drivers/md/raid10.c

   1 /*
   2  * raid10.c : Multiple Devices driver for Linux
   3  *
   4  * Copyright (C) 2000-2004 Neil Brown
   5  *
   6  * RAID-10 support for md.
   7  *
   8  * Base on code in raid1.c.  See raid1.c for futher copyright information.
   9  *
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include "dm-bio-list.h"
  22 #include <linux/raid/raid10.h>
  23 #include <linux/raid/bitmap.h>
  24
  25 /*
  26  * RAID10 provides a combination of RAID0 and RAID1 functionality.
  27  * The layout of data is defined by
  28  *    chunk_size
  29  *    raid_disks
  30  *    near_copies (stored in low byte of layout)
  31  *    far_copies (stored in second byte of layout)
  32  *    far_offset (stored in bit 16 of layout )
  33  *
  34  * The data to be stored is divided into chunks using chunksize.
  35  * Each device is divided into far_copies sections.
  36  * In each section, chunks are laid out in a style similar to raid0, but
  37  * near_copies copies of each chunk is stored (each on a different drive).
  38  * The starting device for each section is offset near_copies from the starting
  39  * device of the previous section.
  40  * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
  41  * drive.
  42  * near_copies and far_copies must be at least one, and their product is at most
  43  * raid_disks.
  44  *
  45  * If far_offset is true, then the far_copies are handled a bit differently.
  46  * The copies are still in different stripes, but instead of be very far apart
  47  * on disk, there are adjacent stripes.
  48  */
  49
  50 /*
  51  * Number of guaranteed r10bios in case of extreme VM load:
  52  */
  53 #define NR_RAID10_BIOS 256
  54
  55 static void unplug_slaves(mddev_t *mddev);
  56
  57 static void allow_barrier(conf_t *conf);
  58 static void lower_barrier(conf_t *conf);
  59
  60 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
  61 {
  62         conf_t *conf = data;
  63         r10bio_t *r10_bio;
  64         int size = offsetof(struct r10bio_s, devs[conf->copies]);
  65
  66         /* allocate a r10bio with room for raid_disks entries in the bios array */
  67         r10_bio = kzalloc(size, gfp_flags);
  68         if (!r10_bio)
  69                 unplug_slaves(conf->mddev);
  70
  71         return r10_bio;
  72 }
  73
  74 static void r10bio_pool_free(void *r10_bio, void *data)
  75 {
  76         kfree(r10_bio);
  77 }
  78
  79 #define RESYNC_BLOCK_SIZE (64*1024)
  80 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
  81 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
  82 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  83 #define RESYNC_WINDOW (2048*1024)
  84
  85 /*
  86  * When performing a resync, we need to read and compare, so
  87  * we need as many pages are there are copies.
  88  * When performing a recovery, we need 2 bios, one for read,
  89  * one for write (we recover only one drive per r10buf)
  90  *
  91  */
  92 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
  93 {
  94         conf_t *conf = data;
  95         struct page *page;
  96         r10bio_t *r10_bio;
  97         struct bio *bio;
  98         int i, j;
  99         int nalloc;
 100
 101         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
 102         if (!r10_bio) {
 103                 unplug_slaves(conf->mddev);
 104                 return NULL;
 105         }
 106
 107         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
 108                 nalloc = conf->copies; /* resync */
 109         else
 110                 nalloc = 2; /* recovery */
 111
 112         /*
 113          * Allocate bios.
 114          */
 115         for (j = nalloc ; j-- ; ) {
 116                 bio = bio_alloc(gfp_flags, RESYNC_PAGES);
 117                 if (!bio)
 118                         goto out_free_bio;
 119                 r10_bio->devs[j].bio = bio;
 120         }
 121         /*
 122          * Allocate RESYNC_PAGES data pages and attach them
 123          * where needed.
 124          */
 125         for (j = 0 ; j < nalloc; j++) {
 126                 bio = r10_bio->devs[j].bio;
 127                 for (i = 0; i < RESYNC_PAGES; i++) {
 128                         page = alloc_page(gfp_flags);
 129                         if (unlikely(!page))
 130                                 goto out_free_pages;
 131
 132                         bio->bi_io_vec[i].bv_page = page;
 133                 }
 134         }
 135
 136         return r10_bio;
 137
 138 out_free_pages:
 139         for ( ; i > 0 ; i--)
 140                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
 141         while (j--)
 142                 for (i = 0; i < RESYNC_PAGES ; i++)
 143                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
 144         j = -1;
 145 out_free_bio:
 146         while ( ++j < nalloc )
 147                 bio_put(r10_bio->devs[j].bio);
 148         r10bio_pool_free(r10_bio, conf);
 149         return NULL;
 150 }
 151
 152 static void r10buf_pool_free(void *__r10_bio, void *data)
 153 {
 154         int i;
 155         conf_t *conf = data;
 156         r10bio_t *r10bio = __r10_bio;
 157         int j;
 158
 159         for (j=0; j < conf->copies; j++) {
 160                 struct bio *bio = r10bio->devs[j].bio;
 161                 if (bio) {
 162                         for (i = 0; i < RESYNC_PAGES; i++) {
 163                                 safe_put_page(bio->bi_io_vec[i].bv_page);
 164                                 bio->bi_io_vec[i].bv_page = NULL;
 165                         }
 166                         bio_put(bio);
 167                 }
 168         }
 169         r10bio_pool_free(r10bio, conf);
 170 }
 171
 172 static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
 173 {
 174         int i;
 175
 176         for (i = 0; i < conf->copies; i++) {
 177                 struct bio **bio = & r10_bio->devs[i].bio;
 178                 if (*bio && *bio != IO_BLOCKED)
 179                         bio_put(*bio);
 180                 *bio = NULL;
 181         }
 182 }
 183
 184 static void free_r10bio(r10bio_t *r10_bio)
 185 {
 186         conf_t *conf = mddev_to_conf(r10_bio->mddev);
 187
 188         /*
 189          * Wake up any possible resync thread that waits for the device
 190          * to go idle.
 191          */
 192         allow_barrier(conf);
 193
 194         put_all_bios(conf, r10_bio);
 195         mempool_free(r10_bio, conf->r10bio_pool);
 196 }
 197
 198 static void put_buf(r10bio_t *r10_bio)
 199 {
 200         conf_t *conf = mddev_to_conf(r10_bio->mddev);
 201
 202         mempool_free(r10_bio, conf->r10buf_pool);
 203
 204         lower_barrier(conf);
 205 }
 206
 207 static void reschedule_retry(r10bio_t *r10_bio)
 208 {
 209         unsigned long flags;
 210         mddev_t *mddev = r10_bio->mddev;
 211         conf_t *conf = mddev_to_conf(mddev);
 212
 213         spin_lock_irqsave(&conf->device_lock, flags);
 214         list_add(&r10_bio->retry_list, &conf->retry_list);
 215         conf->nr_queued ++;
 216         spin_unlock_irqrestore(&conf->device_lock, flags);
 217
 218         md_wakeup_thread(mddev->thread);
 219 }
 220
 221 /*
 222  * raid_end_bio_io() is called when we have finished servicing a mirrored
 223  * operation and are ready to return a success/failure code to the buffer
 224  * cache layer.
 225  */
 226 static void raid_end_bio_io(r10bio_t *r10_bio)
 227 {
 228         struct bio *bio = r10_bio->master_bio;
 229
 230         bio_endio(bio, bio->bi_size,
 231                 test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
 232         free_r10bio(r10_bio);
 233 }
 234
 235 /*
 236  * Update disk head position estimator based on IRQ completion info.
 237  */
 238 static inline void update_head_pos(int slot, r10bio_t *r10_bio)
 239 {
 240         conf_t *conf = mddev_to_conf(r10_bio->mddev);
 241
 242         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
 243                 r10_bio->devs[slot].addr + (r10_bio->sectors);
 244 }
 245
 246 static int raid10_end_read_request(struct bio *bio, unsigned int bytes_done, int error)
 247 {
 248         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 249         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
 250         int slot, dev;
 251         conf_t *conf = mddev_to_conf(r10_bio->mddev);
 252
 253         if (bio->bi_size)
 254                 return 1;
 255
 256         slot = r10_bio->read_slot;
 257         dev = r10_bio->devs[slot].devnum;
 258         /*
 259          * this branch is our 'one mirror IO has finished' event handler:
 260          */
 261         update_head_pos(slot, r10_bio);
 262
 263         if (uptodate) {
 264                 /*
 265                  * Set R10BIO_Uptodate in our master bio, so that
 266                  * we will return a good error code to the higher
 267                  * levels even if IO on some other mirrored buffer fails.
 268                  *
 269                  * The 'master' represents the composite IO operation to
 270                  * user-side. So if something waits for IO, then it will
 271                  * wait for the 'master' bio.
 272                  */
 273                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 274                 raid_end_bio_io(r10_bio);
 275         } else {
 276                 /*
 277                  * oops, read error:
 278                  */
 279                 char b[BDEVNAME_SIZE];
 280                 if (printk_ratelimit())
 281                         printk(KERN_ERR "raid10: %s: rescheduling sector %llu\n",
 282                                bdevname(conf->mirrors[dev].rdev->bdev,b), (unsigned long long)r10_bio->sector);
 283                 reschedule_retry(r10_bio);
 284         }
 285
 286         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 287         return 0;
 288 }
 289
 290 static int raid10_end_write_request(struct bio *bio, unsigned int bytes_done, int error)
 291 {
 292         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 293         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
 294         int slot, dev;
 295         conf_t *conf = mddev_to_conf(r10_bio->mddev);
 296
 297         if (bio->bi_size)
 298                 return 1;
 299
 300         for (slot = 0; slot < conf->copies; slot++)
 301                 if (r10_bio->devs[slot].bio == bio)
 302                         break;
 303         dev = r10_bio->devs[slot].devnum;
 304
 305         /*
 306          * this branch is our 'one mirror IO has finished' event handler:
 307          */
 308         if (!uptodate) {
 309                 md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
 310                 /* an I/O failed, we can't clear the bitmap */
 311                 set_bit(R10BIO_Degraded, &r10_bio->state);
 312         } else
 313                 /*
 314                  * Set R10BIO_Uptodate in our master bio, so that
 315                  * we will return a good error code for to the higher
 316                  * levels even if IO on some other mirrored buffer fails.
 317                  *
 318                  * The 'master' represents the composite IO operation to
 319                  * user-side. So if something waits for IO, then it will
 320                  * wait for the 'master' bio.
 321                  */
 322                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 323
 324         update_head_pos(slot, r10_bio);
 325
 326         /*
 327          *
 328          * Let's see if all mirrored write operations have finished
 329          * already.
 330          */
 331         if (atomic_dec_and_test(&r10_bio->remaining)) {
 332                 /* clear the bitmap if all writes complete successfully */
 333                 bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 334                                 r10_bio->sectors,
 335                                 !test_bit(R10BIO_Degraded, &r10_bio->state),
 336                                 0);
 337                 md_write_end(r10_bio->mddev);
 338                 raid_end_bio_io(r10_bio);
 339         }
 340
 341         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 342         return 0;
 343 }
 344
 345
 346 /*
 347  * RAID10 layout manager
 348  * Aswell as the chunksize and raid_disks count, there are two
 349  * parameters: near_copies and far_copies.
 350  * near_copies * far_copies must be <= raid_disks.
 351  * Normally one of these will be 1.
 352  * If both are 1, we get raid0.
 353  * If near_copies == raid_disks, we get raid1.
 354  *
 355  * Chunks are layed out in raid0 style with near_copies copies of the
 356  * first chunk, followed by near_copies copies of the next chunk and
 357  * so on.
 358  * If far_copies > 1, then after 1/far_copies of the array has been assigned
 359  * as described above, we start again with a device offset of near_copies.
 360  * So we effectively have another copy of the whole array further down all
 361  * the drives, but with blocks on different drives.
 362  * With this layout, and block is never stored twice on the one device.
 363  *
 364  * raid10_find_phys finds the sector offset of a given virtual sector
 365  * on each device that it is on.
 366  *
 367  * raid10_find_virt does the reverse mapping, from a device and a
 368  * sector offset to a virtual address
 369  */
 370
 371 static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
 372 {
 373         int n,f;
 374         sector_t sector;
 375         sector_t chunk;
 376         sector_t stripe;
 377         int dev;
 378
 379         int slot = 0;
 380
 381         /* now calculate first sector/dev */
 382         chunk = r10bio->sector >> conf->chunk_shift;
 383         sector = r10bio->sector & conf->chunk_mask;
 384
 385         chunk *= conf->near_copies;
 386         stripe = chunk;
 387         dev = sector_div(stripe, conf->raid_disks);
 388         if (conf->far_offset)
 389                 stripe *= conf->far_copies;
 390
 391         sector += stripe << conf->chunk_shift;
 392
 393         /* and calculate all the others */
 394         for (n=0; n < conf->near_copies; n++) {
 395                 int d = dev;
 396                 sector_t s = sector;
 397                 r10bio->devs[slot].addr = sector;
 398                 r10bio->devs[slot].devnum = d;
 399                 slot++;
 400
 401                 for (f = 1; f < conf->far_copies; f++) {
 402                         d += conf->near_copies;
 403                         if (d >= conf->raid_disks)
 404                                 d -= conf->raid_disks;
 405                         s += conf->stride;
 406                         r10bio->devs[slot].devnum = d;
 407                         r10bio->devs[slot].addr = s;
 408                         slot++;
 409                 }
 410                 dev++;
 411                 if (dev >= conf->raid_disks) {
 412                         dev = 0;
 413                         sector += (conf->chunk_mask + 1);
 414                 }
 415         }
 416         BUG_ON(slot != conf->copies);
 417 }
 418
 419 static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
 420 {
 421         sector_t offset, chunk, vchunk;
 422
 423         offset = sector & conf->chunk_mask;
 424         if (conf->far_offset) {
 425                 int fc;
 426                 chunk = sector >> conf->chunk_shift;
 427                 fc = sector_div(chunk, conf->far_copies);
 428                 dev -= fc * conf->near_copies;
 429                 if (dev < 0)
 430                         dev += conf->raid_disks;
 431         } else {
 432                 while (sector > conf->stride) {
 433                         sector -= conf->stride;
 434                         if (dev < conf->near_copies)
 435                                 dev += conf->raid_disks - conf->near_copies;
 436                         else
 437                                 dev -= conf->near_copies;
 438                 }
 439                 chunk = sector >> conf->chunk_shift;
 440         }
 441         vchunk = chunk * conf->raid_disks + dev;
 442         sector_div(vchunk, conf->near_copies);
 443         return (vchunk << conf->chunk_shift) + offset;
 444 }
 445
 446 /**
 447  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
 448  *      @q: request queue
 449  *      @bio: the buffer head that's been built up so far
 450  *      @biovec: the request that could be merged to it.
 451  *
 452  *      Return amount of bytes we can accept at this offset
 453  *      If near_copies == raid_disk, there are no striping issues,
 454  *      but in that case, the function isn't called at all.
 455  */
 456 static int raid10_mergeable_bvec(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         const int do_sync = bio_sync(bio);
 786         struct bio_list bl;
 787         unsigned long flags;
 788
 789         if (unlikely(bio_barrier(bio))) {
 790                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
 791                 return 0;
 792         }
 793
 794         /* If this request crosses a chunk boundary, we need to
 795          * split it.  This will only happen for 1 PAGE (or less) requests.
 796          */
 797         if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
 798                       > chunk_sects &&
 799                     conf->near_copies < conf->raid_disks)) {
 800                 struct bio_pair *bp;
 801                 /* Sanity check -- queue functions should prevent this happening */
 802                 if (bio->bi_vcnt != 1 ||
 803                     bio->bi_idx != 0)
 804                         goto bad_map;
 805                 /* This is a one page bio that upper layers
 806                  * refuse to split for us, so we need to split it.
 807                  */
 808                 bp = bio_split(bio, bio_split_pool,
 809                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
 810                 if (make_request(q, &bp->bio1))
 811                         generic_make_request(&bp->bio1);
 812                 if (make_request(q, &bp->bio2))
 813                         generic_make_request(&bp->bio2);
 814
 815                 bio_pair_release(bp);
 816                 return 0;
 817         bad_map:
 818                 printk("raid10_make_request bug: can't convert block across chunks"
 819                        " or bigger than %dk %llu %d\n", chunk_sects/2,
 820                        (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 821
 822                 bio_io_error(bio, bio->bi_size);
 823                 return 0;
 824         }
 825
 826         md_write_start(mddev, bio);
 827
 828         /*
 829          * Register the new request and wait if the reconstruction
 830          * thread has put up a bar for new requests.
 831          * Continue immediately if no resync is active currently.
 832          */
 833         wait_barrier(conf);
 834
 835         disk_stat_inc(mddev->gendisk, ios[rw]);
 836         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
 837
 838         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
 839
 840         r10_bio->master_bio = bio;
 841         r10_bio->sectors = bio->bi_size >> 9;
 842
 843         r10_bio->mddev = mddev;
 844         r10_bio->sector = bio->bi_sector;
 845         r10_bio->state = 0;
 846
 847         if (rw == READ) {
 848                 /*
 849                  * read balancing logic:
 850                  */
 851                 int disk = read_balance(conf, r10_bio);
 852                 int slot = r10_bio->read_slot;
 853                 if (disk < 0) {
 854                         raid_end_bio_io(r10_bio);
 855                         return 0;
 856                 }
 857                 mirror = conf->mirrors + disk;
 858
 859                 read_bio = bio_clone(bio, GFP_NOIO);
 860
 861                 r10_bio->devs[slot].bio = read_bio;
 862
 863                 read_bio->bi_sector = r10_bio->devs[slot].addr +
 864                         mirror->rdev->data_offset;
 865                 read_bio->bi_bdev = mirror->rdev->bdev;
 866                 read_bio->bi_end_io = raid10_end_read_request;
 867                 read_bio->bi_rw = READ | do_sync;
 868                 read_bio->bi_private = r10_bio;
 869
 870                 generic_make_request(read_bio);
 871                 return 0;
 872         }
 873
 874         /*
 875          * WRITE:
 876          */
 877         /* first select target devices under spinlock and
 878          * inc refcount on their rdev.  Record them by setting
 879          * bios[x] to bio
 880          */
 881         raid10_find_phys(conf, r10_bio);
 882         rcu_read_lock();
 883         for (i = 0;  i < conf->copies; i++) {
 884                 int d = r10_bio->devs[i].devnum;
 885                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
 886                 if (rdev &&
 887                     !test_bit(Faulty, &rdev->flags)) {
 888                         atomic_inc(&rdev->nr_pending);
 889                         r10_bio->devs[i].bio = bio;
 890                 } else {
 891                         r10_bio->devs[i].bio = NULL;
 892                         set_bit(R10BIO_Degraded, &r10_bio->state);
 893                 }
 894         }
 895         rcu_read_unlock();
 896
 897         atomic_set(&r10_bio->remaining, 0);
 898
 899         bio_list_init(&bl);
 900         for (i = 0; i < conf->copies; i++) {
 901                 struct bio *mbio;
 902                 int d = r10_bio->devs[i].devnum;
 903                 if (!r10_bio->devs[i].bio)
 904                         continue;
 905
 906                 mbio = bio_clone(bio, GFP_NOIO);
 907                 r10_bio->devs[i].bio = mbio;
 908
 909                 mbio->bi_sector = r10_bio->devs[i].addr+
 910                         conf->mirrors[d].rdev->data_offset;
 911                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
 912                 mbio->bi_end_io = raid10_end_write_request;
 913                 mbio->bi_rw = WRITE | do_sync;
 914                 mbio->bi_private = r10_bio;
 915
 916                 atomic_inc(&r10_bio->remaining);
 917                 bio_list_add(&bl, mbio);
 918         }
 919
 920         bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
 921         spin_lock_irqsave(&conf->device_lock, flags);
 922         bio_list_merge(&conf->pending_bio_list, &bl);
 923         blk_plug_device(mddev->queue);
 924         spin_unlock_irqrestore(&conf->device_lock, flags);
 925
 926         if (do_sync)
 927                 md_wakeup_thread(mddev->thread);
 928
 929         return 0;
 930 }
 931
 932 static void status(struct seq_file *seq, mddev_t *mddev)
 933 {
 934         conf_t *conf = mddev_to_conf(mddev);
 935         int i;
 936
 937         if (conf->near_copies < conf->raid_disks)
 938                 seq_printf(seq, " %dK chunks", mddev->chunk_size/1024);
 939         if (conf->near_copies > 1)
 940                 seq_printf(seq, " %d near-copies", conf->near_copies);
 941         if (conf->far_copies > 1) {
 942                 if (conf->far_offset)
 943                         seq_printf(seq, " %d offset-copies", conf->far_copies);
 944                 else
 945                         seq_printf(seq, " %d far-copies", conf->far_copies);
 946         }
 947         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 948                                         conf->raid_disks - mddev->degraded);
 949         for (i = 0; i < conf->raid_disks; i++)
 950                 seq_printf(seq, "%s",
 951                               conf->mirrors[i].rdev &&
 952                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
 953         seq_printf(seq, "]");
 954 }
 955
 956 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 957 {
 958         char b[BDEVNAME_SIZE];
 959         conf_t *conf = mddev_to_conf(mddev);
 960
 961         /*
 962          * If it is not operational, then we have already marked it as dead
 963          * else if it is the last working disks, ignore the error, let the
 964          * next level up know.
 965          * else mark the drive as failed
 966          */
 967         if (test_bit(In_sync, &rdev->flags)
 968             && conf->raid_disks-mddev->degraded == 1)
 969                 /*
 970                  * Don't fail the drive, just return an IO error.
 971                  * The test should really be more sophisticated than
 972                  * "working_disks == 1", but it isn't critical, and
 973                  * can wait until we do more sophisticated "is the drive
 974                  * really dead" tests...
 975                  */
 976                 return;
 977         if (test_and_clear_bit(In_sync, &rdev->flags)) {
 978                 unsigned long flags;
 979                 spin_lock_irqsave(&conf->device_lock, flags);
 980                 mddev->degraded++;
 981                 spin_unlock_irqrestore(&conf->device_lock, flags);
 982                 /*
 983                  * if recovery is running, make sure it aborts.
 984                  */
 985                 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 986         }
 987         set_bit(Faulty, &rdev->flags);
 988         set_bit(MD_CHANGE_DEVS, &mddev->flags);
 989         printk(KERN_ALERT "raid10: Disk failure on %s, disabling device. \n"
 990                 "       Operation continuing on %d devices\n",
 991                 bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
 992 }
 993
 994 static void print_conf(conf_t *conf)
 995 {
 996         int i;
 997         mirror_info_t *tmp;
 998
 999         printk("RAID10 conf printout:\n");
1000         if (!conf) {
1001                 printk("(!conf)\n");
1002                 return;
1003         }
1004         printk(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1005                 conf->raid_disks);
1006
1007         for (i = 0; i < conf->raid_disks; i++) {
1008                 char b[BDEVNAME_SIZE];
1009                 tmp = conf->mirrors + i;
1010                 if (tmp->rdev)
1011                         printk(" disk %d, wo:%d, o:%d, dev:%s\n",
1012                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1013                                 !test_bit(Faulty, &tmp->rdev->flags),
1014                                 bdevname(tmp->rdev->bdev,b));
1015         }
1016 }
1017
1018 static void close_sync(conf_t *conf)
1019 {
1020         wait_barrier(conf);
1021         allow_barrier(conf);
1022
1023         mempool_destroy(conf->r10buf_pool);
1024         conf->r10buf_pool = NULL;
1025 }
1026
1027 /* check if there are enough drives for
1028  * every block to appear on atleast one
1029  */
1030 static int enough(conf_t *conf)
1031 {
1032         int first = 0;
1033
1034         do {
1035                 int n = conf->copies;
1036                 int cnt = 0;
1037                 while (n--) {
1038                         if (conf->mirrors[first].rdev)
1039                                 cnt++;
1040                         first = (first+1) % conf->raid_disks;
1041                 }
1042                 if (cnt == 0)
1043                         return 0;
1044         } while (first != 0);
1045         return 1;
1046 }
1047
1048 static int raid10_spare_active(mddev_t *mddev)
1049 {
1050         int i;
1051         conf_t *conf = mddev->private;
1052         mirror_info_t *tmp;
1053
1054         /*
1055          * Find all non-in_sync disks within the RAID10 configuration
1056          * and mark them in_sync
1057          */
1058         for (i = 0; i < conf->raid_disks; i++) {
1059                 tmp = conf->mirrors + i;
1060                 if (tmp->rdev
1061                     && !test_bit(Faulty, &tmp->rdev->flags)
1062                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1063                         unsigned long flags;
1064                         spin_lock_irqsave(&conf->device_lock, flags);
1065                         mddev->degraded--;
1066                         spin_unlock_irqrestore(&conf->device_lock, flags);
1067                 }
1068         }
1069
1070         print_conf(conf);
1071         return 0;
1072 }
1073
1074
1075 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1076 {
1077         conf_t *conf = mddev->private;
1078         int found = 0;
1079         int mirror;
1080         mirror_info_t *p;
1081
1082         if (mddev->recovery_cp < MaxSector)
1083                 /* only hot-add to in-sync arrays, as recovery is
1084                  * very different from resync
1085                  */
1086                 return 0;
1087         if (!enough(conf))
1088                 return 0;
1089
1090         if (rdev->saved_raid_disk >= 0 &&
1091             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1092                 mirror = rdev->saved_raid_disk;
1093         else
1094                 mirror = 0;
1095         for ( ; mirror < mddev->raid_disks; mirror++)
1096                 if ( !(p=conf->mirrors+mirror)->rdev) {
1097
1098                         blk_queue_stack_limits(mddev->queue,
1099                                                rdev->bdev->bd_disk->queue);
1100                         /* as we don't honour merge_bvec_fn, we must never risk
1101                          * violating it, so limit ->max_sector to one PAGE, as
1102                          * a one page request is never in violation.
1103                          */
1104                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1105                             mddev->queue->max_sectors > (PAGE_SIZE>>9))
1106                                 mddev->queue->max_sectors = (PAGE_SIZE>>9);
1107
1108                         p->head_position = 0;
1109                         rdev->raid_disk = mirror;
1110                         found = 1;
1111                         if (rdev->saved_raid_disk != mirror)
1112                                 conf->fullsync = 1;
1113                         rcu_assign_pointer(p->rdev, rdev);
1114                         break;
1115                 }
1116
1117         print_conf(conf);
1118         return found;
1119 }
1120
1121 static int raid10_remove_disk(mddev_t *mddev, int number)
1122 {
1123         conf_t *conf = mddev->private;
1124         int err = 0;
1125         mdk_rdev_t *rdev;
1126         mirror_info_t *p = conf->mirrors+ number;
1127
1128         print_conf(conf);
1129         rdev = p->rdev;
1130         if (rdev) {
1131                 if (test_bit(In_sync, &rdev->flags) ||
1132                     atomic_read(&rdev->nr_pending)) {
1133                         err = -EBUSY;
1134                         goto abort;
1135                 }
1136                 p->rdev = NULL;
1137                 synchronize_rcu();
1138                 if (atomic_read(&rdev->nr_pending)) {
1139                         /* lost the race, try later */
1140                         err = -EBUSY;
1141                         p->rdev = rdev;
1142                 }
1143         }
1144 abort:
1145
1146         print_conf(conf);
1147         return err;
1148 }
1149
1150
1151 static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
1152 {
1153         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
1154         conf_t *conf = mddev_to_conf(r10_bio->mddev);
1155         int i,d;
1156
1157         if (bio->bi_size)
1158                 return 1;
1159
1160         for (i=0; i<conf->copies; i++)
1161                 if (r10_bio->devs[i].bio == bio)
1162                         break;
1163         BUG_ON(i == conf->copies);
1164         update_head_pos(i, r10_bio);
1165         d = r10_bio->devs[i].devnum;
1166
1167         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1168                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1169         else {
1170                 atomic_add(r10_bio->sectors,
1171                            &conf->mirrors[d].rdev->corrected_errors);
1172                 if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
1173                         md_error(r10_bio->mddev,
1174                                  conf->mirrors[d].rdev);
1175         }
1176
1177         /* for reconstruct, we always reschedule after a read.
1178          * for resync, only after all reads
1179          */
1180         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1181             atomic_dec_and_test(&r10_bio->remaining)) {
1182                 /* we have read all the blocks,
1183                  * do the comparison in process context in raid10d
1184                  */
1185                 reschedule_retry(r10_bio);
1186         }
1187         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1188         return 0;
1189 }
1190
1191 static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error)
1192 {
1193         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1194         r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
1195         mddev_t *mddev = r10_bio->mddev;
1196         conf_t *conf = mddev_to_conf(mddev);
1197         int i,d;
1198
1199         if (bio->bi_size)
1200                 return 1;
1201
1202         for (i = 0; i < conf->copies; i++)
1203                 if (r10_bio->devs[i].bio == bio)
1204                         break;
1205         d = r10_bio->devs[i].devnum;
1206
1207         if (!uptodate)
1208                 md_error(mddev, conf->mirrors[d].rdev);
1209         update_head_pos(i, r10_bio);
1210
1211         while (atomic_dec_and_test(&r10_bio->remaining)) {
1212                 if (r10_bio->master_bio == NULL) {
1213                         /* the primary of several recovery bios */
1214                         md_done_sync(mddev, r10_bio->sectors, 1);
1215                         put_buf(r10_bio);
1216                         break;
1217                 } else {
1218                         r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
1219                         put_buf(r10_bio);
1220                         r10_bio = r10_bio2;
1221                 }
1222         }
1223         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1224         return 0;
1225 }
1226
1227 /*
1228  * Note: sync and recover and handled very differently for raid10
1229  * This code is for resync.
1230  * For resync, we read through virtual addresses and read all blocks.
1231  * If there is any error, we schedule a write.  The lowest numbered
1232  * drive is authoritative.
1233  * However requests come for physical address, so we need to map.
1234  * For every physical address there are raid_disks/copies virtual addresses,
1235  * which is always are least one, but is not necessarly an integer.
1236  * This means that a physical address can span multiple chunks, so we may
1237  * have to submit multiple io requests for a single sync request.
1238  */
1239 /*
1240  * We check if all blocks are in-sync and only write to blocks that
1241  * aren't in sync
1242  */
1243 static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1244 {
1245         conf_t *conf = mddev_to_conf(mddev);
1246         int i, first;
1247         struct bio *tbio, *fbio;
1248
1249         atomic_set(&r10_bio->remaining, 1);
1250
1251         /* find the first device with a block */
1252         for (i=0; i<conf->copies; i++)
1253                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1254                         break;
1255
1256         if (i == conf->copies)
1257                 goto done;
1258
1259         first = i;
1260         fbio = r10_bio->devs[i].bio;
1261
1262         /* now find blocks with errors */
1263         for (i=0 ; i < conf->copies ; i++) {
1264                 int  j, d;
1265                 int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
1266
1267                 tbio = r10_bio->devs[i].bio;
1268
1269                 if (tbio->bi_end_io != end_sync_read)
1270                         continue;
1271                 if (i == first)
1272                         continue;
1273                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1274                         /* We know that the bi_io_vec layout is the same for
1275                          * both 'first' and 'i', so we just compare them.
1276                          * All vec entries are PAGE_SIZE;
1277                          */
1278                         for (j = 0; j < vcnt; j++)
1279                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1280                                            page_address(tbio->bi_io_vec[j].bv_page),
1281                                            PAGE_SIZE))
1282                                         break;
1283                         if (j == vcnt)
1284                                 continue;
1285                         mddev->resync_mismatches += r10_bio->sectors;
1286                 }
1287                 if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1288                         /* Don't fix anything. */
1289                         continue;
1290                 /* Ok, we need to write this bio
1291                  * First we need to fixup bv_offset, bv_len and
1292                  * bi_vecs, as the read request might have corrupted these
1293                  */
1294                 tbio->bi_vcnt = vcnt;
1295                 tbio->bi_size = r10_bio->sectors << 9;
1296                 tbio->bi_idx = 0;
1297                 tbio->bi_phys_segments = 0;
1298                 tbio->bi_hw_segments = 0;
1299                 tbio->bi_hw_front_size = 0;
1300                 tbio->bi_hw_back_size = 0;
1301                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1302                 tbio->bi_flags |= 1 << BIO_UPTODATE;
1303                 tbio->bi_next = NULL;
1304                 tbio->bi_rw = WRITE;
1305                 tbio->bi_private = r10_bio;
1306                 tbio->bi_sector = r10_bio->devs[i].addr;
1307
1308                 for (j=0; j < vcnt ; j++) {
1309                         tbio->bi_io_vec[j].bv_offset = 0;
1310                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1311
1312                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1313                                page_address(fbio->bi_io_vec[j].bv_page),
1314                                PAGE_SIZE);
1315                 }
1316                 tbio->bi_end_io = end_sync_write;
1317
1318                 d = r10_bio->devs[i].devnum;
1319                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1320                 atomic_inc(&r10_bio->remaining);
1321                 md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1322
1323                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1324                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1325                 generic_make_request(tbio);
1326         }
1327
1328 done:
1329         if (atomic_dec_and_test(&r10_bio->remaining)) {
1330                 md_done_sync(mddev, r10_bio->sectors, 1);
1331                 put_buf(r10_bio);
1332         }
1333 }
1334
1335 /*
1336  * Now for the recovery code.
1337  * Recovery happens across physical sectors.
1338  * We recover all non-is_sync drives by finding the virtual address of
1339  * each, and then choose a working drive that also has that virt address.
1340  * There is a separate r10_bio for each non-in_sync drive.
1341  * Only the first two slots are in use. The first for reading,
1342  * The second for writing.
1343  *
1344  */
1345
1346 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1347 {
1348         conf_t *conf = mddev_to_conf(mddev);
1349         int i, d;
1350         struct bio *bio, *wbio;
1351
1352
1353         /* move the pages across to the second bio
1354          * and submit the write request
1355          */
1356         bio = r10_bio->devs[0].bio;
1357         wbio = r10_bio->devs[1].bio;
1358         for (i=0; i < wbio->bi_vcnt; i++) {
1359                 struct page *p = bio->bi_io_vec[i].bv_page;
1360                 bio->bi_io_vec[i].bv_page = wbio->bi_io_vec[i].bv_page;
1361                 wbio->bi_io_vec[i].bv_page = p;
1362         }
1363         d = r10_bio->devs[1].devnum;
1364
1365         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1366         md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
1367         if (test_bit(R10BIO_Uptodate, &r10_bio->state))
1368                 generic_make_request(wbio);
1369         else
1370                 bio_endio(wbio, wbio->bi_size, -EIO);
1371 }
1372
1373
1374 /*
1375  * This is a kernel thread which:
1376  *
1377  *      1.      Retries failed read operations on working mirrors.
1378  *      2.      Updates the raid superblock when problems encounter.
1379  *      3.      Performs writes following reads for array synchronising.
1380  */
1381
1382 static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
1383 {
1384         int sect = 0; /* Offset from r10_bio->sector */
1385         int sectors = r10_bio->sectors;
1386         mdk_rdev_t*rdev;
1387         while(sectors) {
1388                 int s = sectors;
1389                 int sl = r10_bio->read_slot;
1390                 int success = 0;
1391                 int start;
1392
1393                 if (s > (PAGE_SIZE>>9))
1394                         s = PAGE_SIZE >> 9;
1395
1396                 rcu_read_lock();
1397                 do {
1398                         int d = r10_bio->devs[sl].devnum;
1399                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1400                         if (rdev &&
1401                             test_bit(In_sync, &rdev->flags)) {
1402                                 atomic_inc(&rdev->nr_pending);
1403                                 rcu_read_unlock();
1404                                 success = sync_page_io(rdev->bdev,
1405                                                        r10_bio->devs[sl].addr +
1406                                                        sect + rdev->data_offset,
1407                                                        s<<9,
1408                                                        conf->tmppage, READ);
1409                                 rdev_dec_pending(rdev, mddev);
1410                                 rcu_read_lock();
1411                                 if (success)
1412                                         break;
1413                         }
1414                         sl++;
1415                         if (sl == conf->copies)
1416                                 sl = 0;
1417                 } while (!success && sl != r10_bio->read_slot);
1418                 rcu_read_unlock();
1419
1420                 if (!success) {
1421                         /* Cannot read from anywhere -- bye bye array */
1422                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
1423                         md_error(mddev, conf->mirrors[dn].rdev);
1424                         break;
1425                 }
1426
1427                 start = sl;
1428                 /* write it back and re-read */
1429                 rcu_read_lock();
1430                 while (sl != r10_bio->read_slot) {
1431                         int d;
1432                         if (sl==0)
1433                                 sl = conf->copies;
1434                         sl--;
1435                         d = r10_bio->devs[sl].devnum;
1436                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1437                         if (rdev &&
1438                             test_bit(In_sync, &rdev->flags)) {
1439                                 atomic_inc(&rdev->nr_pending);
1440                                 rcu_read_unlock();
1441                                 atomic_add(s, &rdev->corrected_errors);
1442                                 if (sync_page_io(rdev->bdev,
1443                                                  r10_bio->devs[sl].addr +
1444                                                  sect + rdev->data_offset,
1445                                                  s<<9, conf->tmppage, WRITE)
1446                                     == 0)
1447                                         /* Well, this device is dead */
1448                                         md_error(mddev, rdev);
1449                                 rdev_dec_pending(rdev, mddev);
1450                                 rcu_read_lock();
1451                         }
1452                 }
1453                 sl = start;
1454                 while (sl != r10_bio->read_slot) {
1455                         int d;
1456                         if (sl==0)
1457                                 sl = conf->copies;
1458                         sl--;
1459                         d = r10_bio->devs[sl].devnum;
1460                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1461                         if (rdev &&
1462                             test_bit(In_sync, &rdev->flags)) {
1463                                 char b[BDEVNAME_SIZE];
1464                                 atomic_inc(&rdev->nr_pending);
1465                                 rcu_read_unlock();
1466                                 if (sync_page_io(rdev->bdev,
1467                                                  r10_bio->devs[sl].addr +
1468                                                  sect + rdev->data_offset,
1469                                                  s<<9, conf->tmppage, READ) == 0)
1470                                         /* Well, this device is dead */
1471                                         md_error(mddev, rdev);
1472                                 else
1473                                         printk(KERN_INFO
1474                                                "raid10:%s: read error corrected"
1475                                                " (%d sectors at %llu on %s)\n",
1476                                                mdname(mddev), s,
1477                                                (unsigned long long)(sect+
1478                                                     rdev->data_offset),
1479                                                bdevname(rdev->bdev, b));
1480
1481                                 rdev_dec_pending(rdev, mddev);
1482                                 rcu_read_lock();
1483                         }
1484                 }
1485                 rcu_read_unlock();
1486
1487                 sectors -= s;
1488                 sect += s;
1489         }
1490 }
1491
1492 static void raid10d(mddev_t *mddev)
1493 {
1494         r10bio_t *r10_bio;
1495         struct bio *bio;
1496         unsigned long flags;
1497         conf_t *conf = mddev_to_conf(mddev);
1498         struct list_head *head = &conf->retry_list;
1499         int unplug=0;
1500         mdk_rdev_t *rdev;
1501
1502         md_check_recovery(mddev);
1503
1504         for (;;) {
1505                 char b[BDEVNAME_SIZE];
1506                 spin_lock_irqsave(&conf->device_lock, flags);
1507
1508                 if (conf->pending_bio_list.head) {
1509                         bio = bio_list_get(&conf->pending_bio_list);
1510                         blk_remove_plug(mddev->queue);
1511                         spin_unlock_irqrestore(&conf->device_lock, flags);
1512                         /* flush any pending bitmap writes to disk before proceeding w/ I/O */
1513                         if (bitmap_unplug(mddev->bitmap) != 0)
1514                                 printk("%s: bitmap file write failed!\n", mdname(mddev));
1515
1516                         while (bio) { /* submit pending writes */
1517                                 struct bio *next = bio->bi_next;
1518                                 bio->bi_next = NULL;
1519                                 generic_make_request(bio);
1520                                 bio = next;
1521                         }
1522                         unplug = 1;
1523
1524                         continue;
1525                 }
1526
1527                 if (list_empty(head))
1528                         break;
1529                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
1530                 list_del(head->prev);
1531                 conf->nr_queued--;
1532                 spin_unlock_irqrestore(&conf->device_lock, flags);
1533
1534                 mddev = r10_bio->mddev;
1535                 conf = mddev_to_conf(mddev);
1536                 if (test_bit(R10BIO_IsSync, &r10_bio->state)) {
1537                         sync_request_write(mddev, r10_bio);
1538                         unplug = 1;
1539                 } else  if (test_bit(R10BIO_IsRecover, &r10_bio->state)) {
1540                         recovery_request_write(mddev, r10_bio);
1541                         unplug = 1;
1542                 } else {
1543                         int mirror;
1544                         /* we got a read error. Maybe the drive is bad.  Maybe just
1545                          * the block and we can fix it.
1546                          * We freeze all other IO, and try reading the block from
1547                          * other devices.  When we find one, we re-write
1548                          * and check it that fixes the read error.
1549                          * This is all done synchronously while the array is
1550                          * frozen.
1551                          */
1552                         if (mddev->ro == 0) {
1553                                 freeze_array(conf);
1554                                 fix_read_error(conf, mddev, r10_bio);
1555                                 unfreeze_array(conf);
1556                         }
1557
1558                         bio = r10_bio->devs[r10_bio->read_slot].bio;
1559                         r10_bio->devs[r10_bio->read_slot].bio =
1560                                 mddev->ro ? IO_BLOCKED : NULL;
1561                         bio_put(bio);
1562                         mirror = read_balance(conf, r10_bio);
1563                         if (mirror == -1) {
1564                                 printk(KERN_ALERT "raid10: %s: unrecoverable I/O"
1565                                        " read error for block %llu\n",
1566                                        bdevname(bio->bi_bdev,b),
1567                                        (unsigned long long)r10_bio->sector);
1568                                 raid_end_bio_io(r10_bio);
1569                         } else {
1570                                 const int do_sync = bio_sync(r10_bio->master_bio);
1571                                 rdev = conf->mirrors[mirror].rdev;
1572                                 if (printk_ratelimit())
1573                                         printk(KERN_ERR "raid10: %s: redirecting sector %llu to"
1574                                                " another mirror\n",
1575                                                bdevname(rdev->bdev,b),
1576                                                (unsigned long long)r10_bio->sector);
1577                                 bio = bio_clone(r10_bio->master_bio, GFP_NOIO);
1578                                 r10_bio->devs[r10_bio->read_slot].bio = bio;
1579                                 bio->bi_sector = r10_bio->devs[r10_bio->read_slot].addr
1580                                         + rdev->data_offset;
1581                                 bio->bi_bdev = rdev->bdev;
1582                                 bio->bi_rw = READ | do_sync;
1583                                 bio->bi_private = r10_bio;
1584                                 bio->bi_end_io = raid10_end_read_request;
1585                                 unplug = 1;
1586                                 generic_make_request(bio);
1587                         }
1588                 }
1589         }
1590         spin_unlock_irqrestore(&conf->device_lock, flags);
1591         if (unplug)
1592                 unplug_slaves(mddev);
1593 }
1594
1595
1596 static int init_resync(conf_t *conf)
1597 {
1598         int buffs;
1599
1600         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1601         BUG_ON(conf->r10buf_pool);
1602         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
1603         if (!conf->r10buf_pool)
1604                 return -ENOMEM;
1605         conf->next_resync = 0;
1606         return 0;
1607 }
1608
1609 /*
1610  * perform a "sync" on one "block"
1611  *
1612  * We need to make sure that no normal I/O request - particularly write
1613  * requests - conflict with active sync requests.
1614  *
1615  * This is achieved by tracking pending requests and a 'barrier' concept
1616  * that can be installed to exclude normal IO requests.
1617  *
1618  * Resync and recovery are handled very differently.
1619  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
1620  *
1621  * For resync, we iterate over virtual addresses, read all copies,
1622  * and update if there are differences.  If only one copy is live,
1623  * skip it.
1624  * For recovery, we iterate over physical addresses, read a good
1625  * value for each non-in_sync drive, and over-write.
1626  *
1627  * So, for recovery we may have several outstanding complex requests for a
1628  * given address, one for each out-of-sync device.  We model this by allocating
1629  * a number of r10_bio structures, one for each out-of-sync device.
1630  * As we setup these structures, we collect all bio's together into a list
1631  * which we then process collectively to add pages, and then process again
1632  * to pass to generic_make_request.
1633  *
1634  * The r10_bio structures are linked using a borrowed master_bio pointer.
1635  * This link is counted in ->remaining.  When the r10_bio that points to NULL
1636  * has its remaining count decremented to 0, the whole complex operation
1637  * is complete.
1638  *
1639  */
1640
1641 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1642 {
1643         conf_t *conf = mddev_to_conf(mddev);
1644         r10bio_t *r10_bio;
1645         struct bio *biolist = NULL, *bio;
1646         sector_t max_sector, nr_sectors;
1647         int disk;
1648         int i;
1649         int max_sync;
1650         int sync_blocks;
1651
1652         sector_t sectors_skipped = 0;
1653         int chunks_skipped = 0;
1654
1655         if (!conf->r10buf_pool)
1656                 if (init_resync(conf))
1657                         return 0;
1658
1659  skipped:
1660         max_sector = mddev->size << 1;
1661         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1662                 max_sector = mddev->resync_max_sectors;
1663         if (sector_nr >= max_sector) {
1664                 /* If we aborted, we need to abort the
1665                  * sync on the 'current' bitmap chucks (there can
1666                  * be several when recovering multiple devices).
1667                  * as we may have started syncing it but not finished.
1668                  * We can find the current address in
1669                  * mddev->curr_resync, but for recovery,
1670                  * we need to convert that to several
1671                  * virtual addresses.
1672                  */
1673                 if (mddev->curr_resync < max_sector) { /* aborted */
1674                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1675                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1676                                                 &sync_blocks, 1);
1677                         else for (i=0; i<conf->raid_disks; i++) {
1678                                 sector_t sect =
1679                                         raid10_find_virt(conf, mddev->curr_resync, i);
1680                                 bitmap_end_sync(mddev->bitmap, sect,
1681                                                 &sync_blocks, 1);
1682                         }
1683                 } else /* completed sync */
1684                         conf->fullsync = 0;
1685
1686                 bitmap_close_sync(mddev->bitmap);
1687                 close_sync(conf);
1688                 *skipped = 1;
1689                 return sectors_skipped;
1690         }
1691         if (chunks_skipped >= conf->raid_disks) {
1692                 /* if there has been nothing to do on any drive,
1693                  * then there is nothing to do at all..
1694                  */
1695                 *skipped = 1;
1696                 return (max_sector - sector_nr) + sectors_skipped;
1697         }
1698
1699         /* make sure whole request will fit in a chunk - if chunks
1700          * are meaningful
1701          */
1702         if (conf->near_copies < conf->raid_disks &&
1703             max_sector > (sector_nr | conf->chunk_mask))
1704                 max_sector = (sector_nr | conf->chunk_mask) + 1;
1705         /*
1706          * If there is non-resync activity waiting for us then
1707          * put in a delay to throttle resync.
1708          */
1709         if (!go_faster && conf->nr_waiting)
1710                 msleep_interruptible(1000);
1711
1712         /* Again, very different code for resync and recovery.
1713          * Both must result in an r10bio with a list of bios that
1714          * have bi_end_io, bi_sector, bi_bdev set,
1715          * and bi_private set to the r10bio.
1716          * For recovery, we may actually create several r10bios
1717          * with 2 bios in each, that correspond to the bios in the main one.
1718          * In this case, the subordinate r10bios link back through a
1719          * borrowed master_bio pointer, and the counter in the master
1720          * includes a ref from each subordinate.
1721          */
1722         /* First, we decide what to do and set ->bi_end_io
1723          * To end_sync_read if we want to read, and
1724          * end_sync_write if we will want to write.
1725          */
1726
1727         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
1728         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1729                 /* recovery... the complicated one */
1730                 int i, j, k;
1731                 r10_bio = NULL;
1732
1733                 for (i=0 ; i<conf->raid_disks; i++)
1734                         if (conf->mirrors[i].rdev &&
1735                             !test_bit(In_sync, &conf->mirrors[i].rdev->flags)) {
1736                                 int still_degraded = 0;
1737                                 /* want to reconstruct this device */
1738                                 r10bio_t *rb2 = r10_bio;
1739                                 sector_t sect = raid10_find_virt(conf, sector_nr, i);
1740                                 int must_sync;
1741                                 /* Unless we are doing a full sync, we only need
1742                                  * to recover the block if it is set in the bitmap
1743                                  */
1744                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1745                                                               &sync_blocks, 1);
1746                                 if (sync_blocks < max_sync)
1747                                         max_sync = sync_blocks;
1748                                 if (!must_sync &&
1749                                     !conf->fullsync) {
1750                                         /* yep, skip the sync_blocks here, but don't assume
1751                                          * that there will never be anything to do here
1752                                          */
1753                                         chunks_skipped = -1;
1754                                         continue;
1755                                 }
1756
1757                                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1758                                 raise_barrier(conf, rb2 != NULL);
1759                                 atomic_set(&r10_bio->remaining, 0);
1760
1761                                 r10_bio->master_bio = (struct bio*)rb2;
1762                                 if (rb2)
1763                                         atomic_inc(&rb2->remaining);
1764                                 r10_bio->mddev = mddev;
1765                                 set_bit(R10BIO_IsRecover, &r10_bio->state);
1766                                 r10_bio->sector = sect;
1767
1768                                 raid10_find_phys(conf, r10_bio);
1769                                 /* Need to check if this section will still be
1770                                  * degraded
1771                                  */
1772                                 for (j=0; j<conf->copies;j++) {
1773                                         int d = r10_bio->devs[j].devnum;
1774                                         if (conf->mirrors[d].rdev == NULL ||
1775                                             test_bit(Faulty, &conf->mirrors[d].rdev->flags)) {
1776                                                 still_degraded = 1;
1777                                                 break;
1778                                         }
1779                                 }
1780                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1781                                                               &sync_blocks, still_degraded);
1782
1783                                 for (j=0; j<conf->copies;j++) {
1784                                         int d = r10_bio->devs[j].devnum;
1785                                         if (conf->mirrors[d].rdev &&
1786                                             test_bit(In_sync, &conf->mirrors[d].rdev->flags)) {
1787                                                 /* This is where we read from */
1788                                                 bio = r10_bio->devs[0].bio;
1789                                                 bio->bi_next = biolist;
1790                                                 biolist = bio;
1791                                                 bio->bi_private = r10_bio;
1792                                                 bio->bi_end_io = end_sync_read;
1793                                                 bio->bi_rw = READ;
1794                                                 bio->bi_sector = r10_bio->devs[j].addr +
1795                                                         conf->mirrors[d].rdev->data_offset;
1796                                                 bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1797                                                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1798                                                 atomic_inc(&r10_bio->remaining);
1799                                                 /* and we write to 'i' */
1800
1801                                                 for (k=0; k<conf->copies; k++)
1802                                                         if (r10_bio->devs[k].devnum == i)
1803                                                                 break;
1804                                                 bio = r10_bio->devs[1].bio;
1805                                                 bio->bi_next = biolist;
1806                                                 biolist = bio;
1807                                                 bio->bi_private = r10_bio;
1808                                                 bio->bi_end_io = end_sync_write;
1809                                                 bio->bi_rw = WRITE;
1810                                                 bio->bi_sector = r10_bio->devs[k].addr +
1811                                                         conf->mirrors[i].rdev->data_offset;
1812                                                 bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1813
1814                                                 r10_bio->devs[0].devnum = d;
1815                                                 r10_bio->devs[1].devnum = i;
1816
1817                                                 break;
1818                                         }
1819                                 }
1820                                 if (j == conf->copies) {
1821                                         /* Cannot recover, so abort the recovery */
1822                                         put_buf(r10_bio);
1823                                         r10_bio = rb2;
1824                                         if (!test_and_set_bit(MD_RECOVERY_ERR, &mddev->recovery))
1825                                                 printk(KERN_INFO "raid10: %s: insufficient working devices for recovery.\n",
1826                                                        mdname(mddev));
1827                                         break;
1828                                 }
1829                         }
1830                 if (biolist == NULL) {
1831                         while (r10_bio) {
1832                                 r10bio_t *rb2 = r10_bio;
1833                                 r10_bio = (r10bio_t*) rb2->master_bio;
1834                                 rb2->master_bio = NULL;
1835                                 put_buf(rb2);
1836                         }
1837                         goto giveup;
1838                 }
1839         } else {
1840                 /* resync. Schedule a read for every block at this virt offset */
1841                 int count = 0;
1842
1843                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1844                                        &sync_blocks, mddev->degraded) &&
1845                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1846                         /* We can skip this block */
1847                         *skipped = 1;
1848                         return sync_blocks + sectors_skipped;
1849                 }
1850                 if (sync_blocks < max_sync)
1851                         max_sync = sync_blocks;
1852                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1853
1854                 r10_bio->mddev = mddev;
1855                 atomic_set(&r10_bio->remaining, 0);
1856                 raise_barrier(conf, 0);
1857                 conf->next_resync = sector_nr;
1858
1859                 r10_bio->master_bio = NULL;
1860                 r10_bio->sector = sector_nr;
1861                 set_bit(R10BIO_IsSync, &r10_bio->state);
1862                 raid10_find_phys(conf, r10_bio);
1863                 r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
1864
1865                 for (i=0; i<conf->copies; i++) {
1866                         int d = r10_bio->devs[i].devnum;
1867                         bio = r10_bio->devs[i].bio;
1868                         bio->bi_end_io = NULL;
1869                         if (conf->mirrors[d].rdev == NULL ||
1870                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
1871                                 continue;
1872                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1873                         atomic_inc(&r10_bio->remaining);
1874                         bio->bi_next = biolist;
1875                         biolist = bio;
1876                         bio->bi_private = r10_bio;
1877                         bio->bi_end_io = end_sync_read;
1878                         bio->bi_rw = READ;
1879                         bio->bi_sector = r10_bio->devs[i].addr +
1880                                 conf->mirrors[d].rdev->data_offset;
1881                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1882                         count++;
1883                 }
1884
1885                 if (count < 2) {
1886                         for (i=0; i<conf->copies; i++) {
1887                                 int d = r10_bio->devs[i].devnum;
1888                                 if (r10_bio->devs[i].bio->bi_end_io)
1889                                         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1890                         }
1891                         put_buf(r10_bio);
1892                         biolist = NULL;
1893                         goto giveup;
1894                 }
1895         }
1896
1897         for (bio = biolist; bio ; bio=bio->bi_next) {
1898
1899                 bio->bi_flags &= ~(BIO_POOL_MASK - 1);
1900                 if (bio->bi_end_io)
1901                         bio->bi_flags |= 1 << BIO_UPTODATE;
1902                 bio->bi_vcnt = 0;
1903                 bio->bi_idx = 0;
1904                 bio->bi_phys_segments = 0;
1905                 bio->bi_hw_segments = 0;
1906                 bio->bi_size = 0;
1907         }
1908
1909         nr_sectors = 0;
1910         if (sector_nr + max_sync < max_sector)
1911                 max_sector = sector_nr + max_sync;
1912         do {
1913                 struct page *page;
1914                 int len = PAGE_SIZE;
1915                 disk = 0;
1916                 if (sector_nr + (len>>9) > max_sector)
1917                         len = (max_sector - sector_nr) << 9;
1918                 if (len == 0)
1919                         break;
1920                 for (bio= biolist ; bio ; bio=bio->bi_next) {
1921                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1922                         if (bio_add_page(bio, page, len, 0) == 0) {
1923                                 /* stop here */
1924                                 struct bio *bio2;
1925                                 bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1926                                 for (bio2 = biolist; bio2 && bio2 != bio; bio2 = bio2->bi_next) {
1927                                         /* remove last page from this bio */
1928                                         bio2->bi_vcnt--;
1929                                         bio2->bi_size -= len;
1930                                         bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
1931                                 }
1932                                 goto bio_full;
1933                         }
1934                         disk = i;
1935                 }
1936                 nr_sectors += len>>9;
1937                 sector_nr += len>>9;
1938         } while (biolist->bi_vcnt < RESYNC_PAGES);
1939  bio_full:
1940         r10_bio->sectors = nr_sectors;
1941
1942         while (biolist) {
1943                 bio = biolist;
1944                 biolist = biolist->bi_next;
1945
1946                 bio->bi_next = NULL;
1947                 r10_bio = bio->bi_private;
1948                 r10_bio->sectors = nr_sectors;
1949
1950                 if (bio->bi_end_io == end_sync_read) {
1951                         md_sync_acct(bio->bi_bdev, nr_sectors);
1952                         generic_make_request(bio);
1953                 }
1954         }
1955
1956         if (sectors_skipped)
1957                 /* pretend they weren't skipped, it makes
1958                  * no important difference in this case
1959                  */
1960                 md_done_sync(mddev, sectors_skipped, 1);
1961
1962         return sectors_skipped + nr_sectors;
1963  giveup:
1964         /* There is nowhere to write, so all non-sync
1965          * drives must be failed, so try the next chunk...
1966          */
1967         {
1968         sector_t sec = max_sector - sector_nr;
1969         sectors_skipped += sec;
1970         chunks_skipped ++;
1971         sector_nr = max_sector;
1972         goto skipped;
1973         }
1974 }
1975
1976 static int run(mddev_t *mddev)
1977 {
1978         conf_t *conf;
1979         int i, disk_idx;
1980         mirror_info_t *disk;
1981         mdk_rdev_t *rdev;
1982         struct list_head *tmp;
1983         int nc, fc, fo;
1984         sector_t stride, size;
1985
1986         if (mddev->chunk_size == 0) {
1987                 printk(KERN_ERR "md/raid10: non-zero chunk size required.\n");
1988                 return -EINVAL;
1989         }
1990
1991         nc = mddev->layout & 255;
1992         fc = (mddev->layout >> 8) & 255;
1993         fo = mddev->layout & (1<<16);
1994         if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
1995             (mddev->layout >> 17)) {
1996                 printk(KERN_ERR "raid10: %s: unsupported raid10 layout: 0x%8x\n",
1997                        mdname(mddev), mddev->layout);
1998                 goto out;
1999         }
2000         /*
2001          * copy the already verified devices into our private RAID10
2002          * bookkeeping area. [whatever we allocate in run(),
2003          * should be freed in stop()]
2004          */
2005         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
2006         mddev->private = conf;
2007         if (!conf) {
2008                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2009                         mdname(mddev));
2010                 goto out;
2011         }
2012         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
2013                                  GFP_KERNEL);
2014         if (!conf->mirrors) {
2015                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2016                        mdname(mddev));
2017                 goto out_free_conf;
2018         }
2019
2020         conf->tmppage = alloc_page(GFP_KERNEL);
2021         if (!conf->tmppage)
2022                 goto out_free_conf;
2023
2024         conf->near_copies = nc;
2025         conf->far_copies = fc;
2026         conf->copies = nc*fc;
2027         conf->far_offset = fo;
2028         conf->chunk_mask = (sector_t)(mddev->chunk_size>>9)-1;
2029         conf->chunk_shift = ffz(~mddev->chunk_size) - 9;
2030         if (fo)
2031                 conf->stride = 1 << conf->chunk_shift;
2032         else {
2033                 stride = mddev->size >> (conf->chunk_shift-1);
2034                 sector_div(stride, fc);
2035                 conf->stride = stride << conf->chunk_shift;
2036         }
2037         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
2038                                                 r10bio_pool_free, conf);
2039         if (!conf->r10bio_pool) {
2040                 printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
2041                         mdname(mddev));
2042                 goto out_free_conf;
2043         }
2044
2045         ITERATE_RDEV(mddev, rdev, tmp) {
2046                 disk_idx = rdev->raid_disk;
2047                 if (disk_idx >= mddev->raid_disks
2048                     || disk_idx < 0)
2049                         continue;
2050                 disk = conf->mirrors + disk_idx;
2051
2052                 disk->rdev = rdev;
2053
2054                 blk_queue_stack_limits(mddev->queue,
2055                                        rdev->bdev->bd_disk->queue);
2056                 /* as we don't honour merge_bvec_fn, we must never risk
2057                  * violating it, so limit ->max_sector to one PAGE, as
2058                  * a one page request is never in violation.
2059                  */
2060                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
2061                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
2062                         mddev->queue->max_sectors = (PAGE_SIZE>>9);
2063
2064                 disk->head_position = 0;
2065         }
2066         conf->raid_disks = mddev->raid_disks;
2067         conf->mddev = mddev;
2068         spin_lock_init(&conf->device_lock);
2069         INIT_LIST_HEAD(&conf->retry_list);
2070
2071         spin_lock_init(&conf->resync_lock);
2072         init_waitqueue_head(&conf->wait_barrier);
2073
2074         /* need to check that every block has at least one working mirror */
2075         if (!enough(conf)) {
2076                 printk(KERN_ERR "raid10: not enough operational mirrors for %s\n",
2077                        mdname(mddev));
2078                 goto out_free_conf;
2079         }
2080
2081         mddev->degraded = 0;
2082         for (i = 0; i < conf->raid_disks; i++) {
2083
2084                 disk = conf->mirrors + i;
2085
2086                 if (!disk->rdev ||
2087                     !test_bit(In_sync, &disk->rdev->flags)) {
2088                         disk->head_position = 0;
2089                         mddev->degraded++;
2090                 }
2091         }
2092
2093
2094         mddev->thread = md_register_thread(raid10d, mddev, "%s_raid10");
2095         if (!mddev->thread) {
2096                 printk(KERN_ERR
2097                        "raid10: couldn't allocate thread for %s\n",
2098                        mdname(mddev));
2099                 goto out_free_conf;
2100         }
2101
2102         printk(KERN_INFO
2103                 "raid10: raid set %s active with %d out of %d devices\n",
2104                 mdname(mddev), mddev->raid_disks - mddev->degraded,
2105                 mddev->raid_disks);
2106         /*
2107          * Ok, everything is just fine now
2108          */
2109         if (conf->far_offset) {
2110                 size = mddev->size >> (conf->chunk_shift-1);
2111                 size *= conf->raid_disks;
2112                 size <<= conf->chunk_shift;
2113                 sector_div(size, conf->far_copies);
2114         } else
2115                 size = conf->stride * conf->raid_disks;
2116         sector_div(size, conf->near_copies);
2117         mddev->array_size = size/2;
2118         mddev->resync_max_sectors = size;
2119
2120         mddev->queue->unplug_fn = raid10_unplug;
2121         mddev->queue->issue_flush_fn = raid10_issue_flush;
2122         mddev->queue->backing_dev_info.congested_fn = raid10_congested;
2123         mddev->queue->backing_dev_info.congested_data = mddev;
2124
2125         /* Calculate max read-ahead size.
2126          * We need to readahead at least twice a whole stripe....
2127          * maybe...
2128          */
2129         {
2130                 int stripe = conf->raid_disks * (mddev->chunk_size / PAGE_SIZE);
2131                 stripe /= conf->near_copies;
2132                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
2133                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
2134         }
2135
2136         if (conf->near_copies < mddev->raid_disks)
2137                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
2138         return 0;
2139
2140 out_free_conf:
2141         if (conf->r10bio_pool)
2142                 mempool_destroy(conf->r10bio_pool);
2143         safe_put_page(conf->tmppage);
2144         kfree(conf->mirrors);
2145         kfree(conf);
2146         mddev->private = NULL;
2147 out:
2148         return -EIO;
2149 }
2150
2151 static int stop(mddev_t *mddev)
2152 {
2153         conf_t *conf = mddev_to_conf(mddev);
2154
2155         md_unregister_thread(mddev->thread);
2156         mddev->thread = NULL;
2157         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2158         if (conf->r10bio_pool)
2159                 mempool_destroy(conf->r10bio_pool);
2160         kfree(conf->mirrors);
2161         kfree(conf);
2162         mddev->private = NULL;
2163         return 0;
2164 }
2165
2166 static void raid10_quiesce(mddev_t *mddev, int state)
2167 {
2168         conf_t *conf = mddev_to_conf(mddev);
2169
2170         switch(state) {
2171         case 1:
2172                 raise_barrier(conf, 0);
2173                 break;
2174         case 0:
2175                 lower_barrier(conf);
2176                 break;
2177         }
2178         if (mddev->thread) {
2179                 if (mddev->bitmap)
2180                         mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
2181                 else
2182                         mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
2183                 md_wakeup_thread(mddev->thread);
2184         }
2185 }
2186
2187 static struct mdk_personality raid10_personality =
2188 {
2189         .name           = "raid10",
2190         .level          = 10,
2191         .owner          = THIS_MODULE,
2192         .make_request   = make_request,
2193         .run            = run,
2194         .stop           = stop,
2195         .status         = status,
2196         .error_handler  = error,
2197         .hot_add_disk   = raid10_add_disk,
2198         .hot_remove_disk= raid10_remove_disk,
2199         .spare_active   = raid10_spare_active,
2200         .sync_request   = sync_request,
2201         .quiesce        = raid10_quiesce,
2202 };
2203
2204 static int __init raid_init(void)
2205 {
2206         return register_md_personality(&raid10_personality);
2207 }
2208
2209 static void raid_exit(void)
2210 {
2211         unregister_md_personality(&raid10_personality);
2212 }
2213
2214 module_init(raid_init);
2215 module_exit(raid_exit);
2216 MODULE_LICENSE("GPL");
2217 MODULE_ALIAS("md-personality-9"); /* RAID10 */
2218 MODULE_ALIAS("md-raid10");
2219 MODULE_ALIAS("md-level-10");