ee0ea9183080fd3e333302eb4512803b6d9f26b1
[linux-2.6.git] / drivers / md / raid5.c
1 /*
2  * raid5.c : Multiple Devices driver for Linux
3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4  *         Copyright (C) 1999, 2000 Ingo Molnar
5  *         Copyright (C) 2002, 2003 H. Peter Anvin
6  *
7  * RAID-4/5/6 management functions.
8  * Thanks to Penguin Computing for making the RAID-6 development possible
9  * by donating a test server!
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20
21 /*
22  * BITMAP UNPLUGGING:
23  *
24  * The sequencing for updating the bitmap reliably is a little
25  * subtle (and I got it wrong the first time) so it deserves some
26  * explanation.
27  *
28  * We group bitmap updates into batches.  Each batch has a number.
29  * We may write out several batches at once, but that isn't very important.
30  * conf->bm_write is the number of the last batch successfully written.
31  * conf->bm_flush is the number of the last batch that was closed to
32  *    new additions.
33  * When we discover that we will need to write to any block in a stripe
34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35  * the number of the batch it will be in. This is bm_flush+1.
36  * When we are ready to do a write, if that batch hasn't been written yet,
37  *   we plug the array and queue the stripe for later.
38  * When an unplug happens, we increment bm_flush, thus closing the current
39  *   batch.
40  * When we notice that bm_flush > bm_write, we write out all pending updates
41  * to the bitmap, and advance bm_write to where bm_flush was.
42  * This may occasionally write a bit out twice, but is sure never to
43  * miss any bits.
44  */
45
46 #include <linux/module.h>
47 #include <linux/slab.h>
48 #include <linux/highmem.h>
49 #include <linux/bitops.h>
50 #include <linux/kthread.h>
51 #include <asm/atomic.h>
52 #include "raid6.h"
53
54 #include <linux/raid/bitmap.h>
55 #include <linux/async_tx.h>
56
57 /*
58  * Stripe cache
59  */
60
61 #define NR_STRIPES              256
62 #define STRIPE_SIZE             PAGE_SIZE
63 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
64 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
65 #define IO_THRESHOLD            1
66 #define BYPASS_THRESHOLD        1
67 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
68 #define HASH_MASK               (NR_HASH - 1)
69
70 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
71
72 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
73  * order without overlap.  There may be several bio's per stripe+device, and
74  * a bio could span several devices.
75  * When walking this list for a particular stripe+device, we must never proceed
76  * beyond a bio that extends past this device, as the next bio might no longer
77  * be valid.
78  * This macro is used to determine the 'next' bio in the list, given the sector
79  * of the current stripe+device
80  */
81 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
82 /*
83  * The following can be used to debug the driver
84  */
85 #define RAID5_PARANOIA  1
86 #if RAID5_PARANOIA && defined(CONFIG_SMP)
87 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
88 #else
89 # define CHECK_DEVLOCK()
90 #endif
91
92 #ifdef DEBUG
93 #define inline
94 #define __inline__
95 #endif
96
97 #if !RAID6_USE_EMPTY_ZERO_PAGE
98 /* In .bss so it's zeroed */
99 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
100 #endif
101
102 static inline int raid6_next_disk(int disk, int raid_disks)
103 {
104         disk++;
105         return (disk < raid_disks) ? disk : 0;
106 }
107
108 static void return_io(struct bio *return_bi)
109 {
110         struct bio *bi = return_bi;
111         while (bi) {
112
113                 return_bi = bi->bi_next;
114                 bi->bi_next = NULL;
115                 bi->bi_size = 0;
116                 bi->bi_end_io(bi,
117                               test_bit(BIO_UPTODATE, &bi->bi_flags)
118                                 ? 0 : -EIO);
119                 bi = return_bi;
120         }
121 }
122
123 static void print_raid5_conf (raid5_conf_t *conf);
124
125 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
126 {
127         if (atomic_dec_and_test(&sh->count)) {
128                 BUG_ON(!list_empty(&sh->lru));
129                 BUG_ON(atomic_read(&conf->active_stripes)==0);
130                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
131                         if (test_bit(STRIPE_DELAYED, &sh->state)) {
132                                 list_add_tail(&sh->lru, &conf->delayed_list);
133                                 blk_plug_device(conf->mddev->queue);
134                         } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
135                                    sh->bm_seq - conf->seq_write > 0) {
136                                 list_add_tail(&sh->lru, &conf->bitmap_list);
137                                 blk_plug_device(conf->mddev->queue);
138                         } else {
139                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
140                                 list_add_tail(&sh->lru, &conf->handle_list);
141                         }
142                         md_wakeup_thread(conf->mddev->thread);
143                 } else {
144                         BUG_ON(sh->ops.pending);
145                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
146                                 atomic_dec(&conf->preread_active_stripes);
147                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
148                                         md_wakeup_thread(conf->mddev->thread);
149                         }
150                         atomic_dec(&conf->active_stripes);
151                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
152                                 list_add_tail(&sh->lru, &conf->inactive_list);
153                                 wake_up(&conf->wait_for_stripe);
154                                 if (conf->retry_read_aligned)
155                                         md_wakeup_thread(conf->mddev->thread);
156                         }
157                 }
158         }
159 }
160 static void release_stripe(struct stripe_head *sh)
161 {
162         raid5_conf_t *conf = sh->raid_conf;
163         unsigned long flags;
164
165         spin_lock_irqsave(&conf->device_lock, flags);
166         __release_stripe(conf, sh);
167         spin_unlock_irqrestore(&conf->device_lock, flags);
168 }
169
170 static inline void remove_hash(struct stripe_head *sh)
171 {
172         pr_debug("remove_hash(), stripe %llu\n",
173                 (unsigned long long)sh->sector);
174
175         hlist_del_init(&sh->hash);
176 }
177
178 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
179 {
180         struct hlist_head *hp = stripe_hash(conf, sh->sector);
181
182         pr_debug("insert_hash(), stripe %llu\n",
183                 (unsigned long long)sh->sector);
184
185         CHECK_DEVLOCK();
186         hlist_add_head(&sh->hash, hp);
187 }
188
189
190 /* find an idle stripe, make sure it is unhashed, and return it. */
191 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
192 {
193         struct stripe_head *sh = NULL;
194         struct list_head *first;
195
196         CHECK_DEVLOCK();
197         if (list_empty(&conf->inactive_list))
198                 goto out;
199         first = conf->inactive_list.next;
200         sh = list_entry(first, struct stripe_head, lru);
201         list_del_init(first);
202         remove_hash(sh);
203         atomic_inc(&conf->active_stripes);
204 out:
205         return sh;
206 }
207
208 static void shrink_buffers(struct stripe_head *sh, int num)
209 {
210         struct page *p;
211         int i;
212
213         for (i=0; i<num ; i++) {
214                 p = sh->dev[i].page;
215                 if (!p)
216                         continue;
217                 sh->dev[i].page = NULL;
218                 put_page(p);
219         }
220 }
221
222 static int grow_buffers(struct stripe_head *sh, int num)
223 {
224         int i;
225
226         for (i=0; i<num; i++) {
227                 struct page *page;
228
229                 if (!(page = alloc_page(GFP_KERNEL))) {
230                         return 1;
231                 }
232                 sh->dev[i].page = page;
233         }
234         return 0;
235 }
236
237 static void raid5_build_block (struct stripe_head *sh, int i);
238
239 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
240 {
241         raid5_conf_t *conf = sh->raid_conf;
242         int i;
243
244         BUG_ON(atomic_read(&sh->count) != 0);
245         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
246         BUG_ON(sh->ops.pending || sh->ops.ack || sh->ops.complete);
247
248         CHECK_DEVLOCK();
249         pr_debug("init_stripe called, stripe %llu\n",
250                 (unsigned long long)sh->sector);
251
252         remove_hash(sh);
253
254         sh->sector = sector;
255         sh->pd_idx = pd_idx;
256         sh->state = 0;
257
258         sh->disks = disks;
259
260         for (i = sh->disks; i--; ) {
261                 struct r5dev *dev = &sh->dev[i];
262
263                 if (dev->toread || dev->read || dev->towrite || dev->written ||
264                     test_bit(R5_LOCKED, &dev->flags)) {
265                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
266                                (unsigned long long)sh->sector, i, dev->toread,
267                                dev->read, dev->towrite, dev->written,
268                                test_bit(R5_LOCKED, &dev->flags));
269                         BUG();
270                 }
271                 dev->flags = 0;
272                 raid5_build_block(sh, i);
273         }
274         insert_hash(conf, sh);
275 }
276
277 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
278 {
279         struct stripe_head *sh;
280         struct hlist_node *hn;
281
282         CHECK_DEVLOCK();
283         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
284         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
285                 if (sh->sector == sector && sh->disks == disks)
286                         return sh;
287         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
288         return NULL;
289 }
290
291 static void unplug_slaves(mddev_t *mddev);
292 static void raid5_unplug_device(struct request_queue *q);
293
294 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
295                                              int pd_idx, int noblock)
296 {
297         struct stripe_head *sh;
298
299         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
300
301         spin_lock_irq(&conf->device_lock);
302
303         do {
304                 wait_event_lock_irq(conf->wait_for_stripe,
305                                     conf->quiesce == 0,
306                                     conf->device_lock, /* nothing */);
307                 sh = __find_stripe(conf, sector, disks);
308                 if (!sh) {
309                         if (!conf->inactive_blocked)
310                                 sh = get_free_stripe(conf);
311                         if (noblock && sh == NULL)
312                                 break;
313                         if (!sh) {
314                                 conf->inactive_blocked = 1;
315                                 wait_event_lock_irq(conf->wait_for_stripe,
316                                                     !list_empty(&conf->inactive_list) &&
317                                                     (atomic_read(&conf->active_stripes)
318                                                      < (conf->max_nr_stripes *3/4)
319                                                      || !conf->inactive_blocked),
320                                                     conf->device_lock,
321                                                     raid5_unplug_device(conf->mddev->queue)
322                                         );
323                                 conf->inactive_blocked = 0;
324                         } else
325                                 init_stripe(sh, sector, pd_idx, disks);
326                 } else {
327                         if (atomic_read(&sh->count)) {
328                           BUG_ON(!list_empty(&sh->lru));
329                         } else {
330                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
331                                         atomic_inc(&conf->active_stripes);
332                                 if (list_empty(&sh->lru) &&
333                                     !test_bit(STRIPE_EXPANDING, &sh->state))
334                                         BUG();
335                                 list_del_init(&sh->lru);
336                         }
337                 }
338         } while (sh == NULL);
339
340         if (sh)
341                 atomic_inc(&sh->count);
342
343         spin_unlock_irq(&conf->device_lock);
344         return sh;
345 }
346
347 /* test_and_ack_op() ensures that we only dequeue an operation once */
348 #define test_and_ack_op(op, pend) \
349 do {                                                    \
350         if (test_bit(op, &sh->ops.pending) &&           \
351                 !test_bit(op, &sh->ops.complete)) {     \
352                 if (test_and_set_bit(op, &sh->ops.ack)) \
353                         clear_bit(op, &pend);           \
354                 else                                    \
355                         ack++;                          \
356         } else                                          \
357                 clear_bit(op, &pend);                   \
358 } while (0)
359
360 /* find new work to run, do not resubmit work that is already
361  * in flight
362  */
363 static unsigned long get_stripe_work(struct stripe_head *sh)
364 {
365         unsigned long pending;
366         int ack = 0;
367
368         pending = sh->ops.pending;
369
370         test_and_ack_op(STRIPE_OP_BIOFILL, pending);
371         test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
372         test_and_ack_op(STRIPE_OP_PREXOR, pending);
373         test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
374         test_and_ack_op(STRIPE_OP_POSTXOR, pending);
375         test_and_ack_op(STRIPE_OP_CHECK, pending);
376         if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
377                 ack++;
378
379         sh->ops.count -= ack;
380         if (unlikely(sh->ops.count < 0)) {
381                 printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
382                         "ops.complete: %#lx\n", pending, sh->ops.pending,
383                         sh->ops.ack, sh->ops.complete);
384                 BUG();
385         }
386
387         return pending;
388 }
389
390 static void
391 raid5_end_read_request(struct bio *bi, int error);
392 static void
393 raid5_end_write_request(struct bio *bi, int error);
394
395 static void ops_run_io(struct stripe_head *sh)
396 {
397         raid5_conf_t *conf = sh->raid_conf;
398         int i, disks = sh->disks;
399
400         might_sleep();
401
402         set_bit(STRIPE_IO_STARTED, &sh->state);
403         for (i = disks; i--; ) {
404                 int rw;
405                 struct bio *bi;
406                 mdk_rdev_t *rdev;
407                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
408                         rw = WRITE;
409                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
410                         rw = READ;
411                 else
412                         continue;
413
414                 bi = &sh->dev[i].req;
415
416                 bi->bi_rw = rw;
417                 if (rw == WRITE)
418                         bi->bi_end_io = raid5_end_write_request;
419                 else
420                         bi->bi_end_io = raid5_end_read_request;
421
422                 rcu_read_lock();
423                 rdev = rcu_dereference(conf->disks[i].rdev);
424                 if (rdev && test_bit(Faulty, &rdev->flags))
425                         rdev = NULL;
426                 if (rdev)
427                         atomic_inc(&rdev->nr_pending);
428                 rcu_read_unlock();
429
430                 if (rdev) {
431                         if (test_bit(STRIPE_SYNCING, &sh->state) ||
432                                 test_bit(STRIPE_EXPAND_SOURCE, &sh->state) ||
433                                 test_bit(STRIPE_EXPAND_READY, &sh->state))
434                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
435
436                         bi->bi_bdev = rdev->bdev;
437                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
438                                 __func__, (unsigned long long)sh->sector,
439                                 bi->bi_rw, i);
440                         atomic_inc(&sh->count);
441                         bi->bi_sector = sh->sector + rdev->data_offset;
442                         bi->bi_flags = 1 << BIO_UPTODATE;
443                         bi->bi_vcnt = 1;
444                         bi->bi_max_vecs = 1;
445                         bi->bi_idx = 0;
446                         bi->bi_io_vec = &sh->dev[i].vec;
447                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
448                         bi->bi_io_vec[0].bv_offset = 0;
449                         bi->bi_size = STRIPE_SIZE;
450                         bi->bi_next = NULL;
451                         if (rw == WRITE &&
452                             test_bit(R5_ReWrite, &sh->dev[i].flags))
453                                 atomic_add(STRIPE_SECTORS,
454                                         &rdev->corrected_errors);
455                         generic_make_request(bi);
456                 } else {
457                         if (rw == WRITE)
458                                 set_bit(STRIPE_DEGRADED, &sh->state);
459                         pr_debug("skip op %ld on disc %d for sector %llu\n",
460                                 bi->bi_rw, i, (unsigned long long)sh->sector);
461                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
462                         set_bit(STRIPE_HANDLE, &sh->state);
463                 }
464         }
465 }
466
467 static struct dma_async_tx_descriptor *
468 async_copy_data(int frombio, struct bio *bio, struct page *page,
469         sector_t sector, struct dma_async_tx_descriptor *tx)
470 {
471         struct bio_vec *bvl;
472         struct page *bio_page;
473         int i;
474         int page_offset;
475
476         if (bio->bi_sector >= sector)
477                 page_offset = (signed)(bio->bi_sector - sector) * 512;
478         else
479                 page_offset = (signed)(sector - bio->bi_sector) * -512;
480         bio_for_each_segment(bvl, bio, i) {
481                 int len = bio_iovec_idx(bio, i)->bv_len;
482                 int clen;
483                 int b_offset = 0;
484
485                 if (page_offset < 0) {
486                         b_offset = -page_offset;
487                         page_offset += b_offset;
488                         len -= b_offset;
489                 }
490
491                 if (len > 0 && page_offset + len > STRIPE_SIZE)
492                         clen = STRIPE_SIZE - page_offset;
493                 else
494                         clen = len;
495
496                 if (clen > 0) {
497                         b_offset += bio_iovec_idx(bio, i)->bv_offset;
498                         bio_page = bio_iovec_idx(bio, i)->bv_page;
499                         if (frombio)
500                                 tx = async_memcpy(page, bio_page, page_offset,
501                                         b_offset, clen,
502                                         ASYNC_TX_DEP_ACK,
503                                         tx, NULL, NULL);
504                         else
505                                 tx = async_memcpy(bio_page, page, b_offset,
506                                         page_offset, clen,
507                                         ASYNC_TX_DEP_ACK,
508                                         tx, NULL, NULL);
509                 }
510                 if (clen < len) /* hit end of page */
511                         break;
512                 page_offset +=  len;
513         }
514
515         return tx;
516 }
517
518 static void ops_complete_biofill(void *stripe_head_ref)
519 {
520         struct stripe_head *sh = stripe_head_ref;
521         struct bio *return_bi = NULL;
522         raid5_conf_t *conf = sh->raid_conf;
523         int i;
524
525         pr_debug("%s: stripe %llu\n", __func__,
526                 (unsigned long long)sh->sector);
527
528         /* clear completed biofills */
529         for (i = sh->disks; i--; ) {
530                 struct r5dev *dev = &sh->dev[i];
531
532                 /* acknowledge completion of a biofill operation */
533                 /* and check if we need to reply to a read request,
534                  * new R5_Wantfill requests are held off until
535                  * !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending)
536                  */
537                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
538                         struct bio *rbi, *rbi2;
539
540                         /* The access to dev->read is outside of the
541                          * spin_lock_irq(&conf->device_lock), but is protected
542                          * by the STRIPE_OP_BIOFILL pending bit
543                          */
544                         BUG_ON(!dev->read);
545                         rbi = dev->read;
546                         dev->read = NULL;
547                         while (rbi && rbi->bi_sector <
548                                 dev->sector + STRIPE_SECTORS) {
549                                 rbi2 = r5_next_bio(rbi, dev->sector);
550                                 spin_lock_irq(&conf->device_lock);
551                                 if (--rbi->bi_phys_segments == 0) {
552                                         rbi->bi_next = return_bi;
553                                         return_bi = rbi;
554                                 }
555                                 spin_unlock_irq(&conf->device_lock);
556                                 rbi = rbi2;
557                         }
558                 }
559         }
560         set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
561
562         return_io(return_bi);
563
564         set_bit(STRIPE_HANDLE, &sh->state);
565         release_stripe(sh);
566 }
567
568 static void ops_run_biofill(struct stripe_head *sh)
569 {
570         struct dma_async_tx_descriptor *tx = NULL;
571         raid5_conf_t *conf = sh->raid_conf;
572         int i;
573
574         pr_debug("%s: stripe %llu\n", __func__,
575                 (unsigned long long)sh->sector);
576
577         for (i = sh->disks; i--; ) {
578                 struct r5dev *dev = &sh->dev[i];
579                 if (test_bit(R5_Wantfill, &dev->flags)) {
580                         struct bio *rbi;
581                         spin_lock_irq(&conf->device_lock);
582                         dev->read = rbi = dev->toread;
583                         dev->toread = NULL;
584                         spin_unlock_irq(&conf->device_lock);
585                         while (rbi && rbi->bi_sector <
586                                 dev->sector + STRIPE_SECTORS) {
587                                 tx = async_copy_data(0, rbi, dev->page,
588                                         dev->sector, tx);
589                                 rbi = r5_next_bio(rbi, dev->sector);
590                         }
591                 }
592         }
593
594         atomic_inc(&sh->count);
595         async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
596                 ops_complete_biofill, sh);
597 }
598
599 static void ops_complete_compute5(void *stripe_head_ref)
600 {
601         struct stripe_head *sh = stripe_head_ref;
602         int target = sh->ops.target;
603         struct r5dev *tgt = &sh->dev[target];
604
605         pr_debug("%s: stripe %llu\n", __func__,
606                 (unsigned long long)sh->sector);
607
608         set_bit(R5_UPTODATE, &tgt->flags);
609         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
610         clear_bit(R5_Wantcompute, &tgt->flags);
611         set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
612         set_bit(STRIPE_HANDLE, &sh->state);
613         release_stripe(sh);
614 }
615
616 static struct dma_async_tx_descriptor *
617 ops_run_compute5(struct stripe_head *sh, unsigned long pending)
618 {
619         /* kernel stack size limits the total number of disks */
620         int disks = sh->disks;
621         struct page *xor_srcs[disks];
622         int target = sh->ops.target;
623         struct r5dev *tgt = &sh->dev[target];
624         struct page *xor_dest = tgt->page;
625         int count = 0;
626         struct dma_async_tx_descriptor *tx;
627         int i;
628
629         pr_debug("%s: stripe %llu block: %d\n",
630                 __func__, (unsigned long long)sh->sector, target);
631         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
632
633         for (i = disks; i--; )
634                 if (i != target)
635                         xor_srcs[count++] = sh->dev[i].page;
636
637         atomic_inc(&sh->count);
638
639         if (unlikely(count == 1))
640                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
641                         0, NULL, ops_complete_compute5, sh);
642         else
643                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
644                         ASYNC_TX_XOR_ZERO_DST, NULL,
645                         ops_complete_compute5, sh);
646
647         /* ack now if postxor is not set to be run */
648         if (tx && !test_bit(STRIPE_OP_POSTXOR, &pending))
649                 async_tx_ack(tx);
650
651         return tx;
652 }
653
654 static void ops_complete_prexor(void *stripe_head_ref)
655 {
656         struct stripe_head *sh = stripe_head_ref;
657
658         pr_debug("%s: stripe %llu\n", __func__,
659                 (unsigned long long)sh->sector);
660
661         set_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
662 }
663
664 static struct dma_async_tx_descriptor *
665 ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
666 {
667         /* kernel stack size limits the total number of disks */
668         int disks = sh->disks;
669         struct page *xor_srcs[disks];
670         int count = 0, pd_idx = sh->pd_idx, i;
671
672         /* existing parity data subtracted */
673         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
674
675         pr_debug("%s: stripe %llu\n", __func__,
676                 (unsigned long long)sh->sector);
677
678         for (i = disks; i--; ) {
679                 struct r5dev *dev = &sh->dev[i];
680                 /* Only process blocks that are known to be uptodate */
681                 if (dev->towrite && test_bit(R5_Wantprexor, &dev->flags))
682                         xor_srcs[count++] = dev->page;
683         }
684
685         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
686                 ASYNC_TX_DEP_ACK | ASYNC_TX_XOR_DROP_DST, tx,
687                 ops_complete_prexor, sh);
688
689         return tx;
690 }
691
692 static struct dma_async_tx_descriptor *
693 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
694                  unsigned long pending)
695 {
696         int disks = sh->disks;
697         int pd_idx = sh->pd_idx, i;
698
699         /* check if prexor is active which means only process blocks
700          * that are part of a read-modify-write (Wantprexor)
701          */
702         int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
703
704         pr_debug("%s: stripe %llu\n", __func__,
705                 (unsigned long long)sh->sector);
706
707         for (i = disks; i--; ) {
708                 struct r5dev *dev = &sh->dev[i];
709                 struct bio *chosen;
710                 int towrite;
711
712                 towrite = 0;
713                 if (prexor) { /* rmw */
714                         if (dev->towrite &&
715                             test_bit(R5_Wantprexor, &dev->flags))
716                                 towrite = 1;
717                 } else { /* rcw */
718                         if (i != pd_idx && dev->towrite &&
719                                 test_bit(R5_LOCKED, &dev->flags))
720                                 towrite = 1;
721                 }
722
723                 if (towrite) {
724                         struct bio *wbi;
725
726                         spin_lock(&sh->lock);
727                         chosen = dev->towrite;
728                         dev->towrite = NULL;
729                         BUG_ON(dev->written);
730                         wbi = dev->written = chosen;
731                         spin_unlock(&sh->lock);
732
733                         while (wbi && wbi->bi_sector <
734                                 dev->sector + STRIPE_SECTORS) {
735                                 tx = async_copy_data(1, wbi, dev->page,
736                                         dev->sector, tx);
737                                 wbi = r5_next_bio(wbi, dev->sector);
738                         }
739                 }
740         }
741
742         return tx;
743 }
744
745 static void ops_complete_postxor(void *stripe_head_ref)
746 {
747         struct stripe_head *sh = stripe_head_ref;
748
749         pr_debug("%s: stripe %llu\n", __func__,
750                 (unsigned long long)sh->sector);
751
752         set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
753         set_bit(STRIPE_HANDLE, &sh->state);
754         release_stripe(sh);
755 }
756
757 static void ops_complete_write(void *stripe_head_ref)
758 {
759         struct stripe_head *sh = stripe_head_ref;
760         int disks = sh->disks, i, pd_idx = sh->pd_idx;
761
762         pr_debug("%s: stripe %llu\n", __func__,
763                 (unsigned long long)sh->sector);
764
765         for (i = disks; i--; ) {
766                 struct r5dev *dev = &sh->dev[i];
767                 if (dev->written || i == pd_idx)
768                         set_bit(R5_UPTODATE, &dev->flags);
769         }
770
771         set_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
772         set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
773
774         set_bit(STRIPE_HANDLE, &sh->state);
775         release_stripe(sh);
776 }
777
778 static void
779 ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
780                 unsigned long pending)
781 {
782         /* kernel stack size limits the total number of disks */
783         int disks = sh->disks;
784         struct page *xor_srcs[disks];
785
786         int count = 0, pd_idx = sh->pd_idx, i;
787         struct page *xor_dest;
788         int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
789         unsigned long flags;
790         dma_async_tx_callback callback;
791
792         pr_debug("%s: stripe %llu\n", __func__,
793                 (unsigned long long)sh->sector);
794
795         /* check if prexor is active which means only process blocks
796          * that are part of a read-modify-write (written)
797          */
798         if (prexor) {
799                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
800                 for (i = disks; i--; ) {
801                         struct r5dev *dev = &sh->dev[i];
802                         if (dev->written)
803                                 xor_srcs[count++] = dev->page;
804                 }
805         } else {
806                 xor_dest = sh->dev[pd_idx].page;
807                 for (i = disks; i--; ) {
808                         struct r5dev *dev = &sh->dev[i];
809                         if (i != pd_idx)
810                                 xor_srcs[count++] = dev->page;
811                 }
812         }
813
814         /* check whether this postxor is part of a write */
815         callback = test_bit(STRIPE_OP_BIODRAIN, &pending) ?
816                 ops_complete_write : ops_complete_postxor;
817
818         /* 1/ if we prexor'd then the dest is reused as a source
819          * 2/ if we did not prexor then we are redoing the parity
820          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
821          * for the synchronous xor case
822          */
823         flags = ASYNC_TX_DEP_ACK | ASYNC_TX_ACK |
824                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
825
826         atomic_inc(&sh->count);
827
828         if (unlikely(count == 1)) {
829                 flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
830                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
831                         flags, tx, callback, sh);
832         } else
833                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
834                         flags, tx, callback, sh);
835 }
836
837 static void ops_complete_check(void *stripe_head_ref)
838 {
839         struct stripe_head *sh = stripe_head_ref;
840         int pd_idx = sh->pd_idx;
841
842         pr_debug("%s: stripe %llu\n", __func__,
843                 (unsigned long long)sh->sector);
844
845         if (test_and_clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending) &&
846                 sh->ops.zero_sum_result == 0)
847                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
848
849         set_bit(STRIPE_OP_CHECK, &sh->ops.complete);
850         set_bit(STRIPE_HANDLE, &sh->state);
851         release_stripe(sh);
852 }
853
854 static void ops_run_check(struct stripe_head *sh)
855 {
856         /* kernel stack size limits the total number of disks */
857         int disks = sh->disks;
858         struct page *xor_srcs[disks];
859         struct dma_async_tx_descriptor *tx;
860
861         int count = 0, pd_idx = sh->pd_idx, i;
862         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
863
864         pr_debug("%s: stripe %llu\n", __func__,
865                 (unsigned long long)sh->sector);
866
867         for (i = disks; i--; ) {
868                 struct r5dev *dev = &sh->dev[i];
869                 if (i != pd_idx)
870                         xor_srcs[count++] = dev->page;
871         }
872
873         tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
874                 &sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
875
876         if (tx)
877                 set_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
878         else
879                 clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
880
881         atomic_inc(&sh->count);
882         tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
883                 ops_complete_check, sh);
884 }
885
886 static void raid5_run_ops(struct stripe_head *sh, unsigned long pending)
887 {
888         int overlap_clear = 0, i, disks = sh->disks;
889         struct dma_async_tx_descriptor *tx = NULL;
890
891         if (test_bit(STRIPE_OP_BIOFILL, &pending)) {
892                 ops_run_biofill(sh);
893                 overlap_clear++;
894         }
895
896         if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending))
897                 tx = ops_run_compute5(sh, pending);
898
899         if (test_bit(STRIPE_OP_PREXOR, &pending))
900                 tx = ops_run_prexor(sh, tx);
901
902         if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
903                 tx = ops_run_biodrain(sh, tx, pending);
904                 overlap_clear++;
905         }
906
907         if (test_bit(STRIPE_OP_POSTXOR, &pending))
908                 ops_run_postxor(sh, tx, pending);
909
910         if (test_bit(STRIPE_OP_CHECK, &pending))
911                 ops_run_check(sh);
912
913         if (test_bit(STRIPE_OP_IO, &pending))
914                 ops_run_io(sh);
915
916         if (overlap_clear)
917                 for (i = disks; i--; ) {
918                         struct r5dev *dev = &sh->dev[i];
919                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
920                                 wake_up(&sh->raid_conf->wait_for_overlap);
921                 }
922 }
923
924 static int grow_one_stripe(raid5_conf_t *conf)
925 {
926         struct stripe_head *sh;
927         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
928         if (!sh)
929                 return 0;
930         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
931         sh->raid_conf = conf;
932         spin_lock_init(&sh->lock);
933
934         if (grow_buffers(sh, conf->raid_disks)) {
935                 shrink_buffers(sh, conf->raid_disks);
936                 kmem_cache_free(conf->slab_cache, sh);
937                 return 0;
938         }
939         sh->disks = conf->raid_disks;
940         /* we just created an active stripe so... */
941         atomic_set(&sh->count, 1);
942         atomic_inc(&conf->active_stripes);
943         INIT_LIST_HEAD(&sh->lru);
944         release_stripe(sh);
945         return 1;
946 }
947
948 static int grow_stripes(raid5_conf_t *conf, int num)
949 {
950         struct kmem_cache *sc;
951         int devs = conf->raid_disks;
952
953         sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev));
954         sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev));
955         conf->active_name = 0;
956         sc = kmem_cache_create(conf->cache_name[conf->active_name],
957                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
958                                0, 0, NULL);
959         if (!sc)
960                 return 1;
961         conf->slab_cache = sc;
962         conf->pool_size = devs;
963         while (num--)
964                 if (!grow_one_stripe(conf))
965                         return 1;
966         return 0;
967 }
968
969 #ifdef CONFIG_MD_RAID5_RESHAPE
970 static int resize_stripes(raid5_conf_t *conf, int newsize)
971 {
972         /* Make all the stripes able to hold 'newsize' devices.
973          * New slots in each stripe get 'page' set to a new page.
974          *
975          * This happens in stages:
976          * 1/ create a new kmem_cache and allocate the required number of
977          *    stripe_heads.
978          * 2/ gather all the old stripe_heads and tranfer the pages across
979          *    to the new stripe_heads.  This will have the side effect of
980          *    freezing the array as once all stripe_heads have been collected,
981          *    no IO will be possible.  Old stripe heads are freed once their
982          *    pages have been transferred over, and the old kmem_cache is
983          *    freed when all stripes are done.
984          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
985          *    we simple return a failre status - no need to clean anything up.
986          * 4/ allocate new pages for the new slots in the new stripe_heads.
987          *    If this fails, we don't bother trying the shrink the
988          *    stripe_heads down again, we just leave them as they are.
989          *    As each stripe_head is processed the new one is released into
990          *    active service.
991          *
992          * Once step2 is started, we cannot afford to wait for a write,
993          * so we use GFP_NOIO allocations.
994          */
995         struct stripe_head *osh, *nsh;
996         LIST_HEAD(newstripes);
997         struct disk_info *ndisks;
998         int err = 0;
999         struct kmem_cache *sc;
1000         int i;
1001
1002         if (newsize <= conf->pool_size)
1003                 return 0; /* never bother to shrink */
1004
1005         md_allow_write(conf->mddev);
1006
1007         /* Step 1 */
1008         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1009                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1010                                0, 0, NULL);
1011         if (!sc)
1012                 return -ENOMEM;
1013
1014         for (i = conf->max_nr_stripes; i; i--) {
1015                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
1016                 if (!nsh)
1017                         break;
1018
1019                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
1020
1021                 nsh->raid_conf = conf;
1022                 spin_lock_init(&nsh->lock);
1023
1024                 list_add(&nsh->lru, &newstripes);
1025         }
1026         if (i) {
1027                 /* didn't get enough, give up */
1028                 while (!list_empty(&newstripes)) {
1029                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1030                         list_del(&nsh->lru);
1031                         kmem_cache_free(sc, nsh);
1032                 }
1033                 kmem_cache_destroy(sc);
1034                 return -ENOMEM;
1035         }
1036         /* Step 2 - Must use GFP_NOIO now.
1037          * OK, we have enough stripes, start collecting inactive
1038          * stripes and copying them over
1039          */
1040         list_for_each_entry(nsh, &newstripes, lru) {
1041                 spin_lock_irq(&conf->device_lock);
1042                 wait_event_lock_irq(conf->wait_for_stripe,
1043                                     !list_empty(&conf->inactive_list),
1044                                     conf->device_lock,
1045                                     unplug_slaves(conf->mddev)
1046                         );
1047                 osh = get_free_stripe(conf);
1048                 spin_unlock_irq(&conf->device_lock);
1049                 atomic_set(&nsh->count, 1);
1050                 for(i=0; i<conf->pool_size; i++)
1051                         nsh->dev[i].page = osh->dev[i].page;
1052                 for( ; i<newsize; i++)
1053                         nsh->dev[i].page = NULL;
1054                 kmem_cache_free(conf->slab_cache, osh);
1055         }
1056         kmem_cache_destroy(conf->slab_cache);
1057
1058         /* Step 3.
1059          * At this point, we are holding all the stripes so the array
1060          * is completely stalled, so now is a good time to resize
1061          * conf->disks.
1062          */
1063         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1064         if (ndisks) {
1065                 for (i=0; i<conf->raid_disks; i++)
1066                         ndisks[i] = conf->disks[i];
1067                 kfree(conf->disks);
1068                 conf->disks = ndisks;
1069         } else
1070                 err = -ENOMEM;
1071
1072         /* Step 4, return new stripes to service */
1073         while(!list_empty(&newstripes)) {
1074                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1075                 list_del_init(&nsh->lru);
1076                 for (i=conf->raid_disks; i < newsize; i++)
1077                         if (nsh->dev[i].page == NULL) {
1078                                 struct page *p = alloc_page(GFP_NOIO);
1079                                 nsh->dev[i].page = p;
1080                                 if (!p)
1081                                         err = -ENOMEM;
1082                         }
1083                 release_stripe(nsh);
1084         }
1085         /* critical section pass, GFP_NOIO no longer needed */
1086
1087         conf->slab_cache = sc;
1088         conf->active_name = 1-conf->active_name;
1089         conf->pool_size = newsize;
1090         return err;
1091 }
1092 #endif
1093
1094 static int drop_one_stripe(raid5_conf_t *conf)
1095 {
1096         struct stripe_head *sh;
1097
1098         spin_lock_irq(&conf->device_lock);
1099         sh = get_free_stripe(conf);
1100         spin_unlock_irq(&conf->device_lock);
1101         if (!sh)
1102                 return 0;
1103         BUG_ON(atomic_read(&sh->count));
1104         shrink_buffers(sh, conf->pool_size);
1105         kmem_cache_free(conf->slab_cache, sh);
1106         atomic_dec(&conf->active_stripes);
1107         return 1;
1108 }
1109
1110 static void shrink_stripes(raid5_conf_t *conf)
1111 {
1112         while (drop_one_stripe(conf))
1113                 ;
1114
1115         if (conf->slab_cache)
1116                 kmem_cache_destroy(conf->slab_cache);
1117         conf->slab_cache = NULL;
1118 }
1119
1120 static void raid5_end_read_request(struct bio * bi, int error)
1121 {
1122         struct stripe_head *sh = bi->bi_private;
1123         raid5_conf_t *conf = sh->raid_conf;
1124         int disks = sh->disks, i;
1125         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1126         char b[BDEVNAME_SIZE];
1127         mdk_rdev_t *rdev;
1128
1129
1130         for (i=0 ; i<disks; i++)
1131                 if (bi == &sh->dev[i].req)
1132                         break;
1133
1134         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1135                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1136                 uptodate);
1137         if (i == disks) {
1138                 BUG();
1139                 return;
1140         }
1141
1142         if (uptodate) {
1143                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1144                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1145                         rdev = conf->disks[i].rdev;
1146                         printk(KERN_INFO "raid5:%s: read error corrected (%lu sectors at %llu on %s)\n",
1147                                mdname(conf->mddev), STRIPE_SECTORS,
1148                                (unsigned long long)(sh->sector + rdev->data_offset),
1149                                bdevname(rdev->bdev, b));
1150                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1151                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1152                 }
1153                 if (atomic_read(&conf->disks[i].rdev->read_errors))
1154                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
1155         } else {
1156                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1157                 int retry = 0;
1158                 rdev = conf->disks[i].rdev;
1159
1160                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1161                 atomic_inc(&rdev->read_errors);
1162                 if (conf->mddev->degraded)
1163                         printk(KERN_WARNING "raid5:%s: read error not correctable (sector %llu on %s).\n",
1164                                mdname(conf->mddev),
1165                                (unsigned long long)(sh->sector + rdev->data_offset),
1166                                bdn);
1167                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1168                         /* Oh, no!!! */
1169                         printk(KERN_WARNING "raid5:%s: read error NOT corrected!! (sector %llu on %s).\n",
1170                                mdname(conf->mddev),
1171                                (unsigned long long)(sh->sector + rdev->data_offset),
1172                                bdn);
1173                 else if (atomic_read(&rdev->read_errors)
1174                          > conf->max_nr_stripes)
1175                         printk(KERN_WARNING
1176                                "raid5:%s: Too many read errors, failing device %s.\n",
1177                                mdname(conf->mddev), bdn);
1178                 else
1179                         retry = 1;
1180                 if (retry)
1181                         set_bit(R5_ReadError, &sh->dev[i].flags);
1182                 else {
1183                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1184                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1185                         md_error(conf->mddev, rdev);
1186                 }
1187         }
1188         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1189         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1190         set_bit(STRIPE_HANDLE, &sh->state);
1191         release_stripe(sh);
1192 }
1193
1194 static void raid5_end_write_request (struct bio *bi, int error)
1195 {
1196         struct stripe_head *sh = bi->bi_private;
1197         raid5_conf_t *conf = sh->raid_conf;
1198         int disks = sh->disks, i;
1199         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1200
1201         for (i=0 ; i<disks; i++)
1202                 if (bi == &sh->dev[i].req)
1203                         break;
1204
1205         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1206                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1207                 uptodate);
1208         if (i == disks) {
1209                 BUG();
1210                 return;
1211         }
1212
1213         if (!uptodate)
1214                 md_error(conf->mddev, conf->disks[i].rdev);
1215
1216         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1217         
1218         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1219         set_bit(STRIPE_HANDLE, &sh->state);
1220         release_stripe(sh);
1221 }
1222
1223
1224 static sector_t compute_blocknr(struct stripe_head *sh, int i);
1225         
1226 static void raid5_build_block (struct stripe_head *sh, int i)
1227 {
1228         struct r5dev *dev = &sh->dev[i];
1229
1230         bio_init(&dev->req);
1231         dev->req.bi_io_vec = &dev->vec;
1232         dev->req.bi_vcnt++;
1233         dev->req.bi_max_vecs++;
1234         dev->vec.bv_page = dev->page;
1235         dev->vec.bv_len = STRIPE_SIZE;
1236         dev->vec.bv_offset = 0;
1237
1238         dev->req.bi_sector = sh->sector;
1239         dev->req.bi_private = sh;
1240
1241         dev->flags = 0;
1242         dev->sector = compute_blocknr(sh, i);
1243 }
1244
1245 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1246 {
1247         char b[BDEVNAME_SIZE];
1248         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1249         pr_debug("raid5: error called\n");
1250
1251         if (!test_bit(Faulty, &rdev->flags)) {
1252                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1253                 if (test_and_clear_bit(In_sync, &rdev->flags)) {
1254                         unsigned long flags;
1255                         spin_lock_irqsave(&conf->device_lock, flags);
1256                         mddev->degraded++;
1257                         spin_unlock_irqrestore(&conf->device_lock, flags);
1258                         /*
1259                          * if recovery was running, make sure it aborts.
1260                          */
1261                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
1262                 }
1263                 set_bit(Faulty, &rdev->flags);
1264                 printk (KERN_ALERT
1265                         "raid5: Disk failure on %s, disabling device.\n"
1266                         "raid5: Operation continuing on %d devices.\n",
1267                         bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
1268         }
1269 }
1270
1271 /*
1272  * Input: a 'big' sector number,
1273  * Output: index of the data and parity disk, and the sector # in them.
1274  */
1275 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
1276                         unsigned int data_disks, unsigned int * dd_idx,
1277                         unsigned int * pd_idx, raid5_conf_t *conf)
1278 {
1279         long stripe;
1280         unsigned long chunk_number;
1281         unsigned int chunk_offset;
1282         sector_t new_sector;
1283         int sectors_per_chunk = conf->chunk_size >> 9;
1284
1285         /* First compute the information on this sector */
1286
1287         /*
1288          * Compute the chunk number and the sector offset inside the chunk
1289          */
1290         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1291         chunk_number = r_sector;
1292         BUG_ON(r_sector != chunk_number);
1293
1294         /*
1295          * Compute the stripe number
1296          */
1297         stripe = chunk_number / data_disks;
1298
1299         /*
1300          * Compute the data disk and parity disk indexes inside the stripe
1301          */
1302         *dd_idx = chunk_number % data_disks;
1303
1304         /*
1305          * Select the parity disk based on the user selected algorithm.
1306          */
1307         switch(conf->level) {
1308         case 4:
1309                 *pd_idx = data_disks;
1310                 break;
1311         case 5:
1312                 switch (conf->algorithm) {
1313                 case ALGORITHM_LEFT_ASYMMETRIC:
1314                         *pd_idx = data_disks - stripe % raid_disks;
1315                         if (*dd_idx >= *pd_idx)
1316                                 (*dd_idx)++;
1317                         break;
1318                 case ALGORITHM_RIGHT_ASYMMETRIC:
1319                         *pd_idx = stripe % raid_disks;
1320                         if (*dd_idx >= *pd_idx)
1321                                 (*dd_idx)++;
1322                         break;
1323                 case ALGORITHM_LEFT_SYMMETRIC:
1324                         *pd_idx = data_disks - stripe % raid_disks;
1325                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1326                         break;
1327                 case ALGORITHM_RIGHT_SYMMETRIC:
1328                         *pd_idx = stripe % raid_disks;
1329                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1330                         break;
1331                 default:
1332                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1333                                 conf->algorithm);
1334                 }
1335                 break;
1336         case 6:
1337
1338                 /**** FIX THIS ****/
1339                 switch (conf->algorithm) {
1340                 case ALGORITHM_LEFT_ASYMMETRIC:
1341                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1342                         if (*pd_idx == raid_disks-1)
1343                                 (*dd_idx)++;    /* Q D D D P */
1344                         else if (*dd_idx >= *pd_idx)
1345                                 (*dd_idx) += 2; /* D D P Q D */
1346                         break;
1347                 case ALGORITHM_RIGHT_ASYMMETRIC:
1348                         *pd_idx = stripe % raid_disks;
1349                         if (*pd_idx == raid_disks-1)
1350                                 (*dd_idx)++;    /* Q D D D P */
1351                         else if (*dd_idx >= *pd_idx)
1352                                 (*dd_idx) += 2; /* D D P Q D */
1353                         break;
1354                 case ALGORITHM_LEFT_SYMMETRIC:
1355                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1356                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1357                         break;
1358                 case ALGORITHM_RIGHT_SYMMETRIC:
1359                         *pd_idx = stripe % raid_disks;
1360                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1361                         break;
1362                 default:
1363                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1364                                 conf->algorithm);
1365                 }
1366                 break;
1367         }
1368
1369         /*
1370          * Finally, compute the new sector number
1371          */
1372         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1373         return new_sector;
1374 }
1375
1376
1377 static sector_t compute_blocknr(struct stripe_head *sh, int i)
1378 {
1379         raid5_conf_t *conf = sh->raid_conf;
1380         int raid_disks = sh->disks;
1381         int data_disks = raid_disks - conf->max_degraded;
1382         sector_t new_sector = sh->sector, check;
1383         int sectors_per_chunk = conf->chunk_size >> 9;
1384         sector_t stripe;
1385         int chunk_offset;
1386         int chunk_number, dummy1, dummy2, dd_idx = i;
1387         sector_t r_sector;
1388
1389
1390         chunk_offset = sector_div(new_sector, sectors_per_chunk);
1391         stripe = new_sector;
1392         BUG_ON(new_sector != stripe);
1393
1394         if (i == sh->pd_idx)
1395                 return 0;
1396         switch(conf->level) {
1397         case 4: break;
1398         case 5:
1399                 switch (conf->algorithm) {
1400                 case ALGORITHM_LEFT_ASYMMETRIC:
1401                 case ALGORITHM_RIGHT_ASYMMETRIC:
1402                         if (i > sh->pd_idx)
1403                                 i--;
1404                         break;
1405                 case ALGORITHM_LEFT_SYMMETRIC:
1406                 case ALGORITHM_RIGHT_SYMMETRIC:
1407                         if (i < sh->pd_idx)
1408                                 i += raid_disks;
1409                         i -= (sh->pd_idx + 1);
1410                         break;
1411                 default:
1412                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1413                                conf->algorithm);
1414                 }
1415                 break;
1416         case 6:
1417                 if (i == raid6_next_disk(sh->pd_idx, raid_disks))
1418                         return 0; /* It is the Q disk */
1419                 switch (conf->algorithm) {
1420                 case ALGORITHM_LEFT_ASYMMETRIC:
1421                 case ALGORITHM_RIGHT_ASYMMETRIC:
1422                         if (sh->pd_idx == raid_disks-1)
1423                                 i--;    /* Q D D D P */
1424                         else if (i > sh->pd_idx)
1425                                 i -= 2; /* D D P Q D */
1426                         break;
1427                 case ALGORITHM_LEFT_SYMMETRIC:
1428                 case ALGORITHM_RIGHT_SYMMETRIC:
1429                         if (sh->pd_idx == raid_disks-1)
1430                                 i--; /* Q D D D P */
1431                         else {
1432                                 /* D D P Q D */
1433                                 if (i < sh->pd_idx)
1434                                         i += raid_disks;
1435                                 i -= (sh->pd_idx + 2);
1436                         }
1437                         break;
1438                 default:
1439                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1440                                 conf->algorithm);
1441                 }
1442                 break;
1443         }
1444
1445         chunk_number = stripe * data_disks + i;
1446         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
1447
1448         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
1449         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
1450                 printk(KERN_ERR "compute_blocknr: map not correct\n");
1451                 return 0;
1452         }
1453         return r_sector;
1454 }
1455
1456
1457
1458 /*
1459  * Copy data between a page in the stripe cache, and one or more bion
1460  * The page could align with the middle of the bio, or there could be
1461  * several bion, each with several bio_vecs, which cover part of the page
1462  * Multiple bion are linked together on bi_next.  There may be extras
1463  * at the end of this list.  We ignore them.
1464  */
1465 static void copy_data(int frombio, struct bio *bio,
1466                      struct page *page,
1467                      sector_t sector)
1468 {
1469         char *pa = page_address(page);
1470         struct bio_vec *bvl;
1471         int i;
1472         int page_offset;
1473
1474         if (bio->bi_sector >= sector)
1475                 page_offset = (signed)(bio->bi_sector - sector) * 512;
1476         else
1477                 page_offset = (signed)(sector - bio->bi_sector) * -512;
1478         bio_for_each_segment(bvl, bio, i) {
1479                 int len = bio_iovec_idx(bio,i)->bv_len;
1480                 int clen;
1481                 int b_offset = 0;
1482
1483                 if (page_offset < 0) {
1484                         b_offset = -page_offset;
1485                         page_offset += b_offset;
1486                         len -= b_offset;
1487                 }
1488
1489                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1490                         clen = STRIPE_SIZE - page_offset;
1491                 else clen = len;
1492
1493                 if (clen > 0) {
1494                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
1495                         if (frombio)
1496                                 memcpy(pa+page_offset, ba+b_offset, clen);
1497                         else
1498                                 memcpy(ba+b_offset, pa+page_offset, clen);
1499                         __bio_kunmap_atomic(ba, KM_USER0);
1500                 }
1501                 if (clen < len) /* hit end of page */
1502                         break;
1503                 page_offset +=  len;
1504         }
1505 }
1506
1507 #define check_xor()     do {                                              \
1508                                 if (count == MAX_XOR_BLOCKS) {            \
1509                                 xor_blocks(count, STRIPE_SIZE, dest, ptr);\
1510                                 count = 0;                                \
1511                            }                                              \
1512                         } while(0)
1513
1514 static void compute_parity6(struct stripe_head *sh, int method)
1515 {
1516         raid6_conf_t *conf = sh->raid_conf;
1517         int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
1518         struct bio *chosen;
1519         /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1520         void *ptrs[disks];
1521
1522         qd_idx = raid6_next_disk(pd_idx, disks);
1523         d0_idx = raid6_next_disk(qd_idx, disks);
1524
1525         pr_debug("compute_parity, stripe %llu, method %d\n",
1526                 (unsigned long long)sh->sector, method);
1527
1528         switch(method) {
1529         case READ_MODIFY_WRITE:
1530                 BUG();          /* READ_MODIFY_WRITE N/A for RAID-6 */
1531         case RECONSTRUCT_WRITE:
1532                 for (i= disks; i-- ;)
1533                         if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1534                                 chosen = sh->dev[i].towrite;
1535                                 sh->dev[i].towrite = NULL;
1536
1537                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1538                                         wake_up(&conf->wait_for_overlap);
1539
1540                                 BUG_ON(sh->dev[i].written);
1541                                 sh->dev[i].written = chosen;
1542                         }
1543                 break;
1544         case CHECK_PARITY:
1545                 BUG();          /* Not implemented yet */
1546         }
1547
1548         for (i = disks; i--;)
1549                 if (sh->dev[i].written) {
1550                         sector_t sector = sh->dev[i].sector;
1551                         struct bio *wbi = sh->dev[i].written;
1552                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1553                                 copy_data(1, wbi, sh->dev[i].page, sector);
1554                                 wbi = r5_next_bio(wbi, sector);
1555                         }
1556
1557                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1558                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1559                 }
1560
1561 //      switch(method) {
1562 //      case RECONSTRUCT_WRITE:
1563 //      case CHECK_PARITY:
1564 //      case UPDATE_PARITY:
1565                 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1566                 /* FIX: Is this ordering of drives even remotely optimal? */
1567                 count = 0;
1568                 i = d0_idx;
1569                 do {
1570                         ptrs[count++] = page_address(sh->dev[i].page);
1571                         if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1572                                 printk("block %d/%d not uptodate on parity calc\n", i,count);
1573                         i = raid6_next_disk(i, disks);
1574                 } while ( i != d0_idx );
1575 //              break;
1576 //      }
1577
1578         raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1579
1580         switch(method) {
1581         case RECONSTRUCT_WRITE:
1582                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1583                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1584                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1585                 set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1586                 break;
1587         case UPDATE_PARITY:
1588                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1589                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1590                 break;
1591         }
1592 }
1593
1594
1595 /* Compute one missing block */
1596 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1597 {
1598         int i, count, disks = sh->disks;
1599         void *ptr[MAX_XOR_BLOCKS], *dest, *p;
1600         int pd_idx = sh->pd_idx;
1601         int qd_idx = raid6_next_disk(pd_idx, disks);
1602
1603         pr_debug("compute_block_1, stripe %llu, idx %d\n",
1604                 (unsigned long long)sh->sector, dd_idx);
1605
1606         if ( dd_idx == qd_idx ) {
1607                 /* We're actually computing the Q drive */
1608                 compute_parity6(sh, UPDATE_PARITY);
1609         } else {
1610                 dest = page_address(sh->dev[dd_idx].page);
1611                 if (!nozero) memset(dest, 0, STRIPE_SIZE);
1612                 count = 0;
1613                 for (i = disks ; i--; ) {
1614                         if (i == dd_idx || i == qd_idx)
1615                                 continue;
1616                         p = page_address(sh->dev[i].page);
1617                         if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1618                                 ptr[count++] = p;
1619                         else
1620                                 printk("compute_block() %d, stripe %llu, %d"
1621                                        " not present\n", dd_idx,
1622                                        (unsigned long long)sh->sector, i);
1623
1624                         check_xor();
1625                 }
1626                 if (count)
1627                         xor_blocks(count, STRIPE_SIZE, dest, ptr);
1628                 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1629                 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1630         }
1631 }
1632
1633 /* Compute two missing blocks */
1634 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1635 {
1636         int i, count, disks = sh->disks;
1637         int pd_idx = sh->pd_idx;
1638         int qd_idx = raid6_next_disk(pd_idx, disks);
1639         int d0_idx = raid6_next_disk(qd_idx, disks);
1640         int faila, failb;
1641
1642         /* faila and failb are disk numbers relative to d0_idx */
1643         /* pd_idx become disks-2 and qd_idx become disks-1 */
1644         faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1645         failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1646
1647         BUG_ON(faila == failb);
1648         if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1649
1650         pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1651                (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1652
1653         if ( failb == disks-1 ) {
1654                 /* Q disk is one of the missing disks */
1655                 if ( faila == disks-2 ) {
1656                         /* Missing P+Q, just recompute */
1657                         compute_parity6(sh, UPDATE_PARITY);
1658                         return;
1659                 } else {
1660                         /* We're missing D+Q; recompute D from P */
1661                         compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1662                         compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1663                         return;
1664                 }
1665         }
1666
1667         /* We're missing D+P or D+D; build pointer table */
1668         {
1669                 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1670                 void *ptrs[disks];
1671
1672                 count = 0;
1673                 i = d0_idx;
1674                 do {
1675                         ptrs[count++] = page_address(sh->dev[i].page);
1676                         i = raid6_next_disk(i, disks);
1677                         if (i != dd_idx1 && i != dd_idx2 &&
1678                             !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1679                                 printk("compute_2 with missing block %d/%d\n", count, i);
1680                 } while ( i != d0_idx );
1681
1682                 if ( failb == disks-2 ) {
1683                         /* We're missing D+P. */
1684                         raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1685                 } else {
1686                         /* We're missing D+D. */
1687                         raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1688                 }
1689
1690                 /* Both the above update both missing blocks */
1691                 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1692                 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1693         }
1694 }
1695
1696 static int
1697 handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
1698 {
1699         int i, pd_idx = sh->pd_idx, disks = sh->disks;
1700         int locked = 0;
1701
1702         if (rcw) {
1703                 /* if we are not expanding this is a proper write request, and
1704                  * there will be bios with new data to be drained into the
1705                  * stripe cache
1706                  */
1707                 if (!expand) {
1708                         set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
1709                         sh->ops.count++;
1710                 }
1711
1712                 set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
1713                 sh->ops.count++;
1714
1715                 for (i = disks; i--; ) {
1716                         struct r5dev *dev = &sh->dev[i];
1717
1718                         if (dev->towrite) {
1719                                 set_bit(R5_LOCKED, &dev->flags);
1720                                 if (!expand)
1721                                         clear_bit(R5_UPTODATE, &dev->flags);
1722                                 locked++;
1723                         }
1724                 }
1725                 if (locked + 1 == disks)
1726                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
1727                                 atomic_inc(&sh->raid_conf->pending_full_writes);
1728         } else {
1729                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
1730                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
1731
1732                 set_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
1733                 set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
1734                 set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
1735
1736                 sh->ops.count += 3;
1737
1738                 for (i = disks; i--; ) {
1739                         struct r5dev *dev = &sh->dev[i];
1740                         if (i == pd_idx)
1741                                 continue;
1742
1743                         /* For a read-modify write there may be blocks that are
1744                          * locked for reading while others are ready to be
1745                          * written so we distinguish these blocks by the
1746                          * R5_Wantprexor bit
1747                          */
1748                         if (dev->towrite &&
1749                             (test_bit(R5_UPTODATE, &dev->flags) ||
1750                             test_bit(R5_Wantcompute, &dev->flags))) {
1751                                 set_bit(R5_Wantprexor, &dev->flags);
1752                                 set_bit(R5_LOCKED, &dev->flags);
1753                                 clear_bit(R5_UPTODATE, &dev->flags);
1754                                 locked++;
1755                         }
1756                 }
1757         }
1758
1759         /* keep the parity disk locked while asynchronous operations
1760          * are in flight
1761          */
1762         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
1763         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1764         locked++;
1765
1766         pr_debug("%s: stripe %llu locked: %d pending: %lx\n",
1767                 __func__, (unsigned long long)sh->sector,
1768                 locked, sh->ops.pending);
1769
1770         return locked;
1771 }
1772
1773 /*
1774  * Each stripe/dev can have one or more bion attached.
1775  * toread/towrite point to the first in a chain.
1776  * The bi_next chain must be in order.
1777  */
1778 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1779 {
1780         struct bio **bip;
1781         raid5_conf_t *conf = sh->raid_conf;
1782         int firstwrite=0;
1783
1784         pr_debug("adding bh b#%llu to stripe s#%llu\n",
1785                 (unsigned long long)bi->bi_sector,
1786                 (unsigned long long)sh->sector);
1787
1788
1789         spin_lock(&sh->lock);
1790         spin_lock_irq(&conf->device_lock);
1791         if (forwrite) {
1792                 bip = &sh->dev[dd_idx].towrite;
1793                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1794                         firstwrite = 1;
1795         } else
1796                 bip = &sh->dev[dd_idx].toread;
1797         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1798                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1799                         goto overlap;
1800                 bip = & (*bip)->bi_next;
1801         }
1802         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1803                 goto overlap;
1804
1805         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1806         if (*bip)
1807                 bi->bi_next = *bip;
1808         *bip = bi;
1809         bi->bi_phys_segments ++;
1810         spin_unlock_irq(&conf->device_lock);
1811         spin_unlock(&sh->lock);
1812
1813         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
1814                 (unsigned long long)bi->bi_sector,
1815                 (unsigned long long)sh->sector, dd_idx);
1816
1817         if (conf->mddev->bitmap && firstwrite) {
1818                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1819                                   STRIPE_SECTORS, 0);
1820                 sh->bm_seq = conf->seq_flush+1;
1821                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1822         }
1823
1824         if (forwrite) {
1825                 /* check if page is covered */
1826                 sector_t sector = sh->dev[dd_idx].sector;
1827                 for (bi=sh->dev[dd_idx].towrite;
1828                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1829                              bi && bi->bi_sector <= sector;
1830                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1831                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1832                                 sector = bi->bi_sector + (bi->bi_size>>9);
1833                 }
1834                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1835                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1836         }
1837         return 1;
1838
1839  overlap:
1840         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1841         spin_unlock_irq(&conf->device_lock);
1842         spin_unlock(&sh->lock);
1843         return 0;
1844 }
1845
1846 static void end_reshape(raid5_conf_t *conf);
1847
1848 static int page_is_zero(struct page *p)
1849 {
1850         char *a = page_address(p);
1851         return ((*(u32*)a) == 0 &&
1852                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1853 }
1854
1855 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1856 {
1857         int sectors_per_chunk = conf->chunk_size >> 9;
1858         int pd_idx, dd_idx;
1859         int chunk_offset = sector_div(stripe, sectors_per_chunk);
1860
1861         raid5_compute_sector(stripe * (disks - conf->max_degraded)
1862                              *sectors_per_chunk + chunk_offset,
1863                              disks, disks - conf->max_degraded,
1864                              &dd_idx, &pd_idx, conf);
1865         return pd_idx;
1866 }
1867
1868 static void
1869 handle_requests_to_failed_array(raid5_conf_t *conf, struct stripe_head *sh,
1870                                 struct stripe_head_state *s, int disks,
1871                                 struct bio **return_bi)
1872 {
1873         int i;
1874         for (i = disks; i--; ) {
1875                 struct bio *bi;
1876                 int bitmap_end = 0;
1877
1878                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1879                         mdk_rdev_t *rdev;
1880                         rcu_read_lock();
1881                         rdev = rcu_dereference(conf->disks[i].rdev);
1882                         if (rdev && test_bit(In_sync, &rdev->flags))
1883                                 /* multiple read failures in one stripe */
1884                                 md_error(conf->mddev, rdev);
1885                         rcu_read_unlock();
1886                 }
1887                 spin_lock_irq(&conf->device_lock);
1888                 /* fail all writes first */
1889                 bi = sh->dev[i].towrite;
1890                 sh->dev[i].towrite = NULL;
1891                 if (bi) {
1892                         s->to_write--;
1893                         bitmap_end = 1;
1894                 }
1895
1896                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1897                         wake_up(&conf->wait_for_overlap);
1898
1899                 while (bi && bi->bi_sector <
1900                         sh->dev[i].sector + STRIPE_SECTORS) {
1901                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1902                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1903                         if (--bi->bi_phys_segments == 0) {
1904                                 md_write_end(conf->mddev);
1905                                 bi->bi_next = *return_bi;
1906                                 *return_bi = bi;
1907                         }
1908                         bi = nextbi;
1909                 }
1910                 /* and fail all 'written' */
1911                 bi = sh->dev[i].written;
1912                 sh->dev[i].written = NULL;
1913                 if (bi) bitmap_end = 1;
1914                 while (bi && bi->bi_sector <
1915                        sh->dev[i].sector + STRIPE_SECTORS) {
1916                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1917                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1918                         if (--bi->bi_phys_segments == 0) {
1919                                 md_write_end(conf->mddev);
1920                                 bi->bi_next = *return_bi;
1921                                 *return_bi = bi;
1922                         }
1923                         bi = bi2;
1924                 }
1925
1926                 /* fail any reads if this device is non-operational and
1927                  * the data has not reached the cache yet.
1928                  */
1929                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
1930                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1931                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
1932                         bi = sh->dev[i].toread;
1933                         sh->dev[i].toread = NULL;
1934                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1935                                 wake_up(&conf->wait_for_overlap);
1936                         if (bi) s->to_read--;
1937                         while (bi && bi->bi_sector <
1938                                sh->dev[i].sector + STRIPE_SECTORS) {
1939                                 struct bio *nextbi =
1940                                         r5_next_bio(bi, sh->dev[i].sector);
1941                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1942                                 if (--bi->bi_phys_segments == 0) {
1943                                         bi->bi_next = *return_bi;
1944                                         *return_bi = bi;
1945                                 }
1946                                 bi = nextbi;
1947                         }
1948                 }
1949                 spin_unlock_irq(&conf->device_lock);
1950                 if (bitmap_end)
1951                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1952                                         STRIPE_SECTORS, 0, 0);
1953         }
1954
1955         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
1956                 if (atomic_dec_and_test(&conf->pending_full_writes))
1957                         md_wakeup_thread(conf->mddev->thread);
1958 }
1959
1960 /* __handle_issuing_new_read_requests5 - returns 0 if there are no more disks
1961  * to process
1962  */
1963 static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
1964                         struct stripe_head_state *s, int disk_idx, int disks)
1965 {
1966         struct r5dev *dev = &sh->dev[disk_idx];
1967         struct r5dev *failed_dev = &sh->dev[s->failed_num];
1968
1969         /* don't schedule compute operations or reads on the parity block while
1970          * a check is in flight
1971          */
1972         if ((disk_idx == sh->pd_idx) &&
1973              test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
1974                 return ~0;
1975
1976         /* is the data in this block needed, and can we get it? */
1977         if (!test_bit(R5_LOCKED, &dev->flags) &&
1978             !test_bit(R5_UPTODATE, &dev->flags) && (dev->toread ||
1979             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1980              s->syncing || s->expanding || (s->failed &&
1981              (failed_dev->toread || (failed_dev->towrite &&
1982              !test_bit(R5_OVERWRITE, &failed_dev->flags)
1983              ))))) {
1984                 /* 1/ We would like to get this block, possibly by computing it,
1985                  * but we might not be able to.
1986                  *
1987                  * 2/ Since parity check operations potentially make the parity
1988                  * block !uptodate it will need to be refreshed before any
1989                  * compute operations on data disks are scheduled.
1990                  *
1991                  * 3/ We hold off parity block re-reads until check operations
1992                  * have quiesced.
1993                  */
1994                 if ((s->uptodate == disks - 1) &&
1995                     !test_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
1996                         set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
1997                         set_bit(R5_Wantcompute, &dev->flags);
1998                         sh->ops.target = disk_idx;
1999                         s->req_compute = 1;
2000                         sh->ops.count++;
2001                         /* Careful: from this point on 'uptodate' is in the eye
2002                          * of raid5_run_ops which services 'compute' operations
2003                          * before writes. R5_Wantcompute flags a block that will
2004                          * be R5_UPTODATE by the time it is needed for a
2005                          * subsequent operation.
2006                          */
2007                         s->uptodate++;
2008                         return 0; /* uptodate + compute == disks */
2009                 } else if ((s->uptodate < disks - 1) &&
2010                         test_bit(R5_Insync, &dev->flags)) {
2011                         /* Note: we hold off compute operations while checks are
2012                          * in flight, but we still prefer 'compute' over 'read'
2013                          * hence we only read if (uptodate < * disks-1)
2014                          */
2015                         set_bit(R5_LOCKED, &dev->flags);
2016                         set_bit(R5_Wantread, &dev->flags);
2017                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2018                                 sh->ops.count++;
2019                         s->locked++;
2020                         pr_debug("Reading block %d (sync=%d)\n", disk_idx,
2021                                 s->syncing);
2022                 }
2023         }
2024
2025         return ~0;
2026 }
2027
2028 static void handle_issuing_new_read_requests5(struct stripe_head *sh,
2029                         struct stripe_head_state *s, int disks)
2030 {
2031         int i;
2032
2033         /* Clear completed compute operations.  Parity recovery
2034          * (STRIPE_OP_MOD_REPAIR_PD) implies a write-back which is handled
2035          * later on in this routine
2036          */
2037         if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
2038                 !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2039                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
2040                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
2041                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2042         }
2043
2044         /* look for blocks to read/compute, skip this if a compute
2045          * is already in flight, or if the stripe contents are in the
2046          * midst of changing due to a write
2047          */
2048         if (!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
2049                 !test_bit(STRIPE_OP_PREXOR, &sh->ops.pending) &&
2050                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2051                 for (i = disks; i--; )
2052                         if (__handle_issuing_new_read_requests5(
2053                                 sh, s, i, disks) == 0)
2054                                 break;
2055         }
2056         set_bit(STRIPE_HANDLE, &sh->state);
2057 }
2058
2059 static void handle_issuing_new_read_requests6(struct stripe_head *sh,
2060                         struct stripe_head_state *s, struct r6_state *r6s,
2061                         int disks)
2062 {
2063         int i;
2064         for (i = disks; i--; ) {
2065                 struct r5dev *dev = &sh->dev[i];
2066                 if (!test_bit(R5_LOCKED, &dev->flags) &&
2067                     !test_bit(R5_UPTODATE, &dev->flags) &&
2068                     (dev->toread || (dev->towrite &&
2069                      !test_bit(R5_OVERWRITE, &dev->flags)) ||
2070                      s->syncing || s->expanding ||
2071                      (s->failed >= 1 &&
2072                       (sh->dev[r6s->failed_num[0]].toread ||
2073                        s->to_write)) ||
2074                      (s->failed >= 2 &&
2075                       (sh->dev[r6s->failed_num[1]].toread ||
2076                        s->to_write)))) {
2077                         /* we would like to get this block, possibly
2078                          * by computing it, but we might not be able to
2079                          */
2080                         if (s->uptodate == disks-1) {
2081                                 pr_debug("Computing stripe %llu block %d\n",
2082                                        (unsigned long long)sh->sector, i);
2083                                 compute_block_1(sh, i, 0);
2084                                 s->uptodate++;
2085                         } else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
2086                                 /* Computing 2-failure is *very* expensive; only
2087                                  * do it if failed >= 2
2088                                  */
2089                                 int other;
2090                                 for (other = disks; other--; ) {
2091                                         if (other == i)
2092                                                 continue;
2093                                         if (!test_bit(R5_UPTODATE,
2094                                               &sh->dev[other].flags))
2095                                                 break;
2096                                 }
2097                                 BUG_ON(other < 0);
2098                                 pr_debug("Computing stripe %llu blocks %d,%d\n",
2099                                        (unsigned long long)sh->sector,
2100                                        i, other);
2101                                 compute_block_2(sh, i, other);
2102                                 s->uptodate += 2;
2103                         } else if (test_bit(R5_Insync, &dev->flags)) {
2104                                 set_bit(R5_LOCKED, &dev->flags);
2105                                 set_bit(R5_Wantread, &dev->flags);
2106                                 s->locked++;
2107                                 pr_debug("Reading block %d (sync=%d)\n",
2108                                         i, s->syncing);
2109                         }
2110                 }
2111         }
2112         set_bit(STRIPE_HANDLE, &sh->state);
2113 }
2114
2115
2116 /* handle_completed_write_requests
2117  * any written block on an uptodate or failed drive can be returned.
2118  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2119  * never LOCKED, so we don't need to test 'failed' directly.
2120  */
2121 static void handle_completed_write_requests(raid5_conf_t *conf,
2122         struct stripe_head *sh, int disks, struct bio **return_bi)
2123 {
2124         int i;
2125         struct r5dev *dev;
2126
2127         for (i = disks; i--; )
2128                 if (sh->dev[i].written) {
2129                         dev = &sh->dev[i];
2130                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2131                                 test_bit(R5_UPTODATE, &dev->flags)) {
2132                                 /* We can return any write requests */
2133                                 struct bio *wbi, *wbi2;
2134                                 int bitmap_end = 0;
2135                                 pr_debug("Return write for disc %d\n", i);
2136                                 spin_lock_irq(&conf->device_lock);
2137                                 wbi = dev->written;
2138                                 dev->written = NULL;
2139                                 while (wbi && wbi->bi_sector <
2140                                         dev->sector + STRIPE_SECTORS) {
2141                                         wbi2 = r5_next_bio(wbi, dev->sector);
2142                                         if (--wbi->bi_phys_segments == 0) {
2143                                                 md_write_end(conf->mddev);
2144                                                 wbi->bi_next = *return_bi;
2145                                                 *return_bi = wbi;
2146                                         }
2147                                         wbi = wbi2;
2148                                 }
2149                                 if (dev->towrite == NULL)
2150                                         bitmap_end = 1;
2151                                 spin_unlock_irq(&conf->device_lock);
2152                                 if (bitmap_end)
2153                                         bitmap_endwrite(conf->mddev->bitmap,
2154                                                         sh->sector,
2155                                                         STRIPE_SECTORS,
2156                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2157                                                         0);
2158                         }
2159                 }
2160
2161         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2162                 if (atomic_dec_and_test(&conf->pending_full_writes))
2163                         md_wakeup_thread(conf->mddev->thread);
2164 }
2165
2166 static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
2167                 struct stripe_head *sh, struct stripe_head_state *s, int disks)
2168 {
2169         int rmw = 0, rcw = 0, i;
2170         for (i = disks; i--; ) {
2171                 /* would I have to read this buffer for read_modify_write */
2172                 struct r5dev *dev = &sh->dev[i];
2173                 if ((dev->towrite || i == sh->pd_idx) &&
2174                     !test_bit(R5_LOCKED, &dev->flags) &&
2175                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2176                       test_bit(R5_Wantcompute, &dev->flags))) {
2177                         if (test_bit(R5_Insync, &dev->flags))
2178                                 rmw++;
2179                         else
2180                                 rmw += 2*disks;  /* cannot read it */
2181                 }
2182                 /* Would I have to read this buffer for reconstruct_write */
2183                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2184                     !test_bit(R5_LOCKED, &dev->flags) &&
2185                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2186                     test_bit(R5_Wantcompute, &dev->flags))) {
2187                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2188                         else
2189                                 rcw += 2*disks;
2190                 }
2191         }
2192         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2193                 (unsigned long long)sh->sector, rmw, rcw);
2194         set_bit(STRIPE_HANDLE, &sh->state);
2195         if (rmw < rcw && rmw > 0)
2196                 /* prefer read-modify-write, but need to get some data */
2197                 for (i = disks; i--; ) {
2198                         struct r5dev *dev = &sh->dev[i];
2199                         if ((dev->towrite || i == sh->pd_idx) &&
2200                             !test_bit(R5_LOCKED, &dev->flags) &&
2201                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2202                             test_bit(R5_Wantcompute, &dev->flags)) &&
2203                             test_bit(R5_Insync, &dev->flags)) {
2204                                 if (
2205                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2206                                         pr_debug("Read_old block "
2207                                                 "%d for r-m-w\n", i);
2208                                         set_bit(R5_LOCKED, &dev->flags);
2209                                         set_bit(R5_Wantread, &dev->flags);
2210                                         if (!test_and_set_bit(
2211                                                 STRIPE_OP_IO, &sh->ops.pending))
2212                                                 sh->ops.count++;
2213                                         s->locked++;
2214                                 } else {
2215                                         set_bit(STRIPE_DELAYED, &sh->state);
2216                                         set_bit(STRIPE_HANDLE, &sh->state);
2217                                 }
2218                         }
2219                 }
2220         if (rcw <= rmw && rcw > 0)
2221                 /* want reconstruct write, but need to get some data */
2222                 for (i = disks; i--; ) {
2223                         struct r5dev *dev = &sh->dev[i];
2224                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2225                             i != sh->pd_idx &&
2226                             !test_bit(R5_LOCKED, &dev->flags) &&
2227                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2228                             test_bit(R5_Wantcompute, &dev->flags)) &&
2229                             test_bit(R5_Insync, &dev->flags)) {
2230                                 if (
2231                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2232                                         pr_debug("Read_old block "
2233                                                 "%d for Reconstruct\n", i);
2234                                         set_bit(R5_LOCKED, &dev->flags);
2235                                         set_bit(R5_Wantread, &dev->flags);
2236                                         if (!test_and_set_bit(
2237                                                 STRIPE_OP_IO, &sh->ops.pending))
2238                                                 sh->ops.count++;
2239                                         s->locked++;
2240                                 } else {
2241                                         set_bit(STRIPE_DELAYED, &sh->state);
2242                                         set_bit(STRIPE_HANDLE, &sh->state);
2243                                 }
2244                         }
2245                 }
2246         /* now if nothing is locked, and if we have enough data,
2247          * we can start a write request
2248          */
2249         /* since handle_stripe can be called at any time we need to handle the
2250          * case where a compute block operation has been submitted and then a
2251          * subsequent call wants to start a write request.  raid5_run_ops only
2252          * handles the case where compute block and postxor are requested
2253          * simultaneously.  If this is not the case then new writes need to be
2254          * held off until the compute completes.
2255          */
2256         if ((s->req_compute ||
2257             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) &&
2258                 (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2259                 !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2260                 s->locked += handle_write_operations5(sh, rcw == 0, 0);
2261 }
2262
2263 static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
2264                 struct stripe_head *sh, struct stripe_head_state *s,
2265                 struct r6_state *r6s, int disks)
2266 {
2267         int rcw = 0, must_compute = 0, pd_idx = sh->pd_idx, i;
2268         int qd_idx = r6s->qd_idx;
2269         for (i = disks; i--; ) {
2270                 struct r5dev *dev = &sh->dev[i];
2271                 /* Would I have to read this buffer for reconstruct_write */
2272                 if (!test_bit(R5_OVERWRITE, &dev->flags)
2273                     && i != pd_idx && i != qd_idx
2274                     && (!test_bit(R5_LOCKED, &dev->flags)
2275                             ) &&
2276                     !test_bit(R5_UPTODATE, &dev->flags)) {
2277                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2278                         else {
2279                                 pr_debug("raid6: must_compute: "
2280                                         "disk %d flags=%#lx\n", i, dev->flags);
2281                                 must_compute++;
2282                         }
2283                 }
2284         }
2285         pr_debug("for sector %llu, rcw=%d, must_compute=%d\n",
2286                (unsigned long long)sh->sector, rcw, must_compute);
2287         set_bit(STRIPE_HANDLE, &sh->state);
2288
2289         if (rcw > 0)
2290                 /* want reconstruct write, but need to get some data */
2291                 for (i = disks; i--; ) {
2292                         struct r5dev *dev = &sh->dev[i];
2293                         if (!test_bit(R5_OVERWRITE, &dev->flags)
2294                             && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
2295                             && !test_bit(R5_LOCKED, &dev->flags) &&
2296                             !test_bit(R5_UPTODATE, &dev->flags) &&
2297                             test_bit(R5_Insync, &dev->flags)) {
2298                                 if (
2299                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2300                                         pr_debug("Read_old stripe %llu "
2301                                                 "block %d for Reconstruct\n",
2302                                              (unsigned long long)sh->sector, i);
2303                                         set_bit(R5_LOCKED, &dev->flags);
2304                                         set_bit(R5_Wantread, &dev->flags);
2305                                         s->locked++;
2306                                 } else {
2307                                         pr_debug("Request delayed stripe %llu "
2308                                                 "block %d for Reconstruct\n",
2309                                              (unsigned long long)sh->sector, i);
2310                                         set_bit(STRIPE_DELAYED, &sh->state);
2311                                         set_bit(STRIPE_HANDLE, &sh->state);
2312                                 }
2313                         }
2314                 }
2315         /* now if nothing is locked, and if we have enough data, we can start a
2316          * write request
2317          */
2318         if (s->locked == 0 && rcw == 0 &&
2319             !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2320                 if (must_compute > 0) {
2321                         /* We have failed blocks and need to compute them */
2322                         switch (s->failed) {
2323                         case 0:
2324                                 BUG();
2325                         case 1:
2326                                 compute_block_1(sh, r6s->failed_num[0], 0);
2327                                 break;
2328                         case 2:
2329                                 compute_block_2(sh, r6s->failed_num[0],
2330                                                 r6s->failed_num[1]);
2331                                 break;
2332                         default: /* This request should have been failed? */
2333                                 BUG();
2334                         }
2335                 }
2336
2337                 pr_debug("Computing parity for stripe %llu\n",
2338                         (unsigned long long)sh->sector);
2339                 compute_parity6(sh, RECONSTRUCT_WRITE);
2340                 /* now every locked buffer is ready to be written */
2341                 for (i = disks; i--; )
2342                         if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2343                                 pr_debug("Writing stripe %llu block %d\n",
2344                                        (unsigned long long)sh->sector, i);
2345                                 s->locked++;
2346                                 set_bit(R5_Wantwrite, &sh->dev[i].flags);
2347                         }
2348                 if (s->locked == disks)
2349                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2350                                 atomic_inc(&conf->pending_full_writes);
2351                 /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2352                 set_bit(STRIPE_INSYNC, &sh->state);
2353
2354                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2355                         atomic_dec(&conf->preread_active_stripes);
2356                         if (atomic_read(&conf->preread_active_stripes) <
2357                             IO_THRESHOLD)
2358                                 md_wakeup_thread(conf->mddev->thread);
2359                 }
2360         }
2361 }
2362
2363 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2364                                 struct stripe_head_state *s, int disks)
2365 {
2366         int canceled_check = 0;
2367
2368         set_bit(STRIPE_HANDLE, &sh->state);
2369
2370         /* complete a check operation */
2371         if (test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
2372                 clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
2373                 clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
2374                 if (s->failed == 0) {
2375                         if (sh->ops.zero_sum_result == 0)
2376                                 /* parity is correct (on disc,
2377                                  * not in buffer any more)
2378                                  */
2379                                 set_bit(STRIPE_INSYNC, &sh->state);
2380                         else {
2381                                 conf->mddev->resync_mismatches +=
2382                                         STRIPE_SECTORS;
2383                                 if (test_bit(
2384                                      MD_RECOVERY_CHECK, &conf->mddev->recovery))
2385                                         /* don't try to repair!! */
2386                                         set_bit(STRIPE_INSYNC, &sh->state);
2387                                 else {
2388                                         set_bit(STRIPE_OP_COMPUTE_BLK,
2389                                                 &sh->ops.pending);
2390                                         set_bit(STRIPE_OP_MOD_REPAIR_PD,
2391                                                 &sh->ops.pending);
2392                                         set_bit(R5_Wantcompute,
2393                                                 &sh->dev[sh->pd_idx].flags);
2394                                         sh->ops.target = sh->pd_idx;
2395                                         sh->ops.count++;
2396                                         s->uptodate++;
2397                                 }
2398                         }
2399                 } else
2400                         canceled_check = 1; /* STRIPE_INSYNC is not set */
2401         }
2402
2403         /* start a new check operation if there are no failures, the stripe is
2404          * not insync, and a repair is not in flight
2405          */
2406         if (s->failed == 0 &&
2407             !test_bit(STRIPE_INSYNC, &sh->state) &&
2408             !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2409                 if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
2410                         BUG_ON(s->uptodate != disks);
2411                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2412                         sh->ops.count++;
2413                         s->uptodate--;
2414                 }
2415         }
2416
2417         /* check if we can clear a parity disk reconstruct */
2418         if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
2419             test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2420
2421                 clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
2422                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
2423                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
2424                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2425         }
2426
2427
2428         /* Wait for check parity and compute block operations to complete
2429          * before write-back.  If a failure occurred while the check operation
2430          * was in flight we need to cycle this stripe through handle_stripe
2431          * since the parity block may not be uptodate
2432          */
2433         if (!canceled_check && !test_bit(STRIPE_INSYNC, &sh->state) &&
2434             !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
2435             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
2436                 struct r5dev *dev;
2437                 /* either failed parity check, or recovery is happening */
2438                 if (s->failed == 0)
2439                         s->failed_num = sh->pd_idx;
2440                 dev = &sh->dev[s->failed_num];
2441                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2442                 BUG_ON(s->uptodate != disks);
2443
2444                 set_bit(R5_LOCKED, &dev->flags);
2445                 set_bit(R5_Wantwrite, &dev->flags);
2446                 if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2447                         sh->ops.count++;
2448
2449                 clear_bit(STRIPE_DEGRADED, &sh->state);
2450                 s->locked++;
2451                 set_bit(STRIPE_INSYNC, &sh->state);
2452         }
2453 }
2454
2455
2456 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2457                                 struct stripe_head_state *s,
2458                                 struct r6_state *r6s, struct page *tmp_page,
2459                                 int disks)
2460 {
2461         int update_p = 0, update_q = 0;
2462         struct r5dev *dev;
2463         int pd_idx = sh->pd_idx;
2464         int qd_idx = r6s->qd_idx;
2465
2466         set_bit(STRIPE_HANDLE, &sh->state);
2467
2468         BUG_ON(s->failed > 2);
2469         BUG_ON(s->uptodate < disks);
2470         /* Want to check and possibly repair P and Q.
2471          * However there could be one 'failed' device, in which
2472          * case we can only check one of them, possibly using the
2473          * other to generate missing data
2474          */
2475
2476         /* If !tmp_page, we cannot do the calculations,
2477          * but as we have set STRIPE_HANDLE, we will soon be called
2478          * by stripe_handle with a tmp_page - just wait until then.
2479          */
2480         if (tmp_page) {
2481                 if (s->failed == r6s->q_failed) {
2482                         /* The only possible failed device holds 'Q', so it
2483                          * makes sense to check P (If anything else were failed,
2484                          * we would have used P to recreate it).
2485                          */
2486                         compute_block_1(sh, pd_idx, 1);
2487                         if (!page_is_zero(sh->dev[pd_idx].page)) {
2488                                 compute_block_1(sh, pd_idx, 0);
2489                                 update_p = 1;
2490                         }
2491                 }
2492                 if (!r6s->q_failed && s->failed < 2) {
2493                         /* q is not failed, and we didn't use it to generate
2494                          * anything, so it makes sense to check it
2495                          */
2496                         memcpy(page_address(tmp_page),
2497                                page_address(sh->dev[qd_idx].page),
2498                                STRIPE_SIZE);
2499                         compute_parity6(sh, UPDATE_PARITY);
2500                         if (memcmp(page_address(tmp_page),
2501                                    page_address(sh->dev[qd_idx].page),
2502                                    STRIPE_SIZE) != 0) {
2503                                 clear_bit(STRIPE_INSYNC, &sh->state);
2504                                 update_q = 1;
2505                         }
2506                 }
2507                 if (update_p || update_q) {
2508                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2509                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2510                                 /* don't try to repair!! */
2511                                 update_p = update_q = 0;
2512                 }
2513
2514                 /* now write out any block on a failed drive,
2515                  * or P or Q if they need it
2516                  */
2517
2518                 if (s->failed == 2) {
2519                         dev = &sh->dev[r6s->failed_num[1]];
2520                         s->locked++;
2521                         set_bit(R5_LOCKED, &dev->flags);
2522                         set_bit(R5_Wantwrite, &dev->flags);
2523                 }
2524                 if (s->failed >= 1) {
2525                         dev = &sh->dev[r6s->failed_num[0]];
2526                         s->locked++;
2527                         set_bit(R5_LOCKED, &dev->flags);
2528                         set_bit(R5_Wantwrite, &dev->flags);
2529                 }
2530
2531                 if (update_p) {
2532                         dev = &sh->dev[pd_idx];
2533                         s->locked++;
2534                         set_bit(R5_LOCKED, &dev->flags);
2535                         set_bit(R5_Wantwrite, &dev->flags);
2536                 }
2537                 if (update_q) {
2538                         dev = &sh->dev[qd_idx];
2539                         s->locked++;
2540                         set_bit(R5_LOCKED, &dev->flags);
2541                         set_bit(R5_Wantwrite, &dev->flags);
2542                 }
2543                 clear_bit(STRIPE_DEGRADED, &sh->state);
2544
2545                 set_bit(STRIPE_INSYNC, &sh->state);
2546         }
2547 }
2548
2549 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
2550                                 struct r6_state *r6s)
2551 {
2552         int i;
2553
2554         /* We have read all the blocks in this stripe and now we need to
2555          * copy some of them into a target stripe for expand.
2556          */
2557         struct dma_async_tx_descriptor *tx = NULL;
2558         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2559         for (i = 0; i < sh->disks; i++)
2560                 if (i != sh->pd_idx && (!r6s || i != r6s->qd_idx)) {
2561                         int dd_idx, pd_idx, j;
2562                         struct stripe_head *sh2;
2563
2564                         sector_t bn = compute_blocknr(sh, i);
2565                         sector_t s = raid5_compute_sector(bn, conf->raid_disks,
2566                                                 conf->raid_disks -
2567                                                 conf->max_degraded, &dd_idx,
2568                                                 &pd_idx, conf);
2569                         sh2 = get_active_stripe(conf, s, conf->raid_disks,
2570                                                 pd_idx, 1);
2571                         if (sh2 == NULL)
2572                                 /* so far only the early blocks of this stripe
2573                                  * have been requested.  When later blocks
2574                                  * get requested, we will try again
2575                                  */
2576                                 continue;
2577                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2578                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2579                                 /* must have already done this block */
2580                                 release_stripe(sh2);
2581                                 continue;
2582                         }
2583
2584                         /* place all the copies on one channel */
2585                         tx = async_memcpy(sh2->dev[dd_idx].page,
2586                                 sh->dev[i].page, 0, 0, STRIPE_SIZE,
2587                                 ASYNC_TX_DEP_ACK, tx, NULL, NULL);
2588
2589                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2590                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2591                         for (j = 0; j < conf->raid_disks; j++)
2592                                 if (j != sh2->pd_idx &&
2593                                     (!r6s || j != raid6_next_disk(sh2->pd_idx,
2594                                                                  sh2->disks)) &&
2595                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
2596                                         break;
2597                         if (j == conf->raid_disks) {
2598                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
2599                                 set_bit(STRIPE_HANDLE, &sh2->state);
2600                         }
2601                         release_stripe(sh2);
2602
2603                 }
2604         /* done submitting copies, wait for them to complete */
2605         if (tx) {
2606                 async_tx_ack(tx);
2607                 dma_wait_for_async_tx(tx);
2608         }
2609 }
2610
2611
2612 /*
2613  * handle_stripe - do things to a stripe.
2614  *
2615  * We lock the stripe and then examine the state of various bits
2616  * to see what needs to be done.
2617  * Possible results:
2618  *    return some read request which now have data
2619  *    return some write requests which are safely on disc
2620  *    schedule a read on some buffers
2621  *    schedule a write of some buffers
2622  *    return confirmation of parity correctness
2623  *
2624  * buffers are taken off read_list or write_list, and bh_cache buffers
2625  * get BH_Lock set before the stripe lock is released.
2626  *
2627  */
2628
2629 static void handle_stripe5(struct stripe_head *sh)
2630 {
2631         raid5_conf_t *conf = sh->raid_conf;
2632         int disks = sh->disks, i;
2633         struct bio *return_bi = NULL;
2634         struct stripe_head_state s;
2635         struct r5dev *dev;
2636         unsigned long pending = 0;
2637         mdk_rdev_t *blocked_rdev = NULL;
2638
2639         memset(&s, 0, sizeof(s));
2640         pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d "
2641                 "ops=%lx:%lx:%lx\n", (unsigned long long)sh->sector, sh->state,
2642                 atomic_read(&sh->count), sh->pd_idx,
2643                 sh->ops.pending, sh->ops.ack, sh->ops.complete);
2644
2645         spin_lock(&sh->lock);
2646         clear_bit(STRIPE_HANDLE, &sh->state);
2647         clear_bit(STRIPE_DELAYED, &sh->state);
2648
2649         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2650         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2651         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2652         /* Now to look around and see what can be done */
2653
2654         /* clean-up completed biofill operations */
2655         if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
2656                 clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
2657                 clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
2658                 clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
2659         }
2660
2661         rcu_read_lock();
2662         for (i=disks; i--; ) {
2663                 mdk_rdev_t *rdev;
2664                 struct r5dev *dev = &sh->dev[i];
2665                 clear_bit(R5_Insync, &dev->flags);
2666
2667                 pr_debug("check %d: state 0x%lx toread %p read %p write %p "
2668                         "written %p\n", i, dev->flags, dev->toread, dev->read,
2669                         dev->towrite, dev->written);
2670
2671                 /* maybe we can request a biofill operation
2672                  *
2673                  * new wantfill requests are only permitted while
2674                  * STRIPE_OP_BIOFILL is clear
2675                  */
2676                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
2677                         !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
2678                         set_bit(R5_Wantfill, &dev->flags);
2679
2680                 /* now count some things */
2681                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2682                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2683                 if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;
2684
2685                 if (test_bit(R5_Wantfill, &dev->flags))
2686                         s.to_fill++;
2687                 else if (dev->toread)
2688                         s.to_read++;
2689                 if (dev->towrite) {
2690                         s.to_write++;
2691                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2692                                 s.non_overwrite++;
2693                 }
2694                 if (dev->written)
2695                         s.written++;
2696                 rdev = rcu_dereference(conf->disks[i].rdev);
2697                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
2698                         blocked_rdev = rdev;
2699                         atomic_inc(&rdev->nr_pending);
2700                         break;
2701                 }
2702                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2703                         /* The ReadError flag will just be confusing now */
2704                         clear_bit(R5_ReadError, &dev->flags);
2705                         clear_bit(R5_ReWrite, &dev->flags);
2706                 }
2707                 if (!rdev || !test_bit(In_sync, &rdev->flags)
2708                     || test_bit(R5_ReadError, &dev->flags)) {
2709                         s.failed++;
2710                         s.failed_num = i;
2711                 } else
2712                         set_bit(R5_Insync, &dev->flags);
2713         }
2714         rcu_read_unlock();
2715
2716         if (unlikely(blocked_rdev)) {
2717                 set_bit(STRIPE_HANDLE, &sh->state);
2718                 goto unlock;
2719         }
2720
2721         if (s.to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
2722                 sh->ops.count++;
2723
2724         pr_debug("locked=%d uptodate=%d to_read=%d"
2725                 " to_write=%d failed=%d failed_num=%d\n",
2726                 s.locked, s.uptodate, s.to_read, s.to_write,
2727                 s.failed, s.failed_num);
2728         /* check if the array has lost two devices and, if so, some requests might
2729          * need to be failed
2730          */
2731         if (s.failed > 1 && s.to_read+s.to_write+s.written)
2732                 handle_requests_to_failed_array(conf, sh, &s, disks,
2733                                                 &return_bi);
2734         if (s.failed > 1 && s.syncing) {
2735                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2736                 clear_bit(STRIPE_SYNCING, &sh->state);
2737                 s.syncing = 0;
2738         }
2739
2740         /* might be able to return some write requests if the parity block
2741          * is safe, or on a failed drive
2742          */
2743         dev = &sh->dev[sh->pd_idx];
2744         if ( s.written &&
2745              ((test_bit(R5_Insync, &dev->flags) &&
2746                !test_bit(R5_LOCKED, &dev->flags) &&
2747                test_bit(R5_UPTODATE, &dev->flags)) ||
2748                (s.failed == 1 && s.failed_num == sh->pd_idx)))
2749                 handle_completed_write_requests(conf, sh, disks, &return_bi);
2750
2751         /* Now we might consider reading some blocks, either to check/generate
2752          * parity, or to satisfy requests
2753          * or to load a block that is being partially written.
2754          */
2755         if (s.to_read || s.non_overwrite ||
2756             (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding ||
2757             test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
2758                 handle_issuing_new_read_requests5(sh, &s, disks);
2759
2760         /* Now we check to see if any write operations have recently
2761          * completed
2762          */
2763
2764         /* leave prexor set until postxor is done, allows us to distinguish
2765          * a rmw from a rcw during biodrain
2766          */
2767         if (test_bit(STRIPE_OP_PREXOR, &sh->ops.complete) &&
2768                 test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
2769
2770                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
2771                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.ack);
2772                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
2773
2774                 for (i = disks; i--; )
2775                         clear_bit(R5_Wantprexor, &sh->dev[i].flags);
2776         }
2777
2778         /* if only POSTXOR is set then this is an 'expand' postxor */
2779         if (test_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete) &&
2780                 test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
2781
2782                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
2783                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.ack);
2784                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
2785
2786                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
2787                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
2788                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
2789
2790                 /* All the 'written' buffers and the parity block are ready to
2791                  * be written back to disk
2792                  */
2793                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
2794                 for (i = disks; i--; ) {
2795                         dev = &sh->dev[i];
2796                         if (test_bit(R5_LOCKED, &dev->flags) &&
2797                                 (i == sh->pd_idx || dev->written)) {
2798                                 pr_debug("Writing block %d\n", i);
2799                                 set_bit(R5_Wantwrite, &dev->flags);
2800                                 if (!test_and_set_bit(
2801                                     STRIPE_OP_IO, &sh->ops.pending))
2802                                         sh->ops.count++;
2803                                 if (!test_bit(R5_Insync, &dev->flags) ||
2804                                     (i == sh->pd_idx && s.failed == 0))
2805                                         set_bit(STRIPE_INSYNC, &sh->state);
2806                         }
2807                 }
2808                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2809                         atomic_dec(&conf->preread_active_stripes);
2810                         if (atomic_read(&conf->preread_active_stripes) <
2811                                 IO_THRESHOLD)
2812                                 md_wakeup_thread(conf->mddev->thread);
2813                 }
2814         }
2815
2816         /* Now to consider new write requests and what else, if anything
2817          * should be read.  We do not handle new writes when:
2818          * 1/ A 'write' operation (copy+xor) is already in flight.
2819          * 2/ A 'check' operation is in flight, as it may clobber the parity
2820          *    block.
2821          */
2822         if (s.to_write && !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending) &&
2823                           !test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
2824                 handle_issuing_new_write_requests5(conf, sh, &s, disks);
2825
2826         /* maybe we need to check and possibly fix the parity for this stripe
2827          * Any reads will already have been scheduled, so we just see if enough
2828          * data is available.  The parity check is held off while parity
2829          * dependent operations are in flight.
2830          */
2831         if ((s.syncing && s.locked == 0 &&
2832              !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
2833              !test_bit(STRIPE_INSYNC, &sh->state)) ||
2834               test_bit(STRIPE_OP_CHECK, &sh->ops.pending) ||
2835               test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending))
2836                 handle_parity_checks5(conf, sh, &s, disks);
2837
2838         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2839                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2840                 clear_bit(STRIPE_SYNCING, &sh->state);
2841         }
2842
2843         /* If the failed drive is just a ReadError, then we might need to progress
2844          * the repair/check process
2845          */
2846         if (s.failed == 1 && !conf->mddev->ro &&
2847             test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
2848             && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
2849             && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
2850                 ) {
2851                 dev = &sh->dev[s.failed_num];
2852                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2853                         set_bit(R5_Wantwrite, &dev->flags);
2854                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2855                                 sh->ops.count++;
2856                         set_bit(R5_ReWrite, &dev->flags);
2857                         set_bit(R5_LOCKED, &dev->flags);
2858                         s.locked++;
2859                 } else {
2860                         /* let's read it back */
2861                         set_bit(R5_Wantread, &dev->flags);
2862                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2863                                 sh->ops.count++;
2864                         set_bit(R5_LOCKED, &dev->flags);
2865                         s.locked++;
2866                 }
2867         }
2868
2869         /* Finish postxor operations initiated by the expansion
2870          * process
2871          */
2872         if (test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete) &&
2873                 !test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending)) {
2874
2875                 clear_bit(STRIPE_EXPANDING, &sh->state);
2876
2877                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
2878                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
2879                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
2880
2881                 for (i = conf->raid_disks; i--; ) {
2882                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2883                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2884                                 sh->ops.count++;
2885                 }
2886         }
2887
2888         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
2889                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2890                 /* Need to write out all blocks after computing parity */
2891                 sh->disks = conf->raid_disks;
2892                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2893                         conf->raid_disks);
2894                 s.locked += handle_write_operations5(sh, 1, 1);
2895         } else if (s.expanded &&
2896                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2897                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
2898                 atomic_dec(&conf->reshape_stripes);
2899                 wake_up(&conf->wait_for_overlap);
2900                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2901         }
2902
2903         if (s.expanding && s.locked == 0 &&
2904             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
2905                 handle_stripe_expansion(conf, sh, NULL);
2906
2907         if (sh->ops.count)
2908                 pending = get_stripe_work(sh);
2909
2910  unlock:
2911         spin_unlock(&sh->lock);
2912
2913         /* wait for this device to become unblocked */
2914         if (unlikely(blocked_rdev))
2915                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
2916
2917         if (pending)
2918                 raid5_run_ops(sh, pending);
2919
2920         return_io(return_bi);
2921
2922 }
2923
2924 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
2925 {
2926         raid6_conf_t *conf = sh->raid_conf;
2927         int disks = sh->disks;
2928         struct bio *return_bi = NULL;
2929         int i, pd_idx = sh->pd_idx;
2930         struct stripe_head_state s;
2931         struct r6_state r6s;
2932         struct r5dev *dev, *pdev, *qdev;
2933         mdk_rdev_t *blocked_rdev = NULL;
2934
2935         r6s.qd_idx = raid6_next_disk(pd_idx, disks);
2936         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
2937                 "pd_idx=%d, qd_idx=%d\n",
2938                (unsigned long long)sh->sector, sh->state,
2939                atomic_read(&sh->count), pd_idx, r6s.qd_idx);
2940         memset(&s, 0, sizeof(s));
2941
2942         spin_lock(&sh->lock);
2943         clear_bit(STRIPE_HANDLE, &sh->state);
2944         clear_bit(STRIPE_DELAYED, &sh->state);
2945
2946         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2947         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2948         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2949         /* Now to look around and see what can be done */
2950
2951         rcu_read_lock();
2952         for (i=disks; i--; ) {
2953                 mdk_rdev_t *rdev;
2954                 dev = &sh->dev[i];
2955                 clear_bit(R5_Insync, &dev->flags);
2956
2957                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
2958                         i, dev->flags, dev->toread, dev->towrite, dev->written);
2959                 /* maybe we can reply to a read */
2960                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
2961                         struct bio *rbi, *rbi2;
2962                         pr_debug("Return read for disc %d\n", i);
2963                         spin_lock_irq(&conf->device_lock);
2964                         rbi = dev->toread;
2965                         dev->toread = NULL;
2966                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
2967                                 wake_up(&conf->wait_for_overlap);
2968                         spin_unlock_irq(&conf->device_lock);
2969                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
2970                                 copy_data(0, rbi, dev->page, dev->sector);
2971                                 rbi2 = r5_next_bio(rbi, dev->sector);
2972                                 spin_lock_irq(&conf->device_lock);
2973                                 if (--rbi->bi_phys_segments == 0) {
2974                                         rbi->bi_next = return_bi;
2975                                         return_bi = rbi;
2976                                 }
2977                                 spin_unlock_irq(&conf->device_lock);
2978                                 rbi = rbi2;
2979                         }
2980                 }
2981
2982                 /* now count some things */
2983                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2984                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2985
2986
2987                 if (dev->toread)
2988                         s.to_read++;
2989                 if (dev->towrite) {
2990                         s.to_write++;
2991                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2992                                 s.non_overwrite++;
2993                 }
2994                 if (dev->written)
2995                         s.written++;
2996                 rdev = rcu_dereference(conf->disks[i].rdev);
2997                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
2998                         blocked_rdev = rdev;
2999                         atomic_inc(&rdev->nr_pending);
3000                         break;
3001                 }
3002                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
3003                         /* The ReadError flag will just be confusing now */
3004                         clear_bit(R5_ReadError, &dev->flags);
3005                         clear_bit(R5_ReWrite, &dev->flags);
3006                 }
3007                 if (!rdev || !test_bit(In_sync, &rdev->flags)
3008                     || test_bit(R5_ReadError, &dev->flags)) {
3009                         if (s.failed < 2)
3010                                 r6s.failed_num[s.failed] = i;
3011                         s.failed++;
3012                 } else
3013                         set_bit(R5_Insync, &dev->flags);
3014         }
3015         rcu_read_unlock();
3016
3017         if (unlikely(blocked_rdev)) {
3018                 set_bit(STRIPE_HANDLE, &sh->state);
3019                 goto unlock;
3020         }
3021         pr_debug("locked=%d uptodate=%d to_read=%d"
3022                " to_write=%d failed=%d failed_num=%d,%d\n",
3023                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3024                r6s.failed_num[0], r6s.failed_num[1]);
3025         /* check if the array has lost >2 devices and, if so, some requests
3026          * might need to be failed
3027          */
3028         if (s.failed > 2 && s.to_read+s.to_write+s.written)
3029                 handle_requests_to_failed_array(conf, sh, &s, disks,
3030                                                 &return_bi);
3031         if (s.failed > 2 && s.syncing) {
3032                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
3033                 clear_bit(STRIPE_SYNCING, &sh->state);
3034                 s.syncing = 0;
3035         }
3036
3037         /*
3038          * might be able to return some write requests if the parity blocks
3039          * are safe, or on a failed drive
3040          */
3041         pdev = &sh->dev[pd_idx];
3042         r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
3043                 || (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
3044         qdev = &sh->dev[r6s.qd_idx];
3045         r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == r6s.qd_idx)
3046                 || (s.failed >= 2 && r6s.failed_num[1] == r6s.qd_idx);
3047
3048         if ( s.written &&
3049              ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3050                              && !test_bit(R5_LOCKED, &pdev->flags)
3051                              && test_bit(R5_UPTODATE, &pdev->flags)))) &&
3052              ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3053                              && !test_bit(R5_LOCKED, &qdev->flags)
3054                              && test_bit(R5_UPTODATE, &qdev->flags)))))
3055                 handle_completed_write_requests(conf, sh, disks, &return_bi);
3056
3057         /* Now we might consider reading some blocks, either to check/generate
3058          * parity, or to satisfy requests
3059          * or to load a block that is being partially written.
3060          */
3061         if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
3062             (s.syncing && (s.uptodate < disks)) || s.expanding)
3063                 handle_issuing_new_read_requests6(sh, &s, &r6s, disks);
3064
3065         /* now to consider writing and what else, if anything should be read */
3066         if (s.to_write)
3067                 handle_issuing_new_write_requests6(conf, sh, &s, &r6s, disks);
3068
3069         /* maybe we need to check and possibly fix the parity for this stripe
3070          * Any reads will already have been scheduled, so we just see if enough
3071          * data is available
3072          */
3073         if (s.syncing && s.locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state))
3074                 handle_parity_checks6(conf, sh, &s, &r6s, tmp_page, disks);
3075
3076         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
3077                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
3078                 clear_bit(STRIPE_SYNCING, &sh->state);
3079         }
3080
3081         /* If the failed drives are just a ReadError, then we might need
3082          * to progress the repair/check process
3083          */
3084         if (s.failed <= 2 && !conf->mddev->ro)
3085                 for (i = 0; i < s.failed; i++) {
3086                         dev = &sh->dev[r6s.failed_num[i]];
3087                         if (test_bit(R5_ReadError, &dev->flags)
3088                             && !test_bit(R5_LOCKED, &dev->flags)
3089                             && test_bit(R5_UPTODATE, &dev->flags)
3090                                 ) {
3091                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3092                                         set_bit(R5_Wantwrite, &dev->flags);
3093                                         set_bit(R5_ReWrite, &dev->flags);
3094                                         set_bit(R5_LOCKED, &dev->flags);
3095                                 } else {
3096                                         /* let's read it back */
3097                                         set_bit(R5_Wantread, &dev->flags);
3098                                         set_bit(R5_LOCKED, &dev->flags);
3099                                 }
3100                         }
3101                 }
3102
3103         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
3104                 /* Need to write out all blocks after computing P&Q */
3105                 sh->disks = conf->raid_disks;
3106                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
3107                                              conf->raid_disks);
3108                 compute_parity6(sh, RECONSTRUCT_WRITE);
3109                 for (i = conf->raid_disks ; i-- ;  ) {
3110                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3111                         s.locked++;
3112                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3113                 }
3114                 clear_bit(STRIPE_EXPANDING, &sh->state);
3115         } else if (s.expanded) {
3116                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3117                 atomic_dec(&conf->reshape_stripes);
3118                 wake_up(&conf->wait_for_overlap);
3119                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3120         }
3121
3122         if (s.expanding && s.locked == 0 &&
3123             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
3124                 handle_stripe_expansion(conf, sh, &r6s);
3125
3126  unlock:
3127         spin_unlock(&sh->lock);
3128
3129         /* wait for this device to become unblocked */
3130         if (unlikely(blocked_rdev))
3131                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
3132
3133         return_io(return_bi);
3134
3135         for (i=disks; i-- ;) {
3136                 int rw;
3137                 struct bio *bi;
3138                 mdk_rdev_t *rdev;
3139                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
3140                         rw = WRITE;
3141                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
3142                         rw = READ;
3143                 else
3144                         continue;
3145
3146                 set_bit(STRIPE_IO_STARTED, &sh->state);
3147
3148                 bi = &sh->dev[i].req;
3149
3150                 bi->bi_rw = rw;
3151                 if (rw == WRITE)
3152                         bi->bi_end_io = raid5_end_write_request;
3153                 else
3154                         bi->bi_end_io = raid5_end_read_request;
3155
3156                 rcu_read_lock();
3157                 rdev = rcu_dereference(conf->disks[i].rdev);
3158                 if (rdev && test_bit(Faulty, &rdev->flags))
3159                         rdev = NULL;
3160                 if (rdev)
3161                         atomic_inc(&rdev->nr_pending);
3162                 rcu_read_unlock();
3163
3164                 if (rdev) {
3165                         if (s.syncing || s.expanding || s.expanded)
3166                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
3167
3168                         bi->bi_bdev = rdev->bdev;
3169                         pr_debug("for %llu schedule op %ld on disc %d\n",
3170                                 (unsigned long long)sh->sector, bi->bi_rw, i);
3171                         atomic_inc(&sh->count);
3172                         bi->bi_sector = sh->sector + rdev->data_offset;
3173                         bi->bi_flags = 1 << BIO_UPTODATE;
3174                         bi->bi_vcnt = 1;
3175                         bi->bi_max_vecs = 1;
3176                         bi->bi_idx = 0;
3177                         bi->bi_io_vec = &sh->dev[i].vec;
3178                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
3179                         bi->bi_io_vec[0].bv_offset = 0;
3180                         bi->bi_size = STRIPE_SIZE;
3181                         bi->bi_next = NULL;
3182                         if (rw == WRITE &&
3183                             test_bit(R5_ReWrite, &sh->dev[i].flags))
3184                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
3185                         generic_make_request(bi);
3186                 } else {
3187                         if (rw == WRITE)
3188                                 set_bit(STRIPE_DEGRADED, &sh->state);
3189                         pr_debug("skip op %ld on disc %d for sector %llu\n",
3190                                 bi->bi_rw, i, (unsigned long long)sh->sector);
3191                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
3192                         set_bit(STRIPE_HANDLE, &sh->state);
3193                 }
3194         }
3195 }
3196
3197 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
3198 {
3199         if (sh->raid_conf->level == 6)
3200                 handle_stripe6(sh, tmp_page);
3201         else
3202                 handle_stripe5(sh);
3203 }
3204
3205
3206
3207 static void raid5_activate_delayed(raid5_conf_t *conf)
3208 {
3209         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3210                 while (!list_empty(&conf->delayed_list)) {
3211                         struct list_head *l = conf->delayed_list.next;
3212                         struct stripe_head *sh;
3213                         sh = list_entry(l, struct stripe_head, lru);
3214                         list_del_init(l);
3215                         clear_bit(STRIPE_DELAYED, &sh->state);
3216                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3217                                 atomic_inc(&conf->preread_active_stripes);
3218                         list_add_tail(&sh->lru, &conf->hold_list);
3219                 }
3220         } else
3221                 blk_plug_device(conf->mddev->queue);
3222 }
3223
3224 static void activate_bit_delay(raid5_conf_t *conf)
3225 {
3226         /* device_lock is held */
3227         struct list_head head;
3228         list_add(&head, &conf->bitmap_list);
3229         list_del_init(&conf->bitmap_list);
3230         while (!list_empty(&head)) {
3231                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3232                 list_del_init(&sh->lru);
3233                 atomic_inc(&sh->count);
3234                 __release_stripe(conf, sh);
3235         }
3236 }
3237
3238 static void unplug_slaves(mddev_t *mddev)
3239 {
3240         raid5_conf_t *conf = mddev_to_conf(mddev);
3241         int i;
3242
3243         rcu_read_lock();
3244         for (i=0; i<mddev->raid_disks; i++) {
3245                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3246                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
3247                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
3248
3249                         atomic_inc(&rdev->nr_pending);
3250                         rcu_read_unlock();
3251
3252                         blk_unplug(r_queue);
3253
3254                         rdev_dec_pending(rdev, mddev);
3255                         rcu_read_lock();
3256                 }
3257         }
3258         rcu_read_unlock();
3259 }
3260
3261 static void raid5_unplug_device(struct request_queue *q)
3262 {
3263         mddev_t *mddev = q->queuedata;
3264         raid5_conf_t *conf = mddev_to_conf(mddev);
3265         unsigned long flags;
3266
3267         spin_lock_irqsave(&conf->device_lock, flags);
3268
3269         if (blk_remove_plug(q)) {
3270                 conf->seq_flush++;
3271                 raid5_activate_delayed(conf);
3272         }
3273         md_wakeup_thread(mddev->thread);
3274
3275         spin_unlock_irqrestore(&conf->device_lock, flags);
3276
3277         unplug_slaves(mddev);
3278 }
3279
3280 static int raid5_congested(void *data, int bits)
3281 {
3282         mddev_t *mddev = data;
3283         raid5_conf_t *conf = mddev_to_conf(mddev);
3284
3285         /* No difference between reads and writes.  Just check
3286          * how busy the stripe_cache is
3287          */
3288         if (conf->inactive_blocked)
3289                 return 1;
3290         if (conf->quiesce)
3291                 return 1;
3292         if (list_empty_careful(&conf->inactive_list))
3293                 return 1;
3294
3295         return 0;
3296 }
3297
3298 /* We want read requests to align with chunks where possible,
3299  * but write requests don't need to.
3300  */
3301 static int raid5_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec)
3302 {
3303         mddev_t *mddev = q->queuedata;
3304         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3305         int max;
3306         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3307         unsigned int bio_sectors = bio->bi_size >> 9;
3308
3309         if (bio_data_dir(bio) == WRITE)
3310                 return biovec->bv_len; /* always allow writes to be mergeable */
3311
3312         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3313         if (max < 0) max = 0;
3314         if (max <= biovec->bv_len && bio_sectors == 0)
3315                 return biovec->bv_len;
3316         else
3317                 return max;
3318 }
3319
3320
3321 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3322 {
3323         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3324         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3325         unsigned int bio_sectors = bio->bi_size >> 9;
3326
3327         return  chunk_sectors >=
3328                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3329 }
3330
3331 /*
3332  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3333  *  later sampled by raid5d.
3334  */
3335 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3336 {
3337         unsigned long flags;
3338
3339         spin_lock_irqsave(&conf->device_lock, flags);
3340
3341         bi->bi_next = conf->retry_read_aligned_list;
3342         conf->retry_read_aligned_list = bi;
3343
3344         spin_unlock_irqrestore(&conf->device_lock, flags);
3345         md_wakeup_thread(conf->mddev->thread);
3346 }
3347
3348
3349 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3350 {
3351         struct bio *bi;
3352
3353         bi = conf->retry_read_aligned;
3354         if (bi) {
3355                 conf->retry_read_aligned = NULL;
3356                 return bi;
3357         }
3358         bi = conf->retry_read_aligned_list;
3359         if(bi) {
3360                 conf->retry_read_aligned_list = bi->bi_next;
3361                 bi->bi_next = NULL;
3362                 bi->bi_phys_segments = 1; /* biased count of active stripes */
3363                 bi->bi_hw_segments = 0; /* count of processed stripes */
3364         }
3365
3366         return bi;
3367 }
3368
3369
3370 /*
3371  *  The "raid5_align_endio" should check if the read succeeded and if it
3372  *  did, call bio_endio on the original bio (having bio_put the new bio
3373  *  first).
3374  *  If the read failed..
3375  */
3376 static void raid5_align_endio(struct bio *bi, int error)
3377 {
3378         struct bio* raid_bi  = bi->bi_private;
3379         mddev_t *mddev;
3380         raid5_conf_t *conf;
3381         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3382         mdk_rdev_t *rdev;
3383
3384         bio_put(bi);
3385
3386         mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
3387         conf = mddev_to_conf(mddev);
3388         rdev = (void*)raid_bi->bi_next;
3389         raid_bi->bi_next = NULL;
3390
3391         rdev_dec_pending(rdev, conf->mddev);
3392
3393         if (!error && uptodate) {
3394                 bio_endio(raid_bi, 0);
3395                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3396                         wake_up(&conf->wait_for_stripe);
3397                 return;
3398         }
3399
3400
3401         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3402
3403         add_bio_to_retry(raid_bi, conf);
3404 }
3405
3406 static int bio_fits_rdev(struct bio *bi)
3407 {
3408         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3409
3410         if ((bi->bi_size>>9) > q->max_sectors)
3411                 return 0;
3412         blk_recount_segments(q, bi);
3413         if (bi->bi_phys_segments > q->max_phys_segments ||
3414             bi->bi_hw_segments > q->max_hw_segments)
3415                 return 0;
3416
3417         if (q->merge_bvec_fn)
3418                 /* it's too hard to apply the merge_bvec_fn at this stage,
3419                  * just just give up
3420                  */
3421                 return 0;
3422
3423         return 1;
3424 }
3425
3426
3427 static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
3428 {
3429         mddev_t *mddev = q->queuedata;
3430         raid5_conf_t *conf = mddev_to_conf(mddev);
3431         const unsigned int raid_disks = conf->raid_disks;
3432         const unsigned int data_disks = raid_disks - conf->max_degraded;
3433         unsigned int dd_idx, pd_idx;
3434         struct bio* align_bi;
3435         mdk_rdev_t *rdev;
3436
3437         if (!in_chunk_boundary(mddev, raid_bio)) {
3438                 pr_debug("chunk_aligned_read : non aligned\n");
3439                 return 0;
3440         }
3441         /*
3442          * use bio_clone to make a copy of the bio
3443          */
3444         align_bi = bio_clone(raid_bio, GFP_NOIO);
3445         if (!align_bi)
3446                 return 0;
3447         /*
3448          *   set bi_end_io to a new function, and set bi_private to the
3449          *     original bio.
3450          */
3451         align_bi->bi_end_io  = raid5_align_endio;
3452         align_bi->bi_private = raid_bio;
3453         /*
3454          *      compute position
3455          */
3456         align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
3457                                         raid_disks,
3458                                         data_disks,
3459                                         &dd_idx,
3460                                         &pd_idx,
3461                                         conf);
3462
3463         rcu_read_lock();
3464         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3465         if (rdev && test_bit(In_sync, &rdev->flags)) {
3466                 atomic_inc(&rdev->nr_pending);
3467                 rcu_read_unlock();
3468                 raid_bio->bi_next = (void*)rdev;
3469                 align_bi->bi_bdev =  rdev->bdev;
3470                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3471                 align_bi->bi_sector += rdev->data_offset;
3472
3473                 if (!bio_fits_rdev(align_bi)) {
3474                         /* too big in some way */
3475                         bio_put(align_bi);
3476                         rdev_dec_pending(rdev, mddev);
3477                         return 0;
3478                 }
3479
3480                 spin_lock_irq(&conf->device_lock);
3481                 wait_event_lock_irq(conf->wait_for_stripe,
3482                                     conf->quiesce == 0,
3483                                     conf->device_lock, /* nothing */);
3484                 atomic_inc(&conf->active_aligned_reads);
3485                 spin_unlock_irq(&conf->device_lock);
3486
3487                 generic_make_request(align_bi);
3488                 return 1;
3489         } else {
3490                 rcu_read_unlock();
3491                 bio_put(align_bi);
3492                 return 0;
3493         }
3494 }
3495
3496 /* __get_priority_stripe - get the next stripe to process
3497  *
3498  * Full stripe writes are allowed to pass preread active stripes up until
3499  * the bypass_threshold is exceeded.  In general the bypass_count
3500  * increments when the handle_list is handled before the hold_list; however, it
3501  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
3502  * stripe with in flight i/o.  The bypass_count will be reset when the
3503  * head of the hold_list has changed, i.e. the head was promoted to the
3504  * handle_list.
3505  */
3506 static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
3507 {
3508         struct stripe_head *sh;
3509
3510         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
3511                   __func__,
3512                   list_empty(&conf->handle_list) ? "empty" : "busy",
3513                   list_empty(&conf->hold_list) ? "empty" : "busy",
3514                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
3515
3516         if (!list_empty(&conf->handle_list)) {
3517                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
3518
3519                 if (list_empty(&conf->hold_list))
3520                         conf->bypass_count = 0;
3521                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
3522                         if (conf->hold_list.next == conf->last_hold)
3523                                 conf->bypass_count++;
3524                         else {
3525                                 conf->last_hold = conf->hold_list.next;
3526                                 conf->bypass_count -= conf->bypass_threshold;
3527                                 if (conf->bypass_count < 0)
3528                                         conf->bypass_count = 0;
3529                         }
3530                 }
3531         } else if (!list_empty(&conf->hold_list) &&
3532                    ((conf->bypass_threshold &&
3533                      conf->bypass_count > conf->bypass_threshold) ||
3534                     atomic_read(&conf->pending_full_writes) == 0)) {
3535                 sh = list_entry(conf->hold_list.next,
3536                                 typeof(*sh), lru);
3537                 conf->bypass_count -= conf->bypass_threshold;
3538                 if (conf->bypass_count < 0)
3539                         conf->bypass_count = 0;
3540         } else
3541                 return NULL;
3542
3543         list_del_init(&sh->lru);
3544         atomic_inc(&sh->count);
3545         BUG_ON(atomic_read(&sh->count) != 1);
3546         return sh;
3547 }
3548
3549 static int make_request(struct request_queue *q, struct bio * bi)
3550 {
3551         mddev_t *mddev = q->queuedata;
3552         raid5_conf_t *conf = mddev_to_conf(mddev);
3553         unsigned int dd_idx, pd_idx;
3554         sector_t new_sector;
3555         sector_t logical_sector, last_sector;
3556         struct stripe_head *sh;
3557         const int rw = bio_data_dir(bi);
3558         int remaining;
3559
3560         if (unlikely(bio_barrier(bi))) {
3561                 bio_endio(bi, -EOPNOTSUPP);
3562                 return 0;
3563         }
3564
3565         md_write_start(mddev, bi);
3566
3567         disk_stat_inc(mddev->gendisk, ios[rw]);
3568         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
3569
3570         if (rw == READ &&
3571              mddev->reshape_position == MaxSector &&
3572              chunk_aligned_read(q,bi))
3573                 return 0;
3574
3575         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3576         last_sector = bi->bi_sector + (bi->bi_size>>9);
3577         bi->bi_next = NULL;
3578         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
3579
3580         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
3581                 DEFINE_WAIT(w);
3582                 int disks, data_disks;
3583
3584         retry:
3585                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
3586                 if (likely(conf->expand_progress == MaxSector))
3587                         disks = conf->raid_disks;
3588                 else {
3589                         /* spinlock is needed as expand_progress may be
3590                          * 64bit on a 32bit platform, and so it might be
3591                          * possible to see a half-updated value
3592                          * Ofcourse expand_progress could change after
3593                          * the lock is dropped, so once we get a reference
3594                          * to the stripe that we think it is, we will have
3595                          * to check again.
3596                          */
3597                         spin_lock_irq(&conf->device_lock);
3598                         disks = conf->raid_disks;
3599                         if (logical_sector >= conf->expand_progress)
3600                                 disks = conf->previous_raid_disks;
3601                         else {
3602                                 if (logical_sector >= conf->expand_lo) {
3603                                         spin_unlock_irq(&conf->device_lock);
3604                                         schedule();
3605                                         goto retry;
3606                                 }
3607                         }
3608                         spin_unlock_irq(&conf->device_lock);
3609                 }
3610                 data_disks = disks - conf->max_degraded;
3611
3612                 new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
3613                                                   &dd_idx, &pd_idx, conf);
3614                 pr_debug("raid5: make_request, sector %llu logical %llu\n",
3615                         (unsigned long long)new_sector, 
3616                         (unsigned long long)logical_sector);
3617
3618                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
3619                 if (sh) {
3620                         if (unlikely(conf->expand_progress != MaxSector)) {
3621                                 /* expansion might have moved on while waiting for a
3622                                  * stripe, so we must do the range check again.
3623                                  * Expansion could still move past after this
3624                                  * test, but as we are holding a reference to
3625                                  * 'sh', we know that if that happens,
3626                                  *  STRIPE_EXPANDING will get set and the expansion
3627                                  * won't proceed until we finish with the stripe.
3628                                  */
3629                                 int must_retry = 0;
3630                                 spin_lock_irq(&conf->device_lock);
3631                                 if (logical_sector <  conf->expand_progress &&
3632                                     disks == conf->previous_raid_disks)
3633                                         /* mismatch, need to try again */
3634                                         must_retry = 1;
3635                                 spin_unlock_irq(&conf->device_lock);
3636                                 if (must_retry) {
3637                                         release_stripe(sh);
3638                                         goto retry;
3639                                 }
3640                         }
3641                         /* FIXME what if we get a false positive because these
3642                          * are being updated.
3643                          */
3644                         if (logical_sector >= mddev->suspend_lo &&
3645                             logical_sector < mddev->suspend_hi) {
3646                                 release_stripe(sh);
3647                                 schedule();
3648                                 goto retry;
3649                         }
3650
3651                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
3652                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
3653                                 /* Stripe is busy expanding or
3654                                  * add failed due to overlap.  Flush everything
3655                                  * and wait a while
3656                                  */
3657                                 raid5_unplug_device(mddev->queue);
3658                                 release_stripe(sh);
3659                                 schedule();
3660                                 goto retry;
3661                         }
3662                         finish_wait(&conf->wait_for_overlap, &w);
3663                         set_bit(STRIPE_HANDLE, &sh->state);
3664                         clear_bit(STRIPE_DELAYED, &sh->state);
3665                         release_stripe(sh);
3666                 } else {
3667                         /* cannot get stripe for read-ahead, just give-up */
3668                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3669                         finish_wait(&conf->wait_for_overlap, &w);
3670                         break;
3671                 }
3672                         
3673         }
3674         spin_lock_irq(&conf->device_lock);
3675         remaining = --bi->bi_phys_segments;
3676         spin_unlock_irq(&conf->device_lock);
3677         if (remaining == 0) {
3678
3679                 if ( rw == WRITE )
3680                         md_write_end(mddev);
3681
3682                 bi->bi_end_io(bi,
3683                               test_bit(BIO_UPTODATE, &bi->bi_flags)
3684                                 ? 0 : -EIO);
3685         }
3686         return 0;
3687 }
3688
3689 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
3690 {
3691         /* reshaping is quite different to recovery/resync so it is
3692          * handled quite separately ... here.
3693          *
3694          * On each call to sync_request, we gather one chunk worth of
3695          * destination stripes and flag them as expanding.
3696          * Then we find all the source stripes and request reads.
3697          * As the reads complete, handle_stripe will copy the data
3698          * into the destination stripe and release that stripe.
3699          */
3700         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3701         struct stripe_head *sh;
3702         int pd_idx;
3703         sector_t first_sector, last_sector;
3704         int raid_disks = conf->previous_raid_disks;
3705         int data_disks = raid_disks - conf->max_degraded;
3706         int new_data_disks = conf->raid_disks - conf->max_degraded;
3707         int i;
3708         int dd_idx;
3709         sector_t writepos, safepos, gap;
3710
3711         if (sector_nr == 0 &&
3712             conf->expand_progress != 0) {
3713                 /* restarting in the middle, skip the initial sectors */
3714                 sector_nr = conf->expand_progress;
3715                 sector_div(sector_nr, new_data_disks);
3716                 *skipped = 1;
3717                 return sector_nr;
3718         }
3719
3720         /* we update the metadata when there is more than 3Meg
3721          * in the block range (that is rather arbitrary, should
3722          * probably be time based) or when the data about to be
3723          * copied would over-write the source of the data at
3724          * the front of the range.
3725          * i.e. one new_stripe forward from expand_progress new_maps
3726          * to after where expand_lo old_maps to
3727          */
3728         writepos = conf->expand_progress +
3729                 conf->chunk_size/512*(new_data_disks);
3730         sector_div(writepos, new_data_disks);
3731         safepos = conf->expand_lo;
3732         sector_div(safepos, data_disks);
3733         gap = conf->expand_progress - conf->expand_lo;
3734
3735         if (writepos >= safepos ||
3736             gap > (new_data_disks)*3000*2 /*3Meg*/) {
3737                 /* Cannot proceed until we've updated the superblock... */
3738                 wait_event(conf->wait_for_overlap,
3739                            atomic_read(&conf->reshape_stripes)==0);
3740                 mddev->reshape_position = conf->expand_progress;
3741                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3742                 md_wakeup_thread(mddev->thread);
3743                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
3744                            kthread_should_stop());
3745                 spin_lock_irq(&conf->device_lock);
3746                 conf->expand_lo = mddev->reshape_position;
3747                 spin_unlock_irq(&conf->device_lock);
3748                 wake_up(&conf->wait_for_overlap);
3749         }
3750
3751         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
3752                 int j;
3753                 int skipped = 0;
3754                 pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
3755                 sh = get_active_stripe(conf, sector_nr+i,
3756                                        conf->raid_disks, pd_idx, 0);
3757                 set_bit(STRIPE_EXPANDING, &sh->state);
3758                 atomic_inc(&conf->reshape_stripes);
3759                 /* If any of this stripe is beyond the end of the old
3760                  * array, then we need to zero those blocks
3761                  */
3762                 for (j=sh->disks; j--;) {
3763                         sector_t s;
3764                         if (j == sh->pd_idx)
3765                                 continue;
3766                         if (conf->level == 6 &&
3767                             j == raid6_next_disk(sh->pd_idx, sh->disks))
3768                                 continue;
3769                         s = compute_blocknr(sh, j);
3770                         if (s < (mddev->array_size<<1)) {
3771                                 skipped = 1;
3772                                 continue;
3773                         }
3774                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
3775                         set_bit(R5_Expanded, &sh->dev[j].flags);
3776                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
3777                 }
3778                 if (!skipped) {
3779                         set_bit(STRIPE_EXPAND_READY, &sh->state);
3780                         set_bit(STRIPE_HANDLE, &sh->state);
3781                 }
3782                 release_stripe(sh);
3783         }
3784         spin_lock_irq(&conf->device_lock);
3785         conf->expand_progress = (sector_nr + i) * new_data_disks;
3786         spin_unlock_irq(&conf->device_lock);
3787         /* Ok, those stripe are ready. We can start scheduling
3788          * reads on the source stripes.
3789          * The source stripes are determined by mapping the first and last
3790          * block on the destination stripes.
3791          */
3792         first_sector =
3793                 raid5_compute_sector(sector_nr*(new_data_disks),
3794                                      raid_disks, data_disks,
3795                                      &dd_idx, &pd_idx, conf);
3796         last_sector =
3797                 raid5_compute_sector((sector_nr+conf->chunk_size/512)
3798                                      *(new_data_disks) -1,
3799                                      raid_disks, data_disks,
3800                                      &dd_idx, &pd_idx, conf);
3801         if (last_sector >= (mddev->size<<1))
3802                 last_sector = (mddev->size<<1)-1;
3803         while (first_sector <= last_sector) {
3804                 pd_idx = stripe_to_pdidx(first_sector, conf,
3805                                          conf->previous_raid_disks);
3806                 sh = get_active_stripe(conf, first_sector,
3807                                        conf->previous_raid_disks, pd_idx, 0);
3808                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3809                 set_bit(STRIPE_HANDLE, &sh->state);
3810                 release_stripe(sh);
3811                 first_sector += STRIPE_SECTORS;
3812         }
3813         /* If this takes us to the resync_max point where we have to pause,
3814          * then we need to write out the superblock.
3815          */
3816         sector_nr += conf->chunk_size>>9;
3817         if (sector_nr >= mddev->resync_max) {
3818                 /* Cannot proceed until we've updated the superblock... */
3819                 wait_event(conf->wait_for_overlap,
3820                            atomic_read(&conf->reshape_stripes) == 0);
3821                 mddev->reshape_position = conf->expand_progress;
3822                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3823                 md_wakeup_thread(mddev->thread);
3824                 wait_event(mddev->sb_wait,
3825                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
3826                            || kthread_should_stop());
3827                 spin_lock_irq(&conf->device_lock);
3828                 conf->expand_lo = mddev->reshape_position;
3829                 spin_unlock_irq(&conf->device_lock);
3830                 wake_up(&conf->wait_for_overlap);
3831         }
3832         return conf->chunk_size>>9;
3833 }
3834
3835 /* FIXME go_faster isn't used */
3836 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
3837 {
3838         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3839         struct stripe_head *sh;
3840         int pd_idx;
3841         int raid_disks = conf->raid_disks;
3842         sector_t max_sector = mddev->size << 1;
3843         int sync_blocks;
3844         int still_degraded = 0;
3845         int i;
3846
3847         if (sector_nr >= max_sector) {
3848                 /* just being told to finish up .. nothing much to do */
3849                 unplug_slaves(mddev);
3850                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
3851                         end_reshape(conf);
3852                         return 0;
3853                 }
3854
3855                 if (mddev->curr_resync < max_sector) /* aborted */
3856                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
3857                                         &sync_blocks, 1);
3858                 else /* completed sync */
3859                         conf->fullsync = 0;
3860                 bitmap_close_sync(mddev->bitmap);
3861
3862                 return 0;
3863         }
3864
3865         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3866                 return reshape_request(mddev, sector_nr, skipped);
3867
3868         /* No need to check resync_max as we never do more than one
3869          * stripe, and as resync_max will always be on a chunk boundary,
3870          * if the check in md_do_sync didn't fire, there is no chance
3871          * of overstepping resync_max here
3872          */
3873
3874         /* if there is too many failed drives and we are trying
3875          * to resync, then assert that we are finished, because there is
3876          * nothing we can do.
3877          */
3878         if (mddev->degraded >= conf->max_degraded &&
3879             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3880                 sector_t rv = (mddev->size << 1) - sector_nr;
3881                 *skipped = 1;
3882                 return rv;
3883         }
3884         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
3885             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
3886             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
3887                 /* we can skip this block, and probably more */
3888                 sync_blocks /= STRIPE_SECTORS;
3889                 *skipped = 1;
3890                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
3891         }
3892
3893
3894         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3895
3896         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
3897         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
3898         if (sh == NULL) {
3899                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
3900                 /* make sure we don't swamp the stripe cache if someone else
3901                  * is trying to get access
3902                  */
3903                 schedule_timeout_uninterruptible(1);
3904         }
3905         /* Need to check if array will still be degraded after recovery/resync
3906          * We don't need to check the 'failed' flag as when that gets set,
3907          * recovery aborts.
3908          */
3909         for (i=0; i<mddev->raid_disks; i++)
3910                 if (conf->disks[i].rdev == NULL)
3911                         still_degraded = 1;
3912
3913         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
3914
3915         spin_lock(&sh->lock);
3916         set_bit(STRIPE_SYNCING, &sh->state);
3917         clear_bit(STRIPE_INSYNC, &sh->state);
3918         spin_unlock(&sh->lock);
3919
3920         handle_stripe(sh, NULL);
3921         release_stripe(sh);
3922
3923         return STRIPE_SECTORS;
3924 }
3925
3926 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
3927 {
3928         /* We may not be able to submit a whole bio at once as there
3929          * may not be enough stripe_heads available.
3930          * We cannot pre-allocate enough stripe_heads as we may need
3931          * more than exist in the cache (if we allow ever large chunks).
3932          * So we do one stripe head at a time and record in
3933          * ->bi_hw_segments how many have been done.
3934          *
3935          * We *know* that this entire raid_bio is in one chunk, so
3936          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
3937          */
3938         struct stripe_head *sh;
3939         int dd_idx, pd_idx;
3940         sector_t sector, logical_sector, last_sector;
3941         int scnt = 0;
3942         int remaining;
3943         int handled = 0;
3944
3945         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3946         sector = raid5_compute_sector(  logical_sector,
3947                                         conf->raid_disks,
3948                                         conf->raid_disks - conf->max_degraded,
3949                                         &dd_idx,
3950                                         &pd_idx,
3951                                         conf);
3952         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
3953
3954         for (; logical_sector < last_sector;
3955              logical_sector += STRIPE_SECTORS,
3956                      sector += STRIPE_SECTORS,
3957                      scnt++) {
3958
3959                 if (scnt < raid_bio->bi_hw_segments)
3960                         /* already done this stripe */
3961                         continue;
3962
3963                 sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
3964
3965                 if (!sh) {
3966                         /* failed to get a stripe - must wait */
3967                         raid_bio->bi_hw_segments = scnt;
3968                         conf->retry_read_aligned = raid_bio;
3969                         return handled;
3970                 }
3971
3972                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
3973                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
3974                         release_stripe(sh);
3975                         raid_bio->bi_hw_segments = scnt;
3976                         conf->retry_read_aligned = raid_bio;
3977                         return handled;
3978                 }
3979
3980                 handle_stripe(sh, NULL);
3981                 release_stripe(sh);
3982                 handled++;
3983         }
3984         spin_lock_irq(&conf->device_lock);
3985         remaining = --raid_bio->bi_phys_segments;
3986         spin_unlock_irq(&conf->device_lock);
3987         if (remaining == 0) {
3988
3989                 raid_bio->bi_end_io(raid_bio,
3990                               test_bit(BIO_UPTODATE, &raid_bio->bi_flags)
3991                                 ? 0 : -EIO);
3992         }
3993         if (atomic_dec_and_test(&conf->active_aligned_reads))
3994                 wake_up(&conf->wait_for_stripe);
3995         return handled;
3996 }
3997
3998
3999
4000 /*
4001  * This is our raid5 kernel thread.
4002  *
4003  * We scan the hash table for stripes which can be handled now.
4004  * During the scan, completed stripes are saved for us by the interrupt
4005  * handler, so that they will not have to wait for our next wakeup.
4006  */
4007 static void raid5d(mddev_t *mddev)
4008 {
4009         struct stripe_head *sh;
4010         raid5_conf_t *conf = mddev_to_conf(mddev);
4011         int handled;
4012
4013         pr_debug("+++ raid5d active\n");
4014
4015         md_check_recovery(mddev);
4016
4017         handled = 0;
4018         spin_lock_irq(&conf->device_lock);
4019         while (1) {
4020                 struct bio *bio;
4021
4022                 if (conf->seq_flush != conf->seq_write) {
4023                         int seq = conf->seq_flush;
4024                         spin_unlock_irq(&conf->device_lock);
4025                         bitmap_unplug(mddev->bitmap);
4026                         spin_lock_irq(&conf->device_lock);
4027                         conf->seq_write = seq;
4028                         activate_bit_delay(conf);
4029                 }
4030
4031                 while ((bio = remove_bio_from_retry(conf))) {
4032                         int ok;
4033                         spin_unlock_irq(&conf->device_lock);
4034                         ok = retry_aligned_read(conf, bio);
4035                         spin_lock_irq(&conf->device_lock);
4036                         if (!ok)
4037                                 break;
4038                         handled++;
4039                 }
4040
4041                 sh = __get_priority_stripe(conf);
4042
4043                 if (!sh) {
4044                         async_tx_issue_pending_all();
4045                         break;
4046                 }
4047                 spin_unlock_irq(&conf->device_lock);
4048                 
4049                 handled++;
4050                 handle_stripe(sh, conf->spare_page);
4051                 release_stripe(sh);
4052
4053                 spin_lock_irq(&conf->device_lock);
4054         }
4055         pr_debug("%d stripes handled\n", handled);
4056
4057         spin_unlock_irq(&conf->device_lock);
4058
4059         unplug_slaves(mddev);
4060
4061         pr_debug("--- raid5d inactive\n");
4062 }
4063
4064 static ssize_t
4065 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
4066 {
4067         raid5_conf_t *conf = mddev_to_conf(mddev);
4068         if (conf)
4069                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4070         else
4071                 return 0;
4072 }
4073
4074 static ssize_t
4075 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
4076 {
4077         raid5_conf_t *conf = mddev_to_conf(mddev);
4078         unsigned long new;
4079         if (len >= PAGE_SIZE)
4080                 return -EINVAL;
4081         if (!conf)
4082                 return -ENODEV;
4083
4084         if (strict_strtoul(page, 10, &new))
4085                 return -EINVAL;
4086         if (new <= 16 || new > 32768)
4087                 return -EINVAL;
4088         while (new < conf->max_nr_stripes) {
4089                 if (drop_one_stripe(conf))
4090                         conf->max_nr_stripes--;
4091                 else
4092                         break;
4093         }
4094         md_allow_write(mddev);
4095         while (new > conf->max_nr_stripes) {
4096                 if (grow_one_stripe(conf))
4097                         conf->max_nr_stripes++;
4098                 else break;
4099         }
4100         return len;
4101 }
4102
4103 static struct md_sysfs_entry
4104 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4105                                 raid5_show_stripe_cache_size,
4106                                 raid5_store_stripe_cache_size);
4107
4108 static ssize_t
4109 raid5_show_preread_threshold(mddev_t *mddev, char *page)
4110 {
4111         raid5_conf_t *conf = mddev_to_conf(mddev);
4112         if (conf)
4113                 return sprintf(page, "%d\n", conf->bypass_threshold);
4114         else
4115                 return 0;
4116 }
4117
4118 static ssize_t
4119 raid5_store_preread_threshold(mddev_t *mddev, const char *page, size_t len)
4120 {
4121         raid5_conf_t *conf = mddev_to_conf(mddev);
4122         unsigned long new;
4123         if (len >= PAGE_SIZE)
4124                 return -EINVAL;
4125         if (!conf)
4126                 return -ENODEV;
4127
4128         if (strict_strtoul(page, 10, &new))
4129                 return -EINVAL;
4130         if (new > conf->max_nr_stripes)
4131                 return -EINVAL;
4132         conf->bypass_threshold = new;
4133         return len;
4134 }
4135
4136 static struct md_sysfs_entry
4137 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4138                                         S_IRUGO | S_IWUSR,
4139                                         raid5_show_preread_threshold,
4140                                         raid5_store_preread_threshold);
4141
4142 static ssize_t
4143 stripe_cache_active_show(mddev_t *mddev, char *page)
4144 {
4145         raid5_conf_t *conf = mddev_to_conf(mddev);
4146         if (conf)
4147                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4148         else
4149                 return 0;
4150 }
4151
4152 static struct md_sysfs_entry
4153 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4154
4155 static struct attribute *raid5_attrs[] =  {
4156         &raid5_stripecache_size.attr,
4157         &raid5_stripecache_active.attr,
4158         &raid5_preread_bypass_threshold.attr,
4159         NULL,
4160 };
4161 static struct attribute_group raid5_attrs_group = {
4162         .name = NULL,
4163         .attrs = raid5_attrs,
4164 };
4165
4166 static int run(mddev_t *mddev)
4167 {
4168         raid5_conf_t *conf;
4169         int raid_disk, memory;
4170         mdk_rdev_t *rdev;
4171         struct disk_info *disk;
4172         struct list_head *tmp;
4173         int working_disks = 0;
4174
4175         if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
4176                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
4177                        mdname(mddev), mddev->level);
4178                 return -EIO;
4179         }
4180
4181         if (mddev->reshape_position != MaxSector) {
4182                 /* Check that we can continue the reshape.
4183                  * Currently only disks can change, it must
4184                  * increase, and we must be past the point where
4185                  * a stripe over-writes itself
4186                  */
4187                 sector_t here_new, here_old;
4188                 int old_disks;
4189                 int max_degraded = (mddev->level == 5 ? 1 : 2);
4190
4191                 if (mddev->new_level != mddev->level ||
4192                     mddev->new_layout != mddev->layout ||
4193                     mddev->new_chunk != mddev->chunk_size) {
4194                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4195                                "required - aborting.\n",
4196                                mdname(mddev));
4197                         return -EINVAL;
4198                 }
4199                 if (mddev->delta_disks <= 0) {
4200                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4201                                "(reduce disks) required - aborting.\n",
4202                                mdname(mddev));
4203                         return -EINVAL;
4204                 }
4205                 old_disks = mddev->raid_disks - mddev->delta_disks;
4206                 /* reshape_position must be on a new-stripe boundary, and one
4207                  * further up in new geometry must map after here in old
4208                  * geometry.
4209                  */
4210                 here_new = mddev->reshape_position;
4211                 if (sector_div(here_new, (mddev->chunk_size>>9)*
4212                                (mddev->raid_disks - max_degraded))) {
4213                         printk(KERN_ERR "raid5: reshape_position not "
4214                                "on a stripe boundary\n");
4215                         return -EINVAL;
4216                 }
4217                 /* here_new is the stripe we will write to */
4218                 here_old = mddev->reshape_position;
4219                 sector_div(here_old, (mddev->chunk_size>>9)*
4220                            (old_disks-max_degraded));
4221                 /* here_old is the first stripe that we might need to read
4222                  * from */
4223                 if (here_new >= here_old) {
4224                         /* Reading from the same stripe as writing to - bad */
4225                         printk(KERN_ERR "raid5: reshape_position too early for "
4226                                "auto-recovery - aborting.\n");
4227                         return -EINVAL;
4228                 }
4229                 printk(KERN_INFO "raid5: reshape will continue\n");
4230                 /* OK, we should be able to continue; */
4231         }
4232
4233
4234         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
4235         if ((conf = mddev->private) == NULL)
4236                 goto abort;
4237         if (mddev->reshape_position == MaxSector) {
4238                 conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
4239         } else {
4240                 conf->raid_disks = mddev->raid_disks;
4241                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4242         }
4243
4244         conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
4245                               GFP_KERNEL);
4246         if (!conf->disks)
4247                 goto abort;
4248
4249         conf->mddev = mddev;
4250
4251         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4252                 goto abort;
4253
4254         if (mddev->level == 6) {
4255                 conf->spare_page = alloc_page(GFP_KERNEL);
4256                 if (!conf->spare_page)
4257                         goto abort;
4258         }
4259         spin_lock_init(&conf->device_lock);
4260         init_waitqueue_head(&conf->wait_for_stripe);
4261         init_waitqueue_head(&conf->wait_for_overlap);
4262         INIT_LIST_HEAD(&conf->handle_list);
4263         INIT_LIST_HEAD(&conf->hold_list);
4264         INIT_LIST_HEAD(&conf->delayed_list);
4265         INIT_LIST_HEAD(&conf->bitmap_list);
4266         INIT_LIST_HEAD(&conf->inactive_list);
4267         atomic_set(&conf->active_stripes, 0);
4268         atomic_set(&conf->preread_active_stripes, 0);
4269         atomic_set(&conf->active_aligned_reads, 0);
4270         conf->bypass_threshold = BYPASS_THRESHOLD;
4271
4272         pr_debug("raid5: run(%s) called.\n", mdname(mddev));
4273
4274         rdev_for_each(rdev, tmp, mddev) {
4275                 raid_disk = rdev->raid_disk;
4276                 if (raid_disk >= conf->raid_disks
4277                     || raid_disk < 0)
4278                         continue;
4279                 disk = conf->disks + raid_disk;
4280
4281                 disk->rdev = rdev;
4282
4283                 if (test_bit(In_sync, &rdev->flags)) {
4284                         char b[BDEVNAME_SIZE];
4285                         printk(KERN_INFO "raid5: device %s operational as raid"
4286                                 " disk %d\n", bdevname(rdev->bdev,b),
4287                                 raid_disk);
4288                         working_disks++;
4289                 }
4290         }
4291
4292         /*
4293          * 0 for a fully functional array, 1 or 2 for a degraded array.
4294          */
4295         mddev->degraded = conf->raid_disks - working_disks;
4296         conf->mddev = mddev;
4297         conf->chunk_size = mddev->chunk_size;
4298         conf->level = mddev->level;
4299         if (conf->level == 6)
4300                 conf->max_degraded = 2;
4301         else
4302                 conf->max_degraded = 1;
4303         conf->algorithm = mddev->layout;
4304         conf->max_nr_stripes = NR_STRIPES;
4305         conf->expand_progress = mddev->reshape_position;
4306
4307         /* device size must be a multiple of chunk size */
4308         mddev->size &= ~(mddev->chunk_size/1024 -1);
4309         mddev->resync_max_sectors = mddev->size << 1;
4310
4311         if (conf->level == 6 && conf->raid_disks < 4) {
4312                 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
4313                        mdname(mddev), conf->raid_disks);
4314                 goto abort;
4315         }
4316         if (!conf->chunk_size || conf->chunk_size % 4) {
4317                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
4318                         conf->chunk_size, mdname(mddev));
4319                 goto abort;
4320         }
4321         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
4322                 printk(KERN_ERR 
4323                         "raid5: unsupported parity algorithm %d for %s\n",
4324                         conf->algorithm, mdname(mddev));
4325                 goto abort;
4326         }
4327         if (mddev->degraded > conf->max_degraded) {
4328                 printk(KERN_ERR "raid5: not enough operational devices for %s"
4329                         " (%d/%d failed)\n",
4330                         mdname(mddev), mddev->degraded, conf->raid_disks);
4331                 goto abort;
4332         }
4333
4334         if (mddev->degraded > 0 &&
4335             mddev->recovery_cp != MaxSector) {
4336                 if (mddev->ok_start_degraded)
4337                         printk(KERN_WARNING
4338                                "raid5: starting dirty degraded array: %s"
4339                                "- data corruption possible.\n",
4340                                mdname(mddev));
4341                 else {
4342                         printk(KERN_ERR
4343                                "raid5: cannot start dirty degraded array for %s\n",
4344                                mdname(mddev));
4345                         goto abort;
4346                 }
4347         }
4348
4349         {
4350                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
4351                 if (!mddev->thread) {
4352                         printk(KERN_ERR 
4353                                 "raid5: couldn't allocate thread for %s\n",
4354                                 mdname(mddev));
4355                         goto abort;
4356                 }
4357         }
4358         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4359                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4360         if (grow_stripes(conf, conf->max_nr_stripes)) {
4361                 printk(KERN_ERR 
4362                         "raid5: couldn't allocate %dkB for buffers\n", memory);
4363                 shrink_stripes(conf);
4364                 md_unregister_thread(mddev->thread);
4365                 goto abort;
4366         } else
4367                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
4368                         memory, mdname(mddev));
4369
4370         if (mddev->degraded == 0)
4371                 printk("raid5: raid level %d set %s active with %d out of %d"
4372                         " devices, algorithm %d\n", conf->level, mdname(mddev), 
4373                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
4374                         conf->algorithm);
4375         else
4376                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
4377                         " out of %d devices, algorithm %d\n", conf->level,
4378                         mdname(mddev), mddev->raid_disks - mddev->degraded,
4379                         mddev->raid_disks, conf->algorithm);
4380
4381         print_raid5_conf(conf);
4382
4383         if (conf->expand_progress != MaxSector) {
4384                 printk("...ok start reshape thread\n");
4385                 conf->expand_lo = conf->expand_progress;
4386                 atomic_set(&conf->reshape_stripes, 0);
4387                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4388                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4389                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4390                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4391                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4392                                                         "%s_reshape");
4393         }
4394
4395         /* read-ahead size must cover two whole stripes, which is
4396          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4397          */
4398         {
4399                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
4400                 int stripe = data_disks *
4401                         (mddev->chunk_size / PAGE_SIZE);
4402                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4403                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4404         }
4405
4406         /* Ok, everything is just fine now */
4407         if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
4408                 printk(KERN_WARNING
4409                        "raid5: failed to create sysfs attributes for %s\n",
4410                        mdname(mddev));
4411
4412         mddev->queue->unplug_fn = raid5_unplug_device;
4413         mddev->queue->backing_dev_info.congested_data = mddev;
4414         mddev->queue->backing_dev_info.congested_fn = raid5_congested;
4415
4416         mddev->array_size =  mddev->size * (conf->previous_raid_disks -
4417                                             conf->max_degraded);
4418
4419         blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
4420
4421         return 0;
4422 abort:
4423         if (conf) {
4424                 print_raid5_conf(conf);
4425                 safe_put_page(conf->spare_page);
4426                 kfree(conf->disks);
4427                 kfree(conf->stripe_hashtbl);
4428                 kfree(conf);
4429         }
4430         mddev->private = NULL;
4431         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
4432         return -EIO;
4433 }
4434
4435
4436
4437 static int stop(mddev_t *mddev)
4438 {
4439         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4440
4441         md_unregister_thread(mddev->thread);
4442         mddev->thread = NULL;
4443         shrink_stripes(conf);
4444         kfree(conf->stripe_hashtbl);
4445         mddev->queue->backing_dev_info.congested_fn = NULL;
4446         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
4447         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
4448         kfree(conf->disks);
4449         kfree(conf);
4450         mddev->private = NULL;
4451         return 0;
4452 }
4453
4454 #ifdef DEBUG
4455 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
4456 {
4457         int i;
4458
4459         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
4460                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
4461         seq_printf(seq, "sh %llu,  count %d.\n",
4462                    (unsigned long long)sh->sector, atomic_read(&sh->count));
4463         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
4464         for (i = 0; i < sh->disks; i++) {
4465                 seq_printf(seq, "(cache%d: %p %ld) ",
4466                            i, sh->dev[i].page, sh->dev[i].flags);
4467         }
4468         seq_printf(seq, "\n");
4469 }
4470
4471 static void printall (struct seq_file *seq, raid5_conf_t *conf)
4472 {
4473         struct stripe_head *sh;
4474         struct hlist_node *hn;
4475         int i;
4476
4477         spin_lock_irq(&conf->device_lock);
4478         for (i = 0; i < NR_HASH; i++) {
4479                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
4480                         if (sh->raid_conf != conf)
4481                                 continue;
4482                         print_sh(seq, sh);
4483                 }
4484         }
4485         spin_unlock_irq(&conf->device_lock);
4486 }
4487 #endif
4488
4489 static void status (struct seq_file *seq, mddev_t *mddev)
4490 {
4491         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4492         int i;
4493
4494         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
4495         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
4496         for (i = 0; i < conf->raid_disks; i++)
4497                 seq_printf (seq, "%s",
4498                                conf->disks[i].rdev &&
4499                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
4500         seq_printf (seq, "]");
4501 #ifdef DEBUG
4502         seq_printf (seq, "\n");
4503         printall(seq, conf);
4504 #endif
4505 }
4506
4507 static void print_raid5_conf (raid5_conf_t *conf)
4508 {
4509         int i;
4510         struct disk_info *tmp;
4511
4512         printk("RAID5 conf printout:\n");
4513         if (!conf) {
4514                 printk("(conf==NULL)\n");
4515                 return;
4516         }
4517         printk(" --- rd:%d wd:%d\n", conf->raid_disks,
4518                  conf->raid_disks - conf->mddev->degraded);
4519
4520         for (i = 0; i < conf->raid_disks; i++) {
4521                 char b[BDEVNAME_SIZE];
4522                 tmp = conf->disks + i;
4523                 if (tmp->rdev)
4524                 printk(" disk %d, o:%d, dev:%s\n",
4525                         i, !test_bit(Faulty, &tmp->rdev->flags),
4526                         bdevname(tmp->rdev->bdev,b));
4527         }
4528 }
4529
4530 static int raid5_spare_active(mddev_t *mddev)
4531 {
4532         int i;
4533         raid5_conf_t *conf = mddev->private;
4534         struct disk_info *tmp;
4535
4536         for (i = 0; i < conf->raid_disks; i++) {
4537                 tmp = conf->disks + i;
4538                 if (tmp->rdev
4539                     && !test_bit(Faulty, &tmp->rdev->flags)
4540                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
4541                         unsigned long flags;
4542                         spin_lock_irqsave(&conf->device_lock, flags);
4543                         mddev->degraded--;
4544                         spin_unlock_irqrestore(&conf->device_lock, flags);
4545                 }
4546         }
4547         print_raid5_conf(conf);
4548         return 0;
4549 }
4550
4551 static int raid5_remove_disk(mddev_t *mddev, int number)
4552 {
4553         raid5_conf_t *conf = mddev->private;
4554         int err = 0;
4555         mdk_rdev_t *rdev;
4556         struct disk_info *p = conf->disks + number;
4557
4558         print_raid5_conf(conf);
4559         rdev = p->rdev;
4560         if (rdev) {
4561                 if (test_bit(In_sync, &rdev->flags) ||
4562                     atomic_read(&rdev->nr_pending)) {
4563                         err = -EBUSY;
4564                         goto abort;
4565                 }
4566                 p->rdev = NULL;
4567                 synchronize_rcu();
4568                 if (atomic_read(&rdev->nr_pending)) {
4569                         /* lost the race, try later */
4570                         err = -EBUSY;
4571                         p->rdev = rdev;
4572                 }
4573         }
4574 abort:
4575
4576         print_raid5_conf(conf);
4577         return err;
4578 }
4579
4580 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
4581 {
4582         raid5_conf_t *conf = mddev->private;
4583         int found = 0;
4584         int disk;
4585         struct disk_info *p;
4586
4587         if (mddev->degraded > conf->max_degraded)
4588                 /* no point adding a device */
4589                 return 0;
4590
4591         /*
4592          * find the disk ... but prefer rdev->saved_raid_disk
4593          * if possible.
4594          */
4595         if (rdev->saved_raid_disk >= 0 &&
4596             conf->disks[rdev->saved_raid_disk].rdev == NULL)
4597                 disk = rdev->saved_raid_disk;
4598         else
4599                 disk = 0;
4600         for ( ; disk < conf->raid_disks; disk++)
4601                 if ((p=conf->disks + disk)->rdev == NULL) {
4602                         clear_bit(In_sync, &rdev->flags);
4603                         rdev->raid_disk = disk;
4604                         found = 1;
4605                         if (rdev->saved_raid_disk != disk)
4606                                 conf->fullsync = 1;
4607                         rcu_assign_pointer(p->rdev, rdev);
4608                         break;
4609                 }
4610         print_raid5_conf(conf);
4611         return found;
4612 }
4613
4614 static int raid5_resize(mddev_t *mddev, sector_t sectors)
4615 {
4616         /* no resync is happening, and there is enough space
4617          * on all devices, so we can resize.
4618          * We need to make sure resync covers any new space.
4619          * If the array is shrinking we should possibly wait until
4620          * any io in the removed space completes, but it hardly seems
4621          * worth it.
4622          */
4623         raid5_conf_t *conf = mddev_to_conf(mddev);
4624
4625         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
4626         mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
4627         set_capacity(mddev->gendisk, mddev->array_size << 1);
4628         mddev->changed = 1;
4629         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
4630                 mddev->recovery_cp = mddev->size << 1;
4631                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4632         }
4633         mddev->size = sectors /2;
4634         mddev->resync_max_sectors = sectors;
4635         return 0;
4636 }
4637
4638 #ifdef CONFIG_MD_RAID5_RESHAPE
4639 static int raid5_check_reshape(mddev_t *mddev)
4640 {
4641         raid5_conf_t *conf = mddev_to_conf(mddev);
4642         int err;
4643
4644         if (mddev->delta_disks < 0 ||
4645             mddev->new_level != mddev->level)
4646                 return -EINVAL; /* Cannot shrink array or change level yet */
4647         if (mddev->delta_disks == 0)
4648                 return 0; /* nothing to do */
4649
4650         /* Can only proceed if there are plenty of stripe_heads.
4651          * We need a minimum of one full stripe,, and for sensible progress
4652          * it is best to have about 4 times that.
4653          * If we require 4 times, then the default 256 4K stripe_heads will
4654          * allow for chunk sizes up to 256K, which is probably OK.
4655          * If the chunk size is greater, user-space should request more
4656          * stripe_heads first.
4657          */
4658         if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
4659             (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
4660                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
4661                        (mddev->chunk_size / STRIPE_SIZE)*4);
4662                 return -ENOSPC;
4663         }
4664
4665         err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
4666         if (err)
4667                 return err;
4668
4669         if (mddev->degraded > conf->max_degraded)
4670                 return -EINVAL;
4671         /* looks like we might be able to manage this */
4672         return 0;
4673 }
4674
4675 static int raid5_start_reshape(mddev_t *mddev)
4676 {
4677         raid5_conf_t *conf = mddev_to_conf(mddev);
4678         mdk_rdev_t *rdev;
4679         struct list_head *rtmp;
4680         int spares = 0;
4681         int added_devices = 0;
4682         unsigned long flags;
4683
4684         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4685                 return -EBUSY;
4686
4687         rdev_for_each(rdev, rtmp, mddev)
4688                 if (rdev->raid_disk < 0 &&
4689                     !test_bit(Faulty, &rdev->flags))
4690                         spares++;
4691
4692         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
4693                 /* Not enough devices even to make a degraded array
4694                  * of that size
4695                  */
4696                 return -EINVAL;
4697
4698         atomic_set(&conf->reshape_stripes, 0);
4699         spin_lock_irq(&conf->device_lock);
4700         conf->previous_raid_disks = conf->raid_disks;
4701         conf->raid_disks += mddev->delta_disks;
4702         conf->expand_progress = 0;
4703         conf->expand_lo = 0;
4704         spin_unlock_irq(&conf->device_lock);
4705
4706         /* Add some new drives, as many as will fit.
4707          * We know there are enough to make the newly sized array work.
4708          */
4709         rdev_for_each(rdev, rtmp, mddev)
4710                 if (rdev->raid_disk < 0 &&
4711                     !test_bit(Faulty, &rdev->flags)) {
4712                         if (raid5_add_disk(mddev, rdev)) {
4713                                 char nm[20];
4714                                 set_bit(In_sync, &rdev->flags);
4715                                 added_devices++;
4716                                 rdev->recovery_offset = 0;
4717                                 sprintf(nm, "rd%d", rdev->raid_disk);
4718                                 if (sysfs_create_link(&mddev->kobj,
4719                                                       &rdev->kobj, nm))
4720                                         printk(KERN_WARNING
4721                                                "raid5: failed to create "
4722                                                " link %s for %s\n",
4723                                                nm, mdname(mddev));
4724                         } else
4725                                 break;
4726                 }
4727
4728         spin_lock_irqsave(&conf->device_lock, flags);
4729         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
4730         spin_unlock_irqrestore(&conf->device_lock, flags);
4731         mddev->raid_disks = conf->raid_disks;
4732         mddev->reshape_position = 0;
4733         set_bit(MD_CHANGE_DEVS, &mddev->flags);
4734
4735         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4736         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4737         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4738         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4739         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4740                                                 "%s_reshape");
4741         if (!mddev->sync_thread) {
4742                 mddev->recovery = 0;
4743                 spin_lock_irq(&conf->device_lock);
4744                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
4745                 conf->expand_progress = MaxSector;
4746                 spin_unlock_irq(&conf->device_lock);
4747                 return -EAGAIN;
4748         }
4749         md_wakeup_thread(mddev->sync_thread);
4750         md_new_event(mddev);
4751         return 0;
4752 }
4753 #endif
4754
4755 static void end_reshape(raid5_conf_t *conf)
4756 {
4757         struct block_device *bdev;
4758
4759         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
4760                 conf->mddev->array_size = conf->mddev->size *
4761                         (conf->raid_disks - conf->max_degraded);
4762                 set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
4763                 conf->mddev->changed = 1;
4764
4765                 bdev = bdget_disk(conf->mddev->gendisk, 0);
4766                 if (bdev) {
4767                         mutex_lock(&bdev->bd_inode->i_mutex);
4768                         i_size_write(bdev->bd_inode, (loff_t)conf->mddev->array_size << 10);
4769                         mutex_unlock(&bdev->bd_inode->i_mutex);
4770                         bdput(bdev);
4771                 }
4772                 spin_lock_irq(&conf->device_lock);
4773                 conf->expand_progress = MaxSector;
4774                 spin_unlock_irq(&conf->device_lock);
4775                 conf->mddev->reshape_position = MaxSector;
4776
4777                 /* read-ahead size must cover two whole stripes, which is
4778                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4779                  */
4780                 {
4781                         int data_disks = conf->previous_raid_disks - conf->max_degraded;
4782                         int stripe = data_disks *
4783                                 (conf->mddev->chunk_size / PAGE_SIZE);
4784                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4785                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4786                 }
4787         }
4788 }
4789
4790 static void raid5_quiesce(mddev_t *mddev, int state)
4791 {
4792         raid5_conf_t *conf = mddev_to_conf(mddev);
4793
4794         switch(state) {
4795         case 2: /* resume for a suspend */
4796                 wake_up(&conf->wait_for_overlap);
4797                 break;
4798
4799         case 1: /* stop all writes */
4800                 spin_lock_irq(&conf->device_lock);
4801                 conf->quiesce = 1;
4802                 wait_event_lock_irq(conf->wait_for_stripe,
4803                                     atomic_read(&conf->active_stripes) == 0 &&
4804                                     atomic_read(&conf->active_aligned_reads) == 0,
4805                                     conf->device_lock, /* nothing */);
4806                 spin_unlock_irq(&conf->device_lock);
4807                 break;
4808
4809         case 0: /* re-enable writes */
4810                 spin_lock_irq(&conf->device_lock);
4811                 conf->quiesce = 0;
4812                 wake_up(&conf->wait_for_stripe);
4813                 wake_up(&conf->wait_for_overlap);
4814                 spin_unlock_irq(&conf->device_lock);
4815                 break;
4816         }
4817 }
4818
4819 static struct mdk_personality raid6_personality =
4820 {
4821         .name           = "raid6",
4822         .level          = 6,
4823         .owner          = THIS_MODULE,
4824         .make_request   = make_request,
4825         .run            = run,
4826         .stop           = stop,
4827         .status         = status,
4828         .error_handler  = error,
4829         .hot_add_disk   = raid5_add_disk,
4830         .hot_remove_disk= raid5_remove_disk,
4831         .spare_active   = raid5_spare_active,
4832         .sync_request   = sync_request,
4833         .resize         = raid5_resize,
4834 #ifdef CONFIG_MD_RAID5_RESHAPE
4835         .check_reshape  = raid5_check_reshape,
4836         .start_reshape  = raid5_start_reshape,
4837 #endif
4838         .quiesce        = raid5_quiesce,
4839 };
4840 static struct mdk_personality raid5_personality =
4841 {
4842         .name           = "raid5",
4843         .level          = 5,
4844         .owner          = THIS_MODULE,
4845         .make_request   = make_request,
4846         .run            = run,
4847         .stop           = stop,
4848         .status         = status,
4849         .error_handler  = error,
4850         .hot_add_disk   = raid5_add_disk,
4851         .hot_remove_disk= raid5_remove_disk,
4852         .spare_active   = raid5_spare_active,
4853         .sync_request   = sync_request,
4854         .resize         = raid5_resize,
4855 #ifdef CONFIG_MD_RAID5_RESHAPE
4856         .check_reshape  = raid5_check_reshape,
4857         .start_reshape  = raid5_start_reshape,
4858 #endif
4859         .quiesce        = raid5_quiesce,
4860 };
4861
4862 static struct mdk_personality raid4_personality =
4863 {
4864         .name           = "raid4",
4865         .level          = 4,
4866         .owner          = THIS_MODULE,
4867         .make_request   = make_request,
4868         .run            = run,
4869         .stop           = stop,
4870         .status         = status,
4871         .error_handler  = error,
4872         .hot_add_disk   = raid5_add_disk,
4873         .hot_remove_disk= raid5_remove_disk,
4874         .spare_active   = raid5_spare_active,
4875         .sync_request   = sync_request,
4876         .resize         = raid5_resize,
4877 #ifdef CONFIG_MD_RAID5_RESHAPE
4878         .check_reshape  = raid5_check_reshape,
4879         .start_reshape  = raid5_start_reshape,
4880 #endif
4881         .quiesce        = raid5_quiesce,
4882 };
4883
4884 static int __init raid5_init(void)
4885 {
4886         int e;
4887
4888         e = raid6_select_algo();
4889         if ( e )
4890                 return e;
4891         register_md_personality(&raid6_personality);
4892         register_md_personality(&raid5_personality);
4893         register_md_personality(&raid4_personality);
4894         return 0;
4895 }
4896
4897 static void raid5_exit(void)
4898 {
4899         unregister_md_personality(&raid6_personality);
4900         unregister_md_personality(&raid5_personality);
4901         unregister_md_personality(&raid4_personality);
4902 }
4903
4904 module_init(raid5_init);
4905 module_exit(raid5_exit);
4906 MODULE_LICENSE("GPL");
4907 MODULE_ALIAS("md-personality-4"); /* RAID5 */
4908 MODULE_ALIAS("md-raid5");
4909 MODULE_ALIAS("md-raid4");
4910 MODULE_ALIAS("md-level-5");
4911 MODULE_ALIAS("md-level-4");
4912 MODULE_ALIAS("md-personality-8"); /* RAID6 */
4913 MODULE_ALIAS("md-raid6");
4914 MODULE_ALIAS("md-level-6");
4915
4916 /* This used to be two separate modules, they were: */
4917 MODULE_ALIAS("raid5");
4918 MODULE_ALIAS("raid6");