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