Pileus Git - ~andy/linux/blob - 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 #include "check-integrity.h"
  29
  30 /*
  31  * This is only the first step towards a full-features scrub. It reads all
  32  * extent and super block and verifies the checksums. In case a bad checksum
  33  * is found or the extent cannot be read, good data will be written back if
  34  * any can be found.
  35  *
  36  * Future enhancements:
  37  *  - In case an unrepairable extent is encountered, track which files are
  38  *    affected and report them
  39  *  - In case of a read error on files with nodatasum, map the file and read
  40  *    the extent to trigger a writeback of the good copy
  41  *  - track and record media errors, throw out bad devices
  42  *  - add a mode to also read unallocated space
  43  */
  44
  45 struct scrub_bio;
  46 struct scrub_page;
  47 struct scrub_dev;
  48 static void scrub_bio_end_io(struct bio *bio, int err);
  49 static void scrub_checksum(struct btrfs_work *work);
  50 static int scrub_checksum_data(struct scrub_dev *sdev,
  51                                struct scrub_page *spag, void *buffer);
  52 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
  53                                      struct scrub_page *spag, u64 logical,
  54                                      void *buffer);
  55 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer);
  56 static int scrub_fixup_check(struct scrub_bio *sbio, int ix);
  57 static void scrub_fixup_end_io(struct bio *bio, int err);
  58 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
  59                           struct page *page);
  60 static void scrub_fixup(struct scrub_bio *sbio, int ix);
  61
  62 #define SCRUB_PAGES_PER_BIO     16      /* 64k per bio */
  63 #define SCRUB_BIOS_PER_DEV      16      /* 1 MB per device in flight */
  64
  65 struct scrub_page {
  66         u64                     flags;  /* extent flags */
  67         u64                     generation;
  68         int                     mirror_num;
  69         int                     have_csum;
  70         u8                      csum[BTRFS_CSUM_SIZE];
  71 };
  72
  73 struct scrub_bio {
  74         int                     index;
  75         struct scrub_dev        *sdev;
  76         struct bio              *bio;
  77         int                     err;
  78         u64                     logical;
  79         u64                     physical;
  80         struct scrub_page       spag[SCRUB_PAGES_PER_BIO];
  81         u64                     count;
  82         int                     next_free;
  83         struct btrfs_work       work;
  84 };
  85
  86 struct scrub_dev {
  87         struct scrub_bio        *bios[SCRUB_BIOS_PER_DEV];
  88         struct btrfs_device     *dev;
  89         int                     first_free;
  90         int                     curr;
  91         atomic_t                in_flight;
  92         atomic_t                fixup_cnt;
  93         spinlock_t              list_lock;
  94         wait_queue_head_t       list_wait;
  95         u16                     csum_size;
  96         struct list_head        csum_list;
  97         atomic_t                cancel_req;
  98         int                     readonly;
  99         /*
 100          * statistics
 101          */
 102         struct btrfs_scrub_progress stat;
 103         spinlock_t              stat_lock;
 104 };
 105
 106 struct scrub_fixup_nodatasum {
 107         struct scrub_dev        *sdev;
 108         u64                     logical;
 109         struct btrfs_root       *root;
 110         struct btrfs_work       work;
 111         int                     mirror_num;
 112 };
 113
 114 struct scrub_warning {
 115         struct btrfs_path       *path;
 116         u64                     extent_item_size;
 117         char                    *scratch_buf;
 118         char                    *msg_buf;
 119         const char              *errstr;
 120         sector_t                sector;
 121         u64                     logical;
 122         struct btrfs_device     *dev;
 123         int                     msg_bufsize;
 124         int                     scratch_bufsize;
 125 };
 126
 127 static void scrub_free_csums(struct scrub_dev *sdev)
 128 {
 129         while (!list_empty(&sdev->csum_list)) {
 130                 struct btrfs_ordered_sum *sum;
 131                 sum = list_first_entry(&sdev->csum_list,
 132                                        struct btrfs_ordered_sum, list);
 133                 list_del(&sum->list);
 134                 kfree(sum);
 135         }
 136 }
 137
 138 static void scrub_free_bio(struct bio *bio)
 139 {
 140         int i;
 141         struct page *last_page = NULL;
 142
 143         if (!bio)
 144                 return;
 145
 146         for (i = 0; i < bio->bi_vcnt; ++i) {
 147                 if (bio->bi_io_vec[i].bv_page == last_page)
 148                         continue;
 149                 last_page = bio->bi_io_vec[i].bv_page;
 150                 __free_page(last_page);
 151         }
 152         bio_put(bio);
 153 }
 154
 155 static noinline_for_stack void scrub_free_dev(struct scrub_dev *sdev)
 156 {
 157         int i;
 158
 159         if (!sdev)
 160                 return;
 161
 162         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
 163                 struct scrub_bio *sbio = sdev->bios[i];
 164
 165                 if (!sbio)
 166                         break;
 167
 168                 scrub_free_bio(sbio->bio);
 169                 kfree(sbio);
 170         }
 171
 172         scrub_free_csums(sdev);
 173         kfree(sdev);
 174 }
 175
 176 static noinline_for_stack
 177 struct scrub_dev *scrub_setup_dev(struct btrfs_device *dev)
 178 {
 179         struct scrub_dev *sdev;
 180         int             i;
 181         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 182
 183         sdev = kzalloc(sizeof(*sdev), GFP_NOFS);
 184         if (!sdev)
 185                 goto nomem;
 186         sdev->dev = dev;
 187         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
 188                 struct scrub_bio *sbio;
 189
 190                 sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
 191                 if (!sbio)
 192                         goto nomem;
 193                 sdev->bios[i] = sbio;
 194
 195                 sbio->index = i;
 196                 sbio->sdev = sdev;
 197                 sbio->count = 0;
 198                 sbio->work.func = scrub_checksum;
 199
 200                 if (i != SCRUB_BIOS_PER_DEV-1)
 201                         sdev->bios[i]->next_free = i + 1;
 202                 else
 203                         sdev->bios[i]->next_free = -1;
 204         }
 205         sdev->first_free = 0;
 206         sdev->curr = -1;
 207         atomic_set(&sdev->in_flight, 0);
 208         atomic_set(&sdev->fixup_cnt, 0);
 209         atomic_set(&sdev->cancel_req, 0);
 210         sdev->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 211         INIT_LIST_HEAD(&sdev->csum_list);
 212
 213         spin_lock_init(&sdev->list_lock);
 214         spin_lock_init(&sdev->stat_lock);
 215         init_waitqueue_head(&sdev->list_wait);
 216         return sdev;
 217
 218 nomem:
 219         scrub_free_dev(sdev);
 220         return ERR_PTR(-ENOMEM);
 221 }
 222
 223 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, void *ctx)
 224 {
 225         u64 isize;
 226         u32 nlink;
 227         int ret;
 228         int i;
 229         struct extent_buffer *eb;
 230         struct btrfs_inode_item *inode_item;
 231         struct scrub_warning *swarn = ctx;
 232         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
 233         struct inode_fs_paths *ipath = NULL;
 234         struct btrfs_root *local_root;
 235         struct btrfs_key root_key;
 236
 237         root_key.objectid = root;
 238         root_key.type = BTRFS_ROOT_ITEM_KEY;
 239         root_key.offset = (u64)-1;
 240         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 241         if (IS_ERR(local_root)) {
 242                 ret = PTR_ERR(local_root);
 243                 goto err;
 244         }
 245
 246         ret = inode_item_info(inum, 0, local_root, swarn->path);
 247         if (ret) {
 248                 btrfs_release_path(swarn->path);
 249                 goto err;
 250         }
 251
 252         eb = swarn->path->nodes[0];
 253         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 254                                         struct btrfs_inode_item);
 255         isize = btrfs_inode_size(eb, inode_item);
 256         nlink = btrfs_inode_nlink(eb, inode_item);
 257         btrfs_release_path(swarn->path);
 258
 259         ipath = init_ipath(4096, local_root, swarn->path);
 260         if (IS_ERR(ipath)) {
 261                 ret = PTR_ERR(ipath);
 262                 ipath = NULL;
 263                 goto err;
 264         }
 265         ret = paths_from_inode(inum, ipath);
 266
 267         if (ret < 0)
 268                 goto err;
 269
 270         /*
 271          * we deliberately ignore the bit ipath might have been too small to
 272          * hold all of the paths here
 273          */
 274         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 275                 printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
 276                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
 277                         "length %llu, links %u (path: %s)\n", swarn->errstr,
 278                         swarn->logical, swarn->dev->name,
 279                         (unsigned long long)swarn->sector, root, inum, offset,
 280                         min(isize - offset, (u64)PAGE_SIZE), nlink,
 281                         (char *)(unsigned long)ipath->fspath->val[i]);
 282
 283         free_ipath(ipath);
 284         return 0;
 285
 286 err:
 287         printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
 288                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
 289                 "resolving failed with ret=%d\n", swarn->errstr,
 290                 swarn->logical, swarn->dev->name,
 291                 (unsigned long long)swarn->sector, root, inum, offset, ret);
 292
 293         free_ipath(ipath);
 294         return 0;
 295 }
 296
 297 static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
 298                                 int ix)
 299 {
 300         struct btrfs_device *dev = sbio->sdev->dev;
 301         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 302         struct btrfs_path *path;
 303         struct btrfs_key found_key;
 304         struct extent_buffer *eb;
 305         struct btrfs_extent_item *ei;
 306         struct scrub_warning swarn;
 307         u32 item_size;
 308         int ret;
 309         u64 ref_root;
 310         u8 ref_level;
 311         unsigned long ptr = 0;
 312         const int bufsize = 4096;
 313         u64 extent_item_pos;
 314
 315         path = btrfs_alloc_path();
 316
 317         swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
 318         swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
 319         swarn.sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 320         swarn.logical = sbio->logical + ix * PAGE_SIZE;
 321         swarn.errstr = errstr;
 322         swarn.dev = dev;
 323         swarn.msg_bufsize = bufsize;
 324         swarn.scratch_bufsize = bufsize;
 325
 326         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
 327                 goto out;
 328
 329         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key);
 330         if (ret < 0)
 331                 goto out;
 332
 333         extent_item_pos = swarn.logical - found_key.objectid;
 334         swarn.extent_item_size = found_key.offset;
 335
 336         eb = path->nodes[0];
 337         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 338         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 339         btrfs_release_path(path);
 340
 341         if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 342                 do {
 343                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
 344                                                         &ref_root, &ref_level);
 345                         printk(KERN_WARNING "%s at logical %llu on dev %s, "
 346                                 "sector %llu: metadata %s (level %d) in tree "
 347                                 "%llu\n", errstr, swarn.logical, dev->name,
 348                                 (unsigned long long)swarn.sector,
 349                                 ref_level ? "node" : "leaf",
 350                                 ret < 0 ? -1 : ref_level,
 351                                 ret < 0 ? -1 : ref_root);
 352                 } while (ret != 1);
 353         } else {
 354                 swarn.path = path;
 355                 iterate_extent_inodes(fs_info, path, found_key.objectid,
 356                                         extent_item_pos,
 357                                         scrub_print_warning_inode, &swarn);
 358         }
 359
 360 out:
 361         btrfs_free_path(path);
 362         kfree(swarn.scratch_buf);
 363         kfree(swarn.msg_buf);
 364 }
 365
 366 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *ctx)
 367 {
 368         struct page *page = NULL;
 369         unsigned long index;
 370         struct scrub_fixup_nodatasum *fixup = ctx;
 371         int ret;
 372         int corrected = 0;
 373         struct btrfs_key key;
 374         struct inode *inode = NULL;
 375         u64 end = offset + PAGE_SIZE - 1;
 376         struct btrfs_root *local_root;
 377
 378         key.objectid = root;
 379         key.type = BTRFS_ROOT_ITEM_KEY;
 380         key.offset = (u64)-1;
 381         local_root = btrfs_read_fs_root_no_name(fixup->root->fs_info, &key);
 382         if (IS_ERR(local_root))
 383                 return PTR_ERR(local_root);
 384
 385         key.type = BTRFS_INODE_ITEM_KEY;
 386         key.objectid = inum;
 387         key.offset = 0;
 388         inode = btrfs_iget(fixup->root->fs_info->sb, &key, local_root, NULL);
 389         if (IS_ERR(inode))
 390                 return PTR_ERR(inode);
 391
 392         index = offset >> PAGE_CACHE_SHIFT;
 393
 394         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 395         if (!page) {
 396                 ret = -ENOMEM;
 397                 goto out;
 398         }
 399
 400         if (PageUptodate(page)) {
 401                 struct btrfs_mapping_tree *map_tree;
 402                 if (PageDirty(page)) {
 403                         /*
 404                          * we need to write the data to the defect sector. the
 405                          * data that was in that sector is not in memory,
 406                          * because the page was modified. we must not write the
 407                          * modified page to that sector.
 408                          *
 409                          * TODO: what could be done here: wait for the delalloc
 410                          *       runner to write out that page (might involve
 411                          *       COW) and see whether the sector is still
 412                          *       referenced afterwards.
 413                          *
 414                          * For the meantime, we'll treat this error
 415                          * incorrectable, although there is a chance that a
 416                          * later scrub will find the bad sector again and that
 417                          * there's no dirty page in memory, then.
 418                          */
 419                         ret = -EIO;
 420                         goto out;
 421                 }
 422                 map_tree = &BTRFS_I(inode)->root->fs_info->mapping_tree;
 423                 ret = repair_io_failure(map_tree, offset, PAGE_SIZE,
 424                                         fixup->logical, page,
 425                                         fixup->mirror_num);
 426                 unlock_page(page);
 427                 corrected = !ret;
 428         } else {
 429                 /*
 430                  * we need to get good data first. the general readpage path
 431                  * will call repair_io_failure for us, we just have to make
 432                  * sure we read the bad mirror.
 433                  */
 434                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 435                                         EXTENT_DAMAGED, GFP_NOFS);
 436                 if (ret) {
 437                         /* set_extent_bits should give proper error */
 438                         WARN_ON(ret > 0);
 439                         if (ret > 0)
 440                                 ret = -EFAULT;
 441                         goto out;
 442                 }
 443
 444                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 445                                                 btrfs_get_extent,
 446                                                 fixup->mirror_num);
 447                 wait_on_page_locked(page);
 448
 449                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 450                                                 end, EXTENT_DAMAGED, 0, NULL);
 451                 if (!corrected)
 452                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 453                                                 EXTENT_DAMAGED, GFP_NOFS);
 454         }
 455
 456 out:
 457         if (page)
 458                 put_page(page);
 459         if (inode)
 460                 iput(inode);
 461
 462         if (ret < 0)
 463                 return ret;
 464
 465         if (ret == 0 && corrected) {
 466                 /*
 467                  * we only need to call readpage for one of the inodes belonging
 468                  * to this extent. so make iterate_extent_inodes stop
 469                  */
 470                 return 1;
 471         }
 472
 473         return -EIO;
 474 }
 475
 476 static void scrub_fixup_nodatasum(struct btrfs_work *work)
 477 {
 478         int ret;
 479         struct scrub_fixup_nodatasum *fixup;
 480         struct scrub_dev *sdev;
 481         struct btrfs_trans_handle *trans = NULL;
 482         struct btrfs_fs_info *fs_info;
 483         struct btrfs_path *path;
 484         int uncorrectable = 0;
 485
 486         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
 487         sdev = fixup->sdev;
 488         fs_info = fixup->root->fs_info;
 489
 490         path = btrfs_alloc_path();
 491         if (!path) {
 492                 spin_lock(&sdev->stat_lock);
 493                 ++sdev->stat.malloc_errors;
 494                 spin_unlock(&sdev->stat_lock);
 495                 uncorrectable = 1;
 496                 goto out;
 497         }
 498
 499         trans = btrfs_join_transaction(fixup->root);
 500         if (IS_ERR(trans)) {
 501                 uncorrectable = 1;
 502                 goto out;
 503         }
 504
 505         /*
 506          * the idea is to trigger a regular read through the standard path. we
 507          * read a page from the (failed) logical address by specifying the
 508          * corresponding copynum of the failed sector. thus, that readpage is
 509          * expected to fail.
 510          * that is the point where on-the-fly error correction will kick in
 511          * (once it's finished) and rewrite the failed sector if a good copy
 512          * can be found.
 513          */
 514         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
 515                                                 path, scrub_fixup_readpage,
 516                                                 fixup);
 517         if (ret < 0) {
 518                 uncorrectable = 1;
 519                 goto out;
 520         }
 521         WARN_ON(ret != 1);
 522
 523         spin_lock(&sdev->stat_lock);
 524         ++sdev->stat.corrected_errors;
 525         spin_unlock(&sdev->stat_lock);
 526
 527 out:
 528         if (trans && !IS_ERR(trans))
 529                 btrfs_end_transaction(trans, fixup->root);
 530         if (uncorrectable) {
 531                 spin_lock(&sdev->stat_lock);
 532                 ++sdev->stat.uncorrectable_errors;
 533                 spin_unlock(&sdev->stat_lock);
 534                 printk_ratelimited(KERN_ERR "btrfs: unable to fixup "
 535                                         "(nodatasum) error at logical %llu\n",
 536                                         fixup->logical);
 537         }
 538
 539         btrfs_free_path(path);
 540         kfree(fixup);
 541
 542         /* see caller why we're pretending to be paused in the scrub counters */
 543         mutex_lock(&fs_info->scrub_lock);
 544         atomic_dec(&fs_info->scrubs_running);
 545         atomic_dec(&fs_info->scrubs_paused);
 546         mutex_unlock(&fs_info->scrub_lock);
 547         atomic_dec(&sdev->fixup_cnt);
 548         wake_up(&fs_info->scrub_pause_wait);
 549         wake_up(&sdev->list_wait);
 550 }
 551
 552 /*
 553  * scrub_recheck_error gets called when either verification of the page
 554  * failed or the bio failed to read, e.g. with EIO. In the latter case,
 555  * recheck_error gets called for every page in the bio, even though only
 556  * one may be bad
 557  */
 558 static int scrub_recheck_error(struct scrub_bio *sbio, int ix)
 559 {
 560         struct scrub_dev *sdev = sbio->sdev;
 561         u64 sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 562         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 563                                         DEFAULT_RATELIMIT_BURST);
 564
 565         if (sbio->err) {
 566                 if (scrub_fixup_io(READ, sbio->sdev->dev->bdev, sector,
 567                                    sbio->bio->bi_io_vec[ix].bv_page) == 0) {
 568                         if (scrub_fixup_check(sbio, ix) == 0)
 569                                 return 0;
 570                 }
 571                 if (__ratelimit(&_rs))
 572                         scrub_print_warning("i/o error", sbio, ix);
 573         } else {
 574                 if (__ratelimit(&_rs))
 575                         scrub_print_warning("checksum error", sbio, ix);
 576         }
 577
 578         spin_lock(&sdev->stat_lock);
 579         ++sdev->stat.read_errors;
 580         spin_unlock(&sdev->stat_lock);
 581
 582         scrub_fixup(sbio, ix);
 583         return 1;
 584 }
 585
 586 static int scrub_fixup_check(struct scrub_bio *sbio, int ix)
 587 {
 588         int ret = 1;
 589         struct page *page;
 590         void *buffer;
 591         u64 flags = sbio->spag[ix].flags;
 592
 593         page = sbio->bio->bi_io_vec[ix].bv_page;
 594         buffer = kmap_atomic(page, KM_USER0);
 595         if (flags & BTRFS_EXTENT_FLAG_DATA) {
 596                 ret = scrub_checksum_data(sbio->sdev,
 597                                           sbio->spag + ix, buffer);
 598         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 599                 ret = scrub_checksum_tree_block(sbio->sdev,
 600                                                 sbio->spag + ix,
 601                                                 sbio->logical + ix * PAGE_SIZE,
 602                                                 buffer);
 603         } else {
 604                 WARN_ON(1);
 605         }
 606         kunmap_atomic(buffer, KM_USER0);
 607
 608         return ret;
 609 }
 610
 611 static void scrub_fixup_end_io(struct bio *bio, int err)
 612 {
 613         complete((struct completion *)bio->bi_private);
 614 }
 615
 616 static void scrub_fixup(struct scrub_bio *sbio, int ix)
 617 {
 618         struct scrub_dev *sdev = sbio->sdev;
 619         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 620         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
 621         struct btrfs_bio *bbio = NULL;
 622         struct scrub_fixup_nodatasum *fixup;
 623         u64 logical = sbio->logical + ix * PAGE_SIZE;
 624         u64 length;
 625         int i;
 626         int ret;
 627         DECLARE_COMPLETION_ONSTACK(complete);
 628
 629         if ((sbio->spag[ix].flags & BTRFS_EXTENT_FLAG_DATA) &&
 630             (sbio->spag[ix].have_csum == 0)) {
 631                 fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
 632                 if (!fixup)
 633                         goto uncorrectable;
 634                 fixup->sdev = sdev;
 635                 fixup->logical = logical;
 636                 fixup->root = fs_info->extent_root;
 637                 fixup->mirror_num = sbio->spag[ix].mirror_num;
 638                 /*
 639                  * increment scrubs_running to prevent cancel requests from
 640                  * completing as long as a fixup worker is running. we must also
 641                  * increment scrubs_paused to prevent deadlocking on pause
 642                  * requests used for transactions commits (as the worker uses a
 643                  * transaction context). it is safe to regard the fixup worker
 644                  * as paused for all matters practical. effectively, we only
 645                  * avoid cancellation requests from completing.
 646                  */
 647                 mutex_lock(&fs_info->scrub_lock);
 648                 atomic_inc(&fs_info->scrubs_running);
 649                 atomic_inc(&fs_info->scrubs_paused);
 650                 mutex_unlock(&fs_info->scrub_lock);
 651                 atomic_inc(&sdev->fixup_cnt);
 652                 fixup->work.func = scrub_fixup_nodatasum;
 653                 btrfs_queue_worker(&fs_info->scrub_workers, &fixup->work);
 654                 return;
 655         }
 656
 657         length = PAGE_SIZE;
 658         ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length,
 659                               &bbio, 0);
 660         if (ret || !bbio || length < PAGE_SIZE) {
 661                 printk(KERN_ERR
 662                        "scrub_fixup: btrfs_map_block failed us for %llu\n",
 663                        (unsigned long long)logical);
 664                 WARN_ON(1);
 665                 kfree(bbio);
 666                 return;
 667         }
 668
 669         if (bbio->num_stripes == 1)
 670                 /* there aren't any replicas */
 671                 goto uncorrectable;
 672
 673         /*
 674          * first find a good copy
 675          */
 676         for (i = 0; i < bbio->num_stripes; ++i) {
 677                 if (i + 1 == sbio->spag[ix].mirror_num)
 678                         continue;
 679
 680                 if (scrub_fixup_io(READ, bbio->stripes[i].dev->bdev,
 681                                    bbio->stripes[i].physical >> 9,
 682                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 683                         /* I/O-error, this is not a good copy */
 684                         continue;
 685                 }
 686
 687                 if (scrub_fixup_check(sbio, ix) == 0)
 688                         break;
 689         }
 690         if (i == bbio->num_stripes)
 691                 goto uncorrectable;
 692
 693         if (!sdev->readonly) {
 694                 /*
 695                  * bi_io_vec[ix].bv_page now contains good data, write it back
 696                  */
 697                 if (scrub_fixup_io(WRITE, sdev->dev->bdev,
 698                                    (sbio->physical + ix * PAGE_SIZE) >> 9,
 699                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 700                         /* I/O-error, writeback failed, give up */
 701                         goto uncorrectable;
 702                 }
 703         }
 704
 705         kfree(bbio);
 706         spin_lock(&sdev->stat_lock);
 707         ++sdev->stat.corrected_errors;
 708         spin_unlock(&sdev->stat_lock);
 709
 710         printk_ratelimited(KERN_ERR "btrfs: fixed up error at logical %llu\n",
 711                                (unsigned long long)logical);
 712         return;
 713
 714 uncorrectable:
 715         kfree(bbio);
 716         spin_lock(&sdev->stat_lock);
 717         ++sdev->stat.uncorrectable_errors;
 718         spin_unlock(&sdev->stat_lock);
 719
 720         printk_ratelimited(KERN_ERR "btrfs: unable to fixup (regular) error at "
 721                                 "logical %llu\n", (unsigned long long)logical);
 722 }
 723
 724 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
 725                          struct page *page)
 726 {
 727         struct bio *bio = NULL;
 728         int ret;
 729         DECLARE_COMPLETION_ONSTACK(complete);
 730
 731         bio = bio_alloc(GFP_NOFS, 1);
 732         bio->bi_bdev = bdev;
 733         bio->bi_sector = sector;
 734         bio_add_page(bio, page, PAGE_SIZE, 0);
 735         bio->bi_end_io = scrub_fixup_end_io;
 736         bio->bi_private = &complete;
 737         btrfsic_submit_bio(rw, bio);
 738
 739         /* this will also unplug the queue */
 740         wait_for_completion(&complete);
 741
 742         ret = !test_bit(BIO_UPTODATE, &bio->bi_flags);
 743         bio_put(bio);
 744         return ret;
 745 }
 746
 747 static void scrub_bio_end_io(struct bio *bio, int err)
 748 {
 749         struct scrub_bio *sbio = bio->bi_private;
 750         struct scrub_dev *sdev = sbio->sdev;
 751         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 752
 753         sbio->err = err;
 754         sbio->bio = bio;
 755
 756         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
 757 }
 758
 759 static void scrub_checksum(struct btrfs_work *work)
 760 {
 761         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
 762         struct scrub_dev *sdev = sbio->sdev;
 763         struct page *page;
 764         void *buffer;
 765         int i;
 766         u64 flags;
 767         u64 logical;
 768         int ret;
 769
 770         if (sbio->err) {
 771                 ret = 0;
 772                 for (i = 0; i < sbio->count; ++i)
 773                         ret |= scrub_recheck_error(sbio, i);
 774                 if (!ret) {
 775                         spin_lock(&sdev->stat_lock);
 776                         ++sdev->stat.unverified_errors;
 777                         spin_unlock(&sdev->stat_lock);
 778                 }
 779
 780                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
 781                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
 782                 sbio->bio->bi_phys_segments = 0;
 783                 sbio->bio->bi_idx = 0;
 784
 785                 for (i = 0; i < sbio->count; i++) {
 786                         struct bio_vec *bi;
 787                         bi = &sbio->bio->bi_io_vec[i];
 788                         bi->bv_offset = 0;
 789                         bi->bv_len = PAGE_SIZE;
 790                 }
 791                 goto out;
 792         }
 793         for (i = 0; i < sbio->count; ++i) {
 794                 page = sbio->bio->bi_io_vec[i].bv_page;
 795                 buffer = kmap_atomic(page, KM_USER0);
 796                 flags = sbio->spag[i].flags;
 797                 logical = sbio->logical + i * PAGE_SIZE;
 798                 ret = 0;
 799                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
 800                         ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
 801                 } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 802                         ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
 803                                                         logical, buffer);
 804                 } else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
 805                         BUG_ON(i);
 806                         (void)scrub_checksum_super(sbio, buffer);
 807                 } else {
 808                         WARN_ON(1);
 809                 }
 810                 kunmap_atomic(buffer, KM_USER0);
 811                 if (ret) {
 812                         ret = scrub_recheck_error(sbio, i);
 813                         if (!ret) {
 814                                 spin_lock(&sdev->stat_lock);
 815                                 ++sdev->stat.unverified_errors;
 816                                 spin_unlock(&sdev->stat_lock);
 817                         }
 818                 }
 819         }
 820
 821 out:
 822         scrub_free_bio(sbio->bio);
 823         sbio->bio = NULL;
 824         spin_lock(&sdev->list_lock);
 825         sbio->next_free = sdev->first_free;
 826         sdev->first_free = sbio->index;
 827         spin_unlock(&sdev->list_lock);
 828         atomic_dec(&sdev->in_flight);
 829         wake_up(&sdev->list_wait);
 830 }
 831
 832 static int scrub_checksum_data(struct scrub_dev *sdev,
 833                                struct scrub_page *spag, void *buffer)
 834 {
 835         u8 csum[BTRFS_CSUM_SIZE];
 836         u32 crc = ~(u32)0;
 837         int fail = 0;
 838         struct btrfs_root *root = sdev->dev->dev_root;
 839
 840         if (!spag->have_csum)
 841                 return 0;
 842
 843         crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
 844         btrfs_csum_final(crc, csum);
 845         if (memcmp(csum, spag->csum, sdev->csum_size))
 846                 fail = 1;
 847
 848         spin_lock(&sdev->stat_lock);
 849         ++sdev->stat.data_extents_scrubbed;
 850         sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
 851         if (fail)
 852                 ++sdev->stat.csum_errors;
 853         spin_unlock(&sdev->stat_lock);
 854
 855         return fail;
 856 }
 857
 858 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
 859                                      struct scrub_page *spag, u64 logical,
 860                                      void *buffer)
 861 {
 862         struct btrfs_header *h;
 863         struct btrfs_root *root = sdev->dev->dev_root;
 864         struct btrfs_fs_info *fs_info = root->fs_info;
 865         u8 csum[BTRFS_CSUM_SIZE];
 866         u32 crc = ~(u32)0;
 867         int fail = 0;
 868         int crc_fail = 0;
 869
 870         /*
 871          * we don't use the getter functions here, as we
 872          * a) don't have an extent buffer and
 873          * b) the page is already kmapped
 874          */
 875         h = (struct btrfs_header *)buffer;
 876
 877         if (logical != le64_to_cpu(h->bytenr))
 878                 ++fail;
 879
 880         if (spag->generation != le64_to_cpu(h->generation))
 881                 ++fail;
 882
 883         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 884                 ++fail;
 885
 886         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
 887                    BTRFS_UUID_SIZE))
 888                 ++fail;
 889
 890         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 891                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 892         btrfs_csum_final(crc, csum);
 893         if (memcmp(csum, h->csum, sdev->csum_size))
 894                 ++crc_fail;
 895
 896         spin_lock(&sdev->stat_lock);
 897         ++sdev->stat.tree_extents_scrubbed;
 898         sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
 899         if (crc_fail)
 900                 ++sdev->stat.csum_errors;
 901         if (fail)
 902                 ++sdev->stat.verify_errors;
 903         spin_unlock(&sdev->stat_lock);
 904
 905         return fail || crc_fail;
 906 }
 907
 908 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
 909 {
 910         struct btrfs_super_block *s;
 911         u64 logical;
 912         struct scrub_dev *sdev = sbio->sdev;
 913         struct btrfs_root *root = sdev->dev->dev_root;
 914         struct btrfs_fs_info *fs_info = root->fs_info;
 915         u8 csum[BTRFS_CSUM_SIZE];
 916         u32 crc = ~(u32)0;
 917         int fail = 0;
 918
 919         s = (struct btrfs_super_block *)buffer;
 920         logical = sbio->logical;
 921
 922         if (logical != le64_to_cpu(s->bytenr))
 923                 ++fail;
 924
 925         if (sbio->spag[0].generation != le64_to_cpu(s->generation))
 926                 ++fail;
 927
 928         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 929                 ++fail;
 930
 931         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 932                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 933         btrfs_csum_final(crc, csum);
 934         if (memcmp(csum, s->csum, sbio->sdev->csum_size))
 935                 ++fail;
 936
 937         if (fail) {
 938                 /*
 939                  * if we find an error in a super block, we just report it.
 940                  * They will get written with the next transaction commit
 941                  * anyway
 942                  */
 943                 spin_lock(&sdev->stat_lock);
 944                 ++sdev->stat.super_errors;
 945                 spin_unlock(&sdev->stat_lock);
 946         }
 947
 948         return fail;
 949 }
 950
 951 static int scrub_submit(struct scrub_dev *sdev)
 952 {
 953         struct scrub_bio *sbio;
 954
 955         if (sdev->curr == -1)
 956                 return 0;
 957
 958         sbio = sdev->bios[sdev->curr];
 959         sbio->err = 0;
 960         sdev->curr = -1;
 961         atomic_inc(&sdev->in_flight);
 962
 963         btrfsic_submit_bio(READ, sbio->bio);
 964
 965         return 0;
 966 }
 967
 968 static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
 969                       u64 physical, u64 flags, u64 gen, int mirror_num,
 970                       u8 *csum, int force)
 971 {
 972         struct scrub_bio *sbio;
 973         struct page *page;
 974         int ret;
 975
 976 again:
 977         /*
 978          * grab a fresh bio or wait for one to become available
 979          */
 980         while (sdev->curr == -1) {
 981                 spin_lock(&sdev->list_lock);
 982                 sdev->curr = sdev->first_free;
 983                 if (sdev->curr != -1) {
 984                         sdev->first_free = sdev->bios[sdev->curr]->next_free;
 985                         sdev->bios[sdev->curr]->next_free = -1;
 986                         sdev->bios[sdev->curr]->count = 0;
 987                         spin_unlock(&sdev->list_lock);
 988                 } else {
 989                         spin_unlock(&sdev->list_lock);
 990                         wait_event(sdev->list_wait, sdev->first_free != -1);
 991                 }
 992         }
 993         sbio = sdev->bios[sdev->curr];
 994         if (sbio->count == 0) {
 995                 struct bio *bio;
 996
 997                 sbio->physical = physical;
 998                 sbio->logical = logical;
 999                 bio = bio_alloc(GFP_NOFS, SCRUB_PAGES_PER_BIO);
1000                 if (!bio)
1001                         return -ENOMEM;
1002
1003                 bio->bi_private = sbio;
1004                 bio->bi_end_io = scrub_bio_end_io;
1005                 bio->bi_bdev = sdev->dev->bdev;
1006                 bio->bi_sector = sbio->physical >> 9;
1007                 sbio->err = 0;
1008                 sbio->bio = bio;
1009         } else if (sbio->physical + sbio->count * PAGE_SIZE != physical ||
1010                    sbio->logical + sbio->count * PAGE_SIZE != logical) {
1011                 ret = scrub_submit(sdev);
1012                 if (ret)
1013                         return ret;
1014                 goto again;
1015         }
1016         sbio->spag[sbio->count].flags = flags;
1017         sbio->spag[sbio->count].generation = gen;
1018         sbio->spag[sbio->count].have_csum = 0;
1019         sbio->spag[sbio->count].mirror_num = mirror_num;
1020
1021         page = alloc_page(GFP_NOFS);
1022         if (!page)
1023                 return -ENOMEM;
1024
1025         ret = bio_add_page(sbio->bio, page, PAGE_SIZE, 0);
1026         if (!ret) {
1027                 __free_page(page);
1028                 ret = scrub_submit(sdev);
1029                 if (ret)
1030                         return ret;
1031                 goto again;
1032         }
1033
1034         if (csum) {
1035                 sbio->spag[sbio->count].have_csum = 1;
1036                 memcpy(sbio->spag[sbio->count].csum, csum, sdev->csum_size);
1037         }
1038         ++sbio->count;
1039         if (sbio->count == SCRUB_PAGES_PER_BIO || force) {
1040                 int ret;
1041
1042                 ret = scrub_submit(sdev);
1043                 if (ret)
1044                         return ret;
1045         }
1046
1047         return 0;
1048 }
1049
1050 static int scrub_find_csum(struct scrub_dev *sdev, u64 logical, u64 len,
1051                            u8 *csum)
1052 {
1053         struct btrfs_ordered_sum *sum = NULL;
1054         int ret = 0;
1055         unsigned long i;
1056         unsigned long num_sectors;
1057         u32 sectorsize = sdev->dev->dev_root->sectorsize;
1058
1059         while (!list_empty(&sdev->csum_list)) {
1060                 sum = list_first_entry(&sdev->csum_list,
1061                                        struct btrfs_ordered_sum, list);
1062                 if (sum->bytenr > logical)
1063                         return 0;
1064                 if (sum->bytenr + sum->len > logical)
1065                         break;
1066
1067                 ++sdev->stat.csum_discards;
1068                 list_del(&sum->list);
1069                 kfree(sum);
1070                 sum = NULL;
1071         }
1072         if (!sum)
1073                 return 0;
1074
1075         num_sectors = sum->len / sectorsize;
1076         for (i = 0; i < num_sectors; ++i) {
1077                 if (sum->sums[i].bytenr == logical) {
1078                         memcpy(csum, &sum->sums[i].sum, sdev->csum_size);
1079                         ret = 1;
1080                         break;
1081                 }
1082         }
1083         if (ret && i == num_sectors - 1) {
1084                 list_del(&sum->list);
1085                 kfree(sum);
1086         }
1087         return ret;
1088 }
1089
1090 /* scrub extent tries to collect up to 64 kB for each bio */
1091 static int scrub_extent(struct scrub_dev *sdev, u64 logical, u64 len,
1092                         u64 physical, u64 flags, u64 gen, int mirror_num)
1093 {
1094         int ret;
1095         u8 csum[BTRFS_CSUM_SIZE];
1096
1097         while (len) {
1098                 u64 l = min_t(u64, len, PAGE_SIZE);
1099                 int have_csum = 0;
1100
1101                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
1102                         /* push csums to sbio */
1103                         have_csum = scrub_find_csum(sdev, logical, l, csum);
1104                         if (have_csum == 0)
1105                                 ++sdev->stat.no_csum;
1106                 }
1107                 ret = scrub_page(sdev, logical, l, physical, flags, gen,
1108                                  mirror_num, have_csum ? csum : NULL, 0);
1109                 if (ret)
1110                         return ret;
1111                 len -= l;
1112                 logical += l;
1113                 physical += l;
1114         }
1115         return 0;
1116 }
1117
1118 static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
1119         struct map_lookup *map, int num, u64 base, u64 length)
1120 {
1121         struct btrfs_path *path;
1122         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
1123         struct btrfs_root *root = fs_info->extent_root;
1124         struct btrfs_root *csum_root = fs_info->csum_root;
1125         struct btrfs_extent_item *extent;
1126         struct blk_plug plug;
1127         u64 flags;
1128         int ret;
1129         int slot;
1130         int i;
1131         u64 nstripes;
1132         struct extent_buffer *l;
1133         struct btrfs_key key;
1134         u64 physical;
1135         u64 logical;
1136         u64 generation;
1137         int mirror_num;
1138         struct reada_control *reada1;
1139         struct reada_control *reada2;
1140         struct btrfs_key key_start;
1141         struct btrfs_key key_end;
1142
1143         u64 increment = map->stripe_len;
1144         u64 offset;
1145
1146         nstripes = length;
1147         offset = 0;
1148         do_div(nstripes, map->stripe_len);
1149         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
1150                 offset = map->stripe_len * num;
1151                 increment = map->stripe_len * map->num_stripes;
1152                 mirror_num = 1;
1153         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1154                 int factor = map->num_stripes / map->sub_stripes;
1155                 offset = map->stripe_len * (num / map->sub_stripes);
1156                 increment = map->stripe_len * factor;
1157                 mirror_num = num % map->sub_stripes + 1;
1158         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
1159                 increment = map->stripe_len;
1160                 mirror_num = num % map->num_stripes + 1;
1161         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
1162                 increment = map->stripe_len;
1163                 mirror_num = num % map->num_stripes + 1;
1164         } else {
1165                 increment = map->stripe_len;
1166                 mirror_num = 1;
1167         }
1168
1169         path = btrfs_alloc_path();
1170         if (!path)
1171                 return -ENOMEM;
1172
1173         path->search_commit_root = 1;
1174         path->skip_locking = 1;
1175
1176         /*
1177          * trigger the readahead for extent tree csum tree and wait for
1178          * completion. During readahead, the scrub is officially paused
1179          * to not hold off transaction commits
1180          */
1181         logical = base + offset;
1182
1183         wait_event(sdev->list_wait,
1184                    atomic_read(&sdev->in_flight) == 0);
1185         atomic_inc(&fs_info->scrubs_paused);
1186         wake_up(&fs_info->scrub_pause_wait);
1187
1188         /* FIXME it might be better to start readahead at commit root */
1189         key_start.objectid = logical;
1190         key_start.type = BTRFS_EXTENT_ITEM_KEY;
1191         key_start.offset = (u64)0;
1192         key_end.objectid = base + offset + nstripes * increment;
1193         key_end.type = BTRFS_EXTENT_ITEM_KEY;
1194         key_end.offset = (u64)0;
1195         reada1 = btrfs_reada_add(root, &key_start, &key_end);
1196
1197         key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1198         key_start.type = BTRFS_EXTENT_CSUM_KEY;
1199         key_start.offset = logical;
1200         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1201         key_end.type = BTRFS_EXTENT_CSUM_KEY;
1202         key_end.offset = base + offset + nstripes * increment;
1203         reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);
1204
1205         if (!IS_ERR(reada1))
1206                 btrfs_reada_wait(reada1);
1207         if (!IS_ERR(reada2))
1208                 btrfs_reada_wait(reada2);
1209
1210         mutex_lock(&fs_info->scrub_lock);
1211         while (atomic_read(&fs_info->scrub_pause_req)) {
1212                 mutex_unlock(&fs_info->scrub_lock);
1213                 wait_event(fs_info->scrub_pause_wait,
1214                    atomic_read(&fs_info->scrub_pause_req) == 0);
1215                 mutex_lock(&fs_info->scrub_lock);
1216         }
1217         atomic_dec(&fs_info->scrubs_paused);
1218         mutex_unlock(&fs_info->scrub_lock);
1219         wake_up(&fs_info->scrub_pause_wait);
1220
1221         /*
1222          * collect all data csums for the stripe to avoid seeking during
1223          * the scrub. This might currently (crc32) end up to be about 1MB
1224          */
1225         blk_start_plug(&plug);
1226
1227         /*
1228          * now find all extents for each stripe and scrub them
1229          */
1230         logical = base + offset;
1231         physical = map->stripes[num].physical;
1232         ret = 0;
1233         for (i = 0; i < nstripes; ++i) {
1234                 /*
1235                  * canceled?
1236                  */
1237                 if (atomic_read(&fs_info->scrub_cancel_req) ||
1238                     atomic_read(&sdev->cancel_req)) {
1239                         ret = -ECANCELED;
1240                         goto out;
1241                 }
1242                 /*
1243                  * check to see if we have to pause
1244                  */
1245                 if (atomic_read(&fs_info->scrub_pause_req)) {
1246                         /* push queued extents */
1247                         scrub_submit(sdev);
1248                         wait_event(sdev->list_wait,
1249                                    atomic_read(&sdev->in_flight) == 0);
1250                         atomic_inc(&fs_info->scrubs_paused);
1251                         wake_up(&fs_info->scrub_pause_wait);
1252                         mutex_lock(&fs_info->scrub_lock);
1253                         while (atomic_read(&fs_info->scrub_pause_req)) {
1254                                 mutex_unlock(&fs_info->scrub_lock);
1255                                 wait_event(fs_info->scrub_pause_wait,
1256                                    atomic_read(&fs_info->scrub_pause_req) == 0);
1257                                 mutex_lock(&fs_info->scrub_lock);
1258                         }
1259                         atomic_dec(&fs_info->scrubs_paused);
1260                         mutex_unlock(&fs_info->scrub_lock);
1261                         wake_up(&fs_info->scrub_pause_wait);
1262                 }
1263
1264                 ret = btrfs_lookup_csums_range(csum_root, logical,
1265                                                logical + map->stripe_len - 1,
1266                                                &sdev->csum_list, 1);
1267                 if (ret)
1268                         goto out;
1269
1270                 key.objectid = logical;
1271                 key.type = BTRFS_EXTENT_ITEM_KEY;
1272                 key.offset = (u64)0;
1273
1274                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1275                 if (ret < 0)
1276                         goto out;
1277                 if (ret > 0) {
1278                         ret = btrfs_previous_item(root, path, 0,
1279                                                   BTRFS_EXTENT_ITEM_KEY);
1280                         if (ret < 0)
1281                                 goto out;
1282                         if (ret > 0) {
1283                                 /* there's no smaller item, so stick with the
1284                                  * larger one */
1285                                 btrfs_release_path(path);
1286                                 ret = btrfs_search_slot(NULL, root, &key,
1287                                                         path, 0, 0);
1288                                 if (ret < 0)
1289                                         goto out;
1290                         }
1291                 }
1292
1293                 while (1) {
1294                         l = path->nodes[0];
1295                         slot = path->slots[0];
1296                         if (slot >= btrfs_header_nritems(l)) {
1297                                 ret = btrfs_next_leaf(root, path);
1298                                 if (ret == 0)
1299                                         continue;
1300                                 if (ret < 0)
1301                                         goto out;
1302
1303                                 break;
1304                         }
1305                         btrfs_item_key_to_cpu(l, &key, slot);
1306
1307                         if (key.objectid + key.offset <= logical)
1308                                 goto next;
1309
1310                         if (key.objectid >= logical + map->stripe_len)
1311                                 break;
1312
1313                         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
1314                                 goto next;
1315
1316                         extent = btrfs_item_ptr(l, slot,
1317                                                 struct btrfs_extent_item);
1318                         flags = btrfs_extent_flags(l, extent);
1319                         generation = btrfs_extent_generation(l, extent);
1320
1321                         if (key.objectid < logical &&
1322                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
1323                                 printk(KERN_ERR
1324                                        "btrfs scrub: tree block %llu spanning "
1325                                        "stripes, ignored. logical=%llu\n",
1326                                        (unsigned long long)key.objectid,
1327                                        (unsigned long long)logical);
1328                                 goto next;
1329                         }
1330
1331                         /*
1332                          * trim extent to this stripe
1333                          */
1334                         if (key.objectid < logical) {
1335                                 key.offset -= logical - key.objectid;
1336                                 key.objectid = logical;
1337                         }
1338                         if (key.objectid + key.offset >
1339                             logical + map->stripe_len) {
1340                                 key.offset = logical + map->stripe_len -
1341                                              key.objectid;
1342                         }
1343
1344                         ret = scrub_extent(sdev, key.objectid, key.offset,
1345                                            key.objectid - logical + physical,
1346                                            flags, generation, mirror_num);
1347                         if (ret)
1348                                 goto out;
1349
1350 next:
1351                         path->slots[0]++;
1352                 }
1353                 btrfs_release_path(path);
1354                 logical += increment;
1355                 physical += map->stripe_len;
1356                 spin_lock(&sdev->stat_lock);
1357                 sdev->stat.last_physical = physical;
1358                 spin_unlock(&sdev->stat_lock);
1359         }
1360         /* push queued extents */
1361         scrub_submit(sdev);
1362
1363 out:
1364         blk_finish_plug(&plug);
1365         btrfs_free_path(path);
1366         return ret < 0 ? ret : 0;
1367 }
1368
1369 static noinline_for_stack int scrub_chunk(struct scrub_dev *sdev,
1370         u64 chunk_tree, u64 chunk_objectid, u64 chunk_offset, u64 length)
1371 {
1372         struct btrfs_mapping_tree *map_tree =
1373                 &sdev->dev->dev_root->fs_info->mapping_tree;
1374         struct map_lookup *map;
1375         struct extent_map *em;
1376         int i;
1377         int ret = -EINVAL;
1378
1379         read_lock(&map_tree->map_tree.lock);
1380         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
1381         read_unlock(&map_tree->map_tree.lock);
1382
1383         if (!em)
1384                 return -EINVAL;
1385
1386         map = (struct map_lookup *)em->bdev;
1387         if (em->start != chunk_offset)
1388                 goto out;
1389
1390         if (em->len < length)
1391                 goto out;
1392
1393         for (i = 0; i < map->num_stripes; ++i) {
1394                 if (map->stripes[i].dev == sdev->dev) {
1395                         ret = scrub_stripe(sdev, map, i, chunk_offset, length);
1396                         if (ret)
1397                                 goto out;
1398                 }
1399         }
1400 out:
1401         free_extent_map(em);
1402
1403         return ret;
1404 }
1405
1406 static noinline_for_stack
1407 int scrub_enumerate_chunks(struct scrub_dev *sdev, u64 start, u64 end)
1408 {
1409         struct btrfs_dev_extent *dev_extent = NULL;
1410         struct btrfs_path *path;
1411         struct btrfs_root *root = sdev->dev->dev_root;
1412         struct btrfs_fs_info *fs_info = root->fs_info;
1413         u64 length;
1414         u64 chunk_tree;
1415         u64 chunk_objectid;
1416         u64 chunk_offset;
1417         int ret;
1418         int slot;
1419         struct extent_buffer *l;
1420         struct btrfs_key key;
1421         struct btrfs_key found_key;
1422         struct btrfs_block_group_cache *cache;
1423
1424         path = btrfs_alloc_path();
1425         if (!path)
1426                 return -ENOMEM;
1427
1428         path->reada = 2;
1429         path->search_commit_root = 1;
1430         path->skip_locking = 1;
1431
1432         key.objectid = sdev->dev->devid;
1433         key.offset = 0ull;
1434         key.type = BTRFS_DEV_EXTENT_KEY;
1435
1436
1437         while (1) {
1438                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1439                 if (ret < 0)
1440                         break;
1441                 if (ret > 0) {
1442                         if (path->slots[0] >=
1443                             btrfs_header_nritems(path->nodes[0])) {
1444                                 ret = btrfs_next_leaf(root, path);
1445                                 if (ret)
1446                                         break;
1447                         }
1448                 }
1449
1450                 l = path->nodes[0];
1451                 slot = path->slots[0];
1452
1453                 btrfs_item_key_to_cpu(l, &found_key, slot);
1454
1455                 if (found_key.objectid != sdev->dev->devid)
1456                         break;
1457
1458                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
1459                         break;
1460
1461                 if (found_key.offset >= end)
1462                         break;
1463
1464                 if (found_key.offset < key.offset)
1465                         break;
1466
1467                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
1468                 length = btrfs_dev_extent_length(l, dev_extent);
1469
1470                 if (found_key.offset + length <= start) {
1471                         key.offset = found_key.offset + length;
1472                         btrfs_release_path(path);
1473                         continue;
1474                 }
1475
1476                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
1477                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
1478                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
1479
1480                 /*
1481                  * get a reference on the corresponding block group to prevent
1482                  * the chunk from going away while we scrub it
1483                  */
1484                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
1485                 if (!cache) {
1486                         ret = -ENOENT;
1487                         break;
1488                 }
1489                 ret = scrub_chunk(sdev, chunk_tree, chunk_objectid,
1490                                   chunk_offset, length);
1491                 btrfs_put_block_group(cache);
1492                 if (ret)
1493                         break;
1494
1495                 key.offset = found_key.offset + length;
1496                 btrfs_release_path(path);
1497         }
1498
1499         btrfs_free_path(path);
1500
1501         /*
1502          * ret can still be 1 from search_slot or next_leaf,
1503          * that's not an error
1504          */
1505         return ret < 0 ? ret : 0;
1506 }
1507
1508 static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
1509 {
1510         int     i;
1511         u64     bytenr;
1512         u64     gen;
1513         int     ret;
1514         struct btrfs_device *device = sdev->dev;
1515         struct btrfs_root *root = device->dev_root;
1516
1517         gen = root->fs_info->last_trans_committed;
1518
1519         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
1520                 bytenr = btrfs_sb_offset(i);
1521                 if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
1522                         break;
1523
1524                 ret = scrub_page(sdev, bytenr, PAGE_SIZE, bytenr,
1525                                  BTRFS_EXTENT_FLAG_SUPER, gen, i, NULL, 1);
1526                 if (ret)
1527                         return ret;
1528         }
1529         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1530
1531         return 0;
1532 }
1533
1534 /*
1535  * get a reference count on fs_info->scrub_workers. start worker if necessary
1536  */
1537 static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
1538 {
1539         struct btrfs_fs_info *fs_info = root->fs_info;
1540         int ret = 0;
1541
1542         mutex_lock(&fs_info->scrub_lock);
1543         if (fs_info->scrub_workers_refcnt == 0) {
1544                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
1545                            fs_info->thread_pool_size, &fs_info->generic_worker);
1546                 fs_info->scrub_workers.idle_thresh = 4;
1547                 ret = btrfs_start_workers(&fs_info->scrub_workers);
1548                 if (ret)
1549                         goto out;
1550         }
1551         ++fs_info->scrub_workers_refcnt;
1552 out:
1553         mutex_unlock(&fs_info->scrub_lock);
1554
1555         return ret;
1556 }
1557
1558 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
1559 {
1560         struct btrfs_fs_info *fs_info = root->fs_info;
1561
1562         mutex_lock(&fs_info->scrub_lock);
1563         if (--fs_info->scrub_workers_refcnt == 0)
1564                 btrfs_stop_workers(&fs_info->scrub_workers);
1565         WARN_ON(fs_info->scrub_workers_refcnt < 0);
1566         mutex_unlock(&fs_info->scrub_lock);
1567 }
1568
1569
1570 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
1571                     struct btrfs_scrub_progress *progress, int readonly)
1572 {
1573         struct scrub_dev *sdev;
1574         struct btrfs_fs_info *fs_info = root->fs_info;
1575         int ret;
1576         struct btrfs_device *dev;
1577
1578         if (btrfs_fs_closing(root->fs_info))
1579                 return -EINVAL;
1580
1581         /*
1582          * check some assumptions
1583          */
1584         if (root->sectorsize != PAGE_SIZE ||
1585             root->sectorsize != root->leafsize ||
1586             root->sectorsize != root->nodesize) {
1587                 printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
1588                 return -EINVAL;
1589         }
1590
1591         ret = scrub_workers_get(root);
1592         if (ret)
1593                 return ret;
1594
1595         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1596         dev = btrfs_find_device(root, devid, NULL, NULL);
1597         if (!dev || dev->missing) {
1598                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1599                 scrub_workers_put(root);
1600                 return -ENODEV;
1601         }
1602         mutex_lock(&fs_info->scrub_lock);
1603
1604         if (!dev->in_fs_metadata) {
1605                 mutex_unlock(&fs_info->scrub_lock);
1606                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1607                 scrub_workers_put(root);
1608                 return -ENODEV;
1609         }
1610
1611         if (dev->scrub_device) {
1612                 mutex_unlock(&fs_info->scrub_lock);
1613                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1614                 scrub_workers_put(root);
1615                 return -EINPROGRESS;
1616         }
1617         sdev = scrub_setup_dev(dev);
1618         if (IS_ERR(sdev)) {
1619                 mutex_unlock(&fs_info->scrub_lock);
1620                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1621                 scrub_workers_put(root);
1622                 return PTR_ERR(sdev);
1623         }
1624         sdev->readonly = readonly;
1625         dev->scrub_device = sdev;
1626
1627         atomic_inc(&fs_info->scrubs_running);
1628         mutex_unlock(&fs_info->scrub_lock);
1629         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1630
1631         down_read(&fs_info->scrub_super_lock);
1632         ret = scrub_supers(sdev);
1633         up_read(&fs_info->scrub_super_lock);
1634
1635         if (!ret)
1636                 ret = scrub_enumerate_chunks(sdev, start, end);
1637
1638         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1639         atomic_dec(&fs_info->scrubs_running);
1640         wake_up(&fs_info->scrub_pause_wait);
1641
1642         wait_event(sdev->list_wait, atomic_read(&sdev->fixup_cnt) == 0);
1643
1644         if (progress)
1645                 memcpy(progress, &sdev->stat, sizeof(*progress));
1646
1647         mutex_lock(&fs_info->scrub_lock);
1648         dev->scrub_device = NULL;
1649         mutex_unlock(&fs_info->scrub_lock);
1650
1651         scrub_free_dev(sdev);
1652         scrub_workers_put(root);
1653
1654         return ret;
1655 }
1656
1657 int btrfs_scrub_pause(struct btrfs_root *root)
1658 {
1659         struct btrfs_fs_info *fs_info = root->fs_info;
1660
1661         mutex_lock(&fs_info->scrub_lock);
1662         atomic_inc(&fs_info->scrub_pause_req);
1663         while (atomic_read(&fs_info->scrubs_paused) !=
1664                atomic_read(&fs_info->scrubs_running)) {
1665                 mutex_unlock(&fs_info->scrub_lock);
1666                 wait_event(fs_info->scrub_pause_wait,
1667                            atomic_read(&fs_info->scrubs_paused) ==
1668                            atomic_read(&fs_info->scrubs_running));
1669                 mutex_lock(&fs_info->scrub_lock);
1670         }
1671         mutex_unlock(&fs_info->scrub_lock);
1672
1673         return 0;
1674 }
1675
1676 int btrfs_scrub_continue(struct btrfs_root *root)
1677 {
1678         struct btrfs_fs_info *fs_info = root->fs_info;
1679
1680         atomic_dec(&fs_info->scrub_pause_req);
1681         wake_up(&fs_info->scrub_pause_wait);
1682         return 0;
1683 }
1684
1685 int btrfs_scrub_pause_super(struct btrfs_root *root)
1686 {
1687         down_write(&root->fs_info->scrub_super_lock);
1688         return 0;
1689 }
1690
1691 int btrfs_scrub_continue_super(struct btrfs_root *root)
1692 {
1693         up_write(&root->fs_info->scrub_super_lock);
1694         return 0;
1695 }
1696
1697 int btrfs_scrub_cancel(struct btrfs_root *root)
1698 {
1699         struct btrfs_fs_info *fs_info = root->fs_info;
1700
1701         mutex_lock(&fs_info->scrub_lock);
1702         if (!atomic_read(&fs_info->scrubs_running)) {
1703                 mutex_unlock(&fs_info->scrub_lock);
1704                 return -ENOTCONN;
1705         }
1706
1707         atomic_inc(&fs_info->scrub_cancel_req);
1708         while (atomic_read(&fs_info->scrubs_running)) {
1709                 mutex_unlock(&fs_info->scrub_lock);
1710                 wait_event(fs_info->scrub_pause_wait,
1711                            atomic_read(&fs_info->scrubs_running) == 0);
1712                 mutex_lock(&fs_info->scrub_lock);
1713         }
1714         atomic_dec(&fs_info->scrub_cancel_req);
1715         mutex_unlock(&fs_info->scrub_lock);
1716
1717         return 0;
1718 }
1719
1720 int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
1721 {
1722         struct btrfs_fs_info *fs_info = root->fs_info;
1723         struct scrub_dev *sdev;
1724
1725         mutex_lock(&fs_info->scrub_lock);
1726         sdev = dev->scrub_device;
1727         if (!sdev) {
1728                 mutex_unlock(&fs_info->scrub_lock);
1729                 return -ENOTCONN;
1730         }
1731         atomic_inc(&sdev->cancel_req);
1732         while (dev->scrub_device) {
1733                 mutex_unlock(&fs_info->scrub_lock);
1734                 wait_event(fs_info->scrub_pause_wait,
1735                            dev->scrub_device == NULL);
1736                 mutex_lock(&fs_info->scrub_lock);
1737         }
1738         mutex_unlock(&fs_info->scrub_lock);
1739
1740         return 0;
1741 }
1742 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
1743 {
1744         struct btrfs_fs_info *fs_info = root->fs_info;
1745         struct btrfs_device *dev;
1746         int ret;
1747
1748         /*
1749          * we have to hold the device_list_mutex here so the device
1750          * does not go away in cancel_dev. FIXME: find a better solution
1751          */
1752         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1753         dev = btrfs_find_device(root, devid, NULL, NULL);
1754         if (!dev) {
1755                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1756                 return -ENODEV;
1757         }
1758         ret = btrfs_scrub_cancel_dev(root, dev);
1759         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1760
1761         return ret;
1762 }
1763
1764 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
1765                          struct btrfs_scrub_progress *progress)
1766 {
1767         struct btrfs_device *dev;
1768         struct scrub_dev *sdev = NULL;
1769
1770         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1771         dev = btrfs_find_device(root, devid, NULL, NULL);
1772         if (dev)
1773                 sdev = dev->scrub_device;
1774         if (sdev)
1775                 memcpy(progress, &sdev->stat, sizeof(*progress));
1776         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1777
1778         return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
1779 }