fs/btrfs/scrub.c

   1 /*
   2  * Copyright (C) 2011 STRATO.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/ratelimit.h>
  21 #include "ctree.h"
  22 #include "volumes.h"
  23 #include "disk-io.h"
  24 #include "ordered-data.h"
  25 #include "transaction.h"
  26 #include "backref.h"
  27 #include "extent_io.h"
  28
  29 /*
  30  * This is only the first step towards a full-features scrub. It reads all
  31  * extent and super block and verifies the checksums. In case a bad checksum
  32  * is found or the extent cannot be read, good data will be written back if
  33  * any can be found.
  34  *
  35  * Future enhancements:
  36  *  - In case an unrepairable extent is encountered, track which files are
  37  *    affected and report them
  38  *  - In case of a read error on files with nodatasum, map the file and read
  39  *    the extent to trigger a writeback of the good copy
  40  *  - track and record media errors, throw out bad devices
  41  *  - add a mode to also read unallocated space
  42  */
  43
  44 struct scrub_bio;
  45 struct scrub_page;
  46 struct scrub_dev;
  47 static void scrub_bio_end_io(struct bio *bio, int err);
  48 static void scrub_checksum(struct btrfs_work *work);
  49 static int scrub_checksum_data(struct scrub_dev *sdev,
  50                                struct scrub_page *spag, void *buffer);
  51 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
  52                                      struct scrub_page *spag, u64 logical,
  53                                      void *buffer);
  54 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer);
  55 static int scrub_fixup_check(struct scrub_bio *sbio, int ix);
  56 static void scrub_fixup_end_io(struct bio *bio, int err);
  57 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
  58                           struct page *page);
  59 static void scrub_fixup(struct scrub_bio *sbio, int ix);
  60
  61 #define SCRUB_PAGES_PER_BIO     16      /* 64k per bio */
  62 #define SCRUB_BIOS_PER_DEV      16      /* 1 MB per device in flight */
  63
  64 struct scrub_page {
  65         u64                     flags;  /* extent flags */
  66         u64                     generation;
  67         int                     mirror_num;
  68         int                     have_csum;
  69         u8                      csum[BTRFS_CSUM_SIZE];
  70 };
  71
  72 struct scrub_bio {
  73         int                     index;
  74         struct scrub_dev        *sdev;
  75         struct bio              *bio;
  76         int                     err;
  77         u64                     logical;
  78         u64                     physical;
  79         struct scrub_page       spag[SCRUB_PAGES_PER_BIO];
  80         u64                     count;
  81         int                     next_free;
  82         struct btrfs_work       work;
  83 };
  84
  85 struct scrub_dev {
  86         struct scrub_bio        *bios[SCRUB_BIOS_PER_DEV];
  87         struct btrfs_device     *dev;
  88         int                     first_free;
  89         int                     curr;
  90         atomic_t                in_flight;
  91         atomic_t                fixup_cnt;
  92         spinlock_t              list_lock;
  93         wait_queue_head_t       list_wait;
  94         u16                     csum_size;
  95         struct list_head        csum_list;
  96         atomic_t                cancel_req;
  97         int                     readonly;
  98         /*
  99          * statistics
 100          */
 101         struct btrfs_scrub_progress stat;
 102         spinlock_t              stat_lock;
 103 };
 104
 105 struct scrub_fixup_nodatasum {
 106         struct scrub_dev        *sdev;
 107         u64                     logical;
 108         struct btrfs_root       *root;
 109         struct btrfs_work       work;
 110         int                     mirror_num;
 111 };
 112
 113 struct scrub_warning {
 114         struct btrfs_path       *path;
 115         u64                     extent_item_size;
 116         char                    *scratch_buf;
 117         char                    *msg_buf;
 118         const char              *errstr;
 119         sector_t                sector;
 120         u64                     logical;
 121         struct btrfs_device     *dev;
 122         int                     msg_bufsize;
 123         int                     scratch_bufsize;
 124 };
 125
 126 static void scrub_free_csums(struct scrub_dev *sdev)
 127 {
 128         while (!list_empty(&sdev->csum_list)) {
 129                 struct btrfs_ordered_sum *sum;
 130                 sum = list_first_entry(&sdev->csum_list,
 131                                        struct btrfs_ordered_sum, list);
 132                 list_del(&sum->list);
 133                 kfree(sum);
 134         }
 135 }
 136
 137 static void scrub_free_bio(struct bio *bio)
 138 {
 139         int i;
 140         struct page *last_page = NULL;
 141
 142         if (!bio)
 143                 return;
 144
 145         for (i = 0; i < bio->bi_vcnt; ++i) {
 146                 if (bio->bi_io_vec[i].bv_page == last_page)
 147                         continue;
 148                 last_page = bio->bi_io_vec[i].bv_page;
 149                 __free_page(last_page);
 150         }
 151         bio_put(bio);
 152 }
 153
 154 static noinline_for_stack void scrub_free_dev(struct scrub_dev *sdev)
 155 {
 156         int i;
 157
 158         if (!sdev)
 159                 return;
 160
 161         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
 162                 struct scrub_bio *sbio = sdev->bios[i];
 163
 164                 if (!sbio)
 165                         break;
 166
 167                 scrub_free_bio(sbio->bio);
 168                 kfree(sbio);
 169         }
 170
 171         scrub_free_csums(sdev);
 172         kfree(sdev);
 173 }
 174
 175 static noinline_for_stack
 176 struct scrub_dev *scrub_setup_dev(struct btrfs_device *dev)
 177 {
 178         struct scrub_dev *sdev;
 179         int             i;
 180         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 181
 182         sdev = kzalloc(sizeof(*sdev), GFP_NOFS);
 183         if (!sdev)
 184                 goto nomem;
 185         sdev->dev = dev;
 186         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
 187                 struct scrub_bio *sbio;
 188
 189                 sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
 190                 if (!sbio)
 191                         goto nomem;
 192                 sdev->bios[i] = sbio;
 193
 194                 sbio->index = i;
 195                 sbio->sdev = sdev;
 196                 sbio->count = 0;
 197                 sbio->work.func = scrub_checksum;
 198
 199                 if (i != SCRUB_BIOS_PER_DEV-1)
 200                         sdev->bios[i]->next_free = i + 1;
 201                 else
 202                         sdev->bios[i]->next_free = -1;
 203         }
 204         sdev->first_free = 0;
 205         sdev->curr = -1;
 206         atomic_set(&sdev->in_flight, 0);
 207         atomic_set(&sdev->fixup_cnt, 0);
 208         atomic_set(&sdev->cancel_req, 0);
 209         sdev->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 210         INIT_LIST_HEAD(&sdev->csum_list);
 211
 212         spin_lock_init(&sdev->list_lock);
 213         spin_lock_init(&sdev->stat_lock);
 214         init_waitqueue_head(&sdev->list_wait);
 215         return sdev;
 216
 217 nomem:
 218         scrub_free_dev(sdev);
 219         return ERR_PTR(-ENOMEM);
 220 }
 221
 222 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, void *ctx)
 223 {
 224         u64 isize;
 225         u32 nlink;
 226         int ret;
 227         int i;
 228         struct extent_buffer *eb;
 229         struct btrfs_inode_item *inode_item;
 230         struct scrub_warning *swarn = ctx;
 231         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
 232         struct inode_fs_paths *ipath = NULL;
 233         struct btrfs_root *local_root;
 234         struct btrfs_key root_key;
 235
 236         root_key.objectid = root;
 237         root_key.type = BTRFS_ROOT_ITEM_KEY;
 238         root_key.offset = (u64)-1;
 239         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 240         if (IS_ERR(local_root)) {
 241                 ret = PTR_ERR(local_root);
 242                 goto err;
 243         }
 244
 245         ret = inode_item_info(inum, 0, local_root, swarn->path);
 246         if (ret) {
 247                 btrfs_release_path(swarn->path);
 248                 goto err;
 249         }
 250
 251         eb = swarn->path->nodes[0];
 252         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 253                                         struct btrfs_inode_item);
 254         isize = btrfs_inode_size(eb, inode_item);
 255         nlink = btrfs_inode_nlink(eb, inode_item);
 256         btrfs_release_path(swarn->path);
 257
 258         ipath = init_ipath(4096, local_root, swarn->path);
 259         ret = paths_from_inode(inum, ipath);
 260
 261         if (ret < 0)
 262                 goto err;
 263
 264         /*
 265          * we deliberately ignore the bit ipath might have been too small to
 266          * hold all of the paths here
 267          */
 268         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 269                 printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
 270                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
 271                         "length %llu, links %u (path: %s)\n", swarn->errstr,
 272                         swarn->logical, swarn->dev->name,
 273                         (unsigned long long)swarn->sector, root, inum, offset,
 274                         min(isize - offset, (u64)PAGE_SIZE), nlink,
 275                         (char *)(unsigned long)ipath->fspath->val[i]);
 276
 277         free_ipath(ipath);
 278         return 0;
 279
 280 err:
 281         printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
 282                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
 283                 "resolving failed with ret=%d\n", swarn->errstr,
 284                 swarn->logical, swarn->dev->name,
 285                 (unsigned long long)swarn->sector, root, inum, offset, ret);
 286
 287         free_ipath(ipath);
 288         return 0;
 289 }
 290
 291 static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
 292                                 int ix)
 293 {
 294         struct btrfs_device *dev = sbio->sdev->dev;
 295         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 296         struct btrfs_path *path;
 297         struct btrfs_key found_key;
 298         struct extent_buffer *eb;
 299         struct btrfs_extent_item *ei;
 300         struct scrub_warning swarn;
 301         u32 item_size;
 302         int ret;
 303         u64 ref_root;
 304         u8 ref_level;
 305         unsigned long ptr = 0;
 306         const int bufsize = 4096;
 307         u64 extent_offset;
 308
 309         path = btrfs_alloc_path();
 310
 311         swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
 312         swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
 313         swarn.sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 314         swarn.logical = sbio->logical + ix * PAGE_SIZE;
 315         swarn.errstr = errstr;
 316         swarn.dev = dev;
 317         swarn.msg_bufsize = bufsize;
 318         swarn.scratch_bufsize = bufsize;
 319
 320         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
 321                 goto out;
 322
 323         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key);
 324         if (ret < 0)
 325                 goto out;
 326
 327         extent_offset = swarn.logical - found_key.objectid;
 328         swarn.extent_item_size = found_key.offset;
 329
 330         eb = path->nodes[0];
 331         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 332         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 333
 334         if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 335                 do {
 336                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
 337                                                         &ref_root, &ref_level);
 338                         printk(KERN_WARNING "%s at logical %llu on dev %s, "
 339                                 "sector %llu: metadata %s (level %d) in tree "
 340                                 "%llu\n", errstr, swarn.logical, dev->name,
 341                                 (unsigned long long)swarn.sector,
 342                                 ref_level ? "node" : "leaf",
 343                                 ret < 0 ? -1 : ref_level,
 344                                 ret < 0 ? -1 : ref_root);
 345                 } while (ret != 1);
 346         } else {
 347                 swarn.path = path;
 348                 iterate_extent_inodes(fs_info, path, found_key.objectid,
 349                                         extent_offset,
 350                                         scrub_print_warning_inode, &swarn);
 351         }
 352
 353 out:
 354         btrfs_free_path(path);
 355         kfree(swarn.scratch_buf);
 356         kfree(swarn.msg_buf);
 357 }
 358
 359 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *ctx)
 360 {
 361         struct page *page = NULL;
 362         unsigned long index;
 363         struct scrub_fixup_nodatasum *fixup = ctx;
 364         int ret;
 365         int corrected = 0;
 366         struct btrfs_key key;
 367         struct inode *inode = NULL;
 368         u64 end = offset + PAGE_SIZE - 1;
 369         struct btrfs_root *local_root;
 370
 371         key.objectid = root;
 372         key.type = BTRFS_ROOT_ITEM_KEY;
 373         key.offset = (u64)-1;
 374         local_root = btrfs_read_fs_root_no_name(fixup->root->fs_info, &key);
 375         if (IS_ERR(local_root))
 376                 return PTR_ERR(local_root);
 377
 378         key.type = BTRFS_INODE_ITEM_KEY;
 379         key.objectid = inum;
 380         key.offset = 0;
 381         inode = btrfs_iget(fixup->root->fs_info->sb, &key, local_root, NULL);
 382         if (IS_ERR(inode))
 383                 return PTR_ERR(inode);
 384
 385         index = offset >> PAGE_CACHE_SHIFT;
 386
 387         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 388         if (!page) {
 389                 ret = -ENOMEM;
 390                 goto out;
 391         }
 392
 393         if (PageUptodate(page)) {
 394                 struct btrfs_mapping_tree *map_tree;
 395                 if (PageDirty(page)) {
 396                         /*
 397                          * we need to write the data to the defect sector. the
 398                          * data that was in that sector is not in memory,
 399                          * because the page was modified. we must not write the
 400                          * modified page to that sector.
 401                          *
 402                          * TODO: what could be done here: wait for the delalloc
 403                          *       runner to write out that page (might involve
 404                          *       COW) and see whether the sector is still
 405                          *       referenced afterwards.
 406                          *
 407                          * For the meantime, we'll treat this error
 408                          * incorrectable, although there is a chance that a
 409                          * later scrub will find the bad sector again and that
 410                          * there's no dirty page in memory, then.
 411                          */
 412                         ret = -EIO;
 413                         goto out;
 414                 }
 415                 map_tree = &BTRFS_I(inode)->root->fs_info->mapping_tree;
 416                 ret = repair_io_failure(map_tree, offset, PAGE_SIZE,
 417                                         fixup->logical, page,
 418                                         fixup->mirror_num);
 419                 unlock_page(page);
 420                 corrected = !ret;
 421         } else {
 422                 /*
 423                  * we need to get good data first. the general readpage path
 424                  * will call repair_io_failure for us, we just have to make
 425                  * sure we read the bad mirror.
 426                  */
 427                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 428                                         EXTENT_DAMAGED, GFP_NOFS);
 429                 if (ret) {
 430                         /* set_extent_bits should give proper error */
 431                         WARN_ON(ret > 0);
 432                         if (ret > 0)
 433                                 ret = -EFAULT;
 434                         goto out;
 435                 }
 436
 437                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 438                                                 btrfs_get_extent,
 439                                                 fixup->mirror_num);
 440                 wait_on_page_locked(page);
 441
 442                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 443                                                 end, EXTENT_DAMAGED, 0, NULL);
 444                 if (!corrected)
 445                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 446                                                 EXTENT_DAMAGED, GFP_NOFS);
 447         }
 448
 449 out:
 450         if (page)
 451                 put_page(page);
 452         if (inode)
 453                 iput(inode);
 454
 455         if (ret < 0)
 456                 return ret;
 457
 458         if (ret == 0 && corrected) {
 459                 /*
 460                  * we only need to call readpage for one of the inodes belonging
 461                  * to this extent. so make iterate_extent_inodes stop
 462                  */
 463                 return 1;
 464         }
 465
 466         return -EIO;
 467 }
 468
 469 static void scrub_fixup_nodatasum(struct btrfs_work *work)
 470 {
 471         int ret;
 472         struct scrub_fixup_nodatasum *fixup;
 473         struct scrub_dev *sdev;
 474         struct btrfs_trans_handle *trans = NULL;
 475         struct btrfs_fs_info *fs_info;
 476         struct btrfs_path *path;
 477         int uncorrectable = 0;
 478
 479         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
 480         sdev = fixup->sdev;
 481         fs_info = fixup->root->fs_info;
 482
 483         path = btrfs_alloc_path();
 484         if (!path) {
 485                 spin_lock(&sdev->stat_lock);
 486                 ++sdev->stat.malloc_errors;
 487                 spin_unlock(&sdev->stat_lock);
 488                 uncorrectable = 1;
 489                 goto out;
 490         }
 491
 492         trans = btrfs_join_transaction(fixup->root);
 493         if (IS_ERR(trans)) {
 494                 uncorrectable = 1;
 495                 goto out;
 496         }
 497
 498         /*
 499          * the idea is to trigger a regular read through the standard path. we
 500          * read a page from the (failed) logical address by specifying the
 501          * corresponding copynum of the failed sector. thus, that readpage is
 502          * expected to fail.
 503          * that is the point where on-the-fly error correction will kick in
 504          * (once it's finished) and rewrite the failed sector if a good copy
 505          * can be found.
 506          */
 507         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
 508                                                 path, scrub_fixup_readpage,
 509                                                 fixup);
 510         if (ret < 0) {
 511                 uncorrectable = 1;
 512                 goto out;
 513         }
 514         WARN_ON(ret != 1);
 515
 516         spin_lock(&sdev->stat_lock);
 517         ++sdev->stat.corrected_errors;
 518         spin_unlock(&sdev->stat_lock);
 519
 520 out:
 521         if (trans && !IS_ERR(trans))
 522                 btrfs_end_transaction(trans, fixup->root);
 523         if (uncorrectable) {
 524                 spin_lock(&sdev->stat_lock);
 525                 ++sdev->stat.uncorrectable_errors;
 526                 spin_unlock(&sdev->stat_lock);
 527                 printk_ratelimited(KERN_ERR "btrfs: unable to fixup "
 528                                         "(nodatasum) error at logical %llu\n",
 529                                         fixup->logical);
 530         }
 531
 532         btrfs_free_path(path);
 533         kfree(fixup);
 534
 535         /* see caller why we're pretending to be paused in the scrub counters */
 536         mutex_lock(&fs_info->scrub_lock);
 537         atomic_dec(&fs_info->scrubs_running);
 538         atomic_dec(&fs_info->scrubs_paused);
 539         mutex_unlock(&fs_info->scrub_lock);
 540         atomic_dec(&sdev->fixup_cnt);
 541         wake_up(&fs_info->scrub_pause_wait);
 542         wake_up(&sdev->list_wait);
 543 }
 544
 545 /*
 546  * scrub_recheck_error gets called when either verification of the page
 547  * failed or the bio failed to read, e.g. with EIO. In the latter case,
 548  * recheck_error gets called for every page in the bio, even though only
 549  * one may be bad
 550  */
 551 static int scrub_recheck_error(struct scrub_bio *sbio, int ix)
 552 {
 553         struct scrub_dev *sdev = sbio->sdev;
 554         u64 sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 555         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 556                                         DEFAULT_RATELIMIT_BURST);
 557
 558         if (sbio->err) {
 559                 if (scrub_fixup_io(READ, sbio->sdev->dev->bdev, sector,
 560                                    sbio->bio->bi_io_vec[ix].bv_page) == 0) {
 561                         if (scrub_fixup_check(sbio, ix) == 0)
 562                                 return 0;
 563                 }
 564                 if (__ratelimit(&_rs))
 565                         scrub_print_warning("i/o error", sbio, ix);
 566         } else {
 567                 if (__ratelimit(&_rs))
 568                         scrub_print_warning("checksum error", sbio, ix);
 569         }
 570
 571         spin_lock(&sdev->stat_lock);
 572         ++sdev->stat.read_errors;
 573         spin_unlock(&sdev->stat_lock);
 574
 575         scrub_fixup(sbio, ix);
 576         return 1;
 577 }
 578
 579 static int scrub_fixup_check(struct scrub_bio *sbio, int ix)
 580 {
 581         int ret = 1;
 582         struct page *page;
 583         void *buffer;
 584         u64 flags = sbio->spag[ix].flags;
 585
 586         page = sbio->bio->bi_io_vec[ix].bv_page;
 587         buffer = kmap_atomic(page, KM_USER0);
 588         if (flags & BTRFS_EXTENT_FLAG_DATA) {
 589                 ret = scrub_checksum_data(sbio->sdev,
 590                                           sbio->spag + ix, buffer);
 591         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 592                 ret = scrub_checksum_tree_block(sbio->sdev,
 593                                                 sbio->spag + ix,
 594                                                 sbio->logical + ix * PAGE_SIZE,
 595                                                 buffer);
 596         } else {
 597                 WARN_ON(1);
 598         }
 599         kunmap_atomic(buffer, KM_USER0);
 600
 601         return ret;
 602 }
 603
 604 static void scrub_fixup_end_io(struct bio *bio, int err)
 605 {
 606         complete((struct completion *)bio->bi_private);
 607 }
 608
 609 static void scrub_fixup(struct scrub_bio *sbio, int ix)
 610 {
 611         struct scrub_dev *sdev = sbio->sdev;
 612         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 613         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
 614         struct btrfs_bio *bbio = NULL;
 615         struct scrub_fixup_nodatasum *fixup;
 616         u64 logical = sbio->logical + ix * PAGE_SIZE;
 617         u64 length;
 618         int i;
 619         int ret;
 620         DECLARE_COMPLETION_ONSTACK(complete);
 621
 622         if ((sbio->spag[ix].flags & BTRFS_EXTENT_FLAG_DATA) &&
 623             (sbio->spag[ix].have_csum == 0)) {
 624                 fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
 625                 if (!fixup)
 626                         goto uncorrectable;
 627                 fixup->sdev = sdev;
 628                 fixup->logical = logical;
 629                 fixup->root = fs_info->extent_root;
 630                 fixup->mirror_num = sbio->spag[ix].mirror_num;
 631                 /*
 632                  * increment scrubs_running to prevent cancel requests from
 633                  * completing as long as a fixup worker is running. we must also
 634                  * increment scrubs_paused to prevent deadlocking on pause
 635                  * requests used for transactions commits (as the worker uses a
 636                  * transaction context). it is safe to regard the fixup worker
 637                  * as paused for all matters practical. effectively, we only
 638                  * avoid cancellation requests from completing.
 639                  */
 640                 mutex_lock(&fs_info->scrub_lock);
 641                 atomic_inc(&fs_info->scrubs_running);
 642                 atomic_inc(&fs_info->scrubs_paused);
 643                 mutex_unlock(&fs_info->scrub_lock);
 644                 atomic_inc(&sdev->fixup_cnt);
 645                 fixup->work.func = scrub_fixup_nodatasum;
 646                 btrfs_queue_worker(&fs_info->scrub_workers, &fixup->work);
 647                 return;
 648         }
 649
 650         length = PAGE_SIZE;
 651         ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length,
 652                               &bbio, 0);
 653         if (ret || !bbio || length < PAGE_SIZE) {
 654                 printk(KERN_ERR
 655                        "scrub_fixup: btrfs_map_block failed us for %llu\n",
 656                        (unsigned long long)logical);
 657                 WARN_ON(1);
 658                 kfree(bbio);
 659                 return;
 660         }
 661
 662         if (bbio->num_stripes == 1)
 663                 /* there aren't any replicas */
 664                 goto uncorrectable;
 665
 666         /*
 667          * first find a good copy
 668          */
 669         for (i = 0; i < bbio->num_stripes; ++i) {
 670                 if (i + 1 == sbio->spag[ix].mirror_num)
 671                         continue;
 672
 673                 if (scrub_fixup_io(READ, bbio->stripes[i].dev->bdev,
 674                                    bbio->stripes[i].physical >> 9,
 675                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 676                         /* I/O-error, this is not a good copy */
 677                         continue;
 678                 }
 679
 680                 if (scrub_fixup_check(sbio, ix) == 0)
 681                         break;
 682         }
 683         if (i == bbio->num_stripes)
 684                 goto uncorrectable;
 685
 686         if (!sdev->readonly) {
 687                 /*
 688                  * bi_io_vec[ix].bv_page now contains good data, write it back
 689                  */
 690                 if (scrub_fixup_io(WRITE, sdev->dev->bdev,
 691                                    (sbio->physical + ix * PAGE_SIZE) >> 9,
 692                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 693                         /* I/O-error, writeback failed, give up */
 694                         goto uncorrectable;
 695                 }
 696         }
 697
 698         kfree(bbio);
 699         spin_lock(&sdev->stat_lock);
 700         ++sdev->stat.corrected_errors;
 701         spin_unlock(&sdev->stat_lock);
 702
 703         printk_ratelimited(KERN_ERR "btrfs: fixed up error at logical %llu\n",
 704                                (unsigned long long)logical);
 705         return;
 706
 707 uncorrectable:
 708         kfree(bbio);
 709         spin_lock(&sdev->stat_lock);
 710         ++sdev->stat.uncorrectable_errors;
 711         spin_unlock(&sdev->stat_lock);
 712
 713         printk_ratelimited(KERN_ERR "btrfs: unable to fixup (regular) error at "
 714                                 "logical %llu\n", (unsigned long long)logical);
 715 }
 716
 717 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
 718                          struct page *page)
 719 {
 720         struct bio *bio = NULL;
 721         int ret;
 722         DECLARE_COMPLETION_ONSTACK(complete);
 723
 724         bio = bio_alloc(GFP_NOFS, 1);
 725         bio->bi_bdev = bdev;
 726         bio->bi_sector = sector;
 727         bio_add_page(bio, page, PAGE_SIZE, 0);
 728         bio->bi_end_io = scrub_fixup_end_io;
 729         bio->bi_private = &complete;
 730         submit_bio(rw, bio);
 731
 732         /* this will also unplug the queue */
 733         wait_for_completion(&complete);
 734
 735         ret = !test_bit(BIO_UPTODATE, &bio->bi_flags);
 736         bio_put(bio);
 737         return ret;
 738 }
 739
 740 static void scrub_bio_end_io(struct bio *bio, int err)
 741 {
 742         struct scrub_bio *sbio = bio->bi_private;
 743         struct scrub_dev *sdev = sbio->sdev;
 744         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 745
 746         sbio->err = err;
 747         sbio->bio = bio;
 748
 749         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
 750 }
 751
 752 static void scrub_checksum(struct btrfs_work *work)
 753 {
 754         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
 755         struct scrub_dev *sdev = sbio->sdev;
 756         struct page *page;
 757         void *buffer;
 758         int i;
 759         u64 flags;
 760         u64 logical;
 761         int ret;
 762
 763         if (sbio->err) {
 764                 ret = 0;
 765                 for (i = 0; i < sbio->count; ++i)
 766                         ret |= scrub_recheck_error(sbio, i);
 767                 if (!ret) {
 768                         spin_lock(&sdev->stat_lock);
 769                         ++sdev->stat.unverified_errors;
 770                         spin_unlock(&sdev->stat_lock);
 771                 }
 772
 773                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
 774                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
 775                 sbio->bio->bi_phys_segments = 0;
 776                 sbio->bio->bi_idx = 0;
 777
 778                 for (i = 0; i < sbio->count; i++) {
 779                         struct bio_vec *bi;
 780                         bi = &sbio->bio->bi_io_vec[i];
 781                         bi->bv_offset = 0;
 782                         bi->bv_len = PAGE_SIZE;
 783                 }
 784                 goto out;
 785         }
 786         for (i = 0; i < sbio->count; ++i) {
 787                 page = sbio->bio->bi_io_vec[i].bv_page;
 788                 buffer = kmap_atomic(page, KM_USER0);
 789                 flags = sbio->spag[i].flags;
 790                 logical = sbio->logical + i * PAGE_SIZE;
 791                 ret = 0;
 792                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
 793                         ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
 794                 } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 795                         ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
 796                                                         logical, buffer);
 797                 } else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
 798                         BUG_ON(i);
 799                         (void)scrub_checksum_super(sbio, buffer);
 800                 } else {
 801                         WARN_ON(1);
 802                 }
 803                 kunmap_atomic(buffer, KM_USER0);
 804                 if (ret) {
 805                         ret = scrub_recheck_error(sbio, i);
 806                         if (!ret) {
 807                                 spin_lock(&sdev->stat_lock);
 808                                 ++sdev->stat.unverified_errors;
 809                                 spin_unlock(&sdev->stat_lock);
 810                         }
 811                 }
 812         }
 813
 814 out:
 815         scrub_free_bio(sbio->bio);
 816         sbio->bio = NULL;
 817         spin_lock(&sdev->list_lock);
 818         sbio->next_free = sdev->first_free;
 819         sdev->first_free = sbio->index;
 820         spin_unlock(&sdev->list_lock);
 821         atomic_dec(&sdev->in_flight);
 822         wake_up(&sdev->list_wait);
 823 }
 824
 825 static int scrub_checksum_data(struct scrub_dev *sdev,
 826                                struct scrub_page *spag, void *buffer)
 827 {
 828         u8 csum[BTRFS_CSUM_SIZE];
 829         u32 crc = ~(u32)0;
 830         int fail = 0;
 831         struct btrfs_root *root = sdev->dev->dev_root;
 832
 833         if (!spag->have_csum)
 834                 return 0;
 835
 836         crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
 837         btrfs_csum_final(crc, csum);
 838         if (memcmp(csum, spag->csum, sdev->csum_size))
 839                 fail = 1;
 840
 841         spin_lock(&sdev->stat_lock);
 842         ++sdev->stat.data_extents_scrubbed;
 843         sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
 844         if (fail)
 845                 ++sdev->stat.csum_errors;
 846         spin_unlock(&sdev->stat_lock);
 847
 848         return fail;
 849 }
 850
 851 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
 852                                      struct scrub_page *spag, u64 logical,
 853                                      void *buffer)
 854 {
 855         struct btrfs_header *h;
 856         struct btrfs_root *root = sdev->dev->dev_root;
 857         struct btrfs_fs_info *fs_info = root->fs_info;
 858         u8 csum[BTRFS_CSUM_SIZE];
 859         u32 crc = ~(u32)0;
 860         int fail = 0;
 861         int crc_fail = 0;
 862
 863         /*
 864          * we don't use the getter functions here, as we
 865          * a) don't have an extent buffer and
 866          * b) the page is already kmapped
 867          */
 868         h = (struct btrfs_header *)buffer;
 869
 870         if (logical != le64_to_cpu(h->bytenr))
 871                 ++fail;
 872
 873         if (spag->generation != le64_to_cpu(h->generation))
 874                 ++fail;
 875
 876         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 877                 ++fail;
 878
 879         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
 880                    BTRFS_UUID_SIZE))
 881                 ++fail;
 882
 883         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 884                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 885         btrfs_csum_final(crc, csum);
 886         if (memcmp(csum, h->csum, sdev->csum_size))
 887                 ++crc_fail;
 888
 889         spin_lock(&sdev->stat_lock);
 890         ++sdev->stat.tree_extents_scrubbed;
 891         sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
 892         if (crc_fail)
 893                 ++sdev->stat.csum_errors;
 894         if (fail)
 895                 ++sdev->stat.verify_errors;
 896         spin_unlock(&sdev->stat_lock);
 897
 898         return fail || crc_fail;
 899 }
 900
 901 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
 902 {
 903         struct btrfs_super_block *s;
 904         u64 logical;
 905         struct scrub_dev *sdev = sbio->sdev;
 906         struct btrfs_root *root = sdev->dev->dev_root;
 907         struct btrfs_fs_info *fs_info = root->fs_info;
 908         u8 csum[BTRFS_CSUM_SIZE];
 909         u32 crc = ~(u32)0;
 910         int fail = 0;
 911
 912         s = (struct btrfs_super_block *)buffer;
 913         logical = sbio->logical;
 914
 915         if (logical != le64_to_cpu(s->bytenr))
 916                 ++fail;
 917
 918         if (sbio->spag[0].generation != le64_to_cpu(s->generation))
 919                 ++fail;
 920
 921         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 922                 ++fail;
 923
 924         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 925                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 926         btrfs_csum_final(crc, csum);
 927         if (memcmp(csum, s->csum, sbio->sdev->csum_size))
 928                 ++fail;
 929
 930         if (fail) {
 931                 /*
 932                  * if we find an error in a super block, we just report it.
 933                  * They will get written with the next transaction commit
 934                  * anyway
 935                  */
 936                 spin_lock(&sdev->stat_lock);
 937                 ++sdev->stat.super_errors;
 938                 spin_unlock(&sdev->stat_lock);
 939         }
 940
 941         return fail;
 942 }
 943
 944 static int scrub_submit(struct scrub_dev *sdev)
 945 {
 946         struct scrub_bio *sbio;
 947
 948         if (sdev->curr == -1)
 949                 return 0;
 950
 951         sbio = sdev->bios[sdev->curr];
 952         sbio->err = 0;
 953         sdev->curr = -1;
 954         atomic_inc(&sdev->in_flight);
 955
 956         submit_bio(READ, sbio->bio);
 957
 958         return 0;
 959 }
 960
 961 static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
 962                       u64 physical, u64 flags, u64 gen, int mirror_num,
 963                       u8 *csum, int force)
 964 {
 965         struct scrub_bio *sbio;
 966         struct page *page;
 967         int ret;
 968
 969 again:
 970         /*
 971          * grab a fresh bio or wait for one to become available
 972          */
 973         while (sdev->curr == -1) {
 974                 spin_lock(&sdev->list_lock);
 975                 sdev->curr = sdev->first_free;
 976                 if (sdev->curr != -1) {
 977                         sdev->first_free = sdev->bios[sdev->curr]->next_free;
 978                         sdev->bios[sdev->curr]->next_free = -1;
 979                         sdev->bios[sdev->curr]->count = 0;
 980                         spin_unlock(&sdev->list_lock);
 981                 } else {
 982                         spin_unlock(&sdev->list_lock);
 983                         wait_event(sdev->list_wait, sdev->first_free != -1);
 984                 }
 985         }
 986         sbio = sdev->bios[sdev->curr];
 987         if (sbio->count == 0) {
 988                 struct bio *bio;
 989
 990                 sbio->physical = physical;
 991                 sbio->logical = logical;
 992                 bio = bio_alloc(GFP_NOFS, SCRUB_PAGES_PER_BIO);
 993                 if (!bio)
 994                         return -ENOMEM;
 995
 996                 bio->bi_private = sbio;
 997                 bio->bi_end_io = scrub_bio_end_io;
 998                 bio->bi_bdev = sdev->dev->bdev;
 999                 bio->bi_sector = sbio->physical >> 9;
1000                 sbio->err = 0;
1001                 sbio->bio = bio;
1002         } else if (sbio->physical + sbio->count * PAGE_SIZE != physical ||
1003                    sbio->logical + sbio->count * PAGE_SIZE != logical) {
1004                 ret = scrub_submit(sdev);
1005                 if (ret)
1006                         return ret;
1007                 goto again;
1008         }
1009         sbio->spag[sbio->count].flags = flags;
1010         sbio->spag[sbio->count].generation = gen;
1011         sbio->spag[sbio->count].have_csum = 0;
1012         sbio->spag[sbio->count].mirror_num = mirror_num;
1013
1014         page = alloc_page(GFP_NOFS);
1015         if (!page)
1016                 return -ENOMEM;
1017
1018         ret = bio_add_page(sbio->bio, page, PAGE_SIZE, 0);
1019         if (!ret) {
1020                 __free_page(page);
1021                 ret = scrub_submit(sdev);
1022                 if (ret)
1023                         return ret;
1024                 goto again;
1025         }
1026
1027         if (csum) {
1028                 sbio->spag[sbio->count].have_csum = 1;
1029                 memcpy(sbio->spag[sbio->count].csum, csum, sdev->csum_size);
1030         }
1031         ++sbio->count;
1032         if (sbio->count == SCRUB_PAGES_PER_BIO || force) {
1033                 int ret;
1034
1035                 ret = scrub_submit(sdev);
1036                 if (ret)
1037                         return ret;
1038         }
1039
1040         return 0;
1041 }
1042
1043 static int scrub_find_csum(struct scrub_dev *sdev, u64 logical, u64 len,
1044                            u8 *csum)
1045 {
1046         struct btrfs_ordered_sum *sum = NULL;
1047         int ret = 0;
1048         unsigned long i;
1049         unsigned long num_sectors;
1050         u32 sectorsize = sdev->dev->dev_root->sectorsize;
1051
1052         while (!list_empty(&sdev->csum_list)) {
1053                 sum = list_first_entry(&sdev->csum_list,
1054                                        struct btrfs_ordered_sum, list);
1055                 if (sum->bytenr > logical)
1056                         return 0;
1057                 if (sum->bytenr + sum->len > logical)
1058                         break;
1059
1060                 ++sdev->stat.csum_discards;
1061                 list_del(&sum->list);
1062                 kfree(sum);
1063                 sum = NULL;
1064         }
1065         if (!sum)
1066                 return 0;
1067
1068         num_sectors = sum->len / sectorsize;
1069         for (i = 0; i < num_sectors; ++i) {
1070                 if (sum->sums[i].bytenr == logical) {
1071                         memcpy(csum, &sum->sums[i].sum, sdev->csum_size);
1072                         ret = 1;
1073                         break;
1074                 }
1075         }
1076         if (ret && i == num_sectors - 1) {
1077                 list_del(&sum->list);
1078                 kfree(sum);
1079         }
1080         return ret;
1081 }
1082
1083 /* scrub extent tries to collect up to 64 kB for each bio */
1084 static int scrub_extent(struct scrub_dev *sdev, u64 logical, u64 len,
1085                         u64 physical, u64 flags, u64 gen, int mirror_num)
1086 {
1087         int ret;
1088         u8 csum[BTRFS_CSUM_SIZE];
1089
1090         while (len) {
1091                 u64 l = min_t(u64, len, PAGE_SIZE);
1092                 int have_csum = 0;
1093
1094                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
1095                         /* push csums to sbio */
1096                         have_csum = scrub_find_csum(sdev, logical, l, csum);
1097                         if (have_csum == 0)
1098                                 ++sdev->stat.no_csum;
1099                 }
1100                 ret = scrub_page(sdev, logical, l, physical, flags, gen,
1101                                  mirror_num, have_csum ? csum : NULL, 0);
1102                 if (ret)
1103                         return ret;
1104                 len -= l;
1105                 logical += l;
1106                 physical += l;
1107         }
1108         return 0;
1109 }
1110
1111 static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
1112         struct map_lookup *map, int num, u64 base, u64 length)
1113 {
1114         struct btrfs_path *path;
1115         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
1116         struct btrfs_root *root = fs_info->extent_root;
1117         struct btrfs_root *csum_root = fs_info->csum_root;
1118         struct btrfs_extent_item *extent;
1119         struct blk_plug plug;
1120         u64 flags;
1121         int ret;
1122         int slot;
1123         int i;
1124         u64 nstripes;
1125         struct extent_buffer *l;
1126         struct btrfs_key key;
1127         u64 physical;
1128         u64 logical;
1129         u64 generation;
1130         int mirror_num;
1131         struct reada_control *reada1;
1132         struct reada_control *reada2;
1133         struct btrfs_key key_start;
1134         struct btrfs_key key_end;
1135
1136         u64 increment = map->stripe_len;
1137         u64 offset;
1138
1139         nstripes = length;
1140         offset = 0;
1141         do_div(nstripes, map->stripe_len);
1142         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
1143                 offset = map->stripe_len * num;
1144                 increment = map->stripe_len * map->num_stripes;
1145                 mirror_num = 1;
1146         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1147                 int factor = map->num_stripes / map->sub_stripes;
1148                 offset = map->stripe_len * (num / map->sub_stripes);
1149                 increment = map->stripe_len * factor;
1150                 mirror_num = num % map->sub_stripes + 1;
1151         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
1152                 increment = map->stripe_len;
1153                 mirror_num = num % map->num_stripes + 1;
1154         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
1155                 increment = map->stripe_len;
1156                 mirror_num = num % map->num_stripes + 1;
1157         } else {
1158                 increment = map->stripe_len;
1159                 mirror_num = 1;
1160         }
1161
1162         path = btrfs_alloc_path();
1163         if (!path)
1164                 return -ENOMEM;
1165
1166         path->search_commit_root = 1;
1167         path->skip_locking = 1;
1168
1169         /*
1170          * trigger the readahead for extent tree csum tree and wait for
1171          * completion. During readahead, the scrub is officially paused
1172          * to not hold off transaction commits
1173          */
1174         logical = base + offset;
1175
1176         wait_event(sdev->list_wait,
1177                    atomic_read(&sdev->in_flight) == 0);
1178         atomic_inc(&fs_info->scrubs_paused);
1179         wake_up(&fs_info->scrub_pause_wait);
1180
1181         /* FIXME it might be better to start readahead at commit root */
1182         key_start.objectid = logical;
1183         key_start.type = BTRFS_EXTENT_ITEM_KEY;
1184         key_start.offset = (u64)0;
1185         key_end.objectid = base + offset + nstripes * increment;
1186         key_end.type = BTRFS_EXTENT_ITEM_KEY;
1187         key_end.offset = (u64)0;
1188         reada1 = btrfs_reada_add(root, &key_start, &key_end);
1189
1190         key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1191         key_start.type = BTRFS_EXTENT_CSUM_KEY;
1192         key_start.offset = logical;
1193         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1194         key_end.type = BTRFS_EXTENT_CSUM_KEY;
1195         key_end.offset = base + offset + nstripes * increment;
1196         reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);
1197
1198         if (!IS_ERR(reada1))
1199                 btrfs_reada_wait(reada1);
1200         if (!IS_ERR(reada2))
1201                 btrfs_reada_wait(reada2);
1202
1203         mutex_lock(&fs_info->scrub_lock);
1204         while (atomic_read(&fs_info->scrub_pause_req)) {
1205                 mutex_unlock(&fs_info->scrub_lock);
1206                 wait_event(fs_info->scrub_pause_wait,
1207                    atomic_read(&fs_info->scrub_pause_req) == 0);
1208                 mutex_lock(&fs_info->scrub_lock);
1209         }
1210         atomic_dec(&fs_info->scrubs_paused);
1211         mutex_unlock(&fs_info->scrub_lock);
1212         wake_up(&fs_info->scrub_pause_wait);
1213
1214         /*
1215          * collect all data csums for the stripe to avoid seeking during
1216          * the scrub. This might currently (crc32) end up to be about 1MB
1217          */
1218         blk_start_plug(&plug);
1219
1220         /*
1221          * now find all extents for each stripe and scrub them
1222          */
1223         logical = base + offset;
1224         physical = map->stripes[num].physical;
1225         ret = 0;
1226         for (i = 0; i < nstripes; ++i) {
1227                 /*
1228                  * canceled?
1229                  */
1230                 if (atomic_read(&fs_info->scrub_cancel_req) ||
1231                     atomic_read(&sdev->cancel_req)) {
1232                         ret = -ECANCELED;
1233                         goto out;
1234                 }
1235                 /*
1236                  * check to see if we have to pause
1237                  */
1238                 if (atomic_read(&fs_info->scrub_pause_req)) {
1239                         /* push queued extents */
1240                         scrub_submit(sdev);
1241                         wait_event(sdev->list_wait,
1242                                    atomic_read(&sdev->in_flight) == 0);
1243                         atomic_inc(&fs_info->scrubs_paused);
1244                         wake_up(&fs_info->scrub_pause_wait);
1245                         mutex_lock(&fs_info->scrub_lock);
1246                         while (atomic_read(&fs_info->scrub_pause_req)) {
1247                                 mutex_unlock(&fs_info->scrub_lock);
1248                                 wait_event(fs_info->scrub_pause_wait,
1249                                    atomic_read(&fs_info->scrub_pause_req) == 0);
1250                                 mutex_lock(&fs_info->scrub_lock);
1251                         }
1252                         atomic_dec(&fs_info->scrubs_paused);
1253                         mutex_unlock(&fs_info->scrub_lock);
1254                         wake_up(&fs_info->scrub_pause_wait);
1255                 }
1256
1257                 ret = btrfs_lookup_csums_range(csum_root, logical,
1258                                                logical + map->stripe_len - 1,
1259                                                &sdev->csum_list, 1);
1260                 if (ret)
1261                         goto out;
1262
1263                 key.objectid = logical;
1264                 key.type = BTRFS_EXTENT_ITEM_KEY;
1265                 key.offset = (u64)0;
1266
1267                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1268                 if (ret < 0)
1269                         goto out;
1270                 if (ret > 0) {
1271                         ret = btrfs_previous_item(root, path, 0,
1272                                                   BTRFS_EXTENT_ITEM_KEY);
1273                         if (ret < 0)
1274                                 goto out;
1275                         if (ret > 0) {
1276                                 /* there's no smaller item, so stick with the
1277                                  * larger one */
1278                                 btrfs_release_path(path);
1279                                 ret = btrfs_search_slot(NULL, root, &key,
1280                                                         path, 0, 0);
1281                                 if (ret < 0)
1282                                         goto out;
1283                         }
1284                 }
1285
1286                 while (1) {
1287                         l = path->nodes[0];
1288                         slot = path->slots[0];
1289                         if (slot >= btrfs_header_nritems(l)) {
1290                                 ret = btrfs_next_leaf(root, path);
1291                                 if (ret == 0)
1292                                         continue;
1293                                 if (ret < 0)
1294                                         goto out;
1295
1296                                 break;
1297                         }
1298                         btrfs_item_key_to_cpu(l, &key, slot);
1299
1300                         if (key.objectid + key.offset <= logical)
1301                                 goto next;
1302
1303                         if (key.objectid >= logical + map->stripe_len)
1304                                 break;
1305
1306                         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
1307                                 goto next;
1308
1309                         extent = btrfs_item_ptr(l, slot,
1310                                                 struct btrfs_extent_item);
1311                         flags = btrfs_extent_flags(l, extent);
1312                         generation = btrfs_extent_generation(l, extent);
1313
1314                         if (key.objectid < logical &&
1315                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
1316                                 printk(KERN_ERR
1317                                        "btrfs scrub: tree block %llu spanning "
1318                                        "stripes, ignored. logical=%llu\n",
1319                                        (unsigned long long)key.objectid,
1320                                        (unsigned long long)logical);
1321                                 goto next;
1322                         }
1323
1324                         /*
1325                          * trim extent to this stripe
1326                          */
1327                         if (key.objectid < logical) {
1328                                 key.offset -= logical - key.objectid;
1329                                 key.objectid = logical;
1330                         }
1331                         if (key.objectid + key.offset >
1332                             logical + map->stripe_len) {
1333                                 key.offset = logical + map->stripe_len -
1334                                              key.objectid;
1335                         }
1336
1337                         ret = scrub_extent(sdev, key.objectid, key.offset,
1338                                            key.objectid - logical + physical,
1339                                            flags, generation, mirror_num);
1340                         if (ret)
1341                                 goto out;
1342
1343 next:
1344                         path->slots[0]++;
1345                 }
1346                 btrfs_release_path(path);
1347                 logical += increment;
1348                 physical += map->stripe_len;
1349                 spin_lock(&sdev->stat_lock);
1350                 sdev->stat.last_physical = physical;
1351                 spin_unlock(&sdev->stat_lock);
1352         }
1353         /* push queued extents */
1354         scrub_submit(sdev);
1355
1356 out:
1357         blk_finish_plug(&plug);
1358         btrfs_free_path(path);
1359         return ret < 0 ? ret : 0;
1360 }
1361
1362 static noinline_for_stack int scrub_chunk(struct scrub_dev *sdev,
1363         u64 chunk_tree, u64 chunk_objectid, u64 chunk_offset, u64 length)
1364 {
1365         struct btrfs_mapping_tree *map_tree =
1366                 &sdev->dev->dev_root->fs_info->mapping_tree;
1367         struct map_lookup *map;
1368         struct extent_map *em;
1369         int i;
1370         int ret = -EINVAL;
1371
1372         read_lock(&map_tree->map_tree.lock);
1373         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
1374         read_unlock(&map_tree->map_tree.lock);
1375
1376         if (!em)
1377                 return -EINVAL;
1378
1379         map = (struct map_lookup *)em->bdev;
1380         if (em->start != chunk_offset)
1381                 goto out;
1382
1383         if (em->len < length)
1384                 goto out;
1385
1386         for (i = 0; i < map->num_stripes; ++i) {
1387                 if (map->stripes[i].dev == sdev->dev) {
1388                         ret = scrub_stripe(sdev, map, i, chunk_offset, length);
1389                         if (ret)
1390                                 goto out;
1391                 }
1392         }
1393 out:
1394         free_extent_map(em);
1395
1396         return ret;
1397 }
1398
1399 static noinline_for_stack
1400 int scrub_enumerate_chunks(struct scrub_dev *sdev, u64 start, u64 end)
1401 {
1402         struct btrfs_dev_extent *dev_extent = NULL;
1403         struct btrfs_path *path;
1404         struct btrfs_root *root = sdev->dev->dev_root;
1405         struct btrfs_fs_info *fs_info = root->fs_info;
1406         u64 length;
1407         u64 chunk_tree;
1408         u64 chunk_objectid;
1409         u64 chunk_offset;
1410         int ret;
1411         int slot;
1412         struct extent_buffer *l;
1413         struct btrfs_key key;
1414         struct btrfs_key found_key;
1415         struct btrfs_block_group_cache *cache;
1416
1417         path = btrfs_alloc_path();
1418         if (!path)
1419                 return -ENOMEM;
1420
1421         path->reada = 2;
1422         path->search_commit_root = 1;
1423         path->skip_locking = 1;
1424
1425         key.objectid = sdev->dev->devid;
1426         key.offset = 0ull;
1427         key.type = BTRFS_DEV_EXTENT_KEY;
1428
1429
1430         while (1) {
1431                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1432                 if (ret < 0)
1433                         break;
1434                 if (ret > 0) {
1435                         if (path->slots[0] >=
1436                             btrfs_header_nritems(path->nodes[0])) {
1437                                 ret = btrfs_next_leaf(root, path);
1438                                 if (ret)
1439                                         break;
1440                         }
1441                 }
1442
1443                 l = path->nodes[0];
1444                 slot = path->slots[0];
1445
1446                 btrfs_item_key_to_cpu(l, &found_key, slot);
1447
1448                 if (found_key.objectid != sdev->dev->devid)
1449                         break;
1450
1451                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
1452                         break;
1453
1454                 if (found_key.offset >= end)
1455                         break;
1456
1457                 if (found_key.offset < key.offset)
1458                         break;
1459
1460                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
1461                 length = btrfs_dev_extent_length(l, dev_extent);
1462
1463                 if (found_key.offset + length <= start) {
1464                         key.offset = found_key.offset + length;
1465                         btrfs_release_path(path);
1466                         continue;
1467                 }
1468
1469                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
1470                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
1471                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
1472
1473                 /*
1474                  * get a reference on the corresponding block group to prevent
1475                  * the chunk from going away while we scrub it
1476                  */
1477                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
1478                 if (!cache) {
1479                         ret = -ENOENT;
1480                         break;
1481                 }
1482                 ret = scrub_chunk(sdev, chunk_tree, chunk_objectid,
1483                                   chunk_offset, length);
1484                 btrfs_put_block_group(cache);
1485                 if (ret)
1486                         break;
1487
1488                 key.offset = found_key.offset + length;
1489                 btrfs_release_path(path);
1490         }
1491
1492         btrfs_free_path(path);
1493
1494         /*
1495          * ret can still be 1 from search_slot or next_leaf,
1496          * that's not an error
1497          */
1498         return ret < 0 ? ret : 0;
1499 }
1500
1501 static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
1502 {
1503         int     i;
1504         u64     bytenr;
1505         u64     gen;
1506         int     ret;
1507         struct btrfs_device *device = sdev->dev;
1508         struct btrfs_root *root = device->dev_root;
1509
1510         gen = root->fs_info->last_trans_committed;
1511
1512         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
1513                 bytenr = btrfs_sb_offset(i);
1514                 if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
1515                         break;
1516
1517                 ret = scrub_page(sdev, bytenr, PAGE_SIZE, bytenr,
1518                                  BTRFS_EXTENT_FLAG_SUPER, gen, i, NULL, 1);
1519                 if (ret)
1520                         return ret;
1521         }
1522         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1523
1524         return 0;
1525 }
1526
1527 /*
1528  * get a reference count on fs_info->scrub_workers. start worker if necessary
1529  */
1530 static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
1531 {
1532         struct btrfs_fs_info *fs_info = root->fs_info;
1533
1534         mutex_lock(&fs_info->scrub_lock);
1535         if (fs_info->scrub_workers_refcnt == 0) {
1536                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
1537                            fs_info->thread_pool_size, &fs_info->generic_worker);
1538                 fs_info->scrub_workers.idle_thresh = 4;
1539                 btrfs_start_workers(&fs_info->scrub_workers, 1);
1540         }
1541         ++fs_info->scrub_workers_refcnt;
1542         mutex_unlock(&fs_info->scrub_lock);
1543
1544         return 0;
1545 }
1546
1547 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
1548 {
1549         struct btrfs_fs_info *fs_info = root->fs_info;
1550
1551         mutex_lock(&fs_info->scrub_lock);
1552         if (--fs_info->scrub_workers_refcnt == 0)
1553                 btrfs_stop_workers(&fs_info->scrub_workers);
1554         WARN_ON(fs_info->scrub_workers_refcnt < 0);
1555         mutex_unlock(&fs_info->scrub_lock);
1556 }
1557
1558
1559 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
1560                     struct btrfs_scrub_progress *progress, int readonly)
1561 {
1562         struct scrub_dev *sdev;
1563         struct btrfs_fs_info *fs_info = root->fs_info;
1564         int ret;
1565         struct btrfs_device *dev;
1566
1567         if (btrfs_fs_closing(root->fs_info))
1568                 return -EINVAL;
1569
1570         /*
1571          * check some assumptions
1572          */
1573         if (root->sectorsize != PAGE_SIZE ||
1574             root->sectorsize != root->leafsize ||
1575             root->sectorsize != root->nodesize) {
1576                 printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
1577                 return -EINVAL;
1578         }
1579
1580         ret = scrub_workers_get(root);
1581         if (ret)
1582                 return ret;
1583
1584         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1585         dev = btrfs_find_device(root, devid, NULL, NULL);
1586         if (!dev || dev->missing) {
1587                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1588                 scrub_workers_put(root);
1589                 return -ENODEV;
1590         }
1591         mutex_lock(&fs_info->scrub_lock);
1592
1593         if (!dev->in_fs_metadata) {
1594                 mutex_unlock(&fs_info->scrub_lock);
1595                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1596                 scrub_workers_put(root);
1597                 return -ENODEV;
1598         }
1599
1600         if (dev->scrub_device) {
1601                 mutex_unlock(&fs_info->scrub_lock);
1602                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1603                 scrub_workers_put(root);
1604                 return -EINPROGRESS;
1605         }
1606         sdev = scrub_setup_dev(dev);
1607         if (IS_ERR(sdev)) {
1608                 mutex_unlock(&fs_info->scrub_lock);
1609                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1610                 scrub_workers_put(root);
1611                 return PTR_ERR(sdev);
1612         }
1613         sdev->readonly = readonly;
1614         dev->scrub_device = sdev;
1615
1616         atomic_inc(&fs_info->scrubs_running);
1617         mutex_unlock(&fs_info->scrub_lock);
1618         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1619
1620         down_read(&fs_info->scrub_super_lock);
1621         ret = scrub_supers(sdev);
1622         up_read(&fs_info->scrub_super_lock);
1623
1624         if (!ret)
1625                 ret = scrub_enumerate_chunks(sdev, start, end);
1626
1627         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1628         atomic_dec(&fs_info->scrubs_running);
1629         wake_up(&fs_info->scrub_pause_wait);
1630
1631         wait_event(sdev->list_wait, atomic_read(&sdev->fixup_cnt) == 0);
1632
1633         if (progress)
1634                 memcpy(progress, &sdev->stat, sizeof(*progress));
1635
1636         mutex_lock(&fs_info->scrub_lock);
1637         dev->scrub_device = NULL;
1638         mutex_unlock(&fs_info->scrub_lock);
1639
1640         scrub_free_dev(sdev);
1641         scrub_workers_put(root);
1642
1643         return ret;
1644 }
1645
1646 int btrfs_scrub_pause(struct btrfs_root *root)
1647 {
1648         struct btrfs_fs_info *fs_info = root->fs_info;
1649
1650         mutex_lock(&fs_info->scrub_lock);
1651         atomic_inc(&fs_info->scrub_pause_req);
1652         while (atomic_read(&fs_info->scrubs_paused) !=
1653                atomic_read(&fs_info->scrubs_running)) {
1654                 mutex_unlock(&fs_info->scrub_lock);
1655                 wait_event(fs_info->scrub_pause_wait,
1656                            atomic_read(&fs_info->scrubs_paused) ==
1657                            atomic_read(&fs_info->scrubs_running));
1658                 mutex_lock(&fs_info->scrub_lock);
1659         }
1660         mutex_unlock(&fs_info->scrub_lock);
1661
1662         return 0;
1663 }
1664
1665 int btrfs_scrub_continue(struct btrfs_root *root)
1666 {
1667         struct btrfs_fs_info *fs_info = root->fs_info;
1668
1669         atomic_dec(&fs_info->scrub_pause_req);
1670         wake_up(&fs_info->scrub_pause_wait);
1671         return 0;
1672 }
1673
1674 int btrfs_scrub_pause_super(struct btrfs_root *root)
1675 {
1676         down_write(&root->fs_info->scrub_super_lock);
1677         return 0;
1678 }
1679
1680 int btrfs_scrub_continue_super(struct btrfs_root *root)
1681 {
1682         up_write(&root->fs_info->scrub_super_lock);
1683         return 0;
1684 }
1685
1686 int btrfs_scrub_cancel(struct btrfs_root *root)
1687 {
1688         struct btrfs_fs_info *fs_info = root->fs_info;
1689
1690         mutex_lock(&fs_info->scrub_lock);
1691         if (!atomic_read(&fs_info->scrubs_running)) {
1692                 mutex_unlock(&fs_info->scrub_lock);
1693                 return -ENOTCONN;
1694         }
1695
1696         atomic_inc(&fs_info->scrub_cancel_req);
1697         while (atomic_read(&fs_info->scrubs_running)) {
1698                 mutex_unlock(&fs_info->scrub_lock);
1699                 wait_event(fs_info->scrub_pause_wait,
1700                            atomic_read(&fs_info->scrubs_running) == 0);
1701                 mutex_lock(&fs_info->scrub_lock);
1702         }
1703         atomic_dec(&fs_info->scrub_cancel_req);
1704         mutex_unlock(&fs_info->scrub_lock);
1705
1706         return 0;
1707 }
1708
1709 int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
1710 {
1711         struct btrfs_fs_info *fs_info = root->fs_info;
1712         struct scrub_dev *sdev;
1713
1714         mutex_lock(&fs_info->scrub_lock);
1715         sdev = dev->scrub_device;
1716         if (!sdev) {
1717                 mutex_unlock(&fs_info->scrub_lock);
1718                 return -ENOTCONN;
1719         }
1720         atomic_inc(&sdev->cancel_req);
1721         while (dev->scrub_device) {
1722                 mutex_unlock(&fs_info->scrub_lock);
1723                 wait_event(fs_info->scrub_pause_wait,
1724                            dev->scrub_device == NULL);
1725                 mutex_lock(&fs_info->scrub_lock);
1726         }
1727         mutex_unlock(&fs_info->scrub_lock);
1728
1729         return 0;
1730 }
1731 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
1732 {
1733         struct btrfs_fs_info *fs_info = root->fs_info;
1734         struct btrfs_device *dev;
1735         int ret;
1736
1737         /*
1738          * we have to hold the device_list_mutex here so the device
1739          * does not go away in cancel_dev. FIXME: find a better solution
1740          */
1741         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1742         dev = btrfs_find_device(root, devid, NULL, NULL);
1743         if (!dev) {
1744                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1745                 return -ENODEV;
1746         }
1747         ret = btrfs_scrub_cancel_dev(root, dev);
1748         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1749
1750         return ret;
1751 }
1752
1753 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
1754                          struct btrfs_scrub_progress *progress)
1755 {
1756         struct btrfs_device *dev;
1757         struct scrub_dev *sdev = NULL;
1758
1759         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1760         dev = btrfs_find_device(root, devid, NULL, NULL);
1761         if (dev)
1762                 sdev = dev->scrub_device;
1763         if (sdev)
1764                 memcpy(progress, &sdev->stat, sizeof(*progress));
1765         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1766
1767         return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
1768 }