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 "ctree.h"
  21 #include "volumes.h"
  22 #include "disk-io.h"
  23 #include "ordered-data.h"
  24
  25 /*
  26  * This is only the first step towards a full-features scrub. It reads all
  27  * extent and super block and verifies the checksums. In case a bad checksum
  28  * is found or the extent cannot be read, good data will be written back if
  29  * any can be found.
  30  *
  31  * Future enhancements:
  32  *  - To enhance the performance, better read-ahead strategies for the
  33  *    extent-tree can be employed.
  34  *  - In case an unrepairable extent is encountered, track which files are
  35  *    affected and report them
  36  *  - In case of a read error on files with nodatasum, map the file and read
  37  *    the extent to trigger a writeback of the good copy
  38  *  - track and record media errors, throw out bad devices
  39  *  - add a mode to also read unallocated space
  40  *  - make the prefetch cancellable
  41  */
  42
  43 struct scrub_bio;
  44 struct scrub_page;
  45 struct scrub_dev;
  46 static void scrub_bio_end_io(struct bio *bio, int err);
  47 static void scrub_checksum(struct btrfs_work *work);
  48 static int scrub_checksum_data(struct scrub_dev *sdev,
  49                                struct scrub_page *spag, void *buffer);
  50 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
  51                                      struct scrub_page *spag, u64 logical,
  52                                      void *buffer);
  53 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer);
  54 static int scrub_fixup_check(struct scrub_bio *sbio, int ix);
  55 static void scrub_fixup_end_io(struct bio *bio, int err);
  56 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
  57                           struct page *page);
  58 static void scrub_fixup(struct scrub_bio *sbio, int ix);
  59
  60 #define SCRUB_PAGES_PER_BIO     16      /* 64k per bio */
  61 #define SCRUB_BIOS_PER_DEV      16      /* 1 MB per device in flight */
  62
  63 struct scrub_page {
  64         u64                     flags;  /* extent flags */
  65         u64                     generation;
  66         u64                     mirror_num;
  67         int                     have_csum;
  68         u8                      csum[BTRFS_CSUM_SIZE];
  69 };
  70
  71 struct scrub_bio {
  72         int                     index;
  73         struct scrub_dev        *sdev;
  74         struct bio              *bio;
  75         int                     err;
  76         u64                     logical;
  77         u64                     physical;
  78         struct scrub_page       spag[SCRUB_PAGES_PER_BIO];
  79         u64                     count;
  80         int                     next_free;
  81         struct btrfs_work       work;
  82 };
  83
  84 struct scrub_dev {
  85         struct scrub_bio        *bios[SCRUB_BIOS_PER_DEV];
  86         struct btrfs_device     *dev;
  87         int                     first_free;
  88         int                     curr;
  89         atomic_t                in_flight;
  90         spinlock_t              list_lock;
  91         wait_queue_head_t       list_wait;
  92         u16                     csum_size;
  93         struct list_head        csum_list;
  94         atomic_t                cancel_req;
  95         int                     readonly;
  96         /*
  97          * statistics
  98          */
  99         struct btrfs_scrub_progress stat;
 100         spinlock_t              stat_lock;
 101 };
 102
 103 static void scrub_free_csums(struct scrub_dev *sdev)
 104 {
 105         while (!list_empty(&sdev->csum_list)) {
 106                 struct btrfs_ordered_sum *sum;
 107                 sum = list_first_entry(&sdev->csum_list,
 108                                        struct btrfs_ordered_sum, list);
 109                 list_del(&sum->list);
 110                 kfree(sum);
 111         }
 112 }
 113
 114 static void scrub_free_bio(struct bio *bio)
 115 {
 116         int i;
 117         struct page *last_page = NULL;
 118
 119         if (!bio)
 120                 return;
 121
 122         for (i = 0; i < bio->bi_vcnt; ++i) {
 123                 if (bio->bi_io_vec[i].bv_page == last_page)
 124                         continue;
 125                 last_page = bio->bi_io_vec[i].bv_page;
 126                 __free_page(last_page);
 127         }
 128         bio_put(bio);
 129 }
 130
 131 static noinline_for_stack void scrub_free_dev(struct scrub_dev *sdev)
 132 {
 133         int i;
 134
 135         if (!sdev)
 136                 return;
 137
 138         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
 139                 struct scrub_bio *sbio = sdev->bios[i];
 140
 141                 if (!sbio)
 142                         break;
 143
 144                 scrub_free_bio(sbio->bio);
 145                 kfree(sbio);
 146         }
 147
 148         scrub_free_csums(sdev);
 149         kfree(sdev);
 150 }
 151
 152 static noinline_for_stack
 153 struct scrub_dev *scrub_setup_dev(struct btrfs_device *dev)
 154 {
 155         struct scrub_dev *sdev;
 156         int             i;
 157         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 158
 159         sdev = kzalloc(sizeof(*sdev), GFP_NOFS);
 160         if (!sdev)
 161                 goto nomem;
 162         sdev->dev = dev;
 163         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
 164                 struct scrub_bio *sbio;
 165
 166                 sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
 167                 if (!sbio)
 168                         goto nomem;
 169                 sdev->bios[i] = sbio;
 170
 171                 sbio->index = i;
 172                 sbio->sdev = sdev;
 173                 sbio->count = 0;
 174                 sbio->work.func = scrub_checksum;
 175
 176                 if (i != SCRUB_BIOS_PER_DEV-1)
 177                         sdev->bios[i]->next_free = i + 1;
 178                  else
 179                         sdev->bios[i]->next_free = -1;
 180         }
 181         sdev->first_free = 0;
 182         sdev->curr = -1;
 183         atomic_set(&sdev->in_flight, 0);
 184         atomic_set(&sdev->cancel_req, 0);
 185         sdev->csum_size = btrfs_super_csum_size(&fs_info->super_copy);
 186         INIT_LIST_HEAD(&sdev->csum_list);
 187
 188         spin_lock_init(&sdev->list_lock);
 189         spin_lock_init(&sdev->stat_lock);
 190         init_waitqueue_head(&sdev->list_wait);
 191         return sdev;
 192
 193 nomem:
 194         scrub_free_dev(sdev);
 195         return ERR_PTR(-ENOMEM);
 196 }
 197
 198 /*
 199  * scrub_recheck_error gets called when either verification of the page
 200  * failed or the bio failed to read, e.g. with EIO. In the latter case,
 201  * recheck_error gets called for every page in the bio, even though only
 202  * one may be bad
 203  */
 204 static int scrub_recheck_error(struct scrub_bio *sbio, int ix)
 205 {
 206         struct scrub_dev *sdev = sbio->sdev;
 207         u64 sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
 208
 209         if (sbio->err) {
 210                 if (scrub_fixup_io(READ, sbio->sdev->dev->bdev, sector,
 211                                    sbio->bio->bi_io_vec[ix].bv_page) == 0) {
 212                         if (scrub_fixup_check(sbio, ix) == 0)
 213                                 return 0;
 214                 }
 215         }
 216
 217         spin_lock(&sdev->stat_lock);
 218         ++sdev->stat.read_errors;
 219         spin_unlock(&sdev->stat_lock);
 220
 221         scrub_fixup(sbio, ix);
 222         return 1;
 223 }
 224
 225 static int scrub_fixup_check(struct scrub_bio *sbio, int ix)
 226 {
 227         int ret = 1;
 228         struct page *page;
 229         void *buffer;
 230         u64 flags = sbio->spag[ix].flags;
 231
 232         page = sbio->bio->bi_io_vec[ix].bv_page;
 233         buffer = kmap_atomic(page, KM_USER0);
 234         if (flags & BTRFS_EXTENT_FLAG_DATA) {
 235                 ret = scrub_checksum_data(sbio->sdev,
 236                                           sbio->spag + ix, buffer);
 237         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 238                 ret = scrub_checksum_tree_block(sbio->sdev,
 239                                                 sbio->spag + ix,
 240                                                 sbio->logical + ix * PAGE_SIZE,
 241                                                 buffer);
 242         } else {
 243                 WARN_ON(1);
 244         }
 245         kunmap_atomic(buffer, KM_USER0);
 246
 247         return ret;
 248 }
 249
 250 static void scrub_fixup_end_io(struct bio *bio, int err)
 251 {
 252         complete((struct completion *)bio->bi_private);
 253 }
 254
 255 static void scrub_fixup(struct scrub_bio *sbio, int ix)
 256 {
 257         struct scrub_dev *sdev = sbio->sdev;
 258         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 259         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
 260         struct btrfs_multi_bio *multi = NULL;
 261         u64 logical = sbio->logical + ix * PAGE_SIZE;
 262         u64 length;
 263         int i;
 264         int ret;
 265         DECLARE_COMPLETION_ONSTACK(complete);
 266
 267         if ((sbio->spag[ix].flags & BTRFS_EXTENT_FLAG_DATA) &&
 268             (sbio->spag[ix].have_csum == 0)) {
 269                 /*
 270                  * nodatasum, don't try to fix anything
 271                  * FIXME: we can do better, open the inode and trigger a
 272                  * writeback
 273                  */
 274                 goto uncorrectable;
 275         }
 276
 277         length = PAGE_SIZE;
 278         ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length,
 279                               &multi, 0);
 280         if (ret || !multi || length < PAGE_SIZE) {
 281                 printk(KERN_ERR
 282                        "scrub_fixup: btrfs_map_block failed us for %llu\n",
 283                        (unsigned long long)logical);
 284                 WARN_ON(1);
 285                 return;
 286         }
 287
 288         if (multi->num_stripes == 1)
 289                 /* there aren't any replicas */
 290                 goto uncorrectable;
 291
 292         /*
 293          * first find a good copy
 294          */
 295         for (i = 0; i < multi->num_stripes; ++i) {
 296                 if (i == sbio->spag[ix].mirror_num)
 297                         continue;
 298
 299                 if (scrub_fixup_io(READ, multi->stripes[i].dev->bdev,
 300                                    multi->stripes[i].physical >> 9,
 301                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 302                         /* I/O-error, this is not a good copy */
 303                         continue;
 304                 }
 305
 306                 if (scrub_fixup_check(sbio, ix) == 0)
 307                         break;
 308         }
 309         if (i == multi->num_stripes)
 310                 goto uncorrectable;
 311
 312         if (!sdev->readonly) {
 313                 /*
 314                  * bi_io_vec[ix].bv_page now contains good data, write it back
 315                  */
 316                 if (scrub_fixup_io(WRITE, sdev->dev->bdev,
 317                                    (sbio->physical + ix * PAGE_SIZE) >> 9,
 318                                    sbio->bio->bi_io_vec[ix].bv_page)) {
 319                         /* I/O-error, writeback failed, give up */
 320                         goto uncorrectable;
 321                 }
 322         }
 323
 324         kfree(multi);
 325         spin_lock(&sdev->stat_lock);
 326         ++sdev->stat.corrected_errors;
 327         spin_unlock(&sdev->stat_lock);
 328
 329         if (printk_ratelimit())
 330                 printk(KERN_ERR "btrfs: fixed up at %llu\n",
 331                        (unsigned long long)logical);
 332         return;
 333
 334 uncorrectable:
 335         kfree(multi);
 336         spin_lock(&sdev->stat_lock);
 337         ++sdev->stat.uncorrectable_errors;
 338         spin_unlock(&sdev->stat_lock);
 339
 340         if (printk_ratelimit())
 341                 printk(KERN_ERR "btrfs: unable to fixup at %llu\n",
 342                          (unsigned long long)logical);
 343 }
 344
 345 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
 346                          struct page *page)
 347 {
 348         struct bio *bio = NULL;
 349         int ret;
 350         DECLARE_COMPLETION_ONSTACK(complete);
 351
 352         bio = bio_alloc(GFP_NOFS, 1);
 353         bio->bi_bdev = bdev;
 354         bio->bi_sector = sector;
 355         bio_add_page(bio, page, PAGE_SIZE, 0);
 356         bio->bi_end_io = scrub_fixup_end_io;
 357         bio->bi_private = &complete;
 358         submit_bio(rw, bio);
 359
 360         /* this will also unplug the queue */
 361         wait_for_completion(&complete);
 362
 363         ret = !test_bit(BIO_UPTODATE, &bio->bi_flags);
 364         bio_put(bio);
 365         return ret;
 366 }
 367
 368 static void scrub_bio_end_io(struct bio *bio, int err)
 369 {
 370         struct scrub_bio *sbio = bio->bi_private;
 371         struct scrub_dev *sdev = sbio->sdev;
 372         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 373
 374         sbio->err = err;
 375         sbio->bio = bio;
 376
 377         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
 378 }
 379
 380 static void scrub_checksum(struct btrfs_work *work)
 381 {
 382         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
 383         struct scrub_dev *sdev = sbio->sdev;
 384         struct page *page;
 385         void *buffer;
 386         int i;
 387         u64 flags;
 388         u64 logical;
 389         int ret;
 390
 391         if (sbio->err) {
 392                 ret = 0;
 393                 for (i = 0; i < sbio->count; ++i)
 394                         ret |= scrub_recheck_error(sbio, i);
 395                 if (!ret) {
 396                         spin_lock(&sdev->stat_lock);
 397                         ++sdev->stat.unverified_errors;
 398                         spin_unlock(&sdev->stat_lock);
 399                 }
 400
 401                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
 402                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
 403                 sbio->bio->bi_phys_segments = 0;
 404                 sbio->bio->bi_idx = 0;
 405
 406                 for (i = 0; i < sbio->count; i++) {
 407                         struct bio_vec *bi;
 408                         bi = &sbio->bio->bi_io_vec[i];
 409                         bi->bv_offset = 0;
 410                         bi->bv_len = PAGE_SIZE;
 411                 }
 412                 goto out;
 413         }
 414         for (i = 0; i < sbio->count; ++i) {
 415                 page = sbio->bio->bi_io_vec[i].bv_page;
 416                 buffer = kmap_atomic(page, KM_USER0);
 417                 flags = sbio->spag[i].flags;
 418                 logical = sbio->logical + i * PAGE_SIZE;
 419                 ret = 0;
 420                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
 421                         ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
 422                 } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 423                         ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
 424                                                         logical, buffer);
 425                 } else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
 426                         BUG_ON(i);
 427                         (void)scrub_checksum_super(sbio, buffer);
 428                 } else {
 429                         WARN_ON(1);
 430                 }
 431                 kunmap_atomic(buffer, KM_USER0);
 432                 if (ret) {
 433                         ret = scrub_recheck_error(sbio, i);
 434                         if (!ret) {
 435                                 spin_lock(&sdev->stat_lock);
 436                                 ++sdev->stat.unverified_errors;
 437                                 spin_unlock(&sdev->stat_lock);
 438                         }
 439                 }
 440         }
 441
 442 out:
 443         scrub_free_bio(sbio->bio);
 444         sbio->bio = NULL;
 445         spin_lock(&sdev->list_lock);
 446         sbio->next_free = sdev->first_free;
 447         sdev->first_free = sbio->index;
 448         spin_unlock(&sdev->list_lock);
 449         atomic_dec(&sdev->in_flight);
 450         wake_up(&sdev->list_wait);
 451 }
 452
 453 static int scrub_checksum_data(struct scrub_dev *sdev,
 454                                struct scrub_page *spag, void *buffer)
 455 {
 456         u8 csum[BTRFS_CSUM_SIZE];
 457         u32 crc = ~(u32)0;
 458         int fail = 0;
 459         struct btrfs_root *root = sdev->dev->dev_root;
 460
 461         if (!spag->have_csum)
 462                 return 0;
 463
 464         crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
 465         btrfs_csum_final(crc, csum);
 466         if (memcmp(csum, spag->csum, sdev->csum_size))
 467                 fail = 1;
 468
 469         spin_lock(&sdev->stat_lock);
 470         ++sdev->stat.data_extents_scrubbed;
 471         sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
 472         if (fail)
 473                 ++sdev->stat.csum_errors;
 474         spin_unlock(&sdev->stat_lock);
 475
 476         return fail;
 477 }
 478
 479 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
 480                                      struct scrub_page *spag, u64 logical,
 481                                      void *buffer)
 482 {
 483         struct btrfs_header *h;
 484         struct btrfs_root *root = sdev->dev->dev_root;
 485         struct btrfs_fs_info *fs_info = root->fs_info;
 486         u8 csum[BTRFS_CSUM_SIZE];
 487         u32 crc = ~(u32)0;
 488         int fail = 0;
 489         int crc_fail = 0;
 490
 491         /*
 492          * we don't use the getter functions here, as we
 493          * a) don't have an extent buffer and
 494          * b) the page is already kmapped
 495          */
 496         h = (struct btrfs_header *)buffer;
 497
 498         if (logical != le64_to_cpu(h->bytenr))
 499                 ++fail;
 500
 501         if (spag->generation != le64_to_cpu(h->generation))
 502                 ++fail;
 503
 504         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 505                 ++fail;
 506
 507         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
 508                    BTRFS_UUID_SIZE))
 509                 ++fail;
 510
 511         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 512                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 513         btrfs_csum_final(crc, csum);
 514         if (memcmp(csum, h->csum, sdev->csum_size))
 515                 ++crc_fail;
 516
 517         spin_lock(&sdev->stat_lock);
 518         ++sdev->stat.tree_extents_scrubbed;
 519         sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
 520         if (crc_fail)
 521                 ++sdev->stat.csum_errors;
 522         if (fail)
 523                 ++sdev->stat.verify_errors;
 524         spin_unlock(&sdev->stat_lock);
 525
 526         return fail || crc_fail;
 527 }
 528
 529 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
 530 {
 531         struct btrfs_super_block *s;
 532         u64 logical;
 533         struct scrub_dev *sdev = sbio->sdev;
 534         struct btrfs_root *root = sdev->dev->dev_root;
 535         struct btrfs_fs_info *fs_info = root->fs_info;
 536         u8 csum[BTRFS_CSUM_SIZE];
 537         u32 crc = ~(u32)0;
 538         int fail = 0;
 539
 540         s = (struct btrfs_super_block *)buffer;
 541         logical = sbio->logical;
 542
 543         if (logical != le64_to_cpu(s->bytenr))
 544                 ++fail;
 545
 546         if (sbio->spag[0].generation != le64_to_cpu(s->generation))
 547                 ++fail;
 548
 549         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
 550                 ++fail;
 551
 552         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
 553                               PAGE_SIZE - BTRFS_CSUM_SIZE);
 554         btrfs_csum_final(crc, csum);
 555         if (memcmp(csum, s->csum, sbio->sdev->csum_size))
 556                 ++fail;
 557
 558         if (fail) {
 559                 /*
 560                  * if we find an error in a super block, we just report it.
 561                  * They will get written with the next transaction commit
 562                  * anyway
 563                  */
 564                 spin_lock(&sdev->stat_lock);
 565                 ++sdev->stat.super_errors;
 566                 spin_unlock(&sdev->stat_lock);
 567         }
 568
 569         return fail;
 570 }
 571
 572 static int scrub_submit(struct scrub_dev *sdev)
 573 {
 574         struct scrub_bio *sbio;
 575         struct bio *bio;
 576         int i;
 577
 578         if (sdev->curr == -1)
 579                 return 0;
 580
 581         sbio = sdev->bios[sdev->curr];
 582
 583         bio = bio_alloc(GFP_NOFS, sbio->count);
 584         if (!bio)
 585                 goto nomem;
 586
 587         bio->bi_private = sbio;
 588         bio->bi_end_io = scrub_bio_end_io;
 589         bio->bi_bdev = sdev->dev->bdev;
 590         bio->bi_sector = sbio->physical >> 9;
 591
 592         for (i = 0; i < sbio->count; ++i) {
 593                 struct page *page;
 594                 int ret;
 595
 596                 page = alloc_page(GFP_NOFS);
 597                 if (!page)
 598                         goto nomem;
 599
 600                 ret = bio_add_page(bio, page, PAGE_SIZE, 0);
 601                 if (!ret) {
 602                         __free_page(page);
 603                         goto nomem;
 604                 }
 605         }
 606
 607         sbio->err = 0;
 608         sdev->curr = -1;
 609         atomic_inc(&sdev->in_flight);
 610
 611         submit_bio(READ, bio);
 612
 613         return 0;
 614
 615 nomem:
 616         scrub_free_bio(bio);
 617
 618         return -ENOMEM;
 619 }
 620
 621 static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
 622                       u64 physical, u64 flags, u64 gen, u64 mirror_num,
 623                       u8 *csum, int force)
 624 {
 625         struct scrub_bio *sbio;
 626
 627 again:
 628         /*
 629          * grab a fresh bio or wait for one to become available
 630          */
 631         while (sdev->curr == -1) {
 632                 spin_lock(&sdev->list_lock);
 633                 sdev->curr = sdev->first_free;
 634                 if (sdev->curr != -1) {
 635                         sdev->first_free = sdev->bios[sdev->curr]->next_free;
 636                         sdev->bios[sdev->curr]->next_free = -1;
 637                         sdev->bios[sdev->curr]->count = 0;
 638                         spin_unlock(&sdev->list_lock);
 639                 } else {
 640                         spin_unlock(&sdev->list_lock);
 641                         wait_event(sdev->list_wait, sdev->first_free != -1);
 642                 }
 643         }
 644         sbio = sdev->bios[sdev->curr];
 645         if (sbio->count == 0) {
 646                 sbio->physical = physical;
 647                 sbio->logical = logical;
 648         } else if (sbio->physical + sbio->count * PAGE_SIZE != physical ||
 649                    sbio->logical + sbio->count * PAGE_SIZE != logical) {
 650                 int ret;
 651
 652                 ret = scrub_submit(sdev);
 653                 if (ret)
 654                         return ret;
 655                 goto again;
 656         }
 657         sbio->spag[sbio->count].flags = flags;
 658         sbio->spag[sbio->count].generation = gen;
 659         sbio->spag[sbio->count].have_csum = 0;
 660         sbio->spag[sbio->count].mirror_num = mirror_num;
 661         if (csum) {
 662                 sbio->spag[sbio->count].have_csum = 1;
 663                 memcpy(sbio->spag[sbio->count].csum, csum, sdev->csum_size);
 664         }
 665         ++sbio->count;
 666         if (sbio->count == SCRUB_PAGES_PER_BIO || force) {
 667                 int ret;
 668
 669                 ret = scrub_submit(sdev);
 670                 if (ret)
 671                         return ret;
 672         }
 673
 674         return 0;
 675 }
 676
 677 static int scrub_find_csum(struct scrub_dev *sdev, u64 logical, u64 len,
 678                            u8 *csum)
 679 {
 680         struct btrfs_ordered_sum *sum = NULL;
 681         int ret = 0;
 682         unsigned long i;
 683         unsigned long num_sectors;
 684         u32 sectorsize = sdev->dev->dev_root->sectorsize;
 685
 686         while (!list_empty(&sdev->csum_list)) {
 687                 sum = list_first_entry(&sdev->csum_list,
 688                                        struct btrfs_ordered_sum, list);
 689                 if (sum->bytenr > logical)
 690                         return 0;
 691                 if (sum->bytenr + sum->len > logical)
 692                         break;
 693
 694                 ++sdev->stat.csum_discards;
 695                 list_del(&sum->list);
 696                 kfree(sum);
 697                 sum = NULL;
 698         }
 699         if (!sum)
 700                 return 0;
 701
 702         num_sectors = sum->len / sectorsize;
 703         for (i = 0; i < num_sectors; ++i) {
 704                 if (sum->sums[i].bytenr == logical) {
 705                         memcpy(csum, &sum->sums[i].sum, sdev->csum_size);
 706                         ret = 1;
 707                         break;
 708                 }
 709         }
 710         if (ret && i == num_sectors - 1) {
 711                 list_del(&sum->list);
 712                 kfree(sum);
 713         }
 714         return ret;
 715 }
 716
 717 /* scrub extent tries to collect up to 64 kB for each bio */
 718 static int scrub_extent(struct scrub_dev *sdev, u64 logical, u64 len,
 719                         u64 physical, u64 flags, u64 gen, u64 mirror_num)
 720 {
 721         int ret;
 722         u8 csum[BTRFS_CSUM_SIZE];
 723
 724         while (len) {
 725                 u64 l = min_t(u64, len, PAGE_SIZE);
 726                 int have_csum = 0;
 727
 728                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
 729                         /* push csums to sbio */
 730                         have_csum = scrub_find_csum(sdev, logical, l, csum);
 731                         if (have_csum == 0)
 732                                 ++sdev->stat.no_csum;
 733                 }
 734                 ret = scrub_page(sdev, logical, l, physical, flags, gen,
 735                                  mirror_num, have_csum ? csum : NULL, 0);
 736                 if (ret)
 737                         return ret;
 738                 len -= l;
 739                 logical += l;
 740                 physical += l;
 741         }
 742         return 0;
 743 }
 744
 745 static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
 746         struct map_lookup *map, int num, u64 base, u64 length)
 747 {
 748         struct btrfs_path *path;
 749         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
 750         struct btrfs_root *root = fs_info->extent_root;
 751         struct btrfs_root *csum_root = fs_info->csum_root;
 752         struct btrfs_extent_item *extent;
 753         struct blk_plug plug;
 754         u64 flags;
 755         int ret;
 756         int slot;
 757         int i;
 758         u64 nstripes;
 759         int start_stripe;
 760         struct extent_buffer *l;
 761         struct btrfs_key key;
 762         u64 physical;
 763         u64 logical;
 764         u64 generation;
 765         u64 mirror_num;
 766
 767         u64 increment = map->stripe_len;
 768         u64 offset;
 769
 770         nstripes = length;
 771         offset = 0;
 772         do_div(nstripes, map->stripe_len);
 773         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
 774                 offset = map->stripe_len * num;
 775                 increment = map->stripe_len * map->num_stripes;
 776                 mirror_num = 0;
 777         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
 778                 int factor = map->num_stripes / map->sub_stripes;
 779                 offset = map->stripe_len * (num / map->sub_stripes);
 780                 increment = map->stripe_len * factor;
 781                 mirror_num = num % map->sub_stripes;
 782         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
 783                 increment = map->stripe_len;
 784                 mirror_num = num % map->num_stripes;
 785         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
 786                 increment = map->stripe_len;
 787                 mirror_num = num % map->num_stripes;
 788         } else {
 789                 increment = map->stripe_len;
 790                 mirror_num = 0;
 791         }
 792
 793         path = btrfs_alloc_path();
 794         if (!path)
 795                 return -ENOMEM;
 796
 797         path->reada = 2;
 798         path->search_commit_root = 1;
 799         path->skip_locking = 1;
 800
 801         /*
 802          * find all extents for each stripe and just read them to get
 803          * them into the page cache
 804          * FIXME: we can do better. build a more intelligent prefetching
 805          */
 806         logical = base + offset;
 807         physical = map->stripes[num].physical;
 808         ret = 0;
 809         for (i = 0; i < nstripes; ++i) {
 810                 key.objectid = logical;
 811                 key.type = BTRFS_EXTENT_ITEM_KEY;
 812                 key.offset = (u64)0;
 813
 814                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 815                 if (ret < 0)
 816                         goto out_noplug;
 817
 818                 /*
 819                  * we might miss half an extent here, but that doesn't matter,
 820                  * as it's only the prefetch
 821                  */
 822                 while (1) {
 823                         l = path->nodes[0];
 824                         slot = path->slots[0];
 825                         if (slot >= btrfs_header_nritems(l)) {
 826                                 ret = btrfs_next_leaf(root, path);
 827                                 if (ret == 0)
 828                                         continue;
 829                                 if (ret < 0)
 830                                         goto out_noplug;
 831
 832                                 break;
 833                         }
 834                         btrfs_item_key_to_cpu(l, &key, slot);
 835
 836                         if (key.objectid >= logical + map->stripe_len)
 837                                 break;
 838
 839                         path->slots[0]++;
 840                 }
 841                 btrfs_release_path(path);
 842                 logical += increment;
 843                 physical += map->stripe_len;
 844                 cond_resched();
 845         }
 846
 847         /*
 848          * collect all data csums for the stripe to avoid seeking during
 849          * the scrub. This might currently (crc32) end up to be about 1MB
 850          */
 851         start_stripe = 0;
 852         blk_start_plug(&plug);
 853 again:
 854         logical = base + offset + start_stripe * increment;
 855         for (i = start_stripe; i < nstripes; ++i) {
 856                 ret = btrfs_lookup_csums_range(csum_root, logical,
 857                                                logical + map->stripe_len - 1,
 858                                                &sdev->csum_list, 1);
 859                 if (ret)
 860                         goto out;
 861
 862                 logical += increment;
 863                 cond_resched();
 864         }
 865         /*
 866          * now find all extents for each stripe and scrub them
 867          */
 868         logical = base + offset + start_stripe * increment;
 869         physical = map->stripes[num].physical + start_stripe * map->stripe_len;
 870         ret = 0;
 871         for (i = start_stripe; i < nstripes; ++i) {
 872                 /*
 873                  * canceled?
 874                  */
 875                 if (atomic_read(&fs_info->scrub_cancel_req) ||
 876                     atomic_read(&sdev->cancel_req)) {
 877                         ret = -ECANCELED;
 878                         goto out;
 879                 }
 880                 /*
 881                  * check to see if we have to pause
 882                  */
 883                 if (atomic_read(&fs_info->scrub_pause_req)) {
 884                         /* push queued extents */
 885                         scrub_submit(sdev);
 886                         wait_event(sdev->list_wait,
 887                                    atomic_read(&sdev->in_flight) == 0);
 888                         atomic_inc(&fs_info->scrubs_paused);
 889                         wake_up(&fs_info->scrub_pause_wait);
 890                         mutex_lock(&fs_info->scrub_lock);
 891                         while (atomic_read(&fs_info->scrub_pause_req)) {
 892                                 mutex_unlock(&fs_info->scrub_lock);
 893                                 wait_event(fs_info->scrub_pause_wait,
 894                                    atomic_read(&fs_info->scrub_pause_req) == 0);
 895                                 mutex_lock(&fs_info->scrub_lock);
 896                         }
 897                         atomic_dec(&fs_info->scrubs_paused);
 898                         mutex_unlock(&fs_info->scrub_lock);
 899                         wake_up(&fs_info->scrub_pause_wait);
 900                         scrub_free_csums(sdev);
 901                         start_stripe = i;
 902                         goto again;
 903                 }
 904
 905                 key.objectid = logical;
 906                 key.type = BTRFS_EXTENT_ITEM_KEY;
 907                 key.offset = (u64)0;
 908
 909                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 910                 if (ret < 0)
 911                         goto out;
 912                 if (ret > 0) {
 913                         ret = btrfs_previous_item(root, path, 0,
 914                                                   BTRFS_EXTENT_ITEM_KEY);
 915                         if (ret < 0)
 916                                 goto out;
 917                         if (ret > 0) {
 918                                 /* there's no smaller item, so stick with the
 919                                  * larger one */
 920                                 btrfs_release_path(path);
 921                                 ret = btrfs_search_slot(NULL, root, &key,
 922                                                         path, 0, 0);
 923                                 if (ret < 0)
 924                                         goto out;
 925                         }
 926                 }
 927
 928                 while (1) {
 929                         l = path->nodes[0];
 930                         slot = path->slots[0];
 931                         if (slot >= btrfs_header_nritems(l)) {
 932                                 ret = btrfs_next_leaf(root, path);
 933                                 if (ret == 0)
 934                                         continue;
 935                                 if (ret < 0)
 936                                         goto out;
 937
 938                                 break;
 939                         }
 940                         btrfs_item_key_to_cpu(l, &key, slot);
 941
 942                         if (key.objectid + key.offset <= logical)
 943                                 goto next;
 944
 945                         if (key.objectid >= logical + map->stripe_len)
 946                                 break;
 947
 948                         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
 949                                 goto next;
 950
 951                         extent = btrfs_item_ptr(l, slot,
 952                                                 struct btrfs_extent_item);
 953                         flags = btrfs_extent_flags(l, extent);
 954                         generation = btrfs_extent_generation(l, extent);
 955
 956                         if (key.objectid < logical &&
 957                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
 958                                 printk(KERN_ERR
 959                                        "btrfs scrub: tree block %llu spanning "
 960                                        "stripes, ignored. logical=%llu\n",
 961                                        (unsigned long long)key.objectid,
 962                                        (unsigned long long)logical);
 963                                 goto next;
 964                         }
 965
 966                         /*
 967                          * trim extent to this stripe
 968                          */
 969                         if (key.objectid < logical) {
 970                                 key.offset -= logical - key.objectid;
 971                                 key.objectid = logical;
 972                         }
 973                         if (key.objectid + key.offset >
 974                             logical + map->stripe_len) {
 975                                 key.offset = logical + map->stripe_len -
 976                                              key.objectid;
 977                         }
 978
 979                         ret = scrub_extent(sdev, key.objectid, key.offset,
 980                                            key.objectid - logical + physical,
 981                                            flags, generation, mirror_num);
 982                         if (ret)
 983                                 goto out;
 984
 985 next:
 986                         path->slots[0]++;
 987                 }
 988                 btrfs_release_path(path);
 989                 logical += increment;
 990                 physical += map->stripe_len;
 991                 spin_lock(&sdev->stat_lock);
 992                 sdev->stat.last_physical = physical;
 993                 spin_unlock(&sdev->stat_lock);
 994         }
 995         /* push queued extents */
 996         scrub_submit(sdev);
 997
 998 out:
 999         blk_finish_plug(&plug);
1000 out_noplug:
1001         btrfs_free_path(path);
1002         return ret < 0 ? ret : 0;
1003 }
1004
1005 static noinline_for_stack int scrub_chunk(struct scrub_dev *sdev,
1006         u64 chunk_tree, u64 chunk_objectid, u64 chunk_offset, u64 length)
1007 {
1008         struct btrfs_mapping_tree *map_tree =
1009                 &sdev->dev->dev_root->fs_info->mapping_tree;
1010         struct map_lookup *map;
1011         struct extent_map *em;
1012         int i;
1013         int ret = -EINVAL;
1014
1015         read_lock(&map_tree->map_tree.lock);
1016         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
1017         read_unlock(&map_tree->map_tree.lock);
1018
1019         if (!em)
1020                 return -EINVAL;
1021
1022         map = (struct map_lookup *)em->bdev;
1023         if (em->start != chunk_offset)
1024                 goto out;
1025
1026         if (em->len < length)
1027                 goto out;
1028
1029         for (i = 0; i < map->num_stripes; ++i) {
1030                 if (map->stripes[i].dev == sdev->dev) {
1031                         ret = scrub_stripe(sdev, map, i, chunk_offset, length);
1032                         if (ret)
1033                                 goto out;
1034                 }
1035         }
1036 out:
1037         free_extent_map(em);
1038
1039         return ret;
1040 }
1041
1042 static noinline_for_stack
1043 int scrub_enumerate_chunks(struct scrub_dev *sdev, u64 start, u64 end)
1044 {
1045         struct btrfs_dev_extent *dev_extent = NULL;
1046         struct btrfs_path *path;
1047         struct btrfs_root *root = sdev->dev->dev_root;
1048         struct btrfs_fs_info *fs_info = root->fs_info;
1049         u64 length;
1050         u64 chunk_tree;
1051         u64 chunk_objectid;
1052         u64 chunk_offset;
1053         int ret;
1054         int slot;
1055         struct extent_buffer *l;
1056         struct btrfs_key key;
1057         struct btrfs_key found_key;
1058         struct btrfs_block_group_cache *cache;
1059
1060         path = btrfs_alloc_path();
1061         if (!path)
1062                 return -ENOMEM;
1063
1064         path->reada = 2;
1065         path->search_commit_root = 1;
1066         path->skip_locking = 1;
1067
1068         key.objectid = sdev->dev->devid;
1069         key.offset = 0ull;
1070         key.type = BTRFS_DEV_EXTENT_KEY;
1071
1072
1073         while (1) {
1074                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1075                 if (ret < 0)
1076                         break;
1077                 if (ret > 0) {
1078                         if (path->slots[0] >=
1079                             btrfs_header_nritems(path->nodes[0])) {
1080                                 ret = btrfs_next_leaf(root, path);
1081                                 if (ret)
1082                                         break;
1083                         }
1084                 }
1085
1086                 l = path->nodes[0];
1087                 slot = path->slots[0];
1088
1089                 btrfs_item_key_to_cpu(l, &found_key, slot);
1090
1091                 if (found_key.objectid != sdev->dev->devid)
1092                         break;
1093
1094                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
1095                         break;
1096
1097                 if (found_key.offset >= end)
1098                         break;
1099
1100                 if (found_key.offset < key.offset)
1101                         break;
1102
1103                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
1104                 length = btrfs_dev_extent_length(l, dev_extent);
1105
1106                 if (found_key.offset + length <= start) {
1107                         key.offset = found_key.offset + length;
1108                         btrfs_release_path(path);
1109                         continue;
1110                 }
1111
1112                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
1113                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
1114                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
1115
1116                 /*
1117                  * get a reference on the corresponding block group to prevent
1118                  * the chunk from going away while we scrub it
1119                  */
1120                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
1121                 if (!cache) {
1122                         ret = -ENOENT;
1123                         break;
1124                 }
1125                 ret = scrub_chunk(sdev, chunk_tree, chunk_objectid,
1126                                   chunk_offset, length);
1127                 btrfs_put_block_group(cache);
1128                 if (ret)
1129                         break;
1130
1131                 key.offset = found_key.offset + length;
1132                 btrfs_release_path(path);
1133         }
1134
1135         btrfs_free_path(path);
1136
1137         /*
1138          * ret can still be 1 from search_slot or next_leaf,
1139          * that's not an error
1140          */
1141         return ret < 0 ? ret : 0;
1142 }
1143
1144 static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
1145 {
1146         int     i;
1147         u64     bytenr;
1148         u64     gen;
1149         int     ret;
1150         struct btrfs_device *device = sdev->dev;
1151         struct btrfs_root *root = device->dev_root;
1152
1153         gen = root->fs_info->last_trans_committed;
1154
1155         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
1156                 bytenr = btrfs_sb_offset(i);
1157                 if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
1158                         break;
1159
1160                 ret = scrub_page(sdev, bytenr, PAGE_SIZE, bytenr,
1161                                  BTRFS_EXTENT_FLAG_SUPER, gen, i, NULL, 1);
1162                 if (ret)
1163                         return ret;
1164         }
1165         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1166
1167         return 0;
1168 }
1169
1170 /*
1171  * get a reference count on fs_info->scrub_workers. start worker if necessary
1172  */
1173 static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
1174 {
1175         struct btrfs_fs_info *fs_info = root->fs_info;
1176
1177         mutex_lock(&fs_info->scrub_lock);
1178         if (fs_info->scrub_workers_refcnt == 0) {
1179                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
1180                            fs_info->thread_pool_size, &fs_info->generic_worker);
1181                 fs_info->scrub_workers.idle_thresh = 4;
1182                 btrfs_start_workers(&fs_info->scrub_workers, 1);
1183         }
1184         ++fs_info->scrub_workers_refcnt;
1185         mutex_unlock(&fs_info->scrub_lock);
1186
1187         return 0;
1188 }
1189
1190 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
1191 {
1192         struct btrfs_fs_info *fs_info = root->fs_info;
1193
1194         mutex_lock(&fs_info->scrub_lock);
1195         if (--fs_info->scrub_workers_refcnt == 0)
1196                 btrfs_stop_workers(&fs_info->scrub_workers);
1197         WARN_ON(fs_info->scrub_workers_refcnt < 0);
1198         mutex_unlock(&fs_info->scrub_lock);
1199 }
1200
1201
1202 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
1203                     struct btrfs_scrub_progress *progress, int readonly)
1204 {
1205         struct scrub_dev *sdev;
1206         struct btrfs_fs_info *fs_info = root->fs_info;
1207         int ret;
1208         struct btrfs_device *dev;
1209
1210         if (btrfs_fs_closing(root->fs_info))
1211                 return -EINVAL;
1212
1213         /*
1214          * check some assumptions
1215          */
1216         if (root->sectorsize != PAGE_SIZE ||
1217             root->sectorsize != root->leafsize ||
1218             root->sectorsize != root->nodesize) {
1219                 printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
1220                 return -EINVAL;
1221         }
1222
1223         ret = scrub_workers_get(root);
1224         if (ret)
1225                 return ret;
1226
1227         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1228         dev = btrfs_find_device(root, devid, NULL, NULL);
1229         if (!dev || dev->missing) {
1230                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1231                 scrub_workers_put(root);
1232                 return -ENODEV;
1233         }
1234         mutex_lock(&fs_info->scrub_lock);
1235
1236         if (!dev->in_fs_metadata) {
1237                 mutex_unlock(&fs_info->scrub_lock);
1238                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1239                 scrub_workers_put(root);
1240                 return -ENODEV;
1241         }
1242
1243         if (dev->scrub_device) {
1244                 mutex_unlock(&fs_info->scrub_lock);
1245                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1246                 scrub_workers_put(root);
1247                 return -EINPROGRESS;
1248         }
1249         sdev = scrub_setup_dev(dev);
1250         if (IS_ERR(sdev)) {
1251                 mutex_unlock(&fs_info->scrub_lock);
1252                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1253                 scrub_workers_put(root);
1254                 return PTR_ERR(sdev);
1255         }
1256         sdev->readonly = readonly;
1257         dev->scrub_device = sdev;
1258
1259         atomic_inc(&fs_info->scrubs_running);
1260         mutex_unlock(&fs_info->scrub_lock);
1261         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1262
1263         down_read(&fs_info->scrub_super_lock);
1264         ret = scrub_supers(sdev);
1265         up_read(&fs_info->scrub_super_lock);
1266
1267         if (!ret)
1268                 ret = scrub_enumerate_chunks(sdev, start, end);
1269
1270         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1271
1272         atomic_dec(&fs_info->scrubs_running);
1273         wake_up(&fs_info->scrub_pause_wait);
1274
1275         if (progress)
1276                 memcpy(progress, &sdev->stat, sizeof(*progress));
1277
1278         mutex_lock(&fs_info->scrub_lock);
1279         dev->scrub_device = NULL;
1280         mutex_unlock(&fs_info->scrub_lock);
1281
1282         scrub_free_dev(sdev);
1283         scrub_workers_put(root);
1284
1285         return ret;
1286 }
1287
1288 int btrfs_scrub_pause(struct btrfs_root *root)
1289 {
1290         struct btrfs_fs_info *fs_info = root->fs_info;
1291
1292         mutex_lock(&fs_info->scrub_lock);
1293         atomic_inc(&fs_info->scrub_pause_req);
1294         while (atomic_read(&fs_info->scrubs_paused) !=
1295                atomic_read(&fs_info->scrubs_running)) {
1296                 mutex_unlock(&fs_info->scrub_lock);
1297                 wait_event(fs_info->scrub_pause_wait,
1298                            atomic_read(&fs_info->scrubs_paused) ==
1299                            atomic_read(&fs_info->scrubs_running));
1300                 mutex_lock(&fs_info->scrub_lock);
1301         }
1302         mutex_unlock(&fs_info->scrub_lock);
1303
1304         return 0;
1305 }
1306
1307 int btrfs_scrub_continue(struct btrfs_root *root)
1308 {
1309         struct btrfs_fs_info *fs_info = root->fs_info;
1310
1311         atomic_dec(&fs_info->scrub_pause_req);
1312         wake_up(&fs_info->scrub_pause_wait);
1313         return 0;
1314 }
1315
1316 int btrfs_scrub_pause_super(struct btrfs_root *root)
1317 {
1318         down_write(&root->fs_info->scrub_super_lock);
1319         return 0;
1320 }
1321
1322 int btrfs_scrub_continue_super(struct btrfs_root *root)
1323 {
1324         up_write(&root->fs_info->scrub_super_lock);
1325         return 0;
1326 }
1327
1328 int btrfs_scrub_cancel(struct btrfs_root *root)
1329 {
1330         struct btrfs_fs_info *fs_info = root->fs_info;
1331
1332         mutex_lock(&fs_info->scrub_lock);
1333         if (!atomic_read(&fs_info->scrubs_running)) {
1334                 mutex_unlock(&fs_info->scrub_lock);
1335                 return -ENOTCONN;
1336         }
1337
1338         atomic_inc(&fs_info->scrub_cancel_req);
1339         while (atomic_read(&fs_info->scrubs_running)) {
1340                 mutex_unlock(&fs_info->scrub_lock);
1341                 wait_event(fs_info->scrub_pause_wait,
1342                            atomic_read(&fs_info->scrubs_running) == 0);
1343                 mutex_lock(&fs_info->scrub_lock);
1344         }
1345         atomic_dec(&fs_info->scrub_cancel_req);
1346         mutex_unlock(&fs_info->scrub_lock);
1347
1348         return 0;
1349 }
1350
1351 int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
1352 {
1353         struct btrfs_fs_info *fs_info = root->fs_info;
1354         struct scrub_dev *sdev;
1355
1356         mutex_lock(&fs_info->scrub_lock);
1357         sdev = dev->scrub_device;
1358         if (!sdev) {
1359                 mutex_unlock(&fs_info->scrub_lock);
1360                 return -ENOTCONN;
1361         }
1362         atomic_inc(&sdev->cancel_req);
1363         while (dev->scrub_device) {
1364                 mutex_unlock(&fs_info->scrub_lock);
1365                 wait_event(fs_info->scrub_pause_wait,
1366                            dev->scrub_device == NULL);
1367                 mutex_lock(&fs_info->scrub_lock);
1368         }
1369         mutex_unlock(&fs_info->scrub_lock);
1370
1371         return 0;
1372 }
1373 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
1374 {
1375         struct btrfs_fs_info *fs_info = root->fs_info;
1376         struct btrfs_device *dev;
1377         int ret;
1378
1379         /*
1380          * we have to hold the device_list_mutex here so the device
1381          * does not go away in cancel_dev. FIXME: find a better solution
1382          */
1383         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1384         dev = btrfs_find_device(root, devid, NULL, NULL);
1385         if (!dev) {
1386                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1387                 return -ENODEV;
1388         }
1389         ret = btrfs_scrub_cancel_dev(root, dev);
1390         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1391
1392         return ret;
1393 }
1394
1395 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
1396                          struct btrfs_scrub_progress *progress)
1397 {
1398         struct btrfs_device *dev;
1399         struct scrub_dev *sdev = NULL;
1400
1401         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1402         dev = btrfs_find_device(root, devid, NULL, NULL);
1403         if (dev)
1404                 sdev = dev->scrub_device;
1405         if (sdev)
1406                 memcpy(progress, &sdev->stat, sizeof(*progress));
1407         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1408
1409         return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
1410 }