drivers/md/raid10.c

   1 /*
   2  * raid10.c : Multiple Devices driver for Linux
   3  *
   4  * Copyright (C) 2000-2004 Neil Brown
   5  *
   6  * RAID-10 support for md.
   7  *
   8  * Base on code in raid1.c.  See raid1.c for further copyright information.
   9  *
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/slab.h>
  22 #include <linux/delay.h>
  23 #include <linux/blkdev.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/ratelimit.h>
  26 #include "md.h"
  27 #include "raid10.h"
  28 #include "raid0.h"
  29 #include "bitmap.h"
  30
  31 /*
  32  * RAID10 provides a combination of RAID0 and RAID1 functionality.
  33  * The layout of data is defined by
  34  *    chunk_size
  35  *    raid_disks
  36  *    near_copies (stored in low byte of layout)
  37  *    far_copies (stored in second byte of layout)
  38  *    far_offset (stored in bit 16 of layout )
  39  *
  40  * The data to be stored is divided into chunks using chunksize.
  41  * Each device is divided into far_copies sections.
  42  * In each section, chunks are laid out in a style similar to raid0, but
  43  * near_copies copies of each chunk is stored (each on a different drive).
  44  * The starting device for each section is offset near_copies from the starting
  45  * device of the previous section.
  46  * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
  47  * drive.
  48  * near_copies and far_copies must be at least one, and their product is at most
  49  * raid_disks.
  50  *
  51  * If far_offset is true, then the far_copies are handled a bit differently.
  52  * The copies are still in different stripes, but instead of be very far apart
  53  * on disk, there are adjacent stripes.
  54  */
  55
  56 /*
  57  * Number of guaranteed r10bios in case of extreme VM load:
  58  */
  59 #define NR_RAID10_BIOS 256
  60
  61 static void allow_barrier(conf_t *conf);
  62 static void lower_barrier(conf_t *conf);
  63
  64 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
  65 {
  66         conf_t *conf = data;
  67         int size = offsetof(struct r10bio_s, devs[conf->copies]);
  68
  69         /* allocate a r10bio with room for raid_disks entries in the bios array */
  70         return kzalloc(size, gfp_flags);
  71 }
  72
  73 static void r10bio_pool_free(void *r10_bio, void *data)
  74 {
  75         kfree(r10_bio);
  76 }
  77
  78 /* Maximum size of each resync request */
  79 #define RESYNC_BLOCK_SIZE (64*1024)
  80 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  81 /* amount of memory to reserve for resync requests */
  82 #define RESYNC_WINDOW (1024*1024)
  83 /* maximum number of concurrent requests, memory permitting */
  84 #define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
  85
  86 /*
  87  * When performing a resync, we need to read and compare, so
  88  * we need as many pages are there are copies.
  89  * When performing a recovery, we need 2 bios, one for read,
  90  * one for write (we recover only one drive per r10buf)
  91  *
  92  */
  93 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
  94 {
  95         conf_t *conf = data;
  96         struct page *page;
  97         r10bio_t *r10_bio;
  98         struct bio *bio;
  99         int i, j;
 100         int nalloc;
 101
 102         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
 103         if (!r10_bio)
 104                 return NULL;
 105
 106         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
 107                 nalloc = conf->copies; /* resync */
 108         else
 109                 nalloc = 2; /* recovery */
 110
 111         /*
 112          * Allocate bios.
 113          */
 114         for (j = nalloc ; j-- ; ) {
 115                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 116                 if (!bio)
 117                         goto out_free_bio;
 118                 r10_bio->devs[j].bio = bio;
 119         }
 120         /*
 121          * Allocate RESYNC_PAGES data pages and attach them
 122          * where needed.
 123          */
 124         for (j = 0 ; j < nalloc; j++) {
 125                 bio = r10_bio->devs[j].bio;
 126                 for (i = 0; i < RESYNC_PAGES; i++) {
 127                         if (j == 1 && !test_bit(MD_RECOVERY_SYNC,
 128                                                 &conf->mddev->recovery)) {
 129                                 /* we can share bv_page's during recovery */
 130                                 struct bio *rbio = r10_bio->devs[0].bio;
 131                                 page = rbio->bi_io_vec[i].bv_page;
 132                                 get_page(page);
 133                         } else
 134                                 page = alloc_page(gfp_flags);
 135                         if (unlikely(!page))
 136                                 goto out_free_pages;
 137
 138                         bio->bi_io_vec[i].bv_page = page;
 139                 }
 140         }
 141
 142         return r10_bio;
 143
 144 out_free_pages:
 145         for ( ; i > 0 ; i--)
 146                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
 147         while (j--)
 148                 for (i = 0; i < RESYNC_PAGES ; i++)
 149                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
 150         j = -1;
 151 out_free_bio:
 152         while ( ++j < nalloc )
 153                 bio_put(r10_bio->devs[j].bio);
 154         r10bio_pool_free(r10_bio, conf);
 155         return NULL;
 156 }
 157
 158 static void r10buf_pool_free(void *__r10_bio, void *data)
 159 {
 160         int i;
 161         conf_t *conf = data;
 162         r10bio_t *r10bio = __r10_bio;
 163         int j;
 164
 165         for (j=0; j < conf->copies; j++) {
 166                 struct bio *bio = r10bio->devs[j].bio;
 167                 if (bio) {
 168                         for (i = 0; i < RESYNC_PAGES; i++) {
 169                                 safe_put_page(bio->bi_io_vec[i].bv_page);
 170                                 bio->bi_io_vec[i].bv_page = NULL;
 171                         }
 172                         bio_put(bio);
 173                 }
 174         }
 175         r10bio_pool_free(r10bio, conf);
 176 }
 177
 178 static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
 179 {
 180         int i;
 181
 182         for (i = 0; i < conf->copies; i++) {
 183                 struct bio **bio = & r10_bio->devs[i].bio;
 184                 if (*bio && *bio != IO_BLOCKED)
 185                         bio_put(*bio);
 186                 *bio = NULL;
 187         }
 188 }
 189
 190 static void free_r10bio(r10bio_t *r10_bio)
 191 {
 192         conf_t *conf = r10_bio->mddev->private;
 193
 194         /*
 195          * Wake up any possible resync thread that waits for the device
 196          * to go idle.
 197          */
 198         allow_barrier(conf);
 199
 200         put_all_bios(conf, r10_bio);
 201         mempool_free(r10_bio, conf->r10bio_pool);
 202 }
 203
 204 static void put_buf(r10bio_t *r10_bio)
 205 {
 206         conf_t *conf = r10_bio->mddev->private;
 207
 208         mempool_free(r10_bio, conf->r10buf_pool);
 209
 210         lower_barrier(conf);
 211 }
 212
 213 static void reschedule_retry(r10bio_t *r10_bio)
 214 {
 215         unsigned long flags;
 216         mddev_t *mddev = r10_bio->mddev;
 217         conf_t *conf = mddev->private;
 218
 219         spin_lock_irqsave(&conf->device_lock, flags);
 220         list_add(&r10_bio->retry_list, &conf->retry_list);
 221         conf->nr_queued ++;
 222         spin_unlock_irqrestore(&conf->device_lock, flags);
 223
 224         /* wake up frozen array... */
 225         wake_up(&conf->wait_barrier);
 226
 227         md_wakeup_thread(mddev->thread);
 228 }
 229
 230 /*
 231  * raid_end_bio_io() is called when we have finished servicing a mirrored
 232  * operation and are ready to return a success/failure code to the buffer
 233  * cache layer.
 234  */
 235 static void raid_end_bio_io(r10bio_t *r10_bio)
 236 {
 237         struct bio *bio = r10_bio->master_bio;
 238
 239         bio_endio(bio,
 240                 test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
 241         free_r10bio(r10_bio);
 242 }
 243
 244 /*
 245  * Update disk head position estimator based on IRQ completion info.
 246  */
 247 static inline void update_head_pos(int slot, r10bio_t *r10_bio)
 248 {
 249         conf_t *conf = r10_bio->mddev->private;
 250
 251         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
 252                 r10_bio->devs[slot].addr + (r10_bio->sectors);
 253 }
 254
 255 /*
 256  * Find the disk number which triggered given bio
 257  */
 258 static int find_bio_disk(conf_t *conf, r10bio_t *r10_bio, struct bio *bio)
 259 {
 260         int slot;
 261
 262         for (slot = 0; slot < conf->copies; slot++)
 263                 if (r10_bio->devs[slot].bio == bio)
 264                         break;
 265
 266         BUG_ON(slot == conf->copies);
 267         update_head_pos(slot, r10_bio);
 268
 269         return r10_bio->devs[slot].devnum;
 270 }
 271
 272 static void raid10_end_read_request(struct bio *bio, int error)
 273 {
 274         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 275         r10bio_t *r10_bio = bio->bi_private;
 276         int slot, dev;
 277         conf_t *conf = r10_bio->mddev->private;
 278
 279
 280         slot = r10_bio->read_slot;
 281         dev = r10_bio->devs[slot].devnum;
 282         /*
 283          * this branch is our 'one mirror IO has finished' event handler:
 284          */
 285         update_head_pos(slot, r10_bio);
 286
 287         if (uptodate) {
 288                 /*
 289                  * Set R10BIO_Uptodate in our master bio, so that
 290                  * we will return a good error code to the higher
 291                  * levels even if IO on some other mirrored buffer fails.
 292                  *
 293                  * The 'master' represents the composite IO operation to
 294                  * user-side. So if something waits for IO, then it will
 295                  * wait for the 'master' bio.
 296                  */
 297                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 298                 raid_end_bio_io(r10_bio);
 299                 rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 300         } else {
 301                 /*
 302                  * oops, read error - keep the refcount on the rdev
 303                  */
 304                 char b[BDEVNAME_SIZE];
 305                 printk_ratelimited(KERN_ERR
 306                                    "md/raid10:%s: %s: rescheduling sector %llu\n",
 307                                    mdname(conf->mddev),
 308                                    bdevname(conf->mirrors[dev].rdev->bdev, b),
 309                                    (unsigned long long)r10_bio->sector);
 310                 reschedule_retry(r10_bio);
 311         }
 312 }
 313
 314 static void raid10_end_write_request(struct bio *bio, int error)
 315 {
 316         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 317         r10bio_t *r10_bio = bio->bi_private;
 318         int dev;
 319         conf_t *conf = r10_bio->mddev->private;
 320
 321         dev = find_bio_disk(conf, r10_bio, bio);
 322
 323         /*
 324          * this branch is our 'one mirror IO has finished' event handler:
 325          */
 326         if (!uptodate) {
 327                 md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
 328                 /* an I/O failed, we can't clear the bitmap */
 329                 set_bit(R10BIO_Degraded, &r10_bio->state);
 330         } else
 331                 /*
 332                  * Set R10BIO_Uptodate in our master bio, so that
 333                  * we will return a good error code for to the higher
 334                  * levels even if IO on some other mirrored buffer fails.
 335                  *
 336                  * The 'master' represents the composite IO operation to
 337                  * user-side. So if something waits for IO, then it will
 338                  * wait for the 'master' bio.
 339                  */
 340                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 341
 342         /*
 343          *
 344          * Let's see if all mirrored write operations have finished
 345          * already.
 346          */
 347         if (atomic_dec_and_test(&r10_bio->remaining)) {
 348                 /* clear the bitmap if all writes complete successfully */
 349                 bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 350                                 r10_bio->sectors,
 351                                 !test_bit(R10BIO_Degraded, &r10_bio->state),
 352                                 0);
 353                 md_write_end(r10_bio->mddev);
 354                 raid_end_bio_io(r10_bio);
 355         }
 356
 357         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 358 }
 359
 360
 361 /*
 362  * RAID10 layout manager
 363  * As well as the chunksize and raid_disks count, there are two
 364  * parameters: near_copies and far_copies.
 365  * near_copies * far_copies must be <= raid_disks.
 366  * Normally one of these will be 1.
 367  * If both are 1, we get raid0.
 368  * If near_copies == raid_disks, we get raid1.
 369  *
 370  * Chunks are laid out in raid0 style with near_copies copies of the
 371  * first chunk, followed by near_copies copies of the next chunk and
 372  * so on.
 373  * If far_copies > 1, then after 1/far_copies of the array has been assigned
 374  * as described above, we start again with a device offset of near_copies.
 375  * So we effectively have another copy of the whole array further down all
 376  * the drives, but with blocks on different drives.
 377  * With this layout, and block is never stored twice on the one device.
 378  *
 379  * raid10_find_phys finds the sector offset of a given virtual sector
 380  * on each device that it is on.
 381  *
 382  * raid10_find_virt does the reverse mapping, from a device and a
 383  * sector offset to a virtual address
 384  */
 385
 386 static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
 387 {
 388         int n,f;
 389         sector_t sector;
 390         sector_t chunk;
 391         sector_t stripe;
 392         int dev;
 393
 394         int slot = 0;
 395
 396         /* now calculate first sector/dev */
 397         chunk = r10bio->sector >> conf->chunk_shift;
 398         sector = r10bio->sector & conf->chunk_mask;
 399
 400         chunk *= conf->near_copies;
 401         stripe = chunk;
 402         dev = sector_div(stripe, conf->raid_disks);
 403         if (conf->far_offset)
 404                 stripe *= conf->far_copies;
 405
 406         sector += stripe << conf->chunk_shift;
 407
 408         /* and calculate all the others */
 409         for (n=0; n < conf->near_copies; n++) {
 410                 int d = dev;
 411                 sector_t s = sector;
 412                 r10bio->devs[slot].addr = sector;
 413                 r10bio->devs[slot].devnum = d;
 414                 slot++;
 415
 416                 for (f = 1; f < conf->far_copies; f++) {
 417                         d += conf->near_copies;
 418                         if (d >= conf->raid_disks)
 419                                 d -= conf->raid_disks;
 420                         s += conf->stride;
 421                         r10bio->devs[slot].devnum = d;
 422                         r10bio->devs[slot].addr = s;
 423                         slot++;
 424                 }
 425                 dev++;
 426                 if (dev >= conf->raid_disks) {
 427                         dev = 0;
 428                         sector += (conf->chunk_mask + 1);
 429                 }
 430         }
 431         BUG_ON(slot != conf->copies);
 432 }
 433
 434 static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
 435 {
 436         sector_t offset, chunk, vchunk;
 437
 438         offset = sector & conf->chunk_mask;
 439         if (conf->far_offset) {
 440                 int fc;
 441                 chunk = sector >> conf->chunk_shift;
 442                 fc = sector_div(chunk, conf->far_copies);
 443                 dev -= fc * conf->near_copies;
 444                 if (dev < 0)
 445                         dev += conf->raid_disks;
 446         } else {
 447                 while (sector >= conf->stride) {
 448                         sector -= conf->stride;
 449                         if (dev < conf->near_copies)
 450                                 dev += conf->raid_disks - conf->near_copies;
 451                         else
 452                                 dev -= conf->near_copies;
 453                 }
 454                 chunk = sector >> conf->chunk_shift;
 455         }
 456         vchunk = chunk * conf->raid_disks + dev;
 457         sector_div(vchunk, conf->near_copies);
 458         return (vchunk << conf->chunk_shift) + offset;
 459 }
 460
 461 /**
 462  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
 463  *      @q: request queue
 464  *      @bvm: properties of new bio
 465  *      @biovec: the request that could be merged to it.
 466  *
 467  *      Return amount of bytes we can accept at this offset
 468  *      If near_copies == raid_disk, there are no striping issues,
 469  *      but in that case, the function isn't called at all.
 470  */
 471 static int raid10_mergeable_bvec(struct request_queue *q,
 472                                  struct bvec_merge_data *bvm,
 473                                  struct bio_vec *biovec)
 474 {
 475         mddev_t *mddev = q->queuedata;
 476         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 477         int max;
 478         unsigned int chunk_sectors = mddev->chunk_sectors;
 479         unsigned int bio_sectors = bvm->bi_size >> 9;
 480
 481         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
 482         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
 483         if (max <= biovec->bv_len && bio_sectors == 0)
 484                 return biovec->bv_len;
 485         else
 486                 return max;
 487 }
 488
 489 /*
 490  * This routine returns the disk from which the requested read should
 491  * be done. There is a per-array 'next expected sequential IO' sector
 492  * number - if this matches on the next IO then we use the last disk.
 493  * There is also a per-disk 'last know head position' sector that is
 494  * maintained from IRQ contexts, both the normal and the resync IO
 495  * completion handlers update this position correctly. If there is no
 496  * perfect sequential match then we pick the disk whose head is closest.
 497  *
 498  * If there are 2 mirrors in the same 2 devices, performance degrades
 499  * because position is mirror, not device based.
 500  *
 501  * The rdev for the device selected will have nr_pending incremented.
 502  */
 503
 504 /*
 505  * FIXME: possibly should rethink readbalancing and do it differently
 506  * depending on near_copies / far_copies geometry.
 507  */
 508 static int read_balance(conf_t *conf, r10bio_t *r10_bio)
 509 {
 510         const sector_t this_sector = r10_bio->sector;
 511         int disk, slot;
 512         const int sectors = r10_bio->sectors;
 513         sector_t new_distance, best_dist;
 514         mdk_rdev_t *rdev;
 515         int do_balance;
 516         int best_slot;
 517
 518         raid10_find_phys(conf, r10_bio);
 519         rcu_read_lock();
 520 retry:
 521         best_slot = -1;
 522         best_dist = MaxSector;
 523         do_balance = 1;
 524         /*
 525          * Check if we can balance. We can balance on the whole
 526          * device if no resync is going on (recovery is ok), or below
 527          * the resync window. We take the first readable disk when
 528          * above the resync window.
 529          */
 530         if (conf->mddev->recovery_cp < MaxSector
 531             && (this_sector + sectors >= conf->next_resync))
 532                 do_balance = 0;
 533
 534         for (slot = 0; slot < conf->copies ; slot++) {
 535                 if (r10_bio->devs[slot].bio == IO_BLOCKED)
 536                         continue;
 537                 disk = r10_bio->devs[slot].devnum;
 538                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 539                 if (rdev == NULL)
 540                         continue;
 541                 if (!test_bit(In_sync, &rdev->flags))
 542                         continue;
 543
 544                 if (!do_balance)
 545                         break;
 546
 547                 /* This optimisation is debatable, and completely destroys
 548                  * sequential read speed for 'far copies' arrays.  So only
 549                  * keep it for 'near' arrays, and review those later.
 550                  */
 551                 if (conf->near_copies > 1 && !atomic_read(&rdev->nr_pending))
 552                         break;
 553
 554                 /* for far > 1 always use the lowest address */
 555                 if (conf->far_copies > 1)
 556                         new_distance = r10_bio->devs[slot].addr;
 557                 else
 558                         new_distance = abs(r10_bio->devs[slot].addr -
 559                                            conf->mirrors[disk].head_position);
 560                 if (new_distance < best_dist) {
 561                         best_dist = new_distance;
 562                         best_slot = slot;
 563                 }
 564         }
 565         if (slot == conf->copies)
 566                 slot = best_slot;
 567
 568         if (slot >= 0) {
 569                 disk = r10_bio->devs[slot].devnum;
 570                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 571                 if (!rdev)
 572                         goto retry;
 573                 atomic_inc(&rdev->nr_pending);
 574                 if (test_bit(Faulty, &rdev->flags)) {
 575                         /* Cannot risk returning a device that failed
 576                          * before we inc'ed nr_pending
 577                          */
 578                         rdev_dec_pending(rdev, conf->mddev);
 579                         goto retry;
 580                 }
 581                 r10_bio->read_slot = slot;
 582         } else
 583                 disk = -1;
 584         rcu_read_unlock();
 585
 586         return disk;
 587 }
 588
 589 static int raid10_congested(void *data, int bits)
 590 {
 591         mddev_t *mddev = data;
 592         conf_t *conf = mddev->private;
 593         int i, ret = 0;
 594
 595         if (mddev_congested(mddev, bits))
 596                 return 1;
 597         rcu_read_lock();
 598         for (i = 0; i < conf->raid_disks && ret == 0; i++) {
 599                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 600                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 601                         struct request_queue *q = bdev_get_queue(rdev->bdev);
 602
 603                         ret |= bdi_congested(&q->backing_dev_info, bits);
 604                 }
 605         }
 606         rcu_read_unlock();
 607         return ret;
 608 }
 609
 610 static void flush_pending_writes(conf_t *conf)
 611 {
 612         /* Any writes that have been queued but are awaiting
 613          * bitmap updates get flushed here.
 614          */
 615         spin_lock_irq(&conf->device_lock);
 616
 617         if (conf->pending_bio_list.head) {
 618                 struct bio *bio;
 619                 bio = bio_list_get(&conf->pending_bio_list);
 620                 spin_unlock_irq(&conf->device_lock);
 621                 /* flush any pending bitmap writes to disk
 622                  * before proceeding w/ I/O */
 623                 bitmap_unplug(conf->mddev->bitmap);
 624
 625                 while (bio) { /* submit pending writes */
 626                         struct bio *next = bio->bi_next;
 627                         bio->bi_next = NULL;
 628                         generic_make_request(bio);
 629                         bio = next;
 630                 }
 631         } else
 632                 spin_unlock_irq(&conf->device_lock);
 633 }
 634
 635 /* Barriers....
 636  * Sometimes we need to suspend IO while we do something else,
 637  * either some resync/recovery, or reconfigure the array.
 638  * To do this we raise a 'barrier'.
 639  * The 'barrier' is a counter that can be raised multiple times
 640  * to count how many activities are happening which preclude
 641  * normal IO.
 642  * We can only raise the barrier if there is no pending IO.
 643  * i.e. if nr_pending == 0.
 644  * We choose only to raise the barrier if no-one is waiting for the
 645  * barrier to go down.  This means that as soon as an IO request
 646  * is ready, no other operations which require a barrier will start
 647  * until the IO request has had a chance.
 648  *
 649  * So: regular IO calls 'wait_barrier'.  When that returns there
 650  *    is no backgroup IO happening,  It must arrange to call
 651  *    allow_barrier when it has finished its IO.
 652  * backgroup IO calls must call raise_barrier.  Once that returns
 653  *    there is no normal IO happeing.  It must arrange to call
 654  *    lower_barrier when the particular background IO completes.
 655  */
 656
 657 static void raise_barrier(conf_t *conf, int force)
 658 {
 659         BUG_ON(force && !conf->barrier);
 660         spin_lock_irq(&conf->resync_lock);
 661
 662         /* Wait until no block IO is waiting (unless 'force') */
 663         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
 664                             conf->resync_lock, );
 665
 666         /* block any new IO from starting */
 667         conf->barrier++;
 668
 669         /* Now wait for all pending IO to complete */
 670         wait_event_lock_irq(conf->wait_barrier,
 671                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 672                             conf->resync_lock, );
 673
 674         spin_unlock_irq(&conf->resync_lock);
 675 }
 676
 677 static void lower_barrier(conf_t *conf)
 678 {
 679         unsigned long flags;
 680         spin_lock_irqsave(&conf->resync_lock, flags);
 681         conf->barrier--;
 682         spin_unlock_irqrestore(&conf->resync_lock, flags);
 683         wake_up(&conf->wait_barrier);
 684 }
 685
 686 static void wait_barrier(conf_t *conf)
 687 {
 688         spin_lock_irq(&conf->resync_lock);
 689         if (conf->barrier) {
 690                 conf->nr_waiting++;
 691                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 692                                     conf->resync_lock,
 693                                     );
 694                 conf->nr_waiting--;
 695         }
 696         conf->nr_pending++;
 697         spin_unlock_irq(&conf->resync_lock);
 698 }
 699
 700 static void allow_barrier(conf_t *conf)
 701 {
 702         unsigned long flags;
 703         spin_lock_irqsave(&conf->resync_lock, flags);
 704         conf->nr_pending--;
 705         spin_unlock_irqrestore(&conf->resync_lock, flags);
 706         wake_up(&conf->wait_barrier);
 707 }
 708
 709 static void freeze_array(conf_t *conf)
 710 {
 711         /* stop syncio and normal IO and wait for everything to
 712          * go quiet.
 713          * We increment barrier and nr_waiting, and then
 714          * wait until nr_pending match nr_queued+1
 715          * This is called in the context of one normal IO request
 716          * that has failed. Thus any sync request that might be pending
 717          * will be blocked by nr_pending, and we need to wait for
 718          * pending IO requests to complete or be queued for re-try.
 719          * Thus the number queued (nr_queued) plus this request (1)
 720          * must match the number of pending IOs (nr_pending) before
 721          * we continue.
 722          */
 723         spin_lock_irq(&conf->resync_lock);
 724         conf->barrier++;
 725         conf->nr_waiting++;
 726         wait_event_lock_irq(conf->wait_barrier,
 727                             conf->nr_pending == conf->nr_queued+1,
 728                             conf->resync_lock,
 729                             flush_pending_writes(conf));
 730
 731         spin_unlock_irq(&conf->resync_lock);
 732 }
 733
 734 static void unfreeze_array(conf_t *conf)
 735 {
 736         /* reverse the effect of the freeze */
 737         spin_lock_irq(&conf->resync_lock);
 738         conf->barrier--;
 739         conf->nr_waiting--;
 740         wake_up(&conf->wait_barrier);
 741         spin_unlock_irq(&conf->resync_lock);
 742 }
 743
 744 static int make_request(mddev_t *mddev, struct bio * bio)
 745 {
 746         conf_t *conf = mddev->private;
 747         mirror_info_t *mirror;
 748         r10bio_t *r10_bio;
 749         struct bio *read_bio;
 750         int i;
 751         int chunk_sects = conf->chunk_mask + 1;
 752         const int rw = bio_data_dir(bio);
 753         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
 754         const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
 755         unsigned long flags;
 756         mdk_rdev_t *blocked_rdev;
 757         int plugged;
 758
 759         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 760                 md_flush_request(mddev, bio);
 761                 return 0;
 762         }
 763
 764         /* If this request crosses a chunk boundary, we need to
 765          * split it.  This will only happen for 1 PAGE (or less) requests.
 766          */
 767         if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
 768                       > chunk_sects &&
 769                     conf->near_copies < conf->raid_disks)) {
 770                 struct bio_pair *bp;
 771                 /* Sanity check -- queue functions should prevent this happening */
 772                 if (bio->bi_vcnt != 1 ||
 773                     bio->bi_idx != 0)
 774                         goto bad_map;
 775                 /* This is a one page bio that upper layers
 776                  * refuse to split for us, so we need to split it.
 777                  */
 778                 bp = bio_split(bio,
 779                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
 780
 781                 /* Each of these 'make_request' calls will call 'wait_barrier'.
 782                  * If the first succeeds but the second blocks due to the resync
 783                  * thread raising the barrier, we will deadlock because the
 784                  * IO to the underlying device will be queued in generic_make_request
 785                  * and will never complete, so will never reduce nr_pending.
 786                  * So increment nr_waiting here so no new raise_barriers will
 787                  * succeed, and so the second wait_barrier cannot block.
 788                  */
 789                 spin_lock_irq(&conf->resync_lock);
 790                 conf->nr_waiting++;
 791                 spin_unlock_irq(&conf->resync_lock);
 792
 793                 if (make_request(mddev, &bp->bio1))
 794                         generic_make_request(&bp->bio1);
 795                 if (make_request(mddev, &bp->bio2))
 796                         generic_make_request(&bp->bio2);
 797
 798                 spin_lock_irq(&conf->resync_lock);
 799                 conf->nr_waiting--;
 800                 wake_up(&conf->wait_barrier);
 801                 spin_unlock_irq(&conf->resync_lock);
 802
 803                 bio_pair_release(bp);
 804                 return 0;
 805         bad_map:
 806                 printk("md/raid10:%s: make_request bug: can't convert block across chunks"
 807                        " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
 808                        (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 809
 810                 bio_io_error(bio);
 811                 return 0;
 812         }
 813
 814         md_write_start(mddev, bio);
 815
 816         /*
 817          * Register the new request and wait if the reconstruction
 818          * thread has put up a bar for new requests.
 819          * Continue immediately if no resync is active currently.
 820          */
 821         wait_barrier(conf);
 822
 823         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
 824
 825         r10_bio->master_bio = bio;
 826         r10_bio->sectors = bio->bi_size >> 9;
 827
 828         r10_bio->mddev = mddev;
 829         r10_bio->sector = bio->bi_sector;
 830         r10_bio->state = 0;
 831
 832         if (rw == READ) {
 833                 /*
 834                  * read balancing logic:
 835                  */
 836                 int disk = read_balance(conf, r10_bio);
 837                 int slot = r10_bio->read_slot;
 838                 if (disk < 0) {
 839                         raid_end_bio_io(r10_bio);
 840                         return 0;
 841                 }
 842                 mirror = conf->mirrors + disk;
 843
 844                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
 845
 846                 r10_bio->devs[slot].bio = read_bio;
 847
 848                 read_bio->bi_sector = r10_bio->devs[slot].addr +
 849                         mirror->rdev->data_offset;
 850                 read_bio->bi_bdev = mirror->rdev->bdev;
 851                 read_bio->bi_end_io = raid10_end_read_request;
 852                 read_bio->bi_rw = READ | do_sync;
 853                 read_bio->bi_private = r10_bio;
 854
 855                 generic_make_request(read_bio);
 856                 return 0;
 857         }
 858
 859         /*
 860          * WRITE:
 861          */
 862         /* first select target devices under rcu_lock and
 863          * inc refcount on their rdev.  Record them by setting
 864          * bios[x] to bio
 865          */
 866         plugged = mddev_check_plugged(mddev);
 867
 868         raid10_find_phys(conf, r10_bio);
 869  retry_write:
 870         blocked_rdev = NULL;
 871         rcu_read_lock();
 872         for (i = 0;  i < conf->copies; i++) {
 873                 int d = r10_bio->devs[i].devnum;
 874                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
 875                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 876                         atomic_inc(&rdev->nr_pending);
 877                         blocked_rdev = rdev;
 878                         break;
 879                 }
 880                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 881                         atomic_inc(&rdev->nr_pending);
 882                         r10_bio->devs[i].bio = bio;
 883                 } else {
 884                         r10_bio->devs[i].bio = NULL;
 885                         set_bit(R10BIO_Degraded, &r10_bio->state);
 886                 }
 887         }
 888         rcu_read_unlock();
 889
 890         if (unlikely(blocked_rdev)) {
 891                 /* Have to wait for this device to get unblocked, then retry */
 892                 int j;
 893                 int d;
 894
 895                 for (j = 0; j < i; j++)
 896                         if (r10_bio->devs[j].bio) {
 897                                 d = r10_bio->devs[j].devnum;
 898                                 rdev_dec_pending(conf->mirrors[d].rdev, mddev);
 899                         }
 900                 allow_barrier(conf);
 901                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
 902                 wait_barrier(conf);
 903                 goto retry_write;
 904         }
 905
 906         atomic_set(&r10_bio->remaining, 1);
 907         bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
 908
 909         for (i = 0; i < conf->copies; i++) {
 910                 struct bio *mbio;
 911                 int d = r10_bio->devs[i].devnum;
 912                 if (!r10_bio->devs[i].bio)
 913                         continue;
 914
 915                 mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
 916                 r10_bio->devs[i].bio = mbio;
 917
 918                 mbio->bi_sector = r10_bio->devs[i].addr+
 919                         conf->mirrors[d].rdev->data_offset;
 920                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
 921                 mbio->bi_end_io = raid10_end_write_request;
 922                 mbio->bi_rw = WRITE | do_sync | do_fua;
 923                 mbio->bi_private = r10_bio;
 924
 925                 atomic_inc(&r10_bio->remaining);
 926                 spin_lock_irqsave(&conf->device_lock, flags);
 927                 bio_list_add(&conf->pending_bio_list, mbio);
 928                 spin_unlock_irqrestore(&conf->device_lock, flags);
 929         }
 930
 931         if (atomic_dec_and_test(&r10_bio->remaining)) {
 932                 /* This matches the end of raid10_end_write_request() */
 933                 bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 934                                 r10_bio->sectors,
 935                                 !test_bit(R10BIO_Degraded, &r10_bio->state),
 936                                 0);
 937                 md_write_end(mddev);
 938                 raid_end_bio_io(r10_bio);
 939         }
 940
 941         /* In case raid10d snuck in to freeze_array */
 942         wake_up(&conf->wait_barrier);
 943
 944         if (do_sync || !mddev->bitmap || !plugged)
 945                 md_wakeup_thread(mddev->thread);
 946         return 0;
 947 }
 948
 949 static void status(struct seq_file *seq, mddev_t *mddev)
 950 {
 951         conf_t *conf = mddev->private;
 952         int i;
 953
 954         if (conf->near_copies < conf->raid_disks)
 955                 seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
 956         if (conf->near_copies > 1)
 957                 seq_printf(seq, " %d near-copies", conf->near_copies);
 958         if (conf->far_copies > 1) {
 959                 if (conf->far_offset)
 960                         seq_printf(seq, " %d offset-copies", conf->far_copies);
 961                 else
 962                         seq_printf(seq, " %d far-copies", conf->far_copies);
 963         }
 964         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 965                                         conf->raid_disks - mddev->degraded);
 966         for (i = 0; i < conf->raid_disks; i++)
 967                 seq_printf(seq, "%s",
 968                               conf->mirrors[i].rdev &&
 969                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
 970         seq_printf(seq, "]");
 971 }
 972
 973 /* check if there are enough drives for
 974  * every block to appear on atleast one.
 975  * Don't consider the device numbered 'ignore'
 976  * as we might be about to remove it.
 977  */
 978 static int enough(conf_t *conf, int ignore)
 979 {
 980         int first = 0;
 981
 982         do {
 983                 int n = conf->copies;
 984                 int cnt = 0;
 985                 while (n--) {
 986                         if (conf->mirrors[first].rdev &&
 987                             first != ignore)
 988                                 cnt++;
 989                         first = (first+1) % conf->raid_disks;
 990                 }
 991                 if (cnt == 0)
 992                         return 0;
 993         } while (first != 0);
 994         return 1;
 995 }
 996
 997 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 998 {
 999         char b[BDEVNAME_SIZE];
1000         conf_t *conf = mddev->private;
1001
1002         /*
1003          * If it is not operational, then we have already marked it as dead
1004          * else if it is the last working disks, ignore the error, let the
1005          * next level up know.
1006          * else mark the drive as failed
1007          */
1008         if (test_bit(In_sync, &rdev->flags)
1009             && !enough(conf, rdev->raid_disk))
1010                 /*
1011                  * Don't fail the drive, just return an IO error.
1012                  */
1013                 return;
1014         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1015                 unsigned long flags;
1016                 spin_lock_irqsave(&conf->device_lock, flags);
1017                 mddev->degraded++;
1018                 spin_unlock_irqrestore(&conf->device_lock, flags);
1019                 /*
1020                  * if recovery is running, make sure it aborts.
1021                  */
1022                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1023         }
1024         set_bit(Faulty, &rdev->flags);
1025         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1026         printk(KERN_ALERT
1027                "md/raid10:%s: Disk failure on %s, disabling device.\n"
1028                "md/raid10:%s: Operation continuing on %d devices.\n",
1029                mdname(mddev), bdevname(rdev->bdev, b),
1030                mdname(mddev), conf->raid_disks - mddev->degraded);
1031 }
1032
1033 static void print_conf(conf_t *conf)
1034 {
1035         int i;
1036         mirror_info_t *tmp;
1037
1038         printk(KERN_DEBUG "RAID10 conf printout:\n");
1039         if (!conf) {
1040                 printk(KERN_DEBUG "(!conf)\n");
1041                 return;
1042         }
1043         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1044                 conf->raid_disks);
1045
1046         for (i = 0; i < conf->raid_disks; i++) {
1047                 char b[BDEVNAME_SIZE];
1048                 tmp = conf->mirrors + i;
1049                 if (tmp->rdev)
1050                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1051                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1052                                 !test_bit(Faulty, &tmp->rdev->flags),
1053                                 bdevname(tmp->rdev->bdev,b));
1054         }
1055 }
1056
1057 static void close_sync(conf_t *conf)
1058 {
1059         wait_barrier(conf);
1060         allow_barrier(conf);
1061
1062         mempool_destroy(conf->r10buf_pool);
1063         conf->r10buf_pool = NULL;
1064 }
1065
1066 static int raid10_spare_active(mddev_t *mddev)
1067 {
1068         int i;
1069         conf_t *conf = mddev->private;
1070         mirror_info_t *tmp;
1071         int count = 0;
1072         unsigned long flags;
1073
1074         /*
1075          * Find all non-in_sync disks within the RAID10 configuration
1076          * and mark them in_sync
1077          */
1078         for (i = 0; i < conf->raid_disks; i++) {
1079                 tmp = conf->mirrors + i;
1080                 if (tmp->rdev
1081                     && !test_bit(Faulty, &tmp->rdev->flags)
1082                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1083                         count++;
1084                         sysfs_notify_dirent(tmp->rdev->sysfs_state);
1085                 }
1086         }
1087         spin_lock_irqsave(&conf->device_lock, flags);
1088         mddev->degraded -= count;
1089         spin_unlock_irqrestore(&conf->device_lock, flags);
1090
1091         print_conf(conf);
1092         return count;
1093 }
1094
1095
1096 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1097 {
1098         conf_t *conf = mddev->private;
1099         int err = -EEXIST;
1100         int mirror;
1101         int first = 0;
1102         int last = conf->raid_disks - 1;
1103
1104         if (rdev->badblocks.count)
1105                 return -EINVAL;
1106
1107         if (mddev->recovery_cp < MaxSector)
1108                 /* only hot-add to in-sync arrays, as recovery is
1109                  * very different from resync
1110                  */
1111                 return -EBUSY;
1112         if (!enough(conf, -1))
1113                 return -EINVAL;
1114
1115         if (rdev->raid_disk >= 0)
1116                 first = last = rdev->raid_disk;
1117
1118         if (rdev->saved_raid_disk >= first &&
1119             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1120                 mirror = rdev->saved_raid_disk;
1121         else
1122                 mirror = first;
1123         for ( ; mirror <= last ; mirror++) {
1124                 mirror_info_t *p = &conf->mirrors[mirror];
1125                 if (p->recovery_disabled == mddev->recovery_disabled)
1126                         continue;
1127                 if (!p->rdev)
1128                         continue;
1129
1130                 disk_stack_limits(mddev->gendisk, rdev->bdev,
1131                                   rdev->data_offset << 9);
1132                 /* as we don't honour merge_bvec_fn, we must
1133                  * never risk violating it, so limit
1134                  * ->max_segments to one lying with a single
1135                  * page, as a one page request is never in
1136                  * violation.
1137                  */
1138                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
1139                         blk_queue_max_segments(mddev->queue, 1);
1140                         blk_queue_segment_boundary(mddev->queue,
1141                                                    PAGE_CACHE_SIZE - 1);
1142                 }
1143
1144                 p->head_position = 0;
1145                 rdev->raid_disk = mirror;
1146                 err = 0;
1147                 if (rdev->saved_raid_disk != mirror)
1148                         conf->fullsync = 1;
1149                 rcu_assign_pointer(p->rdev, rdev);
1150                 break;
1151         }
1152
1153         md_integrity_add_rdev(rdev, mddev);
1154         print_conf(conf);
1155         return err;
1156 }
1157
1158 static int raid10_remove_disk(mddev_t *mddev, int number)
1159 {
1160         conf_t *conf = mddev->private;
1161         int err = 0;
1162         mdk_rdev_t *rdev;
1163         mirror_info_t *p = conf->mirrors+ number;
1164
1165         print_conf(conf);
1166         rdev = p->rdev;
1167         if (rdev) {
1168                 if (test_bit(In_sync, &rdev->flags) ||
1169                     atomic_read(&rdev->nr_pending)) {
1170                         err = -EBUSY;
1171                         goto abort;
1172                 }
1173                 /* Only remove faulty devices in recovery
1174                  * is not possible.
1175                  */
1176                 if (!test_bit(Faulty, &rdev->flags) &&
1177                     mddev->recovery_disabled != p->recovery_disabled &&
1178                     enough(conf, -1)) {
1179                         err = -EBUSY;
1180                         goto abort;
1181                 }
1182                 p->rdev = NULL;
1183                 synchronize_rcu();
1184                 if (atomic_read(&rdev->nr_pending)) {
1185                         /* lost the race, try later */
1186                         err = -EBUSY;
1187                         p->rdev = rdev;
1188                         goto abort;
1189                 }
1190                 err = md_integrity_register(mddev);
1191         }
1192 abort:
1193
1194         print_conf(conf);
1195         return err;
1196 }
1197
1198
1199 static void end_sync_read(struct bio *bio, int error)
1200 {
1201         r10bio_t *r10_bio = bio->bi_private;
1202         conf_t *conf = r10_bio->mddev->private;
1203         int d;
1204
1205         d = find_bio_disk(conf, r10_bio, bio);
1206
1207         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1208                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1209         else {
1210                 atomic_add(r10_bio->sectors,
1211                            &conf->mirrors[d].rdev->corrected_errors);
1212                 if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
1213                         md_error(r10_bio->mddev,
1214                                  conf->mirrors[d].rdev);
1215         }
1216
1217         /* for reconstruct, we always reschedule after a read.
1218          * for resync, only after all reads
1219          */
1220         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1221         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1222             atomic_dec_and_test(&r10_bio->remaining)) {
1223                 /* we have read all the blocks,
1224                  * do the comparison in process context in raid10d
1225                  */
1226                 reschedule_retry(r10_bio);
1227         }
1228 }
1229
1230 static void end_sync_write(struct bio *bio, int error)
1231 {
1232         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1233         r10bio_t *r10_bio = bio->bi_private;
1234         mddev_t *mddev = r10_bio->mddev;
1235         conf_t *conf = mddev->private;
1236         int d;
1237
1238         d = find_bio_disk(conf, r10_bio, bio);
1239
1240         if (!uptodate)
1241                 md_error(mddev, conf->mirrors[d].rdev);
1242
1243         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1244         while (atomic_dec_and_test(&r10_bio->remaining)) {
1245                 if (r10_bio->master_bio == NULL) {
1246                         /* the primary of several recovery bios */
1247                         sector_t s = r10_bio->sectors;
1248                         put_buf(r10_bio);
1249                         md_done_sync(mddev, s, 1);
1250                         break;
1251                 } else {
1252                         r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
1253                         put_buf(r10_bio);
1254                         r10_bio = r10_bio2;
1255                 }
1256         }
1257 }
1258
1259 /*
1260  * Note: sync and recover and handled very differently for raid10
1261  * This code is for resync.
1262  * For resync, we read through virtual addresses and read all blocks.
1263  * If there is any error, we schedule a write.  The lowest numbered
1264  * drive is authoritative.
1265  * However requests come for physical address, so we need to map.
1266  * For every physical address there are raid_disks/copies virtual addresses,
1267  * which is always are least one, but is not necessarly an integer.
1268  * This means that a physical address can span multiple chunks, so we may
1269  * have to submit multiple io requests for a single sync request.
1270  */
1271 /*
1272  * We check if all blocks are in-sync and only write to blocks that
1273  * aren't in sync
1274  */
1275 static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1276 {
1277         conf_t *conf = mddev->private;
1278         int i, first;
1279         struct bio *tbio, *fbio;
1280
1281         atomic_set(&r10_bio->remaining, 1);
1282
1283         /* find the first device with a block */
1284         for (i=0; i<conf->copies; i++)
1285                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1286                         break;
1287
1288         if (i == conf->copies)
1289                 goto done;
1290
1291         first = i;
1292         fbio = r10_bio->devs[i].bio;
1293
1294         /* now find blocks with errors */
1295         for (i=0 ; i < conf->copies ; i++) {
1296                 int  j, d;
1297                 int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
1298
1299                 tbio = r10_bio->devs[i].bio;
1300
1301                 if (tbio->bi_end_io != end_sync_read)
1302                         continue;
1303                 if (i == first)
1304                         continue;
1305                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1306                         /* We know that the bi_io_vec layout is the same for
1307                          * both 'first' and 'i', so we just compare them.
1308                          * All vec entries are PAGE_SIZE;
1309                          */
1310                         for (j = 0; j < vcnt; j++)
1311                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1312                                            page_address(tbio->bi_io_vec[j].bv_page),
1313                                            PAGE_SIZE))
1314                                         break;
1315                         if (j == vcnt)
1316                                 continue;
1317                         mddev->resync_mismatches += r10_bio->sectors;
1318                 }
1319                 if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1320                         /* Don't fix anything. */
1321                         continue;
1322                 /* Ok, we need to write this bio
1323                  * First we need to fixup bv_offset, bv_len and
1324                  * bi_vecs, as the read request might have corrupted these
1325                  */
1326                 tbio->bi_vcnt = vcnt;
1327                 tbio->bi_size = r10_bio->sectors << 9;
1328                 tbio->bi_idx = 0;
1329                 tbio->bi_phys_segments = 0;
1330                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1331                 tbio->bi_flags |= 1 << BIO_UPTODATE;
1332                 tbio->bi_next = NULL;
1333                 tbio->bi_rw = WRITE;
1334                 tbio->bi_private = r10_bio;
1335                 tbio->bi_sector = r10_bio->devs[i].addr;
1336
1337                 for (j=0; j < vcnt ; j++) {
1338                         tbio->bi_io_vec[j].bv_offset = 0;
1339                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1340
1341                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1342                                page_address(fbio->bi_io_vec[j].bv_page),
1343                                PAGE_SIZE);
1344                 }
1345                 tbio->bi_end_io = end_sync_write;
1346
1347                 d = r10_bio->devs[i].devnum;
1348                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1349                 atomic_inc(&r10_bio->remaining);
1350                 md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1351
1352                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1353                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1354                 generic_make_request(tbio);
1355         }
1356
1357 done:
1358         if (atomic_dec_and_test(&r10_bio->remaining)) {
1359                 md_done_sync(mddev, r10_bio->sectors, 1);
1360                 put_buf(r10_bio);
1361         }
1362 }
1363
1364 /*
1365  * Now for the recovery code.
1366  * Recovery happens across physical sectors.
1367  * We recover all non-is_sync drives by finding the virtual address of
1368  * each, and then choose a working drive that also has that virt address.
1369  * There is a separate r10_bio for each non-in_sync drive.
1370  * Only the first two slots are in use. The first for reading,
1371  * The second for writing.
1372  *
1373  */
1374
1375 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1376 {
1377         conf_t *conf = mddev->private;
1378         int d;
1379         struct bio *wbio;
1380
1381         /*
1382          * share the pages with the first bio
1383          * and submit the write request
1384          */
1385         wbio = r10_bio->devs[1].bio;
1386         d = r10_bio->devs[1].devnum;
1387
1388         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1389         md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
1390         if (test_bit(R10BIO_Uptodate, &r10_bio->state))
1391                 generic_make_request(wbio);
1392         else {
1393                 printk(KERN_NOTICE
1394                        "md/raid10:%s: recovery aborted due to read error\n",
1395                        mdname(mddev));
1396                 conf->mirrors[d].recovery_disabled = mddev->recovery_disabled;
1397                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1398                 bio_endio(wbio, 0);
1399         }
1400 }
1401
1402
1403 /*
1404  * Used by fix_read_error() to decay the per rdev read_errors.
1405  * We halve the read error count for every hour that has elapsed
1406  * since the last recorded read error.
1407  *
1408  */
1409 static void check_decay_read_errors(mddev_t *mddev, mdk_rdev_t *rdev)
1410 {
1411         struct timespec cur_time_mon;
1412         unsigned long hours_since_last;
1413         unsigned int read_errors = atomic_read(&rdev->read_errors);
1414
1415         ktime_get_ts(&cur_time_mon);
1416
1417         if (rdev->last_read_error.tv_sec == 0 &&
1418             rdev->last_read_error.tv_nsec == 0) {
1419                 /* first time we've seen a read error */
1420                 rdev->last_read_error = cur_time_mon;
1421                 return;
1422         }
1423
1424         hours_since_last = (cur_time_mon.tv_sec -
1425                             rdev->last_read_error.tv_sec) / 3600;
1426
1427         rdev->last_read_error = cur_time_mon;
1428
1429         /*
1430          * if hours_since_last is > the number of bits in read_errors
1431          * just set read errors to 0. We do this to avoid
1432          * overflowing the shift of read_errors by hours_since_last.
1433          */
1434         if (hours_since_last >= 8 * sizeof(read_errors))
1435                 atomic_set(&rdev->read_errors, 0);
1436         else
1437                 atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
1438 }
1439
1440 /*
1441  * This is a kernel thread which:
1442  *
1443  *      1.      Retries failed read operations on working mirrors.
1444  *      2.      Updates the raid superblock when problems encounter.
1445  *      3.      Performs writes following reads for array synchronising.
1446  */
1447
1448 static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
1449 {
1450         int sect = 0; /* Offset from r10_bio->sector */
1451         int sectors = r10_bio->sectors;
1452         mdk_rdev_t*rdev;
1453         int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
1454         int d = r10_bio->devs[r10_bio->read_slot].devnum;
1455
1456         /* still own a reference to this rdev, so it cannot
1457          * have been cleared recently.
1458          */
1459         rdev = conf->mirrors[d].rdev;
1460
1461         if (test_bit(Faulty, &rdev->flags))
1462                 /* drive has already been failed, just ignore any
1463                    more fix_read_error() attempts */
1464                 return;
1465
1466         check_decay_read_errors(mddev, rdev);
1467         atomic_inc(&rdev->read_errors);
1468         if (atomic_read(&rdev->read_errors) > max_read_errors) {
1469                 char b[BDEVNAME_SIZE];
1470                 bdevname(rdev->bdev, b);
1471
1472                 printk(KERN_NOTICE
1473                        "md/raid10:%s: %s: Raid device exceeded "
1474                        "read_error threshold [cur %d:max %d]\n",
1475                        mdname(mddev), b,
1476                        atomic_read(&rdev->read_errors), max_read_errors);
1477                 printk(KERN_NOTICE
1478                        "md/raid10:%s: %s: Failing raid device\n",
1479                        mdname(mddev), b);
1480                 md_error(mddev, conf->mirrors[d].rdev);
1481                 return;
1482         }
1483
1484         while(sectors) {
1485                 int s = sectors;
1486                 int sl = r10_bio->read_slot;
1487                 int success = 0;
1488                 int start;
1489
1490                 if (s > (PAGE_SIZE>>9))
1491                         s = PAGE_SIZE >> 9;
1492
1493                 rcu_read_lock();
1494                 do {
1495                         d = r10_bio->devs[sl].devnum;
1496                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1497                         if (rdev &&
1498                             test_bit(In_sync, &rdev->flags)) {
1499                                 atomic_inc(&rdev->nr_pending);
1500                                 rcu_read_unlock();
1501                                 success = sync_page_io(rdev,
1502                                                        r10_bio->devs[sl].addr +
1503                                                        sect,
1504                                                        s<<9,
1505                                                        conf->tmppage, READ, false);
1506                                 rdev_dec_pending(rdev, mddev);
1507                                 rcu_read_lock();
1508                                 if (success)
1509                                         break;
1510                         }
1511                         sl++;
1512                         if (sl == conf->copies)
1513                                 sl = 0;
1514                 } while (!success && sl != r10_bio->read_slot);
1515                 rcu_read_unlock();
1516
1517                 if (!success) {
1518                         /* Cannot read from anywhere -- bye bye array */
1519                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
1520                         md_error(mddev, conf->mirrors[dn].rdev);
1521                         break;
1522                 }
1523
1524                 start = sl;
1525                 /* write it back and re-read */
1526                 rcu_read_lock();
1527                 while (sl != r10_bio->read_slot) {
1528                         char b[BDEVNAME_SIZE];
1529
1530                         if (sl==0)
1531                                 sl = conf->copies;
1532                         sl--;
1533                         d = r10_bio->devs[sl].devnum;
1534                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1535                         if (rdev &&
1536                             test_bit(In_sync, &rdev->flags)) {
1537                                 atomic_inc(&rdev->nr_pending);
1538                                 rcu_read_unlock();
1539                                 if (sync_page_io(rdev,
1540                                                  r10_bio->devs[sl].addr +
1541                                                  sect,
1542                                                  s<<9, conf->tmppage, WRITE, false)
1543                                     == 0) {
1544                                         /* Well, this device is dead */
1545                                         printk(KERN_NOTICE
1546                                                "md/raid10:%s: read correction "
1547                                                "write failed"
1548                                                " (%d sectors at %llu on %s)\n",
1549                                                mdname(mddev), s,
1550                                                (unsigned long long)(
1551                                                        sect + rdev->data_offset),
1552                                                bdevname(rdev->bdev, b));
1553                                         printk(KERN_NOTICE "md/raid10:%s: %s: failing "
1554                                                "drive\n",
1555                                                mdname(mddev),
1556                                                bdevname(rdev->bdev, b));
1557                                         md_error(mddev, rdev);
1558                                 }
1559                                 rdev_dec_pending(rdev, mddev);
1560                                 rcu_read_lock();
1561                         }
1562                 }
1563                 sl = start;
1564                 while (sl != r10_bio->read_slot) {
1565
1566                         if (sl==0)
1567                                 sl = conf->copies;
1568                         sl--;
1569                         d = r10_bio->devs[sl].devnum;
1570                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1571                         if (rdev &&
1572                             test_bit(In_sync, &rdev->flags)) {
1573                                 char b[BDEVNAME_SIZE];
1574                                 atomic_inc(&rdev->nr_pending);
1575                                 rcu_read_unlock();
1576                                 if (sync_page_io(rdev,
1577                                                  r10_bio->devs[sl].addr +
1578                                                  sect,
1579                                                  s<<9, conf->tmppage,
1580                                                  READ, false) == 0) {
1581                                         /* Well, this device is dead */
1582                                         printk(KERN_NOTICE
1583                                                "md/raid10:%s: unable to read back "
1584                                                "corrected sectors"
1585                                                " (%d sectors at %llu on %s)\n",
1586                                                mdname(mddev), s,
1587                                                (unsigned long long)(
1588                                                        sect + rdev->data_offset),
1589                                                bdevname(rdev->bdev, b));
1590                                         printk(KERN_NOTICE "md/raid10:%s: %s: failing drive\n",
1591                                                mdname(mddev),
1592                                                bdevname(rdev->bdev, b));
1593
1594                                         md_error(mddev, rdev);
1595                                 } else {
1596                                         printk(KERN_INFO
1597                                                "md/raid10:%s: read error corrected"
1598                                                " (%d sectors at %llu on %s)\n",
1599                                                mdname(mddev), s,
1600                                                (unsigned long long)(
1601                                                        sect + rdev->data_offset),
1602                                                bdevname(rdev->bdev, b));
1603                                         atomic_add(s, &rdev->corrected_errors);
1604                                 }
1605
1606                                 rdev_dec_pending(rdev, mddev);
1607                                 rcu_read_lock();
1608                         }
1609                 }
1610                 rcu_read_unlock();
1611
1612                 sectors -= s;
1613                 sect += s;
1614         }
1615 }
1616
1617 static void raid10d(mddev_t *mddev)
1618 {
1619         r10bio_t *r10_bio;
1620         struct bio *bio;
1621         unsigned long flags;
1622         conf_t *conf = mddev->private;
1623         struct list_head *head = &conf->retry_list;
1624         mdk_rdev_t *rdev;
1625         struct blk_plug plug;
1626
1627         md_check_recovery(mddev);
1628
1629         blk_start_plug(&plug);
1630         for (;;) {
1631                 char b[BDEVNAME_SIZE];
1632
1633                 flush_pending_writes(conf);
1634
1635                 spin_lock_irqsave(&conf->device_lock, flags);
1636                 if (list_empty(head)) {
1637                         spin_unlock_irqrestore(&conf->device_lock, flags);
1638                         break;
1639                 }
1640                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
1641                 list_del(head->prev);
1642                 conf->nr_queued--;
1643                 spin_unlock_irqrestore(&conf->device_lock, flags);
1644
1645                 mddev = r10_bio->mddev;
1646                 conf = mddev->private;
1647                 if (test_bit(R10BIO_IsSync, &r10_bio->state))
1648                         sync_request_write(mddev, r10_bio);
1649                 else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
1650                         recovery_request_write(mddev, r10_bio);
1651                 else {
1652                         int slot = r10_bio->read_slot;
1653                         int mirror = r10_bio->devs[slot].devnum;
1654                         /* we got a read error. Maybe the drive is bad.  Maybe just
1655                          * the block and we can fix it.
1656                          * We freeze all other IO, and try reading the block from
1657                          * other devices.  When we find one, we re-write
1658                          * and check it that fixes the read error.
1659                          * This is all done synchronously while the array is
1660                          * frozen.
1661                          */
1662                         if (mddev->ro == 0) {
1663                                 freeze_array(conf);
1664                                 fix_read_error(conf, mddev, r10_bio);
1665                                 unfreeze_array(conf);
1666                         }
1667                         rdev_dec_pending(conf->mirrors[mirror].rdev, mddev);
1668
1669                         bio = r10_bio->devs[slot].bio;
1670                         r10_bio->devs[slot].bio =
1671                                 mddev->ro ? IO_BLOCKED : NULL;
1672                         mirror = read_balance(conf, r10_bio);
1673                         if (mirror == -1) {
1674                                 printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
1675                                        " read error for block %llu\n",
1676                                        mdname(mddev),
1677                                        bdevname(bio->bi_bdev,b),
1678                                        (unsigned long long)r10_bio->sector);
1679                                 raid_end_bio_io(r10_bio);
1680                                 bio_put(bio);
1681                         } else {
1682                                 const unsigned long do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
1683                                 bio_put(bio);
1684                                 slot = r10_bio->read_slot;
1685                                 rdev = conf->mirrors[mirror].rdev;
1686                                 printk_ratelimited(
1687                                         KERN_ERR
1688                                         "md/raid10:%s: %s: redirecting"
1689                                         "sector %llu to another mirror\n",
1690                                         mdname(mddev),
1691                                         bdevname(rdev->bdev, b),
1692                                         (unsigned long long)r10_bio->sector);
1693                                 bio = bio_clone_mddev(r10_bio->master_bio,
1694                                                       GFP_NOIO, mddev);
1695                                 r10_bio->devs[slot].bio = bio;
1696                                 bio->bi_sector = r10_bio->devs[slot].addr
1697                                         + rdev->data_offset;
1698                                 bio->bi_bdev = rdev->bdev;
1699                                 bio->bi_rw = READ | do_sync;
1700                                 bio->bi_private = r10_bio;
1701                                 bio->bi_end_io = raid10_end_read_request;
1702                                 generic_make_request(bio);
1703                         }
1704                 }
1705                 cond_resched();
1706         }
1707         blk_finish_plug(&plug);
1708 }
1709
1710
1711 static int init_resync(conf_t *conf)
1712 {
1713         int buffs;
1714
1715         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1716         BUG_ON(conf->r10buf_pool);
1717         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
1718         if (!conf->r10buf_pool)
1719                 return -ENOMEM;
1720         conf->next_resync = 0;
1721         return 0;
1722 }
1723
1724 /*
1725  * perform a "sync" on one "block"
1726  *
1727  * We need to make sure that no normal I/O request - particularly write
1728  * requests - conflict with active sync requests.
1729  *
1730  * This is achieved by tracking pending requests and a 'barrier' concept
1731  * that can be installed to exclude normal IO requests.
1732  *
1733  * Resync and recovery are handled very differently.
1734  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
1735  *
1736  * For resync, we iterate over virtual addresses, read all copies,
1737  * and update if there are differences.  If only one copy is live,
1738  * skip it.
1739  * For recovery, we iterate over physical addresses, read a good
1740  * value for each non-in_sync drive, and over-write.
1741  *
1742  * So, for recovery we may have several outstanding complex requests for a
1743  * given address, one for each out-of-sync device.  We model this by allocating
1744  * a number of r10_bio structures, one for each out-of-sync device.
1745  * As we setup these structures, we collect all bio's together into a list
1746  * which we then process collectively to add pages, and then process again
1747  * to pass to generic_make_request.
1748  *
1749  * The r10_bio structures are linked using a borrowed master_bio pointer.
1750  * This link is counted in ->remaining.  When the r10_bio that points to NULL
1751  * has its remaining count decremented to 0, the whole complex operation
1752  * is complete.
1753  *
1754  */
1755
1756 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
1757                              int *skipped, int go_faster)
1758 {
1759         conf_t *conf = mddev->private;
1760         r10bio_t *r10_bio;
1761         struct bio *biolist = NULL, *bio;
1762         sector_t max_sector, nr_sectors;
1763         int i;
1764         int max_sync;
1765         sector_t sync_blocks;
1766
1767         sector_t sectors_skipped = 0;
1768         int chunks_skipped = 0;
1769
1770         if (!conf->r10buf_pool)
1771                 if (init_resync(conf))
1772                         return 0;
1773
1774  skipped:
1775         max_sector = mddev->dev_sectors;
1776         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1777                 max_sector = mddev->resync_max_sectors;
1778         if (sector_nr >= max_sector) {
1779                 /* If we aborted, we need to abort the
1780                  * sync on the 'current' bitmap chucks (there can
1781                  * be several when recovering multiple devices).
1782                  * as we may have started syncing it but not finished.
1783                  * We can find the current address in
1784                  * mddev->curr_resync, but for recovery,
1785                  * we need to convert that to several
1786                  * virtual addresses.
1787                  */
1788                 if (mddev->curr_resync < max_sector) { /* aborted */
1789                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1790                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1791                                                 &sync_blocks, 1);
1792                         else for (i=0; i<conf->raid_disks; i++) {
1793                                 sector_t sect =
1794                                         raid10_find_virt(conf, mddev->curr_resync, i);
1795                                 bitmap_end_sync(mddev->bitmap, sect,
1796                                                 &sync_blocks, 1);
1797                         }
1798                 } else /* completed sync */
1799                         conf->fullsync = 0;
1800
1801                 bitmap_close_sync(mddev->bitmap);
1802                 close_sync(conf);
1803                 *skipped = 1;
1804                 return sectors_skipped;
1805         }
1806         if (chunks_skipped >= conf->raid_disks) {
1807                 /* if there has been nothing to do on any drive,
1808                  * then there is nothing to do at all..
1809                  */
1810                 *skipped = 1;
1811                 return (max_sector - sector_nr) + sectors_skipped;
1812         }
1813
1814         if (max_sector > mddev->resync_max)
1815                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
1816
1817         /* make sure whole request will fit in a chunk - if chunks
1818          * are meaningful
1819          */
1820         if (conf->near_copies < conf->raid_disks &&
1821             max_sector > (sector_nr | conf->chunk_mask))
1822                 max_sector = (sector_nr | conf->chunk_mask) + 1;
1823         /*
1824          * If there is non-resync activity waiting for us then
1825          * put in a delay to throttle resync.
1826          */
1827         if (!go_faster && conf->nr_waiting)
1828                 msleep_interruptible(1000);
1829
1830         /* Again, very different code for resync and recovery.
1831          * Both must result in an r10bio with a list of bios that
1832          * have bi_end_io, bi_sector, bi_bdev set,
1833          * and bi_private set to the r10bio.
1834          * For recovery, we may actually create several r10bios
1835          * with 2 bios in each, that correspond to the bios in the main one.
1836          * In this case, the subordinate r10bios link back through a
1837          * borrowed master_bio pointer, and the counter in the master
1838          * includes a ref from each subordinate.
1839          */
1840         /* First, we decide what to do and set ->bi_end_io
1841          * To end_sync_read if we want to read, and
1842          * end_sync_write if we will want to write.
1843          */
1844
1845         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
1846         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1847                 /* recovery... the complicated one */
1848                 int j, k;
1849                 r10_bio = NULL;
1850
1851                 for (i=0 ; i<conf->raid_disks; i++) {
1852                         int still_degraded;
1853                         r10bio_t *rb2;
1854                         sector_t sect;
1855                         int must_sync;
1856
1857                         if (conf->mirrors[i].rdev == NULL ||
1858                             test_bit(In_sync, &conf->mirrors[i].rdev->flags))
1859                                 continue;
1860
1861                         still_degraded = 0;
1862                         /* want to reconstruct this device */
1863                         rb2 = r10_bio;
1864                         sect = raid10_find_virt(conf, sector_nr, i);
1865                         /* Unless we are doing a full sync, we only need
1866                          * to recover the block if it is set in the bitmap
1867                          */
1868                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
1869                                                       &sync_blocks, 1);
1870                         if (sync_blocks < max_sync)
1871                                 max_sync = sync_blocks;
1872                         if (!must_sync &&
1873                             !conf->fullsync) {
1874                                 /* yep, skip the sync_blocks here, but don't assume
1875                                  * that there will never be anything to do here
1876                                  */
1877                                 chunks_skipped = -1;
1878                                 continue;
1879                         }
1880
1881                         r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1882                         raise_barrier(conf, rb2 != NULL);
1883                         atomic_set(&r10_bio->remaining, 0);
1884
1885                         r10_bio->master_bio = (struct bio*)rb2;
1886                         if (rb2)
1887                                 atomic_inc(&rb2->remaining);
1888                         r10_bio->mddev = mddev;
1889                         set_bit(R10BIO_IsRecover, &r10_bio->state);
1890                         r10_bio->sector = sect;
1891
1892                         raid10_find_phys(conf, r10_bio);
1893
1894                         /* Need to check if the array will still be
1895                          * degraded
1896                          */
1897                         for (j=0; j<conf->raid_disks; j++)
1898                                 if (conf->mirrors[j].rdev == NULL ||
1899                                     test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
1900                                         still_degraded = 1;
1901                                         break;
1902                                 }
1903
1904                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
1905                                                       &sync_blocks, still_degraded);
1906
1907                         for (j=0; j<conf->copies;j++) {
1908                                 int d = r10_bio->devs[j].devnum;
1909                                 if (!conf->mirrors[d].rdev ||
1910                                     !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
1911                                         continue;
1912                                 /* This is where we read from */
1913                                 bio = r10_bio->devs[0].bio;
1914                                 bio->bi_next = biolist;
1915                                 biolist = bio;
1916                                 bio->bi_private = r10_bio;
1917                                 bio->bi_end_io = end_sync_read;
1918                                 bio->bi_rw = READ;
1919                                 bio->bi_sector = r10_bio->devs[j].addr +
1920                                         conf->mirrors[d].rdev->data_offset;
1921                                 bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1922                                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1923                                 atomic_inc(&r10_bio->remaining);
1924                                 /* and we write to 'i' */
1925
1926                                 for (k=0; k<conf->copies; k++)
1927                                         if (r10_bio->devs[k].devnum == i)
1928                                                 break;
1929                                 BUG_ON(k == conf->copies);
1930                                 bio = r10_bio->devs[1].bio;
1931                                 bio->bi_next = biolist;
1932                                 biolist = bio;
1933                                 bio->bi_private = r10_bio;
1934                                 bio->bi_end_io = end_sync_write;
1935                                 bio->bi_rw = WRITE;
1936                                 bio->bi_sector = r10_bio->devs[k].addr +
1937                                         conf->mirrors[i].rdev->data_offset;
1938                                 bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1939
1940                                 r10_bio->devs[0].devnum = d;
1941                                 r10_bio->devs[1].devnum = i;
1942
1943                                 break;
1944                         }
1945                         if (j == conf->copies) {
1946                                 /* Cannot recover, so abort the recovery */
1947                                 put_buf(r10_bio);
1948                                 if (rb2)
1949                                         atomic_dec(&rb2->remaining);
1950                                 r10_bio = rb2;
1951                                 if (!test_and_set_bit(MD_RECOVERY_INTR,
1952                                                       &mddev->recovery))
1953                                         printk(KERN_INFO "md/raid10:%s: insufficient "
1954                                                "working devices for recovery.\n",
1955                                                mdname(mddev));
1956                                 break;
1957                         }
1958                 }
1959                 if (biolist == NULL) {
1960                         while (r10_bio) {
1961                                 r10bio_t *rb2 = r10_bio;
1962                                 r10_bio = (r10bio_t*) rb2->master_bio;
1963                                 rb2->master_bio = NULL;
1964                                 put_buf(rb2);
1965                         }
1966                         goto giveup;
1967                 }
1968         } else {
1969                 /* resync. Schedule a read for every block at this virt offset */
1970                 int count = 0;
1971
1972                 bitmap_cond_end_sync(mddev->bitmap, sector_nr);
1973
1974                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1975                                        &sync_blocks, mddev->degraded) &&
1976                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
1977                                                  &mddev->recovery)) {
1978                         /* We can skip this block */
1979                         *skipped = 1;
1980                         return sync_blocks + sectors_skipped;
1981                 }
1982                 if (sync_blocks < max_sync)
1983                         max_sync = sync_blocks;
1984                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1985
1986                 r10_bio->mddev = mddev;
1987                 atomic_set(&r10_bio->remaining, 0);
1988                 raise_barrier(conf, 0);
1989                 conf->next_resync = sector_nr;
1990
1991                 r10_bio->master_bio = NULL;
1992                 r10_bio->sector = sector_nr;
1993                 set_bit(R10BIO_IsSync, &r10_bio->state);
1994                 raid10_find_phys(conf, r10_bio);
1995                 r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
1996
1997                 for (i=0; i<conf->copies; i++) {
1998                         int d = r10_bio->devs[i].devnum;
1999                         bio = r10_bio->devs[i].bio;
2000                         bio->bi_end_io = NULL;
2001                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
2002                         if (conf->mirrors[d].rdev == NULL ||
2003                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
2004                                 continue;
2005                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2006                         atomic_inc(&r10_bio->remaining);
2007                         bio->bi_next = biolist;
2008                         biolist = bio;
2009                         bio->bi_private = r10_bio;
2010                         bio->bi_end_io = end_sync_read;
2011                         bio->bi_rw = READ;
2012                         bio->bi_sector = r10_bio->devs[i].addr +
2013                                 conf->mirrors[d].rdev->data_offset;
2014                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
2015                         count++;
2016                 }
2017
2018                 if (count < 2) {
2019                         for (i=0; i<conf->copies; i++) {
2020                                 int d = r10_bio->devs[i].devnum;
2021                                 if (r10_bio->devs[i].bio->bi_end_io)
2022                                         rdev_dec_pending(conf->mirrors[d].rdev,
2023                                                          mddev);
2024                         }
2025                         put_buf(r10_bio);
2026                         biolist = NULL;
2027                         goto giveup;
2028                 }
2029         }
2030
2031         for (bio = biolist; bio ; bio=bio->bi_next) {
2032
2033                 bio->bi_flags &= ~(BIO_POOL_MASK - 1);
2034                 if (bio->bi_end_io)
2035                         bio->bi_flags |= 1 << BIO_UPTODATE;
2036                 bio->bi_vcnt = 0;
2037                 bio->bi_idx = 0;
2038                 bio->bi_phys_segments = 0;
2039                 bio->bi_size = 0;
2040         }
2041
2042         nr_sectors = 0;
2043         if (sector_nr + max_sync < max_sector)
2044                 max_sector = sector_nr + max_sync;
2045         do {
2046                 struct page *page;
2047                 int len = PAGE_SIZE;
2048                 if (sector_nr + (len>>9) > max_sector)
2049                         len = (max_sector - sector_nr) << 9;
2050                 if (len == 0)
2051                         break;
2052                 for (bio= biolist ; bio ; bio=bio->bi_next) {
2053                         struct bio *bio2;
2054                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
2055                         if (bio_add_page(bio, page, len, 0))
2056                                 continue;
2057
2058                         /* stop here */
2059                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
2060                         for (bio2 = biolist;
2061                              bio2 && bio2 != bio;
2062                              bio2 = bio2->bi_next) {
2063                                 /* remove last page from this bio */
2064                                 bio2->bi_vcnt--;
2065                                 bio2->bi_size -= len;
2066                                 bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
2067                         }
2068                         goto bio_full;
2069                 }
2070                 nr_sectors += len>>9;
2071                 sector_nr += len>>9;
2072         } while (biolist->bi_vcnt < RESYNC_PAGES);
2073  bio_full:
2074         r10_bio->sectors = nr_sectors;
2075
2076         while (biolist) {
2077                 bio = biolist;
2078                 biolist = biolist->bi_next;
2079
2080                 bio->bi_next = NULL;
2081                 r10_bio = bio->bi_private;
2082                 r10_bio->sectors = nr_sectors;
2083
2084                 if (bio->bi_end_io == end_sync_read) {
2085                         md_sync_acct(bio->bi_bdev, nr_sectors);
2086                         generic_make_request(bio);
2087                 }
2088         }
2089
2090         if (sectors_skipped)
2091                 /* pretend they weren't skipped, it makes
2092                  * no important difference in this case
2093                  */
2094                 md_done_sync(mddev, sectors_skipped, 1);
2095
2096         return sectors_skipped + nr_sectors;
2097  giveup:
2098         /* There is nowhere to write, so all non-sync
2099          * drives must be failed, so try the next chunk...
2100          */
2101         if (sector_nr + max_sync < max_sector)
2102                 max_sector = sector_nr + max_sync;
2103
2104         sectors_skipped += (max_sector - sector_nr);
2105         chunks_skipped ++;
2106         sector_nr = max_sector;
2107         goto skipped;
2108 }
2109
2110 static sector_t
2111 raid10_size(mddev_t *mddev, sector_t sectors, int raid_disks)
2112 {
2113         sector_t size;
2114         conf_t *conf = mddev->private;
2115
2116         if (!raid_disks)
2117                 raid_disks = conf->raid_disks;
2118         if (!sectors)
2119                 sectors = conf->dev_sectors;
2120
2121         size = sectors >> conf->chunk_shift;
2122         sector_div(size, conf->far_copies);
2123         size = size * raid_disks;
2124         sector_div(size, conf->near_copies);
2125
2126         return size << conf->chunk_shift;
2127 }
2128
2129
2130 static conf_t *setup_conf(mddev_t *mddev)
2131 {
2132         conf_t *conf = NULL;
2133         int nc, fc, fo;
2134         sector_t stride, size;
2135         int err = -EINVAL;
2136
2137         if (mddev->new_chunk_sectors < (PAGE_SIZE >> 9) ||
2138             !is_power_of_2(mddev->new_chunk_sectors)) {
2139                 printk(KERN_ERR "md/raid10:%s: chunk size must be "
2140                        "at least PAGE_SIZE(%ld) and be a power of 2.\n",
2141                        mdname(mddev), PAGE_SIZE);
2142                 goto out;
2143         }
2144
2145         nc = mddev->new_layout & 255;
2146         fc = (mddev->new_layout >> 8) & 255;
2147         fo = mddev->new_layout & (1<<16);
2148
2149         if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
2150             (mddev->new_layout >> 17)) {
2151                 printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
2152                        mdname(mddev), mddev->new_layout);
2153                 goto out;
2154         }
2155
2156         err = -ENOMEM;
2157         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
2158         if (!conf)
2159                 goto out;
2160
2161         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
2162                                 GFP_KERNEL);
2163         if (!conf->mirrors)
2164                 goto out;
2165
2166         conf->tmppage = alloc_page(GFP_KERNEL);
2167         if (!conf->tmppage)
2168                 goto out;
2169
2170
2171         conf->raid_disks = mddev->raid_disks;
2172         conf->near_copies = nc;
2173         conf->far_copies = fc;
2174         conf->copies = nc*fc;
2175         conf->far_offset = fo;
2176         conf->chunk_mask = mddev->new_chunk_sectors - 1;
2177         conf->chunk_shift = ffz(~mddev->new_chunk_sectors);
2178
2179         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
2180                                            r10bio_pool_free, conf);
2181         if (!conf->r10bio_pool)
2182                 goto out;
2183
2184         size = mddev->dev_sectors >> conf->chunk_shift;
2185         sector_div(size, fc);
2186         size = size * conf->raid_disks;
2187         sector_div(size, nc);
2188         /* 'size' is now the number of chunks in the array */
2189         /* calculate "used chunks per device" in 'stride' */
2190         stride = size * conf->copies;
2191
2192         /* We need to round up when dividing by raid_disks to
2193          * get the stride size.
2194          */
2195         stride += conf->raid_disks - 1;
2196         sector_div(stride, conf->raid_disks);
2197
2198         conf->dev_sectors = stride << conf->chunk_shift;
2199
2200         if (fo)
2201                 stride = 1;
2202         else
2203                 sector_div(stride, fc);
2204         conf->stride = stride << conf->chunk_shift;
2205
2206
2207         spin_lock_init(&conf->device_lock);
2208         INIT_LIST_HEAD(&conf->retry_list);
2209
2210         spin_lock_init(&conf->resync_lock);
2211         init_waitqueue_head(&conf->wait_barrier);
2212
2213         conf->thread = md_register_thread(raid10d, mddev, NULL);
2214         if (!conf->thread)
2215                 goto out;
2216
2217         conf->mddev = mddev;
2218         return conf;
2219
2220  out:
2221         printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
2222                mdname(mddev));
2223         if (conf) {
2224                 if (conf->r10bio_pool)
2225                         mempool_destroy(conf->r10bio_pool);
2226                 kfree(conf->mirrors);
2227                 safe_put_page(conf->tmppage);
2228                 kfree(conf);
2229         }
2230         return ERR_PTR(err);
2231 }
2232
2233 static int run(mddev_t *mddev)
2234 {
2235         conf_t *conf;
2236         int i, disk_idx, chunk_size;
2237         mirror_info_t *disk;
2238         mdk_rdev_t *rdev;
2239         sector_t size;
2240
2241         /*
2242          * copy the already verified devices into our private RAID10
2243          * bookkeeping area. [whatever we allocate in run(),
2244          * should be freed in stop()]
2245          */
2246
2247         if (mddev->private == NULL) {
2248                 conf = setup_conf(mddev);
2249                 if (IS_ERR(conf))
2250                         return PTR_ERR(conf);
2251                 mddev->private = conf;
2252         }
2253         conf = mddev->private;
2254         if (!conf)
2255                 goto out;
2256
2257         mddev->thread = conf->thread;
2258         conf->thread = NULL;
2259
2260         chunk_size = mddev->chunk_sectors << 9;
2261         blk_queue_io_min(mddev->queue, chunk_size);
2262         if (conf->raid_disks % conf->near_copies)
2263                 blk_queue_io_opt(mddev->queue, chunk_size * conf->raid_disks);
2264         else
2265                 blk_queue_io_opt(mddev->queue, chunk_size *
2266                                  (conf->raid_disks / conf->near_copies));
2267
2268         list_for_each_entry(rdev, &mddev->disks, same_set) {
2269
2270                 if (rdev->badblocks.count) {
2271                         printk(KERN_ERR "md/raid10: cannot handle bad blocks yet\n");
2272                         goto out_free_conf;
2273                 }
2274                 disk_idx = rdev->raid_disk;
2275                 if (disk_idx >= conf->raid_disks
2276                     || disk_idx < 0)
2277                         continue;
2278                 disk = conf->mirrors + disk_idx;
2279
2280                 disk->rdev = rdev;
2281                 disk_stack_limits(mddev->gendisk, rdev->bdev,
2282                                   rdev->data_offset << 9);
2283                 /* as we don't honour merge_bvec_fn, we must never risk
2284                  * violating it, so limit max_segments to 1 lying
2285                  * within a single page.
2286                  */
2287                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
2288                         blk_queue_max_segments(mddev->queue, 1);
2289                         blk_queue_segment_boundary(mddev->queue,
2290                                                    PAGE_CACHE_SIZE - 1);
2291                 }
2292
2293                 disk->head_position = 0;
2294         }
2295         /* need to check that every block has at least one working mirror */
2296         if (!enough(conf, -1)) {
2297                 printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
2298                        mdname(mddev));
2299                 goto out_free_conf;
2300         }
2301
2302         mddev->degraded = 0;
2303         for (i = 0; i < conf->raid_disks; i++) {
2304
2305                 disk = conf->mirrors + i;
2306
2307                 if (!disk->rdev ||
2308                     !test_bit(In_sync, &disk->rdev->flags)) {
2309                         disk->head_position = 0;
2310                         mddev->degraded++;
2311                         if (disk->rdev)
2312                                 conf->fullsync = 1;
2313                 }
2314         }
2315
2316         if (mddev->recovery_cp != MaxSector)
2317                 printk(KERN_NOTICE "md/raid10:%s: not clean"
2318                        " -- starting background reconstruction\n",
2319                        mdname(mddev));
2320         printk(KERN_INFO
2321                 "md/raid10:%s: active with %d out of %d devices\n",
2322                 mdname(mddev), conf->raid_disks - mddev->degraded,
2323                 conf->raid_disks);
2324         /*
2325          * Ok, everything is just fine now
2326          */
2327         mddev->dev_sectors = conf->dev_sectors;
2328         size = raid10_size(mddev, 0, 0);
2329         md_set_array_sectors(mddev, size);
2330         mddev->resync_max_sectors = size;
2331
2332         mddev->queue->backing_dev_info.congested_fn = raid10_congested;
2333         mddev->queue->backing_dev_info.congested_data = mddev;
2334
2335         /* Calculate max read-ahead size.
2336          * We need to readahead at least twice a whole stripe....
2337          * maybe...
2338          */
2339         {
2340                 int stripe = conf->raid_disks *
2341                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
2342                 stripe /= conf->near_copies;
2343                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
2344                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
2345         }
2346
2347         if (conf->near_copies < conf->raid_disks)
2348                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
2349
2350         if (md_integrity_register(mddev))
2351                 goto out_free_conf;
2352
2353         return 0;
2354
2355 out_free_conf:
2356         md_unregister_thread(mddev->thread);
2357         if (conf->r10bio_pool)
2358                 mempool_destroy(conf->r10bio_pool);
2359         safe_put_page(conf->tmppage);
2360         kfree(conf->mirrors);
2361         kfree(conf);
2362         mddev->private = NULL;
2363 out:
2364         return -EIO;
2365 }
2366
2367 static int stop(mddev_t *mddev)
2368 {
2369         conf_t *conf = mddev->private;
2370
2371         raise_barrier(conf, 0);
2372         lower_barrier(conf);
2373
2374         md_unregister_thread(mddev->thread);
2375         mddev->thread = NULL;
2376         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2377         if (conf->r10bio_pool)
2378                 mempool_destroy(conf->r10bio_pool);
2379         kfree(conf->mirrors);
2380         kfree(conf);
2381         mddev->private = NULL;
2382         return 0;
2383 }
2384
2385 static void raid10_quiesce(mddev_t *mddev, int state)
2386 {
2387         conf_t *conf = mddev->private;
2388
2389         switch(state) {
2390         case 1:
2391                 raise_barrier(conf, 0);
2392                 break;
2393         case 0:
2394                 lower_barrier(conf);
2395                 break;
2396         }
2397 }
2398
2399 static void *raid10_takeover_raid0(mddev_t *mddev)
2400 {
2401         mdk_rdev_t *rdev;
2402         conf_t *conf;
2403
2404         if (mddev->degraded > 0) {
2405                 printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
2406                        mdname(mddev));
2407                 return ERR_PTR(-EINVAL);
2408         }
2409
2410         /* Set new parameters */
2411         mddev->new_level = 10;
2412         /* new layout: far_copies = 1, near_copies = 2 */
2413         mddev->new_layout = (1<<8) + 2;
2414         mddev->new_chunk_sectors = mddev->chunk_sectors;
2415         mddev->delta_disks = mddev->raid_disks;
2416         mddev->raid_disks *= 2;
2417         /* make sure it will be not marked as dirty */
2418         mddev->recovery_cp = MaxSector;
2419
2420         conf = setup_conf(mddev);
2421         if (!IS_ERR(conf)) {
2422                 list_for_each_entry(rdev, &mddev->disks, same_set)
2423                         if (rdev->raid_disk >= 0)
2424                                 rdev->new_raid_disk = rdev->raid_disk * 2;
2425                 conf->barrier = 1;
2426         }
2427
2428         return conf;
2429 }
2430
2431 static void *raid10_takeover(mddev_t *mddev)
2432 {
2433         struct raid0_private_data *raid0_priv;
2434
2435         /* raid10 can take over:
2436          *  raid0 - providing it has only two drives
2437          */
2438         if (mddev->level == 0) {
2439                 /* for raid0 takeover only one zone is supported */
2440                 raid0_priv = mddev->private;
2441                 if (raid0_priv->nr_strip_zones > 1) {
2442                         printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
2443                                " with more than one zone.\n",
2444                                mdname(mddev));
2445                         return ERR_PTR(-EINVAL);
2446                 }
2447                 return raid10_takeover_raid0(mddev);
2448         }
2449         return ERR_PTR(-EINVAL);
2450 }
2451
2452 static struct mdk_personality raid10_personality =
2453 {
2454         .name           = "raid10",
2455         .level          = 10,
2456         .owner          = THIS_MODULE,
2457         .make_request   = make_request,
2458         .run            = run,
2459         .stop           = stop,
2460         .status         = status,
2461         .error_handler  = error,
2462         .hot_add_disk   = raid10_add_disk,
2463         .hot_remove_disk= raid10_remove_disk,
2464         .spare_active   = raid10_spare_active,
2465         .sync_request   = sync_request,
2466         .quiesce        = raid10_quiesce,
2467         .size           = raid10_size,
2468         .takeover       = raid10_takeover,
2469 };
2470
2471 static int __init raid_init(void)
2472 {
2473         return register_md_personality(&raid10_personality);
2474 }
2475
2476 static void raid_exit(void)
2477 {
2478         unregister_md_personality(&raid10_personality);
2479 }
2480
2481 module_init(raid_init);
2482 module_exit(raid_exit);
2483 MODULE_LICENSE("GPL");
2484 MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
2485 MODULE_ALIAS("md-personality-9"); /* RAID10 */
2486 MODULE_ALIAS("md-raid10");
2487 MODULE_ALIAS("md-level-10");