dd_idx;
3879         sector_t writepos, readpos, safepos;
3880         sector_t stripe_addr;
3881         int reshape_sectors;
3882         struct list_head stripes;
3883
3884         if (sector_nr == 0) {
3885                 /* If restarting in the middle, skip the initial sectors */
3886                 if (mddev->delta_disks < 0 &&
3887                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
3888                         sector_nr = raid5_size(mddev, 0, 0)
3889                                 - conf->reshape_progress;
3890                 } else if (mddev->delta_disks >= 0 &&
3891                            conf->reshape_progress > 0)
3892                         sector_nr = conf->reshape_progress;
3893                 sector_div(sector_nr, new_data_disks);
3894                 if (sector_nr) {
3895                         mddev->curr_resync_completed = sector_nr;
3896                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
3897                         *skipped = 1;
3898                         return sector_nr;
3899                 }
3900         }
3901
3902         /* We need to process a full chunk at a time.
3903          * If old and new chunk sizes differ, we need to process the
3904          * largest of these
3905          */
3906         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
3907                 reshape_sectors = mddev->new_chunk_sectors;
3908         else
3909                 reshape_sectors = mddev->chunk_sectors;
3910
3911         /* we update the metadata when there is more than 3Meg
3912          * in the block range (that is rather arbitrary, should
3913          * probably be time based) or when the data about to be
3914          * copied would over-write the source of the data at
3915          * the front of the range.
3916          * i.e. one new_stripe along from reshape_progress new_maps
3917          * to after where reshape_safe old_maps to
3918          */
3919         writepos = conf->reshape_progress;
3920         sector_div(writepos, new_data_disks);
3921         readpos = conf->reshape_progress;
3922         sector_div(readpos, data_disks);
3923         safepos = conf->reshape_safe;
3924         sector_div(safepos, data_disks);
3925         if (mddev->delta_disks < 0) {
3926                 writepos -= min_t(sector_t, reshape_sectors, writepos);
3927                 readpos += reshape_sectors;
3928                 safepos += reshape_sectors;
3929         } else {
3930                 writepos += reshape_sectors;
3931                 readpos -= min_t(sector_t, reshape_sectors, readpos);
3932                 safepos -= min_t(sector_t, reshape_sectors, safepos);
3933         }
3934
3935         /* 'writepos' is the most advanced device address we might write.
3936          * 'readpos' is the least advanced device address we might read.
3937          * 'safepos' is the least address recorded in the metadata as having
3938          *     been reshaped.
3939          * If 'readpos' is behind 'writepos', then there is no way that we can
3940          * ensure safety in the face of a crash - that must be done by userspace
3941          * making a backup of the data.  So in that case there is no particular
3942          * rush to update metadata.
3943          * Otherwise if 'safepos' is behind 'writepos', then we really need to
3944          * update the metadata to advance 'safepos' to match 'readpos' so that
3945          * we can be safe in the event of a crash.
3946          * So we insist on updating metadata if safepos is behind writepos and
3947          * readpos is beyond writepos.
3948          * In any case, update the metadata every 10 seconds.
3949          * Maybe that number should be configurable, but I'm not sure it is
3950          * worth it.... maybe it could be a multiple of safemode_delay???
3951          */
3952         if ((mddev->delta_disks < 0
3953              ? (safepos > writepos && readpos < writepos)
3954              : (safepos < writepos && readpos > writepos)) ||
3955             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
3956                 /* Cannot proceed until we've updated the superblock... */
3957                 wait_event(conf->wait_for_overlap,
3958                            atomic_read(&conf->reshape_stripes)==0);
3959                 mddev->reshape_position = conf->reshape_progress;
3960                 mddev->curr_resync_completed = sector_nr;
3961                 conf->reshape_checkpoint = jiffies;
3962                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3963                 md_wakeup_thread(mddev->thread);
3964                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
3965                            kthread_should_stop());
3966                 spin_lock_irq(&conf->device_lock);
3967                 conf->reshape_safe = mddev->reshape_position;
3968                 spin_unlock_irq(&conf->device_lock);
3969                 wake_up(&conf->wait_for_overlap);
3970                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
3971         }
3972
3973         if (mddev->delta_disks < 0) {
3974                 BUG_ON(conf->reshape_progress == 0);
3975                 stripe_addr = writepos;
3976                 BUG_ON((mddev->dev_sectors &
3977                         ~((sector_t)reshape_sectors - 1))
3978                        - reshape_sectors - stripe_addr
3979                        != sector_nr);
3980         } else {
3981                 BUG_ON(writepos != sector_nr + reshape_sectors);
3982                 stripe_addr = sector_nr;
3983         }
3984         INIT_LIST_HEAD(&stripes);
3985         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
3986                 int j;
3987                 int skipped_disk = 0;
3988                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
3989                 set_bit(STRIPE_EXPANDING, &sh->state);
3990                 atomic_inc(&conf->reshape_stripes);
3991                 /* If any of this stripe is beyond the end of the old
3992                  * array, then we need to zero those blocks
3993                  */
3994                 for (j=sh->disks; j--;) {
3995                         sector_t s;
3996                         if (j == sh->pd_idx)
3997                                 continue;
3998                         if (conf->level == 6 &&
3999                             j == sh->qd_idx)
4000                                 continue;
4001                         s = compute_blocknr(sh, j, 0);
4002                         if (s < raid5_size(mddev, 0, 0)) {
4003                                 skipped_disk = 1;
4004                                 continue;
4005                         }
4006                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4007                         set_bit(R5_Expanded, &sh->dev[j].flags);
4008                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
4009                 }
4010                 if (!skipped_disk) {
4011                         set_bit(STRIPE_EXPAND_READY, &sh->state);
4012                         set_bit(STRIPE_HANDLE, &sh->state);
4013                 }
4014                 list_add(&sh->lru, &stripes);
4015         }
4016         spin_lock_irq(&conf->device_lock);
4017         if (mddev->delta_disks < 0)
4018                 conf->reshape_progress -= reshape_sectors * new_data_disks;
4019         else
4020                 conf->reshape_progress += reshape_sectors * new_data_disks;
4021         spin_unlock_irq(&conf->device_lock);
4022         /* Ok, those stripe are ready. We can start scheduling
4023          * reads on the source stripes.
4024          * The source stripes are determined by mapping the first and last
4025          * block on the destination stripes.
4026          */
4027         first_sector =
4028                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4029                                      1, &dd_idx, NULL);
4030         last_sector =
4031                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4032                                             * new_data_disks - 1),
4033                                      1, &dd_idx, NULL);
4034         if (last_sector >= mddev->dev_sectors)
4035                 last_sector = mddev->dev_sectors - 1;
4036         while (first_sector <= last_sector) {
4037                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4038                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4039                 set_bit(STRIPE_HANDLE, &sh->state);
4040                 release_stripe(sh);
4041                 first_sector += STRIPE_SECTORS;
4042         }
4043         /* Now that the sources are clearly marked, we can release
4044          * the destination stripes
4045          */
4046         while (!list_empty(&stripes)) {
4047                 sh = list_entry(stripes.next, struct stripe_head, lru);
4048                 list_del_init(&sh->lru);
4049                 release_stripe(sh);
4050         }
4051         /* If this takes us to the resync_max point where we have to pause,
4052          * then we need to write out the superblock.
4053          */
4054         sector_nr += reshape_sectors;
4055         if ((sector_nr - mddev->curr_resync_completed) * 2
4056             >= mddev->resync_max - mddev->curr_resync_completed) {
4057                 /* Cannot proceed until we've updated the superblock... */
4058                 wait_event(conf->wait_for_overlap,
4059                            atomic_read(&conf->reshape_stripes) == 0);
4060                 mddev->reshape_position = conf->reshape_progress;
4061                 mddev->curr_resync_completed = sector_nr;
4062                 conf->reshape_checkpoint = jiffies;
4063                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4064                 md_wakeup_thread(mddev->thread);
4065                 wait_event(mddev->sb_wait,
4066                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4067                            || kthread_should_stop());
4068                 spin_lock_irq(&conf->device_lock);
4069                 conf->reshape_safe = mddev->reshape_position;
4070                 spin_unlock_irq(&conf->device_lock);
4071                 wake_up(&conf->wait_for_overlap);
4072                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4073         }
4074         return reshape_sectors;
4075 }
4076
4077 /* FIXME go_faster isn't used */
4078 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
4079 {
4080         raid5_conf_t *conf = mddev->private;
4081         struct stripe_head *sh;
4082         sector_t max_sector = mddev->dev_sectors;
4083         sector_t sync_blocks;
4084         int still_degraded = 0;
4085         int i;
4086
4087         if (sector_nr >= max_sector) {
4088                 /* just being told to finish up .. nothing much to do */
4089
4090                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4091                         end_reshape(conf);
4092                         return 0;
4093                 }
4094
4095                 if (mddev->curr_resync < max_sector) /* aborted */
4096                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4097                                         &sync_blocks, 1);
4098                 else /* completed sync */
4099                         conf->fullsync = 0;
4100                 bitmap_close_sync(mddev->bitmap);
4101
4102                 return 0;
4103         }
4104
4105         /* Allow raid5_quiesce to complete */
4106         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4107
4108         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4109                 return reshape_request(mddev, sector_nr, skipped);
4110
4111         /* No need to check resync_max as we never do more than one
4112          * stripe, and as resync_max will always be on a chunk boundary,
4113          * if the check in md_do_sync didn't fire, there is no chance
4114          * of overstepping resync_max here
4115          */
4116
4117         /* if there is too many failed drives and we are trying
4118          * to resync, then assert that we are finished, because there is
4119          * nothing we can do.
4120          */
4121         if (mddev->degraded >= conf->max_degraded &&
4122             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4123                 sector_t rv = mddev->dev_sectors - sector_nr;
4124                 *skipped = 1;
4125                 return rv;
4126         }
4127         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4128             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4129             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
4130                 /* we can skip this block, and probably more */
4131                 sync_blocks /= STRIPE_SECTORS;
4132                 *skipped = 1;
4133                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4134         }
4135
4136
4137         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4138
4139         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4140         if (sh == NULL) {
4141                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4142                 /* make sure we don't swamp the stripe cache if someone else
4143                  * is trying to get access
4144                  */
4145                 schedule_timeout_uninterruptible(1);
4146         }
4147         /* Need to check if array will still be degraded after recovery/resync
4148          * We don't need to check the 'failed' flag as when that gets set,
4149          * recovery aborts.
4150          */
4151         for (i = 0; i < conf->raid_disks; i++)
4152                 if (conf->disks[i].rdev == NULL)
4153                         still_degraded = 1;
4154
4155         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4156
4157         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4158
4159         handle_stripe(sh);
4160         release_stripe(sh);
4161
4162         return STRIPE_SECTORS;
4163 }
4164
4165 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
4166 {
4167         /* We may not be able to submit a whole bio at once as there
4168          * may not be enough stripe_heads available.
4169          * We cannot pre-allocate enough stripe_heads as we may need
4170          * more than exist in the cache (if we allow ever large chunks).
4171          * So we do one stripe head at a time and record in
4172          * ->bi_hw_segments how many have been done.
4173          *
4174          * We *know* that this entire raid_bio is in one chunk, so
4175          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4176          */
4177         struct stripe_head *sh;
4178         int dd_idx;
4179         sector_t sector, logical_sector, last_sector;
4180         int scnt = 0;
4181         int remaining;
4182         int handled = 0;
4183
4184         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4185         sector = raid5_compute_sector(conf, logical_sector,
4186                                       0, &dd_idx, NULL);
4187         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4188
4189         for (; logical_sector < last_sector;
4190              logical_sector += STRIPE_SECTORS,
4191                      sector += STRIPE_SECTORS,
4192                      scnt++) {
4193
4194                 if (scnt < raid5_bi_hw_segments(raid_bio))
4195                         /* already done this stripe */
4196                         continue;
4197
4198                 sh = get_active_stripe(conf, sector, 0, 1, 0);
4199
4200                 if (!sh) {
4201                         /* failed to get a stripe - must wait */
4202                         raid5_set_bi_hw_segments(raid_bio, scnt);
4203                         conf->retry_read_aligned = raid_bio;
4204                         return handled;
4205                 }
4206
4207                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
4208                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4209                         release_stripe(sh);
4210                         raid5_set_bi_hw_segments(raid_bio, scnt);
4211                         conf->retry_read_aligned = raid_bio;
4212                         return handled;
4213                 }
4214
4215                 handle_stripe(sh);
4216                 release_stripe(sh);
4217                 handled++;
4218         }
4219         spin_lock_irq(&conf->device_lock);
4220         remaining = raid5_dec_bi_phys_segments(raid_bio);
4221         spin_unlock_irq(&conf->device_lock);
4222         if (remaining == 0)
4223                 bio_endio(raid_bio, 0);
4224         if (atomic_dec_and_test(&conf->active_aligned_reads))
4225                 wake_up(&conf->wait_for_stripe);
4226         return handled;
4227 }
4228
4229
4230 /*
4231  * This is our raid5 kernel thread.
4232  *
4233  * We scan the hash table for stripes which can be handled now.
4234  * During the scan, completed stripes are saved for us by the interrupt
4235  * handler, so that they will not have to wait for our next wakeup.
4236  */
4237 static void raid5d(mddev_t *mddev)
4238 {
4239         struct stripe_head *sh;
4240         raid5_conf_t *conf = mddev->private;
4241         int handled;
4242         struct blk_plug plug;
4243
4244         pr_debug("+++ raid5d active\n");
4245
4246         md_check_recovery(mddev);
4247
4248         blk_start_plug(&plug);
4249         handled = 0;
4250         spin_lock_irq(&conf->device_lock);
4251         while (1) {
4252                 struct bio *bio;
4253
4254                 if (atomic_read(&mddev->plug_cnt) == 0 &&
4255                     !list_empty(&conf->bitmap_list)) {
4256                         /* Now is a good time to flush some bitmap updates */
4257                         conf->seq_flush++;
4258                         spin_unlock_irq(&conf->device_lock);
4259                         bitmap_unplug(mddev->bitmap);
4260                         spin_lock_irq(&conf->device_lock);
4261                         conf->seq_write = conf->seq_flush;
4262                         activate_bit_delay(conf);
4263                 }
4264                 if (atomic_read(&mddev->plug_cnt) == 0)
4265                         raid5_activate_delayed(conf);
4266
4267                 while ((bio = remove_bio_from_retry(conf))) {
4268                         int ok;
4269                         spin_unlock_irq(&conf->device_lock);
4270                         ok = retry_aligned_read(conf, bio);
4271                         spin_lock_irq(&conf->device_lock);
4272                         if (!ok)
4273                                 break;
4274                         handled++;
4275                 }
4276
4277                 sh = __get_priority_stripe(conf);
4278
4279                 if (!sh)
4280                         break;
4281                 spin_unlock_irq(&conf->device_lock);
4282                 
4283                 handled++;
4284                 handle_stripe(sh);
4285                 release_stripe(sh);
4286                 cond_resched();
4287
4288                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
4289                         md_check_recovery(mddev);
4290
4291                 spin_lock_irq(&conf->device_lock);
4292         }
4293         pr_debug("%d stripes handled\n", handled);
4294
4295         spin_unlock_irq(&conf->device_lock);
4296
4297         async_tx_issue_pending_all();
4298         blk_finish_plug(&plug);
4299
4300         pr_debug("--- raid5d inactive\n");
4301 }
4302
4303 static ssize_t
4304 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
4305 {
4306         raid5_conf_t *conf = mddev->private;
4307         if (conf)
4308                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4309         else
4310                 return 0;
4311 }
4312
4313 int
4314 raid5_set_cache_size(mddev_t *mddev, int size)
4315 {
4316         raid5_conf_t *conf = mddev->private;
4317         int err;
4318
4319         if (size <= 16 || size > 32768)
4320                 return -EINVAL;
4321         while (size < conf->max_nr_stripes) {
4322                 if (drop_one_stripe(conf))
4323                         conf->max_nr_stripes--;
4324                 else
4325                         break;
4326         }
4327         err = md_allow_write(mddev);
4328         if (err)
4329                 return err;
4330         while (size > conf->max_nr_stripes) {
4331                 if (grow_one_stripe(conf))
4332                         conf->max_nr_stripes++;
4333                 else break;
4334         }
4335         return 0;
4336 }
4337 EXPORT_SYMBOL(raid5_set_cache_size);
4338
4339 static ssize_t
4340 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
4341 {
4342         raid5_conf_t *conf = mddev->private;
4343         unsigned long new;
4344         int err;
4345
4346         if (len >= PAGE_SIZE)
4347                 return -EINVAL;
4348         if (!conf)
4349                 return -ENODEV;
4350
4351         if (strict_strtoul(page, 10, &new))
4352                 return -EINVAL;
4353         err = raid5_set_cache_size(mddev, new);
4354         if (err)
4355                 return err;
4356         return len;
4357 }
4358
4359 static struct md_sysfs_entry
4360 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4361                                 raid5_show_stripe_cache_size,
4362                                 raid5_store_stripe_cache_size);
4363
4364 static ssize_t
4365 raid5_show_preread_threshold(mddev_t *mddev, char *page)
4366 {
4367         raid5_conf_t *conf = mddev->private;
4368         if (conf)
4369                 return sprintf(page, "%d\n", conf->bypass_threshold);
4370         else
4371                 return 0;
4372 }
4373
4374 static ssize_t
4375 raid5_store_preread_threshold(mddev_t *mddev, const char *page, size_t len)
4376 {
4377         raid5_conf_t *conf = mddev->private;
4378         unsigned long new;
4379         if (len >= PAGE_SIZE)
4380                 return -EINVAL;
4381         if (!conf)
4382                 return -ENODEV;
4383
4384         if (strict_strtoul(page, 10, &new))
4385                 return -EINVAL;
4386         if (new > conf->max_nr_stripes)
4387                 return -EINVAL;
4388         conf->bypass_threshold = new;
4389         return len;
4390 }
4391
4392 static struct md_sysfs_entry
4393 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4394                                         S_IRUGO | S_IWUSR,
4395                                         raid5_show_preread_threshold,
4396                                         raid5_store_preread_threshold);
4397
4398 static ssize_t
4399 stripe_cache_active_show(mddev_t *mddev, char *page)
4400 {
4401         raid5_conf_t *conf = mddev->private;
4402         if (conf)
4403                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4404         else
4405                 return 0;
4406 }
4407
4408 static struct md_sysfs_entry
4409 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4410
4411 static struct attribute *raid5_attrs[] =  {
4412         &raid5_stripecache_size.attr,
4413         &raid5_stripecache_active.attr,
4414         &raid5_preread_bypass_threshold.attr,
4415         NULL,
4416 };
4417 static struct attribute_group raid5_attrs_group = {
4418         .name = NULL,
4419         .attrs = raid5_attrs,
4420 };
4421
4422 static sector_t
4423 raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks)
4424 {
4425         raid5_conf_t *conf = mddev->private;
4426
4427         if (!sectors)
4428                 sectors = mddev->dev_sectors;
4429         if (!raid_disks)
4430                 /* size is defined by the smallest of previous and new size */
4431                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
4432
4433         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
4434         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
4435         return sectors * (raid_disks - conf->max_degraded);
4436 }
4437
4438 static void raid5_free_percpu(raid5_conf_t *conf)
4439 {
4440         struct raid5_percpu *percpu;
4441         unsigned long cpu;
4442
4443         if (!conf->percpu)
4444                 return;
4445
4446         get_online_cpus();
4447         for_each_possible_cpu(cpu) {
4448                 percpu = per_cpu_ptr(conf->percpu, cpu);
4449                 safe_put_page(percpu->spare_page);
4450                 kfree(percpu->scribble);
4451         }
4452 #ifdef CONFIG_HOTPLUG_CPU
4453         unregister_cpu_notifier(&conf->cpu_notify);
4454 #endif
4455         put_online_cpus();
4456
4457         free_percpu(conf->percpu);
4458 }
4459
4460 static void free_conf(raid5_conf_t *conf)
4461 {
4462         shrink_stripes(conf);
4463         raid5_free_percpu(conf);
4464         kfree(conf->disks);
4465         kfree(conf->stripe_hashtbl);
4466         kfree(conf);
4467 }
4468
4469 #ifdef CONFIG_HOTPLUG_CPU
4470 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
4471                               void *hcpu)
4472 {
4473         raid5_conf_t *conf = container_of(nfb, raid5_conf_t, cpu_notify);
4474         long cpu = (long)hcpu;
4475         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
4476
4477         switch (action) {
4478         case CPU_UP_PREPARE:
4479         case CPU_UP_PREPARE_FROZEN:
4480                 if (conf->level == 6 && !percpu->spare_page)
4481                         percpu->spare_page = alloc_page(GFP_KERNEL);
4482                 if (!percpu->scribble)
4483                         percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
4484
4485                 if (!percpu->scribble ||
4486                     (conf->level == 6 && !percpu->spare_page)) {
4487                         safe_put_page(percpu->spare_page);
4488                         kfree(percpu->scribble);
4489                         pr_err("%s: failed memory allocation for cpu%ld\n",
4490                                __func__, cpu);
4491                         return notifier_from_errno(-ENOMEM);
4492                 }
4493                 break;
4494         case CPU_DEAD:
4495         case CPU_DEAD_FROZEN:
4496                 safe_put_page(percpu->spare_page);
4497                 kfree(percpu->scribble);
4498                 percpu->spare_page = NULL;
4499                 percpu->scribble = NULL;
4500                 break;
4501         default:
4502                 break;
4503         }
4504         return NOTIFY_OK;
4505 }
4506 #endif
4507
4508 static int raid5_alloc_percpu(raid5_conf_t *conf)
4509 {
4510         unsigned long cpu;
4511         struct page *spare_page;
4512         struct raid5_percpu __percpu *allcpus;
4513         void *scribble;
4514         int err;
4515
4516         allcpus = alloc_percpu(struct raid5_percpu);
4517         if (!allcpus)
4518                 return -ENOMEM;
4519         conf->percpu = allcpus;
4520
4521         get_online_cpus();
4522         err = 0;
4523         for_each_present_cpu(cpu) {
4524                 if (conf->level == 6) {
4525                         spare_page = alloc_page(GFP_KERNEL);
4526                         if (!spare_page) {
4527                                 err = -ENOMEM;
4528                                 break;
4529                         }
4530                         per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
4531                 }
4532                 scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
4533                 if (!scribble) {
4534                         err = -ENOMEM;
4535                         break;
4536                 }
4537                 per_cpu_ptr(conf->percpu, cpu)->scribble = scribble;
4538         }
4539 #ifdef CONFIG_HOTPLUG_CPU
4540         conf->cpu_notify.notifier_call = raid456_cpu_notify;
4541         conf->cpu_notify.priority = 0;
4542         if (err == 0)
4543                 err = register_cpu_notifier(&conf->cpu_notify);
4544 #endif
4545         put_online_cpus();
4546
4547         return err;
4548 }
4549
4550 static raid5_conf_t *setup_conf(mddev_t *mddev)
4551 {
4552         raid5_conf_t *conf;
4553         int raid_disk, memory, max_disks;
4554         mdk_rdev_t *rdev;
4555         struct disk_info *disk;
4556
4557         if (mddev->new_level != 5
4558             && mddev->new_level != 4
4559             && mddev->new_level != 6) {
4560                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
4561                        mdname(mddev), mddev->new_level);
4562                 return ERR_PTR(-EIO);
4563         }
4564         if ((mddev->new_level == 5
4565              && !algorithm_valid_raid5(mddev->new_layout)) ||
4566             (mddev->new_level == 6
4567              && !algorithm_valid_raid6(mddev->new_layout))) {
4568                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
4569                        mdname(mddev), mddev->new_layout);
4570                 return ERR_PTR(-EIO);
4571         }
4572         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
4573                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
4574                        mdname(mddev), mddev->raid_disks);
4575                 return ERR_PTR(-EINVAL);
4576         }
4577
4578         if (!mddev->new_chunk_sectors ||
4579             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
4580             !is_power_of_2(mddev->new_chunk_sectors)) {
4581                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
4582                        mdname(mddev), mddev->new_chunk_sectors << 9);
4583                 return ERR_PTR(-EINVAL);
4584         }
4585
4586         conf = kzalloc(sizeof(raid5_conf_t), GFP_KERNEL);
4587         if (conf == NULL)
4588                 goto abort;
4589         spin_lock_init(&conf->device_lock);
4590         init_waitqueue_head(&conf->wait_for_stripe);
4591         init_waitqueue_head(&conf->wait_for_overlap);
4592         INIT_LIST_HEAD(&conf->handle_list);
4593         INIT_LIST_HEAD(&conf->hold_list);
4594         INIT_LIST_HEAD(&conf->delayed_list);
4595         INIT_LIST_HEAD(&conf->bitmap_list);
4596         INIT_LIST_HEAD(&conf->inactive_list);
4597         atomic_set(&conf->active_stripes, 0);
4598         atomic_set(&conf->preread_active_stripes, 0);
4599         atomic_set(&conf->active_aligned_reads, 0);
4600         conf->bypass_threshold = BYPASS_THRESHOLD;
4601
4602         conf->raid_disks = mddev->raid_disks;
4603         if (mddev->reshape_position == MaxSector)
4604                 conf->previous_raid_disks = mddev->raid_disks;
4605         else
4606                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4607         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
4608         conf->scribble_len = scribble_len(max_disks);
4609
4610         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
4611                               GFP_KERNEL);
4612         if (!conf->disks)
4613                 goto abort;
4614
4615         conf->mddev = mddev;
4616
4617         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4618                 goto abort;
4619
4620         conf->level = mddev->new_level;
4621         if (raid5_alloc_percpu(conf) != 0)
4622                 goto abort;
4623
4624         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
4625
4626         list_for_each_entry(rdev, &mddev->disks, same_set) {
4627                 raid_disk = rdev->raid_disk;
4628                 if (raid_disk >= max_disks
4629                     || raid_disk < 0)
4630                         continue;
4631                 disk = conf->disks + raid_disk;
4632
4633                 disk->rdev = rdev;
4634
4635                 if (test_bit(In_sync, &rdev->flags)) {
4636                         char b[BDEVNAME_SIZE];
4637                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
4638                                " disk %d\n",
4639                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
4640                 } else if (rdev->saved_raid_disk != raid_disk)
4641                         /* Cannot rely on bitmap to complete recovery */
4642                         conf->fullsync = 1;
4643         }
4644
4645         conf->chunk_sectors = mddev->new_chunk_sectors;
4646         conf->level = mddev->new_level;
4647         if (conf->level == 6)
4648                 conf->max_degraded = 2;
4649         else
4650                 conf->max_degraded = 1;
4651         conf->algorithm = mddev->new_layout;
4652         conf->max_nr_stripes = NR_STRIPES;
4653         conf->reshape_progress = mddev->reshape_position;
4654         if (conf->reshape_progress != MaxSector) {
4655                 conf->prev_chunk_sectors = mddev->chunk_sectors;
4656                 conf->prev_algo = mddev->layout;
4657         }
4658
4659         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4660                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4661         if (grow_stripes(conf, conf->max_nr_stripes)) {
4662                 printk(KERN_ERR
4663                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
4664                        mdname(mddev), memory);
4665                 goto abort;
4666         } else
4667                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
4668                        mdname(mddev), memory);
4669
4670         conf->thread = md_register_thread(raid5d, mddev, NULL);
4671         if (!conf->thread) {
4672                 printk(KERN_ERR
4673                        "md/raid:%s: couldn't allocate thread.\n",
4674                        mdname(mddev));
4675                 goto abort;
4676         }
4677
4678         return conf;
4679
4680  abort:
4681         if (conf) {
4682                 free_conf(conf);
4683                 return ERR_PTR(-EIO);
4684         } else
4685                 return ERR_PTR(-ENOMEM);
4686 }
4687
4688
4689 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
4690 {
4691         switch (algo) {
4692         case ALGORITHM_PARITY_0:
4693                 if (raid_disk < max_degraded)
4694                         return 1;
4695                 break;
4696         case ALGORITHM_PARITY_N:
4697                 if (raid_disk >= raid_disks - max_degraded)
4698                         return 1;
4699                 break;
4700         case ALGORITHM_PARITY_0_6:
4701                 if (raid_disk == 0 || 
4702                     raid_disk == raid_disks - 1)
4703                         return 1;
4704                 break;
4705         case ALGORITHM_LEFT_ASYMMETRIC_6:
4706         case ALGORITHM_RIGHT_ASYMMETRIC_6:
4707         case ALGORITHM_LEFT_SYMMETRIC_6:
4708         case ALGORITHM_RIGHT_SYMMETRIC_6:
4709                 if (raid_disk == raid_disks - 1)
4710                         return 1;
4711         }
4712         return 0;
4713 }
4714
4715 static int run(mddev_t *mddev)
4716 {
4717         raid5_conf_t *conf;
4718         int working_disks = 0;
4719         int dirty_parity_disks = 0;
4720         mdk_rdev_t *rdev;
4721         sector_t reshape_offset = 0;
4722
4723         if (mddev->recovery_cp != MaxSector)
4724                 printk(KERN_NOTICE "md/raid:%s: not clean"
4725                        " -- starting background reconstruction\n",
4726                        mdname(mddev));
4727         if (mddev->reshape_position != MaxSector) {
4728                 /* Check that we can continue the reshape.
4729                  * Currently only disks can change, it must
4730                  * increase, and we must be past the point where
4731                  * a stripe over-writes itself
4732                  */
4733                 sector_t here_new, here_old;
4734                 int old_disks;
4735                 int max_degraded = (mddev->level == 6 ? 2 : 1);
4736
4737                 if (mddev->new_level != mddev->level) {
4738                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
4739                                "required - aborting.\n",
4740                                mdname(mddev));
4741                         return -EINVAL;
4742                 }
4743                 old_disks = mddev->raid_disks - mddev->delta_disks;
4744                 /* reshape_position must be on a new-stripe boundary, and one
4745                  * further up in new geometry must map after here in old
4746                  * geometry.
4747                  */
4748                 here_new = mddev->reshape_position;
4749                 if (sector_div(here_new, mddev->new_chunk_sectors *
4750                                (mddev->raid_disks - max_degraded))) {
4751                         printk(KERN_ERR "md/raid:%s: reshape_position not "
4752                                "on a stripe boundary\n", mdname(mddev));
4753                         return -EINVAL;
4754                 }
4755                 reshape_offset = here_new * mddev->new_chunk_sectors;
4756                 /* here_new is the stripe we will write to */
4757                 here_old = mddev->reshape_position;
4758                 sector_div(here_old, mddev->chunk_sectors *
4759                            (old_disks-max_degraded));
4760                 /* here_old is the first stripe that we might need to read
4761                  * from */
4762                 if (mddev->delta_disks == 0) {
4763                         /* We cannot be sure it is safe to start an in-place
4764                          * reshape.  It is only safe if user-space if monitoring
4765                          * and taking constant backups.
4766                          * mdadm always starts a situation like this in
4767                          * readonly mode so it can take control before
4768                          * allowing any writes.  So just check for that.
4769                          */
4770                         if ((here_new * mddev->new_chunk_sectors != 
4771                              here_old * mddev->chunk_sectors) ||
4772                             mddev->ro == 0) {
4773                                 printk(KERN_ERR "md/raid:%s: in-place reshape must be started"
4774                                        " in read-only mode - aborting\n",
4775                                        mdname(mddev));
4776                                 return -EINVAL;
4777                         }
4778                 } else if (mddev->delta_disks < 0
4779                     ? (here_new * mddev->new_chunk_sectors <=
4780                        here_old * mddev->chunk_sectors)
4781                     : (here_new * mddev->new_chunk_sectors >=
4782                        here_old * mddev->chunk_sectors)) {
4783                         /* Reading from the same stripe as writing to - bad */
4784                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
4785                                "auto-recovery - aborting.\n",
4786                                mdname(mddev));
4787                         return -EINVAL;
4788                 }
4789                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
4790                        mdname(mddev));
4791                 /* OK, we should be able to continue; */
4792         } else {
4793                 BUG_ON(mddev->level != mddev->new_level);
4794                 BUG_ON(mddev->layout != mddev->new_layout);
4795                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
4796                 BUG_ON(mddev->delta_disks != 0);
4797         }
4798
4799         if (mddev->private == NULL)
4800                 conf = setup_conf(mddev);
4801         else
4802                 conf = mddev->private;
4803
4804         if (IS_ERR(conf))
4805                 return PTR_ERR(conf);
4806
4807         mddev->thread = conf->thread;
4808         conf->thread = NULL;
4809         mddev->private = conf;
4810
4811         /*
4812          * 0 for a fully functional array, 1 or 2 for a degraded array.
4813          */
4814         list_for_each_entry(rdev, &mddev->disks, same_set) {
4815                 if (rdev->raid_disk < 0)
4816                         continue;
4817                 if (test_bit(In_sync, &rdev->flags)) {
4818                         working_disks++;
4819                         continue;
4820                 }
4821                 /* This disc is not fully in-sync.  However if it
4822                  * just stored parity (beyond the recovery_offset),
4823                  * when we don't need to be concerned about the
4824                  * array being dirty.
4825                  * When reshape goes 'backwards', we never have
4826                  * partially completed devices, so we only need
4827                  * to worry about reshape going forwards.
4828                  */
4829                 /* Hack because v0.91 doesn't store recovery_offset properly. */
4830                 if (mddev->major_version == 0 &&
4831                     mddev->minor_version > 90)
4832                         rdev->recovery_offset = reshape_offset;
4833                         
4834                 if (rdev->recovery_offset < reshape_offset) {
4835                         /* We need to check old and new layout */
4836                         if (!only_parity(rdev->raid_disk,
4837                                          conf->algorithm,
4838                                          conf->raid_disks,
4839                                          conf->max_degraded))
4840                                 continue;
4841                 }
4842                 if (!only_parity(rdev->raid_disk,
4843                                  conf->prev_algo,
4844                                  conf->previous_raid_disks,
4845                                  conf->max_degraded))
4846                         continue;
4847                 dirty_parity_disks++;
4848         }
4849
4850         mddev->degraded = (max(conf->raid_disks, conf->previous_raid_disks)
4851                            - working_disks);
4852
4853         if (has_failed(conf)) {
4854                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
4855                         " (%d/%d failed)\n",
4856                         mdname(mddev), mddev->degraded, conf->raid_disks);
4857                 goto abort;
4858         }
4859
4860         /* device size must be a multiple of chunk size */
4861         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
4862         mddev->resync_max_sectors = mddev->dev_sectors;
4863
4864         if (mddev->degraded > dirty_parity_disks &&
4865             mddev->recovery_cp != MaxSector) {
4866                 if (mddev->ok_start_degraded)
4867                         printk(KERN_WARNING
4868                                "md/raid:%s: starting dirty degraded array"
4869                                " - data corruption possible.\n",
4870                                mdname(mddev));
4871                 else {
4872                         printk(KERN_ERR
4873                                "md/raid:%s: cannot start dirty degraded array.\n",
4874                                mdname(mddev));
4875                         goto abort;
4876                 }
4877         }
4878
4879         if (mddev->degraded == 0)
4880                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
4881                        " devices, algorithm %d\n", mdname(mddev), conf->level,
4882                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
4883                        mddev->new_layout);
4884         else
4885                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
4886                        " out of %d devices, algorithm %d\n",
4887                        mdname(mddev), conf->level,
4888                        mddev->raid_disks - mddev->degraded,
4889                        mddev->raid_disks, mddev->new_layout);
4890
4891         print_raid5_conf(conf);
4892
4893         if (conf->reshape_progress != MaxSector) {
4894                 conf->reshape_safe = conf->reshape_progress;
4895                 atomic_set(&conf->reshape_stripes, 0);
4896                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4897                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4898                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4899                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4900                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4901                                                         "reshape");
4902         }
4903
4904
4905         /* Ok, everything is just fine now */
4906         if (mddev->to_remove == &raid5_attrs_group)
4907                 mddev->to_remove = NULL;
4908         else if (mddev->kobj.sd &&
4909             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
4910                 printk(KERN_WARNING
4911                        "raid5: failed to create sysfs attributes for %s\n",
4912                        mdname(mddev));
4913         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
4914
4915         if (mddev->queue) {
4916                 int chunk_size;
4917                 /* read-ahead size must cover two whole stripes, which
4918                  * is 2 * (datadisks) * chunksize where 'n' is the
4919                  * number of raid devices
4920                  */
4921                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
4922                 int stripe = data_disks *
4923                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
4924                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4925                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4926
4927                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
4928
4929                 mddev->queue->backing_dev_info.congested_data = mddev;
4930                 mddev->queue->backing_dev_info.congested_fn = raid5_congested;
4931
4932                 chunk_size = mddev->chunk_sectors << 9;
4933                 blk_queue_io_min(mddev->queue, chunk_size);
4934                 blk_queue_io_opt(mddev->queue, chunk_size *
4935                                  (conf->raid_disks - conf->max_degraded));
4936
4937                 list_for_each_entry(rdev, &mddev->disks, same_set)
4938                         disk_stack_limits(mddev->gendisk, rdev->bdev,
4939                                           rdev->data_offset << 9);
4940         }
4941
4942         return 0;
4943 abort:
4944         md_unregister_thread(mddev->thread);
4945         mddev->thread = NULL;
4946         if (conf) {
4947                 print_raid5_conf(conf);
4948                 free_conf(conf);
4949         }
4950         mddev->private = NULL;
4951         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
4952         return -EIO;
4953 }
4954
4955 static int stop(mddev_t *mddev)
4956 {
4957         raid5_conf_t *conf = mddev->private;
4958
4959         md_unregister_thread(mddev->thread);
4960         mddev->thread = NULL;
4961         if (mddev->queue)
4962                 mddev->queue->backing_dev_info.congested_fn = NULL;
4963         free_conf(conf);
4964         mddev->private = NULL;
4965         mddev->to_remove = &raid5_attrs_group;
4966         return 0;
4967 }
4968
4969 #ifdef DEBUG
4970 static void print_sh(struct seq_file *seq, struct stripe_head *sh)
4971 {
4972         int i;
4973
4974         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
4975                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
4976         seq_printf(seq, "sh %llu,  count %d.\n",
4977                    (unsigned long long)sh->sector, atomic_read(&sh->count));
4978         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
4979         for (i = 0; i < sh->disks; i++) {
4980                 seq_printf(seq, "(cache%d: %p %ld) ",
4981                            i, sh->dev[i].page, sh->dev[i].flags);
4982         }
4983         seq_printf(seq, "\n");
4984 }
4985
4986 static void printall(struct seq_file *seq, raid5_conf_t *conf)
4987 {
4988         struct stripe_head *sh;
4989         struct hlist_node *hn;
4990         int i;
4991
4992         spin_lock_irq(&conf->device_lock);
4993         for (i = 0; i < NR_HASH; i++) {
4994                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
4995                         if (sh->raid_conf != conf)
4996                                 continue;
4997                         print_sh(seq, sh);
4998                 }
4999         }
5000         spin_unlock_irq(&conf->device_lock);
5001 }
5002 #endif
5003
5004 static void status(struct seq_file *seq, mddev_t *mddev)
5005 {
5006         raid5_conf_t *conf = mddev->private;
5007         int i;
5008
5009         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
5010                 mddev->chunk_sectors / 2, mddev->layout);
5011         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
5012         for (i = 0; i < conf->raid_disks; i++)
5013                 seq_printf (seq, "%s",
5014                                conf->disks[i].rdev &&
5015                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
5016         seq_printf (seq, "]");
5017 #ifdef DEBUG
5018         seq_printf (seq, "\n");
5019         printall(seq, conf);
5020 #endif
5021 }
5022
5023 static void print_raid5_conf (raid5_conf_t *conf)
5024 {
5025         int i;
5026         struct disk_info *tmp;
5027
5028         printk(KERN_DEBUG "RAID conf printout:\n");
5029         if (!conf) {
5030                 printk("(conf==NULL)\n");
5031                 return;
5032         }
5033         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
5034                conf->raid_disks,
5035                conf->raid_disks - conf->mddev->degraded);
5036
5037         for (i = 0; i < conf->raid_disks; i++) {
5038                 char b[BDEVNAME_SIZE];
5039                 tmp = conf->disks + i;
5040                 if (tmp->rdev)
5041                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
5042                                i, !test_bit(Faulty, &tmp->rdev->flags),
5043                                bdevname(tmp->rdev->bdev, b));
5044         }
5045 }
5046
5047 static int raid5_spare_active(mddev_t *mddev)
5048 {
5049         int i;
5050         raid5_conf_t *conf = mddev->private;
5051         struct disk_info *tmp;
5052         int count = 0;
5053         unsigned long flags;
5054
5055         for (i = 0; i < conf->raid_disks; i++) {
5056                 tmp = conf->disks + i;
5057                 if (tmp->rdev
5058                     && tmp->rdev->recovery_offset == MaxSector
5059                     && !test_bit(Faulty, &tmp->rdev->flags)
5060                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
5061                         count++;
5062                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
5063                 }
5064         }
5065         spin_lock_irqsave(&conf->device_lock, flags);
5066         mddev->degraded -= count;
5067         spin_unlock_irqrestore(&conf->device_lock, flags);
5068         print_raid5_conf(conf);
5069         return count;
5070 }
5071
5072 static int raid5_remove_disk(mddev_t *mddev, int number)
5073 {
5074         raid5_conf_t *conf = mddev->private;
5075         int err = 0;
5076         mdk_rdev_t *rdev;
5077         struct disk_info *p = conf->disks + number;
5078
5079         print_raid5_conf(conf);
5080         rdev = p->rdev;
5081         if (rdev) {
5082                 if (number >= conf->raid_disks &&
5083                     conf->reshape_progress == MaxSector)
5084                         clear_bit(In_sync, &rdev->flags);
5085
5086                 if (test_bit(In_sync, &rdev->flags) ||
5087                     atomic_read(&rdev->nr_pending)) {
5088                         err = -EBUSY;
5089                         goto abort;
5090                 }
5091                 /* Only remove non-faulty devices if recovery
5092                  * isn't possible.
5093                  */
5094                 if (!test_bit(Faulty, &rdev->flags) &&
5095                     mddev->recovery_disabled != conf->recovery_disabled &&
5096                     !has_failed(conf) &&
5097                     number < conf->raid_disks) {
5098                         err = -EBUSY;
5099                         goto abort;
5100                 }
5101                 p->rdev = NULL;
5102                 synchronize_rcu();
5103                 if (atomic_read(&rdev->nr_pending)) {
5104                         /* lost the race, try later */
5105                         err = -EBUSY;
5106                         p->rdev = rdev;
5107                 }
5108         }
5109 abort:
5110
5111         print_raid5_conf(conf);
5112         return err;
5113 }
5114
5115 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
5116 {
5117         raid5_conf_t *conf = mddev->private;
5118         int err = -EEXIST;
5119         int disk;
5120         struct disk_info *p;
5121         int first = 0;
5122         int last = conf->raid_disks - 1;
5123
5124         if (mddev->recovery_disabled == conf->recovery_disabled)
5125                 return -EBUSY;
5126
5127         if (has_failed(conf))
5128                 /* no point adding a device */
5129                 return -EINVAL;
5130
5131         if (rdev->raid_disk >= 0)
5132                 first = last = rdev->raid_disk;
5133
5134         /*
5135          * find the disk ... but prefer rdev->saved_raid_disk
5136          * if possible.
5137          */
5138         if (rdev->saved_raid_disk >= 0 &&
5139             rdev->saved_raid_disk >= first &&
5140             conf->disks[rdev->saved_raid_disk].rdev == NULL)
5141                 disk = rdev->saved_raid_disk;
5142         else
5143                 disk = first;
5144         for ( ; disk <= last ; disk++)
5145                 if ((p=conf->disks + disk)->rdev == NULL) {
5146                         clear_bit(In_sync, &rdev->flags);
5147                         rdev->raid_disk = disk;
5148                         err = 0;
5149                         if (rdev->saved_raid_disk != disk)
5150                                 conf->fullsync = 1;
5151                         rcu_assign_pointer(p->rdev, rdev);
5152                         break;
5153                 }
5154         print_raid5_conf(conf);
5155         return err;
5156 }
5157
5158 static int raid5_resize(mddev_t *mddev, sector_t sectors)
5159 {
5160         /* no resync is happening, and there is enough space
5161          * on all devices, so we can resize.
5162          * We need to make sure resync covers any new space.
5163          * If the array is shrinking we should possibly wait until
5164          * any io in the removed space completes, but it hardly seems
5165          * worth it.
5166          */
5167         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5168         md_set_array_sectors(mddev, raid5_size(mddev, sectors,
5169                                                mddev->raid_disks));
5170         if (mddev->array_sectors >
5171             raid5_size(mddev, sectors, mddev->raid_disks))
5172                 return -EINVAL;
5173         set_capacity(mddev->gendisk, mddev->array_sectors);
5174         revalidate_disk(mddev->gendisk);
5175         if (sectors > mddev->dev_sectors &&
5176             mddev->recovery_cp > mddev->dev_sectors) {
5177                 mddev->recovery_cp = mddev->dev_sectors;
5178                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
5179         }
5180         mddev->dev_sectors = sectors;
5181         mddev->resync_max_sectors = sectors;
5182         return 0;
5183 }
5184
5185 static int check_stripe_cache(mddev_t *mddev)
5186 {
5187         /* Can only proceed if there are plenty of stripe_heads.
5188          * We need a minimum of one full stripe,, and for sensible progress
5189          * it is best to have about 4 times that.
5190          * If we require 4 times, then the default 256 4K stripe_heads will
5191          * allow for chunk sizes up to 256K, which is probably OK.
5192          * If the chunk size is greater, user-space should request more
5193          * stripe_heads first.
5194          */
5195         raid5_conf_t *conf = mddev->private;
5196         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
5197             > conf->max_nr_stripes ||
5198             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
5199             > conf->max_nr_stripes) {
5200                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
5201                        mdname(mddev),
5202                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
5203                         / STRIPE_SIZE)*4);
5204                 return 0;
5205         }
5206         return 1;
5207 }
5208
5209 static int check_reshape(mddev_t *mddev)
5210 {
5211         raid5_conf_t *conf = mddev->private;
5212
5213         if (mddev->delta_disks == 0 &&
5214             mddev->new_layout == mddev->layout &&
5215             mddev->new_chunk_sectors == mddev->chunk_sectors)
5216                 return 0; /* nothing to do */
5217         if (mddev->bitmap)
5218                 /* Cannot grow a bitmap yet */
5219                 return -EBUSY;
5220         if (has_failed(conf))
5221                 return -EINVAL;
5222         if (mddev->delta_disks < 0) {
5223                 /* We might be able to shrink, but the devices must
5224                  * be made bigger first.
5225                  * For raid6, 4 is the minimum size.
5226                  * Otherwise 2 is the minimum
5227                  */
5228                 int min = 2;
5229                 if (mddev->level == 6)
5230                         min = 4;
5231                 if (mddev->raid_disks + mddev->delta_disks < min)
5232                         return -EINVAL;
5233         }
5234
5235         if (!check_stripe_cache(mddev))
5236                 return -ENOSPC;
5237
5238         return resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
5239 }
5240
5241 static int raid5_start_reshape(mddev_t *mddev)
5242 {
5243         raid5_conf_t *conf = mddev->private;
5244         mdk_rdev_t *rdev;
5245         int spares = 0;
5246         unsigned long flags;
5247
5248         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5249                 return -EBUSY;
5250
5251         if (!check_stripe_cache(mddev))
5252                 return -ENOSPC;
5253
5254         list_for_each_entry(rdev, &mddev->disks, same_set)
5255                 if (!test_bit(In_sync, &rdev->flags)
5256                     && !test_bit(Faulty, &rdev->flags))
5257                         spares++;
5258
5259         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
5260                 /* Not enough devices even to make a degraded array
5261                  * of that size
5262                  */
5263                 return -EINVAL;
5264
5265         /* Refuse to reduce size of the array.  Any reductions in
5266          * array size must be through explicit setting of array_size
5267          * attribute.
5268          */
5269         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
5270             < mddev->array_sectors) {
5271                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
5272                        "before number of disks\n", mdname(mddev));
5273                 return -EINVAL;
5274         }
5275
5276         atomic_set(&conf->reshape_stripes, 0);
5277         spin_lock_irq(&conf->device_lock);
5278         conf->previous_raid_disks = conf->raid_disks;
5279         conf->raid_disks += mddev->delta_disks;
5280         conf->prev_chunk_sectors = conf->chunk_sectors;
5281         conf->chunk_sectors = mddev->new_chunk_sectors;
5282         conf->prev_algo = conf->algorithm;
5283         conf->algorithm = mddev->new_layout;
5284         if (mddev->delta_disks < 0)
5285                 conf->reshape_progress = raid5_size(mddev, 0, 0);
5286         else
5287                 conf->reshape_progress = 0;
5288         conf->reshape_safe = conf->reshape_progress;
5289         conf->generation++;
5290         spin_unlock_irq(&conf->device_lock);
5291
5292         /* Add some new drives, as many as will fit.
5293          * We know there are enough to make the newly sized array work.
5294          * Don't add devices if we are reducing the number of
5295          * devices in the array.  This is because it is not possible
5296          * to correctly record the "partially reconstructed" state of
5297          * such devices during the reshape and confusion could result.
5298          */
5299         if (mddev->delta_disks >= 0) {
5300                 int added_devices = 0;
5301                 list_for_each_entry(rdev, &mddev->disks, same_set)
5302                         if (rdev->raid_disk < 0 &&
5303                             !test_bit(Faulty, &rdev->flags)) {
5304                                 if (raid5_add_disk(mddev, rdev) == 0) {
5305                                         if (rdev->raid_disk
5306                                             >= conf->previous_raid_disks) {
5307                                                 set_bit(In_sync, &rdev->flags);
5308                                                 added_devices++;
5309                                         } else
5310                                                 rdev->recovery_offset = 0;
5311
5312                                         if (sysfs_link_rdev(mddev, rdev))
5313                                                 /* Failure here is OK */;
5314                                 }
5315                         } else if (rdev->raid_disk >= conf->previous_raid_disks
5316                                    && !test_bit(Faulty, &rdev->flags)) {
5317                                 /* This is a spare that was manually added */
5318                                 set_bit(In_sync, &rdev->flags);
5319                                 added_devices++;
5320                         }
5321
5322                 /* When a reshape changes the number of devices,
5323        &nbs