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                         ipath->fspath->str[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                 return;
 659         }
 660
 661         if (bbio->num_stripes == 1)
 662                 /* there aren't any replicas */
 663                 goto uncorrectable;
 664
 665         /*
 666          * first find a good copy
 667          */
 668         for (i = 0; i < bbio->num_stripes; ++i) {
 669                 if (i + 1 == sbio->spag[ix].mirror_num)
 670                         continue;
 671
 672                 if (scrub_fixup_io(READ, bbio->stripes[i].dev->bdev,
 673                                    bbio->stripes[i].physical >> 9,
 674                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 675                         /* I/O-error, this is not a good copy */
 676                         continue;
 677                 }
 678
 679                 if (scrub_fixup_check(sbio, ix) == 0)
 680                         break;
 681         }
 682         if (i == bbio->num_stripes)
 683                 goto uncorrectable;
 684
 685         if (!sdev->readonly) {
 686                 /*
 687                  * bi_io_vec[ix].bv_page now contains good data, write it back
 688                  */
 689                 if (scrub_fixup_io(WRITE, sdev->dev->bdev,
 690                                    (sbio->physical + ix * PAGE_SIZE) >> 9,
 691                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 692                         /* I/O-error, writeback failed, give up */
 693                         goto uncorrectable;
 694                 }
 695         }
 696
 697         kfree(bbio);
 698         spin_lock(&sdev->stat_lock);
 699         ++sdev->stat.corrected_errors;
 700         spin_unlock(&sdev->stat_lock);
 701
 702         printk_ratelimited(KERN_ERR "btrfs: fixed up error at logical %llu\n",
 703                                (unsigned long long)logical);
 704         return;
 705
 706 uncorrectable:
 707         kfree(bbio);
 708         spin_lock(&sdev->stat_lock);
 709         ++sdev->stat.uncorrectable_errors;
 710         spin_unlock(&sdev->stat_lock);
 711
 712         printk_ratelimited(KERN_ERR "btrfs: unable to fixup (regular) error at "
 713                                 "logical %llu\n", (unsigned long long)logical);
 714 }
 715
 716 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
 717                          struct page *page)
 718 {
 719         struct bio *bio = NULL;
 720         int ret;
 721         DECLARE_COMPLETION_ONSTACK(complete);
 722
 723         bio = bio_alloc(GFP_NOFS, 1);
 724         bio->bi_bdev = bdev;
 725         bio->bi_sector = sector;
 726         bio_add_page(bio, page, PAGE_SIZE, 0);
 727         bio->bi_end_io = scrub_fixup_end_io;
 728         bio->bi_private = &complete;
 729         submit_bio(rw, bio);
 730
 731         /* this will also unplug the queue */
 732         wait_for_completion(&complete);
 733
 734         ret = !test_bit(BIO_UPTODATE, &bio->bi_flags);
 735         bio_put(bio);
 736         return ret;
 737 }
 738
 739 static void scrub_bio_end_io(struct bio *bio, int err)
 740 {
 741         struct scrub_bio *sbio = bio->bi_private;
 742         struct scrub_dev *sdev = sbio->sdev;
 743         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 744
 745         sbio->err = err;
 746         sbio->bio = bio;
 747
 748         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
 749 }
 750
 751 static void scrub_checksum(struct btrfs_work *work)
 752 {
 753         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
 754         struct scrub_dev *sdev = sbio->sdev;
 755         struct page *page;
 756         void *buffer;
 757         int i;
 758         u64 flags;
 759         u64 logical;
 760         int ret;
 761
 762         if (sbio->err) {
 763                 ret = 0;
 764                 for (i = 0; i < sbio->count; ++i)
 765                         ret |= scrub_recheck_error(sbio, i);
 766                 if (!ret) {
 767                         spin_lock(&sdev->stat_lock);
 768                         ++sdev->stat.unverified_errors;
 769                         spin_unlock(&sdev->stat_lock);
 770                 }
 771
 772                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
 773                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
 774                 sbio->bio->bi_phys_segments = 0;
 775                 sbio->bio->bi_idx = 0;
 776
 777                 for (i = 0; i < sbio->count; i++) {
 778                         struct bio_vec *bi;
 779                         bi = &sbio->bio->bi_io_vec[i];
 780                         bi->bv_offset = 0;
 781                         bi->bv_len = PAGE_SIZE;
 782                 }
 783                 goto out;
 784         }
 785         for (i = 0; i < sbio->count; ++i) {
 786                 page = sbio->bio->bi_io_vec[i].bv_page;
 787                 buffer = kmap_atomic(page, KM_USER0);
 788                 flags = sbio->spag[i].flags;
 789                 logical = sbio->logical + i * PAGE_SIZE;
 790                 ret = 0;
 791                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
 792                         ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
 793                 } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 794                         ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
 795                                                         logical, buffer);
 796                 } else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
 797                         BUG_ON(i);
 798                         (void)scrub_checksum_super(sbio, buffer);
 799                 } else {
 800                         WARN_ON(1);
 801                 }
 802                 kunmap_atomic(buffer, KM_USER0);
 803                 if (ret) {
 804                         ret = scrub_recheck_error(sbio, i);
 805                         if (!ret) {
 806                                 spin_lock(&sdev->stat_lock);
 807                                 ++sdev->stat.unverified_errors;
 808                                 spin_unlock(&sdev->stat_lock);
 809                         }
 810                 }
 811         }
 812
 813 out:
 814         scrub_free_bio(sbio->bio);
 815         sbio->bio = NULL;
 816         spin_lock(&sdev->list_lock);
 817         sbio->next_free = sdev->first_free;
 818         sdev->first_free = sbio->index;
 819         spin_unlock(&sdev->list_lock);
 820         atomic_dec(&sdev->in_flight);
 821         wake_up(&sdev->list_wait);
 822 }
 823
 824 static int scrub_checksum_data(struct scrub_dev *sdev,
 825                                struct scrub_page *spag, void *buffer)
 826 {
 827         u8 csum[BTRFS_CSUM_SIZE];
 828         u32 crc = ~(u32)0;
 829         int fail = 0;
 830         struct btrfs_root *root = sdev->dev->dev_root;
 831
 832         if (!spag->have_csum)
 833                 return 0;
 834
 835         crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
 836         btrfs_csum_final(crc, csum);
 837         if (memcmp(csum, spag->csum, sdev->csum_size))
 838                 fail = 1;
 839
 840         spin_lock(&sdev->stat_lock);
 841         ++sdev->stat.data_extents_scrubbed;
 842         sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
 843         if (fail)
 844                 ++sdev->stat.csum_errors;
 845         spin_unlock(&sdev->stat_lock);
 846
 847         return fail;
 848 }
 849
 850 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
 851                                      struct scrub_page *spag, u64 logical,
 852                                      void *buffer)
 853 {
 854         struct btrfs_header *h;
 855         struct btrfs_root *root = sdev->dev->dev_root;
 856         struct btrfs_fs_info *fs_info = root->fs_info;
 857         u8 csum[BTRFS_CSUM_SIZE];
 858         u32 crc = ~(u32)0;
 859         int fail = 0;
 860         int crc_fail = 0;
 861
 862         /*
 863          * we don't use the getter functions here, as we
 864          * a) don't have an extent buffer and
 865          * b) the page is already kmapped
 866          */
 867         h = (struct btrfs_header *)buffer;
 868
 869         if (logical != le64_to_cpu(h->bytenr))
 870                 ++fail;
 871
 872         if (spag->generation != le64_to_cpu(h->generation))
 873                 ++fail;
 874
 875         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 876                 ++fail;
 877
 878         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
 879                    BTRFS_UUID_SIZE))
 880                 ++fail;
 881
 882         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 883                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 884         btrfs_csum_final(crc, csum);
 885         if (memcmp(csum, h->csum, sdev->csum_size))
 886                 ++crc_fail;
 887
 888         spin_lock(&sdev->stat_lock);
 889         ++sdev->stat.tree_extents_scrubbed;
 890         sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
 891         if (crc_fail)
 892                 ++sdev->stat.csum_errors;
 893         if (fail)
 894                 ++sdev->stat.verify_errors;
 895         spin_unlock(&sdev->stat_lock);
 896
 897         return fail || crc_fail;
 898 }
 899
 900 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
 901 {
 902         struct btrfs_super_block *s;
 903         u64 logical;
 904         struct scrub_dev *sdev = sbio->sdev;
 905         struct btrfs_root *root = sdev->dev->dev_root;
 906         struct btrfs_fs_info *fs_info = root->fs_info;
 907         u8 csum[BTRFS_CSUM_SIZE];
 908         u32 crc = ~(u32)0;
 909         int fail = 0;
 910
 911         s = (struct btrfs_super_block *)buffer;
 912         logical = sbio->logical;
 913
 914         if (logical != le64_to_cpu(s->bytenr))
 915                 ++fail;
 916
 917         if (sbio->spag[0].generation != le64_to_cpu(s->generation))
 918                 ++fail;
 919
 920         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 921                 ++fail;
 922
 923         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 924                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 925         btrfs_csum_final(crc, csum);
 926         if (memcmp(csum, s->csum, sbio->sdev->csum_size))
 927                 ++fail;
 928
 929         if (fail) {
 930                 /*
 931                  * if we find an error in a super block, we just report it.
 932                  * They will get written with the next transaction commit
 933                  * anyway
 934                  */
 935                 spin_lock(&sdev->stat_lock);
 936                 ++sdev->stat.super_errors;
 937                 spin_unlock(&sdev->stat_lock);
 938         }
 939
 940         return fail;
 941 }
 942
 943 static int scrub_submit(struct scrub_dev *sdev)
 944 {
 945         struct scrub_bio *sbio;
 946         struct bio *bio;
 947         int i;
 948
 949         if (sdev->curr == -1)
 950                 return 0;
 951
 952         sbio = sdev->bios[sdev->curr];
 953
 954         bio = bio_alloc(GFP_NOFS, sbio->count);
 955         if (!bio)
 956                 goto nomem;
 957
 958         bio->bi_private = sbio;
 959         bio->bi_end_io = scrub_bio_end_io;
 960         bio->bi_bdev = sdev->dev->bdev;
 961         bio->bi_sector = sbio->physical >> 9;
 962
 963         for (i = 0; i < sbio->count; ++i) {
 964                 struct page *page;
 965                 int ret;
 966
 967                 page = alloc_page(GFP_NOFS);
 968                 if (!page)
 969                         goto nomem;
 970
 971                 ret = bio_add_page(bio, page, PAGE_SIZE, 0);
 972                 if (!ret) {
 973                         __free_page(page);
 974                         goto nomem;
 975                 }
 976         }
 977
 978         sbio->err = 0;
 979         sdev->curr = -1;
 980         atomic_inc(&sdev->in_flight);
 981
 982         submit_bio(READ, bio);
 983
 984         return 0;
 985
 986 nomem:
 987         scrub_free_bio(bio);
 988
 989         return -ENOMEM;
 990 }
 991
 992 static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
 993                       u64 physical, u64 flags, u64 gen, int mirror_num,
 994                       u8 *csum, int force)
 995 {
 996         struct scrub_bio *sbio;
 997
 998 again:
 999         /*
1000          * grab a fresh bio or wait for one to become available
1001          */
1002         while (sdev->curr == -1) {
1003                 spin_lock(&sdev->list_lock);
1004                 sdev->curr = sdev->first_free;
1005                 if (sdev->curr != -1) {
1006                         sdev->first_free = sdev->bios[sdev->curr]->next_free;
1007                         sdev->bios[sdev->curr]->next_free = -1;
1008                         sdev->bios[sdev->curr]->count = 0;
1009                         spin_unlock(&sdev->list_lock);
1010                 } else {
1011                         spin_unlock(&sdev->list_lock);
1012                         wait_event(sdev->list_wait, sdev->first_free != -1);
1013                 }
1014         }
1015         sbio = sdev->bios[sdev->curr];
1016         if (sbio->count == 0) {
1017                 sbio->physical = physical;
1018                 sbio->logical = logical;
1019         } else if (sbio->physical + sbio->count * PAGE_SIZE != physical ||
1020                    sbio->logical + sbio->count * PAGE_SIZE != logical) {
1021                 int ret;
1022
1023                 ret = scrub_submit(sdev);
1024                 if (ret)
1025                         return ret;
1026                 goto again;
1027         }
1028         sbio->spag[sbio->count].flags = flags;
1029         sbio->spag[sbio->count].generation = gen;
1030         sbio->spag[sbio->count].have_csum = 0;
1031         sbio->spag[sbio->count].mirror_num = mirror_num;
1032         if (csum) {
1033                 sbio->spag[sbio->count].have_csum = 1;
1034                 memcpy(sbio->spag[sbio->count].csum, csum, sdev->csum_size);
1035         }
1036         ++sbio->count;
1037         if (sbio->count == SCRUB_PAGES_PER_BIO || force) {
1038                 int ret;
1039
1040                 ret = scrub_submit(sdev);
1041                 if (ret)
1042                         return ret;
1043         }
1044
1045         return 0;
1046 }
1047
1048 static int scrub_find_csum(struct scrub_dev *sdev, u64 logical, u64 len,
1049                            u8 *csum)
1050 {
1051         struct btrfs_ordered_sum *sum = NULL;
1052         int ret = 0;
1053         unsigned long i;
1054         unsigned long num_sectors;
1055         u32 sectorsize = sdev->dev->dev_root->sectorsize;
1056
1057         while (!list_empty(&sdev->csum_list)) {
1058                 sum = list_first_entry(&sdev->csum_list,
1059                                        struct btrfs_ordered_sum, list);
1060                 if (sum->bytenr > logical)
1061                         return 0;
1062                 if (sum->bytenr + sum->len > logical)
1063                         break;
1064
1065                 ++sdev->stat.csum_discards;
1066                 list_del(&sum->list);
1067                 kfree(sum);
1068                 sum = NULL;
1069         }
1070         if (!sum)
1071                 return 0;
1072
1073         num_sectors = sum->len / sectorsize;
1074         for (i = 0; i < num_sectors; ++i) {
1075                 if (sum->sums[i].bytenr == logical) {
1076                         memcpy(csum, &sum->sums[i].sum, sdev->csum_size);
1077                         ret = 1;
1078                         break;
1079                 }
1080         }
1081         if (ret && i == num_sectors - 1) {
1082                 list_del(&sum->list);
1083                 kfree(sum);
1084         }
1085         return ret;
1086 }
1087
1088 /* scrub extent tries to collect up to 64 kB for each bio */
1089 static int scrub_extent(struct scrub_dev *sdev, u64 logical, u64 len,
1090                         u64 physical, u64 flags, u64 gen, int mirror_num)
1091 {
1092         int ret;
1093         u8 csum[BTRFS_CSUM_SIZE];
1094
1095         while (len) {
1096                 u64 l = min_t(u64, len, PAGE_SIZE);
1097                 int have_csum = 0;
1098
1099                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
1100                         /* push csums to sbio */
1101                         have_csum = scrub_find_csum(sdev, logical, l, csum);
1102                         if (have_csum == 0)
1103                                 ++sdev->stat.no_csum;
1104                 }
1105                 ret = scrub_page(sdev, logical, l, physical, flags, gen,
1106                                  mirror_num, have_csum ? csum : NULL, 0);
1107                 if (ret)
1108                         return ret;
1109                 len -= l;
1110                 logical += l;
1111                 physical += l;
1112         }
1113         return 0;
1114 }
1115
1116 static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
1117         struct map_lookup *map, int num, u64 base, u64 length)
1118 {
1119         struct btrfs_path *path;
1120         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
1121         struct btrfs_root *root = fs_info->extent_root;
1122         struct btrfs_root *csum_root = fs_info->csum_root;
1123         struct btrfs_extent_item *extent;
1124         struct blk_plug plug;
1125         u64 flags;
1126         int ret;
1127         int slot;
1128         int i;
1129         u64 nstripes;
1130         struct extent_buffer *l;
1131         struct btrfs_key key;
1132         u64 physical;
1133         u64 logical;
1134         u64 generation;
1135         int mirror_num;
1136         struct reada_control *reada1;
1137         struct reada_control *reada2;
1138         struct btrfs_key key_start;
1139         struct btrfs_key key_end;
1140
1141         u64 increment = map->stripe_len;
1142         u64 offset;
1143
1144         nstripes = length;
1145         offset = 0;
1146         do_div(nstripes, map->stripe_len);
1147         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
1148                 offset = map->stripe_len * num;
1149                 increment = map->stripe_len * map->num_stripes;
1150                 mirror_num = 1;
1151         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1152                 int factor = map->num_stripes / map->sub_stripes;
1153                 offset = map->stripe_len * (num / map->sub_stripes);
1154                 increment = map->stripe_len * factor;
1155                 mirror_num = num % map->sub_stripes + 1;
1156         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
1157                 increment = map->stripe_len;
1158                 mirror_num = num % map->num_stripes + 1;
1159         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
1160                 increment = map->stripe_len;
1161                 mirror_num = num % map->num_stripes + 1;
1162         } else {
1163                 increment = map->stripe_len;
1164                 mirror_num = 1;
1165         }
1166
1167         path = btrfs_alloc_path();
1168         if (!path)
1169                 return -ENOMEM;
1170
1171         path->search_commit_root = 1;
1172         path->skip_locking = 1;
1173
1174         /*
1175          * trigger the readahead for extent tree csum tree and wait for
1176          * completion. During readahead, the scrub is officially paused
1177          * to not hold off transaction commits
1178          */
1179         logical = base + offset;
1180
1181         wait_event(sdev->list_wait,
1182                    atomic_read(&sdev->in_flight) == 0);
1183         atomic_inc(&fs_info->scrubs_paused);
1184         wake_up(&fs_info->scrub_pause_wait);
1185
1186         /* FIXME it might be better to start readahead at commit root */
1187         key_start.objectid = logical;
1188         key_start.type = BTRFS_EXTENT_ITEM_KEY;
1189         key_start.offset = (u64)0;
1190         key_end.objectid = base + offset + nstripes * increment;
1191         key_end.type = BTRFS_EXTENT_ITEM_KEY;
1192         key_end.offset = (u64)0;
1193         reada1 = btrfs_reada_add(root, &key_start, &key_end);
1194
1195         key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1196         key_start.type = BTRFS_EXTENT_CSUM_KEY;
1197         key_start.offset = logical;
1198         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1199         key_end.type = BTRFS_EXTENT_CSUM_KEY;
1200         key_end.offset = base + offset + nstripes * increment;
1201         reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);
1202
1203         if (!IS_ERR(reada1))
1204                 btrfs_reada_wait(reada1);
1205         if (!IS_ERR(reada2))
1206                 btrfs_reada_wait(reada2);
1207
1208         mutex_lock(&fs_info->scrub_lock);
1209         while (atomic_read(&fs_info->scrub_pause_req)) {
1210                 mutex_unlock(&fs_info->scrub_lock);
1211                 wait_event(fs_info->scrub_pause_wait,
1212                    atomic_read(&fs_info->scrub_pause_req) == 0);
1213                 mutex_lock(&fs_info->scrub_lock);
1214         }
1215         atomic_dec(&fs_info->scrubs_paused);
1216         mutex_unlock(&fs_info->scrub_lock);
1217         wake_up(&fs_info->scrub_pause_wait);
1218
1219         /*
1220          * collect all data csums for the stripe to avoid seeking during
1221          * the scrub. This might currently (crc32) end up to be about 1MB
1222          */
1223         blk_start_plug(&plug);
1224
1225         /*
1226          * now find all extents for each stripe and scrub them
1227          */
1228         logical = base + offset;
1229         physical = map->stripes[num].physical;
1230         ret = 0;
1231         for (i = 0; i < nstripes; ++i) {
1232                 /*
1233                  * canceled?
1234                  */
1235                 if (atomic_read(&fs_info->scrub_cancel_req) ||
1236                     atomic_read(&sdev->cancel_req)) {
1237                         ret = -ECANCELED;
1238                         goto out;
1239                 }
1240                 /*
1241                  * check to see if we have to pause
1242                  */
1243                 if (atomic_read(&fs_info->scrub_pause_req)) {
1244                         /* push queued extents */
1245                         scrub_submit(sdev);
1246                         wait_event(sdev->list_wait,
1247                                    atomic_read(&sdev->in_flight) == 0);
1248                         atomic_inc(&fs_info->scrubs_paused);
1249                         wake_up(&fs_info->scrub_pause_wait);
1250                         mutex_lock(&fs_info->scrub_lock);
1251                         while (atomic_read(&fs_info->scrub_pause_req)) {
1252                                 mutex_unlock(&fs_info->scrub_lock);
1253                                 wait_event(fs_info->scrub_pause_wait,
1254                                    atomic_read(&fs_info->scrub_pause_req) == 0);
1255                                 mutex_lock(&fs_info->scrub_lock);
1256                         }
1257                         atomic_dec(&fs_info->scrubs_paused);
1258                         mutex_unlock(&fs_info->scrub_lock);
1259                         wake_up(&fs_info->scrub_pause_wait);
1260                 }
1261
1262                 ret = btrfs_lookup_csums_range(csum_root, logical,
1263                                                logical + map->stripe_len - 1,
1264                                                &sdev->csum_list, 1);
1265                 if (ret)
1266                         goto out;
1267
1268                 key.objectid = logical;
1269                 key.type = BTRFS_EXTENT_ITEM_KEY;
1270                 key.offset = (u64)0;
1271
1272                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1273                 if (ret < 0)
1274                         goto out;
1275                 if (ret > 0) {
1276                         ret = btrfs_previous_item(root, path, 0,
1277                                                   BTRFS_EXTENT_ITEM_KEY);
1278                         if (ret < 0)
1279                                 goto out;
1280                         if (ret > 0) {
1281                                 /* there's no smaller item, so stick with the
1282                                  * larger one */
1283                                 btrfs_release_path(path);
1284                                 ret = btrfs_search_slot(NULL, root, &key,
1285                                                         path, 0, 0);
1286                                 if (ret < 0)
1287                                         goto out;
1288                         }
1289                 }
1290
1291                 while (1) {
1292                         l = path->nodes[0];
1293                         slot = path->slots[0];
1294                         if (slot >= btrfs_header_nritems(l)) {
1295                                 ret = btrfs_next_leaf(root, path);
1296                                 if (ret == 0)
1297                                         continue;
1298                                 if (ret < 0)
1299                                         goto out;
1300
1301                                 break;
1302                         }
1303                         btrfs_item_key_to_cpu(l, &key, slot);
1304
1305                         if (key.objectid + key.offset <= logical)
1306                                 goto next;
1307
1308                         if (key.objectid >= logical + map->stripe_len)
1309                                 break;
1310
1311                         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
1312                                 goto next;
1313
1314                         extent = btrfs_item_ptr(l, slot,
1315                                                 struct btrfs_extent_item);
1316                         flags = btrfs_extent_flags(l, extent);
1317                         generation = btrfs_extent_generation(l, extent);
1318
1319                         if (key.objectid < logical &&
1320                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
1321                                 printk(KERN_ERR
1322                                        "btrfs scrub: tree block %llu spanning "
1323                                        "stripes, ignored. logical=%llu\n",
1324                                        (unsigned long long)key.objectid,
1325                                        (unsigned long long)logical);
1326                                 goto next;
1327                         }
1328
1329                         /*
1330                          * trim extent to this stripe
1331                          */
1332                         if (key.objectid < logical) {
1333                                 key.offset -= logical - key.objectid;
1334                                 key.objectid = logical;
1335                         }
1336                         if (key.objectid + key.offset >
1337                             logical + map->stripe_len) {
1338                                 key.offset = logical + map->stripe_len -
1339                                              key.objectid;
1340                         }
1341
1342                         ret = scrub_extent(sdev, key.objectid, key.offset,
1343                                            key.objectid - logical + physical,
1344                                            flags, generation, mirror_num);
1345                         if (ret)
1346                                 goto out;
1347
1348 next:
1349                         path->slots[0]++;
1350                 }
1351                 btrfs_release_path(path);
1352                 logical += increment;
1353                 physical += map->stripe_len;
1354                 spin_lock(&sdev->stat_lock);
1355                 sdev->stat.last_physical = physical;
1356                 spin_unlock(&sdev->stat_lock);
1357         }
1358         /* push queued extents */
1359         scrub_submit(sdev);
1360
1361 out:
1362         blk_finish_plug(&plug);
1363         btrfs_free_path(path);
1364         return ret < 0 ? ret : 0;
1365 }
1366
1367 static noinline_for_stack int scrub_chunk(struct scrub_dev *sdev,
1368         u64 chunk_tree, u64 chunk_objectid, u64 chunk_offset, u64 length)
1369 {
1370         struct btrfs_mapping_tree *map_tree =
1371                 &sdev->dev->dev_root->fs_info->mapping_tree;
1372         struct map_lookup *map;
1373         struct extent_map *em;
1374         int i;
1375         int ret = -EINVAL;
1376
1377         read_lock(&map_tree->map_tree.lock);
1378         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
1379         read_unlock(&map_tree->map_tree.lock);
1380
1381         if (!em)
1382                 return -EINVAL;
1383
1384         map = (struct map_lookup *)em->bdev;
1385         if (em->start != chunk_offset)
1386                 goto out;
1387
1388         if (em->len < length)
1389                 goto out;
1390
1391         for (i = 0; i < map->num_stripes; ++i) {
1392                 if (map->stripes[i].dev == sdev->dev) {
1393                         ret = scrub_stripe(sdev, map, i, chunk_offset, length);
1394                         if (ret)
1395                                 goto out;
1396                 }
1397         }
1398 out:
1399         free_extent_map(em);
1400
1401         return ret;
1402 }
1403
1404 static noinline_for_stack
1405 int scrub_enumerate_chunks(struct scrub_dev *sdev, u64 start, u64 end)
1406 {
1407         struct btrfs_dev_extent *dev_extent = NULL;
1408         struct btrfs_path *path;
1409         struct btrfs_root *root = sdev->dev->dev_root;
1410         struct btrfs_fs_info *fs_info = root->fs_info;
1411         u64 length;
1412         u64 chunk_tree;
1413         u64 chunk_objectid;
1414         u64 chunk_offset;
1415         int ret;
1416         int slot;
1417         struct extent_buffer *l;
1418         struct btrfs_key key;
1419         struct btrfs_key found_key;
1420         struct btrfs_block_group_cache *cache;
1421
1422         path = btrfs_alloc_path();
1423         if (!path)
1424                 return -ENOMEM;
1425
1426         path->reada = 2;
1427         path->search_commit_root = 1;
1428         path->skip_locking = 1;
1429
1430         key.objectid = sdev->dev->devid;
1431         key.offset = 0ull;
1432         key.type = BTRFS_DEV_EXTENT_KEY;
1433
1434
1435         while (1) {
1436                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1437                 if (ret < 0)
1438                         break;
1439                 if (ret > 0) {
1440                         if (path->slots[0] >=
1441                             btrfs_header_nritems(path->nodes[0])) {
1442                                 ret = btrfs_next_leaf(root, path);
1443                                 if (ret)
1444                                         break;
1445                         }
1446                 }
1447
1448                 l = path->nodes[0];
1449                 slot = path->slots[0];
1450
1451                 btrfs_item_key_to_cpu(l, &found_key, slot);
1452
1453                 if (found_key.objectid != sdev->dev->devid)
1454                         break;
1455
1456                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
1457                         break;
1458
1459                 if (found_key.offset >= end)
1460                         break;
1461
1462                 if (found_key.offset < key.offset)
1463                         break;
1464
1465                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
1466                 length = btrfs_dev_extent_length(l, dev_extent);
1467
1468                 if (found_key.offset + length <= start) {
1469                         key.offset = found_key.offset + length;
1470                         btrfs_release_path(path);
1471                         continue;
1472                 }
1473
1474                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
1475                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
1476                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
1477
1478                 /*
1479                  * get a reference on the corresponding block group to prevent
1480                  * the chunk from going away while we scrub it
1481                  */
1482                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
1483                 if (!cache) {
1484                         ret = -ENOENT;
1485                         break;
1486                 }
1487                 ret = scrub_chunk(sdev, chunk_tree, chunk_objectid,
1488                                   chunk_offset, length);
1489                 btrfs_put_block_group(cache);
1490                 if (ret)
1491                         break;
1492
1493                 key.offset = found_key.offset + length;
1494                 btrfs_release_path(path);
1495         }
1496
1497         btrfs_free_path(path);
1498
1499         /*
1500          * ret can still be 1 from search_slot or next_leaf,
1501          * that's not an error
1502          */
1503         return ret < 0 ? ret : 0;
1504 }
1505
1506 static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
1507 {
1508         int     i;
1509         u64     bytenr;
1510         u64     gen;
1511         int     ret;
1512         struct btrfs_device *device = sdev->dev;
1513         struct btrfs_root *root = device->dev_root;
1514
1515         gen = root->fs_info->last_trans_committed;
1516
1517         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
1518                 bytenr = btrfs_sb_offset(i);
1519                 if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
1520                         break;
1521
1522                 ret = scrub_page(sdev, bytenr, PAGE_SIZE, bytenr,
1523                                  BTRFS_EXTENT_FLAG_SUPER, gen, i, NULL, 1);
1524                 if (ret)
1525                         return ret;
1526         }
1527         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1528
1529         return 0;
1530 }
1531
1532 /*
1533  * get a reference count on fs_info->scrub_workers. start worker if necessary
1534  */
1535 static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
1536 {
1537         struct btrfs_fs_info *fs_info = root->fs_info;
1538
1539         mutex_lock(&fs_info->scrub_lock);
1540         if (fs_info->scrub_workers_refcnt == 0) {
1541                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
1542                            fs_info->thread_pool_size, &fs_info->generic_worker);
1543                 fs_info->scrub_workers.idle_thresh = 4;
1544                 btrfs_start_workers(&fs_info->scrub_workers, 1);
1545         }
1546         ++fs_info->scrub_workers_refcnt;
1547         mutex_unlock(&fs_info->scrub_lock);
1548
1549         return 0;
1550 }
1551
1552 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
1553 {
1554         struct btrfs_fs_info *fs_info = root->fs_info;
1555
1556         mutex_lock(&fs_info->scrub_lock);
1557         if (--fs_info->scrub_workers_refcnt == 0)
1558                 btrfs_stop_workers(&fs_info->scrub_workers);
1559         WARN_ON(fs_info->scrub_workers_refcnt < 0);
1560         mutex_unlock(&fs_info->scrub_lock);
1561 }
1562
1563
1564 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
1565                     struct btrfs_scrub_progress *progress, int readonly)
1566 {
1567         struct scrub_dev *sdev;
1568         struct btrfs_fs_info *fs_info = root->fs_info;
1569         int ret;
1570         struct btrfs_device *dev;
1571
1572         if (btrfs_fs_closing(root->fs_info))
1573                 return -EINVAL;
1574
1575         /*
1576          * check some assumptions
1577          */
1578         if (root->sectorsize != PAGE_SIZE ||
1579             root->sectorsize != root->leafsize ||
1580             root->sectorsize != root->nodesize) {
1581                 printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
1582                 return -EINVAL;
1583         }
1584
1585         ret = scrub_workers_get(root);
1586         if (ret)
1587                 return ret;
1588
1589         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1590         dev = btrfs_find_device(root, devid, NULL, NULL);
1591         if (!dev || dev->missing) {
1592                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1593                 scrub_workers_put(root);
1594                 return -ENODEV;
1595         }
1596         mutex_lock(&fs_info->scrub_lock);
1597
1598         if (!dev->in_fs_metadata) {
1599                 mutex_unlock(&fs_info->scrub_lock);
1600                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1601                 scrub_workers_put(root);
1602                 return -ENODEV;
1603         }
1604
1605         if (dev->scrub_device) {
1606                 mutex_unlock(&fs_info->scrub_lock);
1607                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1608                 scrub_workers_put(root);
1609                 return -EINPROGRESS;
1610         }
1611         sdev = scrub_setup_dev(dev);
1612         if (IS_ERR(sdev)) {
1613                 mutex_unlock(&fs_info->scrub_lock);
1614                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1615                 scrub_workers_put(root);
1616                 return PTR_ERR(sdev);
1617         }
1618         sdev->readonly = readonly;
1619         dev->scrub_device = sdev;
1620
1621         atomic_inc(&fs_info->scrubs_running);
1622         mutex_unlock(&fs_info->scrub_lock);
1623         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1624
1625         down_read(&fs_info->scrub_super_lock);
1626         ret = scrub_supers(sdev);
1627         up_read(&fs_info->scrub_super_lock);
1628
1629         if (!ret)
1630                 ret = scrub_enumerate_chunks(sdev, start, end);
1631
1632         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1633         atomic_dec(&fs_info->scrubs_running);
1634         wake_up(&fs_info->scrub_pause_wait);
1635
1636         wait_event(sdev->list_wait, atomic_read(&sdev->fixup_cnt) == 0);
1637
1638         if (progress)
1639                 memcpy(progress, &sdev->stat, sizeof(*progress));
1640
1641         mutex_lock(&fs_info->scrub_lock);
1642         dev->scrub_device = NULL;
1643         mutex_unlock(&fs_info->scrub_lock);
1644
1645         scrub_free_dev(sdev);
1646         scrub_workers_put(root);
1647
1648         return ret;
1649 }
1650
1651 int btrfs_scrub_pause(struct btrfs_root *root)
1652 {
1653         struct btrfs_fs_info *fs_info = root->fs_info;
1654
1655         mutex_lock(&fs_info->scrub_lock);
1656         atomic_inc(&fs_info->scrub_pause_req);
1657         while (atomic_read(&fs_info->scrubs_paused) !=
1658                atomic_read(&fs_info->scrubs_running)) {
1659                 mutex_unlock(&fs_info->scrub_lock);
1660                 wait_event(fs_info->scrub_pause_wait,
1661                            atomic_read(&fs_info->scrubs_paused) ==
1662                            atomic_read(&fs_info->scrubs_running));
1663                 mutex_lock(&fs_info->scrub_lock);
1664         }
1665         mutex_unlock(&fs_info->scrub_lock);
1666
1667         return 0;
1668 }
1669
1670 int btrfs_scrub_continue(struct btrfs_root *root)
1671 {
1672         struct btrfs_fs_info *fs_info = root->fs_info;
1673
1674         atomic_dec(&fs_info->scrub_pause_req);
1675         wake_up(&fs_info->scrub_pause_wait);
1676         return 0;
1677 }
1678
1679 int btrfs_scrub_pause_super(struct btrfs_root *root)
1680 {
1681         down_write(&root->fs_info->scrub_super_lock);
1682         return 0;
1683 }
1684
1685 int btrfs_scrub_continue_super(struct btrfs_root *root)
1686 {
1687         up_write(&root->fs_info->scrub_super_lock);
1688         return 0;
1689 }
1690
1691 int btrfs_scrub_cancel(struct btrfs_root *root)
1692 {
1693         struct btrfs_fs_info *fs_info = root->fs_info;
1694
1695         mutex_lock(&fs_info->scrub_lock);
1696         if (!atomic_read(&fs_info->scrubs_running)) {
1697                 mutex_unlock(&fs_info->scrub_lock);
1698                 return -ENOTCONN;
1699         }
1700
1701         atomic_inc(&fs_info->scrub_cancel_req);
1702         while (atomic_read(&fs_info->scrubs_running)) {
1703                 mutex_unlock(&fs_info->scrub_lock);
1704                 wait_event(fs_info->scrub_pause_wait,
1705                            atomic_read(&fs_info->scrubs_running) == 0);
1706                 mutex_lock(&fs_info->scrub_lock);
1707         }
1708         atomic_dec(&fs_info->scrub_cancel_req);
1709         mutex_unlock(&fs_info->scrub_lock);
1710
1711         return 0;
1712 }
1713
1714 int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
1715 {
1716         struct btrfs_fs_info *fs_info = root->fs_info;
1717         struct scrub_dev *sdev;
1718
1719         mutex_lock(&fs_info->scrub_lock);
1720         sdev = dev->scrub_device;
1721         if (!sdev) {
1722                 mutex_unlock(&fs_info->scrub_lock);
1723                 return -ENOTCONN;
1724         }
1725         atomic_inc(&sdev->cancel_req);
1726         while (dev->scrub_device) {
1727                 mutex_unlock(&fs_info->scrub_lock);
1728                 wait_event(fs_info->scrub_pause_wait,
1729                            dev->scrub_device == NULL);
1730                 mutex_lock(&fs_info->scrub_lock);
1731         }
1732         mutex_unlock(&fs_info->scrub_lock);
1733
1734         return 0;
1735 }
1736 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
1737 {
1738         struct btrfs_fs_info *fs_info = root->fs_info;
1739         struct btrfs_device *dev;
1740         int ret;
1741
1742         /*
1743          * we have to hold the device_list_mutex here so the device
1744          * does not go away in cancel_dev. FIXME: find a better solution
1745          */
1746         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1747         dev = btrfs_find_device(root, devid, NULL, NULL);
1748         if (!dev) {
1749                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1750                 return -ENODEV;
1751         }
1752         ret = btrfs_scrub_cancel_dev(root, dev);
1753         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1754
1755         return ret;
1756 }
1757
1758 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
1759                          struct btrfs_scrub_progress *progress)
1760 {
1761         struct btrfs_device *dev;
1762         struct scrub_dev *sdev = NULL;
1763
1764         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1765         dev = btrfs_find_device(root, devid, NULL, NULL);
1766         if (dev)
1767                 sdev = dev->scrub_device;
1768         if (sdev)
1769                 memcpy(progress, &sdev->stat, sizeof(*progress));
1770         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1771
1772         return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
1773 }