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   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(request_queue_t *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                         request_queue_t *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(request_queue_t *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(request_queue_t *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                         request_queue_t *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                         request_queue_t *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(request_queue_t *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         struct bio_list bl;
 786         unsigned long flags;
 787
 788         if (unlikely(bio_barrier(bio))) {
 789                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
 790                 return 0;
 791         }
 792
 793         /* If this request crosses a chunk boundary, we need to
 794          * split it.  This will only happen for 1 PAGE (or less) requests.
 795          */
 796         if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
 797                       > chunk_sects &&
 798                     conf->near_copies < conf->raid_disks)) {
 799                 struct bio_pair *bp;
 800                 /* Sanity check -- queue functions should prevent this happening */
 801                 if (bio->bi_vcnt != 1 ||
 802                     bio->bi_idx != 0)
 803                         goto bad_map;
 804                 /* This is a one page bio that upper layers
 805                  * refuse to split for us, so we need to split it.
 806                  */
 807                 bp = bio_split(bio, bio_split_pool,
 808                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
 809                 if (make_request(q, &bp->bio1))
 810                         generic_make_request(&bp->bio1);
 811                 if (make_request(q, &bp->bio2))
 812                         generic_make_request(&bp->bio2);
 813
 814                 bio_pair_release(bp);
 815                 return 0;
 816         bad_map:
 817                 printk("raid10_make_request bug: can't convert block across chunks"
 818                        " or bigger than %dk %llu %d\n", chunk_sects/2,
 819                        (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 820
 821                 bio_io_error(bio, bio->bi_size);
 822                 return 0;
 823         }
 824
 825         md_write_start(mddev, bio);
 826
 827         /*
 828          * Register the new request and wait if the reconstruction
 829          * thread has put up a bar for new requests.
 830          * Continue immediately if no resync is active currently.
 831          */
 832         wait_barrier(conf);
 833
 834         disk_stat_inc(mddev->gendisk, ios[rw]);
 835         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
 836
 837         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
 838
 839         r10_bio->master_bio = bio;
 840         r10_bio->sectors = bio->bi_size >> 9;
 841
 842         r10_bio->mddev = mddev;
 843         r10_bio->sector = bio->bi_sector;
 844         r10_bio->state = 0;
 845
 846         if (rw == READ) {
 847                 /*
 848                  * read balancing logic:
 849                  */
 850                 int disk = read_balance(conf, r10_bio);
 851                 int slot = r10_bio->read_slot;
 852                 if (disk < 0) {
 853                         raid_end_bio_io(r10_bio);
 854                         return 0;
 855                 }
 856                 mirror = conf->mirrors + disk;
 857
 858                 read_bio = bio_clone(bio, GFP_NOIO);
 859
 860                 r10_bio->devs[slot].bio = read_bio;
 861
 862                 read_bio->bi_sector = r10_bio->devs[slot].addr +
 863                         mirror->rdev->data_offset;
 864                 read_bio->bi_bdev = mirror->rdev->bdev;
 865                 read_bio->bi_end_io = raid10_end_read_request;
 866                 read_bio->bi_rw = READ;
 867                 read_bio->bi_private = r10_bio;
 868
 869                 generic_make_request(read_bio);
 870                 return 0;
 871         }
 872
 873         /*
 874          * WRITE:
 875          */
 876         /* first select target devices under spinlock and
 877          * inc refcount on their rdev.  Record them by setting
 878          * bios[x] to bio
 879          */
 880         raid10_find_phys(conf, r10_bio);
 881         rcu_read_lock();
 882         for (i = 0;  i < conf->copies; i++) {
 883                 int d = r10_bio->devs[i].devnum;
 884                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
 885                 if (rdev &&
 886                     !test_bit(Faulty, &rdev->flags)) {
 887                         atomic_inc(&rdev->nr_pending);
 888                         r10_bio->devs[i].bio = bio;
 889                 } else {
 890                         r10_bio->devs[i].bio = NULL;
 891                         set_bit(R10BIO_Degraded, &r10_bio->state);
 892                 }
 893         }
 894         rcu_read_unlock();
 895
 896         atomic_set(&r10_bio->remaining, 0);
 897
 898         bio_list_init(&bl);
 899         for (i = 0; i < conf->copies; i++) {
 900                 struct bio *mbio;
 901                 int d = r10_bio->devs[i].devnum;
 902                 if (!r10_bio->devs[i].bio)
 903                         continue;
 904
 905                 mbio = bio_clone(bio, GFP_NOIO);
 906                 r10_bio->devs[i].bio = mbio;
 907
 908                 mbio->bi_sector = r10_bio->devs[i].addr+
 909                         conf->mirrors[d].rdev->data_offset;
 910                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
 911                 mbio->bi_end_io = raid10_end_write_request;
 912                 mbio->bi_rw = WRITE;
 913                 mbio->bi_private = r10_bio;
 914
 915                 atomic_inc(&r10_bio->remaining);
 916                 bio_list_add(&bl, mbio);
 917         }
 918
 919         bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
 920         spin_lock_irqsave(&conf->device_lock, flags);
 921         bio_list_merge(&conf->pending_bio_list, &bl);
 922         blk_plug_device(mddev->queue);
 923         spin_unlock_irqrestore(&conf->device_lock, flags);
 924
 925         return 0;
 926 }
 927
 928 static void status(struct seq_file *seq, mddev_t *mddev)
 929 {
 930         conf_t *conf = mddev_to_conf(mddev);
 931         int i;
 932
 933         if (conf->near_copies < conf->raid_disks)
 934                 seq_printf(seq, " %dK chunks", mddev->chunk_size/1024);
 935         if (conf->near_copies > 1)
 936                 seq_printf(seq, " %d near-copies", conf->near_copies);
 937         if (conf->far_copies > 1) {
 938                 if (conf->far_offset)
 939                         seq_printf(seq, " %d offset-copies", conf->far_copies);
 940                 else
 941                         seq_printf(seq, " %d far-copies", conf->far_copies);
 942         }
 943         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 944                                         conf->raid_disks - mddev->degraded);
 945         for (i = 0; i < conf->raid_disks; i++)
 946                 seq_printf(seq, "%s",
 947                               conf->mirrors[i].rdev &&
 948                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
 949         seq_printf(seq, "]");
 950 }
 951
 952 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 953 {
 954         char b[BDEVNAME_SIZE];
 955         conf_t *conf = mddev_to_conf(mddev);
 956
 957         /*
 958          * If it is not operational, then we have already marked it as dead
 959          * else if it is the last working disks, ignore the error, let the
 960          * next level up know.
 961          * else mark the drive as failed
 962          */
 963         if (test_bit(In_sync, &rdev->flags)
 964             && conf->raid_disks-mddev->degraded == 1)
 965                 /*
 966                  * Don't fail the drive, just return an IO error.
 967                  * The test should really be more sophisticated than
 968                  * "working_disks == 1", but it isn't critical, and
 969                  * can wait until we do more sophisticated "is the drive
 970                  * really dead" tests...
 971                  */
 972                 return;
 973         if (test_and_clear_bit(In_sync, &rdev->flags)) {
 974                 unsigned long flags;
 975                 spin_lock_irqsave(&conf->device_lock, flags);
 976                 mddev->degraded++;
 977                 spin_unlock_irqrestore(&conf->device_lock, flags);
 978                 /*
 979                  * if recovery is running, make sure it aborts.
 980                  */
 981                 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 982         }
 983         set_bit(Faulty, &rdev->flags);
 984         set_bit(MD_CHANGE_DEVS, &mddev->flags);
 985         printk(KERN_ALERT "raid10: Disk failure on %s, disabling device. \n"
 986                 "       Operation continuing on %d devices\n",
 987                 bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
 988 }
 989
 990 static void print_conf(conf_t *conf)
 991 {
 992         int i;
 993         mirror_info_t *tmp;
 994
 995         printk("RAID10 conf printout:\n");
 996         if (!conf) {
 997                 printk("(!conf)\n");
 998                 return;
 999         }
1000         printk(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1001                 conf->raid_disks);
1002
1003         for (i = 0; i < conf->raid_disks; i++) {
1004                 char b[BDEVNAME_SIZE];
1005                 tmp = conf->mirrors + i;
1006                 if (tmp->rdev)
1007                         printk(" disk %d, wo:%d, o:%d, dev:%s\n",
1008                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1009                                 !test_bit(Faulty, &tmp->rdev->flags),
1010                                 bdevname(tmp->rdev->bdev,b));
1011         }
1012 }
1013
1014 static void close_sync(conf_t *conf)
1015 {
1016         wait_barrier(conf);
1017         allow_barrier(conf);
1018
1019         mempool_destroy(conf->r10buf_pool);
1020         conf->r10buf_pool = NULL;
1021 }
1022
1023 /* check if there are enough drives for
1024  * every block to appear on atleast one
1025  */
1026 static int enough(conf_t *conf)
1027 {
1028         int first = 0;
1029
1030         do {
1031                 int n = conf->copies;
1032                 int cnt = 0;
1033                 while (n--) {
1034                         if (conf->mirrors[first].rdev)
1035                                 cnt++;
1036                         first = (first+1) % conf->raid_disks;
1037                 }
1038                 if (cnt == 0)
1039                         return 0;
1040         } while (first != 0);
1041         return 1;
1042 }
1043
1044 static int raid10_spare_active(mddev_t *mddev)
1045 {
1046         int i;
1047         conf_t *conf = mddev->private;
1048         mirror_info_t *tmp;
1049
1050         /*
1051          * Find all non-in_sync disks within the RAID10 configuration
1052          * and mark them in_sync
1053          */
1054         for (i = 0; i < conf->raid_disks; i++) {
1055                 tmp = conf->mirrors + i;
1056                 if (tmp->rdev
1057                     && !test_bit(Faulty, &tmp->rdev->flags)
1058                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1059                         unsigned long flags;
1060                         spin_lock_irqsave(&conf->device_lock, flags);
1061                         mddev->degraded--;
1062                         spin_unlock_irqrestore(&conf->device_lock, flags);
1063                 }
1064         }
1065
1066         print_conf(conf);
1067         return 0;
1068 }
1069
1070
1071 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1072 {
1073         conf_t *conf = mddev->private;
1074         int found = 0;
1075         int mirror;
1076         mirror_info_t *p;
1077
1078         if (mddev->recovery_cp < MaxSector)
1079                 /* only hot-add to in-sync arrays, as recovery is
1080                  * very different from resync
1081                  */
1082                 return 0;
1083         if (!enough(conf))
1084                 return 0;
1085
1086         if (rdev->saved_raid_disk >= 0 &&
1087             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1088                 mirror = rdev->saved_raid_disk;
1089         else
1090                 mirror = 0;
1091         for ( ; mirror < mddev->raid_disks; mirror++)
1092                 if ( !(p=conf->mirrors+mirror)->rdev) {
1093
1094                         blk_queue_stack_limits(mddev->queue,
1095                                                rdev->bdev->bd_disk->queue);
1096                         /* as we don't honour merge_bvec_fn, we must never risk
1097                          * violating it, so limit ->max_sector to one PAGE, as
1098                          * a one page request is never in violation.
1099                          */
1100                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1101                             mddev->queue->max_sectors > (PAGE_SIZE>>9))
1102                                 mddev->queue->max_sectors = (PAGE_SIZE>>9);
1103
1104                         p->head_position = 0;
1105                         rdev->raid_disk = mirror;
1106                         found = 1;
1107                         if (rdev->saved_raid_disk != mirror)
1108                                 conf->fullsync = 1;
1109                         rcu_assign_pointer(p->rdev, rdev);
1110                         break;
1111                 }
1112
1113         print_conf(conf);
1114         return found;
1115 }
1116
1117 static int raid10_remove_disk(mddev_t *mddev, int number)
1118 {
1119         conf_t *conf = mddev->private;
1120         int err = 0;
1121         mdk_rdev_t *rdev;
1122         mirror_info_t *p = conf->mirrors+ number;
1123
1124         print_conf(conf);
1125         rdev = p->rdev;
1126         if (rdev) {
1127                 if (test_bit(In_sync, &rdev->flags) ||
1128                     atomic_read(&rdev->nr_pending)) {
1129                         err = -EBUSY;
1130                         goto abort;
1131                 }
1132                 p->rdev = NULL;
1133                 synchronize_rcu();
1134                 if (atomic_read(&rdev->nr_pending)) {
1135                         /* lost the race, try later */
1136                         err = -EBUSY;
1137                         p->rdev = rdev;
1138                 }
1139         }
1140 abort:
1141
1142         print_conf(conf);
1143         return err;
1144 }
1145
1146
1147 static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
1148 {
1149         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
1150         conf_t *conf = mddev_to_conf(r10_bio->mddev);
1151         int i,d;
1152
1153         if (bio->bi_size)
1154                 return 1;
1155
1156         for (i=0; i<conf->copies; i++)
1157                 if (r10_bio->devs[i].bio == bio)
1158                         break;
1159         BUG_ON(i == conf->copies);
1160         update_head_pos(i, r10_bio);
1161         d = r10_bio->devs[i].devnum;
1162
1163         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1164                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1165         else {
1166                 atomic_add(r10_bio->sectors,
1167                            &conf->mirrors[d].rdev->corrected_errors);
1168                 if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
1169                         md_error(r10_bio->mddev,
1170                                  conf->mirrors[d].rdev);
1171         }
1172
1173         /* for reconstruct, we always reschedule after a read.
1174          * for resync, only after all reads
1175          */
1176         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1177             atomic_dec_and_test(&r10_bio->remaining)) {
1178                 /* we have read all the blocks,
1179                  * do the comparison in process context in raid10d
1180                  */
1181                 reschedule_retry(r10_bio);
1182         }
1183         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1184         return 0;
1185 }
1186
1187 static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error)
1188 {
1189         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1190         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
1191         mddev_t *mddev = r10_bio->mddev;
1192         conf_t *conf = mddev_to_conf(mddev);
1193         int i,d;
1194
1195         if (bio->bi_size)
1196                 return 1;
1197
1198         for (i = 0; i < conf->copies; i++)
1199                 if (r10_bio->devs[i].bio == bio)
1200                         break;
1201         d = r10_bio->devs[i].devnum;
1202
1203         if (!uptodate)
1204                 md_error(mddev, conf->mirrors[d].rdev);
1205         update_head_pos(i, r10_bio);
1206
1207         while (atomic_dec_and_test(&r10_bio->remaining)) {
1208                 if (r10_bio->master_bio == NULL) {
1209                         /* the primary of several recovery bios */
1210                         md_done_sync(mddev, r10_bio->sectors, 1);
1211                         put_buf(r10_bio);
1212                         break;
1213                 } else {
1214                         r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
1215                         put_buf(r10_bio);
1216                         r10_bio = r10_bio2;
1217                 }
1218         }
1219         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1220         return 0;
1221 }
1222
1223 /*
1224  * Note: sync and recover and handled very differently for raid10
1225  * This code is for resync.
1226  * For resync, we read through virtual addresses and read all blocks.
1227  * If there is any error, we schedule a write.  The lowest numbered
1228  * drive is authoritative.
1229  * However requests come for physical address, so we need to map.
1230  * For every physical address there are raid_disks/copies virtual addresses,
1231  * which is always are least one, but is not necessarly an integer.
1232  * This means that a physical address can span multiple chunks, so we may
1233  * have to submit multiple io requests for a single sync request.
1234  */
1235 /*
1236  * We check if all blocks are in-sync and only write to blocks that
1237  * aren't in sync
1238  */
1239 static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1240 {
1241         conf_t *conf = mddev_to_conf(mddev);
1242         int i, first;
1243         struct bio *tbio, *fbio;
1244
1245         atomic_set(&r10_bio->remaining, 1);
1246
1247         /* find the first device with a block */
1248         for (i=0; i<conf->copies; i++)
1249                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1250                         break;
1251
1252         if (i == conf->copies)
1253                 goto done;
1254
1255         first = i;
1256         fbio = r10_bio->devs[i].bio;
1257
1258         /* now find blocks with errors */
1259         for (i=0 ; i < conf->copies ; i++) {
1260                 int  j, d;
1261                 int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
1262
1263                 tbio = r10_bio->devs[i].bio;
1264
1265                 if (tbio->bi_end_io != end_sync_read)
1266                         continue;
1267                 if (i == first)
1268                         continue;
1269                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1270                         /* We know that the bi_io_vec layout is the same for
1271                          * both 'first' and 'i', so we just compare them.
1272                          * All vec entries are PAGE_SIZE;
1273                          */
1274                         for (j = 0; j < vcnt; j++)
1275                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1276                                            page_address(tbio->bi_io_vec[j].bv_page),
1277                                            PAGE_SIZE))
1278                                         break;
1279                         if (j == vcnt)
1280                                 continue;
1281                         mddev->resync_mismatches += r10_bio->sectors;
1282                 }
1283                 if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1284                         /* Don't fix anything. */
1285                         continue;
1286                 /* Ok, we need to write this bio
1287                  * First we need to fixup bv_offset, bv_len and
1288                  * bi_vecs, as the read request might have corrupted these
1289                  */
1290                 tbio->bi_vcnt = vcnt;
1291                 tbio->bi_size = r10_bio->sectors << 9;
1292                 tbio->bi_idx = 0;
1293                 tbio->bi_phys_segments = 0;
1294                 tbio->bi_hw_segments = 0;
1295                 tbio->bi_hw_front_size = 0;
1296                 tbio->bi_hw_back_size = 0;
1297                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1298                 tbio->bi_flags |= 1 << BIO_UPTODATE;
1299                 tbio->bi_next = NULL;
1300                 tbio->bi_rw = WRITE;
1301                 tbio->bi_private = r10_bio;
1302                 tbio->bi_sector = r10_bio->devs[i].addr;
1303
1304                 for (j=0; j < vcnt ; j++) {
1305                         tbio->bi_io_vec[j].bv_offset = 0;
1306                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1307
1308                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1309                                page_address(fbio->bi_io_vec[j].bv_page),
1310                                PAGE_SIZE);
1311                 }
1312                 tbio->bi_end_io = end_sync_write;
1313
1314                 d = r10_bio->devs[i].devnum;
1315                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1316                 atomic_inc(&r10_bio->remaining);
1317                 md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1318
1319                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1320                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1321                 generic_make_request(tbio);
1322         }
1323
1324 done:
1325         if (atomic_dec_and_test(&r10_bio->remaining)) {
1326                 md_done_sync(mddev, r10_bio->sectors, 1);
1327                 put_buf(r10_bio);
1328         }
1329 }
1330
1331 /*
1332  * Now for the recovery code.
1333  * Recovery happens across physical sectors.
1334  * We recover all non-is_sync drives by finding the virtual address of
1335  * each, and then choose a working drive that also has that virt address.
1336  * There is a separate r10_bio for each non-in_sync drive.
1337  * Only the first two slots are in use. The first for reading,
1338  * The second for writing.
1339  *
1340  */
1341
1342 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1343 {
1344         conf_t *conf = mddev_to_conf(mddev);
1345         int i, d;
1346         struct bio *bio, *wbio;
1347
1348
1349         /* move the pages across to the second bio
1350          * and submit the write request
1351          */
1352         bio = r10_bio->devs[0].bio;
1353         wbio = r10_bio->devs[1].bio;
1354         for (i=0; i < wbio->bi_vcnt; i++) {
1355                 struct page *p = bio->bi_io_vec[i].bv_page;
1356                 bio->bi_io_vec[i].bv_page = wbio->bi_io_vec[i].bv_page;
1357                 wbio->bi_io_vec[i].bv_page = p;
1358         }
1359         d = r10_bio->devs[1].devnum;
1360
1361         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1362         md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
1363         if (test_bit(R10BIO_Uptodate, &r10_bio->state))
1364                 generic_make_request(wbio);
1365         else
1366                 bio_endio(wbio, wbio->bi_size, -EIO);
1367 }
1368
1369
1370 /*
1371  * This is a kernel thread which:
1372  *
1373  *      1.      Retries failed read operations on working mirrors.
1374  *      2.      Updates the raid superblock when problems encounter.
1375  *      3.      Performs writes following reads for array synchronising.
1376  */
1377
1378 static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
1379 {
1380         int sect = 0; /* Offset from r10_bio->sector */
1381         int sectors = r10_bio->sectors;
1382         mdk_rdev_t*rdev;
1383         while(sectors) {
1384                 int s = sectors;
1385                 int sl = r10_bio->read_slot;
1386                 int success = 0;
1387                 int start;
1388
1389                 if (s > (PAGE_SIZE>>9))
1390                         s = PAGE_SIZE >> 9;
1391
1392                 rcu_read_lock();
1393                 do {
1394                         int d = r10_bio->devs[sl].devnum;
1395                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1396                         if (rdev &&
1397                             test_bit(In_sync, &rdev->flags)) {
1398                                 atomic_inc(&rdev->nr_pending);
1399                                 rcu_read_unlock();
1400                                 success = sync_page_io(rdev->bdev,
1401                                                        r10_bio->devs[sl].addr +
1402                                                        sect + rdev->data_offset,
1403                                                        s<<9,
1404                                                        conf->tmppage, READ);
1405                                 rdev_dec_pending(rdev, mddev);
1406                                 rcu_read_lock();
1407                                 if (success)
1408                                         break;
1409                         }
1410                         sl++;
1411                         if (sl == conf->copies)
1412                                 sl = 0;
1413                 } while (!success && sl != r10_bio->read_slot);
1414                 rcu_read_unlock();
1415
1416                 if (!success) {
1417                         /* Cannot read from anywhere -- bye bye array */
1418                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
1419                         md_error(mddev, conf->mirrors[dn].rdev);
1420                         break;
1421                 }
1422
1423                 start = sl;
1424                 /* write it back and re-read */
1425                 rcu_read_lock();
1426                 while (sl != r10_bio->read_slot) {
1427                         int d;
1428                         if (sl==0)
1429                                 sl = conf->copies;
1430                         sl--;
1431                         d = r10_bio->devs[sl].devnum;
1432                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1433                         if (rdev &&
1434                             test_bit(In_sync, &rdev->flags)) {
1435                                 atomic_inc(&rdev->nr_pending);
1436                                 rcu_read_unlock();
1437                                 atomic_add(s, &rdev->corrected_errors);
1438                                 if (sync_page_io(rdev->bdev,
1439                                                  r10_bio->devs[sl].addr +
1440                                                  sect + rdev->data_offset,
1441                                                  s<<9, conf->tmppage, WRITE)
1442                                     == 0)
1443                                         /* Well, this device is dead */
1444                                         md_error(mddev, rdev);
1445                                 rdev_dec_pending(rdev, mddev);
1446                                 rcu_read_lock();
1447                         }
1448                 }
1449                 sl = start;
1450                 while (sl != r10_bio->read_slot) {
1451                         int d;
1452                         if (sl==0)
1453                                 sl = conf->copies;
1454                         sl--;
1455                         d = r10_bio->devs[sl].devnum;
1456                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1457                         if (rdev &&
1458                             test_bit(In_sync, &rdev->flags)) {
1459                                 char b[BDEVNAME_SIZE];
1460                                 atomic_inc(&rdev->nr_pending);
1461                                 rcu_read_unlock();
1462                                 if (sync_page_io(rdev->bdev,
1463                                                  r10_bio->devs[sl].addr +
1464                                                  sect + rdev->data_offset,
1465                                                  s<<9, conf->tmppage, READ) == 0)
1466                                         /* Well, this device is dead */
1467                                         md_error(mddev, rdev);
1468                                 else
1469                                         printk(KERN_INFO
1470                                                "raid10:%s: read error corrected"
1471                                                " (%d sectors at %llu on %s)\n",
1472                                                mdname(mddev), s,
1473                                                (unsigned long long)sect+
1474                                                     rdev->data_offset,
1475                                                bdevname(rdev->bdev, b));
1476
1477                                 rdev_dec_pending(rdev, mddev);
1478                                 rcu_read_lock();
1479                         }
1480                 }
1481                 rcu_read_unlock();
1482
1483                 sectors -= s;
1484                 sect += s;
1485         }
1486 }
1487
1488 static void raid10d(mddev_t *mddev)
1489 {
1490         r10bio_t *r10_bio;
1491         struct bio *bio;
1492         unsigned long flags;
1493         conf_t *conf = mddev_to_conf(mddev);
1494         struct list_head *head = &conf->retry_list;
1495         int unplug=0;
1496         mdk_rdev_t *rdev;
1497
1498         md_check_recovery(mddev);
1499
1500         for (;;) {
1501                 char b[BDEVNAME_SIZE];
1502                 spin_lock_irqsave(&conf->device_lock, flags);
1503
1504                 if (conf->pending_bio_list.head) {
1505                         bio = bio_list_get(&conf->pending_bio_list);
1506                         blk_remove_plug(mddev->queue);
1507                         spin_unlock_irqrestore(&conf->device_lock, flags);
1508                         /* flush any pending bitmap writes to disk before proceeding w/ I/O */
1509                         if (bitmap_unplug(mddev->bitmap) != 0)
1510                                 printk("%s: bitmap file write failed!\n", mdname(mddev));
1511
1512                         while (bio) { /* submit pending writes */
1513                                 struct bio *next = bio->bi_next;
1514                                 bio->bi_next = NULL;
1515                                 generic_make_request(bio);
1516                                 bio = next;
1517                         }
1518                         unplug = 1;
1519
1520                         continue;
1521                 }
1522
1523                 if (list_empty(head))
1524                         break;
1525                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
1526                 list_del(head->prev);
1527                 conf->nr_queued--;
1528                 spin_unlock_irqrestore(&conf->device_lock, flags);
1529
1530                 mddev = r10_bio->mddev;
1531                 conf = mddev_to_conf(mddev);
1532                 if (test_bit(R10BIO_IsSync, &r10_bio->state)) {
1533                         sync_request_write(mddev, r10_bio);
1534                         unplug = 1;
1535                 } else  if (test_bit(R10BIO_IsRecover, &r10_bio->state)) {
1536                         recovery_request_write(mddev, r10_bio);
1537                         unplug = 1;
1538                 } else {
1539                         int mirror;
1540                         /* we got a read error. Maybe the drive is bad.  Maybe just
1541                          * the block and we can fix it.
1542                          * We freeze all other IO, and try reading the block from
1543                          * other devices.  When we find one, we re-write
1544                          * and check it that fixes the read error.
1545                          * This is all done synchronously while the array is
1546                          * frozen.
1547                          */
1548                         if (mddev->ro == 0) {
1549                                 freeze_array(conf);
1550                                 fix_read_error(conf, mddev, r10_bio);
1551                                 unfreeze_array(conf);
1552                         }
1553
1554                         bio = r10_bio->devs[r10_bio->read_slot].bio;
1555                         r10_bio->devs[r10_bio->read_slot].bio =
1556                                 mddev->ro ? IO_BLOCKED : NULL;
1557                         bio_put(bio);
1558                         mirror = read_balance(conf, r10_bio);
1559                         if (mirror == -1) {
1560                                 printk(KERN_ALERT "raid10: %s: unrecoverable I/O"
1561                                        " read error for block %llu\n",
1562                                        bdevname(bio->bi_bdev,b),
1563                                        (unsigned long long)r10_bio->sector);
1564                                 raid_end_bio_io(r10_bio);
1565                         } else {
1566                                 rdev = conf->mirrors[mirror].rdev;
1567                                 if (printk_ratelimit())
1568                                         printk(KERN_ERR "raid10: %s: redirecting sector %llu to"
1569                                                " another mirror\n",
1570                                                bdevname(rdev->bdev,b),
1571                                                (unsigned long long)r10_bio->sector);
1572                                 bio = bio_clone(r10_bio->master_bio, GFP_NOIO);
1573                                 r10_bio->devs[r10_bio->read_slot].bio = bio;
1574                                 bio->bi_sector = r10_bio->devs[r10_bio->read_slot].addr
1575                                         + rdev->data_offset;
1576                                 bio->bi_bdev = rdev->bdev;
1577                                 bio->bi_rw = READ;
1578                                 bio->bi_private = r10_bio;
1579                                 bio->bi_end_io = raid10_end_read_request;
1580                                 unplug = 1;
1581                                 generic_make_request(bio);
1582                         }
1583                 }
1584         }
1585         spin_unlock_irqrestore(&conf->device_lock, flags);
1586         if (unplug)
1587                 unplug_slaves(mddev);
1588 }
1589
1590
1591 static int init_resync(conf_t *conf)
1592 {
1593         int buffs;
1594
1595         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1596         BUG_ON(conf->r10buf_pool);
1597         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
1598         if (!conf->r10buf_pool)
1599                 return -ENOMEM;
1600         conf->next_resync = 0;
1601         return 0;
1602 }
1603
1604 /*
1605  * perform a "sync" on one "block"
1606  *
1607  * We need to make sure that no normal I/O request - particularly write
1608  * requests - conflict with active sync requests.
1609  *
1610  * This is achieved by tracking pending requests and a 'barrier' concept
1611  * that can be installed to exclude normal IO requests.
1612  *
1613  * Resync and recovery are handled very differently.
1614  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
1615  *
1616  * For resync, we iterate over virtual addresses, read all copies,
1617  * and update if there are differences.  If only one copy is live,
1618  * skip it.
1619  * For recovery, we iterate over physical addresses, read a good
1620  * value for each non-in_sync drive, and over-write.
1621  *
1622  * So, for recovery we may have several outstanding complex requests for a
1623  * given address, one for each out-of-sync device.  We model this by allocating
1624  * a number of r10_bio structures, one for each out-of-sync device.
1625  * As we setup these structures, we collect all bio's together into a list
1626  * which we then process collectively to add pages, and then process again
1627  * to pass to generic_make_request.
1628  *
1629  * The r10_bio structures are linked using a borrowed master_bio pointer.
1630  * This link is counted in ->remaining.  When the r10_bio that points to NULL
1631  * has its remaining count decremented to 0, the whole complex operation
1632  * is complete.
1633  *
1634  */
1635
1636 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1637 {
1638         conf_t *conf = mddev_to_conf(mddev);
1639         r10bio_t *r10_bio;
1640         struct bio *biolist = NULL, *bio;
1641         sector_t max_sector, nr_sectors;
1642         int disk;
1643         int i;
1644         int max_sync;
1645         int sync_blocks;
1646
1647         sector_t sectors_skipped = 0;
1648         int chunks_skipped = 0;
1649
1650         if (!conf->r10buf_pool)
1651                 if (init_resync(conf))
1652                         return 0;
1653
1654  skipped:
1655         max_sector = mddev->size << 1;
1656         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1657                 max_sector = mddev->resync_max_sectors;
1658         if (sector_nr >= max_sector) {
1659                 /* If we aborted, we need to abort the
1660                  * sync on the 'current' bitmap chucks (there can
1661                  * be several when recovering multiple devices).
1662                  * as we may have started syncing it but not finished.
1663                  * We can find the current address in
1664                  * mddev->curr_resync, but for recovery,
1665                  * we need to convert that to several
1666                  * virtual addresses.
1667                  */
1668                 if (mddev->curr_resync < max_sector) { /* aborted */
1669                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1670                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1671                                                 &sync_blocks, 1);
1672                         else for (i=0; i<conf->raid_disks; i++) {
1673                                 sector_t sect =
1674                                         raid10_find_virt(conf, mddev->curr_resync, i);
1675                                 bitmap_end_sync(mddev->bitmap, sect,
1676                                                 &sync_blocks, 1);
1677                         }
1678                 } else /* completed sync */
1679                         conf->fullsync = 0;
1680
1681                 bitmap_close_sync(mddev->bitmap);
1682                 close_sync(conf);
1683                 *skipped = 1;
1684                 return sectors_skipped;
1685         }
1686         if (chunks_skipped >= conf->raid_disks) {
1687                 /* if there has been nothing to do on any drive,
1688                  * then there is nothing to do at all..
1689                  */
1690                 *skipped = 1;
1691                 return (max_sector - sector_nr) + sectors_skipped;
1692         }
1693
1694         /* make sure whole request will fit in a chunk - if chunks
1695          * are meaningful
1696          */
1697         if (conf->near_copies < conf->raid_disks &&
1698             max_sector > (sector_nr | conf->chunk_mask))
1699                 max_sector = (sector_nr | conf->chunk_mask) + 1;
1700         /*
1701          * If there is non-resync activity waiting for us then
1702          * put in a delay to throttle resync.
1703          */
1704         if (!go_faster && conf->nr_waiting)
1705                 msleep_interruptible(1000);
1706
1707         /* Again, very different code for resync and recovery.
1708          * Both must result in an r10bio with a list of bios that
1709          * have bi_end_io, bi_sector, bi_bdev set,
1710          * and bi_private set to the r10bio.
1711          * For recovery, we may actually create several r10bios
1712          * with 2 bios in each, that correspond to the bios in the main one.
1713          * In this case, the subordinate r10bios link back through a
1714          * borrowed master_bio pointer, and the counter in the master
1715          * includes a ref from each subordinate.
1716          */
1717         /* First, we decide what to do and set ->bi_end_io
1718          * To end_sync_read if we want to read, and
1719          * end_sync_write if we will want to write.
1720          */
1721
1722         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
1723         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1724                 /* recovery... the complicated one */
1725                 int i, j, k;
1726                 r10_bio = NULL;
1727
1728                 for (i=0 ; i<conf->raid_disks; i++)
1729                         if (conf->mirrors[i].rdev &&
1730                             !test_bit(In_sync, &conf->mirrors[i].rdev->flags)) {
1731                                 int still_degraded = 0;
1732                                 /* want to reconstruct this device */
1733                                 r10bio_t *rb2 = r10_bio;
1734                                 sector_t sect = raid10_find_virt(conf, sector_nr, i);
1735                                 int must_sync;
1736                                 /* Unless we are doing a full sync, we only need
1737                                  * to recover the block if it is set in the bitmap
1738                                  */
1739                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1740                                                               &sync_blocks, 1);
1741                                 if (sync_blocks < max_sync)
1742                                         max_sync = sync_blocks;
1743                                 if (!must_sync &&
1744                                     !conf->fullsync) {
1745                                         /* yep, skip the sync_blocks here, but don't assume
1746                                          * that there will never be anything to do here
1747                                          */
1748                                         chunks_skipped = -1;
1749                                         continue;
1750                                 }
1751
1752                                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1753                                 raise_barrier(conf, rb2 != NULL);
1754                                 atomic_set(&r10_bio->remaining, 0);
1755
1756                                 r10_bio->master_bio = (struct bio*)rb2;
1757                                 if (rb2)
1758                                         atomic_inc(&rb2->remaining);
1759                                 r10_bio->mddev = mddev;
1760                                 set_bit(R10BIO_IsRecover, &r10_bio->state);
1761                                 r10_bio->sector = sect;
1762
1763                                 raid10_find_phys(conf, r10_bio);
1764                                 /* Need to check if this section will still be
1765                                  * degraded
1766                                  */
1767                                 for (j=0; j<conf->copies;j++) {
1768                                         int d = r10_bio->devs[j].devnum;
1769                                         if (conf->mirrors[d].rdev == NULL ||
1770                                             test_bit(Faulty, &conf->mirrors[d].rdev->flags)) {
1771                                                 still_degraded = 1;
1772                                                 break;
1773                                         }
1774                                 }
1775                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1776                                                               &sync_blocks, still_degraded);
1777
1778                                 for (j=0; j<conf->copies;j++) {
1779                                         int d = r10_bio->devs[j].devnum;
1780                                         if (conf->mirrors[d].rdev &&
1781                                             test_bit(In_sync, &conf->mirrors[d].rdev->flags)) {
1782                                                 /* This is where we read from */
1783                                                 bio = r10_bio->devs[0].bio;
1784                                                 bio->bi_next = biolist;
1785                                                 biolist = bio;
1786                                                 bio->bi_private = r10_bio;
1787                                                 bio->bi_end_io = end_sync_read;
1788                                                 bio->bi_rw = 0;
1789                                                 bio->bi_sector = r10_bio->devs[j].addr +
1790                                                         conf->mirrors[d].rdev->data_offset;
1791                                                 bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1792                                                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1793                                                 atomic_inc(&r10_bio->remaining);
1794                                                 /* and we write to 'i' */
1795
1796                                                 for (k=0; k<conf->copies; k++)
1797                                                         if (r10_bio->devs[k].devnum == i)
1798                                                                 break;
1799                                                 bio = r10_bio->devs[1].bio;
1800                                                 bio->bi_next = biolist;
1801                                                 biolist = bio;
1802                                                 bio->bi_private = r10_bio;
1803                                                 bio->bi_end_io = end_sync_write;
1804                                                 bio->bi_rw = 1;
1805                                                 bio->bi_sector = r10_bio->devs[k].addr +
1806                                                         conf->mirrors[i].rdev->data_offset;
1807                                                 bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1808
1809                                                 r10_bio->devs[0].devnum = d;
1810                                                 r10_bio->devs[1].devnum = i;
1811
1812                                                 break;
1813                                         }
1814                                 }
1815                                 if (j == conf->copies) {
1816                                         /* Cannot recover, so abort the recovery */
1817                                         put_buf(r10_bio);
1818                                         r10_bio = rb2;
1819                                         if (!test_and_set_bit(MD_RECOVERY_ERR, &mddev->recovery))
1820                                                 printk(KERN_INFO "raid10: %s: insufficient working devices for recovery.\n",
1821                                                        mdname(mddev));
1822                                         break;
1823                                 }
1824                         }
1825                 if (biolist == NULL) {
1826                         while (r10_bio) {
1827                                 r10bio_t *rb2 = r10_bio;
1828                                 r10_bio = (r10bio_t*) rb2->master_bio;
1829                                 rb2->master_bio = NULL;
1830                                 put_buf(rb2);
1831                         }
1832                         goto giveup;
1833                 }
1834         } else {
1835                 /* resync. Schedule a read for every block at this virt offset */
1836                 int count = 0;
1837
1838                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1839                                        &sync_blocks, mddev->degraded) &&
1840                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1841                         /* We can skip this block */
1842                         *skipped = 1;
1843                         return sync_blocks + sectors_skipped;
1844                 }
1845                 if (sync_blocks < max_sync)
1846                         max_sync = sync_blocks;
1847                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1848
1849                 r10_bio->mddev = mddev;
1850                 atomic_set(&r10_bio->remaining, 0);
1851                 raise_barrier(conf, 0);
1852                 conf->next_resync = sector_nr;
1853
1854                 r10_bio->master_bio = NULL;
1855                 r10_bio->sector = sector_nr;
1856                 set_bit(R10BIO_IsSync, &r10_bio->state);
1857                 raid10_find_phys(conf, r10_bio);
1858                 r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
1859
1860                 for (i=0; i<conf->copies; i++) {
1861                         int d = r10_bio->devs[i].devnum;
1862                         bio = r10_bio->devs[i].bio;
1863                         bio->bi_end_io = NULL;
1864                         if (conf->mirrors[d].rdev == NULL ||
1865                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
1866                                 continue;
1867                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1868                         atomic_inc(&r10_bio->remaining);
1869                         bio->bi_next = biolist;
1870                         biolist = bio;
1871                         bio->bi_private = r10_bio;
1872                         bio->bi_end_io = end_sync_read;
1873                         bio->bi_rw = 0;
1874                         bio->bi_sector = r10_bio->devs[i].addr +
1875                                 conf->mirrors[d].rdev->data_offset;
1876                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1877                         count++;
1878                 }
1879
1880                 if (count < 2) {
1881                         for (i=0; i<conf->copies; i++) {
1882                                 int d = r10_bio->devs[i].devnum;
1883                                 if (r10_bio->devs[i].bio->bi_end_io)
1884                                         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1885                         }
1886                         put_buf(r10_bio);
1887                         biolist = NULL;
1888                         goto giveup;
1889                 }
1890         }
1891
1892         for (bio = biolist; bio ; bio=bio->bi_next) {
1893
1894                 bio->bi_flags &= ~(BIO_POOL_MASK - 1);
1895                 if (bio->bi_end_io)
1896                         bio->bi_flags |= 1 << BIO_UPTODATE;
1897                 bio->bi_vcnt = 0;
1898                 bio->bi_idx = 0;
1899                 bio->bi_phys_segments = 0;
1900                 bio->bi_hw_segments = 0;
1901                 bio->bi_size = 0;
1902         }
1903
1904         nr_sectors = 0;
1905         if (sector_nr + max_sync < max_sector)
1906                 max_sector = sector_nr + max_sync;
1907         do {
1908                 struct page *page;
1909                 int len = PAGE_SIZE;
1910                 disk = 0;
1911                 if (sector_nr + (len>>9) > max_sector)
1912                         len = (max_sector - sector_nr) << 9;
1913                 if (len == 0)
1914                         break;
1915                 for (bio= biolist ; bio ; bio=bio->bi_next) {
1916                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1917                         if (bio_add_page(bio, page, len, 0) == 0) {
1918                                 /* stop here */
1919                                 struct bio *bio2;
1920                                 bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1921                                 for (bio2 = biolist; bio2 && bio2 != bio; bio2 = bio2->bi_next) {
1922                                         /* remove last page from this bio */
1923                                         bio2->bi_vcnt--;
1924                                         bio2->bi_size -= len;
1925                                         bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
1926                                 }
1927                                 goto bio_full;
1928                         }
1929                         disk = i;
1930                 }
1931                 nr_sectors += len>>9;
1932                 sector_nr += len>>9;
1933         } while (biolist->bi_vcnt < RESYNC_PAGES);
1934  bio_full:
1935         r10_bio->sectors = nr_sectors;
1936
1937         while (biolist) {
1938                 bio = biolist;
1939                 biolist = biolist->bi_next;
1940
1941                 bio->bi_next = NULL;
1942                 r10_bio = bio->bi_private;
1943                 r10_bio->sectors = nr_sectors;
1944
1945                 if (bio->bi_end_io == end_sync_read) {
1946                         md_sync_acct(bio->bi_bdev, nr_sectors);
1947                         generic_make_request(bio);
1948                 }
1949         }
1950
1951         if (sectors_skipped)
1952                 /* pretend they weren't skipped, it makes
1953                  * no important difference in this case
1954                  */
1955                 md_done_sync(mddev, sectors_skipped, 1);
1956
1957         return sectors_skipped + nr_sectors;
1958  giveup:
1959         /* There is nowhere to write, so all non-sync
1960          * drives must be failed, so try the next chunk...
1961          */
1962         {
1963         sector_t sec = max_sector - sector_nr;
1964         sectors_skipped += sec;
1965         chunks_skipped ++;
1966         sector_nr = max_sector;
1967         goto skipped;
1968         }
1969 }
1970
1971 static int run(mddev_t *mddev)
1972 {
1973         conf_t *conf;
1974         int i, disk_idx;
1975         mirror_info_t *disk;
1976         mdk_rdev_t *rdev;
1977         struct list_head *tmp;
1978         int nc, fc, fo;
1979         sector_t stride, size;
1980
1981         if (mddev->chunk_size == 0) {
1982                 printk(KERN_ERR "md/raid10: non-zero chunk size required.\n");
1983                 return -EINVAL;
1984         }
1985
1986         nc = mddev->layout & 255;
1987         fc = (mddev->layout >> 8) & 255;
1988         fo = mddev->layout & (1<<16);
1989         if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
1990             (mddev->layout >> 17)) {
1991                 printk(KERN_ERR "raid10: %s: unsupported raid10 layout: 0x%8x\n",
1992                        mdname(mddev), mddev->layout);
1993                 goto out;
1994         }
1995         /*
1996          * copy the already verified devices into our private RAID10
1997          * bookkeeping area. [whatever we allocate in run(),
1998          * should be freed in stop()]
1999          */
2000         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
2001         mddev->private = conf;
2002         if (!conf) {
2003                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2004                         mdname(mddev));
2005                 goto out;
2006         }
2007         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
2008                                  GFP_KERNEL);
2009         if (!conf->mirrors) {
2010                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2011                        mdname(mddev));
2012                 goto out_free_conf;
2013         }
2014
2015         conf->tmppage = alloc_page(GFP_KERNEL);
2016         if (!conf->tmppage)
2017                 goto out_free_conf;
2018
2019         conf->near_copies = nc;
2020         conf->far_copies = fc;
2021         conf->copies = nc*fc;
2022         conf->far_offset = fo;
2023         conf->chunk_mask = (sector_t)(mddev->chunk_size>>9)-1;
2024         conf->chunk_shift = ffz(~mddev->chunk_size) - 9;
2025         if (fo)
2026                 conf->stride = 1 << conf->chunk_shift;
2027         else {
2028                 stride = mddev->size >> (conf->chunk_shift-1);
2029                 sector_div(stride, fc);
2030                 conf->stride = stride << conf->chunk_shift;
2031         }
2032         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
2033                                                 r10bio_pool_free, conf);
2034         if (!conf->r10bio_pool) {
2035                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2036                         mdname(mddev));
2037                 goto out_free_conf;
2038         }
2039
2040         ITERATE_RDEV(mddev, rdev, tmp) {
2041                 disk_idx = rdev->raid_disk;
2042                 if (disk_idx >= mddev->raid_disks
2043                     || disk_idx < 0)
2044                         continue;
2045                 disk = conf->mirrors + disk_idx;
2046
2047                 disk->rdev = rdev;
2048
2049                 blk_queue_stack_limits(mddev->queue,
2050                                        rdev->bdev->bd_disk->queue);
2051                 /* as we don't honour merge_bvec_fn, we must never risk
2052                  * violating it, so limit ->max_sector to one PAGE, as
2053                  * a one page request is never in violation.
2054                  */
2055                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
2056                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
2057                         mddev->queue->max_sectors = (PAGE_SIZE>>9);
2058
2059                 disk->head_position = 0;
2060         }
2061         conf->raid_disks = mddev->raid_disks;
2062         conf->mddev = mddev;
2063         spin_lock_init(&conf->device_lock);
2064         INIT_LIST_HEAD(&conf->retry_list);
2065
2066         spin_lock_init(&conf->resync_lock);
2067         init_waitqueue_head(&conf->wait_barrier);
2068
2069         /* need to check that every block has at least one working mirror */
2070         if (!enough(conf)) {
2071                 printk(KERN_ERR "raid10: not enough operational mirrors for %s\n",
2072                        mdname(mddev));
2073                 goto out_free_conf;
2074         }
2075
2076         mddev->degraded = 0;
2077         for (i = 0; i < conf->raid_disks; i++) {
2078
2079                 disk = conf->mirrors + i;
2080
2081                 if (!disk->rdev ||
2082                     !test_bit(In_sync, &rdev->flags)) {
2083                         disk->head_position = 0;
2084                         mddev->degraded++;
2085                 }
2086         }
2087
2088
2089         mddev->thread = md_register_thread(raid10d, mddev, "%s_raid10");
2090         if (!mddev->thread) {
2091                 printk(KERN_ERR
2092                        "raid10: couldn't allocate thread for %s\n",
2093                        mdname(mddev));
2094                 goto out_free_conf;
2095         }
2096
2097         printk(KERN_INFO
2098                 "raid10: raid set %s active with %d out of %d devices\n",
2099                 mdname(mddev), mddev->raid_disks - mddev->degraded,
2100                 mddev->raid_disks);
2101         /*
2102          * Ok, everything is just fine now
2103          */
2104         if (conf->far_offset) {
2105                 size = mddev->size >> (conf->chunk_shift-1);
2106                 size *= conf->raid_disks;
2107                 size <<= conf->chunk_shift;
2108                 sector_div(size, conf->far_copies);
2109         } else
2110                 size = conf->stride * conf->raid_disks;
2111         sector_div(size, conf->near_copies);
2112         mddev->array_size = size/2;
2113         mddev->resync_max_sectors = size;
2114
2115         mddev->queue->unplug_fn = raid10_unplug;
2116         mddev->queue->issue_flush_fn = raid10_issue_flush;
2117         mddev->queue->backing_dev_info.congested_fn = raid10_congested;
2118         mddev->queue->backing_dev_info.congested_data = mddev;
2119
2120         /* Calculate max read-ahead size.
2121          * We need to readahead at least twice a whole stripe....
2122          * maybe...
2123          */
2124         {
2125                 int stripe = conf->raid_disks * (mddev->chunk_size / PAGE_SIZE);
2126                 stripe /= conf->near_copies;
2127                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
2128                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
2129         }
2130
2131         if (conf->near_copies < mddev->raid_disks)
2132                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
2133         return 0;
2134
2135 out_free_conf:
2136         if (conf->r10bio_pool)
2137                 mempool_destroy(conf->r10bio_pool);
2138         safe_put_page(conf->tmppage);
2139         kfree(conf->mirrors);
2140         kfree(conf);
2141         mddev->private = NULL;
2142 out:
2143         return -EIO;
2144 }
2145
2146 static int stop(mddev_t *mddev)
2147 {
2148         conf_t *conf = mddev_to_conf(mddev);
2149
2150         md_unregister_thread(mddev->thread);
2151         mddev->thread = NULL;
2152         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2153         if (conf->r10bio_pool)
2154                 mempool_destroy(conf->r10bio_pool);
2155         kfree(conf->mirrors);
2156         kfree(conf);
2157         mddev->private = NULL;
2158         return 0;
2159 }
2160
2161 static void raid10_quiesce(mddev_t *mddev, int state)
2162 {
2163         conf_t *conf = mddev_to_conf(mddev);
2164
2165         switch(state) {
2166         case 1:
2167                 raise_barrier(conf, 0);
2168                 break;
2169         case 0:
2170                 lower_barrier(conf);
2171                 break;
2172         }
2173         if (mddev->thread) {
2174                 if (mddev->bitmap)
2175                         mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
2176                 else
2177                         mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
2178                 md_wakeup_thread(mddev->thread);
2179         }
2180 }
2181
2182 static struct mdk_personality raid10_personality =
2183 {
2184         .name           = "raid10",
2185         .level          = 10,
2186         .owner          = THIS_MODULE,
2187         .make_request   = make_request,
2188         .run            = run,
2189         .stop           = stop,
2190         .status         = status,
2191         .error_handler  = error,
2192         .hot_add_disk   = raid10_add_disk,
2193         .hot_remove_disk= raid10_remove_disk,
2194         .spare_active   = raid10_spare_active,
2195         .sync_request   = sync_request,
2196         .quiesce        = raid10_quiesce,
2197 };
2198
2199 static int __init raid_init(void)
2200 {
2201         return register_md_personality(&raid10_personality);
2202 }
2203
2204 static void raid_exit(void)
2205 {
2206         unregister_md_personality(&raid10_personality);
2207 }
2208
2209 module_init(raid_init);
2210 module_exit(raid_exit);
2211 MODULE_LICENSE("GPL");
2212 MODULE_ALIAS("md-personality-9"); /* RAID10 */
2213 MODULE_ALIAS("md-raid10");
2214 MODULE_ALIAS("md-level-10");