[BLOCK] Get rid of request_queue_t typedef
[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 futher 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 "dm-bio-list.h"
22 #include <linux/raid/raid10.h>
23 #include <linux/raid/bitmap.h>
24
25 /*
26  * RAID10 provides a combination of RAID0 and RAID1 functionality.
27  * The layout of data is defined by
28  *    chunk_size
29  *    raid_disks
30  *    near_copies (stored in low byte of layout)
31  *    far_copies (stored in second byte of layout)
32  *    far_offset (stored in bit 16 of layout )
33  *
34  * The data to be stored is divided into chunks using chunksize.
35  * Each device is divided into far_copies sections.
36  * In each section, chunks are laid out in a style similar to raid0, but
37  * near_copies copies of each chunk is stored (each on a different drive).
38  * The starting device for each section is offset near_copies from the starting
39  * device of the previous section.
40  * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
41  * drive.
42  * near_copies and far_copies must be at least one, and their product is at most
43  * raid_disks.
44  *
45  * If far_offset is true, then the far_copies are handled a bit differently.
46  * The copies are still in different stripes, but instead of be very far apart
47  * on disk, there are adjacent stripes.
48  */
49
50 /*
51  * Number of guaranteed r10bios in case of extreme VM load:
52  */
53 #define NR_RAID10_BIOS 256
54
55 static void unplug_slaves(mddev_t *mddev);
56
57 static void allow_barrier(conf_t *conf);
58 static void lower_barrier(conf_t *conf);
59
60 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
61 {
62         conf_t *conf = data;
63         r10bio_t *r10_bio;
64         int size = offsetof(struct r10bio_s, devs[conf->copies]);
65
66         /* allocate a r10bio with room for raid_disks entries in the bios array */
67         r10_bio = kzalloc(size, gfp_flags);
68         if (!r10_bio)
69                 unplug_slaves(conf->mddev);
70
71         return r10_bio;
72 }
73
74 static void r10bio_pool_free(void *r10_bio, void *data)
75 {
76         kfree(r10_bio);
77 }
78
79 #define RESYNC_BLOCK_SIZE (64*1024)
80 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
81 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
82 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
83 #define RESYNC_WINDOW (2048*1024)
84
85 /*
86  * When performing a resync, we need to read and compare, so
87  * we need as many pages are there are copies.
88  * When performing a recovery, we need 2 bios, one for read,
89  * one for write (we recover only one drive per r10buf)
90  *
91  */
92 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
93 {
94         conf_t *conf = data;
95         struct page *page;
96         r10bio_t *r10_bio;
97         struct bio *bio;
98         int i, j;
99         int nalloc;
100
101         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
102         if (!r10_bio) {
103                 unplug_slaves(conf->mddev);
104                 return NULL;
105         }
106
107         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
108                 nalloc = conf->copies; /* resync */
109         else
110                 nalloc = 2; /* recovery */
111
112         /*
113          * Allocate bios.
114          */
115         for (j = nalloc ; j-- ; ) {
116                 bio = bio_alloc(gfp_flags, RESYNC_PAGES);
117                 if (!bio)
118                         goto out_free_bio;
119                 r10_bio->devs[j].bio = bio;
120         }
121         /*
122          * Allocate RESYNC_PAGES data pages and attach them
123          * where needed.
124          */
125         for (j = 0 ; j < nalloc; j++) {
126                 bio = r10_bio->devs[j].bio;
127                 for (i = 0; i < RESYNC_PAGES; i++) {
128                         page = alloc_page(gfp_flags);
129                         if (unlikely(!page))
130                                 goto out_free_pages;
131
132                         bio->bi_io_vec[i].bv_page = page;
133                 }
134         }
135
136         return r10_bio;
137
138 out_free_pages:
139         for ( ; i > 0 ; i--)
140                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
141         while (j--)
142                 for (i = 0; i < RESYNC_PAGES ; i++)
143                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
144         j = -1;
145 out_free_bio:
146         while ( ++j < nalloc )
147                 bio_put(r10_bio->devs[j].bio);
148         r10bio_pool_free(r10_bio, conf);
149         return NULL;
150 }
151
152 static void r10buf_pool_free(void *__r10_bio, void *data)
153 {
154         int i;
155         conf_t *conf = data;
156         r10bio_t *r10bio = __r10_bio;
157         int j;
158
159         for (j=0; j < conf->copies; j++) {
160                 struct bio *bio = r10bio->devs[j].bio;
161                 if (bio) {
162                         for (i = 0; i < RESYNC_PAGES; i++) {
163                                 safe_put_page(bio->bi_io_vec[i].bv_page);
164                                 bio->bi_io_vec[i].bv_page = NULL;
165                         }
166                         bio_put(bio);
167                 }
168         }
169         r10bio_pool_free(r10bio, conf);
170 }
171
172 static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
173 {
174         int i;
175
176         for (i = 0; i < conf->copies; i++) {
177                 struct bio **bio = & r10_bio->devs[i].bio;
178                 if (*bio && *bio != IO_BLOCKED)
179                         bio_put(*bio);
180                 *bio = NULL;
181         }
182 }
183
184 static void free_r10bio(r10bio_t *r10_bio)
185 {
186         conf_t *conf = mddev_to_conf(r10_bio->mddev);
187
188         /*
189          * Wake up any possible resync thread that waits for the device
190          * to go idle.
191          */
192         allow_barrier(conf);
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 = mddev_to_conf(r10_bio->mddev);
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_to_conf(mddev);
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         md_wakeup_thread(mddev->thread);
219 }
220
221 /*
222  * raid_end_bio_io() is called when we have finished servicing a mirrored
223  * operation and are ready to return a success/failure code to the buffer
224  * cache layer.
225  */
226 static void raid_end_bio_io(r10bio_t *r10_bio)
227 {
228         struct bio *bio = r10_bio->master_bio;
229
230         bio_endio(bio, bio->bi_size,
231                 test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
232         free_r10bio(r10_bio);
233 }
234
235 /*
236  * Update disk head position estimator based on IRQ completion info.
237  */
238 static inline void update_head_pos(int slot, r10bio_t *r10_bio)
239 {
240         conf_t *conf = mddev_to_conf(r10_bio->mddev);
241
242         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
243                 r10_bio->devs[slot].addr + (r10_bio->sectors);
244 }
245
246 static int raid10_end_read_request(struct bio *bio, unsigned int bytes_done, int error)
247 {
248         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
249         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
250         int slot, dev;
251         conf_t *conf = mddev_to_conf(r10_bio->mddev);
252
253         if (bio->bi_size)
254                 return 1;
255
256         slot = r10_bio->read_slot;
257         dev = r10_bio->devs[slot].devnum;
258         /*
259          * this branch is our 'one mirror IO has finished' event handler:
260          */
261         update_head_pos(slot, r10_bio);
262
263         if (uptodate) {
264                 /*
265                  * Set R10BIO_Uptodate in our master bio, so that
266                  * we will return a good error code to the higher
267                  * levels even if IO on some other mirrored buffer fails.
268                  *
269                  * The 'master' represents the composite IO operation to
270                  * user-side. So if something waits for IO, then it will
271                  * wait for the 'master' bio.
272                  */
273                 set_bit(R10BIO_Uptodate, &r10_bio->state);
274                 raid_end_bio_io(r10_bio);
275         } else {
276                 /*
277                  * oops, read error:
278                  */
279                 char b[BDEVNAME_SIZE];
280                 if (printk_ratelimit())
281                         printk(KERN_ERR "raid10: %s: rescheduling sector %llu\n",
282                                bdevname(conf->mirrors[dev].rdev->bdev,b), (unsigned long long)r10_bio->sector);
283                 reschedule_retry(r10_bio);
284         }
285
286         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
287         return 0;
288 }
289
290 static int raid10_end_write_request(struct bio *bio, unsigned int bytes_done, int error)
291 {
292         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
293         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
294         int slot, dev;
295         conf_t *conf = mddev_to_conf(r10_bio->mddev);
296
297         if (bio->bi_size)
298                 return 1;
299
300         for (slot = 0; slot < conf->copies; slot++)
301                 if (r10_bio->devs[slot].bio == bio)
302                         break;
303         dev = r10_bio->devs[slot].devnum;
304
305         /*
306          * this branch is our 'one mirror IO has finished' event handler:
307          */
308         if (!uptodate) {
309                 md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
310                 /* an I/O failed, we can't clear the bitmap */
311                 set_bit(R10BIO_Degraded, &r10_bio->state);
312         } else
313                 /*
314                  * Set R10BIO_Uptodate in our master bio, so that
315                  * we will return a good error code for to the higher
316                  * levels even if IO on some other mirrored buffer fails.
317                  *
318                  * The 'master' represents the composite IO operation to
319                  * user-side. So if something waits for IO, then it will
320                  * wait for the 'master' bio.
321                  */
322                 set_bit(R10BIO_Uptodate, &r10_bio->state);
323
324         update_head_pos(slot, r10_bio);
325
326         /*
327          *
328          * Let's see if all mirrored write operations have finished
329          * already.
330          */
331         if (atomic_dec_and_test(&r10_bio->remaining)) {
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                 raid_end_bio_io(r10_bio);
339         }
340
341         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
342         return 0;
343 }
344
345
346 /*
347  * RAID10 layout manager
348  * Aswell as the chunksize and raid_disks count, there are two
349  * parameters: near_copies and far_copies.
350  * near_copies * far_copies must be <= raid_disks.
351  * Normally one of these will be 1.
352  * If both are 1, we get raid0.
353  * If near_copies == raid_disks, we get raid1.
354  *
355  * Chunks are layed out in raid0 style with near_copies copies of the
356  * first chunk, followed by near_copies copies of the next chunk and
357  * so on.
358  * If far_copies > 1, then after 1/far_copies of the array has been assigned
359  * as described above, we start again with a device offset of near_copies.
360  * So we effectively have another copy of the whole array further down all
361  * the drives, but with blocks on different drives.
362  * With this layout, and block is never stored twice on the one device.
363  *
364  * raid10_find_phys finds the sector offset of a given virtual sector
365  * on each device that it is on.
366  *
367  * raid10_find_virt does the reverse mapping, from a device and a
368  * sector offset to a virtual address
369  */
370
371 static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
372 {
373         int n,f;
374         sector_t sector;
375         sector_t chunk;
376         sector_t stripe;
377         int dev;
378
379         int slot = 0;
380
381         /* now calculate first sector/dev */
382         chunk = r10bio->sector >> conf->chunk_shift;
383         sector = r10bio->sector & conf->chunk_mask;
384
385         chunk *= conf->near_copies;
386         stripe = chunk;
387         dev = sector_div(stripe, conf->raid_disks);
388         if (conf->far_offset)
389                 stripe *= conf->far_copies;
390
391         sector += stripe << conf->chunk_shift;
392
393         /* and calculate all the others */
394         for (n=0; n < conf->near_copies; n++) {
395                 int d = dev;
396                 sector_t s = sector;
397                 r10bio->devs[slot].addr = sector;
398                 r10bio->devs[slot].devnum = d;
399                 slot++;
400
401                 for (f = 1; f < conf->far_copies; f++) {
402                         d += conf->near_copies;
403                         if (d >= conf->raid_disks)
404                                 d -= conf->raid_disks;
405                         s += conf->stride;
406                         r10bio->devs[slot].devnum = d;
407                         r10bio->devs[slot].addr = s;
408                         slot++;
409                 }
410                 dev++;
411                 if (dev >= conf->raid_disks) {
412                         dev = 0;
413                         sector += (conf->chunk_mask + 1);
414                 }
415         }
416         BUG_ON(slot != conf->copies);
417 }
418
419 static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
420 {
421         sector_t offset, chunk, vchunk;
422
423         offset = sector & conf->chunk_mask;
424         if (conf->far_offset) {
425                 int fc;
426                 chunk = sector >> conf->chunk_shift;
427                 fc = sector_div(chunk, conf->far_copies);
428                 dev -= fc * conf->near_copies;
429                 if (dev < 0)
430                         dev += conf->raid_disks;
431         } else {
432                 while (sector >= conf->stride) {
433                         sector -= conf->stride;
434                         if (dev < conf->near_copies)
435                                 dev += conf->raid_disks - conf->near_copies;
436                         else
437                                 dev -= conf->near_copies;
438                 }
439                 chunk = sector >> conf->chunk_shift;
440         }
441         vchunk = chunk * conf->raid_disks + dev;
442         sector_div(vchunk, conf->near_copies);
443         return (vchunk << conf->chunk_shift) + offset;
444 }
445
446 /**
447  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
448  *      @q: request queue
449  *      @bio: the buffer head that's been built up so far
450  *      @biovec: the request that could be merged to it.
451  *
452  *      Return amount of bytes we can accept at this offset
453  *      If near_copies == raid_disk, there are no striping issues,
454  *      but in that case, the function isn't called at all.
455  */
456 static int raid10_mergeable_bvec(struct request_queue *q, struct bio *bio,
457                                 struct bio_vec *bio_vec)
458 {
459         mddev_t *mddev = q->queuedata;
460         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
461         int max;
462         unsigned int chunk_sectors = mddev->chunk_size >> 9;
463         unsigned int bio_sectors = bio->bi_size >> 9;
464
465         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
466         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
467         if (max <= bio_vec->bv_len && bio_sectors == 0)
468                 return bio_vec->bv_len;
469         else
470                 return max;
471 }
472
473 /*
474  * This routine returns the disk from which the requested read should
475  * be done. There is a per-array 'next expected sequential IO' sector
476  * number - if this matches on the next IO then we use the last disk.
477  * There is also a per-disk 'last know head position' sector that is
478  * maintained from IRQ contexts, both the normal and the resync IO
479  * completion handlers update this position correctly. If there is no
480  * perfect sequential match then we pick the disk whose head is closest.
481  *
482  * If there are 2 mirrors in the same 2 devices, performance degrades
483  * because position is mirror, not device based.
484  *
485  * The rdev for the device selected will have nr_pending incremented.
486  */
487
488 /*
489  * FIXME: possibly should rethink readbalancing and do it differently
490  * depending on near_copies / far_copies geometry.
491  */
492 static int read_balance(conf_t *conf, r10bio_t *r10_bio)
493 {
494         const unsigned long this_sector = r10_bio->sector;
495         int disk, slot, nslot;
496         const int sectors = r10_bio->sectors;
497         sector_t new_distance, current_distance;
498         mdk_rdev_t *rdev;
499
500         raid10_find_phys(conf, r10_bio);
501         rcu_read_lock();
502         /*
503          * Check if we can balance. We can balance on the whole
504          * device if no resync is going on (recovery is ok), or below
505          * the resync window. We take the first readable disk when
506          * above the resync window.
507          */
508         if (conf->mddev->recovery_cp < MaxSector
509             && (this_sector + sectors >= conf->next_resync)) {
510                 /* make sure that disk is operational */
511                 slot = 0;
512                 disk = r10_bio->devs[slot].devnum;
513
514                 while ((rdev = rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
515                        r10_bio->devs[slot].bio == IO_BLOCKED ||
516                        !test_bit(In_sync, &rdev->flags)) {
517                         slot++;
518                         if (slot == conf->copies) {
519                                 slot = 0;
520                                 disk = -1;
521                                 break;
522                         }
523                         disk = r10_bio->devs[slot].devnum;
524                 }
525                 goto rb_out;
526         }
527
528
529         /* make sure the disk is operational */
530         slot = 0;
531         disk = r10_bio->devs[slot].devnum;
532         while ((rdev=rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
533                r10_bio->devs[slot].bio == IO_BLOCKED ||
534                !test_bit(In_sync, &rdev->flags)) {
535                 slot ++;
536                 if (slot == conf->copies) {
537                         disk = -1;
538                         goto rb_out;
539                 }
540                 disk = r10_bio->devs[slot].devnum;
541         }
542
543
544         current_distance = abs(r10_bio->devs[slot].addr -
545                                conf->mirrors[disk].head_position);
546
547         /* Find the disk whose head is closest */
548
549         for (nslot = slot; nslot < conf->copies; nslot++) {
550                 int ndisk = r10_bio->devs[nslot].devnum;
551
552
553                 if ((rdev=rcu_dereference(conf->mirrors[ndisk].rdev)) == NULL ||
554                     r10_bio->devs[nslot].bio == IO_BLOCKED ||
555                     !test_bit(In_sync, &rdev->flags))
556                         continue;
557
558                 /* This optimisation is debatable, and completely destroys
559                  * sequential read speed for 'far copies' arrays.  So only
560                  * keep it for 'near' arrays, and review those later.
561                  */
562                 if (conf->near_copies > 1 && !atomic_read(&rdev->nr_pending)) {
563                         disk = ndisk;
564                         slot = nslot;
565                         break;
566                 }
567                 new_distance = abs(r10_bio->devs[nslot].addr -
568                                    conf->mirrors[ndisk].head_position);
569                 if (new_distance < current_distance) {
570                         current_distance = new_distance;
571                         disk = ndisk;
572                         slot = nslot;
573                 }
574         }
575
576 rb_out:
577         r10_bio->read_slot = slot;
578 /*      conf->next_seq_sect = this_sector + sectors;*/
579
580         if (disk >= 0 && (rdev=rcu_dereference(conf->mirrors[disk].rdev))!= NULL)
581                 atomic_inc(&conf->mirrors[disk].rdev->nr_pending);
582         else
583                 disk = -1;
584         rcu_read_unlock();
585
586         return disk;
587 }
588
589 static void unplug_slaves(mddev_t *mddev)
590 {
591         conf_t *conf = mddev_to_conf(mddev);
592         int i;
593
594         rcu_read_lock();
595         for (i=0; i<mddev->raid_disks; i++) {
596                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
597                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
598                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
599
600                         atomic_inc(&rdev->nr_pending);
601                         rcu_read_unlock();
602
603                         if (r_queue->unplug_fn)
604                                 r_queue->unplug_fn(r_queue);
605
606                         rdev_dec_pending(rdev, mddev);
607                         rcu_read_lock();
608                 }
609         }
610         rcu_read_unlock();
611 }
612
613 static void raid10_unplug(struct request_queue *q)
614 {
615         mddev_t *mddev = q->queuedata;
616
617         unplug_slaves(q->queuedata);
618         md_wakeup_thread(mddev->thread);
619 }
620
621 static int raid10_issue_flush(struct request_queue *q, struct gendisk *disk,
622                              sector_t *error_sector)
623 {
624         mddev_t *mddev = q->queuedata;
625         conf_t *conf = mddev_to_conf(mddev);
626         int i, ret = 0;
627
628         rcu_read_lock();
629         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
630                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
631                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
632                         struct block_device *bdev = rdev->bdev;
633                         struct request_queue *r_queue = bdev_get_queue(bdev);
634
635                         if (!r_queue->issue_flush_fn)
636                                 ret = -EOPNOTSUPP;
637                         else {
638                                 atomic_inc(&rdev->nr_pending);
639                                 rcu_read_unlock();
640                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
641                                                               error_sector);
642                                 rdev_dec_pending(rdev, mddev);
643                                 rcu_read_lock();
644                         }
645                 }
646         }
647         rcu_read_unlock();
648         return ret;
649 }
650
651 static int raid10_congested(void *data, int bits)
652 {
653         mddev_t *mddev = data;
654         conf_t *conf = mddev_to_conf(mddev);
655         int i, ret = 0;
656
657         rcu_read_lock();
658         for (i = 0; i < mddev->raid_disks && ret == 0; i++) {
659                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
660                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
661                         struct request_queue *q = bdev_get_queue(rdev->bdev);
662
663                         ret |= bdi_congested(&q->backing_dev_info, bits);
664                 }
665         }
666         rcu_read_unlock();
667         return ret;
668 }
669
670
671 /* Barriers....
672  * Sometimes we need to suspend IO while we do something else,
673  * either some resync/recovery, or reconfigure the array.
674  * To do this we raise a 'barrier'.
675  * The 'barrier' is a counter that can be raised multiple times
676  * to count how many activities are happening which preclude
677  * normal IO.
678  * We can only raise the barrier if there is no pending IO.
679  * i.e. if nr_pending == 0.
680  * We choose only to raise the barrier if no-one is waiting for the
681  * barrier to go down.  This means that as soon as an IO request
682  * is ready, no other operations which require a barrier will start
683  * until the IO request has had a chance.
684  *
685  * So: regular IO calls 'wait_barrier'.  When that returns there
686  *    is no backgroup IO happening,  It must arrange to call
687  *    allow_barrier when it has finished its IO.
688  * backgroup IO calls must call raise_barrier.  Once that returns
689  *    there is no normal IO happeing.  It must arrange to call
690  *    lower_barrier when the particular background IO completes.
691  */
692 #define RESYNC_DEPTH 32
693
694 static void raise_barrier(conf_t *conf, int force)
695 {
696         BUG_ON(force && !conf->barrier);
697         spin_lock_irq(&conf->resync_lock);
698
699         /* Wait until no block IO is waiting (unless 'force') */
700         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
701                             conf->resync_lock,
702                             raid10_unplug(conf->mddev->queue));
703
704         /* block any new IO from starting */
705         conf->barrier++;
706
707         /* No wait for all pending IO to complete */
708         wait_event_lock_irq(conf->wait_barrier,
709                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
710                             conf->resync_lock,
711                             raid10_unplug(conf->mddev->queue));
712
713         spin_unlock_irq(&conf->resync_lock);
714 }
715
716 static void lower_barrier(conf_t *conf)
717 {
718         unsigned long flags;
719         spin_lock_irqsave(&conf->resync_lock, flags);
720         conf->barrier--;
721         spin_unlock_irqrestore(&conf->resync_lock, flags);
722         wake_up(&conf->wait_barrier);
723 }
724
725 static void wait_barrier(conf_t *conf)
726 {
727         spin_lock_irq(&conf->resync_lock);
728         if (conf->barrier) {
729                 conf->nr_waiting++;
730                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
731                                     conf->resync_lock,
732                                     raid10_unplug(conf->mddev->queue));
733                 conf->nr_waiting--;
734         }
735         conf->nr_pending++;
736         spin_unlock_irq(&conf->resync_lock);
737 }
738
739 static void allow_barrier(conf_t *conf)
740 {
741         unsigned long flags;
742         spin_lock_irqsave(&conf->resync_lock, flags);
743         conf->nr_pending--;
744         spin_unlock_irqrestore(&conf->resync_lock, flags);
745         wake_up(&conf->wait_barrier);
746 }
747
748 static void freeze_array(conf_t *conf)
749 {
750         /* stop syncio and normal IO and wait for everything to
751          * go quiet.
752          * We increment barrier and nr_waiting, and then
753          * wait until barrier+nr_pending match nr_queued+2
754          */
755         spin_lock_irq(&conf->resync_lock);
756         conf->barrier++;
757         conf->nr_waiting++;
758         wait_event_lock_irq(conf->wait_barrier,
759                             conf->barrier+conf->nr_pending == conf->nr_queued+2,
760                             conf->resync_lock,
761                             raid10_unplug(conf->mddev->queue));
762         spin_unlock_irq(&conf->resync_lock);
763 }
764
765 static void unfreeze_array(conf_t *conf)
766 {
767         /* reverse the effect of the freeze */
768         spin_lock_irq(&conf->resync_lock);
769         conf->barrier--;
770         conf->nr_waiting--;
771         wake_up(&conf->wait_barrier);
772         spin_unlock_irq(&conf->resync_lock);
773 }
774
775 static int make_request(struct request_queue *q, struct bio * bio)
776 {
777         mddev_t *mddev = q->queuedata;
778         conf_t *conf = mddev_to_conf(mddev);
779         mirror_info_t *mirror;
780         r10bio_t *r10_bio;
781         struct bio *read_bio;
782         int i;
783         int chunk_sects = conf->chunk_mask + 1;
784         const int rw = bio_data_dir(bio);
785         const int do_sync = bio_sync(bio);
786         struct bio_list bl;
787         unsigned long flags;
788
789         if (unlikely(bio_barrier(bio))) {
790                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
791                 return 0;
792         }
793
794         /* If this request crosses a chunk boundary, we need to
795          * split it.  This will only happen for 1 PAGE (or less) requests.
796          */
797         if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
798                       > chunk_sects &&
799                     conf->near_copies < conf->raid_disks)) {
800                 struct bio_pair *bp;
801                 /* Sanity check -- queue functions should prevent this happening */
802                 if (bio->bi_vcnt != 1 ||
803                     bio->bi_idx != 0)
804                         goto bad_map;
805                 /* This is a one page bio that upper layers
806                  * refuse to split for us, so we need to split it.
807                  */
808                 bp = bio_split(bio, bio_split_pool,
809                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
810                 if (make_request(q, &bp->bio1))
811                         generic_make_request(&bp->bio1);
812                 if (make_request(q, &bp->bio2))
813                         generic_make_request(&bp->bio2);
814
815                 bio_pair_release(bp);
816                 return 0;
817         bad_map:
818                 printk("raid10_make_request bug: can't convert block across chunks"
819                        " or bigger than %dk %llu %d\n", chunk_sects/2,
820                        (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
821
822                 bio_io_error(bio, bio->bi_size);
823                 return 0;
824         }
825
826         md_write_start(mddev, bio);
827
828         /*
829          * Register the new request and wait if the reconstruction
830          * thread has put up a bar for new requests.
831          * Continue immediately if no resync is active currently.
832          */
833         wait_barrier(conf);
834
835         disk_stat_inc(mddev->gendisk, ios[rw]);
836         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
837
838         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
839
840         r10_bio->master_bio = bio;
841         r10_bio->sectors = bio->bi_size >> 9;
842
843         r10_bio->mddev = mddev;
844         r10_bio->sector = bio->bi_sector;
845         r10_bio->state = 0;
846
847         if (rw == READ) {
848                 /*
849                  * read balancing logic:
850                  */
851                 int disk = read_balance(conf, r10_bio);
852                 int slot = r10_bio->read_slot;
853                 if (disk < 0) {
854                         raid_end_bio_io(r10_bio);
855                         return 0;
856                 }
857                 mirror = conf->mirrors + disk;
858
859                 read_bio = bio_clone(bio, GFP_NOIO);
860
861                 r10_bio->devs[slot].bio = read_bio;
862
863                 read_bio->bi_sector = r10_bio->devs[slot].addr +
864                         mirror->rdev->data_offset;
865                 read_bio->bi_bdev = mirror->rdev->bdev;
866                 read_bio->bi_end_io = raid10_end_read_request;
867                 read_bio->bi_rw = READ | do_sync;
868                 read_bio->bi_private = r10_bio;
869
870                 generic_make_request(read_bio);
871                 return 0;
872         }
873
874         /*
875          * WRITE:
876          */
877         /* first select target devices under spinlock and
878          * inc refcount on their rdev.  Record them by setting
879          * bios[x] to bio
880          */
881         raid10_find_phys(conf, r10_bio);
882         rcu_read_lock();
883         for (i = 0;  i < conf->copies; i++) {
884                 int d = r10_bio->devs[i].devnum;
885                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
886                 if (rdev &&
887                     !test_bit(Faulty, &rdev->flags)) {
888                         atomic_inc(&rdev->nr_pending);
889                         r10_bio->devs[i].bio = bio;
890                 } else {
891                         r10_bio->devs[i].bio = NULL;
892                         set_bit(R10BIO_Degraded, &r10_bio->state);
893                 }
894         }
895         rcu_read_unlock();
896
897         atomic_set(&r10_bio->remaining, 0);
898
899         bio_list_init(&bl);
900         for (i = 0; i < conf->copies; i++) {
901                 struct bio *mbio;
902                 int d = r10_bio->devs[i].devnum;
903                 if (!r10_bio->devs[i].bio)
904                         continue;
905
906                 mbio = bio_clone(bio, GFP_NOIO);
907                 r10_bio->devs[i].bio = mbio;
908
909                 mbio->bi_sector = r10_bio->devs[i].addr+
910                         conf->mirrors[d].rdev->data_offset;
911                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
912                 mbio->bi_end_io = raid10_end_write_request;
913                 mbio->bi_rw = WRITE | do_sync;
914                 mbio->bi_private = r10_bio;
915
916                 atomic_inc(&r10_bio->remaining);
917                 bio_list_add(&bl, mbio);
918         }
919
920         bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
921         spin_lock_irqsave(&conf->device_lock, flags);
922         bio_list_merge(&conf->pending_bio_list, &bl);
923         blk_plug_device(mddev->queue);
924         spin_unlock_irqrestore(&conf->device_lock, flags);
925
926         if (do_sync)
927                 md_wakeup_thread(mddev->thread);
928
929         return 0;
930 }
931
932 static void status(struct seq_file *seq, mddev_t *mddev)
933 {
934         conf_t *conf = mddev_to_conf(mddev);
935         int i;
936
937         if (conf->near_copies < conf->raid_disks)
938                 seq_printf(seq, " %dK chunks", mddev->chunk_size/1024);
939         if (conf->near_copies > 1)
940                 seq_printf(seq, " %d near-copies", conf->near_copies);
941         if (conf->far_copies > 1) {
942                 if (conf->far_offset)
943                         seq_printf(seq, " %d offset-copies", conf->far_copies);
944                 else
945                         seq_printf(seq, " %d far-copies", conf->far_copies);
946         }
947         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
948                                         conf->raid_disks - mddev->degraded);
949         for (i = 0; i < conf->raid_disks; i++)
950                 seq_printf(seq, "%s",
951                               conf->mirrors[i].rdev &&
952                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
953         seq_printf(seq, "]");
954 }
955
956 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
957 {
958         char b[BDEVNAME_SIZE];
959         conf_t *conf = mddev_to_conf(mddev);
960
961         /*
962          * If it is not operational, then we have already marked it as dead
963          * else if it is the last working disks, ignore the error, let the
964          * next level up know.
965          * else mark the drive as failed
966          */
967         if (test_bit(In_sync, &rdev->flags)
968             && conf->raid_disks-mddev->degraded == 1)
969                 /*
970                  * Don't fail the drive, just return an IO error.
971                  * The test should really be more sophisticated than
972                  * "working_disks == 1", but it isn't critical, and
973                  * can wait until we do more sophisticated "is the drive
974                  * really dead" tests...
975                  */
976                 return;
977         if (test_and_clear_bit(In_sync, &rdev->flags)) {
978                 unsigned long flags;
979                 spin_lock_irqsave(&conf->device_lock, flags);
980                 mddev->degraded++;
981                 spin_unlock_irqrestore(&conf->device_lock, flags);
982                 /*
983                  * if recovery is running, make sure it aborts.
984                  */
985                 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
986         }
987         set_bit(Faulty, &rdev->flags);
988         set_bit(MD_CHANGE_DEVS, &mddev->flags);
989         printk(KERN_ALERT "raid10: Disk failure on %s, disabling device. \n"
990                 "       Operation continuing on %d devices\n",
991                 bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
992 }
993
994 static void print_conf(conf_t *conf)
995 {
996         int i;
997         mirror_info_t *tmp;
998
999         printk("RAID10 conf printout:\n");
1000         if (!conf) {
1001                 printk("(!conf)\n");
1002                 return;
1003         }
1004         printk(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1005                 conf->raid_disks);
1006
1007         for (i = 0; i < conf->raid_disks; i++) {
1008                 char b[BDEVNAME_SIZE];
1009                 tmp = conf->mirrors + i;
1010                 if (tmp->rdev)
1011                         printk(" disk %d, wo:%d, o:%d, dev:%s\n",
1012                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1013                                 !test_bit(Faulty, &tmp->rdev->flags),
1014                                 bdevname(tmp->rdev->bdev,b));
1015         }
1016 }
1017
1018 static void close_sync(conf_t *conf)
1019 {
1020         wait_barrier(conf);
1021         allow_barrier(conf);
1022
1023         mempool_destroy(conf->r10buf_pool);
1024         conf->r10buf_pool = NULL;
1025 }
1026
1027 /* check if there are enough drives for
1028  * every block to appear on atleast one
1029  */
1030 static int enough(conf_t *conf)
1031 {
1032         int first = 0;
1033
1034         do {
1035                 int n = conf->copies;
1036                 int cnt = 0;
1037                 while (n--) {
1038                         if (conf->mirrors[first].rdev)
1039                                 cnt++;
1040                         first = (first+1) % conf->raid_disks;
1041                 }
1042                 if (cnt == 0)
1043                         return 0;
1044         } while (first != 0);
1045         return 1;
1046 }
1047
1048 static int raid10_spare_active(mddev_t *mddev)
1049 {
1050         int i;
1051         conf_t *conf = mddev->private;
1052         mirror_info_t *tmp;
1053
1054         /*
1055          * Find all non-in_sync disks within the RAID10 configuration
1056          * and mark them in_sync
1057          */
1058         for (i = 0; i < conf->raid_disks; i++) {
1059                 tmp = conf->mirrors + i;
1060                 if (tmp->rdev
1061                     && !test_bit(Faulty, &tmp->rdev->flags)
1062                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1063                         unsigned long flags;
1064                         spin_lock_irqsave(&conf->device_lock, flags);
1065                         mddev->degraded--;
1066                         spin_unlock_irqrestore(&conf->device_lock, flags);
1067                 }
1068         }
1069
1070         print_conf(conf);
1071         return 0;
1072 }
1073
1074
1075 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1076 {
1077         conf_t *conf = mddev->private;
1078         int found = 0;
1079         int mirror;
1080         mirror_info_t *p;
1081
1082         if (mddev->recovery_cp < MaxSector)
1083                 /* only hot-add to in-sync arrays, as recovery is
1084                  * very different from resync
1085                  */
1086                 return 0;
1087         if (!enough(conf))
1088                 return 0;
1089
1090         if (rdev->saved_raid_disk >= 0 &&
1091             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1092                 mirror = rdev->saved_raid_disk;
1093         else
1094                 mirror = 0;
1095         for ( ; mirror < mddev->raid_disks; mirror++)
1096                 if ( !(p=conf->mirrors+mirror)->rdev) {
1097
1098                         blk_queue_stack_limits(mddev->queue,
1099                                                rdev->bdev->bd_disk->queue);
1100                         /* as we don't honour merge_bvec_fn, we must never risk
1101                          * violating it, so limit ->max_sector to one PAGE, as
1102                          * a one page request is never in violation.
1103                          */
1104                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1105                             mddev->queue->max_sectors > (PAGE_SIZE>>9))
1106                                 mddev->queue->max_sectors = (PAGE_SIZE>>9);
1107
1108                         p->head_position = 0;
1109                         rdev->raid_disk = mirror;
1110                         found = 1;
1111                         if (rdev->saved_raid_disk != mirror)
1112                                 conf->fullsync = 1;
1113                         rcu_assign_pointer(p->rdev, rdev);
1114                         break;
1115                 }
1116
1117         print_conf(conf);
1118         return found;
1119 }
1120
1121 static int raid10_remove_disk(mddev_t *mddev, int number)
1122 {
1123         conf_t *conf = mddev->private;
1124         int err = 0;
1125         mdk_rdev_t *rdev;
1126         mirror_info_t *p = conf->mirrors+ number;
1127
1128         print_conf(conf);
1129         rdev = p->rdev;
1130         if (rdev) {
1131                 if (test_bit(In_sync, &rdev->flags) ||
1132                     atomic_read(&rdev->nr_pending)) {
1133                         err = -EBUSY;
1134                         goto abort;
1135                 }
1136                 p->rdev = NULL;
1137                 synchronize_rcu();
1138                 if (atomic_read(&rdev->nr_pending)) {
1139                         /* lost the race, try later */
1140                         err = -EBUSY;
1141                         p->rdev = rdev;
1142                 }
1143         }
1144 abort:
1145
1146         print_conf(conf);
1147         return err;
1148 }
1149
1150
1151 static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
1152 {
1153         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
1154         conf_t *conf = mddev_to_conf(r10_bio->mddev);
1155         int i,d;
1156
1157         if (bio->bi_size)
1158                 return 1;
1159
1160         for (i=0; i<conf->copies; i++)
1161                 if (r10_bio->devs[i].bio == bio)
1162                         break;
1163         BUG_ON(i == conf->copies);
1164         update_head_pos(i, r10_bio);
1165         d = r10_bio->devs[i].devnum;
1166
1167         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1168                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1169         else {
1170                 atomic_add(r10_bio->sectors,
1171                            &conf->mirrors[d].rdev->corrected_errors);
1172                 if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
1173                         md_error(r10_bio->mddev,
1174                                  conf->mirrors[d].rdev);
1175         }
1176
1177         /* for reconstruct, we always reschedule after a read.
1178          * for resync, only after all reads
1179          */
1180         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1181             atomic_dec_and_test(&r10_bio->remaining)) {
1182                 /* we have read all the blocks,
1183                  * do the comparison in process context in raid10d
1184                  */
1185                 reschedule_retry(r10_bio);
1186         }
1187         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1188         return 0;
1189 }
1190
1191 static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error)
1192 {
1193         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1194         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
1195         mddev_t *mddev = r10_bio->mddev;
1196         conf_t *conf = mddev_to_conf(mddev);
1197         int i,d;
1198
1199         if (bio->bi_size)
1200                 return 1;
1201
1202         for (i = 0; i < conf->copies; i++)
1203                 if (r10_bio->devs[i].bio == bio)
1204                         break;
1205         d = r10_bio->devs[i].devnum;
1206
1207         if (!uptodate)
1208                 md_error(mddev, conf->mirrors[d].rdev);
1209         update_head_pos(i, r10_bio);
1210
1211         while (atomic_dec_and_test(&r10_bio->remaining)) {
1212                 if (r10_bio->master_bio == NULL) {
1213                         /* the primary of several recovery bios */
1214                         md_done_sync(mddev, r10_bio->sectors, 1);
1215                         put_buf(r10_bio);
1216                         break;
1217                 } else {
1218                         r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
1219                         put_buf(r10_bio);
1220                         r10_bio = r10_bio2;
1221                 }
1222         }
1223         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1224         return 0;
1225 }
1226
1227 /*
1228  * Note: sync and recover and handled very differently for raid10
1229  * This code is for resync.
1230  * For resync, we read through virtual addresses and read all blocks.
1231  * If there is any error, we schedule a write.  The lowest numbered
1232  * drive is authoritative.
1233  * However requests come for physical address, so we need to map.
1234  * For every physical address there are raid_disks/copies virtual addresses,
1235  * which is always are least one, but is not necessarly an integer.
1236  * This means that a physical address can span multiple chunks, so we may
1237  * have to submit multiple io requests for a single sync request.
1238  */
1239 /*
1240  * We check if all blocks are in-sync and only write to blocks that
1241  * aren't in sync
1242  */
1243 static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1244 {
1245         conf_t *conf = mddev_to_conf(mddev);
1246         int i, first;
1247         struct bio *tbio, *fbio;
1248
1249         atomic_set(&r10_bio->remaining, 1);
1250
1251         /* find the first device with a block */
1252         for (i=0; i<conf->copies; i++)
1253                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1254                         break;
1255
1256         if (i == conf->copies)
1257                 goto done;
1258
1259         first = i;
1260         fbio = r10_bio->devs[i].bio;
1261
1262         /* now find blocks with errors */
1263         for (i=0 ; i < conf->copies ; i++) {
1264                 int  j, d;
1265                 int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
1266
1267                 tbio = r10_bio->devs[i].bio;
1268
1269                 if (tbio->bi_end_io != end_sync_read)
1270                         continue;
1271                 if (i == first)
1272                         continue;
1273                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1274                         /* We know that the bi_io_vec layout is the same for
1275                          * both 'first' and 'i', so we just compare them.
1276                          * All vec entries are PAGE_SIZE;
1277                          */
1278                         for (j = 0; j < vcnt; j++)
1279                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1280                                            page_address(tbio->bi_io_vec[j].bv_page),
1281                                            PAGE_SIZE))
1282                                         break;
1283                         if (j == vcnt)
1284                                 continue;
1285                         mddev->resync_mismatches += r10_bio->sectors;
1286                 }
1287                 if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1288                         /* Don't fix anything. */
1289                         continue;
1290                 /* Ok, we need to write this bio
1291                  * First we need to fixup bv_offset, bv_len and
1292                  * bi_vecs, as the read request might have corrupted these
1293                  */
1294                 tbio->bi_vcnt = vcnt;
1295                 tbio->bi_size = r10_bio->sectors << 9;
1296                 tbio->bi_idx = 0;
1297                 tbio->bi_phys_segments = 0;
1298                 tbio->bi_hw_segments = 0;
1299                 tbio->bi_hw_front_size = 0;
1300                 tbio->bi_hw_back_size = 0;
1301                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1302                 tbio->bi_flags |= 1 << BIO_UPTODATE;
1303                 tbio->bi_next = NULL;
1304                 tbio->bi_rw = WRITE;
1305                 tbio->bi_private = r10_bio;
1306                 tbio->bi_sector = r10_bio->devs[i].addr;
1307
1308                 for (j=0; j < vcnt ; j++) {
1309                         tbio->bi_io_vec[j].bv_offset = 0;
1310                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1311
1312                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1313                                page_address(fbio->bi_io_vec[j].bv_page),
1314                                PAGE_SIZE);
1315                 }
1316                 tbio->bi_end_io = end_sync_write;
1317
1318                 d = r10_bio->devs[i].devnum;
1319                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1320                 atomic_inc(&r10_bio->remaining);
1321                 md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1322
1323                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1324                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1325                 generic_make_request(tbio);
1326         }
1327
1328 done:
1329         if (atomic_dec_and_test(&r10_bio->remaining)) {
1330                 md_done_sync(mddev, r10_bio->sectors, 1);
1331                 put_buf(r10_bio);
1332         }
1333 }
1334
1335 /*
1336  * Now for the recovery code.
1337  * Recovery happens across physical sectors.
1338  * We recover all non-is_sync drives by finding the virtual address of
1339  * each, and then choose a working drive that also has that virt address.
1340  * There is a separate r10_bio for each non-in_sync drive.
1341  * Only the first two slots are in use. The first for reading,
1342  * The second for writing.
1343  *
1344  */
1345
1346 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1347 {
1348         conf_t *conf = mddev_to_conf(mddev);
1349         int i, d;
1350         struct bio *bio, *wbio;
1351
1352
1353         /* move the pages across to the second bio
1354          * and submit the write request
1355          */
1356         bio = r10_bio->devs[0].bio;
1357         wbio = r10_bio->devs[1].bio;
1358         for (i=0; i < wbio->bi_vcnt; i++) {
1359                 struct page *p = bio->bi_io_vec[i].bv_page;
1360                 bio->bi_io_vec[i].bv_page = wbio->bi_io_vec[i].bv_page;
1361                 wbio->bi_io_vec[i].bv_page = p;
1362         }
1363         d = r10_bio->devs[1].devnum;
1364
1365         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1366         md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
1367         if (test_bit(R10BIO_Uptodate, &r10_bio->state))
1368                 generic_make_request(wbio);
1369         else
1370                 bio_endio(wbio, wbio->bi_size, -EIO);
1371 }
1372
1373
1374 /*
1375  * This is a kernel thread which:
1376  *
1377  *      1.      Retries failed read operations on working mirrors.
1378  *      2.      Updates the raid superblock when problems encounter.
1379  *      3.      Performs writes following reads for array synchronising.
1380  */
1381
1382 static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
1383 {
1384         int sect = 0; /* Offset from r10_bio->sector */
1385         int sectors = r10_bio->sectors;
1386         mdk_rdev_t*rdev;
1387         while(sectors) {
1388                 int s = sectors;
1389                 int sl = r10_bio->read_slot;
1390                 int success = 0;
1391                 int start;
1392
1393                 if (s > (PAGE_SIZE>>9))
1394                         s = PAGE_SIZE >> 9;
1395
1396                 rcu_read_lock();
1397                 do {
1398                         int d = r10_bio->devs[sl].devnum;
1399                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1400                         if (rdev &&
1401                             test_bit(In_sync, &rdev->flags)) {
1402                                 atomic_inc(&rdev->nr_pending);
1403                                 rcu_read_unlock();
1404                                 success = sync_page_io(rdev->bdev,
1405                                                        r10_bio->devs[sl].addr +
1406                                                        sect + rdev->data_offset,
1407                                                        s<<9,
1408                                                        conf->tmppage, READ);
1409                                 rdev_dec_pending(rdev, mddev);
1410                                 rcu_read_lock();
1411                                 if (success)
1412                                         break;
1413                         }
1414                         sl++;
1415                         if (sl == conf->copies)
1416                                 sl = 0;
1417                 } while (!success && sl != r10_bio->read_slot);
1418                 rcu_read_unlock();
1419
1420                 if (!success) {
1421                         /* Cannot read from anywhere -- bye bye array */
1422                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
1423                         md_error(mddev, conf->mirrors[dn].rdev);
1424                         break;
1425                 }
1426
1427                 start = sl;
1428                 /* write it back and re-read */
1429                 rcu_read_lock();
1430                 while (sl != r10_bio->read_slot) {
1431                         int d;
1432                         if (sl==0)
1433                                 sl = conf->copies;
1434                         sl--;
1435                         d = r10_bio->devs[sl].devnum;
1436                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1437                         if (rdev &&
1438                             test_bit(In_sync, &rdev->flags)) {
1439                                 atomic_inc(&rdev->nr_pending);
1440                                 rcu_read_unlock();
1441                                 atomic_add(s, &rdev->corrected_errors);
1442                                 if (sync_page_io(rdev->bdev,
1443                                                  r10_bio->devs[sl].addr +
1444                                                  sect + rdev->data_offset,
1445                                                  s<<9, conf->tmppage, WRITE)
1446                                     == 0)
1447                                         /* Well, this device is dead */
1448                                         md_error(mddev, rdev);
1449                                 rdev_dec_pending(rdev, mddev);
1450                                 rcu_read_lock();
1451                         }
1452                 }
1453                 sl = start;
1454                 while (sl != r10_bio->read_slot) {
1455                         int d;
1456                         if (sl==0)
1457                                 sl = conf->copies;
1458                         sl--;
1459                         d = r10_bio->devs[sl].devnum;
1460                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1461                         if (rdev &&
1462                             test_bit(In_sync, &rdev->flags)) {
1463                                 char b[BDEVNAME_SIZE];
1464                                 atomic_inc(&rdev->nr_pending);
1465                                 rcu_read_unlock();
1466                                 if (sync_page_io(rdev->bdev,
1467                                                  r10_bio->devs[sl].addr +
1468                                                  sect + rdev->data_offset,
1469                                                  s<<9, conf->tmppage, READ) == 0)
1470                                         /* Well, this device is dead */
1471                                         md_error(mddev, rdev);
1472                                 else
1473                                         printk(KERN_INFO
1474                                                "raid10:%s: read error corrected"
1475                                                " (%d sectors at %llu on %s)\n",
1476                                                mdname(mddev), s,
1477                                                (unsigned long long)(sect+
1478                                                     rdev->data_offset),
1479                                                bdevname(rdev->bdev, b));
1480
1481                                 rdev_dec_pending(rdev, mddev);
1482                                 rcu_read_lock();
1483                         }
1484                 }
1485                 rcu_read_unlock();
1486
1487                 sectors -= s;
1488                 sect += s;
1489         }
1490 }
1491
1492 static void raid10d(mddev_t *mddev)
1493 {
1494         r10bio_t *r10_bio;
1495         struct bio *bio;
1496         unsigned long flags;
1497         conf_t *conf = mddev_to_conf(mddev);
1498         struct list_head *head = &conf->retry_list;
1499         int unplug=0;
1500         mdk_rdev_t *rdev;
1501
1502         md_check_recovery(mddev);
1503
1504         for (;;) {
1505                 char b[BDEVNAME_SIZE];
1506                 spin_lock_irqsave(&conf->device_lock, flags);
1507
1508                 if (conf->pending_bio_list.head) {
1509                         bio = bio_list_get(&conf->pending_bio_list);
1510                         blk_remove_plug(mddev->queue);
1511                         spin_unlock_irqrestore(&conf->device_lock, flags);
1512                         /* flush any pending bitmap writes to disk before proceeding w/ I/O */
1513                         bitmap_unplug(mddev->bitmap);
1514
1515                         while (bio) { /* submit pending writes */
1516                                 struct bio *next = bio->bi_next;
1517                                 bio->bi_next = NULL;
1518                                 generic_make_request(bio);
1519                                 bio = next;
1520                         }
1521                         unplug = 1;
1522
1523                         continue;
1524                 }
1525
1526                 if (list_empty(head))
1527                         break;
1528                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
1529                 list_del(head->prev);
1530                 conf->nr_queued--;
1531                 spin_unlock_irqrestore(&conf->device_lock, flags);
1532
1533                 mddev = r10_bio->mddev;
1534                 conf = mddev_to_conf(mddev);
1535                 if (test_bit(R10BIO_IsSync, &r10_bio->state)) {
1536                         sync_request_write(mddev, r10_bio);
1537                         unplug = 1;
1538                 } else  if (test_bit(R10BIO_IsRecover, &r10_bio->state)) {
1539                         recovery_request_write(mddev, r10_bio);
1540                         unplug = 1;
1541                 } else {
1542                         int mirror;
1543                         /* we got a read error. Maybe the drive is bad.  Maybe just
1544                          * the block and we can fix it.
1545                          * We freeze all other IO, and try reading the block from
1546                          * other devices.  When we find one, we re-write
1547                          * and check it that fixes the read error.
1548                          * This is all done synchronously while the array is
1549                          * frozen.
1550                          */
1551                         if (mddev->ro == 0) {
1552                                 freeze_array(conf);
1553                                 fix_read_error(conf, mddev, r10_bio);
1554                                 unfreeze_array(conf);
1555                         }
1556
1557                         bio = r10_bio->devs[r10_bio->read_slot].bio;
1558                         r10_bio->devs[r10_bio->read_slot].bio =
1559                                 mddev->ro ? IO_BLOCKED : NULL;
1560                         bio_put(bio);
1561                         mirror = read_balance(conf, r10_bio);
1562                         if (mirror == -1) {
1563                                 printk(KERN_ALERT "raid10: %s: unrecoverable I/O"
1564                                        " read error for block %llu\n",
1565                                        bdevname(bio->bi_bdev,b),
1566                                        (unsigned long long)r10_bio->sector);
1567                                 raid_end_bio_io(r10_bio);
1568                         } else {
1569                                 const int do_sync = bio_sync(r10_bio->master_bio);
1570                                 rdev = conf->mirrors[mirror].rdev;
1571                                 if (printk_ratelimit())
1572                                         printk(KERN_ERR "raid10: %s: redirecting sector %llu to"
1573                                                " another mirror\n",
1574                                                bdevname(rdev->bdev,b),
1575                                                (unsigned long long)r10_bio->sector);
1576                                 bio = bio_clone(r10_bio->master_bio, GFP_NOIO);
1577                                 r10_bio->devs[r10_bio->read_slot].bio = bio;
1578                                 bio->bi_sector = r10_bio->devs[r10_bio->read_slot].addr
1579                                         + rdev->data_offset;
1580                                 bio->bi_bdev = rdev->bdev;
1581                                 bio->bi_rw = READ | do_sync;
1582                                 bio->bi_private = r10_bio;
1583                                 bio->bi_end_io = raid10_end_read_request;
1584                                 unplug = 1;
1585                                 generic_make_request(bio);
1586                         }
1587                 }
1588         }
1589         spin_unlock_irqrestore(&conf->device_lock, flags);
1590         if (unplug)
1591                 unplug_slaves(mddev);
1592 }
1593
1594
1595 static int init_resync(conf_t *conf)
1596 {
1597         int buffs;
1598
1599         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1600         BUG_ON(conf->r10buf_pool);
1601         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
1602         if (!conf->r10buf_pool)
1603                 return -ENOMEM;
1604         conf->next_resync = 0;
1605         return 0;
1606 }
1607
1608 /*
1609  * perform a "sync" on one "block"
1610  *
1611  * We need to make sure that no normal I/O request - particularly write
1612  * requests - conflict with active sync requests.
1613  *
1614  * This is achieved by tracking pending requests and a 'barrier' concept
1615  * that can be installed to exclude normal IO requests.
1616  *
1617  * Resync and recovery are handled very differently.
1618  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
1619  *
1620  * For resync, we iterate over virtual addresses, read all copies,
1621  * and update if there are differences.  If only one copy is live,
1622  * skip it.
1623  * For recovery, we iterate over physical addresses, read a good
1624  * value for each non-in_sync drive, and over-write.
1625  *
1626  * So, for recovery we may have several outstanding complex requests for a
1627  * given address, one for each out-of-sync device.  We model this by allocating
1628  * a number of r10_bio structures, one for each out-of-sync device.
1629  * As we setup these structures, we collect all bio's together into a list
1630  * which we then process collectively to add pages, and then process again
1631  * to pass to generic_make_request.
1632  *
1633  * The r10_bio structures are linked using a borrowed master_bio pointer.
1634  * This link is counted in ->remaining.  When the r10_bio that points to NULL
1635  * has its remaining count decremented to 0, the whole complex operation
1636  * is complete.
1637  *
1638  */
1639
1640 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1641 {
1642         conf_t *conf = mddev_to_conf(mddev);
1643         r10bio_t *r10_bio;
1644         struct bio *biolist = NULL, *bio;
1645         sector_t max_sector, nr_sectors;
1646         int disk;
1647         int i;
1648         int max_sync;
1649         int sync_blocks;
1650
1651         sector_t sectors_skipped = 0;
1652         int chunks_skipped = 0;
1653
1654         if (!conf->r10buf_pool)
1655                 if (init_resync(conf))
1656                         return 0;
1657
1658  skipped:
1659         max_sector = mddev->size << 1;
1660         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1661                 max_sector = mddev->resync_max_sectors;
1662         if (sector_nr >= max_sector) {
1663                 /* If we aborted, we need to abort the
1664                  * sync on the 'current' bitmap chucks (there can
1665                  * be several when recovering multiple devices).
1666                  * as we may have started syncing it but not finished.
1667                  * We can find the current address in
1668                  * mddev->curr_resync, but for recovery,
1669                  * we need to convert that to several
1670                  * virtual addresses.
1671                  */
1672                 if (mddev->curr_resync < max_sector) { /* aborted */
1673                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1674                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1675                                                 &sync_blocks, 1);
1676                         else for (i=0; i<conf->raid_disks; i++) {
1677                                 sector_t sect =
1678                                         raid10_find_virt(conf, mddev->curr_resync, i);
1679                                 bitmap_end_sync(mddev->bitmap, sect,
1680                                                 &sync_blocks, 1);
1681                         }
1682                 } else /* completed sync */
1683                         conf->fullsync = 0;
1684
1685                 bitmap_close_sync(mddev->bitmap);
1686                 close_sync(conf);
1687                 *skipped = 1;
1688                 return sectors_skipped;
1689         }
1690         if (chunks_skipped >= conf->raid_disks) {
1691                 /* if there has been nothing to do on any drive,
1692                  * then there is nothing to do at all..
1693                  */
1694                 *skipped = 1;
1695                 return (max_sector - sector_nr) + sectors_skipped;
1696         }
1697
1698         /* make sure whole request will fit in a chunk - if chunks
1699          * are meaningful
1700          */
1701         if (conf->near_copies < conf->raid_disks &&
1702             max_sector > (sector_nr | conf->chunk_mask))
1703                 max_sector = (sector_nr | conf->chunk_mask) + 1;
1704         /*
1705          * If there is non-resync activity waiting for us then
1706          * put in a delay to throttle resync.
1707          */
1708         if (!go_faster && conf->nr_waiting)
1709                 msleep_interruptible(1000);
1710
1711         /* Again, very different code for resync and recovery.
1712          * Both must result in an r10bio with a list of bios that
1713          * have bi_end_io, bi_sector, bi_bdev set,
1714          * and bi_private set to the r10bio.
1715          * For recovery, we may actually create several r10bios
1716          * with 2 bios in each, that correspond to the bios in the main one.
1717          * In this case, the subordinate r10bios link back through a
1718          * borrowed master_bio pointer, and the counter in the master
1719          * includes a ref from each subordinate.
1720          */
1721         /* First, we decide what to do and set ->bi_end_io
1722          * To end_sync_read if we want to read, and
1723          * end_sync_write if we will want to write.
1724          */
1725
1726         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
1727         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1728                 /* recovery... the complicated one */
1729                 int i, j, k;
1730                 r10_bio = NULL;
1731
1732                 for (i=0 ; i<conf->raid_disks; i++)
1733                         if (conf->mirrors[i].rdev &&
1734                             !test_bit(In_sync, &conf->mirrors[i].rdev->flags)) {
1735                                 int still_degraded = 0;
1736                                 /* want to reconstruct this device */
1737                                 r10bio_t *rb2 = r10_bio;
1738                                 sector_t sect = raid10_find_virt(conf, sector_nr, i);
1739                                 int must_sync;
1740                                 /* Unless we are doing a full sync, we only need
1741                                  * to recover the block if it is set in the bitmap
1742                                  */
1743                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1744                                                               &sync_blocks, 1);
1745                                 if (sync_blocks < max_sync)
1746                                         max_sync = sync_blocks;
1747                                 if (!must_sync &&
1748                                     !conf->fullsync) {
1749                                         /* yep, skip the sync_blocks here, but don't assume
1750                                          * that there will never be anything to do here
1751                                          */
1752                                         chunks_skipped = -1;
1753                                         continue;
1754                                 }
1755
1756                                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1757                                 raise_barrier(conf, rb2 != NULL);
1758                                 atomic_set(&r10_bio->remaining, 0);
1759
1760                                 r10_bio->master_bio = (struct bio*)rb2;
1761                                 if (rb2)
1762                                         atomic_inc(&rb2->remaining);
1763                                 r10_bio->mddev = mddev;
1764                                 set_bit(R10BIO_IsRecover, &r10_bio->state);
1765                                 r10_bio->sector = sect;
1766
1767                                 raid10_find_phys(conf, r10_bio);
1768                                 /* Need to check if this section will still be
1769                                  * degraded
1770                                  */
1771                                 for (j=0; j<conf->copies;j++) {
1772                                         int d = r10_bio->devs[j].devnum;
1773                                         if (conf->mirrors[d].rdev == NULL ||
1774                                             test_bit(Faulty, &conf->mirrors[d].rdev->flags)) {
1775                                                 still_degraded = 1;
1776                                                 break;
1777                                         }
1778                                 }
1779                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1780                                                               &sync_blocks, still_degraded);
1781
1782                                 for (j=0; j<conf->copies;j++) {
1783                                         int d = r10_bio->devs[j].devnum;
1784                                         if (conf->mirrors[d].rdev &&
1785                                             test_bit(In_sync, &conf->mirrors[d].rdev->flags)) {
1786                                                 /* This is where we read from */
1787                                                 bio = r10_bio->devs[0].bio;
1788                                                 bio->bi_next = biolist;
1789                                                 biolist = bio;
1790                                                 bio->bi_private = r10_bio;
1791                                                 bio->bi_end_io = end_sync_read;
1792                                                 bio->bi_rw = READ;
1793                                                 bio->bi_sector = r10_bio->devs[j].addr +
1794                                                         conf->mirrors[d].rdev->data_offset;
1795                                                 bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1796                                                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1797                                                 atomic_inc(&r10_bio->remaining);
1798                                                 /* and we write to 'i' */
1799
1800                                                 for (k=0; k<conf->copies; k++)
1801                                                         if (r10_bio->devs[k].devnum == i)
1802                                                                 break;
1803                                                 BUG_ON(k == conf->copies);
1804                                                 bio = r10_bio->devs[1].bio;
1805                                                 bio->bi_next = biolist;
1806                                                 biolist = bio;
1807                                                 bio->bi_private = r10_bio;
1808                                                 bio->bi_end_io = end_sync_write;
1809                                                 bio->bi_rw = WRITE;
1810                                                 bio->bi_sector = r10_bio->devs[k].addr +
1811                                                         conf->mirrors[i].rdev->data_offset;
1812                                                 bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1813
1814                                                 r10_bio->devs[0].devnum = d;
1815                                                 r10_bio->devs[1].devnum = i;
1816
1817                                                 break;
1818                                         }
1819                                 }
1820                                 if (j == conf->copies) {
1821                                         /* Cannot recover, so abort the recovery */
1822                                         put_buf(r10_bio);
1823                                         r10_bio = rb2;
1824                                         if (!test_and_set_bit(MD_RECOVERY_ERR, &mddev->recovery))
1825                                                 printk(KERN_INFO "raid10: %s: insufficient working devices for recovery.\n",
1826                                                        mdname(mddev));
1827                                         break;
1828                                 }
1829                         }
1830                 if (biolist == NULL) {
1831                         while (r10_bio) {
1832                                 r10bio_t *rb2 = r10_bio;
1833                                 r10_bio = (r10bio_t*) rb2->master_bio;
1834                                 rb2->master_bio = NULL;
1835                                 put_buf(rb2);
1836                         }
1837                         goto giveup;
1838                 }
1839         } else {
1840                 /* resync. Schedule a read for every block at this virt offset */
1841                 int count = 0;
1842
1843                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1844                                        &sync_blocks, mddev->degraded) &&
1845                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1846                         /* We can skip this block */
1847                         *skipped = 1;
1848                         return sync_blocks + sectors_skipped;
1849                 }
1850                 if (sync_blocks < max_sync)
1851                         max_sync = sync_blocks;
1852                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1853
1854                 r10_bio->mddev = mddev;
1855                 atomic_set(&r10_bio->remaining, 0);
1856                 raise_barrier(conf, 0);
1857                 conf->next_resync = sector_nr;
1858
1859                 r10_bio->master_bio = NULL;
1860                 r10_bio->sector = sector_nr;
1861                 set_bit(R10BIO_IsSync, &r10_bio->state);
1862                 raid10_find_phys(conf, r10_bio);
1863                 r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
1864
1865                 for (i=0; i<conf->copies; i++) {
1866                         int d = r10_bio->devs[i].devnum;
1867                         bio = r10_bio->devs[i].bio;
1868                         bio->bi_end_io = NULL;
1869                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
1870                         if (conf->mirrors[d].rdev == NULL ||
1871                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
1872                                 continue;
1873                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1874                         atomic_inc(&r10_bio->remaining);
1875                         bio->bi_next = biolist;
1876                         biolist = bio;
1877                         bio->bi_private = r10_bio;
1878                         bio->bi_end_io = end_sync_read;
1879                         bio->bi_rw = READ;
1880                         bio->bi_sector = r10_bio->devs[i].addr +
1881                                 conf->mirrors[d].rdev->data_offset;
1882                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1883                         count++;
1884                 }
1885
1886                 if (count < 2) {
1887                         for (i=0; i<conf->copies; i++) {
1888                                 int d = r10_bio->devs[i].devnum;
1889                                 if (r10_bio->devs[i].bio->bi_end_io)
1890                                         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1891                         }
1892                         put_buf(r10_bio);
1893                         biolist = NULL;
1894                         goto giveup;
1895                 }
1896         }
1897
1898         for (bio = biolist; bio ; bio=bio->bi_next) {
1899
1900                 bio->bi_flags &= ~(BIO_POOL_MASK - 1);
1901                 if (bio->bi_end_io)
1902                         bio->bi_flags |= 1 << BIO_UPTODATE;
1903                 bio->bi_vcnt = 0;
1904                 bio->bi_idx = 0;
1905                 bio->bi_phys_segments = 0;
1906                 bio->bi_hw_segments = 0;
1907                 bio->bi_size = 0;
1908         }
1909
1910         nr_sectors = 0;
1911         if (sector_nr + max_sync < max_sector)
1912                 max_sector = sector_nr + max_sync;
1913         do {
1914                 struct page *page;
1915                 int len = PAGE_SIZE;
1916                 disk = 0;
1917                 if (sector_nr + (len>>9) > max_sector)
1918                         len = (max_sector - sector_nr) << 9;
1919                 if (len == 0)
1920                         break;
1921                 for (bio= biolist ; bio ; bio=bio->bi_next) {
1922                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1923                         if (bio_add_page(bio, page, len, 0) == 0) {
1924                                 /* stop here */
1925                                 struct bio *bio2;
1926                                 bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1927                                 for (bio2 = biolist; bio2 && bio2 != bio; bio2 = bio2->bi_next) {
1928                                         /* remove last page from this bio */
1929                                         bio2->bi_vcnt--;
1930                                         bio2->bi_size -= len;
1931                                         bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
1932                                 }
1933                                 goto bio_full;
1934                         }
1935                         disk = i;
1936                 }
1937                 nr_sectors += len>>9;
1938                 sector_nr += len>>9;
1939         } while (biolist->bi_vcnt < RESYNC_PAGES);
1940  bio_full:
1941         r10_bio->sectors = nr_sectors;
1942
1943         while (biolist) {
1944                 bio = biolist;
1945                 biolist = biolist->bi_next;
1946
1947                 bio->bi_next = NULL;
1948                 r10_bio = bio->bi_private;
1949                 r10_bio->sectors = nr_sectors;
1950
1951                 if (bio->bi_end_io == end_sync_read) {
1952                         md_sync_acct(bio->bi_bdev, nr_sectors);
1953                         generic_make_request(bio);
1954                 }
1955         }
1956
1957         if (sectors_skipped)
1958                 /* pretend they weren't skipped, it makes
1959                  * no important difference in this case
1960                  */
1961                 md_done_sync(mddev, sectors_skipped, 1);
1962
1963         return sectors_skipped + nr_sectors;
1964  giveup:
1965         /* There is nowhere to write, so all non-sync
1966          * drives must be failed, so try the next chunk...
1967          */
1968         {
1969         sector_t sec = max_sector - sector_nr;
1970         sectors_skipped += sec;
1971         chunks_skipped ++;
1972         sector_nr = max_sector;
1973         goto skipped;
1974         }
1975 }
1976
1977 static int run(mddev_t *mddev)
1978 {
1979         conf_t *conf;
1980         int i, disk_idx;
1981         mirror_info_t *disk;
1982         mdk_rdev_t *rdev;
1983         struct list_head *tmp;
1984         int nc, fc, fo;
1985         sector_t stride, size;
1986
1987         if (mddev->chunk_size == 0) {
1988                 printk(KERN_ERR "md/raid10: non-zero chunk size required.\n");
1989                 return -EINVAL;
1990         }
1991
1992         nc = mddev->layout & 255;
1993         fc = (mddev->layout >> 8) & 255;
1994         fo = mddev->layout & (1<<16);
1995         if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
1996             (mddev->layout >> 17)) {
1997                 printk(KERN_ERR "raid10: %s: unsupported raid10 layout: 0x%8x\n",
1998                        mdname(mddev), mddev->layout);
1999                 goto out;
2000         }
2001         /*
2002          * copy the already verified devices into our private RAID10
2003          * bookkeeping area. [whatever we allocate in run(),
2004          * should be freed in stop()]
2005          */
2006         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
2007         mddev->private = conf;
2008         if (!conf) {
2009                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2010                         mdname(mddev));
2011                 goto out;
2012         }
2013         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
2014                                  GFP_KERNEL);
2015         if (!conf->mirrors) {
2016                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2017                        mdname(mddev));
2018                 goto out_free_conf;
2019         }
2020
2021         conf->tmppage = alloc_page(GFP_KERNEL);
2022         if (!conf->tmppage)
2023                 goto out_free_conf;
2024
2025         conf->mddev = mddev;
2026         conf->raid_disks = mddev->raid_disks;
2027         conf->near_copies = nc;
2028         conf->far_copies = fc;
2029         conf->copies = nc*fc;
2030         conf->far_offset = fo;
2031         conf->chunk_mask = (sector_t)(mddev->chunk_size>>9)-1;
2032         conf->chunk_shift = ffz(~mddev->chunk_size) - 9;
2033         size = mddev->size >> (conf->chunk_shift-1);
2034         sector_div(size, fc);
2035         size = size * conf->raid_disks;
2036         sector_div(size, nc);
2037         /* 'size' is now the number of chunks in the array */
2038         /* calculate "used chunks per device" in 'stride' */
2039         stride = size * conf->copies;
2040
2041         /* We need to round up when dividing by raid_disks to
2042          * get the stride size.
2043          */
2044         stride += conf->raid_disks - 1;
2045         sector_div(stride, conf->raid_disks);
2046         mddev->size = stride  << (conf->chunk_shift-1);
2047
2048         if (fo)
2049                 stride = 1;
2050         else
2051                 sector_div(stride, fc);
2052         conf->stride = stride << conf->chunk_shift;
2053
2054         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
2055                                                 r10bio_pool_free, conf);
2056         if (!conf->r10bio_pool) {
2057                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2058                         mdname(mddev));
2059                 goto out_free_conf;
2060         }
2061
2062         ITERATE_RDEV(mddev, rdev, tmp) {
2063                 disk_idx = rdev->raid_disk;
2064                 if (disk_idx >= mddev->raid_disks
2065                     || disk_idx < 0)
2066                         continue;
2067                 disk = conf->mirrors + disk_idx;
2068
2069                 disk->rdev = rdev;
2070
2071                 blk_queue_stack_limits(mddev->queue,
2072                                        rdev->bdev->bd_disk->queue);
2073                 /* as we don't honour merge_bvec_fn, we must never risk
2074                  * violating it, so limit ->max_sector to one PAGE, as
2075                  * a one page request is never in violation.
2076                  */
2077                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
2078                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
2079                         mddev->queue->max_sectors = (PAGE_SIZE>>9);
2080
2081                 disk->head_position = 0;
2082         }
2083         spin_lock_init(&conf->device_lock);
2084         INIT_LIST_HEAD(&conf->retry_list);
2085
2086         spin_lock_init(&conf->resync_lock);
2087         init_waitqueue_head(&conf->wait_barrier);
2088
2089         /* need to check that every block has at least one working mirror */
2090         if (!enough(conf)) {
2091                 printk(KERN_ERR "raid10: not enough operational mirrors for %s\n",
2092                        mdname(mddev));
2093                 goto out_free_conf;
2094         }
2095
2096         mddev->degraded = 0;
2097         for (i = 0; i < conf->raid_disks; i++) {
2098
2099                 disk = conf->mirrors + i;
2100
2101                 if (!disk->rdev ||
2102                     !test_bit(In_sync, &disk->rdev->flags)) {
2103                         disk->head_position = 0;
2104                         mddev->degraded++;
2105                 }
2106         }
2107
2108
2109         mddev->thread = md_register_thread(raid10d, mddev, "%s_raid10");
2110         if (!mddev->thread) {
2111                 printk(KERN_ERR
2112                        "raid10: couldn't allocate thread for %s\n",
2113                        mdname(mddev));
2114                 goto out_free_conf;
2115         }
2116
2117         printk(KERN_INFO
2118                 "raid10: raid set %s active with %d out of %d devices\n",
2119                 mdname(mddev), mddev->raid_disks - mddev->degraded,
2120                 mddev->raid_disks);
2121         /*
2122          * Ok, everything is just fine now
2123          */
2124         mddev->array_size = size << (conf->chunk_shift-1);
2125         mddev->resync_max_sectors = size << conf->chunk_shift;
2126
2127         mddev->queue->unplug_fn = raid10_unplug;
2128         mddev->queue->issue_flush_fn = raid10_issue_flush;
2129         mddev->queue->backing_dev_info.congested_fn = raid10_congested;
2130         mddev->queue->backing_dev_info.congested_data = mddev;
2131
2132         /* Calculate max read-ahead size.
2133          * We need to readahead at least twice a whole stripe....
2134          * maybe...
2135          */
2136         {
2137                 int stripe = conf->raid_disks * (mddev->chunk_size / PAGE_SIZE);
2138                 stripe /= conf->near_copies;
2139                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
2140                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
2141         }
2142
2143         if (conf->near_copies < mddev->raid_disks)
2144                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
2145         return 0;
2146
2147 out_free_conf:
2148         if (conf->r10bio_pool)
2149                 mempool_destroy(conf->r10bio_pool);
2150         safe_put_page(conf->tmppage);
2151         kfree(conf->mirrors);
2152         kfree(conf);
2153         mddev->private = NULL;
2154 out:
2155         return -EIO;
2156 }
2157
2158 static int stop(mddev_t *mddev)
2159 {
2160         conf_t *conf = mddev_to_conf(mddev);
2161
2162         md_unregister_thread(mddev->thread);
2163         mddev->thread = NULL;
2164         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2165         if (conf->r10bio_pool)
2166                 mempool_destroy(conf->r10bio_pool);
2167         kfree(conf->mirrors);
2168         kfree(conf);
2169         mddev->private = NULL;
2170         return 0;
2171 }
2172
2173 static void raid10_quiesce(mddev_t *mddev, int state)
2174 {
2175         conf_t *conf = mddev_to_conf(mddev);
2176
2177         switch(state) {
2178         case 1:
2179                 raise_barrier(conf, 0);
2180                 break;
2181         case 0:
2182                 lower_barrier(conf);
2183                 break;
2184         }
2185         if (mddev->thread) {
2186                 if (mddev->bitmap)
2187                         mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
2188                 else
2189                         mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
2190                 md_wakeup_thread(mddev->thread);
2191         }
2192 }
2193
2194 static struct mdk_personality raid10_personality =
2195 {
2196         .name           = "raid10",
2197         .level          = 10,
2198         .owner          = THIS_MODULE,
2199         .make_request   = make_request,
2200         .run            = run,
2201         .stop           = stop,
2202         .status         = status,
2203         .error_handler  = error,
2204         .hot_add_disk   = raid10_add_disk,
2205         .hot_remove_disk= raid10_remove_disk,
2206         .spare_active   = raid10_spare_active,
2207         .sync_request   = sync_request,
2208         .quiesce        = raid10_quiesce,
2209 };
2210
2211 static int __init raid_init(void)
2212 {
2213         return register_md_personality(&raid10_personality);
2214 }
2215
2216 static void raid_exit(void)
2217 {
2218         unregister_md_personality(&raid10_personality);
2219 }
2220
2221 module_init(raid_init);
2222 module_exit(raid_exit);
2223 MODULE_LICENSE("GPL");
2224 MODULE_ALIAS("md-personality-9"); /* RAID10 */
2225 MODULE_ALIAS("md-raid10");
2226 MODULE_ALIAS("md-level-10");