Revert "ACPI: Add BayTrail SoC GPIO and LPSS ACPI IDs"
[firefly-linux-kernel-4.4.55.git] / drivers / md / raid10.c
1 /*
2  * raid10.c : Multiple Devices driver for Linux
3  *
4  * Copyright (C) 2000-2004 Neil Brown
5  *
6  * RAID-10 support for md.
7  *
8  * Base on code in raid1.c.  See raid1.c for further copyright information.
9  *
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20
21 #include <linux/slab.h>
22 #include <linux/delay.h>
23 #include <linux/blkdev.h>
24 #include <linux/module.h>
25 #include <linux/seq_file.h>
26 #include <linux/ratelimit.h>
27 #include <linux/kthread.h>
28 #include "md.h"
29 #include "raid10.h"
30 #include "raid0.h"
31 #include "bitmap.h"
32
33 /*
34  * RAID10 provides a combination of RAID0 and RAID1 functionality.
35  * The layout of data is defined by
36  *    chunk_size
37  *    raid_disks
38  *    near_copies (stored in low byte of layout)
39  *    far_copies (stored in second byte of layout)
40  *    far_offset (stored in bit 16 of layout )
41  *    use_far_sets (stored in bit 17 of layout )
42  *
43  * The data to be stored is divided into chunks using chunksize.  Each device
44  * is divided into far_copies sections.   In each section, chunks are laid out
45  * in a style similar to raid0, but near_copies copies of each chunk is stored
46  * (each on a different drive).  The starting device for each section is offset
47  * near_copies from the starting device of the previous section.  Thus there
48  * are (near_copies * far_copies) of each chunk, and each is on a different
49  * drive.  near_copies and far_copies must be at least one, and their product
50  * is at most raid_disks.
51  *
52  * If far_offset is true, then the far_copies are handled a bit differently.
53  * The copies are still in different stripes, but instead of being very far
54  * apart on disk, there are adjacent stripes.
55  *
56  * The far and offset algorithms are handled slightly differently if
57  * 'use_far_sets' is true.  In this case, the array's devices are grouped into
58  * sets that are (near_copies * far_copies) in size.  The far copied stripes
59  * are still shifted by 'near_copies' devices, but this shifting stays confined
60  * to the set rather than the entire array.  This is done to improve the number
61  * of device combinations that can fail without causing the array to fail.
62  * Example 'far' algorithm w/o 'use_far_sets' (each letter represents a chunk
63  * on a device):
64  *    A B C D    A B C D E
65  *      ...         ...
66  *    D A B C    E A B C D
67  * Example 'far' algorithm w/ 'use_far_sets' enabled (sets illustrated w/ []'s):
68  *    [A B] [C D]    [A B] [C D E]
69  *    |...| |...|    |...| | ... |
70  *    [B A] [D C]    [B A] [E C D]
71  */
72
73 /*
74  * Number of guaranteed r10bios in case of extreme VM load:
75  */
76 #define NR_RAID10_BIOS 256
77
78 /* when we get a read error on a read-only array, we redirect to another
79  * device without failing the first device, or trying to over-write to
80  * correct the read error.  To keep track of bad blocks on a per-bio
81  * level, we store IO_BLOCKED in the appropriate 'bios' pointer
82  */
83 #define IO_BLOCKED ((struct bio *)1)
84 /* When we successfully write to a known bad-block, we need to remove the
85  * bad-block marking which must be done from process context.  So we record
86  * the success by setting devs[n].bio to IO_MADE_GOOD
87  */
88 #define IO_MADE_GOOD ((struct bio *)2)
89
90 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
91
92 /* When there are this many requests queued to be written by
93  * the raid10 thread, we become 'congested' to provide back-pressure
94  * for writeback.
95  */
96 static int max_queued_requests = 1024;
97
98 static void allow_barrier(struct r10conf *conf);
99 static void lower_barrier(struct r10conf *conf);
100 static int _enough(struct r10conf *conf, int previous, int ignore);
101 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
102                                 int *skipped);
103 static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio);
104 static void end_reshape_write(struct bio *bio, int error);
105 static void end_reshape(struct r10conf *conf);
106
107 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
108 {
109         struct r10conf *conf = data;
110         int size = offsetof(struct r10bio, devs[conf->copies]);
111
112         /* allocate a r10bio with room for raid_disks entries in the
113          * bios array */
114         return kzalloc(size, gfp_flags);
115 }
116
117 static void r10bio_pool_free(void *r10_bio, void *data)
118 {
119         kfree(r10_bio);
120 }
121
122 /* Maximum size of each resync request */
123 #define RESYNC_BLOCK_SIZE (64*1024)
124 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
125 /* amount of memory to reserve for resync requests */
126 #define RESYNC_WINDOW (1024*1024)
127 /* maximum number of concurrent requests, memory permitting */
128 #define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
129
130 /*
131  * When performing a resync, we need to read and compare, so
132  * we need as many pages are there are copies.
133  * When performing a recovery, we need 2 bios, one for read,
134  * one for write (we recover only one drive per r10buf)
135  *
136  */
137 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
138 {
139         struct r10conf *conf = data;
140         struct page *page;
141         struct r10bio *r10_bio;
142         struct bio *bio;
143         int i, j;
144         int nalloc;
145
146         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
147         if (!r10_bio)
148                 return NULL;
149
150         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery) ||
151             test_bit(MD_RECOVERY_RESHAPE, &conf->mddev->recovery))
152                 nalloc = conf->copies; /* resync */
153         else
154                 nalloc = 2; /* recovery */
155
156         /*
157          * Allocate bios.
158          */
159         for (j = nalloc ; j-- ; ) {
160                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
161                 if (!bio)
162                         goto out_free_bio;
163                 r10_bio->devs[j].bio = bio;
164                 if (!conf->have_replacement)
165                         continue;
166                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
167                 if (!bio)
168                         goto out_free_bio;
169                 r10_bio->devs[j].repl_bio = bio;
170         }
171         /*
172          * Allocate RESYNC_PAGES data pages and attach them
173          * where needed.
174          */
175         for (j = 0 ; j < nalloc; j++) {
176                 struct bio *rbio = r10_bio->devs[j].repl_bio;
177                 bio = r10_bio->devs[j].bio;
178                 for (i = 0; i < RESYNC_PAGES; i++) {
179                         if (j > 0 && !test_bit(MD_RECOVERY_SYNC,
180                                                &conf->mddev->recovery)) {
181                                 /* we can share bv_page's during recovery
182                                  * and reshape */
183                                 struct bio *rbio = r10_bio->devs[0].bio;
184                                 page = rbio->bi_io_vec[i].bv_page;
185                                 get_page(page);
186                         } else
187                                 page = alloc_page(gfp_flags);
188                         if (unlikely(!page))
189                                 goto out_free_pages;
190
191                         bio->bi_io_vec[i].bv_page = page;
192                         if (rbio)
193                                 rbio->bi_io_vec[i].bv_page = page;
194                 }
195         }
196
197         return r10_bio;
198
199 out_free_pages:
200         for ( ; i > 0 ; i--)
201                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
202         while (j--)
203                 for (i = 0; i < RESYNC_PAGES ; i++)
204                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
205         j = 0;
206 out_free_bio:
207         for ( ; j < nalloc; j++) {
208                 if (r10_bio->devs[j].bio)
209                         bio_put(r10_bio->devs[j].bio);
210                 if (r10_bio->devs[j].repl_bio)
211                         bio_put(r10_bio->devs[j].repl_bio);
212         }
213         r10bio_pool_free(r10_bio, conf);
214         return NULL;
215 }
216
217 static void r10buf_pool_free(void *__r10_bio, void *data)
218 {
219         int i;
220         struct r10conf *conf = data;
221         struct r10bio *r10bio = __r10_bio;
222         int j;
223
224         for (j=0; j < conf->copies; j++) {
225                 struct bio *bio = r10bio->devs[j].bio;
226                 if (bio) {
227                         for (i = 0; i < RESYNC_PAGES; i++) {
228                                 safe_put_page(bio->bi_io_vec[i].bv_page);
229                                 bio->bi_io_vec[i].bv_page = NULL;
230                         }
231                         bio_put(bio);
232                 }
233                 bio = r10bio->devs[j].repl_bio;
234                 if (bio)
235                         bio_put(bio);
236         }
237         r10bio_pool_free(r10bio, conf);
238 }
239
240 static void put_all_bios(struct r10conf *conf, struct r10bio *r10_bio)
241 {
242         int i;
243
244         for (i = 0; i < conf->copies; i++) {
245                 struct bio **bio = & r10_bio->devs[i].bio;
246                 if (!BIO_SPECIAL(*bio))
247                         bio_put(*bio);
248                 *bio = NULL;
249                 bio = &r10_bio->devs[i].repl_bio;
250                 if (r10_bio->read_slot < 0 && !BIO_SPECIAL(*bio))
251                         bio_put(*bio);
252                 *bio = NULL;
253         }
254 }
255
256 static void free_r10bio(struct r10bio *r10_bio)
257 {
258         struct r10conf *conf = r10_bio->mddev->private;
259
260         put_all_bios(conf, r10_bio);
261         mempool_free(r10_bio, conf->r10bio_pool);
262 }
263
264 static void put_buf(struct r10bio *r10_bio)
265 {
266         struct r10conf *conf = r10_bio->mddev->private;
267
268         mempool_free(r10_bio, conf->r10buf_pool);
269
270         lower_barrier(conf);
271 }
272
273 static void reschedule_retry(struct r10bio *r10_bio)
274 {
275         unsigned long flags;
276         struct mddev *mddev = r10_bio->mddev;
277         struct r10conf *conf = mddev->private;
278
279         spin_lock_irqsave(&conf->device_lock, flags);
280         list_add(&r10_bio->retry_list, &conf->retry_list);
281         conf->nr_queued ++;
282         spin_unlock_irqrestore(&conf->device_lock, flags);
283
284         /* wake up frozen array... */
285         wake_up(&conf->wait_barrier);
286
287         md_wakeup_thread(mddev->thread);
288 }
289
290 /*
291  * raid_end_bio_io() is called when we have finished servicing a mirrored
292  * operation and are ready to return a success/failure code to the buffer
293  * cache layer.
294  */
295 static void raid_end_bio_io(struct r10bio *r10_bio)
296 {
297         struct bio *bio = r10_bio->master_bio;
298         int done;
299         struct r10conf *conf = r10_bio->mddev->private;
300
301         if (bio->bi_phys_segments) {
302                 unsigned long flags;
303                 spin_lock_irqsave(&conf->device_lock, flags);
304                 bio->bi_phys_segments--;
305                 done = (bio->bi_phys_segments == 0);
306                 spin_unlock_irqrestore(&conf->device_lock, flags);
307         } else
308                 done = 1;
309         if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
310                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
311         if (done) {
312                 bio_endio(bio, 0);
313                 /*
314                  * Wake up any possible resync thread that waits for the device
315                  * to go idle.
316                  */
317                 allow_barrier(conf);
318         }
319         free_r10bio(r10_bio);
320 }
321
322 /*
323  * Update disk head position estimator based on IRQ completion info.
324  */
325 static inline void update_head_pos(int slot, struct r10bio *r10_bio)
326 {
327         struct r10conf *conf = r10_bio->mddev->private;
328
329         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
330                 r10_bio->devs[slot].addr + (r10_bio->sectors);
331 }
332
333 /*
334  * Find the disk number which triggered given bio
335  */
336 static int find_bio_disk(struct r10conf *conf, struct r10bio *r10_bio,
337                          struct bio *bio, int *slotp, int *replp)
338 {
339         int slot;
340         int repl = 0;
341
342         for (slot = 0; slot < conf->copies; slot++) {
343                 if (r10_bio->devs[slot].bio == bio)
344                         break;
345                 if (r10_bio->devs[slot].repl_bio == bio) {
346                         repl = 1;
347                         break;
348                 }
349         }
350
351         BUG_ON(slot == conf->copies);
352         update_head_pos(slot, r10_bio);
353
354         if (slotp)
355                 *slotp = slot;
356         if (replp)
357                 *replp = repl;
358         return r10_bio->devs[slot].devnum;
359 }
360
361 static void raid10_end_read_request(struct bio *bio, int error)
362 {
363         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
364         struct r10bio *r10_bio = bio->bi_private;
365         int slot, dev;
366         struct md_rdev *rdev;
367         struct r10conf *conf = r10_bio->mddev->private;
368
369
370         slot = r10_bio->read_slot;
371         dev = r10_bio->devs[slot].devnum;
372         rdev = r10_bio->devs[slot].rdev;
373         /*
374          * this branch is our 'one mirror IO has finished' event handler:
375          */
376         update_head_pos(slot, r10_bio);
377
378         if (uptodate) {
379                 /*
380                  * Set R10BIO_Uptodate in our master bio, so that
381                  * we will return a good error code to the higher
382                  * levels even if IO on some other mirrored buffer fails.
383                  *
384                  * The 'master' represents the composite IO operation to
385                  * user-side. So if something waits for IO, then it will
386                  * wait for the 'master' bio.
387                  */
388                 set_bit(R10BIO_Uptodate, &r10_bio->state);
389         } else {
390                 /* If all other devices that store this block have
391                  * failed, we want to return the error upwards rather
392                  * than fail the last device.  Here we redefine
393                  * "uptodate" to mean "Don't want to retry"
394                  */
395                 if (!_enough(conf, test_bit(R10BIO_Previous, &r10_bio->state),
396                              rdev->raid_disk))
397                         uptodate = 1;
398         }
399         if (uptodate) {
400                 raid_end_bio_io(r10_bio);
401                 rdev_dec_pending(rdev, conf->mddev);
402         } else {
403                 /*
404                  * oops, read error - keep the refcount on the rdev
405                  */
406                 char b[BDEVNAME_SIZE];
407                 printk_ratelimited(KERN_ERR
408                                    "md/raid10:%s: %s: rescheduling sector %llu\n",
409                                    mdname(conf->mddev),
410                                    bdevname(rdev->bdev, b),
411                                    (unsigned long long)r10_bio->sector);
412                 set_bit(R10BIO_ReadError, &r10_bio->state);
413                 reschedule_retry(r10_bio);
414         }
415 }
416
417 static void close_write(struct r10bio *r10_bio)
418 {
419         /* clear the bitmap if all writes complete successfully */
420         bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
421                         r10_bio->sectors,
422                         !test_bit(R10BIO_Degraded, &r10_bio->state),
423                         0);
424         md_write_end(r10_bio->mddev);
425 }
426
427 static void one_write_done(struct r10bio *r10_bio)
428 {
429         if (atomic_dec_and_test(&r10_bio->remaining)) {
430                 if (test_bit(R10BIO_WriteError, &r10_bio->state))
431                         reschedule_retry(r10_bio);
432                 else {
433                         close_write(r10_bio);
434                         if (test_bit(R10BIO_MadeGood, &r10_bio->state))
435                                 reschedule_retry(r10_bio);
436                         else
437                                 raid_end_bio_io(r10_bio);
438                 }
439         }
440 }
441
442 static void raid10_end_write_request(struct bio *bio, int error)
443 {
444         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
445         struct r10bio *r10_bio = bio->bi_private;
446         int dev;
447         int dec_rdev = 1;
448         struct r10conf *conf = r10_bio->mddev->private;
449         int slot, repl;
450         struct md_rdev *rdev = NULL;
451
452         dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
453
454         if (repl)
455                 rdev = conf->mirrors[dev].replacement;
456         if (!rdev) {
457                 smp_rmb();
458                 repl = 0;
459                 rdev = conf->mirrors[dev].rdev;
460         }
461         /*
462          * this branch is our 'one mirror IO has finished' event handler:
463          */
464         if (!uptodate) {
465                 if (repl)
466                         /* Never record new bad blocks to replacement,
467                          * just fail it.
468                          */
469                         md_error(rdev->mddev, rdev);
470                 else {
471                         set_bit(WriteErrorSeen, &rdev->flags);
472                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
473                                 set_bit(MD_RECOVERY_NEEDED,
474                                         &rdev->mddev->recovery);
475                         set_bit(R10BIO_WriteError, &r10_bio->state);
476                         dec_rdev = 0;
477                 }
478         } else {
479                 /*
480                  * Set R10BIO_Uptodate in our master bio, so that
481                  * we will return a good error code for to the higher
482                  * levels even if IO on some other mirrored buffer fails.
483                  *
484                  * The 'master' represents the composite IO operation to
485                  * user-side. So if something waits for IO, then it will
486                  * wait for the 'master' bio.
487                  */
488                 sector_t first_bad;
489                 int bad_sectors;
490
491                 /*
492                  * Do not set R10BIO_Uptodate if the current device is
493                  * rebuilding or Faulty. This is because we cannot use
494                  * such device for properly reading the data back (we could
495                  * potentially use it, if the current write would have felt
496                  * before rdev->recovery_offset, but for simplicity we don't
497                  * check this here.
498                  */
499                 if (test_bit(In_sync, &rdev->flags) &&
500                     !test_bit(Faulty, &rdev->flags))
501                         set_bit(R10BIO_Uptodate, &r10_bio->state);
502
503                 /* Maybe we can clear some bad blocks. */
504                 if (is_badblock(rdev,
505                                 r10_bio->devs[slot].addr,
506                                 r10_bio->sectors,
507                                 &first_bad, &bad_sectors)) {
508                         bio_put(bio);
509                         if (repl)
510                                 r10_bio->devs[slot].repl_bio = IO_MADE_GOOD;
511                         else
512                                 r10_bio->devs[slot].bio = IO_MADE_GOOD;
513                         dec_rdev = 0;
514                         set_bit(R10BIO_MadeGood, &r10_bio->state);
515                 }
516         }
517
518         /*
519          *
520          * Let's see if all mirrored write operations have finished
521          * already.
522          */
523         one_write_done(r10_bio);
524         if (dec_rdev)
525                 rdev_dec_pending(rdev, conf->mddev);
526 }
527
528 /*
529  * RAID10 layout manager
530  * As well as the chunksize and raid_disks count, there are two
531  * parameters: near_copies and far_copies.
532  * near_copies * far_copies must be <= raid_disks.
533  * Normally one of these will be 1.
534  * If both are 1, we get raid0.
535  * If near_copies == raid_disks, we get raid1.
536  *
537  * Chunks are laid out in raid0 style with near_copies copies of the
538  * first chunk, followed by near_copies copies of the next chunk and
539  * so on.
540  * If far_copies > 1, then after 1/far_copies of the array has been assigned
541  * as described above, we start again with a device offset of near_copies.
542  * So we effectively have another copy of the whole array further down all
543  * the drives, but with blocks on different drives.
544  * With this layout, and block is never stored twice on the one device.
545  *
546  * raid10_find_phys finds the sector offset of a given virtual sector
547  * on each device that it is on.
548  *
549  * raid10_find_virt does the reverse mapping, from a device and a
550  * sector offset to a virtual address
551  */
552
553 static void __raid10_find_phys(struct geom *geo, struct r10bio *r10bio)
554 {
555         int n,f;
556         sector_t sector;
557         sector_t chunk;
558         sector_t stripe;
559         int dev;
560         int slot = 0;
561         int last_far_set_start, last_far_set_size;
562
563         last_far_set_start = (geo->raid_disks / geo->far_set_size) - 1;
564         last_far_set_start *= geo->far_set_size;
565
566         last_far_set_size = geo->far_set_size;
567         last_far_set_size += (geo->raid_disks % geo->far_set_size);
568
569         /* now calculate first sector/dev */
570         chunk = r10bio->sector >> geo->chunk_shift;
571         sector = r10bio->sector & geo->chunk_mask;
572
573         chunk *= geo->near_copies;
574         stripe = chunk;
575         dev = sector_div(stripe, geo->raid_disks);
576         if (geo->far_offset)
577                 stripe *= geo->far_copies;
578
579         sector += stripe << geo->chunk_shift;
580
581         /* and calculate all the others */
582         for (n = 0; n < geo->near_copies; n++) {
583                 int d = dev;
584                 int set;
585                 sector_t s = sector;
586                 r10bio->devs[slot].devnum = d;
587                 r10bio->devs[slot].addr = s;
588                 slot++;
589
590                 for (f = 1; f < geo->far_copies; f++) {
591                         set = d / geo->far_set_size;
592                         d += geo->near_copies;
593
594                         if ((geo->raid_disks % geo->far_set_size) &&
595                             (d > last_far_set_start)) {
596                                 d -= last_far_set_start;
597                                 d %= last_far_set_size;
598                                 d += last_far_set_start;
599                         } else {
600                                 d %= geo->far_set_size;
601                                 d += geo->far_set_size * set;
602                         }
603                         s += geo->stride;
604                         r10bio->devs[slot].devnum = d;
605                         r10bio->devs[slot].addr = s;
606                         slot++;
607                 }
608                 dev++;
609                 if (dev >= geo->raid_disks) {
610                         dev = 0;
611                         sector += (geo->chunk_mask + 1);
612                 }
613         }
614 }
615
616 static void raid10_find_phys(struct r10conf *conf, struct r10bio *r10bio)
617 {
618         struct geom *geo = &conf->geo;
619
620         if (conf->reshape_progress != MaxSector &&
621             ((r10bio->sector >= conf->reshape_progress) !=
622              conf->mddev->reshape_backwards)) {
623                 set_bit(R10BIO_Previous, &r10bio->state);
624                 geo = &conf->prev;
625         } else
626                 clear_bit(R10BIO_Previous, &r10bio->state);
627
628         __raid10_find_phys(geo, r10bio);
629 }
630
631 static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev)
632 {
633         sector_t offset, chunk, vchunk;
634         /* Never use conf->prev as this is only called during resync
635          * or recovery, so reshape isn't happening
636          */
637         struct geom *geo = &conf->geo;
638         int far_set_start = (dev / geo->far_set_size) * geo->far_set_size;
639         int far_set_size = geo->far_set_size;
640         int last_far_set_start;
641
642         if (geo->raid_disks % geo->far_set_size) {
643                 last_far_set_start = (geo->raid_disks / geo->far_set_size) - 1;
644                 last_far_set_start *= geo->far_set_size;
645
646                 if (dev >= last_far_set_start) {
647                         far_set_size = geo->far_set_size;
648                         far_set_size += (geo->raid_disks % geo->far_set_size);
649                         far_set_start = last_far_set_start;
650                 }
651         }
652
653         offset = sector & geo->chunk_mask;
654         if (geo->far_offset) {
655                 int fc;
656                 chunk = sector >> geo->chunk_shift;
657                 fc = sector_div(chunk, geo->far_copies);
658                 dev -= fc * geo->near_copies;
659                 if (dev < far_set_start)
660                         dev += far_set_size;
661         } else {
662                 while (sector >= geo->stride) {
663                         sector -= geo->stride;
664                         if (dev < (geo->near_copies + far_set_start))
665                                 dev += far_set_size - geo->near_copies;
666                         else
667                                 dev -= geo->near_copies;
668                 }
669                 chunk = sector >> geo->chunk_shift;
670         }
671         vchunk = chunk * geo->raid_disks + dev;
672         sector_div(vchunk, geo->near_copies);
673         return (vchunk << geo->chunk_shift) + offset;
674 }
675
676 /**
677  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
678  *      @q: request queue
679  *      @bvm: properties of new bio
680  *      @biovec: the request that could be merged to it.
681  *
682  *      Return amount of bytes we can accept at this offset
683  *      This requires checking for end-of-chunk if near_copies != raid_disks,
684  *      and for subordinate merge_bvec_fns if merge_check_needed.
685  */
686 static int raid10_mergeable_bvec(struct request_queue *q,
687                                  struct bvec_merge_data *bvm,
688                                  struct bio_vec *biovec)
689 {
690         struct mddev *mddev = q->queuedata;
691         struct r10conf *conf = mddev->private;
692         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
693         int max;
694         unsigned int chunk_sectors;
695         unsigned int bio_sectors = bvm->bi_size >> 9;
696         struct geom *geo = &conf->geo;
697
698         chunk_sectors = (conf->geo.chunk_mask & conf->prev.chunk_mask) + 1;
699         if (conf->reshape_progress != MaxSector &&
700             ((sector >= conf->reshape_progress) !=
701              conf->mddev->reshape_backwards))
702                 geo = &conf->prev;
703
704         if (geo->near_copies < geo->raid_disks) {
705                 max = (chunk_sectors - ((sector & (chunk_sectors - 1))
706                                         + bio_sectors)) << 9;
707                 if (max < 0)
708                         /* bio_add cannot handle a negative return */
709                         max = 0;
710                 if (max <= biovec->bv_len && bio_sectors == 0)
711                         return biovec->bv_len;
712         } else
713                 max = biovec->bv_len;
714
715         if (mddev->merge_check_needed) {
716                 struct {
717                         struct r10bio r10_bio;
718                         struct r10dev devs[conf->copies];
719                 } on_stack;
720                 struct r10bio *r10_bio = &on_stack.r10_bio;
721                 int s;
722                 if (conf->reshape_progress != MaxSector) {
723                         /* Cannot give any guidance during reshape */
724                         if (max <= biovec->bv_len && bio_sectors == 0)
725                                 return biovec->bv_len;
726                         return 0;
727                 }
728                 r10_bio->sector = sector;
729                 raid10_find_phys(conf, r10_bio);
730                 rcu_read_lock();
731                 for (s = 0; s < conf->copies; s++) {
732                         int disk = r10_bio->devs[s].devnum;
733                         struct md_rdev *rdev = rcu_dereference(
734                                 conf->mirrors[disk].rdev);
735                         if (rdev && !test_bit(Faulty, &rdev->flags)) {
736                                 struct request_queue *q =
737                                         bdev_get_queue(rdev->bdev);
738                                 if (q->merge_bvec_fn) {
739                                         bvm->bi_sector = r10_bio->devs[s].addr
740                                                 + rdev->data_offset;
741                                         bvm->bi_bdev = rdev->bdev;
742                                         max = min(max, q->merge_bvec_fn(
743                                                           q, bvm, biovec));
744                                 }
745                         }
746                         rdev = rcu_dereference(conf->mirrors[disk].replacement);
747                         if (rdev && !test_bit(Faulty, &rdev->flags)) {
748                                 struct request_queue *q =
749                                         bdev_get_queue(rdev->bdev);
750                                 if (q->merge_bvec_fn) {
751                                         bvm->bi_sector = r10_bio->devs[s].addr
752                                                 + rdev->data_offset;
753                                         bvm->bi_bdev = rdev->bdev;
754                                         max = min(max, q->merge_bvec_fn(
755                                                           q, bvm, biovec));
756                                 }
757                         }
758                 }
759                 rcu_read_unlock();
760         }
761         return max;
762 }
763
764 /*
765  * This routine returns the disk from which the requested read should
766  * be done. There is a per-array 'next expected sequential IO' sector
767  * number - if this matches on the next IO then we use the last disk.
768  * There is also a per-disk 'last know head position' sector that is
769  * maintained from IRQ contexts, both the normal and the resync IO
770  * completion handlers update this position correctly. If there is no
771  * perfect sequential match then we pick the disk whose head is closest.
772  *
773  * If there are 2 mirrors in the same 2 devices, performance degrades
774  * because position is mirror, not device based.
775  *
776  * The rdev for the device selected will have nr_pending incremented.
777  */
778
779 /*
780  * FIXME: possibly should rethink readbalancing and do it differently
781  * depending on near_copies / far_copies geometry.
782  */
783 static struct md_rdev *read_balance(struct r10conf *conf,
784                                     struct r10bio *r10_bio,
785                                     int *max_sectors)
786 {
787         const sector_t this_sector = r10_bio->sector;
788         int disk, slot;
789         int sectors = r10_bio->sectors;
790         int best_good_sectors;
791         sector_t new_distance, best_dist;
792         struct md_rdev *best_rdev, *rdev = NULL;
793         int do_balance;
794         int best_slot;
795         struct geom *geo = &conf->geo;
796
797         raid10_find_phys(conf, r10_bio);
798         rcu_read_lock();
799 retry:
800         sectors = r10_bio->sectors;
801         best_slot = -1;
802         best_rdev = NULL;
803         best_dist = MaxSector;
804         best_good_sectors = 0;
805         do_balance = 1;
806         /*
807          * Check if we can balance. We can balance on the whole
808          * device if no resync is going on (recovery is ok), or below
809          * the resync window. We take the first readable disk when
810          * above the resync window.
811          */
812         if (conf->mddev->recovery_cp < MaxSector
813             && (this_sector + sectors >= conf->next_resync))
814                 do_balance = 0;
815
816         for (slot = 0; slot < conf->copies ; slot++) {
817                 sector_t first_bad;
818                 int bad_sectors;
819                 sector_t dev_sector;
820
821                 if (r10_bio->devs[slot].bio == IO_BLOCKED)
822                         continue;
823                 disk = r10_bio->devs[slot].devnum;
824                 rdev = rcu_dereference(conf->mirrors[disk].replacement);
825                 if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
826                     test_bit(Unmerged, &rdev->flags) ||
827                     r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
828                         rdev = rcu_dereference(conf->mirrors[disk].rdev);
829                 if (rdev == NULL ||
830                     test_bit(Faulty, &rdev->flags) ||
831                     test_bit(Unmerged, &rdev->flags))
832                         continue;
833                 if (!test_bit(In_sync, &rdev->flags) &&
834                     r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
835                         continue;
836
837                 dev_sector = r10_bio->devs[slot].addr;
838                 if (is_badblock(rdev, dev_sector, sectors,
839                                 &first_bad, &bad_sectors)) {
840                         if (best_dist < MaxSector)
841                                 /* Already have a better slot */
842                                 continue;
843                         if (first_bad <= dev_sector) {
844                                 /* Cannot read here.  If this is the
845                                  * 'primary' device, then we must not read
846                                  * beyond 'bad_sectors' from another device.
847                                  */
848                                 bad_sectors -= (dev_sector - first_bad);
849                                 if (!do_balance && sectors > bad_sectors)
850                                         sectors = bad_sectors;
851                                 if (best_good_sectors > sectors)
852                                         best_good_sectors = sectors;
853                         } else {
854                                 sector_t good_sectors =
855                                         first_bad - dev_sector;
856                                 if (good_sectors > best_good_sectors) {
857                                         best_good_sectors = good_sectors;
858                                         best_slot = slot;
859                                         best_rdev = rdev;
860                                 }
861                                 if (!do_balance)
862                                         /* Must read from here */
863                                         break;
864                         }
865                         continue;
866                 } else
867                         best_good_sectors = sectors;
868
869                 if (!do_balance)
870                         break;
871
872                 /* This optimisation is debatable, and completely destroys
873                  * sequential read speed for 'far copies' arrays.  So only
874                  * keep it for 'near' arrays, and review those later.
875                  */
876                 if (geo->near_copies > 1 && !atomic_read(&rdev->nr_pending))
877                         break;
878
879                 /* for far > 1 always use the lowest address */
880                 if (geo->far_copies > 1)
881                         new_distance = r10_bio->devs[slot].addr;
882                 else
883                         new_distance = abs(r10_bio->devs[slot].addr -
884                                            conf->mirrors[disk].head_position);
885                 if (new_distance < best_dist) {
886                         best_dist = new_distance;
887                         best_slot = slot;
888                         best_rdev = rdev;
889                 }
890         }
891         if (slot >= conf->copies) {
892                 slot = best_slot;
893                 rdev = best_rdev;
894         }
895
896         if (slot >= 0) {
897                 atomic_inc(&rdev->nr_pending);
898                 if (test_bit(Faulty, &rdev->flags)) {
899                         /* Cannot risk returning a device that failed
900                          * before we inc'ed nr_pending
901                          */
902                         rdev_dec_pending(rdev, conf->mddev);
903                         goto retry;
904                 }
905                 r10_bio->read_slot = slot;
906         } else
907                 rdev = NULL;
908         rcu_read_unlock();
909         *max_sectors = best_good_sectors;
910
911         return rdev;
912 }
913
914 int md_raid10_congested(struct mddev *mddev, int bits)
915 {
916         struct r10conf *conf = mddev->private;
917         int i, ret = 0;
918
919         if ((bits & (1 << BDI_async_congested)) &&
920             conf->pending_count >= max_queued_requests)
921                 return 1;
922
923         rcu_read_lock();
924         for (i = 0;
925              (i < conf->geo.raid_disks || i < conf->prev.raid_disks)
926                      && ret == 0;
927              i++) {
928                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
929                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
930                         struct request_queue *q = bdev_get_queue(rdev->bdev);
931
932                         ret |= bdi_congested(&q->backing_dev_info, bits);
933                 }
934         }
935         rcu_read_unlock();
936         return ret;
937 }
938 EXPORT_SYMBOL_GPL(md_raid10_congested);
939
940 static int raid10_congested(void *data, int bits)
941 {
942         struct mddev *mddev = data;
943
944         return mddev_congested(mddev, bits) ||
945                 md_raid10_congested(mddev, bits);
946 }
947
948 static void flush_pending_writes(struct r10conf *conf)
949 {
950         /* Any writes that have been queued but are awaiting
951          * bitmap updates get flushed here.
952          */
953         spin_lock_irq(&conf->device_lock);
954
955         if (conf->pending_bio_list.head) {
956                 struct bio *bio;
957                 bio = bio_list_get(&conf->pending_bio_list);
958                 conf->pending_count = 0;
959                 spin_unlock_irq(&conf->device_lock);
960                 /* flush any pending bitmap writes to disk
961                  * before proceeding w/ I/O */
962                 bitmap_unplug(conf->mddev->bitmap);
963                 wake_up(&conf->wait_barrier);
964
965                 while (bio) { /* submit pending writes */
966                         struct bio *next = bio->bi_next;
967                         bio->bi_next = NULL;
968                         if (unlikely((bio->bi_rw & REQ_DISCARD) &&
969                             !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
970                                 /* Just ignore it */
971                                 bio_endio(bio, 0);
972                         else
973                                 generic_make_request(bio);
974                         bio = next;
975                 }
976         } else
977                 spin_unlock_irq(&conf->device_lock);
978 }
979
980 /* Barriers....
981  * Sometimes we need to suspend IO while we do something else,
982  * either some resync/recovery, or reconfigure the array.
983  * To do this we raise a 'barrier'.
984  * The 'barrier' is a counter that can be raised multiple times
985  * to count how many activities are happening which preclude
986  * normal IO.
987  * We can only raise the barrier if there is no pending IO.
988  * i.e. if nr_pending == 0.
989  * We choose only to raise the barrier if no-one is waiting for the
990  * barrier to go down.  This means that as soon as an IO request
991  * is ready, no other operations which require a barrier will start
992  * until the IO request has had a chance.
993  *
994  * So: regular IO calls 'wait_barrier'.  When that returns there
995  *    is no backgroup IO happening,  It must arrange to call
996  *    allow_barrier when it has finished its IO.
997  * backgroup IO calls must call raise_barrier.  Once that returns
998  *    there is no normal IO happeing.  It must arrange to call
999  *    lower_barrier when the particular background IO completes.
1000  */
1001
1002 static void raise_barrier(struct r10conf *conf, int force)
1003 {
1004         BUG_ON(force && !conf->barrier);
1005         spin_lock_irq(&conf->resync_lock);
1006
1007         /* Wait until no block IO is waiting (unless 'force') */
1008         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
1009                             conf->resync_lock);
1010
1011         /* block any new IO from starting */
1012         conf->barrier++;
1013
1014         /* Now wait for all pending IO to complete */
1015         wait_event_lock_irq(conf->wait_barrier,
1016                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
1017                             conf->resync_lock);
1018
1019         spin_unlock_irq(&conf->resync_lock);
1020 }
1021
1022 static void lower_barrier(struct r10conf *conf)
1023 {
1024         unsigned long flags;
1025         spin_lock_irqsave(&conf->resync_lock, flags);
1026         conf->barrier--;
1027         spin_unlock_irqrestore(&conf->resync_lock, flags);
1028         wake_up(&conf->wait_barrier);
1029 }
1030
1031 static void wait_barrier(struct r10conf *conf)
1032 {
1033         spin_lock_irq(&conf->resync_lock);
1034         if (conf->barrier) {
1035                 conf->nr_waiting++;
1036                 /* Wait for the barrier to drop.
1037                  * However if there are already pending
1038                  * requests (preventing the barrier from
1039                  * rising completely), and the
1040                  * pre-process bio queue isn't empty,
1041                  * then don't wait, as we need to empty
1042                  * that queue to get the nr_pending
1043                  * count down.
1044                  */
1045                 wait_event_lock_irq(conf->wait_barrier,
1046                                     !conf->barrier ||
1047                                     (conf->nr_pending &&
1048                                      current->bio_list &&
1049                                      !bio_list_empty(current->bio_list)),
1050                                     conf->resync_lock);
1051                 conf->nr_waiting--;
1052         }
1053         conf->nr_pending++;
1054         spin_unlock_irq(&conf->resync_lock);
1055 }
1056
1057 static void allow_barrier(struct r10conf *conf)
1058 {
1059         unsigned long flags;
1060         spin_lock_irqsave(&conf->resync_lock, flags);
1061         conf->nr_pending--;
1062         spin_unlock_irqrestore(&conf->resync_lock, flags);
1063         wake_up(&conf->wait_barrier);
1064 }
1065
1066 static void freeze_array(struct r10conf *conf, int extra)
1067 {
1068         /* stop syncio and normal IO and wait for everything to
1069          * go quiet.
1070          * We increment barrier and nr_waiting, and then
1071          * wait until nr_pending match nr_queued+extra
1072          * This is called in the context of one normal IO request
1073          * that has failed. Thus any sync request that might be pending
1074          * will be blocked by nr_pending, and we need to wait for
1075          * pending IO requests to complete or be queued for re-try.
1076          * Thus the number queued (nr_queued) plus this request (extra)
1077          * must match the number of pending IOs (nr_pending) before
1078          * we continue.
1079          */
1080         spin_lock_irq(&conf->resync_lock);
1081         conf->barrier++;
1082         conf->nr_waiting++;
1083         wait_event_lock_irq_cmd(conf->wait_barrier,
1084                                 conf->nr_pending == conf->nr_queued+extra,
1085                                 conf->resync_lock,
1086                                 flush_pending_writes(conf));
1087
1088         spin_unlock_irq(&conf->resync_lock);
1089 }
1090
1091 static void unfreeze_array(struct r10conf *conf)
1092 {
1093         /* reverse the effect of the freeze */
1094         spin_lock_irq(&conf->resync_lock);
1095         conf->barrier--;
1096         conf->nr_waiting--;
1097         wake_up(&conf->wait_barrier);
1098         spin_unlock_irq(&conf->resync_lock);
1099 }
1100
1101 static sector_t choose_data_offset(struct r10bio *r10_bio,
1102                                    struct md_rdev *rdev)
1103 {
1104         if (!test_bit(MD_RECOVERY_RESHAPE, &rdev->mddev->recovery) ||
1105             test_bit(R10BIO_Previous, &r10_bio->state))
1106                 return rdev->data_offset;
1107         else
1108                 return rdev->new_data_offset;
1109 }
1110
1111 struct raid10_plug_cb {
1112         struct blk_plug_cb      cb;
1113         struct bio_list         pending;
1114         int                     pending_cnt;
1115 };
1116
1117 static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
1118 {
1119         struct raid10_plug_cb *plug = container_of(cb, struct raid10_plug_cb,
1120                                                    cb);
1121         struct mddev *mddev = plug->cb.data;
1122         struct r10conf *conf = mddev->private;
1123         struct bio *bio;
1124
1125         if (from_schedule || current->bio_list) {
1126                 spin_lock_irq(&conf->device_lock);
1127                 bio_list_merge(&conf->pending_bio_list, &plug->pending);
1128                 conf->pending_count += plug->pending_cnt;
1129                 spin_unlock_irq(&conf->device_lock);
1130                 wake_up(&conf->wait_barrier);
1131                 md_wakeup_thread(mddev->thread);
1132                 kfree(plug);
1133                 return;
1134         }
1135
1136         /* we aren't scheduling, so we can do the write-out directly. */
1137         bio = bio_list_get(&plug->pending);
1138         bitmap_unplug(mddev->bitmap);
1139         wake_up(&conf->wait_barrier);
1140
1141         while (bio) { /* submit pending writes */
1142                 struct bio *next = bio->bi_next;
1143                 bio->bi_next = NULL;
1144                 if (unlikely((bio->bi_rw & REQ_DISCARD) &&
1145                     !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
1146                         /* Just ignore it */
1147                         bio_endio(bio, 0);
1148                 else
1149                         generic_make_request(bio);
1150                 bio = next;
1151         }
1152         kfree(plug);
1153 }
1154
1155 static void make_request(struct mddev *mddev, struct bio * bio)
1156 {
1157         struct r10conf *conf = mddev->private;
1158         struct r10bio *r10_bio;
1159         struct bio *read_bio;
1160         int i;
1161         sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask);
1162         int chunk_sects = chunk_mask + 1;
1163         const int rw = bio_data_dir(bio);
1164         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
1165         const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
1166         const unsigned long do_discard = (bio->bi_rw
1167                                           & (REQ_DISCARD | REQ_SECURE));
1168         const unsigned long do_same = (bio->bi_rw & REQ_WRITE_SAME);
1169         unsigned long flags;
1170         struct md_rdev *blocked_rdev;
1171         struct blk_plug_cb *cb;
1172         struct raid10_plug_cb *plug = NULL;
1173         int sectors_handled;
1174         int max_sectors;
1175         int sectors;
1176
1177         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
1178                 md_flush_request(mddev, bio);
1179                 return;
1180         }
1181
1182         /* If this request crosses a chunk boundary, we need to
1183          * split it.  This will only happen for 1 PAGE (or less) requests.
1184          */
1185         if (unlikely((bio->bi_sector & chunk_mask) + bio_sectors(bio)
1186                      > chunk_sects
1187                      && (conf->geo.near_copies < conf->geo.raid_disks
1188                          || conf->prev.near_copies < conf->prev.raid_disks))) {
1189                 struct bio_pair *bp;
1190                 /* Sanity check -- queue functions should prevent this happening */
1191                 if (bio_segments(bio) > 1)
1192                         goto bad_map;
1193                 /* This is a one page bio that upper layers
1194                  * refuse to split for us, so we need to split it.
1195                  */
1196                 bp = bio_split(bio,
1197                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
1198
1199                 /* Each of these 'make_request' calls will call 'wait_barrier'.
1200                  * If the first succeeds but the second blocks due to the resync
1201                  * thread raising the barrier, we will deadlock because the
1202                  * IO to the underlying device will be queued in generic_make_request
1203                  * and will never complete, so will never reduce nr_pending.
1204                  * So increment nr_waiting here so no new raise_barriers will
1205                  * succeed, and so the second wait_barrier cannot block.
1206                  */
1207                 spin_lock_irq(&conf->resync_lock);
1208                 conf->nr_waiting++;
1209                 spin_unlock_irq(&conf->resync_lock);
1210
1211                 make_request(mddev, &bp->bio1);
1212                 make_request(mddev, &bp->bio2);
1213
1214                 spin_lock_irq(&conf->resync_lock);
1215                 conf->nr_waiting--;
1216                 wake_up(&conf->wait_barrier);
1217                 spin_unlock_irq(&conf->resync_lock);
1218
1219                 bio_pair_release(bp);
1220                 return;
1221         bad_map:
1222                 printk("md/raid10:%s: make_request bug: can't convert block across chunks"
1223                        " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
1224                        (unsigned long long)bio->bi_sector, bio_sectors(bio) / 2);
1225
1226                 bio_io_error(bio);
1227                 return;
1228         }
1229
1230         md_write_start(mddev, bio);
1231
1232         /*
1233          * Register the new request and wait if the reconstruction
1234          * thread has put up a bar for new requests.
1235          * Continue immediately if no resync is active currently.
1236          */
1237         wait_barrier(conf);
1238
1239         sectors = bio_sectors(bio);
1240         while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1241             bio->bi_sector < conf->reshape_progress &&
1242             bio->bi_sector + sectors > conf->reshape_progress) {
1243                 /* IO spans the reshape position.  Need to wait for
1244                  * reshape to pass
1245                  */
1246                 allow_barrier(conf);
1247                 wait_event(conf->wait_barrier,
1248                            conf->reshape_progress <= bio->bi_sector ||
1249                            conf->reshape_progress >= bio->bi_sector + sectors);
1250                 wait_barrier(conf);
1251         }
1252         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1253             bio_data_dir(bio) == WRITE &&
1254             (mddev->reshape_backwards
1255              ? (bio->bi_sector < conf->reshape_safe &&
1256                 bio->bi_sector + sectors > conf->reshape_progress)
1257              : (bio->bi_sector + sectors > conf->reshape_safe &&
1258                 bio->bi_sector < conf->reshape_progress))) {
1259                 /* Need to update reshape_position in metadata */
1260                 mddev->reshape_position = conf->reshape_progress;
1261                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1262                 set_bit(MD_CHANGE_PENDING, &mddev->flags);
1263                 md_wakeup_thread(mddev->thread);
1264                 wait_event(mddev->sb_wait,
1265                            !test_bit(MD_CHANGE_PENDING, &mddev->flags));
1266
1267                 conf->reshape_safe = mddev->reshape_position;
1268         }
1269
1270         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1271
1272         r10_bio->master_bio = bio;
1273         r10_bio->sectors = sectors;
1274
1275         r10_bio->mddev = mddev;
1276         r10_bio->sector = bio->bi_sector;
1277         r10_bio->state = 0;
1278
1279         /* We might need to issue multiple reads to different
1280          * devices if there are bad blocks around, so we keep
1281          * track of the number of reads in bio->bi_phys_segments.
1282          * If this is 0, there is only one r10_bio and no locking
1283          * will be needed when the request completes.  If it is
1284          * non-zero, then it is the number of not-completed requests.
1285          */
1286         bio->bi_phys_segments = 0;
1287         clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1288
1289         if (rw == READ) {
1290                 /*
1291                  * read balancing logic:
1292                  */
1293                 struct md_rdev *rdev;
1294                 int slot;
1295
1296 read_again:
1297                 rdev = read_balance(conf, r10_bio, &max_sectors);
1298                 if (!rdev) {
1299                         raid_end_bio_io(r10_bio);
1300                         return;
1301                 }
1302                 slot = r10_bio->read_slot;
1303
1304                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1305                 bio_trim(read_bio, r10_bio->sector - bio->bi_sector,
1306                          max_sectors);
1307
1308                 r10_bio->devs[slot].bio = read_bio;
1309                 r10_bio->devs[slot].rdev = rdev;
1310
1311                 read_bio->bi_sector = r10_bio->devs[slot].addr +
1312                         choose_data_offset(r10_bio, rdev);
1313                 read_bio->bi_bdev = rdev->bdev;
1314                 read_bio->bi_end_io = raid10_end_read_request;
1315                 read_bio->bi_rw = READ | do_sync;
1316                 read_bio->bi_private = r10_bio;
1317
1318                 if (max_sectors < r10_bio->sectors) {
1319                         /* Could not read all from this device, so we will
1320                          * need another r10_bio.
1321                          */
1322                         sectors_handled = (r10_bio->sectors + max_sectors
1323                                            - bio->bi_sector);
1324                         r10_bio->sectors = max_sectors;
1325                         spin_lock_irq(&conf->device_lock);
1326                         if (bio->bi_phys_segments == 0)
1327                                 bio->bi_phys_segments = 2;
1328                         else
1329                                 bio->bi_phys_segments++;
1330                         spin_unlock(&conf->device_lock);
1331                         /* Cannot call generic_make_request directly
1332                          * as that will be queued in __generic_make_request
1333                          * and subsequent mempool_alloc might block
1334                          * waiting for it.  so hand bio over to raid10d.
1335                          */
1336                         reschedule_retry(r10_bio);
1337
1338                         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1339
1340                         r10_bio->master_bio = bio;
1341                         r10_bio->sectors = bio_sectors(bio) - sectors_handled;
1342                         r10_bio->state = 0;
1343                         r10_bio->mddev = mddev;
1344                         r10_bio->sector = bio->bi_sector + sectors_handled;
1345                         goto read_again;
1346                 } else
1347                         generic_make_request(read_bio);
1348                 return;
1349         }
1350
1351         /*
1352          * WRITE:
1353          */
1354         if (conf->pending_count >= max_queued_requests) {
1355                 md_wakeup_thread(mddev->thread);
1356                 wait_event(conf->wait_barrier,
1357                            conf->pending_count < max_queued_requests);
1358         }
1359         /* first select target devices under rcu_lock and
1360          * inc refcount on their rdev.  Record them by setting
1361          * bios[x] to bio
1362          * If there are known/acknowledged bad blocks on any device
1363          * on which we have seen a write error, we want to avoid
1364          * writing to those blocks.  This potentially requires several
1365          * writes to write around the bad blocks.  Each set of writes
1366          * gets its own r10_bio with a set of bios attached.  The number
1367          * of r10_bios is recored in bio->bi_phys_segments just as with
1368          * the read case.
1369          */
1370
1371         r10_bio->read_slot = -1; /* make sure repl_bio gets freed */
1372         raid10_find_phys(conf, r10_bio);
1373 retry_write:
1374         blocked_rdev = NULL;
1375         rcu_read_lock();
1376         max_sectors = r10_bio->sectors;
1377
1378         for (i = 0;  i < conf->copies; i++) {
1379                 int d = r10_bio->devs[i].devnum;
1380                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev);
1381                 struct md_rdev *rrdev = rcu_dereference(
1382                         conf->mirrors[d].replacement);
1383                 if (rdev == rrdev)
1384                         rrdev = NULL;
1385                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1386                         atomic_inc(&rdev->nr_pending);
1387                         blocked_rdev = rdev;
1388                         break;
1389                 }
1390                 if (rrdev && unlikely(test_bit(Blocked, &rrdev->flags))) {
1391                         atomic_inc(&rrdev->nr_pending);
1392                         blocked_rdev = rrdev;
1393                         break;
1394                 }
1395                 if (rdev && (test_bit(Faulty, &rdev->flags)
1396                              || test_bit(Unmerged, &rdev->flags)))
1397                         rdev = NULL;
1398                 if (rrdev && (test_bit(Faulty, &rrdev->flags)
1399                               || test_bit(Unmerged, &rrdev->flags)))
1400                         rrdev = NULL;
1401
1402                 r10_bio->devs[i].bio = NULL;
1403                 r10_bio->devs[i].repl_bio = NULL;
1404
1405                 if (!rdev && !rrdev) {
1406                         set_bit(R10BIO_Degraded, &r10_bio->state);
1407                         continue;
1408                 }
1409                 if (rdev && test_bit(WriteErrorSeen, &rdev->flags)) {
1410                         sector_t first_bad;
1411                         sector_t dev_sector = r10_bio->devs[i].addr;
1412                         int bad_sectors;
1413                         int is_bad;
1414
1415                         is_bad = is_badblock(rdev, dev_sector,
1416                                              max_sectors,
1417                                              &first_bad, &bad_sectors);
1418                         if (is_bad < 0) {
1419                                 /* Mustn't write here until the bad block
1420                                  * is acknowledged
1421                                  */
1422                                 atomic_inc(&rdev->nr_pending);
1423                                 set_bit(BlockedBadBlocks, &rdev->flags);
1424                                 blocked_rdev = rdev;
1425                                 break;
1426                         }
1427                         if (is_bad && first_bad <= dev_sector) {
1428                                 /* Cannot write here at all */
1429                                 bad_sectors -= (dev_sector - first_bad);
1430                                 if (bad_sectors < max_sectors)
1431                                         /* Mustn't write more than bad_sectors
1432                                          * to other devices yet
1433                                          */
1434                                         max_sectors = bad_sectors;
1435                                 /* We don't set R10BIO_Degraded as that
1436                                  * only applies if the disk is missing,
1437                                  * so it might be re-added, and we want to
1438                                  * know to recover this chunk.
1439                                  * In this case the device is here, and the
1440                                  * fact that this chunk is not in-sync is
1441                                  * recorded in the bad block log.
1442                                  */
1443                                 continue;
1444                         }
1445                         if (is_bad) {
1446                                 int good_sectors = first_bad - dev_sector;
1447                                 if (good_sectors < max_sectors)
1448                                         max_sectors = good_sectors;
1449                         }
1450                 }
1451                 if (rdev) {
1452                         r10_bio->devs[i].bio = bio;
1453                         atomic_inc(&rdev->nr_pending);
1454                 }
1455                 if (rrdev) {
1456                         r10_bio->devs[i].repl_bio = bio;
1457                         atomic_inc(&rrdev->nr_pending);
1458                 }
1459         }
1460         rcu_read_unlock();
1461
1462         if (unlikely(blocked_rdev)) {
1463                 /* Have to wait for this device to get unblocked, then retry */
1464                 int j;
1465                 int d;
1466
1467                 for (j = 0; j < i; j++) {
1468                         if (r10_bio->devs[j].bio) {
1469                                 d = r10_bio->devs[j].devnum;
1470                                 rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1471                         }
1472                         if (r10_bio->devs[j].repl_bio) {
1473                                 struct md_rdev *rdev;
1474                                 d = r10_bio->devs[j].devnum;
1475                                 rdev = conf->mirrors[d].replacement;
1476                                 if (!rdev) {
1477                                         /* Race with remove_disk */
1478                                         smp_mb();
1479                                         rdev = conf->mirrors[d].rdev;
1480                                 }
1481                                 rdev_dec_pending(rdev, mddev);
1482                         }
1483                 }
1484                 allow_barrier(conf);
1485                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
1486                 wait_barrier(conf);
1487                 goto retry_write;
1488         }
1489
1490         if (max_sectors < r10_bio->sectors) {
1491                 /* We are splitting this into multiple parts, so
1492                  * we need to prepare for allocating another r10_bio.
1493                  */
1494                 r10_bio->sectors = max_sectors;
1495                 spin_lock_irq(&conf->device_lock);
1496                 if (bio->bi_phys_segments == 0)
1497                         bio->bi_phys_segments = 2;
1498                 else
1499                         bio->bi_phys_segments++;
1500                 spin_unlock_irq(&conf->device_lock);
1501         }
1502         sectors_handled = r10_bio->sector + max_sectors - bio->bi_sector;
1503
1504         atomic_set(&r10_bio->remaining, 1);
1505         bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
1506
1507         for (i = 0; i < conf->copies; i++) {
1508                 struct bio *mbio;
1509                 int d = r10_bio->devs[i].devnum;
1510                 if (r10_bio->devs[i].bio) {
1511                         struct md_rdev *rdev = conf->mirrors[d].rdev;
1512                         mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1513                         bio_trim(mbio, r10_bio->sector - bio->bi_sector,
1514                                  max_sectors);
1515                         r10_bio->devs[i].bio = mbio;
1516
1517                         mbio->bi_sector = (r10_bio->devs[i].addr+
1518                                            choose_data_offset(r10_bio,
1519                                                               rdev));
1520                         mbio->bi_bdev = rdev->bdev;
1521                         mbio->bi_end_io = raid10_end_write_request;
1522                         mbio->bi_rw =
1523                                 WRITE | do_sync | do_fua | do_discard | do_same;
1524                         mbio->bi_private = r10_bio;
1525
1526                         atomic_inc(&r10_bio->remaining);
1527
1528                         cb = blk_check_plugged(raid10_unplug, mddev,
1529                                                sizeof(*plug));
1530                         if (cb)
1531                                 plug = container_of(cb, struct raid10_plug_cb,
1532                                                     cb);
1533                         else
1534                                 plug = NULL;
1535                         spin_lock_irqsave(&conf->device_lock, flags);
1536                         if (plug) {
1537                                 bio_list_add(&plug->pending, mbio);
1538                                 plug->pending_cnt++;
1539                         } else {
1540                                 bio_list_add(&conf->pending_bio_list, mbio);
1541                                 conf->pending_count++;
1542                         }
1543                         spin_unlock_irqrestore(&conf->device_lock, flags);
1544                         if (!plug)
1545                                 md_wakeup_thread(mddev->thread);
1546                 }
1547
1548                 if (r10_bio->devs[i].repl_bio) {
1549                         struct md_rdev *rdev = conf->mirrors[d].replacement;
1550                         if (rdev == NULL) {
1551                                 /* Replacement just got moved to main 'rdev' */
1552                                 smp_mb();
1553                                 rdev = conf->mirrors[d].rdev;
1554                         }
1555                         mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1556                         bio_trim(mbio, r10_bio->sector - bio->bi_sector,
1557                                  max_sectors);
1558                         r10_bio->devs[i].repl_bio = mbio;
1559
1560                         mbio->bi_sector = (r10_bio->devs[i].addr +
1561                                            choose_data_offset(
1562                                                    r10_bio, rdev));
1563                         mbio->bi_bdev = rdev->bdev;
1564                         mbio->bi_end_io = raid10_end_write_request;
1565                         mbio->bi_rw =
1566                                 WRITE | do_sync | do_fua | do_discard | do_same;
1567                         mbio->bi_private = r10_bio;
1568
1569                         atomic_inc(&r10_bio->remaining);
1570                         spin_lock_irqsave(&conf->device_lock, flags);
1571                         bio_list_add(&conf->pending_bio_list, mbio);
1572                         conf->pending_count++;
1573                         spin_unlock_irqrestore(&conf->device_lock, flags);
1574                         if (!mddev_check_plugged(mddev))
1575                                 md_wakeup_thread(mddev->thread);
1576                 }
1577         }
1578
1579         /* Don't remove the bias on 'remaining' (one_write_done) until
1580          * after checking if we need to go around again.
1581          */
1582
1583         if (sectors_handled < bio_sectors(bio)) {
1584                 one_write_done(r10_bio);
1585                 /* We need another r10_bio.  It has already been counted
1586                  * in bio->bi_phys_segments.
1587                  */
1588                 r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1589
1590                 r10_bio->master_bio = bio;
1591                 r10_bio->sectors = bio_sectors(bio) - sectors_handled;
1592
1593                 r10_bio->mddev = mddev;
1594                 r10_bio->sector = bio->bi_sector + sectors_handled;
1595                 r10_bio->state = 0;
1596                 goto retry_write;
1597         }
1598         one_write_done(r10_bio);
1599
1600         /* In case raid10d snuck in to freeze_array */
1601         wake_up(&conf->wait_barrier);
1602 }
1603
1604 static void status(struct seq_file *seq, struct mddev *mddev)
1605 {
1606         struct r10conf *conf = mddev->private;
1607         int i;
1608
1609         if (conf->geo.near_copies < conf->geo.raid_disks)
1610                 seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
1611         if (conf->geo.near_copies > 1)
1612                 seq_printf(seq, " %d near-copies", conf->geo.near_copies);
1613         if (conf->geo.far_copies > 1) {
1614                 if (conf->geo.far_offset)
1615                         seq_printf(seq, " %d offset-copies", conf->geo.far_copies);
1616                 else
1617                         seq_printf(seq, " %d far-copies", conf->geo.far_copies);
1618         }
1619         seq_printf(seq, " [%d/%d] [", conf->geo.raid_disks,
1620                                         conf->geo.raid_disks - mddev->degraded);
1621         for (i = 0; i < conf->geo.raid_disks; i++)
1622                 seq_printf(seq, "%s",
1623                               conf->mirrors[i].rdev &&
1624                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
1625         seq_printf(seq, "]");
1626 }
1627
1628 /* check if there are enough drives for
1629  * every block to appear on atleast one.
1630  * Don't consider the device numbered 'ignore'
1631  * as we might be about to remove it.
1632  */
1633 static int _enough(struct r10conf *conf, int previous, int ignore)
1634 {
1635         int first = 0;
1636         int has_enough = 0;
1637         int disks, ncopies;
1638         if (previous) {
1639                 disks = conf->prev.raid_disks;
1640                 ncopies = conf->prev.near_copies;
1641         } else {
1642                 disks = conf->geo.raid_disks;
1643                 ncopies = conf->geo.near_copies;
1644         }
1645
1646         rcu_read_lock();
1647         do {
1648                 int n = conf->copies;
1649                 int cnt = 0;
1650                 int this = first;
1651                 while (n--) {
1652                         struct md_rdev *rdev;
1653                         if (this != ignore &&
1654                             (rdev = rcu_dereference(conf->mirrors[this].rdev)) &&
1655                             test_bit(In_sync, &rdev->flags))
1656                                 cnt++;
1657                         this = (this+1) % disks;
1658                 }
1659                 if (cnt == 0)
1660                         goto out;
1661                 first = (first + ncopies) % disks;
1662         } while (first != 0);
1663         has_enough = 1;
1664 out:
1665         rcu_read_unlock();
1666         return has_enough;
1667 }
1668
1669 static int enough(struct r10conf *conf, int ignore)
1670 {
1671         /* when calling 'enough', both 'prev' and 'geo' must
1672          * be stable.
1673          * This is ensured if ->reconfig_mutex or ->device_lock
1674          * is held.
1675          */
1676         return _enough(conf, 0, ignore) &&
1677                 _enough(conf, 1, ignore);
1678 }
1679
1680 static void error(struct mddev *mddev, struct md_rdev *rdev)
1681 {
1682         char b[BDEVNAME_SIZE];
1683         struct r10conf *conf = mddev->private;
1684         unsigned long flags;
1685
1686         /*
1687          * If it is not operational, then we have already marked it as dead
1688          * else if it is the last working disks, ignore the error, let the
1689          * next level up know.
1690          * else mark the drive as failed
1691          */
1692         spin_lock_irqsave(&conf->device_lock, flags);
1693         if (test_bit(In_sync, &rdev->flags)
1694             && !enough(conf, rdev->raid_disk)) {
1695                 /*
1696                  * Don't fail the drive, just return an IO error.
1697                  */
1698                 spin_unlock_irqrestore(&conf->device_lock, flags);
1699                 return;
1700         }
1701         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1702                 mddev->degraded++;
1703                         /*
1704                  * if recovery is running, make sure it aborts.
1705                  */
1706                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1707         }
1708         set_bit(Blocked, &rdev->flags);
1709         set_bit(Faulty, &rdev->flags);
1710         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1711         spin_unlock_irqrestore(&conf->device_lock, flags);
1712         printk(KERN_ALERT
1713                "md/raid10:%s: Disk failure on %s, disabling device.\n"
1714                "md/raid10:%s: Operation continuing on %d devices.\n",
1715                mdname(mddev), bdevname(rdev->bdev, b),
1716                mdname(mddev), conf->geo.raid_disks - mddev->degraded);
1717 }
1718
1719 static void print_conf(struct r10conf *conf)
1720 {
1721         int i;
1722         struct raid10_info *tmp;
1723
1724         printk(KERN_DEBUG "RAID10 conf printout:\n");
1725         if (!conf) {
1726                 printk(KERN_DEBUG "(!conf)\n");
1727                 return;
1728         }
1729         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->geo.raid_disks - conf->mddev->degraded,
1730                 conf->geo.raid_disks);
1731
1732         for (i = 0; i < conf->geo.raid_disks; i++) {
1733                 char b[BDEVNAME_SIZE];
1734                 tmp = conf->mirrors + i;
1735                 if (tmp->rdev)
1736                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1737                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1738                                 !test_bit(Faulty, &tmp->rdev->flags),
1739                                 bdevname(tmp->rdev->bdev,b));
1740         }
1741 }
1742
1743 static void close_sync(struct r10conf *conf)
1744 {
1745         wait_barrier(conf);
1746         allow_barrier(conf);
1747
1748         mempool_destroy(conf->r10buf_pool);
1749         conf->r10buf_pool = NULL;
1750 }
1751
1752 static int raid10_spare_active(struct mddev *mddev)
1753 {
1754         int i;
1755         struct r10conf *conf = mddev->private;
1756         struct raid10_info *tmp;
1757         int count = 0;
1758         unsigned long flags;
1759
1760         /*
1761          * Find all non-in_sync disks within the RAID10 configuration
1762          * and mark them in_sync
1763          */
1764         for (i = 0; i < conf->geo.raid_disks; i++) {
1765                 tmp = conf->mirrors + i;
1766                 if (tmp->replacement
1767                     && tmp->replacement->recovery_offset == MaxSector
1768                     && !test_bit(Faulty, &tmp->replacement->flags)
1769                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
1770                         /* Replacement has just become active */
1771                         if (!tmp->rdev
1772                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
1773                                 count++;
1774                         if (tmp->rdev) {
1775                                 /* Replaced device not technically faulty,
1776                                  * but we need to be sure it gets removed
1777                                  * and never re-added.
1778                                  */
1779                                 set_bit(Faulty, &tmp->rdev->flags);
1780                                 sysfs_notify_dirent_safe(
1781                                         tmp->rdev->sysfs_state);
1782                         }
1783                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
1784                 } else if (tmp->rdev
1785                            && tmp->rdev->recovery_offset == MaxSector
1786                            && !test_bit(Faulty, &tmp->rdev->flags)
1787                            && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1788                         count++;
1789                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
1790                 }
1791         }
1792         spin_lock_irqsave(&conf->device_lock, flags);
1793         mddev->degraded -= count;
1794         spin_unlock_irqrestore(&conf->device_lock, flags);
1795
1796         print_conf(conf);
1797         return count;
1798 }
1799
1800
1801 static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1802 {
1803         struct r10conf *conf = mddev->private;
1804         int err = -EEXIST;
1805         int mirror;
1806         int first = 0;
1807         int last = conf->geo.raid_disks - 1;
1808         struct request_queue *q = bdev_get_queue(rdev->bdev);
1809
1810         if (mddev->recovery_cp < MaxSector)
1811                 /* only hot-add to in-sync arrays, as recovery is
1812                  * very different from resync
1813                  */
1814                 return -EBUSY;
1815         if (rdev->saved_raid_disk < 0 && !_enough(conf, 1, -1))
1816                 return -EINVAL;
1817
1818         if (rdev->raid_disk >= 0)
1819                 first = last = rdev->raid_disk;
1820
1821         if (q->merge_bvec_fn) {
1822                 set_bit(Unmerged, &rdev->flags);
1823                 mddev->merge_check_needed = 1;
1824         }
1825
1826         if (rdev->saved_raid_disk >= first &&
1827             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1828                 mirror = rdev->saved_raid_disk;
1829         else
1830                 mirror = first;
1831         for ( ; mirror <= last ; mirror++) {
1832                 struct raid10_info *p = &conf->mirrors[mirror];
1833                 if (p->recovery_disabled == mddev->recovery_disabled)
1834                         continue;
1835                 if (p->rdev) {
1836                         if (!test_bit(WantReplacement, &p->rdev->flags) ||
1837                             p->replacement != NULL)
1838                                 continue;
1839                         clear_bit(In_sync, &rdev->flags);
1840                         set_bit(Replacement, &rdev->flags);
1841                         rdev->raid_disk = mirror;
1842                         err = 0;
1843                         if (mddev->gendisk)
1844                                 disk_stack_limits(mddev->gendisk, rdev->bdev,
1845                                                   rdev->data_offset << 9);
1846                         conf->fullsync = 1;
1847                         rcu_assign_pointer(p->replacement, rdev);
1848                         break;
1849                 }
1850
1851                 if (mddev->gendisk)
1852                         disk_stack_limits(mddev->gendisk, rdev->bdev,
1853                                           rdev->data_offset << 9);
1854
1855                 p->head_position = 0;
1856                 p->recovery_disabled = mddev->recovery_disabled - 1;
1857                 rdev->raid_disk = mirror;
1858                 err = 0;
1859                 if (rdev->saved_raid_disk != mirror)
1860                         conf->fullsync = 1;
1861                 rcu_assign_pointer(p->rdev, rdev);
1862                 break;
1863         }
1864         if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
1865                 /* Some requests might not have seen this new
1866                  * merge_bvec_fn.  We must wait for them to complete
1867                  * before merging the device fully.
1868                  * First we make sure any code which has tested
1869                  * our function has submitted the request, then
1870                  * we wait for all outstanding requests to complete.
1871                  */
1872                 synchronize_sched();
1873                 freeze_array(conf, 0);
1874                 unfreeze_array(conf);
1875                 clear_bit(Unmerged, &rdev->flags);
1876         }
1877         md_integrity_add_rdev(rdev, mddev);
1878         if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
1879                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
1880
1881         print_conf(conf);
1882         return err;
1883 }
1884
1885 static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1886 {
1887         struct r10conf *conf = mddev->private;
1888         int err = 0;
1889         int number = rdev->raid_disk;
1890         struct md_rdev **rdevp;
1891         struct raid10_info *p = conf->mirrors + number;
1892
1893         print_conf(conf);
1894         if (rdev == p->rdev)
1895                 rdevp = &p->rdev;
1896         else if (rdev == p->replacement)
1897                 rdevp = &p->replacement;
1898         else
1899                 return 0;
1900
1901         if (test_bit(In_sync, &rdev->flags) ||
1902             atomic_read(&rdev->nr_pending)) {
1903                 err = -EBUSY;
1904                 goto abort;
1905         }
1906         /* Only remove faulty devices if recovery
1907          * is not possible.
1908          */
1909         if (!test_bit(Faulty, &rdev->flags) &&
1910             mddev->recovery_disabled != p->recovery_disabled &&
1911             (!p->replacement || p->replacement == rdev) &&
1912             number < conf->geo.raid_disks &&
1913             enough(conf, -1)) {
1914                 err = -EBUSY;
1915                 goto abort;
1916         }
1917         *rdevp = NULL;
1918         synchronize_rcu();
1919         if (atomic_read(&rdev->nr_pending)) {
1920                 /* lost the race, try later */
1921                 err = -EBUSY;
1922                 *rdevp = rdev;
1923                 goto abort;
1924         } else if (p->replacement) {
1925                 /* We must have just cleared 'rdev' */
1926                 p->rdev = p->replacement;
1927                 clear_bit(Replacement, &p->replacement->flags);
1928                 smp_mb(); /* Make sure other CPUs may see both as identical
1929                            * but will never see neither -- if they are careful.
1930                            */
1931                 p->replacement = NULL;
1932                 clear_bit(WantReplacement, &rdev->flags);
1933         } else
1934                 /* We might have just remove the Replacement as faulty
1935                  * Clear the flag just in case
1936                  */
1937                 clear_bit(WantReplacement, &rdev->flags);
1938
1939         err = md_integrity_register(mddev);
1940
1941 abort:
1942
1943         print_conf(conf);
1944         return err;
1945 }
1946
1947
1948 static void end_sync_read(struct bio *bio, int error)
1949 {
1950         struct r10bio *r10_bio = bio->bi_private;
1951         struct r10conf *conf = r10_bio->mddev->private;
1952         int d;
1953
1954         if (bio == r10_bio->master_bio) {
1955                 /* this is a reshape read */
1956                 d = r10_bio->read_slot; /* really the read dev */
1957         } else
1958                 d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
1959
1960         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1961                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1962         else
1963                 /* The write handler will notice the lack of
1964                  * R10BIO_Uptodate and record any errors etc
1965                  */
1966                 atomic_add(r10_bio->sectors,
1967                            &conf->mirrors[d].rdev->corrected_errors);
1968
1969         /* for reconstruct, we always reschedule after a read.
1970          * for resync, only after all reads
1971          */
1972         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1973         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1974             atomic_dec_and_test(&r10_bio->remaining)) {
1975                 /* we have read all the blocks,
1976                  * do the comparison in process context in raid10d
1977                  */
1978                 reschedule_retry(r10_bio);
1979         }
1980 }
1981
1982 static void end_sync_request(struct r10bio *r10_bio)
1983 {
1984         struct mddev *mddev = r10_bio->mddev;
1985
1986         while (atomic_dec_and_test(&r10_bio->remaining)) {
1987                 if (r10_bio->master_bio == NULL) {
1988                         /* the primary of several recovery bios */
1989                         sector_t s = r10_bio->sectors;
1990                         if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1991                             test_bit(R10BIO_WriteError, &r10_bio->state))
1992                                 reschedule_retry(r10_bio);
1993                         else
1994                                 put_buf(r10_bio);
1995                         md_done_sync(mddev, s, 1);
1996                         break;
1997                 } else {
1998                         struct r10bio *r10_bio2 = (struct r10bio *)r10_bio->master_bio;
1999                         if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
2000                             test_bit(R10BIO_WriteError, &r10_bio->state))
2001                                 reschedule_retry(r10_bio);
2002                         else
2003                                 put_buf(r10_bio);
2004                         r10_bio = r10_bio2;
2005                 }
2006         }
2007 }
2008
2009 static void end_sync_write(struct bio *bio, int error)
2010 {
2011         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
2012         struct r10bio *r10_bio = bio->bi_private;
2013         struct mddev *mddev = r10_bio->mddev;
2014         struct r10conf *conf = mddev->private;
2015         int d;
2016         sector_t first_bad;
2017         int bad_sectors;
2018         int slot;
2019         int repl;
2020         struct md_rdev *rdev = NULL;
2021
2022         d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
2023         if (repl)
2024                 rdev = conf->mirrors[d].replacement;
2025         else
2026                 rdev = conf->mirrors[d].rdev;
2027
2028         if (!uptodate) {
2029                 if (repl)
2030                         md_error(mddev, rdev);
2031                 else {
2032                         set_bit(WriteErrorSeen, &rdev->flags);
2033                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2034                                 set_bit(MD_RECOVERY_NEEDED,
2035                                         &rdev->mddev->recovery);
2036                         set_bit(R10BIO_WriteError, &r10_bio->state);
2037                 }
2038         } else if (is_badblock(rdev,
2039                              r10_bio->devs[slot].addr,
2040                              r10_bio->sectors,
2041                              &first_bad, &bad_sectors))
2042                 set_bit(R10BIO_MadeGood, &r10_bio->state);
2043
2044         rdev_dec_pending(rdev, mddev);
2045
2046         end_sync_request(r10_bio);
2047 }
2048
2049 /*
2050  * Note: sync and recover and handled very differently for raid10
2051  * This code is for resync.
2052  * For resync, we read through virtual addresses and read all blocks.
2053  * If there is any error, we schedule a write.  The lowest numbered
2054  * drive is authoritative.
2055  * However requests come for physical address, so we need to map.
2056  * For every physical address there are raid_disks/copies virtual addresses,
2057  * which is always are least one, but is not necessarly an integer.
2058  * This means that a physical address can span multiple chunks, so we may
2059  * have to submit multiple io requests for a single sync request.
2060  */
2061 /*
2062  * We check if all blocks are in-sync and only write to blocks that
2063  * aren't in sync
2064  */
2065 static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
2066 {
2067         struct r10conf *conf = mddev->private;
2068         int i, first;
2069         struct bio *tbio, *fbio;
2070         int vcnt;
2071
2072         atomic_set(&r10_bio->remaining, 1);
2073
2074         /* find the first device with a block */
2075         for (i=0; i<conf->copies; i++)
2076                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
2077                         break;
2078
2079         if (i == conf->copies)
2080                 goto done;
2081
2082         first = i;
2083         fbio = r10_bio->devs[i].bio;
2084
2085         vcnt = (r10_bio->sectors + (PAGE_SIZE >> 9) - 1) >> (PAGE_SHIFT - 9);
2086         /* now find blocks with errors */
2087         for (i=0 ; i < conf->copies ; i++) {
2088                 int  j, d;
2089
2090                 tbio = r10_bio->devs[i].bio;
2091
2092                 if (tbio->bi_end_io != end_sync_read)
2093                         continue;
2094                 if (i == first)
2095                         continue;
2096                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
2097                         /* We know that the bi_io_vec layout is the same for
2098                          * both 'first' and 'i', so we just compare them.
2099                          * All vec entries are PAGE_SIZE;
2100                          */
2101                         int sectors = r10_bio->sectors;
2102                         for (j = 0; j < vcnt; j++) {
2103                                 int len = PAGE_SIZE;
2104                                 if (sectors < (len / 512))
2105                                         len = sectors * 512;
2106                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
2107                                            page_address(tbio->bi_io_vec[j].bv_page),
2108                                            len))
2109                                         break;
2110                                 sectors -= len/512;
2111                         }
2112                         if (j == vcnt)
2113                                 continue;
2114                         atomic64_add(r10_bio->sectors, &mddev->resync_mismatches);
2115                         if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
2116                                 /* Don't fix anything. */
2117                                 continue;
2118                 }
2119                 /* Ok, we need to write this bio, either to correct an
2120                  * inconsistency or to correct an unreadable block.
2121                  * First we need to fixup bv_offset, bv_len and
2122                  * bi_vecs, as the read request might have corrupted these
2123                  */
2124                 bio_reset(tbio);
2125
2126                 tbio->bi_vcnt = vcnt;
2127                 tbio->bi_size = r10_bio->sectors << 9;
2128                 tbio->bi_rw = WRITE;
2129                 tbio->bi_private = r10_bio;
2130                 tbio->bi_sector = r10_bio->devs[i].addr;
2131
2132                 for (j=0; j < vcnt ; j++) {
2133                         tbio->bi_io_vec[j].bv_offset = 0;
2134                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
2135
2136                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2137                                page_address(fbio->bi_io_vec[j].bv_page),
2138                                PAGE_SIZE);
2139                 }
2140                 tbio->bi_end_io = end_sync_write;
2141
2142                 d = r10_bio->devs[i].devnum;
2143                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2144                 atomic_inc(&r10_bio->remaining);
2145                 md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(tbio));
2146
2147                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
2148                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
2149                 generic_make_request(tbio);
2150         }
2151
2152         /* Now write out to any replacement devices
2153          * that are active
2154          */
2155         for (i = 0; i < conf->copies; i++) {
2156                 int j, d;
2157
2158                 tbio = r10_bio->devs[i].repl_bio;
2159                 if (!tbio || !tbio->bi_end_io)
2160                         continue;
2161                 if (r10_bio->devs[i].bio->bi_end_io != end_sync_write
2162                     && r10_bio->devs[i].bio != fbio)
2163                         for (j = 0; j < vcnt; j++)
2164                                 memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2165                                        page_address(fbio->bi_io_vec[j].bv_page),
2166                                        PAGE_SIZE);
2167                 d = r10_bio->devs[i].devnum;
2168                 atomic_inc(&r10_bio->remaining);
2169                 md_sync_acct(conf->mirrors[d].replacement->bdev,
2170                              bio_sectors(tbio));
2171                 generic_make_request(tbio);
2172         }
2173
2174 done:
2175         if (atomic_dec_and_test(&r10_bio->remaining)) {
2176                 md_done_sync(mddev, r10_bio->sectors, 1);
2177                 put_buf(r10_bio);
2178         }
2179 }
2180
2181 /*
2182  * Now for the recovery code.
2183  * Recovery happens across physical sectors.
2184  * We recover all non-is_sync drives by finding the virtual address of
2185  * each, and then choose a working drive that also has that virt address.
2186  * There is a separate r10_bio for each non-in_sync drive.
2187  * Only the first two slots are in use. The first for reading,
2188  * The second for writing.
2189  *
2190  */
2191 static void fix_recovery_read_error(struct r10bio *r10_bio)
2192 {
2193         /* We got a read error during recovery.
2194          * We repeat the read in smaller page-sized sections.
2195          * If a read succeeds, write it to the new device or record
2196          * a bad block if we cannot.
2197          * If a read fails, record a bad block on both old and
2198          * new devices.
2199          */
2200         struct mddev *mddev = r10_bio->mddev;
2201         struct r10conf *conf = mddev->private;
2202         struct bio *bio = r10_bio->devs[0].bio;
2203         sector_t sect = 0;
2204         int sectors = r10_bio->sectors;
2205         int idx = 0;
2206         int dr = r10_bio->devs[0].devnum;
2207         int dw = r10_bio->devs[1].devnum;
2208
2209         while (sectors) {
2210                 int s = sectors;
2211                 struct md_rdev *rdev;
2212                 sector_t addr;
2213                 int ok;
2214
2215                 if (s > (PAGE_SIZE>>9))
2216                         s = PAGE_SIZE >> 9;
2217
2218                 rdev = conf->mirrors[dr].rdev;
2219                 addr = r10_bio->devs[0].addr + sect,
2220                 ok = sync_page_io(rdev,
2221                                   addr,
2222                                   s << 9,
2223                                   bio->bi_io_vec[idx].bv_page,
2224                                   READ, false);
2225                 if (ok) {
2226                         rdev = conf->mirrors[dw].rdev;
2227                         addr = r10_bio->devs[1].addr + sect;
2228                         ok = sync_page_io(rdev,
2229                                           addr,
2230                                           s << 9,
2231                                           bio->bi_io_vec[idx].bv_page,
2232                                           WRITE, false);
2233                         if (!ok) {
2234                                 set_bit(WriteErrorSeen, &rdev->flags);
2235                                 if (!test_and_set_bit(WantReplacement,
2236                                                       &rdev->flags))
2237                                         set_bit(MD_RECOVERY_NEEDED,
2238                                                 &rdev->mddev->recovery);
2239                         }
2240                 }
2241                 if (!ok) {
2242                         /* We don't worry if we cannot set a bad block -
2243                          * it really is bad so there is no loss in not
2244                          * recording it yet
2245                          */
2246                         rdev_set_badblocks(rdev, addr, s, 0);
2247
2248                         if (rdev != conf->mirrors[dw].rdev) {
2249                                 /* need bad block on destination too */
2250                                 struct md_rdev *rdev2 = conf->mirrors[dw].rdev;
2251                                 addr = r10_bio->devs[1].addr + sect;
2252                                 ok = rdev_set_badblocks(rdev2, addr, s, 0);
2253                                 if (!ok) {
2254                                         /* just abort the recovery */
2255                                         printk(KERN_NOTICE
2256                                                "md/raid10:%s: recovery aborted"
2257                                                " due to read error\n",
2258                                                mdname(mddev));
2259
2260                                         conf->mirrors[dw].recovery_disabled
2261                                                 = mddev->recovery_disabled;
2262                                         set_bit(MD_RECOVERY_INTR,
2263                                                 &mddev->recovery);
2264                                         break;
2265                                 }
2266                         }
2267                 }
2268
2269                 sectors -= s;
2270                 sect += s;
2271                 idx++;
2272         }
2273 }
2274
2275 static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
2276 {
2277         struct r10conf *conf = mddev->private;
2278         int d;
2279         struct bio *wbio, *wbio2;
2280
2281         if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
2282                 fix_recovery_read_error(r10_bio);
2283                 end_sync_request(r10_bio);
2284                 return;
2285         }
2286
2287         /*
2288          * share the pages with the first bio
2289          * and submit the write request
2290          */
2291         d = r10_bio->devs[1].devnum;
2292         wbio = r10_bio->devs[1].bio;
2293         wbio2 = r10_bio->devs[1].repl_bio;
2294         /* Need to test wbio2->bi_end_io before we call
2295          * generic_make_request as if the former is NULL,
2296          * the latter is free to free wbio2.
2297          */
2298         if (wbio2 && !wbio2->bi_end_io)
2299                 wbio2 = NULL;
2300         if (wbio->bi_end_io) {
2301                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2302                 md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));
2303                 generic_make_request(wbio);
2304         }
2305         if (wbio2) {
2306                 atomic_inc(&conf->mirrors[d].replacement->nr_pending);
2307                 md_sync_acct(conf->mirrors[d].replacement->bdev,
2308                              bio_sectors(wbio2));
2309                 generic_make_request(wbio2);
2310         }
2311 }
2312
2313
2314 /*
2315  * Used by fix_read_error() to decay the per rdev read_errors.
2316  * We halve the read error count for every hour that has elapsed
2317  * since the last recorded read error.
2318  *
2319  */
2320 static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev)
2321 {
2322         struct timespec cur_time_mon;
2323         unsigned long hours_since_last;
2324         unsigned int read_errors = atomic_read(&rdev->read_errors);
2325
2326         ktime_get_ts(&cur_time_mon);
2327
2328         if (rdev->last_read_error.tv_sec == 0 &&
2329             rdev->last_read_error.tv_nsec == 0) {
2330                 /* first time we've seen a read error */
2331                 rdev->last_read_error = cur_time_mon;
2332                 return;
2333         }
2334
2335         hours_since_last = (cur_time_mon.tv_sec -
2336                             rdev->last_read_error.tv_sec) / 3600;
2337
2338         rdev->last_read_error = cur_time_mon;
2339
2340         /*
2341          * if hours_since_last is > the number of bits in read_errors
2342          * just set read errors to 0. We do this to avoid
2343          * overflowing the shift of read_errors by hours_since_last.
2344          */
2345         if (hours_since_last >= 8 * sizeof(read_errors))
2346                 atomic_set(&rdev->read_errors, 0);
2347         else
2348                 atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
2349 }
2350
2351 static int r10_sync_page_io(struct md_rdev *rdev, sector_t sector,
2352                             int sectors, struct page *page, int rw)
2353 {
2354         sector_t first_bad;
2355         int bad_sectors;
2356
2357         if (is_badblock(rdev, sector, sectors, &first_bad, &bad_sectors)
2358             && (rw == READ || test_bit(WriteErrorSeen, &rdev->flags)))
2359                 return -1;
2360         if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
2361                 /* success */
2362                 return 1;
2363         if (rw == WRITE) {
2364                 set_bit(WriteErrorSeen, &rdev->flags);
2365                 if (!test_and_set_bit(WantReplacement, &rdev->flags))
2366                         set_bit(MD_RECOVERY_NEEDED,
2367                                 &rdev->mddev->recovery);
2368         }
2369         /* need to record an error - either for the block or the device */
2370         if (!rdev_set_badblocks(rdev, sector, sectors, 0))
2371                 md_error(rdev->mddev, rdev);
2372         return 0;
2373 }
2374
2375 /*
2376  * This is a kernel thread which:
2377  *
2378  *      1.      Retries failed read operations on working mirrors.
2379  *      2.      Updates the raid superblock when problems encounter.
2380  *      3.      Performs writes following reads for array synchronising.
2381  */
2382
2383 static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10bio *r10_bio)
2384 {
2385         int sect = 0; /* Offset from r10_bio->sector */
2386         int sectors = r10_bio->sectors;
2387         struct md_rdev*rdev;
2388         int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
2389         int d = r10_bio->devs[r10_bio->read_slot].devnum;
2390
2391         /* still own a reference to this rdev, so it cannot
2392          * have been cleared recently.
2393          */
2394         rdev = conf->mirrors[d].rdev;
2395
2396         if (test_bit(Faulty, &rdev->flags))
2397                 /* drive has already been failed, just ignore any
2398                    more fix_read_error() attempts */
2399                 return;
2400
2401         check_decay_read_errors(mddev, rdev);
2402         atomic_inc(&rdev->read_errors);
2403         if (atomic_read(&rdev->read_errors) > max_read_errors) {
2404                 char b[BDEVNAME_SIZE];
2405                 bdevname(rdev->bdev, b);
2406
2407                 printk(KERN_NOTICE
2408                        "md/raid10:%s: %s: Raid device exceeded "
2409                        "read_error threshold [cur %d:max %d]\n",
2410                        mdname(mddev), b,
2411                        atomic_read(&rdev->read_errors), max_read_errors);
2412                 printk(KERN_NOTICE
2413                        "md/raid10:%s: %s: Failing raid device\n",
2414                        mdname(mddev), b);
2415                 md_error(mddev, conf->mirrors[d].rdev);
2416                 r10_bio->devs[r10_bio->read_slot].bio = IO_BLOCKED;
2417                 return;
2418         }
2419
2420         while(sectors) {
2421                 int s = sectors;
2422                 int sl = r10_bio->read_slot;
2423                 int success = 0;
2424                 int start;
2425
2426                 if (s > (PAGE_SIZE>>9))
2427                         s = PAGE_SIZE >> 9;
2428
2429                 rcu_read_lock();
2430                 do {
2431                         sector_t first_bad;
2432                         int bad_sectors;
2433
2434                         d = r10_bio->devs[sl].devnum;
2435                         rdev = rcu_dereference(conf->mirrors[d].rdev);
2436                         if (rdev &&
2437                             !test_bit(Unmerged, &rdev->flags) &&
2438                             test_bit(In_sync, &rdev->flags) &&
2439                             is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
2440                                         &first_bad, &bad_sectors) == 0) {
2441                                 atomic_inc(&rdev->nr_pending);
2442                                 rcu_read_unlock();
2443                                 success = sync_page_io(rdev,
2444                                                        r10_bio->devs[sl].addr +
2445                                                        sect,
2446                                                        s<<9,
2447                                                        conf->tmppage, READ, false);
2448                                 rdev_dec_pending(rdev, mddev);
2449                                 rcu_read_lock();
2450                                 if (success)
2451                                         break;
2452                         }
2453                         sl++;
2454                         if (sl == conf->copies)
2455                                 sl = 0;
2456                 } while (!success && sl != r10_bio->read_slot);
2457                 rcu_read_unlock();
2458
2459                 if (!success) {
2460                         /* Cannot read from anywhere, just mark the block
2461                          * as bad on the first device to discourage future
2462                          * reads.
2463                          */
2464                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
2465                         rdev = conf->mirrors[dn].rdev;
2466
2467                         if (!rdev_set_badblocks(
2468                                     rdev,
2469                                     r10_bio->devs[r10_bio->read_slot].addr
2470                                     + sect,
2471                                     s, 0)) {
2472                                 md_error(mddev, rdev);
2473                                 r10_bio->devs[r10_bio->read_slot].bio
2474                                         = IO_BLOCKED;
2475                         }
2476                         break;
2477                 }
2478
2479                 start = sl;
2480                 /* write it back and re-read */
2481                 rcu_read_lock();
2482                 while (sl != r10_bio->read_slot) {
2483                         char b[BDEVNAME_SIZE];
2484
2485                         if (sl==0)
2486                                 sl = conf->copies;
2487                         sl--;
2488                         d = r10_bio->devs[sl].devnum;
2489                         rdev = rcu_dereference(conf->mirrors[d].rdev);
2490                         if (!rdev ||
2491                             test_bit(Unmerged, &rdev->flags) ||
2492                             !test_bit(In_sync, &rdev->flags))
2493                                 continue;
2494
2495                         atomic_inc(&rdev->nr_pending);
2496                         rcu_read_unlock();
2497                         if (r10_sync_page_io(rdev,
2498                                              r10_bio->devs[sl].addr +
2499                                              sect,
2500                                              s, conf->tmppage, WRITE)
2501                             == 0) {
2502                                 /* Well, this device is dead */
2503                                 printk(KERN_NOTICE
2504                                        "md/raid10:%s: read correction "
2505                                        "write failed"
2506                                        " (%d sectors at %llu on %s)\n",
2507                                        mdname(mddev), s,
2508                                        (unsigned long long)(
2509                                                sect +
2510                                                choose_data_offset(r10_bio,
2511                                                                   rdev)),
2512                                        bdevname(rdev->bdev, b));
2513                                 printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2514                                        "drive\n",
2515                                        mdname(mddev),
2516                                        bdevname(rdev->bdev, b));
2517                         }
2518                         rdev_dec_pending(rdev, mddev);
2519                         rcu_read_lock();
2520                 }
2521                 sl = start;
2522                 while (sl != r10_bio->read_slot) {
2523                         char b[BDEVNAME_SIZE];
2524
2525                         if (sl==0)
2526                                 sl = conf->copies;
2527                         sl--;
2528                         d = r10_bio->devs[sl].devnum;
2529                         rdev = rcu_dereference(conf->mirrors[d].rdev);
2530                         if (!rdev ||
2531                             !test_bit(In_sync, &rdev->flags))
2532                                 continue;
2533
2534                         atomic_inc(&rdev->nr_pending);
2535                         rcu_read_unlock();
2536                         switch (r10_sync_page_io(rdev,
2537                                              r10_bio->devs[sl].addr +
2538                                              sect,
2539                                              s, conf->tmppage,
2540                                                  READ)) {
2541                         case 0:
2542                                 /* Well, this device is dead */
2543                                 printk(KERN_NOTICE
2544                                        "md/raid10:%s: unable to read back "
2545                                        "corrected sectors"
2546                                        " (%d sectors at %llu on %s)\n",
2547                                        mdname(mddev), s,
2548                                        (unsigned long long)(
2549                                                sect +
2550                                                choose_data_offset(r10_bio, rdev)),
2551                                        bdevname(rdev->bdev, b));
2552                                 printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2553                                        "drive\n",
2554                                        mdname(mddev),
2555                                        bdevname(rdev->bdev, b));
2556                                 break;
2557                         case 1:
2558                                 printk(KERN_INFO
2559                                        "md/raid10:%s: read error corrected"
2560                                        " (%d sectors at %llu on %s)\n",
2561                                        mdname(mddev), s,
2562                                        (unsigned long long)(
2563                                                sect +
2564                                                choose_data_offset(r10_bio, rdev)),
2565                                        bdevname(rdev->bdev, b));
2566                                 atomic_add(s, &rdev->corrected_errors);
2567                         }
2568
2569                         rdev_dec_pending(rdev, mddev);
2570                         rcu_read_lock();
2571                 }
2572                 rcu_read_unlock();
2573
2574                 sectors -= s;
2575                 sect += s;
2576         }
2577 }
2578
2579 static int narrow_write_error(struct r10bio *r10_bio, int i)
2580 {
2581         struct bio *bio = r10_bio->master_bio;
2582         struct mddev *mddev = r10_bio->mddev;
2583         struct r10conf *conf = mddev->private;
2584         struct md_rdev *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
2585         /* bio has the data to be written to slot 'i' where
2586          * we just recently had a write error.
2587          * We repeatedly clone the bio and trim down to one block,
2588          * then try the write.  Where the write fails we record
2589          * a bad block.
2590          * It is conceivable that the bio doesn't exactly align with
2591          * blocks.  We must handle this.
2592          *
2593          * We currently own a reference to the rdev.
2594          */
2595
2596         int block_sectors;
2597         sector_t sector;
2598         int sectors;
2599         int sect_to_write = r10_bio->sectors;
2600         int ok = 1;
2601
2602         if (rdev->badblocks.shift < 0)
2603                 return 0;
2604
2605         block_sectors = 1 << rdev->badblocks.shift;
2606         sector = r10_bio->sector;
2607         sectors = ((r10_bio->sector + block_sectors)
2608                    & ~(sector_t)(block_sectors - 1))
2609                 - sector;
2610
2611         while (sect_to_write) {
2612                 struct bio *wbio;
2613                 if (sectors > sect_to_write)
2614                         sectors = sect_to_write;
2615                 /* Write at 'sector' for 'sectors' */
2616                 wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
2617                 bio_trim(wbio, sector - bio->bi_sector, sectors);
2618                 wbio->bi_sector = (r10_bio->devs[i].addr+
2619                                    choose_data_offset(r10_bio, rdev) +
2620                                    (sector - r10_bio->sector));
2621                 wbio->bi_bdev = rdev->bdev;
2622                 if (submit_bio_wait(WRITE, wbio) == 0)
2623                         /* Failure! */
2624                         ok = rdev_set_badblocks(rdev, sector,
2625                                                 sectors, 0)
2626                                 && ok;
2627
2628                 bio_put(wbio);
2629                 sect_to_write -= sectors;
2630                 sector += sectors;
2631                 sectors = block_sectors;
2632         }
2633         return ok;
2634 }
2635
2636 static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
2637 {
2638         int slot = r10_bio->read_slot;
2639         struct bio *bio;
2640         struct r10conf *conf = mddev->private;
2641         struct md_rdev *rdev = r10_bio->devs[slot].rdev;
2642         char b[BDEVNAME_SIZE];
2643         unsigned long do_sync;
2644         int max_sectors;
2645
2646         /* we got a read error. Maybe the drive is bad.  Maybe just
2647          * the block and we can fix it.
2648          * We freeze all other IO, and try reading the block from
2649          * other devices.  When we find one, we re-write
2650          * and check it that fixes the read error.
2651          * This is all done synchronously while the array is
2652          * frozen.
2653          */
2654         bio = r10_bio->devs[slot].bio;
2655         bdevname(bio->bi_bdev, b);
2656         bio_put(bio);
2657         r10_bio->devs[slot].bio = NULL;
2658
2659         if (mddev->ro == 0) {
2660                 freeze_array(conf, 1);
2661                 fix_read_error(conf, mddev, r10_bio);
2662                 unfreeze_array(conf);
2663         } else
2664                 r10_bio->devs[slot].bio = IO_BLOCKED;
2665
2666         rdev_dec_pending(rdev, mddev);
2667
2668 read_more:
2669         rdev = read_balance(conf, r10_bio, &max_sectors);
2670         if (rdev == NULL) {
2671                 printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
2672                        " read error for block %llu\n",
2673                        mdname(mddev), b,
2674                        (unsigned long long)r10_bio->sector);
2675                 raid_end_bio_io(r10_bio);
2676                 return;
2677         }
2678
2679         do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
2680         slot = r10_bio->read_slot;
2681         printk_ratelimited(
2682                 KERN_ERR
2683                 "md/raid10:%s: %s: redirecting "
2684                 "sector %llu to another mirror\n",
2685                 mdname(mddev),
2686                 bdevname(rdev->bdev, b),
2687                 (unsigned long long)r10_bio->sector);
2688         bio = bio_clone_mddev(r10_bio->master_bio,
2689                               GFP_NOIO, mddev);
2690         bio_trim(bio, r10_bio->sector - bio->bi_sector, max_sectors);
2691         r10_bio->devs[slot].bio = bio;
2692         r10_bio->devs[slot].rdev = rdev;
2693         bio->bi_sector = r10_bio->devs[slot].addr
2694                 + choose_data_offset(r10_bio, rdev);
2695         bio->bi_bdev = rdev->bdev;
2696         bio->bi_rw = READ | do_sync;
2697         bio->bi_private = r10_bio;
2698         bio->bi_end_io = raid10_end_read_request;
2699         if (max_sectors < r10_bio->sectors) {
2700                 /* Drat - have to split this up more */
2701                 struct bio *mbio = r10_bio->master_bio;
2702                 int sectors_handled =
2703                         r10_bio->sector + max_sectors
2704                         - mbio->bi_sector;
2705                 r10_bio->sectors = max_sectors;
2706                 spin_lock_irq(&conf->device_lock);
2707                 if (mbio->bi_phys_segments == 0)
2708                         mbio->bi_phys_segments = 2;
2709                 else
2710                         mbio->bi_phys_segments++;
2711                 spin_unlock_irq(&conf->device_lock);
2712                 generic_make_request(bio);
2713
2714                 r10_bio = mempool_alloc(conf->r10bio_pool,
2715                                         GFP_NOIO);
2716                 r10_bio->master_bio = mbio;
2717                 r10_bio->sectors = bio_sectors(mbio) - sectors_handled;
2718                 r10_bio->state = 0;
2719                 set_bit(R10BIO_ReadError,
2720                         &r10_bio->state);
2721                 r10_bio->mddev = mddev;
2722                 r10_bio->sector = mbio->bi_sector
2723                         + sectors_handled;
2724
2725                 goto read_more;
2726         } else
2727                 generic_make_request(bio);
2728 }
2729
2730 static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
2731 {
2732         /* Some sort of write request has finished and it
2733          * succeeded in writing where we thought there was a
2734          * bad block.  So forget the bad block.
2735          * Or possibly if failed and we need to record
2736          * a bad block.
2737          */
2738         int m;
2739         struct md_rdev *rdev;
2740
2741         if (test_bit(R10BIO_IsSync, &r10_bio->state) ||
2742             test_bit(R10BIO_IsRecover, &r10_bio->state)) {
2743                 for (m = 0; m < conf->copies; m++) {
2744                         int dev = r10_bio->devs[m].devnum;
2745                         rdev = conf->mirrors[dev].rdev;
2746                         if (r10_bio->devs[m].bio == NULL)
2747                                 continue;
2748                         if (test_bit(BIO_UPTODATE,
2749                                      &r10_bio->devs[m].bio->bi_flags)) {
2750                                 rdev_clear_badblocks(
2751                                         rdev,
2752                                         r10_bio->devs[m].addr,
2753                                         r10_bio->sectors, 0);
2754                         } else {
2755                                 if (!rdev_set_badblocks(
2756                                             rdev,
2757                                             r10_bio->devs[m].addr,
2758                                             r10_bio->sectors, 0))
2759                                         md_error(conf->mddev, rdev);
2760                         }
2761                         rdev = conf->mirrors[dev].replacement;
2762                         if (r10_bio->devs[m].repl_bio == NULL)
2763                                 continue;
2764                         if (test_bit(BIO_UPTODATE,
2765                                      &r10_bio->devs[m].repl_bio->bi_flags)) {
2766                                 rdev_clear_badblocks(
2767                                         rdev,
2768                                         r10_bio->devs[m].addr,
2769                                         r10_bio->sectors, 0);
2770                         } else {
2771                                 if (!rdev_set_badblocks(
2772                                             rdev,
2773                                             r10_bio->devs[m].addr,
2774                                             r10_bio->sectors, 0))
2775                                         md_error(conf->mddev, rdev);
2776                         }
2777                 }
2778                 put_buf(r10_bio);
2779         } else {
2780                 for (m = 0; m < conf->copies; m++) {
2781                         int dev = r10_bio->devs[m].devnum;
2782                         struct bio *bio = r10_bio->devs[m].bio;
2783                         rdev = conf->mirrors[dev].rdev;
2784                         if (bio == IO_MADE_GOOD) {
2785                                 rdev_clear_badblocks(
2786                                         rdev,
2787                                         r10_bio->devs[m].addr,
2788                                         r10_bio->sectors, 0);
2789                                 rdev_dec_pending(rdev, conf->mddev);
2790                         } else if (bio != NULL &&
2791                                    !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
2792                                 if (!narrow_write_error(r10_bio, m)) {
2793                                         md_error(conf->mddev, rdev);
2794                                         set_bit(R10BIO_Degraded,
2795                                                 &r10_bio->state);
2796                                 }
2797                                 rdev_dec_pending(rdev, conf->mddev);
2798                         }
2799                         bio = r10_bio->devs[m].repl_bio;
2800                         rdev = conf->mirrors[dev].replacement;
2801                         if (rdev && bio == IO_MADE_GOOD) {
2802                                 rdev_clear_badblocks(
2803                                         rdev,
2804                                         r10_bio->devs[m].addr,
2805                                         r10_bio->sectors, 0);
2806                                 rdev_dec_pending(rdev, conf->mddev);
2807                         }
2808                 }
2809                 if (test_bit(R10BIO_WriteError,
2810                              &r10_bio->state))
2811                         close_write(r10_bio);
2812                 raid_end_bio_io(r10_bio);
2813         }
2814 }
2815
2816 static void raid10d(struct md_thread *thread)
2817 {
2818         struct mddev *mddev = thread->mddev;
2819         struct r10bio *r10_bio;
2820         unsigned long flags;
2821         struct r10conf *conf = mddev->private;
2822         struct list_head *head = &conf->retry_list;
2823         struct blk_plug plug;
2824
2825         md_check_recovery(mddev);
2826
2827         blk_start_plug(&plug);
2828         for (;;) {
2829
2830                 flush_pending_writes(conf);
2831
2832                 spin_lock_irqsave(&conf->device_lock, flags);
2833                 if (list_empty(head)) {
2834                         spin_unlock_irqrestore(&conf->device_lock, flags);
2835                         break;
2836                 }
2837                 r10_bio = list_entry(head->prev, struct r10bio, retry_list);
2838                 list_del(head->prev);
2839                 conf->nr_queued--;
2840                 spin_unlock_irqrestore(&conf->device_lock, flags);
2841
2842                 mddev = r10_bio->mddev;
2843                 conf = mddev->private;
2844                 if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
2845                     test_bit(R10BIO_WriteError, &r10_bio->state))
2846                         handle_write_completed(conf, r10_bio);
2847                 else if (test_bit(R10BIO_IsReshape, &r10_bio->state))
2848                         reshape_request_write(mddev, r10_bio);
2849                 else if (test_bit(R10BIO_IsSync, &r10_bio->state))
2850                         sync_request_write(mddev, r10_bio);
2851                 else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
2852                         recovery_request_write(mddev, r10_bio);
2853                 else if (test_bit(R10BIO_ReadError, &r10_bio->state))
2854                         handle_read_error(mddev, r10_bio);
2855                 else {
2856                         /* just a partial read to be scheduled from a
2857                          * separate context
2858                          */
2859                         int slot = r10_bio->read_slot;
2860                         generic_make_request(r10_bio->devs[slot].bio);
2861                 }
2862
2863                 cond_resched();
2864                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2865                         md_check_recovery(mddev);
2866         }
2867         blk_finish_plug(&plug);
2868 }
2869
2870
2871 static int init_resync(struct r10conf *conf)
2872 {
2873         int buffs;
2874         int i;
2875
2876         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2877         BUG_ON(conf->r10buf_pool);
2878         conf->have_replacement = 0;
2879         for (i = 0; i < conf->geo.raid_disks; i++)
2880                 if (conf->mirrors[i].replacement)
2881                         conf->have_replacement = 1;
2882         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
2883         if (!conf->r10buf_pool)
2884                 return -ENOMEM;
2885         conf->next_resync = 0;
2886         return 0;
2887 }
2888
2889 /*
2890  * perform a "sync" on one "block"
2891  *
2892  * We need to make sure that no normal I/O request - particularly write
2893  * requests - conflict with active sync requests.
2894  *
2895  * This is achieved by tracking pending requests and a 'barrier' concept
2896  * that can be installed to exclude normal IO requests.
2897  *
2898  * Resync and recovery are handled very differently.
2899  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
2900  *
2901  * For resync, we iterate over virtual addresses, read all copies,
2902  * and update if there are differences.  If only one copy is live,
2903  * skip it.
2904  * For recovery, we iterate over physical addresses, read a good
2905  * value for each non-in_sync drive, and over-write.
2906  *
2907  * So, for recovery we may have several outstanding complex requests for a
2908  * given address, one for each out-of-sync device.  We model this by allocating
2909  * a number of r10_bio structures, one for each out-of-sync device.
2910  * As we setup these structures, we collect all bio's together into a list
2911  * which we then process collectively to add pages, and then process again
2912  * to pass to generic_make_request.
2913  *
2914  * The r10_bio structures are linked using a borrowed master_bio pointer.
2915  * This link is counted in ->remaining.  When the r10_bio that points to NULL
2916  * has its remaining count decremented to 0, the whole complex operation
2917  * is complete.
2918  *
2919  */
2920
2921 static sector_t sync_request(struct mddev *mddev, sector_t sector_nr,
2922                              int *skipped, int go_faster)
2923 {
2924         struct r10conf *conf = mddev->private;
2925         struct r10bio *r10_bio;
2926         struct bio *biolist = NULL, *bio;
2927         sector_t max_sector, nr_sectors;
2928         int i;
2929         int max_sync;
2930         sector_t sync_blocks;
2931         sector_t sectors_skipped = 0;
2932         int chunks_skipped = 0;
2933         sector_t chunk_mask = conf->geo.chunk_mask;
2934
2935         if (!conf->r10buf_pool)
2936                 if (init_resync(conf))
2937                         return 0;
2938
2939         /*
2940          * Allow skipping a full rebuild for incremental assembly
2941          * of a clean array, like RAID1 does.
2942          */
2943         if (mddev->bitmap == NULL &&
2944             mddev->recovery_cp == MaxSector &&
2945             mddev->reshape_position == MaxSector &&
2946             !test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
2947             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
2948             !test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
2949             conf->fullsync == 0) {
2950                 *skipped = 1;
2951                 return mddev->dev_sectors - sector_nr;
2952         }
2953
2954  skipped:
2955         max_sector = mddev->dev_sectors;
2956         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
2957             test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2958                 max_sector = mddev->resync_max_sectors;
2959         if (sector_nr >= max_sector) {
2960                 /* If we aborted, we need to abort the
2961                  * sync on the 'current' bitmap chucks (there can
2962                  * be several when recovering multiple devices).
2963                  * as we may have started syncing it but not finished.
2964                  * We can find the current address in
2965                  * mddev->curr_resync, but for recovery,
2966                  * we need to convert that to several
2967                  * virtual addresses.
2968                  */
2969                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
2970                         end_reshape(conf);
2971                         return 0;
2972                 }
2973
2974                 if (mddev->curr_resync < max_sector) { /* aborted */
2975                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
2976                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2977                                                 &sync_blocks, 1);
2978                         else for (i = 0; i < conf->geo.raid_disks; i++) {
2979                                 sector_t sect =
2980                                         raid10_find_virt(conf, mddev->curr_resync, i);
2981                                 bitmap_end_sync(mddev->bitmap, sect,
2982                                                 &sync_blocks, 1);
2983                         }
2984                 } else {
2985                         /* completed sync */
2986                         if ((!mddev->bitmap || conf->fullsync)
2987                             && conf->have_replacement
2988                             && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2989                                 /* Completed a full sync so the replacements
2990                                  * are now fully recovered.
2991                                  */
2992                                 for (i = 0; i < conf->geo.raid_disks; i++)
2993                                         if (conf->mirrors[i].replacement)
2994                                                 conf->mirrors[i].replacement
2995                                                         ->recovery_offset
2996                                                         = MaxSector;
2997                         }
2998                         conf->fullsync = 0;
2999                 }
3000                 bitmap_close_sync(mddev->bitmap);
3001                 close_sync(conf);
3002                 *skipped = 1;
3003                 return sectors_skipped;
3004         }
3005
3006         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3007                 return reshape_request(mddev, sector_nr, skipped);
3008
3009         if (chunks_skipped >= conf->geo.raid_disks) {
3010                 /* if there has been nothing to do on any drive,
3011                  * then there is nothing to do at all..
3012                  */
3013                 *skipped = 1;
3014                 return (max_sector - sector_nr) + sectors_skipped;
3015         }
3016
3017         if (max_sector > mddev->resync_max)
3018                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
3019
3020         /* make sure whole request will fit in a chunk - if chunks
3021          * are meaningful
3022          */
3023         if (conf->geo.near_copies < conf->geo.raid_disks &&
3024             max_sector > (sector_nr | chunk_mask))
3025                 max_sector = (sector_nr | chunk_mask) + 1;
3026         /*
3027          * If there is non-resync activity waiting for us then
3028          * put in a delay to throttle resync.
3029          */
3030         if (!go_faster && conf->nr_waiting)
3031                 msleep_interruptible(1000);
3032
3033         /* Again, very different code for resync and recovery.
3034          * Both must result in an r10bio with a list of bios that
3035          * have bi_end_io, bi_sector, bi_bdev set,
3036          * and bi_private set to the r10bio.
3037          * For recovery, we may actually create several r10bios
3038          * with 2 bios in each, that correspond to the bios in the main one.
3039          * In this case, the subordinate r10bios link back through a
3040          * borrowed master_bio pointer, and the counter in the master
3041          * includes a ref from each subordinate.
3042          */
3043         /* First, we decide what to do and set ->bi_end_io
3044          * To end_sync_read if we want to read, and
3045          * end_sync_write if we will want to write.
3046          */
3047
3048         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
3049         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3050                 /* recovery... the complicated one */
3051                 int j;
3052                 r10_bio = NULL;
3053
3054                 for (i = 0 ; i < conf->geo.raid_disks; i++) {
3055                         int still_degraded;
3056                         struct r10bio *rb2;
3057                         sector_t sect;
3058                         int must_sync;
3059                         int any_working;
3060                         struct raid10_info *mirror = &conf->mirrors[i];
3061
3062                         if ((mirror->rdev == NULL ||
3063                              test_bit(In_sync, &mirror->rdev->flags))
3064                             &&
3065                             (mirror->replacement == NULL ||
3066                              test_bit(Faulty,
3067                                       &mirror->replacement->flags)))
3068                                 continue;
3069
3070                         still_degraded = 0;
3071                         /* want to reconstruct this device */
3072                         rb2 = r10_bio;
3073                         sect = raid10_find_virt(conf, sector_nr, i);
3074                         if (sect >= mddev->resync_max_sectors) {
3075                                 /* last stripe is not complete - don't
3076                                  * try to recover this sector.
3077                                  */
3078                                 continue;
3079                         }
3080                         /* Unless we are doing a full sync, or a replacement
3081                          * we only need to recover the block if it is set in
3082                          * the bitmap
3083                          */
3084                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
3085                                                       &sync_blocks, 1);
3086                         if (sync_blocks < max_sync)
3087                                 max_sync = sync_blocks;
3088                         if (!must_sync &&
3089                             mirror->replacement == NULL &&
3090                             !conf->fullsync) {
3091                                 /* yep, skip the sync_blocks here, but don't assume
3092                                  * that there will never be anything to do here
3093                                  */
3094                                 chunks_skipped = -1;
3095                                 continue;
3096                         }
3097
3098                         r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3099                         raise_barrier(conf, rb2 != NULL);
3100                         atomic_set(&r10_bio->remaining, 0);
3101
3102                         r10_bio->master_bio = (struct bio*)rb2;
3103                         if (rb2)
3104                                 atomic_inc(&rb2->remaining);
3105                         r10_bio->mddev = mddev;
3106                         set_bit(R10BIO_IsRecover, &r10_bio->state);
3107                         r10_bio->sector = sect;
3108
3109                         raid10_find_phys(conf, r10_bio);
3110
3111                         /* Need to check if the array will still be
3112                          * degraded
3113                          */
3114                         for (j = 0; j < conf->geo.raid_disks; j++)
3115                                 if (conf->mirrors[j].rdev == NULL ||
3116                                     test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
3117                                         still_degraded = 1;
3118                                         break;
3119                                 }
3120
3121                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
3122                                                       &sync_blocks, still_degraded);
3123
3124                         any_working = 0;
3125                         for (j=0; j<conf->copies;j++) {
3126                                 int k;
3127                                 int d = r10_bio->devs[j].devnum;
3128                                 sector_t from_addr, to_addr;
3129                                 struct md_rdev *rdev;
3130                                 sector_t sector, first_bad;
3131                                 int bad_sectors;
3132                                 if (!conf->mirrors[d].rdev ||
3133                                     !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
3134                                         continue;
3135                                 /* This is where we read from */
3136                                 any_working = 1;
3137                                 rdev = conf->mirrors[d].rdev;
3138                                 sector = r10_bio->devs[j].addr;
3139
3140                                 if (is_badblock(rdev, sector, max_sync,
3141                                                 &first_bad, &bad_sectors)) {
3142                                         if (first_bad > sector)
3143                                                 max_sync = first_bad - sector;
3144                                         else {
3145                                                 bad_sectors -= (sector
3146                                                                 - first_bad);
3147                                                 if (max_sync > bad_sectors)
3148                                                         max_sync = bad_sectors;
3149                                                 continue;
3150                                         }
3151                                 }
3152                                 bio = r10_bio->devs[0].bio;
3153                                 bio_reset(bio);
3154                                 bio->bi_next = biolist;
3155                                 biolist = bio;
3156                                 bio->bi_private = r10_bio;
3157                                 bio->bi_end_io = end_sync_read;
3158                                 bio->bi_rw = READ;
3159                                 from_addr = r10_bio->devs[j].addr;
3160                                 bio->bi_sector = from_addr + rdev->data_offset;
3161                                 bio->bi_bdev = rdev->bdev;
3162                                 atomic_inc(&rdev->nr_pending);
3163                                 /* and we write to 'i' (if not in_sync) */
3164
3165                                 for (k=0; k<conf->copies; k++)
3166                                         if (r10_bio->devs[k].devnum == i)
3167                                                 break;
3168                                 BUG_ON(k == conf->copies);
3169                                 to_addr = r10_bio->devs[k].addr;
3170                                 r10_bio->devs[0].devnum = d;
3171                                 r10_bio->devs[0].addr = from_addr;
3172                                 r10_bio->devs[1].devnum = i;
3173                                 r10_bio->devs[1].addr = to_addr;
3174
3175                                 rdev = mirror->rdev;
3176                                 if (!test_bit(In_sync, &rdev->flags)) {
3177                                         bio = r10_bio->devs[1].bio;
3178                                         bio_reset(bio);
3179                                         bio->bi_next = biolist;
3180                                         biolist = bio;
3181                                         bio->bi_private = r10_bio;
3182                                         bio->bi_end_io = end_sync_write;
3183                                         bio->bi_rw = WRITE;
3184                                         bio->bi_sector = to_addr
3185                                                 + rdev->data_offset;
3186                                         bio->bi_bdev = rdev->bdev;
3187                                         atomic_inc(&r10_bio->remaining);
3188                                 } else
3189                                         r10_bio->devs[1].bio->bi_end_io = NULL;
3190
3191                                 /* and maybe write to replacement */
3192                                 bio = r10_bio->devs[1].repl_bio;
3193                                 if (bio)
3194                                         bio->bi_end_io = NULL;
3195                                 rdev = mirror->replacement;
3196                                 /* Note: if rdev != NULL, then bio
3197                                  * cannot be NULL as r10buf_pool_alloc will
3198                                  * have allocated it.
3199                                  * So the second test here is pointless.
3200                                  * But it keeps semantic-checkers happy, and
3201                                  * this comment keeps human reviewers
3202                                  * happy.
3203                                  */
3204                                 if (rdev == NULL || bio == NULL ||
3205                                     test_bit(Faulty, &rdev->flags))
3206                                         break;
3207                                 bio_reset(bio);
3208                                 bio->bi_next = biolist;
3209                                 biolist = bio;
3210                                 bio->bi_private = r10_bio;
3211                                 bio->bi_end_io = end_sync_write;
3212                                 bio->bi_rw = WRITE;
3213                                 bio->bi_sector = to_addr + rdev->data_offset;
3214                                 bio->bi_bdev = rdev->bdev;
3215                                 atomic_inc(&r10_bio->remaining);
3216                                 break;
3217                         }
3218                         if (j == conf->copies) {
3219                                 /* Cannot recover, so abort the recovery or
3220                                  * record a bad block */
3221                                 put_buf(r10_bio);
3222                                 if (rb2)
3223                                         atomic_dec(&rb2->remaining);
3224                                 r10_bio = rb2;
3225                                 if (any_working) {
3226                                         /* problem is that there are bad blocks
3227                                          * on other device(s)
3228                                          */
3229                                         int k;
3230                                         for (k = 0; k < conf->copies; k++)
3231                                                 if (r10_bio->devs[k].devnum == i)
3232                                                         break;
3233                                         if (!test_bit(In_sync,
3234                                                       &mirror->rdev->flags)
3235                                             && !rdev_set_badblocks(
3236                                                     mirror->rdev,
3237                                                     r10_bio->devs[k].addr,
3238                                                     max_sync, 0))
3239                                                 any_working = 0;
3240                                         if (mirror->replacement &&
3241                                             !rdev_set_badblocks(
3242                                                     mirror->replacement,
3243                                                     r10_bio->devs[k].addr,
3244                                                     max_sync, 0))
3245                                                 any_working = 0;
3246                                 }
3247                                 if (!any_working)  {
3248                                         if (!test_and_set_bit(MD_RECOVERY_INTR,
3249                                                               &mddev->recovery))
3250                                                 printk(KERN_INFO "md/raid10:%s: insufficient "
3251                                                        "working devices for recovery.\n",
3252                                                        mdname(mddev));
3253                                         mirror->recovery_disabled
3254                                                 = mddev->recovery_disabled;
3255                                 }
3256                                 break;
3257                         }
3258                 }
3259                 if (biolist == NULL) {
3260                         while (r10_bio) {
3261                                 struct r10bio *rb2 = r10_bio;
3262                                 r10_bio = (struct r10bio*) rb2->master_bio;
3263                                 rb2->master_bio = NULL;
3264                                 put_buf(rb2);
3265                         }
3266                         goto giveup;
3267                 }
3268         } else {
3269                 /* resync. Schedule a read for every block at this virt offset */
3270                 int count = 0;
3271
3272                 bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3273
3274                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
3275                                        &sync_blocks, mddev->degraded) &&
3276                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
3277                                                  &mddev->recovery)) {
3278                         /* We can skip this block */
3279                         *skipped = 1;
3280                         return sync_blocks + sectors_skipped;
3281                 }
3282                 if (sync_blocks < max_sync)
3283                         max_sync = sync_blocks;
3284                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3285
3286                 r10_bio->mddev = mddev;
3287                 atomic_set(&r10_bio->remaining, 0);
3288                 raise_barrier(conf, 0);
3289                 conf->next_resync = sector_nr;
3290
3291                 r10_bio->master_bio = NULL;
3292                 r10_bio->sector = sector_nr;
3293                 set_bit(R10BIO_IsSync, &r10_bio->state);
3294                 raid10_find_phys(conf, r10_bio);
3295                 r10_bio->sectors = (sector_nr | chunk_mask) - sector_nr + 1;
3296
3297                 for (i = 0; i < conf->copies; i++) {
3298                         int d = r10_bio->devs[i].devnum;
3299                         sector_t first_bad, sector;
3300                         int bad_sectors;
3301
3302                         if (r10_bio->devs[i].repl_bio)
3303                                 r10_bio->devs[i].repl_bio->bi_end_io = NULL;
3304
3305                         bio = r10_bio->devs[i].bio;
3306                         bio_reset(bio);
3307                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
3308                         if (conf->mirrors[d].rdev == NULL ||
3309                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
3310                                 continue;
3311                         sector = r10_bio->devs[i].addr;
3312                         if (is_badblock(conf->mirrors[d].rdev,
3313                                         sector, max_sync,
3314                                         &first_bad, &bad_sectors)) {
3315                                 if (first_bad > sector)
3316                                         max_sync = first_bad - sector;
3317                                 else {
3318                                         bad_sectors -= (sector - first_bad);
3319                                         if (max_sync > bad_sectors)
3320                                                 max_sync = bad_sectors;
3321                                         continue;
3322                                 }
3323                         }
3324                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3325                         atomic_inc(&r10_bio->remaining);
3326                         bio->bi_next = biolist;
3327                         biolist = bio;
3328                         bio->bi_private = r10_bio;
3329                         bio->bi_end_io = end_sync_read;
3330                         bio->bi_rw = READ;
3331                         bio->bi_sector = sector +
3332                                 conf->mirrors[d].rdev->data_offset;
3333                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
3334                         count++;
3335
3336                         if (conf->mirrors[d].replacement == NULL ||
3337                             test_bit(Faulty,
3338                                      &conf->mirrors[d].replacement->flags))
3339                                 continue;
3340
3341                         /* Need to set up for writing to the replacement */
3342                         bio = r10_bio->devs[i].repl_bio;
3343                         bio_reset(bio);
3344                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
3345
3346                         sector = r10_bio->devs[i].addr;
3347                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3348                         bio->bi_next = biolist;
3349                         biolist = bio;
3350                         bio->bi_private = r10_bio;
3351                         bio->bi_end_io = end_sync_write;
3352                         bio->bi_rw = WRITE;
3353                         bio->bi_sector = sector +
3354                                 conf->mirrors[d].replacement->data_offset;
3355                         bio->bi_bdev = conf->mirrors[d].replacement->bdev;
3356                         count++;
3357                 }
3358
3359                 if (count < 2) {
3360                         for (i=0; i<conf->copies; i++) {
3361                                 int d = r10_bio->devs[i].devnum;
3362                                 if (r10_bio->devs[i].bio->bi_end_io)
3363                                         rdev_dec_pending(conf->mirrors[d].rdev,
3364                                                          mddev);
3365                                 if (r10_bio->devs[i].repl_bio &&
3366                                     r10_bio->devs[i].repl_bio->bi_end_io)
3367                                         rdev_dec_pending(
3368                                                 conf->mirrors[d].replacement,
3369                                                 mddev);
3370                         }
3371                         put_buf(r10_bio);
3372                         biolist = NULL;
3373                         goto giveup;
3374                 }
3375         }
3376
3377         nr_sectors = 0;
3378         if (sector_nr + max_sync < max_sector)
3379                 max_sector = sector_nr + max_sync;
3380         do {
3381                 struct page *page;
3382                 int len = PAGE_SIZE;
3383                 if (sector_nr + (len>>9) > max_sector)
3384                         len = (max_sector - sector_nr) << 9;
3385                 if (len == 0)
3386                         break;
3387                 for (bio= biolist ; bio ; bio=bio->bi_next) {
3388                         struct bio *bio2;
3389                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
3390                         if (bio_add_page(bio, page, len, 0))
3391                                 continue;
3392
3393                         /* stop here */
3394                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
3395                         for (bio2 = biolist;
3396                              bio2 && bio2 != bio;
3397                              bio2 = bio2->bi_next) {
3398                                 /* remove last page from this bio */
3399                                 bio2->bi_vcnt--;
3400                                 bio2->bi_size -= len;
3401                                 bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
3402                         }
3403                         goto bio_full;
3404                 }
3405                 nr_sectors += len>>9;
3406                 sector_nr += len>>9;
3407         } while (biolist->bi_vcnt < RESYNC_PAGES);
3408  bio_full:
3409         r10_bio->sectors = nr_sectors;
3410
3411         while (biolist) {
3412                 bio = biolist;
3413                 biolist = biolist->bi_next;
3414
3415                 bio->bi_next = NULL;
3416                 r10_bio = bio->bi_private;
3417                 r10_bio->sectors = nr_sectors;
3418
3419                 if (bio->bi_end_io == end_sync_read) {
3420                         md_sync_acct(bio->bi_bdev, nr_sectors);
3421                         set_bit(BIO_UPTODATE, &bio->bi_flags);
3422                         generic_make_request(bio);
3423                 }
3424         }
3425
3426         if (sectors_skipped)
3427                 /* pretend they weren't skipped, it makes
3428                  * no important difference in this case
3429                  */
3430                 md_done_sync(mddev, sectors_skipped, 1);
3431
3432         return sectors_skipped + nr_sectors;
3433  giveup:
3434         /* There is nowhere to write, so all non-sync
3435          * drives must be failed or in resync, all drives
3436          * have a bad block, so try the next chunk...
3437          */
3438         if (sector_nr + max_sync < max_sector)
3439                 max_sector = sector_nr + max_sync;
3440
3441         sectors_skipped += (max_sector - sector_nr);
3442         chunks_skipped ++;
3443         sector_nr = max_sector;
3444         goto skipped;
3445 }
3446
3447 static sector_t
3448 raid10_size(struct mddev *mddev, sector_t sectors, int raid_disks)
3449 {
3450         sector_t size;
3451         struct r10conf *conf = mddev->private;
3452
3453         if (!raid_disks)
3454                 raid_disks = min(conf->geo.raid_disks,
3455                                  conf->prev.raid_disks);
3456         if (!sectors)
3457                 sectors = conf->dev_sectors;
3458
3459         size = sectors >> conf->geo.chunk_shift;
3460         sector_div(size, conf->geo.far_copies);
3461         size = size * raid_disks;
3462         sector_div(size, conf->geo.near_copies);
3463
3464         return size << conf->geo.chunk_shift;
3465 }
3466
3467 static void calc_sectors(struct r10conf *conf, sector_t size)
3468 {
3469         /* Calculate the number of sectors-per-device that will
3470          * actually be used, and set conf->dev_sectors and
3471          * conf->stride
3472          */
3473
3474         size = size >> conf->geo.chunk_shift;
3475         sector_div(size, conf->geo.far_copies);
3476         size = size * conf->geo.raid_disks;
3477         sector_div(size, conf->geo.near_copies);
3478         /* 'size' is now the number of chunks in the array */
3479         /* calculate "used chunks per device" */
3480         size = size * conf->copies;
3481
3482         /* We need to round up when dividing by raid_disks to
3483          * get the stride size.
3484          */
3485         size = DIV_ROUND_UP_SECTOR_T(size, conf->geo.raid_disks);
3486
3487         conf->dev_sectors = size << conf->geo.chunk_shift;
3488
3489         if (conf->geo.far_offset)
3490                 conf->geo.stride = 1 << conf->geo.chunk_shift;
3491         else {
3492                 sector_div(size, conf->geo.far_copies);
3493                 conf->geo.stride = size << conf->geo.chunk_shift;
3494         }
3495 }
3496
3497 enum geo_type {geo_new, geo_old, geo_start};
3498 static int setup_geo(struct geom *geo, struct mddev *mddev, enum geo_type new)
3499 {
3500         int nc, fc, fo;
3501         int layout, chunk, disks;
3502         switch (new) {
3503         case geo_old:
3504                 layout = mddev->layout;
3505                 chunk = mddev->chunk_sectors;
3506                 disks = mddev->raid_disks - mddev->delta_disks;
3507                 break;
3508         case geo_new:
3509                 layout = mddev->new_layout;
3510                 chunk = mddev->new_chunk_sectors;
3511                 disks = mddev->raid_disks;
3512                 break;
3513         default: /* avoid 'may be unused' warnings */
3514         case geo_start: /* new when starting reshape - raid_disks not
3515                          * updated yet. */
3516                 layout = mddev->new_layout;
3517                 chunk = mddev->new_chunk_sectors;
3518                 disks = mddev->raid_disks + mddev->delta_disks;
3519                 break;
3520         }
3521         if (layout >> 18)
3522                 return -1;
3523         if (chunk < (PAGE_SIZE >> 9) ||
3524             !is_power_of_2(chunk))
3525                 return -2;
3526         nc = layout & 255;
3527         fc = (layout >> 8) & 255;
3528         fo = layout & (1<<16);
3529         geo->raid_disks = disks;
3530         geo->near_copies = nc;
3531         geo->far_copies = fc;
3532         geo->far_offset = fo;
3533         geo->far_set_size = (layout & (1<<17)) ? disks / fc : disks;
3534         geo->chunk_mask = chunk - 1;
3535         geo->chunk_shift = ffz(~chunk);
3536         return nc*fc;
3537 }
3538
3539 static struct r10conf *setup_conf(struct mddev *mddev)
3540 {
3541         struct r10conf *conf = NULL;
3542         int err = -EINVAL;
3543         struct geom geo;
3544         int copies;
3545
3546         copies = setup_geo(&geo, mddev, geo_new);
3547
3548         if (copies == -2) {
3549                 printk(KERN_ERR "md/raid10:%s: chunk size must be "
3550                        "at least PAGE_SIZE(%ld) and be a power of 2.\n",
3551                        mdname(mddev), PAGE_SIZE);
3552                 goto out;
3553         }
3554
3555         if (copies < 2 || copies > mddev->raid_disks) {
3556                 printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
3557                        mdname(mddev), mddev->new_layout);
3558                 goto out;
3559         }
3560
3561         err = -ENOMEM;
3562         conf = kzalloc(sizeof(struct r10conf), GFP_KERNEL);
3563         if (!conf)
3564                 goto out;
3565
3566         /* FIXME calc properly */
3567         conf->mirrors = kzalloc(sizeof(struct raid10_info)*(mddev->raid_disks +
3568                                                             max(0,-mddev->delta_disks)),
3569                                 GFP_KERNEL);
3570         if (!conf->mirrors)
3571                 goto out;
3572
3573         conf->tmppage = alloc_page(GFP_KERNEL);
3574         if (!conf->tmppage)
3575                 goto out;
3576
3577         conf->geo = geo;
3578         conf->copies = copies;
3579         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
3580                                            r10bio_pool_free, conf);
3581         if (!conf->r10bio_pool)
3582                 goto out;
3583
3584         calc_sectors(conf, mddev->dev_sectors);
3585         if (mddev->reshape_position == MaxSector) {
3586                 conf->prev = conf->geo;
3587                 conf->reshape_progress = MaxSector;
3588         } else {
3589                 if (setup_geo(&conf->prev, mddev, geo_old) != conf->copies) {
3590                         err = -EINVAL;
3591                         goto out;
3592                 }
3593                 conf->reshape_progress = mddev->reshape_position;
3594                 if (conf->prev.far_offset)
3595                         conf->prev.stride = 1 << conf->prev.chunk_shift;
3596                 else
3597                         /* far_copies must be 1 */
3598                         conf->prev.stride = conf->dev_sectors;
3599         }
3600         spin_lock_init(&conf->device_lock);
3601         INIT_LIST_HEAD(&conf->retry_list);
3602
3603         spin_lock_init(&conf->resync_lock);
3604         init_waitqueue_head(&conf->wait_barrier);
3605
3606         conf->thread = md_register_thread(raid10d, mddev, "raid10");
3607         if (!conf->thread)
3608                 goto out;
3609
3610         conf->mddev = mddev;
3611         return conf;
3612
3613  out:
3614         if (err == -ENOMEM)
3615                 printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
3616                        mdname(mddev));
3617         if (conf) {
3618                 if (conf->r10bio_pool)
3619                         mempool_destroy(conf->r10bio_pool);
3620                 kfree(conf->mirrors);
3621                 safe_put_page(conf->tmppage);
3622                 kfree(conf);
3623         }
3624         return ERR_PTR(err);
3625 }
3626
3627 static int run(struct mddev *mddev)
3628 {
3629         struct r10conf *conf;
3630         int i, disk_idx, chunk_size;
3631         struct raid10_info *disk;
3632         struct md_rdev *rdev;
3633         sector_t size;
3634         sector_t min_offset_diff = 0;
3635         int first = 1;
3636         bool discard_supported = false;
3637
3638         if (mddev->private == NULL) {
3639                 conf = setup_conf(mddev);
3640                 if (IS_ERR(conf))
3641                         return PTR_ERR(conf);
3642                 mddev->private = conf;
3643         }
3644         conf = mddev->private;
3645         if (!conf)
3646                 goto out;
3647
3648         mddev->thread = conf->thread;
3649         conf->thread = NULL;
3650
3651         chunk_size = mddev->chunk_sectors << 9;
3652         if (mddev->queue) {
3653                 blk_queue_max_discard_sectors(mddev->queue,
3654                                               mddev->chunk_sectors);
3655                 blk_queue_max_write_same_sectors(mddev->queue, 0);
3656                 blk_queue_io_min(mddev->queue, chunk_size);
3657                 if (conf->geo.raid_disks % conf->geo.near_copies)
3658                         blk_queue_io_opt(mddev->queue, chunk_size * conf->geo.raid_disks);
3659                 else
3660                         blk_queue_io_opt(mddev->queue, chunk_size *
3661                                          (conf->geo.raid_disks / conf->geo.near_copies));
3662         }
3663
3664         rdev_for_each(rdev, mddev) {
3665                 long long diff;
3666                 struct request_queue *q;
3667
3668                 disk_idx = rdev->raid_disk;
3669                 if (disk_idx < 0)
3670                         continue;
3671                 if (disk_idx >= conf->geo.raid_disks &&
3672                     disk_idx >= conf->prev.raid_disks)
3673                         continue;
3674                 disk = conf->mirrors + disk_idx;
3675
3676                 if (test_bit(Replacement, &rdev->flags)) {
3677                         if (disk->replacement)
3678                                 goto out_free_conf;
3679                         disk->replacement = rdev;
3680                 } else {
3681                         if (disk->rdev)
3682                                 goto out_free_conf;
3683                         disk->rdev = rdev;
3684                 }
3685                 q = bdev_get_queue(rdev->bdev);
3686                 if (q->merge_bvec_fn)
3687                         mddev->merge_check_needed = 1;
3688                 diff = (rdev->new_data_offset - rdev->data_offset);
3689                 if (!mddev->reshape_backwards)
3690                         diff = -diff;
3691                 if (diff < 0)
3692                         diff = 0;
3693                 if (first || diff < min_offset_diff)
3694                         min_offset_diff = diff;
3695
3696                 if (mddev->gendisk)
3697                         disk_stack_limits(mddev->gendisk, rdev->bdev,
3698                                           rdev->data_offset << 9);
3699
3700                 disk->head_position = 0;
3701
3702                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
3703                         discard_supported = true;
3704         }
3705
3706         if (mddev->queue) {
3707                 if (discard_supported)
3708                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
3709                                                 mddev->queue);
3710                 else
3711                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
3712                                                   mddev->queue);
3713         }
3714         /* need to check that every block has at least one working mirror */
3715         if (!enough(conf, -1)) {
3716                 printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
3717                        mdname(mddev));
3718                 goto out_free_conf;
3719         }
3720
3721         if (conf->reshape_progress != MaxSector) {
3722                 /* must ensure that shape change is supported */
3723                 if (conf->geo.far_copies != 1 &&
3724                     conf->geo.far_offset == 0)
3725                         goto out_free_conf;
3726                 if (conf->prev.far_copies != 1 &&
3727                     conf->prev.far_offset == 0)
3728                         goto out_free_conf;
3729         }
3730
3731         mddev->degraded = 0;
3732         for (i = 0;
3733              i < conf->geo.raid_disks
3734                      || i < conf->prev.raid_disks;
3735              i++) {
3736
3737                 disk = conf->mirrors + i;
3738
3739                 if (!disk->rdev && disk->replacement) {
3740                         /* The replacement is all we have - use it */
3741                         disk->rdev = disk->replacement;
3742                         disk->replacement = NULL;
3743                         clear_bit(Replacement, &disk->rdev->flags);
3744                 }
3745
3746                 if (!disk->rdev ||
3747                     !test_bit(In_sync, &disk->rdev->flags)) {
3748                         disk->head_position = 0;
3749                         mddev->degraded++;
3750                         if (disk->rdev)
3751                                 conf->fullsync = 1;
3752                 }
3753                 disk->recovery_disabled = mddev->recovery_disabled - 1;
3754         }
3755
3756         if (mddev->recovery_cp != MaxSector)
3757                 printk(KERN_NOTICE "md/raid10:%s: not clean"
3758                        " -- starting background reconstruction\n",
3759                        mdname(mddev));
3760         printk(KERN_INFO
3761                 "md/raid10:%s: active with %d out of %d devices\n",
3762                 mdname(mddev), conf->geo.raid_disks - mddev->degraded,
3763                 conf->geo.raid_disks);
3764         /*
3765          * Ok, everything is just fine now
3766          */
3767         mddev->dev_sectors = conf->dev_sectors;
3768         size = raid10_size(mddev, 0, 0);
3769         md_set_array_sectors(mddev, size);
3770         mddev->resync_max_sectors = size;
3771
3772         if (mddev->queue) {
3773                 int stripe = conf->geo.raid_disks *
3774                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
3775                 mddev->queue->backing_dev_info.congested_fn = raid10_congested;
3776                 mddev->queue->backing_dev_info.congested_data = mddev;
3777
3778                 /* Calculate max read-ahead size.
3779                  * We need to readahead at least twice a whole stripe....
3780                  * maybe...
3781                  */
3782                 stripe /= conf->geo.near_copies;
3783                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3784                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3785                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
3786         }
3787
3788
3789         if (md_integrity_register(mddev))
3790                 goto out_free_conf;
3791
3792         if (conf->reshape_progress != MaxSector) {
3793                 unsigned long before_length, after_length;
3794
3795                 before_length = ((1 << conf->prev.chunk_shift) *
3796                                  conf->prev.far_copies);
3797                 after_length = ((1 << conf->geo.chunk_shift) *
3798                                 conf->geo.far_copies);
3799
3800                 if (max(before_length, after_length) > min_offset_diff) {
3801                         /* This cannot work */
3802                         printk("md/raid10: offset difference not enough to continue reshape\n");
3803                         goto out_free_conf;
3804                 }
3805                 conf->offset_diff = min_offset_diff;
3806
3807                 conf->reshape_safe = conf->reshape_progress;
3808                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3809                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3810                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3811                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3812                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3813                                                         "reshape");
3814         }
3815
3816         return 0;
3817
3818 out_free_conf:
3819         md_unregister_thread(&mddev->thread);
3820         if (conf->r10bio_pool)
3821                 mempool_destroy(conf->r10bio_pool);
3822         safe_put_page(conf->tmppage);
3823         kfree(conf->mirrors);
3824         kfree(conf);
3825         mddev->private = NULL;
3826 out:
3827         return -EIO;
3828 }
3829
3830 static int stop(struct mddev *mddev)
3831 {
3832         struct r10conf *conf = mddev->private;
3833
3834         raise_barrier(conf, 0);
3835         lower_barrier(conf);
3836
3837         md_unregister_thread(&mddev->thread);
3838         if (mddev->queue)
3839                 /* the unplug fn references 'conf'*/
3840                 blk_sync_queue(mddev->queue);
3841
3842         if (conf->r10bio_pool)
3843                 mempool_destroy(conf->r10bio_pool);
3844         safe_put_page(conf->tmppage);
3845         kfree(conf->mirrors);
3846         kfree(conf);
3847         mddev->private = NULL;
3848         return 0;
3849 }
3850
3851 static void raid10_quiesce(struct mddev *mddev, int state)
3852 {
3853         struct r10conf *conf = mddev->private;
3854
3855         switch(state) {
3856         case 1:
3857                 raise_barrier(conf, 0);
3858                 break;
3859         case 0:
3860                 lower_barrier(conf);
3861                 break;
3862         }
3863 }
3864
3865 static int raid10_resize(struct mddev *mddev, sector_t sectors)
3866 {
3867         /* Resize of 'far' arrays is not supported.
3868          * For 'near' and 'offset' arrays we can set the
3869          * number of sectors used to be an appropriate multiple
3870          * of the chunk size.
3871          * For 'offset', this is far_copies*chunksize.
3872          * For 'near' the multiplier is the LCM of
3873          * near_copies and raid_disks.
3874          * So if far_copies > 1 && !far_offset, fail.
3875          * Else find LCM(raid_disks, near_copy)*far_copies and
3876          * multiply by chunk_size.  Then round to this number.
3877          * This is mostly done by raid10_size()
3878          */
3879         struct r10conf *conf = mddev->private;
3880         sector_t oldsize, size;
3881
3882         if (mddev->reshape_position != MaxSector)
3883                 return -EBUSY;
3884
3885         if (conf->geo.far_copies > 1 && !conf->geo.far_offset)
3886                 return -EINVAL;
3887
3888         oldsize = raid10_size(mddev, 0, 0);
3889         size = raid10_size(mddev, sectors, 0);
3890         if (mddev->external_size &&
3891             mddev->array_sectors > size)
3892                 return -EINVAL;
3893         if (mddev->bitmap) {
3894                 int ret = bitmap_resize(mddev->bitmap, size, 0, 0);
3895                 if (ret)
3896                         return ret;
3897         }
3898         md_set_array_sectors(mddev, size);
3899         set_capacity(mddev->gendisk, mddev->array_sectors);
3900         revalidate_disk(mddev->gendisk);
3901         if (sectors > mddev->dev_sectors &&
3902             mddev->recovery_cp > oldsize) {
3903                 mddev->recovery_cp = oldsize;
3904                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3905         }
3906         calc_sectors(conf, sectors);
3907         mddev->dev_sectors = conf->dev_sectors;
3908         mddev->resync_max_sectors = size;
3909         return 0;
3910 }
3911
3912 static void *raid10_takeover_raid0(struct mddev *mddev)
3913 {
3914         struct md_rdev *rdev;
3915         struct r10conf *conf;
3916
3917         if (mddev->degraded > 0) {
3918                 printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
3919                        mdname(mddev));
3920                 return ERR_PTR(-EINVAL);
3921         }
3922
3923         /* Set new parameters */
3924         mddev->new_level = 10;
3925         /* new layout: far_copies = 1, near_copies = 2 */
3926         mddev->new_layout = (1<<8) + 2;
3927         mddev->new_chunk_sectors = mddev->chunk_sectors;
3928         mddev->delta_disks = mddev->raid_disks;
3929         mddev->raid_disks *= 2;
3930         /* make sure it will be not marked as dirty */
3931         mddev->recovery_cp = MaxSector;
3932
3933         conf = setup_conf(mddev);
3934         if (!IS_ERR(conf)) {
3935                 rdev_for_each(rdev, mddev)
3936                         if (rdev->raid_disk >= 0)
3937                                 rdev->new_raid_disk = rdev->raid_disk * 2;
3938                 conf->barrier = 1;
3939         }
3940
3941         return conf;
3942 }
3943
3944 static void *raid10_takeover(struct mddev *mddev)
3945 {
3946         struct r0conf *raid0_conf;
3947
3948         /* raid10 can take over:
3949          *  raid0 - providing it has only two drives
3950          */
3951         if (mddev->level == 0) {
3952                 /* for raid0 takeover only one zone is supported */
3953                 raid0_conf = mddev->private;
3954                 if (raid0_conf->nr_strip_zones > 1) {
3955                         printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
3956                                " with more than one zone.\n",
3957                                mdname(mddev));
3958                         return ERR_PTR(-EINVAL);
3959                 }
3960                 return raid10_takeover_raid0(mddev);
3961         }
3962         return ERR_PTR(-EINVAL);
3963 }
3964
3965 static int raid10_check_reshape(struct mddev *mddev)
3966 {
3967         /* Called when there is a request to change
3968          * - layout (to ->new_layout)
3969          * - chunk size (to ->new_chunk_sectors)
3970          * - raid_disks (by delta_disks)
3971          * or when trying to restart a reshape that was ongoing.
3972          *
3973          * We need to validate the request and possibly allocate
3974          * space if that might be an issue later.
3975          *
3976          * Currently we reject any reshape of a 'far' mode array,
3977          * allow chunk size to change if new is generally acceptable,
3978          * allow raid_disks to increase, and allow
3979          * a switch between 'near' mode and 'offset' mode.
3980          */
3981         struct r10conf *conf = mddev->private;
3982         struct geom geo;
3983
3984         if (conf->geo.far_copies != 1 && !conf->geo.far_offset)
3985                 return -EINVAL;
3986
3987         if (setup_geo(&geo, mddev, geo_start) != conf->copies)
3988                 /* mustn't change number of copies */
3989                 return -EINVAL;
3990         if (geo.far_copies > 1 && !geo.far_offset)
3991                 /* Cannot switch to 'far' mode */
3992                 return -EINVAL;
3993
3994         if (mddev->array_sectors & geo.chunk_mask)
3995                         /* not factor of array size */
3996                         return -EINVAL;
3997
3998         if (!enough(conf, -1))
3999                 return -EINVAL;
4000
4001         kfree(conf->mirrors_new);
4002         conf->mirrors_new = NULL;
4003         if (mddev->delta_disks > 0) {
4004                 /* allocate new 'mirrors' list */
4005                 conf->mirrors_new = kzalloc(
4006                         sizeof(struct raid10_info)
4007                         *(mddev->raid_disks +
4008                           mddev->delta_disks),
4009                         GFP_KERNEL);
4010                 if (!conf->mirrors_new)
4011                         return -ENOMEM;
4012         }
4013         return 0;
4014 }
4015
4016 /*
4017  * Need to check if array has failed when deciding whether to:
4018  *  - start an array
4019  *  - remove non-faulty devices
4020  *  - add a spare
4021  *  - allow a reshape
4022  * This determination is simple when no reshape is happening.
4023  * However if there is a reshape, we need to carefully check
4024  * both the before and after sections.
4025  * This is because some failed devices may only affect one
4026  * of the two sections, and some non-in_sync devices may
4027  * be insync in the section most affected by failed devices.
4028  */
4029 static int calc_degraded(struct r10conf *conf)
4030 {
4031         int degraded, degraded2;
4032         int i;
4033
4034         rcu_read_lock();
4035         degraded = 0;
4036         /* 'prev' section first */
4037         for (i = 0; i < conf->prev.raid_disks; i++) {
4038                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
4039                 if (!rdev || test_bit(Faulty, &rdev->flags))
4040                         degraded++;
4041                 else if (!test_bit(In_sync, &rdev->flags))
4042                         /* When we can reduce the number of devices in
4043                          * an array, this might not contribute to
4044                          * 'degraded'.  It does now.
4045                          */
4046                         degraded++;
4047         }
4048         rcu_read_unlock();
4049         if (conf->geo.raid_disks == conf->prev.raid_disks)
4050                 return degraded;
4051         rcu_read_lock();
4052         degraded2 = 0;
4053         for (i = 0; i < conf->geo.raid_disks; i++) {
4054                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
4055                 if (!rdev || test_bit(Faulty, &rdev->flags))
4056                         degraded2++;
4057                 else if (!test_bit(In_sync, &rdev->flags)) {
4058                         /* If reshape is increasing the number of devices,
4059                          * this section has already been recovered, so
4060                          * it doesn't contribute to degraded.
4061                          * else it does.
4062                          */
4063                         if (conf->geo.raid_disks <= conf->prev.raid_disks)
4064                                 degraded2++;
4065                 }
4066         }
4067         rcu_read_unlock();
4068         if (degraded2 > degraded)
4069                 return degraded2;
4070         return degraded;
4071 }
4072
4073 static int raid10_start_reshape(struct mddev *mddev)
4074 {
4075         /* A 'reshape' has been requested. This commits
4076          * the various 'new' fields and sets MD_RECOVER_RESHAPE
4077          * This also checks if there are enough spares and adds them
4078          * to the array.
4079          * We currently require enough spares to make the final
4080          * array non-degraded.  We also require that the difference
4081          * between old and new data_offset - on each device - is
4082          * enough that we never risk over-writing.
4083          */
4084
4085         unsigned long before_length, after_length;
4086         sector_t min_offset_diff = 0;
4087         int first = 1;
4088         struct geom new;
4089         struct r10conf *conf = mddev->private;
4090         struct md_rdev *rdev;
4091         int spares = 0;
4092         int ret;
4093
4094         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4095                 return -EBUSY;
4096
4097         if (setup_geo(&new, mddev, geo_start) != conf->copies)
4098                 return -EINVAL;
4099
4100         before_length = ((1 << conf->prev.chunk_shift) *
4101                          conf->prev.far_copies);
4102         after_length = ((1 << conf->geo.chunk_shift) *
4103                         conf->geo.far_copies);
4104
4105         rdev_for_each(rdev, mddev) {
4106                 if (!test_bit(In_sync, &rdev->flags)
4107                     && !test_bit(Faulty, &rdev->flags))
4108                         spares++;
4109                 if (rdev->raid_disk >= 0) {
4110                         long long diff = (rdev->new_data_offset
4111                                           - rdev->data_offset);
4112                         if (!mddev->reshape_backwards)
4113                                 diff = -diff;
4114                         if (diff < 0)
4115                                 diff = 0;
4116                         if (first || diff < min_offset_diff)
4117                                 min_offset_diff = diff;
4118                 }
4119         }
4120
4121         if (max(before_length, after_length) > min_offset_diff)
4122                 return -EINVAL;
4123
4124         if (spares < mddev->delta_disks)
4125                 return -EINVAL;
4126
4127         conf->offset_diff = min_offset_diff;
4128         spin_lock_irq(&conf->device_lock);
4129         if (conf->mirrors_new) {
4130                 memcpy(conf->mirrors_new, conf->mirrors,
4131                        sizeof(struct raid10_info)*conf->prev.raid_disks);
4132                 smp_mb();
4133                 kfree(conf->mirrors_old); /* FIXME and elsewhere */
4134                 conf->mirrors_old = conf->mirrors;
4135                 conf->mirrors = conf->mirrors_new;
4136                 conf->mirrors_new = NULL;
4137         }
4138         setup_geo(&conf->geo, mddev, geo_start);
4139         smp_mb();
4140         if (mddev->reshape_backwards) {
4141                 sector_t size = raid10_size(mddev, 0, 0);
4142                 if (size < mddev->array_sectors) {
4143                         spin_unlock_irq(&conf->device_lock);
4144                         printk(KERN_ERR "md/raid10:%s: array size must be reduce before number of disks\n",
4145                                mdname(mddev));
4146                         return -EINVAL;
4147                 }
4148                 mddev->resync_max_sectors = size;
4149                 conf->reshape_progress = size;
4150         } else
4151                 conf->reshape_progress = 0;
4152         spin_unlock_irq(&conf->device_lock);
4153
4154         if (mddev->delta_disks && mddev->bitmap) {
4155                 ret = bitmap_resize(mddev->bitmap,
4156                                     raid10_size(mddev, 0,
4157                                                 conf->geo.raid_disks),
4158                                     0, 0);
4159                 if (ret)
4160                         goto abort;
4161         }
4162         if (mddev->delta_disks > 0) {
4163                 rdev_for_each(rdev, mddev)
4164                         if (rdev->raid_disk < 0 &&
4165                             !test_bit(Faulty, &rdev->flags)) {
4166                                 if (raid10_add_disk(mddev, rdev) == 0) {
4167                                         if (rdev->raid_disk >=
4168                                             conf->prev.raid_disks)
4169                                                 set_bit(In_sync, &rdev->flags);
4170                                         else
4171                                                 rdev->recovery_offset = 0;
4172
4173                                         if (sysfs_link_rdev(mddev, rdev))
4174                                                 /* Failure here  is OK */;
4175                                 }
4176                         } else if (rdev->raid_disk >= conf->prev.raid_disks
4177                                    && !test_bit(Faulty, &rdev->flags)) {
4178                                 /* This is a spare that was manually added */
4179                                 set_bit(In_sync, &rdev->flags);
4180                         }
4181         }
4182         /* When a reshape changes the number of devices,
4183          * ->degraded is measured against the larger of the
4184          * pre and  post numbers.
4185          */
4186         spin_lock_irq(&conf->device_lock);
4187         mddev->degraded = calc_degraded(conf);
4188         spin_unlock_irq(&conf->device_lock);
4189         mddev->raid_disks = conf->geo.raid_disks;
4190         mddev->reshape_position = conf->reshape_progress;
4191         set_bit(MD_CHANGE_DEVS, &mddev->flags);
4192
4193         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4194         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4195         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4196         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4197
4198         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4199                                                 "reshape");
4200         if (!mddev->sync_thread) {
4201                 ret = -EAGAIN;
4202                 goto abort;
4203         }
4204         conf->reshape_checkpoint = jiffies;
4205         md_wakeup_thread(mddev->sync_thread);
4206         md_new_event(mddev);
4207         return 0;
4208
4209 abort:
4210         mddev->recovery = 0;
4211         spin_lock_irq(&conf->device_lock);
4212         conf->geo = conf->prev;
4213         mddev->raid_disks = conf->geo.raid_disks;
4214         rdev_for_each(rdev, mddev)
4215                 rdev->new_data_offset = rdev->data_offset;
4216         smp_wmb();
4217         conf->reshape_progress = MaxSector;
4218         mddev->reshape_position = MaxSector;
4219         spin_unlock_irq(&conf->device_lock);
4220         return ret;
4221 }
4222
4223 /* Calculate the last device-address that could contain
4224  * any block from the chunk that includes the array-address 's'
4225  * and report the next address.
4226  * i.e. the address returned will be chunk-aligned and after
4227  * any data that is in the chunk containing 's'.
4228  */
4229 static sector_t last_dev_address(sector_t s, struct geom *geo)
4230 {
4231         s = (s | geo->chunk_mask) + 1;
4232         s >>= geo->chunk_shift;
4233         s *= geo->near_copies;
4234         s = DIV_ROUND_UP_SECTOR_T(s, geo->raid_disks);
4235         s *= geo->far_copies;
4236         s <<= geo->chunk_shift;
4237         return s;
4238 }
4239
4240 /* Calculate the first device-address that could contain
4241  * any block from the chunk that includes the array-address 's'.
4242  * This too will be the start of a chunk
4243  */
4244 static sector_t first_dev_address(sector_t s, struct geom *geo)
4245 {
4246         s >>= geo->chunk_shift;
4247         s *= geo->near_copies;
4248         sector_div(s, geo->raid_disks);
4249         s *= geo->far_copies;
4250         s <<= geo->chunk_shift;
4251         return s;
4252 }
4253
4254 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
4255                                 int *skipped)
4256 {
4257         /* We simply copy at most one chunk (smallest of old and new)
4258          * at a time, possibly less if that exceeds RESYNC_PAGES,
4259          * or we hit a bad block or something.
4260          * This might mean we pause for normal IO in the middle of
4261          * a chunk, but that is not a problem was mddev->reshape_position
4262          * can record any location.
4263          *
4264          * If we will want to write to a location that isn't
4265          * yet recorded as 'safe' (i.e. in metadata on disk) then
4266          * we need to flush all reshape requests and update the metadata.
4267          *
4268          * When reshaping forwards (e.g. to more devices), we interpret
4269          * 'safe' as the earliest block which might not have been copied
4270          * down yet.  We divide this by previous stripe size and multiply
4271          * by previous stripe length to get lowest device offset that we
4272          * cannot write to yet.
4273          * We interpret 'sector_nr' as an address that we want to write to.
4274          * From this we use last_device_address() to find where we might
4275          * write to, and first_device_address on the  'safe' position.
4276          * If this 'next' write position is after the 'safe' position,
4277          * we must update the metadata to increase the 'safe' position.
4278          *
4279          * When reshaping backwards, we round in the opposite direction
4280          * and perform the reverse test:  next write position must not be
4281          * less than current safe position.
4282          *
4283          * In all this the minimum difference in data offsets
4284          * (conf->offset_diff - always positive) allows a bit of slack,
4285          * so next can be after 'safe', but not by more than offset_disk
4286          *
4287          * We need to prepare all the bios here before we start any IO
4288          * to ensure the size we choose is acceptable to all devices.
4289          * The means one for each copy for write-out and an extra one for
4290          * read-in.
4291          * We store the read-in bio in ->master_bio and the others in
4292          * ->devs[x].bio and ->devs[x].repl_bio.
4293          */
4294         struct r10conf *conf = mddev->private;
4295         struct r10bio *r10_bio;
4296         sector_t next, safe, last;
4297         int max_sectors;
4298         int nr_sectors;
4299         int s;
4300         struct md_rdev *rdev;
4301         int need_flush = 0;
4302         struct bio *blist;
4303         struct bio *bio, *read_bio;
4304         int sectors_done = 0;
4305
4306         if (sector_nr == 0) {
4307                 /* If restarting in the middle, skip the initial sectors */
4308                 if (mddev->reshape_backwards &&
4309                     conf->reshape_progress < raid10_size(mddev, 0, 0)) {
4310                         sector_nr = (raid10_size(mddev, 0, 0)
4311                                      - conf->reshape_progress);
4312                 } else if (!mddev->reshape_backwards &&
4313                            conf->reshape_progress > 0)
4314                         sector_nr = conf->reshape_progress;
4315                 if (sector_nr) {
4316                         mddev->curr_resync_completed = sector_nr;
4317                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4318                         *skipped = 1;
4319                         return sector_nr;
4320                 }
4321         }
4322
4323         /* We don't use sector_nr to track where we are up to
4324          * as that doesn't work well for ->reshape_backwards.
4325          * So just use ->reshape_progress.
4326          */
4327         if (mddev->reshape_backwards) {
4328                 /* 'next' is the earliest device address that we might
4329                  * write to for this chunk in the new layout
4330                  */
4331                 next = first_dev_address(conf->reshape_progress - 1,
4332                                          &conf->geo);
4333
4334                 /* 'safe' is the last device address that we might read from
4335                  * in the old layout after a restart
4336                  */
4337                 safe = last_dev_address(conf->reshape_safe - 1,
4338                                         &conf->prev);
4339
4340                 if (next + conf->offset_diff < safe)
4341                         need_flush = 1;
4342
4343                 last = conf->reshape_progress - 1;
4344                 sector_nr = last & ~(sector_t)(conf->geo.chunk_mask
4345                                                & conf->prev.chunk_mask);
4346                 if (sector_nr + RESYNC_BLOCK_SIZE/512 < last)
4347                         sector_nr = last + 1 - RESYNC_BLOCK_SIZE/512;
4348         } else {
4349                 /* 'next' is after the last device address that we
4350                  * might write to for this chunk in the new layout
4351                  */
4352                 next = last_dev_address(conf->reshape_progress, &conf->geo);
4353
4354                 /* 'safe' is the earliest device address that we might
4355                  * read from in the old layout after a restart
4356                  */
4357                 safe = first_dev_address(conf->reshape_safe, &conf->prev);
4358
4359                 /* Need to update metadata if 'next' might be beyond 'safe'
4360                  * as that would possibly corrupt data
4361                  */
4362                 if (next > safe + conf->offset_diff)
4363                         need_flush = 1;
4364
4365                 sector_nr = conf->reshape_progress;
4366                 last  = sector_nr | (conf->geo.chunk_mask
4367                                      & conf->prev.chunk_mask);
4368
4369                 if (sector_nr + RESYNC_BLOCK_SIZE/512 <= last)
4370                         last = sector_nr + RESYNC_BLOCK_SIZE/512 - 1;
4371         }
4372
4373         if (need_flush ||
4374             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4375                 /* Need to update reshape_position in metadata */
4376                 wait_barrier(conf);
4377                 mddev->reshape_position = conf->reshape_progress;
4378                 if (mddev->reshape_backwards)
4379                         mddev->curr_resync_completed = raid10_size(mddev, 0, 0)
4380                                 - conf->reshape_progress;
4381                 else
4382                         mddev->curr_resync_completed = conf->reshape_progress;
4383                 conf->reshape_checkpoint = jiffies;
4384                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4385                 md_wakeup_thread(mddev->thread);
4386                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4387                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4388                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
4389                         allow_barrier(conf);
4390                         return sectors_done;
4391                 }
4392                 conf->reshape_safe = mddev->reshape_position;
4393                 allow_barrier(conf);
4394         }
4395
4396 read_more:
4397         /* Now schedule reads for blocks from sector_nr to last */
4398         r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
4399         raise_barrier(conf, sectors_done != 0);
4400         atomic_set(&r10_bio->remaining, 0);
4401         r10_bio->mddev = mddev;
4402         r10_bio->sector = sector_nr;
4403         set_bit(R10BIO_IsReshape, &r10_bio->state);
4404         r10_bio->sectors = last - sector_nr + 1;
4405         rdev = read_balance(conf, r10_bio, &max_sectors);
4406         BUG_ON(!test_bit(R10BIO_Previous, &r10_bio->state));
4407
4408         if (!rdev) {
4409                 /* Cannot read from here, so need to record bad blocks
4410                  * on all the target devices.
4411                  */
4412                 // FIXME
4413                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
4414                 return sectors_done;
4415         }
4416
4417         read_bio = bio_alloc_mddev(GFP_KERNEL, RESYNC_PAGES, mddev);
4418
4419         read_bio->bi_bdev = rdev->bdev;
4420         read_bio->bi_sector = (r10_bio->devs[r10_bio->read_slot].addr
4421                                + rdev->data_offset);
4422         read_bio->bi_private = r10_bio;
4423         read_bio->bi_end_io = end_sync_read;
4424         read_bio->bi_rw = READ;
4425         read_bio->bi_flags &= ~(BIO_POOL_MASK - 1);
4426         read_bio->bi_flags |= 1 << BIO_UPTODATE;
4427         read_bio->bi_vcnt = 0;
4428         read_bio->bi_size = 0;
4429         r10_bio->master_bio = read_bio;
4430         r10_bio->read_slot = r10_bio->devs[r10_bio->read_slot].devnum;
4431
4432         /* Now find the locations in the new layout */
4433         __raid10_find_phys(&conf->geo, r10_bio);
4434
4435         blist = read_bio;
4436         read_bio->bi_next = NULL;
4437
4438         for (s = 0; s < conf->copies*2; s++) {
4439                 struct bio *b;
4440                 int d = r10_bio->devs[s/2].devnum;
4441                 struct md_rdev *rdev2;
4442                 if (s&1) {
4443                         rdev2 = conf->mirrors[d].replacement;
4444                         b = r10_bio->devs[s/2].repl_bio;
4445                 } else {
4446                         rdev2 = conf->mirrors[d].rdev;
4447                         b = r10_bio->devs[s/2].bio;
4448                 }
4449                 if (!rdev2 || test_bit(Faulty, &rdev2->flags))
4450                         continue;
4451
4452                 bio_reset(b);
4453                 b->bi_bdev = rdev2->bdev;
4454                 b->bi_sector = r10_bio->devs[s/2].addr + rdev2->new_data_offset;
4455                 b->bi_private = r10_bio;
4456                 b->bi_end_io = end_reshape_write;
4457                 b->bi_rw = WRITE;
4458                 b->bi_next = blist;
4459                 blist = b;
4460         }
4461
4462         /* Now add as many pages as possible to all of these bios. */
4463
4464         nr_sectors = 0;
4465         for (s = 0 ; s < max_sectors; s += PAGE_SIZE >> 9) {
4466                 struct page *page = r10_bio->devs[0].bio->bi_io_vec[s/(PAGE_SIZE>>9)].bv_page;
4467                 int len = (max_sectors - s) << 9;
4468                 if (len > PAGE_SIZE)
4469                         len = PAGE_SIZE;
4470                 for (bio = blist; bio ; bio = bio->bi_next) {
4471                         struct bio *bio2;
4472                         if (bio_add_page(bio, page, len, 0))
4473                                 continue;
4474
4475                         /* Didn't fit, must stop */
4476                         for (bio2 = blist;
4477                              bio2 && bio2 != bio;
4478                              bio2 = bio2->bi_next) {
4479                                 /* Remove last page from this bio */
4480                                 bio2->bi_vcnt--;
4481                                 bio2->bi_size -= len;
4482                                 bio2->bi_flags &= ~(1<<BIO_SEG_VALID);
4483                         }
4484                         goto bio_full;
4485                 }
4486                 sector_nr += len >> 9;
4487                 nr_sectors += len >> 9;
4488         }
4489 bio_full:
4490         r10_bio->sectors = nr_sectors;
4491
4492         /* Now submit the read */
4493         md_sync_acct(read_bio->bi_bdev, r10_bio->sectors);
4494         atomic_inc(&r10_bio->remaining);
4495         read_bio->bi_next = NULL;
4496         generic_make_request(read_bio);
4497         sector_nr += nr_sectors;
4498         sectors_done += nr_sectors;
4499         if (sector_nr <= last)
4500                 goto read_more;
4501
4502         /* Now that we have done the whole section we can
4503          * update reshape_progress
4504          */
4505         if (mddev->reshape_backwards)
4506                 conf->reshape_progress -= sectors_done;
4507         else
4508                 conf->reshape_progress += sectors_done;
4509
4510         return sectors_done;
4511 }
4512
4513 static void end_reshape_request(struct r10bio *r10_bio);
4514 static int handle_reshape_read_error(struct mddev *mddev,
4515                                      struct r10bio *r10_bio);
4516 static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio)
4517 {
4518         /* Reshape read completed.  Hopefully we have a block
4519          * to write out.
4520          * If we got a read error then we do sync 1-page reads from
4521          * elsewhere until we find the data - or give up.
4522          */
4523         struct r10conf *conf = mddev->private;
4524         int s;
4525
4526         if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
4527                 if (handle_reshape_read_error(mddev, r10_bio) < 0) {
4528                         /* Reshape has been aborted */
4529                         md_done_sync(mddev, r10_bio->sectors, 0);
4530                         return;
4531                 }
4532
4533         /* We definitely have the data in the pages, schedule the
4534          * writes.
4535          */
4536         atomic_set(&r10_bio->remaining, 1);
4537         for (s = 0; s < conf->copies*2; s++) {
4538                 struct bio *b;
4539                 int d = r10_bio->devs[s/2].devnum;
4540                 struct md_rdev *rdev;
4541                 if (s&1) {
4542                         rdev = conf->mirrors[d].replacement;
4543                         b = r10_bio->devs[s/2].repl_bio;
4544                 } else {
4545                         rdev = conf->mirrors[d].rdev;
4546                         b = r10_bio->devs[s/2].bio;
4547                 }
4548                 if (!rdev || test_bit(Faulty, &rdev->flags))
4549                         continue;
4550                 atomic_inc(&rdev->nr_pending);
4551                 md_sync_acct(b->bi_bdev, r10_bio->sectors);
4552                 atomic_inc(&r10_bio->remaining);
4553                 b->bi_next = NULL;
4554                 generic_make_request(b);
4555         }
4556         end_reshape_request(r10_bio);
4557 }
4558
4559 static void end_reshape(struct r10conf *conf)
4560 {
4561         if (test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery))
4562                 return;
4563
4564         spin_lock_irq(&conf->device_lock);
4565         conf->prev = conf->geo;
4566         md_finish_reshape(conf->mddev);
4567         smp_wmb();
4568         conf->reshape_progress = MaxSector;
4569         spin_unlock_irq(&conf->device_lock);
4570
4571         /* read-ahead size must cover two whole stripes, which is
4572          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4573          */
4574         if (conf->mddev->queue) {
4575                 int stripe = conf->geo.raid_disks *
4576                         ((conf->mddev->chunk_sectors << 9) / PAGE_SIZE);
4577                 stripe /= conf->geo.near_copies;
4578                 if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4579                         conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4580         }
4581         conf->fullsync = 0;
4582 }
4583
4584
4585 static int handle_reshape_read_error(struct mddev *mddev,
4586                                      struct r10bio *r10_bio)
4587 {
4588         /* Use sync reads to get the blocks from somewhere else */
4589         int sectors = r10_bio->sectors;
4590         struct r10conf *conf = mddev->private;
4591         struct {
4592                 struct r10bio r10_bio;
4593                 struct r10dev devs[conf->copies];
4594         } on_stack;
4595         struct r10bio *r10b = &on_stack.r10_bio;
4596         int slot = 0;
4597         int idx = 0;
4598         struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;
4599
4600         r10b->sector = r10_bio->sector;
4601         __raid10_find_phys(&conf->prev, r10b);
4602
4603         while (sectors) {
4604                 int s = sectors;
4605                 int success = 0;
4606                 int first_slot = slot;
4607
4608                 if (s > (PAGE_SIZE >> 9))
4609                         s = PAGE_SIZE >> 9;
4610
4611                 while (!success) {
4612                         int d = r10b->devs[slot].devnum;
4613                         struct md_rdev *rdev = conf->mirrors[d].rdev;
4614                         sector_t addr;
4615                         if (rdev == NULL ||
4616                             test_bit(Faulty, &rdev->flags) ||
4617                             !test_bit(In_sync, &rdev->flags))
4618                                 goto failed;
4619
4620                         addr = r10b->devs[slot].addr + idx * PAGE_SIZE;
4621                         success = sync_page_io(rdev,
4622                                                addr,
4623                                                s << 9,
4624                                                bvec[idx].bv_page,
4625                                                READ, false);
4626                         if (success)
4627                                 break;
4628                 failed:
4629                         slot++;
4630                         if (slot >= conf->copies)
4631                                 slot = 0;
4632                         if (slot == first_slot)
4633                                 break;
4634                 }
4635                 if (!success) {
4636                         /* couldn't read this block, must give up */
4637                         set_bit(MD_RECOVERY_INTR,
4638                                 &mddev->recovery);
4639                         return -EIO;
4640                 }
4641                 sectors -= s;
4642                 idx++;
4643         }
4644         return 0;
4645 }
4646
4647 static void end_reshape_write(struct bio *bio, int error)
4648 {
4649         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
4650         struct r10bio *r10_bio = bio->bi_private;
4651         struct mddev *mddev = r10_bio->mddev;
4652         struct r10conf *conf = mddev->private;
4653         int d;
4654         int slot;
4655         int repl;
4656         struct md_rdev *rdev = NULL;
4657
4658         d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
4659         if (repl)
4660                 rdev = conf->mirrors[d].replacement;
4661         if (!rdev) {
4662                 smp_mb();
4663                 rdev = conf->mirrors[d].rdev;
4664         }
4665
4666         if (!uptodate) {
4667                 /* FIXME should record badblock */
4668                 md_error(mddev, rdev);
4669         }
4670
4671         rdev_dec_pending(rdev, mddev);
4672         end_reshape_request(r10_bio);
4673 }
4674
4675 static void end_reshape_request(struct r10bio *r10_bio)
4676 {
4677         if (!atomic_dec_and_test(&r10_bio->remaining))
4678                 return;
4679         md_done_sync(r10_bio->mddev, r10_bio->sectors, 1);
4680         bio_put(r10_bio->master_bio);
4681         put_buf(r10_bio);
4682 }
4683
4684 static void raid10_finish_reshape(struct mddev *mddev)
4685 {
4686         struct r10conf *conf = mddev->private;
4687
4688         if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4689                 return;
4690
4691         if (mddev->delta_disks > 0) {
4692                 sector_t size = raid10_size(mddev, 0, 0);
4693                 md_set_array_sectors(mddev, size);
4694                 if (mddev->recovery_cp > mddev->resync_max_sectors) {
4695                         mddev->recovery_cp = mddev->resync_max_sectors;
4696                         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4697                 }
4698                 mddev->resync_max_sectors = size;
4699                 set_capacity(mddev->gendisk, mddev->array_sectors);
4700                 revalidate_disk(mddev->gendisk);
4701         } else {
4702                 int d;
4703                 for (d = conf->geo.raid_disks ;
4704                      d < conf->geo.raid_disks - mddev->delta_disks;
4705                      d++) {
4706                         struct md_rdev *rdev = conf->mirrors[d].rdev;
4707                         if (rdev)
4708                                 clear_bit(In_sync, &rdev->flags);
4709                         rdev = conf->mirrors[d].replacement;
4710                         if (rdev)
4711                                 clear_bit(In_sync, &rdev->flags);
4712                 }
4713         }
4714         mddev->layout = mddev->new_layout;
4715         mddev->chunk_sectors = 1 << conf->geo.chunk_shift;
4716         mddev->reshape_position = MaxSector;
4717         mddev->delta_disks = 0;
4718         mddev->reshape_backwards = 0;
4719 }
4720
4721 static struct md_personality raid10_personality =
4722 {
4723         .name           = "raid10",
4724         .level          = 10,
4725         .owner          = THIS_MODULE,
4726         .make_request   = make_request,
4727         .run            = run,
4728         .stop           = stop,
4729         .status         = status,
4730         .error_handler  = error,
4731         .hot_add_disk   = raid10_add_disk,
4732         .hot_remove_disk= raid10_remove_disk,
4733         .spare_active   = raid10_spare_active,
4734         .sync_request   = sync_request,
4735         .quiesce        = raid10_quiesce,
4736         .size           = raid10_size,
4737         .resize         = raid10_resize,
4738         .takeover       = raid10_takeover,
4739         .check_reshape  = raid10_check_reshape,
4740         .start_reshape  = raid10_start_reshape,
4741         .finish_reshape = raid10_finish_reshape,
4742 };
4743
4744 static int __init raid_init(void)
4745 {
4746         return register_md_personality(&raid10_personality);
4747 }
4748
4749 static void raid_exit(void)
4750 {
4751         unregister_md_personality(&raid10_personality);
4752 }
4753
4754 module_init(raid_init);
4755 module_exit(raid_exit);
4756 MODULE_LICENSE("GPL");
4757 MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
4758 MODULE_ALIAS("md-personality-9"); /* RAID10 */
4759 MODULE_ALIAS("md-raid10");
4760 MODULE_ALIAS("md-level-10");
4761
4762 module_param(max_queued_requests, int, S_IRUGO|S_IWUSR);