block: make bi_phys_segments an unsigned int instead of short
[linux-2.6.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->bm_write is the number of the last batch successfully written.
31  * conf->bm_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 bm_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/module.h>
47 #include <linux/slab.h>
48 #include <linux/highmem.h>
49 #include <linux/bitops.h>
50 #include <linux/kthread.h>
51 #include <asm/atomic.h>
52 #include "raid6.h"
53
54 #include <linux/raid/bitmap.h>
55 #include <linux/async_tx.h>
56
57 /*
58  * Stripe cache
59  */
60
61 #define NR_STRIPES              256
62 #define STRIPE_SIZE             PAGE_SIZE
63 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
64 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
65 #define IO_THRESHOLD            1
66 #define BYPASS_THRESHOLD        1
67 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
68 #define HASH_MASK               (NR_HASH - 1)
69
70 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
71
72 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
73  * order without overlap.  There may be several bio's per stripe+device, and
74  * a bio could span several devices.
75  * When walking this list for a particular stripe+device, we must never proceed
76  * beyond a bio that extends past this device, as the next bio might no longer
77  * be valid.
78  * This macro is used to determine the 'next' bio in the list, given the sector
79  * of the current stripe+device
80  */
81 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
82 /*
83  * The following can be used to debug the driver
84  */
85 #define RAID5_PARANOIA  1
86 #if RAID5_PARANOIA && defined(CONFIG_SMP)
87 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
88 #else
89 # define CHECK_DEVLOCK()
90 #endif
91
92 #ifdef DEBUG
93 #define inline
94 #define __inline__
95 #endif
96
97 #define printk_rl(args...) ((void) (printk_ratelimit() && printk(args)))
98
99 #if !RAID6_USE_EMPTY_ZERO_PAGE
100 /* In .bss so it's zeroed */
101 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
102 #endif
103
104 /*
105  * We maintain a biased count of active stripes in the bottom 16 bits of
106  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
107  */
108 static inline int raid5_bi_phys_segments(struct bio *bio)
109 {
110         return bio->bi_phys_segments & 0xffff;
111 }
112
113 static inline int raid5_bi_hw_segments(struct bio *bio)
114 {
115         return (bio->bi_phys_segments >> 16) & 0xffff;
116 }
117
118 static inline int raid5_dec_bi_phys_segments(struct bio *bio)
119 {
120         --bio->bi_phys_segments;
121         return raid5_bi_phys_segments(bio);
122 }
123
124 static inline int raid5_dec_bi_hw_segments(struct bio *bio)
125 {
126         unsigned short val = raid5_bi_hw_segments(bio);
127
128         --val;
129         bio->bi_phys_segments = (val << 16) | raid5_bi_phys_segments(bio);
130         return val;
131 }
132
133 static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
134 {
135         bio->bi_phys_segments = raid5_bi_phys_segments(bio) || (cnt << 16);
136 }
137
138 static inline int raid6_next_disk(int disk, int raid_disks)
139 {
140         disk++;
141         return (disk < raid_disks) ? disk : 0;
142 }
143
144 static void return_io(struct bio *return_bi)
145 {
146         struct bio *bi = return_bi;
147         while (bi) {
148
149                 return_bi = bi->bi_next;
150                 bi->bi_next = NULL;
151                 bi->bi_size = 0;
152                 bio_endio(bi, 0);
153                 bi = return_bi;
154         }
155 }
156
157 static void print_raid5_conf (raid5_conf_t *conf);
158
159 static int stripe_operations_active(struct stripe_head *sh)
160 {
161         return sh->check_state || sh->reconstruct_state ||
162                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
163                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
164 }
165
166 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
167 {
168         if (atomic_dec_and_test(&sh->count)) {
169                 BUG_ON(!list_empty(&sh->lru));
170                 BUG_ON(atomic_read(&conf->active_stripes)==0);
171                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
172                         if (test_bit(STRIPE_DELAYED, &sh->state)) {
173                                 list_add_tail(&sh->lru, &conf->delayed_list);
174                                 blk_plug_device(conf->mddev->queue);
175                         } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
176                                    sh->bm_seq - conf->seq_write > 0) {
177                                 list_add_tail(&sh->lru, &conf->bitmap_list);
178                                 blk_plug_device(conf->mddev->queue);
179                         } else {
180                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
181                                 list_add_tail(&sh->lru, &conf->handle_list);
182                         }
183                         md_wakeup_thread(conf->mddev->thread);
184                 } else {
185                         BUG_ON(stripe_operations_active(sh));
186                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
187                                 atomic_dec(&conf->preread_active_stripes);
188                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
189                                         md_wakeup_thread(conf->mddev->thread);
190                         }
191                         atomic_dec(&conf->active_stripes);
192                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
193                                 list_add_tail(&sh->lru, &conf->inactive_list);
194                                 wake_up(&conf->wait_for_stripe);
195                                 if (conf->retry_read_aligned)
196                                         md_wakeup_thread(conf->mddev->thread);
197                         }
198                 }
199         }
200 }
201 static void release_stripe(struct stripe_head *sh)
202 {
203         raid5_conf_t *conf = sh->raid_conf;
204         unsigned long flags;
205
206         spin_lock_irqsave(&conf->device_lock, flags);
207         __release_stripe(conf, sh);
208         spin_unlock_irqrestore(&conf->device_lock, flags);
209 }
210
211 static inline void remove_hash(struct stripe_head *sh)
212 {
213         pr_debug("remove_hash(), stripe %llu\n",
214                 (unsigned long long)sh->sector);
215
216         hlist_del_init(&sh->hash);
217 }
218
219 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
220 {
221         struct hlist_head *hp = stripe_hash(conf, sh->sector);
222
223         pr_debug("insert_hash(), stripe %llu\n",
224                 (unsigned long long)sh->sector);
225
226         CHECK_DEVLOCK();
227         hlist_add_head(&sh->hash, hp);
228 }
229
230
231 /* find an idle stripe, make sure it is unhashed, and return it. */
232 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
233 {
234         struct stripe_head *sh = NULL;
235         struct list_head *first;
236
237         CHECK_DEVLOCK();
238         if (list_empty(&conf->inactive_list))
239                 goto out;
240         first = conf->inactive_list.next;
241         sh = list_entry(first, struct stripe_head, lru);
242         list_del_init(first);
243         remove_hash(sh);
244         atomic_inc(&conf->active_stripes);
245 out:
246         return sh;
247 }
248
249 static void shrink_buffers(struct stripe_head *sh, int num)
250 {
251         struct page *p;
252         int i;
253
254         for (i=0; i<num ; i++) {
255                 p = sh->dev[i].page;
256                 if (!p)
257                         continue;
258                 sh->dev[i].page = NULL;
259                 put_page(p);
260         }
261 }
262
263 static int grow_buffers(struct stripe_head *sh, int num)
264 {
265         int i;
266
267         for (i=0; i<num; i++) {
268                 struct page *page;
269
270                 if (!(page = alloc_page(GFP_KERNEL))) {
271                         return 1;
272                 }
273                 sh->dev[i].page = page;
274         }
275         return 0;
276 }
277
278 static void raid5_build_block (struct stripe_head *sh, int i);
279
280 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
281 {
282         raid5_conf_t *conf = sh->raid_conf;
283         int i;
284
285         BUG_ON(atomic_read(&sh->count) != 0);
286         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
287         BUG_ON(stripe_operations_active(sh));
288
289         CHECK_DEVLOCK();
290         pr_debug("init_stripe called, stripe %llu\n",
291                 (unsigned long long)sh->sector);
292
293         remove_hash(sh);
294
295         sh->sector = sector;
296         sh->pd_idx = pd_idx;
297         sh->state = 0;
298
299         sh->disks = disks;
300
301         for (i = sh->disks; i--; ) {
302                 struct r5dev *dev = &sh->dev[i];
303
304                 if (dev->toread || dev->read || dev->towrite || dev->written ||
305                     test_bit(R5_LOCKED, &dev->flags)) {
306                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
307                                (unsigned long long)sh->sector, i, dev->toread,
308                                dev->read, dev->towrite, dev->written,
309                                test_bit(R5_LOCKED, &dev->flags));
310                         BUG();
311                 }
312                 dev->flags = 0;
313                 raid5_build_block(sh, i);
314         }
315         insert_hash(conf, sh);
316 }
317
318 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
319 {
320         struct stripe_head *sh;
321         struct hlist_node *hn;
322
323         CHECK_DEVLOCK();
324         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
325         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
326                 if (sh->sector == sector && sh->disks == disks)
327                         return sh;
328         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
329         return NULL;
330 }
331
332 static void unplug_slaves(mddev_t *mddev);
333 static void raid5_unplug_device(struct request_queue *q);
334
335 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
336                                              int pd_idx, int noblock)
337 {
338         struct stripe_head *sh;
339
340         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
341
342         spin_lock_irq(&conf->device_lock);
343
344         do {
345                 wait_event_lock_irq(conf->wait_for_stripe,
346                                     conf->quiesce == 0,
347                                     conf->device_lock, /* nothing */);
348                 sh = __find_stripe(conf, sector, disks);
349                 if (!sh) {
350                         if (!conf->inactive_blocked)
351                                 sh = get_free_stripe(conf);
352                         if (noblock && sh == NULL)
353                                 break;
354                         if (!sh) {
355                                 conf->inactive_blocked = 1;
356                                 wait_event_lock_irq(conf->wait_for_stripe,
357                                                     !list_empty(&conf->inactive_list) &&
358                                                     (atomic_read(&conf->active_stripes)
359                                                      < (conf->max_nr_stripes *3/4)
360                                                      || !conf->inactive_blocked),
361                                                     conf->device_lock,
362                                                     raid5_unplug_device(conf->mddev->queue)
363                                         );
364                                 conf->inactive_blocked = 0;
365                         } else
366                                 init_stripe(sh, sector, pd_idx, disks);
367                 } else {
368                         if (atomic_read(&sh->count)) {
369                           BUG_ON(!list_empty(&sh->lru));
370                         } else {
371                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
372                                         atomic_inc(&conf->active_stripes);
373                                 if (list_empty(&sh->lru) &&
374                                     !test_bit(STRIPE_EXPANDING, &sh->state))
375                                         BUG();
376                                 list_del_init(&sh->lru);
377                         }
378                 }
379         } while (sh == NULL);
380
381         if (sh)
382                 atomic_inc(&sh->count);
383
384         spin_unlock_irq(&conf->device_lock);
385         return sh;
386 }
387
388 static void
389 raid5_end_read_request(struct bio *bi, int error);
390 static void
391 raid5_end_write_request(struct bio *bi, int error);
392
393 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
394 {
395         raid5_conf_t *conf = sh->raid_conf;
396         int i, disks = sh->disks;
397
398         might_sleep();
399
400         for (i = disks; i--; ) {
401                 int rw;
402                 struct bio *bi;
403                 mdk_rdev_t *rdev;
404                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
405                         rw = WRITE;
406                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
407                         rw = READ;
408                 else
409                         continue;
410
411                 bi = &sh->dev[i].req;
412
413                 bi->bi_rw = rw;
414                 if (rw == WRITE)
415                         bi->bi_end_io = raid5_end_write_request;
416                 else
417                         bi->bi_end_io = raid5_end_read_request;
418
419                 rcu_read_lock();
420                 rdev = rcu_dereference(conf->disks[i].rdev);
421                 if (rdev && test_bit(Faulty, &rdev->flags))
422                         rdev = NULL;
423                 if (rdev)
424                         atomic_inc(&rdev->nr_pending);
425                 rcu_read_unlock();
426
427                 if (rdev) {
428                         if (s->syncing || s->expanding || s->expanded)
429                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
430
431                         set_bit(STRIPE_IO_STARTED, &sh->state);
432
433                         bi->bi_bdev = rdev->bdev;
434                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
435                                 __func__, (unsigned long long)sh->sector,
436                                 bi->bi_rw, i);
437                         atomic_inc(&sh->count);
438                         bi->bi_sector = sh->sector + rdev->data_offset;
439                         bi->bi_flags = 1 << BIO_UPTODATE;
440                         bi->bi_vcnt = 1;
441                         bi->bi_max_vecs = 1;
442                         bi->bi_idx = 0;
443                         bi->bi_io_vec = &sh->dev[i].vec;
444                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
445                         bi->bi_io_vec[0].bv_offset = 0;
446                         bi->bi_size = STRIPE_SIZE;
447                         bi->bi_next = NULL;
448                         if (rw == WRITE &&
449                             test_bit(R5_ReWrite, &sh->dev[i].flags))
450                                 atomic_add(STRIPE_SECTORS,
451                                         &rdev->corrected_errors);
452                         generic_make_request(bi);
453                 } else {
454                         if (rw == WRITE)
455                                 set_bit(STRIPE_DEGRADED, &sh->state);
456                         pr_debug("skip op %ld on disc %d for sector %llu\n",
457                                 bi->bi_rw, i, (unsigned long long)sh->sector);
458                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
459                         set_bit(STRIPE_HANDLE, &sh->state);
460                 }
461         }
462 }
463
464 static struct dma_async_tx_descriptor *
465 async_copy_data(int frombio, struct bio *bio, struct page *page,
466         sector_t sector, struct dma_async_tx_descriptor *tx)
467 {
468         struct bio_vec *bvl;
469         struct page *bio_page;
470         int i;
471         int page_offset;
472
473         if (bio->bi_sector >= sector)
474                 page_offset = (signed)(bio->bi_sector - sector) * 512;
475         else
476                 page_offset = (signed)(sector - bio->bi_sector) * -512;
477         bio_for_each_segment(bvl, bio, i) {
478                 int len = bio_iovec_idx(bio, i)->bv_len;
479                 int clen;
480                 int b_offset = 0;
481
482                 if (page_offset < 0) {
483                         b_offset = -page_offset;
484                         page_offset += b_offset;
485                         len -= b_offset;
486                 }
487
488                 if (len > 0 && page_offset + len > STRIPE_SIZE)
489                         clen = STRIPE_SIZE - page_offset;
490                 else
491                         clen = len;
492
493                 if (clen > 0) {
494                         b_offset += bio_iovec_idx(bio, i)->bv_offset;
495                         bio_page = bio_iovec_idx(bio, i)->bv_page;
496                         if (frombio)
497                                 tx = async_memcpy(page, bio_page, page_offset,
498                                         b_offset, clen,
499                                         ASYNC_TX_DEP_ACK,
500                                         tx, NULL, NULL);
501                         else
502                                 tx = async_memcpy(bio_page, page, b_offset,
503                                         page_offset, clen,
504                                         ASYNC_TX_DEP_ACK,
505                                         tx, NULL, NULL);
506                 }
507                 if (clen < len) /* hit end of page */
508                         break;
509                 page_offset +=  len;
510         }
511
512         return tx;
513 }
514
515 static void ops_complete_biofill(void *stripe_head_ref)
516 {
517         struct stripe_head *sh = stripe_head_ref;
518         struct bio *return_bi = NULL;
519         raid5_conf_t *conf = sh->raid_conf;
520         int i;
521
522         pr_debug("%s: stripe %llu\n", __func__,
523                 (unsigned long long)sh->sector);
524
525         /* clear completed biofills */
526         spin_lock_irq(&conf->device_lock);
527         for (i = sh->disks; i--; ) {
528                 struct r5dev *dev = &sh->dev[i];
529
530                 /* acknowledge completion of a biofill operation */
531                 /* and check if we need to reply to a read request,
532                  * new R5_Wantfill requests are held off until
533                  * !STRIPE_BIOFILL_RUN
534                  */
535                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
536                         struct bio *rbi, *rbi2;
537
538                         BUG_ON(!dev->read);
539                         rbi = dev->read;
540                         dev->read = NULL;
541                         while (rbi && rbi->bi_sector <
542                                 dev->sector + STRIPE_SECTORS) {
543                                 rbi2 = r5_next_bio(rbi, dev->sector);
544                                 if (!raid5_dec_bi_phys_segments(rbi)) {
545                                         rbi->bi_next = return_bi;
546                                         return_bi = rbi;
547                                 }
548                                 rbi = rbi2;
549                         }
550                 }
551         }
552         spin_unlock_irq(&conf->device_lock);
553         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
554
555         return_io(return_bi);
556
557         set_bit(STRIPE_HANDLE, &sh->state);
558         release_stripe(sh);
559 }
560
561 static void ops_run_biofill(struct stripe_head *sh)
562 {
563         struct dma_async_tx_descriptor *tx = NULL;
564         raid5_conf_t *conf = sh->raid_conf;
565         int i;
566
567         pr_debug("%s: stripe %llu\n", __func__,
568                 (unsigned long long)sh->sector);
569
570         for (i = sh->disks; i--; ) {
571                 struct r5dev *dev = &sh->dev[i];
572                 if (test_bit(R5_Wantfill, &dev->flags)) {
573                         struct bio *rbi;
574                         spin_lock_irq(&conf->device_lock);
575                         dev->read = rbi = dev->toread;
576                         dev->toread = NULL;
577                         spin_unlock_irq(&conf->device_lock);
578                         while (rbi && rbi->bi_sector <
579                                 dev->sector + STRIPE_SECTORS) {
580                                 tx = async_copy_data(0, rbi, dev->page,
581                                         dev->sector, tx);
582                                 rbi = r5_next_bio(rbi, dev->sector);
583                         }
584                 }
585         }
586
587         atomic_inc(&sh->count);
588         async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
589                 ops_complete_biofill, sh);
590 }
591
592 static void ops_complete_compute5(void *stripe_head_ref)
593 {
594         struct stripe_head *sh = stripe_head_ref;
595         int target = sh->ops.target;
596         struct r5dev *tgt = &sh->dev[target];
597
598         pr_debug("%s: stripe %llu\n", __func__,
599                 (unsigned long long)sh->sector);
600
601         set_bit(R5_UPTODATE, &tgt->flags);
602         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
603         clear_bit(R5_Wantcompute, &tgt->flags);
604         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
605         if (sh->check_state == check_state_compute_run)
606                 sh->check_state = check_state_compute_result;
607         set_bit(STRIPE_HANDLE, &sh->state);
608         release_stripe(sh);
609 }
610
611 static struct dma_async_tx_descriptor *ops_run_compute5(struct stripe_head *sh)
612 {
613         /* kernel stack size limits the total number of disks */
614         int disks = sh->disks;
615         struct page *xor_srcs[disks];
616         int target = sh->ops.target;
617         struct r5dev *tgt = &sh->dev[target];
618         struct page *xor_dest = tgt->page;
619         int count = 0;
620         struct dma_async_tx_descriptor *tx;
621         int i;
622
623         pr_debug("%s: stripe %llu block: %d\n",
624                 __func__, (unsigned long long)sh->sector, target);
625         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
626
627         for (i = disks; i--; )
628                 if (i != target)
629                         xor_srcs[count++] = sh->dev[i].page;
630
631         atomic_inc(&sh->count);
632
633         if (unlikely(count == 1))
634                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
635                         0, NULL, ops_complete_compute5, sh);
636         else
637                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
638                         ASYNC_TX_XOR_ZERO_DST, NULL,
639                         ops_complete_compute5, sh);
640
641         return tx;
642 }
643
644 static void ops_complete_prexor(void *stripe_head_ref)
645 {
646         struct stripe_head *sh = stripe_head_ref;
647
648         pr_debug("%s: stripe %llu\n", __func__,
649                 (unsigned long long)sh->sector);
650 }
651
652 static struct dma_async_tx_descriptor *
653 ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
654 {
655         /* kernel stack size limits the total number of disks */
656         int disks = sh->disks;
657         struct page *xor_srcs[disks];
658         int count = 0, pd_idx = sh->pd_idx, i;
659
660         /* existing parity data subtracted */
661         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
662
663         pr_debug("%s: stripe %llu\n", __func__,
664                 (unsigned long long)sh->sector);
665
666         for (i = disks; i--; ) {
667                 struct r5dev *dev = &sh->dev[i];
668                 /* Only process blocks that are known to be uptodate */
669                 if (test_bit(R5_Wantdrain, &dev->flags))
670                         xor_srcs[count++] = dev->page;
671         }
672
673         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
674                 ASYNC_TX_DEP_ACK | ASYNC_TX_XOR_DROP_DST, tx,
675                 ops_complete_prexor, sh);
676
677         return tx;
678 }
679
680 static struct dma_async_tx_descriptor *
681 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
682 {
683         int disks = sh->disks;
684         int i;
685
686         pr_debug("%s: stripe %llu\n", __func__,
687                 (unsigned long long)sh->sector);
688
689         for (i = disks; i--; ) {
690                 struct r5dev *dev = &sh->dev[i];
691                 struct bio *chosen;
692
693                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
694                         struct bio *wbi;
695
696                         spin_lock(&sh->lock);
697                         chosen = dev->towrite;
698                         dev->towrite = NULL;
699                         BUG_ON(dev->written);
700                         wbi = dev->written = chosen;
701                         spin_unlock(&sh->lock);
702
703                         while (wbi && wbi->bi_sector <
704                                 dev->sector + STRIPE_SECTORS) {
705                                 tx = async_copy_data(1, wbi, dev->page,
706                                         dev->sector, tx);
707                                 wbi = r5_next_bio(wbi, dev->sector);
708                         }
709                 }
710         }
711
712         return tx;
713 }
714
715 static void ops_complete_postxor(void *stripe_head_ref)
716 {
717         struct stripe_head *sh = stripe_head_ref;
718         int disks = sh->disks, i, pd_idx = sh->pd_idx;
719
720         pr_debug("%s: stripe %llu\n", __func__,
721                 (unsigned long long)sh->sector);
722
723         for (i = disks; i--; ) {
724                 struct r5dev *dev = &sh->dev[i];
725                 if (dev->written || i == pd_idx)
726                         set_bit(R5_UPTODATE, &dev->flags);
727         }
728
729         if (sh->reconstruct_state == reconstruct_state_drain_run)
730                 sh->reconstruct_state = reconstruct_state_drain_result;
731         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
732                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
733         else {
734                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
735                 sh->reconstruct_state = reconstruct_state_result;
736         }
737
738         set_bit(STRIPE_HANDLE, &sh->state);
739         release_stripe(sh);
740 }
741
742 static void
743 ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
744 {
745         /* kernel stack size limits the total number of disks */
746         int disks = sh->disks;
747         struct page *xor_srcs[disks];
748
749         int count = 0, pd_idx = sh->pd_idx, i;
750         struct page *xor_dest;
751         int prexor = 0;
752         unsigned long flags;
753
754         pr_debug("%s: stripe %llu\n", __func__,
755                 (unsigned long long)sh->sector);
756
757         /* check if prexor is active which means only process blocks
758          * that are part of a read-modify-write (written)
759          */
760         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
761                 prexor = 1;
762                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
763                 for (i = disks; i--; ) {
764                         struct r5dev *dev = &sh->dev[i];
765                         if (dev->written)
766                                 xor_srcs[count++] = dev->page;
767                 }
768         } else {
769                 xor_dest = sh->dev[pd_idx].page;
770                 for (i = disks; i--; ) {
771                         struct r5dev *dev = &sh->dev[i];
772                         if (i != pd_idx)
773                                 xor_srcs[count++] = dev->page;
774                 }
775         }
776
777         /* 1/ if we prexor'd then the dest is reused as a source
778          * 2/ if we did not prexor then we are redoing the parity
779          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
780          * for the synchronous xor case
781          */
782         flags = ASYNC_TX_DEP_ACK | ASYNC_TX_ACK |
783                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
784
785         atomic_inc(&sh->count);
786
787         if (unlikely(count == 1)) {
788                 flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
789                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
790                         flags, tx, ops_complete_postxor, sh);
791         } else
792                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
793                         flags, tx, ops_complete_postxor, sh);
794 }
795
796 static void ops_complete_check(void *stripe_head_ref)
797 {
798         struct stripe_head *sh = stripe_head_ref;
799
800         pr_debug("%s: stripe %llu\n", __func__,
801                 (unsigned long long)sh->sector);
802
803         sh->check_state = check_state_check_result;
804         set_bit(STRIPE_HANDLE, &sh->state);
805         release_stripe(sh);
806 }
807
808 static void ops_run_check(struct stripe_head *sh)
809 {
810         /* kernel stack size limits the total number of disks */
811         int disks = sh->disks;
812         struct page *xor_srcs[disks];
813         struct dma_async_tx_descriptor *tx;
814
815         int count = 0, pd_idx = sh->pd_idx, i;
816         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
817
818         pr_debug("%s: stripe %llu\n", __func__,
819                 (unsigned long long)sh->sector);
820
821         for (i = disks; i--; ) {
822                 struct r5dev *dev = &sh->dev[i];
823                 if (i != pd_idx)
824                         xor_srcs[count++] = dev->page;
825         }
826
827         tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
828                 &sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
829
830         atomic_inc(&sh->count);
831         tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
832                 ops_complete_check, sh);
833 }
834
835 static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request)
836 {
837         int overlap_clear = 0, i, disks = sh->disks;
838         struct dma_async_tx_descriptor *tx = NULL;
839
840         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
841                 ops_run_biofill(sh);
842                 overlap_clear++;
843         }
844
845         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
846                 tx = ops_run_compute5(sh);
847                 /* terminate the chain if postxor is not set to be run */
848                 if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request))
849                         async_tx_ack(tx);
850         }
851
852         if (test_bit(STRIPE_OP_PREXOR, &ops_request))
853                 tx = ops_run_prexor(sh, tx);
854
855         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
856                 tx = ops_run_biodrain(sh, tx);
857                 overlap_clear++;
858         }
859
860         if (test_bit(STRIPE_OP_POSTXOR, &ops_request))
861                 ops_run_postxor(sh, tx);
862
863         if (test_bit(STRIPE_OP_CHECK, &ops_request))
864                 ops_run_check(sh);
865
866         if (overlap_clear)
867                 for (i = disks; i--; ) {
868                         struct r5dev *dev = &sh->dev[i];
869                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
870                                 wake_up(&sh->raid_conf->wait_for_overlap);
871                 }
872 }
873
874 static int grow_one_stripe(raid5_conf_t *conf)
875 {
876         struct stripe_head *sh;
877         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
878         if (!sh)
879                 return 0;
880         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
881         sh->raid_conf = conf;
882         spin_lock_init(&sh->lock);
883
884         if (grow_buffers(sh, conf->raid_disks)) {
885                 shrink_buffers(sh, conf->raid_disks);
886                 kmem_cache_free(conf->slab_cache, sh);
887                 return 0;
888         }
889         sh->disks = conf->raid_disks;
890         /* we just created an active stripe so... */
891         atomic_set(&sh->count, 1);
892         atomic_inc(&conf->active_stripes);
893         INIT_LIST_HEAD(&sh->lru);
894         release_stripe(sh);
895         return 1;
896 }
897
898 static int grow_stripes(raid5_conf_t *conf, int num)
899 {
900         struct kmem_cache *sc;
901         int devs = conf->raid_disks;
902
903         sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev));
904         sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev));
905         conf->active_name = 0;
906         sc = kmem_cache_create(conf->cache_name[conf->active_name],
907                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
908                                0, 0, NULL);
909         if (!sc)
910                 return 1;
911         conf->slab_cache = sc;
912         conf->pool_size = devs;
913         while (num--)
914                 if (!grow_one_stripe(conf))
915                         return 1;
916         return 0;
917 }
918
919 #ifdef CONFIG_MD_RAID5_RESHAPE
920 static int resize_stripes(raid5_conf_t *conf, int newsize)
921 {
922         /* Make all the stripes able to hold 'newsize' devices.
923          * New slots in each stripe get 'page' set to a new page.
924          *
925          * This happens in stages:
926          * 1/ create a new kmem_cache and allocate the required number of
927          *    stripe_heads.
928          * 2/ gather all the old stripe_heads and tranfer the pages across
929          *    to the new stripe_heads.  This will have the side effect of
930          *    freezing the array as once all stripe_heads have been collected,
931          *    no IO will be possible.  Old stripe heads are freed once their
932          *    pages have been transferred over, and the old kmem_cache is
933          *    freed when all stripes are done.
934          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
935          *    we simple return a failre status - no need to clean anything up.
936          * 4/ allocate new pages for the new slots in the new stripe_heads.
937          *    If this fails, we don't bother trying the shrink the
938          *    stripe_heads down again, we just leave them as they are.
939          *    As each stripe_head is processed the new one is released into
940          *    active service.
941          *
942          * Once step2 is started, we cannot afford to wait for a write,
943          * so we use GFP_NOIO allocations.
944          */
945         struct stripe_head *osh, *nsh;
946         LIST_HEAD(newstripes);
947         struct disk_info *ndisks;
948         int err;
949         struct kmem_cache *sc;
950         int i;
951
952         if (newsize <= conf->pool_size)
953                 return 0; /* never bother to shrink */
954
955         err = md_allow_write(conf->mddev);
956         if (err)
957                 return err;
958
959         /* Step 1 */
960         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
961                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
962                                0, 0, NULL);
963         if (!sc)
964                 return -ENOMEM;
965
966         for (i = conf->max_nr_stripes; i; i--) {
967                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
968                 if (!nsh)
969                         break;
970
971                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
972
973                 nsh->raid_conf = conf;
974                 spin_lock_init(&nsh->lock);
975
976                 list_add(&nsh->lru, &newstripes);
977         }
978         if (i) {
979                 /* didn't get enough, give up */
980                 while (!list_empty(&newstripes)) {
981                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
982                         list_del(&nsh->lru);
983                         kmem_cache_free(sc, nsh);
984                 }
985                 kmem_cache_destroy(sc);
986                 return -ENOMEM;
987         }
988         /* Step 2 - Must use GFP_NOIO now.
989          * OK, we have enough stripes, start collecting inactive
990          * stripes and copying them over
991          */
992         list_for_each_entry(nsh, &newstripes, lru) {
993                 spin_lock_irq(&conf->device_lock);
994                 wait_event_lock_irq(conf->wait_for_stripe,
995                                     !list_empty(&conf->inactive_list),
996                                     conf->device_lock,
997                                     unplug_slaves(conf->mddev)
998                         );
999                 osh = get_free_stripe(conf);
1000                 spin_unlock_irq(&conf->device_lock);
1001                 atomic_set(&nsh->count, 1);
1002                 for(i=0; i<conf->pool_size; i++)
1003                         nsh->dev[i].page = osh->dev[i].page;
1004                 for( ; i<newsize; i++)
1005                         nsh->dev[i].page = NULL;
1006                 kmem_cache_free(conf->slab_cache, osh);
1007         }
1008         kmem_cache_destroy(conf->slab_cache);
1009
1010         /* Step 3.
1011          * At this point, we are holding all the stripes so the array
1012          * is completely stalled, so now is a good time to resize
1013          * conf->disks.
1014          */
1015         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1016         if (ndisks) {
1017                 for (i=0; i<conf->raid_disks; i++)
1018                         ndisks[i] = conf->disks[i];
1019                 kfree(conf->disks);
1020                 conf->disks = ndisks;
1021         } else
1022                 err = -ENOMEM;
1023
1024         /* Step 4, return new stripes to service */
1025         while(!list_empty(&newstripes)) {
1026                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1027                 list_del_init(&nsh->lru);
1028                 for (i=conf->raid_disks; i < newsize; i++)
1029                         if (nsh->dev[i].page == NULL) {
1030                                 struct page *p = alloc_page(GFP_NOIO);
1031                                 nsh->dev[i].page = p;
1032                                 if (!p)
1033                                         err = -ENOMEM;
1034                         }
1035                 release_stripe(nsh);
1036         }
1037         /* critical section pass, GFP_NOIO no longer needed */
1038
1039         conf->slab_cache = sc;
1040         conf->active_name = 1-conf->active_name;
1041         conf->pool_size = newsize;
1042         return err;
1043 }
1044 #endif
1045
1046 static int drop_one_stripe(raid5_conf_t *conf)
1047 {
1048         struct stripe_head *sh;
1049
1050         spin_lock_irq(&conf->device_lock);
1051         sh = get_free_stripe(conf);
1052         spin_unlock_irq(&conf->device_lock);
1053         if (!sh)
1054                 return 0;
1055         BUG_ON(atomic_read(&sh->count));
1056         shrink_buffers(sh, conf->pool_size);
1057         kmem_cache_free(conf->slab_cache, sh);
1058         atomic_dec(&conf->active_stripes);
1059         return 1;
1060 }
1061
1062 static void shrink_stripes(raid5_conf_t *conf)
1063 {
1064         while (drop_one_stripe(conf))
1065                 ;
1066
1067         if (conf->slab_cache)
1068                 kmem_cache_destroy(conf->slab_cache);
1069         conf->slab_cache = NULL;
1070 }
1071
1072 static void raid5_end_read_request(struct bio * bi, int error)
1073 {
1074         struct stripe_head *sh = bi->bi_private;
1075         raid5_conf_t *conf = sh->raid_conf;
1076         int disks = sh->disks, i;
1077         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1078         char b[BDEVNAME_SIZE];
1079         mdk_rdev_t *rdev;
1080
1081
1082         for (i=0 ; i<disks; i++)
1083                 if (bi == &sh->dev[i].req)
1084                         break;
1085
1086         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1087                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1088                 uptodate);
1089         if (i == disks) {
1090                 BUG();
1091                 return;
1092         }
1093
1094         if (uptodate) {
1095                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1096                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1097                         rdev = conf->disks[i].rdev;
1098                         printk_rl(KERN_INFO "raid5:%s: read error corrected"
1099                                   " (%lu sectors at %llu on %s)\n",
1100                                   mdname(conf->mddev), STRIPE_SECTORS,
1101                                   (unsigned long long)(sh->sector
1102                                                        + rdev->data_offset),
1103                                   bdevname(rdev->bdev, b));
1104                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1105                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1106                 }
1107                 if (atomic_read(&conf->disks[i].rdev->read_errors))
1108                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
1109         } else {
1110                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1111                 int retry = 0;
1112                 rdev = conf->disks[i].rdev;
1113
1114                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1115                 atomic_inc(&rdev->read_errors);
1116                 if (conf->mddev->degraded)
1117                         printk_rl(KERN_WARNING
1118                                   "raid5:%s: read error not correctable "
1119                                   "(sector %llu on %s).\n",
1120                                   mdname(conf->mddev),
1121                                   (unsigned long long)(sh->sector
1122                                                        + rdev->data_offset),
1123                                   bdn);
1124                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1125                         /* Oh, no!!! */
1126                         printk_rl(KERN_WARNING
1127                                   "raid5:%s: read error NOT corrected!! "
1128                                   "(sector %llu on %s).\n",
1129                                   mdname(conf->mddev),
1130                                   (unsigned long long)(sh->sector
1131                                                        + rdev->data_offset),
1132                                   bdn);
1133                 else if (atomic_read(&rdev->read_errors)
1134                          > conf->max_nr_stripes)
1135                         printk(KERN_WARNING
1136                                "raid5:%s: Too many read errors, failing device %s.\n",
1137                                mdname(conf->mddev), bdn);
1138                 else
1139                         retry = 1;
1140                 if (retry)
1141                         set_bit(R5_ReadError, &sh->dev[i].flags);
1142                 else {
1143                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1144                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1145                         md_error(conf->mddev, rdev);
1146                 }
1147         }
1148         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1149         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1150         set_bit(STRIPE_HANDLE, &sh->state);
1151         release_stripe(sh);
1152 }
1153
1154 static void raid5_end_write_request (struct bio *bi, int error)
1155 {
1156         struct stripe_head *sh = bi->bi_private;
1157         raid5_conf_t *conf = sh->raid_conf;
1158         int disks = sh->disks, i;
1159         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1160
1161         for (i=0 ; i<disks; i++)
1162                 if (bi == &sh->dev[i].req)
1163                         break;
1164
1165         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1166                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1167                 uptodate);
1168         if (i == disks) {
1169                 BUG();
1170                 return;
1171         }
1172
1173         if (!uptodate)
1174                 md_error(conf->mddev, conf->disks[i].rdev);
1175
1176         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1177         
1178         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1179         set_bit(STRIPE_HANDLE, &sh->state);
1180         release_stripe(sh);
1181 }
1182
1183
1184 static sector_t compute_blocknr(struct stripe_head *sh, int i);
1185         
1186 static void raid5_build_block (struct stripe_head *sh, int i)
1187 {
1188         struct r5dev *dev = &sh->dev[i];
1189
1190         bio_init(&dev->req);
1191         dev->req.bi_io_vec = &dev->vec;
1192         dev->req.bi_vcnt++;
1193         dev->req.bi_max_vecs++;
1194         dev->vec.bv_page = dev->page;
1195         dev->vec.bv_len = STRIPE_SIZE;
1196         dev->vec.bv_offset = 0;
1197
1198         dev->req.bi_sector = sh->sector;
1199         dev->req.bi_private = sh;
1200
1201         dev->flags = 0;
1202         dev->sector = compute_blocknr(sh, i);
1203 }
1204
1205 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1206 {
1207         char b[BDEVNAME_SIZE];
1208         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1209         pr_debug("raid5: error called\n");
1210
1211         if (!test_bit(Faulty, &rdev->flags)) {
1212                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1213                 if (test_and_clear_bit(In_sync, &rdev->flags)) {
1214                         unsigned long flags;
1215                         spin_lock_irqsave(&conf->device_lock, flags);
1216                         mddev->degraded++;
1217                         spin_unlock_irqrestore(&conf->device_lock, flags);
1218                         /*
1219                          * if recovery was running, make sure it aborts.
1220                          */
1221                         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1222                 }
1223                 set_bit(Faulty, &rdev->flags);
1224                 printk (KERN_ALERT
1225                         "raid5: Disk failure on %s, disabling device.\n"
1226                         "raid5: Operation continuing on %d devices.\n",
1227                         bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
1228         }
1229 }
1230
1231 /*
1232  * Input: a 'big' sector number,
1233  * Output: index of the data and parity disk, and the sector # in them.
1234  */
1235 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
1236                         unsigned int data_disks, unsigned int * dd_idx,
1237                         unsigned int * pd_idx, raid5_conf_t *conf)
1238 {
1239         long stripe;
1240         unsigned long chunk_number;
1241         unsigned int chunk_offset;
1242         sector_t new_sector;
1243         int sectors_per_chunk = conf->chunk_size >> 9;
1244
1245         /* First compute the information on this sector */
1246
1247         /*
1248          * Compute the chunk number and the sector offset inside the chunk
1249          */
1250         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1251         chunk_number = r_sector;
1252         BUG_ON(r_sector != chunk_number);
1253
1254         /*
1255          * Compute the stripe number
1256          */
1257         stripe = chunk_number / data_disks;
1258
1259         /*
1260          * Compute the data disk and parity disk indexes inside the stripe
1261          */
1262         *dd_idx = chunk_number % data_disks;
1263
1264         /*
1265          * Select the parity disk based on the user selected algorithm.
1266          */
1267         switch(conf->level) {
1268         case 4:
1269                 *pd_idx = data_disks;
1270                 break;
1271         case 5:
1272                 switch (conf->algorithm) {
1273                 case ALGORITHM_LEFT_ASYMMETRIC:
1274                         *pd_idx = data_disks - stripe % raid_disks;
1275                         if (*dd_idx >= *pd_idx)
1276                                 (*dd_idx)++;
1277                         break;
1278                 case ALGORITHM_RIGHT_ASYMMETRIC:
1279                         *pd_idx = stripe % raid_disks;
1280                         if (*dd_idx >= *pd_idx)
1281                                 (*dd_idx)++;
1282                         break;
1283                 case ALGORITHM_LEFT_SYMMETRIC:
1284                         *pd_idx = data_disks - stripe % raid_disks;
1285                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1286                         break;
1287                 case ALGORITHM_RIGHT_SYMMETRIC:
1288                         *pd_idx = stripe % raid_disks;
1289                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1290                         break;
1291                 default:
1292                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1293                                 conf->algorithm);
1294                 }
1295                 break;
1296         case 6:
1297
1298                 /**** FIX THIS ****/
1299                 switch (conf->algorithm) {
1300                 case ALGORITHM_LEFT_ASYMMETRIC:
1301                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1302                         if (*pd_idx == raid_disks-1)
1303                                 (*dd_idx)++;    /* Q D D D P */
1304                         else if (*dd_idx >= *pd_idx)
1305                                 (*dd_idx) += 2; /* D D P Q D */
1306                         break;
1307                 case ALGORITHM_RIGHT_ASYMMETRIC:
1308                         *pd_idx = stripe % raid_disks;
1309                         if (*pd_idx == raid_disks-1)
1310                                 (*dd_idx)++;    /* Q D D D P */
1311                         else if (*dd_idx >= *pd_idx)
1312                                 (*dd_idx) += 2; /* D D P Q D */
1313                         break;
1314                 case ALGORITHM_LEFT_SYMMETRIC:
1315                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1316                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1317                         break;
1318                 case ALGORITHM_RIGHT_SYMMETRIC:
1319                         *pd_idx = stripe % raid_disks;
1320                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1321                         break;
1322                 default:
1323                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1324                                 conf->algorithm);
1325                 }
1326                 break;
1327         }
1328
1329         /*
1330          * Finally, compute the new sector number
1331          */
1332         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1333         return new_sector;
1334 }
1335
1336
1337 static sector_t compute_blocknr(struct stripe_head *sh, int i)
1338 {
1339         raid5_conf_t *conf = sh->raid_conf;
1340         int raid_disks = sh->disks;
1341         int data_disks = raid_disks - conf->max_degraded;
1342         sector_t new_sector = sh->sector, check;
1343         int sectors_per_chunk = conf->chunk_size >> 9;
1344         sector_t stripe;
1345         int chunk_offset;
1346         int chunk_number, dummy1, dummy2, dd_idx = i;
1347         sector_t r_sector;
1348
1349
1350         chunk_offset = sector_div(new_sector, sectors_per_chunk);
1351         stripe = new_sector;
1352         BUG_ON(new_sector != stripe);
1353
1354         if (i == sh->pd_idx)
1355                 return 0;
1356         switch(conf->level) {
1357         case 4: break;
1358         case 5:
1359                 switch (conf->algorithm) {
1360                 case ALGORITHM_LEFT_ASYMMETRIC:
1361                 case ALGORITHM_RIGHT_ASYMMETRIC:
1362                         if (i > sh->pd_idx)
1363                                 i--;
1364                         break;
1365                 case ALGORITHM_LEFT_SYMMETRIC:
1366                 case ALGORITHM_RIGHT_SYMMETRIC:
1367                         if (i < sh->pd_idx)
1368                                 i += raid_disks;
1369                         i -= (sh->pd_idx + 1);
1370                         break;
1371                 default:
1372                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1373                                conf->algorithm);
1374                 }
1375                 break;
1376         case 6:
1377                 if (i == raid6_next_disk(sh->pd_idx, raid_disks))
1378                         return 0; /* It is the Q disk */
1379                 switch (conf->algorithm) {
1380                 case ALGORITHM_LEFT_ASYMMETRIC:
1381                 case ALGORITHM_RIGHT_ASYMMETRIC:
1382                         if (sh->pd_idx == raid_disks-1)
1383                                 i--;    /* Q D D D P */
1384                         else if (i > sh->pd_idx)
1385                                 i -= 2; /* D D P Q D */
1386                         break;
1387                 case ALGORITHM_LEFT_SYMMETRIC:
1388                 case ALGORITHM_RIGHT_SYMMETRIC:
1389                         if (sh->pd_idx == raid_disks-1)
1390                                 i--; /* Q D D D P */
1391                         else {
1392                                 /* D D P Q D */
1393                                 if (i < sh->pd_idx)
1394                                         i += raid_disks;
1395                                 i -= (sh->pd_idx + 2);
1396                         }
1397                         break;
1398                 default:
1399                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1400                                 conf->algorithm);
1401                 }
1402                 break;
1403         }
1404
1405         chunk_number = stripe * data_disks + i;
1406         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
1407
1408         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
1409         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
1410                 printk(KERN_ERR "compute_blocknr: map not correct\n");
1411                 return 0;
1412         }
1413         return r_sector;
1414 }
1415
1416
1417
1418 /*
1419  * Copy data between a page in the stripe cache, and one or more bion
1420  * The page could align with the middle of the bio, or there could be
1421  * several bion, each with several bio_vecs, which cover part of the page
1422  * Multiple bion are linked together on bi_next.  There may be extras
1423  * at the end of this list.  We ignore them.
1424  */
1425 static void copy_data(int frombio, struct bio *bio,
1426                      struct page *page,
1427                      sector_t sector)
1428 {
1429         char *pa = page_address(page);
1430         struct bio_vec *bvl;
1431         int i;
1432         int page_offset;
1433
1434         if (bio->bi_sector >= sector)
1435                 page_offset = (signed)(bio->bi_sector - sector) * 512;
1436         else
1437                 page_offset = (signed)(sector - bio->bi_sector) * -512;
1438         bio_for_each_segment(bvl, bio, i) {
1439                 int len = bio_iovec_idx(bio,i)->bv_len;
1440                 int clen;
1441                 int b_offset = 0;
1442
1443                 if (page_offset < 0) {
1444                         b_offset = -page_offset;
1445                         page_offset += b_offset;
1446                         len -= b_offset;
1447                 }
1448
1449                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1450                         clen = STRIPE_SIZE - page_offset;
1451                 else clen = len;
1452
1453                 if (clen > 0) {
1454                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
1455                         if (frombio)
1456                                 memcpy(pa+page_offset, ba+b_offset, clen);
1457                         else
1458                                 memcpy(ba+b_offset, pa+page_offset, clen);
1459                         __bio_kunmap_atomic(ba, KM_USER0);
1460                 }
1461                 if (clen < len) /* hit end of page */
1462                         break;
1463                 page_offset +=  len;
1464         }
1465 }
1466
1467 #define check_xor()     do {                                              \
1468                                 if (count == MAX_XOR_BLOCKS) {            \
1469                                 xor_blocks(count, STRIPE_SIZE, dest, ptr);\
1470                                 count = 0;                                \
1471                            }                                              \
1472                         } while(0)
1473
1474 static void compute_parity6(struct stripe_head *sh, int method)
1475 {
1476         raid6_conf_t *conf = sh->raid_conf;
1477         int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
1478         struct bio *chosen;
1479         /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1480         void *ptrs[disks];
1481
1482         qd_idx = raid6_next_disk(pd_idx, disks);
1483         d0_idx = raid6_next_disk(qd_idx, disks);
1484
1485         pr_debug("compute_parity, stripe %llu, method %d\n",
1486                 (unsigned long long)sh->sector, method);
1487
1488         switch(method) {
1489         case READ_MODIFY_WRITE:
1490                 BUG();          /* READ_MODIFY_WRITE N/A for RAID-6 */
1491         case RECONSTRUCT_WRITE:
1492                 for (i= disks; i-- ;)
1493                         if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1494                                 chosen = sh->dev[i].towrite;
1495                                 sh->dev[i].towrite = NULL;
1496
1497                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1498                                         wake_up(&conf->wait_for_overlap);
1499
1500                                 BUG_ON(sh->dev[i].written);
1501                                 sh->dev[i].written = chosen;
1502                         }
1503                 break;
1504         case CHECK_PARITY:
1505                 BUG();          /* Not implemented yet */
1506         }
1507
1508         for (i = disks; i--;)
1509                 if (sh->dev[i].written) {
1510                         sector_t sector = sh->dev[i].sector;
1511                         struct bio *wbi = sh->dev[i].written;
1512                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1513                                 copy_data(1, wbi, sh->dev[i].page, sector);
1514                                 wbi = r5_next_bio(wbi, sector);
1515                         }
1516
1517                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1518                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1519                 }
1520
1521 //      switch(method) {
1522 //      case RECONSTRUCT_WRITE:
1523 //      case CHECK_PARITY:
1524 //      case UPDATE_PARITY:
1525                 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1526                 /* FIX: Is this ordering of drives even remotely optimal? */
1527                 count = 0;
1528                 i = d0_idx;
1529                 do {
1530                         ptrs[count++] = page_address(sh->dev[i].page);
1531                         if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1532                                 printk("block %d/%d not uptodate on parity calc\n", i,count);
1533                         i = raid6_next_disk(i, disks);
1534                 } while ( i != d0_idx );
1535 //              break;
1536 //      }
1537
1538         raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1539
1540         switch(method) {
1541         case RECONSTRUCT_WRITE:
1542                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1543                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1544                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1545                 set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1546                 break;
1547         case UPDATE_PARITY:
1548                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1549                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1550                 break;
1551         }
1552 }
1553
1554
1555 /* Compute one missing block */
1556 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1557 {
1558         int i, count, disks = sh->disks;
1559         void *ptr[MAX_XOR_BLOCKS], *dest, *p;
1560         int pd_idx = sh->pd_idx;
1561         int qd_idx = raid6_next_disk(pd_idx, disks);
1562
1563         pr_debug("compute_block_1, stripe %llu, idx %d\n",
1564                 (unsigned long long)sh->sector, dd_idx);
1565
1566         if ( dd_idx == qd_idx ) {
1567                 /* We're actually computing the Q drive */
1568                 compute_parity6(sh, UPDATE_PARITY);
1569         } else {
1570                 dest = page_address(sh->dev[dd_idx].page);
1571                 if (!nozero) memset(dest, 0, STRIPE_SIZE);
1572                 count = 0;
1573                 for (i = disks ; i--; ) {
1574                         if (i == dd_idx || i == qd_idx)
1575                                 continue;
1576                         p = page_address(sh->dev[i].page);
1577                         if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1578                                 ptr[count++] = p;
1579                         else
1580                                 printk("compute_block() %d, stripe %llu, %d"
1581                                        " not present\n", dd_idx,
1582                                        (unsigned long long)sh->sector, i);
1583
1584                         check_xor();
1585                 }
1586                 if (count)
1587                         xor_blocks(count, STRIPE_SIZE, dest, ptr);
1588                 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1589                 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1590         }
1591 }
1592
1593 /* Compute two missing blocks */
1594 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1595 {
1596         int i, count, disks = sh->disks;
1597         int pd_idx = sh->pd_idx;
1598         int qd_idx = raid6_next_disk(pd_idx, disks);
1599         int d0_idx = raid6_next_disk(qd_idx, disks);
1600         int faila, failb;
1601
1602         /* faila and failb are disk numbers relative to d0_idx */
1603         /* pd_idx become disks-2 and qd_idx become disks-1 */
1604         faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1605         failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1606
1607         BUG_ON(faila == failb);
1608         if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1609
1610         pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1611                (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1612
1613         if ( failb == disks-1 ) {
1614                 /* Q disk is one of the missing disks */
1615                 if ( faila == disks-2 ) {
1616                         /* Missing P+Q, just recompute */
1617                         compute_parity6(sh, UPDATE_PARITY);
1618                         return;
1619                 } else {
1620                         /* We're missing D+Q; recompute D from P */
1621                         compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1622                         compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1623                         return;
1624                 }
1625         }
1626
1627         /* We're missing D+P or D+D; build pointer table */
1628         {
1629                 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1630                 void *ptrs[disks];
1631
1632                 count = 0;
1633                 i = d0_idx;
1634                 do {
1635                         ptrs[count++] = page_address(sh->dev[i].page);
1636                         i = raid6_next_disk(i, disks);
1637                         if (i != dd_idx1 && i != dd_idx2 &&
1638                             !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1639                                 printk("compute_2 with missing block %d/%d\n", count, i);
1640                 } while ( i != d0_idx );
1641
1642                 if ( failb == disks-2 ) {
1643                         /* We're missing D+P. */
1644                         raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1645                 } else {
1646                         /* We're missing D+D. */
1647                         raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1648                 }
1649
1650                 /* Both the above update both missing blocks */
1651                 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1652                 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1653         }
1654 }
1655
1656 static void
1657 schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
1658                          int rcw, int expand)
1659 {
1660         int i, pd_idx = sh->pd_idx, disks = sh->disks;
1661
1662         if (rcw) {
1663                 /* if we are not expanding this is a proper write request, and
1664                  * there will be bios with new data to be drained into the
1665                  * stripe cache
1666                  */
1667                 if (!expand) {
1668                         sh->reconstruct_state = reconstruct_state_drain_run;
1669                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
1670                 } else
1671                         sh->reconstruct_state = reconstruct_state_run;
1672
1673                 set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
1674
1675                 for (i = disks; i--; ) {
1676                         struct r5dev *dev = &sh->dev[i];
1677
1678                         if (dev->towrite) {
1679                                 set_bit(R5_LOCKED, &dev->flags);
1680                                 set_bit(R5_Wantdrain, &dev->flags);
1681                                 if (!expand)
1682                                         clear_bit(R5_UPTODATE, &dev->flags);
1683                                 s->locked++;
1684                         }
1685                 }
1686                 if (s->locked + 1 == disks)
1687                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
1688                                 atomic_inc(&sh->raid_conf->pending_full_writes);
1689         } else {
1690                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
1691                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
1692
1693                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
1694                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
1695                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
1696                 set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
1697
1698                 for (i = disks; i--; ) {
1699                         struct r5dev *dev = &sh->dev[i];
1700                         if (i == pd_idx)
1701                                 continue;
1702
1703                         if (dev->towrite &&
1704                             (test_bit(R5_UPTODATE, &dev->flags) ||
1705                              test_bit(R5_Wantcompute, &dev->flags))) {
1706                                 set_bit(R5_Wantdrain, &dev->flags);
1707                                 set_bit(R5_LOCKED, &dev->flags);
1708                                 clear_bit(R5_UPTODATE, &dev->flags);
1709                                 s->locked++;
1710                         }
1711                 }
1712         }
1713
1714         /* keep the parity disk locked while asynchronous operations
1715          * are in flight
1716          */
1717         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
1718         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1719         s->locked++;
1720
1721         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
1722                 __func__, (unsigned long long)sh->sector,
1723                 s->locked, s->ops_request);
1724 }
1725
1726 /*
1727  * Each stripe/dev can have one or more bion attached.
1728  * toread/towrite point to the first in a chain.
1729  * The bi_next chain must be in order.
1730  */
1731 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1732 {
1733         struct bio **bip;
1734         raid5_conf_t *conf = sh->raid_conf;
1735         int firstwrite=0;
1736
1737         pr_debug("adding bh b#%llu to stripe s#%llu\n",
1738                 (unsigned long long)bi->bi_sector,
1739                 (unsigned long long)sh->sector);
1740
1741
1742         spin_lock(&sh->lock);
1743         spin_lock_irq(&conf->device_lock);
1744         if (forwrite) {
1745                 bip = &sh->dev[dd_idx].towrite;
1746                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1747                         firstwrite = 1;
1748         } else
1749                 bip = &sh->dev[dd_idx].toread;
1750         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1751                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1752                         goto overlap;
1753                 bip = & (*bip)->bi_next;
1754         }
1755         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1756                 goto overlap;
1757
1758         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1759         if (*bip)
1760                 bi->bi_next = *bip;
1761         *bip = bi;
1762         bi->bi_phys_segments++;
1763         spin_unlock_irq(&conf->device_lock);
1764         spin_unlock(&sh->lock);
1765
1766         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
1767                 (unsigned long long)bi->bi_sector,
1768                 (unsigned long long)sh->sector, dd_idx);
1769
1770         if (conf->mddev->bitmap && firstwrite) {
1771                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1772                                   STRIPE_SECTORS, 0);
1773                 sh->bm_seq = conf->seq_flush+1;
1774                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1775         }
1776
1777         if (forwrite) {
1778                 /* check if page is covered */
1779                 sector_t sector = sh->dev[dd_idx].sector;
1780                 for (bi=sh->dev[dd_idx].towrite;
1781                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1782                              bi && bi->bi_sector <= sector;
1783                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1784                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1785                                 sector = bi->bi_sector + (bi->bi_size>>9);
1786                 }
1787                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1788                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1789         }
1790         return 1;
1791
1792  overlap:
1793         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1794         spin_unlock_irq(&conf->device_lock);
1795         spin_unlock(&sh->lock);
1796         return 0;
1797 }
1798
1799 static void end_reshape(raid5_conf_t *conf);
1800
1801 static int page_is_zero(struct page *p)
1802 {
1803         char *a = page_address(p);
1804         return ((*(u32*)a) == 0 &&
1805                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1806 }
1807
1808 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1809 {
1810         int sectors_per_chunk = conf->chunk_size >> 9;
1811         int pd_idx, dd_idx;
1812         int chunk_offset = sector_div(stripe, sectors_per_chunk);
1813
1814         raid5_compute_sector(stripe * (disks - conf->max_degraded)
1815                              *sectors_per_chunk + chunk_offset,
1816                              disks, disks - conf->max_degraded,
1817                              &dd_idx, &pd_idx, conf);
1818         return pd_idx;
1819 }
1820
1821 static void
1822 handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
1823                                 struct stripe_head_state *s, int disks,
1824                                 struct bio **return_bi)
1825 {
1826         int i;
1827         for (i = disks; i--; ) {
1828                 struct bio *bi;
1829                 int bitmap_end = 0;
1830
1831                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1832                         mdk_rdev_t *rdev;
1833                         rcu_read_lock();
1834                         rdev = rcu_dereference(conf->disks[i].rdev);
1835                         if (rdev && test_bit(In_sync, &rdev->flags))
1836                                 /* multiple read failures in one stripe */
1837                                 md_error(conf->mddev, rdev);
1838                         rcu_read_unlock();
1839                 }
1840                 spin_lock_irq(&conf->device_lock);
1841                 /* fail all writes first */
1842                 bi = sh->dev[i].towrite;
1843                 sh->dev[i].towrite = NULL;
1844                 if (bi) {
1845                         s->to_write--;
1846                         bitmap_end = 1;
1847                 }
1848
1849                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1850                         wake_up(&conf->wait_for_overlap);
1851
1852                 while (bi && bi->bi_sector <
1853                         sh->dev[i].sector + STRIPE_SECTORS) {
1854                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1855                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1856                         if (!raid5_dec_bi_phys_segments(bi)) {
1857                                 md_write_end(conf->mddev);
1858                                 bi->bi_next = *return_bi;
1859                                 *return_bi = bi;
1860                         }
1861                         bi = nextbi;
1862                 }
1863                 /* and fail all 'written' */
1864                 bi = sh->dev[i].written;
1865                 sh->dev[i].written = NULL;
1866                 if (bi) bitmap_end = 1;
1867                 while (bi && bi->bi_sector <
1868                        sh->dev[i].sector + STRIPE_SECTORS) {
1869                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1870                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1871                         if (!raid5_dec_bi_phys_segments(bi)) {
1872                                 md_write_end(conf->mddev);
1873                                 bi->bi_next = *return_bi;
1874                                 *return_bi = bi;
1875                         }
1876                         bi = bi2;
1877                 }
1878
1879                 /* fail any reads if this device is non-operational and
1880                  * the data has not reached the cache yet.
1881                  */
1882                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
1883                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1884                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
1885                         bi = sh->dev[i].toread;
1886                         sh->dev[i].toread = NULL;
1887                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1888                                 wake_up(&conf->wait_for_overlap);
1889                         if (bi) s->to_read--;
1890                         while (bi && bi->bi_sector <
1891                                sh->dev[i].sector + STRIPE_SECTORS) {
1892                                 struct bio *nextbi =
1893                                         r5_next_bio(bi, sh->dev[i].sector);
1894                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1895                                 if (!raid5_dec_bi_phys_segments(bi)) {
1896                                         bi->bi_next = *return_bi;
1897                                         *return_bi = bi;
1898                                 }
1899                                 bi = nextbi;
1900                         }
1901                 }
1902                 spin_unlock_irq(&conf->device_lock);
1903                 if (bitmap_end)
1904                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1905                                         STRIPE_SECTORS, 0, 0);
1906         }
1907
1908         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
1909                 if (atomic_dec_and_test(&conf->pending_full_writes))
1910                         md_wakeup_thread(conf->mddev->thread);
1911 }
1912
1913 /* fetch_block5 - checks the given member device to see if its data needs
1914  * to be read or computed to satisfy a request.
1915  *
1916  * Returns 1 when no more member devices need to be checked, otherwise returns
1917  * 0 to tell the loop in handle_stripe_fill5 to continue
1918  */
1919 static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
1920                         int disk_idx, int disks)
1921 {
1922         struct r5dev *dev = &sh->dev[disk_idx];
1923         struct r5dev *failed_dev = &sh->dev[s->failed_num];
1924
1925         /* is the data in this block needed, and can we get it? */
1926         if (!test_bit(R5_LOCKED, &dev->flags) &&
1927             !test_bit(R5_UPTODATE, &dev->flags) &&
1928             (dev->toread ||
1929              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1930              s->syncing || s->expanding ||
1931              (s->failed &&
1932               (failed_dev->toread ||
1933                (failed_dev->towrite &&
1934                 !test_bit(R5_OVERWRITE, &failed_dev->flags)))))) {
1935                 /* We would like to get this block, possibly by computing it,
1936                  * otherwise read it if the backing disk is insync
1937                  */
1938                 if ((s->uptodate == disks - 1) &&
1939                     (s->failed && disk_idx == s->failed_num)) {
1940                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
1941                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
1942                         set_bit(R5_Wantcompute, &dev->flags);
1943                         sh->ops.target = disk_idx;
1944                         s->req_compute = 1;
1945                         /* Careful: from this point on 'uptodate' is in the eye
1946                          * of raid5_run_ops which services 'compute' operations
1947                          * before writes. R5_Wantcompute flags a block that will
1948                          * be R5_UPTODATE by the time it is needed for a
1949                          * subsequent operation.
1950                          */
1951                         s->uptodate++;
1952                         return 1; /* uptodate + compute == disks */
1953                 } else if (test_bit(R5_Insync, &dev->flags)) {
1954                         set_bit(R5_LOCKED, &dev->flags);
1955                         set_bit(R5_Wantread, &dev->flags);
1956                         s->locked++;
1957                         pr_debug("Reading block %d (sync=%d)\n", disk_idx,
1958                                 s->syncing);
1959                 }
1960         }
1961
1962         return 0;
1963 }
1964
1965 /**
1966  * handle_stripe_fill5 - read or compute data to satisfy pending requests.
1967  */
1968 static void handle_stripe_fill5(struct stripe_head *sh,
1969                         struct stripe_head_state *s, int disks)
1970 {
1971         int i;
1972
1973         /* look for blocks to read/compute, skip this if a compute
1974          * is already in flight, or if the stripe contents are in the
1975          * midst of changing due to a write
1976          */
1977         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
1978             !sh->reconstruct_state)
1979                 for (i = disks; i--; )
1980                         if (fetch_block5(sh, s, i, disks))
1981                                 break;
1982         set_bit(STRIPE_HANDLE, &sh->state);
1983 }
1984
1985 static void handle_stripe_fill6(struct stripe_head *sh,
1986                         struct stripe_head_state *s, struct r6_state *r6s,
1987                         int disks)
1988 {
1989         int i;
1990         for (i = disks; i--; ) {
1991                 struct r5dev *dev = &sh->dev[i];
1992                 if (!test_bit(R5_LOCKED, &dev->flags) &&
1993                     !test_bit(R5_UPTODATE, &dev->flags) &&
1994                     (dev->toread || (dev->towrite &&
1995                      !test_bit(R5_OVERWRITE, &dev->flags)) ||
1996                      s->syncing || s->expanding ||
1997                      (s->failed >= 1 &&
1998                       (sh->dev[r6s->failed_num[0]].toread ||
1999                        s->to_write)) ||
2000                      (s->failed >= 2 &&
2001                       (sh->dev[r6s->failed_num[1]].toread ||
2002                        s->to_write)))) {
2003                         /* we would like to get this block, possibly
2004                          * by computing it, but we might not be able to
2005                          */
2006                         if ((s->uptodate == disks - 1) &&
2007                             (s->failed && (i == r6s->failed_num[0] ||
2008                                            i == r6s->failed_num[1]))) {
2009                                 pr_debug("Computing stripe %llu block %d\n",
2010                                        (unsigned long long)sh->sector, i);
2011                                 compute_block_1(sh, i, 0);
2012                                 s->uptodate++;
2013                         } else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
2014                                 /* Computing 2-failure is *very* expensive; only
2015                                  * do it if failed >= 2
2016                                  */
2017                                 int other;
2018                                 for (other = disks; other--; ) {
2019                                         if (other == i)
2020                                                 continue;
2021                                         if (!test_bit(R5_UPTODATE,
2022                                               &sh->dev[other].flags))
2023                                                 break;
2024                                 }
2025                                 BUG_ON(other < 0);
2026                                 pr_debug("Computing stripe %llu blocks %d,%d\n",
2027                                        (unsigned long long)sh->sector,
2028                                        i, other);
2029                                 compute_block_2(sh, i, other);
2030                                 s->uptodate += 2;
2031                         } else if (test_bit(R5_Insync, &dev->flags)) {
2032                                 set_bit(R5_LOCKED, &dev->flags);
2033                                 set_bit(R5_Wantread, &dev->flags);
2034                                 s->locked++;
2035                                 pr_debug("Reading block %d (sync=%d)\n",
2036                                         i, s->syncing);
2037                         }
2038                 }
2039         }
2040         set_bit(STRIPE_HANDLE, &sh->state);
2041 }
2042
2043
2044 /* handle_stripe_clean_event
2045  * any written block on an uptodate or failed drive can be returned.
2046  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2047  * never LOCKED, so we don't need to test 'failed' directly.
2048  */
2049 static void handle_stripe_clean_event(raid5_conf_t *conf,
2050         struct stripe_head *sh, int disks, struct bio **return_bi)
2051 {
2052         int i;
2053         struct r5dev *dev;
2054
2055         for (i = disks; i--; )
2056                 if (sh->dev[i].written) {
2057                         dev = &sh->dev[i];
2058                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2059                                 test_bit(R5_UPTODATE, &dev->flags)) {
2060                                 /* We can return any write requests */
2061                                 struct bio *wbi, *wbi2;
2062                                 int bitmap_end = 0;
2063                                 pr_debug("Return write for disc %d\n", i);
2064                                 spin_lock_irq(&conf->device_lock);
2065                                 wbi = dev->written;
2066                                 dev->written = NULL;
2067                                 while (wbi && wbi->bi_sector <
2068                                         dev->sector + STRIPE_SECTORS) {
2069                                         wbi2 = r5_next_bio(wbi, dev->sector);
2070                                         if (!raid5_dec_bi_phys_segments(wbi)) {
2071                                                 md_write_end(conf->mddev);
2072                                                 wbi->bi_next = *return_bi;
2073                                                 *return_bi = wbi;
2074                                         }
2075                                         wbi = wbi2;
2076                                 }
2077                                 if (dev->towrite == NULL)
2078                                         bitmap_end = 1;
2079                                 spin_unlock_irq(&conf->device_lock);
2080                                 if (bitmap_end)
2081                                         bitmap_endwrite(conf->mddev->bitmap,
2082                                                         sh->sector,
2083                                                         STRIPE_SECTORS,
2084                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2085                                                         0);
2086                         }
2087                 }
2088
2089         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2090                 if (atomic_dec_and_test(&conf->pending_full_writes))
2091                         md_wakeup_thread(conf->mddev->thread);
2092 }
2093
2094 static void handle_stripe_dirtying5(raid5_conf_t *conf,
2095                 struct stripe_head *sh, struct stripe_head_state *s, int disks)
2096 {
2097         int rmw = 0, rcw = 0, i;
2098         for (i = disks; i--; ) {
2099                 /* would I have to read this buffer for read_modify_write */
2100                 struct r5dev *dev = &sh->dev[i];
2101                 if ((dev->towrite || i == sh->pd_idx) &&
2102                     !test_bit(R5_LOCKED, &dev->flags) &&
2103                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2104                       test_bit(R5_Wantcompute, &dev->flags))) {
2105                         if (test_bit(R5_Insync, &dev->flags))
2106                                 rmw++;
2107                         else
2108                                 rmw += 2*disks;  /* cannot read it */
2109                 }
2110                 /* Would I have to read this buffer for reconstruct_write */
2111                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2112                     !test_bit(R5_LOCKED, &dev->flags) &&
2113                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2114                     test_bit(R5_Wantcompute, &dev->flags))) {
2115                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2116                         else
2117                                 rcw += 2*disks;
2118                 }
2119         }
2120         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2121                 (unsigned long long)sh->sector, rmw, rcw);
2122         set_bit(STRIPE_HANDLE, &sh->state);
2123         if (rmw < rcw && rmw > 0)
2124                 /* prefer read-modify-write, but need to get some data */
2125                 for (i = disks; i--; ) {
2126                         struct r5dev *dev = &sh->dev[i];
2127                         if ((dev->towrite || i == sh->pd_idx) &&
2128                             !test_bit(R5_LOCKED, &dev->flags) &&
2129                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2130                             test_bit(R5_Wantcompute, &dev->flags)) &&
2131                             test_bit(R5_Insync, &dev->flags)) {
2132                                 if (
2133                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2134                                         pr_debug("Read_old block "
2135                                                 "%d for r-m-w\n", i);
2136                                         set_bit(R5_LOCKED, &dev->flags);
2137                                         set_bit(R5_Wantread, &dev->flags);
2138                                         s->locked++;
2139                                 } else {
2140                                         set_bit(STRIPE_DELAYED, &sh->state);
2141                                         set_bit(STRIPE_HANDLE, &sh->state);
2142                                 }
2143                         }
2144                 }
2145         if (rcw <= rmw && rcw > 0)
2146                 /* want reconstruct write, but need to get some data */
2147                 for (i = disks; i--; ) {
2148                         struct r5dev *dev = &sh->dev[i];
2149                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2150                             i != sh->pd_idx &&
2151                             !test_bit(R5_LOCKED, &dev->flags) &&
2152                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2153                             test_bit(R5_Wantcompute, &dev->flags)) &&
2154                             test_bit(R5_Insync, &dev->flags)) {
2155                                 if (
2156                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2157                                         pr_debug("Read_old block "
2158                                                 "%d for Reconstruct\n", i);
2159                                         set_bit(R5_LOCKED, &dev->flags);
2160                                         set_bit(R5_Wantread, &dev->flags);
2161                                         s->locked++;
2162                                 } else {
2163                                         set_bit(STRIPE_DELAYED, &sh->state);
2164                                         set_bit(STRIPE_HANDLE, &sh->state);
2165                                 }
2166                         }
2167                 }
2168         /* now if nothing is locked, and if we have enough data,
2169          * we can start a write request
2170          */
2171         /* since handle_stripe can be called at any time we need to handle the
2172          * case where a compute block operation has been submitted and then a
2173          * subsequent call wants to start a write request.  raid5_run_ops only
2174          * handles the case where compute block and postxor are requested
2175          * simultaneously.  If this is not the case then new writes need to be
2176          * held off until the compute completes.
2177          */
2178         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2179             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2180             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2181                 schedule_reconstruction5(sh, s, rcw == 0, 0);
2182 }
2183
2184 static void handle_stripe_dirtying6(raid5_conf_t *conf,
2185                 struct stripe_head *sh, struct stripe_head_state *s,
2186                 struct r6_state *r6s, int disks)
2187 {
2188         int rcw = 0, must_compute = 0, pd_idx = sh->pd_idx, i;
2189         int qd_idx = r6s->qd_idx;
2190         for (i = disks; i--; ) {
2191                 struct r5dev *dev = &sh->dev[i];
2192                 /* Would I have to read this buffer for reconstruct_write */
2193                 if (!test_bit(R5_OVERWRITE, &dev->flags)
2194                     && i != pd_idx && i != qd_idx
2195                     && (!test_bit(R5_LOCKED, &dev->flags)
2196                             ) &&
2197                     !test_bit(R5_UPTODATE, &dev->flags)) {
2198                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2199                         else {
2200                                 pr_debug("raid6: must_compute: "
2201                                         "disk %d flags=%#lx\n", i, dev->flags);
2202                                 must_compute++;
2203                         }
2204                 }
2205         }
2206         pr_debug("for sector %llu, rcw=%d, must_compute=%d\n",
2207                (unsigned long long)sh->sector, rcw, must_compute);
2208         set_bit(STRIPE_HANDLE, &sh->state);
2209
2210         if (rcw > 0)
2211                 /* want reconstruct write, but need to get some data */
2212                 for (i = disks; i--; ) {
2213                         struct r5dev *dev = &sh->dev[i];
2214                         if (!test_bit(R5_OVERWRITE, &dev->flags)
2215                             && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
2216                             && !test_bit(R5_LOCKED, &dev->flags) &&
2217                             !test_bit(R5_UPTODATE, &dev->flags) &&
2218                             test_bit(R5_Insync, &dev->flags)) {
2219                                 if (
2220                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2221                                         pr_debug("Read_old stripe %llu "
2222                                                 "block %d for Reconstruct\n",
2223                                              (unsigned long long)sh->sector, i);
2224                                         set_bit(R5_LOCKED, &dev->flags);
2225                                         set_bit(R5_Wantread, &dev->flags);
2226                                         s->locked++;
2227                                 } else {
2228                                         pr_debug("Request delayed stripe %llu "
2229                                                 "block %d for Reconstruct\n",
2230                                              (unsigned long long)sh->sector, i);
2231                                         set_bit(STRIPE_DELAYED, &sh->state);
2232                                         set_bit(STRIPE_HANDLE, &sh->state);
2233                                 }
2234                         }
2235                 }
2236         /* now if nothing is locked, and if we have enough data, we can start a
2237          * write request
2238          */
2239         if (s->locked == 0 && rcw == 0 &&
2240             !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2241                 if (must_compute > 0) {
2242                         /* We have failed blocks and need to compute them */
2243                         switch (s->failed) {
2244                         case 0:
2245                                 BUG();
2246                         case 1:
2247                                 compute_block_1(sh, r6s->failed_num[0], 0);
2248                                 break;
2249                         case 2:
2250                                 compute_block_2(sh, r6s->failed_num[0],
2251                                                 r6s->failed_num[1]);
2252                                 break;
2253                         default: /* This request should have been failed? */
2254                                 BUG();
2255                         }
2256                 }
2257
2258                 pr_debug("Computing parity for stripe %llu\n",
2259                         (unsigned long long)sh->sector);
2260                 compute_parity6(sh, RECONSTRUCT_WRITE);
2261                 /* now every locked buffer is ready to be written */
2262                 for (i = disks; i--; )
2263                         if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2264                                 pr_debug("Writing stripe %llu block %d\n",
2265                                        (unsigned long long)sh->sector, i);
2266                                 s->locked++;
2267                                 set_bit(R5_Wantwrite, &sh->dev[i].flags);
2268                         }
2269                 if (s->locked == disks)
2270                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2271                                 atomic_inc(&conf->pending_full_writes);
2272                 /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2273                 set_bit(STRIPE_INSYNC, &sh->state);
2274
2275                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2276                         atomic_dec(&conf->preread_active_stripes);
2277                         if (atomic_read(&conf->preread_active_stripes) <
2278                             IO_THRESHOLD)
2279                                 md_wakeup_thread(conf->mddev->thread);
2280                 }
2281         }
2282 }
2283
2284 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2285                                 struct stripe_head_state *s, int disks)
2286 {
2287         struct r5dev *dev = NULL;
2288
2289         set_bit(STRIPE_HANDLE, &sh->state);
2290
2291         switch (sh->check_state) {
2292         case check_state_idle:
2293                 /* start a new check operation if there are no failures */
2294                 if (s->failed == 0) {
2295                         BUG_ON(s->uptodate != disks);
2296                         sh->check_state = check_state_run;
2297                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2298                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2299                         s->uptodate--;
2300                         break;
2301                 }
2302                 dev = &sh->dev[s->failed_num];
2303                 /* fall through */
2304         case check_state_compute_result:
2305                 sh->check_state = check_state_idle;
2306                 if (!dev)
2307                         dev = &sh->dev[sh->pd_idx];
2308
2309                 /* check that a write has not made the stripe insync */
2310                 if (test_bit(STRIPE_INSYNC, &sh->state))
2311                         break;
2312
2313                 /* either failed parity check, or recovery is happening */
2314                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2315                 BUG_ON(s->uptodate != disks);
2316
2317                 set_bit(R5_LOCKED, &dev->flags);
2318                 s->locked++;
2319                 set_bit(R5_Wantwrite, &dev->flags);
2320
2321                 clear_bit(STRIPE_DEGRADED, &sh->state);
2322                 set_bit(STRIPE_INSYNC, &sh->state);
2323                 break;
2324         case check_state_run:
2325                 break; /* we will be called again upon completion */
2326         case check_state_check_result:
2327                 sh->check_state = check_state_idle;
2328
2329                 /* if a failure occurred during the check operation, leave
2330                  * STRIPE_INSYNC not set and let the stripe be handled again
2331                  */
2332                 if (s->failed)
2333                         break;
2334
2335                 /* handle a successful check operation, if parity is correct
2336                  * we are done.  Otherwise update the mismatch count and repair
2337                  * parity if !MD_RECOVERY_CHECK
2338                  */
2339                 if (sh->ops.zero_sum_result == 0)
2340                         /* parity is correct (on disc,
2341                          * not in buffer any more)
2342                          */
2343                         set_bit(STRIPE_INSYNC, &sh->state);
2344                 else {
2345                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2346                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2347                                 /* don't try to repair!! */
2348                                 set_bit(STRIPE_INSYNC, &sh->state);
2349                         else {
2350                                 sh->check_state = check_state_compute_run;
2351                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2352                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2353                                 set_bit(R5_Wantcompute,
2354                                         &sh->dev[sh->pd_idx].flags);
2355                                 sh->ops.target = sh->pd_idx;
2356                                 s->uptodate++;
2357                         }
2358                 }
2359                 break;
2360         case check_state_compute_run:
2361                 break;
2362         default:
2363                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2364                        __func__, sh->check_state,
2365                        (unsigned long long) sh->sector);
2366                 BUG();
2367         }
2368 }
2369
2370
2371 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2372                                 struct stripe_head_state *s,
2373                                 struct r6_state *r6s, struct page *tmp_page,
2374                                 int disks)
2375 {
2376         int update_p = 0, update_q = 0;
2377         struct r5dev *dev;
2378         int pd_idx = sh->pd_idx;
2379         int qd_idx = r6s->qd_idx;
2380
2381         set_bit(STRIPE_HANDLE, &sh->state);
2382
2383         BUG_ON(s->failed > 2);
2384         BUG_ON(s->uptodate < disks);
2385         /* Want to check and possibly repair P and Q.
2386          * However there could be one 'failed' device, in which
2387          * case we can only check one of them, possibly using the
2388          * other to generate missing data
2389          */
2390
2391         /* If !tmp_page, we cannot do the calculations,
2392          * but as we have set STRIPE_HANDLE, we will soon be called
2393          * by stripe_handle with a tmp_page - just wait until then.
2394          */
2395         if (tmp_page) {
2396                 if (s->failed == r6s->q_failed) {
2397                         /* The only possible failed device holds 'Q', so it
2398                          * makes sense to check P (If anything else were failed,
2399                          * we would have used P to recreate it).
2400                          */
2401                         compute_block_1(sh, pd_idx, 1);
2402                         if (!page_is_zero(sh->dev[pd_idx].page)) {
2403                                 compute_block_1(sh, pd_idx, 0);
2404                                 update_p = 1;
2405                         }
2406                 }
2407                 if (!r6s->q_failed && s->failed < 2) {
2408                         /* q is not failed, and we didn't use it to generate
2409                          * anything, so it makes sense to check it
2410                          */
2411                         memcpy(page_address(tmp_page),
2412                                page_address(sh->dev[qd_idx].page),
2413                                STRIPE_SIZE);
2414                         compute_parity6(sh, UPDATE_PARITY);
2415                         if (memcmp(page_address(tmp_page),
2416                                    page_address(sh->dev[qd_idx].page),
2417                                    STRIPE_SIZE) != 0) {
2418                                 clear_bit(STRIPE_INSYNC, &sh->state);
2419                                 update_q = 1;
2420                         }
2421                 }
2422                 if (update_p || update_q) {
2423                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2424                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2425                                 /* don't try to repair!! */
2426                                 update_p = update_q = 0;
2427                 }
2428
2429                 /* now write out any block on a failed drive,
2430                  * or P or Q if they need it
2431                  */
2432
2433                 if (s->failed == 2) {
2434                         dev = &sh->dev[r6s->failed_num[1]];
2435                         s->locked++;
2436                         set_bit(R5_LOCKED, &dev->flags);
2437                         set_bit(R5_Wantwrite, &dev->flags);
2438                 }
2439                 if (s->failed >= 1) {
2440                         dev = &sh->dev[r6s->failed_num[0]];
2441                         s->locked++;
2442                         set_bit(R5_LOCKED, &dev->flags);
2443                         set_bit(R5_Wantwrite, &dev->flags);
2444                 }
2445
2446                 if (update_p) {
2447                         dev = &sh->dev[pd_idx];
2448                         s->locked++;
2449                         set_bit(R5_LOCKED, &dev->flags);
2450                         set_bit(R5_Wantwrite, &dev->flags);
2451                 }
2452                 if (update_q) {
2453                         dev = &sh->dev[qd_idx];
2454                         s->locked++;
2455                         set_bit(R5_LOCKED, &dev->flags);
2456                         set_bit(R5_Wantwrite, &dev->flags);
2457                 }
2458                 clear_bit(STRIPE_DEGRADED, &sh->state);
2459
2460                 set_bit(STRIPE_INSYNC, &sh->state);
2461         }
2462 }
2463
2464 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
2465                                 struct r6_state *r6s)
2466 {
2467         int i;
2468
2469         /* We have read all the blocks in this stripe and now we need to
2470          * copy some of them into a target stripe for expand.
2471          */
2472         struct dma_async_tx_descriptor *tx = NULL;
2473         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2474         for (i = 0; i < sh->disks; i++)
2475                 if (i != sh->pd_idx && (!r6s || i != r6s->qd_idx)) {
2476                         int dd_idx, pd_idx, j;
2477                         struct stripe_head *sh2;
2478
2479                         sector_t bn = compute_blocknr(sh, i);
2480                         sector_t s = raid5_compute_sector(bn, conf->raid_disks,
2481                                                 conf->raid_disks -
2482                                                 conf->max_degraded, &dd_idx,
2483                                                 &pd_idx, conf);
2484                         sh2 = get_active_stripe(conf, s, conf->raid_disks,
2485                                                 pd_idx, 1);
2486                         if (sh2 == NULL)
2487                                 /* so far only the early blocks of this stripe
2488                                  * have been requested.  When later blocks
2489                                  * get requested, we will try again
2490                                  */
2491                                 continue;
2492                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2493                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2494                                 /* must have already done this block */
2495                                 release_stripe(sh2);
2496                                 continue;
2497                         }
2498
2499                         /* place all the copies on one channel */
2500                         tx = async_memcpy(sh2->dev[dd_idx].page,
2501                                 sh->dev[i].page, 0, 0, STRIPE_SIZE,
2502                                 ASYNC_TX_DEP_ACK, tx, NULL, NULL);
2503
2504                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2505                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2506                         for (j = 0; j < conf->raid_disks; j++)
2507                                 if (j != sh2->pd_idx &&
2508                                     (!r6s || j != raid6_next_disk(sh2->pd_idx,
2509                                                                  sh2->disks)) &&
2510                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
2511                                         break;
2512                         if (j == conf->raid_disks) {
2513                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
2514                                 set_bit(STRIPE_HANDLE, &sh2->state);
2515                         }
2516                         release_stripe(sh2);
2517
2518                 }
2519         /* done submitting copies, wait for them to complete */
2520         if (tx) {
2521                 async_tx_ack(tx);
2522                 dma_wait_for_async_tx(tx);
2523         }
2524 }
2525
2526
2527 /*
2528  * handle_stripe - do things to a stripe.
2529  *
2530  * We lock the stripe and then examine the state of various bits
2531  * to see what needs to be done.
2532  * Possible results:
2533  *    return some read request which now have data
2534  *    return some write requests which are safely on disc
2535  *    schedule a read on some buffers
2536  *    schedule a write of some buffers
2537  *    return confirmation of parity correctness
2538  *
2539  * buffers are taken off read_list or write_list, and bh_cache buffers
2540  * get BH_Lock set before the stripe lock is released.
2541  *
2542  */
2543
2544 static bool handle_stripe5(struct stripe_head *sh)
2545 {
2546         raid5_conf_t *conf = sh->raid_conf;
2547         int disks = sh->disks, i;
2548         struct bio *return_bi = NULL;
2549         struct stripe_head_state s;
2550         struct r5dev *dev;
2551         mdk_rdev_t *blocked_rdev = NULL;
2552         int prexor;
2553
2554         memset(&s, 0, sizeof(s));
2555         pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d check:%d "
2556                  "reconstruct:%d\n", (unsigned long long)sh->sector, sh->state,
2557                  atomic_read(&sh->count), sh->pd_idx, sh->check_state,
2558                  sh->reconstruct_state);
2559
2560         spin_lock(&sh->lock);
2561         clear_bit(STRIPE_HANDLE, &sh->state);
2562         clear_bit(STRIPE_DELAYED, &sh->state);
2563
2564         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2565         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2566         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2567
2568         /* Now to look around and see what can be done */
2569         rcu_read_lock();
2570         for (i=disks; i--; ) {
2571                 mdk_rdev_t *rdev;
2572                 struct r5dev *dev = &sh->dev[i];
2573                 clear_bit(R5_Insync, &dev->flags);
2574
2575                 pr_debug("check %d: state 0x%lx toread %p read %p write %p "
2576                         "written %p\n", i, dev->flags, dev->toread, dev->read,
2577                         dev->towrite, dev->written);
2578
2579                 /* maybe we can request a biofill operation
2580                  *
2581                  * new wantfill requests are only permitted while
2582                  * ops_complete_biofill is guaranteed to be inactive
2583                  */
2584                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
2585                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
2586                         set_bit(R5_Wantfill, &dev->flags);
2587
2588                 /* now count some things */
2589                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2590                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2591                 if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;
2592
2593                 if (test_bit(R5_Wantfill, &dev->flags))
2594                         s.to_fill++;
2595                 else if (dev->toread)
2596                         s.to_read++;
2597                 if (dev->towrite) {
2598                         s.to_write++;
2599                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2600                                 s.non_overwrite++;
2601                 }
2602                 if (dev->written)
2603                         s.written++;
2604                 rdev = rcu_dereference(conf->disks[i].rdev);
2605                 if (blocked_rdev == NULL &&
2606                     rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
2607                         blocked_rdev = rdev;
2608                         atomic_inc(&rdev->nr_pending);
2609                 }
2610                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2611                         /* The ReadError flag will just be confusing now */
2612                         clear_bit(R5_ReadError, &dev->flags);
2613                         clear_bit(R5_ReWrite, &dev->flags);
2614                 }
2615                 if (!rdev || !test_bit(In_sync, &rdev->flags)
2616                     || test_bit(R5_ReadError, &dev->flags)) {
2617                         s.failed++;
2618                         s.failed_num = i;
2619                 } else
2620                         set_bit(R5_Insync, &dev->flags);
2621         }
2622         rcu_read_unlock();
2623
2624         if (unlikely(blocked_rdev)) {
2625                 if (s.syncing || s.expanding || s.expanded ||
2626                     s.to_write || s.written) {
2627                         set_bit(STRIPE_HANDLE, &sh->state);
2628                         goto unlock;
2629                 }
2630                 /* There is nothing for the blocked_rdev to block */
2631                 rdev_dec_pending(blocked_rdev, conf->mddev);
2632                 blocked_rdev = NULL;
2633         }
2634
2635         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
2636                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
2637                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
2638         }
2639
2640         pr_debug("locked=%d uptodate=%d to_read=%d"
2641                 " to_write=%d failed=%d failed_num=%d\n",
2642                 s.locked, s.uptodate, s.to_read, s.to_write,
2643                 s.failed, s.failed_num);
2644         /* check if the array has lost two devices and, if so, some requests might
2645          * need to be failed
2646          */
2647         if (s.failed > 1 && s.to_read+s.to_write+s.written)
2648                 handle_failed_stripe(conf, sh, &s, disks, &return_bi);
2649         if (s.failed > 1 && s.syncing) {
2650                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2651                 clear_bit(STRIPE_SYNCING, &sh->state);
2652                 s.syncing = 0;
2653         }
2654
2655         /* might be able to return some write requests if the parity block
2656          * is safe, or on a failed drive
2657          */
2658         dev = &sh->dev[sh->pd_idx];
2659         if ( s.written &&
2660              ((test_bit(R5_Insync, &dev->flags) &&
2661                !test_bit(R5_LOCKED, &dev->flags) &&
2662                test_bit(R5_UPTODATE, &dev->flags)) ||
2663                (s.failed == 1 && s.failed_num == sh->pd_idx)))
2664                 handle_stripe_clean_event(conf, sh, disks, &return_bi);
2665
2666         /* Now we might consider reading some blocks, either to check/generate
2667          * parity, or to satisfy requests
2668          * or to load a block that is being partially written.
2669          */
2670         if (s.to_read || s.non_overwrite ||
2671             (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
2672                 handle_stripe_fill5(sh, &s, disks);
2673
2674         /* Now we check to see if any write operations have recently
2675          * completed
2676          */
2677         prexor = 0;
2678         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
2679                 prexor = 1;
2680         if (sh->reconstruct_state == reconstruct_state_drain_result ||
2681             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
2682                 sh->reconstruct_state = reconstruct_state_idle;
2683
2684                 /* All the 'written' buffers and the parity block are ready to
2685                  * be written back to disk
2686                  */
2687                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
2688                 for (i = disks; i--; ) {
2689                         dev = &sh->dev[i];
2690                         if (test_bit(R5_LOCKED, &dev->flags) &&
2691                                 (i == sh->pd_idx || dev->written)) {
2692                                 pr_debug("Writing block %d\n", i);
2693                                 set_bit(R5_Wantwrite, &dev->flags);
2694                                 if (prexor)
2695                                         continue;
2696                                 if (!test_bit(R5_Insync, &dev->flags) ||
2697                                     (i == sh->pd_idx && s.failed == 0))
2698                                         set_bit(STRIPE_INSYNC, &sh->state);
2699                         }
2700                 }
2701                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2702                         atomic_dec(&conf->preread_active_stripes);
2703                         if (atomic_read(&conf->preread_active_stripes) <
2704                                 IO_THRESHOLD)
2705                                 md_wakeup_thread(conf->mddev->thread);
2706                 }
2707         }
2708
2709         /* Now to consider new write requests and what else, if anything
2710          * should be read.  We do not handle new writes when:
2711          * 1/ A 'write' operation (copy+xor) is already in flight.
2712          * 2/ A 'check' operation is in flight, as it may clobber the parity
2713          *    block.
2714          */
2715         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
2716                 handle_stripe_dirtying5(conf, sh, &s, disks);
2717
2718         /* maybe we need to check and possibly fix the parity for this stripe
2719          * Any reads will already have been scheduled, so we just see if enough
2720          * data is available.  The parity check is held off while parity
2721          * dependent operations are in flight.
2722          */
2723         if (sh->check_state ||
2724             (s.syncing && s.locked == 0 &&
2725              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
2726              !test_bit(STRIPE_INSYNC, &sh->state)))
2727                 handle_parity_checks5(conf, sh, &s, disks);
2728
2729         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2730                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2731                 clear_bit(STRIPE_SYNCING, &sh->state);
2732         }
2733
2734         /* If the failed drive is just a ReadError, then we might need to progress
2735          * the repair/check process
2736          */
2737         if (s.failed == 1 && !conf->mddev->ro &&
2738             test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
2739             && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
2740             && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
2741                 ) {
2742                 dev = &sh->dev[s.failed_num];
2743                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2744                         set_bit(R5_Wantwrite, &dev->flags);
2745                         set_bit(R5_ReWrite, &dev->flags);
2746                         set_bit(R5_LOCKED, &dev->flags);
2747                         s.locked++;
2748                 } else {
2749                         /* let's read it back */
2750                         set_bit(R5_Wantread, &dev->flags);
2751                         set_bit(R5_LOCKED, &dev->flags);
2752                         s.locked++;
2753                 }
2754         }
2755
2756         /* Finish reconstruct operations initiated by the expansion process */
2757         if (sh->reconstruct_state == reconstruct_state_result) {
2758                 sh->reconstruct_state = reconstruct_state_idle;
2759                 clear_bit(STRIPE_EXPANDING, &sh->state);
2760                 for (i = conf->raid_disks; i--; ) {
2761                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2762                         set_bit(R5_LOCKED, &sh->dev[i].flags);
2763                         s.locked++;
2764                 }
2765         }
2766
2767         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
2768             !sh->reconstruct_state) {
2769                 /* Need to write out all blocks after computing parity */
2770                 sh->disks = conf->raid_disks;
2771                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2772                         conf->raid_disks);
2773                 schedule_reconstruction5(sh, &s, 1, 1);
2774         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
2775                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
2776                 atomic_dec(&conf->reshape_stripes);
2777                 wake_up(&conf->wait_for_overlap);
2778                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2779         }
2780
2781         if (s.expanding && s.locked == 0 &&
2782             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
2783                 handle_stripe_expansion(conf, sh, NULL);
2784
2785  unlock:
2786         spin_unlock(&sh->lock);
2787
2788         /* wait for this device to become unblocked */
2789         if (unlikely(blocked_rdev))
2790                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
2791
2792         if (s.ops_request)
2793                 raid5_run_ops(sh, s.ops_request);
2794
2795         ops_run_io(sh, &s);
2796
2797         return_io(return_bi);
2798
2799         return blocked_rdev == NULL;
2800 }
2801
2802 static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
2803 {
2804         raid6_conf_t *conf = sh->raid_conf;
2805         int disks = sh->disks;
2806         struct bio *return_bi = NULL;
2807         int i, pd_idx = sh->pd_idx;
2808         struct stripe_head_state s;
2809         struct r6_state r6s;
2810         struct r5dev *dev, *pdev, *qdev;
2811         mdk_rdev_t *blocked_rdev = NULL;
2812
2813         r6s.qd_idx = raid6_next_disk(pd_idx, disks);
2814         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
2815                 "pd_idx=%d, qd_idx=%d\n",
2816                (unsigned long long)sh->sector, sh->state,
2817                atomic_read(&sh->count), pd_idx, r6s.qd_idx);
2818         memset(&s, 0, sizeof(s));
2819
2820         spin_lock(&sh->lock);
2821         clear_bit(STRIPE_HANDLE, &sh->state);
2822         clear_bit(STRIPE_DELAYED, &sh->state);
2823
2824         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2825         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2826         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2827         /* Now to look around and see what can be done */
2828
2829         rcu_read_lock();
2830         for (i=disks; i--; ) {
2831                 mdk_rdev_t *rdev;
2832                 dev = &sh->dev[i];
2833                 clear_bit(R5_Insync, &dev->flags);
2834
2835                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
2836                         i, dev->flags, dev->toread, dev->towrite, dev->written);
2837                 /* maybe we can reply to a read */
2838                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
2839                         struct bio *rbi, *rbi2;
2840                         pr_debug("Return read for disc %d\n", i);
2841                         spin_lock_irq(&conf->device_lock);
2842                         rbi = dev->toread;
2843                         dev->toread = NULL;
2844                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
2845                                 wake_up(&conf->wait_for_overlap);
2846                         spin_unlock_irq(&conf->device_lock);
2847                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
2848                                 copy_data(0, rbi, dev->page, dev->sector);
2849                                 rbi2 = r5_next_bio(rbi, dev->sector);
2850                                 spin_lock_irq(&conf->device_lock);
2851                                 if (!raid5_dec_bi_phys_segments(rbi)) {
2852                                         rbi->bi_next = return_bi;
2853                                         return_bi = rbi;
2854                                 }
2855                                 spin_unlock_irq(&conf->device_lock);
2856                                 rbi = rbi2;
2857                         }
2858                 }
2859
2860                 /* now count some things */
2861                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2862                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2863
2864
2865                 if (dev->toread)
2866                         s.to_read++;
2867                 if (dev->towrite) {
2868                         s.to_write++;
2869                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2870                                 s.non_overwrite++;
2871                 }
2872                 if (dev->written)
2873                         s.written++;
2874                 rdev = rcu_dereference(conf->disks[i].rdev);
2875                 if (blocked_rdev == NULL &&
2876                     rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
2877                         blocked_rdev = rdev;
2878                         atomic_inc(&rdev->nr_pending);
2879                 }
2880                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2881                         /* The ReadError flag will just be confusing now */
2882                         clear_bit(R5_ReadError, &dev->flags);
2883                         clear_bit(R5_ReWrite, &dev->flags);
2884                 }
2885                 if (!rdev || !test_bit(In_sync, &rdev->flags)
2886                     || test_bit(R5_ReadError, &dev->flags)) {
2887                         if (s.failed < 2)
2888                                 r6s.failed_num[s.failed] = i;
2889                         s.failed++;
2890                 } else
2891                         set_bit(R5_Insync, &dev->flags);
2892         }
2893         rcu_read_unlock();
2894
2895         if (unlikely(blocked_rdev)) {
2896                 if (s.syncing || s.expanding || s.expanded ||
2897                     s.to_write || s.written) {
2898                         set_bit(STRIPE_HANDLE, &sh->state);
2899                         goto unlock;
2900                 }
2901                 /* There is nothing for the blocked_rdev to block */
2902                 rdev_dec_pending(blocked_rdev, conf->mddev);
2903                 blocked_rdev = NULL;
2904         }
2905
2906         pr_debug("locked=%d uptodate=%d to_read=%d"
2907                " to_write=%d failed=%d failed_num=%d,%d\n",
2908                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
2909                r6s.failed_num[0], r6s.failed_num[1]);
2910         /* check if the array has lost >2 devices and, if so, some requests
2911          * might need to be failed
2912          */
2913         if (s.failed > 2 && s.to_read+s.to_write+s.written)
2914                 handle_failed_stripe(conf, sh, &s, disks, &return_bi);
2915         if (s.failed > 2 && s.syncing) {
2916                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2917                 clear_bit(STRIPE_SYNCING, &sh->state);
2918                 s.syncing = 0;
2919         }
2920
2921         /*
2922          * might be able to return some write requests if the parity blocks
2923          * are safe, or on a failed drive
2924          */
2925         pdev = &sh->dev[pd_idx];
2926         r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
2927                 || (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
2928         qdev = &sh->dev[r6s.qd_idx];
2929         r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == r6s.qd_idx)
2930                 || (s.failed >= 2 && r6s.failed_num[1] == r6s.qd_idx);
2931
2932         if ( s.written &&
2933              ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
2934                              && !test_bit(R5_LOCKED, &pdev->flags)
2935                              && test_bit(R5_UPTODATE, &pdev->flags)))) &&
2936              ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
2937                              && !test_bit(R5_LOCKED, &qdev->flags)
2938                              && test_bit(R5_UPTODATE, &qdev->flags)))))
2939                 handle_stripe_clean_event(conf, sh, disks, &return_bi);
2940
2941         /* Now we might consider reading some blocks, either to check/generate
2942          * parity, or to satisfy requests
2943          * or to load a block that is being partially written.
2944          */
2945         if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
2946             (s.syncing && (s.uptodate < disks)) || s.expanding)
2947                 handle_stripe_fill6(sh, &s, &r6s, disks);
2948
2949         /* now to consider writing and what else, if anything should be read */
2950         if (s.to_write)
2951                 handle_stripe_dirtying6(conf, sh, &s, &r6s, disks);
2952
2953         /* maybe we need to check and possibly fix the parity for this stripe
2954          * Any reads will already have been scheduled, so we just see if enough
2955          * data is available
2956          */
2957         if (s.syncing && s.locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state))
2958                 handle_parity_checks6(conf, sh, &s, &r6s, tmp_page, disks);
2959
2960         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2961                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2962                 clear_bit(STRIPE_SYNCING, &sh->state);
2963         }
2964
2965         /* If the failed drives are just a ReadError, then we might need
2966          * to progress the repair/check process
2967          */
2968         if (s.failed <= 2 && !conf->mddev->ro)
2969                 for (i = 0; i < s.failed; i++) {
2970                         dev = &sh->dev[r6s.failed_num[i]];
2971                         if (test_bit(R5_ReadError, &dev->flags)
2972                             && !test_bit(R5_LOCKED, &dev->flags)
2973                             && test_bit(R5_UPTODATE, &dev->flags)
2974                                 ) {
2975                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2976                                         set_bit(R5_Wantwrite, &dev->flags);
2977                                         set_bit(R5_ReWrite, &dev->flags);
2978                                         set_bit(R5_LOCKED, &dev->flags);
2979                                 } else {
2980                                         /* let's read it back */
2981                                         set_bit(R5_Wantread, &dev->flags);
2982                                         set_bit(R5_LOCKED, &dev->flags);
2983                                 }
2984                         }
2985                 }
2986
2987         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
2988                 /* Need to write out all blocks after computing P&Q */
2989                 sh->disks = conf->raid_disks;
2990                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2991                                              conf->raid_disks);
2992                 compute_parity6(sh, RECONSTRUCT_WRITE);
2993                 for (i = conf->raid_disks ; i-- ;  ) {
2994                         set_bit(R5_LOCKED, &sh->dev[i].flags);
2995                         s.locked++;
2996                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2997                 }
2998                 clear_bit(STRIPE_EXPANDING, &sh->state);
2999         } else if (s.expanded) {
3000                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3001                 atomic_dec(&conf->reshape_stripes);
3002                 wake_up(&conf->wait_for_overlap);
3003                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3004         }
3005
3006         if (s.expanding && s.locked == 0 &&
3007             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3008                 handle_stripe_expansion(conf, sh, &r6s);
3009
3010  unlock:
3011         spin_unlock(&sh->lock);
3012
3013         /* wait for this device to become unblocked */
3014         if (unlikely(blocked_rdev))
3015                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
3016
3017         ops_run_io(sh, &s);
3018
3019         return_io(return_bi);
3020
3021         return blocked_rdev == NULL;
3022 }
3023
3024 /* returns true if the stripe was handled */
3025 static bool handle_stripe(struct stripe_head *sh, struct page *tmp_page)
3026 {
3027         if (sh->raid_conf->level == 6)
3028                 return handle_stripe6(sh, tmp_page);
3029         else
3030                 return handle_stripe5(sh);
3031 }
3032
3033
3034
3035 static void raid5_activate_delayed(raid5_conf_t *conf)
3036 {
3037         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3038                 while (!list_empty(&conf->delayed_list)) {
3039                         struct list_head *l = conf->delayed_list.next;
3040                         struct stripe_head *sh;
3041                         sh = list_entry(l, struct stripe_head, lru);
3042                         list_del_init(l);
3043                         clear_bit(STRIPE_DELAYED, &sh->state);
3044                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3045                                 atomic_inc(&conf->preread_active_stripes);
3046                         list_add_tail(&sh->lru, &conf->hold_list);
3047                 }
3048         } else
3049                 blk_plug_device(conf->mddev->queue);
3050 }
3051
3052 static void activate_bit_delay(raid5_conf_t *conf)
3053 {
3054         /* device_lock is held */
3055         struct list_head head;
3056         list_add(&head, &conf->bitmap_list);
3057         list_del_init(&conf->bitmap_list);
3058         while (!list_empty(&head)) {
3059                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3060                 list_del_init(&sh->lru);
3061                 atomic_inc(&sh->count);
3062                 __release_stripe(conf, sh);
3063         }
3064 }
3065
3066 static void unplug_slaves(mddev_t *mddev)
3067 {
3068         raid5_conf_t *conf = mddev_to_conf(mddev);
3069         int i;
3070
3071         rcu_read_lock();
3072         for (i=0; i<mddev->raid_disks; i++) {
3073                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3074                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
3075                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
3076
3077                         atomic_inc(&rdev->nr_pending);
3078                         rcu_read_unlock();
3079
3080                         blk_unplug(r_queue);
3081
3082                         rdev_dec_pending(rdev, mddev);
3083                         rcu_read_lock();
3084                 }
3085         }
3086         rcu_read_unlock();
3087 }
3088
3089 static void raid5_unplug_device(struct request_queue *q)
3090 {
3091         mddev_t *mddev = q->queuedata;
3092         raid5_conf_t *conf = mddev_to_conf(mddev);
3093         unsigned long flags;
3094
3095         spin_lock_irqsave(&conf->device_lock, flags);
3096
3097         if (blk_remove_plug(q)) {
3098                 conf->seq_flush++;
3099                 raid5_activate_delayed(conf);
3100         }
3101         md_wakeup_thread(mddev->thread);
3102
3103         spin_unlock_irqrestore(&conf->device_lock, flags);
3104
3105         unplug_slaves(mddev);
3106 }
3107
3108 static int raid5_congested(void *data, int bits)
3109 {
3110         mddev_t *mddev = data;
3111         raid5_conf_t *conf = mddev_to_conf(mddev);
3112
3113         /* No difference between reads and writes.  Just check
3114          * how busy the stripe_cache is
3115          */
3116         if (conf->inactive_blocked)
3117                 return 1;
3118         if (conf->quiesce)
3119                 return 1;
3120         if (list_empty_careful(&conf->inactive_list))
3121                 return 1;
3122
3123         return 0;
3124 }
3125
3126 /* We want read requests to align with chunks where possible,
3127  * but write requests don't need to.
3128  */
3129 static int raid5_mergeable_bvec(struct request_queue *q,
3130                                 struct bvec_merge_data *bvm,
3131                                 struct bio_vec *biovec)
3132 {
3133         mddev_t *mddev = q->queuedata;
3134         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3135         int max;
3136         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3137         unsigned int bio_sectors = bvm->bi_size >> 9;
3138
3139         if ((bvm->bi_rw & 1) == WRITE)
3140                 return biovec->bv_len; /* always allow writes to be mergeable */
3141
3142         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3143         if (max < 0) max = 0;
3144         if (max <= biovec->bv_len && bio_sectors == 0)
3145                 return biovec->bv_len;
3146         else
3147                 return max;
3148 }
3149
3150
3151 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3152 {
3153         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3154         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3155         unsigned int bio_sectors = bio->bi_size >> 9;
3156
3157         return  chunk_sectors >=
3158                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3159 }
3160
3161 /*
3162  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3163  *  later sampled by raid5d.
3164  */
3165 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3166 {
3167         unsigned long flags;
3168
3169         spin_lock_irqsave(&conf->device_lock, flags);
3170
3171         bi->bi_next = conf->retry_read_aligned_list;
3172         conf->retry_read_aligned_list = bi;
3173
3174         spin_unlock_irqrestore(&conf->device_lock, flags);
3175         md_wakeup_thread(conf->mddev->thread);
3176 }
3177
3178
3179 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3180 {
3181         struct bio *bi;
3182
3183         bi = conf->retry_read_aligned;
3184         if (bi) {
3185                 conf->retry_read_aligned = NULL;
3186                 return bi;
3187         }
3188         bi = conf->retry_read_aligned_list;
3189         if(bi) {
3190                 conf->retry_read_aligned_list = bi->bi_next;
3191                 bi->bi_next = NULL;
3192                 /*
3193                  * this sets the active strip count to 1 and the processed
3194                  * strip count to zero (upper 8 bits)
3195                  */
3196                 bi->bi_phys_segments = 1; /* biased count of active stripes */
3197         }
3198
3199         return bi;
3200 }
3201
3202
3203 /*
3204  *  The "raid5_align_endio" should check if the read succeeded and if it
3205  *  did, call bio_endio on the original bio (having bio_put the new bio
3206  *  first).
3207  *  If the read failed..
3208  */
3209 static void raid5_align_endio(struct bio *bi, int error)
3210 {
3211         struct bio* raid_bi  = bi->bi_private;
3212         mddev_t *mddev;
3213         raid5_conf_t *conf;
3214         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3215         mdk_rdev_t *rdev;
3216
3217         bio_put(bi);
3218
3219         mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
3220         conf = mddev_to_conf(mddev);
3221         rdev = (void*)raid_bi->bi_next;
3222         raid_bi->bi_next = NULL;
3223
3224         rdev_dec_pending(rdev, conf->mddev);
3225
3226         if (!error && uptodate) {
3227                 bio_endio(raid_bi, 0);
3228                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3229                         wake_up(&conf->wait_for_stripe);
3230                 return;
3231         }
3232
3233
3234         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3235
3236         add_bio_to_retry(raid_bi, conf);
3237 }
3238
3239 static int bio_fits_rdev(struct bio *bi)
3240 {
3241         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3242
3243         if ((bi->bi_size>>9) > q->max_sectors)
3244                 return 0;
3245         blk_recount_segments(q, bi);
3246         if (bi->bi_phys_segments > q->max_phys_segments)
3247                 return 0;
3248
3249         if (q->merge_bvec_fn)
3250                 /* it's too hard to apply the merge_bvec_fn at this stage,
3251                  * just just give up
3252                  */
3253                 return 0;
3254
3255         return 1;
3256 }
3257
3258
3259 static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
3260 {
3261         mddev_t *mddev = q->queuedata;
3262         raid5_conf_t *conf = mddev_to_conf(mddev);
3263         const unsigned int raid_disks = conf->raid_disks;
3264         const unsigned int data_disks = raid_disks - conf->max_degraded;
3265         unsigned int dd_idx, pd_idx;
3266         struct bio* align_bi;
3267         mdk_rdev_t *rdev;
3268
3269         if (!in_chunk_boundary(mddev, raid_bio)) {
3270                 pr_debug("chunk_aligned_read : non aligned\n");
3271                 return 0;
3272         }
3273         /*
3274          * use bio_clone to make a copy of the bio
3275          */
3276         align_bi = bio_clone(raid_bio, GFP_NOIO);
3277         if (!align_bi)
3278                 return 0;
3279         /*
3280          *   set bi_end_io to a new function, and set bi_private to the
3281          *     original bio.
3282          */
3283         align_bi->bi_end_io  = raid5_align_endio;
3284         align_bi->bi_private = raid_bio;
3285         /*
3286          *      compute position
3287          */
3288         align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
3289                                         raid_disks,
3290                                         data_disks,
3291                                         &dd_idx,
3292                                         &pd_idx,
3293                                         conf);
3294
3295         rcu_read_lock();
3296         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3297         if (rdev && test_bit(In_sync, &rdev->flags)) {
3298                 atomic_inc(&rdev->nr_pending);
3299                 rcu_read_unlock();
3300                 raid_bio->bi_next = (void*)rdev;
3301                 align_bi->bi_bdev =  rdev->bdev;
3302                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3303                 align_bi->bi_sector += rdev->data_offset;
3304
3305                 if (!bio_fits_rdev(align_bi)) {
3306                         /* too big in some way */
3307                         bio_put(align_bi);
3308                         rdev_dec_pending(rdev, mddev);
3309                         return 0;
3310                 }
3311
3312                 spin_lock_irq(&conf->device_lock);
3313                 wait_event_lock_irq(conf->wait_for_stripe,
3314                                     conf->quiesce == 0,
3315                                     conf->device_lock, /* nothing */);
3316                 atomic_inc(&conf->active_aligned_reads);
3317                 spin_unlock_irq(&conf->device_lock);
3318
3319                 generic_make_request(align_bi);
3320                 return 1;
3321         } else {
3322                 rcu_read_unlock();
3323                 bio_put(align_bi);
3324                 return 0;
3325         }
3326 }
3327
3328 /* __get_priority_stripe - get the next stripe to process
3329  *
3330  * Full stripe writes are allowed to pass preread active stripes up until
3331  * the bypass_threshold is exceeded.  In general the bypass_count
3332  * increments when the handle_list is handled before the hold_list; however, it
3333  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
3334  * stripe with in flight i/o.  The bypass_count will be reset when the
3335  * head of the hold_list has changed, i.e. the head was promoted to the
3336  * handle_list.
3337  */
3338 static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
3339 {
3340         struct stripe_head *sh;
3341
3342         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
3343                   __func__,
3344                   list_empty(&conf->handle_list) ? "empty" : "busy",
3345                   list_empty(&conf->hold_list) ? "empty" : "busy",
3346                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
3347
3348         if (!list_empty(&conf->handle_list)) {
3349                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
3350
3351                 if (list_empty(&conf->hold_list))
3352                         conf->bypass_count = 0;
3353                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
3354                         if (conf->hold_list.next == conf->last_hold)
3355                                 conf->bypass_count++;
3356                         else {
3357                                 conf->last_hold = conf->hold_list.next;
3358                                 conf->bypass_count -= conf->bypass_threshold;
3359                                 if (conf->bypass_count < 0)
3360                                         conf->bypass_count = 0;
3361                         }
3362                 }
3363         } else if (!list_empty(&conf->hold_list) &&
3364                    ((conf->bypass_threshold &&
3365                      conf->bypass_count > conf->bypass_threshold) ||
3366                     atomic_read(&conf->pending_full_writes) == 0)) {
3367                 sh = list_entry(conf->hold_list.next,
3368                                 typeof(*sh), lru);
3369                 conf->bypass_count -= conf->bypass_threshold;
3370                 if (conf->bypass_count < 0)
3371                         conf->bypass_count = 0;
3372         } else
3373                 return NULL;
3374
3375         list_del_init(&sh->lru);
3376         atomic_inc(&sh->count);
3377         BUG_ON(atomic_read(&sh->count) != 1);
3378         return sh;
3379 }
3380
3381 static int make_request(struct request_queue *q, struct bio * bi)
3382 {
3383         mddev_t *mddev = q->queuedata;
3384         raid5_conf_t *conf = mddev_to_conf(mddev);
3385         unsigned int dd_idx, pd_idx;
3386         sector_t new_sector;
3387         sector_t logical_sector, last_sector;
3388         struct stripe_head *sh;
3389         const int rw = bio_data_dir(bi);
3390         int remaining;
3391
3392         if (unlikely(bio_barrier(bi))) {
3393                 bio_endio(bi, -EOPNOTSUPP);
3394                 return 0;
3395         }
3396
3397         md_write_start(mddev, bi);
3398
3399         disk_stat_inc(mddev->gendisk, ios[rw]);
3400         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
3401
3402         if (rw == READ &&
3403              mddev->reshape_position == MaxSector &&
3404              chunk_aligned_read(q,bi))
3405                 return 0;
3406
3407         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3408         last_sector = bi->bi_sector + (bi->bi_size>>9);
3409         bi->bi_next = NULL;
3410         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
3411
3412         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
3413                 DEFINE_WAIT(w);
3414                 int disks, data_disks;
3415
3416         retry:
3417                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
3418                 if (likely(conf->expand_progress == MaxSector))
3419                         disks = conf->raid_disks;
3420                 else {
3421                         /* spinlock is needed as expand_progress may be
3422                          * 64bit on a 32bit platform, and so it might be
3423                          * possible to see a half-updated value
3424                          * Ofcourse expand_progress could change after
3425                          * the lock is dropped, so once we get a reference
3426                          * to the stripe that we think it is, we will have
3427                          * to check again.
3428                          */
3429                         spin_lock_irq(&conf->device_lock);
3430                         disks = conf->raid_disks;
3431                         if (logical_sector >= conf->expand_progress)
3432                                 disks = conf->previous_raid_disks;
3433                         else {
3434                                 if (logical_sector >= conf->expand_lo) {
3435                                         spin_unlock_irq(&conf->device_lock);
3436                                         schedule();
3437                                         goto retry;
3438                                 }
3439                         }
3440                         spin_unlock_irq(&conf->device_lock);
3441                 }
3442                 data_disks = disks - conf->max_degraded;
3443
3444                 new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
3445                                                   &dd_idx, &pd_idx, conf);
3446                 pr_debug("raid5: make_request, sector %llu logical %llu\n",
3447                         (unsigned long long)new_sector, 
3448                         (unsigned long long)logical_sector);
3449
3450                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
3451                 if (sh) {
3452                         if (unlikely(conf->expand_progress != MaxSector)) {
3453                                 /* expansion might have moved on while waiting for a
3454                                  * stripe, so we must do the range check again.
3455                                  * Expansion could still move past after this
3456                                  * test, but as we are holding a reference to
3457                                  * 'sh', we know that if that happens,
3458                                  *  STRIPE_EXPANDING will get set and the expansion
3459                                  * won't proceed until we finish with the stripe.
3460                                  */
3461                                 int must_retry = 0;
3462                                 spin_lock_irq(&conf->device_lock);
3463                                 if (logical_sector <  conf->expand_progress &&
3464                                     disks == conf->previous_raid_disks)
3465                                         /* mismatch, need to try again */
3466                                         must_retry = 1;
3467                                 spin_unlock_irq(&conf->device_lock);
3468                                 if (must_retry) {
3469                                         release_stripe(sh);
3470                                         goto retry;
3471                                 }
3472                         }
3473                         /* FIXME what if we get a false positive because these
3474                          * are being updated.
3475                          */
3476                         if (logical_sector >= mddev->suspend_lo &&
3477                             logical_sector < mddev->suspend_hi) {
3478                                 release_stripe(sh);
3479                                 schedule();
3480                                 goto retry;
3481                         }
3482
3483                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
3484                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
3485                                 /* Stripe is busy expanding or
3486                                  * add failed due to overlap.  Flush everything
3487                                  * and wait a while
3488                                  */
3489                                 raid5_unplug_device(mddev->queue);
3490                                 release_stripe(sh);
3491                                 schedule();
3492                                 goto retry;
3493                         }
3494                         finish_wait(&conf->wait_for_overlap, &w);
3495                         set_bit(STRIPE_HANDLE, &sh->state);
3496                         clear_bit(STRIPE_DELAYED, &sh->state);
3497                         release_stripe(sh);
3498                 } else {
3499                         /* cannot get stripe for read-ahead, just give-up */
3500                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3501                         finish_wait(&conf->wait_for_overlap, &w);
3502                         break;
3503                 }
3504                         
3505         }
3506         spin_lock_irq(&conf->device_lock);
3507         remaining = raid5_dec_bi_phys_segments(bi);
3508         spin_unlock_irq(&conf->device_lock);
3509         if (remaining == 0) {
3510
3511                 if ( rw == WRITE )
3512                         md_write_end(mddev);
3513
3514                 bio_endio(bi, 0);
3515         }
3516         return 0;
3517 }
3518
3519 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
3520 {
3521         /* reshaping is quite different to recovery/resync so it is
3522          * handled quite separately ... here.
3523          *
3524          * On each call to sync_request, we gather one chunk worth of
3525          * destination stripes and flag them as expanding.
3526          * Then we find all the source stripes and request reads.
3527          * As the reads complete, handle_stripe will copy the data
3528          * into the destination stripe and release that stripe.
3529          */
3530         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3531         struct stripe_head *sh;
3532         int pd_idx;
3533         sector_t first_sector, last_sector;
3534         int raid_disks = conf->previous_raid_disks;
3535         int data_disks = raid_disks - conf->max_degraded;
3536         int new_data_disks = conf->raid_disks - conf->max_degraded;
3537         int i;
3538         int dd_idx;
3539         sector_t writepos, safepos, gap;
3540
3541         if (sector_nr == 0 &&
3542             conf->expand_progress != 0) {
3543                 /* restarting in the middle, skip the initial sectors */
3544                 sector_nr = conf->expand_progress;
3545                 sector_div(sector_nr, new_data_disks);
3546                 *skipped = 1;
3547                 return sector_nr;
3548         }
3549
3550         /* we update the metadata when there is more than 3Meg
3551          * in the block range (that is rather arbitrary, should
3552          * probably be time based) or when the data about to be
3553          * copied would over-write the source of the data at
3554          * the front of the range.
3555          * i.e. one new_stripe forward from expand_progress new_maps
3556          * to after where expand_lo old_maps to
3557          */
3558         writepos = conf->expand_progress +
3559                 conf->chunk_size/512*(new_data_disks);
3560         sector_div(writepos, new_data_disks);
3561         safepos = conf->expand_lo;
3562         sector_div(safepos, data_disks);
3563         gap = conf->expand_progress - conf->expand_lo;
3564
3565         if (writepos >= safepos ||
3566             gap > (new_data_disks)*3000*2 /*3Meg*/) {
3567                 /* Cannot proceed until we've updated the superblock... */
3568                 wait_event(conf->wait_for_overlap,
3569                            atomic_read(&conf->reshape_stripes)==0);
3570                 mddev->reshape_position = conf->expand_progress;
3571                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3572                 md_wakeup_thread(mddev->thread);
3573                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
3574                            kthread_should_stop());
3575                 spin_lock_irq(&conf->device_lock);
3576                 conf->expand_lo = mddev->reshape_position;
3577                 spin_unlock_irq(&conf->device_lock);
3578                 wake_up(&conf->wait_for_overlap);
3579         }
3580
3581         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
3582                 int j;
3583                 int skipped = 0;
3584                 pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
3585                 sh = get_active_stripe(conf, sector_nr+i,
3586                                        conf->raid_disks, pd_idx, 0);
3587                 set_bit(STRIPE_EXPANDING, &sh->state);
3588                 atomic_inc(&conf->reshape_stripes);
3589                 /* If any of this stripe is beyond the end of the old
3590                  * array, then we need to zero those blocks
3591                  */
3592                 for (j=sh->disks; j--;) {
3593                         sector_t s;
3594                         if (j == sh->pd_idx)
3595                                 continue;
3596                         if (conf->level == 6 &&
3597                             j == raid6_next_disk(sh->pd_idx, sh->disks))
3598                                 continue;
3599                         s = compute_blocknr(sh, j);
3600                         if (s < mddev->array_sectors) {
3601                                 skipped = 1;
3602                                 continue;
3603                         }
3604                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
3605                         set_bit(R5_Expanded, &sh->dev[j].flags);
3606                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
3607                 }
3608                 if (!skipped) {
3609                         set_bit(STRIPE_EXPAND_READY, &sh->state);
3610                         set_bit(STRIPE_HANDLE, &sh->state);
3611                 }
3612                 release_stripe(sh);
3613         }
3614         spin_lock_irq(&conf->device_lock);
3615         conf->expand_progress = (sector_nr + i) * new_data_disks;
3616         spin_unlock_irq(&conf->device_lock);
3617         /* Ok, those stripe are ready. We can start scheduling
3618          * reads on the source stripes.
3619          * The source stripes are determined by mapping the first and last
3620          * block on the destination stripes.
3621          */
3622         first_sector =
3623                 raid5_compute_sector(sector_nr*(new_data_disks),
3624                                      raid_disks, data_disks,
3625                                      &dd_idx, &pd_idx, conf);
3626         last_sector =
3627                 raid5_compute_sector((sector_nr+conf->chunk_size/512)
3628                                      *(new_data_disks) -1,
3629                                      raid_disks, data_disks,
3630                                      &dd_idx, &pd_idx, conf);
3631         if (last_sector >= (mddev->size<<1))
3632                 last_sector = (mddev->size<<1)-1;
3633         while (first_sector <= last_sector) {
3634                 pd_idx = stripe_to_pdidx(first_sector, conf,
3635                                          conf->previous_raid_disks);
3636                 sh = get_active_stripe(conf, first_sector,
3637                                        conf->previous_raid_disks, pd_idx, 0);
3638                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3639                 set_bit(STRIPE_HANDLE, &sh->state);
3640                 release_stripe(sh);
3641                 first_sector += STRIPE_SECTORS;
3642         }
3643         /* If this takes us to the resync_max point where we have to pause,
3644          * then we need to write out the superblock.
3645          */
3646         sector_nr += conf->chunk_size>>9;
3647         if (sector_nr >= mddev->resync_max) {
3648                 /* Cannot proceed until we've updated the superblock... */
3649                 wait_event(conf->wait_for_overlap,
3650                            atomic_read(&conf->reshape_stripes) == 0);
3651                 mddev->reshape_position = conf->expand_progress;
3652                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3653                 md_wakeup_thread(mddev->thread);
3654                 wait_event(mddev->sb_wait,
3655                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
3656                            || kthread_should_stop());
3657                 spin_lock_irq(&conf->device_lock);
3658                 conf->expand_lo = mddev->reshape_position;
3659                 spin_unlock_irq(&conf->device_lock);
3660                 wake_up(&conf->wait_for_overlap);
3661         }
3662         return conf->chunk_size>>9;
3663 }
3664
3665 /* FIXME go_faster isn't used */
3666 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
3667 {
3668         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3669         struct stripe_head *sh;
3670         int pd_idx;
3671         int raid_disks = conf->raid_disks;
3672         sector_t max_sector = mddev->size << 1;
3673         int sync_blocks;
3674         int still_degraded = 0;
3675         int i;
3676
3677         if (sector_nr >= max_sector) {
3678                 /* just being told to finish up .. nothing much to do */
3679                 unplug_slaves(mddev);
3680                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
3681                         end_reshape(conf);
3682                         return 0;
3683                 }
3684
3685                 if (mddev->curr_resync < max_sector) /* aborted */
3686                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
3687                                         &sync_blocks, 1);
3688                 else /* completed sync */
3689                         conf->fullsync = 0;
3690                 bitmap_close_sync(mddev->bitmap);
3691
3692                 return 0;
3693         }
3694
3695         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3696                 return reshape_request(mddev, sector_nr, skipped);
3697
3698         /* No need to check resync_max as we never do more than one
3699          * stripe, and as resync_max will always be on a chunk boundary,
3700          * if the check in md_do_sync didn't fire, there is no chance
3701          * of overstepping resync_max here
3702          */
3703
3704         /* if there is too many failed drives and we are trying
3705          * to resync, then assert that we are finished, because there is
3706          * nothing we can do.
3707          */
3708         if (mddev->degraded >= conf->max_degraded &&
3709             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3710                 sector_t rv = (mddev->size << 1) - sector_nr;
3711                 *skipped = 1;
3712                 return rv;
3713         }
3714         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
3715             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
3716             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
3717                 /* we can skip this block, and probably more */
3718                 sync_blocks /= STRIPE_SECTORS;
3719                 *skipped = 1;
3720                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
3721         }
3722
3723
3724         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3725
3726         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
3727         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
3728         if (sh == NULL) {
3729                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
3730                 /* make sure we don't swamp the stripe cache if someone else
3731                  * is trying to get access
3732                  */
3733                 schedule_timeout_uninterruptible(1);
3734         }
3735         /* Need to check if array will still be degraded after recovery/resync
3736          * We don't need to check the 'failed' flag as when that gets set,
3737          * recovery aborts.
3738          */
3739         for (i=0; i<mddev->raid_disks; i++)
3740                 if (conf->disks[i].rdev == NULL)
3741                         still_degraded = 1;
3742
3743         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
3744
3745         spin_lock(&sh->lock);
3746         set_bit(STRIPE_SYNCING, &sh->state);
3747         clear_bit(STRIPE_INSYNC, &sh->state);
3748         spin_unlock(&sh->lock);
3749
3750         /* wait for any blocked device to be handled */
3751         while(unlikely(!handle_stripe(sh, NULL)))
3752                 ;
3753         release_stripe(sh);
3754
3755         return STRIPE_SECTORS;
3756 }
3757
3758 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
3759 {
3760         /* We may not be able to submit a whole bio at once as there
3761          * may not be enough stripe_heads available.
3762          * We cannot pre-allocate enough stripe_heads as we may need
3763          * more than exist in the cache (if we allow ever large chunks).
3764          * So we do one stripe head at a time and record in
3765          * ->bi_hw_segments how many have been done.
3766          *
3767          * We *know* that this entire raid_bio is in one chunk, so
3768          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
3769          */
3770         struct stripe_head *sh;
3771         int dd_idx, pd_idx;
3772         sector_t sector, logical_sector, last_sector;
3773         int scnt = 0;
3774         int remaining;
3775         int handled = 0;
3776
3777         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3778         sector = raid5_compute_sector(  logical_sector,
3779                                         conf->raid_disks,
3780                                         conf->raid_disks - conf->max_degraded,
3781                                         &dd_idx,
3782                                         &pd_idx,
3783                                         conf);
3784         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
3785
3786         for (; logical_sector < last_sector;
3787              logical_sector += STRIPE_SECTORS,
3788                      sector += STRIPE_SECTORS,
3789                      scnt++) {
3790
3791                 if (scnt < raid5_bi_hw_segments(raid_bio))
3792                         /* already done this stripe */
3793                         continue;
3794
3795                 sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
3796
3797                 if (!sh) {
3798                         /* failed to get a stripe - must wait */
3799                         raid5_set_bi_hw_segments(raid_bio, scnt);
3800                         conf->retry_read_aligned = raid_bio;
3801                         return handled;
3802                 }
3803
3804                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
3805                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
3806                         release_stripe(sh);
3807                         raid5_set_bi_hw_segments(raid_bio, scnt);
3808                         conf->retry_read_aligned = raid_bio;
3809                         return handled;
3810                 }
3811
3812                 handle_stripe(sh, NULL);
3813                 release_stripe(sh);
3814                 handled++;
3815         }
3816         spin_lock_irq(&conf->device_lock);
3817         remaining = raid5_dec_bi_phys_segments(raid_bio);
3818         spin_unlock_irq(&conf->device_lock);
3819         if (remaining == 0)
3820                 bio_endio(raid_bio, 0);
3821         if (atomic_dec_and_test(&conf->active_aligned_reads))
3822                 wake_up(&conf->wait_for_stripe);
3823         return handled;
3824 }
3825
3826
3827
3828 /*
3829  * This is our raid5 kernel thread.
3830  *
3831  * We scan the hash table for stripes which can be handled now.
3832  * During the scan, completed stripes are saved for us by the interrupt
3833  * handler, so that they will not have to wait for our next wakeup.
3834  */
3835 static void raid5d(mddev_t *mddev)
3836 {
3837         struct stripe_head *sh;
3838         raid5_conf_t *conf = mddev_to_conf(mddev);
3839         int handled;
3840
3841         pr_debug("+++ raid5d active\n");
3842
3843         md_check_recovery(mddev);
3844
3845         handled = 0;
3846         spin_lock_irq(&conf->device_lock);
3847         while (1) {
3848                 struct bio *bio;
3849
3850                 if (conf->seq_flush != conf->seq_write) {
3851                         int seq = conf->seq_flush;
3852                         spin_unlock_irq(&conf->device_lock);
3853                         bitmap_unplug(mddev->bitmap);
3854                         spin_lock_irq(&conf->device_lock);
3855                         conf->seq_write = seq;
3856                         activate_bit_delay(conf);
3857                 }
3858
3859                 while ((bio = remove_bio_from_retry(conf))) {
3860                         int ok;
3861                         spin_unlock_irq(&conf->device_lock);
3862                         ok = retry_aligned_read(conf, bio);
3863                         spin_lock_irq(&conf->device_lock);
3864                         if (!ok)
3865                                 break;
3866                         handled++;
3867                 }
3868
3869                 sh = __get_priority_stripe(conf);
3870
3871                 if (!sh)
3872                         break;
3873                 spin_unlock_irq(&conf->device_lock);
3874                 
3875                 handled++;
3876                 handle_stripe(sh, conf->spare_page);
3877                 release_stripe(sh);
3878
3879                 spin_lock_irq(&conf->device_lock);
3880         }
3881         pr_debug("%d stripes handled\n", handled);
3882
3883         spin_unlock_irq(&conf->device_lock);
3884
3885         async_tx_issue_pending_all();
3886         unplug_slaves(mddev);
3887
3888         pr_debug("--- raid5d inactive\n");
3889 }
3890
3891 static ssize_t
3892 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
3893 {
3894         raid5_conf_t *conf = mddev_to_conf(mddev);
3895         if (conf)
3896                 return sprintf(page, "%d\n", conf->max_nr_stripes);
3897         else
3898                 return 0;
3899 }
3900
3901 static ssize_t
3902 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
3903 {
3904         raid5_conf_t *conf = mddev_to_conf(mddev);
3905         unsigned long new;
3906         int err;
3907
3908         if (len >= PAGE_SIZE)
3909                 return -EINVAL;
3910         if (!conf)
3911                 return -ENODEV;
3912
3913         if (strict_strtoul(page, 10, &new))
3914                 return -EINVAL;
3915         if (new <= 16 || new > 32768)
3916                 return -EINVAL;
3917         while (new < conf->max_nr_stripes) {
3918                 if (drop_one_stripe(conf))
3919                         conf->max_nr_stripes--;
3920                 else
3921                         break;
3922         }
3923         err = md_allow_write(mddev);
3924         if (err)
3925                 return err;
3926         while (new > conf->max_nr_stripes) {
3927                 if (grow_one_stripe(conf))
3928                         conf->max_nr_stripes++;
3929                 else break;
3930         }
3931         return len;
3932 }
3933
3934 static struct md_sysfs_entry
3935 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
3936                                 raid5_show_stripe_cache_size,
3937                                 raid5_store_stripe_cache_size);
3938
3939 static ssize_t
3940 raid5_show_preread_threshold(mddev_t *mddev, char *page)
3941 {
3942         raid5_conf_t *conf = mddev_to_conf(mddev);
3943         if (conf)
3944                 return sprintf(page, "%d\n", conf->bypass_threshold);
3945         else
3946                 return 0;
3947 }
3948
3949 static ssize_t
3950 raid5_store_preread_threshold(mddev_t *mddev, const char *page, size_t len)
3951 {
3952         raid5_conf_t *conf = mddev_to_conf(mddev);
3953         unsigned long new;
3954         if (len >= PAGE_SIZE)
3955                 return -EINVAL;
3956         if (!conf)
3957                 return -ENODEV;
3958
3959         if (strict_strtoul(page, 10, &new))
3960                 return -EINVAL;
3961         if (new > conf->max_nr_stripes)
3962                 return -EINVAL;
3963         conf->bypass_threshold = new;
3964         return len;
3965 }
3966
3967 static struct md_sysfs_entry
3968 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
3969                                         S_IRUGO | S_IWUSR,
3970                                         raid5_show_preread_threshold,
3971                                         raid5_store_preread_threshold);
3972
3973 static ssize_t
3974 stripe_cache_active_show(mddev_t *mddev, char *page)
3975 {
3976         raid5_conf_t *conf = mddev_to_conf(mddev);
3977         if (conf)
3978                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
3979         else
3980                 return 0;
3981 }
3982
3983 static struct md_sysfs_entry
3984 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
3985
3986 static struct attribute *raid5_attrs[] =  {
3987         &raid5_stripecache_size.attr,
3988         &raid5_stripecache_active.attr,
3989         &raid5_preread_bypass_threshold.attr,
3990         NULL,
3991 };
3992 static struct attribute_group raid5_attrs_group = {
3993         .name = NULL,
3994         .attrs = raid5_attrs,
3995 };
3996
3997 static int run(mddev_t *mddev)
3998 {
3999         raid5_conf_t *conf;
4000         int raid_disk, memory;
4001         mdk_rdev_t *rdev;
4002         struct disk_info *disk;
4003         struct list_head *tmp;
4004         int working_disks = 0;
4005
4006         if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
4007                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
4008                        mdname(mddev), mddev->level);
4009                 return -EIO;
4010         }
4011
4012         if (mddev->reshape_position != MaxSector) {
4013                 /* Check that we can continue the reshape.
4014                  * Currently only disks can change, it must
4015                  * increase, and we must be past the point where
4016                  * a stripe over-writes itself
4017                  */
4018                 sector_t here_new, here_old;
4019                 int old_disks;
4020                 int max_degraded = (mddev->level == 5 ? 1 : 2);
4021
4022                 if (mddev->new_level != mddev->level ||
4023                     mddev->new_layout != mddev->layout ||
4024                     mddev->new_chunk != mddev->chunk_size) {
4025                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4026                                "required - aborting.\n",
4027                                mdname(mddev));
4028                         return -EINVAL;
4029                 }
4030                 if (mddev->delta_disks <= 0) {
4031                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4032                                "(reduce disks) required - aborting.\n",
4033                                mdname(mddev));
4034                         return -EINVAL;
4035                 }
4036                 old_disks = mddev->raid_disks - mddev->delta_disks;
4037                 /* reshape_position must be on a new-stripe boundary, and one
4038                  * further up in new geometry must map after here in old
4039                  * geometry.
4040                  */
4041                 here_new = mddev->reshape_position;
4042                 if (sector_div(here_new, (mddev->chunk_size>>9)*
4043                                (mddev->raid_disks - max_degraded))) {
4044                         printk(KERN_ERR "raid5: reshape_position not "
4045                                "on a stripe boundary\n");
4046                         return -EINVAL;
4047                 }
4048                 /* here_new is the stripe we will write to */
4049                 here_old = mddev->reshape_position;
4050                 sector_div(here_old, (mddev->chunk_size>>9)*
4051                            (old_disks-max_degraded));
4052                 /* here_old is the first stripe that we might need to read
4053                  * from */
4054                 if (here_new >= here_old) {
4055                         /* Reading from the same stripe as writing to - bad */
4056                         printk(KERN_ERR "raid5: reshape_position too early for "
4057                                "auto-recovery - aborting.\n");
4058                         return -EINVAL;
4059                 }
4060                 printk(KERN_INFO "raid5: reshape will continue\n");
4061                 /* OK, we should be able to continue; */
4062         }
4063
4064
4065         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
4066         if ((conf = mddev->private) == NULL)
4067                 goto abort;
4068         if (mddev->reshape_position == MaxSector) {
4069                 conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
4070         } else {
4071                 conf->raid_disks = mddev->raid_disks;
4072                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4073         }
4074
4075         conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
4076                               GFP_KERNEL);
4077         if (!conf->disks)
4078                 goto abort;
4079
4080         conf->mddev = mddev;
4081
4082         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4083                 goto abort;
4084
4085         if (mddev->level == 6) {
4086                 conf->spare_page = alloc_page(GFP_KERNEL);
4087                 if (!conf->spare_page)
4088                         goto abort;
4089         }
4090         spin_lock_init(&conf->device_lock);
4091         mddev->queue->queue_lock = &conf->device_lock;
4092         init_waitqueue_head(&conf->wait_for_stripe);
4093         init_waitqueue_head(&conf->wait_for_overlap);
4094         INIT_LIST_HEAD(&conf->handle_list);
4095         INIT_LIST_HEAD(&conf->hold_list);
4096         INIT_LIST_HEAD(&conf->delayed_list);
4097         INIT_LIST_HEAD(&conf->bitmap_list);
4098         INIT_LIST_HEAD(&conf->inactive_list);
4099         atomic_set(&conf->active_stripes, 0);
4100         atomic_set(&conf->preread_active_stripes, 0);
4101         atomic_set(&conf->active_aligned_reads, 0);
4102         conf->bypass_threshold = BYPASS_THRESHOLD;
4103
4104         pr_debug("raid5: run(%s) called.\n", mdname(mddev));
4105
4106         rdev_for_each(rdev, tmp, mddev) {
4107                 raid_disk = rdev->raid_disk;
4108                 if (raid_disk >= conf->raid_disks
4109                     || raid_disk < 0)
4110                         continue;
4111                 disk = conf->disks + raid_disk;
4112
4113                 disk->rdev = rdev;
4114
4115                 if (test_bit(In_sync, &rdev->flags)) {
4116                         char b[BDEVNAME_SIZE];
4117                         printk(KERN_INFO "raid5: device %s operational as raid"
4118                                 " disk %d\n", bdevname(rdev->bdev,b),
4119                                 raid_disk);
4120                         working_disks++;
4121                 } else
4122                         /* Cannot rely on bitmap to complete recovery */
4123                         conf->fullsync = 1;
4124         }
4125
4126         /*
4127          * 0 for a fully functional array, 1 or 2 for a degraded array.
4128          */
4129         mddev->degraded = conf->raid_disks - working_disks;
4130         conf->mddev = mddev;
4131         conf->chunk_size = mddev->chunk_size;
4132         conf->level = mddev->level;
4133         if (conf->level == 6)
4134                 conf->max_degraded = 2;
4135         else
4136                 conf->max_degraded = 1;
4137         conf->algorithm = mddev->layout;
4138         conf->max_nr_stripes = NR_STRIPES;
4139         conf->expand_progress = mddev->reshape_position;
4140
4141         /* device size must be a multiple of chunk size */
4142         mddev->size &= ~(mddev->chunk_size/1024 -1);
4143         mddev->resync_max_sectors = mddev->size << 1;
4144
4145         if (conf->level == 6 && conf->raid_disks < 4) {
4146                 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
4147                        mdname(mddev), conf->raid_disks);
4148                 goto abort;
4149         }
4150         if (!conf->chunk_size || conf->chunk_size % 4) {
4151                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
4152                         conf->chunk_size, mdname(mddev));
4153                 goto abort;
4154         }
4155         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
4156                 printk(KERN_ERR 
4157                         "raid5: unsupported parity algorithm %d for %s\n",
4158                         conf->algorithm, mdname(mddev));
4159                 goto abort;
4160         }
4161         if (mddev->degraded > conf->max_degraded) {
4162                 printk(KERN_ERR "raid5: not enough operational devices for %s"
4163                         " (%d/%d failed)\n",
4164                         mdname(mddev), mddev->degraded, conf->raid_disks);
4165                 goto abort;
4166         }
4167
4168         if (mddev->degraded > 0 &&
4169             mddev->recovery_cp != MaxSector) {
4170                 if (mddev->ok_start_degraded)
4171                         printk(KERN_WARNING
4172                                "raid5: starting dirty degraded array: %s"
4173                                "- data corruption possible.\n",
4174                                mdname(mddev));
4175                 else {
4176                         printk(KERN_ERR
4177                                "raid5: cannot start dirty degraded array for %s\n",
4178                                mdname(mddev));
4179                         goto abort;
4180                 }
4181         }
4182
4183         {
4184                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
4185                 if (!mddev->thread) {
4186                         printk(KERN_ERR 
4187                                 "raid5: couldn't allocate thread for %s\n",
4188                                 mdname(mddev));
4189                         goto abort;
4190                 }
4191         }
4192         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4193                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4194         if (grow_stripes(conf, conf->max_nr_stripes)) {
4195                 printk(KERN_ERR 
4196                         "raid5: couldn't allocate %dkB for buffers\n", memory);
4197                 shrink_stripes(conf);
4198                 md_unregister_thread(mddev->thread);
4199                 goto abort;
4200         } else
4201                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
4202                         memory, mdname(mddev));
4203
4204         if (mddev->degraded == 0)
4205                 printk("raid5: raid level %d set %s active with %d out of %d"
4206                         " devices, algorithm %d\n", conf->level, mdname(mddev), 
4207                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
4208                         conf->algorithm);
4209         else
4210                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
4211                         " out of %d devices, algorithm %d\n", conf->level,
4212                         mdname(mddev), mddev->raid_disks - mddev->degraded,
4213                         mddev->raid_disks, conf->algorithm);
4214
4215         print_raid5_conf(conf);
4216
4217         if (conf->expand_progress != MaxSector) {
4218                 printk("...ok start reshape thread\n");
4219                 conf->expand_lo = conf->expand_progress;
4220                 atomic_set(&conf->reshape_stripes, 0);
4221                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4222                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4223                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4224                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4225                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4226                                                         "%s_reshape");
4227         }
4228
4229         /* read-ahead size must cover two whole stripes, which is
4230          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4231          */
4232         {
4233                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
4234                 int stripe = data_disks *
4235                         (mddev->chunk_size / PAGE_SIZE);
4236                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4237                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4238         }
4239
4240         /* Ok, everything is just fine now */
4241         if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
4242                 printk(KERN_WARNING
4243                        "raid5: failed to create sysfs attributes for %s\n",
4244                        mdname(mddev));
4245
4246         mddev->queue->unplug_fn = raid5_unplug_device;
4247         mddev->queue->backing_dev_info.congested_data = mddev;
4248         mddev->queue->backing_dev_info.congested_fn = raid5_congested;
4249
4250         mddev->array_sectors = 2 * mddev->size * (conf->previous_raid_disks -
4251                                             conf->max_degraded);
4252
4253         blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
4254
4255         return 0;
4256 abort:
4257         if (conf) {
4258                 print_raid5_conf(conf);
4259                 safe_put_page(conf->spare_page);
4260                 kfree(conf->disks);
4261                 kfree(conf->stripe_hashtbl);
4262                 kfree(conf);
4263         }
4264         mddev->private = NULL;
4265         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
4266         return -EIO;
4267 }
4268
4269
4270
4271 static int stop(mddev_t *mddev)
4272 {
4273         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4274
4275         md_unregister_thread(mddev->thread);
4276         mddev->thread = NULL;
4277         shrink_stripes(conf);
4278         kfree(conf->stripe_hashtbl);
4279         mddev->queue->backing_dev_info.congested_fn = NULL;
4280         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
4281         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
4282         kfree(conf->disks);
4283         kfree(conf);
4284         mddev->private = NULL;
4285         return 0;
4286 }
4287
4288 #ifdef DEBUG
4289 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
4290 {
4291         int i;
4292
4293         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
4294                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
4295         seq_printf(seq, "sh %llu,  count %d.\n",
4296                    (unsigned long long)sh->sector, atomic_read(&sh->count));
4297         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
4298         for (i = 0; i < sh->disks; i++) {
4299                 seq_printf(seq, "(cache%d: %p %ld) ",
4300                            i, sh->dev[i].page, sh->dev[i].flags);
4301         }
4302         seq_printf(seq, "\n");
4303 }
4304
4305 static void printall (struct seq_file *seq, raid5_conf_t *conf)
4306 {
4307         struct stripe_head *sh;
4308         struct hlist_node *hn;
4309         int i;
4310
4311         spin_lock_irq(&conf->device_lock);
4312         for (i = 0; i < NR_HASH; i++) {
4313                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
4314                         if (sh->raid_conf != conf)
4315                                 continue;
4316                         print_sh(seq, sh);
4317                 }
4318         }
4319         spin_unlock_irq(&conf->device_lock);
4320 }
4321 #endif
4322
4323 static void status (struct seq_file *seq, mddev_t *mddev)
4324 {
4325         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4326         int i;
4327
4328         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
4329         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
4330         for (i = 0; i < conf->raid_disks; i++)
4331                 seq_printf (seq, "%s",
4332                                conf->disks[i].rdev &&
4333                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
4334         seq_printf (seq, "]");
4335 #ifdef DEBUG
4336         seq_printf (seq, "\n");
4337         printall(seq, conf);
4338 #endif
4339 }
4340
4341 static void print_raid5_conf (raid5_conf_t *conf)
4342 {
4343         int i;
4344         struct disk_info *tmp;
4345
4346         printk("RAID5 conf printout:\n");
4347         if (!conf) {
4348                 printk("(conf==NULL)\n");
4349                 return;
4350         }
4351         printk(" --- rd:%d wd:%d\n", conf->raid_disks,
4352                  conf->raid_disks - conf->mddev->degraded);
4353
4354         for (i = 0; i < conf->raid_disks; i++) {
4355                 char b[BDEVNAME_SIZE];
4356                 tmp = conf->disks + i;
4357                 if (tmp->rdev)
4358                 printk(" disk %d, o:%d, dev:%s\n",
4359                         i, !test_bit(Faulty, &tmp->rdev->flags),
4360                         bdevname(tmp->rdev->bdev,b));
4361         }
4362 }
4363
4364 static int raid5_spare_active(mddev_t *mddev)
4365 {
4366         int i;
4367         raid5_conf_t *conf = mddev->private;
4368         struct disk_info *tmp;
4369
4370         for (i = 0; i < conf->raid_disks; i++) {
4371                 tmp = conf->disks + i;
4372                 if (tmp->rdev
4373                     && !test_bit(Faulty, &tmp->rdev->flags)
4374                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
4375                         unsigned long flags;
4376                         spin_lock_irqsave(&conf->device_lock, flags);
4377                         mddev->degraded--;
4378                         spin_unlock_irqrestore(&conf->device_lock, flags);
4379                 }
4380         }
4381         print_raid5_conf(conf);
4382         return 0;
4383 }
4384
4385 static int raid5_remove_disk(mddev_t *mddev, int number)
4386 {
4387         raid5_conf_t *conf = mddev->private;
4388         int err = 0;
4389         mdk_rdev_t *rdev;
4390         struct disk_info *p = conf->disks + number;
4391
4392         print_raid5_conf(conf);
4393         rdev = p->rdev;
4394         if (rdev) {
4395                 if (test_bit(In_sync, &rdev->flags) ||
4396                     atomic_read(&rdev->nr_pending)) {
4397                         err = -EBUSY;
4398                         goto abort;
4399                 }
4400                 /* Only remove non-faulty devices if recovery
4401                  * isn't possible.
4402                  */
4403                 if (!test_bit(Faulty, &rdev->flags) &&
4404                     mddev->degraded <= conf->max_degraded) {
4405                         err = -EBUSY;
4406                         goto abort;
4407                 }
4408                 p->rdev = NULL;
4409                 synchronize_rcu();
4410                 if (atomic_read(&rdev->nr_pending)) {
4411                         /* lost the race, try later */
4412                         err = -EBUSY;
4413                         p->rdev = rdev;
4414                 }
4415         }
4416 abort:
4417
4418         print_raid5_conf(conf);
4419         return err;
4420 }
4421
4422 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
4423 {
4424         raid5_conf_t *conf = mddev->private;
4425         int err = -EEXIST;
4426         int disk;
4427         struct disk_info *p;
4428         int first = 0;
4429         int last = conf->raid_disks - 1;
4430
4431         if (mddev->degraded > conf->max_degraded)
4432                 /* no point adding a device */
4433                 return -EINVAL;
4434
4435         if (rdev->raid_disk >= 0)
4436                 first = last = rdev->raid_disk;
4437
4438         /*
4439          * find the disk ... but prefer rdev->saved_raid_disk
4440          * if possible.
4441          */
4442         if (rdev->saved_raid_disk >= 0 &&
4443             rdev->saved_raid_disk >= first &&
4444             conf->disks[rdev->saved_raid_disk].rdev == NULL)
4445                 disk = rdev->saved_raid_disk;
4446         else
4447                 disk = first;
4448         for ( ; disk <= last ; disk++)
4449                 if ((p=conf->disks + disk)->rdev == NULL) {
4450                         clear_bit(In_sync, &rdev->flags);
4451                         rdev->raid_disk = disk;
4452                         err = 0;
4453                         if (rdev->saved_raid_disk != disk)
4454                                 conf->fullsync = 1;
4455                         rcu_assign_pointer(p->rdev, rdev);
4456                         break;
4457                 }
4458         print_raid5_conf(conf);
4459         return err;
4460 }
4461
4462 static int raid5_resize(mddev_t *mddev, sector_t sectors)
4463 {
4464         /* no resync is happening, and there is enough space
4465          * on all devices, so we can resize.
4466          * We need to make sure resync covers any new space.
4467          * If the array is shrinking we should possibly wait until
4468          * any io in the removed space completes, but it hardly seems
4469          * worth it.
4470          */
4471         raid5_conf_t *conf = mddev_to_conf(mddev);
4472
4473         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
4474         mddev->array_sectors = sectors * (mddev->raid_disks
4475                                           - conf->max_degraded);
4476         set_capacity(mddev->gendisk, mddev->array_sectors);
4477         mddev->changed = 1;
4478         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
4479                 mddev->recovery_cp = mddev->size << 1;
4480                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4481         }
4482         mddev->size = sectors /2;
4483         mddev->resync_max_sectors = sectors;
4484         return 0;
4485 }
4486
4487 #ifdef CONFIG_MD_RAID5_RESHAPE
4488 static int raid5_check_reshape(mddev_t *mddev)
4489 {
4490         raid5_conf_t *conf = mddev_to_conf(mddev);
4491         int err;
4492
4493         if (mddev->delta_disks < 0 ||
4494             mddev->new_level != mddev->level)
4495                 return -EINVAL; /* Cannot shrink array or change level yet */
4496         if (mddev->delta_disks == 0)
4497                 return 0; /* nothing to do */
4498         if (mddev->bitmap)
4499                 /* Cannot grow a bitmap yet */
4500                 return -EBUSY;
4501
4502         /* Can only proceed if there are plenty of stripe_heads.
4503          * We need a minimum of one full stripe,, and for sensible progress
4504          * it is best to have about 4 times that.
4505          * If we require 4 times, then the default 256 4K stripe_heads will
4506          * allow for chunk sizes up to 256K, which is probably OK.
4507          * If the chunk size is greater, user-space should request more
4508          * stripe_heads first.
4509          */
4510         if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
4511             (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
4512                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
4513                        (mddev->chunk_size / STRIPE_SIZE)*4);
4514                 return -ENOSPC;
4515         }
4516
4517         err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
4518         if (err)
4519                 return err;
4520
4521         if (mddev->degraded > conf->max_degraded)
4522                 return -EINVAL;
4523         /* looks like we might be able to manage this */
4524         return 0;
4525 }
4526
4527 static int raid5_start_reshape(mddev_t *mddev)
4528 {
4529         raid5_conf_t *conf = mddev_to_conf(mddev);
4530         mdk_rdev_t *rdev;
4531         struct list_head *rtmp;
4532         int spares = 0;
4533         int added_devices = 0;
4534         unsigned long flags;
4535
4536         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4537                 return -EBUSY;
4538
4539         rdev_for_each(rdev, rtmp, mddev)
4540                 if (rdev->raid_disk < 0 &&
4541                     !test_bit(Faulty, &rdev->flags))
4542                         spares++;
4543
4544         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
4545                 /* Not enough devices even to make a degraded array
4546                  * of that size
4547                  */
4548                 return -EINVAL;
4549
4550         atomic_set(&conf->reshape_stripes, 0);
4551         spin_lock_irq(&conf->device_lock);
4552         conf->previous_raid_disks = conf->raid_disks;
4553         conf->raid_disks += mddev->delta_disks;
4554         conf->expand_progress = 0;
4555         conf->expand_lo = 0;
4556         spin_unlock_irq(&conf->device_lock);
4557
4558         /* Add some new drives, as many as will fit.
4559          * We know there are enough to make the newly sized array work.
4560          */
4561         rdev_for_each(rdev, rtmp, mddev)
4562                 if (rdev->raid_disk < 0 &&
4563                     !test_bit(Faulty, &rdev->flags)) {
4564                         if (raid5_add_disk(mddev, rdev) == 0) {
4565                                 char nm[20];
4566                                 set_bit(In_sync, &rdev->flags);
4567                                 added_devices++;
4568                                 rdev->recovery_offset = 0;
4569                                 sprintf(nm, "rd%d", rdev->raid_disk);
4570                                 if (sysfs_create_link(&mddev->kobj,
4571                                                       &rdev->kobj, nm))
4572                                         printk(KERN_WARNING
4573                                                "raid5: failed to create "
4574                                                " link %s for %s\n",
4575                                                nm, mdname(mddev));
4576                         } else
4577                                 break;
4578                 }
4579
4580         spin_lock_irqsave(&conf->device_lock, flags);
4581         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
4582         spin_unlock_irqrestore(&conf->device_lock, flags);
4583         mddev->raid_disks = conf->raid_disks;
4584         mddev->reshape_position = 0;
4585         set_bit(MD_CHANGE_DEVS, &mddev->flags);
4586
4587         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4588         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4589         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4590         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4591         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4592                                                 "%s_reshape");
4593         if (!mddev->sync_thread) {
4594                 mddev->recovery = 0;
4595                 spin_lock_irq(&conf->device_lock);
4596                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
4597                 conf->expand_progress = MaxSector;
4598                 spin_unlock_irq(&conf->device_lock);
4599                 return -EAGAIN;
4600         }
4601         md_wakeup_thread(mddev->sync_thread);
4602         md_new_event(mddev);
4603         return 0;
4604 }
4605 #endif
4606
4607 static void end_reshape(raid5_conf_t *conf)
4608 {
4609         struct block_device *bdev;
4610
4611         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
4612                 conf->mddev->array_sectors = 2 * conf->mddev->size *
4613                         (conf->raid_disks - conf->max_degraded);
4614                 set_capacity(conf->mddev->gendisk, conf->mddev->array_sectors);
4615                 conf->mddev->changed = 1;
4616
4617                 bdev = bdget_disk(conf->mddev->gendisk, 0);
4618                 if (bdev) {
4619                         mutex_lock(&bdev->bd_inode->i_mutex);
4620                         i_size_write(bdev->bd_inode,
4621                                      (loff_t)conf->mddev->array_sectors << 9);
4622                         mutex_unlock(&bdev->bd_inode->i_mutex);
4623                         bdput(bdev);
4624                 }
4625                 spin_lock_irq(&conf->device_lock);
4626                 conf->expand_progress = MaxSector;
4627                 spin_unlock_irq(&conf->device_lock);
4628                 conf->mddev->reshape_position = MaxSector;
4629
4630                 /* read-ahead size must cover two whole stripes, which is
4631                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4632                  */
4633                 {
4634                         int data_disks = conf->previous_raid_disks - conf->max_degraded;
4635                         int stripe = data_disks *
4636                                 (conf->mddev->chunk_size / PAGE_SIZE);
4637                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4638                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4639                 }
4640         }
4641 }
4642
4643 static void raid5_quiesce(mddev_t *mddev, int state)
4644 {
4645         raid5_conf_t *conf = mddev_to_conf(mddev);
4646
4647         switch(state) {
4648         case 2: /* resume for a suspend */
4649                 wake_up(&conf->wait_for_overlap);
4650                 break;
4651
4652         case 1: /* stop all writes */
4653                 spin_lock_irq(&conf->device_lock);
4654                 conf->quiesce = 1;
4655                 wait_event_lock_irq(conf->wait_for_stripe,
4656                                     atomic_read(&conf->active_stripes) == 0 &&
4657                                     atomic_read(&conf->active_aligned_reads) == 0,
4658                                     conf->device_lock, /* nothing */);
4659                 spin_unlock_irq(&conf->device_lock);
4660                 break;
4661
4662         case 0: /* re-enable writes */
4663                 spin_lock_irq(&conf->device_lock);
4664                 conf->quiesce = 0;
4665                 wake_up(&conf->wait_for_stripe);
4666                 wake_up(&conf->wait_for_overlap);
4667                 spin_unlock_irq(&conf->device_lock);
4668                 break;
4669         }
4670 }
4671
4672 static struct mdk_personality raid6_personality =
4673 {
4674         .name           = "raid6",
4675         .level          = 6,
4676         .owner          = THIS_MODULE,
4677         .make_request   = make_request,
4678         .run            = run,
4679         .stop           = stop,
4680         .status         = status,
4681         .error_handler  = error,
4682         .hot_add_disk   = raid5_add_disk,
4683         .hot_remove_disk= raid5_remove_disk,
4684         .spare_active   = raid5_spare_active,
4685         .sync_request   = sync_request,
4686         .resize         = raid5_resize,
4687 #ifdef CONFIG_MD_RAID5_RESHAPE
4688         .check_reshape  = raid5_check_reshape,
4689         .start_reshape  = raid5_start_reshape,
4690 #endif
4691         .quiesce        = raid5_quiesce,
4692 };
4693 static struct mdk_personality raid5_personality =
4694 {
4695         .name           = "raid5",
4696         .level          = 5,
4697         .owner          = THIS_MODULE,
4698         .make_request   = make_request,
4699         .run            = run,
4700         .stop           = stop,
4701         .status         = status,
4702         .error_handler  = error,
4703         .hot_add_disk   = raid5_add_disk,
4704         .hot_remove_disk= raid5_remove_disk,
4705         .spare_active   = raid5_spare_active,
4706         .sync_request   = sync_request,
4707         .resize         = raid5_resize,
4708 #ifdef CONFIG_MD_RAID5_RESHAPE
4709         .check_reshape  = raid5_check_reshape,
4710         .start_reshape  = raid5_start_reshape,
4711 #endif
4712         .quiesce        = raid5_quiesce,
4713 };
4714
4715 static struct mdk_personality raid4_personality =
4716 {
4717         .name           = "raid4",
4718         .level          = 4,
4719         .owner          = THIS_MODULE,
4720         .make_request   = make_request,
4721         .run            = run,
4722         .stop           = stop,
4723         .status         = status,
4724         .error_handler  = error,
4725         .hot_add_disk   = raid5_add_disk,
4726         .hot_remove_disk= raid5_remove_disk,
4727         .spare_active   = raid5_spare_active,
4728         .sync_request   = sync_request,
4729         .resize         = raid5_resize,
4730 #ifdef CONFIG_MD_RAID5_RESHAPE
4731         .check_reshape  = raid5_check_reshape,
4732         .start_reshape  = raid5_start_reshape,
4733 #endif
4734         .quiesce        = raid5_quiesce,
4735 };
4736
4737 static int __init raid5_init(void)
4738 {
4739         int e;
4740
4741         e = raid6_select_algo();
4742         if ( e )
4743                 return e;
4744         register_md_personality(&raid6_personality);
4745         register_md_personality(&raid5_personality);
4746         register_md_personality(&raid4_personality);
4747         return 0;
4748 }
4749
4750 static void raid5_exit(void)
4751 {
4752         unregister_md_personality(&raid6_personality);
4753         unregister_md_personality(&raid5_personality);
4754         unregister_md_personality(&raid4_personality);
4755 }
4756
4757 module_init(raid5_init);
4758 module_exit(raid5_exit);
4759 MODULE_LICENSE("GPL");
4760 MODULE_ALIAS("md-personality-4"); /* RAID5 */
4761 MODULE_ALIAS("md-raid5");
4762 MODULE_ALIAS("md-raid4");
4763 MODULE_ALIAS("md-level-5");
4764 MODULE_ALIAS("md-level-4");
4765 MODULE_ALIAS("md-personality-8"); /* RAID6 */
4766 MODULE_ALIAS("md-raid6");
4767 MODULE_ALIAS("md-level-6");
4768
4769 /* This used to be two separate modules, they were: */
4770 MODULE_ALIAS("raid5");
4771 MODULE_ALIAS("raid6");