Merge tag 'for-f2fs-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk...
[platform/kernel/linux-stable.git] / drivers / md / raid1.c
1 /*
2  * raid1.c : Multiple Devices driver for Linux
3  *
4  * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
5  *
6  * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
7  *
8  * RAID-1 management functions.
9  *
10  * Better read-balancing code written by Mika Kuoppala <miku@iki.fi>, 2000
11  *
12  * Fixes to reconstruction by Jakob Ã˜stergaard" <jakob@ostenfeld.dk>
13  * Various fixes by Neil Brown <neilb@cse.unsw.edu.au>
14  *
15  * Changes by Peter T. Breuer <ptb@it.uc3m.es> 31/1/2003 to support
16  * bitmapped intelligence in resync:
17  *
18  *      - bitmap marked during normal i/o
19  *      - bitmap used to skip nondirty blocks during sync
20  *
21  * Additions to bitmap code, (C) 2003-2004 Paul Clements, SteelEye Technology:
22  * - persistent bitmap code
23  *
24  * This program is free software; you can redistribute it and/or modify
25  * it under the terms of the GNU General Public License as published by
26  * the Free Software Foundation; either version 2, or (at your option)
27  * any later version.
28  *
29  * You should have received a copy of the GNU General Public License
30  * (for example /usr/src/linux/COPYING); if not, write to the Free
31  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
32  */
33
34 #include <linux/slab.h>
35 #include <linux/delay.h>
36 #include <linux/blkdev.h>
37 #include <linux/module.h>
38 #include <linux/seq_file.h>
39 #include <linux/ratelimit.h>
40 #include "md.h"
41 #include "raid1.h"
42 #include "bitmap.h"
43
44 /*
45  * Number of guaranteed r1bios in case of extreme VM load:
46  */
47 #define NR_RAID1_BIOS 256
48
49 /* when we get a read error on a read-only array, we redirect to another
50  * device without failing the first device, or trying to over-write to
51  * correct the read error.  To keep track of bad blocks on a per-bio
52  * level, we store IO_BLOCKED in the appropriate 'bios' pointer
53  */
54 #define IO_BLOCKED ((struct bio *)1)
55 /* When we successfully write to a known bad-block, we need to remove the
56  * bad-block marking which must be done from process context.  So we record
57  * the success by setting devs[n].bio to IO_MADE_GOOD
58  */
59 #define IO_MADE_GOOD ((struct bio *)2)
60
61 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
62
63 /* When there are this many requests queue to be written by
64  * the raid1 thread, we become 'congested' to provide back-pressure
65  * for writeback.
66  */
67 static int max_queued_requests = 1024;
68
69 static void allow_barrier(struct r1conf *conf, sector_t start_next_window,
70                           sector_t bi_sector);
71 static void lower_barrier(struct r1conf *conf);
72
73 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
74 {
75         struct pool_info *pi = data;
76         int size = offsetof(struct r1bio, bios[pi->raid_disks]);
77
78         /* allocate a r1bio with room for raid_disks entries in the bios array */
79         return kzalloc(size, gfp_flags);
80 }
81
82 static void r1bio_pool_free(void *r1_bio, void *data)
83 {
84         kfree(r1_bio);
85 }
86
87 #define RESYNC_BLOCK_SIZE (64*1024)
88 #define RESYNC_DEPTH 32
89 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
90 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
91 #define RESYNC_WINDOW (RESYNC_BLOCK_SIZE * RESYNC_DEPTH)
92 #define RESYNC_WINDOW_SECTORS (RESYNC_WINDOW >> 9)
93 #define NEXT_NORMALIO_DISTANCE (3 * RESYNC_WINDOW_SECTORS)
94
95 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
96 {
97         struct pool_info *pi = data;
98         struct r1bio *r1_bio;
99         struct bio *bio;
100         int i, j;
101
102         r1_bio = r1bio_pool_alloc(gfp_flags, pi);
103         if (!r1_bio)
104                 return NULL;
105
106         /*
107          * Allocate bios : 1 for reading, n-1 for writing
108          */
109         for (j = pi->raid_disks ; j-- ; ) {
110                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
111                 if (!bio)
112                         goto out_free_bio;
113                 r1_bio->bios[j] = bio;
114         }
115         /*
116          * Allocate RESYNC_PAGES data pages and attach them to
117          * the first bio.
118          * If this is a user-requested check/repair, allocate
119          * RESYNC_PAGES for each bio.
120          */
121         if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
122                 j = pi->raid_disks;
123         else
124                 j = 1;
125         while(j--) {
126                 bio = r1_bio->bios[j];
127                 bio->bi_vcnt = RESYNC_PAGES;
128
129                 if (bio_alloc_pages(bio, gfp_flags))
130                         goto out_free_bio;
131         }
132         /* If not user-requests, copy the page pointers to all bios */
133         if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
134                 for (i=0; i<RESYNC_PAGES ; i++)
135                         for (j=1; j<pi->raid_disks; j++)
136                                 r1_bio->bios[j]->bi_io_vec[i].bv_page =
137                                         r1_bio->bios[0]->bi_io_vec[i].bv_page;
138         }
139
140         r1_bio->master_bio = NULL;
141
142         return r1_bio;
143
144 out_free_bio:
145         while (++j < pi->raid_disks)
146                 bio_put(r1_bio->bios[j]);
147         r1bio_pool_free(r1_bio, data);
148         return NULL;
149 }
150
151 static void r1buf_pool_free(void *__r1_bio, void *data)
152 {
153         struct pool_info *pi = data;
154         int i,j;
155         struct r1bio *r1bio = __r1_bio;
156
157         for (i = 0; i < RESYNC_PAGES; i++)
158                 for (j = pi->raid_disks; j-- ;) {
159                         if (j == 0 ||
160                             r1bio->bios[j]->bi_io_vec[i].bv_page !=
161                             r1bio->bios[0]->bi_io_vec[i].bv_page)
162                                 safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
163                 }
164         for (i=0 ; i < pi->raid_disks; i++)
165                 bio_put(r1bio->bios[i]);
166
167         r1bio_pool_free(r1bio, data);
168 }
169
170 static void put_all_bios(struct r1conf *conf, struct r1bio *r1_bio)
171 {
172         int i;
173
174         for (i = 0; i < conf->raid_disks * 2; i++) {
175                 struct bio **bio = r1_bio->bios + i;
176                 if (!BIO_SPECIAL(*bio))
177                         bio_put(*bio);
178                 *bio = NULL;
179         }
180 }
181
182 static void free_r1bio(struct r1bio *r1_bio)
183 {
184         struct r1conf *conf = r1_bio->mddev->private;
185
186         put_all_bios(conf, r1_bio);
187         mempool_free(r1_bio, conf->r1bio_pool);
188 }
189
190 static void put_buf(struct r1bio *r1_bio)
191 {
192         struct r1conf *conf = r1_bio->mddev->private;
193         int i;
194
195         for (i = 0; i < conf->raid_disks * 2; i++) {
196                 struct bio *bio = r1_bio->bios[i];
197                 if (bio->bi_end_io)
198                         rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
199         }
200
201         mempool_free(r1_bio, conf->r1buf_pool);
202
203         lower_barrier(conf);
204 }
205
206 static void reschedule_retry(struct r1bio *r1_bio)
207 {
208         unsigned long flags;
209         struct mddev *mddev = r1_bio->mddev;
210         struct r1conf *conf = mddev->private;
211
212         spin_lock_irqsave(&conf->device_lock, flags);
213         list_add(&r1_bio->retry_list, &conf->retry_list);
214         conf->nr_queued ++;
215         spin_unlock_irqrestore(&conf->device_lock, flags);
216
217         wake_up(&conf->wait_barrier);
218         md_wakeup_thread(mddev->thread);
219 }
220
221 /*
222  * raid_end_bio_io() is called when we have finished servicing a mirrored
223  * operation and are ready to return a success/failure code to the buffer
224  * cache layer.
225  */
226 static void call_bio_endio(struct r1bio *r1_bio)
227 {
228         struct bio *bio = r1_bio->master_bio;
229         int done;
230         struct r1conf *conf = r1_bio->mddev->private;
231         sector_t start_next_window = r1_bio->start_next_window;
232         sector_t bi_sector = bio->bi_sector;
233
234         if (bio->bi_phys_segments) {
235                 unsigned long flags;
236                 spin_lock_irqsave(&conf->device_lock, flags);
237                 bio->bi_phys_segments--;
238                 done = (bio->bi_phys_segments == 0);
239                 spin_unlock_irqrestore(&conf->device_lock, flags);
240                 /*
241                  * make_request() might be waiting for
242                  * bi_phys_segments to decrease
243                  */
244                 wake_up(&conf->wait_barrier);
245         } else
246                 done = 1;
247
248         if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
249                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
250         if (done) {
251                 bio_endio(bio, 0);
252                 /*
253                  * Wake up any possible resync thread that waits for the device
254                  * to go idle.
255                  */
256                 allow_barrier(conf, start_next_window, bi_sector);
257         }
258 }
259
260 static void raid_end_bio_io(struct r1bio *r1_bio)
261 {
262         struct bio *bio = r1_bio->master_bio;
263
264         /* if nobody has done the final endio yet, do it now */
265         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
266                 pr_debug("raid1: sync end %s on sectors %llu-%llu\n",
267                          (bio_data_dir(bio) == WRITE) ? "write" : "read",
268                          (unsigned long long) bio->bi_sector,
269                          (unsigned long long) bio->bi_sector +
270                          bio_sectors(bio) - 1);
271
272                 call_bio_endio(r1_bio);
273         }
274         free_r1bio(r1_bio);
275 }
276
277 /*
278  * Update disk head position estimator based on IRQ completion info.
279  */
280 static inline void update_head_pos(int disk, struct r1bio *r1_bio)
281 {
282         struct r1conf *conf = r1_bio->mddev->private;
283
284         conf->mirrors[disk].head_position =
285                 r1_bio->sector + (r1_bio->sectors);
286 }
287
288 /*
289  * Find the disk number which triggered given bio
290  */
291 static int find_bio_disk(struct r1bio *r1_bio, struct bio *bio)
292 {
293         int mirror;
294         struct r1conf *conf = r1_bio->mddev->private;
295         int raid_disks = conf->raid_disks;
296
297         for (mirror = 0; mirror < raid_disks * 2; mirror++)
298                 if (r1_bio->bios[mirror] == bio)
299                         break;
300
301         BUG_ON(mirror == raid_disks * 2);
302         update_head_pos(mirror, r1_bio);
303
304         return mirror;
305 }
306
307 static void raid1_end_read_request(struct bio *bio, int error)
308 {
309         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
310         struct r1bio *r1_bio = bio->bi_private;
311         int mirror;
312         struct r1conf *conf = r1_bio->mddev->private;
313
314         mirror = r1_bio->read_disk;
315         /*
316          * this branch is our 'one mirror IO has finished' event handler:
317          */
318         update_head_pos(mirror, r1_bio);
319
320         if (uptodate)
321                 set_bit(R1BIO_Uptodate, &r1_bio->state);
322         else {
323                 /* If all other devices have failed, we want to return
324                  * the error upwards rather than fail the last device.
325                  * Here we redefine "uptodate" to mean "Don't want to retry"
326                  */
327                 unsigned long flags;
328                 spin_lock_irqsave(&conf->device_lock, flags);
329                 if (r1_bio->mddev->degraded == conf->raid_disks ||
330                     (r1_bio->mddev->degraded == conf->raid_disks-1 &&
331                      !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
332                         uptodate = 1;
333                 spin_unlock_irqrestore(&conf->device_lock, flags);
334         }
335
336         if (uptodate) {
337                 raid_end_bio_io(r1_bio);
338                 rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
339         } else {
340                 /*
341                  * oops, read error:
342                  */
343                 char b[BDEVNAME_SIZE];
344                 printk_ratelimited(
345                         KERN_ERR "md/raid1:%s: %s: "
346                         "rescheduling sector %llu\n",
347                         mdname(conf->mddev),
348                         bdevname(conf->mirrors[mirror].rdev->bdev,
349                                  b),
350                         (unsigned long long)r1_bio->sector);
351                 set_bit(R1BIO_ReadError, &r1_bio->state);
352                 reschedule_retry(r1_bio);
353                 /* don't drop the reference on read_disk yet */
354         }
355 }
356
357 static void close_write(struct r1bio *r1_bio)
358 {
359         /* it really is the end of this request */
360         if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
361                 /* free extra copy of the data pages */
362                 int i = r1_bio->behind_page_count;
363                 while (i--)
364                         safe_put_page(r1_bio->behind_bvecs[i].bv_page);
365                 kfree(r1_bio->behind_bvecs);
366                 r1_bio->behind_bvecs = NULL;
367         }
368         /* clear the bitmap if all writes complete successfully */
369         bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
370                         r1_bio->sectors,
371                         !test_bit(R1BIO_Degraded, &r1_bio->state),
372                         test_bit(R1BIO_BehindIO, &r1_bio->state));
373         md_write_end(r1_bio->mddev);
374 }
375
376 static void r1_bio_write_done(struct r1bio *r1_bio)
377 {
378         if (!atomic_dec_and_test(&r1_bio->remaining))
379                 return;
380
381         if (test_bit(R1BIO_WriteError, &r1_bio->state))
382                 reschedule_retry(r1_bio);
383         else {
384                 close_write(r1_bio);
385                 if (test_bit(R1BIO_MadeGood, &r1_bio->state))
386                         reschedule_retry(r1_bio);
387                 else
388                         raid_end_bio_io(r1_bio);
389         }
390 }
391
392 static void raid1_end_write_request(struct bio *bio, int error)
393 {
394         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
395         struct r1bio *r1_bio = bio->bi_private;
396         int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
397         struct r1conf *conf = r1_bio->mddev->private;
398         struct bio *to_put = NULL;
399
400         mirror = find_bio_disk(r1_bio, bio);
401
402         /*
403          * 'one mirror IO has finished' event handler:
404          */
405         if (!uptodate) {
406                 set_bit(WriteErrorSeen,
407                         &conf->mirrors[mirror].rdev->flags);
408                 if (!test_and_set_bit(WantReplacement,
409                                       &conf->mirrors[mirror].rdev->flags))
410                         set_bit(MD_RECOVERY_NEEDED, &
411                                 conf->mddev->recovery);
412
413                 set_bit(R1BIO_WriteError, &r1_bio->state);
414         } else {
415                 /*
416                  * Set R1BIO_Uptodate in our master bio, so that we
417                  * will return a good error code for to the higher
418                  * levels even if IO on some other mirrored buffer
419                  * fails.
420                  *
421                  * The 'master' represents the composite IO operation
422                  * to user-side. So if something waits for IO, then it
423                  * will wait for the 'master' bio.
424                  */
425                 sector_t first_bad;
426                 int bad_sectors;
427
428                 r1_bio->bios[mirror] = NULL;
429                 to_put = bio;
430                 /*
431                  * Do not set R1BIO_Uptodate if the current device is
432                  * rebuilding or Faulty. This is because we cannot use
433                  * such device for properly reading the data back (we could
434                  * potentially use it, if the current write would have felt
435                  * before rdev->recovery_offset, but for simplicity we don't
436                  * check this here.
437                  */
438                 if (test_bit(In_sync, &conf->mirrors[mirror].rdev->flags) &&
439                     !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags))
440                         set_bit(R1BIO_Uptodate, &r1_bio->state);
441
442                 /* Maybe we can clear some bad blocks. */
443                 if (is_badblock(conf->mirrors[mirror].rdev,
444                                 r1_bio->sector, r1_bio->sectors,
445                                 &first_bad, &bad_sectors)) {
446                         r1_bio->bios[mirror] = IO_MADE_GOOD;
447                         set_bit(R1BIO_MadeGood, &r1_bio->state);
448                 }
449         }
450
451         if (behind) {
452                 if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
453                         atomic_dec(&r1_bio->behind_remaining);
454
455                 /*
456                  * In behind mode, we ACK the master bio once the I/O
457                  * has safely reached all non-writemostly
458                  * disks. Setting the Returned bit ensures that this
459                  * gets done only once -- we don't ever want to return
460                  * -EIO here, instead we'll wait
461                  */
462                 if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
463                     test_bit(R1BIO_Uptodate, &r1_bio->state)) {
464                         /* Maybe we can return now */
465                         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
466                                 struct bio *mbio = r1_bio->master_bio;
467                                 pr_debug("raid1: behind end write sectors"
468                                          " %llu-%llu\n",
469                                          (unsigned long long) mbio->bi_sector,
470                                          (unsigned long long) mbio->bi_sector +
471                                          bio_sectors(mbio) - 1);
472                                 call_bio_endio(r1_bio);
473                         }
474                 }
475         }
476         if (r1_bio->bios[mirror] == NULL)
477                 rdev_dec_pending(conf->mirrors[mirror].rdev,
478                                  conf->mddev);
479
480         /*
481          * Let's see if all mirrored write operations have finished
482          * already.
483          */
484         r1_bio_write_done(r1_bio);
485
486         if (to_put)
487                 bio_put(to_put);
488 }
489
490
491 /*
492  * This routine returns the disk from which the requested read should
493  * be done. There is a per-array 'next expected sequential IO' sector
494  * number - if this matches on the next IO then we use the last disk.
495  * There is also a per-disk 'last know head position' sector that is
496  * maintained from IRQ contexts, both the normal and the resync IO
497  * completion handlers update this position correctly. If there is no
498  * perfect sequential match then we pick the disk whose head is closest.
499  *
500  * If there are 2 mirrors in the same 2 devices, performance degrades
501  * because position is mirror, not device based.
502  *
503  * The rdev for the device selected will have nr_pending incremented.
504  */
505 static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sectors)
506 {
507         const sector_t this_sector = r1_bio->sector;
508         int sectors;
509         int best_good_sectors;
510         int best_disk, best_dist_disk, best_pending_disk;
511         int has_nonrot_disk;
512         int disk;
513         sector_t best_dist;
514         unsigned int min_pending;
515         struct md_rdev *rdev;
516         int choose_first;
517         int choose_next_idle;
518
519         rcu_read_lock();
520         /*
521          * Check if we can balance. We can balance on the whole
522          * device if no resync is going on, or below the resync window.
523          * We take the first readable disk when above the resync window.
524          */
525  retry:
526         sectors = r1_bio->sectors;
527         best_disk = -1;
528         best_dist_disk = -1;
529         best_dist = MaxSector;
530         best_pending_disk = -1;
531         min_pending = UINT_MAX;
532         best_good_sectors = 0;
533         has_nonrot_disk = 0;
534         choose_next_idle = 0;
535
536         if (conf->mddev->recovery_cp < MaxSector &&
537             (this_sector + sectors >= conf->next_resync))
538                 choose_first = 1;
539         else
540                 choose_first = 0;
541
542         for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) {
543                 sector_t dist;
544                 sector_t first_bad;
545                 int bad_sectors;
546                 unsigned int pending;
547                 bool nonrot;
548
549                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
550                 if (r1_bio->bios[disk] == IO_BLOCKED
551                     || rdev == NULL
552                     || test_bit(Unmerged, &rdev->flags)
553                     || test_bit(Faulty, &rdev->flags))
554                         continue;
555                 if (!test_bit(In_sync, &rdev->flags) &&
556                     rdev->recovery_offset < this_sector + sectors)
557                         continue;
558                 if (test_bit(WriteMostly, &rdev->flags)) {
559                         /* Don't balance among write-mostly, just
560                          * use the first as a last resort */
561                         if (best_disk < 0) {
562                                 if (is_badblock(rdev, this_sector, sectors,
563                                                 &first_bad, &bad_sectors)) {
564                                         if (first_bad < this_sector)
565                                                 /* Cannot use this */
566                                                 continue;
567                                         best_good_sectors = first_bad - this_sector;
568                                 } else
569                                         best_good_sectors = sectors;
570                                 best_disk = disk;
571                         }
572                         continue;
573                 }
574                 /* This is a reasonable device to use.  It might
575                  * even be best.
576                  */
577                 if (is_badblock(rdev, this_sector, sectors,
578                                 &first_bad, &bad_sectors)) {
579                         if (best_dist < MaxSector)
580                                 /* already have a better device */
581                                 continue;
582                         if (first_bad <= this_sector) {
583                                 /* cannot read here. If this is the 'primary'
584                                  * device, then we must not read beyond
585                                  * bad_sectors from another device..
586                                  */
587                                 bad_sectors -= (this_sector - first_bad);
588                                 if (choose_first && sectors > bad_sectors)
589                                         sectors = bad_sectors;
590                                 if (best_good_sectors > sectors)
591                                         best_good_sectors = sectors;
592
593                         } else {
594                                 sector_t good_sectors = first_bad - this_sector;
595                                 if (good_sectors > best_good_sectors) {
596                                         best_good_sectors = good_sectors;
597                                         best_disk = disk;
598                                 }
599                                 if (choose_first)
600                                         break;
601                         }
602                         continue;
603                 } else
604                         best_good_sectors = sectors;
605
606                 nonrot = blk_queue_nonrot(bdev_get_queue(rdev->bdev));
607                 has_nonrot_disk |= nonrot;
608                 pending = atomic_read(&rdev->nr_pending);
609                 dist = abs(this_sector - conf->mirrors[disk].head_position);
610                 if (choose_first) {
611                         best_disk = disk;
612                         break;
613                 }
614                 /* Don't change to another disk for sequential reads */
615                 if (conf->mirrors[disk].next_seq_sect == this_sector
616                     || dist == 0) {
617                         int opt_iosize = bdev_io_opt(rdev->bdev) >> 9;
618                         struct raid1_info *mirror = &conf->mirrors[disk];
619
620                         best_disk = disk;
621                         /*
622                          * If buffered sequential IO size exceeds optimal
623                          * iosize, check if there is idle disk. If yes, choose
624                          * the idle disk. read_balance could already choose an
625                          * idle disk before noticing it's a sequential IO in
626                          * this disk. This doesn't matter because this disk
627                          * will idle, next time it will be utilized after the
628                          * first disk has IO size exceeds optimal iosize. In
629                          * this way, iosize of the first disk will be optimal
630                          * iosize at least. iosize of the second disk might be
631                          * small, but not a big deal since when the second disk
632                          * starts IO, the first disk is likely still busy.
633                          */
634                         if (nonrot && opt_iosize > 0 &&
635                             mirror->seq_start != MaxSector &&
636                             mirror->next_seq_sect > opt_iosize &&
637                             mirror->next_seq_sect - opt_iosize >=
638                             mirror->seq_start) {
639                                 choose_next_idle = 1;
640                                 continue;
641                         }
642                         break;
643                 }
644                 /* If device is idle, use it */
645                 if (pending == 0) {
646                         best_disk = disk;
647                         break;
648                 }
649
650                 if (choose_next_idle)
651                         continue;
652
653                 if (min_pending > pending) {
654                         min_pending = pending;
655                         best_pending_disk = disk;
656                 }
657
658                 if (dist < best_dist) {
659                         best_dist = dist;
660                         best_dist_disk = disk;
661                 }
662         }
663
664         /*
665          * If all disks are rotational, choose the closest disk. If any disk is
666          * non-rotational, choose the disk with less pending request even the
667          * disk is rotational, which might/might not be optimal for raids with
668          * mixed ratation/non-rotational disks depending on workload.
669          */
670         if (best_disk == -1) {
671                 if (has_nonrot_disk)
672                         best_disk = best_pending_disk;
673                 else
674                         best_disk = best_dist_disk;
675         }
676
677         if (best_disk >= 0) {
678                 rdev = rcu_dereference(conf->mirrors[best_disk].rdev);
679                 if (!rdev)
680                         goto retry;
681                 atomic_inc(&rdev->nr_pending);
682                 if (test_bit(Faulty, &rdev->flags)) {
683                         /* cannot risk returning a device that failed
684                          * before we inc'ed nr_pending
685                          */
686                         rdev_dec_pending(rdev, conf->mddev);
687                         goto retry;
688                 }
689                 sectors = best_good_sectors;
690
691                 if (conf->mirrors[best_disk].next_seq_sect != this_sector)
692                         conf->mirrors[best_disk].seq_start = this_sector;
693
694                 conf->mirrors[best_disk].next_seq_sect = this_sector + sectors;
695         }
696         rcu_read_unlock();
697         *max_sectors = sectors;
698
699         return best_disk;
700 }
701
702 static int raid1_mergeable_bvec(struct request_queue *q,
703                                 struct bvec_merge_data *bvm,
704                                 struct bio_vec *biovec)
705 {
706         struct mddev *mddev = q->queuedata;
707         struct r1conf *conf = mddev->private;
708         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
709         int max = biovec->bv_len;
710
711         if (mddev->merge_check_needed) {
712                 int disk;
713                 rcu_read_lock();
714                 for (disk = 0; disk < conf->raid_disks * 2; disk++) {
715                         struct md_rdev *rdev = rcu_dereference(
716                                 conf->mirrors[disk].rdev);
717                         if (rdev && !test_bit(Faulty, &rdev->flags)) {
718                                 struct request_queue *q =
719                                         bdev_get_queue(rdev->bdev);
720                                 if (q->merge_bvec_fn) {
721                                         bvm->bi_sector = sector +
722                                                 rdev->data_offset;
723                                         bvm->bi_bdev = rdev->bdev;
724                                         max = min(max, q->merge_bvec_fn(
725                                                           q, bvm, biovec));
726                                 }
727                         }
728                 }
729                 rcu_read_unlock();
730         }
731         return max;
732
733 }
734
735 int md_raid1_congested(struct mddev *mddev, int bits)
736 {
737         struct r1conf *conf = mddev->private;
738         int i, ret = 0;
739
740         if ((bits & (1 << BDI_async_congested)) &&
741             conf->pending_count >= max_queued_requests)
742                 return 1;
743
744         rcu_read_lock();
745         for (i = 0; i < conf->raid_disks * 2; i++) {
746                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
747                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
748                         struct request_queue *q = bdev_get_queue(rdev->bdev);
749
750                         BUG_ON(!q);
751
752                         /* Note the '|| 1' - when read_balance prefers
753                          * non-congested targets, it can be removed
754                          */
755                         if ((bits & (1<<BDI_async_congested)) || 1)
756                                 ret |= bdi_congested(&q->backing_dev_info, bits);
757                         else
758                                 ret &= bdi_congested(&q->backing_dev_info, bits);
759                 }
760         }
761         rcu_read_unlock();
762         return ret;
763 }
764 EXPORT_SYMBOL_GPL(md_raid1_congested);
765
766 static int raid1_congested(void *data, int bits)
767 {
768         struct mddev *mddev = data;
769
770         return mddev_congested(mddev, bits) ||
771                 md_raid1_congested(mddev, bits);
772 }
773
774 static void flush_pending_writes(struct r1conf *conf)
775 {
776         /* Any writes that have been queued but are awaiting
777          * bitmap updates get flushed here.
778          */
779         spin_lock_irq(&conf->device_lock);
780
781         if (conf->pending_bio_list.head) {
782                 struct bio *bio;
783                 bio = bio_list_get(&conf->pending_bio_list);
784                 conf->pending_count = 0;
785                 spin_unlock_irq(&conf->device_lock);
786                 /* flush any pending bitmap writes to
787                  * disk before proceeding w/ I/O */
788                 bitmap_unplug(conf->mddev->bitmap);
789                 wake_up(&conf->wait_barrier);
790
791                 while (bio) { /* submit pending writes */
792                         struct bio *next = bio->bi_next;
793                         bio->bi_next = NULL;
794                         if (unlikely((bio->bi_rw & REQ_DISCARD) &&
795                             !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
796                                 /* Just ignore it */
797                                 bio_endio(bio, 0);
798                         else
799                                 generic_make_request(bio);
800                         bio = next;
801                 }
802         } else
803                 spin_unlock_irq(&conf->device_lock);
804 }
805
806 /* Barriers....
807  * Sometimes we need to suspend IO while we do something else,
808  * either some resync/recovery, or reconfigure the array.
809  * To do this we raise a 'barrier'.
810  * The 'barrier' is a counter that can be raised multiple times
811  * to count how many activities are happening which preclude
812  * normal IO.
813  * We can only raise the barrier if there is no pending IO.
814  * i.e. if nr_pending == 0.
815  * We choose only to raise the barrier if no-one is waiting for the
816  * barrier to go down.  This means that as soon as an IO request
817  * is ready, no other operations which require a barrier will start
818  * until the IO request has had a chance.
819  *
820  * So: regular IO calls 'wait_barrier'.  When that returns there
821  *    is no backgroup IO happening,  It must arrange to call
822  *    allow_barrier when it has finished its IO.
823  * backgroup IO calls must call raise_barrier.  Once that returns
824  *    there is no normal IO happeing.  It must arrange to call
825  *    lower_barrier when the particular background IO completes.
826  */
827 static void raise_barrier(struct r1conf *conf)
828 {
829         spin_lock_irq(&conf->resync_lock);
830
831         /* Wait until no block IO is waiting */
832         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
833                             conf->resync_lock);
834
835         /* block any new IO from starting */
836         conf->barrier++;
837
838         /* For these conditions we must wait:
839          * A: while the array is in frozen state
840          * B: while barrier >= RESYNC_DEPTH, meaning resync reach
841          *    the max count which allowed.
842          * C: next_resync + RESYNC_SECTORS > start_next_window, meaning
843          *    next resync will reach to the window which normal bios are
844          *    handling.
845          */
846         wait_event_lock_irq(conf->wait_barrier,
847                             !conf->array_frozen &&
848                             conf->barrier < RESYNC_DEPTH &&
849                             (conf->start_next_window >=
850                              conf->next_resync + RESYNC_SECTORS),
851                             conf->resync_lock);
852
853         spin_unlock_irq(&conf->resync_lock);
854 }
855
856 static void lower_barrier(struct r1conf *conf)
857 {
858         unsigned long flags;
859         BUG_ON(conf->barrier <= 0);
860         spin_lock_irqsave(&conf->resync_lock, flags);
861         conf->barrier--;
862         spin_unlock_irqrestore(&conf->resync_lock, flags);
863         wake_up(&conf->wait_barrier);
864 }
865
866 static bool need_to_wait_for_sync(struct r1conf *conf, struct bio *bio)
867 {
868         bool wait = false;
869
870         if (conf->array_frozen || !bio)
871                 wait = true;
872         else if (conf->barrier && bio_data_dir(bio) == WRITE) {
873                 if (conf->next_resync < RESYNC_WINDOW_SECTORS)
874                         wait = true;
875                 else if ((conf->next_resync - RESYNC_WINDOW_SECTORS
876                                 >= bio_end_sector(bio)) ||
877                          (conf->next_resync + NEXT_NORMALIO_DISTANCE
878                                 <= bio->bi_sector))
879                         wait = false;
880                 else
881                         wait = true;
882         }
883
884         return wait;
885 }
886
887 static sector_t wait_barrier(struct r1conf *conf, struct bio *bio)
888 {
889         sector_t sector = 0;
890
891         spin_lock_irq(&conf->resync_lock);
892         if (need_to_wait_for_sync(conf, bio)) {
893                 conf->nr_waiting++;
894                 /* Wait for the barrier to drop.
895                  * However if there are already pending
896                  * requests (preventing the barrier from
897                  * rising completely), and the
898                  * pre-process bio queue isn't empty,
899                  * then don't wait, as we need to empty
900                  * that queue to get the nr_pending
901                  * count down.
902                  */
903                 wait_event_lock_irq(conf->wait_barrier,
904                                     !conf->array_frozen &&
905                                     (!conf->barrier ||
906                                     ((conf->start_next_window <
907                                       conf->next_resync + RESYNC_SECTORS) &&
908                                      current->bio_list &&
909                                      !bio_list_empty(current->bio_list))),
910                                     conf->resync_lock);
911                 conf->nr_waiting--;
912         }
913
914         if (bio && bio_data_dir(bio) == WRITE) {
915                 if (conf->next_resync + NEXT_NORMALIO_DISTANCE
916                     <= bio->bi_sector) {
917                         if (conf->start_next_window == MaxSector)
918                                 conf->start_next_window =
919                                         conf->next_resync +
920                                         NEXT_NORMALIO_DISTANCE;
921
922                         if ((conf->start_next_window + NEXT_NORMALIO_DISTANCE)
923                             <= bio->bi_sector)
924                                 conf->next_window_requests++;
925                         else
926                                 conf->current_window_requests++;
927                         sector = conf->start_next_window;
928                 }
929         }
930
931         conf->nr_pending++;
932         spin_unlock_irq(&conf->resync_lock);
933         return sector;
934 }
935
936 static void allow_barrier(struct r1conf *conf, sector_t start_next_window,
937                           sector_t bi_sector)
938 {
939         unsigned long flags;
940
941         spin_lock_irqsave(&conf->resync_lock, flags);
942         conf->nr_pending--;
943         if (start_next_window) {
944                 if (start_next_window == conf->start_next_window) {
945                         if (conf->start_next_window + NEXT_NORMALIO_DISTANCE
946                             <= bi_sector)
947                                 conf->next_window_requests--;
948                         else
949                                 conf->current_window_requests--;
950                 } else
951                         conf->current_window_requests--;
952
953                 if (!conf->current_window_requests) {
954                         if (conf->next_window_requests) {
955                                 conf->current_window_requests =
956                                         conf->next_window_requests;
957                                 conf->next_window_requests = 0;
958                                 conf->start_next_window +=
959                                         NEXT_NORMALIO_DISTANCE;
960                         } else
961                                 conf->start_next_window = MaxSector;
962                 }
963         }
964         spin_unlock_irqrestore(&conf->resync_lock, flags);
965         wake_up(&conf->wait_barrier);
966 }
967
968 static void freeze_array(struct r1conf *conf, int extra)
969 {
970         /* stop syncio and normal IO and wait for everything to
971          * go quite.
972          * We wait until nr_pending match nr_queued+extra
973          * This is called in the context of one normal IO request
974          * that has failed. Thus any sync request that might be pending
975          * will be blocked by nr_pending, and we need to wait for
976          * pending IO requests to complete or be queued for re-try.
977          * Thus the number queued (nr_queued) plus this request (extra)
978          * must match the number of pending IOs (nr_pending) before
979          * we continue.
980          */
981         spin_lock_irq(&conf->resync_lock);
982         conf->array_frozen = 1;
983         wait_event_lock_irq_cmd(conf->wait_barrier,
984                                 conf->nr_pending == conf->nr_queued+extra,
985                                 conf->resync_lock,
986                                 flush_pending_writes(conf));
987         spin_unlock_irq(&conf->resync_lock);
988 }
989 static void unfreeze_array(struct r1conf *conf)
990 {
991         /* reverse the effect of the freeze */
992         spin_lock_irq(&conf->resync_lock);
993         conf->array_frozen = 0;
994         wake_up(&conf->wait_barrier);
995         spin_unlock_irq(&conf->resync_lock);
996 }
997
998
999 /* duplicate the data pages for behind I/O 
1000  */
1001 static void alloc_behind_pages(struct bio *bio, struct r1bio *r1_bio)
1002 {
1003         int i;
1004         struct bio_vec *bvec;
1005         struct bio_vec *bvecs = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
1006                                         GFP_NOIO);
1007         if (unlikely(!bvecs))
1008                 return;
1009
1010         bio_for_each_segment_all(bvec, bio, i) {
1011                 bvecs[i] = *bvec;
1012                 bvecs[i].bv_page = alloc_page(GFP_NOIO);
1013                 if (unlikely(!bvecs[i].bv_page))
1014                         goto do_sync_io;
1015                 memcpy(kmap(bvecs[i].bv_page) + bvec->bv_offset,
1016                        kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
1017                 kunmap(bvecs[i].bv_page);
1018                 kunmap(bvec->bv_page);
1019         }
1020         r1_bio->behind_bvecs = bvecs;
1021         r1_bio->behind_page_count = bio->bi_vcnt;
1022         set_bit(R1BIO_BehindIO, &r1_bio->state);
1023         return;
1024
1025 do_sync_io:
1026         for (i = 0; i < bio->bi_vcnt; i++)
1027                 if (bvecs[i].bv_page)
1028                         put_page(bvecs[i].bv_page);
1029         kfree(bvecs);
1030         pr_debug("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
1031 }
1032
1033 struct raid1_plug_cb {
1034         struct blk_plug_cb      cb;
1035         struct bio_list         pending;
1036         int                     pending_cnt;
1037 };
1038
1039 static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule)
1040 {
1041         struct raid1_plug_cb *plug = container_of(cb, struct raid1_plug_cb,
1042                                                   cb);
1043         struct mddev *mddev = plug->cb.data;
1044         struct r1conf *conf = mddev->private;
1045         struct bio *bio;
1046
1047         if (from_schedule || current->bio_list) {
1048                 spin_lock_irq(&conf->device_lock);
1049                 bio_list_merge(&conf->pending_bio_list, &plug->pending);
1050                 conf->pending_count += plug->pending_cnt;
1051                 spin_unlock_irq(&conf->device_lock);
1052                 wake_up(&conf->wait_barrier);
1053                 md_wakeup_thread(mddev->thread);
1054                 kfree(plug);
1055                 return;
1056         }
1057
1058         /* we aren't scheduling, so we can do the write-out directly. */
1059         bio = bio_list_get(&plug->pending);
1060         bitmap_unplug(mddev->bitmap);
1061         wake_up(&conf->wait_barrier);
1062
1063         while (bio) { /* submit pending writes */
1064                 struct bio *next = bio->bi_next;
1065                 bio->bi_next = NULL;
1066                 if (unlikely((bio->bi_rw & REQ_DISCARD) &&
1067                     !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
1068                         /* Just ignore it */
1069                         bio_endio(bio, 0);
1070                 else
1071                         generic_make_request(bio);
1072                 bio = next;
1073         }
1074         kfree(plug);
1075 }
1076
1077 static void make_request(struct mddev *mddev, struct bio * bio)
1078 {
1079         struct r1conf *conf = mddev->private;
1080         struct raid1_info *mirror;
1081         struct r1bio *r1_bio;
1082         struct bio *read_bio;
1083         int i, disks;
1084         struct bitmap *bitmap;
1085         unsigned long flags;
1086         const int rw = bio_data_dir(bio);
1087         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
1088         const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
1089         const unsigned long do_discard = (bio->bi_rw
1090                                           & (REQ_DISCARD | REQ_SECURE));
1091         const unsigned long do_same = (bio->bi_rw & REQ_WRITE_SAME);
1092         struct md_rdev *blocked_rdev;
1093         struct blk_plug_cb *cb;
1094         struct raid1_plug_cb *plug = NULL;
1095         int first_clone;
1096         int sectors_handled;
1097         int max_sectors;
1098         sector_t start_next_window;
1099
1100         /*
1101          * Register the new request and wait if the reconstruction
1102          * thread has put up a bar for new requests.
1103          * Continue immediately if no resync is active currently.
1104          */
1105
1106         md_write_start(mddev, bio); /* wait on superblock update early */
1107
1108         if (bio_data_dir(bio) == WRITE &&
1109             bio_end_sector(bio) > mddev->suspend_lo &&
1110             bio->bi_sector < mddev->suspend_hi) {
1111                 /* As the suspend_* range is controlled by
1112                  * userspace, we want an interruptible
1113                  * wait.
1114                  */
1115                 DEFINE_WAIT(w);
1116                 for (;;) {
1117                         flush_signals(current);
1118                         prepare_to_wait(&conf->wait_barrier,
1119                                         &w, TASK_INTERRUPTIBLE);
1120                         if (bio_end_sector(bio) <= mddev->suspend_lo ||
1121                             bio->bi_sector >= mddev->suspend_hi)
1122                                 break;
1123                         schedule();
1124                 }
1125                 finish_wait(&conf->wait_barrier, &w);
1126         }
1127
1128         start_next_window = wait_barrier(conf, bio);
1129
1130         bitmap = mddev->bitmap;
1131
1132         /*
1133          * make_request() can abort the operation when READA is being
1134          * used and no empty request is available.
1135          *
1136          */
1137         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
1138
1139         r1_bio->master_bio = bio;
1140         r1_bio->sectors = bio_sectors(bio);
1141         r1_bio->state = 0;
1142         r1_bio->mddev = mddev;
1143         r1_bio->sector = bio->bi_sector;
1144
1145         /* We might need to issue multiple reads to different
1146          * devices if there are bad blocks around, so we keep
1147          * track of the number of reads in bio->bi_phys_segments.
1148          * If this is 0, there is only one r1_bio and no locking
1149          * will be needed when requests complete.  If it is
1150          * non-zero, then it is the number of not-completed requests.
1151          */
1152         bio->bi_phys_segments = 0;
1153         clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1154
1155         if (rw == READ) {
1156                 /*
1157                  * read balancing logic:
1158                  */
1159                 int rdisk;
1160
1161 read_again:
1162                 rdisk = read_balance(conf, r1_bio, &max_sectors);
1163
1164                 if (rdisk < 0) {
1165                         /* couldn't find anywhere to read from */
1166                         raid_end_bio_io(r1_bio);
1167                         return;
1168                 }
1169                 mirror = conf->mirrors + rdisk;
1170
1171                 if (test_bit(WriteMostly, &mirror->rdev->flags) &&
1172                     bitmap) {
1173                         /* Reading from a write-mostly device must
1174                          * take care not to over-take any writes
1175                          * that are 'behind'
1176                          */
1177                         wait_event(bitmap->behind_wait,
1178                                    atomic_read(&bitmap->behind_writes) == 0);
1179                 }
1180                 r1_bio->read_disk = rdisk;
1181
1182                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1183                 bio_trim(read_bio, r1_bio->sector - bio->bi_sector,
1184                          max_sectors);
1185
1186                 r1_bio->bios[rdisk] = read_bio;
1187
1188                 read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
1189                 read_bio->bi_bdev = mirror->rdev->bdev;
1190                 read_bio->bi_end_io = raid1_end_read_request;
1191                 read_bio->bi_rw = READ | do_sync;
1192                 read_bio->bi_private = r1_bio;
1193
1194                 if (max_sectors < r1_bio->sectors) {
1195                         /* could not read all from this device, so we will
1196                          * need another r1_bio.
1197                          */
1198
1199                         sectors_handled = (r1_bio->sector + max_sectors
1200                                            - bio->bi_sector);
1201                         r1_bio->sectors = max_sectors;
1202                         spin_lock_irq(&conf->device_lock);
1203                         if (bio->bi_phys_segments == 0)
1204                                 bio->bi_phys_segments = 2;
1205                         else
1206                                 bio->bi_phys_segments++;
1207                         spin_unlock_irq(&conf->device_lock);
1208                         /* Cannot call generic_make_request directly
1209                          * as that will be queued in __make_request
1210                          * and subsequent mempool_alloc might block waiting
1211                          * for it.  So hand bio over to raid1d.
1212                          */
1213                         reschedule_retry(r1_bio);
1214
1215                         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
1216
1217                         r1_bio->master_bio = bio;
1218                         r1_bio->sectors = bio_sectors(bio) - sectors_handled;
1219                         r1_bio->state = 0;
1220                         r1_bio->mddev = mddev;
1221                         r1_bio->sector = bio->bi_sector + sectors_handled;
1222                         goto read_again;
1223                 } else
1224                         generic_make_request(read_bio);
1225                 return;
1226         }
1227
1228         /*
1229          * WRITE:
1230          */
1231         if (conf->pending_count >= max_queued_requests) {
1232                 md_wakeup_thread(mddev->thread);
1233                 wait_event(conf->wait_barrier,
1234                            conf->pending_count < max_queued_requests);
1235         }
1236         /* first select target devices under rcu_lock and
1237          * inc refcount on their rdev.  Record them by setting
1238          * bios[x] to bio
1239          * If there are known/acknowledged bad blocks on any device on
1240          * which we have seen a write error, we want to avoid writing those
1241          * blocks.
1242          * This potentially requires several writes to write around
1243          * the bad blocks.  Each set of writes gets it's own r1bio
1244          * with a set of bios attached.
1245          */
1246
1247         disks = conf->raid_disks * 2;
1248  retry_write:
1249         r1_bio->start_next_window = start_next_window;
1250         blocked_rdev = NULL;
1251         rcu_read_lock();
1252         max_sectors = r1_bio->sectors;
1253         for (i = 0;  i < disks; i++) {
1254                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
1255                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1256                         atomic_inc(&rdev->nr_pending);
1257                         blocked_rdev = rdev;
1258                         break;
1259                 }
1260                 r1_bio->bios[i] = NULL;
1261                 if (!rdev || test_bit(Faulty, &rdev->flags)
1262                     || test_bit(Unmerged, &rdev->flags)) {
1263                         if (i < conf->raid_disks)
1264                                 set_bit(R1BIO_Degraded, &r1_bio->state);
1265                         continue;
1266                 }
1267
1268                 atomic_inc(&rdev->nr_pending);
1269                 if (test_bit(WriteErrorSeen, &rdev->flags)) {
1270                         sector_t first_bad;
1271                         int bad_sectors;
1272                         int is_bad;
1273
1274                         is_bad = is_badblock(rdev, r1_bio->sector,
1275                                              max_sectors,
1276                                              &first_bad, &bad_sectors);
1277                         if (is_bad < 0) {
1278                                 /* mustn't write here until the bad block is
1279                                  * acknowledged*/
1280                                 set_bit(BlockedBadBlocks, &rdev->flags);
1281                                 blocked_rdev = rdev;
1282                                 break;
1283                         }
1284                         if (is_bad && first_bad <= r1_bio->sector) {
1285                                 /* Cannot write here at all */
1286                                 bad_sectors -= (r1_bio->sector - first_bad);
1287                                 if (bad_sectors < max_sectors)
1288                                         /* mustn't write more than bad_sectors
1289                                          * to other devices yet
1290                                          */
1291                                         max_sectors = bad_sectors;
1292                                 rdev_dec_pending(rdev, mddev);
1293                                 /* We don't set R1BIO_Degraded as that
1294                                  * only applies if the disk is
1295                                  * missing, so it might be re-added,
1296                                  * and we want to know to recover this
1297                                  * chunk.
1298                                  * In this case the device is here,
1299                                  * and the fact that this chunk is not
1300                                  * in-sync is recorded in the bad
1301                                  * block log
1302                                  */
1303                                 continue;
1304                         }
1305                         if (is_bad) {
1306                                 int good_sectors = first_bad - r1_bio->sector;
1307                                 if (good_sectors < max_sectors)
1308                                         max_sectors = good_sectors;
1309                         }
1310                 }
1311                 r1_bio->bios[i] = bio;
1312         }
1313         rcu_read_unlock();
1314
1315         if (unlikely(blocked_rdev)) {
1316                 /* Wait for this device to become unblocked */
1317                 int j;
1318                 sector_t old = start_next_window;
1319
1320                 for (j = 0; j < i; j++)
1321                         if (r1_bio->bios[j])
1322                                 rdev_dec_pending(conf->mirrors[j].rdev, mddev);
1323                 r1_bio->state = 0;
1324                 allow_barrier(conf, start_next_window, bio->bi_sector);
1325                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
1326                 start_next_window = wait_barrier(conf, bio);
1327                 /*
1328                  * We must make sure the multi r1bios of bio have
1329                  * the same value of bi_phys_segments
1330                  */
1331                 if (bio->bi_phys_segments && old &&
1332                     old != start_next_window)
1333                         /* Wait for the former r1bio(s) to complete */
1334                         wait_event(conf->wait_barrier,
1335                                    bio->bi_phys_segments == 1);
1336                 goto retry_write;
1337         }
1338
1339         if (max_sectors < r1_bio->sectors) {
1340                 /* We are splitting this write into multiple parts, so
1341                  * we need to prepare for allocating another r1_bio.
1342                  */
1343                 r1_bio->sectors = max_sectors;
1344                 spin_lock_irq(&conf->device_lock);
1345                 if (bio->bi_phys_segments == 0)
1346                         bio->bi_phys_segments = 2;
1347                 else
1348                         bio->bi_phys_segments++;
1349                 spin_unlock_irq(&conf->device_lock);
1350         }
1351         sectors_handled = r1_bio->sector + max_sectors - bio->bi_sector;
1352
1353         atomic_set(&r1_bio->remaining, 1);
1354         atomic_set(&r1_bio->behind_remaining, 0);
1355
1356         first_clone = 1;
1357         for (i = 0; i < disks; i++) {
1358                 struct bio *mbio;
1359                 if (!r1_bio->bios[i])
1360                         continue;
1361
1362                 mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1363                 bio_trim(mbio, r1_bio->sector - bio->bi_sector, max_sectors);
1364
1365                 if (first_clone) {
1366                         /* do behind I/O ?
1367                          * Not if there are too many, or cannot
1368                          * allocate memory, or a reader on WriteMostly
1369                          * is waiting for behind writes to flush */
1370                         if (bitmap &&
1371                             (atomic_read(&bitmap->behind_writes)
1372                              < mddev->bitmap_info.max_write_behind) &&
1373                             !waitqueue_active(&bitmap->behind_wait))
1374                                 alloc_behind_pages(mbio, r1_bio);
1375
1376                         bitmap_startwrite(bitmap, r1_bio->sector,
1377                                           r1_bio->sectors,
1378                                           test_bit(R1BIO_BehindIO,
1379                                                    &r1_bio->state));
1380                         first_clone = 0;
1381                 }
1382                 if (r1_bio->behind_bvecs) {
1383                         struct bio_vec *bvec;
1384                         int j;
1385
1386                         /*
1387                          * We trimmed the bio, so _all is legit
1388                          */
1389                         bio_for_each_segment_all(bvec, mbio, j)
1390                                 bvec->bv_page = r1_bio->behind_bvecs[j].bv_page;
1391                         if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
1392                                 atomic_inc(&r1_bio->behind_remaining);
1393                 }
1394
1395                 r1_bio->bios[i] = mbio;
1396
1397                 mbio->bi_sector = (r1_bio->sector +
1398                                    conf->mirrors[i].rdev->data_offset);
1399                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1400                 mbio->bi_end_io = raid1_end_write_request;
1401                 mbio->bi_rw =
1402                         WRITE | do_flush_fua | do_sync | do_discard | do_same;
1403                 mbio->bi_private = r1_bio;
1404
1405                 atomic_inc(&r1_bio->remaining);
1406
1407                 cb = blk_check_plugged(raid1_unplug, mddev, sizeof(*plug));
1408                 if (cb)
1409                         plug = container_of(cb, struct raid1_plug_cb, cb);
1410                 else
1411                         plug = NULL;
1412                 spin_lock_irqsave(&conf->device_lock, flags);
1413                 if (plug) {
1414                         bio_list_add(&plug->pending, mbio);
1415                         plug->pending_cnt++;
1416                 } else {
1417                         bio_list_add(&conf->pending_bio_list, mbio);
1418                         conf->pending_count++;
1419                 }
1420                 spin_unlock_irqrestore(&conf->device_lock, flags);
1421                 if (!plug)
1422                         md_wakeup_thread(mddev->thread);
1423         }
1424         /* Mustn't call r1_bio_write_done before this next test,
1425          * as it could result in the bio being freed.
1426          */
1427         if (sectors_handled < bio_sectors(bio)) {
1428                 r1_bio_write_done(r1_bio);
1429                 /* We need another r1_bio.  It has already been counted
1430                  * in bio->bi_phys_segments
1431                  */
1432                 r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
1433                 r1_bio->master_bio = bio;
1434                 r1_bio->sectors = bio_sectors(bio) - sectors_handled;
1435                 r1_bio->state = 0;
1436                 r1_bio->mddev = mddev;
1437                 r1_bio->sector = bio->bi_sector + sectors_handled;
1438                 goto retry_write;
1439         }
1440
1441         r1_bio_write_done(r1_bio);
1442
1443         /* In case raid1d snuck in to freeze_array */
1444         wake_up(&conf->wait_barrier);
1445 }
1446
1447 static void status(struct seq_file *seq, struct mddev *mddev)
1448 {
1449         struct r1conf *conf = mddev->private;
1450         int i;
1451
1452         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
1453                    conf->raid_disks - mddev->degraded);
1454         rcu_read_lock();
1455         for (i = 0; i < conf->raid_disks; i++) {
1456                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
1457                 seq_printf(seq, "%s",
1458                            rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
1459         }
1460         rcu_read_unlock();
1461         seq_printf(seq, "]");
1462 }
1463
1464
1465 static void error(struct mddev *mddev, struct md_rdev *rdev)
1466 {
1467         char b[BDEVNAME_SIZE];
1468         struct r1conf *conf = mddev->private;
1469
1470         /*
1471          * If it is not operational, then we have already marked it as dead
1472          * else if it is the last working disks, ignore the error, let the
1473          * next level up know.
1474          * else mark the drive as failed
1475          */
1476         if (test_bit(In_sync, &rdev->flags)
1477             && (conf->raid_disks - mddev->degraded) == 1) {
1478                 /*
1479                  * Don't fail the drive, act as though we were just a
1480                  * normal single drive.
1481                  * However don't try a recovery from this drive as
1482                  * it is very likely to fail.
1483                  */
1484                 conf->recovery_disabled = mddev->recovery_disabled;
1485                 return;
1486         }
1487         set_bit(Blocked, &rdev->flags);
1488         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1489                 unsigned long flags;
1490                 spin_lock_irqsave(&conf->device_lock, flags);
1491                 mddev->degraded++;
1492                 set_bit(Faulty, &rdev->flags);
1493                 spin_unlock_irqrestore(&conf->device_lock, flags);
1494                 /*
1495                  * if recovery is running, make sure it aborts.
1496                  */
1497                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1498         } else
1499                 set_bit(Faulty, &rdev->flags);
1500         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1501         printk(KERN_ALERT
1502                "md/raid1:%s: Disk failure on %s, disabling device.\n"
1503                "md/raid1:%s: Operation continuing on %d devices.\n",
1504                mdname(mddev), bdevname(rdev->bdev, b),
1505                mdname(mddev), conf->raid_disks - mddev->degraded);
1506 }
1507
1508 static void print_conf(struct r1conf *conf)
1509 {
1510         int i;
1511
1512         printk(KERN_DEBUG "RAID1 conf printout:\n");
1513         if (!conf) {
1514                 printk(KERN_DEBUG "(!conf)\n");
1515                 return;
1516         }
1517         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1518                 conf->raid_disks);
1519
1520         rcu_read_lock();
1521         for (i = 0; i < conf->raid_disks; i++) {
1522                 char b[BDEVNAME_SIZE];
1523                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
1524                 if (rdev)
1525                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1526                                i, !test_bit(In_sync, &rdev->flags),
1527                                !test_bit(Faulty, &rdev->flags),
1528                                bdevname(rdev->bdev,b));
1529         }
1530         rcu_read_unlock();
1531 }
1532
1533 static void close_sync(struct r1conf *conf)
1534 {
1535         wait_barrier(conf, NULL);
1536         allow_barrier(conf, 0, 0);
1537
1538         mempool_destroy(conf->r1buf_pool);
1539         conf->r1buf_pool = NULL;
1540
1541         conf->next_resync = 0;
1542         conf->start_next_window = MaxSector;
1543 }
1544
1545 static int raid1_spare_active(struct mddev *mddev)
1546 {
1547         int i;
1548         struct r1conf *conf = mddev->private;
1549         int count = 0;
1550         unsigned long flags;
1551
1552         /*
1553          * Find all failed disks within the RAID1 configuration 
1554          * and mark them readable.
1555          * Called under mddev lock, so rcu protection not needed.
1556          */
1557         for (i = 0; i < conf->raid_disks; i++) {
1558                 struct md_rdev *rdev = conf->mirrors[i].rdev;
1559                 struct md_rdev *repl = conf->mirrors[conf->raid_disks + i].rdev;
1560                 if (repl
1561                     && repl->recovery_offset == MaxSector
1562                     && !test_bit(Faulty, &repl->flags)
1563                     && !test_and_set_bit(In_sync, &repl->flags)) {
1564                         /* replacement has just become active */
1565                         if (!rdev ||
1566                             !test_and_clear_bit(In_sync, &rdev->flags))
1567                                 count++;
1568                         if (rdev) {
1569                                 /* Replaced device not technically
1570                                  * faulty, but we need to be sure
1571                                  * it gets removed and never re-added
1572                                  */
1573                                 set_bit(Faulty, &rdev->flags);
1574                                 sysfs_notify_dirent_safe(
1575                                         rdev->sysfs_state);
1576                         }
1577                 }
1578                 if (rdev
1579                     && rdev->recovery_offset == MaxSector
1580                     && !test_bit(Faulty, &rdev->flags)
1581                     && !test_and_set_bit(In_sync, &rdev->flags)) {
1582                         count++;
1583                         sysfs_notify_dirent_safe(rdev->sysfs_state);
1584                 }
1585         }
1586         spin_lock_irqsave(&conf->device_lock, flags);
1587         mddev->degraded -= count;
1588         spin_unlock_irqrestore(&conf->device_lock, flags);
1589
1590         print_conf(conf);
1591         return count;
1592 }
1593
1594
1595 static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1596 {
1597         struct r1conf *conf = mddev->private;
1598         int err = -EEXIST;
1599         int mirror = 0;
1600         struct raid1_info *p;
1601         int first = 0;
1602         int last = conf->raid_disks - 1;
1603         struct request_queue *q = bdev_get_queue(rdev->bdev);
1604
1605         if (mddev->recovery_disabled == conf->recovery_disabled)
1606                 return -EBUSY;
1607
1608         if (rdev->raid_disk >= 0)
1609                 first = last = rdev->raid_disk;
1610
1611         if (q->merge_bvec_fn) {
1612                 set_bit(Unmerged, &rdev->flags);
1613                 mddev->merge_check_needed = 1;
1614         }
1615
1616         for (mirror = first; mirror <= last; mirror++) {
1617                 p = conf->mirrors+mirror;
1618                 if (!p->rdev) {
1619
1620                         if (mddev->gendisk)
1621                                 disk_stack_limits(mddev->gendisk, rdev->bdev,
1622                                                   rdev->data_offset << 9);
1623
1624                         p->head_position = 0;
1625                         rdev->raid_disk = mirror;
1626                         err = 0;
1627                         /* As all devices are equivalent, we don't need a full recovery
1628                          * if this was recently any drive of the array
1629                          */
1630                         if (rdev->saved_raid_disk < 0)
1631                                 conf->fullsync = 1;
1632                         rcu_assign_pointer(p->rdev, rdev);
1633                         break;
1634                 }
1635                 if (test_bit(WantReplacement, &p->rdev->flags) &&
1636                     p[conf->raid_disks].rdev == NULL) {
1637                         /* Add this device as a replacement */
1638                         clear_bit(In_sync, &rdev->flags);
1639                         set_bit(Replacement, &rdev->flags);
1640                         rdev->raid_disk = mirror;
1641                         err = 0;
1642                         conf->fullsync = 1;
1643                         rcu_assign_pointer(p[conf->raid_disks].rdev, rdev);
1644                         break;
1645                 }
1646         }
1647         if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
1648                 /* Some requests might not have seen this new
1649                  * merge_bvec_fn.  We must wait for them to complete
1650                  * before merging the device fully.
1651                  * First we make sure any code which has tested
1652                  * our function has submitted the request, then
1653                  * we wait for all outstanding requests to complete.
1654                  */
1655                 synchronize_sched();
1656                 freeze_array(conf, 0);
1657                 unfreeze_array(conf);
1658                 clear_bit(Unmerged, &rdev->flags);
1659         }
1660         md_integrity_add_rdev(rdev, mddev);
1661         if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
1662                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
1663         print_conf(conf);
1664         return err;
1665 }
1666
1667 static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1668 {
1669         struct r1conf *conf = mddev->private;
1670         int err = 0;
1671         int number = rdev->raid_disk;
1672         struct raid1_info *p = conf->mirrors + number;
1673
1674         if (rdev != p->rdev)
1675                 p = conf->mirrors + conf->raid_disks + number;
1676
1677         print_conf(conf);
1678         if (rdev == p->rdev) {
1679                 if (test_bit(In_sync, &rdev->flags) ||
1680                     atomic_read(&rdev->nr_pending)) {
1681                         err = -EBUSY;
1682                         goto abort;
1683                 }
1684                 /* Only remove non-faulty devices if recovery
1685                  * is not possible.
1686                  */
1687                 if (!test_bit(Faulty, &rdev->flags) &&
1688                     mddev->recovery_disabled != conf->recovery_disabled &&
1689                     mddev->degraded < conf->raid_disks) {
1690                         err = -EBUSY;
1691                         goto abort;
1692                 }
1693                 p->rdev = NULL;
1694                 synchronize_rcu();
1695                 if (atomic_read(&rdev->nr_pending)) {
1696                         /* lost the race, try later */
1697                         err = -EBUSY;
1698                         p->rdev = rdev;
1699                         goto abort;
1700                 } else if (conf->mirrors[conf->raid_disks + number].rdev) {
1701                         /* We just removed a device that is being replaced.
1702                          * Move down the replacement.  We drain all IO before
1703                          * doing this to avoid confusion.
1704                          */
1705                         struct md_rdev *repl =
1706                                 conf->mirrors[conf->raid_disks + number].rdev;
1707                         freeze_array(conf, 0);
1708                         clear_bit(Replacement, &repl->flags);
1709                         p->rdev = repl;
1710                         conf->mirrors[conf->raid_disks + number].rdev = NULL;
1711                         unfreeze_array(conf);
1712                         clear_bit(WantReplacement, &rdev->flags);
1713                 } else
1714                         clear_bit(WantReplacement, &rdev->flags);
1715                 err = md_integrity_register(mddev);
1716         }
1717 abort:
1718
1719         print_conf(conf);
1720         return err;
1721 }
1722
1723
1724 static void end_sync_read(struct bio *bio, int error)
1725 {
1726         struct r1bio *r1_bio = bio->bi_private;
1727
1728         update_head_pos(r1_bio->read_disk, r1_bio);
1729
1730         /*
1731          * we have read a block, now it needs to be re-written,
1732          * or re-read if the read failed.
1733          * We don't do much here, just schedule handling by raid1d
1734          */
1735         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1736                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1737
1738         if (atomic_dec_and_test(&r1_bio->remaining))
1739                 reschedule_retry(r1_bio);
1740 }
1741
1742 static void end_sync_write(struct bio *bio, int error)
1743 {
1744         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1745         struct r1bio *r1_bio = bio->bi_private;
1746         struct mddev *mddev = r1_bio->mddev;
1747         struct r1conf *conf = mddev->private;
1748         int mirror=0;
1749         sector_t first_bad;
1750         int bad_sectors;
1751
1752         mirror = find_bio_disk(r1_bio, bio);
1753
1754         if (!uptodate) {
1755                 sector_t sync_blocks = 0;
1756                 sector_t s = r1_bio->sector;
1757                 long sectors_to_go = r1_bio->sectors;
1758                 /* make sure these bits doesn't get cleared. */
1759                 do {
1760                         bitmap_end_sync(mddev->bitmap, s,
1761                                         &sync_blocks, 1);
1762                         s += sync_blocks;
1763                         sectors_to_go -= sync_blocks;
1764                 } while (sectors_to_go > 0);
1765                 set_bit(WriteErrorSeen,
1766                         &conf->mirrors[mirror].rdev->flags);
1767                 if (!test_and_set_bit(WantReplacement,
1768                                       &conf->mirrors[mirror].rdev->flags))
1769                         set_bit(MD_RECOVERY_NEEDED, &
1770                                 mddev->recovery);
1771                 set_bit(R1BIO_WriteError, &r1_bio->state);
1772         } else if (is_badblock(conf->mirrors[mirror].rdev,
1773                                r1_bio->sector,
1774                                r1_bio->sectors,
1775                                &first_bad, &bad_sectors) &&
1776                    !is_badblock(conf->mirrors[r1_bio->read_disk].rdev,
1777                                 r1_bio->sector,
1778                                 r1_bio->sectors,
1779                                 &first_bad, &bad_sectors)
1780                 )
1781                 set_bit(R1BIO_MadeGood, &r1_bio->state);
1782
1783         if (atomic_dec_and_test(&r1_bio->remaining)) {
1784                 int s = r1_bio->sectors;
1785                 if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
1786                     test_bit(R1BIO_WriteError, &r1_bio->state))
1787                         reschedule_retry(r1_bio);
1788                 else {
1789                         put_buf(r1_bio);
1790                         md_done_sync(mddev, s, uptodate);
1791                 }
1792         }
1793 }
1794
1795 static int r1_sync_page_io(struct md_rdev *rdev, sector_t sector,
1796                             int sectors, struct page *page, int rw)
1797 {
1798         if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
1799                 /* success */
1800                 return 1;
1801         if (rw == WRITE) {
1802                 set_bit(WriteErrorSeen, &rdev->flags);
1803                 if (!test_and_set_bit(WantReplacement,
1804                                       &rdev->flags))
1805                         set_bit(MD_RECOVERY_NEEDED, &
1806                                 rdev->mddev->recovery);
1807         }
1808         /* need to record an error - either for the block or the device */
1809         if (!rdev_set_badblocks(rdev, sector, sectors, 0))
1810                 md_error(rdev->mddev, rdev);
1811         return 0;
1812 }
1813
1814 static int fix_sync_read_error(struct r1bio *r1_bio)
1815 {
1816         /* Try some synchronous reads of other devices to get
1817          * good data, much like with normal read errors.  Only
1818          * read into the pages we already have so we don't
1819          * need to re-issue the read request.
1820          * We don't need to freeze the array, because being in an
1821          * active sync request, there is no normal IO, and
1822          * no overlapping syncs.
1823          * We don't need to check is_badblock() again as we
1824          * made sure that anything with a bad block in range
1825          * will have bi_end_io clear.
1826          */
1827         struct mddev *mddev = r1_bio->mddev;
1828         struct r1conf *conf = mddev->private;
1829         struct bio *bio = r1_bio->bios[r1_bio->read_disk];
1830         sector_t sect = r1_bio->sector;
1831         int sectors = r1_bio->sectors;
1832         int idx = 0;
1833
1834         while(sectors) {
1835                 int s = sectors;
1836                 int d = r1_bio->read_disk;
1837                 int success = 0;
1838                 struct md_rdev *rdev;
1839                 int start;
1840
1841                 if (s > (PAGE_SIZE>>9))
1842                         s = PAGE_SIZE >> 9;
1843                 do {
1844                         if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
1845                                 /* No rcu protection needed here devices
1846                                  * can only be removed when no resync is
1847                                  * active, and resync is currently active
1848                                  */
1849                                 rdev = conf->mirrors[d].rdev;
1850                                 if (sync_page_io(rdev, sect, s<<9,
1851                                                  bio->bi_io_vec[idx].bv_page,
1852                                                  READ, false)) {
1853                                         success = 1;
1854                                         break;
1855                                 }
1856                         }
1857                         d++;
1858                         if (d == conf->raid_disks * 2)
1859                                 d = 0;
1860                 } while (!success && d != r1_bio->read_disk);
1861
1862                 if (!success) {
1863                         char b[BDEVNAME_SIZE];
1864                         int abort = 0;
1865                         /* Cannot read from anywhere, this block is lost.
1866                          * Record a bad block on each device.  If that doesn't
1867                          * work just disable and interrupt the recovery.
1868                          * Don't fail devices as that won't really help.
1869                          */
1870                         printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O read error"
1871                                " for block %llu\n",
1872                                mdname(mddev),
1873                                bdevname(bio->bi_bdev, b),
1874                                (unsigned long long)r1_bio->sector);
1875                         for (d = 0; d < conf->raid_disks * 2; d++) {
1876                                 rdev = conf->mirrors[d].rdev;
1877                                 if (!rdev || test_bit(Faulty, &rdev->flags))
1878                                         continue;
1879                                 if (!rdev_set_badblocks(rdev, sect, s, 0))
1880                                         abort = 1;
1881                         }
1882                         if (abort) {
1883                                 conf->recovery_disabled =
1884                                         mddev->recovery_disabled;
1885                                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1886                                 md_done_sync(mddev, r1_bio->sectors, 0);
1887                                 put_buf(r1_bio);
1888                                 return 0;
1889                         }
1890                         /* Try next page */
1891                         sectors -= s;
1892                         sect += s;
1893                         idx++;
1894                         continue;
1895                 }
1896
1897                 start = d;
1898                 /* write it back and re-read */
1899                 while (d != r1_bio->read_disk) {
1900                         if (d == 0)
1901                                 d = conf->raid_disks * 2;
1902                         d--;
1903                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1904                                 continue;
1905                         rdev = conf->mirrors[d].rdev;
1906                         if (r1_sync_page_io(rdev, sect, s,
1907                                             bio->bi_io_vec[idx].bv_page,
1908                                             WRITE) == 0) {
1909                                 r1_bio->bios[d]->bi_end_io = NULL;
1910                                 rdev_dec_pending(rdev, mddev);
1911                         }
1912                 }
1913                 d = start;
1914                 while (d != r1_bio->read_disk) {
1915                         if (d == 0)
1916                                 d = conf->raid_disks * 2;
1917                         d--;
1918                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1919                                 continue;
1920                         rdev = conf->mirrors[d].rdev;
1921                         if (r1_sync_page_io(rdev, sect, s,
1922                                             bio->bi_io_vec[idx].bv_page,
1923                                             READ) != 0)
1924                                 atomic_add(s, &rdev->corrected_errors);
1925                 }
1926                 sectors -= s;
1927                 sect += s;
1928                 idx ++;
1929         }
1930         set_bit(R1BIO_Uptodate, &r1_bio->state);
1931         set_bit(BIO_UPTODATE, &bio->bi_flags);
1932         return 1;
1933 }
1934
1935 static int process_checks(struct r1bio *r1_bio)
1936 {
1937         /* We have read all readable devices.  If we haven't
1938          * got the block, then there is no hope left.
1939          * If we have, then we want to do a comparison
1940          * and skip the write if everything is the same.
1941          * If any blocks failed to read, then we need to
1942          * attempt an over-write
1943          */
1944         struct mddev *mddev = r1_bio->mddev;
1945         struct r1conf *conf = mddev->private;
1946         int primary;
1947         int i;
1948         int vcnt;
1949
1950         /* Fix variable parts of all bios */
1951         vcnt = (r1_bio->sectors + PAGE_SIZE / 512 - 1) >> (PAGE_SHIFT - 9);
1952         for (i = 0; i < conf->raid_disks * 2; i++) {
1953                 int j;
1954                 int size;
1955                 struct bio *b = r1_bio->bios[i];
1956                 if (b->bi_end_io != end_sync_read)
1957                         continue;
1958                 /* fixup the bio for reuse */
1959                 bio_reset(b);
1960                 b->bi_vcnt = vcnt;
1961                 b->bi_size = r1_bio->sectors << 9;
1962                 b->bi_sector = r1_bio->sector +
1963                         conf->mirrors[i].rdev->data_offset;
1964                 b->bi_bdev = conf->mirrors[i].rdev->bdev;
1965                 b->bi_end_io = end_sync_read;
1966                 b->bi_private = r1_bio;
1967
1968                 size = b->bi_size;
1969                 for (j = 0; j < vcnt ; j++) {
1970                         struct bio_vec *bi;
1971                         bi = &b->bi_io_vec[j];
1972                         bi->bv_offset = 0;
1973                         if (size > PAGE_SIZE)
1974                                 bi->bv_len = PAGE_SIZE;
1975                         else
1976                                 bi->bv_len = size;
1977                         size -= PAGE_SIZE;
1978                 }
1979         }
1980         for (primary = 0; primary < conf->raid_disks * 2; primary++)
1981                 if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
1982                     test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
1983                         r1_bio->bios[primary]->bi_end_io = NULL;
1984                         rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
1985                         break;
1986                 }
1987         r1_bio->read_disk = primary;
1988         for (i = 0; i < conf->raid_disks * 2; i++) {
1989                 int j;
1990                 struct bio *pbio = r1_bio->bios[primary];
1991                 struct bio *sbio = r1_bio->bios[i];
1992
1993                 if (sbio->bi_end_io != end_sync_read)
1994                         continue;
1995
1996                 if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
1997                         for (j = vcnt; j-- ; ) {
1998                                 struct page *p, *s;
1999                                 p = pbio->bi_io_vec[j].bv_page;
2000                                 s = sbio->bi_io_vec[j].bv_page;
2001                                 if (memcmp(page_address(p),
2002                                            page_address(s),
2003                                            sbio->bi_io_vec[j].bv_len))
2004                                         break;
2005                         }
2006                 } else
2007                         j = 0;
2008                 if (j >= 0)
2009                         atomic64_add(r1_bio->sectors, &mddev->resync_mismatches);
2010                 if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
2011                               && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
2012                         /* No need to write to this device. */
2013                         sbio->bi_end_io = NULL;
2014                         rdev_dec_pending(conf->mirrors[i].rdev, mddev);
2015                         continue;
2016                 }
2017
2018                 bio_copy_data(sbio, pbio);
2019         }
2020         return 0;
2021 }
2022
2023 static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
2024 {
2025         struct r1conf *conf = mddev->private;
2026         int i;
2027         int disks = conf->raid_disks * 2;
2028         struct bio *bio, *wbio;
2029
2030         bio = r1_bio->bios[r1_bio->read_disk];
2031
2032         if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
2033                 /* ouch - failed to read all of that. */
2034                 if (!fix_sync_read_error(r1_bio))
2035                         return;
2036
2037         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
2038                 if (process_checks(r1_bio) < 0)
2039                         return;
2040         /*
2041          * schedule writes
2042          */
2043         atomic_set(&r1_bio->remaining, 1);
2044         for (i = 0; i < disks ; i++) {
2045                 wbio = r1_bio->bios[i];
2046                 if (wbio->bi_end_io == NULL ||
2047                     (wbio->bi_end_io == end_sync_read &&
2048                      (i == r1_bio->read_disk ||
2049                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
2050                         continue;
2051
2052                 wbio->bi_rw = WRITE;
2053                 wbio->bi_end_io = end_sync_write;
2054                 atomic_inc(&r1_bio->remaining);
2055                 md_sync_acct(conf->mirrors[i].rdev->bdev, bio_sectors(wbio));
2056
2057                 generic_make_request(wbio);
2058         }
2059
2060         if (atomic_dec_and_test(&r1_bio->remaining)) {
2061                 /* if we're here, all write(s) have completed, so clean up */
2062                 int s = r1_bio->sectors;
2063                 if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2064                     test_bit(R1BIO_WriteError, &r1_bio->state))
2065                         reschedule_retry(r1_bio);
2066                 else {
2067                         put_buf(r1_bio);
2068                         md_done_sync(mddev, s, 1);
2069                 }
2070         }
2071 }
2072
2073 /*
2074  * This is a kernel thread which:
2075  *
2076  *      1.      Retries failed read operations on working mirrors.
2077  *      2.      Updates the raid superblock when problems encounter.
2078  *      3.      Performs writes following reads for array synchronising.
2079  */
2080
2081 static void fix_read_error(struct r1conf *conf, int read_disk,
2082                            sector_t sect, int sectors)
2083 {
2084         struct mddev *mddev = conf->mddev;
2085         while(sectors) {
2086                 int s = sectors;
2087                 int d = read_disk;
2088                 int success = 0;
2089                 int start;
2090                 struct md_rdev *rdev;
2091
2092                 if (s > (PAGE_SIZE>>9))
2093                         s = PAGE_SIZE >> 9;
2094
2095                 do {
2096                         /* Note: no rcu protection needed here
2097                          * as this is synchronous in the raid1d thread
2098                          * which is the thread that might remove
2099                          * a device.  If raid1d ever becomes multi-threaded....
2100                          */
2101                         sector_t first_bad;
2102                         int bad_sectors;
2103
2104                         rdev = conf->mirrors[d].rdev;
2105                         if (rdev &&
2106                             (test_bit(In_sync, &rdev->flags) ||
2107                              (!test_bit(Faulty, &rdev->flags) &&
2108                               rdev->recovery_offset >= sect + s)) &&
2109                             is_badblock(rdev, sect, s,
2110                                         &first_bad, &bad_sectors) == 0 &&
2111                             sync_page_io(rdev, sect, s<<9,
2112                                          conf->tmppage, READ, false))
2113                                 success = 1;
2114                         else {
2115                                 d++;
2116                                 if (d == conf->raid_disks * 2)
2117                                         d = 0;
2118                         }
2119                 } while (!success && d != read_disk);
2120
2121                 if (!success) {
2122                         /* Cannot read from anywhere - mark it bad */
2123                         struct md_rdev *rdev = conf->mirrors[read_disk].rdev;
2124                         if (!rdev_set_badblocks(rdev, sect, s, 0))
2125                                 md_error(mddev, rdev);
2126                         break;
2127                 }
2128                 /* write it back and re-read */
2129                 start = d;
2130                 while (d != read_disk) {
2131                         if (d==0)
2132                                 d = conf->raid_disks * 2;
2133                         d--;
2134                         rdev = conf->mirrors[d].rdev;
2135                         if (rdev &&
2136                             test_bit(In_sync, &rdev->flags))
2137                                 r1_sync_page_io(rdev, sect, s,
2138                                                 conf->tmppage, WRITE);
2139                 }
2140                 d = start;
2141                 while (d != read_disk) {
2142                         char b[BDEVNAME_SIZE];
2143                         if (d==0)
2144                                 d = conf->raid_disks * 2;
2145                         d--;
2146                         rdev = conf->mirrors[d].rdev;
2147                         if (rdev &&
2148                             test_bit(In_sync, &rdev->flags)) {
2149                                 if (r1_sync_page_io(rdev, sect, s,
2150                                                     conf->tmppage, READ)) {
2151                                         atomic_add(s, &rdev->corrected_errors);
2152                                         printk(KERN_INFO
2153                                                "md/raid1:%s: read error corrected "
2154                                                "(%d sectors at %llu on %s)\n",
2155                                                mdname(mddev), s,
2156                                                (unsigned long long)(sect +
2157                                                    rdev->data_offset),
2158                                                bdevname(rdev->bdev, b));
2159                                 }
2160                         }
2161                 }
2162                 sectors -= s;
2163                 sect += s;
2164         }
2165 }
2166
2167 static int narrow_write_error(struct r1bio *r1_bio, int i)
2168 {
2169         struct mddev *mddev = r1_bio->mddev;
2170         struct r1conf *conf = mddev->private;
2171         struct md_rdev *rdev = conf->mirrors[i].rdev;
2172
2173         /* bio has the data to be written to device 'i' where
2174          * we just recently had a write error.
2175          * We repeatedly clone the bio and trim down to one block,
2176          * then try the write.  Where the write fails we record
2177          * a bad block.
2178          * It is conceivable that the bio doesn't exactly align with
2179          * blocks.  We must handle this somehow.
2180          *
2181          * We currently own a reference on the rdev.
2182          */
2183
2184         int block_sectors;
2185         sector_t sector;
2186         int sectors;
2187         int sect_to_write = r1_bio->sectors;
2188         int ok = 1;
2189
2190         if (rdev->badblocks.shift < 0)
2191                 return 0;
2192
2193         block_sectors = 1 << rdev->badblocks.shift;
2194         sector = r1_bio->sector;
2195         sectors = ((sector + block_sectors)
2196                    & ~(sector_t)(block_sectors - 1))
2197                 - sector;
2198
2199         while (sect_to_write) {
2200                 struct bio *wbio;
2201                 if (sectors > sect_to_write)
2202                         sectors = sect_to_write;
2203                 /* Write at 'sector' for 'sectors'*/
2204
2205                 if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
2206                         unsigned vcnt = r1_bio->behind_page_count;
2207                         struct bio_vec *vec = r1_bio->behind_bvecs;
2208
2209                         while (!vec->bv_page) {
2210                                 vec++;
2211                                 vcnt--;
2212                         }
2213
2214                         wbio = bio_alloc_mddev(GFP_NOIO, vcnt, mddev);
2215                         memcpy(wbio->bi_io_vec, vec, vcnt * sizeof(struct bio_vec));
2216
2217                         wbio->bi_vcnt = vcnt;
2218                 } else {
2219                         wbio = bio_clone_mddev(r1_bio->master_bio, GFP_NOIO, mddev);
2220                 }
2221
2222                 wbio->bi_rw = WRITE;
2223                 wbio->bi_sector = r1_bio->sector;
2224                 wbio->bi_size = r1_bio->sectors << 9;
2225
2226                 bio_trim(wbio, sector - r1_bio->sector, sectors);
2227                 wbio->bi_sector += rdev->data_offset;
2228                 wbio->bi_bdev = rdev->bdev;
2229                 if (submit_bio_wait(WRITE, wbio) == 0)
2230                         /* failure! */
2231                         ok = rdev_set_badblocks(rdev, sector,
2232                                                 sectors, 0)
2233                                 && ok;
2234
2235                 bio_put(wbio);
2236                 sect_to_write -= sectors;
2237                 sector += sectors;
2238                 sectors = block_sectors;
2239         }
2240         return ok;
2241 }
2242
2243 static void handle_sync_write_finished(struct r1conf *conf, struct r1bio *r1_bio)
2244 {
2245         int m;
2246         int s = r1_bio->sectors;
2247         for (m = 0; m < conf->raid_disks * 2 ; m++) {
2248                 struct md_rdev *rdev = conf->mirrors[m].rdev;
2249                 struct bio *bio = r1_bio->bios[m];
2250                 if (bio->bi_end_io == NULL)
2251                         continue;
2252                 if (test_bit(BIO_UPTODATE, &bio->bi_flags) &&
2253                     test_bit(R1BIO_MadeGood, &r1_bio->state)) {
2254                         rdev_clear_badblocks(rdev, r1_bio->sector, s, 0);
2255                 }
2256                 if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
2257                     test_bit(R1BIO_WriteError, &r1_bio->state)) {
2258                         if (!rdev_set_badblocks(rdev, r1_bio->sector, s, 0))
2259                                 md_error(conf->mddev, rdev);
2260                 }
2261         }
2262         put_buf(r1_bio);
2263         md_done_sync(conf->mddev, s, 1);
2264 }
2265
2266 static void handle_write_finished(struct r1conf *conf, struct r1bio *r1_bio)
2267 {
2268         int m;
2269         for (m = 0; m < conf->raid_disks * 2 ; m++)
2270                 if (r1_bio->bios[m] == IO_MADE_GOOD) {
2271                         struct md_rdev *rdev = conf->mirrors[m].rdev;
2272                         rdev_clear_badblocks(rdev,
2273                                              r1_bio->sector,
2274                                              r1_bio->sectors, 0);
2275                         rdev_dec_pending(rdev, conf->mddev);
2276                 } else if (r1_bio->bios[m] != NULL) {
2277                         /* This drive got a write error.  We need to
2278                          * narrow down and record precise write
2279                          * errors.
2280                          */
2281                         if (!narrow_write_error(r1_bio, m)) {
2282                                 md_error(conf->mddev,
2283                                          conf->mirrors[m].rdev);
2284                                 /* an I/O failed, we can't clear the bitmap */
2285                                 set_bit(R1BIO_Degraded, &r1_bio->state);
2286                         }
2287                         rdev_dec_pending(conf->mirrors[m].rdev,
2288                                          conf->mddev);
2289                 }
2290         if (test_bit(R1BIO_WriteError, &r1_bio->state))
2291                 close_write(r1_bio);
2292         raid_end_bio_io(r1_bio);
2293 }
2294
2295 static void handle_read_error(struct r1conf *conf, struct r1bio *r1_bio)
2296 {
2297         int disk;
2298         int max_sectors;
2299         struct mddev *mddev = conf->mddev;
2300         struct bio *bio;
2301         char b[BDEVNAME_SIZE];
2302         struct md_rdev *rdev;
2303
2304         clear_bit(R1BIO_ReadError, &r1_bio->state);
2305         /* we got a read error. Maybe the drive is bad.  Maybe just
2306          * the block and we can fix it.
2307          * We freeze all other IO, and try reading the block from
2308          * other devices.  When we find one, we re-write
2309          * and check it that fixes the read error.
2310          * This is all done synchronously while the array is
2311          * frozen
2312          */
2313         if (mddev->ro == 0) {
2314                 freeze_array(conf, 1);
2315                 fix_read_error(conf, r1_bio->read_disk,
2316                                r1_bio->sector, r1_bio->sectors);
2317                 unfreeze_array(conf);
2318         } else
2319                 md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
2320         rdev_dec_pending(conf->mirrors[r1_bio->read_disk].rdev, conf->mddev);
2321
2322         bio = r1_bio->bios[r1_bio->read_disk];
2323         bdevname(bio->bi_bdev, b);
2324 read_more:
2325         disk = read_balance(conf, r1_bio, &max_sectors);
2326         if (disk == -1) {
2327                 printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O"
2328                        " read error for block %llu\n",
2329                        mdname(mddev), b, (unsigned long long)r1_bio->sector);
2330                 raid_end_bio_io(r1_bio);
2331         } else {
2332                 const unsigned long do_sync
2333                         = r1_bio->master_bio->bi_rw & REQ_SYNC;
2334                 if (bio) {
2335                         r1_bio->bios[r1_bio->read_disk] =
2336                                 mddev->ro ? IO_BLOCKED : NULL;
2337                         bio_put(bio);
2338                 }
2339                 r1_bio->read_disk = disk;
2340                 bio = bio_clone_mddev(r1_bio->master_bio, GFP_NOIO, mddev);
2341                 bio_trim(bio, r1_bio->sector - bio->bi_sector, max_sectors);
2342                 r1_bio->bios[r1_bio->read_disk] = bio;
2343                 rdev = conf->mirrors[disk].rdev;
2344                 printk_ratelimited(KERN_ERR
2345                                    "md/raid1:%s: redirecting sector %llu"
2346                                    " to other mirror: %s\n",
2347                                    mdname(mddev),
2348                                    (unsigned long long)r1_bio->sector,
2349                                    bdevname(rdev->bdev, b));
2350                 bio->bi_sector = r1_bio->sector + rdev->data_offset;
2351                 bio->bi_bdev = rdev->bdev;
2352                 bio->bi_end_io = raid1_end_read_request;
2353                 bio->bi_rw = READ | do_sync;
2354                 bio->bi_private = r1_bio;
2355                 if (max_sectors < r1_bio->sectors) {
2356                         /* Drat - have to split this up more */
2357                         struct bio *mbio = r1_bio->master_bio;
2358                         int sectors_handled = (r1_bio->sector + max_sectors
2359                                                - mbio->bi_sector);
2360                         r1_bio->sectors = max_sectors;
2361                         spin_lock_irq(&conf->device_lock);
2362                         if (mbio->bi_phys_segments == 0)
2363                                 mbio->bi_phys_segments = 2;
2364                         else
2365                                 mbio->bi_phys_segments++;
2366                         spin_unlock_irq(&conf->device_lock);
2367                         generic_make_request(bio);
2368                         bio = NULL;
2369
2370                         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
2371
2372                         r1_bio->master_bio = mbio;
2373                         r1_bio->sectors = bio_sectors(mbio) - sectors_handled;
2374                         r1_bio->state = 0;
2375                         set_bit(R1BIO_ReadError, &r1_bio->state);
2376                         r1_bio->mddev = mddev;
2377                         r1_bio->sector = mbio->bi_sector + sectors_handled;
2378
2379                         goto read_more;
2380                 } else
2381                         generic_make_request(bio);
2382         }
2383 }
2384
2385 static void raid1d(struct md_thread *thread)
2386 {
2387         struct mddev *mddev = thread->mddev;
2388         struct r1bio *r1_bio;
2389         unsigned long flags;
2390         struct r1conf *conf = mddev->private;
2391         struct list_head *head = &conf->retry_list;
2392         struct blk_plug plug;
2393
2394         md_check_recovery(mddev);
2395
2396         blk_start_plug(&plug);
2397         for (;;) {
2398
2399                 flush_pending_writes(conf);
2400
2401                 spin_lock_irqsave(&conf->device_lock, flags);
2402                 if (list_empty(head)) {
2403                         spin_unlock_irqrestore(&conf->device_lock, flags);
2404                         break;
2405                 }
2406                 r1_bio = list_entry(head->prev, struct r1bio, retry_list);
2407                 list_del(head->prev);
2408                 conf->nr_queued--;
2409                 spin_unlock_irqrestore(&conf->device_lock, flags);
2410
2411                 mddev = r1_bio->mddev;
2412                 conf = mddev->private;
2413                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
2414                         if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2415                             test_bit(R1BIO_WriteError, &r1_bio->state))
2416                                 handle_sync_write_finished(conf, r1_bio);
2417                         else
2418                                 sync_request_write(mddev, r1_bio);
2419                 } else if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2420                            test_bit(R1BIO_WriteError, &r1_bio->state))
2421                         handle_write_finished(conf, r1_bio);
2422                 else if (test_bit(R1BIO_ReadError, &r1_bio->state))
2423                         handle_read_error(conf, r1_bio);
2424                 else
2425                         /* just a partial read to be scheduled from separate
2426                          * context
2427                          */
2428                         generic_make_request(r1_bio->bios[r1_bio->read_disk]);
2429
2430                 cond_resched();
2431                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2432                         md_check_recovery(mddev);
2433         }
2434         blk_finish_plug(&plug);
2435 }
2436
2437
2438 static int init_resync(struct r1conf *conf)
2439 {
2440         int buffs;
2441
2442         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2443         BUG_ON(conf->r1buf_pool);
2444         conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
2445                                           conf->poolinfo);
2446         if (!conf->r1buf_pool)
2447                 return -ENOMEM;
2448         conf->next_resync = 0;
2449         return 0;
2450 }
2451
2452 /*
2453  * perform a "sync" on one "block"
2454  *
2455  * We need to make sure that no normal I/O request - particularly write
2456  * requests - conflict with active sync requests.
2457  *
2458  * This is achieved by tracking pending requests and a 'barrier' concept
2459  * that can be installed to exclude normal IO requests.
2460  */
2461
2462 static sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
2463 {
2464         struct r1conf *conf = mddev->private;
2465         struct r1bio *r1_bio;
2466         struct bio *bio;
2467         sector_t max_sector, nr_sectors;
2468         int disk = -1;
2469         int i;
2470         int wonly = -1;
2471         int write_targets = 0, read_targets = 0;
2472         sector_t sync_blocks;
2473         int still_degraded = 0;
2474         int good_sectors = RESYNC_SECTORS;
2475         int min_bad = 0; /* number of sectors that are bad in all devices */
2476
2477         if (!conf->r1buf_pool)
2478                 if (init_resync(conf))
2479                         return 0;
2480
2481         max_sector = mddev->dev_sectors;
2482         if (sector_nr >= max_sector) {
2483                 /* If we aborted, we need to abort the
2484                  * sync on the 'current' bitmap chunk (there will
2485                  * only be one in raid1 resync.
2486                  * We can find the current addess in mddev->curr_resync
2487                  */
2488                 if (mddev->curr_resync < max_sector) /* aborted */
2489                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2490                                                 &sync_blocks, 1);
2491                 else /* completed sync */
2492                         conf->fullsync = 0;
2493
2494                 bitmap_close_sync(mddev->bitmap);
2495                 close_sync(conf);
2496                 return 0;
2497         }
2498
2499         if (mddev->bitmap == NULL &&
2500             mddev->recovery_cp == MaxSector &&
2501             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
2502             conf->fullsync == 0) {
2503                 *skipped = 1;
2504                 return max_sector - sector_nr;
2505         }
2506         /* before building a request, check if we can skip these blocks..
2507          * This call the bitmap_start_sync doesn't actually record anything
2508          */
2509         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
2510             !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
2511                 /* We can skip this block, and probably several more */
2512                 *skipped = 1;
2513                 return sync_blocks;
2514         }
2515         /*
2516          * If there is non-resync activity waiting for a turn,
2517          * and resync is going fast enough,
2518          * then let it though before starting on this new sync request.
2519          */
2520         if (!go_faster && conf->nr_waiting)
2521                 msleep_interruptible(1000);
2522
2523         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
2524         r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
2525         raise_barrier(conf);
2526
2527         conf->next_resync = sector_nr;
2528
2529         rcu_read_lock();
2530         /*
2531          * If we get a correctably read error during resync or recovery,
2532          * we might want to read from a different device.  So we
2533          * flag all drives that could conceivably be read from for READ,
2534          * and any others (which will be non-In_sync devices) for WRITE.
2535          * If a read fails, we try reading from something else for which READ
2536          * is OK.
2537          */
2538
2539         r1_bio->mddev = mddev;
2540         r1_bio->sector = sector_nr;
2541         r1_bio->state = 0;
2542         set_bit(R1BIO_IsSync, &r1_bio->state);
2543
2544         for (i = 0; i < conf->raid_disks * 2; i++) {
2545                 struct md_rdev *rdev;
2546                 bio = r1_bio->bios[i];
2547                 bio_reset(bio);
2548
2549                 rdev = rcu_dereference(conf->mirrors[i].rdev);
2550                 if (rdev == NULL ||
2551                     test_bit(Faulty, &rdev->flags)) {
2552                         if (i < conf->raid_disks)
2553                                 still_degraded = 1;
2554                 } else if (!test_bit(In_sync, &rdev->flags)) {
2555                         bio->bi_rw = WRITE;
2556                         bio->bi_end_io = end_sync_write;
2557                         write_targets ++;
2558                 } else {
2559                         /* may need to read from here */
2560                         sector_t first_bad = MaxSector;
2561                         int bad_sectors;
2562
2563                         if (is_badblock(rdev, sector_nr, good_sectors,
2564                                         &first_bad, &bad_sectors)) {
2565                                 if (first_bad > sector_nr)
2566                                         good_sectors = first_bad - sector_nr;
2567                                 else {
2568                                         bad_sectors -= (sector_nr - first_bad);
2569                                         if (min_bad == 0 ||
2570                                             min_bad > bad_sectors)
2571                                                 min_bad = bad_sectors;
2572                                 }
2573                         }
2574                         if (sector_nr < first_bad) {
2575                                 if (test_bit(WriteMostly, &rdev->flags)) {
2576                                         if (wonly < 0)
2577                                                 wonly = i;
2578                                 } else {
2579                                         if (disk < 0)
2580                                                 disk = i;
2581                                 }
2582                                 bio->bi_rw = READ;
2583                                 bio->bi_end_io = end_sync_read;
2584                                 read_targets++;
2585                         } else if (!test_bit(WriteErrorSeen, &rdev->flags) &&
2586                                 test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
2587                                 !test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
2588                                 /*
2589                                  * The device is suitable for reading (InSync),
2590                                  * but has bad block(s) here. Let's try to correct them,
2591                                  * if we are doing resync or repair. Otherwise, leave
2592                                  * this device alone for this sync request.
2593                                  */
2594                                 bio->bi_rw = WRITE;
2595                                 bio->bi_end_io = end_sync_write;
2596                                 write_targets++;
2597                         }
2598                 }
2599                 if (bio->bi_end_io) {
2600                         atomic_inc(&rdev->nr_pending);
2601                         bio->bi_sector = sector_nr + rdev->data_offset;
2602                         bio->bi_bdev = rdev->bdev;
2603                         bio->bi_private = r1_bio;
2604                 }
2605         }
2606         rcu_read_unlock();
2607         if (disk < 0)
2608                 disk = wonly;
2609         r1_bio->read_disk = disk;
2610
2611         if (read_targets == 0 && min_bad > 0) {
2612                 /* These sectors are bad on all InSync devices, so we
2613                  * need to mark them bad on all write targets
2614                  */
2615                 int ok = 1;
2616                 for (i = 0 ; i < conf->raid_disks * 2 ; i++)
2617                         if (r1_bio->bios[i]->bi_end_io == end_sync_write) {
2618                                 struct md_rdev *rdev = conf->mirrors[i].rdev;
2619                                 ok = rdev_set_badblocks(rdev, sector_nr,
2620                                                         min_bad, 0
2621                                         ) && ok;
2622                         }
2623                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
2624                 *skipped = 1;
2625                 put_buf(r1_bio);
2626
2627                 if (!ok) {
2628                         /* Cannot record the badblocks, so need to
2629                          * abort the resync.
2630                          * If there are multiple read targets, could just
2631                          * fail the really bad ones ???
2632                          */
2633                         conf->recovery_disabled = mddev->recovery_disabled;
2634                         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2635                         return 0;
2636                 } else
2637                         return min_bad;
2638
2639         }
2640         if (min_bad > 0 && min_bad < good_sectors) {
2641                 /* only resync enough to reach the next bad->good
2642                  * transition */
2643                 good_sectors = min_bad;
2644         }
2645
2646         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
2647                 /* extra read targets are also write targets */
2648                 write_targets += read_targets-1;
2649
2650         if (write_targets == 0 || read_targets == 0) {
2651                 /* There is nowhere to write, so all non-sync
2652                  * drives must be failed - so we are finished
2653                  */
2654                 sector_t rv;
2655                 if (min_bad > 0)
2656                         max_sector = sector_nr + min_bad;
2657                 rv = max_sector - sector_nr;
2658                 *skipped = 1;
2659                 put_buf(r1_bio);
2660                 return rv;
2661         }
2662
2663         if (max_sector > mddev->resync_max)
2664                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
2665         if (max_sector > sector_nr + good_sectors)
2666                 max_sector = sector_nr + good_sectors;
2667         nr_sectors = 0;
2668         sync_blocks = 0;
2669         do {
2670                 struct page *page;
2671                 int len = PAGE_SIZE;
2672                 if (sector_nr + (len>>9) > max_sector)
2673                         len = (max_sector - sector_nr) << 9;
2674                 if (len == 0)
2675                         break;
2676                 if (sync_blocks == 0) {
2677                         if (!bitmap_start_sync(mddev->bitmap, sector_nr,
2678                                                &sync_blocks, still_degraded) &&
2679                             !conf->fullsync &&
2680                             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
2681                                 break;
2682                         BUG_ON(sync_blocks < (PAGE_SIZE>>9));
2683                         if ((len >> 9) > sync_blocks)
2684                                 len = sync_blocks<<9;
2685                 }
2686
2687                 for (i = 0 ; i < conf->raid_disks * 2; i++) {
2688                         bio = r1_bio->bios[i];
2689                         if (bio->bi_end_io) {
2690                                 page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
2691                                 if (bio_add_page(bio, page, len, 0) == 0) {
2692                                         /* stop here */
2693                                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
2694                                         while (i > 0) {
2695                                                 i--;
2696                                                 bio = r1_bio->bios[i];
2697                                                 if (bio->bi_end_io==NULL)
2698                                                         continue;
2699                                                 /* remove last page from this bio */
2700                                                 bio->bi_vcnt--;
2701                                                 bio->bi_size -= len;
2702                                                 bio->bi_flags &= ~(1<< BIO_SEG_VALID);
2703                                         }
2704                                         goto bio_full;
2705                                 }
2706                         }
2707                 }
2708                 nr_sectors += len>>9;
2709                 sector_nr += len>>9;
2710                 sync_blocks -= (len>>9);
2711         } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
2712  bio_full:
2713         r1_bio->sectors = nr_sectors;
2714
2715         /* For a user-requested sync, we read all readable devices and do a
2716          * compare
2717          */
2718         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
2719                 atomic_set(&r1_bio->remaining, read_targets);
2720                 for (i = 0; i < conf->raid_disks * 2 && read_targets; i++) {
2721                         bio = r1_bio->bios[i];
2722                         if (bio->bi_end_io == end_sync_read) {
2723                                 read_targets--;
2724                                 md_sync_acct(bio->bi_bdev, nr_sectors);
2725                                 generic_make_request(bio);
2726                         }
2727                 }
2728         } else {
2729                 atomic_set(&r1_bio->remaining, 1);
2730                 bio = r1_bio->bios[r1_bio->read_disk];
2731                 md_sync_acct(bio->bi_bdev, nr_sectors);
2732                 generic_make_request(bio);
2733
2734         }
2735         return nr_sectors;
2736 }
2737
2738 static sector_t raid1_size(struct mddev *mddev, sector_t sectors, int raid_disks)
2739 {
2740         if (sectors)
2741                 return sectors;
2742
2743         return mddev->dev_sectors;
2744 }
2745
2746 static struct r1conf *setup_conf(struct mddev *mddev)
2747 {
2748         struct r1conf *conf;
2749         int i;
2750         struct raid1_info *disk;
2751         struct md_rdev *rdev;
2752         int err = -ENOMEM;
2753
2754         conf = kzalloc(sizeof(struct r1conf), GFP_KERNEL);
2755         if (!conf)
2756                 goto abort;
2757
2758         conf->mirrors = kzalloc(sizeof(struct raid1_info)
2759                                 * mddev->raid_disks * 2,
2760                                  GFP_KERNEL);
2761         if (!conf->mirrors)
2762                 goto abort;
2763
2764         conf->tmppage = alloc_page(GFP_KERNEL);
2765         if (!conf->tmppage)
2766                 goto abort;
2767
2768         conf->poolinfo = kzalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
2769         if (!conf->poolinfo)
2770                 goto abort;
2771         conf->poolinfo->raid_disks = mddev->raid_disks * 2;
2772         conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2773                                           r1bio_pool_free,
2774                                           conf->poolinfo);
2775         if (!conf->r1bio_pool)
2776                 goto abort;
2777
2778         conf->poolinfo->mddev = mddev;
2779
2780         err = -EINVAL;
2781         spin_lock_init(&conf->device_lock);
2782         rdev_for_each(rdev, mddev) {
2783                 struct request_queue *q;
2784                 int disk_idx = rdev->raid_disk;
2785                 if (disk_idx >= mddev->raid_disks
2786                     || disk_idx < 0)
2787                         continue;
2788                 if (test_bit(Replacement, &rdev->flags))
2789                         disk = conf->mirrors + mddev->raid_disks + disk_idx;
2790                 else
2791                         disk = conf->mirrors + disk_idx;
2792
2793                 if (disk->rdev)
2794                         goto abort;
2795                 disk->rdev = rdev;
2796                 q = bdev_get_queue(rdev->bdev);
2797                 if (q->merge_bvec_fn)
2798                         mddev->merge_check_needed = 1;
2799
2800                 disk->head_position = 0;
2801                 disk->seq_start = MaxSector;
2802         }
2803         conf->raid_disks = mddev->raid_disks;
2804         conf->mddev = mddev;
2805         INIT_LIST_HEAD(&conf->retry_list);
2806
2807         spin_lock_init(&conf->resync_lock);
2808         init_waitqueue_head(&conf->wait_barrier);
2809
2810         bio_list_init(&conf->pending_bio_list);
2811         conf->pending_count = 0;
2812         conf->recovery_disabled = mddev->recovery_disabled - 1;
2813
2814         conf->start_next_window = MaxSector;
2815         conf->current_window_requests = conf->next_window_requests = 0;
2816
2817         err = -EIO;
2818         for (i = 0; i < conf->raid_disks * 2; i++) {
2819
2820                 disk = conf->mirrors + i;
2821
2822                 if (i < conf->raid_disks &&
2823                     disk[conf->raid_disks].rdev) {
2824                         /* This slot has a replacement. */
2825                         if (!disk->rdev) {
2826                                 /* No original, just make the replacement
2827                                  * a recovering spare
2828                                  */
2829                                 disk->rdev =
2830                                         disk[conf->raid_disks].rdev;
2831                                 disk[conf->raid_disks].rdev = NULL;
2832                         } else if (!test_bit(In_sync, &disk->rdev->flags))
2833                                 /* Original is not in_sync - bad */
2834                                 goto abort;
2835                 }
2836
2837                 if (!disk->rdev ||
2838                     !test_bit(In_sync, &disk->rdev->flags)) {
2839                         disk->head_position = 0;
2840                         if (disk->rdev &&
2841                             (disk->rdev->saved_raid_disk < 0))
2842                                 conf->fullsync = 1;
2843                 }
2844         }
2845
2846         err = -ENOMEM;
2847         conf->thread = md_register_thread(raid1d, mddev, "raid1");
2848         if (!conf->thread) {
2849                 printk(KERN_ERR
2850                        "md/raid1:%s: couldn't allocate thread\n",
2851                        mdname(mddev));
2852                 goto abort;
2853         }
2854
2855         return conf;
2856
2857  abort:
2858         if (conf) {
2859                 if (conf->r1bio_pool)
2860                         mempool_destroy(conf->r1bio_pool);
2861                 kfree(conf->mirrors);
2862                 safe_put_page(conf->tmppage);
2863                 kfree(conf->poolinfo);
2864                 kfree(conf);
2865         }
2866         return ERR_PTR(err);
2867 }
2868
2869 static int stop(struct mddev *mddev);
2870 static int run(struct mddev *mddev)
2871 {
2872         struct r1conf *conf;
2873         int i;
2874         struct md_rdev *rdev;
2875         int ret;
2876         bool discard_supported = false;
2877
2878         if (mddev->level != 1) {
2879                 printk(KERN_ERR "md/raid1:%s: raid level not set to mirroring (%d)\n",
2880                        mdname(mddev), mddev->level);
2881                 return -EIO;
2882         }
2883         if (mddev->reshape_position != MaxSector) {
2884                 printk(KERN_ERR "md/raid1:%s: reshape_position set but not supported\n",
2885                        mdname(mddev));
2886                 return -EIO;
2887         }
2888         /*
2889          * copy the already verified devices into our private RAID1
2890          * bookkeeping area. [whatever we allocate in run(),
2891          * should be freed in stop()]
2892          */
2893         if (mddev->private == NULL)
2894                 conf = setup_conf(mddev);
2895         else
2896                 conf = mddev->private;
2897
2898         if (IS_ERR(conf))
2899                 return PTR_ERR(conf);
2900
2901         if (mddev->queue)
2902                 blk_queue_max_write_same_sectors(mddev->queue, 0);
2903
2904         rdev_for_each(rdev, mddev) {
2905                 if (!mddev->gendisk)
2906                         continue;
2907                 disk_stack_limits(mddev->gendisk, rdev->bdev,
2908                                   rdev->data_offset << 9);
2909                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
2910                         discard_supported = true;
2911         }
2912
2913         mddev->degraded = 0;
2914         for (i=0; i < conf->raid_disks; i++)
2915                 if (conf->mirrors[i].rdev == NULL ||
2916                     !test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
2917                     test_bit(Faulty, &conf->mirrors[i].rdev->flags))
2918                         mddev->degraded++;
2919
2920         if (conf->raid_disks - mddev->degraded == 1)
2921                 mddev->recovery_cp = MaxSector;
2922
2923         if (mddev->recovery_cp != MaxSector)
2924                 printk(KERN_NOTICE "md/raid1:%s: not clean"
2925                        " -- starting background reconstruction\n",
2926                        mdname(mddev));
2927         printk(KERN_INFO 
2928                 "md/raid1:%s: active with %d out of %d mirrors\n",
2929                 mdname(mddev), mddev->raid_disks - mddev->degraded, 
2930                 mddev->raid_disks);
2931
2932         /*
2933          * Ok, everything is just fine now
2934          */
2935         mddev->thread = conf->thread;
2936         conf->thread = NULL;
2937         mddev->private = conf;
2938
2939         md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
2940
2941         if (mddev->queue) {
2942                 mddev->queue->backing_dev_info.congested_fn = raid1_congested;
2943                 mddev->queue->backing_dev_info.congested_data = mddev;
2944                 blk_queue_merge_bvec(mddev->queue, raid1_mergeable_bvec);
2945
2946                 if (discard_supported)
2947                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
2948                                                 mddev->queue);
2949                 else
2950                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
2951                                                   mddev->queue);
2952         }
2953
2954         ret =  md_integrity_register(mddev);
2955         if (ret)
2956                 stop(mddev);
2957         return ret;
2958 }
2959
2960 static int stop(struct mddev *mddev)
2961 {
2962         struct r1conf *conf = mddev->private;
2963         struct bitmap *bitmap = mddev->bitmap;
2964
2965         /* wait for behind writes to complete */
2966         if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
2967                 printk(KERN_INFO "md/raid1:%s: behind writes in progress - waiting to stop.\n",
2968                        mdname(mddev));
2969                 /* need to kick something here to make sure I/O goes? */
2970                 wait_event(bitmap->behind_wait,
2971                            atomic_read(&bitmap->behind_writes) == 0);
2972         }
2973
2974         freeze_array(conf, 0);
2975         unfreeze_array(conf);
2976
2977         md_unregister_thread(&mddev->thread);
2978         if (conf->r1bio_pool)
2979                 mempool_destroy(conf->r1bio_pool);
2980         kfree(conf->mirrors);
2981         safe_put_page(conf->tmppage);
2982         kfree(conf->poolinfo);
2983         kfree(conf);
2984         mddev->private = NULL;
2985         return 0;
2986 }
2987
2988 static int raid1_resize(struct mddev *mddev, sector_t sectors)
2989 {
2990         /* no resync is happening, and there is enough space
2991          * on all devices, so we can resize.
2992          * We need to make sure resync covers any new space.
2993          * If the array is shrinking we should possibly wait until
2994          * any io in the removed space completes, but it hardly seems
2995          * worth it.
2996          */
2997         sector_t newsize = raid1_size(mddev, sectors, 0);
2998         if (mddev->external_size &&
2999             mddev->array_sectors > newsize)
3000                 return -EINVAL;
3001         if (mddev->bitmap) {
3002                 int ret = bitmap_resize(mddev->bitmap, newsize, 0, 0);
3003                 if (ret)
3004                         return ret;
3005         }
3006         md_set_array_sectors(mddev, newsize);
3007         set_capacity(mddev->gendisk, mddev->array_sectors);
3008         revalidate_disk(mddev->gendisk);
3009         if (sectors > mddev->dev_sectors &&
3010             mddev->recovery_cp > mddev->dev_sectors) {
3011                 mddev->recovery_cp = mddev->dev_sectors;
3012                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3013         }
3014         mddev->dev_sectors = sectors;
3015         mddev->resync_max_sectors = sectors;
3016         return 0;
3017 }
3018
3019 static int raid1_reshape(struct mddev *mddev)
3020 {
3021         /* We need to:
3022          * 1/ resize the r1bio_pool
3023          * 2/ resize conf->mirrors
3024          *
3025          * We allocate a new r1bio_pool if we can.
3026          * Then raise a device barrier and wait until all IO stops.
3027          * Then resize conf->mirrors and swap in the new r1bio pool.
3028          *
3029          * At the same time, we "pack" the devices so that all the missing
3030          * devices have the higher raid_disk numbers.
3031          */
3032         mempool_t *newpool, *oldpool;
3033         struct pool_info *newpoolinfo;
3034         struct raid1_info *newmirrors;
3035         struct r1conf *conf = mddev->private;
3036         int cnt, raid_disks;
3037         unsigned long flags;
3038         int d, d2, err;
3039
3040         /* Cannot change chunk_size, layout, or level */
3041         if (mddev->chunk_sectors != mddev->new_chunk_sectors ||
3042             mddev->layout != mddev->new_layout ||
3043             mddev->level != mddev->new_level) {
3044                 mddev->new_chunk_sectors = mddev->chunk_sectors;
3045                 mddev->new_layout = mddev->layout;
3046                 mddev->new_level = mddev->level;
3047                 return -EINVAL;
3048         }
3049
3050         err = md_allow_write(mddev);
3051         if (err)
3052                 return err;
3053
3054         raid_disks = mddev->raid_disks + mddev->delta_disks;
3055
3056         if (raid_disks < conf->raid_disks) {
3057                 cnt=0;
3058                 for (d= 0; d < conf->raid_disks; d++)
3059                         if (conf->mirrors[d].rdev)
3060                                 cnt++;
3061                 if (cnt > raid_disks)
3062                         return -EBUSY;
3063         }
3064
3065         newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
3066         if (!newpoolinfo)
3067                 return -ENOMEM;
3068         newpoolinfo->mddev = mddev;
3069         newpoolinfo->raid_disks = raid_disks * 2;
3070
3071         newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
3072                                  r1bio_pool_free, newpoolinfo);
3073         if (!newpool) {
3074                 kfree(newpoolinfo);
3075                 return -ENOMEM;
3076         }
3077         newmirrors = kzalloc(sizeof(struct raid1_info) * raid_disks * 2,
3078                              GFP_KERNEL);
3079         if (!newmirrors) {
3080                 kfree(newpoolinfo);
3081                 mempool_destroy(newpool);
3082                 return -ENOMEM;
3083         }
3084
3085         freeze_array(conf, 0);
3086
3087         /* ok, everything is stopped */
3088         oldpool = conf->r1bio_pool;
3089         conf->r1bio_pool = newpool;
3090
3091         for (d = d2 = 0; d < conf->raid_disks; d++) {
3092                 struct md_rdev *rdev = conf->mirrors[d].rdev;
3093                 if (rdev && rdev->raid_disk != d2) {
3094                         sysfs_unlink_rdev(mddev, rdev);
3095                         rdev->raid_disk = d2;
3096                         sysfs_unlink_rdev(mddev, rdev);
3097                         if (sysfs_link_rdev(mddev, rdev))
3098                                 printk(KERN_WARNING
3099                                        "md/raid1:%s: cannot register rd%d\n",
3100                                        mdname(mddev), rdev->raid_disk);
3101                 }
3102                 if (rdev)
3103                         newmirrors[d2++].rdev = rdev;
3104         }
3105         kfree(conf->mirrors);
3106         conf->mirrors = newmirrors;
3107         kfree(conf->poolinfo);
3108         conf->poolinfo = newpoolinfo;
3109
3110         spin_lock_irqsave(&conf->device_lock, flags);
3111         mddev->degraded += (raid_disks - conf->raid_disks);
3112         spin_unlock_irqrestore(&conf->device_lock, flags);
3113         conf->raid_disks = mddev->raid_disks = raid_disks;
3114         mddev->delta_disks = 0;
3115
3116         unfreeze_array(conf);
3117
3118         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3119         md_wakeup_thread(mddev->thread);
3120
3121         mempool_destroy(oldpool);
3122         return 0;
3123 }
3124
3125 static void raid1_quiesce(struct mddev *mddev, int state)
3126 {
3127         struct r1conf *conf = mddev->private;
3128
3129         switch(state) {
3130         case 2: /* wake for suspend */
3131                 wake_up(&conf->wait_barrier);
3132                 break;
3133         case 1:
3134                 freeze_array(conf, 0);
3135                 break;
3136         case 0:
3137                 unfreeze_array(conf);
3138                 break;
3139         }
3140 }
3141
3142 static void *raid1_takeover(struct mddev *mddev)
3143 {
3144         /* raid1 can take over:
3145          *  raid5 with 2 devices, any layout or chunk size
3146          */
3147         if (mddev->level == 5 && mddev->raid_disks == 2) {
3148                 struct r1conf *conf;
3149                 mddev->new_level = 1;
3150                 mddev->new_layout = 0;
3151                 mddev->new_chunk_sectors = 0;
3152                 conf = setup_conf(mddev);
3153                 if (!IS_ERR(conf))
3154                         /* Array must appear to be quiesced */
3155                         conf->array_frozen = 1;
3156                 return conf;
3157         }
3158         return ERR_PTR(-EINVAL);
3159 }
3160
3161 static struct md_personality raid1_personality =
3162 {
3163         .name           = "raid1",
3164         .level          = 1,
3165         .owner          = THIS_MODULE,
3166         .make_request   = make_request,
3167         .run            = run,
3168         .stop           = stop,
3169         .status         = status,
3170         .error_handler  = error,
3171         .hot_add_disk   = raid1_add_disk,
3172         .hot_remove_disk= raid1_remove_disk,
3173         .spare_active   = raid1_spare_active,
3174         .sync_request   = sync_request,
3175         .resize         = raid1_resize,
3176         .size           = raid1_size,
3177         .check_reshape  = raid1_reshape,
3178         .quiesce        = raid1_quiesce,
3179         .takeover       = raid1_takeover,
3180 };
3181
3182 static int __init raid_init(void)
3183 {
3184         return register_md_personality(&raid1_personality);
3185 }
3186
3187 static void raid_exit(void)
3188 {
3189         unregister_md_personality(&raid1_personality);
3190 }
3191
3192 module_init(raid_init);
3193 module_exit(raid_exit);
3194 MODULE_LICENSE("GPL");
3195 MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
3196 MODULE_ALIAS("md-personality-3"); /* RAID1 */
3197 MODULE_ALIAS("md-raid1");
3198 MODULE_ALIAS("md-level-1");
3199
3200 module_param(max_queued_requests, int, S_IRUGO|S_IWUSR);