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         if (IS_ERR(ipath)) {
 260                 ret = PTR_ERR(ipath);
 261                 ipath = NULL;
 262                 goto err;
 263         }
 264         ret = paths_from_inode(inum, ipath);
 265
 266         if (ret < 0)
 267                 goto err;
 268
 269         /*
 270          * we deliberately ignore the bit ipath might have been too small to
 271          * hold all of the paths here
 272          */
 273         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 274                 printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
 275                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
 276                         "length %llu, links %u (path: %s)\n", swarn->errstr,
 277                         swarn->logical, swarn->dev->name,
 278                         (unsigned long long)swarn->sector, root, inum, offset,
 279                         min(isize - offset, (u64)PAGE_SIZE), nlink,
 280                         (char *)(unsigned long)ipath->fspath->val[i]);
 281
 282         free_ipath(ipath);
 283         return 0;
 284
 285 err:
 286         printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
 287                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
 288                 "resolving failed with ret=%d\n", swarn->errstr,
 289                 swarn->logical, swarn->dev->name,
 290                 (unsigned long long)swarn->sector, root, inum, offset, ret);
 291
 292         free_ipath(ipath);
 293         return 0;
 294 }
 295
 296 static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
 297                                 int ix)
 298 {
 299         struct btrfs_device *dev = sbio->sdev->dev;
 300         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 301         struct btrfs_path *path;
 302         struct btrfs_key found_key;
 303         struct extent_buffer *eb;
 304         struct btrfs_extent_item *ei;
 305         struct scrub_warning swarn;
 306         u32 item_size;
 307         int ret;
 308         u64 ref_root;
 309         u8 ref_level;
 310         unsigned long ptr = 0;
 311         const int bufsize = 4096;
 312         u64 extent_offset;
 313
 314         path = btrfs_alloc_path();
 315
 316         swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
 317         swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
 318         swarn.sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 319         swarn.logical = sbio->logical + ix * PAGE_SIZE;
 320         swarn.errstr = errstr;
 321         swarn.dev = dev;
 322         swarn.msg_bufsize = bufsize;
 323         swarn.scratch_bufsize = bufsize;
 324
 325         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
 326                 goto out;
 327
 328         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key);
 329         if (ret < 0)
 330                 goto out;
 331
 332         extent_offset = swarn.logical - found_key.objectid;
 333         swarn.extent_item_size = found_key.offset;
 334
 335         eb = path->nodes[0];
 336         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 337         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 338
 339         if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 340                 do {
 341                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
 342                                                         &ref_root, &ref_level);
 343                         printk(KERN_WARNING "%s at logical %llu on dev %s, "
 344                                 "sector %llu: metadata %s (level %d) in tree "
 345                                 "%llu\n", errstr, swarn.logical, dev->name,
 346                                 (unsigned long long)swarn.sector,
 347                                 ref_level ? "node" : "leaf",
 348                                 ret < 0 ? -1 : ref_level,
 349                                 ret < 0 ? -1 : ref_root);
 350                 } while (ret != 1);
 351         } else {
 352                 swarn.path = path;
 353                 iterate_extent_inodes(fs_info, path, found_key.objectid,
 354                                         extent_offset,
 355                                         scrub_print_warning_inode, &swarn);
 356         }
 357
 358 out:
 359         btrfs_free_path(path);
 360         kfree(swarn.scratch_buf);
 361         kfree(swarn.msg_buf);
 362 }
 363
 364 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *ctx)
 365 {
 366         struct page *page = NULL;
 367         unsigned long index;
 368         struct scrub_fixup_nodatasum *fixup = ctx;
 369         int ret;
 370         int corrected = 0;
 371         struct btrfs_key key;
 372         struct inode *inode = NULL;
 373         u64 end = offset + PAGE_SIZE - 1;
 374         struct btrfs_root *local_root;
 375
 376         key.objectid = root;
 377         key.type = BTRFS_ROOT_ITEM_KEY;
 378         key.offset = (u64)-1;
 379         local_root = btrfs_read_fs_root_no_name(fixup->root->fs_info, &key);
 380         if (IS_ERR(local_root))
 381                 return PTR_ERR(local_root);
 382
 383         key.type = BTRFS_INODE_ITEM_KEY;
 384         key.objectid = inum;
 385         key.offset = 0;
 386         inode = btrfs_iget(fixup->root->fs_info->sb, &key, local_root, NULL);
 387         if (IS_ERR(inode))
 388                 return PTR_ERR(inode);
 389
 390         index = offset >> PAGE_CACHE_SHIFT;
 391
 392         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 393         if (!page) {
 394                 ret = -ENOMEM;
 395                 goto out;
 396         }
 397
 398         if (PageUptodate(page)) {
 399                 struct btrfs_mapping_tree *map_tree;
 400                 if (PageDirty(page)) {
 401                         /*
 402                          * we need to write the data to the defect sector. the
 403                          * data that was in that sector is not in memory,
 404                          * because the page was modified. we must not write the
 405                          * modified page to that sector.
 406                          *
 407                          * TODO: what could be done here: wait for the delalloc
 408                          *       runner to write out that page (might involve
 409                          *       COW) and see whether the sector is still
 410                          *       referenced afterwards.
 411                          *
 412                          * For the meantime, we'll treat this error
 413                          * incorrectable, although there is a chance that a
 414                          * later scrub will find the bad sector again and that
 415                          * there's no dirty page in memory, then.
 416                          */
 417                         ret = -EIO;
 418                         goto out;
 419                 }
 420                 map_tree = &BTRFS_I(inode)->root->fs_info->mapping_tree;
 421                 ret = repair_io_failure(map_tree, offset, PAGE_SIZE,
 422                                         fixup->logical, page,
 423                                         fixup->mirror_num);
 424                 unlock_page(page);
 425                 corrected = !ret;
 426         } else {
 427                 /*
 428                  * we need to get good data first. the general readpage path
 429                  * will call repair_io_failure for us, we just have to make
 430                  * sure we read the bad mirror.
 431                  */
 432                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 433                                         EXTENT_DAMAGED, GFP_NOFS);
 434                 if (ret) {
 435                         /* set_extent_bits should give proper error */
 436                         WARN_ON(ret > 0);
 437                         if (ret > 0)
 438                                 ret = -EFAULT;
 439                         goto out;
 440                 }
 441
 442                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 443                                                 btrfs_get_extent,
 444                                                 fixup->mirror_num);
 445                 wait_on_page_locked(page);
 446
 447                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 448                                                 end, EXTENT_DAMAGED, 0, NULL);
 449                 if (!corrected)
 450                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 451                                                 EXTENT_DAMAGED, GFP_NOFS);
 452         }
 453
 454 out:
 455         if (page)
 456                 put_page(page);
 457         if (inode)
 458                 iput(inode);
 459
 460         if (ret < 0)
 461                 return ret;
 462
 463         if (ret == 0 && corrected) {
 464                 /*
 465                  * we only need to call readpage for one of the inodes belonging
 466                  * to this extent. so make iterate_extent_inodes stop
 467                  */
 468                 return 1;
 469         }
 470
 471         return -EIO;
 472 }
 473
 474 static void scrub_fixup_nodatasum(struct btrfs_work *work)
 475 {
 476         int ret;
 477         struct scrub_fixup_nodatasum *fixup;
 478         struct scrub_dev *sdev;
 479         struct btrfs_trans_handle *trans = NULL;
 480         struct btrfs_fs_info *fs_info;
 481         struct btrfs_path *path;
 482         int uncorrectable = 0;
 483
 484         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
 485         sdev = fixup->sdev;
 486         fs_info = fixup->root->fs_info;
 487
 488         path = btrfs_alloc_path();
 489         if (!path) {
 490                 spin_lock(&sdev->stat_lock);
 491                 ++sdev->stat.malloc_errors;
 492                 spin_unlock(&sdev->stat_lock);
 493                 uncorrectable = 1;
 494                 goto out;
 495         }
 496
 497         trans = btrfs_join_transaction(fixup->root);
 498         if (IS_ERR(trans)) {
 499                 uncorrectable = 1;
 500                 goto out;
 501         }
 502
 503         /*
 504          * the idea is to trigger a regular read through the standard path. we
 505          * read a page from the (failed) logical address by specifying the
 506          * corresponding copynum of the failed sector. thus, that readpage is
 507          * expected to fail.
 508          * that is the point where on-the-fly error correction will kick in
 509          * (once it's finished) and rewrite the failed sector if a good copy
 510          * can be found.
 511          */
 512         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
 513                                                 path, scrub_fixup_readpage,
 514                                                 fixup);
 515         if (ret < 0) {
 516                 uncorrectable = 1;
 517                 goto out;
 518         }
 519         WARN_ON(ret != 1);
 520
 521         spin_lock(&sdev->stat_lock);
 522         ++sdev->stat.corrected_errors;
 523         spin_unlock(&sdev->stat_lock);
 524
 525 out:
 526         if (trans && !IS_ERR(trans))
 527                 btrfs_end_transaction(trans, fixup->root);
 528         if (uncorrectable) {
 529                 spin_lock(&sdev->stat_lock);
 530                 ++sdev->stat.uncorrectable_errors;
 531                 spin_unlock(&sdev->stat_lock);
 532                 printk_ratelimited(KERN_ERR "btrfs: unable to fixup "
 533                                         "(nodatasum) error at logical %llu\n",
 534                                         fixup->logical);
 535         }
 536
 537         btrfs_free_path(path);
 538         kfree(fixup);
 539
 540         /* see caller why we're pretending to be paused in the scrub counters */
 541         mutex_lock(&fs_info->scrub_lock);
 542         atomic_dec(&fs_info->scrubs_running);
 543         atomic_dec(&fs_info->scrubs_paused);
 544         mutex_unlock(&fs_info->scrub_lock);
 545         atomic_dec(&sdev->fixup_cnt);
 546         wake_up(&fs_info->scrub_pause_wait);
 547         wake_up(&sdev->list_wait);
 548 }
 549
 550 /*
 551  * scrub_recheck_error gets called when either verification of the page
 552  * failed or the bio failed to read, e.g. with EIO. In the latter case,
 553  * recheck_error gets called for every page in the bio, even though only
 554  * one may be bad
 555  */
 556 static int scrub_recheck_error(struct scrub_bio *sbio, int ix)
 557 {
 558         struct scrub_dev *sdev = sbio->sdev;
 559         u64 sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 560         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 561                                         DEFAULT_RATELIMIT_BURST);
 562
 563         if (sbio->err) {
 564                 if (scrub_fixup_io(READ, sbio->sdev->dev->bdev, sector,
 565                                    sbio->bio->bi_io_vec[ix].bv_page) == 0) {
 566                         if (scrub_fixup_check(sbio, ix) == 0)
 567                                 return 0;
 568                 }
 569                 if (__ratelimit(&_rs))
 570                         scrub_print_warning("i/o error", sbio, ix);
 571         } else {
 572                 if (__ratelimit(&_rs))
 573                         scrub_print_warning("checksum error", sbio, ix);
 574         }
 575
 576         spin_lock(&sdev->stat_lock);
 577         ++sdev->stat.read_errors;
 578         spin_unlock(&sdev->stat_lock);
 579
 580         scrub_fixup(sbio, ix);
 581         return 1;
 582 }
 583
 584 static int scrub_fixup_check(struct scrub_bio *sbio, int ix)
 585 {
 586         int ret = 1;
 587         struct page *page;
 588         void *buffer;
 589         u64 flags = sbio->spag[ix].flags;
 590
 591         page = sbio->bio->bi_io_vec[ix].bv_page;
 592         buffer = kmap_atomic(page, KM_USER0);
 593         if (flags & BTRFS_EXTENT_FLAG_DATA) {
 594                 ret = scrub_checksum_data(sbio->sdev,
 595                                           sbio->spag + ix, buffer);
 596         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 597                 ret = scrub_checksum_tree_block(sbio->sdev,
 598                                                 sbio->spag + ix,
 599                                                 sbio->logical + ix * PAGE_SIZE,
 600                                                 buffer);
 601         } else {
 602                 WARN_ON(1);
 603         }
 604         kunmap_atomic(buffer, KM_USER0);
 605
 606         return ret;
 607 }
 608
 609 static void scrub_fixup_end_io(struct bio *bio, int err)
 610 {
 611         complete((struct completion *)bio->bi_private);
 612 }
 613
 614 static void scrub_fixup(struct scrub_bio *sbio, int ix)
 615 {
 616         struct scrub_dev *sdev = sbio->sdev;
 617         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 618         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
 619         struct btrfs_bio *bbio = NULL;
 620         struct scrub_fixup_nodatasum *fixup;
 621         u64 logical = sbio->logical + ix * PAGE_SIZE;
 622         u64 length;
 623         int i;
 624         int ret;
 625         DECLARE_COMPLETION_ONSTACK(complete);
 626
 627         if ((sbio->spag[ix].flags & BTRFS_EXTENT_FLAG_DATA) &&
 628             (sbio->spag[ix].have_csum == 0)) {
 629                 fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
 630                 if (!fixup)
 631                         goto uncorrectable;
 632                 fixup->sdev = sdev;
 633                 fixup->logical = logical;
 634                 fixup->root = fs_info->extent_root;
 635                 fixup->mirror_num = sbio->spag[ix].mirror_num;
 636                 /*
 637                  * increment scrubs_running to prevent cancel requests from
 638                  * completing as long as a fixup worker is running. we must also
 639                  * increment scrubs_paused to prevent deadlocking on pause
 640                  * requests used for transactions commits (as the worker uses a
 641                  * transaction context). it is safe to regard the fixup worker
 642                  * as paused for all matters practical. effectively, we only
 643                  * avoid cancellation requests from completing.
 644                  */
 645                 mutex_lock(&fs_info->scrub_lock);
 646                 atomic_inc(&fs_info->scrubs_running);
 647                 atomic_inc(&fs_info->scrubs_paused);
 648                 mutex_unlock(&fs_info->scrub_lock);
 649                 atomic_inc(&sdev->fixup_cnt);
 650                 fixup->work.func = scrub_fixup_nodatasum;
 651                 btrfs_queue_worker(&fs_info->scrub_workers, &fixup->work);
 652                 return;
 653         }
 654
 655         length = PAGE_SIZE;
 656         ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length,
 657                               &bbio, 0);
 658         if (ret || !bbio || length < PAGE_SIZE) {
 659                 printk(KERN_ERR
 660                        "scrub_fixup: btrfs_map_block failed us for %llu\n",
 661                        (unsigned long long)logical);
 662                 WARN_ON(1);
 663                 kfree(bbio);
 664                 return;
 665         }
 666
 667         if (bbio->num_stripes == 1)
 668                 /* there aren't any replicas */
 669                 goto uncorrectable;
 670
 671         /*
 672          * first find a good copy
 673          */
 674         for (i = 0; i < bbio->num_stripes; ++i) {
 675                 if (i + 1 == sbio->spag[ix].mirror_num)
 676                         continue;
 677
 678                 if (scrub_fixup_io(READ, bbio->stripes[i].dev->bdev,
 679                                    bbio->stripes[i].physical >> 9,
 680                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 681                         /* I/O-error, this is not a good copy */
 682                         continue;
 683                 }
 684
 685                 if (scrub_fixup_check(sbio, ix) == 0)
 686                         break;
 687         }
 688         if (i == bbio->num_stripes)
 689                 goto uncorrectable;
 690
 691         if (!sdev->readonly) {
 692                 /*
 693                  * bi_io_vec[ix].bv_page now contains good data, write it back
 694                  */
 695                 if (scrub_fixup_io(WRITE, sdev->dev->bdev,
 696                                    (sbio->physical + ix * PAGE_SIZE) >> 9,
 697                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 698                         /* I/O-error, writeback failed, give up */
 699                         goto uncorrectable;
 700                 }
 701         }
 702
 703         kfree(bbio);
 704         spin_lock(&sdev->stat_lock);
 705         ++sdev->stat.corrected_errors;
 706         spin_unlock(&sdev->stat_lock);
 707
 708         printk_ratelimited(KERN_ERR "btrfs: fixed up error at logical %llu\n",
 709                                (unsigned long long)logical);
 710         return;
 711
 712 uncorrectable:
 713         kfree(bbio);
 714         spin_lock(&sdev->stat_lock);
 715         ++sdev->stat.uncorrectable_errors;
 716         spin_unlock(&sdev->stat_lock);
 717
 718         printk_ratelimited(KERN_ERR "btrfs: unable to fixup (regular) error at "
 719                                 "logical %llu\n", (unsigned long long)logical);
 720 }
 721
 722 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
 723                          struct page *page)
 724 {
 725         struct bio *bio = NULL;
 726         int ret;
 727         DECLARE_COMPLETION_ONSTACK(complete);
 728
 729         bio = bio_alloc(GFP_NOFS, 1);
 730         bio->bi_bdev = bdev;
 731         bio->bi_sector = sector;
 732         bio_add_page(bio, page, PAGE_SIZE, 0);
 733         bio->bi_end_io = scrub_fixup_end_io;
 734         bio->bi_private = &complete;
 735         submit_bio(rw, bio);
 736
 737         /* this will also unplug the queue */
 738         wait_for_completion(&complete);
 739
 740         ret = !test_bit(BIO_UPTODATE, &bio->bi_flags);
 741         bio_put(bio);
 742         return ret;
 743 }
 744
 745 static void scrub_bio_end_io(struct bio *bio, int err)
 746 {
 747         struct scrub_bio *sbio = bio->bi_private;
 748         struct scrub_dev *sdev = sbio->sdev;
 749         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 750
 751         sbio->err = err;
 752         sbio->bio = bio;
 753
 754         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
 755 }
 756
 757 static void scrub_checksum(struct btrfs_work *work)
 758 {
 759         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
 760         struct scrub_dev *sdev = sbio->sdev;
 761         struct page *page;
 762         void *buffer;
 763         int i;
 764         u64 flags;
 765         u64 logical;
 766         int ret;
 767
 768         if (sbio->err) {
 769                 ret = 0;
 770                 for (i = 0; i < sbio->count; ++i)
 771                         ret |= scrub_recheck_error(sbio, i);
 772                 if (!ret) {
 773                         spin_lock(&sdev->stat_lock);
 774                         ++sdev->stat.unverified_errors;
 775                         spin_unlock(&sdev->stat_lock);
 776                 }
 777
 778                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
 779                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
 780                 sbio->bio->bi_phys_segments = 0;
 781                 sbio->bio->bi_idx = 0;
 782
 783                 for (i = 0; i < sbio->count; i++) {
 784                         struct bio_vec *bi;
 785                         bi = &sbio->bio->bi_io_vec[i];
 786                         bi->bv_offset = 0;
 787                         bi->bv_len = PAGE_SIZE;
 788                 }
 789                 goto out;
 790         }
 791         for (i = 0; i < sbio->count; ++i) {
 792                 page = sbio->bio->bi_io_vec[i].bv_page;
 793                 buffer = kmap_atomic(page, KM_USER0);
 794                 flags = sbio->spag[i].flags;
 795                 logical = sbio->logical + i * PAGE_SIZE;
 796                 ret = 0;
 797                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
 798                         ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
 799                 } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 800                         ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
 801                                                         logical, buffer);
 802                 } else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
 803                         BUG_ON(i);
 804                         (void)scrub_checksum_super(sbio, buffer);
 805                 } else {
 806                         WARN_ON(1);
 807                 }
 808                 kunmap_atomic(buffer, KM_USER0);
 809                 if (ret) {
 810                         ret = scrub_recheck_error(sbio, i);
 811                         if (!ret) {
 812                                 spin_lock(&sdev->stat_lock);
 813                                 ++sdev->stat.unverified_errors;
 814                                 spin_unlock(&sdev->stat_lock);
 815                         }
 816                 }
 817         }
 818
 819 out:
 820         scrub_free_bio(sbio->bio);
 821         sbio->bio = NULL;
 822         spin_lock(&sdev->list_lock);
 823         sbio->next_free = sdev->first_free;
 824         sdev->first_free = sbio->index;
 825         spin_unlock(&sdev->list_lock);
 826         atomic_dec(&sdev->in_flight);
 827         wake_up(&sdev->list_wait);
 828 }
 829
 830 static int scrub_checksum_data(struct scrub_dev *sdev,
 831                                struct scrub_page *spag, void *buffer)
 832 {
 833         u8 csum[BTRFS_CSUM_SIZE];
 834         u32 crc = ~(u32)0;
 835         int fail = 0;
 836         struct btrfs_root *root = sdev->dev->dev_root;
 837
 838         if (!spag->have_csum)
 839                 return 0;
 840
 841         crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
 842         btrfs_csum_final(crc, csum);
 843         if (memcmp(csum, spag->csum, sdev->csum_size))
 844                 fail = 1;
 845
 846         spin_lock(&sdev->stat_lock);
 847         ++sdev->stat.data_extents_scrubbed;
 848         sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
 849         if (fail)
 850                 ++sdev->stat.csum_errors;
 851         spin_unlock(&sdev->stat_lock);
 852
 853         return fail;
 854 }
 855
 856 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
 857                                      struct scrub_page *spag, u64 logical,
 858                                      void *buffer)
 859 {
 860         struct btrfs_header *h;
 861         struct btrfs_root *root = sdev->dev->dev_root;
 862         struct btrfs_fs_info *fs_info = root->fs_info;
 863         u8 csum[BTRFS_CSUM_SIZE];
 864         u32 crc = ~(u32)0;
 865         int fail = 0;
 866         int crc_fail = 0;
 867
 868         /*
 869          * we don't use the getter functions here, as we
 870          * a) don't have an extent buffer and
 871          * b) the page is already kmapped
 872          */
 873         h = (struct btrfs_header *)buffer;
 874
 875         if (logical != le64_to_cpu(h->bytenr))
 876                 ++fail;
 877
 878         if (spag->generation != le64_to_cpu(h->generation))
 879                 ++fail;
 880
 881         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 882                 ++fail;
 883
 884         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
 885                    BTRFS_UUID_SIZE))
 886                 ++fail;
 887
 888         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 889                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 890         btrfs_csum_final(crc, csum);
 891         if (memcmp(csum, h->csum, sdev->csum_size))
 892                 ++crc_fail;
 893
 894         spin_lock(&sdev->stat_lock);
 895         ++sdev->stat.tree_extents_scrubbed;
 896         sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
 897         if (crc_fail)
 898                 ++sdev->stat.csum_errors;
 899         if (fail)
 900                 ++sdev->stat.verify_errors;
 901         spin_unlock(&sdev->stat_lock);
 902
 903         return fail || crc_fail;
 904 }
 905
 906 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
 907 {
 908         struct btrfs_super_block *s;
 909         u64 logical;
 910         struct scrub_dev *sdev = sbio->sdev;
 911         struct btrfs_root *root = sdev->dev->dev_root;
 912         struct btrfs_fs_info *fs_info = root->fs_info;
 913         u8 csum[BTRFS_CSUM_SIZE];
 914         u32 crc = ~(u32)0;
 915         int fail = 0;
 916
 917         s = (struct btrfs_super_block *)buffer;
 918         logical = sbio->logical;
 919
 920         if (logical != le64_to_cpu(s->bytenr))
 921                 ++fail;
 922
 923         if (sbio->spag[0].generation != le64_to_cpu(s->generation))
 924                 ++fail;
 925
 926         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 927                 ++fail;
 928
 929         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 930                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 931         btrfs_csum_final(crc, csum);
 932         if (memcmp(csum, s->csum, sbio->sdev->csum_size))
 933                 ++fail;
 934
 935         if (fail) {
 936                 /*
 937                  * if we find an error in a super block, we just report it.
 938                  * They will get written with the next transaction commit
 939                  * anyway
 940                  */
 941                 spin_lock(&sdev->stat_lock);
 942                 ++sdev->stat.super_errors;
 943                 spin_unlock(&sdev->stat_lock);
 944         }
 945
 946         return fail;
 947 }
 948
 949 static int scrub_submit(struct scrub_dev *sdev)
 950 {
 951         struct scrub_bio *sbio;
 952
 953         if (sdev->curr == -1)
 954                 return 0;
 955
 956         sbio = sdev->bios[sdev->curr];
 957         sbio->err = 0;
 958         sdev->curr = -1;
 959         atomic_inc(&sdev->in_flight);
 960
 961         submit_bio(READ, sbio->bio);
 962
 963         return 0;
 964 }
 965
 966 static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
 967                       u64 physical, u64 flags, u64 gen, int mirror_num,
 968                       u8 *csum, int force)
 969 {
 970         struct scrub_bio *sbio;
 971         struct page *page;
 972         int ret;
 973
 974 again:
 975         /*
 976          * grab a fresh bio or wait for one to become available
 977          */
 978         while (sdev->curr == -1) {
 979                 spin_lock(&sdev->list_lock);
 980                 sdev->curr = sdev->first_free;
 981                 if (sdev->curr != -1) {
 982                         sdev->first_free = sdev->bios[sdev->curr]->next_free;
 983                         sdev->bios[sdev->curr]->next_free = -1;
 984                         sdev->bios[sdev->curr]->count = 0;
 985                         spin_unlock(&sdev->list_lock);
 986                 } else {
 987                         spin_unlock(&sdev->list_lock);
 988                         wait_event(sdev->list_wait, sdev->first_free != -1);
 989                 }
 990         }
 991         sbio = sdev->bios[sdev->curr];
 992         if (sbio->count == 0) {
 993                 struct bio *bio;
 994
 995                 sbio->physical = physical;
 996                 sbio->logical = logical;
 997                 bio = bio_alloc(GFP_NOFS, SCRUB_PAGES_PER_BIO);
 998                 if (!bio)
 999                         return -ENOMEM;
1000
1001                 bio->bi_private = sbio;
1002                 bio->bi_end_io = scrub_bio_end_io;
1003                 bio->bi_bdev = sdev->dev->bdev;
1004                 bio->bi_sector = sbio->physical >> 9;
1005                 sbio->err = 0;
1006                 sbio->bio = bio;
1007         } else if (sbio->physical + sbio->count * PAGE_SIZE != physical ||
1008                    sbio->logical + sbio->count * PAGE_SIZE != logical) {
1009                 ret = scrub_submit(sdev);
1010                 if (ret)
1011                         return ret;
1012                 goto again;
1013         }
1014         sbio->spag[sbio->count].flags = flags;
1015         sbio->spag[sbio->count].generation = gen;
1016         sbio->spag[sbio->count].have_csum = 0;
1017         sbio->spag[sbio->count].mirror_num = mirror_num;
1018
1019         page = alloc_page(GFP_NOFS);
1020         if (!page)
1021                 return -ENOMEM;
1022
1023         ret = bio_add_page(sbio->bio, page, PAGE_SIZE, 0);
1024         if (!ret) {
1025                 __free_page(page);
1026                 ret = scrub_submit(sdev);
1027                 if (ret)
1028                         return ret;
1029                 goto again;
1030         }
1031
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         int ret = 0;
1539
1540         mutex_lock(&fs_info->scrub_lock);
1541         if (fs_info->scrub_workers_refcnt == 0) {
1542                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
1543                            fs_info->thread_pool_size, &fs_info->generic_worker);
1544                 fs_info->scrub_workers.idle_thresh = 4;
1545                 ret = btrfs_start_workers(&fs_info->scrub_workers);
1546                 if (ret)
1547                         goto out;
1548         }
1549         ++fs_info->scrub_workers_refcnt;
1550 out:
1551         mutex_unlock(&fs_info->scrub_lock);
1552
1553         return ret;
1554 }
1555
1556 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
1557 {
1558         struct btrfs_fs_info *fs_info = root->fs_info;
1559
1560         mutex_lock(&fs_info->scrub_lock);
1561         if (--fs_info->scrub_workers_refcnt == 0)
1562                 btrfs_stop_workers(&fs_info->scrub_workers);
1563         WARN_ON(fs_info->scrub_workers_refcnt < 0);
1564         mutex_unlock(&fs_info->scrub_lock);
1565 }
1566
1567
1568 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
1569                     struct btrfs_scrub_progress *progress, int readonly)
1570 {
1571         struct scrub_dev *sdev;
1572         struct btrfs_fs_info *fs_info = root->fs_info;
1573         int ret;
1574         struct btrfs_device *dev;
1575
1576         if (btrfs_fs_closing(root->fs_info))
1577                 return -EINVAL;
1578
1579         /*
1580          * check some assumptions
1581          */
1582         if (root->sectorsize != PAGE_SIZE ||
1583             root->sectorsize != root->leafsize ||
1584             root->sectorsize != root->nodesize) {
1585                 printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
1586                 return -EINVAL;
1587         }
1588
1589         ret = scrub_workers_get(root);
1590         if (ret)
1591                 return ret;
1592
1593         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1594         dev = btrfs_find_device(root, devid, NULL, NULL);
1595         if (!dev || dev->missing) {
1596                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1597                 scrub_workers_put(root);
1598                 return -ENODEV;
1599         }
1600         mutex_lock(&fs_info->scrub_lock);
1601
1602         if (!dev->in_fs_metadata) {
1603                 mutex_unlock(&fs_info->scrub_lock);
1604                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1605                 scrub_workers_put(root);
1606                 return -ENODEV;
1607         }
1608
1609         if (dev->scrub_device) {
1610                 mutex_unlock(&fs_info->scrub_lock);
1611                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1612                 scrub_workers_put(root);
1613                 return -EINPROGRESS;
1614         }
1615         sdev = scrub_setup_dev(dev);
1616         if (IS_ERR(sdev)) {
1617                 mutex_unlock(&fs_info->scrub_lock);
1618                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1619                 scrub_workers_put(root);
1620                 return PTR_ERR(sdev);
1621         }
1622         sdev->readonly = readonly;
1623         dev->scrub_device = sdev;
1624
1625         atomic_inc(&fs_info->scrubs_running);
1626         mutex_unlock(&fs_info->scrub_lock);
1627         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1628
1629         down_read(&fs_info->scrub_super_lock);
1630         ret = scrub_supers(sdev);
1631         up_read(&fs_info->scrub_super_lock);
1632
1633         if (!ret)
1634                 ret = scrub_enumerate_chunks(sdev, start, end);
1635
1636         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1637         atomic_dec(&fs_info->scrubs_running);
1638         wake_up(&fs_info->scrub_pause_wait);
1639
1640         wait_event(sdev->list_wait, atomic_read(&sdev->fixup_cnt) == 0);
1641
1642         if (progress)
1643                 memcpy(progress, &sdev->stat, sizeof(*progress));
1644
1645         mutex_lock(&fs_info->scrub_lock);
1646         dev->scrub_device = NULL;
1647         mutex_unlock(&fs_info->scrub_lock);
1648
1649         scrub_free_dev(sdev);
1650         scrub_workers_put(root);
1651
1652         return ret;
1653 }
1654
1655 int btrfs_scrub_pause(struct btrfs_root *root)
1656 {
1657         struct btrfs_fs_info *fs_info = root->fs_info;
1658
1659         mutex_lock(&fs_info->scrub_lock);
1660         atomic_inc(&fs_info->scrub_pause_req);
1661         while (atomic_read(&fs_info->scrubs_paused) !=
1662                atomic_read(&fs_info->scrubs_running)) {
1663                 mutex_unlock(&fs_info->scrub_lock);
1664                 wait_event(fs_info->scrub_pause_wait,
1665                            atomic_read(&fs_info->scrubs_paused) ==
1666                            atomic_read(&fs_info->scrubs_running));
1667                 mutex_lock(&fs_info->scrub_lock);
1668         }
1669         mutex_unlock(&fs_info->scrub_lock);
1670
1671         return 0;
1672 }
1673
1674 int btrfs_scrub_continue(struct btrfs_root *root)
1675 {
1676         struct btrfs_fs_info *fs_info = root->fs_info;
1677
1678         atomic_dec(&fs_info->scrub_pause_req);
1679         wake_up(&fs_info->scrub_pause_wait);
1680         return 0;
1681 }
1682
1683 int btrfs_scrub_pause_super(struct btrfs_root *root)
1684 {
1685         down_write(&root->fs_info->scrub_super_lock);
1686         return 0;
1687 }
1688
1689 int btrfs_scrub_continue_super(struct btrfs_root *root)
1690 {
1691         up_write(&root->fs_info->scrub_super_lock);
1692         return 0;
1693 }
1694
1695 int btrfs_scrub_cancel(struct btrfs_root *root)
1696 {
1697         struct btrfs_fs_info *fs_info = root->fs_info;
1698
1699         mutex_lock(&fs_info->scrub_lock);
1700         if (!atomic_read(&fs_info->scrubs_running)) {
1701                 mutex_unlock(&fs_info->scrub_lock);
1702                 return -ENOTCONN;
1703         }
1704
1705         atomic_inc(&fs_info->scrub_cancel_req);
1706         while (atomic_read(&fs_info->scrubs_running)) {
1707                 mutex_unlock(&fs_info->scrub_lock);
1708                 wait_event(fs_info->scrub_pause_wait,
1709                            atomic_read(&fs_info->scrubs_running) == 0);
1710                 mutex_lock(&fs_info->scrub_lock);
1711         }
1712         atomic_dec(&fs_info->scrub_cancel_req);
1713         mutex_unlock(&fs_info->scrub_lock);
1714
1715         return 0;
1716 }
1717
1718 int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
1719 {
1720         struct btrfs_fs_info *fs_info = root->fs_info;
1721         struct scrub_dev *sdev;
1722
1723         mutex_lock(&fs_info->scrub_lock);
1724         sdev = dev->scrub_device;
1725         if (!sdev) {
1726                 mutex_unlock(&fs_info->scrub_lock);
1727                 return -ENOTCONN;
1728         }
1729         atomic_inc(&sdev->cancel_req);
1730         while (dev->scrub_device) {
1731                 mutex_unlock(&fs_info->scrub_lock);
1732                 wait_event(fs_info->scrub_pause_wait,
1733                            dev->scrub_device == NULL);
1734                 mutex_lock(&fs_info->scrub_lock);
1735         }
1736         mutex_unlock(&fs_info->scrub_lock);
1737
1738         return 0;
1739 }
1740 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
1741 {
1742         struct btrfs_fs_info *fs_info = root->fs_info;
1743         struct btrfs_device *dev;
1744         int ret;
1745
1746         /*
1747          * we have to hold the device_list_mutex here so the device
1748          * does not go away in cancel_dev. FIXME: find a better solution
1749          */
1750         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1751         dev = btrfs_find_device(root, devid, NULL, NULL);
1752         if (!dev) {
1753                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1754                 return -ENODEV;
1755         }
1756         ret = btrfs_scrub_cancel_dev(root, dev);
1757         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1758
1759         return ret;
1760 }
1761
1762 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
1763                          struct btrfs_scrub_progress *progress)
1764 {
1765         struct btrfs_device *dev;
1766         struct scrub_dev *sdev = NULL;
1767
1768         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1769         dev = btrfs_find_device(root, devid, NULL, NULL);
1770         if (dev)
1771                 sdev = dev->scrub_device;
1772         if (sdev)
1773                 memcpy(progress, &sdev->stat, sizeof(*progress));
1774         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1775
1776         return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
1777 }