md: fix an occasional deadlock in raid5
[linux-2.6.git] / drivers / md / raid5.c
1 /*
2  * raid5.c : Multiple Devices driver for Linux
3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4  *         Copyright (C) 1999, 2000 Ingo Molnar
5  *         Copyright (C) 2002, 2003 H. Peter Anvin
6  *
7  * RAID-4/5/6 management functions.
8  * Thanks to Penguin Computing for making the RAID-6 development possible
9  * by donating a test server!
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20
21 /*
22  * BITMAP UNPLUGGING:
23  *
24  * The sequencing for updating the bitmap reliably is a little
25  * subtle (and I got it wrong the first time) so it deserves some
26  * explanation.
27  *
28  * We group bitmap updates into batches.  Each batch has a number.
29  * We may write out several batches at once, but that isn't very important.
30  * conf->bm_write is the number of the last batch successfully written.
31  * conf->bm_flush is the number of the last batch that was closed to
32  *    new additions.
33  * When we discover that we will need to write to any block in a stripe
34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35  * the number of the batch it will be in. This is bm_flush+1.
36  * When we are ready to do a write, if that batch hasn't been written yet,
37  *   we plug the array and queue the stripe for later.
38  * When an unplug happens, we increment bm_flush, thus closing the current
39  *   batch.
40  * When we notice that bm_flush > bm_write, we write out all pending updates
41  * to the bitmap, and advance bm_write to where bm_flush was.
42  * This may occasionally write a bit out twice, but is sure never to
43  * miss any bits.
44  */
45
46 #include <linux/module.h>
47 #include <linux/slab.h>
48 #include <linux/highmem.h>
49 #include <linux/bitops.h>
50 #include <linux/kthread.h>
51 #include <asm/atomic.h>
52 #include "raid6.h"
53
54 #include <linux/raid/bitmap.h>
55 #include <linux/async_tx.h>
56
57 /*
58  * Stripe cache
59  */
60
61 #define NR_STRIPES              256
62 #define STRIPE_SIZE             PAGE_SIZE
63 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
64 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
65 #define IO_THRESHOLD            1
66 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
67 #define HASH_MASK               (NR_HASH - 1)
68
69 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
70
71 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
72  * order without overlap.  There may be several bio's per stripe+device, and
73  * a bio could span several devices.
74  * When walking this list for a particular stripe+device, we must never proceed
75  * beyond a bio that extends past this device, as the next bio might no longer
76  * be valid.
77  * This macro is used to determine the 'next' bio in the list, given the sector
78  * of the current stripe+device
79  */
80 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
81 /*
82  * The following can be used to debug the driver
83  */
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 #ifdef DEBUG
92 #define inline
93 #define __inline__
94 #endif
95
96 #if !RAID6_USE_EMPTY_ZERO_PAGE
97 /* In .bss so it's zeroed */
98 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
99 #endif
100
101 static inline int raid6_next_disk(int disk, int raid_disks)
102 {
103         disk++;
104         return (disk < raid_disks) ? disk : 0;
105 }
106
107 static void return_io(struct bio *return_bi)
108 {
109         struct bio *bi = return_bi;
110         while (bi) {
111
112                 return_bi = bi->bi_next;
113                 bi->bi_next = NULL;
114                 bi->bi_size = 0;
115                 bi->bi_end_io(bi,
116                               test_bit(BIO_UPTODATE, &bi->bi_flags)
117                                 ? 0 : -EIO);
118                 bi = return_bi;
119         }
120 }
121
122 static void print_raid5_conf (raid5_conf_t *conf);
123
124 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
125 {
126         if (atomic_dec_and_test(&sh->count)) {
127                 BUG_ON(!list_empty(&sh->lru));
128                 BUG_ON(atomic_read(&conf->active_stripes)==0);
129                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
130                         if (test_bit(STRIPE_DELAYED, &sh->state)) {
131                                 list_add_tail(&sh->lru, &conf->delayed_list);
132                                 blk_plug_device(conf->mddev->queue);
133                         } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
134                                    sh->bm_seq - conf->seq_write > 0) {
135                                 list_add_tail(&sh->lru, &conf->bitmap_list);
136                                 blk_plug_device(conf->mddev->queue);
137                         } else {
138                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
139                                 list_add_tail(&sh->lru, &conf->handle_list);
140                         }
141                         md_wakeup_thread(conf->mddev->thread);
142                 } else {
143                         BUG_ON(sh->ops.pending);
144                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
145                                 atomic_dec(&conf->preread_active_stripes);
146                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
147                                         md_wakeup_thread(conf->mddev->thread);
148                         }
149                         atomic_dec(&conf->active_stripes);
150                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
151                                 list_add_tail(&sh->lru, &conf->inactive_list);
152                                 wake_up(&conf->wait_for_stripe);
153                                 if (conf->retry_read_aligned)
154                                         md_wakeup_thread(conf->mddev->thread);
155                         }
156                 }
157         }
158 }
159 static void release_stripe(struct stripe_head *sh)
160 {
161         raid5_conf_t *conf = sh->raid_conf;
162         unsigned long flags;
163
164         spin_lock_irqsave(&conf->device_lock, flags);
165         __release_stripe(conf, sh);
166         spin_unlock_irqrestore(&conf->device_lock, flags);
167 }
168
169 static inline void remove_hash(struct stripe_head *sh)
170 {
171         pr_debug("remove_hash(), stripe %llu\n",
172                 (unsigned long long)sh->sector);
173
174         hlist_del_init(&sh->hash);
175 }
176
177 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
178 {
179         struct hlist_head *hp = stripe_hash(conf, sh->sector);
180
181         pr_debug("insert_hash(), stripe %llu\n",
182                 (unsigned long long)sh->sector);
183
184         CHECK_DEVLOCK();
185         hlist_add_head(&sh->hash, hp);
186 }
187
188
189 /* find an idle stripe, make sure it is unhashed, and return it. */
190 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
191 {
192         struct stripe_head *sh = NULL;
193         struct list_head *first;
194
195         CHECK_DEVLOCK();
196         if (list_empty(&conf->inactive_list))
197                 goto out;
198         first = conf->inactive_list.next;
199         sh = list_entry(first, struct stripe_head, lru);
200         list_del_init(first);
201         remove_hash(sh);
202         atomic_inc(&conf->active_stripes);
203 out:
204         return sh;
205 }
206
207 static void shrink_buffers(struct stripe_head *sh, int num)
208 {
209         struct page *p;
210         int i;
211
212         for (i=0; i<num ; i++) {
213                 p = sh->dev[i].page;
214                 if (!p)
215                         continue;
216                 sh->dev[i].page = NULL;
217                 put_page(p);
218         }
219 }
220
221 static int grow_buffers(struct stripe_head *sh, int num)
222 {
223         int i;
224
225         for (i=0; i<num; i++) {
226                 struct page *page;
227
228                 if (!(page = alloc_page(GFP_KERNEL))) {
229                         return 1;
230                 }
231                 sh->dev[i].page = page;
232         }
233         return 0;
234 }
235
236 static void raid5_build_block (struct stripe_head *sh, int i);
237
238 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
239 {
240         raid5_conf_t *conf = sh->raid_conf;
241         int i;
242
243         BUG_ON(atomic_read(&sh->count) != 0);
244         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
245         BUG_ON(sh->ops.pending || sh->ops.ack || sh->ops.complete);
246
247         CHECK_DEVLOCK();
248         pr_debug("init_stripe called, stripe %llu\n",
249                 (unsigned long long)sh->sector);
250
251         remove_hash(sh);
252
253         sh->sector = sector;
254         sh->pd_idx = pd_idx;
255         sh->state = 0;
256
257         sh->disks = disks;
258
259         for (i = sh->disks; i--; ) {
260                 struct r5dev *dev = &sh->dev[i];
261
262                 if (dev->toread || dev->read || dev->towrite || dev->written ||
263                     test_bit(R5_LOCKED, &dev->flags)) {
264                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
265                                (unsigned long long)sh->sector, i, dev->toread,
266                                dev->read, dev->towrite, dev->written,
267                                test_bit(R5_LOCKED, &dev->flags));
268                         BUG();
269                 }
270                 dev->flags = 0;
271                 raid5_build_block(sh, i);
272         }
273         insert_hash(conf, sh);
274 }
275
276 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
277 {
278         struct stripe_head *sh;
279         struct hlist_node *hn;
280
281         CHECK_DEVLOCK();
282         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
283         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
284                 if (sh->sector == sector && sh->disks == disks)
285                         return sh;
286         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
287         return NULL;
288 }
289
290 static void unplug_slaves(mddev_t *mddev);
291 static void raid5_unplug_device(struct request_queue *q);
292
293 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
294                                              int pd_idx, int noblock)
295 {
296         struct stripe_head *sh;
297
298         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
299
300         spin_lock_irq(&conf->device_lock);
301
302         do {
303                 wait_event_lock_irq(conf->wait_for_stripe,
304                                     conf->quiesce == 0,
305                                     conf->device_lock, /* nothing */);
306                 sh = __find_stripe(conf, sector, disks);
307                 if (!sh) {
308                         if (!conf->inactive_blocked)
309                                 sh = get_free_stripe(conf);
310                         if (noblock && sh == NULL)
311                                 break;
312                         if (!sh) {
313                                 conf->inactive_blocked = 1;
314                                 wait_event_lock_irq(conf->wait_for_stripe,
315                                                     !list_empty(&conf->inactive_list) &&
316                                                     (atomic_read(&conf->active_stripes)
317                                                      < (conf->max_nr_stripes *3/4)
318                                                      || !conf->inactive_blocked),
319                                                     conf->device_lock,
320                                                     raid5_unplug_device(conf->mddev->queue)
321                                         );
322                                 conf->inactive_blocked = 0;
323                         } else
324                                 init_stripe(sh, sector, pd_idx, disks);
325                 } else {
326                         if (atomic_read(&sh->count)) {
327                           BUG_ON(!list_empty(&sh->lru));
328                         } else {
329                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
330                                         atomic_inc(&conf->active_stripes);
331                                 if (list_empty(&sh->lru) &&
332                                     !test_bit(STRIPE_EXPANDING, &sh->state))
333                                         BUG();
334                                 list_del_init(&sh->lru);
335                         }
336                 }
337         } while (sh == NULL);
338
339         if (sh)
340                 atomic_inc(&sh->count);
341
342         spin_unlock_irq(&conf->device_lock);
343         return sh;
344 }
345
346 /* test_and_ack_op() ensures that we only dequeue an operation once */
347 #define test_and_ack_op(op, pend) \
348 do {                                                    \
349         if (test_bit(op, &sh->ops.pending) &&           \
350                 !test_bit(op, &sh->ops.complete)) {     \
351                 if (test_and_set_bit(op, &sh->ops.ack)) \
352                         clear_bit(op, &pend);           \
353                 else                                    \
354                         ack++;                          \
355         } else                                          \
356                 clear_bit(op, &pend);                   \
357 } while (0)
358
359 /* find new work to run, do not resubmit work that is already
360  * in flight
361  */
362 static unsigned long get_stripe_work(struct stripe_head *sh)
363 {
364         unsigned long pending;
365         int ack = 0;
366
367         pending = sh->ops.pending;
368
369         test_and_ack_op(STRIPE_OP_BIOFILL, pending);
370         test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
371         test_and_ack_op(STRIPE_OP_PREXOR, pending);
372         test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
373         test_and_ack_op(STRIPE_OP_POSTXOR, pending);
374         test_and_ack_op(STRIPE_OP_CHECK, pending);
375         if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
376                 ack++;
377
378         sh->ops.count -= ack;
379         if (unlikely(sh->ops.count < 0)) {
380                 printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
381                         "ops.complete: %#lx\n", pending, sh->ops.pending,
382                         sh->ops.ack, sh->ops.complete);
383                 BUG();
384         }
385
386         return pending;
387 }
388
389 static void
390 raid5_end_read_request(struct bio *bi, int error);
391 static void
392 raid5_end_write_request(struct bio *bi, int error);
393
394 static void ops_run_io(struct stripe_head *sh)
395 {
396         raid5_conf_t *conf = sh->raid_conf;
397         int i, disks = sh->disks;
398
399         might_sleep();
400
401         for (i = disks; i--; ) {
402                 int rw;
403                 struct bio *bi;
404                 mdk_rdev_t *rdev;
405                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
406                         rw = WRITE;
407                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
408                         rw = READ;
409                 else
410                         continue;
411
412                 bi = &sh->dev[i].req;
413
414                 bi->bi_rw = rw;
415                 if (rw == WRITE)
416                         bi->bi_end_io = raid5_end_write_request;
417                 else
418                         bi->bi_end_io = raid5_end_read_request;
419
420                 rcu_read_lock();
421                 rdev = rcu_dereference(conf->disks[i].rdev);
422                 if (rdev && test_bit(Faulty, &rdev->flags))
423                         rdev = NULL;
424                 if (rdev)
425                         atomic_inc(&rdev->nr_pending);
426                 rcu_read_unlock();
427
428                 if (rdev) {
429                         if (test_bit(STRIPE_SYNCING, &sh->state) ||
430                                 test_bit(STRIPE_EXPAND_SOURCE, &sh->state) ||
431                                 test_bit(STRIPE_EXPAND_READY, &sh->state))
432                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
433
434                         bi->bi_bdev = rdev->bdev;
435                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
436                                 __FUNCTION__, (unsigned long long)sh->sector,
437                                 bi->bi_rw, i);
438                         atomic_inc(&sh->count);
439                         bi->bi_sector = sh->sector + rdev->data_offset;
440                         bi->bi_flags = 1 << BIO_UPTODATE;
441                         bi->bi_vcnt = 1;
442                         bi->bi_max_vecs = 1;
443                         bi->bi_idx = 0;
444                         bi->bi_io_vec = &sh->dev[i].vec;
445                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
446                         bi->bi_io_vec[0].bv_offset = 0;
447                         bi->bi_size = STRIPE_SIZE;
448                         bi->bi_next = NULL;
449                         if (rw == WRITE &&
450                             test_bit(R5_ReWrite, &sh->dev[i].flags))
451                                 atomic_add(STRIPE_SECTORS,
452                                         &rdev->corrected_errors);
453                         generic_make_request(bi);
454                 } else {
455                         if (rw == WRITE)
456                                 set_bit(STRIPE_DEGRADED, &sh->state);
457                         pr_debug("skip op %ld on disc %d for sector %llu\n",
458                                 bi->bi_rw, i, (unsigned long long)sh->sector);
459                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
460                         set_bit(STRIPE_HANDLE, &sh->state);
461                 }
462         }
463 }
464
465 static struct dma_async_tx_descriptor *
466 async_copy_data(int frombio, struct bio *bio, struct page *page,
467         sector_t sector, struct dma_async_tx_descriptor *tx)
468 {
469         struct bio_vec *bvl;
470         struct page *bio_page;
471         int i;
472         int page_offset;
473
474         if (bio->bi_sector >= sector)
475                 page_offset = (signed)(bio->bi_sector - sector) * 512;
476         else
477                 page_offset = (signed)(sector - bio->bi_sector) * -512;
478         bio_for_each_segment(bvl, bio, i) {
479                 int len = bio_iovec_idx(bio, i)->bv_len;
480                 int clen;
481                 int b_offset = 0;
482
483                 if (page_offset < 0) {
484                         b_offset = -page_offset;
485                         page_offset += b_offset;
486                         len -= b_offset;
487                 }
488
489                 if (len > 0 && page_offset + len > STRIPE_SIZE)
490                         clen = STRIPE_SIZE - page_offset;
491                 else
492                         clen = len;
493
494                 if (clen > 0) {
495                         b_offset += bio_iovec_idx(bio, i)->bv_offset;
496                         bio_page = bio_iovec_idx(bio, i)->bv_page;
497                         if (frombio)
498                                 tx = async_memcpy(page, bio_page, page_offset,
499                                         b_offset, clen,
500                                         ASYNC_TX_DEP_ACK,
501                                         tx, NULL, NULL);
502                         else
503                                 tx = async_memcpy(bio_page, page, b_offset,
504                                         page_offset, clen,
505                                         ASYNC_TX_DEP_ACK,
506                                         tx, NULL, NULL);
507                 }
508                 if (clen < len) /* hit end of page */
509                         break;
510                 page_offset +=  len;
511         }
512
513         return tx;
514 }
515
516 static void ops_complete_biofill(void *stripe_head_ref)
517 {
518         struct stripe_head *sh = stripe_head_ref;
519         struct bio *return_bi = NULL;
520         raid5_conf_t *conf = sh->raid_conf;
521         int i;
522
523         pr_debug("%s: stripe %llu\n", __FUNCTION__,
524                 (unsigned long long)sh->sector);
525
526         /* clear completed biofills */
527         for (i = sh->disks; i--; ) {
528                 struct r5dev *dev = &sh->dev[i];
529
530                 /* acknowledge completion of a biofill operation */
531                 /* and check if we need to reply to a read request,
532                  * new R5_Wantfill requests are held off until
533                  * !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending)
534                  */
535                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
536                         struct bio *rbi, *rbi2;
537
538                         /* The access to dev->read is outside of the
539                          * spin_lock_irq(&conf->device_lock), but is protected
540                          * by the STRIPE_OP_BIOFILL pending bit
541                          */
542                         BUG_ON(!dev->read);
543                         rbi = dev->read;
544                         dev->read = NULL;
545                         while (rbi && rbi->bi_sector <
546                                 dev->sector + STRIPE_SECTORS) {
547                                 rbi2 = r5_next_bio(rbi, dev->sector);
548                                 spin_lock_irq(&conf->device_lock);
549                                 if (--rbi->bi_phys_segments == 0) {
550                                         rbi->bi_next = return_bi;
551                                         return_bi = rbi;
552                                 }
553                                 spin_unlock_irq(&conf->device_lock);
554                                 rbi = rbi2;
555                         }
556                 }
557         }
558         set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
559
560         return_io(return_bi);
561
562         set_bit(STRIPE_HANDLE, &sh->state);
563         release_stripe(sh);
564 }
565
566 static void ops_run_biofill(struct stripe_head *sh)
567 {
568         struct dma_async_tx_descriptor *tx = NULL;
569         raid5_conf_t *conf = sh->raid_conf;
570         int i;
571
572         pr_debug("%s: stripe %llu\n", __FUNCTION__,
573                 (unsigned long long)sh->sector);
574
575         for (i = sh->disks; i--; ) {
576                 struct r5dev *dev = &sh->dev[i];
577                 if (test_bit(R5_Wantfill, &dev->flags)) {
578                         struct bio *rbi;
579                         spin_lock_irq(&conf->device_lock);
580                         dev->read = rbi = dev->toread;
581                         dev->toread = NULL;
582                         spin_unlock_irq(&conf->device_lock);
583                         while (rbi && rbi->bi_sector <
584                                 dev->sector + STRIPE_SECTORS) {
585                                 tx = async_copy_data(0, rbi, dev->page,
586                                         dev->sector, tx);
587                                 rbi = r5_next_bio(rbi, dev->sector);
588                         }
589                 }
590         }
591
592         atomic_inc(&sh->count);
593         async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
594                 ops_complete_biofill, sh);
595 }
596
597 static void ops_complete_compute5(void *stripe_head_ref)
598 {
599         struct stripe_head *sh = stripe_head_ref;
600         int target = sh->ops.target;
601         struct r5dev *tgt = &sh->dev[target];
602
603         pr_debug("%s: stripe %llu\n", __FUNCTION__,
604                 (unsigned long long)sh->sector);
605
606         set_bit(R5_UPTODATE, &tgt->flags);
607         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
608         clear_bit(R5_Wantcompute, &tgt->flags);
609         set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
610         set_bit(STRIPE_HANDLE, &sh->state);
611         release_stripe(sh);
612 }
613
614 static struct dma_async_tx_descriptor *
615 ops_run_compute5(struct stripe_head *sh, unsigned long pending)
616 {
617         /* kernel stack size limits the total number of disks */
618         int disks = sh->disks;
619         struct page *xor_srcs[disks];
620         int target = sh->ops.target;
621         struct r5dev *tgt = &sh->dev[target];
622         struct page *xor_dest = tgt->page;
623         int count = 0;
624         struct dma_async_tx_descriptor *tx;
625         int i;
626
627         pr_debug("%s: stripe %llu block: %d\n",
628                 __FUNCTION__, (unsigned long long)sh->sector, target);
629         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
630
631         for (i = disks; i--; )
632                 if (i != target)
633                         xor_srcs[count++] = sh->dev[i].page;
634
635         atomic_inc(&sh->count);
636
637         if (unlikely(count == 1))
638                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
639                         0, NULL, ops_complete_compute5, sh);
640         else
641                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
642                         ASYNC_TX_XOR_ZERO_DST, NULL,
643                         ops_complete_compute5, sh);
644
645         /* ack now if postxor is not set to be run */
646         if (tx && !test_bit(STRIPE_OP_POSTXOR, &pending))
647                 async_tx_ack(tx);
648
649         return tx;
650 }
651
652 static void ops_complete_prexor(void *stripe_head_ref)
653 {
654         struct stripe_head *sh = stripe_head_ref;
655
656         pr_debug("%s: stripe %llu\n", __FUNCTION__,
657                 (unsigned long long)sh->sector);
658
659         set_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
660 }
661
662 static struct dma_async_tx_descriptor *
663 ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
664 {
665         /* kernel stack size limits the total number of disks */
666         int disks = sh->disks;
667         struct page *xor_srcs[disks];
668         int count = 0, pd_idx = sh->pd_idx, i;
669
670         /* existing parity data subtracted */
671         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
672
673         pr_debug("%s: stripe %llu\n", __FUNCTION__,
674                 (unsigned long long)sh->sector);
675
676         for (i = disks; i--; ) {
677                 struct r5dev *dev = &sh->dev[i];
678                 /* Only process blocks that are known to be uptodate */
679                 if (dev->towrite && test_bit(R5_Wantprexor, &dev->flags))
680                         xor_srcs[count++] = dev->page;
681         }
682
683         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
684                 ASYNC_TX_DEP_ACK | ASYNC_TX_XOR_DROP_DST, tx,
685                 ops_complete_prexor, sh);
686
687         return tx;
688 }
689
690 static struct dma_async_tx_descriptor *
691 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
692                  unsigned long pending)
693 {
694         int disks = sh->disks;
695         int pd_idx = sh->pd_idx, i;
696
697         /* check if prexor is active which means only process blocks
698          * that are part of a read-modify-write (Wantprexor)
699          */
700         int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
701
702         pr_debug("%s: stripe %llu\n", __FUNCTION__,
703                 (unsigned long long)sh->sector);
704
705         for (i = disks; i--; ) {
706                 struct r5dev *dev = &sh->dev[i];
707                 struct bio *chosen;
708                 int towrite;
709
710                 towrite = 0;
711                 if (prexor) { /* rmw */
712                         if (dev->towrite &&
713                             test_bit(R5_Wantprexor, &dev->flags))
714                                 towrite = 1;
715                 } else { /* rcw */
716                         if (i != pd_idx && dev->towrite &&
717                                 test_bit(R5_LOCKED, &dev->flags))
718                                 towrite = 1;
719                 }
720
721                 if (towrite) {
722                         struct bio *wbi;
723
724                         spin_lock(&sh->lock);
725                         chosen = dev->towrite;
726                         dev->towrite = NULL;
727                         BUG_ON(dev->written);
728                         wbi = dev->written = chosen;
729                         spin_unlock(&sh->lock);
730
731                         while (wbi && wbi->bi_sector <
732                                 dev->sector + STRIPE_SECTORS) {
733                                 tx = async_copy_data(1, wbi, dev->page,
734                                         dev->sector, tx);
735                                 wbi = r5_next_bio(wbi, dev->sector);
736                         }
737                 }
738         }
739
740         return tx;
741 }
742
743 static void ops_complete_postxor(void *stripe_head_ref)
744 {
745         struct stripe_head *sh = stripe_head_ref;
746
747         pr_debug("%s: stripe %llu\n", __FUNCTION__,
748                 (unsigned long long)sh->sector);
749
750         set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
751         set_bit(STRIPE_HANDLE, &sh->state);
752         release_stripe(sh);
753 }
754
755 static void ops_complete_write(void *stripe_head_ref)
756 {
757         struct stripe_head *sh = stripe_head_ref;
758         int disks = sh->disks, i, pd_idx = sh->pd_idx;
759
760         pr_debug("%s: stripe %llu\n", __FUNCTION__,
761                 (unsigned long long)sh->sector);
762
763         for (i = disks; i--; ) {
764                 struct r5dev *dev = &sh->dev[i];
765                 if (dev->written || i == pd_idx)
766                         set_bit(R5_UPTODATE, &dev->flags);
767         }
768
769         set_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
770         set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
771
772         set_bit(STRIPE_HANDLE, &sh->state);
773         release_stripe(sh);
774 }
775
776 static void
777 ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
778                 unsigned long pending)
779 {
780         /* kernel stack size limits the total number of disks */
781         int disks = sh->disks;
782         struct page *xor_srcs[disks];
783
784         int count = 0, pd_idx = sh->pd_idx, i;
785         struct page *xor_dest;
786         int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
787         unsigned long flags;
788         dma_async_tx_callback callback;
789
790         pr_debug("%s: stripe %llu\n", __FUNCTION__,
791                 (unsigned long long)sh->sector);
792
793         /* check if prexor is active which means only process blocks
794          * that are part of a read-modify-write (written)
795          */
796         if (prexor) {
797                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
798                 for (i = disks; i--; ) {
799                         struct r5dev *dev = &sh->dev[i];
800                         if (dev->written)
801                                 xor_srcs[count++] = dev->page;
802                 }
803         } else {
804                 xor_dest = sh->dev[pd_idx].page;
805                 for (i = disks; i--; ) {
806                         struct r5dev *dev = &sh->dev[i];
807                         if (i != pd_idx)
808                                 xor_srcs[count++] = dev->page;
809                 }
810         }
811
812         /* check whether this postxor is part of a write */
813         callback = test_bit(STRIPE_OP_BIODRAIN, &pending) ?
814                 ops_complete_write : ops_complete_postxor;
815
816         /* 1/ if we prexor'd then the dest is reused as a source
817          * 2/ if we did not prexor then we are redoing the parity
818          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
819          * for the synchronous xor case
820          */
821         flags = ASYNC_TX_DEP_ACK | ASYNC_TX_ACK |
822                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
823
824         atomic_inc(&sh->count);
825
826         if (unlikely(count == 1)) {
827                 flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
828                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
829                         flags, tx, callback, sh);
830         } else
831                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
832                         flags, tx, callback, sh);
833 }
834
835 static void ops_complete_check(void *stripe_head_ref)
836 {
837         struct stripe_head *sh = stripe_head_ref;
838         int pd_idx = sh->pd_idx;
839
840         pr_debug("%s: stripe %llu\n", __FUNCTION__,
841                 (unsigned long long)sh->sector);
842
843         if (test_and_clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending) &&
844                 sh->ops.zero_sum_result == 0)
845                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
846
847         set_bit(STRIPE_OP_CHECK, &sh->ops.complete);
848         set_bit(STRIPE_HANDLE, &sh->state);
849         release_stripe(sh);
850 }
851
852 static void ops_run_check(struct stripe_head *sh)
853 {
854         /* kernel stack size limits the total number of disks */
855         int disks = sh->disks;
856         struct page *xor_srcs[disks];
857         struct dma_async_tx_descriptor *tx;
858
859         int count = 0, pd_idx = sh->pd_idx, i;
860         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
861
862         pr_debug("%s: stripe %llu\n", __FUNCTION__,
863                 (unsigned long long)sh->sector);
864
865         for (i = disks; i--; ) {
866                 struct r5dev *dev = &sh->dev[i];
867                 if (i != pd_idx)
868                         xor_srcs[count++] = dev->page;
869         }
870
871         tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
872                 &sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
873
874         if (tx)
875                 set_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
876         else
877                 clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
878
879         atomic_inc(&sh->count);
880         tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
881                 ops_complete_check, sh);
882 }
883
884 static void raid5_run_ops(struct stripe_head *sh, unsigned long pending)
885 {
886         int overlap_clear = 0, i, disks = sh->disks;
887         struct dma_async_tx_descriptor *tx = NULL;
888
889         if (test_bit(STRIPE_OP_BIOFILL, &pending)) {
890                 ops_run_biofill(sh);
891                 overlap_clear++;
892         }
893
894         if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending))
895                 tx = ops_run_compute5(sh, pending);
896
897         if (test_bit(STRIPE_OP_PREXOR, &pending))
898                 tx = ops_run_prexor(sh, tx);
899
900         if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
901                 tx = ops_run_biodrain(sh, tx, pending);
902                 overlap_clear++;
903         }
904
905         if (test_bit(STRIPE_OP_POSTXOR, &pending))
906                 ops_run_postxor(sh, tx, pending);
907
908         if (test_bit(STRIPE_OP_CHECK, &pending))
909                 ops_run_check(sh);
910
911         if (test_bit(STRIPE_OP_IO, &pending))
912                 ops_run_io(sh);
913
914         if (overlap_clear)
915                 for (i = disks; i--; ) {
916                         struct r5dev *dev = &sh->dev[i];
917                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
918                                 wake_up(&sh->raid_conf->wait_for_overlap);
919                 }
920 }
921
922 static int grow_one_stripe(raid5_conf_t *conf)
923 {
924         struct stripe_head *sh;
925         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
926         if (!sh)
927                 return 0;
928         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
929         sh->raid_conf = conf;
930         spin_lock_init(&sh->lock);
931
932         if (grow_buffers(sh, conf->raid_disks)) {
933                 shrink_buffers(sh, conf->raid_disks);
934                 kmem_cache_free(conf->slab_cache, sh);
935                 return 0;
936         }
937         sh->disks = conf->raid_disks;
938         /* we just created an active stripe so... */
939         atomic_set(&sh->count, 1);
940         atomic_inc(&conf->active_stripes);
941         INIT_LIST_HEAD(&sh->lru);
942         release_stripe(sh);
943         return 1;
944 }
945
946 static int grow_stripes(raid5_conf_t *conf, int num)
947 {
948         struct kmem_cache *sc;
949         int devs = conf->raid_disks;
950
951         sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev));
952         sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev));
953         conf->active_name = 0;
954         sc = kmem_cache_create(conf->cache_name[conf->active_name],
955                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
956                                0, 0, NULL);
957         if (!sc)
958                 return 1;
959         conf->slab_cache = sc;
960         conf->pool_size = devs;
961         while (num--)
962                 if (!grow_one_stripe(conf))
963                         return 1;
964         return 0;
965 }
966
967 #ifdef CONFIG_MD_RAID5_RESHAPE
968 static int resize_stripes(raid5_conf_t *conf, int newsize)
969 {
970         /* Make all the stripes able to hold 'newsize' devices.
971          * New slots in each stripe get 'page' set to a new page.
972          *
973          * This happens in stages:
974          * 1/ create a new kmem_cache and allocate the required number of
975          *    stripe_heads.
976          * 2/ gather all the old stripe_heads and tranfer the pages across
977          *    to the new stripe_heads.  This will have the side effect of
978          *    freezing the array as once all stripe_heads have been collected,
979          *    no IO will be possible.  Old stripe heads are freed once their
980          *    pages have been transferred over, and the old kmem_cache is
981          *    freed when all stripes are done.
982          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
983          *    we simple return a failre status - no need to clean anything up.
984          * 4/ allocate new pages for the new slots in the new stripe_heads.
985          *    If this fails, we don't bother trying the shrink the
986          *    stripe_heads down again, we just leave them as they are.
987          *    As each stripe_head is processed the new one is released into
988          *    active service.
989          *
990          * Once step2 is started, we cannot afford to wait for a write,
991          * so we use GFP_NOIO allocations.
992          */
993         struct stripe_head *osh, *nsh;
994         LIST_HEAD(newstripes);
995         struct disk_info *ndisks;
996         int err = 0;
997         struct kmem_cache *sc;
998         int i;
999
1000         if (newsize <= conf->pool_size)
1001                 return 0; /* never bother to shrink */
1002
1003         md_allow_write(conf->mddev);
1004
1005         /* Step 1 */
1006         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1007                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1008                                0, 0, NULL);
1009         if (!sc)
1010                 return -ENOMEM;
1011
1012         for (i = conf->max_nr_stripes; i; i--) {
1013                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
1014                 if (!nsh)
1015                         break;
1016
1017                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
1018
1019                 nsh->raid_conf = conf;
1020                 spin_lock_init(&nsh->lock);
1021
1022                 list_add(&nsh->lru, &newstripes);
1023         }
1024         if (i) {
1025                 /* didn't get enough, give up */
1026                 while (!list_empty(&newstripes)) {
1027                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1028                         list_del(&nsh->lru);
1029                         kmem_cache_free(sc, nsh);
1030                 }
1031                 kmem_cache_destroy(sc);
1032                 return -ENOMEM;
1033         }
1034         /* Step 2 - Must use GFP_NOIO now.
1035          * OK, we have enough stripes, start collecting inactive
1036          * stripes and copying them over
1037          */
1038         list_for_each_entry(nsh, &newstripes, lru) {
1039                 spin_lock_irq(&conf->device_lock);
1040                 wait_event_lock_irq(conf->wait_for_stripe,
1041                                     !list_empty(&conf->inactive_list),
1042                                     conf->device_lock,
1043                                     unplug_slaves(conf->mddev)
1044                         );
1045                 osh = get_free_stripe(conf);
1046                 spin_unlock_irq(&conf->device_lock);
1047                 atomic_set(&nsh->count, 1);
1048                 for(i=0; i<conf->pool_size; i++)
1049                         nsh->dev[i].page = osh->dev[i].page;
1050                 for( ; i<newsize; i++)
1051                         nsh->dev[i].page = NULL;
1052                 kmem_cache_free(conf->slab_cache, osh);
1053         }
1054         kmem_cache_destroy(conf->slab_cache);
1055
1056         /* Step 3.
1057          * At this point, we are holding all the stripes so the array
1058          * is completely stalled, so now is a good time to resize
1059          * conf->disks.
1060          */
1061         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1062         if (ndisks) {
1063                 for (i=0; i<conf->raid_disks; i++)
1064                         ndisks[i] = conf->disks[i];
1065                 kfree(conf->disks);
1066                 conf->disks = ndisks;
1067         } else
1068                 err = -ENOMEM;
1069
1070         /* Step 4, return new stripes to service */
1071         while(!list_empty(&newstripes)) {
1072                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1073                 list_del_init(&nsh->lru);
1074                 for (i=conf->raid_disks; i < newsize; i++)
1075                         if (nsh->dev[i].page == NULL) {
1076                                 struct page *p = alloc_page(GFP_NOIO);
1077                                 nsh->dev[i].page = p;
1078                                 if (!p)
1079                                         err = -ENOMEM;
1080                         }
1081                 release_stripe(nsh);
1082         }
1083         /* critical section pass, GFP_NOIO no longer needed */
1084
1085         conf->slab_cache = sc;
1086         conf->active_name = 1-conf->active_name;
1087         conf->pool_size = newsize;
1088         return err;
1089 }
1090 #endif
1091
1092 static int drop_one_stripe(raid5_conf_t *conf)
1093 {
1094         struct stripe_head *sh;
1095
1096         spin_lock_irq(&conf->device_lock);
1097         sh = get_free_stripe(conf);
1098         spin_unlock_irq(&conf->device_lock);
1099         if (!sh)
1100                 return 0;
1101         BUG_ON(atomic_read(&sh->count));
1102         shrink_buffers(sh, conf->pool_size);
1103         kmem_cache_free(conf->slab_cache, sh);
1104         atomic_dec(&conf->active_stripes);
1105         return 1;
1106 }
1107
1108 static void shrink_stripes(raid5_conf_t *conf)
1109 {
1110         while (drop_one_stripe(conf))
1111                 ;
1112
1113         if (conf->slab_cache)
1114                 kmem_cache_destroy(conf->slab_cache);
1115         conf->slab_cache = NULL;
1116 }
1117
1118 static void raid5_end_read_request(struct bio * bi, int error)
1119 {
1120         struct stripe_head *sh = bi->bi_private;
1121         raid5_conf_t *conf = sh->raid_conf;
1122         int disks = sh->disks, i;
1123         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1124         char b[BDEVNAME_SIZE];
1125         mdk_rdev_t *rdev;
1126
1127
1128         for (i=0 ; i<disks; i++)
1129                 if (bi == &sh->dev[i].req)
1130                         break;
1131
1132         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1133                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1134                 uptodate);
1135         if (i == disks) {
1136                 BUG();
1137                 return;
1138         }
1139
1140         if (uptodate) {
1141                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1142                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1143                         rdev = conf->disks[i].rdev;
1144                         printk(KERN_INFO "raid5:%s: read error corrected (%lu sectors at %llu on %s)\n",
1145                                mdname(conf->mddev), STRIPE_SECTORS,
1146                                (unsigned long long)sh->sector + rdev->data_offset,
1147                                bdevname(rdev->bdev, b));
1148                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1149                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1150                 }
1151                 if (atomic_read(&conf->disks[i].rdev->read_errors))
1152                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
1153         } else {
1154                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1155                 int retry = 0;
1156                 rdev = conf->disks[i].rdev;
1157
1158                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1159                 atomic_inc(&rdev->read_errors);
1160                 if (conf->mddev->degraded)
1161                         printk(KERN_WARNING "raid5:%s: read error not correctable (sector %llu on %s).\n",
1162                                mdname(conf->mddev),
1163                                (unsigned long long)sh->sector + rdev->data_offset,
1164                                bdn);
1165                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1166                         /* Oh, no!!! */
1167                         printk(KERN_WARNING "raid5:%s: read error NOT corrected!! (sector %llu on %s).\n",
1168                                mdname(conf->mddev),
1169                                (unsigned long long)sh->sector + rdev->data_offset,
1170                                bdn);
1171                 else if (atomic_read(&rdev->read_errors)
1172                          > conf->max_nr_stripes)
1173                         printk(KERN_WARNING
1174                                "raid5:%s: Too many read errors, failing device %s.\n",
1175                                mdname(conf->mddev), bdn);
1176                 else
1177                         retry = 1;
1178                 if (retry)
1179                         set_bit(R5_ReadError, &sh->dev[i].flags);
1180                 else {
1181                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1182                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1183                         md_error(conf->mddev, rdev);
1184                 }
1185         }
1186         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1187         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1188         set_bit(STRIPE_HANDLE, &sh->state);
1189         release_stripe(sh);
1190 }
1191
1192 static void raid5_end_write_request (struct bio *bi, int error)
1193 {
1194         struct stripe_head *sh = bi->bi_private;
1195         raid5_conf_t *conf = sh->raid_conf;
1196         int disks = sh->disks, i;
1197         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1198
1199         for (i=0 ; i<disks; i++)
1200                 if (bi == &sh->dev[i].req)
1201                         break;
1202
1203         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1204                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1205                 uptodate);
1206         if (i == disks) {
1207                 BUG();
1208                 return;
1209         }
1210
1211         if (!uptodate)
1212                 md_error(conf->mddev, conf->disks[i].rdev);
1213
1214         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1215         
1216         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1217         set_bit(STRIPE_HANDLE, &sh->state);
1218         release_stripe(sh);
1219 }
1220
1221
1222 static sector_t compute_blocknr(struct stripe_head *sh, int i);
1223         
1224 static void raid5_build_block (struct stripe_head *sh, int i)
1225 {
1226         struct r5dev *dev = &sh->dev[i];
1227
1228         bio_init(&dev->req);
1229         dev->req.bi_io_vec = &dev->vec;
1230         dev->req.bi_vcnt++;
1231         dev->req.bi_max_vecs++;
1232         dev->vec.bv_page = dev->page;
1233         dev->vec.bv_len = STRIPE_SIZE;
1234         dev->vec.bv_offset = 0;
1235
1236         dev->req.bi_sector = sh->sector;
1237         dev->req.bi_private = sh;
1238
1239         dev->flags = 0;
1240         dev->sector = compute_blocknr(sh, i);
1241 }
1242
1243 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1244 {
1245         char b[BDEVNAME_SIZE];
1246         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1247         pr_debug("raid5: error called\n");
1248
1249         if (!test_bit(Faulty, &rdev->flags)) {
1250                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1251                 if (test_and_clear_bit(In_sync, &rdev->flags)) {
1252                         unsigned long flags;
1253                         spin_lock_irqsave(&conf->device_lock, flags);
1254                         mddev->degraded++;
1255                         spin_unlock_irqrestore(&conf->device_lock, flags);
1256                         /*
1257                          * if recovery was running, make sure it aborts.
1258                          */
1259                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
1260                 }
1261                 set_bit(Faulty, &rdev->flags);
1262                 printk (KERN_ALERT
1263                         "raid5: Disk failure on %s, disabling device."
1264                         " Operation continuing on %d devices\n",
1265                         bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
1266         }
1267 }
1268
1269 /*
1270  * Input: a 'big' sector number,
1271  * Output: index of the data and parity disk, and the sector # in them.
1272  */
1273 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
1274                         unsigned int data_disks, unsigned int * dd_idx,
1275                         unsigned int * pd_idx, raid5_conf_t *conf)
1276 {
1277         long stripe;
1278         unsigned long chunk_number;
1279         unsigned int chunk_offset;
1280         sector_t new_sector;
1281         int sectors_per_chunk = conf->chunk_size >> 9;
1282
1283         /* First compute the information on this sector */
1284
1285         /*
1286          * Compute the chunk number and the sector offset inside the chunk
1287          */
1288         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1289         chunk_number = r_sector;
1290         BUG_ON(r_sector != chunk_number);
1291
1292         /*
1293          * Compute the stripe number
1294          */
1295         stripe = chunk_number / data_disks;
1296
1297         /*
1298          * Compute the data disk and parity disk indexes inside the stripe
1299          */
1300         *dd_idx = chunk_number % data_disks;
1301
1302         /*
1303          * Select the parity disk based on the user selected algorithm.
1304          */
1305         switch(conf->level) {
1306         case 4:
1307                 *pd_idx = data_disks;
1308                 break;
1309         case 5:
1310                 switch (conf->algorithm) {
1311                 case ALGORITHM_LEFT_ASYMMETRIC:
1312                         *pd_idx = data_disks - stripe % raid_disks;
1313                         if (*dd_idx >= *pd_idx)
1314                                 (*dd_idx)++;
1315                         break;
1316                 case ALGORITHM_RIGHT_ASYMMETRIC:
1317                         *pd_idx = stripe % raid_disks;
1318                         if (*dd_idx >= *pd_idx)
1319                                 (*dd_idx)++;
1320                         break;
1321                 case ALGORITHM_LEFT_SYMMETRIC:
1322                         *pd_idx = data_disks - stripe % raid_disks;
1323                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1324                         break;
1325                 case ALGORITHM_RIGHT_SYMMETRIC:
1326                         *pd_idx = stripe % raid_disks;
1327                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1328                         break;
1329                 default:
1330                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1331                                 conf->algorithm);
1332                 }
1333                 break;
1334         case 6:
1335
1336                 /**** FIX THIS ****/
1337                 switch (conf->algorithm) {
1338                 case ALGORITHM_LEFT_ASYMMETRIC:
1339                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1340                         if (*pd_idx == raid_disks-1)
1341                                 (*dd_idx)++;    /* Q D D D P */
1342                         else if (*dd_idx >= *pd_idx)
1343                                 (*dd_idx) += 2; /* D D P Q D */
1344                         break;
1345                 case ALGORITHM_RIGHT_ASYMMETRIC:
1346                         *pd_idx = stripe % raid_disks;
1347                         if (*pd_idx == raid_disks-1)
1348                                 (*dd_idx)++;    /* Q D D D P */
1349                         else if (*dd_idx >= *pd_idx)
1350                                 (*dd_idx) += 2; /* D D P Q D */
1351                         break;
1352                 case ALGORITHM_LEFT_SYMMETRIC:
1353                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1354                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1355                         break;
1356                 case ALGORITHM_RIGHT_SYMMETRIC:
1357                         *pd_idx = stripe % raid_disks;
1358                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1359                         break;
1360                 default:
1361                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1362                                 conf->algorithm);
1363                 }
1364                 break;
1365         }
1366
1367         /*
1368          * Finally, compute the new sector number
1369          */
1370         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1371         return new_sector;
1372 }
1373
1374
1375 static sector_t compute_blocknr(struct stripe_head *sh, int i)
1376 {
1377         raid5_conf_t *conf = sh->raid_conf;
1378         int raid_disks = sh->disks;
1379         int data_disks = raid_disks - conf->max_degraded;
1380         sector_t new_sector = sh->sector, check;
1381         int sectors_per_chunk = conf->chunk_size >> 9;
1382         sector_t stripe;
1383         int chunk_offset;
1384         int chunk_number, dummy1, dummy2, dd_idx = i;
1385         sector_t r_sector;
1386
1387
1388         chunk_offset = sector_div(new_sector, sectors_per_chunk);
1389         stripe = new_sector;
1390         BUG_ON(new_sector != stripe);
1391
1392         if (i == sh->pd_idx)
1393                 return 0;
1394         switch(conf->level) {
1395         case 4: break;
1396         case 5:
1397                 switch (conf->algorithm) {
1398                 case ALGORITHM_LEFT_ASYMMETRIC:
1399                 case ALGORITHM_RIGHT_ASYMMETRIC:
1400                         if (i > sh->pd_idx)
1401                                 i--;
1402                         break;
1403                 case ALGORITHM_LEFT_SYMMETRIC:
1404                 case ALGORITHM_RIGHT_SYMMETRIC:
1405                         if (i < sh->pd_idx)
1406                                 i += raid_disks;
1407                         i -= (sh->pd_idx + 1);
1408                         break;
1409                 default:
1410                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1411                                conf->algorithm);
1412                 }
1413                 break;
1414         case 6:
1415                 if (i == raid6_next_disk(sh->pd_idx, raid_disks))
1416                         return 0; /* It is the Q disk */
1417                 switch (conf->algorithm) {
1418                 case ALGORITHM_LEFT_ASYMMETRIC:
1419                 case ALGORITHM_RIGHT_ASYMMETRIC:
1420                         if (sh->pd_idx == raid_disks-1)
1421                                 i--;    /* Q D D D P */
1422                         else if (i > sh->pd_idx)
1423                                 i -= 2; /* D D P Q D */
1424                         break;
1425                 case ALGORITHM_LEFT_SYMMETRIC:
1426                 case ALGORITHM_RIGHT_SYMMETRIC:
1427                         if (sh->pd_idx == raid_disks-1)
1428                                 i--; /* Q D D D P */
1429                         else {
1430                                 /* D D P Q D */
1431                                 if (i < sh->pd_idx)
1432                                         i += raid_disks;
1433                                 i -= (sh->pd_idx + 2);
1434                         }
1435                         break;
1436                 default:
1437                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1438                                 conf->algorithm);
1439                 }
1440                 break;
1441         }
1442
1443         chunk_number = stripe * data_disks + i;
1444         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
1445
1446         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
1447         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
1448                 printk(KERN_ERR "compute_blocknr: map not correct\n");
1449                 return 0;
1450         }
1451         return r_sector;
1452 }
1453
1454
1455
1456 /*
1457  * Copy data between a page in the stripe cache, and one or more bion
1458  * The page could align with the middle of the bio, or there could be
1459  * several bion, each with several bio_vecs, which cover part of the page
1460  * Multiple bion are linked together on bi_next.  There may be extras
1461  * at the end of this list.  We ignore them.
1462  */
1463 static void copy_data(int frombio, struct bio *bio,
1464                      struct page *page,
1465                      sector_t sector)
1466 {
1467         char *pa = page_address(page);
1468         struct bio_vec *bvl;
1469         int i;
1470         int page_offset;
1471
1472         if (bio->bi_sector >= sector)
1473                 page_offset = (signed)(bio->bi_sector - sector) * 512;
1474         else
1475                 page_offset = (signed)(sector - bio->bi_sector) * -512;
1476         bio_for_each_segment(bvl, bio, i) {
1477                 int len = bio_iovec_idx(bio,i)->bv_len;
1478                 int clen;
1479                 int b_offset = 0;
1480
1481                 if (page_offset < 0) {
1482                         b_offset = -page_offset;
1483                         page_offset += b_offset;
1484                         len -= b_offset;
1485                 }
1486
1487                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1488                         clen = STRIPE_SIZE - page_offset;
1489                 else clen = len;
1490
1491                 if (clen > 0) {
1492                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
1493                         if (frombio)
1494                                 memcpy(pa+page_offset, ba+b_offset, clen);
1495                         else
1496                                 memcpy(ba+b_offset, pa+page_offset, clen);
1497                         __bio_kunmap_atomic(ba, KM_USER0);
1498                 }
1499                 if (clen < len) /* hit end of page */
1500                         break;
1501                 page_offset +=  len;
1502         }
1503 }
1504
1505 #define check_xor()     do {                                              \
1506                                 if (count == MAX_XOR_BLOCKS) {            \
1507                                 xor_blocks(count, STRIPE_SIZE, dest, ptr);\
1508                                 count = 0;                                \
1509                            }                                              \
1510                         } while(0)
1511
1512 static void compute_parity6(struct stripe_head *sh, int method)
1513 {
1514         raid6_conf_t *conf = sh->raid_conf;
1515         int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
1516         struct bio *chosen;
1517         /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1518         void *ptrs[disks];
1519
1520         qd_idx = raid6_next_disk(pd_idx, disks);
1521         d0_idx = raid6_next_disk(qd_idx, disks);
1522
1523         pr_debug("compute_parity, stripe %llu, method %d\n",
1524                 (unsigned long long)sh->sector, method);
1525
1526         switch(method) {
1527         case READ_MODIFY_WRITE:
1528                 BUG();          /* READ_MODIFY_WRITE N/A for RAID-6 */
1529         case RECONSTRUCT_WRITE:
1530                 for (i= disks; i-- ;)
1531                         if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1532                                 chosen = sh->dev[i].towrite;
1533                                 sh->dev[i].towrite = NULL;
1534
1535                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1536                                         wake_up(&conf->wait_for_overlap);
1537
1538                                 BUG_ON(sh->dev[i].written);
1539                                 sh->dev[i].written = chosen;
1540                         }
1541                 break;
1542         case CHECK_PARITY:
1543                 BUG();          /* Not implemented yet */
1544         }
1545
1546         for (i = disks; i--;)
1547                 if (sh->dev[i].written) {
1548                         sector_t sector = sh->dev[i].sector;
1549                         struct bio *wbi = sh->dev[i].written;
1550                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1551                                 copy_data(1, wbi, sh->dev[i].page, sector);
1552                                 wbi = r5_next_bio(wbi, sector);
1553                         }
1554
1555                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1556                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1557                 }
1558
1559 //      switch(method) {
1560 //      case RECONSTRUCT_WRITE:
1561 //      case CHECK_PARITY:
1562 //      case UPDATE_PARITY:
1563                 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1564                 /* FIX: Is this ordering of drives even remotely optimal? */
1565                 count = 0;
1566                 i = d0_idx;
1567                 do {
1568                         ptrs[count++] = page_address(sh->dev[i].page);
1569                         if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1570                                 printk("block %d/%d not uptodate on parity calc\n", i,count);
1571                         i = raid6_next_disk(i, disks);
1572                 } while ( i != d0_idx );
1573 //              break;
1574 //      }
1575
1576         raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1577
1578         switch(method) {
1579         case RECONSTRUCT_WRITE:
1580                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1581                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1582                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1583                 set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1584                 break;
1585         case UPDATE_PARITY:
1586                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1587                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1588                 break;
1589         }
1590 }
1591
1592
1593 /* Compute one missing block */
1594 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1595 {
1596         int i, count, disks = sh->disks;
1597         void *ptr[MAX_XOR_BLOCKS], *dest, *p;
1598         int pd_idx = sh->pd_idx;
1599         int qd_idx = raid6_next_disk(pd_idx, disks);
1600
1601         pr_debug("compute_block_1, stripe %llu, idx %d\n",
1602                 (unsigned long long)sh->sector, dd_idx);
1603
1604         if ( dd_idx == qd_idx ) {
1605                 /* We're actually computing the Q drive */
1606                 compute_parity6(sh, UPDATE_PARITY);
1607         } else {
1608                 dest = page_address(sh->dev[dd_idx].page);
1609                 if (!nozero) memset(dest, 0, STRIPE_SIZE);
1610                 count = 0;
1611                 for (i = disks ; i--; ) {
1612                         if (i == dd_idx || i == qd_idx)
1613                                 continue;
1614                         p = page_address(sh->dev[i].page);
1615                         if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1616                                 ptr[count++] = p;
1617                         else
1618                                 printk("compute_block() %d, stripe %llu, %d"
1619                                        " not present\n", dd_idx,
1620                                        (unsigned long long)sh->sector, i);
1621
1622                         check_xor();
1623                 }
1624                 if (count)
1625                         xor_blocks(count, STRIPE_SIZE, dest, ptr);
1626                 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1627                 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1628         }
1629 }
1630
1631 /* Compute two missing blocks */
1632 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1633 {
1634         int i, count, disks = sh->disks;
1635         int pd_idx = sh->pd_idx;
1636         int qd_idx = raid6_next_disk(pd_idx, disks);
1637         int d0_idx = raid6_next_disk(qd_idx, disks);
1638         int faila, failb;
1639
1640         /* faila and failb are disk numbers relative to d0_idx */
1641         /* pd_idx become disks-2 and qd_idx become disks-1 */
1642         faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1643         failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1644
1645         BUG_ON(faila == failb);
1646         if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1647
1648         pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1649                (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1650
1651         if ( failb == disks-1 ) {
1652                 /* Q disk is one of the missing disks */
1653                 if ( faila == disks-2 ) {
1654                         /* Missing P+Q, just recompute */
1655                         compute_parity6(sh, UPDATE_PARITY);
1656                         return;
1657                 } else {
1658                         /* We're missing D+Q; recompute D from P */
1659                         compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1660                         compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1661                         return;
1662                 }
1663         }
1664
1665         /* We're missing D+P or D+D; build pointer table */
1666         {
1667                 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1668                 void *ptrs[disks];
1669
1670                 count = 0;
1671                 i = d0_idx;
1672                 do {
1673                         ptrs[count++] = page_address(sh->dev[i].page);
1674                         i = raid6_next_disk(i, disks);
1675                         if (i != dd_idx1 && i != dd_idx2 &&
1676                             !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1677                                 printk("compute_2 with missing block %d/%d\n", count, i);
1678                 } while ( i != d0_idx );
1679
1680                 if ( failb == disks-2 ) {
1681                         /* We're missing D+P. */
1682                         raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1683                 } else {
1684                         /* We're missing D+D. */
1685                         raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1686                 }
1687
1688                 /* Both the above update both missing blocks */
1689                 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1690                 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1691         }
1692 }
1693
1694 static int
1695 handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
1696 {
1697         int i, pd_idx = sh->pd_idx, disks = sh->disks;
1698         int locked = 0;
1699
1700         if (rcw) {
1701                 /* if we are not expanding this is a proper write request, and
1702                  * there will be bios with new data to be drained into the
1703                  * stripe cache
1704                  */
1705                 if (!expand) {
1706                         set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
1707                         sh->ops.count++;
1708                 }
1709
1710                 set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
1711                 sh->ops.count++;
1712
1713                 for (i = disks; i--; ) {
1714                         struct r5dev *dev = &sh->dev[i];
1715
1716                         if (dev->towrite) {
1717                                 set_bit(R5_LOCKED, &dev->flags);
1718                                 if (!expand)
1719                                         clear_bit(R5_UPTODATE, &dev->flags);
1720                                 locked++;
1721                         }
1722                 }
1723         } else {
1724                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
1725                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
1726
1727                 set_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
1728                 set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
1729                 set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
1730
1731                 sh->ops.count += 3;
1732
1733                 for (i = disks; i--; ) {
1734                         struct r5dev *dev = &sh->dev[i];
1735                         if (i == pd_idx)
1736                                 continue;
1737
1738                         /* For a read-modify write there may be blocks that are
1739                          * locked for reading while others are ready to be
1740                          * written so we distinguish these blocks by the
1741                          * R5_Wantprexor bit
1742                          */
1743                         if (dev->towrite &&
1744                             (test_bit(R5_UPTODATE, &dev->flags) ||
1745                             test_bit(R5_Wantcompute, &dev->flags))) {
1746                                 set_bit(R5_Wantprexor, &dev->flags);
1747                                 set_bit(R5_LOCKED, &dev->flags);
1748                                 clear_bit(R5_UPTODATE, &dev->flags);
1749                                 locked++;
1750                         }
1751                 }
1752         }
1753
1754         /* keep the parity disk locked while asynchronous operations
1755          * are in flight
1756          */
1757         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
1758         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1759         locked++;
1760
1761         pr_debug("%s: stripe %llu locked: %d pending: %lx\n",
1762                 __FUNCTION__, (unsigned long long)sh->sector,
1763                 locked, sh->ops.pending);
1764
1765         return locked;
1766 }
1767
1768 /*
1769  * Each stripe/dev can have one or more bion attached.
1770  * toread/towrite point to the first in a chain.
1771  * The bi_next chain must be in order.
1772  */
1773 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1774 {
1775         struct bio **bip;
1776         raid5_conf_t *conf = sh->raid_conf;
1777         int firstwrite=0;
1778
1779         pr_debug("adding bh b#%llu to stripe s#%llu\n",
1780                 (unsigned long long)bi->bi_sector,
1781                 (unsigned long long)sh->sector);
1782
1783
1784         spin_lock(&sh->lock);
1785         spin_lock_irq(&conf->device_lock);
1786         if (forwrite) {
1787                 bip = &sh->dev[dd_idx].towrite;
1788                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1789                         firstwrite = 1;
1790         } else
1791                 bip = &sh->dev[dd_idx].toread;
1792         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1793                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1794                         goto overlap;
1795                 bip = & (*bip)->bi_next;
1796         }
1797         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1798                 goto overlap;
1799
1800         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1801         if (*bip)
1802                 bi->bi_next = *bip;
1803         *bip = bi;
1804         bi->bi_phys_segments ++;
1805         spin_unlock_irq(&conf->device_lock);
1806         spin_unlock(&sh->lock);
1807
1808         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
1809                 (unsigned long long)bi->bi_sector,
1810                 (unsigned long long)sh->sector, dd_idx);
1811
1812         if (conf->mddev->bitmap && firstwrite) {
1813                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1814                                   STRIPE_SECTORS, 0);
1815                 sh->bm_seq = conf->seq_flush+1;
1816                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1817         }
1818
1819         if (forwrite) {
1820                 /* check if page is covered */
1821                 sector_t sector = sh->dev[dd_idx].sector;
1822                 for (bi=sh->dev[dd_idx].towrite;
1823                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1824                              bi && bi->bi_sector <= sector;
1825                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1826                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1827                                 sector = bi->bi_sector + (bi->bi_size>>9);
1828                 }
1829                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1830                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1831         }
1832         return 1;
1833
1834  overlap:
1835         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1836         spin_unlock_irq(&conf->device_lock);
1837         spin_unlock(&sh->lock);
1838         return 0;
1839 }
1840
1841 static void end_reshape(raid5_conf_t *conf);
1842
1843 static int page_is_zero(struct page *p)
1844 {
1845         char *a = page_address(p);
1846         return ((*(u32*)a) == 0 &&
1847                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1848 }
1849
1850 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1851 {
1852         int sectors_per_chunk = conf->chunk_size >> 9;
1853         int pd_idx, dd_idx;
1854         int chunk_offset = sector_div(stripe, sectors_per_chunk);
1855
1856         raid5_compute_sector(stripe * (disks - conf->max_degraded)
1857                              *sectors_per_chunk + chunk_offset,
1858                              disks, disks - conf->max_degraded,
1859                              &dd_idx, &pd_idx, conf);
1860         return pd_idx;
1861 }
1862
1863 static void
1864 handle_requests_to_failed_array(raid5_conf_t *conf, struct stripe_head *sh,
1865                                 struct stripe_head_state *s, int disks,
1866                                 struct bio **return_bi)
1867 {
1868         int i;
1869         for (i = disks; i--; ) {
1870                 struct bio *bi;
1871                 int bitmap_end = 0;
1872
1873                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1874                         mdk_rdev_t *rdev;
1875                         rcu_read_lock();
1876                         rdev = rcu_dereference(conf->disks[i].rdev);
1877                         if (rdev && test_bit(In_sync, &rdev->flags))
1878                                 /* multiple read failures in one stripe */
1879                                 md_error(conf->mddev, rdev);
1880                         rcu_read_unlock();
1881                 }
1882                 spin_lock_irq(&conf->device_lock);
1883                 /* fail all writes first */
1884                 bi = sh->dev[i].towrite;
1885                 sh->dev[i].towrite = NULL;
1886                 if (bi) {
1887                         s->to_write--;
1888                         bitmap_end = 1;
1889                 }
1890
1891                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1892                         wake_up(&conf->wait_for_overlap);
1893
1894                 while (bi && bi->bi_sector <
1895                         sh->dev[i].sector + STRIPE_SECTORS) {
1896                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1897                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1898                         if (--bi->bi_phys_segments == 0) {
1899                                 md_write_end(conf->mddev);
1900                                 bi->bi_next = *return_bi;
1901                                 *return_bi = bi;
1902                         }
1903                         bi = nextbi;
1904                 }
1905                 /* and fail all 'written' */
1906                 bi = sh->dev[i].written;
1907                 sh->dev[i].written = NULL;
1908                 if (bi) bitmap_end = 1;
1909                 while (bi && bi->bi_sector <
1910                        sh->dev[i].sector + STRIPE_SECTORS) {
1911                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1912                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1913                         if (--bi->bi_phys_segments == 0) {
1914                                 md_write_end(conf->mddev);
1915                                 bi->bi_next = *return_bi;
1916                                 *return_bi = bi;
1917                         }
1918                         bi = bi2;
1919                 }
1920
1921                 /* fail any reads if this device is non-operational and
1922                  * the data has not reached the cache yet.
1923                  */
1924                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
1925                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1926                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
1927                         bi = sh->dev[i].toread;
1928                         sh->dev[i].toread = NULL;
1929                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1930                                 wake_up(&conf->wait_for_overlap);
1931                         if (bi) s->to_read--;
1932                         while (bi && bi->bi_sector <
1933                                sh->dev[i].sector + STRIPE_SECTORS) {
1934                                 struct bio *nextbi =
1935                                         r5_next_bio(bi, sh->dev[i].sector);
1936                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1937                                 if (--bi->bi_phys_segments == 0) {
1938                                         bi->bi_next = *return_bi;
1939                                         *return_bi = bi;
1940                                 }
1941                                 bi = nextbi;
1942                         }
1943                 }
1944                 spin_unlock_irq(&conf->device_lock);
1945                 if (bitmap_end)
1946                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1947                                         STRIPE_SECTORS, 0, 0);
1948         }
1949
1950 }
1951
1952 /* __handle_issuing_new_read_requests5 - returns 0 if there are no more disks
1953  * to process
1954  */
1955 static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
1956                         struct stripe_head_state *s, int disk_idx, int disks)
1957 {
1958         struct r5dev *dev = &sh->dev[disk_idx];
1959         struct r5dev *failed_dev = &sh->dev[s->failed_num];
1960
1961         /* don't schedule compute operations or reads on the parity block while
1962          * a check is in flight
1963          */
1964         if ((disk_idx == sh->pd_idx) &&
1965              test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
1966                 return ~0;
1967
1968         /* is the data in this block needed, and can we get it? */
1969         if (!test_bit(R5_LOCKED, &dev->flags) &&
1970             !test_bit(R5_UPTODATE, &dev->flags) && (dev->toread ||
1971             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1972              s->syncing || s->expanding || (s->failed &&
1973              (failed_dev->toread || (failed_dev->towrite &&
1974              !test_bit(R5_OVERWRITE, &failed_dev->flags)
1975              ))))) {
1976                 /* 1/ We would like to get this block, possibly by computing it,
1977                  * but we might not be able to.
1978                  *
1979                  * 2/ Since parity check operations potentially make the parity
1980                  * block !uptodate it will need to be refreshed before any
1981                  * compute operations on data disks are scheduled.
1982                  *
1983                  * 3/ We hold off parity block re-reads until check operations
1984                  * have quiesced.
1985                  */
1986                 if ((s->uptodate == disks - 1) &&
1987                     !test_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
1988                         set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
1989                         set_bit(R5_Wantcompute, &dev->flags);
1990                         sh->ops.target = disk_idx;
1991                         s->req_compute = 1;
1992                         sh->ops.count++;
1993                         /* Careful: from this point on 'uptodate' is in the eye
1994                          * of raid5_run_ops which services 'compute' operations
1995                          * before writes. R5_Wantcompute flags a block that will
1996                          * be R5_UPTODATE by the time it is needed for a
1997                          * subsequent operation.
1998                          */
1999                         s->uptodate++;
2000                         return 0; /* uptodate + compute == disks */
2001                 } else if ((s->uptodate < disks - 1) &&
2002                         test_bit(R5_Insync, &dev->flags)) {
2003                         /* Note: we hold off compute operations while checks are
2004                          * in flight, but we still prefer 'compute' over 'read'
2005                          * hence we only read if (uptodate < * disks-1)
2006                          */
2007                         set_bit(R5_LOCKED, &dev->flags);
2008                         set_bit(R5_Wantread, &dev->flags);
2009                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2010                                 sh->ops.count++;
2011                         s->locked++;
2012                         pr_debug("Reading block %d (sync=%d)\n", disk_idx,
2013                                 s->syncing);
2014                 }
2015         }
2016
2017         return ~0;
2018 }
2019
2020 static void handle_issuing_new_read_requests5(struct stripe_head *sh,
2021                         struct stripe_head_state *s, int disks)
2022 {
2023         int i;
2024
2025         /* Clear completed compute operations.  Parity recovery
2026          * (STRIPE_OP_MOD_REPAIR_PD) implies a write-back which is handled
2027          * later on in this routine
2028          */
2029         if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
2030                 !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2031                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
2032                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
2033                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2034         }
2035
2036         /* look for blocks to read/compute, skip this if a compute
2037          * is already in flight, or if the stripe contents are in the
2038          * midst of changing due to a write
2039          */
2040         if (!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
2041                 !test_bit(STRIPE_OP_PREXOR, &sh->ops.pending) &&
2042                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2043                 for (i = disks; i--; )
2044                         if (__handle_issuing_new_read_requests5(
2045                                 sh, s, i, disks) == 0)
2046                                 break;
2047         }
2048         set_bit(STRIPE_HANDLE, &sh->state);
2049 }
2050
2051 static void handle_issuing_new_read_requests6(struct stripe_head *sh,
2052                         struct stripe_head_state *s, struct r6_state *r6s,
2053                         int disks)
2054 {
2055         int i;
2056         for (i = disks; i--; ) {
2057                 struct r5dev *dev = &sh->dev[i];
2058                 if (!test_bit(R5_LOCKED, &dev->flags) &&
2059                     !test_bit(R5_UPTODATE, &dev->flags) &&
2060                     (dev->toread || (dev->towrite &&
2061                      !test_bit(R5_OVERWRITE, &dev->flags)) ||
2062                      s->syncing || s->expanding ||
2063                      (s->failed >= 1 &&
2064                       (sh->dev[r6s->failed_num[0]].toread ||
2065                        s->to_write)) ||
2066                      (s->failed >= 2 &&
2067                       (sh->dev[r6s->failed_num[1]].toread ||
2068                        s->to_write)))) {
2069                         /* we would like to get this block, possibly
2070                          * by computing it, but we might not be able to
2071                          */
2072                         if (s->uptodate == disks-1) {
2073                                 pr_debug("Computing stripe %llu block %d\n",
2074                                        (unsigned long long)sh->sector, i);
2075                                 compute_block_1(sh, i, 0);
2076                                 s->uptodate++;
2077                         } else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
2078                                 /* Computing 2-failure is *very* expensive; only
2079                                  * do it if failed >= 2
2080                                  */
2081                                 int other;
2082                                 for (other = disks; other--; ) {
2083                                         if (other == i)
2084                                                 continue;
2085                                         if (!test_bit(R5_UPTODATE,
2086                                               &sh->dev[other].flags))
2087                                                 break;
2088                                 }
2089                                 BUG_ON(other < 0);
2090                                 pr_debug("Computing stripe %llu blocks %d,%d\n",
2091                                        (unsigned long long)sh->sector,
2092                                        i, other);
2093                                 compute_block_2(sh, i, other);
2094                                 s->uptodate += 2;
2095                         } else if (test_bit(R5_Insync, &dev->flags)) {
2096                                 set_bit(R5_LOCKED, &dev->flags);
2097                                 set_bit(R5_Wantread, &dev->flags);
2098                                 s->locked++;
2099                                 pr_debug("Reading block %d (sync=%d)\n",
2100                                         i, s->syncing);
2101                         }
2102                 }
2103         }
2104         set_bit(STRIPE_HANDLE, &sh->state);
2105 }
2106
2107
2108 /* handle_completed_write_requests
2109  * any written block on an uptodate or failed drive can be returned.
2110  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2111  * never LOCKED, so we don't need to test 'failed' directly.
2112  */
2113 static void handle_completed_write_requests(raid5_conf_t *conf,
2114         struct stripe_head *sh, int disks, struct bio **return_bi)
2115 {
2116         int i;
2117         struct r5dev *dev;
2118
2119         for (i = disks; i--; )
2120                 if (sh->dev[i].written) {
2121                         dev = &sh->dev[i];
2122                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2123                                 test_bit(R5_UPTODATE, &dev->flags)) {
2124                                 /* We can return any write requests */
2125                                 struct bio *wbi, *wbi2;
2126                                 int bitmap_end = 0;
2127                                 pr_debug("Return write for disc %d\n", i);
2128                                 spin_lock_irq(&conf->device_lock);
2129                                 wbi = dev->written;
2130                                 dev->written = NULL;
2131                                 while (wbi && wbi->bi_sector <
2132                                         dev->sector + STRIPE_SECTORS) {
2133                                         wbi2 = r5_next_bio(wbi, dev->sector);
2134                                         if (--wbi->bi_phys_segments == 0) {
2135                                                 md_write_end(conf->mddev);
2136                                                 wbi->bi_next = *return_bi;
2137                                                 *return_bi = wbi;
2138                                         }
2139                                         wbi = wbi2;
2140                                 }
2141                                 if (dev->towrite == NULL)
2142                                         bitmap_end = 1;
2143                                 spin_unlock_irq(&conf->device_lock);
2144                                 if (bitmap_end)
2145                                         bitmap_endwrite(conf->mddev->bitmap,
2146                                                         sh->sector,
2147                                                         STRIPE_SECTORS,
2148                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2149                                                         0);
2150                         }
2151                 }
2152 }
2153
2154 static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
2155                 struct stripe_head *sh, struct stripe_head_state *s, int disks)
2156 {
2157         int rmw = 0, rcw = 0, i;
2158         for (i = disks; i--; ) {
2159                 /* would I have to read this buffer for read_modify_write */
2160                 struct r5dev *dev = &sh->dev[i];
2161                 if ((dev->towrite || i == sh->pd_idx) &&
2162                     !test_bit(R5_LOCKED, &dev->flags) &&
2163                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2164                       test_bit(R5_Wantcompute, &dev->flags))) {
2165                         if (test_bit(R5_Insync, &dev->flags))
2166                                 rmw++;
2167                         else
2168                                 rmw += 2*disks;  /* cannot read it */
2169                 }
2170                 /* Would I have to read this buffer for reconstruct_write */
2171                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2172                     !test_bit(R5_LOCKED, &dev->flags) &&
2173                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2174                     test_bit(R5_Wantcompute, &dev->flags))) {
2175                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2176                         else
2177                                 rcw += 2*disks;
2178                 }
2179         }
2180         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2181                 (unsigned long long)sh->sector, rmw, rcw);
2182         set_bit(STRIPE_HANDLE, &sh->state);
2183         if (rmw < rcw && rmw > 0)
2184                 /* prefer read-modify-write, but need to get some data */
2185                 for (i = disks; i--; ) {
2186                         struct r5dev *dev = &sh->dev[i];
2187                         if ((dev->towrite || i == sh->pd_idx) &&
2188                             !test_bit(R5_LOCKED, &dev->flags) &&
2189                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2190                             test_bit(R5_Wantcompute, &dev->flags)) &&
2191                             test_bit(R5_Insync, &dev->flags)) {
2192                                 if (
2193                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2194                                         pr_debug("Read_old block "
2195                                                 "%d for r-m-w\n", i);
2196                                         set_bit(R5_LOCKED, &dev->flags);
2197                                         set_bit(R5_Wantread, &dev->flags);
2198                                         if (!test_and_set_bit(
2199                                                 STRIPE_OP_IO, &sh->ops.pending))
2200                                                 sh->ops.count++;
2201                                         s->locked++;
2202                                 } else {
2203                                         set_bit(STRIPE_DELAYED, &sh->state);
2204                                         set_bit(STRIPE_HANDLE, &sh->state);
2205                                 }
2206                         }
2207                 }
2208         if (rcw <= rmw && rcw > 0)
2209                 /* want reconstruct write, but need to get some data */
2210                 for (i = disks; i--; ) {
2211                         struct r5dev *dev = &sh->dev[i];
2212                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2213                             i != sh->pd_idx &&
2214                             !test_bit(R5_LOCKED, &dev->flags) &&
2215                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2216                             test_bit(R5_Wantcompute, &dev->flags)) &&
2217                             test_bit(R5_Insync, &dev->flags)) {
2218                                 if (
2219                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2220                                         pr_debug("Read_old block "
2221                                                 "%d for Reconstruct\n", i);
2222                                         set_bit(R5_LOCKED, &dev->flags);
2223                                         set_bit(R5_Wantread, &dev->flags);
2224                                         if (!test_and_set_bit(
2225                                                 STRIPE_OP_IO, &sh->ops.pending))
2226                                                 sh->ops.count++;
2227                                         s->locked++;
2228                                 } else {
2229                                         set_bit(STRIPE_DELAYED, &sh->state);
2230                                         set_bit(STRIPE_HANDLE, &sh->state);
2231                                 }
2232                         }
2233                 }
2234         /* now if nothing is locked, and if we have enough data,
2235          * we can start a write request
2236          */
2237         /* since handle_stripe can be called at any time we need to handle the
2238          * case where a compute block operation has been submitted and then a
2239          * subsequent call wants to start a write request.  raid5_run_ops only
2240          * handles the case where compute block and postxor are requested
2241          * simultaneously.  If this is not the case then new writes need to be
2242          * held off until the compute completes.
2243          */
2244         if ((s->req_compute ||
2245             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) &&
2246                 (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2247                 !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2248                 s->locked += handle_write_operations5(sh, rcw == 0, 0);
2249 }
2250
2251 static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
2252                 struct stripe_head *sh, struct stripe_head_state *s,
2253                 struct r6_state *r6s, int disks)
2254 {
2255         int rcw = 0, must_compute = 0, pd_idx = sh->pd_idx, i;
2256         int qd_idx = r6s->qd_idx;
2257         for (i = disks; i--; ) {
2258                 struct r5dev *dev = &sh->dev[i];
2259                 /* Would I have to read this buffer for reconstruct_write */
2260                 if (!test_bit(R5_OVERWRITE, &dev->flags)
2261                     && i != pd_idx && i != qd_idx
2262                     && (!test_bit(R5_LOCKED, &dev->flags)
2263                             ) &&
2264                     !test_bit(R5_UPTODATE, &dev->flags)) {
2265                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2266                         else {
2267                                 pr_debug("raid6: must_compute: "
2268                                         "disk %d flags=%#lx\n", i, dev->flags);
2269                                 must_compute++;
2270                         }
2271                 }
2272         }
2273         pr_debug("for sector %llu, rcw=%d, must_compute=%d\n",
2274                (unsigned long long)sh->sector, rcw, must_compute);
2275         set_bit(STRIPE_HANDLE, &sh->state);
2276
2277         if (rcw > 0)
2278                 /* want reconstruct write, but need to get some data */
2279                 for (i = disks; i--; ) {
2280                         struct r5dev *dev = &sh->dev[i];
2281                         if (!test_bit(R5_OVERWRITE, &dev->flags)
2282                             && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
2283                             && !test_bit(R5_LOCKED, &dev->flags) &&
2284                             !test_bit(R5_UPTODATE, &dev->flags) &&
2285                             test_bit(R5_Insync, &dev->flags)) {
2286                                 if (
2287                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2288                                         pr_debug("Read_old stripe %llu "
2289                                                 "block %d for Reconstruct\n",
2290                                              (unsigned long long)sh->sector, i);
2291                                         set_bit(R5_LOCKED, &dev->flags);
2292                                         set_bit(R5_Wantread, &dev->flags);
2293                                         s->locked++;
2294                                 } else {
2295                                         pr_debug("Request delayed stripe %llu "
2296                                                 "block %d for Reconstruct\n",
2297                                              (unsigned long long)sh->sector, i);
2298                                         set_bit(STRIPE_DELAYED, &sh->state);
2299                                         set_bit(STRIPE_HANDLE, &sh->state);
2300                                 }
2301                         }
2302                 }
2303         /* now if nothing is locked, and if we have enough data, we can start a
2304          * write request
2305          */
2306         if (s->locked == 0 && rcw == 0 &&
2307             !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2308                 if (must_compute > 0) {
2309                         /* We have failed blocks and need to compute them */
2310                         switch (s->failed) {
2311                         case 0:
2312                                 BUG();
2313                         case 1:
2314                                 compute_block_1(sh, r6s->failed_num[0], 0);
2315                                 break;
2316                         case 2:
2317                                 compute_block_2(sh, r6s->failed_num[0],
2318                                                 r6s->failed_num[1]);
2319                                 break;
2320                         default: /* This request should have been failed? */
2321                                 BUG();
2322                         }
2323                 }
2324
2325                 pr_debug("Computing parity for stripe %llu\n",
2326                         (unsigned long long)sh->sector);
2327                 compute_parity6(sh, RECONSTRUCT_WRITE);
2328                 /* now every locked buffer is ready to be written */
2329                 for (i = disks; i--; )
2330                         if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2331                                 pr_debug("Writing stripe %llu block %d\n",
2332                                        (unsigned long long)sh->sector, i);
2333                                 s->locked++;
2334                                 set_bit(R5_Wantwrite, &sh->dev[i].flags);
2335                         }
2336                 /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2337                 set_bit(STRIPE_INSYNC, &sh->state);
2338
2339                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2340                         atomic_dec(&conf->preread_active_stripes);
2341                         if (atomic_read(&conf->preread_active_stripes) <
2342                             IO_THRESHOLD)
2343                                 md_wakeup_thread(conf->mddev->thread);
2344                 }
2345         }
2346 }
2347
2348 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2349                                 struct stripe_head_state *s, int disks)
2350 {
2351         set_bit(STRIPE_HANDLE, &sh->state);
2352         /* Take one of the following actions:
2353          * 1/ start a check parity operation if (uptodate == disks)
2354          * 2/ finish a check parity operation and act on the result
2355          * 3/ skip to the writeback section if we previously
2356          *    initiated a recovery operation
2357          */
2358         if (s->failed == 0 &&
2359             !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2360                 if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
2361                         BUG_ON(s->uptodate != disks);
2362                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2363                         sh->ops.count++;
2364                         s->uptodate--;
2365                 } else if (
2366                        test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
2367                         clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
2368                         clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
2369
2370                         if (sh->ops.zero_sum_result == 0)
2371                                 /* parity is correct (on disc,
2372                                  * not in buffer any more)
2373                                  */
2374                                 set_bit(STRIPE_INSYNC, &sh->state);
2375                         else {
2376                                 conf->mddev->resync_mismatches +=
2377                                         STRIPE_SECTORS;
2378                                 if (test_bit(
2379                                      MD_RECOVERY_CHECK, &conf->mddev->recovery))
2380                                         /* don't try to repair!! */
2381                                         set_bit(STRIPE_INSYNC, &sh->state);
2382                                 else {
2383                                         set_bit(STRIPE_OP_COMPUTE_BLK,
2384                                                 &sh->ops.pending);
2385                                         set_bit(STRIPE_OP_MOD_REPAIR_PD,
2386                                                 &sh->ops.pending);
2387                                         set_bit(R5_Wantcompute,
2388                                                 &sh->dev[sh->pd_idx].flags);
2389                                         sh->ops.target = sh->pd_idx;
2390                                         sh->ops.count++;
2391                                         s->uptodate++;
2392                                 }
2393                         }
2394                 }
2395         }
2396
2397         /* check if we can clear a parity disk reconstruct */
2398         if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
2399                 test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2400
2401                 clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
2402                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
2403                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
2404                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2405         }
2406
2407         /* Wait for check parity and compute block operations to complete
2408          * before write-back
2409          */
2410         if (!test_bit(STRIPE_INSYNC, &sh->state) &&
2411                 !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
2412                 !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
2413                 struct r5dev *dev;
2414                 /* either failed parity check, or recovery is happening */
2415                 if (s->failed == 0)
2416                         s->failed_num = sh->pd_idx;
2417                 dev = &sh->dev[s->failed_num];
2418                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2419                 BUG_ON(s->uptodate != disks);
2420
2421                 set_bit(R5_LOCKED, &dev->flags);
2422                 set_bit(R5_Wantwrite, &dev->flags);
2423                 if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2424                         sh->ops.count++;
2425
2426                 clear_bit(STRIPE_DEGRADED, &sh->state);
2427                 s->locked++;
2428                 set_bit(STRIPE_INSYNC, &sh->state);
2429         }
2430 }
2431
2432
2433 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2434                                 struct stripe_head_state *s,
2435                                 struct r6_state *r6s, struct page *tmp_page,
2436                                 int disks)
2437 {
2438         int update_p = 0, update_q = 0;
2439         struct r5dev *dev;
2440         int pd_idx = sh->pd_idx;
2441         int qd_idx = r6s->qd_idx;
2442
2443         set_bit(STRIPE_HANDLE, &sh->state);
2444
2445         BUG_ON(s->failed > 2);
2446         BUG_ON(s->uptodate < disks);
2447         /* Want to check and possibly repair P and Q.
2448          * However there could be one 'failed' device, in which
2449          * case we can only check one of them, possibly using the
2450          * other to generate missing data
2451          */
2452
2453         /* If !tmp_page, we cannot do the calculations,
2454          * but as we have set STRIPE_HANDLE, we will soon be called
2455          * by stripe_handle with a tmp_page - just wait until then.
2456          */
2457         if (tmp_page) {
2458                 if (s->failed == r6s->q_failed) {
2459                         /* The only possible failed device holds 'Q', so it
2460                          * makes sense to check P (If anything else were failed,
2461                          * we would have used P to recreate it).
2462                          */
2463                         compute_block_1(sh, pd_idx, 1);
2464                         if (!page_is_zero(sh->dev[pd_idx].page)) {
2465                                 compute_block_1(sh, pd_idx, 0);
2466                                 update_p = 1;
2467                         }
2468                 }
2469                 if (!r6s->q_failed && s->failed < 2) {
2470                         /* q is not failed, and we didn't use it to generate
2471                          * anything, so it makes sense to check it
2472                          */
2473                         memcpy(page_address(tmp_page),
2474                                page_address(sh->dev[qd_idx].page),
2475                                STRIPE_SIZE);
2476                         compute_parity6(sh, UPDATE_PARITY);
2477                         if (memcmp(page_address(tmp_page),
2478                                    page_address(sh->dev[qd_idx].page),
2479                                    STRIPE_SIZE) != 0) {
2480                                 clear_bit(STRIPE_INSYNC, &sh->state);
2481                                 update_q = 1;
2482                         }
2483                 }
2484                 if (update_p || update_q) {
2485                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2486                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2487                                 /* don't try to repair!! */
2488                                 update_p = update_q = 0;
2489                 }
2490
2491                 /* now write out any block on a failed drive,
2492                  * or P or Q if they need it
2493                  */
2494
2495                 if (s->failed == 2) {
2496                         dev = &sh->dev[r6s->failed_num[1]];
2497                         s->locked++;
2498                         set_bit(R5_LOCKED, &dev->flags);
2499                         set_bit(R5_Wantwrite, &dev->flags);
2500                 }
2501                 if (s->failed >= 1) {
2502                         dev = &sh->dev[r6s->failed_num[0]];
2503                         s->locked++;
2504                         set_bit(R5_LOCKED, &dev->flags);
2505                         set_bit(R5_Wantwrite, &dev->flags);
2506                 }
2507
2508                 if (update_p) {
2509                         dev = &sh->dev[pd_idx];
2510                         s->locked++;
2511                         set_bit(R5_LOCKED, &dev->flags);
2512                         set_bit(R5_Wantwrite, &dev->flags);
2513                 }
2514                 if (update_q) {
2515                         dev = &sh->dev[qd_idx];
2516                         s->locked++;
2517                         set_bit(R5_LOCKED, &dev->flags);
2518                         set_bit(R5_Wantwrite, &dev->flags);
2519                 }
2520                 clear_bit(STRIPE_DEGRADED, &sh->state);
2521
2522                 set_bit(STRIPE_INSYNC, &sh->state);
2523         }
2524 }
2525
2526 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
2527                                 struct r6_state *r6s)
2528 {
2529         int i;
2530
2531         /* We have read all the blocks in this stripe and now we need to
2532          * copy some of them into a target stripe for expand.
2533          */
2534         struct dma_async_tx_descriptor *tx = NULL;
2535         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2536         for (i = 0; i < sh->disks; i++)
2537                 if (i != sh->pd_idx && (!r6s || i != r6s->qd_idx)) {
2538                         int dd_idx, pd_idx, j;
2539                         struct stripe_head *sh2;
2540
2541                         sector_t bn = compute_blocknr(sh, i);
2542                         sector_t s = raid5_compute_sector(bn, conf->raid_disks,
2543                                                 conf->raid_disks -
2544                                                 conf->max_degraded, &dd_idx,
2545                                                 &pd_idx, conf);
2546                         sh2 = get_active_stripe(conf, s, conf->raid_disks,
2547                                                 pd_idx, 1);
2548                         if (sh2 == NULL)
2549                                 /* so far only the early blocks of this stripe
2550                                  * have been requested.  When later blocks
2551                                  * get requested, we will try again
2552                                  */
2553                                 continue;
2554                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2555                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2556                                 /* must have already done this block */
2557                                 release_stripe(sh2);
2558                                 continue;
2559                         }
2560
2561                         /* place all the copies on one channel */
2562                         tx = async_memcpy(sh2->dev[dd_idx].page,
2563                                 sh->dev[i].page, 0, 0, STRIPE_SIZE,
2564                                 ASYNC_TX_DEP_ACK, tx, NULL, NULL);
2565
2566                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2567                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2568                         for (j = 0; j < conf->raid_disks; j++)
2569                                 if (j != sh2->pd_idx &&
2570                                     (!r6s || j != raid6_next_disk(sh2->pd_idx,
2571                                                                  sh2->disks)) &&
2572                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
2573                                         break;
2574                         if (j == conf->raid_disks) {
2575                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
2576                                 set_bit(STRIPE_HANDLE, &sh2->state);
2577                         }
2578                         release_stripe(sh2);
2579
2580                 }
2581         /* done submitting copies, wait for them to complete */
2582         if (tx) {
2583                 async_tx_ack(tx);
2584                 dma_wait_for_async_tx(tx);
2585         }
2586 }
2587
2588 /*
2589  * handle_stripe - do things to a stripe.
2590  *
2591  * We lock the stripe and then examine the state of various bits
2592  * to see what needs to be done.
2593  * Possible results:
2594  *    return some read request which now have data
2595  *    return some write requests which are safely on disc
2596  *    schedule a read on some buffers
2597  *    schedule a write of some buffers
2598  *    return confirmation of parity correctness
2599  *
2600  * buffers are taken off read_list or write_list, and bh_cache buffers
2601  * get BH_Lock set before the stripe lock is released.
2602  *
2603  */
2604
2605 static void handle_stripe5(struct stripe_head *sh)
2606 {
2607         raid5_conf_t *conf = sh->raid_conf;
2608         int disks = sh->disks, i;
2609         struct bio *return_bi = NULL;
2610         struct stripe_head_state s;
2611         struct r5dev *dev;
2612         unsigned long pending = 0;
2613
2614         memset(&s, 0, sizeof(s));
2615         pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d "
2616                 "ops=%lx:%lx:%lx\n", (unsigned long long)sh->sector, sh->state,
2617                 atomic_read(&sh->count), sh->pd_idx,
2618                 sh->ops.pending, sh->ops.ack, sh->ops.complete);
2619
2620         spin_lock(&sh->lock);
2621         clear_bit(STRIPE_HANDLE, &sh->state);
2622         clear_bit(STRIPE_DELAYED, &sh->state);
2623
2624         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2625         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2626         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2627         /* Now to look around and see what can be done */
2628
2629         /* clean-up completed biofill operations */
2630         if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
2631                 clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
2632                 clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
2633                 clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
2634         }
2635
2636         rcu_read_lock();
2637         for (i=disks; i--; ) {
2638                 mdk_rdev_t *rdev;
2639                 struct r5dev *dev = &sh->dev[i];
2640                 clear_bit(R5_Insync, &dev->flags);
2641
2642                 pr_debug("check %d: state 0x%lx toread %p read %p write %p "
2643                         "written %p\n", i, dev->flags, dev->toread, dev->read,
2644                         dev->towrite, dev->written);
2645
2646                 /* maybe we can request a biofill operation
2647                  *
2648                  * new wantfill requests are only permitted while
2649                  * STRIPE_OP_BIOFILL is clear
2650                  */
2651                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
2652                         !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
2653                         set_bit(R5_Wantfill, &dev->flags);
2654
2655                 /* now count some things */
2656                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2657                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2658                 if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;
2659
2660                 if (test_bit(R5_Wantfill, &dev->flags))
2661                         s.to_fill++;
2662                 else if (dev->toread)
2663                         s.to_read++;
2664                 if (dev->towrite) {
2665                         s.to_write++;
2666                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2667                                 s.non_overwrite++;
2668                 }
2669                 if (dev->written)
2670                         s.written++;
2671                 rdev = rcu_dereference(conf->disks[i].rdev);
2672                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2673                         /* The ReadError flag will just be confusing now */
2674                         clear_bit(R5_ReadError, &dev->flags);
2675                         clear_bit(R5_ReWrite, &dev->flags);
2676                 }
2677                 if (!rdev || !test_bit(In_sync, &rdev->flags)
2678                     || test_bit(R5_ReadError, &dev->flags)) {
2679                         s.failed++;
2680                         s.failed_num = i;
2681                 } else
2682                         set_bit(R5_Insync, &dev->flags);
2683         }
2684         rcu_read_unlock();
2685
2686         if (s.to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
2687                 sh->ops.count++;
2688
2689         pr_debug("locked=%d uptodate=%d to_read=%d"
2690                 " to_write=%d failed=%d failed_num=%d\n",
2691                 s.locked, s.uptodate, s.to_read, s.to_write,
2692                 s.failed, s.failed_num);
2693         /* check if the array has lost two devices and, if so, some requests might
2694          * need to be failed
2695          */
2696         if (s.failed > 1 && s.to_read+s.to_write+s.written)
2697                 handle_requests_to_failed_array(conf, sh, &s, disks,
2698                                                 &return_bi);
2699         if (s.failed > 1 && s.syncing) {
2700                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2701                 clear_bit(STRIPE_SYNCING, &sh->state);
2702                 s.syncing = 0;
2703         }
2704
2705         /* might be able to return some write requests if the parity block
2706          * is safe, or on a failed drive
2707          */
2708         dev = &sh->dev[sh->pd_idx];
2709         if ( s.written &&
2710              ((test_bit(R5_Insync, &dev->flags) &&
2711                !test_bit(R5_LOCKED, &dev->flags) &&
2712                test_bit(R5_UPTODATE, &dev->flags)) ||
2713                (s.failed == 1 && s.failed_num == sh->pd_idx)))
2714                 handle_completed_write_requests(conf, sh, disks, &return_bi);
2715
2716         /* Now we might consider reading some blocks, either to check/generate
2717          * parity, or to satisfy requests
2718          * or to load a block that is being partially written.
2719          */
2720         if (s.to_read || s.non_overwrite ||
2721             (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding ||
2722             test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
2723                 handle_issuing_new_read_requests5(sh, &s, disks);
2724
2725         /* Now we check to see if any write operations have recently
2726          * completed
2727          */
2728
2729         /* leave prexor set until postxor is done, allows us to distinguish
2730          * a rmw from a rcw during biodrain
2731          */
2732         if (test_bit(STRIPE_OP_PREXOR, &sh->ops.complete) &&
2733                 test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
2734
2735                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
2736                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.ack);
2737                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
2738
2739                 for (i = disks; i--; )
2740                         clear_bit(R5_Wantprexor, &sh->dev[i].flags);
2741         }
2742
2743         /* if only POSTXOR is set then this is an 'expand' postxor */
2744         if (test_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete) &&
2745                 test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
2746
2747                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
2748                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.ack);
2749                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
2750
2751                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
2752                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
2753                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
2754
2755                 /* All the 'written' buffers and the parity block are ready to
2756                  * be written back to disk
2757                  */
2758                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
2759                 for (i = disks; i--; ) {
2760                         dev = &sh->dev[i];
2761                         if (test_bit(R5_LOCKED, &dev->flags) &&
2762                                 (i == sh->pd_idx || dev->written)) {
2763                                 pr_debug("Writing block %d\n", i);
2764                                 set_bit(R5_Wantwrite, &dev->flags);
2765                                 if (!test_and_set_bit(
2766                                     STRIPE_OP_IO, &sh->ops.pending))
2767                                         sh->ops.count++;
2768                                 if (!test_bit(R5_Insync, &dev->flags) ||
2769                                     (i == sh->pd_idx && s.failed == 0))
2770                                         set_bit(STRIPE_INSYNC, &sh->state);
2771                         }
2772                 }
2773                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2774                         atomic_dec(&conf->preread_active_stripes);
2775                         if (atomic_read(&conf->preread_active_stripes) <
2776                                 IO_THRESHOLD)
2777                                 md_wakeup_thread(conf->mddev->thread);
2778                 }
2779         }
2780
2781         /* Now to consider new write requests and what else, if anything
2782          * should be read.  We do not handle new writes when:
2783          * 1/ A 'write' operation (copy+xor) is already in flight.
2784          * 2/ A 'check' operation is in flight, as it may clobber the parity
2785          *    block.
2786          */
2787         if (s.to_write && !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending) &&
2788                           !test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
2789                 handle_issuing_new_write_requests5(conf, sh, &s, disks);
2790
2791         /* maybe we need to check and possibly fix the parity for this stripe
2792          * Any reads will already have been scheduled, so we just see if enough
2793          * data is available.  The parity check is held off while parity
2794          * dependent operations are in flight.
2795          */
2796         if ((s.syncing && s.locked == 0 &&
2797              !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
2798              !test_bit(STRIPE_INSYNC, &sh->state)) ||
2799               test_bit(STRIPE_OP_CHECK, &sh->ops.pending) ||
2800               test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending))
2801                 handle_parity_checks5(conf, sh, &s, disks);
2802
2803         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2804                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2805                 clear_bit(STRIPE_SYNCING, &sh->state);
2806         }
2807
2808         /* If the failed drive is just a ReadError, then we might need to progress
2809          * the repair/check process
2810          */
2811         if (s.failed == 1 && !conf->mddev->ro &&
2812             test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
2813             && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
2814             && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
2815                 ) {
2816                 dev = &sh->dev[s.failed_num];
2817                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2818                         set_bit(R5_Wantwrite, &dev->flags);
2819                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2820                                 sh->ops.count++;
2821                         set_bit(R5_ReWrite, &dev->flags);
2822                         set_bit(R5_LOCKED, &dev->flags);
2823                         s.locked++;
2824                 } else {
2825                         /* let's read it back */
2826                         set_bit(R5_Wantread, &dev->flags);
2827                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2828                                 sh->ops.count++;
2829                         set_bit(R5_LOCKED, &dev->flags);
2830                         s.locked++;
2831                 }
2832         }
2833
2834         /* Finish postxor operations initiated by the expansion
2835          * process
2836          */
2837         if (test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete) &&
2838                 !test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending)) {
2839
2840                 clear_bit(STRIPE_EXPANDING, &sh->state);
2841
2842                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
2843                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
2844                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
2845
2846                 for (i = conf->raid_disks; i--; ) {
2847                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2848                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2849                                 sh->ops.count++;
2850                 }
2851         }
2852
2853         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
2854                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2855                 /* Need to write out all blocks after computing parity */
2856                 sh->disks = conf->raid_disks;
2857                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2858                         conf->raid_disks);
2859                 s.locked += handle_write_operations5(sh, 1, 1);
2860         } else if (s.expanded &&
2861                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2862                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
2863                 atomic_dec(&conf->reshape_stripes);
2864                 wake_up(&conf->wait_for_overlap);
2865                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2866         }
2867
2868         if (s.expanding && s.locked == 0 &&
2869             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
2870                 handle_stripe_expansion(conf, sh, NULL);
2871
2872         if (sh->ops.count)
2873                 pending = get_stripe_work(sh);
2874
2875         spin_unlock(&sh->lock);
2876
2877         if (pending)
2878                 raid5_run_ops(sh, pending);
2879
2880         return_io(return_bi);
2881
2882 }
2883
2884 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
2885 {
2886         raid6_conf_t *conf = sh->raid_conf;
2887         int disks = sh->disks;
2888         struct bio *return_bi = NULL;
2889         int i, pd_idx = sh->pd_idx;
2890         struct stripe_head_state s;
2891         struct r6_state r6s;
2892         struct r5dev *dev, *pdev, *qdev;
2893
2894         r6s.qd_idx = raid6_next_disk(pd_idx, disks);
2895         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
2896                 "pd_idx=%d, qd_idx=%d\n",
2897                (unsigned long long)sh->sector, sh->state,
2898                atomic_read(&sh->count), pd_idx, r6s.qd_idx);
2899         memset(&s, 0, sizeof(s));
2900
2901         spin_lock(&sh->lock);
2902         clear_bit(STRIPE_HANDLE, &sh->state);
2903         clear_bit(STRIPE_DELAYED, &sh->state);
2904
2905         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2906         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2907         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2908         /* Now to look around and see what can be done */
2909
2910         rcu_read_lock();
2911         for (i=disks; i--; ) {
2912                 mdk_rdev_t *rdev;
2913                 dev = &sh->dev[i];
2914                 clear_bit(R5_Insync, &dev->flags);
2915
2916                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
2917                         i, dev->flags, dev->toread, dev->towrite, dev->written);
2918                 /* maybe we can reply to a read */
2919                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
2920                         struct bio *rbi, *rbi2;
2921                         pr_debug("Return read for disc %d\n", i);
2922                         spin_lock_irq(&conf->device_lock);
2923                         rbi = dev->toread;
2924                         dev->toread = NULL;
2925                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
2926                                 wake_up(&conf->wait_for_overlap);
2927                         spin_unlock_irq(&conf->device_lock);
2928                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
2929                                 copy_data(0, rbi, dev->page, dev->sector);
2930                                 rbi2 = r5_next_bio(rbi, dev->sector);
2931                                 spin_lock_irq(&conf->device_lock);
2932                                 if (--rbi->bi_phys_segments == 0) {
2933                                         rbi->bi_next = return_bi;
2934                                         return_bi = rbi;
2935                                 }
2936                                 spin_unlock_irq(&conf->device_lock);
2937                                 rbi = rbi2;
2938                         }
2939                 }
2940
2941                 /* now count some things */
2942                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2943                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2944
2945
2946                 if (dev->toread)
2947                         s.to_read++;
2948                 if (dev->towrite) {
2949                         s.to_write++;
2950                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2951                                 s.non_overwrite++;
2952                 }
2953                 if (dev->written)
2954                         s.written++;
2955                 rdev = rcu_dereference(conf->disks[i].rdev);
2956                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2957                         /* The ReadError flag will just be confusing now */
2958                         clear_bit(R5_ReadError, &dev->flags);
2959                         clear_bit(R5_ReWrite, &dev->flags);
2960                 }
2961                 if (!rdev || !test_bit(In_sync, &rdev->flags)
2962                     || test_bit(R5_ReadError, &dev->flags)) {
2963                         if (s.failed < 2)
2964                                 r6s.failed_num[s.failed] = i;
2965                         s.failed++;
2966                 } else
2967                         set_bit(R5_Insync, &dev->flags);
2968         }
2969         rcu_read_unlock();
2970         pr_debug("locked=%d uptodate=%d to_read=%d"
2971                " to_write=%d failed=%d failed_num=%d,%d\n",
2972                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
2973                r6s.failed_num[0], r6s.failed_num[1]);
2974         /* check if the array has lost >2 devices and, if so, some requests
2975          * might need to be failed
2976          */
2977         if (s.failed > 2 && s.to_read+s.to_write+s.written)
2978                 handle_requests_to_failed_array(conf, sh, &s, disks,
2979                                                 &return_bi);
2980         if (s.failed > 2 && s.syncing) {
2981                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2982                 clear_bit(STRIPE_SYNCING, &sh->state);
2983                 s.syncing = 0;
2984         }
2985
2986         /*
2987          * might be able to return some write requests if the parity blocks
2988          * are safe, or on a failed drive
2989          */
2990         pdev = &sh->dev[pd_idx];
2991         r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
2992                 || (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
2993         qdev = &sh->dev[r6s.qd_idx];
2994         r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == r6s.qd_idx)
2995                 || (s.failed >= 2 && r6s.failed_num[1] == r6s.qd_idx);
2996
2997         if ( s.written &&
2998              ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
2999                              && !test_bit(R5_LOCKED, &pdev->flags)
3000                              && test_bit(R5_UPTODATE, &pdev->flags)))) &&
3001              ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3002                              && !test_bit(R5_LOCKED, &qdev->flags)
3003                              && test_bit(R5_UPTODATE, &qdev->flags)))))
3004                 handle_completed_write_requests(conf, sh, disks, &return_bi);
3005
3006         /* Now we might consider reading some blocks, either to check/generate
3007          * parity, or to satisfy requests
3008          * or to load a block that is being partially written.
3009          */
3010         if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
3011             (s.syncing && (s.uptodate < disks)) || s.expanding)
3012                 handle_issuing_new_read_requests6(sh, &s, &r6s, disks);
3013
3014         /* now to consider writing and what else, if anything should be read */
3015         if (s.to_write)
3016                 handle_issuing_new_write_requests6(conf, sh, &s, &r6s, disks);
3017
3018         /* maybe we need to check and possibly fix the parity for this stripe
3019          * Any reads will already have been scheduled, so we just see if enough
3020          * data is available
3021          */
3022         if (s.syncing && s.locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state))
3023                 handle_parity_checks6(conf, sh, &s, &r6s, tmp_page, disks);
3024
3025         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
3026                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
3027                 clear_bit(STRIPE_SYNCING, &sh->state);
3028         }
3029
3030         /* If the failed drives are just a ReadError, then we might need
3031          * to progress the repair/check process
3032          */
3033         if (s.failed <= 2 && !conf->mddev->ro)
3034                 for (i = 0; i < s.failed; i++) {
3035                         dev = &sh->dev[r6s.failed_num[i]];
3036                         if (test_bit(R5_ReadError, &dev->flags)
3037                             && !test_bit(R5_LOCKED, &dev->flags)
3038                             && test_bit(R5_UPTODATE, &dev->flags)
3039                                 ) {
3040                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3041                                         set_bit(R5_Wantwrite, &dev->flags);
3042                                         set_bit(R5_ReWrite, &dev->flags);
3043                                         set_bit(R5_LOCKED, &dev->flags);
3044                                 } else {
3045                                         /* let's read it back */
3046                                         set_bit(R5_Wantread, &dev->flags);
3047                                         set_bit(R5_LOCKED, &dev->flags);
3048                                 }
3049                         }
3050                 }
3051
3052         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
3053                 /* Need to write out all blocks after computing P&Q */
3054                 sh->disks = conf->raid_disks;
3055                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
3056                                              conf->raid_disks);
3057                 compute_parity6(sh, RECONSTRUCT_WRITE);
3058                 for (i = conf->raid_disks ; i-- ;  ) {
3059                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3060                         s.locked++;
3061                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3062                 }
3063                 clear_bit(STRIPE_EXPANDING, &sh->state);
3064         } else if (s.expanded) {
3065                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3066                 atomic_dec(&conf->reshape_stripes);
3067                 wake_up(&conf->wait_for_overlap);
3068                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3069         }
3070
3071         if (s.expanding && s.locked == 0 &&
3072             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
3073                 handle_stripe_expansion(conf, sh, &r6s);
3074
3075         spin_unlock(&sh->lock);
3076
3077         return_io(return_bi);
3078
3079         for (i=disks; i-- ;) {
3080                 int rw;
3081                 struct bio *bi;
3082                 mdk_rdev_t *rdev;
3083                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
3084                         rw = WRITE;
3085                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
3086                         rw = READ;
3087                 else
3088                         continue;
3089
3090                 bi = &sh->dev[i].req;
3091
3092                 bi->bi_rw = rw;
3093                 if (rw == WRITE)
3094                         bi->bi_end_io = raid5_end_write_request;
3095                 else
3096                         bi->bi_end_io = raid5_end_read_request;
3097
3098                 rcu_read_lock();
3099                 rdev = rcu_dereference(conf->disks[i].rdev);
3100                 if (rdev && test_bit(Faulty, &rdev->flags))
3101                         rdev = NULL;
3102                 if (rdev)
3103                         atomic_inc(&rdev->nr_pending);
3104                 rcu_read_unlock();
3105
3106                 if (rdev) {
3107                         if (s.syncing || s.expanding || s.expanded)
3108                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
3109
3110                         bi->bi_bdev = rdev->bdev;
3111                         pr_debug("for %llu schedule op %ld on disc %d\n",
3112                                 (unsigned long long)sh->sector, bi->bi_rw, i);
3113                         atomic_inc(&sh->count);
3114                         bi->bi_sector = sh->sector + rdev->data_offset;
3115                         bi->bi_flags = 1 << BIO_UPTODATE;
3116                         bi->bi_vcnt = 1;
3117                         bi->bi_max_vecs = 1;
3118                         bi->bi_idx = 0;
3119                         bi->bi_io_vec = &sh->dev[i].vec;
3120                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
3121                         bi->bi_io_vec[0].bv_offset = 0;
3122                         bi->bi_size = STRIPE_SIZE;
3123                         bi->bi_next = NULL;
3124                         if (rw == WRITE &&
3125                             test_bit(R5_ReWrite, &sh->dev[i].flags))
3126                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
3127                         generic_make_request(bi);
3128                 } else {
3129                         if (rw == WRITE)
3130                                 set_bit(STRIPE_DEGRADED, &sh->state);
3131                         pr_debug("skip op %ld on disc %d for sector %llu\n",
3132                                 bi->bi_rw, i, (unsigned long long)sh->sector);
3133                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
3134                         set_bit(STRIPE_HANDLE, &sh->state);
3135                 }
3136         }
3137 }
3138
3139 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
3140 {
3141         if (sh->raid_conf->level == 6)
3142                 handle_stripe6(sh, tmp_page);
3143         else
3144                 handle_stripe5(sh);
3145 }
3146
3147
3148
3149 static void raid5_activate_delayed(raid5_conf_t *conf)
3150 {
3151         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3152                 while (!list_empty(&conf->delayed_list)) {
3153                         struct list_head *l = conf->delayed_list.next;
3154                         struct stripe_head *sh;
3155                         sh = list_entry(l, struct stripe_head, lru);
3156                         list_del_init(l);
3157                         clear_bit(STRIPE_DELAYED, &sh->state);
3158                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3159                                 atomic_inc(&conf->preread_active_stripes);
3160                         list_add_tail(&sh->lru, &conf->handle_list);
3161                 }
3162         } else
3163                 blk_plug_device(conf->mddev->queue);
3164 }
3165
3166 static void activate_bit_delay(raid5_conf_t *conf)
3167 {
3168         /* device_lock is held */
3169         struct list_head head;
3170         list_add(&head, &conf->bitmap_list);
3171         list_del_init(&conf->bitmap_list);
3172         while (!list_empty(&head)) {
3173                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3174                 list_del_init(&sh->lru);
3175                 atomic_inc(&sh->count);
3176                 __release_stripe(conf, sh);
3177         }
3178 }
3179
3180 static void unplug_slaves(mddev_t *mddev)
3181 {
3182         raid5_conf_t *conf = mddev_to_conf(mddev);
3183         int i;
3184
3185         rcu_read_lock();
3186         for (i=0; i<mddev->raid_disks; i++) {
3187                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3188                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
3189                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
3190
3191                         atomic_inc(&rdev->nr_pending);
3192                         rcu_read_unlock();
3193
3194                         blk_unplug(r_queue);
3195
3196                         rdev_dec_pending(rdev, mddev);
3197                         rcu_read_lock();
3198                 }
3199         }
3200         rcu_read_unlock();
3201 }
3202
3203 static void raid5_unplug_device(struct request_queue *q)
3204 {
3205         mddev_t *mddev = q->queuedata;
3206         raid5_conf_t *conf = mddev_to_conf(mddev);
3207         unsigned long flags;
3208
3209         spin_lock_irqsave(&conf->device_lock, flags);
3210
3211         if (blk_remove_plug(q)) {
3212                 conf->seq_flush++;
3213                 raid5_activate_delayed(conf);
3214         }
3215         md_wakeup_thread(mddev->thread);
3216
3217         spin_unlock_irqrestore(&conf->device_lock, flags);
3218
3219         unplug_slaves(mddev);
3220 }
3221
3222 static int raid5_congested(void *data, int bits)
3223 {
3224         mddev_t *mddev = data;
3225         raid5_conf_t *conf = mddev_to_conf(mddev);
3226
3227         /* No difference between reads and writes.  Just check
3228          * how busy the stripe_cache is
3229          */
3230         if (conf->inactive_blocked)
3231                 return 1;
3232         if (conf->quiesce)
3233                 return 1;
3234         if (list_empty_careful(&conf->inactive_list))
3235                 return 1;
3236
3237         return 0;
3238 }
3239
3240 /* We want read requests to align with chunks where possible,
3241  * but write requests don't need to.
3242  */
3243 static int raid5_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec)
3244 {
3245         mddev_t *mddev = q->queuedata;
3246         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3247         int max;
3248         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3249         unsigned int bio_sectors = bio->bi_size >> 9;
3250
3251         if (bio_data_dir(bio) == WRITE)
3252                 return biovec->bv_len; /* always allow writes to be mergeable */
3253
3254         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3255         if (max < 0) max = 0;
3256         if (max <= biovec->bv_len && bio_sectors == 0)
3257                 return biovec->bv_len;
3258         else
3259                 return max;
3260 }
3261
3262
3263 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3264 {
3265         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3266         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3267         unsigned int bio_sectors = bio->bi_size >> 9;
3268
3269         return  chunk_sectors >=
3270                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3271 }
3272
3273 /*
3274  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3275  *  later sampled by raid5d.
3276  */
3277 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3278 {
3279         unsigned long flags;
3280
3281         spin_lock_irqsave(&conf->device_lock, flags);
3282
3283         bi->bi_next = conf->retry_read_aligned_list;
3284         conf->retry_read_aligned_list = bi;
3285
3286         spin_unlock_irqrestore(&conf->device_lock, flags);
3287         md_wakeup_thread(conf->mddev->thread);
3288 }
3289
3290
3291 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3292 {
3293         struct bio *bi;
3294
3295         bi = conf->retry_read_aligned;
3296         if (bi) {
3297                 conf->retry_read_aligned = NULL;
3298                 return bi;
3299         }
3300         bi = conf->retry_read_aligned_list;
3301         if(bi) {
3302                 conf->retry_read_aligned_list = bi->bi_next;
3303                 bi->bi_next = NULL;
3304                 bi->bi_phys_segments = 1; /* biased count of active stripes */
3305                 bi->bi_hw_segments = 0; /* count of processed stripes */
3306         }
3307
3308         return bi;
3309 }
3310
3311
3312 /*
3313  *  The "raid5_align_endio" should check if the read succeeded and if it
3314  *  did, call bio_endio on the original bio (having bio_put the new bio
3315  *  first).
3316  *  If the read failed..
3317  */
3318 static void raid5_align_endio(struct bio *bi, int error)
3319 {
3320         struct bio* raid_bi  = bi->bi_private;
3321         mddev_t *mddev;
3322         raid5_conf_t *conf;
3323         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3324         mdk_rdev_t *rdev;
3325
3326         bio_put(bi);
3327
3328         mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
3329         conf = mddev_to_conf(mddev);
3330         rdev = (void*)raid_bi->bi_next;
3331         raid_bi->bi_next = NULL;
3332
3333         rdev_dec_pending(rdev, conf->mddev);
3334
3335         if (!error && uptodate) {
3336                 bio_endio(raid_bi, 0);
3337                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3338                         wake_up(&conf->wait_for_stripe);
3339                 return;
3340         }
3341
3342
3343         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3344
3345         add_bio_to_retry(raid_bi, conf);
3346 }
3347
3348 static int bio_fits_rdev(struct bio *bi)
3349 {
3350         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3351
3352         if ((bi->bi_size>>9) > q->max_sectors)
3353                 return 0;
3354         blk_recount_segments(q, bi);
3355         if (bi->bi_phys_segments > q->max_phys_segments ||
3356             bi->bi_hw_segments > q->max_hw_segments)
3357                 return 0;
3358
3359         if (q->merge_bvec_fn)
3360                 /* it's too hard to apply the merge_bvec_fn at this stage,
3361                  * just just give up
3362                  */
3363                 return 0;
3364
3365         return 1;
3366 }
3367
3368
3369 static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
3370 {
3371         mddev_t *mddev = q->queuedata;
3372         raid5_conf_t *conf = mddev_to_conf(mddev);
3373         const unsigned int raid_disks = conf->raid_disks;
3374         const unsigned int data_disks = raid_disks - conf->max_degraded;
3375         unsigned int dd_idx, pd_idx;
3376         struct bio* align_bi;
3377         mdk_rdev_t *rdev;
3378
3379         if (!in_chunk_boundary(mddev, raid_bio)) {
3380                 pr_debug("chunk_aligned_read : non aligned\n");
3381                 return 0;
3382         }
3383         /*
3384          * use bio_clone to make a copy of the bio
3385          */
3386         align_bi = bio_clone(raid_bio, GFP_NOIO);
3387         if (!align_bi)
3388                 return 0;
3389         /*
3390          *   set bi_end_io to a new function, and set bi_private to the
3391          *     original bio.
3392          */
3393         align_bi->bi_end_io  = raid5_align_endio;
3394         align_bi->bi_private = raid_bio;
3395         /*
3396          *      compute position
3397          */
3398         align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
3399                                         raid_disks,
3400                                         data_disks,
3401                                         &dd_idx,
3402                                         &pd_idx,
3403                                         conf);
3404
3405         rcu_read_lock();
3406         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3407         if (rdev && test_bit(In_sync, &rdev->flags)) {
3408                 atomic_inc(&rdev->nr_pending);
3409                 rcu_read_unlock();
3410                 raid_bio->bi_next = (void*)rdev;
3411                 align_bi->bi_bdev =  rdev->bdev;
3412                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3413                 align_bi->bi_sector += rdev->data_offset;
3414
3415                 if (!bio_fits_rdev(align_bi)) {
3416                         /* too big in some way */
3417                         bio_put(align_bi);
3418                         rdev_dec_pending(rdev, mddev);
3419                         return 0;
3420                 }
3421
3422                 spin_lock_irq(&conf->device_lock);
3423                 wait_event_lock_irq(conf->wait_for_stripe,
3424                                     conf->quiesce == 0,
3425                                     conf->device_lock, /* nothing */);
3426                 atomic_inc(&conf->active_aligned_reads);
3427                 spin_unlock_irq(&conf->device_lock);
3428
3429                 generic_make_request(align_bi);
3430                 return 1;
3431         } else {
3432                 rcu_read_unlock();
3433                 bio_put(align_bi);
3434                 return 0;
3435         }
3436 }
3437
3438
3439 static int make_request(struct request_queue *q, struct bio * bi)
3440 {
3441         mddev_t *mddev = q->queuedata;
3442         raid5_conf_t *conf = mddev_to_conf(mddev);
3443         unsigned int dd_idx, pd_idx;
3444         sector_t new_sector;
3445         sector_t logical_sector, last_sector;
3446         struct stripe_head *sh;
3447         const int rw = bio_data_dir(bi);
3448         int remaining;
3449
3450         if (unlikely(bio_barrier(bi))) {
3451                 bio_endio(bi, -EOPNOTSUPP);
3452                 return 0;
3453         }
3454
3455         md_write_start(mddev, bi);
3456
3457         disk_stat_inc(mddev->gendisk, ios[rw]);
3458         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
3459
3460         if (rw == READ &&
3461              mddev->reshape_position == MaxSector &&
3462              chunk_aligned_read(q,bi))
3463                 return 0;
3464
3465         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3466         last_sector = bi->bi_sector + (bi->bi_size>>9);
3467         bi->bi_next = NULL;
3468         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
3469
3470         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
3471                 DEFINE_WAIT(w);
3472                 int disks, data_disks;
3473
3474         retry:
3475                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
3476                 if (likely(conf->expand_progress == MaxSector))
3477                         disks = conf->raid_disks;
3478                 else {
3479                         /* spinlock is needed as expand_progress may be
3480                          * 64bit on a 32bit platform, and so it might be
3481                          * possible to see a half-updated value
3482                          * Ofcourse expand_progress could change after
3483                          * the lock is dropped, so once we get a reference
3484                          * to the stripe that we think it is, we will have
3485                          * to check again.
3486                          */
3487                         spin_lock_irq(&conf->device_lock);
3488                         disks = conf->raid_disks;
3489                         if (logical_sector >= conf->expand_progress)
3490                                 disks = conf->previous_raid_disks;
3491                         else {
3492                                 if (logical_sector >= conf->expand_lo) {
3493                                         spin_unlock_irq(&conf->device_lock);
3494                                         schedule();
3495                                         goto retry;
3496                                 }
3497                         }
3498                         spin_unlock_irq(&conf->device_lock);
3499                 }
3500                 data_disks = disks - conf->max_degraded;
3501
3502                 new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
3503                                                   &dd_idx, &pd_idx, conf);
3504                 pr_debug("raid5: make_request, sector %llu logical %llu\n",
3505                         (unsigned long long)new_sector, 
3506                         (unsigned long long)logical_sector);
3507
3508                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
3509                 if (sh) {
3510                         if (unlikely(conf->expand_progress != MaxSector)) {
3511                                 /* expansion might have moved on while waiting for a
3512                                  * stripe, so we must do the range check again.
3513                                  * Expansion could still move past after this
3514                                  * test, but as we are holding a reference to
3515                                  * 'sh', we know that if that happens,
3516                                  *  STRIPE_EXPANDING will get set and the expansion
3517                                  * won't proceed until we finish with the stripe.
3518                                  */
3519                                 int must_retry = 0;
3520                                 spin_lock_irq(&conf->device_lock);
3521                                 if (logical_sector <  conf->expand_progress &&
3522                                     disks == conf->previous_raid_disks)
3523                                         /* mismatch, need to try again */
3524                                         must_retry = 1;
3525                                 spin_unlock_irq(&conf->device_lock);
3526                                 if (must_retry) {
3527                                         release_stripe(sh);
3528                                         goto retry;
3529                                 }
3530                         }
3531                         /* FIXME what if we get a false positive because these
3532                          * are being updated.
3533                          */
3534                         if (logical_sector >= mddev->suspend_lo &&
3535                             logical_sector < mddev->suspend_hi) {
3536                                 release_stripe(sh);
3537                                 schedule();
3538                                 goto retry;
3539                         }
3540
3541                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
3542                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
3543                                 /* Stripe is busy expanding or
3544                                  * add failed due to overlap.  Flush everything
3545                                  * and wait a while
3546                                  */
3547                                 raid5_unplug_device(mddev->queue);
3548                                 release_stripe(sh);
3549                                 schedule();
3550                                 goto retry;
3551                         }
3552                         finish_wait(&conf->wait_for_overlap, &w);
3553                         set_bit(STRIPE_HANDLE, &sh->state);
3554                         clear_bit(STRIPE_DELAYED, &sh->state);
3555                         release_stripe(sh);
3556                 } else {
3557                         /* cannot get stripe for read-ahead, just give-up */
3558                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3559                         finish_wait(&conf->wait_for_overlap, &w);
3560                         break;
3561                 }
3562                         
3563         }
3564         spin_lock_irq(&conf->device_lock);
3565         remaining = --bi->bi_phys_segments;
3566         spin_unlock_irq(&conf->device_lock);
3567         if (remaining == 0) {
3568
3569                 if ( rw == WRITE )
3570                         md_write_end(mddev);
3571
3572                 bi->bi_end_io(bi,
3573                               test_bit(BIO_UPTODATE, &bi->bi_flags)
3574                                 ? 0 : -EIO);
3575         }
3576         return 0;
3577 }
3578
3579 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
3580 {
3581         /* reshaping is quite different to recovery/resync so it is
3582          * handled quite separately ... here.
3583          *
3584          * On each call to sync_request, we gather one chunk worth of
3585          * destination stripes and flag them as expanding.
3586          * Then we find all the source stripes and request reads.
3587          * As the reads complete, handle_stripe will copy the data
3588          * into the destination stripe and release that stripe.
3589          */
3590         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3591         struct stripe_head *sh;
3592         int pd_idx;
3593         sector_t first_sector, last_sector;
3594         int raid_disks = conf->previous_raid_disks;
3595         int data_disks = raid_disks - conf->max_degraded;
3596         int new_data_disks = conf->raid_disks - conf->max_degraded;
3597         int i;
3598         int dd_idx;
3599         sector_t writepos, safepos, gap;
3600
3601         if (sector_nr == 0 &&
3602             conf->expand_progress != 0) {
3603                 /* restarting in the middle, skip the initial sectors */
3604                 sector_nr = conf->expand_progress;
3605                 sector_div(sector_nr, new_data_disks);
3606                 *skipped = 1;
3607                 return sector_nr;
3608         }
3609
3610         /* we update the metadata when there is more than 3Meg
3611          * in the block range (that is rather arbitrary, should
3612          * probably be time based) or when the data about to be
3613          * copied would over-write the source of the data at
3614          * the front of the range.
3615          * i.e. one new_stripe forward from expand_progress new_maps
3616          * to after where expand_lo old_maps to
3617          */
3618         writepos = conf->expand_progress +
3619                 conf->chunk_size/512*(new_data_disks);
3620         sector_div(writepos, new_data_disks);
3621         safepos = conf->expand_lo;
3622         sector_div(safepos, data_disks);
3623         gap = conf->expand_progress - conf->expand_lo;
3624
3625         if (writepos >= safepos ||
3626             gap > (new_data_disks)*3000*2 /*3Meg*/) {
3627                 /* Cannot proceed until we've updated the superblock... */
3628                 wait_event(conf->wait_for_overlap,
3629                            atomic_read(&conf->reshape_stripes)==0);
3630                 mddev->reshape_position = conf->expand_progress;
3631                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3632                 md_wakeup_thread(mddev->thread);
3633                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
3634                            kthread_should_stop());
3635                 spin_lock_irq(&conf->device_lock);
3636                 conf->expand_lo = mddev->reshape_position;
3637                 spin_unlock_irq(&conf->device_lock);
3638                 wake_up(&conf->wait_for_overlap);
3639         }
3640
3641         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
3642                 int j;
3643                 int skipped = 0;
3644                 pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
3645                 sh = get_active_stripe(conf, sector_nr+i,
3646                                        conf->raid_disks, pd_idx, 0);
3647                 set_bit(STRIPE_EXPANDING, &sh->state);
3648                 atomic_inc(&conf->reshape_stripes);
3649                 /* If any of this stripe is beyond the end of the old
3650                  * array, then we need to zero those blocks
3651                  */
3652                 for (j=sh->disks; j--;) {
3653                         sector_t s;
3654                         if (j == sh->pd_idx)
3655                                 continue;
3656                         if (conf->level == 6 &&
3657                             j == raid6_next_disk(sh->pd_idx, sh->disks))
3658                                 continue;
3659                         s = compute_blocknr(sh, j);
3660                         if (s < (mddev->array_size<<1)) {
3661                                 skipped = 1;
3662                                 continue;
3663                         }
3664                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
3665                         set_bit(R5_Expanded, &sh->dev[j].flags);
3666                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
3667                 }
3668                 if (!skipped) {
3669                         set_bit(STRIPE_EXPAND_READY, &sh->state);
3670                         set_bit(STRIPE_HANDLE, &sh->state);
3671                 }
3672                 release_stripe(sh);
3673         }
3674         spin_lock_irq(&conf->device_lock);
3675         conf->expand_progress = (sector_nr + i) * new_data_disks;
3676         spin_unlock_irq(&conf->device_lock);
3677         /* Ok, those stripe are ready. We can start scheduling
3678          * reads on the source stripes.
3679          * The source stripes are determined by mapping the first and last
3680          * block on the destination stripes.
3681          */
3682         first_sector =
3683                 raid5_compute_sector(sector_nr*(new_data_disks),
3684                                      raid_disks, data_disks,
3685                                      &dd_idx, &pd_idx, conf);
3686         last_sector =
3687                 raid5_compute_sector((sector_nr+conf->chunk_size/512)
3688                                      *(new_data_disks) -1,
3689                                      raid_disks, data_disks,
3690                                      &dd_idx, &pd_idx, conf);
3691         if (last_sector >= (mddev->size<<1))
3692                 last_sector = (mddev->size<<1)-1;
3693         while (first_sector <= last_sector) {
3694                 pd_idx = stripe_to_pdidx(first_sector, conf,
3695                                          conf->previous_raid_disks);
3696                 sh = get_active_stripe(conf, first_sector,
3697                                        conf->previous_raid_disks, pd_idx, 0);
3698                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3699                 set_bit(STRIPE_HANDLE, &sh->state);
3700                 release_stripe(sh);
3701                 first_sector += STRIPE_SECTORS;
3702         }
3703         /* If this takes us to the resync_max point where we have to pause,
3704          * then we need to write out the superblock.
3705          */
3706         sector_nr += conf->chunk_size>>9;
3707         if (sector_nr >= mddev->resync_max) {
3708                 /* Cannot proceed until we've updated the superblock... */
3709                 wait_event(conf->wait_for_overlap,
3710                            atomic_read(&conf->reshape_stripes) == 0);
3711                 mddev->reshape_position = conf->expand_progress;
3712                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3713                 md_wakeup_thread(mddev->thread);
3714                 wait_event(mddev->sb_wait,
3715                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
3716                            || kthread_should_stop());
3717                 spin_lock_irq(&conf->device_lock);
3718                 conf->expand_lo = mddev->reshape_position;
3719                 spin_unlock_irq(&conf->device_lock);
3720                 wake_up(&conf->wait_for_overlap);
3721         }
3722         return conf->chunk_size>>9;
3723 }
3724
3725 /* FIXME go_faster isn't used */
3726 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
3727 {
3728         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3729         struct stripe_head *sh;
3730         int pd_idx;
3731         int raid_disks = conf->raid_disks;
3732         sector_t max_sector = mddev->size << 1;
3733         int sync_blocks;
3734         int still_degraded = 0;
3735         int i;
3736
3737         if (sector_nr >= max_sector) {
3738                 /* just being told to finish up .. nothing much to do */
3739                 unplug_slaves(mddev);
3740                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
3741                         end_reshape(conf);
3742                         return 0;
3743                 }
3744
3745                 if (mddev->curr_resync < max_sector) /* aborted */
3746                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
3747                                         &sync_blocks, 1);
3748                 else /* completed sync */
3749                         conf->fullsync = 0;
3750                 bitmap_close_sync(mddev->bitmap);
3751
3752                 return 0;
3753         }
3754
3755         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3756                 return reshape_request(mddev, sector_nr, skipped);
3757
3758         /* No need to check resync_max as we never do more than one
3759          * stripe, and as resync_max will always be on a chunk boundary,
3760          * if the check in md_do_sync didn't fire, there is no chance
3761          * of overstepping resync_max here
3762          */
3763
3764         /* if there is too many failed drives and we are trying
3765          * to resync, then assert that we are finished, because there is
3766          * nothing we can do.
3767          */
3768         if (mddev->degraded >= conf->max_degraded &&
3769             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3770                 sector_t rv = (mddev->size << 1) - sector_nr;
3771                 *skipped = 1;
3772                 return rv;
3773         }
3774         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
3775             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
3776             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
3777                 /* we can skip this block, and probably more */
3778                 sync_blocks /= STRIPE_SECTORS;
3779                 *skipped = 1;
3780                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
3781         }
3782
3783
3784         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3785
3786         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
3787         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
3788         if (sh == NULL) {
3789                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
3790                 /* make sure we don't swamp the stripe cache if someone else
3791                  * is trying to get access
3792                  */
3793                 schedule_timeout_uninterruptible(1);
3794         }
3795         /* Need to check if array will still be degraded after recovery/resync
3796          * We don't need to check the 'failed' flag as when that gets set,
3797          * recovery aborts.
3798          */
3799         for (i=0; i<mddev->raid_disks; i++)
3800                 if (conf->disks[i].rdev == NULL)
3801                         still_degraded = 1;
3802
3803         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
3804
3805         spin_lock(&sh->lock);
3806         set_bit(STRIPE_SYNCING, &sh->state);
3807         clear_bit(STRIPE_INSYNC, &sh->state);
3808         spin_unlock(&sh->lock);
3809
3810         handle_stripe(sh, NULL);
3811         release_stripe(sh);
3812
3813         return STRIPE_SECTORS;
3814 }
3815
3816 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
3817 {
3818         /* We may not be able to submit a whole bio at once as there
3819          * may not be enough stripe_heads available.
3820          * We cannot pre-allocate enough stripe_heads as we may need
3821          * more than exist in the cache (if we allow ever large chunks).
3822          * So we do one stripe head at a time and record in
3823          * ->bi_hw_segments how many have been done.
3824          *
3825          * We *know* that this entire raid_bio is in one chunk, so
3826          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
3827          */
3828         struct stripe_head *sh;
3829         int dd_idx, pd_idx;
3830         sector_t sector, logical_sector, last_sector;
3831         int scnt = 0;
3832         int remaining;
3833         int handled = 0;
3834
3835         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3836         sector = raid5_compute_sector(  logical_sector,
3837                                         conf->raid_disks,
3838                                         conf->raid_disks - conf->max_degraded,
3839                                         &dd_idx,
3840                                         &pd_idx,
3841                                         conf);
3842         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
3843
3844         for (; logical_sector < last_sector;
3845              logical_sector += STRIPE_SECTORS,
3846                      sector += STRIPE_SECTORS,
3847                      scnt++) {
3848
3849                 if (scnt < raid_bio->bi_hw_segments)
3850                         /* already done this stripe */
3851                         continue;
3852
3853                 sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
3854
3855                 if (!sh) {
3856                         /* failed to get a stripe - must wait */
3857                         raid_bio->bi_hw_segments = scnt;
3858                         conf->retry_read_aligned = raid_bio;
3859                         return handled;
3860                 }
3861
3862                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
3863                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
3864                         release_stripe(sh);
3865                         raid_bio->bi_hw_segments = scnt;
3866                         conf->retry_read_aligned = raid_bio;
3867                         return handled;
3868                 }
3869
3870                 handle_stripe(sh, NULL);
3871                 release_stripe(sh);
3872                 handled++;
3873         }
3874         spin_lock_irq(&conf->device_lock);
3875         remaining = --raid_bio->bi_phys_segments;
3876         spin_unlock_irq(&conf->device_lock);
3877         if (remaining == 0) {
3878
3879                 raid_bio->bi_end_io(raid_bio,
3880                               test_bit(BIO_UPTODATE, &raid_bio->bi_flags)
3881                                 ? 0 : -EIO);
3882         }
3883         if (atomic_dec_and_test(&conf->active_aligned_reads))
3884                 wake_up(&conf->wait_for_stripe);
3885         return handled;
3886 }
3887
3888
3889
3890 /*
3891  * This is our raid5 kernel thread.
3892  *
3893  * We scan the hash table for stripes which can be handled now.
3894  * During the scan, completed stripes are saved for us by the interrupt
3895  * handler, so that they will not have to wait for our next wakeup.
3896  */
3897 static void raid5d(mddev_t *mddev)
3898 {
3899         struct stripe_head *sh;
3900         raid5_conf_t *conf = mddev_to_conf(mddev);
3901         int handled;
3902
3903         pr_debug("+++ raid5d active\n");
3904
3905         md_check_recovery(mddev);
3906
3907         handled = 0;
3908         spin_lock_irq(&conf->device_lock);
3909         while (1) {
3910                 struct list_head *first;
3911                 struct bio *bio;
3912
3913                 if (conf->seq_flush != conf->seq_write) {
3914                         int seq = conf->seq_flush;
3915                         spin_unlock_irq(&conf->device_lock);
3916                         bitmap_unplug(mddev->bitmap);
3917                         spin_lock_irq(&conf->device_lock);
3918                         conf->seq_write = seq;
3919                         activate_bit_delay(conf);
3920                 }
3921
3922                 while ((bio = remove_bio_from_retry(conf))) {
3923                         int ok;
3924                         spin_unlock_irq(&conf->device_lock);
3925                         ok = retry_aligned_read(conf, bio);
3926                         spin_lock_irq(&conf->device_lock);
3927                         if (!ok)
3928                                 break;
3929                         handled++;
3930                 }
3931
3932                 if (list_empty(&conf->handle_list)) {
3933                         async_tx_issue_pending_all();
3934                         break;
3935                 }
3936
3937                 first = conf->handle_list.next;
3938                 sh = list_entry(first, struct stripe_head, lru);
3939
3940                 list_del_init(first);
3941                 atomic_inc(&sh->count);
3942                 BUG_ON(atomic_read(&sh->count)!= 1);
3943                 spin_unlock_irq(&conf->device_lock);
3944                 
3945                 handled++;
3946                 handle_stripe(sh, conf->spare_page);
3947                 release_stripe(sh);
3948
3949                 spin_lock_irq(&conf->device_lock);
3950         }
3951         pr_debug("%d stripes handled\n", handled);
3952
3953         spin_unlock_irq(&conf->device_lock);
3954
3955         unplug_slaves(mddev);
3956
3957         pr_debug("--- raid5d inactive\n");
3958 }
3959
3960 static ssize_t
3961 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
3962 {
3963         raid5_conf_t *conf = mddev_to_conf(mddev);
3964         if (conf)
3965                 return sprintf(page, "%d\n", conf->max_nr_stripes);
3966         else
3967                 return 0;
3968 }
3969
3970 static ssize_t
3971 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
3972 {
3973         raid5_conf_t *conf = mddev_to_conf(mddev);
3974         char *end;
3975         int new;
3976         if (len >= PAGE_SIZE)
3977                 return -EINVAL;
3978         if (!conf)
3979                 return -ENODEV;
3980
3981         new = simple_strtoul(page, &end, 10);
3982         if (!*page || (*end && *end != '\n') )
3983                 return -EINVAL;
3984         if (new <= 16 || new > 32768)
3985                 return -EINVAL;
3986         while (new < conf->max_nr_stripes) {
3987                 if (drop_one_stripe(conf))
3988                         conf->max_nr_stripes--;
3989                 else
3990                         break;
3991         }
3992         md_allow_write(mddev);
3993         while (new > conf->max_nr_stripes) {
3994                 if (grow_one_stripe(conf))
3995                         conf->max_nr_stripes++;
3996                 else break;
3997         }
3998         return len;
3999 }
4000
4001 static struct md_sysfs_entry
4002 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4003                                 raid5_show_stripe_cache_size,
4004                                 raid5_store_stripe_cache_size);
4005
4006 static ssize_t
4007 stripe_cache_active_show(mddev_t *mddev, char *page)
4008 {
4009         raid5_conf_t *conf = mddev_to_conf(mddev);
4010         if (conf)
4011                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4012         else
4013                 return 0;
4014 }
4015
4016 static struct md_sysfs_entry
4017 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4018
4019 static struct attribute *raid5_attrs[] =  {
4020         &raid5_stripecache_size.attr,
4021         &raid5_stripecache_active.attr,
4022         NULL,
4023 };
4024 static struct attribute_group raid5_attrs_group = {
4025         .name = NULL,
4026         .attrs = raid5_attrs,
4027 };
4028
4029 static int run(mddev_t *mddev)
4030 {
4031         raid5_conf_t *conf;
4032         int raid_disk, memory;
4033         mdk_rdev_t *rdev;
4034         struct disk_info *disk;
4035         struct list_head *tmp;
4036         int working_disks = 0;
4037
4038         if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
4039                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
4040                        mdname(mddev), mddev->level);
4041                 return -EIO;
4042         }
4043
4044         if (mddev->reshape_position != MaxSector) {
4045                 /* Check that we can continue the reshape.
4046                  * Currently only disks can change, it must
4047                  * increase, and we must be past the point where
4048                  * a stripe over-writes itself
4049                  */
4050                 sector_t here_new, here_old;
4051                 int old_disks;
4052                 int max_degraded = (mddev->level == 5 ? 1 : 2);
4053
4054                 if (mddev->new_level != mddev->level ||
4055                     mddev->new_layout != mddev->layout ||
4056                     mddev->new_chunk != mddev->chunk_size) {
4057                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4058                                "required - aborting.\n",
4059                                mdname(mddev));
4060                         return -EINVAL;
4061                 }
4062                 if (mddev->delta_disks <= 0) {
4063                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4064                                "(reduce disks) required - aborting.\n",
4065                                mdname(mddev));
4066                         return -EINVAL;
4067                 }
4068                 old_disks = mddev->raid_disks - mddev->delta_disks;
4069                 /* reshape_position must be on a new-stripe boundary, and one
4070                  * further up in new geometry must map after here in old
4071                  * geometry.
4072                  */
4073                 here_new = mddev->reshape_position;
4074                 if (sector_div(here_new, (mddev->chunk_size>>9)*
4075                                (mddev->raid_disks - max_degraded))) {
4076                         printk(KERN_ERR "raid5: reshape_position not "
4077                                "on a stripe boundary\n");
4078                         return -EINVAL;
4079                 }
4080                 /* here_new is the stripe we will write to */
4081                 here_old = mddev->reshape_position;
4082                 sector_div(here_old, (mddev->chunk_size>>9)*
4083                            (old_disks-max_degraded));
4084                 /* here_old is the first stripe that we might need to read
4085                  * from */
4086                 if (here_new >= here_old) {
4087                         /* Reading from the same stripe as writing to - bad */
4088                         printk(KERN_ERR "raid5: reshape_position too early for "
4089                                "auto-recovery - aborting.\n");
4090                         return -EINVAL;
4091                 }
4092                 printk(KERN_INFO "raid5: reshape will continue\n");
4093                 /* OK, we should be able to continue; */
4094         }
4095
4096
4097         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
4098         if ((conf = mddev->private) == NULL)
4099                 goto abort;
4100         if (mddev->reshape_position == MaxSector) {
4101                 conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
4102         } else {
4103                 conf->raid_disks = mddev->raid_disks;
4104                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4105         }
4106
4107         conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
4108                               GFP_KERNEL);
4109         if (!conf->disks)
4110                 goto abort;
4111
4112         conf->mddev = mddev;
4113
4114         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4115                 goto abort;
4116
4117         if (mddev->level == 6) {
4118                 conf->spare_page = alloc_page(GFP_KERNEL);
4119                 if (!conf->spare_page)
4120                         goto abort;
4121         }
4122         spin_lock_init(&conf->device_lock);
4123         init_waitqueue_head(&conf->wait_for_stripe);
4124         init_waitqueue_head(&conf->wait_for_overlap);
4125         INIT_LIST_HEAD(&conf->handle_list);
4126         INIT_LIST_HEAD(&conf->delayed_list);
4127         INIT_LIST_HEAD(&conf->bitmap_list);
4128         INIT_LIST_HEAD(&conf->inactive_list);
4129         atomic_set(&conf->active_stripes, 0);
4130         atomic_set(&conf->preread_active_stripes, 0);
4131         atomic_set(&conf->active_aligned_reads, 0);
4132
4133         pr_debug("raid5: run(%s) called.\n", mdname(mddev));
4134
4135         rdev_for_each(rdev, tmp, mddev) {
4136                 raid_disk = rdev->raid_disk;
4137                 if (raid_disk >= conf->raid_disks
4138                     || raid_disk < 0)
4139                         continue;
4140                 disk = conf->disks + raid_disk;
4141
4142                 disk->rdev = rdev;
4143
4144                 if (test_bit(In_sync, &rdev->flags)) {
4145                         char b[BDEVNAME_SIZE];
4146                         printk(KERN_INFO "raid5: device %s operational as raid"
4147                                 " disk %d\n", bdevname(rdev->bdev,b),
4148                                 raid_disk);
4149                         working_disks++;
4150                 }
4151         }
4152
4153         /*
4154          * 0 for a fully functional array, 1 or 2 for a degraded array.
4155          */
4156         mddev->degraded = conf->raid_disks - working_disks;
4157         conf->mddev = mddev;
4158         conf->chunk_size = mddev->chunk_size;
4159         conf->level = mddev->level;
4160         if (conf->level == 6)
4161                 conf->max_degraded = 2;
4162         else
4163                 conf->max_degraded = 1;
4164         conf->algorithm = mddev->layout;
4165         conf->max_nr_stripes = NR_STRIPES;
4166         conf->expand_progress = mddev->reshape_position;
4167
4168         /* device size must be a multiple of chunk size */
4169         mddev->size &= ~(mddev->chunk_size/1024 -1);
4170         mddev->resync_max_sectors = mddev->size << 1;
4171
4172         if (conf->level == 6 && conf->raid_disks < 4) {
4173                 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
4174                        mdname(mddev), conf->raid_disks);
4175                 goto abort;
4176         }
4177         if (!conf->chunk_size || conf->chunk_size % 4) {
4178                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
4179                         conf->chunk_size, mdname(mddev));
4180                 goto abort;
4181         }
4182         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
4183                 printk(KERN_ERR 
4184                         "raid5: unsupported parity algorithm %d for %s\n",
4185                         conf->algorithm, mdname(mddev));
4186                 goto abort;
4187         }
4188         if (mddev->degraded > conf->max_degraded) {
4189                 printk(KERN_ERR "raid5: not enough operational devices for %s"
4190                         " (%d/%d failed)\n",
4191                         mdname(mddev), mddev->degraded, conf->raid_disks);
4192                 goto abort;
4193         }
4194
4195         if (mddev->degraded > 0 &&
4196             mddev->recovery_cp != MaxSector) {
4197                 if (mddev->ok_start_degraded)
4198                         printk(KERN_WARNING
4199                                "raid5: starting dirty degraded array: %s"
4200                                "- data corruption possible.\n",
4201                                mdname(mddev));
4202                 else {
4203                         printk(KERN_ERR
4204                                "raid5: cannot start dirty degraded array for %s\n",
4205                                mdname(mddev));
4206                         goto abort;
4207                 }
4208         }
4209
4210         {
4211                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
4212                 if (!mddev->thread) {
4213                         printk(KERN_ERR 
4214                                 "raid5: couldn't allocate thread for %s\n",
4215                                 mdname(mddev));
4216                         goto abort;
4217                 }
4218         }
4219         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4220                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4221         if (grow_stripes(conf, conf->max_nr_stripes)) {
4222                 printk(KERN_ERR 
4223                         "raid5: couldn't allocate %dkB for buffers\n", memory);
4224                 shrink_stripes(conf);
4225                 md_unregister_thread(mddev->thread);
4226                 goto abort;
4227         } else
4228                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
4229                         memory, mdname(mddev));
4230
4231         if (mddev->degraded == 0)
4232                 printk("raid5: raid level %d set %s active with %d out of %d"
4233                         " devices, algorithm %d\n", conf->level, mdname(mddev), 
4234                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
4235                         conf->algorithm);
4236         else
4237                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
4238                         " out of %d devices, algorithm %d\n", conf->level,
4239                         mdname(mddev), mddev->raid_disks - mddev->degraded,
4240                         mddev->raid_disks, conf->algorithm);
4241
4242         print_raid5_conf(conf);
4243
4244         if (conf->expand_progress != MaxSector) {
4245                 printk("...ok start reshape thread\n");
4246                 conf->expand_lo = conf->expand_progress;
4247                 atomic_set(&conf->reshape_stripes, 0);
4248                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4249                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4250                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4251                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4252                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4253                                                         "%s_reshape");
4254         }
4255
4256         /* read-ahead size must cover two whole stripes, which is
4257          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4258          */
4259         {
4260                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
4261                 int stripe = data_disks *
4262                         (mddev->chunk_size / PAGE_SIZE);
4263                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4264                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4265         }
4266
4267         /* Ok, everything is just fine now */
4268         if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
4269                 printk(KERN_WARNING
4270                        "raid5: failed to create sysfs attributes for %s\n",
4271                        mdname(mddev));
4272
4273         mddev->queue->unplug_fn = raid5_unplug_device;
4274         mddev->queue->backing_dev_info.congested_data = mddev;
4275         mddev->queue->backing_dev_info.congested_fn = raid5_congested;
4276
4277         mddev->array_size =  mddev->size * (conf->previous_raid_disks -
4278                                             conf->max_degraded);
4279
4280         blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
4281
4282         return 0;
4283 abort:
4284         if (conf) {
4285                 print_raid5_conf(conf);
4286                 safe_put_page(conf->spare_page);
4287                 kfree(conf->disks);
4288                 kfree(conf->stripe_hashtbl);
4289                 kfree(conf);
4290         }
4291         mddev->private = NULL;
4292         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
4293         return -EIO;
4294 }
4295
4296
4297
4298 static int stop(mddev_t *mddev)
4299 {
4300         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4301
4302         md_unregister_thread(mddev->thread);
4303         mddev->thread = NULL;
4304         shrink_stripes(conf);
4305         kfree(conf->stripe_hashtbl);
4306         mddev->queue->backing_dev_info.congested_fn = NULL;
4307         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
4308         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
4309         kfree(conf->disks);
4310         kfree(conf);
4311         mddev->private = NULL;
4312         return 0;
4313 }
4314
4315 #ifdef DEBUG
4316 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
4317 {
4318         int i;
4319
4320         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
4321                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
4322         seq_printf(seq, "sh %llu,  count %d.\n",
4323                    (unsigned long long)sh->sector, atomic_read(&sh->count));
4324         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
4325         for (i = 0; i < sh->disks; i++) {
4326                 seq_printf(seq, "(cache%d: %p %ld) ",
4327                            i, sh->dev[i].page, sh->dev[i].flags);
4328         }
4329         seq_printf(seq, "\n");
4330 }
4331
4332 static void printall (struct seq_file *seq, raid5_conf_t *conf)
4333 {
4334         struct stripe_head *sh;
4335         struct hlist_node *hn;
4336         int i;
4337
4338         spin_lock_irq(&conf->device_lock);
4339         for (i = 0; i < NR_HASH; i++) {
4340                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
4341                         if (sh->raid_conf != conf)
4342                                 continue;
4343                         print_sh(seq, sh);
4344                 }
4345         }
4346         spin_unlock_irq(&conf->device_lock);
4347 }
4348 #endif
4349
4350 static void status (struct seq_file *seq, mddev_t *mddev)
4351 {
4352         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4353         int i;
4354
4355         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
4356         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
4357         for (i = 0; i < conf->raid_disks; i++)
4358                 seq_printf (seq, "%s",
4359                                conf->disks[i].rdev &&
4360                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
4361         seq_printf (seq, "]");
4362 #ifdef DEBUG
4363         seq_printf (seq, "\n");
4364         printall(seq, conf);
4365 #endif
4366 }
4367
4368 static void print_raid5_conf (raid5_conf_t *conf)
4369 {
4370         int i;
4371         struct disk_info *tmp;
4372
4373         printk("RAID5 conf printout:\n");
4374         if (!conf) {
4375                 printk("(conf==NULL)\n");
4376                 return;
4377         }
4378         printk(" --- rd:%d wd:%d\n", conf->raid_disks,
4379                  conf->raid_disks - conf->mddev->degraded);
4380
4381         for (i = 0; i < conf->raid_disks; i++) {
4382                 char b[BDEVNAME_SIZE];
4383                 tmp = conf->disks + i;
4384                 if (tmp->rdev)
4385                 printk(" disk %d, o:%d, dev:%s\n",
4386                         i, !test_bit(Faulty, &tmp->rdev->flags),
4387                         bdevname(tmp->rdev->bdev,b));
4388         }
4389 }
4390
4391 static int raid5_spare_active(mddev_t *mddev)
4392 {
4393         int i;
4394         raid5_conf_t *conf = mddev->private;
4395         struct disk_info *tmp;
4396
4397         for (i = 0; i < conf->raid_disks; i++) {
4398                 tmp = conf->disks + i;
4399                 if (tmp->rdev
4400                     && !test_bit(Faulty, &tmp->rdev->flags)
4401                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
4402                         unsigned long flags;
4403                         spin_lock_irqsave(&conf->device_lock, flags);
4404                         mddev->degraded--;
4405                         spin_unlock_irqrestore(&conf->device_lock, flags);
4406                 }
4407         }
4408         print_raid5_conf(conf);
4409         return 0;
4410 }
4411
4412 static int raid5_remove_disk(mddev_t *mddev, int number)
4413 {
4414         raid5_conf_t *conf = mddev->private;
4415         int err = 0;
4416         mdk_rdev_t *rdev;
4417         struct disk_info *p = conf->disks + number;
4418
4419         print_raid5_conf(conf);
4420         rdev = p->rdev;
4421         if (rdev) {
4422                 if (test_bit(In_sync, &rdev->flags) ||
4423                     atomic_read(&rdev->nr_pending)) {
4424                         err = -EBUSY;
4425                         goto abort;
4426                 }
4427                 p->rdev = NULL;
4428                 synchronize_rcu();
4429                 if (atomic_read(&rdev->nr_pending)) {
4430                         /* lost the race, try later */
4431                         err = -EBUSY;
4432                         p->rdev = rdev;
4433                 }
4434         }
4435 abort:
4436
4437         print_raid5_conf(conf);
4438         return err;
4439 }
4440
4441 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
4442 {
4443         raid5_conf_t *conf = mddev->private;
4444         int found = 0;
4445         int disk;
4446         struct disk_info *p;
4447
4448         if (mddev->degraded > conf->max_degraded)
4449                 /* no point adding a device */
4450                 return 0;
4451
4452         /*
4453          * find the disk ... but prefer rdev->saved_raid_disk
4454          * if possible.
4455          */
4456         if (rdev->saved_raid_disk >= 0 &&
4457             conf->disks[rdev->saved_raid_disk].rdev == NULL)
4458                 disk = rdev->saved_raid_disk;
4459         else
4460                 disk = 0;
4461         for ( ; disk < conf->raid_disks; disk++)
4462                 if ((p=conf->disks + disk)->rdev == NULL) {
4463                         clear_bit(In_sync, &rdev->flags);
4464                         rdev->raid_disk = disk;
4465                         found = 1;
4466                         if (rdev->saved_raid_disk != disk)
4467                                 conf->fullsync = 1;
4468                         rcu_assign_pointer(p->rdev, rdev);
4469                         break;
4470                 }
4471         print_raid5_conf(conf);
4472         return found;
4473 }
4474
4475 static int raid5_resize(mddev_t *mddev, sector_t sectors)
4476 {
4477         /* no resync is happening, and there is enough space
4478          * on all devices, so we can resize.
4479          * We need to make sure resync covers any new space.
4480          * If the array is shrinking we should possibly wait until
4481          * any io in the removed space completes, but it hardly seems
4482          * worth it.
4483          */
4484         raid5_conf_t *conf = mddev_to_conf(mddev);
4485
4486         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
4487         mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
4488         set_capacity(mddev->gendisk, mddev->array_size << 1);
4489         mddev->changed = 1;
4490         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
4491                 mddev->recovery_cp = mddev->size << 1;
4492                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4493         }
4494         mddev->size = sectors /2;
4495         mddev->resync_max_sectors = sectors;
4496         return 0;
4497 }
4498
4499 #ifdef CONFIG_MD_RAID5_RESHAPE
4500 static int raid5_check_reshape(mddev_t *mddev)
4501 {
4502         raid5_conf_t *conf = mddev_to_conf(mddev);
4503         int err;
4504
4505         if (mddev->delta_disks < 0 ||
4506             mddev->new_level != mddev->level)
4507                 return -EINVAL; /* Cannot shrink array or change level yet */
4508         if (mddev->delta_disks == 0)
4509                 return 0; /* nothing to do */
4510
4511         /* Can only proceed if there are plenty of stripe_heads.
4512          * We need a minimum of one full stripe,, and for sensible progress
4513          * it is best to have about 4 times that.
4514          * If we require 4 times, then the default 256 4K stripe_heads will
4515          * allow for chunk sizes up to 256K, which is probably OK.
4516          * If the chunk size is greater, user-space should request more
4517          * stripe_heads first.
4518          */
4519         if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
4520             (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
4521                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
4522                        (mddev->chunk_size / STRIPE_SIZE)*4);
4523                 return -ENOSPC;
4524         }
4525
4526         err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
4527         if (err)
4528                 return err;
4529
4530         if (mddev->degraded > conf->max_degraded)
4531                 return -EINVAL;
4532         /* looks like we might be able to manage this */
4533         return 0;
4534 }
4535
4536 static int raid5_start_reshape(mddev_t *mddev)
4537 {
4538         raid5_conf_t *conf = mddev_to_conf(mddev);
4539         mdk_rdev_t *rdev;
4540         struct list_head *rtmp;
4541         int spares = 0;
4542         int added_devices = 0;
4543         unsigned long flags;
4544
4545         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4546                 return -EBUSY;
4547
4548         rdev_for_each(rdev, rtmp, mddev)
4549                 if (rdev->raid_disk < 0 &&
4550                     !test_bit(Faulty, &rdev->flags))
4551                         spares++;
4552
4553         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
4554                 /* Not enough devices even to make a degraded array
4555                  * of that size
4556                  */
4557                 return -EINVAL;
4558
4559         atomic_set(&conf->reshape_stripes, 0);
4560         spin_lock_irq(&conf->device_lock);
4561         conf->previous_raid_disks = conf->raid_disks;
4562         conf->raid_disks += mddev->delta_disks;
4563         conf->expand_progress = 0;
4564         conf->expand_lo = 0;
4565         spin_unlock_irq(&conf->device_lock);
4566
4567         /* Add some new drives, as many as will fit.
4568          * We know there are enough to make the newly sized array work.
4569          */
4570         rdev_for_each(rdev, rtmp, mddev)
4571                 if (rdev->raid_disk < 0 &&
4572                     !test_bit(Faulty, &rdev->flags)) {
4573                         if (raid5_add_disk(mddev, rdev)) {
4574                                 char nm[20];
4575                                 set_bit(In_sync, &rdev->flags);
4576                                 added_devices++;
4577                                 rdev->recovery_offset = 0;
4578                                 sprintf(nm, "rd%d", rdev->raid_disk);
4579                                 if (sysfs_create_link(&mddev->kobj,
4580                                                       &rdev->kobj, nm))
4581                                         printk(KERN_WARNING
4582                                                "raid5: failed to create "
4583                                                " link %s for %s\n",
4584                                                nm, mdname(mddev));
4585                         } else
4586                                 break;
4587                 }
4588
4589         spin_lock_irqsave(&conf->device_lock, flags);
4590         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
4591         spin_unlock_irqrestore(&conf->device_lock, flags);
4592         mddev->raid_disks = conf->raid_disks;
4593         mddev->reshape_position = 0;
4594         set_bit(MD_CHANGE_DEVS, &mddev->flags);
4595
4596         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4597         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4598         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4599         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4600         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4601                                                 "%s_reshape");
4602         if (!mddev->sync_thread) {
4603                 mddev->recovery = 0;
4604                 spin_lock_irq(&conf->device_lock);
4605                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
4606                 conf->expand_progress = MaxSector;
4607                 spin_unlock_irq(&conf->device_lock);
4608                 return -EAGAIN;
4609         }
4610         md_wakeup_thread(mddev->sync_thread);
4611         md_new_event(mddev);
4612         return 0;
4613 }
4614 #endif
4615
4616 static void end_reshape(raid5_conf_t *conf)
4617 {
4618         struct block_device *bdev;
4619
4620         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
4621                 conf->mddev->array_size = conf->mddev->size *
4622                         (conf->raid_disks - conf->max_degraded);
4623                 set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
4624                 conf->mddev->changed = 1;
4625
4626                 bdev = bdget_disk(conf->mddev->gendisk, 0);
4627                 if (bdev) {
4628                         mutex_lock(&bdev->bd_inode->i_mutex);
4629                         i_size_write(bdev->bd_inode, (loff_t)conf->mddev->array_size << 10);
4630                         mutex_unlock(&bdev->bd_inode->i_mutex);
4631                         bdput(bdev);
4632                 }
4633                 spin_lock_irq(&conf->device_lock);
4634                 conf->expand_progress = MaxSector;
4635                 spin_unlock_irq(&conf->device_lock);
4636                 conf->mddev->reshape_position = MaxSector;
4637
4638                 /* read-ahead size must cover two whole stripes, which is
4639                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4640                  */
4641                 {
4642                         int data_disks = conf->previous_raid_disks - conf->max_degraded;
4643                         int stripe = data_disks *
4644                                 (conf->mddev->chunk_size / PAGE_SIZE);
4645                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4646                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4647                 }
4648         }
4649 }
4650
4651 static void raid5_quiesce(mddev_t *mddev, int state)
4652 {
4653         raid5_conf_t *conf = mddev_to_conf(mddev);
4654
4655         switch(state) {
4656         case 2: /* resume for a suspend */
4657                 wake_up(&conf->wait_for_overlap);
4658                 break;
4659
4660         case 1: /* stop all writes */
4661                 spin_lock_irq(&conf->device_lock);
4662                 conf->quiesce = 1;
4663                 wait_event_lock_irq(conf->wait_for_stripe,
4664                                     atomic_read(&conf->active_stripes) == 0 &&
4665                                     atomic_read(&conf->active_aligned_reads) == 0,
4666                                     conf->device_lock, /* nothing */);
4667                 spin_unlock_irq(&conf->device_lock);
4668                 break;
4669
4670         case 0: /* re-enable writes */
4671                 spin_lock_irq(&conf->device_lock);
4672                 conf->quiesce = 0;
4673                 wake_up(&conf->wait_for_stripe);
4674                 wake_up(&conf->wait_for_overlap);
4675                 spin_unlock_irq(&conf->device_lock);
4676                 break;
4677         }
4678 }
4679
4680 static struct mdk_personality raid6_personality =
4681 {
4682         .name           = "raid6",
4683         .level          = 6,
4684         .owner          = THIS_MODULE,
4685         .make_request   = make_request,
4686         .run            = run,
4687         .stop           = stop,
4688         .status         = status,
4689         .error_handler  = error,
4690         .hot_add_disk   = raid5_add_disk,
4691         .hot_remove_disk= raid5_remove_disk,
4692         .spare_active   = raid5_spare_active,
4693         .sync_request   = sync_request,
4694         .resize         = raid5_resize,
4695 #ifdef CONFIG_MD_RAID5_RESHAPE
4696         .check_reshape  = raid5_check_reshape,
4697         .start_reshape  = raid5_start_reshape,
4698 #endif
4699         .quiesce        = raid5_quiesce,
4700 };
4701 static struct mdk_personality raid5_personality =
4702 {
4703         .name           = "raid5",
4704         .level          = 5,
4705         .owner          = THIS_MODULE,
4706         .make_request   = make_request,
4707         .run            = run,
4708         .stop           = stop,
4709         .status         = status,
4710         .error_handler  = error,
4711         .hot_add_disk   = raid5_add_disk,
4712         .hot_remove_disk= raid5_remove_disk,
4713         .spare_active   = raid5_spare_active,
4714         .sync_request   = sync_request,
4715         .resize         = raid5_resize,
4716 #ifdef CONFIG_MD_RAID5_RESHAPE
4717         .check_reshape  = raid5_check_reshape,
4718         .start_reshape  = raid5_start_reshape,
4719 #endif
4720         .quiesce        = raid5_quiesce,
4721 };
4722
4723 static struct mdk_personality raid4_personality =
4724 {
4725         .name           = "raid4",
4726         .level          = 4,
4727         .owner          = THIS_MODULE,
4728         .make_request   = make_request,
4729         .run            = run,
4730         .stop           = stop,
4731         .status         = status,
4732         .error_handler  = error,
4733         .hot_add_disk   = raid5_add_disk,
4734         .hot_remove_disk= raid5_remove_disk,
4735         .spare_active   = raid5_spare_active,
4736         .sync_request   = sync_request,
4737         .resize         = raid5_resize,
4738 #ifdef CONFIG_MD_RAID5_RESHAPE
4739         .check_reshape  = raid5_check_reshape,
4740         .start_reshape  = raid5_start_reshape,
4741 #endif
4742         .quiesce        = raid5_quiesce,
4743 };
4744
4745 static int __init raid5_init(void)
4746 {
4747         int e;
4748
4749         e = raid6_select_algo();
4750         if ( e )
4751                 return e;
4752         register_md_personality(&raid6_personality);
4753         register_md_personality(&raid5_personality);
4754         register_md_personality(&raid4_personality);
4755         return 0;
4756 }
4757
4758 static void raid5_exit(void)
4759 {
4760         unregister_md_personality(&raid6_personality);
4761         unregister_md_personality(&raid5_personality);
4762         unregister_md_personality(&raid4_personality);
4763 }
4764
4765 module_init(raid5_init);
4766 module_exit(raid5_exit);
4767 MODULE_LICENSE("GPL");
4768 MODULE_ALIAS("md-personality-4"); /* RAID5 */
4769 MODULE_ALIAS("md-raid5");
4770 MODULE_ALIAS("md-raid4");
4771 MODULE_ALIAS("md-level-5");
4772 MODULE_ALIAS("md-level-4");
4773 MODULE_ALIAS("md-personality-8"); /* RAID6 */
4774 MODULE_ALIAS("md-raid6");
4775 MODULE_ALIAS("md-level-6");
4776
4777 /* This used to be two separate modules, they were: */
4778 MODULE_ALIAS("raid5");
4779 MODULE_ALIAS("raid6");