i2c: tegra: Add stub runtime power management
[linux-2.6.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/seq_file.h>
25 #include <linux/ratelimit.h>
26 #include "md.h"
27 #include "raid10.h"
28 #include "raid0.h"
29 #include "bitmap.h"
30
31 /*
32  * RAID10 provides a combination of RAID0 and RAID1 functionality.
33  * The layout of data is defined by
34  *    chunk_size
35  *    raid_disks
36  *    near_copies (stored in low byte of layout)
37  *    far_copies (stored in second byte of layout)
38  *    far_offset (stored in bit 16 of layout )
39  *
40  * The data to be stored is divided into chunks using chunksize.
41  * Each device is divided into far_copies sections.
42  * In each section, chunks are laid out in a style similar to raid0, but
43  * near_copies copies of each chunk is stored (each on a different drive).
44  * The starting device for each section is offset near_copies from the starting
45  * device of the previous section.
46  * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
47  * drive.
48  * near_copies and far_copies must be at least one, and their product is at most
49  * raid_disks.
50  *
51  * If far_offset is true, then the far_copies are handled a bit differently.
52  * The copies are still in different stripes, but instead of be very far apart
53  * on disk, there are adjacent stripes.
54  */
55
56 /*
57  * Number of guaranteed r10bios in case of extreme VM load:
58  */
59 #define NR_RAID10_BIOS 256
60
61 static void allow_barrier(conf_t *conf);
62 static void lower_barrier(conf_t *conf);
63
64 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
65 {
66         conf_t *conf = data;
67         int size = offsetof(struct r10bio_s, devs[conf->copies]);
68
69         /* allocate a r10bio with room for raid_disks entries in the bios array */
70         return kzalloc(size, gfp_flags);
71 }
72
73 static void r10bio_pool_free(void *r10_bio, void *data)
74 {
75         kfree(r10_bio);
76 }
77
78 /* Maximum size of each resync request */
79 #define RESYNC_BLOCK_SIZE (64*1024)
80 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
81 /* amount of memory to reserve for resync requests */
82 #define RESYNC_WINDOW (1024*1024)
83 /* maximum number of concurrent requests, memory permitting */
84 #define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
85
86 /*
87  * When performing a resync, we need to read and compare, so
88  * we need as many pages are there are copies.
89  * When performing a recovery, we need 2 bios, one for read,
90  * one for write (we recover only one drive per r10buf)
91  *
92  */
93 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
94 {
95         conf_t *conf = data;
96         struct page *page;
97         r10bio_t *r10_bio;
98         struct bio *bio;
99         int i, j;
100         int nalloc;
101
102         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
103         if (!r10_bio)
104                 return NULL;
105
106         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
107                 nalloc = conf->copies; /* resync */
108         else
109                 nalloc = 2; /* recovery */
110
111         /*
112          * Allocate bios.
113          */
114         for (j = nalloc ; j-- ; ) {
115                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
116                 if (!bio)
117                         goto out_free_bio;
118                 r10_bio->devs[j].bio = bio;
119         }
120         /*
121          * Allocate RESYNC_PAGES data pages and attach them
122          * where needed.
123          */
124         for (j = 0 ; j < nalloc; j++) {
125                 bio = r10_bio->devs[j].bio;
126                 for (i = 0; i < RESYNC_PAGES; i++) {
127                         if (j == 1 && !test_bit(MD_RECOVERY_SYNC,
128                                                 &conf->mddev->recovery)) {
129                                 /* we can share bv_page's during recovery */
130                                 struct bio *rbio = r10_bio->devs[0].bio;
131                                 page = rbio->bi_io_vec[i].bv_page;
132                                 get_page(page);
133                         } else
134                                 page = alloc_page(gfp_flags);
135                         if (unlikely(!page))
136                                 goto out_free_pages;
137
138                         bio->bi_io_vec[i].bv_page = page;
139                 }
140         }
141
142         return r10_bio;
143
144 out_free_pages:
145         for ( ; i > 0 ; i--)
146                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
147         while (j--)
148                 for (i = 0; i < RESYNC_PAGES ; i++)
149                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
150         j = -1;
151 out_free_bio:
152         while ( ++j < nalloc )
153                 bio_put(r10_bio->devs[j].bio);
154         r10bio_pool_free(r10_bio, conf);
155         return NULL;
156 }
157
158 static void r10buf_pool_free(void *__r10_bio, void *data)
159 {
160         int i;
161         conf_t *conf = data;
162         r10bio_t *r10bio = __r10_bio;
163         int j;
164
165         for (j=0; j < conf->copies; j++) {
166                 struct bio *bio = r10bio->devs[j].bio;
167                 if (bio) {
168                         for (i = 0; i < RESYNC_PAGES; i++) {
169                                 safe_put_page(bio->bi_io_vec[i].bv_page);
170                                 bio->bi_io_vec[i].bv_page = NULL;
171                         }
172                         bio_put(bio);
173                 }
174         }
175         r10bio_pool_free(r10bio, conf);
176 }
177
178 static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
179 {
180         int i;
181
182         for (i = 0; i < conf->copies; i++) {
183                 struct bio **bio = & r10_bio->devs[i].bio;
184                 if (!BIO_SPECIAL(*bio))
185                         bio_put(*bio);
186                 *bio = NULL;
187         }
188 }
189
190 static void free_r10bio(r10bio_t *r10_bio)
191 {
192         conf_t *conf = r10_bio->mddev->private;
193
194         put_all_bios(conf, r10_bio);
195         mempool_free(r10_bio, conf->r10bio_pool);
196 }
197
198 static void put_buf(r10bio_t *r10_bio)
199 {
200         conf_t *conf = r10_bio->mddev->private;
201
202         mempool_free(r10_bio, conf->r10buf_pool);
203
204         lower_barrier(conf);
205 }
206
207 static void reschedule_retry(r10bio_t *r10_bio)
208 {
209         unsigned long flags;
210         mddev_t *mddev = r10_bio->mddev;
211         conf_t *conf = mddev->private;
212
213         spin_lock_irqsave(&conf->device_lock, flags);
214         list_add(&r10_bio->retry_list, &conf->retry_list);
215         conf->nr_queued ++;
216         spin_unlock_irqrestore(&conf->device_lock, flags);
217
218         /* wake up frozen array... */
219         wake_up(&conf->wait_barrier);
220
221         md_wakeup_thread(mddev->thread);
222 }
223
224 /*
225  * raid_end_bio_io() is called when we have finished servicing a mirrored
226  * operation and are ready to return a success/failure code to the buffer
227  * cache layer.
228  */
229 static void raid_end_bio_io(r10bio_t *r10_bio)
230 {
231         struct bio *bio = r10_bio->master_bio;
232         int done;
233         conf_t *conf = r10_bio->mddev->private;
234
235         if (bio->bi_phys_segments) {
236                 unsigned long flags;
237                 spin_lock_irqsave(&conf->device_lock, flags);
238                 bio->bi_phys_segments--;
239                 done = (bio->bi_phys_segments == 0);
240                 spin_unlock_irqrestore(&conf->device_lock, flags);
241         } else
242                 done = 1;
243         if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
244                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
245         if (done) {
246                 bio_endio(bio, 0);
247                 /*
248                  * Wake up any possible resync thread that waits for the device
249                  * to go idle.
250                  */
251                 allow_barrier(conf);
252         }
253         free_r10bio(r10_bio);
254 }
255
256 /*
257  * Update disk head position estimator based on IRQ completion info.
258  */
259 static inline void update_head_pos(int slot, r10bio_t *r10_bio)
260 {
261         conf_t *conf = r10_bio->mddev->private;
262
263         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
264                 r10_bio->devs[slot].addr + (r10_bio->sectors);
265 }
266
267 /*
268  * Find the disk number which triggered given bio
269  */
270 static int find_bio_disk(conf_t *conf, r10bio_t *r10_bio,
271                          struct bio *bio, int *slotp)
272 {
273         int slot;
274
275         for (slot = 0; slot < conf->copies; slot++)
276                 if (r10_bio->devs[slot].bio == bio)
277                         break;
278
279         BUG_ON(slot == conf->copies);
280         update_head_pos(slot, r10_bio);
281
282         if (slotp)
283                 *slotp = slot;
284         return r10_bio->devs[slot].devnum;
285 }
286
287 static void raid10_end_read_request(struct bio *bio, int error)
288 {
289         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
290         r10bio_t *r10_bio = bio->bi_private;
291         int slot, dev;
292         conf_t *conf = r10_bio->mddev->private;
293
294
295         slot = r10_bio->read_slot;
296         dev = r10_bio->devs[slot].devnum;
297         /*
298          * this branch is our 'one mirror IO has finished' event handler:
299          */
300         update_head_pos(slot, r10_bio);
301
302         if (uptodate) {
303                 /*
304                  * Set R10BIO_Uptodate in our master bio, so that
305                  * we will return a good error code to the higher
306                  * levels even if IO on some other mirrored buffer fails.
307                  *
308                  * The 'master' represents the composite IO operation to
309                  * user-side. So if something waits for IO, then it will
310                  * wait for the 'master' bio.
311                  */
312                 set_bit(R10BIO_Uptodate, &r10_bio->state);
313                 raid_end_bio_io(r10_bio);
314                 rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
315         } else {
316                 /*
317                  * oops, read error - keep the refcount on the rdev
318                  */
319                 char b[BDEVNAME_SIZE];
320                 printk_ratelimited(KERN_ERR
321                                    "md/raid10:%s: %s: rescheduling sector %llu\n",
322                                    mdname(conf->mddev),
323                                    bdevname(conf->mirrors[dev].rdev->bdev, b),
324                                    (unsigned long long)r10_bio->sector);
325                 set_bit(R10BIO_ReadError, &r10_bio->state);
326                 reschedule_retry(r10_bio);
327         }
328 }
329
330 static void close_write(r10bio_t *r10_bio)
331 {
332         /* clear the bitmap if all writes complete successfully */
333         bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
334                         r10_bio->sectors,
335                         !test_bit(R10BIO_Degraded, &r10_bio->state),
336                         0);
337         md_write_end(r10_bio->mddev);
338 }
339
340 static void one_write_done(r10bio_t *r10_bio)
341 {
342         if (atomic_dec_and_test(&r10_bio->remaining)) {
343                 if (test_bit(R10BIO_WriteError, &r10_bio->state))
344                         reschedule_retry(r10_bio);
345                 else {
346                         close_write(r10_bio);
347                         if (test_bit(R10BIO_MadeGood, &r10_bio->state))
348                                 reschedule_retry(r10_bio);
349                         else
350                                 raid_end_bio_io(r10_bio);
351                 }
352         }
353 }
354
355 static void raid10_end_write_request(struct bio *bio, int error)
356 {
357         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
358         r10bio_t *r10_bio = bio->bi_private;
359         int dev;
360         int dec_rdev = 1;
361         conf_t *conf = r10_bio->mddev->private;
362         int slot;
363
364         dev = find_bio_disk(conf, r10_bio, bio, &slot);
365
366         /*
367          * this branch is our 'one mirror IO has finished' event handler:
368          */
369         if (!uptodate) {
370                 set_bit(WriteErrorSeen, &conf->mirrors[dev].rdev->flags);
371                 set_bit(R10BIO_WriteError, &r10_bio->state);
372                 dec_rdev = 0;
373         } else {
374                 /*
375                  * Set R10BIO_Uptodate in our master bio, so that
376                  * we will return a good error code for to the higher
377                  * levels even if IO on some other mirrored buffer fails.
378                  *
379                  * The 'master' represents the composite IO operation to
380                  * user-side. So if something waits for IO, then it will
381                  * wait for the 'master' bio.
382                  */
383                 sector_t first_bad;
384                 int bad_sectors;
385
386                 set_bit(R10BIO_Uptodate, &r10_bio->state);
387
388                 /* Maybe we can clear some bad blocks. */
389                 if (is_badblock(conf->mirrors[dev].rdev,
390                                 r10_bio->devs[slot].addr,
391                                 r10_bio->sectors,
392                                 &first_bad, &bad_sectors)) {
393                         bio_put(bio);
394                         r10_bio->devs[slot].bio = IO_MADE_GOOD;
395                         dec_rdev = 0;
396                         set_bit(R10BIO_MadeGood, &r10_bio->state);
397                 }
398         }
399
400         /*
401          *
402          * Let's see if all mirrored write operations have finished
403          * already.
404          */
405         one_write_done(r10_bio);
406         if (dec_rdev)
407                 rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
408 }
409
410
411 /*
412  * RAID10 layout manager
413  * As well as the chunksize and raid_disks count, there are two
414  * parameters: near_copies and far_copies.
415  * near_copies * far_copies must be <= raid_disks.
416  * Normally one of these will be 1.
417  * If both are 1, we get raid0.
418  * If near_copies == raid_disks, we get raid1.
419  *
420  * Chunks are laid out in raid0 style with near_copies copies of the
421  * first chunk, followed by near_copies copies of the next chunk and
422  * so on.
423  * If far_copies > 1, then after 1/far_copies of the array has been assigned
424  * as described above, we start again with a device offset of near_copies.
425  * So we effectively have another copy of the whole array further down all
426  * the drives, but with blocks on different drives.
427  * With this layout, and block is never stored twice on the one device.
428  *
429  * raid10_find_phys finds the sector offset of a given virtual sector
430  * on each device that it is on.
431  *
432  * raid10_find_virt does the reverse mapping, from a device and a
433  * sector offset to a virtual address
434  */
435
436 static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
437 {
438         int n,f;
439         sector_t sector;
440         sector_t chunk;
441         sector_t stripe;
442         int dev;
443
444         int slot = 0;
445
446         /* now calculate first sector/dev */
447         chunk = r10bio->sector >> conf->chunk_shift;
448         sector = r10bio->sector & conf->chunk_mask;
449
450         chunk *= conf->near_copies;
451         stripe = chunk;
452         dev = sector_div(stripe, conf->raid_disks);
453         if (conf->far_offset)
454                 stripe *= conf->far_copies;
455
456         sector += stripe << conf->chunk_shift;
457
458         /* and calculate all the others */
459         for (n=0; n < conf->near_copies; n++) {
460                 int d = dev;
461                 sector_t s = sector;
462                 r10bio->devs[slot].addr = sector;
463                 r10bio->devs[slot].devnum = d;
464                 slot++;
465
466                 for (f = 1; f < conf->far_copies; f++) {
467                         d += conf->near_copies;
468                         if (d >= conf->raid_disks)
469                                 d -= conf->raid_disks;
470                         s += conf->stride;
471                         r10bio->devs[slot].devnum = d;
472                         r10bio->devs[slot].addr = s;
473                         slot++;
474                 }
475                 dev++;
476                 if (dev >= conf->raid_disks) {
477                         dev = 0;
478                         sector += (conf->chunk_mask + 1);
479                 }
480         }
481         BUG_ON(slot != conf->copies);
482 }
483
484 static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
485 {
486         sector_t offset, chunk, vchunk;
487
488         offset = sector & conf->chunk_mask;
489         if (conf->far_offset) {
490                 int fc;
491                 chunk = sector >> conf->chunk_shift;
492                 fc = sector_div(chunk, conf->far_copies);
493                 dev -= fc * conf->near_copies;
494                 if (dev < 0)
495                         dev += conf->raid_disks;
496         } else {
497                 while (sector >= conf->stride) {
498                         sector -= conf->stride;
499                         if (dev < conf->near_copies)
500                                 dev += conf->raid_disks - conf->near_copies;
501                         else
502                                 dev -= conf->near_copies;
503                 }
504                 chunk = sector >> conf->chunk_shift;
505         }
506         vchunk = chunk * conf->raid_disks + dev;
507         sector_div(vchunk, conf->near_copies);
508         return (vchunk << conf->chunk_shift) + offset;
509 }
510
511 /**
512  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
513  *      @q: request queue
514  *      @bvm: properties of new bio
515  *      @biovec: the request that could be merged to it.
516  *
517  *      Return amount of bytes we can accept at this offset
518  *      If near_copies == raid_disk, there are no striping issues,
519  *      but in that case, the function isn't called at all.
520  */
521 static int raid10_mergeable_bvec(struct request_queue *q,
522                                  struct bvec_merge_data *bvm,
523                                  struct bio_vec *biovec)
524 {
525         mddev_t *mddev = q->queuedata;
526         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
527         int max;
528         unsigned int chunk_sectors = mddev->chunk_sectors;
529         unsigned int bio_sectors = bvm->bi_size >> 9;
530
531         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
532         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
533         if (max <= biovec->bv_len && bio_sectors == 0)
534                 return biovec->bv_len;
535         else
536                 return max;
537 }
538
539 /*
540  * This routine returns the disk from which the requested read should
541  * be done. There is a per-array 'next expected sequential IO' sector
542  * number - if this matches on the next IO then we use the last disk.
543  * There is also a per-disk 'last know head position' sector that is
544  * maintained from IRQ contexts, both the normal and the resync IO
545  * completion handlers update this position correctly. If there is no
546  * perfect sequential match then we pick the disk whose head is closest.
547  *
548  * If there are 2 mirrors in the same 2 devices, performance degrades
549  * because position is mirror, not device based.
550  *
551  * The rdev for the device selected will have nr_pending incremented.
552  */
553
554 /*
555  * FIXME: possibly should rethink readbalancing and do it differently
556  * depending on near_copies / far_copies geometry.
557  */
558 static int read_balance(conf_t *conf, r10bio_t *r10_bio, int *max_sectors)
559 {
560         const sector_t this_sector = r10_bio->sector;
561         int disk, slot;
562         int sectors = r10_bio->sectors;
563         int best_good_sectors;
564         sector_t new_distance, best_dist;
565         mdk_rdev_t *rdev;
566         int do_balance;
567         int best_slot;
568
569         raid10_find_phys(conf, r10_bio);
570         rcu_read_lock();
571 retry:
572         sectors = r10_bio->sectors;
573         best_slot = -1;
574         best_dist = MaxSector;
575         best_good_sectors = 0;
576         do_balance = 1;
577         /*
578          * Check if we can balance. We can balance on the whole
579          * device if no resync is going on (recovery is ok), or below
580          * the resync window. We take the first readable disk when
581          * above the resync window.
582          */
583         if (conf->mddev->recovery_cp < MaxSector
584             && (this_sector + sectors >= conf->next_resync))
585                 do_balance = 0;
586
587         for (slot = 0; slot < conf->copies ; slot++) {
588                 sector_t first_bad;
589                 int bad_sectors;
590                 sector_t dev_sector;
591
592                 if (r10_bio->devs[slot].bio == IO_BLOCKED)
593                         continue;
594                 disk = r10_bio->devs[slot].devnum;
595                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
596                 if (rdev == NULL)
597                         continue;
598                 if (!test_bit(In_sync, &rdev->flags))
599                         continue;
600
601                 dev_sector = r10_bio->devs[slot].addr;
602                 if (is_badblock(rdev, dev_sector, sectors,
603                                 &first_bad, &bad_sectors)) {
604                         if (best_dist < MaxSector)
605                                 /* Already have a better slot */
606                                 continue;
607                         if (first_bad <= dev_sector) {
608                                 /* Cannot read here.  If this is the
609                                  * 'primary' device, then we must not read
610                                  * beyond 'bad_sectors' from another device.
611                                  */
612                                 bad_sectors -= (dev_sector - first_bad);
613                                 if (!do_balance && sectors > bad_sectors)
614                                         sectors = bad_sectors;
615                                 if (best_good_sectors > sectors)
616                                         best_good_sectors = sectors;
617                         } else {
618                                 sector_t good_sectors =
619                                         first_bad - dev_sector;
620                                 if (good_sectors > best_good_sectors) {
621                                         best_good_sectors = good_sectors;
622                                         best_slot = slot;
623                                 }
624                                 if (!do_balance)
625                                         /* Must read from here */
626                                         break;
627                         }
628                         continue;
629                 } else
630                         best_good_sectors = sectors;
631
632                 if (!do_balance)
633                         break;
634
635                 /* This optimisation is debatable, and completely destroys
636                  * sequential read speed for 'far copies' arrays.  So only
637                  * keep it for 'near' arrays, and review those later.
638                  */
639                 if (conf->near_copies > 1 && !atomic_read(&rdev->nr_pending))
640                         break;
641
642                 /* for far > 1 always use the lowest address */
643                 if (conf->far_copies > 1)
644                         new_distance = r10_bio->devs[slot].addr;
645                 else
646                         new_distance = abs(r10_bio->devs[slot].addr -
647                                            conf->mirrors[disk].head_position);
648                 if (new_distance < best_dist) {
649                         best_dist = new_distance;
650                         best_slot = slot;
651                 }
652         }
653         if (slot == conf->copies)
654                 slot = best_slot;
655
656         if (slot >= 0) {
657                 disk = r10_bio->devs[slot].devnum;
658                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
659                 if (!rdev)
660                         goto retry;
661                 atomic_inc(&rdev->nr_pending);
662                 if (test_bit(Faulty, &rdev->flags)) {
663                         /* Cannot risk returning a device that failed
664                          * before we inc'ed nr_pending
665                          */
666                         rdev_dec_pending(rdev, conf->mddev);
667                         goto retry;
668                 }
669                 r10_bio->read_slot = slot;
670         } else
671                 disk = -1;
672         rcu_read_unlock();
673         *max_sectors = best_good_sectors;
674
675         return disk;
676 }
677
678 static int raid10_congested(void *data, int bits)
679 {
680         mddev_t *mddev = data;
681         conf_t *conf = mddev->private;
682         int i, ret = 0;
683
684         if (mddev_congested(mddev, bits))
685                 return 1;
686         rcu_read_lock();
687         for (i = 0; i < conf->raid_disks && ret == 0; i++) {
688                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
689                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
690                         struct request_queue *q = bdev_get_queue(rdev->bdev);
691
692                         ret |= bdi_congested(&q->backing_dev_info, bits);
693                 }
694         }
695         rcu_read_unlock();
696         return ret;
697 }
698
699 static void flush_pending_writes(conf_t *conf)
700 {
701         /* Any writes that have been queued but are awaiting
702          * bitmap updates get flushed here.
703          */
704         spin_lock_irq(&conf->device_lock);
705
706         if (conf->pending_bio_list.head) {
707                 struct bio *bio;
708                 bio = bio_list_get(&conf->pending_bio_list);
709                 spin_unlock_irq(&conf->device_lock);
710                 /* flush any pending bitmap writes to disk
711                  * before proceeding w/ I/O */
712                 bitmap_unplug(conf->mddev->bitmap);
713
714                 while (bio) { /* submit pending writes */
715                         struct bio *next = bio->bi_next;
716                         bio->bi_next = NULL;
717                         generic_make_request(bio);
718                         bio = next;
719                 }
720         } else
721                 spin_unlock_irq(&conf->device_lock);
722 }
723
724 /* Barriers....
725  * Sometimes we need to suspend IO while we do something else,
726  * either some resync/recovery, or reconfigure the array.
727  * To do this we raise a 'barrier'.
728  * The 'barrier' is a counter that can be raised multiple times
729  * to count how many activities are happening which preclude
730  * normal IO.
731  * We can only raise the barrier if there is no pending IO.
732  * i.e. if nr_pending == 0.
733  * We choose only to raise the barrier if no-one is waiting for the
734  * barrier to go down.  This means that as soon as an IO request
735  * is ready, no other operations which require a barrier will start
736  * until the IO request has had a chance.
737  *
738  * So: regular IO calls 'wait_barrier'.  When that returns there
739  *    is no backgroup IO happening,  It must arrange to call
740  *    allow_barrier when it has finished its IO.
741  * backgroup IO calls must call raise_barrier.  Once that returns
742  *    there is no normal IO happeing.  It must arrange to call
743  *    lower_barrier when the particular background IO completes.
744  */
745
746 static void raise_barrier(conf_t *conf, int force)
747 {
748         BUG_ON(force && !conf->barrier);
749         spin_lock_irq(&conf->resync_lock);
750
751         /* Wait until no block IO is waiting (unless 'force') */
752         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
753                             conf->resync_lock, );
754
755         /* block any new IO from starting */
756         conf->barrier++;
757
758         /* Now wait for all pending IO to complete */
759         wait_event_lock_irq(conf->wait_barrier,
760                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
761                             conf->resync_lock, );
762
763         spin_unlock_irq(&conf->resync_lock);
764 }
765
766 static void lower_barrier(conf_t *conf)
767 {
768         unsigned long flags;
769         spin_lock_irqsave(&conf->resync_lock, flags);
770         conf->barrier--;
771         spin_unlock_irqrestore(&conf->resync_lock, flags);
772         wake_up(&conf->wait_barrier);
773 }
774
775 static void wait_barrier(conf_t *conf)
776 {
777         spin_lock_irq(&conf->resync_lock);
778         if (conf->barrier) {
779                 conf->nr_waiting++;
780                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
781                                     conf->resync_lock,
782                                     );
783                 conf->nr_waiting--;
784         }
785         conf->nr_pending++;
786         spin_unlock_irq(&conf->resync_lock);
787 }
788
789 static void allow_barrier(conf_t *conf)
790 {
791         unsigned long flags;
792         spin_lock_irqsave(&conf->resync_lock, flags);
793         conf->nr_pending--;
794         spin_unlock_irqrestore(&conf->resync_lock, flags);
795         wake_up(&conf->wait_barrier);
796 }
797
798 static void freeze_array(conf_t *conf)
799 {
800         /* stop syncio and normal IO and wait for everything to
801          * go quiet.
802          * We increment barrier and nr_waiting, and then
803          * wait until nr_pending match nr_queued+1
804          * This is called in the context of one normal IO request
805          * that has failed. Thus any sync request that might be pending
806          * will be blocked by nr_pending, and we need to wait for
807          * pending IO requests to complete or be queued for re-try.
808          * Thus the number queued (nr_queued) plus this request (1)
809          * must match the number of pending IOs (nr_pending) before
810          * we continue.
811          */
812         spin_lock_irq(&conf->resync_lock);
813         conf->barrier++;
814         conf->nr_waiting++;
815         wait_event_lock_irq(conf->wait_barrier,
816                             conf->nr_pending == conf->nr_queued+1,
817                             conf->resync_lock,
818                             flush_pending_writes(conf));
819
820         spin_unlock_irq(&conf->resync_lock);
821 }
822
823 static void unfreeze_array(conf_t *conf)
824 {
825         /* reverse the effect of the freeze */
826         spin_lock_irq(&conf->resync_lock);
827         conf->barrier--;
828         conf->nr_waiting--;
829         wake_up(&conf->wait_barrier);
830         spin_unlock_irq(&conf->resync_lock);
831 }
832
833 static int make_request(mddev_t *mddev, struct bio * bio)
834 {
835         conf_t *conf = mddev->private;
836         mirror_info_t *mirror;
837         r10bio_t *r10_bio;
838         struct bio *read_bio;
839         int i;
840         int chunk_sects = conf->chunk_mask + 1;
841         const int rw = bio_data_dir(bio);
842         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
843         const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
844         unsigned long flags;
845         mdk_rdev_t *blocked_rdev;
846         int plugged;
847         int sectors_handled;
848         int max_sectors;
849
850         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
851                 md_flush_request(mddev, bio);
852                 return 0;
853         }
854
855         /* If this request crosses a chunk boundary, we need to
856          * split it.  This will only happen for 1 PAGE (or less) requests.
857          */
858         if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
859                       > chunk_sects &&
860                     conf->near_copies < conf->raid_disks)) {
861                 struct bio_pair *bp;
862                 /* Sanity check -- queue functions should prevent this happening */
863                 if (bio->bi_vcnt != 1 ||
864                     bio->bi_idx != 0)
865                         goto bad_map;
866                 /* This is a one page bio that upper layers
867                  * refuse to split for us, so we need to split it.
868                  */
869                 bp = bio_split(bio,
870                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
871
872                 /* Each of these 'make_request' calls will call 'wait_barrier'.
873                  * If the first succeeds but the second blocks due to the resync
874                  * thread raising the barrier, we will deadlock because the
875                  * IO to the underlying device will be queued in generic_make_request
876                  * and will never complete, so will never reduce nr_pending.
877                  * So increment nr_waiting here so no new raise_barriers will
878                  * succeed, and so the second wait_barrier cannot block.
879                  */
880                 spin_lock_irq(&conf->resync_lock);
881                 conf->nr_waiting++;
882                 spin_unlock_irq(&conf->resync_lock);
883
884                 if (make_request(mddev, &bp->bio1))
885                         generic_make_request(&bp->bio1);
886                 if (make_request(mddev, &bp->bio2))
887                         generic_make_request(&bp->bio2);
888
889                 spin_lock_irq(&conf->resync_lock);
890                 conf->nr_waiting--;
891                 wake_up(&conf->wait_barrier);
892                 spin_unlock_irq(&conf->resync_lock);
893
894                 bio_pair_release(bp);
895                 return 0;
896         bad_map:
897                 printk("md/raid10:%s: make_request bug: can't convert block across chunks"
898                        " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
899                        (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
900
901                 bio_io_error(bio);
902                 return 0;
903         }
904
905         md_write_start(mddev, bio);
906
907         /*
908          * Register the new request and wait if the reconstruction
909          * thread has put up a bar for new requests.
910          * Continue immediately if no resync is active currently.
911          */
912         wait_barrier(conf);
913
914         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
915
916         r10_bio->master_bio = bio;
917         r10_bio->sectors = bio->bi_size >> 9;
918
919         r10_bio->mddev = mddev;
920         r10_bio->sector = bio->bi_sector;
921         r10_bio->state = 0;
922
923         /* We might need to issue multiple reads to different
924          * devices if there are bad blocks around, so we keep
925          * track of the number of reads in bio->bi_phys_segments.
926          * If this is 0, there is only one r10_bio and no locking
927          * will be needed when the request completes.  If it is
928          * non-zero, then it is the number of not-completed requests.
929          */
930         bio->bi_phys_segments = 0;
931         clear_bit(BIO_SEG_VALID, &bio->bi_flags);
932
933         if (rw == READ) {
934                 /*
935                  * read balancing logic:
936                  */
937                 int disk;
938                 int slot;
939
940 read_again:
941                 disk = read_balance(conf, r10_bio, &max_sectors);
942                 slot = r10_bio->read_slot;
943                 if (disk < 0) {
944                         raid_end_bio_io(r10_bio);
945                         return 0;
946                 }
947                 mirror = conf->mirrors + disk;
948
949                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
950                 md_trim_bio(read_bio, r10_bio->sector - bio->bi_sector,
951                             max_sectors);
952
953                 r10_bio->devs[slot].bio = read_bio;
954
955                 read_bio->bi_sector = r10_bio->devs[slot].addr +
956                         mirror->rdev->data_offset;
957                 read_bio->bi_bdev = mirror->rdev->bdev;
958                 read_bio->bi_end_io = raid10_end_read_request;
959                 read_bio->bi_rw = READ | do_sync;
960                 read_bio->bi_private = r10_bio;
961
962                 if (max_sectors < r10_bio->sectors) {
963                         /* Could not read all from this device, so we will
964                          * need another r10_bio.
965                          */
966                         sectors_handled = (r10_bio->sectors + max_sectors
967                                            - bio->bi_sector);
968                         r10_bio->sectors = max_sectors;
969                         spin_lock_irq(&conf->device_lock);
970                         if (bio->bi_phys_segments == 0)
971                                 bio->bi_phys_segments = 2;
972                         else
973                                 bio->bi_phys_segments++;
974                         spin_unlock(&conf->device_lock);
975                         /* Cannot call generic_make_request directly
976                          * as that will be queued in __generic_make_request
977                          * and subsequent mempool_alloc might block
978                          * waiting for it.  so hand bio over to raid10d.
979                          */
980                         reschedule_retry(r10_bio);
981
982                         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
983
984                         r10_bio->master_bio = bio;
985                         r10_bio->sectors = ((bio->bi_size >> 9)
986                                             - sectors_handled);
987                         r10_bio->state = 0;
988                         r10_bio->mddev = mddev;
989                         r10_bio->sector = bio->bi_sector + sectors_handled;
990                         goto read_again;
991                 } else
992                         generic_make_request(read_bio);
993                 return 0;
994         }
995
996         /*
997          * WRITE:
998          */
999         /* first select target devices under rcu_lock and
1000          * inc refcount on their rdev.  Record them by setting
1001          * bios[x] to bio
1002          * If there are known/acknowledged bad blocks on any device
1003          * on which we have seen a write error, we want to avoid
1004          * writing to those blocks.  This potentially requires several
1005          * writes to write around the bad blocks.  Each set of writes
1006          * gets its own r10_bio with a set of bios attached.  The number
1007          * of r10_bios is recored in bio->bi_phys_segments just as with
1008          * the read case.
1009          */
1010         plugged = mddev_check_plugged(mddev);
1011
1012         raid10_find_phys(conf, r10_bio);
1013 retry_write:
1014         blocked_rdev = NULL;
1015         rcu_read_lock();
1016         max_sectors = r10_bio->sectors;
1017
1018         for (i = 0;  i < conf->copies; i++) {
1019                 int d = r10_bio->devs[i].devnum;
1020                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
1021                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1022                         atomic_inc(&rdev->nr_pending);
1023                         blocked_rdev = rdev;
1024                         break;
1025                 }
1026                 r10_bio->devs[i].bio = NULL;
1027                 if (!rdev || test_bit(Faulty, &rdev->flags)) {
1028                         set_bit(R10BIO_Degraded, &r10_bio->state);
1029                         continue;
1030                 }
1031                 if (test_bit(WriteErrorSeen, &rdev->flags)) {
1032                         sector_t first_bad;
1033                         sector_t dev_sector = r10_bio->devs[i].addr;
1034                         int bad_sectors;
1035                         int is_bad;
1036
1037                         is_bad = is_badblock(rdev, dev_sector,
1038                                              max_sectors,
1039                                              &first_bad, &bad_sectors);
1040                         if (is_bad < 0) {
1041                                 /* Mustn't write here until the bad block
1042                                  * is acknowledged
1043                                  */
1044                                 atomic_inc(&rdev->nr_pending);
1045                                 set_bit(BlockedBadBlocks, &rdev->flags);
1046                                 blocked_rdev = rdev;
1047                                 break;
1048                         }
1049                         if (is_bad && first_bad <= dev_sector) {
1050                                 /* Cannot write here at all */
1051                                 bad_sectors -= (dev_sector - first_bad);
1052                                 if (bad_sectors < max_sectors)
1053                                         /* Mustn't write more than bad_sectors
1054                                          * to other devices yet
1055                                          */
1056                                         max_sectors = bad_sectors;
1057                                 /* We don't set R10BIO_Degraded as that
1058                                  * only applies if the disk is missing,
1059                                  * so it might be re-added, and we want to
1060                                  * know to recover this chunk.
1061                                  * In this case the device is here, and the
1062                                  * fact that this chunk is not in-sync is
1063                                  * recorded in the bad block log.
1064                                  */
1065                                 continue;
1066                         }
1067                         if (is_bad) {
1068                                 int good_sectors = first_bad - dev_sector;
1069                                 if (good_sectors < max_sectors)
1070                                         max_sectors = good_sectors;
1071                         }
1072                 }
1073                 r10_bio->devs[i].bio = bio;
1074                 atomic_inc(&rdev->nr_pending);
1075         }
1076         rcu_read_unlock();
1077
1078         if (unlikely(blocked_rdev)) {
1079                 /* Have to wait for this device to get unblocked, then retry */
1080                 int j;
1081                 int d;
1082
1083                 for (j = 0; j < i; j++)
1084                         if (r10_bio->devs[j].bio) {
1085                                 d = r10_bio->devs[j].devnum;
1086                                 rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1087                         }
1088                 allow_barrier(conf);
1089                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
1090                 wait_barrier(conf);
1091                 goto retry_write;
1092         }
1093
1094         if (max_sectors < r10_bio->sectors) {
1095                 /* We are splitting this into multiple parts, so
1096                  * we need to prepare for allocating another r10_bio.
1097                  */
1098                 r10_bio->sectors = max_sectors;
1099                 spin_lock_irq(&conf->device_lock);
1100                 if (bio->bi_phys_segments == 0)
1101                         bio->bi_phys_segments = 2;
1102                 else
1103                         bio->bi_phys_segments++;
1104                 spin_unlock_irq(&conf->device_lock);
1105         }
1106         sectors_handled = r10_bio->sector + max_sectors - bio->bi_sector;
1107
1108         atomic_set(&r10_bio->remaining, 1);
1109         bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
1110
1111         for (i = 0; i < conf->copies; i++) {
1112                 struct bio *mbio;
1113                 int d = r10_bio->devs[i].devnum;
1114                 if (!r10_bio->devs[i].bio)
1115                         continue;
1116
1117                 mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1118                 md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1119                             max_sectors);
1120                 r10_bio->devs[i].bio = mbio;
1121
1122                 mbio->bi_sector = (r10_bio->devs[i].addr+
1123                                    conf->mirrors[d].rdev->data_offset);
1124                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1125                 mbio->bi_end_io = raid10_end_write_request;
1126                 mbio->bi_rw = WRITE | do_sync | do_fua;
1127                 mbio->bi_private = r10_bio;
1128
1129                 atomic_inc(&r10_bio->remaining);
1130                 spin_lock_irqsave(&conf->device_lock, flags);
1131                 bio_list_add(&conf->pending_bio_list, mbio);
1132                 spin_unlock_irqrestore(&conf->device_lock, flags);
1133         }
1134
1135         /* Don't remove the bias on 'remaining' (one_write_done) until
1136          * after checking if we need to go around again.
1137          */
1138
1139         if (sectors_handled < (bio->bi_size >> 9)) {
1140                 one_write_done(r10_bio);
1141                 /* We need another r10_bio.  It has already been counted
1142                  * in bio->bi_phys_segments.
1143                  */
1144                 r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1145
1146                 r10_bio->master_bio = bio;
1147                 r10_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
1148
1149                 r10_bio->mddev = mddev;
1150                 r10_bio->sector = bio->bi_sector + sectors_handled;
1151                 r10_bio->state = 0;
1152                 goto retry_write;
1153         }
1154         one_write_done(r10_bio);
1155
1156         /* In case raid10d snuck in to freeze_array */
1157         wake_up(&conf->wait_barrier);
1158
1159         if (do_sync || !mddev->bitmap || !plugged)
1160                 md_wakeup_thread(mddev->thread);
1161         return 0;
1162 }
1163
1164 static void status(struct seq_file *seq, mddev_t *mddev)
1165 {
1166         conf_t *conf = mddev->private;
1167         int i;
1168
1169         if (conf->near_copies < conf->raid_disks)
1170                 seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
1171         if (conf->near_copies > 1)
1172                 seq_printf(seq, " %d near-copies", conf->near_copies);
1173         if (conf->far_copies > 1) {
1174                 if (conf->far_offset)
1175                         seq_printf(seq, " %d offset-copies", conf->far_copies);
1176                 else
1177                         seq_printf(seq, " %d far-copies", conf->far_copies);
1178         }
1179         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
1180                                         conf->raid_disks - mddev->degraded);
1181         for (i = 0; i < conf->raid_disks; i++)
1182                 seq_printf(seq, "%s",
1183                               conf->mirrors[i].rdev &&
1184                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
1185         seq_printf(seq, "]");
1186 }
1187
1188 /* check if there are enough drives for
1189  * every block to appear on atleast one.
1190  * Don't consider the device numbered 'ignore'
1191  * as we might be about to remove it.
1192  */
1193 static int enough(conf_t *conf, int ignore)
1194 {
1195         int first = 0;
1196
1197         do {
1198                 int n = conf->copies;
1199                 int cnt = 0;
1200                 while (n--) {
1201                         if (conf->mirrors[first].rdev &&
1202                             first != ignore)
1203                                 cnt++;
1204                         first = (first+1) % conf->raid_disks;
1205                 }
1206                 if (cnt == 0)
1207                         return 0;
1208         } while (first != 0);
1209         return 1;
1210 }
1211
1212 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1213 {
1214         char b[BDEVNAME_SIZE];
1215         conf_t *conf = mddev->private;
1216
1217         /*
1218          * If it is not operational, then we have already marked it as dead
1219          * else if it is the last working disks, ignore the error, let the
1220          * next level up know.
1221          * else mark the drive as failed
1222          */
1223         if (test_bit(In_sync, &rdev->flags)
1224             && !enough(conf, rdev->raid_disk))
1225                 /*
1226                  * Don't fail the drive, just return an IO error.
1227                  */
1228                 return;
1229         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1230                 unsigned long flags;
1231                 spin_lock_irqsave(&conf->device_lock, flags);
1232                 mddev->degraded++;
1233                 spin_unlock_irqrestore(&conf->device_lock, flags);
1234                 /*
1235                  * if recovery is running, make sure it aborts.
1236                  */
1237                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1238         }
1239         set_bit(Blocked, &rdev->flags);
1240         set_bit(Faulty, &rdev->flags);
1241         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1242         printk(KERN_ALERT
1243                "md/raid10:%s: Disk failure on %s, disabling device.\n"
1244                "md/raid10:%s: Operation continuing on %d devices.\n",
1245                mdname(mddev), bdevname(rdev->bdev, b),
1246                mdname(mddev), conf->raid_disks - mddev->degraded);
1247 }
1248
1249 static void print_conf(conf_t *conf)
1250 {
1251         int i;
1252         mirror_info_t *tmp;
1253
1254         printk(KERN_DEBUG "RAID10 conf printout:\n");
1255         if (!conf) {
1256                 printk(KERN_DEBUG "(!conf)\n");
1257                 return;
1258         }
1259         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1260                 conf->raid_disks);
1261
1262         for (i = 0; i < conf->raid_disks; i++) {
1263                 char b[BDEVNAME_SIZE];
1264                 tmp = conf->mirrors + i;
1265                 if (tmp->rdev)
1266                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1267                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1268                                 !test_bit(Faulty, &tmp->rdev->flags),
1269                                 bdevname(tmp->rdev->bdev,b));
1270         }
1271 }
1272
1273 static void close_sync(conf_t *conf)
1274 {
1275         wait_barrier(conf);
1276         allow_barrier(conf);
1277
1278         mempool_destroy(conf->r10buf_pool);
1279         conf->r10buf_pool = NULL;
1280 }
1281
1282 static int raid10_spare_active(mddev_t *mddev)
1283 {
1284         int i;
1285         conf_t *conf = mddev->private;
1286         mirror_info_t *tmp;
1287         int count = 0;
1288         unsigned long flags;
1289
1290         /*
1291          * Find all non-in_sync disks within the RAID10 configuration
1292          * and mark them in_sync
1293          */
1294         for (i = 0; i < conf->raid_disks; i++) {
1295                 tmp = conf->mirrors + i;
1296                 if (tmp->rdev
1297                     && !test_bit(Faulty, &tmp->rdev->flags)
1298                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1299                         count++;
1300                         sysfs_notify_dirent(tmp->rdev->sysfs_state);
1301                 }
1302         }
1303         spin_lock_irqsave(&conf->device_lock, flags);
1304         mddev->degraded -= count;
1305         spin_unlock_irqrestore(&conf->device_lock, flags);
1306
1307         print_conf(conf);
1308         return count;
1309 }
1310
1311
1312 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1313 {
1314         conf_t *conf = mddev->private;
1315         int err = -EEXIST;
1316         int mirror;
1317         int first = 0;
1318         int last = conf->raid_disks - 1;
1319
1320         if (mddev->recovery_cp < MaxSector)
1321                 /* only hot-add to in-sync arrays, as recovery is
1322                  * very different from resync
1323                  */
1324                 return -EBUSY;
1325         if (!enough(conf, -1))
1326                 return -EINVAL;
1327
1328         if (rdev->raid_disk >= 0)
1329                 first = last = rdev->raid_disk;
1330
1331         if (rdev->saved_raid_disk >= first &&
1332             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1333                 mirror = rdev->saved_raid_disk;
1334         else
1335                 mirror = first;
1336         for ( ; mirror <= last ; mirror++) {
1337                 mirror_info_t *p = &conf->mirrors[mirror];
1338                 if (p->recovery_disabled == mddev->recovery_disabled)
1339                         continue;
1340                 if (p->rdev)
1341                         continue;
1342
1343                 disk_stack_limits(mddev->gendisk, rdev->bdev,
1344                                   rdev->data_offset << 9);
1345                 /* as we don't honour merge_bvec_fn, we must
1346                  * never risk violating it, so limit
1347                  * ->max_segments to one lying with a single
1348                  * page, as a one page request is never in
1349                  * violation.
1350                  */
1351                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
1352                         blk_queue_max_segments(mddev->queue, 1);
1353                         blk_queue_segment_boundary(mddev->queue,
1354                                                    PAGE_CACHE_SIZE - 1);
1355                 }
1356
1357                 p->head_position = 0;
1358                 rdev->raid_disk = mirror;
1359                 err = 0;
1360                 if (rdev->saved_raid_disk != mirror)
1361                         conf->fullsync = 1;
1362                 rcu_assign_pointer(p->rdev, rdev);
1363                 break;
1364         }
1365
1366         md_integrity_add_rdev(rdev, mddev);
1367         print_conf(conf);
1368         return err;
1369 }
1370
1371 static int raid10_remove_disk(mddev_t *mddev, int number)
1372 {
1373         conf_t *conf = mddev->private;
1374         int err = 0;
1375         mdk_rdev_t *rdev;
1376         mirror_info_t *p = conf->mirrors+ number;
1377
1378         print_conf(conf);
1379         rdev = p->rdev;
1380         if (rdev) {
1381                 if (test_bit(In_sync, &rdev->flags) ||
1382                     atomic_read(&rdev->nr_pending)) {
1383                         err = -EBUSY;
1384                         goto abort;
1385                 }
1386                 /* Only remove faulty devices in recovery
1387                  * is not possible.
1388                  */
1389                 if (!test_bit(Faulty, &rdev->flags) &&
1390                     mddev->recovery_disabled != p->recovery_disabled &&
1391                     enough(conf, -1)) {
1392                         err = -EBUSY;
1393                         goto abort;
1394                 }
1395                 p->rdev = NULL;
1396                 synchronize_rcu();
1397                 if (atomic_read(&rdev->nr_pending)) {
1398                         /* lost the race, try later */
1399                         err = -EBUSY;
1400                         p->rdev = rdev;
1401                         goto abort;
1402                 }
1403                 err = md_integrity_register(mddev);
1404         }
1405 abort:
1406
1407         print_conf(conf);
1408         return err;
1409 }
1410
1411
1412 static void end_sync_read(struct bio *bio, int error)
1413 {
1414         r10bio_t *r10_bio = bio->bi_private;
1415         conf_t *conf = r10_bio->mddev->private;
1416         int d;
1417
1418         d = find_bio_disk(conf, r10_bio, bio, NULL);
1419
1420         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1421                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1422         else
1423                 /* The write handler will notice the lack of
1424                  * R10BIO_Uptodate and record any errors etc
1425                  */
1426                 atomic_add(r10_bio->sectors,
1427                            &conf->mirrors[d].rdev->corrected_errors);
1428
1429         /* for reconstruct, we always reschedule after a read.
1430          * for resync, only after all reads
1431          */
1432         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1433         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1434             atomic_dec_and_test(&r10_bio->remaining)) {
1435                 /* we have read all the blocks,
1436                  * do the comparison in process context in raid10d
1437                  */
1438                 reschedule_retry(r10_bio);
1439         }
1440 }
1441
1442 static void end_sync_request(r10bio_t *r10_bio)
1443 {
1444         mddev_t *mddev = r10_bio->mddev;
1445
1446         while (atomic_dec_and_test(&r10_bio->remaining)) {
1447                 if (r10_bio->master_bio == NULL) {
1448                         /* the primary of several recovery bios */
1449                         sector_t s = r10_bio->sectors;
1450                         if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1451                             test_bit(R10BIO_WriteError, &r10_bio->state))
1452                                 reschedule_retry(r10_bio);
1453                         else
1454                                 put_buf(r10_bio);
1455                         md_done_sync(mddev, s, 1);
1456                         break;
1457                 } else {
1458                         r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
1459                         if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1460                             test_bit(R10BIO_WriteError, &r10_bio->state))
1461                                 reschedule_retry(r10_bio);
1462                         else
1463                                 put_buf(r10_bio);
1464                         r10_bio = r10_bio2;
1465                 }
1466         }
1467 }
1468
1469 static void end_sync_write(struct bio *bio, int error)
1470 {
1471         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1472         r10bio_t *r10_bio = bio->bi_private;
1473         mddev_t *mddev = r10_bio->mddev;
1474         conf_t *conf = mddev->private;
1475         int d;
1476         sector_t first_bad;
1477         int bad_sectors;
1478         int slot;
1479
1480         d = find_bio_disk(conf, r10_bio, bio, &slot);
1481
1482         if (!uptodate) {
1483                 set_bit(WriteErrorSeen, &conf->mirrors[d].rdev->flags);
1484                 set_bit(R10BIO_WriteError, &r10_bio->state);
1485         } else if (is_badblock(conf->mirrors[d].rdev,
1486                              r10_bio->devs[slot].addr,
1487                              r10_bio->sectors,
1488                              &first_bad, &bad_sectors))
1489                 set_bit(R10BIO_MadeGood, &r10_bio->state);
1490
1491         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1492
1493         end_sync_request(r10_bio);
1494 }
1495
1496 /*
1497  * Note: sync and recover and handled very differently for raid10
1498  * This code is for resync.
1499  * For resync, we read through virtual addresses and read all blocks.
1500  * If there is any error, we schedule a write.  The lowest numbered
1501  * drive is authoritative.
1502  * However requests come for physical address, so we need to map.
1503  * For every physical address there are raid_disks/copies virtual addresses,
1504  * which is always are least one, but is not necessarly an integer.
1505  * This means that a physical address can span multiple chunks, so we may
1506  * have to submit multiple io requests for a single sync request.
1507  */
1508 /*
1509  * We check if all blocks are in-sync and only write to blocks that
1510  * aren't in sync
1511  */
1512 static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1513 {
1514         conf_t *conf = mddev->private;
1515         int i, first;
1516         struct bio *tbio, *fbio;
1517
1518         atomic_set(&r10_bio->remaining, 1);
1519
1520         /* find the first device with a block */
1521         for (i=0; i<conf->copies; i++)
1522                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1523                         break;
1524
1525         if (i == conf->copies)
1526                 goto done;
1527
1528         first = i;
1529         fbio = r10_bio->devs[i].bio;
1530
1531         /* now find blocks with errors */
1532         for (i=0 ; i < conf->copies ; i++) {
1533                 int  j, d;
1534                 int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
1535
1536                 tbio = r10_bio->devs[i].bio;
1537
1538                 if (tbio->bi_end_io != end_sync_read)
1539                         continue;
1540                 if (i == first)
1541                         continue;
1542                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1543                         /* We know that the bi_io_vec layout is the same for
1544                          * both 'first' and 'i', so we just compare them.
1545                          * All vec entries are PAGE_SIZE;
1546                          */
1547                         for (j = 0; j < vcnt; j++)
1548                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1549                                            page_address(tbio->bi_io_vec[j].bv_page),
1550                                            PAGE_SIZE))
1551                                         break;
1552                         if (j == vcnt)
1553                                 continue;
1554                         mddev->resync_mismatches += r10_bio->sectors;
1555                         if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1556                                 /* Don't fix anything. */
1557                                 continue;
1558                 }
1559                 /* Ok, we need to write this bio, either to correct an
1560                  * inconsistency or to correct an unreadable block.
1561                  * First we need to fixup bv_offset, bv_len and
1562                  * bi_vecs, as the read request might have corrupted these
1563                  */
1564                 tbio->bi_vcnt = vcnt;
1565                 tbio->bi_size = r10_bio->sectors << 9;
1566                 tbio->bi_idx = 0;
1567                 tbio->bi_phys_segments = 0;
1568                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1569                 tbio->bi_flags |= 1 << BIO_UPTODATE;
1570                 tbio->bi_next = NULL;
1571                 tbio->bi_rw = WRITE;
1572                 tbio->bi_private = r10_bio;
1573                 tbio->bi_sector = r10_bio->devs[i].addr;
1574
1575                 for (j=0; j < vcnt ; j++) {
1576                         tbio->bi_io_vec[j].bv_offset = 0;
1577                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1578
1579                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1580                                page_address(fbio->bi_io_vec[j].bv_page),
1581                                PAGE_SIZE);
1582                 }
1583                 tbio->bi_end_io = end_sync_write;
1584
1585                 d = r10_bio->devs[i].devnum;
1586                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1587                 atomic_inc(&r10_bio->remaining);
1588                 md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1589
1590                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1591                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1592                 generic_make_request(tbio);
1593         }
1594
1595 done:
1596         if (atomic_dec_and_test(&r10_bio->remaining)) {
1597                 md_done_sync(mddev, r10_bio->sectors, 1);
1598                 put_buf(r10_bio);
1599         }
1600 }
1601
1602 /*
1603  * Now for the recovery code.
1604  * Recovery happens across physical sectors.
1605  * We recover all non-is_sync drives by finding the virtual address of
1606  * each, and then choose a working drive that also has that virt address.
1607  * There is a separate r10_bio for each non-in_sync drive.
1608  * Only the first two slots are in use. The first for reading,
1609  * The second for writing.
1610  *
1611  */
1612 static void fix_recovery_read_error(r10bio_t *r10_bio)
1613 {
1614         /* We got a read error during recovery.
1615          * We repeat the read in smaller page-sized sections.
1616          * If a read succeeds, write it to the new device or record
1617          * a bad block if we cannot.
1618          * If a read fails, record a bad block on both old and
1619          * new devices.
1620          */
1621         mddev_t *mddev = r10_bio->mddev;
1622         conf_t *conf = mddev->private;
1623         struct bio *bio = r10_bio->devs[0].bio;
1624         sector_t sect = 0;
1625         int sectors = r10_bio->sectors;
1626         int idx = 0;
1627         int dr = r10_bio->devs[0].devnum;
1628         int dw = r10_bio->devs[1].devnum;
1629
1630         while (sectors) {
1631                 int s = sectors;
1632                 mdk_rdev_t *rdev;
1633                 sector_t addr;
1634                 int ok;
1635
1636                 if (s > (PAGE_SIZE>>9))
1637                         s = PAGE_SIZE >> 9;
1638
1639                 rdev = conf->mirrors[dr].rdev;
1640                 addr = r10_bio->devs[0].addr + sect,
1641                 ok = sync_page_io(rdev,
1642                                   addr,
1643                                   s << 9,
1644                                   bio->bi_io_vec[idx].bv_page,
1645                                   READ, false);
1646                 if (ok) {
1647                         rdev = conf->mirrors[dw].rdev;
1648                         addr = r10_bio->devs[1].addr + sect;
1649                         ok = sync_page_io(rdev,
1650                                           addr,
1651                                           s << 9,
1652                                           bio->bi_io_vec[idx].bv_page,
1653                                           WRITE, false);
1654                         if (!ok)
1655                                 set_bit(WriteErrorSeen, &rdev->flags);
1656                 }
1657                 if (!ok) {
1658                         /* We don't worry if we cannot set a bad block -
1659                          * it really is bad so there is no loss in not
1660                          * recording it yet
1661                          */
1662                         rdev_set_badblocks(rdev, addr, s, 0);
1663
1664                         if (rdev != conf->mirrors[dw].rdev) {
1665                                 /* need bad block on destination too */
1666                                 mdk_rdev_t *rdev2 = conf->mirrors[dw].rdev;
1667                                 addr = r10_bio->devs[1].addr + sect;
1668                                 ok = rdev_set_badblocks(rdev2, addr, s, 0);
1669                                 if (!ok) {
1670                                         /* just abort the recovery */
1671                                         printk(KERN_NOTICE
1672                                                "md/raid10:%s: recovery aborted"
1673                                                " due to read error\n",
1674                                                mdname(mddev));
1675
1676                                         conf->mirrors[dw].recovery_disabled
1677                                                 = mddev->recovery_disabled;
1678                                         set_bit(MD_RECOVERY_INTR,
1679                                                 &mddev->recovery);
1680                                         break;
1681                                 }
1682                         }
1683                 }
1684
1685                 sectors -= s;
1686                 sect += s;
1687                 idx++;
1688         }
1689 }
1690
1691 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1692 {
1693         conf_t *conf = mddev->private;
1694         int d;
1695         struct bio *wbio;
1696
1697         if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
1698                 fix_recovery_read_error(r10_bio);
1699                 end_sync_request(r10_bio);
1700                 return;
1701         }
1702
1703         /*
1704          * share the pages with the first bio
1705          * and submit the write request
1706          */
1707         wbio = r10_bio->devs[1].bio;
1708         d = r10_bio->devs[1].devnum;
1709
1710         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1711         md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
1712         generic_make_request(wbio);
1713 }
1714
1715
1716 /*
1717  * Used by fix_read_error() to decay the per rdev read_errors.
1718  * We halve the read error count for every hour that has elapsed
1719  * since the last recorded read error.
1720  *
1721  */
1722 static void check_decay_read_errors(mddev_t *mddev, mdk_rdev_t *rdev)
1723 {
1724         struct timespec cur_time_mon;
1725         unsigned long hours_since_last;
1726         unsigned int read_errors = atomic_read(&rdev->read_errors);
1727
1728         ktime_get_ts(&cur_time_mon);
1729
1730         if (rdev->last_read_error.tv_sec == 0 &&
1731             rdev->last_read_error.tv_nsec == 0) {
1732                 /* first time we've seen a read error */
1733                 rdev->last_read_error = cur_time_mon;
1734                 return;
1735         }
1736
1737         hours_since_last = (cur_time_mon.tv_sec -
1738                             rdev->last_read_error.tv_sec) / 3600;
1739
1740         rdev->last_read_error = cur_time_mon;
1741
1742         /*
1743          * if hours_since_last is > the number of bits in read_errors
1744          * just set read errors to 0. We do this to avoid
1745          * overflowing the shift of read_errors by hours_since_last.
1746          */
1747         if (hours_since_last >= 8 * sizeof(read_errors))
1748                 atomic_set(&rdev->read_errors, 0);
1749         else
1750                 atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
1751 }
1752
1753 static int r10_sync_page_io(mdk_rdev_t *rdev, sector_t sector,
1754                             int sectors, struct page *page, int rw)
1755 {
1756         sector_t first_bad;
1757         int bad_sectors;
1758
1759         if (is_badblock(rdev, sector, sectors, &first_bad, &bad_sectors)
1760             && (rw == READ || test_bit(WriteErrorSeen, &rdev->flags)))
1761                 return -1;
1762         if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
1763                 /* success */
1764                 return 1;
1765         if (rw == WRITE)
1766                 set_bit(WriteErrorSeen, &rdev->flags);
1767         /* need to record an error - either for the block or the device */
1768         if (!rdev_set_badblocks(rdev, sector, sectors, 0))
1769                 md_error(rdev->mddev, rdev);
1770         return 0;
1771 }
1772
1773 /*
1774  * This is a kernel thread which:
1775  *
1776  *      1.      Retries failed read operations on working mirrors.
1777  *      2.      Updates the raid superblock when problems encounter.
1778  *      3.      Performs writes following reads for array synchronising.
1779  */
1780
1781 static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
1782 {
1783         int sect = 0; /* Offset from r10_bio->sector */
1784         int sectors = r10_bio->sectors;
1785         mdk_rdev_t*rdev;
1786         int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
1787         int d = r10_bio->devs[r10_bio->read_slot].devnum;
1788
1789         /* still own a reference to this rdev, so it cannot
1790          * have been cleared recently.
1791          */
1792         rdev = conf->mirrors[d].rdev;
1793
1794         if (test_bit(Faulty, &rdev->flags))
1795                 /* drive has already been failed, just ignore any
1796                    more fix_read_error() attempts */
1797                 return;
1798
1799         check_decay_read_errors(mddev, rdev);
1800         atomic_inc(&rdev->read_errors);
1801         if (atomic_read(&rdev->read_errors) > max_read_errors) {
1802                 char b[BDEVNAME_SIZE];
1803                 bdevname(rdev->bdev, b);
1804
1805                 printk(KERN_NOTICE
1806                        "md/raid10:%s: %s: Raid device exceeded "
1807                        "read_error threshold [cur %d:max %d]\n",
1808                        mdname(mddev), b,
1809                        atomic_read(&rdev->read_errors), max_read_errors);
1810                 printk(KERN_NOTICE
1811                        "md/raid10:%s: %s: Failing raid device\n",
1812                        mdname(mddev), b);
1813                 md_error(mddev, conf->mirrors[d].rdev);
1814                 return;
1815         }
1816
1817         while(sectors) {
1818                 int s = sectors;
1819                 int sl = r10_bio->read_slot;
1820                 int success = 0;
1821                 int start;
1822
1823                 if (s > (PAGE_SIZE>>9))
1824                         s = PAGE_SIZE >> 9;
1825
1826                 rcu_read_lock();
1827                 do {
1828                         sector_t first_bad;
1829                         int bad_sectors;
1830
1831                         d = r10_bio->devs[sl].devnum;
1832                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1833                         if (rdev &&
1834                             test_bit(In_sync, &rdev->flags) &&
1835                             is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
1836                                         &first_bad, &bad_sectors) == 0) {
1837                                 atomic_inc(&rdev->nr_pending);
1838                                 rcu_read_unlock();
1839                                 success = sync_page_io(rdev,
1840                                                        r10_bio->devs[sl].addr +
1841                                                        sect,
1842                                                        s<<9,
1843                                                        conf->tmppage, READ, false);
1844                                 rdev_dec_pending(rdev, mddev);
1845                                 rcu_read_lock();
1846                                 if (success)
1847                                         break;
1848                         }
1849                         sl++;
1850                         if (sl == conf->copies)
1851                                 sl = 0;
1852                 } while (!success && sl != r10_bio->read_slot);
1853                 rcu_read_unlock();
1854
1855                 if (!success) {
1856                         /* Cannot read from anywhere, just mark the block
1857                          * as bad on the first device to discourage future
1858                          * reads.
1859                          */
1860                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
1861                         rdev = conf->mirrors[dn].rdev;
1862
1863                         if (!rdev_set_badblocks(
1864                                     rdev,
1865                                     r10_bio->devs[r10_bio->read_slot].addr
1866                                     + sect,
1867                                     s, 0))
1868                                 md_error(mddev, rdev);
1869                         break;
1870                 }
1871
1872                 start = sl;
1873                 /* write it back and re-read */
1874                 rcu_read_lock();
1875                 while (sl != r10_bio->read_slot) {
1876                         char b[BDEVNAME_SIZE];
1877
1878                         if (sl==0)
1879                                 sl = conf->copies;
1880                         sl--;
1881                         d = r10_bio->devs[sl].devnum;
1882                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1883                         if (!rdev ||
1884                             !test_bit(In_sync, &rdev->flags))
1885                                 continue;
1886
1887                         atomic_inc(&rdev->nr_pending);
1888                         rcu_read_unlock();
1889                         if (r10_sync_page_io(rdev,
1890                                              r10_bio->devs[sl].addr +
1891                                              sect,
1892                                              s<<9, conf->tmppage, WRITE)
1893                             == 0) {
1894                                 /* Well, this device is dead */
1895                                 printk(KERN_NOTICE
1896                                        "md/raid10:%s: read correction "
1897                                        "write failed"
1898                                        " (%d sectors at %llu on %s)\n",
1899                                        mdname(mddev), s,
1900                                        (unsigned long long)(
1901                                                sect + rdev->data_offset),
1902                                        bdevname(rdev->bdev, b));
1903                                 printk(KERN_NOTICE "md/raid10:%s: %s: failing "
1904                                        "drive\n",
1905                                        mdname(mddev),
1906                                        bdevname(rdev->bdev, b));
1907                         }
1908                         rdev_dec_pending(rdev, mddev);
1909                         rcu_read_lock();
1910                 }
1911                 sl = start;
1912                 while (sl != r10_bio->read_slot) {
1913                         char b[BDEVNAME_SIZE];
1914
1915                         if (sl==0)
1916                                 sl = conf->copies;
1917                         sl--;
1918                         d = r10_bio->devs[sl].devnum;
1919                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1920                         if (!rdev ||
1921                             !test_bit(In_sync, &rdev->flags))
1922                                 continue;
1923
1924                         atomic_inc(&rdev->nr_pending);
1925                         rcu_read_unlock();
1926                         switch (r10_sync_page_io(rdev,
1927                                              r10_bio->devs[sl].addr +
1928                                              sect,
1929                                              s<<9, conf->tmppage,
1930                                                  READ)) {
1931                         case 0:
1932                                 /* Well, this device is dead */
1933                                 printk(KERN_NOTICE
1934                                        "md/raid10:%s: unable to read back "
1935                                        "corrected sectors"
1936                                        " (%d sectors at %llu on %s)\n",
1937                                        mdname(mddev), s,
1938                                        (unsigned long long)(
1939                                                sect + rdev->data_offset),
1940                                        bdevname(rdev->bdev, b));
1941                                 printk(KERN_NOTICE "md/raid10:%s: %s: failing "
1942                                        "drive\n",
1943                                        mdname(mddev),
1944                                        bdevname(rdev->bdev, b));
1945                                 break;
1946                         case 1:
1947                                 printk(KERN_INFO
1948                                        "md/raid10:%s: read error corrected"
1949                                        " (%d sectors at %llu on %s)\n",
1950                                        mdname(mddev), s,
1951                                        (unsigned long long)(
1952                                                sect + rdev->data_offset),
1953                                        bdevname(rdev->bdev, b));
1954                                 atomic_add(s, &rdev->corrected_errors);
1955                         }
1956
1957                         rdev_dec_pending(rdev, mddev);
1958                         rcu_read_lock();
1959                 }
1960                 rcu_read_unlock();
1961
1962                 sectors -= s;
1963                 sect += s;
1964         }
1965 }
1966
1967 static void bi_complete(struct bio *bio, int error)
1968 {
1969         complete((struct completion *)bio->bi_private);
1970 }
1971
1972 static int submit_bio_wait(int rw, struct bio *bio)
1973 {
1974         struct completion event;
1975         rw |= REQ_SYNC;
1976
1977         init_completion(&event);
1978         bio->bi_private = &event;
1979         bio->bi_end_io = bi_complete;
1980         submit_bio(rw, bio);
1981         wait_for_completion(&event);
1982
1983         return test_bit(BIO_UPTODATE, &bio->bi_flags);
1984 }
1985
1986 static int narrow_write_error(r10bio_t *r10_bio, int i)
1987 {
1988         struct bio *bio = r10_bio->master_bio;
1989         mddev_t *mddev = r10_bio->mddev;
1990         conf_t *conf = mddev->private;
1991         mdk_rdev_t *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
1992         /* bio has the data to be written to slot 'i' where
1993          * we just recently had a write error.
1994          * We repeatedly clone the bio and trim down to one block,
1995          * then try the write.  Where the write fails we record
1996          * a bad block.
1997          * It is conceivable that the bio doesn't exactly align with
1998          * blocks.  We must handle this.
1999          *
2000          * We currently own a reference to the rdev.
2001          */
2002
2003         int block_sectors;
2004         sector_t sector;
2005         int sectors;
2006         int sect_to_write = r10_bio->sectors;
2007         int ok = 1;
2008
2009         if (rdev->badblocks.shift < 0)
2010                 return 0;
2011
2012         block_sectors = 1 << rdev->badblocks.shift;
2013         sector = r10_bio->sector;
2014         sectors = ((r10_bio->sector + block_sectors)
2015                    & ~(sector_t)(block_sectors - 1))
2016                 - sector;
2017
2018         while (sect_to_write) {
2019                 struct bio *wbio;
2020                 if (sectors > sect_to_write)
2021                         sectors = sect_to_write;
2022                 /* Write at 'sector' for 'sectors' */
2023                 wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
2024                 md_trim_bio(wbio, sector - bio->bi_sector, sectors);
2025                 wbio->bi_sector = (r10_bio->devs[i].addr+
2026                                    rdev->data_offset+
2027                                    (sector - r10_bio->sector));
2028                 wbio->bi_bdev = rdev->bdev;
2029                 if (submit_bio_wait(WRITE, wbio) == 0)
2030                         /* Failure! */
2031                         ok = rdev_set_badblocks(rdev, sector,
2032                                                 sectors, 0)
2033                                 && ok;
2034
2035                 bio_put(wbio);
2036                 sect_to_write -= sectors;
2037                 sector += sectors;
2038                 sectors = block_sectors;
2039         }
2040         return ok;
2041 }
2042
2043 static void handle_read_error(mddev_t *mddev, r10bio_t *r10_bio)
2044 {
2045         int slot = r10_bio->read_slot;
2046         int mirror = r10_bio->devs[slot].devnum;
2047         struct bio *bio;
2048         conf_t *conf = mddev->private;
2049         mdk_rdev_t *rdev;
2050         char b[BDEVNAME_SIZE];
2051         unsigned long do_sync;
2052         int max_sectors;
2053
2054         /* we got a read error. Maybe the drive is bad.  Maybe just
2055          * the block and we can fix it.
2056          * We freeze all other IO, and try reading the block from
2057          * other devices.  When we find one, we re-write
2058          * and check it that fixes the read error.
2059          * This is all done synchronously while the array is
2060          * frozen.
2061          */
2062         if (mddev->ro == 0) {
2063                 freeze_array(conf);
2064                 fix_read_error(conf, mddev, r10_bio);
2065                 unfreeze_array(conf);
2066         }
2067         rdev_dec_pending(conf->mirrors[mirror].rdev, mddev);
2068
2069         bio = r10_bio->devs[slot].bio;
2070         bdevname(bio->bi_bdev, b);
2071         r10_bio->devs[slot].bio =
2072                 mddev->ro ? IO_BLOCKED : NULL;
2073 read_more:
2074         mirror = read_balance(conf, r10_bio, &max_sectors);
2075         if (mirror == -1) {
2076                 printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
2077                        " read error for block %llu\n",
2078                        mdname(mddev), b,
2079                        (unsigned long long)r10_bio->sector);
2080                 raid_end_bio_io(r10_bio);
2081                 bio_put(bio);
2082                 return;
2083         }
2084
2085         do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
2086         if (bio)
2087                 bio_put(bio);
2088         slot = r10_bio->read_slot;
2089         rdev = conf->mirrors[mirror].rdev;
2090         printk_ratelimited(
2091                 KERN_ERR
2092                 "md/raid10:%s: %s: redirecting"
2093                 "sector %llu to another mirror\n",
2094                 mdname(mddev),
2095                 bdevname(rdev->bdev, b),
2096                 (unsigned long long)r10_bio->sector);
2097         bio = bio_clone_mddev(r10_bio->master_bio,
2098                               GFP_NOIO, mddev);
2099         md_trim_bio(bio,
2100                     r10_bio->sector - bio->bi_sector,
2101                     max_sectors);
2102         r10_bio->devs[slot].bio = bio;
2103         bio->bi_sector = r10_bio->devs[slot].addr
2104                 + rdev->data_offset;
2105         bio->bi_bdev = rdev->bdev;
2106         bio->bi_rw = READ | do_sync;
2107         bio->bi_private = r10_bio;
2108         bio->bi_end_io = raid10_end_read_request;
2109         if (max_sectors < r10_bio->sectors) {
2110                 /* Drat - have to split this up more */
2111                 struct bio *mbio = r10_bio->master_bio;
2112                 int sectors_handled =
2113                         r10_bio->sector + max_sectors
2114                         - mbio->bi_sector;
2115                 r10_bio->sectors = max_sectors;
2116                 spin_lock_irq(&conf->device_lock);
2117                 if (mbio->bi_phys_segments == 0)
2118                         mbio->bi_phys_segments = 2;
2119                 else
2120                         mbio->bi_phys_segments++;
2121                 spin_unlock_irq(&conf->device_lock);
2122                 generic_make_request(bio);
2123                 bio = NULL;
2124
2125                 r10_bio = mempool_alloc(conf->r10bio_pool,
2126                                         GFP_NOIO);
2127                 r10_bio->master_bio = mbio;
2128                 r10_bio->sectors = (mbio->bi_size >> 9)
2129                         - sectors_handled;
2130                 r10_bio->state = 0;
2131                 set_bit(R10BIO_ReadError,
2132                         &r10_bio->state);
2133                 r10_bio->mddev = mddev;
2134                 r10_bio->sector = mbio->bi_sector
2135                         + sectors_handled;
2136
2137                 goto read_more;
2138         } else
2139                 generic_make_request(bio);
2140 }
2141
2142 static void handle_write_completed(conf_t *conf, r10bio_t *r10_bio)
2143 {
2144         /* Some sort of write request has finished and it
2145          * succeeded in writing where we thought there was a
2146          * bad block.  So forget the bad block.
2147          * Or possibly if failed and we need to record
2148          * a bad block.
2149          */
2150         int m;
2151         mdk_rdev_t *rdev;
2152
2153         if (test_bit(R10BIO_IsSync, &r10_bio->state) ||
2154             test_bit(R10BIO_IsRecover, &r10_bio->state)) {
2155                 for (m = 0; m < conf->copies; m++) {
2156                         int dev = r10_bio->devs[m].devnum;
2157                         rdev = conf->mirrors[dev].rdev;
2158                         if (r10_bio->devs[m].bio == NULL)
2159                                 continue;
2160                         if (test_bit(BIO_UPTODATE,
2161                                      &r10_bio->devs[m].bio->bi_flags)) {
2162                                 rdev_clear_badblocks(
2163                                         rdev,
2164                                         r10_bio->devs[m].addr,
2165                                         r10_bio->sectors);
2166                         } else {
2167                                 if (!rdev_set_badblocks(
2168                                             rdev,
2169                                             r10_bio->devs[m].addr,
2170                                             r10_bio->sectors, 0))
2171                                         md_error(conf->mddev, rdev);
2172                         }
2173                 }
2174                 put_buf(r10_bio);
2175         } else {
2176                 for (m = 0; m < conf->copies; m++) {
2177                         int dev = r10_bio->devs[m].devnum;
2178                         struct bio *bio = r10_bio->devs[m].bio;
2179                         rdev = conf->mirrors[dev].rdev;
2180                         if (bio == IO_MADE_GOOD) {
2181                                 rdev_clear_badblocks(
2182                                         rdev,
2183                                         r10_bio->devs[m].addr,
2184                                         r10_bio->sectors);
2185                                 rdev_dec_pending(rdev, conf->mddev);
2186                         } else if (bio != NULL &&
2187                                    !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
2188                                 if (!narrow_write_error(r10_bio, m)) {
2189                                         md_error(conf->mddev, rdev);
2190                                         set_bit(R10BIO_Degraded,
2191                                                 &r10_bio->state);
2192                                 }
2193                                 rdev_dec_pending(rdev, conf->mddev);
2194                         }
2195                 }
2196                 if (test_bit(R10BIO_WriteError,
2197                              &r10_bio->state))
2198                         close_write(r10_bio);
2199                 raid_end_bio_io(r10_bio);
2200         }
2201 }
2202
2203 static void raid10d(mddev_t *mddev)
2204 {
2205         r10bio_t *r10_bio;
2206         unsigned long flags;
2207         conf_t *conf = mddev->private;
2208         struct list_head *head = &conf->retry_list;
2209         struct blk_plug plug;
2210
2211         md_check_recovery(mddev);
2212
2213         blk_start_plug(&plug);
2214         for (;;) {
2215
2216                 flush_pending_writes(conf);
2217
2218                 spin_lock_irqsave(&conf->device_lock, flags);
2219                 if (list_empty(head)) {
2220                         spin_unlock_irqrestore(&conf->device_lock, flags);
2221                         break;
2222                 }
2223                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
2224                 list_del(head->prev);
2225                 conf->nr_queued--;
2226                 spin_unlock_irqrestore(&conf->device_lock, flags);
2227
2228                 mddev = r10_bio->mddev;
2229                 conf = mddev->private;
2230                 if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
2231                     test_bit(R10BIO_WriteError, &r10_bio->state))
2232                         handle_write_completed(conf, r10_bio);
2233                 else if (test_bit(R10BIO_IsSync, &r10_bio->state))
2234                         sync_request_write(mddev, r10_bio);
2235                 else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
2236                         recovery_request_write(mddev, r10_bio);
2237                 else if (test_bit(R10BIO_ReadError, &r10_bio->state))
2238                         handle_read_error(mddev, r10_bio);
2239                 else {
2240                         /* just a partial read to be scheduled from a
2241                          * separate context
2242                          */
2243                         int slot = r10_bio->read_slot;
2244                         generic_make_request(r10_bio->devs[slot].bio);
2245                 }
2246
2247                 cond_resched();
2248                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2249                         md_check_recovery(mddev);
2250         }
2251         blk_finish_plug(&plug);
2252 }
2253
2254
2255 static int init_resync(conf_t *conf)
2256 {
2257         int buffs;
2258
2259         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2260         BUG_ON(conf->r10buf_pool);
2261         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
2262         if (!conf->r10buf_pool)
2263                 return -ENOMEM;
2264         conf->next_resync = 0;
2265         return 0;
2266 }
2267
2268 /*
2269  * perform a "sync" on one "block"
2270  *
2271  * We need to make sure that no normal I/O request - particularly write
2272  * requests - conflict with active sync requests.
2273  *
2274  * This is achieved by tracking pending requests and a 'barrier' concept
2275  * that can be installed to exclude normal IO requests.
2276  *
2277  * Resync and recovery are handled very differently.
2278  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
2279  *
2280  * For resync, we iterate over virtual addresses, read all copies,
2281  * and update if there are differences.  If only one copy is live,
2282  * skip it.
2283  * For recovery, we iterate over physical addresses, read a good
2284  * value for each non-in_sync drive, and over-write.
2285  *
2286  * So, for recovery we may have several outstanding complex requests for a
2287  * given address, one for each out-of-sync device.  We model this by allocating
2288  * a number of r10_bio structures, one for each out-of-sync device.
2289  * As we setup these structures, we collect all bio's together into a list
2290  * which we then process collectively to add pages, and then process again
2291  * to pass to generic_make_request.
2292  *
2293  * The r10_bio structures are linked using a borrowed master_bio pointer.
2294  * This link is counted in ->remaining.  When the r10_bio that points to NULL
2295  * has its remaining count decremented to 0, the whole complex operation
2296  * is complete.
2297  *
2298  */
2299
2300 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
2301                              int *skipped, int go_faster)
2302 {
2303         conf_t *conf = mddev->private;
2304         r10bio_t *r10_bio;
2305         struct bio *biolist = NULL, *bio;
2306         sector_t max_sector, nr_sectors;
2307         int i;
2308         int max_sync;
2309         sector_t sync_blocks;
2310         sector_t sectors_skipped = 0;
2311         int chunks_skipped = 0;
2312
2313         if (!conf->r10buf_pool)
2314                 if (init_resync(conf))
2315                         return 0;
2316
2317  skipped:
2318         max_sector = mddev->dev_sectors;
2319         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
2320                 max_sector = mddev->resync_max_sectors;
2321         if (sector_nr >= max_sector) {
2322                 /* If we aborted, we need to abort the
2323                  * sync on the 'current' bitmap chucks (there can
2324                  * be several when recovering multiple devices).
2325                  * as we may have started syncing it but not finished.
2326                  * We can find the current address in
2327                  * mddev->curr_resync, but for recovery,
2328                  * we need to convert that to several
2329                  * virtual addresses.
2330                  */
2331                 if (mddev->curr_resync < max_sector) { /* aborted */
2332                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
2333                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2334                                                 &sync_blocks, 1);
2335                         else for (i=0; i<conf->raid_disks; i++) {
2336                                 sector_t sect =
2337                                         raid10_find_virt(conf, mddev->curr_resync, i);
2338                                 bitmap_end_sync(mddev->bitmap, sect,
2339                                                 &sync_blocks, 1);
2340                         }
2341                 } else /* completed sync */
2342                         conf->fullsync = 0;
2343
2344                 bitmap_close_sync(mddev->bitmap);
2345                 close_sync(conf);
2346                 *skipped = 1;
2347                 return sectors_skipped;
2348         }
2349         if (chunks_skipped >= conf->raid_disks) {
2350                 /* if there has been nothing to do on any drive,
2351                  * then there is nothing to do at all..
2352                  */
2353                 *skipped = 1;
2354                 return (max_sector - sector_nr) + sectors_skipped;
2355         }
2356
2357         if (max_sector > mddev->resync_max)
2358                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
2359
2360         /* make sure whole request will fit in a chunk - if chunks
2361          * are meaningful
2362          */
2363         if (conf->near_copies < conf->raid_disks &&
2364             max_sector > (sector_nr | conf->chunk_mask))
2365                 max_sector = (sector_nr | conf->chunk_mask) + 1;
2366         /*
2367          * If there is non-resync activity waiting for us then
2368          * put in a delay to throttle resync.
2369          */
2370         if (!go_faster && conf->nr_waiting)
2371                 msleep_interruptible(1000);
2372
2373         /* Again, very different code for resync and recovery.
2374          * Both must result in an r10bio with a list of bios that
2375          * have bi_end_io, bi_sector, bi_bdev set,
2376          * and bi_private set to the r10bio.
2377          * For recovery, we may actually create several r10bios
2378          * with 2 bios in each, that correspond to the bios in the main one.
2379          * In this case, the subordinate r10bios link back through a
2380          * borrowed master_bio pointer, and the counter in the master
2381          * includes a ref from each subordinate.
2382          */
2383         /* First, we decide what to do and set ->bi_end_io
2384          * To end_sync_read if we want to read, and
2385          * end_sync_write if we will want to write.
2386          */
2387
2388         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
2389         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2390                 /* recovery... the complicated one */
2391                 int j;
2392                 r10_bio = NULL;
2393
2394                 for (i=0 ; i<conf->raid_disks; i++) {
2395                         int still_degraded;
2396                         r10bio_t *rb2;
2397                         sector_t sect;
2398                         int must_sync;
2399                         int any_working;
2400
2401                         if (conf->mirrors[i].rdev == NULL ||
2402                             test_bit(In_sync, &conf->mirrors[i].rdev->flags)) 
2403                                 continue;
2404
2405                         still_degraded = 0;
2406                         /* want to reconstruct this device */
2407                         rb2 = r10_bio;
2408                         sect = raid10_find_virt(conf, sector_nr, i);
2409                         /* Unless we are doing a full sync, we only need
2410                          * to recover the block if it is set in the bitmap
2411                          */
2412                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
2413                                                       &sync_blocks, 1);
2414                         if (sync_blocks < max_sync)
2415                                 max_sync = sync_blocks;
2416                         if (!must_sync &&
2417                             !conf->fullsync) {
2418                                 /* yep, skip the sync_blocks here, but don't assume
2419                                  * that there will never be anything to do here
2420                                  */
2421                                 chunks_skipped = -1;
2422                                 continue;
2423                         }
2424
2425                         r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
2426                         raise_barrier(conf, rb2 != NULL);
2427                         atomic_set(&r10_bio->remaining, 0);
2428
2429                         r10_bio->master_bio = (struct bio*)rb2;
2430                         if (rb2)
2431                                 atomic_inc(&rb2->remaining);
2432                         r10_bio->mddev = mddev;
2433                         set_bit(R10BIO_IsRecover, &r10_bio->state);
2434                         r10_bio->sector = sect;
2435
2436                         raid10_find_phys(conf, r10_bio);
2437
2438                         /* Need to check if the array will still be
2439                          * degraded
2440                          */
2441                         for (j=0; j<conf->raid_disks; j++)
2442                                 if (conf->mirrors[j].rdev == NULL ||
2443                                     test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
2444                                         still_degraded = 1;
2445                                         break;
2446                                 }
2447
2448                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
2449                                                       &sync_blocks, still_degraded);
2450
2451                         any_working = 0;
2452                         for (j=0; j<conf->copies;j++) {
2453                                 int k;
2454                                 int d = r10_bio->devs[j].devnum;
2455                                 sector_t from_addr, to_addr;
2456                                 mdk_rdev_t *rdev;
2457                                 sector_t sector, first_bad;
2458                                 int bad_sectors;
2459                                 if (!conf->mirrors[d].rdev ||
2460                                     !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
2461                                         continue;
2462                                 /* This is where we read from */
2463                                 any_working = 1;
2464                                 rdev = conf->mirrors[d].rdev;
2465                                 sector = r10_bio->devs[j].addr;
2466
2467                                 if (is_badblock(rdev, sector, max_sync,
2468                                                 &first_bad, &bad_sectors)) {
2469                                         if (first_bad > sector)
2470                                                 max_sync = first_bad - sector;
2471                                         else {
2472                                                 bad_sectors -= (sector
2473                                                                 - first_bad);
2474                                                 if (max_sync > bad_sectors)
2475                                                         max_sync = bad_sectors;
2476                                                 continue;
2477                                         }
2478                                 }
2479                                 bio = r10_bio->devs[0].bio;
2480                                 bio->bi_next = biolist;
2481                                 biolist = bio;
2482                                 bio->bi_private = r10_bio;
2483                                 bio->bi_end_io = end_sync_read;
2484                                 bio->bi_rw = READ;
2485                                 from_addr = r10_bio->devs[j].addr;
2486                                 bio->bi_sector = from_addr +
2487                                         conf->mirrors[d].rdev->data_offset;
2488                                 bio->bi_bdev = conf->mirrors[d].rdev->bdev;
2489                                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2490                                 atomic_inc(&r10_bio->remaining);
2491                                 /* and we write to 'i' */
2492
2493                                 for (k=0; k<conf->copies; k++)
2494                                         if (r10_bio->devs[k].devnum == i)
2495                                                 break;
2496                                 BUG_ON(k == conf->copies);
2497                                 bio = r10_bio->devs[1].bio;
2498                                 bio->bi_next = biolist;
2499                                 biolist = bio;
2500                                 bio->bi_private = r10_bio;
2501                                 bio->bi_end_io = end_sync_write;
2502                                 bio->bi_rw = WRITE;
2503                                 to_addr = r10_bio->devs[k].addr;
2504                                 bio->bi_sector = to_addr +
2505                                         conf->mirrors[i].rdev->data_offset;
2506                                 bio->bi_bdev = conf->mirrors[i].rdev->bdev;
2507
2508                                 r10_bio->devs[0].devnum = d;
2509                                 r10_bio->devs[0].addr = from_addr;
2510                                 r10_bio->devs[1].devnum = i;
2511                                 r10_bio->devs[1].addr = to_addr;
2512
2513                                 break;
2514                         }
2515                         if (j == conf->copies) {
2516                                 /* Cannot recover, so abort the recovery or
2517                                  * record a bad block */
2518                                 put_buf(r10_bio);
2519                                 if (rb2)
2520                                         atomic_dec(&rb2->remaining);
2521                                 r10_bio = rb2;
2522                                 if (any_working) {
2523                                         /* problem is that there are bad blocks
2524                                          * on other device(s)
2525                                          */
2526                                         int k;
2527                                         for (k = 0; k < conf->copies; k++)
2528                                                 if (r10_bio->devs[k].devnum == i)
2529                                                         break;
2530                                         if (!rdev_set_badblocks(
2531                                                     conf->mirrors[i].rdev,
2532                                                     r10_bio->devs[k].addr,
2533                                                     max_sync, 0))
2534                                                 any_working = 0;
2535                                 }
2536                                 if (!any_working)  {
2537                                         if (!test_and_set_bit(MD_RECOVERY_INTR,
2538                                                               &mddev->recovery))
2539                                                 printk(KERN_INFO "md/raid10:%s: insufficient "
2540                                                        "working devices for recovery.\n",
2541                                                        mdname(mddev));
2542                                         conf->mirrors[i].recovery_disabled
2543                                                 = mddev->recovery_disabled;
2544                                 }
2545                                 break;
2546                         }
2547                 }
2548                 if (biolist == NULL) {
2549                         while (r10_bio) {
2550                                 r10bio_t *rb2 = r10_bio;
2551                                 r10_bio = (r10bio_t*) rb2->master_bio;
2552                                 rb2->master_bio = NULL;
2553                                 put_buf(rb2);
2554                         }
2555                         goto giveup;
2556                 }
2557         } else {
2558                 /* resync. Schedule a read for every block at this virt offset */
2559                 int count = 0;
2560
2561                 bitmap_cond_end_sync(mddev->bitmap, sector_nr);
2562
2563                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
2564                                        &sync_blocks, mddev->degraded) &&
2565                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
2566                                                  &mddev->recovery)) {
2567                         /* We can skip this block */
2568                         *skipped = 1;
2569                         return sync_blocks + sectors_skipped;
2570                 }
2571                 if (sync_blocks < max_sync)
2572                         max_sync = sync_blocks;
2573                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
2574
2575                 r10_bio->mddev = mddev;
2576                 atomic_set(&r10_bio->remaining, 0);
2577                 raise_barrier(conf, 0);
2578                 conf->next_resync = sector_nr;
2579
2580                 r10_bio->master_bio = NULL;
2581                 r10_bio->sector = sector_nr;
2582                 set_bit(R10BIO_IsSync, &r10_bio->state);
2583                 raid10_find_phys(conf, r10_bio);
2584                 r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
2585
2586                 for (i=0; i<conf->copies; i++) {
2587                         int d = r10_bio->devs[i].devnum;
2588                         sector_t first_bad, sector;
2589                         int bad_sectors;
2590
2591                         bio = r10_bio->devs[i].bio;
2592                         bio->bi_end_io = NULL;
2593                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
2594                         if (conf->mirrors[d].rdev == NULL ||
2595                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
2596                                 continue;
2597                         sector = r10_bio->devs[i].addr;
2598                         if (is_badblock(conf->mirrors[d].rdev,
2599                                         sector, max_sync,
2600                                         &first_bad, &bad_sectors)) {
2601                                 if (first_bad > sector)
2602                                         max_sync = first_bad - sector;
2603                                 else {
2604                                         bad_sectors -= (sector - first_bad);
2605                                         if (max_sync > bad_sectors)
2606                                                 max_sync = max_sync;
2607                                         continue;
2608                                 }
2609                         }
2610                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2611                         atomic_inc(&r10_bio->remaining);
2612                         bio->bi_next = biolist;
2613                         biolist = bio;
2614                         bio->bi_private = r10_bio;
2615                         bio->bi_end_io = end_sync_read;
2616                         bio->bi_rw = READ;
2617                         bio->bi_sector = sector +
2618                                 conf->mirrors[d].rdev->data_offset;
2619                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
2620                         count++;
2621                 }
2622
2623                 if (count < 2) {
2624                         for (i=0; i<conf->copies; i++) {
2625                                 int d = r10_bio->devs[i].devnum;
2626                                 if (r10_bio->devs[i].bio->bi_end_io)
2627                                         rdev_dec_pending(conf->mirrors[d].rdev,
2628                                                          mddev);
2629                         }
2630                         put_buf(r10_bio);
2631                         biolist = NULL;
2632                         goto giveup;
2633                 }
2634         }
2635
2636         for (bio = biolist; bio ; bio=bio->bi_next) {
2637
2638                 bio->bi_flags &= ~(BIO_POOL_MASK - 1);
2639                 if (bio->bi_end_io)
2640                         bio->bi_flags |= 1 << BIO_UPTODATE;
2641                 bio->bi_vcnt = 0;
2642                 bio->bi_idx = 0;
2643                 bio->bi_phys_segments = 0;
2644                 bio->bi_size = 0;
2645         }
2646
2647         nr_sectors = 0;
2648         if (sector_nr + max_sync < max_sector)
2649                 max_sector = sector_nr + max_sync;
2650         do {
2651                 struct page *page;
2652                 int len = PAGE_SIZE;
2653                 if (sector_nr + (len>>9) > max_sector)
2654                         len = (max_sector - sector_nr) << 9;
2655                 if (len == 0)
2656                         break;
2657                 for (bio= biolist ; bio ; bio=bio->bi_next) {
2658                         struct bio *bio2;
2659                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
2660                         if (bio_add_page(bio, page, len, 0))
2661                                 continue;
2662
2663                         /* stop here */
2664                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
2665                         for (bio2 = biolist;
2666                              bio2 && bio2 != bio;
2667                              bio2 = bio2->bi_next) {
2668                                 /* remove last page from this bio */
2669                                 bio2->bi_vcnt--;
2670                                 bio2->bi_size -= len;
2671                                 bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
2672                         }
2673                         goto bio_full;
2674                 }
2675                 nr_sectors += len>>9;
2676                 sector_nr += len>>9;
2677         } while (biolist->bi_vcnt < RESYNC_PAGES);
2678  bio_full:
2679         r10_bio->sectors = nr_sectors;
2680
2681         while (biolist) {
2682                 bio = biolist;
2683                 biolist = biolist->bi_next;
2684
2685                 bio->bi_next = NULL;
2686                 r10_bio = bio->bi_private;
2687                 r10_bio->sectors = nr_sectors;
2688
2689                 if (bio->bi_end_io == end_sync_read) {
2690                         md_sync_acct(bio->bi_bdev, nr_sectors);
2691                         generic_make_request(bio);
2692                 }
2693         }
2694
2695         if (sectors_skipped)
2696                 /* pretend they weren't skipped, it makes
2697                  * no important difference in this case
2698                  */
2699                 md_done_sync(mddev, sectors_skipped, 1);
2700
2701         return sectors_skipped + nr_sectors;
2702  giveup:
2703         /* There is nowhere to write, so all non-sync
2704          * drives must be failed or in resync, all drives
2705          * have a bad block, so try the next chunk...
2706          */
2707         if (sector_nr + max_sync < max_sector)
2708                 max_sector = sector_nr + max_sync;
2709
2710         sectors_skipped += (max_sector - sector_nr);
2711         chunks_skipped ++;
2712         sector_nr = max_sector;
2713         goto skipped;
2714 }
2715
2716 static sector_t
2717 raid10_size(mddev_t *mddev, sector_t sectors, int raid_disks)
2718 {
2719         sector_t size;
2720         conf_t *conf = mddev->private;
2721
2722         if (!raid_disks)
2723                 raid_disks = conf->raid_disks;
2724         if (!sectors)
2725                 sectors = conf->dev_sectors;
2726
2727         size = sectors >> conf->chunk_shift;
2728         sector_div(size, conf->far_copies);
2729         size = size * raid_disks;
2730         sector_div(size, conf->near_copies);
2731
2732         return size << conf->chunk_shift;
2733 }
2734
2735
2736 static conf_t *setup_conf(mddev_t *mddev)
2737 {
2738         conf_t *conf = NULL;
2739         int nc, fc, fo;
2740         sector_t stride, size;
2741         int err = -EINVAL;
2742
2743         if (mddev->new_chunk_sectors < (PAGE_SIZE >> 9) ||
2744             !is_power_of_2(mddev->new_chunk_sectors)) {
2745                 printk(KERN_ERR "md/raid10:%s: chunk size must be "
2746                        "at least PAGE_SIZE(%ld) and be a power of 2.\n",
2747                        mdname(mddev), PAGE_SIZE);
2748                 goto out;
2749         }
2750
2751         nc = mddev->new_layout & 255;
2752         fc = (mddev->new_layout >> 8) & 255;
2753         fo = mddev->new_layout & (1<<16);
2754
2755         if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
2756             (mddev->new_layout >> 17)) {
2757                 printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
2758                        mdname(mddev), mddev->new_layout);
2759                 goto out;
2760         }
2761
2762         err = -ENOMEM;
2763         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
2764         if (!conf)
2765                 goto out;
2766
2767         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
2768                                 GFP_KERNEL);
2769         if (!conf->mirrors)
2770                 goto out;
2771
2772         conf->tmppage = alloc_page(GFP_KERNEL);
2773         if (!conf->tmppage)
2774                 goto out;
2775
2776
2777         conf->raid_disks = mddev->raid_disks;
2778         conf->near_copies = nc;
2779         conf->far_copies = fc;
2780         conf->copies = nc*fc;
2781         conf->far_offset = fo;
2782         conf->chunk_mask = mddev->new_chunk_sectors - 1;
2783         conf->chunk_shift = ffz(~mddev->new_chunk_sectors);
2784
2785         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
2786                                            r10bio_pool_free, conf);
2787         if (!conf->r10bio_pool)
2788                 goto out;
2789
2790         size = mddev->dev_sectors >> conf->chunk_shift;
2791         sector_div(size, fc);
2792         size = size * conf->raid_disks;
2793         sector_div(size, nc);
2794         /* 'size' is now the number of chunks in the array */
2795         /* calculate "used chunks per device" in 'stride' */
2796         stride = size * conf->copies;
2797
2798         /* We need to round up when dividing by raid_disks to
2799          * get the stride size.
2800          */
2801         stride += conf->raid_disks - 1;
2802         sector_div(stride, conf->raid_disks);
2803
2804         conf->dev_sectors = stride << conf->chunk_shift;
2805
2806         if (fo)
2807                 stride = 1;
2808         else
2809                 sector_div(stride, fc);
2810         conf->stride = stride << conf->chunk_shift;
2811
2812
2813         spin_lock_init(&conf->device_lock);
2814         INIT_LIST_HEAD(&conf->retry_list);
2815
2816         spin_lock_init(&conf->resync_lock);
2817         init_waitqueue_head(&conf->wait_barrier);
2818
2819         conf->thread = md_register_thread(raid10d, mddev, NULL);
2820         if (!conf->thread)
2821                 goto out;
2822
2823         conf->mddev = mddev;
2824         return conf;
2825
2826  out:
2827         printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
2828                mdname(mddev));
2829         if (conf) {
2830                 if (conf->r10bio_pool)
2831                         mempool_destroy(conf->r10bio_pool);
2832                 kfree(conf->mirrors);
2833                 safe_put_page(conf->tmppage);
2834                 kfree(conf);
2835         }
2836         return ERR_PTR(err);
2837 }
2838
2839 static int run(mddev_t *mddev)
2840 {
2841         conf_t *conf;
2842         int i, disk_idx, chunk_size;
2843         mirror_info_t *disk;
2844         mdk_rdev_t *rdev;
2845         sector_t size;
2846
2847         /*
2848          * copy the already verified devices into our private RAID10
2849          * bookkeeping area. [whatever we allocate in run(),
2850          * should be freed in stop()]
2851          */
2852
2853         if (mddev->private == NULL) {
2854                 conf = setup_conf(mddev);
2855                 if (IS_ERR(conf))
2856                         return PTR_ERR(conf);
2857                 mddev->private = conf;
2858         }
2859         conf = mddev->private;
2860         if (!conf)
2861                 goto out;
2862
2863         mddev->thread = conf->thread;
2864         conf->thread = NULL;
2865
2866         chunk_size = mddev->chunk_sectors << 9;
2867         blk_queue_io_min(mddev->queue, chunk_size);
2868         if (conf->raid_disks % conf->near_copies)
2869                 blk_queue_io_opt(mddev->queue, chunk_size * conf->raid_disks);
2870         else
2871                 blk_queue_io_opt(mddev->queue, chunk_size *
2872                                  (conf->raid_disks / conf->near_copies));
2873
2874         list_for_each_entry(rdev, &mddev->disks, same_set) {
2875
2876                 disk_idx = rdev->raid_disk;
2877                 if (disk_idx >= conf->raid_disks
2878                     || disk_idx < 0)
2879                         continue;
2880                 disk = conf->mirrors + disk_idx;
2881
2882                 disk->rdev = rdev;
2883                 disk_stack_limits(mddev->gendisk, rdev->bdev,
2884                                   rdev->data_offset << 9);
2885                 /* as we don't honour merge_bvec_fn, we must never risk
2886                  * violating it, so limit max_segments to 1 lying
2887                  * within a single page.
2888                  */
2889                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
2890                         blk_queue_max_segments(mddev->queue, 1);
2891                         blk_queue_segment_boundary(mddev->queue,
2892                                                    PAGE_CACHE_SIZE - 1);
2893                 }
2894
2895                 disk->head_position = 0;
2896         }
2897         /* need to check that every block has at least one working mirror */
2898         if (!enough(conf, -1)) {
2899                 printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
2900                        mdname(mddev));
2901                 goto out_free_conf;
2902         }
2903
2904         mddev->degraded = 0;
2905         for (i = 0; i < conf->raid_disks; i++) {
2906
2907                 disk = conf->mirrors + i;
2908
2909                 if (!disk->rdev ||
2910                     !test_bit(In_sync, &disk->rdev->flags)) {
2911                         disk->head_position = 0;
2912                         mddev->degraded++;
2913                         if (disk->rdev)
2914                                 conf->fullsync = 1;
2915                 }
2916         }
2917
2918         if (mddev->recovery_cp != MaxSector)
2919                 printk(KERN_NOTICE "md/raid10:%s: not clean"
2920                        " -- starting background reconstruction\n",
2921                        mdname(mddev));
2922         printk(KERN_INFO
2923                 "md/raid10:%s: active with %d out of %d devices\n",
2924                 mdname(mddev), conf->raid_disks - mddev->degraded,
2925                 conf->raid_disks);
2926         /*
2927          * Ok, everything is just fine now
2928          */
2929         mddev->dev_sectors = conf->dev_sectors;
2930         size = raid10_size(mddev, 0, 0);
2931         md_set_array_sectors(mddev, size);
2932         mddev->resync_max_sectors = size;
2933
2934         mddev->queue->backing_dev_info.congested_fn = raid10_congested;
2935         mddev->queue->backing_dev_info.congested_data = mddev;
2936
2937         /* Calculate max read-ahead size.
2938          * We need to readahead at least twice a whole stripe....
2939          * maybe...
2940          */
2941         {
2942                 int stripe = conf->raid_disks *
2943                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
2944                 stripe /= conf->near_copies;
2945                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
2946                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
2947         }
2948
2949         if (conf->near_copies < conf->raid_disks)
2950                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
2951
2952         if (md_integrity_register(mddev))
2953                 goto out_free_conf;
2954
2955         return 0;
2956
2957 out_free_conf:
2958         md_unregister_thread(&mddev->thread);
2959         if (conf->r10bio_pool)
2960                 mempool_destroy(conf->r10bio_pool);
2961         safe_put_page(conf->tmppage);
2962         kfree(conf->mirrors);
2963         kfree(conf);
2964         mddev->private = NULL;
2965 out:
2966         return -EIO;
2967 }
2968
2969 static int stop(mddev_t *mddev)
2970 {
2971         conf_t *conf = mddev->private;
2972
2973         raise_barrier(conf, 0);
2974         lower_barrier(conf);
2975
2976         md_unregister_thread(&mddev->thread);
2977         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2978         if (conf->r10bio_pool)
2979                 mempool_destroy(conf->r10bio_pool);
2980         kfree(conf->mirrors);
2981         kfree(conf);
2982         mddev->private = NULL;
2983         return 0;
2984 }
2985
2986 static void raid10_quiesce(mddev_t *mddev, int state)
2987 {
2988         conf_t *conf = mddev->private;
2989
2990         switch(state) {
2991         case 1:
2992                 raise_barrier(conf, 0);
2993                 break;
2994         case 0:
2995                 lower_barrier(conf);
2996                 break;
2997         }
2998 }
2999
3000 static void *raid10_takeover_raid0(mddev_t *mddev)
3001 {
3002         mdk_rdev_t *rdev;
3003         conf_t *conf;
3004
3005         if (mddev->degraded > 0) {
3006                 printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
3007                        mdname(mddev));
3008                 return ERR_PTR(-EINVAL);
3009         }
3010
3011         /* Set new parameters */
3012         mddev->new_level = 10;
3013         /* new layout: far_copies = 1, near_copies = 2 */
3014         mddev->new_layout = (1<<8) + 2;
3015         mddev->new_chunk_sectors = mddev->chunk_sectors;
3016         mddev->delta_disks = mddev->raid_disks;
3017         mddev->raid_disks *= 2;
3018         /* make sure it will be not marked as dirty */
3019         mddev->recovery_cp = MaxSector;
3020
3021         conf = setup_conf(mddev);
3022         if (!IS_ERR(conf)) {
3023                 list_for_each_entry(rdev, &mddev->disks, same_set)
3024                         if (rdev->raid_disk >= 0)
3025                                 rdev->new_raid_disk = rdev->raid_disk * 2;
3026                 conf->barrier = 1;
3027         }
3028
3029         return conf;
3030 }
3031
3032 static void *raid10_takeover(mddev_t *mddev)
3033 {
3034         struct raid0_private_data *raid0_priv;
3035
3036         /* raid10 can take over:
3037          *  raid0 - providing it has only two drives
3038          */
3039         if (mddev->level == 0) {
3040                 /* for raid0 takeover only one zone is supported */
3041                 raid0_priv = mddev->private;
3042                 if (raid0_priv->nr_strip_zones > 1) {
3043                         printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
3044                                " with more than one zone.\n",
3045                                mdname(mddev));
3046                         return ERR_PTR(-EINVAL);
3047                 }
3048                 return raid10_takeover_raid0(mddev);
3049         }
3050         return ERR_PTR(-EINVAL);
3051 }
3052
3053 static struct mdk_personality raid10_personality =
3054 {
3055         .name           = "raid10",
3056         .level          = 10,
3057         .owner          = THIS_MODULE,
3058         .make_request   = make_request,
3059         .run            = run,
3060         .stop           = stop,
3061         .status         = status,
3062         .error_handler  = error,
3063         .hot_add_disk   = raid10_add_disk,
3064         .hot_remove_disk= raid10_remove_disk,
3065         .spare_active   = raid10_spare_active,
3066         .sync_request   = sync_request,
3067         .quiesce        = raid10_quiesce,
3068         .size           = raid10_size,
3069         .takeover       = raid10_takeover,
3070 };
3071
3072 static int __init raid_init(void)
3073 {
3074         return register_md_personality(&raid10_personality);
3075 }
3076
3077 static void raid_exit(void)
3078 {
3079         unregister_md_personality(&raid10_personality);
3080 }
3081
3082 module_init(raid_init);
3083 module_exit(raid_exit);
3084 MODULE_LICENSE("GPL");
3085 MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
3086 MODULE_ALIAS("md-personality-9"); /* RAID10 */
3087 MODULE_ALIAS("md-raid10");
3088 MODULE_ALIAS("md-level-10");