[PATCH] md: add support for reshape of a raid6
[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
56 /*
57  * Stripe cache
58  */
59
60 #define NR_STRIPES              256
61 #define STRIPE_SIZE             PAGE_SIZE
62 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
63 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
64 #define IO_THRESHOLD            1
65 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
66 #define HASH_MASK               (NR_HASH - 1)
67
68 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
69
70 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
71  * order without overlap.  There may be several bio's per stripe+device, and
72  * a bio could span several devices.
73  * When walking this list for a particular stripe+device, we must never proceed
74  * beyond a bio that extends past this device, as the next bio might no longer
75  * be valid.
76  * This macro is used to determine the 'next' bio in the list, given the sector
77  * of the current stripe+device
78  */
79 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
80 /*
81  * The following can be used to debug the driver
82  */
83 #define RAID5_DEBUG     0
84 #define RAID5_PARANOIA  1
85 #if RAID5_PARANOIA && defined(CONFIG_SMP)
86 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
87 #else
88 # define CHECK_DEVLOCK()
89 #endif
90
91 #define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
92 #if RAID5_DEBUG
93 #define inline
94 #define __inline__
95 #endif
96
97 #if !RAID6_USE_EMPTY_ZERO_PAGE
98 /* In .bss so it's zeroed */
99 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
100 #endif
101
102 static inline int raid6_next_disk(int disk, int raid_disks)
103 {
104         disk++;
105         return (disk < raid_disks) ? disk : 0;
106 }
107 static void print_raid5_conf (raid5_conf_t *conf);
108
109 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
110 {
111         if (atomic_dec_and_test(&sh->count)) {
112                 BUG_ON(!list_empty(&sh->lru));
113                 BUG_ON(atomic_read(&conf->active_stripes)==0);
114                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
115                         if (test_bit(STRIPE_DELAYED, &sh->state)) {
116                                 list_add_tail(&sh->lru, &conf->delayed_list);
117                                 blk_plug_device(conf->mddev->queue);
118                         } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
119                                    sh->bm_seq - conf->seq_write > 0) {
120                                 list_add_tail(&sh->lru, &conf->bitmap_list);
121                                 blk_plug_device(conf->mddev->queue);
122                         } else {
123                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
124                                 list_add_tail(&sh->lru, &conf->handle_list);
125                         }
126                         md_wakeup_thread(conf->mddev->thread);
127                 } else {
128                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
129                                 atomic_dec(&conf->preread_active_stripes);
130                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
131                                         md_wakeup_thread(conf->mddev->thread);
132                         }
133                         atomic_dec(&conf->active_stripes);
134                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
135                                 list_add_tail(&sh->lru, &conf->inactive_list);
136                                 wake_up(&conf->wait_for_stripe);
137                                 if (conf->retry_read_aligned)
138                                         md_wakeup_thread(conf->mddev->thread);
139                         }
140                 }
141         }
142 }
143 static void release_stripe(struct stripe_head *sh)
144 {
145         raid5_conf_t *conf = sh->raid_conf;
146         unsigned long flags;
147
148         spin_lock_irqsave(&conf->device_lock, flags);
149         __release_stripe(conf, sh);
150         spin_unlock_irqrestore(&conf->device_lock, flags);
151 }
152
153 static inline void remove_hash(struct stripe_head *sh)
154 {
155         PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
156
157         hlist_del_init(&sh->hash);
158 }
159
160 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
161 {
162         struct hlist_head *hp = stripe_hash(conf, sh->sector);
163
164         PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
165
166         CHECK_DEVLOCK();
167         hlist_add_head(&sh->hash, hp);
168 }
169
170
171 /* find an idle stripe, make sure it is unhashed, and return it. */
172 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
173 {
174         struct stripe_head *sh = NULL;
175         struct list_head *first;
176
177         CHECK_DEVLOCK();
178         if (list_empty(&conf->inactive_list))
179                 goto out;
180         first = conf->inactive_list.next;
181         sh = list_entry(first, struct stripe_head, lru);
182         list_del_init(first);
183         remove_hash(sh);
184         atomic_inc(&conf->active_stripes);
185 out:
186         return sh;
187 }
188
189 static void shrink_buffers(struct stripe_head *sh, int num)
190 {
191         struct page *p;
192         int i;
193
194         for (i=0; i<num ; i++) {
195                 p = sh->dev[i].page;
196                 if (!p)
197                         continue;
198                 sh->dev[i].page = NULL;
199                 put_page(p);
200         }
201 }
202
203 static int grow_buffers(struct stripe_head *sh, int num)
204 {
205         int i;
206
207         for (i=0; i<num; i++) {
208                 struct page *page;
209
210                 if (!(page = alloc_page(GFP_KERNEL))) {
211                         return 1;
212                 }
213                 sh->dev[i].page = page;
214         }
215         return 0;
216 }
217
218 static void raid5_build_block (struct stripe_head *sh, int i);
219
220 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
221 {
222         raid5_conf_t *conf = sh->raid_conf;
223         int i;
224
225         BUG_ON(atomic_read(&sh->count) != 0);
226         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
227         
228         CHECK_DEVLOCK();
229         PRINTK("init_stripe called, stripe %llu\n", 
230                 (unsigned long long)sh->sector);
231
232         remove_hash(sh);
233
234         sh->sector = sector;
235         sh->pd_idx = pd_idx;
236         sh->state = 0;
237
238         sh->disks = disks;
239
240         for (i = sh->disks; i--; ) {
241                 struct r5dev *dev = &sh->dev[i];
242
243                 if (dev->toread || dev->towrite || dev->written ||
244                     test_bit(R5_LOCKED, &dev->flags)) {
245                         printk("sector=%llx i=%d %p %p %p %d\n",
246                                (unsigned long long)sh->sector, i, dev->toread,
247                                dev->towrite, dev->written,
248                                test_bit(R5_LOCKED, &dev->flags));
249                         BUG();
250                 }
251                 dev->flags = 0;
252                 raid5_build_block(sh, i);
253         }
254         insert_hash(conf, sh);
255 }
256
257 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
258 {
259         struct stripe_head *sh;
260         struct hlist_node *hn;
261
262         CHECK_DEVLOCK();
263         PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
264         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
265                 if (sh->sector == sector && sh->disks == disks)
266                         return sh;
267         PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
268         return NULL;
269 }
270
271 static void unplug_slaves(mddev_t *mddev);
272 static void raid5_unplug_device(request_queue_t *q);
273
274 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
275                                              int pd_idx, int noblock)
276 {
277         struct stripe_head *sh;
278
279         PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
280
281         spin_lock_irq(&conf->device_lock);
282
283         do {
284                 wait_event_lock_irq(conf->wait_for_stripe,
285                                     conf->quiesce == 0,
286                                     conf->device_lock, /* nothing */);
287                 sh = __find_stripe(conf, sector, disks);
288                 if (!sh) {
289                         if (!conf->inactive_blocked)
290                                 sh = get_free_stripe(conf);
291                         if (noblock && sh == NULL)
292                                 break;
293                         if (!sh) {
294                                 conf->inactive_blocked = 1;
295                                 wait_event_lock_irq(conf->wait_for_stripe,
296                                                     !list_empty(&conf->inactive_list) &&
297                                                     (atomic_read(&conf->active_stripes)
298                                                      < (conf->max_nr_stripes *3/4)
299                                                      || !conf->inactive_blocked),
300                                                     conf->device_lock,
301                                                     raid5_unplug_device(conf->mddev->queue)
302                                         );
303                                 conf->inactive_blocked = 0;
304                         } else
305                                 init_stripe(sh, sector, pd_idx, disks);
306                 } else {
307                         if (atomic_read(&sh->count)) {
308                           BUG_ON(!list_empty(&sh->lru));
309                         } else {
310                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
311                                         atomic_inc(&conf->active_stripes);
312                                 if (list_empty(&sh->lru) &&
313                                     !test_bit(STRIPE_EXPANDING, &sh->state))
314                                         BUG();
315                                 list_del_init(&sh->lru);
316                         }
317                 }
318         } while (sh == NULL);
319
320         if (sh)
321                 atomic_inc(&sh->count);
322
323         spin_unlock_irq(&conf->device_lock);
324         return sh;
325 }
326
327 static int grow_one_stripe(raid5_conf_t *conf)
328 {
329         struct stripe_head *sh;
330         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
331         if (!sh)
332                 return 0;
333         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
334         sh->raid_conf = conf;
335         spin_lock_init(&sh->lock);
336
337         if (grow_buffers(sh, conf->raid_disks)) {
338                 shrink_buffers(sh, conf->raid_disks);
339                 kmem_cache_free(conf->slab_cache, sh);
340                 return 0;
341         }
342         sh->disks = conf->raid_disks;
343         /* we just created an active stripe so... */
344         atomic_set(&sh->count, 1);
345         atomic_inc(&conf->active_stripes);
346         INIT_LIST_HEAD(&sh->lru);
347         release_stripe(sh);
348         return 1;
349 }
350
351 static int grow_stripes(raid5_conf_t *conf, int num)
352 {
353         struct kmem_cache *sc;
354         int devs = conf->raid_disks;
355
356         sprintf(conf->cache_name[0], "raid5/%s", mdname(conf->mddev));
357         sprintf(conf->cache_name[1], "raid5/%s-alt", mdname(conf->mddev));
358         conf->active_name = 0;
359         sc = kmem_cache_create(conf->cache_name[conf->active_name],
360                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
361                                0, 0, NULL, NULL);
362         if (!sc)
363                 return 1;
364         conf->slab_cache = sc;
365         conf->pool_size = devs;
366         while (num--)
367                 if (!grow_one_stripe(conf))
368                         return 1;
369         return 0;
370 }
371
372 #ifdef CONFIG_MD_RAID5_RESHAPE
373 static int resize_stripes(raid5_conf_t *conf, int newsize)
374 {
375         /* Make all the stripes able to hold 'newsize' devices.
376          * New slots in each stripe get 'page' set to a new page.
377          *
378          * This happens in stages:
379          * 1/ create a new kmem_cache and allocate the required number of
380          *    stripe_heads.
381          * 2/ gather all the old stripe_heads and tranfer the pages across
382          *    to the new stripe_heads.  This will have the side effect of
383          *    freezing the array as once all stripe_heads have been collected,
384          *    no IO will be possible.  Old stripe heads are freed once their
385          *    pages have been transferred over, and the old kmem_cache is
386          *    freed when all stripes are done.
387          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
388          *    we simple return a failre status - no need to clean anything up.
389          * 4/ allocate new pages for the new slots in the new stripe_heads.
390          *    If this fails, we don't bother trying the shrink the
391          *    stripe_heads down again, we just leave them as they are.
392          *    As each stripe_head is processed the new one is released into
393          *    active service.
394          *
395          * Once step2 is started, we cannot afford to wait for a write,
396          * so we use GFP_NOIO allocations.
397          */
398         struct stripe_head *osh, *nsh;
399         LIST_HEAD(newstripes);
400         struct disk_info *ndisks;
401         int err = 0;
402         struct kmem_cache *sc;
403         int i;
404
405         if (newsize <= conf->pool_size)
406                 return 0; /* never bother to shrink */
407
408         md_allow_write(conf->mddev);
409
410         /* Step 1 */
411         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
412                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
413                                0, 0, NULL, NULL);
414         if (!sc)
415                 return -ENOMEM;
416
417         for (i = conf->max_nr_stripes; i; i--) {
418                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
419                 if (!nsh)
420                         break;
421
422                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
423
424                 nsh->raid_conf = conf;
425                 spin_lock_init(&nsh->lock);
426
427                 list_add(&nsh->lru, &newstripes);
428         }
429         if (i) {
430                 /* didn't get enough, give up */
431                 while (!list_empty(&newstripes)) {
432                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
433                         list_del(&nsh->lru);
434                         kmem_cache_free(sc, nsh);
435                 }
436                 kmem_cache_destroy(sc);
437                 return -ENOMEM;
438         }
439         /* Step 2 - Must use GFP_NOIO now.
440          * OK, we have enough stripes, start collecting inactive
441          * stripes and copying them over
442          */
443         list_for_each_entry(nsh, &newstripes, lru) {
444                 spin_lock_irq(&conf->device_lock);
445                 wait_event_lock_irq(conf->wait_for_stripe,
446                                     !list_empty(&conf->inactive_list),
447                                     conf->device_lock,
448                                     unplug_slaves(conf->mddev)
449                         );
450                 osh = get_free_stripe(conf);
451                 spin_unlock_irq(&conf->device_lock);
452                 atomic_set(&nsh->count, 1);
453                 for(i=0; i<conf->pool_size; i++)
454                         nsh->dev[i].page = osh->dev[i].page;
455                 for( ; i<newsize; i++)
456                         nsh->dev[i].page = NULL;
457                 kmem_cache_free(conf->slab_cache, osh);
458         }
459         kmem_cache_destroy(conf->slab_cache);
460
461         /* Step 3.
462          * At this point, we are holding all the stripes so the array
463          * is completely stalled, so now is a good time to resize
464          * conf->disks.
465          */
466         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
467         if (ndisks) {
468                 for (i=0; i<conf->raid_disks; i++)
469                         ndisks[i] = conf->disks[i];
470                 kfree(conf->disks);
471                 conf->disks = ndisks;
472         } else
473                 err = -ENOMEM;
474
475         /* Step 4, return new stripes to service */
476         while(!list_empty(&newstripes)) {
477                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
478                 list_del_init(&nsh->lru);
479                 for (i=conf->raid_disks; i < newsize; i++)
480                         if (nsh->dev[i].page == NULL) {
481                                 struct page *p = alloc_page(GFP_NOIO);
482                                 nsh->dev[i].page = p;
483                                 if (!p)
484                                         err = -ENOMEM;
485                         }
486                 release_stripe(nsh);
487         }
488         /* critical section pass, GFP_NOIO no longer needed */
489
490         conf->slab_cache = sc;
491         conf->active_name = 1-conf->active_name;
492         conf->pool_size = newsize;
493         return err;
494 }
495 #endif
496
497 static int drop_one_stripe(raid5_conf_t *conf)
498 {
499         struct stripe_head *sh;
500
501         spin_lock_irq(&conf->device_lock);
502         sh = get_free_stripe(conf);
503         spin_unlock_irq(&conf->device_lock);
504         if (!sh)
505                 return 0;
506         BUG_ON(atomic_read(&sh->count));
507         shrink_buffers(sh, conf->pool_size);
508         kmem_cache_free(conf->slab_cache, sh);
509         atomic_dec(&conf->active_stripes);
510         return 1;
511 }
512
513 static void shrink_stripes(raid5_conf_t *conf)
514 {
515         while (drop_one_stripe(conf))
516                 ;
517
518         if (conf->slab_cache)
519                 kmem_cache_destroy(conf->slab_cache);
520         conf->slab_cache = NULL;
521 }
522
523 static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
524                                    int error)
525 {
526         struct stripe_head *sh = bi->bi_private;
527         raid5_conf_t *conf = sh->raid_conf;
528         int disks = sh->disks, i;
529         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
530         char b[BDEVNAME_SIZE];
531         mdk_rdev_t *rdev;
532
533         if (bi->bi_size)
534                 return 1;
535
536         for (i=0 ; i<disks; i++)
537                 if (bi == &sh->dev[i].req)
538                         break;
539
540         PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n", 
541                 (unsigned long long)sh->sector, i, atomic_read(&sh->count), 
542                 uptodate);
543         if (i == disks) {
544                 BUG();
545                 return 0;
546         }
547
548         if (uptodate) {
549                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
550                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
551                         rdev = conf->disks[i].rdev;
552                         printk(KERN_INFO "raid5:%s: read error corrected (%lu sectors at %llu on %s)\n",
553                                mdname(conf->mddev), STRIPE_SECTORS,
554                                (unsigned long long)sh->sector + rdev->data_offset,
555                                bdevname(rdev->bdev, b));
556                         clear_bit(R5_ReadError, &sh->dev[i].flags);
557                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
558                 }
559                 if (atomic_read(&conf->disks[i].rdev->read_errors))
560                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
561         } else {
562                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
563                 int retry = 0;
564                 rdev = conf->disks[i].rdev;
565
566                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
567                 atomic_inc(&rdev->read_errors);
568                 if (conf->mddev->degraded)
569                         printk(KERN_WARNING "raid5:%s: read error not correctable (sector %llu on %s).\n",
570                                mdname(conf->mddev),
571                                (unsigned long long)sh->sector + rdev->data_offset,
572                                bdn);
573                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
574                         /* Oh, no!!! */
575                         printk(KERN_WARNING "raid5:%s: read error NOT corrected!! (sector %llu on %s).\n",
576                                mdname(conf->mddev),
577                                (unsigned long long)sh->sector + rdev->data_offset,
578                                bdn);
579                 else if (atomic_read(&rdev->read_errors)
580                          > conf->max_nr_stripes)
581                         printk(KERN_WARNING
582                                "raid5:%s: Too many read errors, failing device %s.\n",
583                                mdname(conf->mddev), bdn);
584                 else
585                         retry = 1;
586                 if (retry)
587                         set_bit(R5_ReadError, &sh->dev[i].flags);
588                 else {
589                         clear_bit(R5_ReadError, &sh->dev[i].flags);
590                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
591                         md_error(conf->mddev, rdev);
592                 }
593         }
594         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
595         clear_bit(R5_LOCKED, &sh->dev[i].flags);
596         set_bit(STRIPE_HANDLE, &sh->state);
597         release_stripe(sh);
598         return 0;
599 }
600
601 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
602                                     int error)
603 {
604         struct stripe_head *sh = bi->bi_private;
605         raid5_conf_t *conf = sh->raid_conf;
606         int disks = sh->disks, i;
607         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
608
609         if (bi->bi_size)
610                 return 1;
611
612         for (i=0 ; i<disks; i++)
613                 if (bi == &sh->dev[i].req)
614                         break;
615
616         PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n", 
617                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
618                 uptodate);
619         if (i == disks) {
620                 BUG();
621                 return 0;
622         }
623
624         if (!uptodate)
625                 md_error(conf->mddev, conf->disks[i].rdev);
626
627         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
628         
629         clear_bit(R5_LOCKED, &sh->dev[i].flags);
630         set_bit(STRIPE_HANDLE, &sh->state);
631         release_stripe(sh);
632         return 0;
633 }
634
635
636 static sector_t compute_blocknr(struct stripe_head *sh, int i);
637         
638 static void raid5_build_block (struct stripe_head *sh, int i)
639 {
640         struct r5dev *dev = &sh->dev[i];
641
642         bio_init(&dev->req);
643         dev->req.bi_io_vec = &dev->vec;
644         dev->req.bi_vcnt++;
645         dev->req.bi_max_vecs++;
646         dev->vec.bv_page = dev->page;
647         dev->vec.bv_len = STRIPE_SIZE;
648         dev->vec.bv_offset = 0;
649
650         dev->req.bi_sector = sh->sector;
651         dev->req.bi_private = sh;
652
653         dev->flags = 0;
654         dev->sector = compute_blocknr(sh, i);
655 }
656
657 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
658 {
659         char b[BDEVNAME_SIZE];
660         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
661         PRINTK("raid5: error called\n");
662
663         if (!test_bit(Faulty, &rdev->flags)) {
664                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
665                 if (test_and_clear_bit(In_sync, &rdev->flags)) {
666                         unsigned long flags;
667                         spin_lock_irqsave(&conf->device_lock, flags);
668                         mddev->degraded++;
669                         spin_unlock_irqrestore(&conf->device_lock, flags);
670                         /*
671                          * if recovery was running, make sure it aborts.
672                          */
673                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
674                 }
675                 set_bit(Faulty, &rdev->flags);
676                 printk (KERN_ALERT
677                         "raid5: Disk failure on %s, disabling device."
678                         " Operation continuing on %d devices\n",
679                         bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
680         }
681 }
682
683 /*
684  * Input: a 'big' sector number,
685  * Output: index of the data and parity disk, and the sector # in them.
686  */
687 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
688                         unsigned int data_disks, unsigned int * dd_idx,
689                         unsigned int * pd_idx, raid5_conf_t *conf)
690 {
691         long stripe;
692         unsigned long chunk_number;
693         unsigned int chunk_offset;
694         sector_t new_sector;
695         int sectors_per_chunk = conf->chunk_size >> 9;
696
697         /* First compute the information on this sector */
698
699         /*
700          * Compute the chunk number and the sector offset inside the chunk
701          */
702         chunk_offset = sector_div(r_sector, sectors_per_chunk);
703         chunk_number = r_sector;
704         BUG_ON(r_sector != chunk_number);
705
706         /*
707          * Compute the stripe number
708          */
709         stripe = chunk_number / data_disks;
710
711         /*
712          * Compute the data disk and parity disk indexes inside the stripe
713          */
714         *dd_idx = chunk_number % data_disks;
715
716         /*
717          * Select the parity disk based on the user selected algorithm.
718          */
719         switch(conf->level) {
720         case 4:
721                 *pd_idx = data_disks;
722                 break;
723         case 5:
724                 switch (conf->algorithm) {
725                 case ALGORITHM_LEFT_ASYMMETRIC:
726                         *pd_idx = data_disks - stripe % raid_disks;
727                         if (*dd_idx >= *pd_idx)
728                                 (*dd_idx)++;
729                         break;
730                 case ALGORITHM_RIGHT_ASYMMETRIC:
731                         *pd_idx = stripe % raid_disks;
732                         if (*dd_idx >= *pd_idx)
733                                 (*dd_idx)++;
734                         break;
735                 case ALGORITHM_LEFT_SYMMETRIC:
736                         *pd_idx = data_disks - stripe % raid_disks;
737                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
738                         break;
739                 case ALGORITHM_RIGHT_SYMMETRIC:
740                         *pd_idx = stripe % raid_disks;
741                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
742                         break;
743                 default:
744                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
745                                 conf->algorithm);
746                 }
747                 break;
748         case 6:
749
750                 /**** FIX THIS ****/
751                 switch (conf->algorithm) {
752                 case ALGORITHM_LEFT_ASYMMETRIC:
753                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
754                         if (*pd_idx == raid_disks-1)
755                                 (*dd_idx)++;    /* Q D D D P */
756                         else if (*dd_idx >= *pd_idx)
757                                 (*dd_idx) += 2; /* D D P Q D */
758                         break;
759                 case ALGORITHM_RIGHT_ASYMMETRIC:
760                         *pd_idx = stripe % raid_disks;
761                         if (*pd_idx == raid_disks-1)
762                                 (*dd_idx)++;    /* Q D D D P */
763                         else if (*dd_idx >= *pd_idx)
764                                 (*dd_idx) += 2; /* D D P Q D */
765                         break;
766                 case ALGORITHM_LEFT_SYMMETRIC:
767                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
768                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
769                         break;
770                 case ALGORITHM_RIGHT_SYMMETRIC:
771                         *pd_idx = stripe % raid_disks;
772                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
773                         break;
774                 default:
775                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
776                                 conf->algorithm);
777                 }
778                 break;
779         }
780
781         /*
782          * Finally, compute the new sector number
783          */
784         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
785         return new_sector;
786 }
787
788
789 static sector_t compute_blocknr(struct stripe_head *sh, int i)
790 {
791         raid5_conf_t *conf = sh->raid_conf;
792         int raid_disks = sh->disks;
793         int data_disks = raid_disks - conf->max_degraded;
794         sector_t new_sector = sh->sector, check;
795         int sectors_per_chunk = conf->chunk_size >> 9;
796         sector_t stripe;
797         int chunk_offset;
798         int chunk_number, dummy1, dummy2, dd_idx = i;
799         sector_t r_sector;
800
801
802         chunk_offset = sector_div(new_sector, sectors_per_chunk);
803         stripe = new_sector;
804         BUG_ON(new_sector != stripe);
805
806         if (i == sh->pd_idx)
807                 return 0;
808         switch(conf->level) {
809         case 4: break;
810         case 5:
811                 switch (conf->algorithm) {
812                 case ALGORITHM_LEFT_ASYMMETRIC:
813                 case ALGORITHM_RIGHT_ASYMMETRIC:
814                         if (i > sh->pd_idx)
815                                 i--;
816                         break;
817                 case ALGORITHM_LEFT_SYMMETRIC:
818                 case ALGORITHM_RIGHT_SYMMETRIC:
819                         if (i < sh->pd_idx)
820                                 i += raid_disks;
821                         i -= (sh->pd_idx + 1);
822                         break;
823                 default:
824                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
825                                conf->algorithm);
826                 }
827                 break;
828         case 6:
829                 if (i == raid6_next_disk(sh->pd_idx, raid_disks))
830                         return 0; /* It is the Q disk */
831                 switch (conf->algorithm) {
832                 case ALGORITHM_LEFT_ASYMMETRIC:
833                 case ALGORITHM_RIGHT_ASYMMETRIC:
834                         if (sh->pd_idx == raid_disks-1)
835                                 i--;    /* Q D D D P */
836                         else if (i > sh->pd_idx)
837                                 i -= 2; /* D D P Q D */
838                         break;
839                 case ALGORITHM_LEFT_SYMMETRIC:
840                 case ALGORITHM_RIGHT_SYMMETRIC:
841                         if (sh->pd_idx == raid_disks-1)
842                                 i--; /* Q D D D P */
843                         else {
844                                 /* D D P Q D */
845                                 if (i < sh->pd_idx)
846                                         i += raid_disks;
847                                 i -= (sh->pd_idx + 2);
848                         }
849                         break;
850                 default:
851                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
852                                 conf->algorithm);
853                 }
854                 break;
855         }
856
857         chunk_number = stripe * data_disks + i;
858         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
859
860         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
861         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
862                 printk(KERN_ERR "compute_blocknr: map not correct\n");
863                 return 0;
864         }
865         return r_sector;
866 }
867
868
869
870 /*
871  * Copy data between a page in the stripe cache, and one or more bion
872  * The page could align with the middle of the bio, or there could be
873  * several bion, each with several bio_vecs, which cover part of the page
874  * Multiple bion are linked together on bi_next.  There may be extras
875  * at the end of this list.  We ignore them.
876  */
877 static void copy_data(int frombio, struct bio *bio,
878                      struct page *page,
879                      sector_t sector)
880 {
881         char *pa = page_address(page);
882         struct bio_vec *bvl;
883         int i;
884         int page_offset;
885
886         if (bio->bi_sector >= sector)
887                 page_offset = (signed)(bio->bi_sector - sector) * 512;
888         else
889                 page_offset = (signed)(sector - bio->bi_sector) * -512;
890         bio_for_each_segment(bvl, bio, i) {
891                 int len = bio_iovec_idx(bio,i)->bv_len;
892                 int clen;
893                 int b_offset = 0;
894
895                 if (page_offset < 0) {
896                         b_offset = -page_offset;
897                         page_offset += b_offset;
898                         len -= b_offset;
899                 }
900
901                 if (len > 0 && page_offset + len > STRIPE_SIZE)
902                         clen = STRIPE_SIZE - page_offset;
903                 else clen = len;
904
905                 if (clen > 0) {
906                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
907                         if (frombio)
908                                 memcpy(pa+page_offset, ba+b_offset, clen);
909                         else
910                                 memcpy(ba+b_offset, pa+page_offset, clen);
911                         __bio_kunmap_atomic(ba, KM_USER0);
912                 }
913                 if (clen < len) /* hit end of page */
914                         break;
915                 page_offset +=  len;
916         }
917 }
918
919 #define check_xor()     do {                                            \
920                            if (count == MAX_XOR_BLOCKS) {               \
921                                 xor_block(count, STRIPE_SIZE, ptr);     \
922                                 count = 1;                              \
923                            }                                            \
924                         } while(0)
925
926
927 static void compute_block(struct stripe_head *sh, int dd_idx)
928 {
929         int i, count, disks = sh->disks;
930         void *ptr[MAX_XOR_BLOCKS], *p;
931
932         PRINTK("compute_block, stripe %llu, idx %d\n", 
933                 (unsigned long long)sh->sector, dd_idx);
934
935         ptr[0] = page_address(sh->dev[dd_idx].page);
936         memset(ptr[0], 0, STRIPE_SIZE);
937         count = 1;
938         for (i = disks ; i--; ) {
939                 if (i == dd_idx)
940                         continue;
941                 p = page_address(sh->dev[i].page);
942                 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
943                         ptr[count++] = p;
944                 else
945                         printk(KERN_ERR "compute_block() %d, stripe %llu, %d"
946                                 " not present\n", dd_idx,
947                                 (unsigned long long)sh->sector, i);
948
949                 check_xor();
950         }
951         if (count != 1)
952                 xor_block(count, STRIPE_SIZE, ptr);
953         set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
954 }
955
956 static void compute_parity5(struct stripe_head *sh, int method)
957 {
958         raid5_conf_t *conf = sh->raid_conf;
959         int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
960         void *ptr[MAX_XOR_BLOCKS];
961         struct bio *chosen;
962
963         PRINTK("compute_parity5, stripe %llu, method %d\n",
964                 (unsigned long long)sh->sector, method);
965
966         count = 1;
967         ptr[0] = page_address(sh->dev[pd_idx].page);
968         switch(method) {
969         case READ_MODIFY_WRITE:
970                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags));
971                 for (i=disks ; i-- ;) {
972                         if (i==pd_idx)
973                                 continue;
974                         if (sh->dev[i].towrite &&
975                             test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
976                                 ptr[count++] = page_address(sh->dev[i].page);
977                                 chosen = sh->dev[i].towrite;
978                                 sh->dev[i].towrite = NULL;
979
980                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
981                                         wake_up(&conf->wait_for_overlap);
982
983                                 BUG_ON(sh->dev[i].written);
984                                 sh->dev[i].written = chosen;
985                                 check_xor();
986                         }
987                 }
988                 break;
989         case RECONSTRUCT_WRITE:
990                 memset(ptr[0], 0, STRIPE_SIZE);
991                 for (i= disks; i-- ;)
992                         if (i!=pd_idx && sh->dev[i].towrite) {
993                                 chosen = sh->dev[i].towrite;
994                                 sh->dev[i].towrite = NULL;
995
996                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
997                                         wake_up(&conf->wait_for_overlap);
998
999                                 BUG_ON(sh->dev[i].written);
1000                                 sh->dev[i].written = chosen;
1001                         }
1002                 break;
1003         case CHECK_PARITY:
1004                 break;
1005         }
1006         if (count>1) {
1007                 xor_block(count, STRIPE_SIZE, ptr);
1008                 count = 1;
1009         }
1010         
1011         for (i = disks; i--;)
1012                 if (sh->dev[i].written) {
1013                         sector_t sector = sh->dev[i].sector;
1014                         struct bio *wbi = sh->dev[i].written;
1015                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1016                                 copy_data(1, wbi, sh->dev[i].page, sector);
1017                                 wbi = r5_next_bio(wbi, sector);
1018                         }
1019
1020                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1021                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1022                 }
1023
1024         switch(method) {
1025         case RECONSTRUCT_WRITE:
1026         case CHECK_PARITY:
1027                 for (i=disks; i--;)
1028                         if (i != pd_idx) {
1029                                 ptr[count++] = page_address(sh->dev[i].page);
1030                                 check_xor();
1031                         }
1032                 break;
1033         case READ_MODIFY_WRITE:
1034                 for (i = disks; i--;)
1035                         if (sh->dev[i].written) {
1036                                 ptr[count++] = page_address(sh->dev[i].page);
1037                                 check_xor();
1038                         }
1039         }
1040         if (count != 1)
1041                 xor_block(count, STRIPE_SIZE, ptr);
1042         
1043         if (method != CHECK_PARITY) {
1044                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1045                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1046         } else
1047                 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1048 }
1049
1050 static void compute_parity6(struct stripe_head *sh, int method)
1051 {
1052         raid6_conf_t *conf = sh->raid_conf;
1053         int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
1054         struct bio *chosen;
1055         /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1056         void *ptrs[disks];
1057
1058         qd_idx = raid6_next_disk(pd_idx, disks);
1059         d0_idx = raid6_next_disk(qd_idx, disks);
1060
1061         PRINTK("compute_parity, stripe %llu, method %d\n",
1062                 (unsigned long long)sh->sector, method);
1063
1064         switch(method) {
1065         case READ_MODIFY_WRITE:
1066                 BUG();          /* READ_MODIFY_WRITE N/A for RAID-6 */
1067         case RECONSTRUCT_WRITE:
1068                 for (i= disks; i-- ;)
1069                         if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1070                                 chosen = sh->dev[i].towrite;
1071                                 sh->dev[i].towrite = NULL;
1072
1073                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1074                                         wake_up(&conf->wait_for_overlap);
1075
1076                                 BUG_ON(sh->dev[i].written);
1077                                 sh->dev[i].written = chosen;
1078                         }
1079                 break;
1080         case CHECK_PARITY:
1081                 BUG();          /* Not implemented yet */
1082         }
1083
1084         for (i = disks; i--;)
1085                 if (sh->dev[i].written) {
1086                         sector_t sector = sh->dev[i].sector;
1087                         struct bio *wbi = sh->dev[i].written;
1088                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1089                                 copy_data(1, wbi, sh->dev[i].page, sector);
1090                                 wbi = r5_next_bio(wbi, sector);
1091                         }
1092
1093                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1094                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1095                 }
1096
1097 //      switch(method) {
1098 //      case RECONSTRUCT_WRITE:
1099 //      case CHECK_PARITY:
1100 //      case UPDATE_PARITY:
1101                 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1102                 /* FIX: Is this ordering of drives even remotely optimal? */
1103                 count = 0;
1104                 i = d0_idx;
1105                 do {
1106                         ptrs[count++] = page_address(sh->dev[i].page);
1107                         if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1108                                 printk("block %d/%d not uptodate on parity calc\n", i,count);
1109                         i = raid6_next_disk(i, disks);
1110                 } while ( i != d0_idx );
1111 //              break;
1112 //      }
1113
1114         raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1115
1116         switch(method) {
1117         case RECONSTRUCT_WRITE:
1118                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1119                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1120                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1121                 set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1122                 break;
1123         case UPDATE_PARITY:
1124                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1125                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1126                 break;
1127         }
1128 }
1129
1130
1131 /* Compute one missing block */
1132 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1133 {
1134         int i, count, disks = sh->disks;
1135         void *ptr[MAX_XOR_BLOCKS], *p;
1136         int pd_idx = sh->pd_idx;
1137         int qd_idx = raid6_next_disk(pd_idx, disks);
1138
1139         PRINTK("compute_block_1, stripe %llu, idx %d\n",
1140                 (unsigned long long)sh->sector, dd_idx);
1141
1142         if ( dd_idx == qd_idx ) {
1143                 /* We're actually computing the Q drive */
1144                 compute_parity6(sh, UPDATE_PARITY);
1145         } else {
1146                 ptr[0] = page_address(sh->dev[dd_idx].page);
1147                 if (!nozero) memset(ptr[0], 0, STRIPE_SIZE);
1148                 count = 1;
1149                 for (i = disks ; i--; ) {
1150                         if (i == dd_idx || i == qd_idx)
1151                                 continue;
1152                         p = page_address(sh->dev[i].page);
1153                         if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1154                                 ptr[count++] = p;
1155                         else
1156                                 printk("compute_block() %d, stripe %llu, %d"
1157                                        " not present\n", dd_idx,
1158                                        (unsigned long long)sh->sector, i);
1159
1160                         check_xor();
1161                 }
1162                 if (count != 1)
1163                         xor_block(count, STRIPE_SIZE, ptr);
1164                 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1165                 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1166         }
1167 }
1168
1169 /* Compute two missing blocks */
1170 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1171 {
1172         int i, count, disks = sh->disks;
1173         int pd_idx = sh->pd_idx;
1174         int qd_idx = raid6_next_disk(pd_idx, disks);
1175         int d0_idx = raid6_next_disk(qd_idx, disks);
1176         int faila, failb;
1177
1178         /* faila and failb are disk numbers relative to d0_idx */
1179         /* pd_idx become disks-2 and qd_idx become disks-1 */
1180         faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1181         failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1182
1183         BUG_ON(faila == failb);
1184         if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1185
1186         PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1187                (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1188
1189         if ( failb == disks-1 ) {
1190                 /* Q disk is one of the missing disks */
1191                 if ( faila == disks-2 ) {
1192                         /* Missing P+Q, just recompute */
1193                         compute_parity6(sh, UPDATE_PARITY);
1194                         return;
1195                 } else {
1196                         /* We're missing D+Q; recompute D from P */
1197                         compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1198                         compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1199                         return;
1200                 }
1201         }
1202
1203         /* We're missing D+P or D+D; build pointer table */
1204         {
1205                 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1206                 void *ptrs[disks];
1207
1208                 count = 0;
1209                 i = d0_idx;
1210                 do {
1211                         ptrs[count++] = page_address(sh->dev[i].page);
1212                         i = raid6_next_disk(i, disks);
1213                         if (i != dd_idx1 && i != dd_idx2 &&
1214                             !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1215                                 printk("compute_2 with missing block %d/%d\n", count, i);
1216                 } while ( i != d0_idx );
1217
1218                 if ( failb == disks-2 ) {
1219                         /* We're missing D+P. */
1220                         raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1221                 } else {
1222                         /* We're missing D+D. */
1223                         raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1224                 }
1225
1226                 /* Both the above update both missing blocks */
1227                 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1228                 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1229         }
1230 }
1231
1232
1233
1234 /*
1235  * Each stripe/dev can have one or more bion attached.
1236  * toread/towrite point to the first in a chain.
1237  * The bi_next chain must be in order.
1238  */
1239 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1240 {
1241         struct bio **bip;
1242         raid5_conf_t *conf = sh->raid_conf;
1243         int firstwrite=0;
1244
1245         PRINTK("adding bh b#%llu to stripe s#%llu\n",
1246                 (unsigned long long)bi->bi_sector,
1247                 (unsigned long long)sh->sector);
1248
1249
1250         spin_lock(&sh->lock);
1251         spin_lock_irq(&conf->device_lock);
1252         if (forwrite) {
1253                 bip = &sh->dev[dd_idx].towrite;
1254                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1255                         firstwrite = 1;
1256         } else
1257                 bip = &sh->dev[dd_idx].toread;
1258         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1259                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1260                         goto overlap;
1261                 bip = & (*bip)->bi_next;
1262         }
1263         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1264                 goto overlap;
1265
1266         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1267         if (*bip)
1268                 bi->bi_next = *bip;
1269         *bip = bi;
1270         bi->bi_phys_segments ++;
1271         spin_unlock_irq(&conf->device_lock);
1272         spin_unlock(&sh->lock);
1273
1274         PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
1275                 (unsigned long long)bi->bi_sector,
1276                 (unsigned long long)sh->sector, dd_idx);
1277
1278         if (conf->mddev->bitmap && firstwrite) {
1279                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1280                                   STRIPE_SECTORS, 0);
1281                 sh->bm_seq = conf->seq_flush+1;
1282                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1283         }
1284
1285         if (forwrite) {
1286                 /* check if page is covered */
1287                 sector_t sector = sh->dev[dd_idx].sector;
1288                 for (bi=sh->dev[dd_idx].towrite;
1289                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1290                              bi && bi->bi_sector <= sector;
1291                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1292                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1293                                 sector = bi->bi_sector + (bi->bi_size>>9);
1294                 }
1295                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1296                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1297         }
1298         return 1;
1299
1300  overlap:
1301         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1302         spin_unlock_irq(&conf->device_lock);
1303         spin_unlock(&sh->lock);
1304         return 0;
1305 }
1306
1307 static void end_reshape(raid5_conf_t *conf);
1308
1309 static int page_is_zero(struct page *p)
1310 {
1311         char *a = page_address(p);
1312         return ((*(u32*)a) == 0 &&
1313                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1314 }
1315
1316 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1317 {
1318         int sectors_per_chunk = conf->chunk_size >> 9;
1319         int pd_idx, dd_idx;
1320         int chunk_offset = sector_div(stripe, sectors_per_chunk);
1321
1322         raid5_compute_sector(stripe * (disks - conf->max_degraded)
1323                              *sectors_per_chunk + chunk_offset,
1324                              disks, disks - conf->max_degraded,
1325                              &dd_idx, &pd_idx, conf);
1326         return pd_idx;
1327 }
1328
1329
1330 /*
1331  * handle_stripe - do things to a stripe.
1332  *
1333  * We lock the stripe and then examine the state of various bits
1334  * to see what needs to be done.
1335  * Possible results:
1336  *    return some read request which now have data
1337  *    return some write requests which are safely on disc
1338  *    schedule a read on some buffers
1339  *    schedule a write of some buffers
1340  *    return confirmation of parity correctness
1341  *
1342  * Parity calculations are done inside the stripe lock
1343  * buffers are taken off read_list or write_list, and bh_cache buffers
1344  * get BH_Lock set before the stripe lock is released.
1345  *
1346  */
1347  
1348 static void handle_stripe5(struct stripe_head *sh)
1349 {
1350         raid5_conf_t *conf = sh->raid_conf;
1351         int disks = sh->disks;
1352         struct bio *return_bi= NULL;
1353         struct bio *bi;
1354         int i;
1355         int syncing, expanding, expanded;
1356         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
1357         int non_overwrite = 0;
1358         int failed_num=0;
1359         struct r5dev *dev;
1360
1361         PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n",
1362                 (unsigned long long)sh->sector, atomic_read(&sh->count),
1363                 sh->pd_idx);
1364
1365         spin_lock(&sh->lock);
1366         clear_bit(STRIPE_HANDLE, &sh->state);
1367         clear_bit(STRIPE_DELAYED, &sh->state);
1368
1369         syncing = test_bit(STRIPE_SYNCING, &sh->state);
1370         expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
1371         expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
1372         /* Now to look around and see what can be done */
1373
1374         rcu_read_lock();
1375         for (i=disks; i--; ) {
1376                 mdk_rdev_t *rdev;
1377                 dev = &sh->dev[i];
1378                 clear_bit(R5_Insync, &dev->flags);
1379
1380                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
1381                         i, dev->flags, dev->toread, dev->towrite, dev->written);
1382                 /* maybe we can reply to a read */
1383                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
1384                         struct bio *rbi, *rbi2;
1385                         PRINTK("Return read for disc %d\n", i);
1386                         spin_lock_irq(&conf->device_lock);
1387                         rbi = dev->toread;
1388                         dev->toread = NULL;
1389                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1390                                 wake_up(&conf->wait_for_overlap);
1391                         spin_unlock_irq(&conf->device_lock);
1392                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1393                                 copy_data(0, rbi, dev->page, dev->sector);
1394                                 rbi2 = r5_next_bio(rbi, dev->sector);
1395                                 spin_lock_irq(&conf->device_lock);
1396                                 if (--rbi->bi_phys_segments == 0) {
1397                                         rbi->bi_next = return_bi;
1398                                         return_bi = rbi;
1399                                 }
1400                                 spin_unlock_irq(&conf->device_lock);
1401                                 rbi = rbi2;
1402                         }
1403                 }
1404
1405                 /* now count some things */
1406                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
1407                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
1408
1409                 
1410                 if (dev->toread) to_read++;
1411                 if (dev->towrite) {
1412                         to_write++;
1413                         if (!test_bit(R5_OVERWRITE, &dev->flags))
1414                                 non_overwrite++;
1415                 }
1416                 if (dev->written) written++;
1417                 rdev = rcu_dereference(conf->disks[i].rdev);
1418                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
1419                         /* The ReadError flag will just be confusing now */
1420                         clear_bit(R5_ReadError, &dev->flags);
1421                         clear_bit(R5_ReWrite, &dev->flags);
1422                 }
1423                 if (!rdev || !test_bit(In_sync, &rdev->flags)
1424                     || test_bit(R5_ReadError, &dev->flags)) {
1425                         failed++;
1426                         failed_num = i;
1427                 } else
1428                         set_bit(R5_Insync, &dev->flags);
1429         }
1430         rcu_read_unlock();
1431         PRINTK("locked=%d uptodate=%d to_read=%d"
1432                 " to_write=%d failed=%d failed_num=%d\n",
1433                 locked, uptodate, to_read, to_write, failed, failed_num);
1434         /* check if the array has lost two devices and, if so, some requests might
1435          * need to be failed
1436          */
1437         if (failed > 1 && to_read+to_write+written) {
1438                 for (i=disks; i--; ) {
1439                         int bitmap_end = 0;
1440
1441                         if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1442                                 mdk_rdev_t *rdev;
1443                                 rcu_read_lock();
1444                                 rdev = rcu_dereference(conf->disks[i].rdev);
1445                                 if (rdev && test_bit(In_sync, &rdev->flags))
1446                                         /* multiple read failures in one stripe */
1447                                         md_error(conf->mddev, rdev);
1448                                 rcu_read_unlock();
1449                         }
1450
1451                         spin_lock_irq(&conf->device_lock);
1452                         /* fail all writes first */
1453                         bi = sh->dev[i].towrite;
1454                         sh->dev[i].towrite = NULL;
1455                         if (bi) { to_write--; bitmap_end = 1; }
1456
1457                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1458                                 wake_up(&conf->wait_for_overlap);
1459
1460                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1461                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1462                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1463                                 if (--bi->bi_phys_segments == 0) {
1464                                         md_write_end(conf->mddev);
1465                                         bi->bi_next = return_bi;
1466                                         return_bi = bi;
1467                                 }
1468                                 bi = nextbi;
1469                         }
1470                         /* and fail all 'written' */
1471                         bi = sh->dev[i].written;
1472                         sh->dev[i].written = NULL;
1473                         if (bi) bitmap_end = 1;
1474                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
1475                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1476                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1477                                 if (--bi->bi_phys_segments == 0) {
1478                                         md_write_end(conf->mddev);
1479                                         bi->bi_next = return_bi;
1480                                         return_bi = bi;
1481                                 }
1482                                 bi = bi2;
1483                         }
1484
1485                         /* fail any reads if this device is non-operational */
1486                         if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1487                             test_bit(R5_ReadError, &sh->dev[i].flags)) {
1488                                 bi = sh->dev[i].toread;
1489                                 sh->dev[i].toread = NULL;
1490                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1491                                         wake_up(&conf->wait_for_overlap);
1492                                 if (bi) to_read--;
1493                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1494                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1495                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1496                                         if (--bi->bi_phys_segments == 0) {
1497                                                 bi->bi_next = return_bi;
1498                                                 return_bi = bi;
1499                                         }
1500                                         bi = nextbi;
1501                                 }
1502                         }
1503                         spin_unlock_irq(&conf->device_lock);
1504                         if (bitmap_end)
1505                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1506                                                 STRIPE_SECTORS, 0, 0);
1507                 }
1508         }
1509         if (failed > 1 && syncing) {
1510                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1511                 clear_bit(STRIPE_SYNCING, &sh->state);
1512                 syncing = 0;
1513         }
1514
1515         /* might be able to return some write requests if the parity block
1516          * is safe, or on a failed drive
1517          */
1518         dev = &sh->dev[sh->pd_idx];
1519         if ( written &&
1520              ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) &&
1521                 test_bit(R5_UPTODATE, &dev->flags))
1522                || (failed == 1 && failed_num == sh->pd_idx))
1523             ) {
1524             /* any written block on an uptodate or failed drive can be returned.
1525              * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but 
1526              * never LOCKED, so we don't need to test 'failed' directly.
1527              */
1528             for (i=disks; i--; )
1529                 if (sh->dev[i].written) {
1530                     dev = &sh->dev[i];
1531                     if (!test_bit(R5_LOCKED, &dev->flags) &&
1532                          test_bit(R5_UPTODATE, &dev->flags) ) {
1533                         /* We can return any write requests */
1534                             struct bio *wbi, *wbi2;
1535                             int bitmap_end = 0;
1536                             PRINTK("Return write for disc %d\n", i);
1537                             spin_lock_irq(&conf->device_lock);
1538                             wbi = dev->written;
1539                             dev->written = NULL;
1540                             while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1541                                     wbi2 = r5_next_bio(wbi, dev->sector);
1542                                     if (--wbi->bi_phys_segments == 0) {
1543                                             md_write_end(conf->mddev);
1544                                             wbi->bi_next = return_bi;
1545                                             return_bi = wbi;
1546                                     }
1547                                     wbi = wbi2;
1548                             }
1549                             if (dev->towrite == NULL)
1550                                     bitmap_end = 1;
1551                             spin_unlock_irq(&conf->device_lock);
1552                             if (bitmap_end)
1553                                     bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1554                                                     STRIPE_SECTORS,
1555                                                     !test_bit(STRIPE_DEGRADED, &sh->state), 0);
1556                     }
1557                 }
1558         }
1559
1560         /* Now we might consider reading some blocks, either to check/generate
1561          * parity, or to satisfy requests
1562          * or to load a block that is being partially written.
1563          */
1564         if (to_read || non_overwrite || (syncing && (uptodate < disks)) || expanding) {
1565                 for (i=disks; i--;) {
1566                         dev = &sh->dev[i];
1567                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1568                             (dev->toread ||
1569                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1570                              syncing ||
1571                              expanding ||
1572                              (failed && (sh->dev[failed_num].toread ||
1573                                          (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
1574                                     )
1575                                 ) {
1576                                 /* we would like to get this block, possibly
1577                                  * by computing it, but we might not be able to
1578                                  */
1579                                 if (uptodate == disks-1) {
1580                                         PRINTK("Computing block %d\n", i);
1581                                         compute_block(sh, i);
1582                                         uptodate++;
1583                                 } else if (test_bit(R5_Insync, &dev->flags)) {
1584                                         set_bit(R5_LOCKED, &dev->flags);
1585                                         set_bit(R5_Wantread, &dev->flags);
1586                                         locked++;
1587                                         PRINTK("Reading block %d (sync=%d)\n", 
1588                                                 i, syncing);
1589                                 }
1590                         }
1591                 }
1592                 set_bit(STRIPE_HANDLE, &sh->state);
1593         }
1594
1595         /* now to consider writing and what else, if anything should be read */
1596         if (to_write) {
1597                 int rmw=0, rcw=0;
1598                 for (i=disks ; i--;) {
1599                         /* would I have to read this buffer for read_modify_write */
1600                         dev = &sh->dev[i];
1601                         if ((dev->towrite || i == sh->pd_idx) &&
1602                             (!test_bit(R5_LOCKED, &dev->flags) 
1603                                     ) &&
1604                             !test_bit(R5_UPTODATE, &dev->flags)) {
1605                                 if (test_bit(R5_Insync, &dev->flags)
1606 /*                                  && !(!mddev->insync && i == sh->pd_idx) */
1607                                         )
1608                                         rmw++;
1609                                 else rmw += 2*disks;  /* cannot read it */
1610                         }
1611                         /* Would I have to read this buffer for reconstruct_write */
1612                         if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1613                             (!test_bit(R5_LOCKED, &dev->flags) 
1614                                     ) &&
1615                             !test_bit(R5_UPTODATE, &dev->flags)) {
1616                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1617                                 else rcw += 2*disks;
1618                         }
1619                 }
1620                 PRINTK("for sector %llu, rmw=%d rcw=%d\n", 
1621                         (unsigned long long)sh->sector, rmw, rcw);
1622                 set_bit(STRIPE_HANDLE, &sh->state);
1623                 if (rmw < rcw && rmw > 0)
1624                         /* prefer read-modify-write, but need to get some data */
1625                         for (i=disks; i--;) {
1626                                 dev = &sh->dev[i];
1627                                 if ((dev->towrite || i == sh->pd_idx) &&
1628                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1629                                     test_bit(R5_Insync, &dev->flags)) {
1630                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1631                                         {
1632                                                 PRINTK("Read_old block %d for r-m-w\n", i);
1633                                                 set_bit(R5_LOCKED, &dev->flags);
1634                                                 set_bit(R5_Wantread, &dev->flags);
1635                                                 locked++;
1636                                         } else {
1637                                                 set_bit(STRIPE_DELAYED, &sh->state);
1638                                                 set_bit(STRIPE_HANDLE, &sh->state);
1639                                         }
1640                                 }
1641                         }
1642                 if (rcw <= rmw && rcw > 0)
1643                         /* want reconstruct write, but need to get some data */
1644                         for (i=disks; i--;) {
1645                                 dev = &sh->dev[i];
1646                                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1647                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1648                                     test_bit(R5_Insync, &dev->flags)) {
1649                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1650                                         {
1651                                                 PRINTK("Read_old block %d for Reconstruct\n", i);
1652                                                 set_bit(R5_LOCKED, &dev->flags);
1653                                                 set_bit(R5_Wantread, &dev->flags);
1654                                                 locked++;
1655                                         } else {
1656                                                 set_bit(STRIPE_DELAYED, &sh->state);
1657                                                 set_bit(STRIPE_HANDLE, &sh->state);
1658                                         }
1659                                 }
1660                         }
1661                 /* now if nothing is locked, and if we have enough data, we can start a write request */
1662                 if (locked == 0 && (rcw == 0 ||rmw == 0) &&
1663                     !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
1664                         PRINTK("Computing parity...\n");
1665                         compute_parity5(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
1666                         /* now every locked buffer is ready to be written */
1667                         for (i=disks; i--;)
1668                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1669                                         PRINTK("Writing block %d\n", i);
1670                                         locked++;
1671                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1672                                         if (!test_bit(R5_Insync, &sh->dev[i].flags)
1673                                             || (i==sh->pd_idx && failed == 0))
1674                                                 set_bit(STRIPE_INSYNC, &sh->state);
1675                                 }
1676                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1677                                 atomic_dec(&conf->preread_active_stripes);
1678                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1679                                         md_wakeup_thread(conf->mddev->thread);
1680                         }
1681                 }
1682         }
1683
1684         /* maybe we need to check and possibly fix the parity for this stripe
1685          * Any reads will already have been scheduled, so we just see if enough data
1686          * is available
1687          */
1688         if (syncing && locked == 0 &&
1689             !test_bit(STRIPE_INSYNC, &sh->state)) {
1690                 set_bit(STRIPE_HANDLE, &sh->state);
1691                 if (failed == 0) {
1692                         BUG_ON(uptodate != disks);
1693                         compute_parity5(sh, CHECK_PARITY);
1694                         uptodate--;
1695                         if (page_is_zero(sh->dev[sh->pd_idx].page)) {
1696                                 /* parity is correct (on disc, not in buffer any more) */
1697                                 set_bit(STRIPE_INSYNC, &sh->state);
1698                         } else {
1699                                 conf->mddev->resync_mismatches += STRIPE_SECTORS;
1700                                 if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
1701                                         /* don't try to repair!! */
1702                                         set_bit(STRIPE_INSYNC, &sh->state);
1703                                 else {
1704                                         compute_block(sh, sh->pd_idx);
1705                                         uptodate++;
1706                                 }
1707                         }
1708                 }
1709                 if (!test_bit(STRIPE_INSYNC, &sh->state)) {
1710                         /* either failed parity check, or recovery is happening */
1711                         if (failed==0)
1712                                 failed_num = sh->pd_idx;
1713                         dev = &sh->dev[failed_num];
1714                         BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
1715                         BUG_ON(uptodate != disks);
1716
1717                         set_bit(R5_LOCKED, &dev->flags);
1718                         set_bit(R5_Wantwrite, &dev->flags);
1719                         clear_bit(STRIPE_DEGRADED, &sh->state);
1720                         locked++;
1721                         set_bit(STRIPE_INSYNC, &sh->state);
1722                 }
1723         }
1724         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1725                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1726                 clear_bit(STRIPE_SYNCING, &sh->state);
1727         }
1728
1729         /* If the failed drive is just a ReadError, then we might need to progress
1730          * the repair/check process
1731          */
1732         if (failed == 1 && ! conf->mddev->ro &&
1733             test_bit(R5_ReadError, &sh->dev[failed_num].flags)
1734             && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags)
1735             && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)
1736                 ) {
1737                 dev = &sh->dev[failed_num];
1738                 if (!test_bit(R5_ReWrite, &dev->flags)) {
1739                         set_bit(R5_Wantwrite, &dev->flags);
1740                         set_bit(R5_ReWrite, &dev->flags);
1741                         set_bit(R5_LOCKED, &dev->flags);
1742                         locked++;
1743                 } else {
1744                         /* let's read it back */
1745                         set_bit(R5_Wantread, &dev->flags);
1746                         set_bit(R5_LOCKED, &dev->flags);
1747                         locked++;
1748                 }
1749         }
1750
1751         if (expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
1752                 /* Need to write out all blocks after computing parity */
1753                 sh->disks = conf->raid_disks;
1754                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf, conf->raid_disks);
1755                 compute_parity5(sh, RECONSTRUCT_WRITE);
1756                 for (i= conf->raid_disks; i--;) {
1757                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1758                         locked++;
1759                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1760                 }
1761                 clear_bit(STRIPE_EXPANDING, &sh->state);
1762         } else if (expanded) {
1763                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
1764                 atomic_dec(&conf->reshape_stripes);
1765                 wake_up(&conf->wait_for_overlap);
1766                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
1767         }
1768
1769         if (expanding && locked == 0) {
1770                 /* We have read all the blocks in this stripe and now we need to
1771                  * copy some of them into a target stripe for expand.
1772                  */
1773                 clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
1774                 for (i=0; i< sh->disks; i++)
1775                         if (i != sh->pd_idx) {
1776                                 int dd_idx, pd_idx, j;
1777                                 struct stripe_head *sh2;
1778
1779                                 sector_t bn = compute_blocknr(sh, i);
1780                                 sector_t s = raid5_compute_sector(bn, conf->raid_disks,
1781                                                                   conf->raid_disks-1,
1782                                                                   &dd_idx, &pd_idx, conf);
1783                                 sh2 = get_active_stripe(conf, s, conf->raid_disks, pd_idx, 1);
1784                                 if (sh2 == NULL)
1785                                         /* so far only the early blocks of this stripe
1786                                          * have been requested.  When later blocks
1787                                          * get requested, we will try again
1788                                          */
1789                                         continue;
1790                                 if(!test_bit(STRIPE_EXPANDING, &sh2->state) ||
1791                                    test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
1792                                         /* must have already done this block */
1793                                         release_stripe(sh2);
1794                                         continue;
1795                                 }
1796                                 memcpy(page_address(sh2->dev[dd_idx].page),
1797                                        page_address(sh->dev[i].page),
1798                                        STRIPE_SIZE);
1799                                 set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
1800                                 set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
1801                                 for (j=0; j<conf->raid_disks; j++)
1802                                         if (j != sh2->pd_idx &&
1803                                             !test_bit(R5_Expanded, &sh2->dev[j].flags))
1804                                                 break;
1805                                 if (j == conf->raid_disks) {
1806                                         set_bit(STRIPE_EXPAND_READY, &sh2->state);
1807                                         set_bit(STRIPE_HANDLE, &sh2->state);
1808                                 }
1809                                 release_stripe(sh2);
1810                         }
1811         }
1812
1813         spin_unlock(&sh->lock);
1814
1815         while ((bi=return_bi)) {
1816                 int bytes = bi->bi_size;
1817
1818                 return_bi = bi->bi_next;
1819                 bi->bi_next = NULL;
1820                 bi->bi_size = 0;
1821                 bi->bi_end_io(bi, bytes,
1822                               test_bit(BIO_UPTODATE, &bi->bi_flags)
1823                                 ? 0 : -EIO);
1824         }
1825         for (i=disks; i-- ;) {
1826                 int rw;
1827                 struct bio *bi;
1828                 mdk_rdev_t *rdev;
1829                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1830                         rw = WRITE;
1831                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1832                         rw = READ;
1833                 else
1834                         continue;
1835  
1836                 bi = &sh->dev[i].req;
1837  
1838                 bi->bi_rw = rw;
1839                 if (rw == WRITE)
1840                         bi->bi_end_io = raid5_end_write_request;
1841                 else
1842                         bi->bi_end_io = raid5_end_read_request;
1843  
1844                 rcu_read_lock();
1845                 rdev = rcu_dereference(conf->disks[i].rdev);
1846                 if (rdev && test_bit(Faulty, &rdev->flags))
1847                         rdev = NULL;
1848                 if (rdev)
1849                         atomic_inc(&rdev->nr_pending);
1850                 rcu_read_unlock();
1851  
1852                 if (rdev) {
1853                         if (syncing || expanding || expanded)
1854                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1855
1856                         bi->bi_bdev = rdev->bdev;
1857                         PRINTK("for %llu schedule op %ld on disc %d\n",
1858                                 (unsigned long long)sh->sector, bi->bi_rw, i);
1859                         atomic_inc(&sh->count);
1860                         bi->bi_sector = sh->sector + rdev->data_offset;
1861                         bi->bi_flags = 1 << BIO_UPTODATE;
1862                         bi->bi_vcnt = 1;        
1863                         bi->bi_max_vecs = 1;
1864                         bi->bi_idx = 0;
1865                         bi->bi_io_vec = &sh->dev[i].vec;
1866                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1867                         bi->bi_io_vec[0].bv_offset = 0;
1868                         bi->bi_size = STRIPE_SIZE;
1869                         bi->bi_next = NULL;
1870                         if (rw == WRITE &&
1871                             test_bit(R5_ReWrite, &sh->dev[i].flags))
1872                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1873                         generic_make_request(bi);
1874                 } else {
1875                         if (rw == WRITE)
1876                                 set_bit(STRIPE_DEGRADED, &sh->state);
1877                         PRINTK("skip op %ld on disc %d for sector %llu\n",
1878                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1879                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1880                         set_bit(STRIPE_HANDLE, &sh->state);
1881                 }
1882         }
1883 }
1884
1885 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
1886 {
1887         raid6_conf_t *conf = sh->raid_conf;
1888         int disks = sh->disks;
1889         struct bio *return_bi= NULL;
1890         struct bio *bi;
1891         int i;
1892         int syncing, expanding, expanded;
1893         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
1894         int non_overwrite = 0;
1895         int failed_num[2] = {0, 0};
1896         struct r5dev *dev, *pdev, *qdev;
1897         int pd_idx = sh->pd_idx;
1898         int qd_idx = raid6_next_disk(pd_idx, disks);
1899         int p_failed, q_failed;
1900
1901         PRINTK("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d, qd_idx=%d\n",
1902                (unsigned long long)sh->sector, sh->state, atomic_read(&sh->count),
1903                pd_idx, qd_idx);
1904
1905         spin_lock(&sh->lock);
1906         clear_bit(STRIPE_HANDLE, &sh->state);
1907         clear_bit(STRIPE_DELAYED, &sh->state);
1908
1909         syncing = test_bit(STRIPE_SYNCING, &sh->state);
1910         expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
1911         expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
1912         /* Now to look around and see what can be done */
1913
1914         rcu_read_lock();
1915         for (i=disks; i--; ) {
1916                 mdk_rdev_t *rdev;
1917                 dev = &sh->dev[i];
1918                 clear_bit(R5_Insync, &dev->flags);
1919
1920                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
1921                         i, dev->flags, dev->toread, dev->towrite, dev->written);
1922                 /* maybe we can reply to a read */
1923                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
1924                         struct bio *rbi, *rbi2;
1925                         PRINTK("Return read for disc %d\n", i);
1926                         spin_lock_irq(&conf->device_lock);
1927                         rbi = dev->toread;
1928                         dev->toread = NULL;
1929                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1930                                 wake_up(&conf->wait_for_overlap);
1931                         spin_unlock_irq(&conf->device_lock);
1932                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1933                                 copy_data(0, rbi, dev->page, dev->sector);
1934                                 rbi2 = r5_next_bio(rbi, dev->sector);
1935                                 spin_lock_irq(&conf->device_lock);
1936                                 if (--rbi->bi_phys_segments == 0) {
1937                                         rbi->bi_next = return_bi;
1938                                         return_bi = rbi;
1939                                 }
1940                                 spin_unlock_irq(&conf->device_lock);
1941                                 rbi = rbi2;
1942                         }
1943                 }
1944
1945                 /* now count some things */
1946                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
1947                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
1948
1949
1950                 if (dev->toread) to_read++;
1951                 if (dev->towrite) {
1952                         to_write++;
1953                         if (!test_bit(R5_OVERWRITE, &dev->flags))
1954                                 non_overwrite++;
1955                 }
1956                 if (dev->written) written++;
1957                 rdev = rcu_dereference(conf->disks[i].rdev);
1958                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
1959                         /* The ReadError flag will just be confusing now */
1960                         clear_bit(R5_ReadError, &dev->flags);
1961                         clear_bit(R5_ReWrite, &dev->flags);
1962                 }
1963                 if (!rdev || !test_bit(In_sync, &rdev->flags)
1964                     || test_bit(R5_ReadError, &dev->flags)) {
1965                         if ( failed < 2 )
1966                                 failed_num[failed] = i;
1967                         failed++;
1968                 } else
1969                         set_bit(R5_Insync, &dev->flags);
1970         }
1971         rcu_read_unlock();
1972         PRINTK("locked=%d uptodate=%d to_read=%d"
1973                " to_write=%d failed=%d failed_num=%d,%d\n",
1974                locked, uptodate, to_read, to_write, failed,
1975                failed_num[0], failed_num[1]);
1976         /* check if the array has lost >2 devices and, if so, some requests might
1977          * need to be failed
1978          */
1979         if (failed > 2 && to_read+to_write+written) {
1980                 for (i=disks; i--; ) {
1981                         int bitmap_end = 0;
1982
1983                         if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1984                                 mdk_rdev_t *rdev;
1985                                 rcu_read_lock();
1986                                 rdev = rcu_dereference(conf->disks[i].rdev);
1987                                 if (rdev && test_bit(In_sync, &rdev->flags))
1988                                         /* multiple read failures in one stripe */
1989                                         md_error(conf->mddev, rdev);
1990                                 rcu_read_unlock();
1991                         }
1992
1993                         spin_lock_irq(&conf->device_lock);
1994                         /* fail all writes first */
1995                         bi = sh->dev[i].towrite;
1996                         sh->dev[i].towrite = NULL;
1997                         if (bi) { to_write--; bitmap_end = 1; }
1998
1999                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2000                                 wake_up(&conf->wait_for_overlap);
2001
2002                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
2003                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2004                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2005                                 if (--bi->bi_phys_segments == 0) {
2006                                         md_write_end(conf->mddev);
2007                                         bi->bi_next = return_bi;
2008                                         return_bi = bi;
2009                                 }
2010                                 bi = nextbi;
2011                         }
2012                         /* and fail all 'written' */
2013                         bi = sh->dev[i].written;
2014                         sh->dev[i].written = NULL;
2015                         if (bi) bitmap_end = 1;
2016                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
2017                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2018                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2019                                 if (--bi->bi_phys_segments == 0) {
2020                                         md_write_end(conf->mddev);
2021                                         bi->bi_next = return_bi;
2022                                         return_bi = bi;
2023                                 }
2024                                 bi = bi2;
2025                         }
2026
2027                         /* fail any reads if this device is non-operational */
2028                         if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2029                             test_bit(R5_ReadError, &sh->dev[i].flags)) {
2030                                 bi = sh->dev[i].toread;
2031                                 sh->dev[i].toread = NULL;
2032                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2033                                         wake_up(&conf->wait_for_overlap);
2034                                 if (bi) to_read--;
2035                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
2036                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2037                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2038                                         if (--bi->bi_phys_segments == 0) {
2039                                                 bi->bi_next = return_bi;
2040                                                 return_bi = bi;
2041                                         }
2042                                         bi = nextbi;
2043                                 }
2044                         }
2045                         spin_unlock_irq(&conf->device_lock);
2046                         if (bitmap_end)
2047                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2048                                                 STRIPE_SECTORS, 0, 0);
2049                 }
2050         }
2051         if (failed > 2 && syncing) {
2052                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2053                 clear_bit(STRIPE_SYNCING, &sh->state);
2054                 syncing = 0;
2055         }
2056
2057         /*
2058          * might be able to return some write requests if the parity blocks
2059          * are safe, or on a failed drive
2060          */
2061         pdev = &sh->dev[pd_idx];
2062         p_failed = (failed >= 1 && failed_num[0] == pd_idx)
2063                 || (failed >= 2 && failed_num[1] == pd_idx);
2064         qdev = &sh->dev[qd_idx];
2065         q_failed = (failed >= 1 && failed_num[0] == qd_idx)
2066                 || (failed >= 2 && failed_num[1] == qd_idx);
2067
2068         if ( written &&
2069              ( p_failed || ((test_bit(R5_Insync, &pdev->flags)
2070                              && !test_bit(R5_LOCKED, &pdev->flags)
2071                              && test_bit(R5_UPTODATE, &pdev->flags))) ) &&
2072              ( q_failed || ((test_bit(R5_Insync, &qdev->flags)
2073                              && !test_bit(R5_LOCKED, &qdev->flags)
2074                              && test_bit(R5_UPTODATE, &qdev->flags))) ) ) {
2075                 /* any written block on an uptodate or failed drive can be
2076                  * returned.  Note that if we 'wrote' to a failed drive,
2077                  * it will be UPTODATE, but never LOCKED, so we don't need
2078                  * to test 'failed' directly.
2079                  */
2080                 for (i=disks; i--; )
2081                         if (sh->dev[i].written) {
2082                                 dev = &sh->dev[i];
2083                                 if (!test_bit(R5_LOCKED, &dev->flags) &&
2084                                     test_bit(R5_UPTODATE, &dev->flags) ) {
2085                                         /* We can return any write requests */
2086                                         int bitmap_end = 0;
2087                                         struct bio *wbi, *wbi2;
2088                                         PRINTK("Return write for stripe %llu disc %d\n",
2089                                                (unsigned long long)sh->sector, i);
2090                                         spin_lock_irq(&conf->device_lock);
2091                                         wbi = dev->written;
2092                                         dev->written = NULL;
2093                                         while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
2094                                                 wbi2 = r5_next_bio(wbi, dev->sector);
2095                                                 if (--wbi->bi_phys_segments == 0) {
2096                                                         md_write_end(conf->mddev);
2097                                                         wbi->bi_next = return_bi;
2098                                                         return_bi = wbi;
2099                                                 }
2100                                                 wbi = wbi2;
2101                                         }
2102                                         if (dev->towrite == NULL)
2103                                                 bitmap_end = 1;
2104                                         spin_unlock_irq(&conf->device_lock);
2105                                         if (bitmap_end)
2106                                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2107                                                                 STRIPE_SECTORS,
2108                                                                 !test_bit(STRIPE_DEGRADED, &sh->state), 0);
2109                                 }
2110                         }
2111         }
2112
2113         /* Now we might consider reading some blocks, either to check/generate
2114          * parity, or to satisfy requests
2115          * or to load a block that is being partially written.
2116          */
2117         if (to_read || non_overwrite || (to_write && failed) ||
2118             (syncing && (uptodate < disks)) || expanding) {
2119                 for (i=disks; i--;) {
2120                         dev = &sh->dev[i];
2121                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
2122                             (dev->toread ||
2123                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2124                              syncing ||
2125                              expanding ||
2126                              (failed >= 1 && (sh->dev[failed_num[0]].toread || to_write)) ||
2127                              (failed >= 2 && (sh->dev[failed_num[1]].toread || to_write))
2128                                     )
2129                                 ) {
2130                                 /* we would like to get this block, possibly
2131                                  * by computing it, but we might not be able to
2132                                  */
2133                                 if (uptodate == disks-1) {
2134                                         PRINTK("Computing stripe %llu block %d\n",
2135                                                (unsigned long long)sh->sector, i);
2136                                         compute_block_1(sh, i, 0);
2137                                         uptodate++;
2138                                 } else if ( uptodate == disks-2 && failed >= 2 ) {
2139                                         /* Computing 2-failure is *very* expensive; only do it if failed >= 2 */
2140                                         int other;
2141                                         for (other=disks; other--;) {
2142                                                 if ( other == i )
2143                                                         continue;
2144                                                 if ( !test_bit(R5_UPTODATE, &sh->dev[other].flags) )
2145                                                         break;
2146                                         }
2147                                         BUG_ON(other < 0);
2148                                         PRINTK("Computing stripe %llu blocks %d,%d\n",
2149                                                (unsigned long long)sh->sector, i, other);
2150                                         compute_block_2(sh, i, other);
2151                                         uptodate += 2;
2152                                 } else if (test_bit(R5_Insync, &dev->flags)) {
2153                                         set_bit(R5_LOCKED, &dev->flags);
2154                                         set_bit(R5_Wantread, &dev->flags);
2155                                         locked++;
2156                                         PRINTK("Reading block %d (sync=%d)\n",
2157                                                 i, syncing);
2158                                 }
2159                         }
2160                 }
2161                 set_bit(STRIPE_HANDLE, &sh->state);
2162         }
2163
2164         /* now to consider writing and what else, if anything should be read */
2165         if (to_write) {
2166                 int rcw=0, must_compute=0;
2167                 for (i=disks ; i--;) {
2168                         dev = &sh->dev[i];
2169                         /* Would I have to read this buffer for reconstruct_write */
2170                         if (!test_bit(R5_OVERWRITE, &dev->flags)
2171                             && i != pd_idx && i != qd_idx
2172                             && (!test_bit(R5_LOCKED, &dev->flags)
2173                                     ) &&
2174                             !test_bit(R5_UPTODATE, &dev->flags)) {
2175                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
2176                                 else {
2177                                         PRINTK("raid6: must_compute: disk %d flags=%#lx\n", i, dev->flags);
2178                                         must_compute++;
2179                                 }
2180                         }
2181                 }
2182                 PRINTK("for sector %llu, rcw=%d, must_compute=%d\n",
2183                        (unsigned long long)sh->sector, rcw, must_compute);
2184                 set_bit(STRIPE_HANDLE, &sh->state);
2185
2186                 if (rcw > 0)
2187                         /* want reconstruct write, but need to get some data */
2188                         for (i=disks; i--;) {
2189                                 dev = &sh->dev[i];
2190                                 if (!test_bit(R5_OVERWRITE, &dev->flags)
2191                                     && !(failed == 0 && (i == pd_idx || i == qd_idx))
2192                                     && !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
2193                                     test_bit(R5_Insync, &dev->flags)) {
2194                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
2195                                         {
2196                                                 PRINTK("Read_old stripe %llu block %d for Reconstruct\n",
2197                                                        (unsigned long long)sh->sector, i);
2198                                                 set_bit(R5_LOCKED, &dev->flags);
2199                                                 set_bit(R5_Wantread, &dev->flags);
2200                                                 locked++;
2201                                         } else {
2202                                                 PRINTK("Request delayed stripe %llu block %d for Reconstruct\n",
2203                                                        (unsigned long long)sh->sector, i);
2204                                                 set_bit(STRIPE_DELAYED, &sh->state);
2205                                                 set_bit(STRIPE_HANDLE, &sh->state);
2206                                         }
2207                                 }
2208                         }
2209                 /* now if nothing is locked, and if we have enough data, we can start a write request */
2210                 if (locked == 0 && rcw == 0 &&
2211                     !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2212                         if ( must_compute > 0 ) {
2213                                 /* We have failed blocks and need to compute them */
2214                                 switch ( failed ) {
2215                                 case 0: BUG();
2216                                 case 1: compute_block_1(sh, failed_num[0], 0); break;
2217                                 case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break;
2218                                 default: BUG(); /* This request should have been failed? */
2219                                 }
2220                         }
2221
2222                         PRINTK("Computing parity for stripe %llu\n", (unsigned long long)sh->sector);
2223                         compute_parity6(sh, RECONSTRUCT_WRITE);
2224                         /* now every locked buffer is ready to be written */
2225                         for (i=disks; i--;)
2226                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2227                                         PRINTK("Writing stripe %llu block %d\n",
2228                                                (unsigned long long)sh->sector, i);
2229                                         locked++;
2230                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2231                                 }
2232                         /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2233                         set_bit(STRIPE_INSYNC, &sh->state);
2234
2235                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2236                                 atomic_dec(&conf->preread_active_stripes);
2237                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
2238                                         md_wakeup_thread(conf->mddev->thread);
2239                         }
2240                 }
2241         }
2242
2243         /* maybe we need to check and possibly fix the parity for this stripe
2244          * Any reads will already have been scheduled, so we just see if enough data
2245          * is available
2246          */
2247         if (syncing && locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state)) {
2248                 int update_p = 0, update_q = 0;
2249                 struct r5dev *dev;
2250
2251                 set_bit(STRIPE_HANDLE, &sh->state);
2252
2253                 BUG_ON(failed>2);
2254                 BUG_ON(uptodate < disks);
2255                 /* Want to check and possibly repair P and Q.
2256                  * However there could be one 'failed' device, in which
2257                  * case we can only check one of them, possibly using the
2258                  * other to generate missing data
2259                  */
2260
2261                 /* If !tmp_page, we cannot do the calculations,
2262                  * but as we have set STRIPE_HANDLE, we will soon be called
2263                  * by stripe_handle with a tmp_page - just wait until then.
2264                  */
2265                 if (tmp_page) {
2266                         if (failed == q_failed) {
2267                                 /* The only possible failed device holds 'Q', so it makes
2268                                  * sense to check P (If anything else were failed, we would
2269                                  * have used P to recreate it).
2270                                  */
2271                                 compute_block_1(sh, pd_idx, 1);
2272                                 if (!page_is_zero(sh->dev[pd_idx].page)) {
2273                                         compute_block_1(sh,pd_idx,0);
2274                                         update_p = 1;
2275                                 }
2276                         }
2277                         if (!q_failed && failed < 2) {
2278                                 /* q is not failed, and we didn't use it to generate
2279                                  * anything, so it makes sense to check it
2280                                  */
2281                                 memcpy(page_address(tmp_page),
2282                                        page_address(sh->dev[qd_idx].page),
2283                                        STRIPE_SIZE);
2284                                 compute_parity6(sh, UPDATE_PARITY);
2285                                 if (memcmp(page_address(tmp_page),
2286                                            page_address(sh->dev[qd_idx].page),
2287                                            STRIPE_SIZE)!= 0) {
2288                                         clear_bit(STRIPE_INSYNC, &sh->state);
2289                                         update_q = 1;
2290                                 }
2291                         }
2292                         if (update_p || update_q) {
2293                                 conf->mddev->resync_mismatches += STRIPE_SECTORS;
2294                                 if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2295                                         /* don't try to repair!! */
2296                                         update_p = update_q = 0;
2297                         }
2298
2299                         /* now write out any block on a failed drive,
2300                          * or P or Q if they need it
2301                          */
2302
2303                         if (failed == 2) {
2304                                 dev = &sh->dev[failed_num[1]];
2305                                 locked++;
2306                                 set_bit(R5_LOCKED, &dev->flags);
2307                                 set_bit(R5_Wantwrite, &dev->flags);
2308                         }
2309                         if (failed >= 1) {
2310                                 dev = &sh->dev[failed_num[0]];
2311                                 locked++;
2312                                 set_bit(R5_LOCKED, &dev->flags);
2313                                 set_bit(R5_Wantwrite, &dev->flags);
2314                         }
2315
2316                         if (update_p) {
2317                                 dev = &sh->dev[pd_idx];
2318                                 locked ++;
2319                                 set_bit(R5_LOCKED, &dev->flags);
2320                                 set_bit(R5_Wantwrite, &dev->flags);
2321                         }
2322                         if (update_q) {
2323                                 dev = &sh->dev[qd_idx];
2324                                 locked++;
2325                                 set_bit(R5_LOCKED, &dev->flags);
2326                                 set_bit(R5_Wantwrite, &dev->flags);
2327                         }
2328                         clear_bit(STRIPE_DEGRADED, &sh->state);
2329
2330                         set_bit(STRIPE_INSYNC, &sh->state);
2331                 }
2332         }
2333
2334         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2335                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2336                 clear_bit(STRIPE_SYNCING, &sh->state);
2337         }
2338
2339         /* If the failed drives are just a ReadError, then we might need
2340          * to progress the repair/check process
2341          */
2342         if (failed <= 2 && ! conf->mddev->ro)
2343                 for (i=0; i<failed;i++) {
2344                         dev = &sh->dev[failed_num[i]];
2345                         if (test_bit(R5_ReadError, &dev->flags)
2346                             && !test_bit(R5_LOCKED, &dev->flags)
2347                             && test_bit(R5_UPTODATE, &dev->flags)
2348                                 ) {
2349                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2350                                         set_bit(R5_Wantwrite, &dev->flags);
2351                                         set_bit(R5_ReWrite, &dev->flags);
2352                                         set_bit(R5_LOCKED, &dev->flags);
2353                                 } else {
2354                                         /* let's read it back */
2355                                         set_bit(R5_Wantread, &dev->flags);
2356                                         set_bit(R5_LOCKED, &dev->flags);
2357                                 }
2358                         }
2359                 }
2360
2361         if (expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
2362                 /* Need to write out all blocks after computing P&Q */
2363                 sh->disks = conf->raid_disks;
2364                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2365                                              conf->raid_disks);
2366                 compute_parity6(sh, RECONSTRUCT_WRITE);
2367                 for (i = conf->raid_disks ; i-- ;  ) {
2368                         set_bit(R5_LOCKED, &sh->dev[i].flags);
2369                         locked++;
2370                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2371                 }
2372                 clear_bit(STRIPE_EXPANDING, &sh->state);
2373         } else if (expanded) {
2374                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
2375                 atomic_dec(&conf->reshape_stripes);
2376                 wake_up(&conf->wait_for_overlap);
2377                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2378         }
2379
2380         if (expanding && locked == 0) {
2381                 /* We have read all the blocks in this stripe and now we need to
2382                  * copy some of them into a target stripe for expand.
2383                  */
2384                 clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2385                 for (i = 0; i < sh->disks ; i++)
2386                         if (i != pd_idx && i != qd_idx) {
2387                                 int dd_idx2, pd_idx2, j;
2388                                 struct stripe_head *sh2;
2389
2390                                 sector_t bn = compute_blocknr(sh, i);
2391                                 sector_t s = raid5_compute_sector(
2392                                         bn, conf->raid_disks,
2393                                         conf->raid_disks - conf->max_degraded,
2394                                         &dd_idx2, &pd_idx2, conf);
2395                                 sh2 = get_active_stripe(conf, s,
2396                                                         conf->raid_disks,
2397                                                        pd_idx2, 1);
2398                                 if (sh2 == NULL)
2399                                         /* so for only the early blocks of
2400                                          * this stripe have been requests.
2401                                          * When later blocks get requests, we
2402                                          * will try again
2403                                          */
2404                                         continue;
2405                                 if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2406                                     test_bit(R5_Expanded,
2407                                              &sh2->dev[dd_idx2].flags)) {
2408                                         /* must have already done this block */
2409                                         release_stripe(sh2);
2410                                         continue;
2411                                 }
2412                                 memcpy(page_address(sh2->dev[dd_idx2].page),
2413                                        page_address(sh->dev[i].page),
2414                                        STRIPE_SIZE);
2415                                 set_bit(R5_Expanded, &sh2->dev[dd_idx2].flags);
2416                                 set_bit(R5_UPTODATE, &sh2->dev[dd_idx2].flags);
2417                                 for (j = 0 ; j < conf->raid_disks ; j++)
2418                                         if (j != sh2->pd_idx &&
2419                                             j != raid6_next_disk(sh2->pd_idx,
2420                                                            sh2->disks) &&
2421                                             !test_bit(R5_Expanded,
2422                                                       &sh2->dev[j].flags))
2423                                                 break;
2424                                 if (j == conf->raid_disks) {
2425                                         set_bit(STRIPE_EXPAND_READY,
2426                                                 &sh2->state);
2427                                         set_bit(STRIPE_HANDLE, &sh2->state);
2428                                 }
2429                                 release_stripe(sh2);
2430                         }
2431         }
2432
2433         spin_unlock(&sh->lock);
2434
2435         while ((bi=return_bi)) {
2436                 int bytes = bi->bi_size;
2437
2438                 return_bi = bi->bi_next;
2439                 bi->bi_next = NULL;
2440                 bi->bi_size = 0;
2441                 bi->bi_end_io(bi, bytes,
2442                               test_bit(BIO_UPTODATE, &bi->bi_flags)
2443                                 ? 0 : -EIO);
2444         }
2445         for (i=disks; i-- ;) {
2446                 int rw;
2447                 struct bio *bi;
2448                 mdk_rdev_t *rdev;
2449                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
2450                         rw = WRITE;
2451                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
2452                         rw = READ;
2453                 else
2454                         continue;
2455
2456                 bi = &sh->dev[i].req;
2457
2458                 bi->bi_rw = rw;
2459                 if (rw == WRITE)
2460                         bi->bi_end_io = raid5_end_write_request;
2461                 else
2462                         bi->bi_end_io = raid5_end_read_request;
2463
2464                 rcu_read_lock();
2465                 rdev = rcu_dereference(conf->disks[i].rdev);
2466                 if (rdev && test_bit(Faulty, &rdev->flags))
2467                         rdev = NULL;
2468                 if (rdev)
2469                         atomic_inc(&rdev->nr_pending);
2470                 rcu_read_unlock();
2471
2472                 if (rdev) {
2473                         if (syncing || expanding || expanded)
2474                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
2475
2476                         bi->bi_bdev = rdev->bdev;
2477                         PRINTK("for %llu schedule op %ld on disc %d\n",
2478                                 (unsigned long long)sh->sector, bi->bi_rw, i);
2479                         atomic_inc(&sh->count);
2480                         bi->bi_sector = sh->sector + rdev->data_offset;
2481                         bi->bi_flags = 1 << BIO_UPTODATE;
2482                         bi->bi_vcnt = 1;
2483                         bi->bi_max_vecs = 1;
2484                         bi->bi_idx = 0;
2485                         bi->bi_io_vec = &sh->dev[i].vec;
2486                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
2487                         bi->bi_io_vec[0].bv_offset = 0;
2488                         bi->bi_size = STRIPE_SIZE;
2489                         bi->bi_next = NULL;
2490                         if (rw == WRITE &&
2491                             test_bit(R5_ReWrite, &sh->dev[i].flags))
2492                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2493                         generic_make_request(bi);
2494                 } else {
2495                         if (rw == WRITE)
2496                                 set_bit(STRIPE_DEGRADED, &sh->state);
2497                         PRINTK("skip op %ld on disc %d for sector %llu\n",
2498                                 bi->bi_rw, i, (unsigned long long)sh->sector);
2499                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2500                         set_bit(STRIPE_HANDLE, &sh->state);
2501                 }
2502         }
2503 }
2504
2505 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
2506 {
2507         if (sh->raid_conf->level == 6)
2508                 handle_stripe6(sh, tmp_page);
2509         else
2510                 handle_stripe5(sh);
2511 }
2512
2513
2514
2515 static void raid5_activate_delayed(raid5_conf_t *conf)
2516 {
2517         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
2518                 while (!list_empty(&conf->delayed_list)) {
2519                         struct list_head *l = conf->delayed_list.next;
2520                         struct stripe_head *sh;
2521                         sh = list_entry(l, struct stripe_head, lru);
2522                         list_del_init(l);
2523                         clear_bit(STRIPE_DELAYED, &sh->state);
2524                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
2525                                 atomic_inc(&conf->preread_active_stripes);
2526                         list_add_tail(&sh->lru, &conf->handle_list);
2527                 }
2528         }
2529 }
2530
2531 static void activate_bit_delay(raid5_conf_t *conf)
2532 {
2533         /* device_lock is held */
2534         struct list_head head;
2535         list_add(&head, &conf->bitmap_list);
2536         list_del_init(&conf->bitmap_list);
2537         while (!list_empty(&head)) {
2538                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
2539                 list_del_init(&sh->lru);
2540                 atomic_inc(&sh->count);
2541                 __release_stripe(conf, sh);
2542         }
2543 }
2544
2545 static void unplug_slaves(mddev_t *mddev)
2546 {
2547         raid5_conf_t *conf = mddev_to_conf(mddev);
2548         int i;
2549
2550         rcu_read_lock();
2551         for (i=0; i<mddev->raid_disks; i++) {
2552                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
2553                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
2554                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
2555
2556                         atomic_inc(&rdev->nr_pending);
2557                         rcu_read_unlock();
2558
2559                         if (r_queue->unplug_fn)
2560                                 r_queue->unplug_fn(r_queue);
2561
2562                         rdev_dec_pending(rdev, mddev);
2563                         rcu_read_lock();
2564                 }
2565         }
2566         rcu_read_unlock();
2567 }
2568
2569 static void raid5_unplug_device(request_queue_t *q)
2570 {
2571         mddev_t *mddev = q->queuedata;
2572         raid5_conf_t *conf = mddev_to_conf(mddev);
2573         unsigned long flags;
2574
2575         spin_lock_irqsave(&conf->device_lock, flags);
2576
2577         if (blk_remove_plug(q)) {
2578                 conf->seq_flush++;
2579                 raid5_activate_delayed(conf);
2580         }
2581         md_wakeup_thread(mddev->thread);
2582
2583         spin_unlock_irqrestore(&conf->device_lock, flags);
2584
2585         unplug_slaves(mddev);
2586 }
2587
2588 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
2589                              sector_t *error_sector)
2590 {
2591         mddev_t *mddev = q->queuedata;
2592         raid5_conf_t *conf = mddev_to_conf(mddev);
2593         int i, ret = 0;
2594
2595         rcu_read_lock();
2596         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
2597                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
2598                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
2599                         struct block_device *bdev = rdev->bdev;
2600                         request_queue_t *r_queue = bdev_get_queue(bdev);
2601
2602                         if (!r_queue->issue_flush_fn)
2603                                 ret = -EOPNOTSUPP;
2604                         else {
2605                                 atomic_inc(&rdev->nr_pending);
2606                                 rcu_read_unlock();
2607                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
2608                                                               error_sector);
2609                                 rdev_dec_pending(rdev, mddev);
2610                                 rcu_read_lock();
2611                         }
2612                 }
2613         }
2614         rcu_read_unlock();
2615         return ret;
2616 }
2617
2618 static int raid5_congested(void *data, int bits)
2619 {
2620         mddev_t *mddev = data;
2621         raid5_conf_t *conf = mddev_to_conf(mddev);
2622
2623         /* No difference between reads and writes.  Just check
2624          * how busy the stripe_cache is
2625          */
2626         if (conf->inactive_blocked)
2627                 return 1;
2628         if (conf->quiesce)
2629                 return 1;
2630         if (list_empty_careful(&conf->inactive_list))
2631                 return 1;
2632
2633         return 0;
2634 }
2635
2636 /* We want read requests to align with chunks where possible,
2637  * but write requests don't need to.
2638  */
2639 static int raid5_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
2640 {
2641         mddev_t *mddev = q->queuedata;
2642         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
2643         int max;
2644         unsigned int chunk_sectors = mddev->chunk_size >> 9;
2645         unsigned int bio_sectors = bio->bi_size >> 9;
2646
2647         if (bio_data_dir(bio) == WRITE)
2648                 return biovec->bv_len; /* always allow writes to be mergeable */
2649
2650         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
2651         if (max < 0) max = 0;
2652         if (max <= biovec->bv_len && bio_sectors == 0)
2653                 return biovec->bv_len;
2654         else
2655                 return max;
2656 }
2657
2658
2659 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
2660 {
2661         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
2662         unsigned int chunk_sectors = mddev->chunk_size >> 9;
2663         unsigned int bio_sectors = bio->bi_size >> 9;
2664
2665         return  chunk_sectors >=
2666                 ((sector & (chunk_sectors - 1)) + bio_sectors);
2667 }
2668
2669 /*
2670  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
2671  *  later sampled by raid5d.
2672  */
2673 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
2674 {
2675         unsigned long flags;
2676
2677         spin_lock_irqsave(&conf->device_lock, flags);
2678
2679         bi->bi_next = conf->retry_read_aligned_list;
2680         conf->retry_read_aligned_list = bi;
2681
2682         spin_unlock_irqrestore(&conf->device_lock, flags);
2683         md_wakeup_thread(conf->mddev->thread);
2684 }
2685
2686
2687 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
2688 {
2689         struct bio *bi;
2690
2691         bi = conf->retry_read_aligned;
2692         if (bi) {
2693                 conf->retry_read_aligned = NULL;
2694                 return bi;
2695         }
2696         bi = conf->retry_read_aligned_list;
2697         if(bi) {
2698                 conf->retry_read_aligned_list = bi->bi_next;
2699                 bi->bi_next = NULL;
2700                 bi->bi_phys_segments = 1; /* biased count of active stripes */
2701                 bi->bi_hw_segments = 0; /* count of processed stripes */
2702         }
2703
2704         return bi;
2705 }
2706
2707
2708 /*
2709  *  The "raid5_align_endio" should check if the read succeeded and if it
2710  *  did, call bio_endio on the original bio (having bio_put the new bio
2711  *  first).
2712  *  If the read failed..
2713  */
2714 static int raid5_align_endio(struct bio *bi, unsigned int bytes, int error)
2715 {
2716         struct bio* raid_bi  = bi->bi_private;
2717         mddev_t *mddev;
2718         raid5_conf_t *conf;
2719         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2720         mdk_rdev_t *rdev;
2721
2722         if (bi->bi_size)
2723                 return 1;
2724         bio_put(bi);
2725
2726         mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
2727         conf = mddev_to_conf(mddev);
2728         rdev = (void*)raid_bi->bi_next;
2729         raid_bi->bi_next = NULL;
2730
2731         rdev_dec_pending(rdev, conf->mddev);
2732
2733         if (!error && uptodate) {
2734                 bio_endio(raid_bi, bytes, 0);
2735                 if (atomic_dec_and_test(&conf->active_aligned_reads))
2736                         wake_up(&conf->wait_for_stripe);
2737                 return 0;
2738         }
2739
2740
2741         PRINTK("raid5_align_endio : io error...handing IO for a retry\n");
2742
2743         add_bio_to_retry(raid_bi, conf);
2744         return 0;
2745 }
2746
2747 static int bio_fits_rdev(struct bio *bi)
2748 {
2749         request_queue_t *q = bdev_get_queue(bi->bi_bdev);
2750
2751         if ((bi->bi_size>>9) > q->max_sectors)
2752                 return 0;
2753         blk_recount_segments(q, bi);
2754         if (bi->bi_phys_segments > q->max_phys_segments ||
2755             bi->bi_hw_segments > q->max_hw_segments)
2756                 return 0;
2757
2758         if (q->merge_bvec_fn)
2759                 /* it's too hard to apply the merge_bvec_fn at this stage,
2760                  * just just give up
2761                  */
2762                 return 0;
2763
2764         return 1;
2765 }
2766
2767
2768 static int chunk_aligned_read(request_queue_t *q, struct bio * raid_bio)
2769 {
2770         mddev_t *mddev = q->queuedata;
2771         raid5_conf_t *conf = mddev_to_conf(mddev);
2772         const unsigned int raid_disks = conf->raid_disks;
2773         const unsigned int data_disks = raid_disks - conf->max_degraded;
2774         unsigned int dd_idx, pd_idx;
2775         struct bio* align_bi;
2776         mdk_rdev_t *rdev;
2777
2778         if (!in_chunk_boundary(mddev, raid_bio)) {
2779                 PRINTK("chunk_aligned_read : non aligned\n");
2780                 return 0;
2781         }
2782         /*
2783          * use bio_clone to make a copy of the bio
2784          */
2785         align_bi = bio_clone(raid_bio, GFP_NOIO);
2786         if (!align_bi)
2787                 return 0;
2788         /*
2789          *   set bi_end_io to a new function, and set bi_private to the
2790          *     original bio.
2791          */
2792         align_bi->bi_end_io  = raid5_align_endio;
2793         align_bi->bi_private = raid_bio;
2794         /*
2795          *      compute position
2796          */
2797         align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
2798                                         raid_disks,
2799                                         data_disks,
2800                                         &dd_idx,
2801                                         &pd_idx,
2802                                         conf);
2803
2804         rcu_read_lock();
2805         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
2806         if (rdev && test_bit(In_sync, &rdev->flags)) {
2807                 atomic_inc(&rdev->nr_pending);
2808                 rcu_read_unlock();
2809                 raid_bio->bi_next = (void*)rdev;
2810                 align_bi->bi_bdev =  rdev->bdev;
2811                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
2812                 align_bi->bi_sector += rdev->data_offset;
2813
2814                 if (!bio_fits_rdev(align_bi)) {
2815                         /* too big in some way */
2816                         bio_put(align_bi);
2817                         rdev_dec_pending(rdev, mddev);
2818                         return 0;
2819                 }
2820
2821                 spin_lock_irq(&conf->device_lock);
2822                 wait_event_lock_irq(conf->wait_for_stripe,
2823                                     conf->quiesce == 0,
2824                                     conf->device_lock, /* nothing */);
2825                 atomic_inc(&conf->active_aligned_reads);
2826                 spin_unlock_irq(&conf->device_lock);
2827
2828                 generic_make_request(align_bi);
2829                 return 1;
2830         } else {
2831                 rcu_read_unlock();
2832                 bio_put(align_bi);
2833                 return 0;
2834         }
2835 }
2836
2837
2838 static int make_request(request_queue_t *q, struct bio * bi)
2839 {
2840         mddev_t *mddev = q->queuedata;
2841         raid5_conf_t *conf = mddev_to_conf(mddev);
2842         unsigned int dd_idx, pd_idx;
2843         sector_t new_sector;
2844         sector_t logical_sector, last_sector;
2845         struct stripe_head *sh;
2846         const int rw = bio_data_dir(bi);
2847         int remaining;
2848
2849         if (unlikely(bio_barrier(bi))) {
2850                 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
2851                 return 0;
2852         }
2853
2854         md_write_start(mddev, bi);
2855
2856         disk_stat_inc(mddev->gendisk, ios[rw]);
2857         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
2858
2859         if (rw == READ &&
2860              mddev->reshape_position == MaxSector &&
2861              chunk_aligned_read(q,bi))
2862                 return 0;
2863
2864         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
2865         last_sector = bi->bi_sector + (bi->bi_size>>9);
2866         bi->bi_next = NULL;
2867         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
2868
2869         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
2870                 DEFINE_WAIT(w);
2871                 int disks, data_disks;
2872
2873         retry:
2874                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
2875                 if (likely(conf->expand_progress == MaxSector))
2876                         disks = conf->raid_disks;
2877                 else {
2878                         /* spinlock is needed as expand_progress may be
2879                          * 64bit on a 32bit platform, and so it might be
2880                          * possible to see a half-updated value
2881                          * Ofcourse expand_progress could change after
2882                          * the lock is dropped, so once we get a reference
2883                          * to the stripe that we think it is, we will have
2884                          * to check again.
2885                          */
2886                         spin_lock_irq(&conf->device_lock);
2887                         disks = conf->raid_disks;
2888                         if (logical_sector >= conf->expand_progress)
2889                                 disks = conf->previous_raid_disks;
2890                         else {
2891                                 if (logical_sector >= conf->expand_lo) {
2892                                         spin_unlock_irq(&conf->device_lock);
2893                                         schedule();
2894                                         goto retry;
2895                                 }
2896                         }
2897                         spin_unlock_irq(&conf->device_lock);
2898                 }
2899                 data_disks = disks - conf->max_degraded;
2900
2901                 new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
2902                                                   &dd_idx, &pd_idx, conf);
2903                 PRINTK("raid5: make_request, sector %llu logical %llu\n",
2904                         (unsigned long long)new_sector, 
2905                         (unsigned long long)logical_sector);
2906
2907                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
2908                 if (sh) {
2909                         if (unlikely(conf->expand_progress != MaxSector)) {
2910                                 /* expansion might have moved on while waiting for a
2911                                  * stripe, so we must do the range check again.
2912                                  * Expansion could still move past after this
2913                                  * test, but as we are holding a reference to
2914                                  * 'sh', we know that if that happens,
2915                                  *  STRIPE_EXPANDING will get set and the expansion
2916                                  * won't proceed until we finish with the stripe.
2917                                  */
2918                                 int must_retry = 0;
2919                                 spin_lock_irq(&conf->device_lock);
2920                                 if (logical_sector <  conf->expand_progress &&
2921                                     disks == conf->previous_raid_disks)
2922                                         /* mismatch, need to try again */
2923                                         must_retry = 1;
2924                                 spin_unlock_irq(&conf->device_lock);
2925                                 if (must_retry) {
2926                                         release_stripe(sh);
2927                                         goto retry;
2928                                 }
2929                         }
2930                         /* FIXME what if we get a false positive because these
2931                          * are being updated.
2932                          */
2933                         if (logical_sector >= mddev->suspend_lo &&
2934                             logical_sector < mddev->suspend_hi) {
2935                                 release_stripe(sh);
2936                                 schedule();
2937                                 goto retry;
2938                         }
2939
2940                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
2941                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
2942                                 /* Stripe is busy expanding or
2943                                  * add failed due to overlap.  Flush everything
2944                                  * and wait a while
2945                                  */
2946                                 raid5_unplug_device(mddev->queue);
2947                                 release_stripe(sh);
2948                                 schedule();
2949                                 goto retry;
2950                         }
2951                         finish_wait(&conf->wait_for_overlap, &w);
2952                         handle_stripe(sh, NULL);
2953                         release_stripe(sh);
2954                 } else {
2955                         /* cannot get stripe for read-ahead, just give-up */
2956                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2957                         finish_wait(&conf->wait_for_overlap, &w);
2958                         break;
2959                 }
2960                         
2961         }
2962         spin_lock_irq(&conf->device_lock);
2963         remaining = --bi->bi_phys_segments;
2964         spin_unlock_irq(&conf->device_lock);
2965         if (remaining == 0) {
2966                 int bytes = bi->bi_size;
2967
2968                 if ( rw == WRITE )
2969                         md_write_end(mddev);
2970                 bi->bi_size = 0;
2971                 bi->bi_end_io(bi, bytes,
2972                               test_bit(BIO_UPTODATE, &bi->bi_flags)
2973                                 ? 0 : -EIO);
2974         }
2975         return 0;
2976 }
2977
2978 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
2979 {
2980         /* reshaping is quite different to recovery/resync so it is
2981          * handled quite separately ... here.
2982          *
2983          * On each call to sync_request, we gather one chunk worth of
2984          * destination stripes and flag them as expanding.
2985          * Then we find all the source stripes and request reads.
2986          * As the reads complete, handle_stripe will copy the data
2987          * into the destination stripe and release that stripe.
2988          */
2989         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
2990         struct stripe_head *sh;
2991         int pd_idx;
2992         sector_t first_sector, last_sector;
2993         int raid_disks = conf->previous_raid_disks;
2994         int data_disks = raid_disks - conf->max_degraded;
2995         int new_data_disks = conf->raid_disks - conf->max_degraded;
2996         int i;
2997         int dd_idx;
2998         sector_t writepos, safepos, gap;
2999
3000         if (sector_nr == 0 &&
3001             conf->expand_progress != 0) {
3002                 /* restarting in the middle, skip the initial sectors */
3003                 sector_nr = conf->expand_progress;
3004                 sector_div(sector_nr, new_data_disks);
3005                 *skipped = 1;
3006                 return sector_nr;
3007         }
3008
3009         /* we update the metadata when there is more than 3Meg
3010          * in the block range (that is rather arbitrary, should
3011          * probably be time based) or when the data about to be
3012          * copied would over-write the source of the data at
3013          * the front of the range.
3014          * i.e. one new_stripe forward from expand_progress new_maps
3015          * to after where expand_lo old_maps to
3016          */
3017         writepos = conf->expand_progress +
3018                 conf->chunk_size/512*(new_data_disks);
3019         sector_div(writepos, new_data_disks);
3020         safepos = conf->expand_lo;
3021         sector_div(safepos, data_disks);
3022         gap = conf->expand_progress - conf->expand_lo;
3023
3024         if (writepos >= safepos ||
3025             gap > (new_data_disks)*3000*2 /*3Meg*/) {
3026                 /* Cannot proceed until we've updated the superblock... */
3027                 wait_event(conf->wait_for_overlap,
3028                            atomic_read(&conf->reshape_stripes)==0);
3029                 mddev->reshape_position = conf->expand_progress;
3030                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3031                 md_wakeup_thread(mddev->thread);
3032                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
3033                            kthread_should_stop());
3034                 spin_lock_irq(&conf->device_lock);
3035                 conf->expand_lo = mddev->reshape_position;
3036                 spin_unlock_irq(&conf->device_lock);
3037                 wake_up(&conf->wait_for_overlap);
3038         }
3039
3040         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
3041                 int j;
3042                 int skipped = 0;
3043                 pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
3044                 sh = get_active_stripe(conf, sector_nr+i,
3045                                        conf->raid_disks, pd_idx, 0);
3046                 set_bit(STRIPE_EXPANDING, &sh->state);
3047                 atomic_inc(&conf->reshape_stripes);
3048                 /* If any of this stripe is beyond the end of the old
3049                  * array, then we need to zero those blocks
3050                  */
3051                 for (j=sh->disks; j--;) {
3052                         sector_t s;
3053                         if (j == sh->pd_idx)
3054                                 continue;
3055                         if (conf->level == 6 &&
3056                             j == raid6_next_disk(sh->pd_idx, sh->disks))
3057                                 continue;
3058                         s = compute_blocknr(sh, j);
3059                         if (s < (mddev->array_size<<1)) {
3060                                 skipped = 1;
3061                                 continue;
3062                         }
3063                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
3064                         set_bit(R5_Expanded, &sh->dev[j].flags);
3065                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
3066                 }
3067                 if (!skipped) {
3068                         set_bit(STRIPE_EXPAND_READY, &sh->state);
3069                         set_bit(STRIPE_HANDLE, &sh->state);
3070                 }
3071                 release_stripe(sh);
3072         }
3073         spin_lock_irq(&conf->device_lock);
3074         conf->expand_progress = (sector_nr + i)*(conf->raid_disks-1);
3075         spin_unlock_irq(&conf->device_lock);
3076         /* Ok, those stripe are ready. We can start scheduling
3077          * reads on the source stripes.
3078          * The source stripes are determined by mapping the first and last
3079          * block on the destination stripes.
3080          */
3081         first_sector =
3082                 raid5_compute_sector(sector_nr*(new_data_disks),
3083                                      raid_disks, data_disks,
3084                                      &dd_idx, &pd_idx, conf);
3085         last_sector =
3086                 raid5_compute_sector((sector_nr+conf->chunk_size/512)
3087                                      *(new_data_disks) -1,
3088                                      raid_disks, data_disks,
3089                                      &dd_idx, &pd_idx, conf);
3090         if (last_sector >= (mddev->size<<1))
3091                 last_sector = (mddev->size<<1)-1;
3092         while (first_sector <= last_sector) {
3093                 pd_idx = stripe_to_pdidx(first_sector, conf,
3094                                          conf->previous_raid_disks);
3095                 sh = get_active_stripe(conf, first_sector,
3096                                        conf->previous_raid_disks, pd_idx, 0);
3097                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3098                 set_bit(STRIPE_HANDLE, &sh->state);
3099                 release_stripe(sh);
3100                 first_sector += STRIPE_SECTORS;
3101         }
3102         return conf->chunk_size>>9;
3103 }
3104
3105 /* FIXME go_faster isn't used */
3106 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
3107 {
3108         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3109         struct stripe_head *sh;
3110         int pd_idx;
3111         int raid_disks = conf->raid_disks;
3112         sector_t max_sector = mddev->size << 1;
3113         int sync_blocks;
3114         int still_degraded = 0;
3115         int i;
3116
3117         if (sector_nr >= max_sector) {
3118                 /* just being told to finish up .. nothing much to do */
3119                 unplug_slaves(mddev);
3120                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
3121                         end_reshape(conf);
3122                         return 0;
3123                 }
3124
3125                 if (mddev->curr_resync < max_sector) /* aborted */
3126                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
3127                                         &sync_blocks, 1);
3128                 else /* completed sync */
3129                         conf->fullsync = 0;
3130                 bitmap_close_sync(mddev->bitmap);
3131
3132                 return 0;
3133         }
3134
3135         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3136                 return reshape_request(mddev, sector_nr, skipped);
3137
3138         /* if there is too many failed drives and we are trying
3139          * to resync, then assert that we are finished, because there is
3140          * nothing we can do.
3141          */
3142         if (mddev->degraded >= conf->max_degraded &&
3143             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3144                 sector_t rv = (mddev->size << 1) - sector_nr;
3145                 *skipped = 1;
3146                 return rv;
3147         }
3148         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
3149             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
3150             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
3151                 /* we can skip this block, and probably more */
3152                 sync_blocks /= STRIPE_SECTORS;
3153                 *skipped = 1;
3154                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
3155         }
3156
3157         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
3158         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
3159         if (sh == NULL) {
3160                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
3161                 /* make sure we don't swamp the stripe cache if someone else
3162                  * is trying to get access
3163                  */
3164                 schedule_timeout_uninterruptible(1);
3165         }
3166         /* Need to check if array will still be degraded after recovery/resync
3167          * We don't need to check the 'failed' flag as when that gets set,
3168          * recovery aborts.
3169          */
3170         for (i=0; i<mddev->raid_disks; i++)
3171                 if (conf->disks[i].rdev == NULL)
3172                         still_degraded = 1;
3173
3174         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
3175
3176         spin_lock(&sh->lock);
3177         set_bit(STRIPE_SYNCING, &sh->state);
3178         clear_bit(STRIPE_INSYNC, &sh->state);
3179         spin_unlock(&sh->lock);
3180
3181         handle_stripe(sh, NULL);
3182         release_stripe(sh);
3183
3184         return STRIPE_SECTORS;
3185 }
3186
3187 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
3188 {
3189         /* We may not be able to submit a whole bio at once as there
3190          * may not be enough stripe_heads available.
3191          * We cannot pre-allocate enough stripe_heads as we may need
3192          * more than exist in the cache (if we allow ever large chunks).
3193          * So we do one stripe head at a time and record in
3194          * ->bi_hw_segments how many have been done.
3195          *
3196          * We *know* that this entire raid_bio is in one chunk, so
3197          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
3198          */
3199         struct stripe_head *sh;
3200         int dd_idx, pd_idx;
3201         sector_t sector, logical_sector, last_sector;
3202         int scnt = 0;
3203         int remaining;
3204         int handled = 0;
3205
3206         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3207         sector = raid5_compute_sector(  logical_sector,
3208                                         conf->raid_disks,
3209                                         conf->raid_disks - conf->max_degraded,
3210                                         &dd_idx,
3211                                         &pd_idx,
3212                                         conf);
3213         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
3214
3215         for (; logical_sector < last_sector;
3216              logical_sector += STRIPE_SECTORS,
3217                      sector += STRIPE_SECTORS,
3218                      scnt++) {
3219
3220                 if (scnt < raid_bio->bi_hw_segments)
3221                         /* already done this stripe */
3222                         continue;
3223
3224                 sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
3225
3226                 if (!sh) {
3227                         /* failed to get a stripe - must wait */
3228                         raid_bio->bi_hw_segments = scnt;
3229                         conf->retry_read_aligned = raid_bio;
3230                         return handled;
3231                 }
3232
3233                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
3234                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
3235                         release_stripe(sh);
3236                         raid_bio->bi_hw_segments = scnt;
3237                         conf->retry_read_aligned = raid_bio;
3238                         return handled;
3239                 }
3240
3241                 handle_stripe(sh, NULL);
3242                 release_stripe(sh);
3243                 handled++;
3244         }
3245         spin_lock_irq(&conf->device_lock);
3246         remaining = --raid_bio->bi_phys_segments;
3247         spin_unlock_irq(&conf->device_lock);
3248         if (remaining == 0) {
3249                 int bytes = raid_bio->bi_size;
3250
3251                 raid_bio->bi_size = 0;
3252                 raid_bio->bi_end_io(raid_bio, bytes,
3253                               test_bit(BIO_UPTODATE, &raid_bio->bi_flags)
3254                                 ? 0 : -EIO);
3255         }
3256         if (atomic_dec_and_test(&conf->active_aligned_reads))
3257                 wake_up(&conf->wait_for_stripe);
3258         return handled;
3259 }
3260
3261
3262
3263 /*
3264  * This is our raid5 kernel thread.
3265  *
3266  * We scan the hash table for stripes which can be handled now.
3267  * During the scan, completed stripes are saved for us by the interrupt
3268  * handler, so that they will not have to wait for our next wakeup.
3269  */
3270 static void raid5d (mddev_t *mddev)
3271 {
3272         struct stripe_head *sh;
3273         raid5_conf_t *conf = mddev_to_conf(mddev);
3274         int handled;
3275
3276         PRINTK("+++ raid5d active\n");
3277
3278         md_check_recovery(mddev);
3279
3280         handled = 0;
3281         spin_lock_irq(&conf->device_lock);
3282         while (1) {
3283                 struct list_head *first;
3284                 struct bio *bio;
3285
3286                 if (conf->seq_flush != conf->seq_write) {
3287                         int seq = conf->seq_flush;
3288                         spin_unlock_irq(&conf->device_lock);
3289                         bitmap_unplug(mddev->bitmap);
3290                         spin_lock_irq(&conf->device_lock);
3291                         conf->seq_write = seq;
3292                         activate_bit_delay(conf);
3293                 }
3294
3295                 if (list_empty(&conf->handle_list) &&
3296                     atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
3297                     !blk_queue_plugged(mddev->queue) &&
3298                     !list_empty(&conf->delayed_list))
3299                         raid5_activate_delayed(conf);
3300
3301                 while ((bio = remove_bio_from_retry(conf))) {
3302                         int ok;
3303                         spin_unlock_irq(&conf->device_lock);
3304                         ok = retry_aligned_read(conf, bio);
3305                         spin_lock_irq(&conf->device_lock);
3306                         if (!ok)
3307                                 break;
3308                         handled++;
3309                 }
3310
3311                 if (list_empty(&conf->handle_list))
3312                         break;
3313
3314                 first = conf->handle_list.next;
3315                 sh = list_entry(first, struct stripe_head, lru);
3316
3317                 list_del_init(first);
3318                 atomic_inc(&sh->count);
3319                 BUG_ON(atomic_read(&sh->count)!= 1);
3320                 spin_unlock_irq(&conf->device_lock);
3321                 
3322                 handled++;
3323                 handle_stripe(sh, conf->spare_page);
3324                 release_stripe(sh);
3325
3326                 spin_lock_irq(&conf->device_lock);
3327         }
3328         PRINTK("%d stripes handled\n", handled);
3329
3330         spin_unlock_irq(&conf->device_lock);
3331
3332         unplug_slaves(mddev);
3333
3334         PRINTK("--- raid5d inactive\n");
3335 }
3336
3337 static ssize_t
3338 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
3339 {
3340         raid5_conf_t *conf = mddev_to_conf(mddev);
3341         if (conf)
3342                 return sprintf(page, "%d\n", conf->max_nr_stripes);
3343         else
3344                 return 0;
3345 }
3346
3347 static ssize_t
3348 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
3349 {
3350         raid5_conf_t *conf = mddev_to_conf(mddev);
3351         char *end;
3352         int new;
3353         if (len >= PAGE_SIZE)
3354                 return -EINVAL;
3355         if (!conf)
3356                 return -ENODEV;
3357
3358         new = simple_strtoul(page, &end, 10);
3359         if (!*page || (*end && *end != '\n') )
3360                 return -EINVAL;
3361         if (new <= 16 || new > 32768)
3362                 return -EINVAL;
3363         while (new < conf->max_nr_stripes) {
3364                 if (drop_one_stripe(conf))
3365                         conf->max_nr_stripes--;
3366                 else
3367                         break;
3368         }
3369         md_allow_write(mddev);
3370         while (new > conf->max_nr_stripes) {
3371                 if (grow_one_stripe(conf))
3372                         conf->max_nr_stripes++;
3373                 else break;
3374         }
3375         return len;
3376 }
3377
3378 static struct md_sysfs_entry
3379 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
3380                                 raid5_show_stripe_cache_size,
3381                                 raid5_store_stripe_cache_size);
3382
3383 static ssize_t
3384 stripe_cache_active_show(mddev_t *mddev, char *page)
3385 {
3386         raid5_conf_t *conf = mddev_to_conf(mddev);
3387         if (conf)
3388                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
3389         else
3390                 return 0;
3391 }
3392
3393 static struct md_sysfs_entry
3394 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
3395
3396 static struct attribute *raid5_attrs[] =  {
3397         &raid5_stripecache_size.attr,
3398         &raid5_stripecache_active.attr,
3399         NULL,
3400 };
3401 static struct attribute_group raid5_attrs_group = {
3402         .name = NULL,
3403         .attrs = raid5_attrs,
3404 };
3405
3406 static int run(mddev_t *mddev)
3407 {
3408         raid5_conf_t *conf;
3409         int raid_disk, memory;
3410         mdk_rdev_t *rdev;
3411         struct disk_info *disk;
3412         struct list_head *tmp;
3413         int working_disks = 0;
3414
3415         if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
3416                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
3417                        mdname(mddev), mddev->level);
3418                 return -EIO;
3419         }
3420
3421         if (mddev->reshape_position != MaxSector) {
3422                 /* Check that we can continue the reshape.
3423                  * Currently only disks can change, it must
3424                  * increase, and we must be past the point where
3425                  * a stripe over-writes itself
3426                  */
3427                 sector_t here_new, here_old;
3428                 int old_disks;
3429                 int max_degraded = (mddev->level == 5 ? 1 : 2);
3430
3431                 if (mddev->new_level != mddev->level ||
3432                     mddev->new_layout != mddev->layout ||
3433                     mddev->new_chunk != mddev->chunk_size) {
3434                         printk(KERN_ERR "raid5: %s: unsupported reshape "
3435                                "required - aborting.\n",
3436                                mdname(mddev));
3437                         return -EINVAL;
3438                 }
3439                 if (mddev->delta_disks <= 0) {
3440                         printk(KERN_ERR "raid5: %s: unsupported reshape "
3441                                "(reduce disks) required - aborting.\n",
3442                                mdname(mddev));
3443                         return -EINVAL;
3444                 }
3445                 old_disks = mddev->raid_disks - mddev->delta_disks;
3446                 /* reshape_position must be on a new-stripe boundary, and one
3447                  * further up in new geometry must map after here in old
3448                  * geometry.
3449                  */
3450                 here_new = mddev->reshape_position;
3451                 if (sector_div(here_new, (mddev->chunk_size>>9)*
3452                                (mddev->raid_disks - max_degraded))) {
3453                         printk(KERN_ERR "raid5: reshape_position not "
3454                                "on a stripe boundary\n");
3455                         return -EINVAL;
3456                 }
3457                 /* here_new is the stripe we will write to */
3458                 here_old = mddev->reshape_position;
3459                 sector_div(here_old, (mddev->chunk_size>>9)*
3460                            (old_disks-max_degraded));
3461                 /* here_old is the first stripe that we might need to read
3462                  * from */
3463                 if (here_new >= here_old) {
3464                         /* Reading from the same stripe as writing to - bad */
3465                         printk(KERN_ERR "raid5: reshape_position too early for "
3466                                "auto-recovery - aborting.\n");
3467                         return -EINVAL;
3468                 }
3469                 printk(KERN_INFO "raid5: reshape will continue\n");
3470                 /* OK, we should be able to continue; */
3471         }
3472
3473
3474         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
3475         if ((conf = mddev->private) == NULL)
3476                 goto abort;
3477         if (mddev->reshape_position == MaxSector) {
3478                 conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
3479         } else {
3480                 conf->raid_disks = mddev->raid_disks;
3481                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
3482         }
3483
3484         conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
3485                               GFP_KERNEL);
3486         if (!conf->disks)
3487                 goto abort;
3488
3489         conf->mddev = mddev;
3490
3491         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
3492                 goto abort;
3493
3494         if (mddev->level == 6) {
3495                 conf->spare_page = alloc_page(GFP_KERNEL);
3496                 if (!conf->spare_page)
3497                         goto abort;
3498         }
3499         spin_lock_init(&conf->device_lock);
3500         init_waitqueue_head(&conf->wait_for_stripe);
3501         init_waitqueue_head(&conf->wait_for_overlap);
3502         INIT_LIST_HEAD(&conf->handle_list);
3503         INIT_LIST_HEAD(&conf->delayed_list);
3504         INIT_LIST_HEAD(&conf->bitmap_list);
3505         INIT_LIST_HEAD(&conf->inactive_list);
3506         atomic_set(&conf->active_stripes, 0);
3507         atomic_set(&conf->preread_active_stripes, 0);
3508         atomic_set(&conf->active_aligned_reads, 0);
3509
3510         PRINTK("raid5: run(%s) called.\n", mdname(mddev));
3511
3512         ITERATE_RDEV(mddev,rdev,tmp) {
3513                 raid_disk = rdev->raid_disk;
3514                 if (raid_disk >= conf->raid_disks
3515                     || raid_disk < 0)
3516                         continue;
3517                 disk = conf->disks + raid_disk;
3518
3519                 disk->rdev = rdev;
3520
3521                 if (test_bit(In_sync, &rdev->flags)) {
3522                         char b[BDEVNAME_SIZE];
3523                         printk(KERN_INFO "raid5: device %s operational as raid"
3524                                 " disk %d\n", bdevname(rdev->bdev,b),
3525                                 raid_disk);
3526                         working_disks++;
3527                 }
3528         }
3529
3530         /*
3531          * 0 for a fully functional array, 1 or 2 for a degraded array.
3532          */
3533         mddev->degraded = conf->raid_disks - working_disks;
3534         conf->mddev = mddev;
3535         conf->chunk_size = mddev->chunk_size;
3536         conf->level = mddev->level;
3537         if (conf->level == 6)
3538                 conf->max_degraded = 2;
3539         else
3540                 conf->max_degraded = 1;
3541         conf->algorithm = mddev->layout;
3542         conf->max_nr_stripes = NR_STRIPES;
3543         conf->expand_progress = mddev->reshape_position;
3544
3545         /* device size must be a multiple of chunk size */
3546         mddev->size &= ~(mddev->chunk_size/1024 -1);
3547         mddev->resync_max_sectors = mddev->size << 1;
3548
3549         if (conf->level == 6 && conf->raid_disks < 4) {
3550                 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
3551                        mdname(mddev), conf->raid_disks);
3552                 goto abort;
3553         }
3554         if (!conf->chunk_size || conf->chunk_size % 4) {
3555                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
3556                         conf->chunk_size, mdname(mddev));
3557                 goto abort;
3558         }
3559         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
3560                 printk(KERN_ERR 
3561                         "raid5: unsupported parity algorithm %d for %s\n",
3562                         conf->algorithm, mdname(mddev));
3563                 goto abort;
3564         }
3565         if (mddev->degraded > conf->max_degraded) {
3566                 printk(KERN_ERR "raid5: not enough operational devices for %s"
3567                         " (%d/%d failed)\n",
3568                         mdname(mddev), mddev->degraded, conf->raid_disks);
3569                 goto abort;
3570         }
3571
3572         if (mddev->degraded > 0 &&
3573             mddev->recovery_cp != MaxSector) {
3574                 if (mddev->ok_start_degraded)
3575                         printk(KERN_WARNING
3576                                "raid5: starting dirty degraded array: %s"
3577                                "- data corruption possible.\n",
3578                                mdname(mddev));
3579                 else {
3580                         printk(KERN_ERR
3581                                "raid5: cannot start dirty degraded array for %s\n",
3582                                mdname(mddev));
3583                         goto abort;
3584                 }
3585         }
3586
3587         {
3588                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
3589                 if (!mddev->thread) {
3590                         printk(KERN_ERR 
3591                                 "raid5: couldn't allocate thread for %s\n",
3592                                 mdname(mddev));
3593                         goto abort;
3594                 }
3595         }
3596         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
3597                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
3598         if (grow_stripes(conf, conf->max_nr_stripes)) {
3599                 printk(KERN_ERR 
3600                         "raid5: couldn't allocate %dkB for buffers\n", memory);
3601                 shrink_stripes(conf);
3602                 md_unregister_thread(mddev->thread);
3603                 goto abort;
3604         } else
3605                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
3606                         memory, mdname(mddev));
3607
3608         if (mddev->degraded == 0)
3609                 printk("raid5: raid level %d set %s active with %d out of %d"
3610                         " devices, algorithm %d\n", conf->level, mdname(mddev), 
3611                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
3612                         conf->algorithm);
3613         else
3614                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
3615                         " out of %d devices, algorithm %d\n", conf->level,
3616                         mdname(mddev), mddev->raid_disks - mddev->degraded,
3617                         mddev->raid_disks, conf->algorithm);
3618
3619         print_raid5_conf(conf);
3620
3621         if (conf->expand_progress != MaxSector) {
3622                 printk("...ok start reshape thread\n");
3623                 conf->expand_lo = conf->expand_progress;
3624                 atomic_set(&conf->reshape_stripes, 0);
3625                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3626                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3627                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3628                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3629                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3630                                                         "%s_reshape");
3631         }
3632
3633         /* read-ahead size must cover two whole stripes, which is
3634          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
3635          */
3636         {
3637                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
3638                 int stripe = data_disks *
3639                         (mddev->chunk_size / PAGE_SIZE);
3640                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3641                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3642         }
3643
3644         /* Ok, everything is just fine now */
3645         sysfs_create_group(&mddev->kobj, &raid5_attrs_group);
3646
3647         mddev->queue->unplug_fn = raid5_unplug_device;
3648         mddev->queue->issue_flush_fn = raid5_issue_flush;
3649         mddev->queue->backing_dev_info.congested_fn = raid5_congested;
3650         mddev->queue->backing_dev_info.congested_data = mddev;
3651
3652         mddev->array_size =  mddev->size * (conf->previous_raid_disks -
3653                                             conf->max_degraded);
3654
3655         blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
3656
3657         return 0;
3658 abort:
3659         if (conf) {
3660                 print_raid5_conf(conf);
3661                 safe_put_page(conf->spare_page);
3662                 kfree(conf->disks);
3663                 kfree(conf->stripe_hashtbl);
3664                 kfree(conf);
3665         }
3666         mddev->private = NULL;
3667         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
3668         return -EIO;
3669 }
3670
3671
3672
3673 static int stop(mddev_t *mddev)
3674 {
3675         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3676
3677         md_unregister_thread(mddev->thread);
3678         mddev->thread = NULL;
3679         shrink_stripes(conf);
3680         kfree(conf->stripe_hashtbl);
3681         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
3682         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
3683         kfree(conf->disks);
3684         kfree(conf);
3685         mddev->private = NULL;
3686         return 0;
3687 }
3688
3689 #if RAID5_DEBUG
3690 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
3691 {
3692         int i;
3693
3694         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
3695                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
3696         seq_printf(seq, "sh %llu,  count %d.\n",
3697                    (unsigned long long)sh->sector, atomic_read(&sh->count));
3698         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
3699         for (i = 0; i < sh->disks; i++) {
3700                 seq_printf(seq, "(cache%d: %p %ld) ",
3701                            i, sh->dev[i].page, sh->dev[i].flags);
3702         }
3703         seq_printf(seq, "\n");
3704 }
3705
3706 static void printall (struct seq_file *seq, raid5_conf_t *conf)
3707 {
3708         struct stripe_head *sh;
3709         struct hlist_node *hn;
3710         int i;
3711
3712         spin_lock_irq(&conf->device_lock);
3713         for (i = 0; i < NR_HASH; i++) {
3714                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
3715                         if (sh->raid_conf != conf)
3716                                 continue;
3717                         print_sh(seq, sh);
3718                 }
3719         }
3720         spin_unlock_irq(&conf->device_lock);
3721 }
3722 #endif
3723
3724 static void status (struct seq_file *seq, mddev_t *mddev)
3725 {
3726         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3727         int i;
3728
3729         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
3730         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
3731         for (i = 0; i < conf->raid_disks; i++)
3732                 seq_printf (seq, "%s",
3733                                conf->disks[i].rdev &&
3734                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
3735         seq_printf (seq, "]");
3736 #if RAID5_DEBUG
3737         seq_printf (seq, "\n");
3738         printall(seq, conf);
3739 #endif
3740 }
3741
3742 static void print_raid5_conf (raid5_conf_t *conf)
3743 {
3744         int i;
3745         struct disk_info *tmp;
3746
3747         printk("RAID5 conf printout:\n");
3748         if (!conf) {
3749                 printk("(conf==NULL)\n");
3750                 return;
3751         }
3752         printk(" --- rd:%d wd:%d\n", conf->raid_disks,
3753                  conf->raid_disks - conf->mddev->degraded);
3754
3755         for (i = 0; i < conf->raid_disks; i++) {
3756                 char b[BDEVNAME_SIZE];
3757                 tmp = conf->disks + i;
3758                 if (tmp->rdev)
3759                 printk(" disk %d, o:%d, dev:%s\n",
3760                         i, !test_bit(Faulty, &tmp->rdev->flags),
3761                         bdevname(tmp->rdev->bdev,b));
3762         }
3763 }
3764
3765 static int raid5_spare_active(mddev_t *mddev)
3766 {
3767         int i;
3768         raid5_conf_t *conf = mddev->private;
3769         struct disk_info *tmp;
3770
3771         for (i = 0; i < conf->raid_disks; i++) {
3772                 tmp = conf->disks + i;
3773                 if (tmp->rdev
3774                     && !test_bit(Faulty, &tmp->rdev->flags)
3775                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
3776                         unsigned long flags;
3777                         spin_lock_irqsave(&conf->device_lock, flags);
3778                         mddev->degraded--;
3779                         spin_unlock_irqrestore(&conf->device_lock, flags);
3780                 }
3781         }
3782         print_raid5_conf(conf);
3783         return 0;
3784 }
3785
3786 static int raid5_remove_disk(mddev_t *mddev, int number)
3787 {
3788         raid5_conf_t *conf = mddev->private;
3789         int err = 0;
3790         mdk_rdev_t *rdev;
3791         struct disk_info *p = conf->disks + number;
3792
3793         print_raid5_conf(conf);
3794         rdev = p->rdev;
3795         if (rdev) {
3796                 if (test_bit(In_sync, &rdev->flags) ||
3797                     atomic_read(&rdev->nr_pending)) {
3798                         err = -EBUSY;
3799                         goto abort;
3800                 }
3801                 p->rdev = NULL;
3802                 synchronize_rcu();
3803                 if (atomic_read(&rdev->nr_pending)) {
3804                         /* lost the race, try later */
3805                         err = -EBUSY;
3806                         p->rdev = rdev;
3807                 }
3808         }
3809 abort:
3810
3811         print_raid5_conf(conf);
3812         return err;
3813 }
3814
3815 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
3816 {
3817         raid5_conf_t *conf = mddev->private;
3818         int found = 0;
3819         int disk;
3820         struct disk_info *p;
3821
3822         if (mddev->degraded > conf->max_degraded)
3823                 /* no point adding a device */
3824                 return 0;
3825
3826         /*
3827          * find the disk ... but prefer rdev->saved_raid_disk
3828          * if possible.
3829          */
3830         if (rdev->saved_raid_disk >= 0 &&
3831             conf->disks[rdev->saved_raid_disk].rdev == NULL)
3832                 disk = rdev->saved_raid_disk;
3833         else
3834                 disk = 0;
3835         for ( ; disk < conf->raid_disks; disk++)
3836                 if ((p=conf->disks + disk)->rdev == NULL) {
3837                         clear_bit(In_sync, &rdev->flags);
3838                         rdev->raid_disk = disk;
3839                         found = 1;
3840                         if (rdev->saved_raid_disk != disk)
3841                                 conf->fullsync = 1;
3842                         rcu_assign_pointer(p->rdev, rdev);
3843                         break;
3844                 }
3845         print_raid5_conf(conf);
3846         return found;
3847 }
3848
3849 static int raid5_resize(mddev_t *mddev, sector_t sectors)
3850 {
3851         /* no resync is happening, and there is enough space
3852          * on all devices, so we can resize.
3853          * We need to make sure resync covers any new space.
3854          * If the array is shrinking we should possibly wait until
3855          * any io in the removed space completes, but it hardly seems
3856          * worth it.
3857          */
3858         raid5_conf_t *conf = mddev_to_conf(mddev);
3859
3860         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
3861         mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
3862         set_capacity(mddev->gendisk, mddev->array_size << 1);
3863         mddev->changed = 1;
3864         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
3865                 mddev->recovery_cp = mddev->size << 1;
3866                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3867         }
3868         mddev->size = sectors /2;
3869         mddev->resync_max_sectors = sectors;
3870         return 0;
3871 }
3872
3873 #ifdef CONFIG_MD_RAID5_RESHAPE
3874 static int raid5_check_reshape(mddev_t *mddev)
3875 {
3876         raid5_conf_t *conf = mddev_to_conf(mddev);
3877         int err;
3878
3879         if (mddev->delta_disks < 0 ||
3880             mddev->new_level != mddev->level)
3881                 return -EINVAL; /* Cannot shrink array or change level yet */
3882         if (mddev->delta_disks == 0)
3883                 return 0; /* nothing to do */
3884
3885         /* Can only proceed if there are plenty of stripe_heads.
3886          * We need a minimum of one full stripe,, and for sensible progress
3887          * it is best to have about 4 times that.
3888          * If we require 4 times, then the default 256 4K stripe_heads will
3889          * allow for chunk sizes up to 256K, which is probably OK.
3890          * If the chunk size is greater, user-space should request more
3891          * stripe_heads first.
3892          */
3893         if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
3894             (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
3895                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
3896                        (mddev->chunk_size / STRIPE_SIZE)*4);
3897                 return -ENOSPC;
3898         }
3899
3900         err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
3901         if (err)
3902                 return err;
3903
3904         if (mddev->degraded > conf->max_degraded)
3905                 return -EINVAL;
3906         /* looks like we might be able to manage this */
3907         return 0;
3908 }
3909
3910 static int raid5_start_reshape(mddev_t *mddev)
3911 {
3912         raid5_conf_t *conf = mddev_to_conf(mddev);
3913         mdk_rdev_t *rdev;
3914         struct list_head *rtmp;
3915         int spares = 0;
3916         int added_devices = 0;
3917         unsigned long flags;
3918
3919         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
3920                 return -EBUSY;
3921
3922         ITERATE_RDEV(mddev, rdev, rtmp)
3923                 if (rdev->raid_disk < 0 &&
3924                     !test_bit(Faulty, &rdev->flags))
3925                         spares++;
3926
3927         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
3928                 /* Not enough devices even to make a degraded array
3929                  * of that size
3930                  */
3931                 return -EINVAL;
3932
3933         atomic_set(&conf->reshape_stripes, 0);
3934         spin_lock_irq(&conf->device_lock);
3935         conf->previous_raid_disks = conf->raid_disks;
3936         conf->raid_disks += mddev->delta_disks;
3937         conf->expand_progress = 0;
3938         conf->expand_lo = 0;
3939         spin_unlock_irq(&conf->device_lock);
3940
3941         /* Add some new drives, as many as will fit.
3942          * We know there are enough to make the newly sized array work.
3943          */
3944         ITERATE_RDEV(mddev, rdev, rtmp)
3945                 if (rdev->raid_disk < 0 &&
3946                     !test_bit(Faulty, &rdev->flags)) {
3947                         if (raid5_add_disk(mddev, rdev)) {
3948                                 char nm[20];
3949                                 set_bit(In_sync, &rdev->flags);
3950                                 added_devices++;
3951                                 rdev->recovery_offset = 0;
3952                                 sprintf(nm, "rd%d", rdev->raid_disk);
3953                                 sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
3954                         } else
3955                                 break;
3956                 }
3957
3958         spin_lock_irqsave(&conf->device_lock, flags);
3959         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
3960         spin_unlock_irqrestore(&conf->device_lock, flags);
3961         mddev->raid_disks = conf->raid_disks;
3962         mddev->reshape_position = 0;
3963         set_bit(MD_CHANGE_DEVS, &mddev->flags);
3964
3965         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3966         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3967         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3968         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3969         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3970                                                 "%s_reshape");
3971         if (!mddev->sync_thread) {
3972                 mddev->recovery = 0;
3973                 spin_lock_irq(&conf->device_lock);
3974                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
3975                 conf->expand_progress = MaxSector;
3976                 spin_unlock_irq(&conf->device_lock);
3977                 return -EAGAIN;
3978         }
3979         md_wakeup_thread(mddev->sync_thread);
3980         md_new_event(mddev);
3981         return 0;
3982 }
3983 #endif
3984
3985 static void end_reshape(raid5_conf_t *conf)
3986 {
3987         struct block_device *bdev;
3988
3989         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
3990                 conf->mddev->array_size = conf->mddev->size *
3991                         (conf->raid_disks - conf->max_degraded);
3992                 set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
3993                 conf->mddev->changed = 1;
3994
3995                 bdev = bdget_disk(conf->mddev->gendisk, 0);
3996                 if (bdev) {
3997                         mutex_lock(&bdev->bd_inode->i_mutex);
3998                         i_size_write(bdev->bd_inode, (loff_t)conf->mddev->array_size << 10);
3999                         mutex_unlock(&bdev->bd_inode->i_mutex);
4000                         bdput(bdev);
4001                 }
4002                 spin_lock_irq(&conf->device_lock);
4003                 conf->expand_progress = MaxSector;
4004                 spin_unlock_irq(&conf->device_lock);
4005                 conf->mddev->reshape_position = MaxSector;
4006
4007                 /* read-ahead size must cover two whole stripes, which is
4008                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4009                  */
4010                 {
4011                         int data_disks = conf->previous_raid_disks - conf->max_degraded;
4012                         int stripe = data_disks *
4013                                 (conf->mddev->chunk_size / PAGE_SIZE);
4014                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4015                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4016                 }
4017         }
4018 }
4019
4020 static void raid5_quiesce(mddev_t *mddev, int state)
4021 {
4022         raid5_conf_t *conf = mddev_to_conf(mddev);
4023
4024         switch(state) {
4025         case 2: /* resume for a suspend */
4026                 wake_up(&conf->wait_for_overlap);
4027                 break;
4028
4029         case 1: /* stop all writes */
4030                 spin_lock_irq(&conf->device_lock);
4031                 conf->quiesce = 1;
4032                 wait_event_lock_irq(conf->wait_for_stripe,
4033                                     atomic_read(&conf->active_stripes) == 0 &&
4034                                     atomic_read(&conf->active_aligned_reads) == 0,
4035                                     conf->device_lock, /* nothing */);
4036                 spin_unlock_irq(&conf->device_lock);
4037                 break;
4038
4039         case 0: /* re-enable writes */
4040                 spin_lock_irq(&conf->device_lock);
4041                 conf->quiesce = 0;
4042                 wake_up(&conf->wait_for_stripe);
4043                 wake_up(&conf->wait_for_overlap);
4044                 spin_unlock_irq(&conf->device_lock);
4045                 break;
4046         }
4047 }
4048
4049 static struct mdk_personality raid6_personality =
4050 {
4051         .name           = "raid6",
4052         .level          = 6,
4053         .owner          = THIS_MODULE,
4054         .make_request   = make_request,
4055         .run            = run,
4056         .stop           = stop,
4057         .status         = status,
4058         .error_handler  = error,
4059         .hot_add_disk   = raid5_add_disk,
4060         .hot_remove_disk= raid5_remove_disk,
4061         .spare_active   = raid5_spare_active,
4062         .sync_request   = sync_request,
4063         .resize         = raid5_resize,
4064 #ifdef CONFIG_MD_RAID5_RESHAPE
4065         .check_reshape  = raid5_check_reshape,
4066         .start_reshape  = raid5_start_reshape,
4067 #endif
4068         .quiesce        = raid5_quiesce,
4069 };
4070 static struct mdk_personality raid5_personality =
4071 {
4072         .name           = "raid5",
4073         .level          = 5,
4074         .owner          = THIS_MODULE,
4075         .make_request   = make_request,
4076         .run            = run,
4077         .stop           = stop,
4078         .status         = status,
4079         .error_handler  = error,
4080         .hot_add_disk   = raid5_add_disk,
4081         .hot_remove_disk= raid5_remove_disk,
4082         .spare_active   = raid5_spare_active,
4083         .sync_request   = sync_request,
4084         .resize         = raid5_resize,
4085 #ifdef CONFIG_MD_RAID5_RESHAPE
4086         .check_reshape  = raid5_check_reshape,
4087         .start_reshape  = raid5_start_reshape,
4088 #endif
4089         .quiesce        = raid5_quiesce,
4090 };
4091
4092 static struct mdk_personality raid4_personality =
4093 {
4094         .name           = "raid4",
4095         .level          = 4,
4096         .owner          = THIS_MODULE,
4097         .make_request   = make_request,
4098         .run            = run,
4099         .stop           = stop,
4100         .status         = status,
4101         .error_handler  = error,
4102         .hot_add_disk   = raid5_add_disk,
4103         .hot_remove_disk= raid5_remove_disk,
4104         .spare_active   = raid5_spare_active,
4105         .sync_request   = sync_request,
4106         .resize         = raid5_resize,
4107         .quiesce        = raid5_quiesce,
4108 };
4109
4110 static int __init raid5_init(void)
4111 {
4112         int e;
4113
4114         e = raid6_select_algo();
4115         if ( e )
4116                 return e;
4117         register_md_personality(&raid6_personality);
4118         register_md_personality(&raid5_personality);
4119         register_md_personality(&raid4_personality);
4120         return 0;
4121 }
4122
4123 static void raid5_exit(void)
4124 {
4125         unregister_md_personality(&raid6_personality);
4126         unregister_md_personality(&raid5_personality);
4127         unregister_md_personality(&raid4_personality);
4128 }
4129
4130 module_init(raid5_init);
4131 module_exit(raid5_exit);
4132 MODULE_LICENSE("GPL");
4133 MODULE_ALIAS("md-personality-4"); /* RAID5 */
4134 MODULE_ALIAS("md-raid5");
4135 MODULE_ALIAS("md-raid4");
4136 MODULE_ALIAS("md-level-5");
4137 MODULE_ALIAS("md-level-4");
4138 MODULE_ALIAS("md-personality-8"); /* RAID6 */
4139 MODULE_ALIAS("md-raid6");
4140 MODULE_ALIAS("md-level-6");
4141
4142 /* This used to be two separate modules, they were: */
4143 MODULE_ALIAS("raid5");
4144 MODULE_ALIAS("raid6");