fs/btrfs/scrub.c

   1 /*
   2  * Copyright (C) 2011, 2012 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 "dev-replace.h"
  29 #include "check-integrity.h"
  30 #include "rcu-string.h"
  31 #include "raid56.h"
  32
  33 /*
  34  * This is only the first step towards a full-features scrub. It reads all
  35  * extent and super block and verifies the checksums. In case a bad checksum
  36  * is found or the extent cannot be read, good data will be written back if
  37  * any can be found.
  38  *
  39  * Future enhancements:
  40  *  - In case an unrepairable extent is encountered, track which files are
  41  *    affected and report them
  42  *  - track and record media errors, throw out bad devices
  43  *  - add a mode to also read unallocated space
  44  */
  45
  46 struct scrub_block;
  47 struct scrub_ctx;
  48
  49 /*
  50  * the following three values only influence the performance.
  51  * The last one configures the number of parallel and outstanding I/O
  52  * operations. The first two values configure an upper limit for the number
  53  * of (dynamically allocated) pages that are added to a bio.
  54  */
  55 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  56 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  57 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  58
  59 /*
  60  * the following value times PAGE_SIZE needs to be large enough to match the
  61  * largest node/leaf/sector size that shall be supported.
  62  * Values larger than BTRFS_STRIPE_LEN are not supported.
  63  */
  64 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  65
  66 struct scrub_recover {
  67         atomic_t                refs;
  68         struct btrfs_bio        *bbio;
  69         u64                     map_length;
  70 };
  71
  72 struct scrub_page {
  73         struct scrub_block      *sblock;
  74         struct page             *page;
  75         struct btrfs_device     *dev;
  76         struct list_head        list;
  77         u64                     flags;  /* extent flags */
  78         u64                     generation;
  79         u64                     logical;
  80         u64                     physical;
  81         u64                     physical_for_dev_replace;
  82         atomic_t                refs;
  83         struct {
  84                 unsigned int    mirror_num:8;
  85                 unsigned int    have_csum:1;
  86                 unsigned int    io_error:1;
  87         };
  88         u8                      csum[BTRFS_CSUM_SIZE];
  89
  90         struct scrub_recover    *recover;
  91 };
  92
  93 struct scrub_bio {
  94         int                     index;
  95         struct scrub_ctx        *sctx;
  96         struct btrfs_device     *dev;
  97         struct bio              *bio;
  98         int                     err;
  99         u64                     logical;
 100         u64                     physical;
 101 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
 102         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
 103 #else
 104         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
 105 #endif
 106         int                     page_count;
 107         int                     next_free;
 108         struct btrfs_work       work;
 109 };
 110
 111 struct scrub_block {
 112         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 113         int                     page_count;
 114         atomic_t                outstanding_pages;
 115         atomic_t                refs; /* free mem on transition to zero */
 116         struct scrub_ctx        *sctx;
 117         struct scrub_parity     *sparity;
 118         struct {
 119                 unsigned int    header_error:1;
 120                 unsigned int    checksum_error:1;
 121                 unsigned int    no_io_error_seen:1;
 122                 unsigned int    generation_error:1; /* also sets header_error */
 123
 124                 /* The following is for the data used to check parity */
 125                 /* It is for the data with checksum */
 126                 unsigned int    data_corrected:1;
 127         };
 128         struct btrfs_work       work;
 129 };
 130
 131 /* Used for the chunks with parity stripe such RAID5/6 */
 132 struct scrub_parity {
 133         struct scrub_ctx        *sctx;
 134
 135         struct btrfs_device     *scrub_dev;
 136
 137         u64                     logic_start;
 138
 139         u64                     logic_end;
 140
 141         int                     nsectors;
 142
 143         int                     stripe_len;
 144
 145         atomic_t                refs;
 146
 147         struct list_head        spages;
 148
 149         /* Work of parity check and repair */
 150         struct btrfs_work       work;
 151
 152         /* Mark the parity blocks which have data */
 153         unsigned long           *dbitmap;
 154
 155         /*
 156          * Mark the parity blocks which have data, but errors happen when
 157          * read data or check data
 158          */
 159         unsigned long           *ebitmap;
 160
 161         unsigned long           bitmap[0];
 162 };
 163
 164 struct scrub_wr_ctx {
 165         struct scrub_bio *wr_curr_bio;
 166         struct btrfs_device *tgtdev;
 167         int pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 168         atomic_t flush_all_writes;
 169         struct mutex wr_lock;
 170 };
 171
 172 struct scrub_ctx {
 173         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 174         struct btrfs_root       *dev_root;
 175         int                     first_free;
 176         int                     curr;
 177         atomic_t                bios_in_flight;
 178         atomic_t                workers_pending;
 179         spinlock_t              list_lock;
 180         wait_queue_head_t       list_wait;
 181         u16                     csum_size;
 182         struct list_head        csum_list;
 183         atomic_t                cancel_req;
 184         int                     readonly;
 185         int                     pages_per_rd_bio;
 186         u32                     sectorsize;
 187         u32                     nodesize;
 188
 189         int                     is_dev_replace;
 190         struct scrub_wr_ctx     wr_ctx;
 191
 192         /*
 193          * statistics
 194          */
 195         struct btrfs_scrub_progress stat;
 196         spinlock_t              stat_lock;
 197
 198         /*
 199          * Use a ref counter to avoid use-after-free issues. Scrub workers
 200          * decrement bios_in_flight and workers_pending and then do a wakeup
 201          * on the list_wait wait queue. We must ensure the main scrub task
 202          * doesn't free the scrub context before or while the workers are
 203          * doing the wakeup() call.
 204          */
 205         atomic_t                refs;
 206 };
 207
 208 struct scrub_fixup_nodatasum {
 209         struct scrub_ctx        *sctx;
 210         struct btrfs_device     *dev;
 211         u64                     logical;
 212         struct btrfs_root       *root;
 213         struct btrfs_work       work;
 214         int                     mirror_num;
 215 };
 216
 217 struct scrub_nocow_inode {
 218         u64                     inum;
 219         u64                     offset;
 220         u64                     root;
 221         struct list_head        list;
 222 };
 223
 224 struct scrub_copy_nocow_ctx {
 225         struct scrub_ctx        *sctx;
 226         u64                     logical;
 227         u64                     len;
 228         int                     mirror_num;
 229         u64                     physical_for_dev_replace;
 230         struct list_head        inodes;
 231         struct btrfs_work       work;
 232 };
 233
 234 struct scrub_warning {
 235         struct btrfs_path       *path;
 236         u64                     extent_item_size;
 237         const char              *errstr;
 238         sector_t                sector;
 239         u64                     logical;
 240         struct btrfs_device     *dev;
 241 };
 242
 243 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 244 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 245 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
 246 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
 247 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 248 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 249                                      struct scrub_block *sblocks_for_recheck);
 250 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 251                                 struct scrub_block *sblock,
 252                                 int retry_failed_mirror);
 253 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 254 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 255                                              struct scrub_block *sblock_good);
 256 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 257                                             struct scrub_block *sblock_good,
 258                                             int page_num, int force_write);
 259 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 260 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 261                                            int page_num);
 262 static int scrub_checksum_data(struct scrub_block *sblock);
 263 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 264 static int scrub_checksum_super(struct scrub_block *sblock);
 265 static void scrub_block_get(struct scrub_block *sblock);
 266 static void scrub_block_put(struct scrub_block *sblock);
 267 static void scrub_page_get(struct scrub_page *spage);
 268 static void scrub_page_put(struct scrub_page *spage);
 269 static void scrub_parity_get(struct scrub_parity *sparity);
 270 static void scrub_parity_put(struct scrub_parity *sparity);
 271 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 272                                     struct scrub_page *spage);
 273 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 274                        u64 physical, struct btrfs_device *dev, u64 flags,
 275                        u64 gen, int mirror_num, u8 *csum, int force,
 276                        u64 physical_for_dev_replace);
 277 static void scrub_bio_end_io(struct bio *bio);
 278 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 279 static void scrub_block_complete(struct scrub_block *sblock);
 280 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 281                                u64 extent_logical, u64 extent_len,
 282                                u64 *extent_physical,
 283                                struct btrfs_device **extent_dev,
 284                                int *extent_mirror_num);
 285 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
 286                               struct scrub_wr_ctx *wr_ctx,
 287                               struct btrfs_fs_info *fs_info,
 288                               struct btrfs_device *dev,
 289                               int is_dev_replace);
 290 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx);
 291 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 292                                     struct scrub_page *spage);
 293 static void scrub_wr_submit(struct scrub_ctx *sctx);
 294 static void scrub_wr_bio_end_io(struct bio *bio);
 295 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 296 static int write_page_nocow(struct scrub_ctx *sctx,
 297                             u64 physical_for_dev_replace, struct page *page);
 298 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
 299                                       struct scrub_copy_nocow_ctx *ctx);
 300 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 301                             int mirror_num, u64 physical_for_dev_replace);
 302 static void copy_nocow_pages_worker(struct btrfs_work *work);
 303 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 304 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 305 static void scrub_put_ctx(struct scrub_ctx *sctx);
 306
 307
 308 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 309 {
 310         atomic_inc(&sctx->refs);
 311         atomic_inc(&sctx->bios_in_flight);
 312 }
 313
 314 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 315 {
 316         atomic_dec(&sctx->bios_in_flight);
 317         wake_up(&sctx->list_wait);
 318         scrub_put_ctx(sctx);
 319 }
 320
 321 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 322 {
 323         while (atomic_read(&fs_info->scrub_pause_req)) {
 324                 mutex_unlock(&fs_info->scrub_lock);
 325                 wait_event(fs_info->scrub_pause_wait,
 326                    atomic_read(&fs_info->scrub_pause_req) == 0);
 327                 mutex_lock(&fs_info->scrub_lock);
 328         }
 329 }
 330
 331 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 332 {
 333         atomic_inc(&fs_info->scrubs_paused);
 334         wake_up(&fs_info->scrub_pause_wait);
 335 }
 336
 337 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 338 {
 339         mutex_lock(&fs_info->scrub_lock);
 340         __scrub_blocked_if_needed(fs_info);
 341         atomic_dec(&fs_info->scrubs_paused);
 342         mutex_unlock(&fs_info->scrub_lock);
 343
 344         wake_up(&fs_info->scrub_pause_wait);
 345 }
 346
 347 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 348 {
 349         scrub_pause_on(fs_info);
 350         scrub_pause_off(fs_info);
 351 }
 352
 353 /*
 354  * used for workers that require transaction commits (i.e., for the
 355  * NOCOW case)
 356  */
 357 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
 358 {
 359         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 360
 361         atomic_inc(&sctx->refs);
 362         /*
 363          * increment scrubs_running to prevent cancel requests from
 364          * completing as long as a worker is running. we must also
 365          * increment scrubs_paused to prevent deadlocking on pause
 366          * requests used for transactions commits (as the worker uses a
 367          * transaction context). it is safe to regard the worker
 368          * as paused for all matters practical. effectively, we only
 369          * avoid cancellation requests from completing.
 370          */
 371         mutex_lock(&fs_info->scrub_lock);
 372         atomic_inc(&fs_info->scrubs_running);
 373         atomic_inc(&fs_info->scrubs_paused);
 374         mutex_unlock(&fs_info->scrub_lock);
 375
 376         /*
 377          * check if @scrubs_running=@scrubs_paused condition
 378          * inside wait_event() is not an atomic operation.
 379          * which means we may inc/dec @scrub_running/paused
 380          * at any time. Let's wake up @scrub_pause_wait as
 381          * much as we can to let commit transaction blocked less.
 382          */
 383         wake_up(&fs_info->scrub_pause_wait);
 384
 385         atomic_inc(&sctx->workers_pending);
 386 }
 387
 388 /* used for workers that require transaction commits */
 389 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
 390 {
 391         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 392
 393         /*
 394          * see scrub_pending_trans_workers_inc() why we're pretending
 395          * to be paused in the scrub counters
 396          */
 397         mutex_lock(&fs_info->scrub_lock);
 398         atomic_dec(&fs_info->scrubs_running);
 399         atomic_dec(&fs_info->scrubs_paused);
 400         mutex_unlock(&fs_info->scrub_lock);
 401         atomic_dec(&sctx->workers_pending);
 402         wake_up(&fs_info->scrub_pause_wait);
 403         wake_up(&sctx->list_wait);
 404         scrub_put_ctx(sctx);
 405 }
 406
 407 static void scrub_free_csums(struct scrub_ctx *sctx)
 408 {
 409         while (!list_empty(&sctx->csum_list)) {
 410                 struct btrfs_ordered_sum *sum;
 411                 sum = list_first_entry(&sctx->csum_list,
 412                                        struct btrfs_ordered_sum, list);
 413                 list_del(&sum->list);
 414                 kfree(sum);
 415         }
 416 }
 417
 418 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 419 {
 420         int i;
 421
 422         if (!sctx)
 423                 return;
 424
 425         scrub_free_wr_ctx(&sctx->wr_ctx);
 426
 427         /* this can happen when scrub is cancelled */
 428         if (sctx->curr != -1) {
 429                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 430
 431                 for (i = 0; i < sbio->page_count; i++) {
 432                         WARN_ON(!sbio->pagev[i]->page);
 433                         scrub_block_put(sbio->pagev[i]->sblock);
 434                 }
 435                 bio_put(sbio->bio);
 436         }
 437
 438         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 439                 struct scrub_bio *sbio = sctx->bios[i];
 440
 441                 if (!sbio)
 442                         break;
 443                 kfree(sbio);
 444         }
 445
 446         scrub_free_csums(sctx);
 447         kfree(sctx);
 448 }
 449
 450 static void scrub_put_ctx(struct scrub_ctx *sctx)
 451 {
 452         if (atomic_dec_and_test(&sctx->refs))
 453                 scrub_free_ctx(sctx);
 454 }
 455
 456 static noinline_for_stack
 457 struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 458 {
 459         struct scrub_ctx *sctx;
 460         int             i;
 461         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 462         int ret;
 463
 464         sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 465         if (!sctx)
 466                 goto nomem;
 467         atomic_set(&sctx->refs, 1);
 468         sctx->is_dev_replace = is_dev_replace;
 469         sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 470         sctx->curr = -1;
 471         sctx->dev_root = dev->dev_root;
 472         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 473                 struct scrub_bio *sbio;
 474
 475                 sbio = kzalloc(sizeof(*sbio), GFP_KERNEL);
 476                 if (!sbio)
 477                         goto nomem;
 478                 sctx->bios[i] = sbio;
 479
 480                 sbio->index = i;
 481                 sbio->sctx = sctx;
 482                 sbio->page_count = 0;
 483                 btrfs_init_work(&sbio->work, btrfs_scrub_helper,
 484                                 scrub_bio_end_io_worker, NULL, NULL);
 485
 486                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 487                         sctx->bios[i]->next_free = i + 1;
 488                 else
 489                         sctx->bios[i]->next_free = -1;
 490         }
 491         sctx->first_free = 0;
 492         sctx->nodesize = dev->dev_root->nodesize;
 493         sctx->sectorsize = dev->dev_root->sectorsize;
 494         atomic_set(&sctx->bios_in_flight, 0);
 495         atomic_set(&sctx->workers_pending, 0);
 496         atomic_set(&sctx->cancel_req, 0);
 497         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 498         INIT_LIST_HEAD(&sctx->csum_list);
 499
 500         spin_lock_init(&sctx->list_lock);
 501         spin_lock_init(&sctx->stat_lock);
 502         init_waitqueue_head(&sctx->list_wait);
 503
 504         ret = scrub_setup_wr_ctx(sctx, &sctx->wr_ctx, fs_info,
 505                                  fs_info->dev_replace.tgtdev, is_dev_replace);
 506         if (ret) {
 507                 scrub_free_ctx(sctx);
 508                 return ERR_PTR(ret);
 509         }
 510         return sctx;
 511
 512 nomem:
 513         scrub_free_ctx(sctx);
 514         return ERR_PTR(-ENOMEM);
 515 }
 516
 517 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 518                                      void *warn_ctx)
 519 {
 520         u64 isize;
 521         u32 nlink;
 522         int ret;
 523         int i;
 524         struct extent_buffer *eb;
 525         struct btrfs_inode_item *inode_item;
 526         struct scrub_warning *swarn = warn_ctx;
 527         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
 528         struct inode_fs_paths *ipath = NULL;
 529         struct btrfs_root *local_root;
 530         struct btrfs_key root_key;
 531         struct btrfs_key key;
 532
 533         root_key.objectid = root;
 534         root_key.type = BTRFS_ROOT_ITEM_KEY;
 535         root_key.offset = (u64)-1;
 536         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 537         if (IS_ERR(local_root)) {
 538                 ret = PTR_ERR(local_root);
 539                 goto err;
 540         }
 541
 542         /*
 543          * this makes the path point to (inum INODE_ITEM ioff)
 544          */
 545         key.objectid = inum;
 546         key.type = BTRFS_INODE_ITEM_KEY;
 547         key.offset = 0;
 548
 549         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 550         if (ret) {
 551                 btrfs_release_path(swarn->path);
 552                 goto err;
 553         }
 554
 555         eb = swarn->path->nodes[0];
 556         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 557                                         struct btrfs_inode_item);
 558         isize = btrfs_inode_size(eb, inode_item);
 559         nlink = btrfs_inode_nlink(eb, inode_item);
 560         btrfs_release_path(swarn->path);
 561
 562         ipath = init_ipath(4096, local_root, swarn->path);
 563         if (IS_ERR(ipath)) {
 564                 ret = PTR_ERR(ipath);
 565                 ipath = NULL;
 566                 goto err;
 567         }
 568         ret = paths_from_inode(inum, ipath);
 569
 570         if (ret < 0)
 571                 goto err;
 572
 573         /*
 574          * we deliberately ignore the bit ipath might have been too small to
 575          * hold all of the paths here
 576          */
 577         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 578                 btrfs_warn_in_rcu(fs_info, "%s at logical %llu on dev "
 579                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
 580                         "length %llu, links %u (path: %s)", swarn->errstr,
 581                         swarn->logical, rcu_str_deref(swarn->dev->name),
 582                         (unsigned long long)swarn->sector, root, inum, offset,
 583                         min(isize - offset, (u64)PAGE_SIZE), nlink,
 584                         (char *)(unsigned long)ipath->fspath->val[i]);
 585
 586         free_ipath(ipath);
 587         return 0;
 588
 589 err:
 590         btrfs_warn_in_rcu(fs_info, "%s at logical %llu on dev "
 591                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
 592                 "resolving failed with ret=%d", swarn->errstr,
 593                 swarn->logical, rcu_str_deref(swarn->dev->name),
 594                 (unsigned long long)swarn->sector, root, inum, offset, ret);
 595
 596         free_ipath(ipath);
 597         return 0;
 598 }
 599
 600 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 601 {
 602         struct btrfs_device *dev;
 603         struct btrfs_fs_info *fs_info;
 604         struct btrfs_path *path;
 605         struct btrfs_key found_key;
 606         struct extent_buffer *eb;
 607         struct btrfs_extent_item *ei;
 608         struct scrub_warning swarn;
 609         unsigned long ptr = 0;
 610         u64 extent_item_pos;
 611         u64 flags = 0;
 612         u64 ref_root;
 613         u32 item_size;
 614         u8 ref_level = 0;
 615         int ret;
 616
 617         WARN_ON(sblock->page_count < 1);
 618         dev = sblock->pagev[0]->dev;
 619         fs_info = sblock->sctx->dev_root->fs_info;
 620
 621         path = btrfs_alloc_path();
 622         if (!path)
 623                 return;
 624
 625         swarn.sector = (sblock->pagev[0]->physical) >> 9;
 626         swarn.logical = sblock->pagev[0]->logical;
 627         swarn.errstr = errstr;
 628         swarn.dev = NULL;
 629
 630         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 631                                   &flags);
 632         if (ret < 0)
 633                 goto out;
 634
 635         extent_item_pos = swarn.logical - found_key.objectid;
 636         swarn.extent_item_size = found_key.offset;
 637
 638         eb = path->nodes[0];
 639         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 640         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 641
 642         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 643                 do {
 644                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 645                                                       item_size, &ref_root,
 646                                                       &ref_level);
 647                         btrfs_warn_in_rcu(fs_info,
 648                                 "%s at logical %llu on dev %s, "
 649                                 "sector %llu: metadata %s (level %d) in tree "
 650                                 "%llu", errstr, swarn.logical,
 651                                 rcu_str_deref(dev->name),
 652                                 (unsigned long long)swarn.sector,
 653                                 ref_level ? "node" : "leaf",
 654                                 ret < 0 ? -1 : ref_level,
 655                                 ret < 0 ? -1 : ref_root);
 656                 } while (ret != 1);
 657                 btrfs_release_path(path);
 658         } else {
 659                 btrfs_release_path(path);
 660                 swarn.path = path;
 661                 swarn.dev = dev;
 662                 iterate_extent_inodes(fs_info, found_key.objectid,
 663                                         extent_item_pos, 1,
 664                                         scrub_print_warning_inode, &swarn);
 665         }
 666
 667 out:
 668         btrfs_free_path(path);
 669 }
 670
 671 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
 672 {
 673         struct page *page = NULL;
 674         unsigned long index;
 675         struct scrub_fixup_nodatasum *fixup = fixup_ctx;
 676         int ret;
 677         int corrected = 0;
 678         struct btrfs_key key;
 679         struct inode *inode = NULL;
 680         struct btrfs_fs_info *fs_info;
 681         u64 end = offset + PAGE_SIZE - 1;
 682         struct btrfs_root *local_root;
 683         int srcu_index;
 684
 685         key.objectid = root;
 686         key.type = BTRFS_ROOT_ITEM_KEY;
 687         key.offset = (u64)-1;
 688
 689         fs_info = fixup->root->fs_info;
 690         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
 691
 692         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
 693         if (IS_ERR(local_root)) {
 694                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 695                 return PTR_ERR(local_root);
 696         }
 697
 698         key.type = BTRFS_INODE_ITEM_KEY;
 699         key.objectid = inum;
 700         key.offset = 0;
 701         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
 702         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 703         if (IS_ERR(inode))
 704                 return PTR_ERR(inode);
 705
 706         index = offset >> PAGE_SHIFT;
 707
 708         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 709         if (!page) {
 710                 ret = -ENOMEM;
 711                 goto out;
 712         }
 713
 714         if (PageUptodate(page)) {
 715                 if (PageDirty(page)) {
 716                         /*
 717                          * we need to write the data to the defect sector. the
 718                          * data that was in that sector is not in memory,
 719                          * because the page was modified. we must not write the
 720                          * modified page to that sector.
 721                          *
 722                          * TODO: what could be done here: wait for the delalloc
 723                          *       runner to write out that page (might involve
 724                          *       COW) and see whether the sector is still
 725                          *       referenced afterwards.
 726                          *
 727                          * For the meantime, we'll treat this error
 728                          * incorrectable, although there is a chance that a
 729                          * later scrub will find the bad sector again and that
 730                          * there's no dirty page in memory, then.
 731                          */
 732                         ret = -EIO;
 733                         goto out;
 734                 }
 735                 ret = repair_io_failure(inode, offset, PAGE_SIZE,
 736                                         fixup->logical, page,
 737                                         offset - page_offset(page),
 738                                         fixup->mirror_num);
 739                 unlock_page(page);
 740                 corrected = !ret;
 741         } else {
 742                 /*
 743                  * we need to get good data first. the general readpage path
 744                  * will call repair_io_failure for us, we just have to make
 745                  * sure we read the bad mirror.
 746                  */
 747                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 748                                         EXTENT_DAMAGED);
 749                 if (ret) {
 750                         /* set_extent_bits should give proper error */
 751                         WARN_ON(ret > 0);
 752                         if (ret > 0)
 753                                 ret = -EFAULT;
 754                         goto out;
 755                 }
 756
 757                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 758                                                 btrfs_get_extent,
 759                                                 fixup->mirror_num);
 760                 wait_on_page_locked(page);
 761
 762                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 763                                                 end, EXTENT_DAMAGED, 0, NULL);
 764                 if (!corrected)
 765                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 766                                                 EXTENT_DAMAGED);
 767         }
 768
 769 out:
 770         if (page)
 771                 put_page(page);
 772
 773         iput(inode);
 774
 775         if (ret < 0)
 776                 return ret;
 777
 778         if (ret == 0 && corrected) {
 779                 /*
 780                  * we only need to call readpage for one of the inodes belonging
 781                  * to this extent. so make iterate_extent_inodes stop
 782                  */
 783                 return 1;
 784         }
 785
 786         return -EIO;
 787 }
 788
 789 static void scrub_fixup_nodatasum(struct btrfs_work *work)
 790 {
 791         int ret;
 792         struct scrub_fixup_nodatasum *fixup;
 793         struct scrub_ctx *sctx;
 794         struct btrfs_trans_handle *trans = NULL;
 795         struct btrfs_path *path;
 796         int uncorrectable = 0;
 797
 798         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
 799         sctx = fixup->sctx;
 800
 801         path = btrfs_alloc_path();
 802         if (!path) {
 803                 spin_lock(&sctx->stat_lock);
 804                 ++sctx->stat.malloc_errors;
 805                 spin_unlock(&sctx->stat_lock);
 806                 uncorrectable = 1;
 807                 goto out;
 808         }
 809
 810         trans = btrfs_join_transaction(fixup->root);
 811         if (IS_ERR(trans)) {
 812                 uncorrectable = 1;
 813                 goto out;
 814         }
 815
 816         /*
 817          * the idea is to trigger a regular read through the standard path. we
 818          * read a page from the (failed) logical address by specifying the
 819          * corresponding copynum of the failed sector. thus, that readpage is
 820          * expected to fail.
 821          * that is the point where on-the-fly error correction will kick in
 822          * (once it's finished) and rewrite the failed sector if a good copy
 823          * can be found.
 824          */
 825         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
 826                                                 path, scrub_fixup_readpage,
 827                                                 fixup);
 828         if (ret < 0) {
 829                 uncorrectable = 1;
 830                 goto out;
 831         }
 832         WARN_ON(ret != 1);
 833
 834         spin_lock(&sctx->stat_lock);
 835         ++sctx->stat.corrected_errors;
 836         spin_unlock(&sctx->stat_lock);
 837
 838 out:
 839         if (trans && !IS_ERR(trans))
 840                 btrfs_end_transaction(trans, fixup->root);
 841         if (uncorrectable) {
 842                 spin_lock(&sctx->stat_lock);
 843                 ++sctx->stat.uncorrectable_errors;
 844                 spin_unlock(&sctx->stat_lock);
 845                 btrfs_dev_replace_stats_inc(
 846                         &sctx->dev_root->fs_info->dev_replace.
 847                         num_uncorrectable_read_errors);
 848                 btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
 849                     "unable to fixup (nodatasum) error at logical %llu on dev %s",
 850                         fixup->logical, rcu_str_deref(fixup->dev->name));
 851         }
 852
 853         btrfs_free_path(path);
 854         kfree(fixup);
 855
 856         scrub_pending_trans_workers_dec(sctx);
 857 }
 858
 859 static inline void scrub_get_recover(struct scrub_recover *recover)
 860 {
 861         atomic_inc(&recover->refs);
 862 }
 863
 864 static inline void scrub_put_recover(struct scrub_recover *recover)
 865 {
 866         if (atomic_dec_and_test(&recover->refs)) {
 867                 btrfs_put_bbio(recover->bbio);
 868                 kfree(recover);
 869         }
 870 }
 871
 872 /*
 873  * scrub_handle_errored_block gets called when either verification of the
 874  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 875  * case, this function handles all pages in the bio, even though only one
 876  * may be bad.
 877  * The goal of this function is to repair the errored block by using the
 878  * contents of one of the mirrors.
 879  */
 880 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 881 {
 882         struct scrub_ctx *sctx = sblock_to_check->sctx;
 883         struct btrfs_device *dev;
 884         struct btrfs_fs_info *fs_info;
 885         u64 length;
 886         u64 logical;
 887         unsigned int failed_mirror_index;
 888         unsigned int is_metadata;
 889         unsigned int have_csum;
 890         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 891         struct scrub_block *sblock_bad;
 892         int ret;
 893         int mirror_index;
 894         int page_num;
 895         int success;
 896         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 897                                       DEFAULT_RATELIMIT_BURST);
 898
 899         BUG_ON(sblock_to_check->page_count < 1);
 900         fs_info = sctx->dev_root->fs_info;
 901         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 902                 /*
 903                  * if we find an error in a super block, we just report it.
 904                  * They will get written with the next transaction commit
 905                  * anyway
 906                  */
 907                 spin_lock(&sctx->stat_lock);
 908                 ++sctx->stat.super_errors;
 909                 spin_unlock(&sctx->stat_lock);
 910                 return 0;
 911         }
 912         length = sblock_to_check->page_count * PAGE_SIZE;
 913         logical = sblock_to_check->pagev[0]->logical;
 914         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 915         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 916         is_metadata = !(sblock_to_check->pagev[0]->flags &
 917                         BTRFS_EXTENT_FLAG_DATA);
 918         have_csum = sblock_to_check->pagev[0]->have_csum;
 919         dev = sblock_to_check->pagev[0]->dev;
 920
 921         if (sctx->is_dev_replace && !is_metadata && !have_csum) {
 922                 sblocks_for_recheck = NULL;
 923                 goto nodatasum_case;
 924         }
 925
 926         /*
 927          * read all mirrors one after the other. This includes to
 928          * re-read the extent or metadata block that failed (that was
 929          * the cause that this fixup code is called) another time,
 930          * page by page this time in order to know which pages
 931          * caused I/O errors and which ones are good (for all mirrors).
 932          * It is the goal to handle the situation when more than one
 933          * mirror contains I/O errors, but the errors do not
 934          * overlap, i.e. the data can be repaired by selecting the
 935          * pages from those mirrors without I/O error on the
 936          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 937          * would be that mirror #1 has an I/O error on the first page,
 938          * the second page is good, and mirror #2 has an I/O error on
 939          * the second page, but the first page is good.
 940          * Then the first page of the first mirror can be repaired by
 941          * taking the first page of the second mirror, and the
 942          * second page of the second mirror can be repaired by
 943          * copying the contents of the 2nd page of the 1st mirror.
 944          * One more note: if the pages of one mirror contain I/O
 945          * errors, the checksum cannot be verified. In order to get
 946          * the best data for repairing, the first attempt is to find
 947          * a mirror without I/O errors and with a validated checksum.
 948          * Only if this is not possible, the pages are picked from
 949          * mirrors with I/O errors without considering the checksum.
 950          * If the latter is the case, at the end, the checksum of the
 951          * repaired area is verified in order to correctly maintain
 952          * the statistics.
 953          */
 954
 955         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
 956                                       sizeof(*sblocks_for_recheck), GFP_NOFS);
 957         if (!sblocks_for_recheck) {
 958                 spin_lock(&sctx->stat_lock);
 959                 sctx->stat.malloc_errors++;
 960                 sctx->stat.read_errors++;
 961                 sctx->stat.uncorrectable_errors++;
 962                 spin_unlock(&sctx->stat_lock);
 963                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 964                 goto out;
 965         }
 966
 967         /* setup the context, map the logical blocks and alloc the pages */
 968         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
 969         if (ret) {
 970                 spin_lock(&sctx->stat_lock);
 971                 sctx->stat.read_errors++;
 972                 sctx->stat.uncorrectable_errors++;
 973                 spin_unlock(&sctx->stat_lock);
 974                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 975                 goto out;
 976         }
 977         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 978         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 979
 980         /* build and submit the bios for the failed mirror, check checksums */
 981         scrub_recheck_block(fs_info, sblock_bad, 1);
 982
 983         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 984             sblock_bad->no_io_error_seen) {
 985                 /*
 986                  * the error disappeared after reading page by page, or
 987                  * the area was part of a huge bio and other parts of the
 988                  * bio caused I/O errors, or the block layer merged several
 989                  * read requests into one and the error is caused by a
 990                  * different bio (usually one of the two latter cases is
 991                  * the cause)
 992                  */
 993                 spin_lock(&sctx->stat_lock);
 994                 sctx->stat.unverified_errors++;
 995                 sblock_to_check->data_corrected = 1;
 996                 spin_unlock(&sctx->stat_lock);
 997
 998                 if (sctx->is_dev_replace)
 999                         scrub_write_block_to_dev_replace(sblock_bad);
1000                 goto out;
1001         }
1002
1003         if (!sblock_bad->no_io_error_seen) {
1004                 spin_lock(&sctx->stat_lock);
1005                 sctx->stat.read_errors++;
1006                 spin_unlock(&sctx->stat_lock);
1007                 if (__ratelimit(&_rs))
1008                         scrub_print_warning("i/o error", sblock_to_check);
1009                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
1010         } else if (sblock_bad->checksum_error) {
1011                 spin_lock(&sctx->stat_lock);
1012                 sctx->stat.csum_errors++;
1013                 spin_unlock(&sctx->stat_lock);
1014                 if (__ratelimit(&_rs))
1015                         scrub_print_warning("checksum error", sblock_to_check);
1016                 btrfs_dev_stat_inc_and_print(dev,
1017                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
1018         } else if (sblock_bad->header_error) {
1019                 spin_lock(&sctx->stat_lock);
1020                 sctx->stat.verify_errors++;
1021                 spin_unlock(&sctx->stat_lock);
1022                 if (__ratelimit(&_rs))
1023                         scrub_print_warning("checksum/header error",
1024                                             sblock_to_check);
1025                 if (sblock_bad->generation_error)
1026                         btrfs_dev_stat_inc_and_print(dev,
1027                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1028                 else
1029                         btrfs_dev_stat_inc_and_print(dev,
1030                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1031         }
1032
1033         if (sctx->readonly) {
1034                 ASSERT(!sctx->is_dev_replace);
1035                 goto out;
1036         }
1037
1038         if (!is_metadata && !have_csum) {
1039                 struct scrub_fixup_nodatasum *fixup_nodatasum;
1040
1041                 WARN_ON(sctx->is_dev_replace);
1042
1043 nodatasum_case:
1044
1045                 /*
1046                  * !is_metadata and !have_csum, this means that the data
1047                  * might not be COWed, that it might be modified
1048                  * concurrently. The general strategy to work on the
1049                  * commit root does not help in the case when COW is not
1050                  * used.
1051                  */
1052                 fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum), GFP_NOFS);
1053                 if (!fixup_nodatasum)
1054                         goto did_not_correct_error;
1055                 fixup_nodatasum->sctx = sctx;
1056                 fixup_nodatasum->dev = dev;
1057                 fixup_nodatasum->logical = logical;
1058                 fixup_nodatasum->root = fs_info->extent_root;
1059                 fixup_nodatasum->mirror_num = failed_mirror_index + 1;
1060                 scrub_pending_trans_workers_inc(sctx);
1061                 btrfs_init_work(&fixup_nodatasum->work, btrfs_scrub_helper,
1062                                 scrub_fixup_nodatasum, NULL, NULL);
1063                 btrfs_queue_work(fs_info->scrub_workers,
1064                                  &fixup_nodatasum->work);
1065                 goto out;
1066         }
1067
1068         /*
1069          * now build and submit the bios for the other mirrors, check
1070          * checksums.
1071          * First try to pick the mirror which is completely without I/O
1072          * errors and also does not have a checksum error.
1073          * If one is found, and if a checksum is present, the full block
1074          * that is known to contain an error is rewritten. Afterwards
1075          * the block is known to be corrected.
1076          * If a mirror is found which is completely correct, and no
1077          * checksum is present, only those pages are rewritten that had
1078          * an I/O error in the block to be repaired, since it cannot be
1079          * determined, which copy of the other pages is better (and it
1080          * could happen otherwise that a correct page would be
1081          * overwritten by a bad one).
1082          */
1083         for (mirror_index = 0;
1084              mirror_index < BTRFS_MAX_MIRRORS &&
1085              sblocks_for_recheck[mirror_index].page_count > 0;
1086              mirror_index++) {
1087                 struct scrub_block *sblock_other;
1088
1089                 if (mirror_index == failed_mirror_index)
1090                         continue;
1091                 sblock_other = sblocks_for_recheck + mirror_index;
1092
1093                 /* build and submit the bios, check checksums */
1094                 scrub_recheck_block(fs_info, sblock_other, 0);
1095
1096                 if (!sblock_other->header_error &&
1097                     !sblock_other->checksum_error &&
1098                     sblock_other->no_io_error_seen) {
1099                         if (sctx->is_dev_replace) {
1100                                 scrub_write_block_to_dev_replace(sblock_other);
1101                                 goto corrected_error;
1102                         } else {
1103                                 ret = scrub_repair_block_from_good_copy(
1104                                                 sblock_bad, sblock_other);
1105                                 if (!ret)
1106                                         goto corrected_error;
1107                         }
1108                 }
1109         }
1110
1111         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1112                 goto did_not_correct_error;
1113
1114         /*
1115          * In case of I/O errors in the area that is supposed to be
1116          * repaired, continue by picking good copies of those pages.
1117          * Select the good pages from mirrors to rewrite bad pages from
1118          * the area to fix. Afterwards verify the checksum of the block
1119          * that is supposed to be repaired. This verification step is
1120          * only done for the purpose of statistic counting and for the
1121          * final scrub report, whether errors remain.
1122          * A perfect algorithm could make use of the checksum and try
1123          * all possible combinations of pages from the different mirrors
1124          * until the checksum verification succeeds. For example, when
1125          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1126          * of mirror #2 is readable but the final checksum test fails,
1127          * then the 2nd page of mirror #3 could be tried, whether now
1128          * the final checksum succeeds. But this would be a rare
1129          * exception and is therefore not implemented. At least it is
1130          * avoided that the good copy is overwritten.
1131          * A more useful improvement would be to pick the sectors
1132          * without I/O error based on sector sizes (512 bytes on legacy
1133          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1134          * mirror could be repaired by taking 512 byte of a different
1135          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1136          * area are unreadable.
1137          */
1138         success = 1;
1139         for (page_num = 0; page_num < sblock_bad->page_count;
1140              page_num++) {
1141                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1142                 struct scrub_block *sblock_other = NULL;
1143
1144                 /* skip no-io-error page in scrub */
1145                 if (!page_bad->io_error && !sctx->is_dev_replace)
1146                         continue;
1147
1148                 /* try to find no-io-error page in mirrors */
1149                 if (page_bad->io_error) {
1150                         for (mirror_index = 0;
1151                              mirror_index < BTRFS_MAX_MIRRORS &&
1152                              sblocks_for_recheck[mirror_index].page_count > 0;
1153                              mirror_index++) {
1154                                 if (!sblocks_for_recheck[mirror_index].
1155                                     pagev[page_num]->io_error) {
1156                                         sblock_other = sblocks_for_recheck +
1157                                                        mirror_index;
1158                                         break;
1159                                 }
1160                         }
1161                         if (!sblock_other)
1162                                 success = 0;
1163                 }
1164
1165                 if (sctx->is_dev_replace) {
1166                         /*
1167                          * did not find a mirror to fetch the page
1168                          * from. scrub_write_page_to_dev_replace()
1169                          * handles this case (page->io_error), by
1170                          * filling the block with zeros before
1171                          * submitting the write request
1172                          */
1173                         if (!sblock_other)
1174                                 sblock_other = sblock_bad;
1175
1176                         if (scrub_write_page_to_dev_replace(sblock_other,
1177                                                             page_num) != 0) {
1178                                 btrfs_dev_replace_stats_inc(
1179                                         &sctx->dev_root->
1180                                         fs_info->dev_replace.
1181                                         num_write_errors);
1182                                 success = 0;
1183                         }
1184                 } else if (sblock_other) {
1185                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1186                                                                sblock_other,
1187                                                                page_num, 0);
1188                         if (0 == ret)
1189                                 page_bad->io_error = 0;
1190                         else
1191                                 success = 0;
1192                 }
1193         }
1194
1195         if (success && !sctx->is_dev_replace) {
1196                 if (is_metadata || have_csum) {
1197                         /*
1198                          * need to verify the checksum now that all
1199                          * sectors on disk are repaired (the write
1200                          * request for data to be repaired is on its way).
1201                          * Just be lazy and use scrub_recheck_block()
1202                          * which re-reads the data before the checksum
1203                          * is verified, but most likely the data comes out
1204                          * of the page cache.
1205                          */
1206                         scrub_recheck_block(fs_info, sblock_bad, 1);
1207                         if (!sblock_bad->header_error &&
1208                             !sblock_bad->checksum_error &&
1209                             sblock_bad->no_io_error_seen)
1210                                 goto corrected_error;
1211                         else
1212                                 goto did_not_correct_error;
1213                 } else {
1214 corrected_error:
1215                         spin_lock(&sctx->stat_lock);
1216                         sctx->stat.corrected_errors++;
1217                         sblock_to_check->data_corrected = 1;
1218                         spin_unlock(&sctx->stat_lock);
1219                         btrfs_err_rl_in_rcu(fs_info,
1220                                 "fixed up error at logical %llu on dev %s",
1221                                 logical, rcu_str_deref(dev->name));
1222                 }
1223         } else {
1224 did_not_correct_error:
1225                 spin_lock(&sctx->stat_lock);
1226                 sctx->stat.uncorrectable_errors++;
1227                 spin_unlock(&sctx->stat_lock);
1228                 btrfs_err_rl_in_rcu(fs_info,
1229                         "unable to fixup (regular) error at logical %llu on dev %s",
1230                         logical, rcu_str_deref(dev->name));
1231         }
1232
1233 out:
1234         if (sblocks_for_recheck) {
1235                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1236                      mirror_index++) {
1237                         struct scrub_block *sblock = sblocks_for_recheck +
1238                                                      mirror_index;
1239                         struct scrub_recover *recover;
1240                         int page_index;
1241
1242                         for (page_index = 0; page_index < sblock->page_count;
1243                              page_index++) {
1244                                 sblock->pagev[page_index]->sblock = NULL;
1245                                 recover = sblock->pagev[page_index]->recover;
1246                                 if (recover) {
1247                                         scrub_put_recover(recover);
1248                                         sblock->pagev[page_index]->recover =
1249                                                                         NULL;
1250                                 }
1251                                 scrub_page_put(sblock->pagev[page_index]);
1252                         }
1253                 }
1254                 kfree(sblocks_for_recheck);
1255         }
1256
1257         return 0;
1258 }
1259
1260 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1261 {
1262         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1263                 return 2;
1264         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1265                 return 3;
1266         else
1267                 return (int)bbio->num_stripes;
1268 }
1269
1270 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1271                                                  u64 *raid_map,
1272                                                  u64 mapped_length,
1273                                                  int nstripes, int mirror,
1274                                                  int *stripe_index,
1275                                                  u64 *stripe_offset)
1276 {
1277         int i;
1278
1279         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1280                 /* RAID5/6 */
1281                 for (i = 0; i < nstripes; i++) {
1282                         if (raid_map[i] == RAID6_Q_STRIPE ||
1283                             raid_map[i] == RAID5_P_STRIPE)
1284                                 continue;
1285
1286                         if (logical >= raid_map[i] &&
1287                             logical < raid_map[i] + mapped_length)
1288                                 break;
1289                 }
1290
1291                 *stripe_index = i;
1292                 *stripe_offset = logical - raid_map[i];
1293         } else {
1294                 /* The other RAID type */
1295                 *stripe_index = mirror;
1296                 *stripe_offset = 0;
1297         }
1298 }
1299
1300 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1301                                      struct scrub_block *sblocks_for_recheck)
1302 {
1303         struct scrub_ctx *sctx = original_sblock->sctx;
1304         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
1305         u64 length = original_sblock->page_count * PAGE_SIZE;
1306         u64 logical = original_sblock->pagev[0]->logical;
1307         u64 generation = original_sblock->pagev[0]->generation;
1308         u64 flags = original_sblock->pagev[0]->flags;
1309         u64 have_csum = original_sblock->pagev[0]->have_csum;
1310         struct scrub_recover *recover;
1311         struct btrfs_bio *bbio;
1312         u64 sublen;
1313         u64 mapped_length;
1314         u64 stripe_offset;
1315         int stripe_index;
1316         int page_index = 0;
1317         int mirror_index;
1318         int nmirrors;
1319         int ret;
1320
1321         /*
1322          * note: the two members refs and outstanding_pages
1323          * are not used (and not set) in the blocks that are used for
1324          * the recheck procedure
1325          */
1326
1327         while (length > 0) {
1328                 sublen = min_t(u64, length, PAGE_SIZE);
1329                 mapped_length = sublen;
1330                 bbio = NULL;
1331
1332                 /*
1333                  * with a length of PAGE_SIZE, each returned stripe
1334                  * represents one mirror
1335                  */
1336                 ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical,
1337                                        &mapped_length, &bbio, 0, 1);
1338                 if (ret || !bbio || mapped_length < sublen) {
1339                         btrfs_put_bbio(bbio);
1340                         return -EIO;
1341                 }
1342
1343                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1344                 if (!recover) {
1345                         btrfs_put_bbio(bbio);
1346                         return -ENOMEM;
1347                 }
1348
1349                 atomic_set(&recover->refs, 1);
1350                 recover->bbio = bbio;
1351                 recover->map_length = mapped_length;
1352
1353                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1354
1355                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1356
1357                 for (mirror_index = 0; mirror_index < nmirrors;
1358                      mirror_index++) {
1359                         struct scrub_block *sblock;
1360                         struct scrub_page *page;
1361
1362                         sblock = sblocks_for_recheck + mirror_index;
1363                         sblock->sctx = sctx;
1364
1365                         page = kzalloc(sizeof(*page), GFP_NOFS);
1366                         if (!page) {
1367 leave_nomem:
1368                                 spin_lock(&sctx->stat_lock);
1369                                 sctx->stat.malloc_errors++;
1370                                 spin_unlock(&sctx->stat_lock);
1371                                 scrub_put_recover(recover);
1372                                 return -ENOMEM;
1373                         }
1374                         scrub_page_get(page);
1375                         sblock->pagev[page_index] = page;
1376                         page->sblock = sblock;
1377                         page->flags = flags;
1378                         page->generation = generation;
1379                         page->logical = logical;
1380                         page->have_csum = have_csum;
1381                         if (have_csum)
1382                                 memcpy(page->csum,
1383                                        original_sblock->pagev[0]->csum,
1384                                        sctx->csum_size);
1385
1386                         scrub_stripe_index_and_offset(logical,
1387                                                       bbio->map_type,
1388                                                       bbio->raid_map,
1389                                                       mapped_length,
1390                                                       bbio->num_stripes -
1391                                                       bbio->num_tgtdevs,
1392                                                       mirror_index,
1393                                                       &stripe_index,
1394                                                       &stripe_offset);
1395                         page->physical = bbio->stripes[stripe_index].physical +
1396                                          stripe_offset;
1397                         page->dev = bbio->stripes[stripe_index].dev;
1398
1399                         BUG_ON(page_index >= original_sblock->page_count);
1400                         page->physical_for_dev_replace =
1401                                 original_sblock->pagev[page_index]->
1402                                 physical_for_dev_replace;
1403                         /* for missing devices, dev->bdev is NULL */
1404                         page->mirror_num = mirror_index + 1;
1405                         sblock->page_count++;
1406                         page->page = alloc_page(GFP_NOFS);
1407                         if (!page->page)
1408                                 goto leave_nomem;
1409
1410                         scrub_get_recover(recover);
1411                         page->recover = recover;
1412                 }
1413                 scrub_put_recover(recover);
1414                 length -= sublen;
1415                 logical += sublen;
1416                 page_index++;
1417         }
1418
1419         return 0;
1420 }
1421
1422 struct scrub_bio_ret {
1423         struct completion event;
1424         int error;
1425 };
1426
1427 static void scrub_bio_wait_endio(struct bio *bio)
1428 {
1429         struct scrub_bio_ret *ret = bio->bi_private;
1430
1431         ret->error = bio->bi_error;
1432         complete(&ret->event);
1433 }
1434
1435 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
1436 {
1437         return page->recover &&
1438                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
1439 }
1440
1441 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1442                                         struct bio *bio,
1443                                         struct scrub_page *page)
1444 {
1445         struct scrub_bio_ret done;
1446         int ret;
1447
1448         init_completion(&done.event);
1449         done.error = 0;
1450         bio->bi_iter.bi_sector = page->logical >> 9;
1451         bio->bi_private = &done;
1452         bio->bi_end_io = scrub_bio_wait_endio;
1453
1454         ret = raid56_parity_recover(fs_info->fs_root, bio, page->recover->bbio,
1455                                     page->recover->map_length,
1456                                     page->mirror_num, 0);
1457         if (ret)
1458                 return ret;
1459
1460         wait_for_completion(&done.event);
1461         if (done.error)
1462                 return -EIO;
1463
1464         return 0;
1465 }
1466
1467 /*
1468  * this function will check the on disk data for checksum errors, header
1469  * errors and read I/O errors. If any I/O errors happen, the exact pages
1470  * which are errored are marked as being bad. The goal is to enable scrub
1471  * to take those pages that are not errored from all the mirrors so that
1472  * the pages that are errored in the just handled mirror can be repaired.
1473  */
1474 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1475                                 struct scrub_block *sblock,
1476                                 int retry_failed_mirror)
1477 {
1478         int page_num;
1479
1480         sblock->no_io_error_seen = 1;
1481
1482         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1483                 struct bio *bio;
1484                 struct scrub_page *page = sblock->pagev[page_num];
1485
1486                 if (page->dev->bdev == NULL) {
1487                         page->io_error = 1;
1488                         sblock->no_io_error_seen = 0;
1489                         continue;
1490                 }
1491
1492                 WARN_ON(!page->page);
1493                 bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1494                 if (!bio) {
1495                         page->io_error = 1;
1496                         sblock->no_io_error_seen = 0;
1497                         continue;
1498                 }
1499                 bio->bi_bdev = page->dev->bdev;
1500
1501                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1502                 if (!retry_failed_mirror && scrub_is_page_on_raid56(page)) {
1503                         if (scrub_submit_raid56_bio_wait(fs_info, bio, page))
1504                                 sblock->no_io_error_seen = 0;
1505                 } else {
1506                         bio->bi_iter.bi_sector = page->physical >> 9;
1507                         bio_set_op_attrs(bio, REQ_OP_READ, 0);
1508
1509                         if (btrfsic_submit_bio_wait(bio))
1510                                 sblock->no_io_error_seen = 0;
1511                 }
1512
1513                 bio_put(bio);
1514         }
1515
1516         if (sblock->no_io_error_seen)
1517                 scrub_recheck_block_checksum(sblock);
1518 }
1519
1520 static inline int scrub_check_fsid(u8 fsid[],
1521                                    struct scrub_page *spage)
1522 {
1523         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1524         int ret;
1525
1526         ret = memcmp(fsid, fs_devices->fsid, BTRFS_UUID_SIZE);
1527         return !ret;
1528 }
1529
1530 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1531 {
1532         sblock->header_error = 0;
1533         sblock->checksum_error = 0;
1534         sblock->generation_error = 0;
1535
1536         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1537                 scrub_checksum_data(sblock);
1538         else
1539                 scrub_checksum_tree_block(sblock);
1540 }
1541
1542 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1543                                              struct scrub_block *sblock_good)
1544 {
1545         int page_num;
1546         int ret = 0;
1547
1548         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1549                 int ret_sub;
1550
1551                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1552                                                            sblock_good,
1553                                                            page_num, 1);
1554                 if (ret_sub)
1555                         ret = ret_sub;
1556         }
1557
1558         return ret;
1559 }
1560
1561 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1562                                             struct scrub_block *sblock_good,
1563                                             int page_num, int force_write)
1564 {
1565         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1566         struct scrub_page *page_good = sblock_good->pagev[page_num];
1567
1568         BUG_ON(page_bad->page == NULL);
1569         BUG_ON(page_good->page == NULL);
1570         if (force_write || sblock_bad->header_error ||
1571             sblock_bad->checksum_error || page_bad->io_error) {
1572                 struct bio *bio;
1573                 int ret;
1574
1575                 if (!page_bad->dev->bdev) {
1576                         btrfs_warn_rl(sblock_bad->sctx->dev_root->fs_info,
1577                                 "scrub_repair_page_from_good_copy(bdev == NULL) "
1578                                 "is unexpected");
1579                         return -EIO;
1580                 }
1581
1582                 bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1583                 if (!bio)
1584                         return -EIO;
1585                 bio->bi_bdev = page_bad->dev->bdev;
1586                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1587                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
1588
1589                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1590                 if (PAGE_SIZE != ret) {
1591                         bio_put(bio);
1592                         return -EIO;
1593                 }
1594
1595                 if (btrfsic_submit_bio_wait(bio)) {
1596                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1597                                 BTRFS_DEV_STAT_WRITE_ERRS);
1598                         btrfs_dev_replace_stats_inc(
1599                                 &sblock_bad->sctx->dev_root->fs_info->
1600                                 dev_replace.num_write_errors);
1601                         bio_put(bio);
1602                         return -EIO;
1603                 }
1604                 bio_put(bio);
1605         }
1606
1607         return 0;
1608 }
1609
1610 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1611 {
1612         int page_num;
1613
1614         /*
1615          * This block is used for the check of the parity on the source device,
1616          * so the data needn't be written into the destination device.
1617          */
1618         if (sblock->sparity)
1619                 return;
1620
1621         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1622                 int ret;
1623
1624                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1625                 if (ret)
1626                         btrfs_dev_replace_stats_inc(
1627                                 &sblock->sctx->dev_root->fs_info->dev_replace.
1628                                 num_write_errors);
1629         }
1630 }
1631
1632 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1633                                            int page_num)
1634 {
1635         struct scrub_page *spage = sblock->pagev[page_num];
1636
1637         BUG_ON(spage->page == NULL);
1638         if (spage->io_error) {
1639                 void *mapped_buffer = kmap_atomic(spage->page);
1640
1641                 memset(mapped_buffer, 0, PAGE_SIZE);
1642                 flush_dcache_page(spage->page);
1643                 kunmap_atomic(mapped_buffer);
1644         }
1645         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1646 }
1647
1648 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1649                                     struct scrub_page *spage)
1650 {
1651         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1652         struct scrub_bio *sbio;
1653         int ret;
1654
1655         mutex_lock(&wr_ctx->wr_lock);
1656 again:
1657         if (!wr_ctx->wr_curr_bio) {
1658                 wr_ctx->wr_curr_bio = kzalloc(sizeof(*wr_ctx->wr_curr_bio),
1659                                               GFP_KERNEL);
1660                 if (!wr_ctx->wr_curr_bio) {
1661                         mutex_unlock(&wr_ctx->wr_lock);
1662                         return -ENOMEM;
1663                 }
1664                 wr_ctx->wr_curr_bio->sctx = sctx;
1665                 wr_ctx->wr_curr_bio->page_count = 0;
1666         }
1667         sbio = wr_ctx->wr_curr_bio;
1668         if (sbio->page_count == 0) {
1669                 struct bio *bio;
1670
1671                 sbio->physical = spage->physical_for_dev_replace;
1672                 sbio->logical = spage->logical;
1673                 sbio->dev = wr_ctx->tgtdev;
1674                 bio = sbio->bio;
1675                 if (!bio) {
1676                         bio = btrfs_io_bio_alloc(GFP_KERNEL,
1677                                         wr_ctx->pages_per_wr_bio);
1678                         if (!bio) {
1679                                 mutex_unlock(&wr_ctx->wr_lock);
1680                                 return -ENOMEM;
1681                         }
1682                         sbio->bio = bio;
1683                 }
1684
1685                 bio->bi_private = sbio;
1686                 bio->bi_end_io = scrub_wr_bio_end_io;
1687                 bio->bi_bdev = sbio->dev->bdev;
1688                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1689                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
1690                 sbio->err = 0;
1691         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1692                    spage->physical_for_dev_replace ||
1693                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1694                    spage->logical) {
1695                 scrub_wr_submit(sctx);
1696                 goto again;
1697         }
1698
1699         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1700         if (ret != PAGE_SIZE) {
1701                 if (sbio->page_count < 1) {
1702                         bio_put(sbio->bio);
1703                         sbio->bio = NULL;
1704                         mutex_unlock(&wr_ctx->wr_lock);
1705                         return -EIO;
1706                 }
1707                 scrub_wr_submit(sctx);
1708                 goto again;
1709         }
1710
1711         sbio->pagev[sbio->page_count] = spage;
1712         scrub_page_get(spage);
1713         sbio->page_count++;
1714         if (sbio->page_count == wr_ctx->pages_per_wr_bio)
1715                 scrub_wr_submit(sctx);
1716         mutex_unlock(&wr_ctx->wr_lock);
1717
1718         return 0;
1719 }
1720
1721 static void scrub_wr_submit(struct scrub_ctx *sctx)
1722 {
1723         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1724         struct scrub_bio *sbio;
1725
1726         if (!wr_ctx->wr_curr_bio)
1727                 return;
1728
1729         sbio = wr_ctx->wr_curr_bio;
1730         wr_ctx->wr_curr_bio = NULL;
1731         WARN_ON(!sbio->bio->bi_bdev);
1732         scrub_pending_bio_inc(sctx);
1733         /* process all writes in a single worker thread. Then the block layer
1734          * orders the requests before sending them to the driver which
1735          * doubled the write performance on spinning disks when measured
1736          * with Linux 3.5 */
1737         btrfsic_submit_bio(sbio->bio);
1738 }
1739
1740 static void scrub_wr_bio_end_io(struct bio *bio)
1741 {
1742         struct scrub_bio *sbio = bio->bi_private;
1743         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
1744
1745         sbio->err = bio->bi_error;
1746         sbio->bio = bio;
1747
1748         btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
1749                          scrub_wr_bio_end_io_worker, NULL, NULL);
1750         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1751 }
1752
1753 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1754 {
1755         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1756         struct scrub_ctx *sctx = sbio->sctx;
1757         int i;
1758
1759         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1760         if (sbio->err) {
1761                 struct btrfs_dev_replace *dev_replace =
1762                         &sbio->sctx->dev_root->fs_info->dev_replace;
1763
1764                 for (i = 0; i < sbio->page_count; i++) {
1765                         struct scrub_page *spage = sbio->pagev[i];
1766
1767                         spage->io_error = 1;
1768                         btrfs_dev_replace_stats_inc(&dev_replace->
1769                                                     num_write_errors);
1770                 }
1771         }
1772
1773         for (i = 0; i < sbio->page_count; i++)
1774                 scrub_page_put(sbio->pagev[i]);
1775
1776         bio_put(sbio->bio);
1777         kfree(sbio);
1778         scrub_pending_bio_dec(sctx);
1779 }
1780
1781 static int scrub_checksum(struct scrub_block *sblock)
1782 {
1783         u64 flags;
1784         int ret;
1785
1786         /*
1787          * No need to initialize these stats currently,
1788          * because this function only use return value
1789          * instead of these stats value.
1790          *
1791          * Todo:
1792          * always use stats
1793          */
1794         sblock->header_error = 0;
1795         sblock->generation_error = 0;
1796         sblock->checksum_error = 0;
1797
1798         WARN_ON(sblock->page_count < 1);
1799         flags = sblock->pagev[0]->flags;
1800         ret = 0;
1801         if (flags & BTRFS_EXTENT_FLAG_DATA)
1802                 ret = scrub_checksum_data(sblock);
1803         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1804                 ret = scrub_checksum_tree_block(sblock);
1805         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1806                 (void)scrub_checksum_super(sblock);
1807         else
1808                 WARN_ON(1);
1809         if (ret)
1810                 scrub_handle_errored_block(sblock);
1811
1812         return ret;
1813 }
1814
1815 static int scrub_checksum_data(struct scrub_block *sblock)
1816 {
1817         struct scrub_ctx *sctx = sblock->sctx;
1818         u8 csum[BTRFS_CSUM_SIZE];
1819         u8 *on_disk_csum;
1820         struct page *page;
1821         void *buffer;
1822         u32 crc = ~(u32)0;
1823         u64 len;
1824         int index;
1825
1826         BUG_ON(sblock->page_count < 1);
1827         if (!sblock->pagev[0]->have_csum)
1828                 return 0;
1829
1830         on_disk_csum = sblock->pagev[0]->csum;
1831         page = sblock->pagev[0]->page;
1832         buffer = kmap_atomic(page);
1833
1834         len = sctx->sectorsize;
1835         index = 0;
1836         for (;;) {
1837                 u64 l = min_t(u64, len, PAGE_SIZE);
1838
1839                 crc = btrfs_csum_data(buffer, crc, l);
1840                 kunmap_atomic(buffer);
1841                 len -= l;
1842                 if (len == 0)
1843                         break;
1844                 index++;
1845                 BUG_ON(index >= sblock->page_count);
1846                 BUG_ON(!sblock->pagev[index]->page);
1847                 page = sblock->pagev[index]->page;
1848                 buffer = kmap_atomic(page);
1849         }
1850
1851         btrfs_csum_final(crc, csum);
1852         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1853                 sblock->checksum_error = 1;
1854
1855         return sblock->checksum_error;
1856 }
1857
1858 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1859 {
1860         struct scrub_ctx *sctx = sblock->sctx;
1861         struct btrfs_header *h;
1862         struct btrfs_root *root = sctx->dev_root;
1863         struct btrfs_fs_info *fs_info = root->fs_info;
1864         u8 calculated_csum[BTRFS_CSUM_SIZE];
1865         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1866         struct page *page;
1867         void *mapped_buffer;
1868         u64 mapped_size;
1869         void *p;
1870         u32 crc = ~(u32)0;
1871         u64 len;
1872         int index;
1873
1874         BUG_ON(sblock->page_count < 1);
1875         page = sblock->pagev[0]->page;
1876         mapped_buffer = kmap_atomic(page);
1877         h = (struct btrfs_header *)mapped_buffer;
1878         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1879
1880         /*
1881          * we don't use the getter functions here, as we
1882          * a) don't have an extent buffer and
1883          * b) the page is already kmapped
1884          */
1885         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1886                 sblock->header_error = 1;
1887
1888         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
1889                 sblock->header_error = 1;
1890                 sblock->generation_error = 1;
1891         }
1892
1893         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
1894                 sblock->header_error = 1;
1895
1896         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1897                    BTRFS_UUID_SIZE))
1898                 sblock->header_error = 1;
1899
1900         len = sctx->nodesize - BTRFS_CSUM_SIZE;
1901         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1902         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1903         index = 0;
1904         for (;;) {
1905                 u64 l = min_t(u64, len, mapped_size);
1906
1907                 crc = btrfs_csum_data(p, crc, l);
1908                 kunmap_atomic(mapped_buffer);
1909                 len -= l;
1910                 if (len == 0)
1911                         break;
1912                 index++;
1913                 BUG_ON(index >= sblock->page_count);
1914                 BUG_ON(!sblock->pagev[index]->page);
1915                 page = sblock->pagev[index]->page;
1916                 mapped_buffer = kmap_atomic(page);
1917                 mapped_size = PAGE_SIZE;
1918                 p = mapped_buffer;
1919         }
1920
1921         btrfs_csum_final(crc, calculated_csum);
1922         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1923                 sblock->checksum_error = 1;
1924
1925         return sblock->header_error || sblock->checksum_error;
1926 }
1927
1928 static int scrub_checksum_super(struct scrub_block *sblock)
1929 {
1930         struct btrfs_super_block *s;
1931         struct scrub_ctx *sctx = sblock->sctx;
1932         u8 calculated_csum[BTRFS_CSUM_SIZE];
1933         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1934         struct page *page;
1935         void *mapped_buffer;
1936         u64 mapped_size;
1937         void *p;
1938         u32 crc = ~(u32)0;
1939         int fail_gen = 0;
1940         int fail_cor = 0;
1941         u64 len;
1942         int index;
1943
1944         BUG_ON(sblock->page_count < 1);
1945         page = sblock->pagev[0]->page;
1946         mapped_buffer = kmap_atomic(page);
1947         s = (struct btrfs_super_block *)mapped_buffer;
1948         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1949
1950         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1951                 ++fail_cor;
1952
1953         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1954                 ++fail_gen;
1955
1956         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1957                 ++fail_cor;
1958
1959         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1960         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1961         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1962         index = 0;
1963         for (;;) {
1964                 u64 l = min_t(u64, len, mapped_size);
1965
1966                 crc = btrfs_csum_data(p, crc, l);
1967                 kunmap_atomic(mapped_buffer);
1968                 len -= l;
1969                 if (len == 0)
1970                         break;
1971                 index++;
1972                 BUG_ON(index >= sblock->page_count);
1973                 BUG_ON(!sblock->pagev[index]->page);
1974                 page = sblock->pagev[index]->page;
1975                 mapped_buffer = kmap_atomic(page);
1976                 mapped_size = PAGE_SIZE;
1977                 p = mapped_buffer;
1978         }
1979
1980         btrfs_csum_final(crc, calculated_csum);
1981         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1982                 ++fail_cor;
1983
1984         if (fail_cor + fail_gen) {
1985                 /*
1986                  * if we find an error in a super block, we just report it.
1987                  * They will get written with the next transaction commit
1988                  * anyway
1989                  */
1990                 spin_lock(&sctx->stat_lock);
1991                 ++sctx->stat.super_errors;
1992                 spin_unlock(&sctx->stat_lock);
1993                 if (fail_cor)
1994                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1995                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1996                 else
1997                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1998                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1999         }
2000
2001         return fail_cor + fail_gen;
2002 }
2003
2004 static void scrub_block_get(struct scrub_block *sblock)
2005 {
2006         atomic_inc(&sblock->refs);
2007 }
2008
2009 static void scrub_block_put(struct scrub_block *sblock)
2010 {
2011         if (atomic_dec_and_test(&sblock->refs)) {
2012                 int i;
2013
2014                 if (sblock->sparity)
2015                         scrub_parity_put(sblock->sparity);
2016
2017                 for (i = 0; i < sblock->page_count; i++)
2018                         scrub_page_put(sblock->pagev[i]);
2019                 kfree(sblock);
2020         }
2021 }
2022
2023 static void scrub_page_get(struct scrub_page *spage)
2024 {
2025         atomic_inc(&spage->refs);
2026 }
2027
2028 static void scrub_page_put(struct scrub_page *spage)
2029 {
2030         if (atomic_dec_and_test(&spage->refs)) {
2031                 if (spage->page)
2032                         __free_page(spage->page);
2033                 kfree(spage);
2034         }
2035 }
2036
2037 static void scrub_submit(struct scrub_ctx *sctx)
2038 {
2039         struct scrub_bio *sbio;
2040
2041         if (sctx->curr == -1)
2042                 return;
2043
2044         sbio = sctx->bios[sctx->curr];
2045         sctx->curr = -1;
2046         scrub_pending_bio_inc(sctx);
2047         btrfsic_submit_bio(sbio->bio);
2048 }
2049
2050 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2051                                     struct scrub_page *spage)
2052 {
2053         struct scrub_block *sblock = spage->sblock;
2054         struct scrub_bio *sbio;
2055         int ret;
2056
2057 again:
2058         /*
2059          * grab a fresh bio or wait for one to become available
2060          */
2061         while (sctx->curr == -1) {
2062                 spin_lock(&sctx->list_lock);
2063                 sctx->curr = sctx->first_free;
2064                 if (sctx->curr != -1) {
2065                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2066                         sctx->bios[sctx->curr]->next_free = -1;
2067                         sctx->bios[sctx->curr]->page_count = 0;
2068                         spin_unlock(&sctx->list_lock);
2069                 } else {
2070                         spin_unlock(&sctx->list_lock);
2071                         wait_event(sctx->list_wait, sctx->first_free != -1);
2072                 }
2073         }
2074         sbio = sctx->bios[sctx->curr];
2075         if (sbio->page_count == 0) {
2076                 struct bio *bio;
2077
2078                 sbio->physical = spage->physical;
2079                 sbio->logical = spage->logical;
2080                 sbio->dev = spage->dev;
2081                 bio = sbio->bio;
2082                 if (!bio) {
2083                         bio = btrfs_io_bio_alloc(GFP_KERNEL,
2084                                         sctx->pages_per_rd_bio);
2085                         if (!bio)
2086                                 return -ENOMEM;
2087                         sbio->bio = bio;
2088                 }
2089
2090                 bio->bi_private = sbio;
2091                 bio->bi_end_io = scrub_bio_end_io;
2092                 bio->bi_bdev = sbio->dev->bdev;
2093                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2094                 bio_set_op_attrs(bio, REQ_OP_READ, 0);
2095                 sbio->err = 0;
2096         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2097                    spage->physical ||
2098                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2099                    spage->logical ||
2100                    sbio->dev != spage->dev) {
2101                 scrub_submit(sctx);
2102                 goto again;
2103         }
2104
2105         sbio->pagev[sbio->page_count] = spage;
2106         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2107         if (ret != PAGE_SIZE) {
2108                 if (sbio->page_count < 1) {
2109                         bio_put(sbio->bio);
2110                         sbio->bio = NULL;
2111                         return -EIO;
2112                 }
2113                 scrub_submit(sctx);
2114                 goto again;
2115         }
2116
2117         scrub_block_get(sblock); /* one for the page added to the bio */
2118         atomic_inc(&sblock->outstanding_pages);
2119         sbio->page_count++;
2120         if (sbio->page_count == sctx->pages_per_rd_bio)
2121                 scrub_submit(sctx);
2122
2123         return 0;
2124 }
2125
2126 static void scrub_missing_raid56_end_io(struct bio *bio)
2127 {
2128         struct scrub_block *sblock = bio->bi_private;
2129         struct btrfs_fs_info *fs_info = sblock->sctx->dev_root->fs_info;
2130
2131         if (bio->bi_error)
2132                 sblock->no_io_error_seen = 0;
2133
2134         bio_put(bio);
2135
2136         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2137 }
2138
2139 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2140 {
2141         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2142         struct scrub_ctx *sctx = sblock->sctx;
2143         u64 logical;
2144         struct btrfs_device *dev;
2145
2146         logical = sblock->pagev[0]->logical;
2147         dev = sblock->pagev[0]->dev;
2148
2149         if (sblock->no_io_error_seen)
2150                 scrub_recheck_block_checksum(sblock);
2151
2152         if (!sblock->no_io_error_seen) {
2153                 spin_lock(&sctx->stat_lock);
2154                 sctx->stat.read_errors++;
2155                 spin_unlock(&sctx->stat_lock);
2156                 btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
2157                         "IO error rebuilding logical %llu for dev %s",
2158                         logical, rcu_str_deref(dev->name));
2159         } else if (sblock->header_error || sblock->checksum_error) {
2160                 spin_lock(&sctx->stat_lock);
2161                 sctx->stat.uncorrectable_errors++;
2162                 spin_unlock(&sctx->stat_lock);
2163                 btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
2164                         "failed to rebuild valid logical %llu for dev %s",
2165                         logical, rcu_str_deref(dev->name));
2166         } else {
2167                 scrub_write_block_to_dev_replace(sblock);
2168         }
2169
2170         scrub_block_put(sblock);
2171
2172         if (sctx->is_dev_replace &&
2173             atomic_read(&sctx->wr_ctx.flush_all_writes)) {
2174                 mutex_lock(&sctx->wr_ctx.wr_lock);
2175                 scrub_wr_submit(sctx);
2176                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2177         }
2178
2179         scrub_pending_bio_dec(sctx);
2180 }
2181
2182 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2183 {
2184         struct scrub_ctx *sctx = sblock->sctx;
2185         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
2186         u64 length = sblock->page_count * PAGE_SIZE;
2187         u64 logical = sblock->pagev[0]->logical;
2188         struct btrfs_bio *bbio = NULL;
2189         struct bio *bio;
2190         struct btrfs_raid_bio *rbio;
2191         int ret;
2192         int i;
2193
2194         ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
2195                                &bbio, 0, 1);
2196         if (ret || !bbio || !bbio->raid_map)
2197                 goto bbio_out;
2198
2199         if (WARN_ON(!sctx->is_dev_replace ||
2200                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2201                 /*
2202                  * We shouldn't be scrubbing a missing device. Even for dev
2203                  * replace, we should only get here for RAID 5/6. We either
2204                  * managed to mount something with no mirrors remaining or
2205                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2206                  */
2207                 goto bbio_out;
2208         }
2209
2210         bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
2211         if (!bio)
2212                 goto bbio_out;
2213
2214         bio->bi_iter.bi_sector = logical >> 9;
2215         bio->bi_private = sblock;
2216         bio->bi_end_io = scrub_missing_raid56_end_io;
2217
2218         rbio = raid56_alloc_missing_rbio(sctx->dev_root, bio, bbio, length);
2219         if (!rbio)
2220                 goto rbio_out;
2221
2222         for (i = 0; i < sblock->page_count; i++) {
2223                 struct scrub_page *spage = sblock->pagev[i];
2224
2225                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2226         }
2227
2228         btrfs_init_work(&sblock->work, btrfs_scrub_helper,
2229                         scrub_missing_raid56_worker, NULL, NULL);
2230         scrub_block_get(sblock);
2231         scrub_pending_bio_inc(sctx);
2232         raid56_submit_missing_rbio(rbio);
2233         return;
2234
2235 rbio_out:
2236         bio_put(bio);
2237 bbio_out:
2238         btrfs_put_bbio(bbio);
2239         spin_lock(&sctx->stat_lock);
2240         sctx->stat.malloc_errors++;
2241         spin_unlock(&sctx->stat_lock);
2242 }
2243
2244 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2245                        u64 physical, struct btrfs_device *dev, u64 flags,
2246                        u64 gen, int mirror_num, u8 *csum, int force,
2247                        u64 physical_for_dev_replace)
2248 {
2249         struct scrub_block *sblock;
2250         int index;
2251
2252         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2253         if (!sblock) {
2254                 spin_lock(&sctx->stat_lock);
2255                 sctx->stat.malloc_errors++;
2256                 spin_unlock(&sctx->stat_lock);
2257                 return -ENOMEM;
2258         }
2259
2260         /* one ref inside this function, plus one for each page added to
2261          * a bio later on */
2262         atomic_set(&sblock->refs, 1);
2263         sblock->sctx = sctx;
2264         sblock->no_io_error_seen = 1;
2265
2266         for (index = 0; len > 0; index++) {
2267                 struct scrub_page *spage;
2268                 u64 l = min_t(u64, len, PAGE_SIZE);
2269
2270                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2271                 if (!spage) {
2272 leave_nomem:
2273                         spin_lock(&sctx->stat_lock);
2274                         sctx->stat.malloc_errors++;
2275                         spin_unlock(&sctx->stat_lock);
2276                         scrub_block_put(sblock);
2277                         return -ENOMEM;
2278                 }
2279                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2280                 scrub_page_get(spage);
2281                 sblock->pagev[index] = spage;
2282                 spage->sblock = sblock;
2283                 spage->dev = dev;
2284                 spage->flags = flags;
2285                 spage->generation = gen;
2286                 spage->logical = logical;
2287                 spage->physical = physical;
2288                 spage->physical_for_dev_replace = physical_for_dev_replace;
2289                 spage->mirror_num = mirror_num;
2290                 if (csum) {
2291                         spage->have_csum = 1;
2292                         memcpy(spage->csum, csum, sctx->csum_size);
2293                 } else {
2294                         spage->have_csum = 0;
2295                 }
2296                 sblock->page_count++;
2297                 spage->page = alloc_page(GFP_KERNEL);
2298                 if (!spage->page)
2299                         goto leave_nomem;
2300                 len -= l;
2301                 logical += l;
2302                 physical += l;
2303                 physical_for_dev_replace += l;
2304         }
2305
2306         WARN_ON(sblock->page_count == 0);
2307         if (dev->missing) {
2308                 /*
2309                  * This case should only be hit for RAID 5/6 device replace. See
2310                  * the comment in scrub_missing_raid56_pages() for details.
2311                  */
2312                 scrub_missing_raid56_pages(sblock);
2313         } else {
2314                 for (index = 0; index < sblock->page_count; index++) {
2315                         struct scrub_page *spage = sblock->pagev[index];
2316                         int ret;
2317
2318                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2319                         if (ret) {
2320                                 scrub_block_put(sblock);
2321                                 return ret;
2322                         }
2323                 }
2324
2325                 if (force)
2326                         scrub_submit(sctx);
2327         }
2328
2329         /* last one frees, either here or in bio completion for last page */
2330         scrub_block_put(sblock);
2331         return 0;
2332 }
2333
2334 static void scrub_bio_end_io(struct bio *bio)
2335 {
2336         struct scrub_bio *sbio = bio->bi_private;
2337         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
2338
2339         sbio->err = bio->bi_error;
2340         sbio->bio = bio;
2341
2342         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2343 }
2344
2345 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2346 {
2347         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2348         struct scrub_ctx *sctx = sbio->sctx;
2349         int i;
2350
2351         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2352         if (sbio->err) {
2353                 for (i = 0; i < sbio->page_count; i++) {
2354                         struct scrub_page *spage = sbio->pagev[i];
2355
2356                         spage->io_error = 1;
2357                         spage->sblock->no_io_error_seen = 0;
2358                 }
2359         }
2360
2361         /* now complete the scrub_block items that have all pages completed */
2362         for (i = 0; i < sbio->page_count; i++) {
2363                 struct scrub_page *spage = sbio->pagev[i];
2364                 struct scrub_block *sblock = spage->sblock;
2365
2366                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2367                         scrub_block_complete(sblock);
2368                 scrub_block_put(sblock);
2369         }
2370
2371         bio_put(sbio->bio);
2372         sbio->bio = NULL;
2373         spin_lock(&sctx->list_lock);
2374         sbio->next_free = sctx->first_free;
2375         sctx->first_free = sbio->index;
2376         spin_unlock(&sctx->list_lock);
2377
2378         if (sctx->is_dev_replace &&
2379             atomic_read(&sctx->wr_ctx.flush_all_writes)) {
2380                 mutex_lock(&sctx->wr_ctx.wr_lock);
2381                 scrub_wr_submit(sctx);
2382                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2383         }
2384
2385         scrub_pending_bio_dec(sctx);
2386 }
2387
2388 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2389                                        unsigned long *bitmap,
2390                                        u64 start, u64 len)
2391 {
2392         u32 offset;
2393         int nsectors;
2394         int sectorsize = sparity->sctx->dev_root->sectorsize;
2395
2396         if (len >= sparity->stripe_len) {
2397                 bitmap_set(bitmap, 0, sparity->nsectors);
2398                 return;
2399         }
2400
2401         start -= sparity->logic_start;
2402         start = div_u64_rem(start, sparity->stripe_len, &offset);
2403         offset /= sectorsize;
2404         nsectors = (int)len / sectorsize;
2405
2406         if (offset + nsectors <= sparity->nsectors) {
2407                 bitmap_set(bitmap, offset, nsectors);
2408                 return;
2409         }
2410
2411         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2412         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2413 }
2414
2415 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2416                                                    u64 start, u64 len)
2417 {
2418         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2419 }
2420
2421 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2422                                                   u64 start, u64 len)
2423 {
2424         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2425 }
2426
2427 static void scrub_block_complete(struct scrub_block *sblock)
2428 {
2429         int corrupted = 0;
2430
2431         if (!sblock->no_io_error_seen) {
2432                 corrupted = 1;
2433                 scrub_handle_errored_block(sblock);
2434         } else {
2435                 /*
2436                  * if has checksum error, write via repair mechanism in
2437                  * dev replace case, otherwise write here in dev replace
2438                  * case.
2439                  */
2440                 corrupted = scrub_checksum(sblock);
2441                 if (!corrupted && sblock->sctx->is_dev_replace)
2442                         scrub_write_block_to_dev_replace(sblock);
2443         }
2444
2445         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2446                 u64 start = sblock->pagev[0]->logical;
2447                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2448                           PAGE_SIZE;
2449
2450                 scrub_parity_mark_sectors_error(sblock->sparity,
2451                                                 start, end - start);
2452         }
2453 }
2454
2455 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2456 {
2457         struct btrfs_ordered_sum *sum = NULL;
2458         unsigned long index;
2459         unsigned long num_sectors;
2460
2461         while (!list_empty(&sctx->csum_list)) {
2462                 sum = list_first_entry(&sctx->csum_list,
2463                                        struct btrfs_ordered_sum, list);
2464                 if (sum->bytenr > logical)
2465                         return 0;
2466                 if (sum->bytenr + sum->len > logical)
2467                         break;
2468
2469                 ++sctx->stat.csum_discards;
2470                 list_del(&sum->list);
2471                 kfree(sum);
2472                 sum = NULL;
2473         }
2474         if (!sum)
2475                 return 0;
2476
2477         index = ((u32)(logical - sum->bytenr)) / sctx->sectorsize;
2478         num_sectors = sum->len / sctx->sectorsize;
2479         memcpy(csum, sum->sums + index, sctx->csum_size);
2480         if (index == num_sectors - 1) {
2481                 list_del(&sum->list);
2482                 kfree(sum);
2483         }
2484         return 1;
2485 }
2486
2487 /* scrub extent tries to collect up to 64 kB for each bio */
2488 static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
2489                         u64 physical, struct btrfs_device *dev, u64 flags,
2490                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2491 {
2492         int ret;
2493         u8 csum[BTRFS_CSUM_SIZE];
2494         u32 blocksize;
2495
2496         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2497                 blocksize = sctx->sectorsize;
2498                 spin_lock(&sctx->stat_lock);
2499                 sctx->stat.data_extents_scrubbed++;
2500                 sctx->stat.data_bytes_scrubbed += len;
2501                 spin_unlock(&sctx->stat_lock);
2502         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2503                 blocksize = sctx->nodesize;
2504                 spin_lock(&sctx->stat_lock);
2505                 sctx->stat.tree_extents_scrubbed++;
2506                 sctx->stat.tree_bytes_scrubbed += len;
2507                 spin_unlock(&sctx->stat_lock);
2508         } else {
2509                 blocksize = sctx->sectorsize;
2510                 WARN_ON(1);
2511         }
2512
2513         while (len) {
2514                 u64 l = min_t(u64, len, blocksize);
2515                 int have_csum = 0;
2516
2517                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2518                         /* push csums to sbio */
2519                         have_csum = scrub_find_csum(sctx, logical, csum);
2520                         if (have_csum == 0)
2521                                 ++sctx->stat.no_csum;
2522                         if (sctx->is_dev_replace && !have_csum) {
2523                                 ret = copy_nocow_pages(sctx, logical, l,
2524                                                        mirror_num,
2525                                                       physical_for_dev_replace);
2526                                 goto behind_scrub_pages;
2527                         }
2528                 }
2529                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2530                                   mirror_num, have_csum ? csum : NULL, 0,
2531                                   physical_for_dev_replace);
2532 behind_scrub_pages:
2533                 if (ret)
2534                         return ret;
2535                 len -= l;
2536                 logical += l;
2537                 physical += l;
2538                 physical_for_dev_replace += l;
2539         }
2540         return 0;
2541 }
2542
2543 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2544                                   u64 logical, u64 len,
2545                                   u64 physical, struct btrfs_device *dev,
2546                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2547 {
2548         struct scrub_ctx *sctx = sparity->sctx;
2549         struct scrub_block *sblock;
2550         int index;
2551
2552         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2553         if (!sblock) {
2554                 spin_lock(&sctx->stat_lock);
2555                 sctx->stat.malloc_errors++;
2556                 spin_unlock(&sctx->stat_lock);
2557                 return -ENOMEM;
2558         }
2559
2560         /* one ref inside this function, plus one for each page added to
2561          * a bio later on */
2562         atomic_set(&sblock->refs, 1);
2563         sblock->sctx = sctx;
2564         sblock->no_io_error_seen = 1;
2565         sblock->sparity = sparity;
2566         scrub_parity_get(sparity);
2567
2568         for (index = 0; len > 0; index++) {
2569                 struct scrub_page *spage;
2570                 u64 l = min_t(u64, len, PAGE_SIZE);
2571
2572                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2573                 if (!spage) {
2574 leave_nomem:
2575                         spin_lock(&sctx->stat_lock);
2576                         sctx->stat.malloc_errors++;
2577                         spin_unlock(&sctx->stat_lock);
2578                         scrub_block_put(sblock);
2579                         return -ENOMEM;
2580                 }
2581                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2582                 /* For scrub block */
2583                 scrub_page_get(spage);
2584                 sblock->pagev[index] = spage;
2585                 /* For scrub parity */
2586                 scrub_page_get(spage);
2587                 list_add_tail(&spage->list, &sparity->spages);
2588                 spage->sblock = sblock;
2589                 spage->dev = dev;
2590                 spage->flags = flags;
2591                 spage->generation = gen;
2592                 spage->logical = logical;
2593                 spage->physical = physical;
2594                 spage->mirror_num = mirror_num;
2595                 if (csum) {
2596                         spage->have_csum = 1;
2597                         memcpy(spage->csum, csum, sctx->csum_size);
2598                 } else {
2599                         spage->have_csum = 0;
2600                 }
2601                 sblock->page_count++;
2602                 spage->page = alloc_page(GFP_KERNEL);
2603                 if (!spage->page)
2604                         goto leave_nomem;
2605                 len -= l;
2606                 logical += l;
2607                 physical += l;
2608         }
2609
2610         WARN_ON(sblock->page_count == 0);
2611         for (index = 0; index < sblock->page_count; index++) {
2612                 struct scrub_page *spage = sblock->pagev[index];
2613                 int ret;
2614
2615                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2616                 if (ret) {
2617                         scrub_block_put(sblock);
2618                         return ret;
2619                 }
2620         }
2621
2622         /* last one frees, either here or in bio completion for last page */
2623         scrub_block_put(sblock);
2624         return 0;
2625 }
2626
2627 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2628                                    u64 logical, u64 len,
2629                                    u64 physical, struct btrfs_device *dev,
2630                                    u64 flags, u64 gen, int mirror_num)
2631 {
2632         struct scrub_ctx *sctx = sparity->sctx;
2633         int ret;
2634         u8 csum[BTRFS_CSUM_SIZE];
2635         u32 blocksize;
2636
2637         if (dev->missing) {
2638                 scrub_parity_mark_sectors_error(sparity, logical, len);
2639                 return 0;
2640         }
2641
2642         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2643                 blocksize = sctx->sectorsize;
2644         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2645                 blocksize = sctx->nodesize;
2646         } else {
2647                 blocksize = sctx->sectorsize;
2648                 WARN_ON(1);
2649         }
2650
2651         while (len) {
2652                 u64 l = min_t(u64, len, blocksize);
2653                 int have_csum = 0;
2654
2655                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2656                         /* push csums to sbio */
2657                         have_csum = scrub_find_csum(sctx, logical, csum);
2658                         if (have_csum == 0)
2659                                 goto skip;
2660                 }
2661                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2662                                              flags, gen, mirror_num,
2663                                              have_csum ? csum : NULL);
2664                 if (ret)
2665                         return ret;
2666 skip:
2667                 len -= l;
2668                 logical += l;
2669                 physical += l;
2670         }
2671         return 0;
2672 }
2673
2674 /*
2675  * Given a physical address, this will calculate it's
2676  * logical offset. if this is a parity stripe, it will return
2677  * the most left data stripe's logical offset.
2678  *
2679  * return 0 if it is a data stripe, 1 means parity stripe.
2680  */
2681 static int get_raid56_logic_offset(u64 physical, int num,
2682                                    struct map_lookup *map, u64 *offset,
2683                                    u64 *stripe_start)
2684 {
2685         int i;
2686         int j = 0;
2687         u64 stripe_nr;
2688         u64 last_offset;
2689         u32 stripe_index;
2690         u32 rot;
2691
2692         last_offset = (physical - map->stripes[num].physical) *
2693                       nr_data_stripes(map);
2694         if (stripe_start)
2695                 *stripe_start = last_offset;
2696
2697         *offset = last_offset;
2698         for (i = 0; i < nr_data_stripes(map); i++) {
2699                 *offset = last_offset + i * map->stripe_len;
2700
2701                 stripe_nr = div_u64(*offset, map->stripe_len);
2702                 stripe_nr = div_u64(stripe_nr, nr_data_stripes(map));
2703
2704                 /* Work out the disk rotation on this stripe-set */
2705                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2706                 /* calculate which stripe this data locates */
2707                 rot += i;
2708                 stripe_index = rot % map->num_stripes;
2709                 if (stripe_index == num)
2710                         return 0;
2711                 if (stripe_index < num)
2712                         j++;
2713         }
2714         *offset = last_offset + j * map->stripe_len;
2715         return 1;
2716 }
2717
2718 static void scrub_free_parity(struct scrub_parity *sparity)
2719 {
2720         struct scrub_ctx *sctx = sparity->sctx;
2721         struct scrub_page *curr, *next;
2722         int nbits;
2723
2724         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2725         if (nbits) {
2726                 spin_lock(&sctx->stat_lock);
2727                 sctx->stat.read_errors += nbits;
2728                 sctx->stat.uncorrectable_errors += nbits;
2729                 spin_unlock(&sctx->stat_lock);
2730         }
2731
2732         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2733                 list_del_init(&curr->list);
2734                 scrub_page_put(curr);
2735         }
2736
2737         kfree(sparity);
2738 }
2739
2740 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2741 {
2742         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2743                                                     work);
2744         struct scrub_ctx *sctx = sparity->sctx;
2745
2746         scrub_free_parity(sparity);
2747         scrub_pending_bio_dec(sctx);
2748 }
2749
2750 static void scrub_parity_bio_endio(struct bio *bio)
2751 {
2752         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
2753
2754         if (bio->bi_error)
2755                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2756                           sparity->nsectors);
2757
2758         bio_put(bio);
2759
2760         btrfs_init_work(&sparity->work, btrfs_scrubparity_helper,
2761                         scrub_parity_bio_endio_worker, NULL, NULL);
2762         btrfs_queue_work(sparity->sctx->dev_root->fs_info->scrub_parity_workers,
2763                          &sparity->work);
2764 }
2765
2766 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
2767 {
2768         struct scrub_ctx *sctx = sparity->sctx;
2769         struct bio *bio;
2770         struct btrfs_raid_bio *rbio;
2771         struct scrub_page *spage;
2772         struct btrfs_bio *bbio = NULL;
2773         u64 length;
2774         int ret;
2775
2776         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
2777                            sparity->nsectors))
2778                 goto out;
2779
2780         length = sparity->logic_end - sparity->logic_start;
2781         ret = btrfs_map_sblock(sctx->dev_root->fs_info, WRITE,
2782                                sparity->logic_start,
2783                                &length, &bbio, 0, 1);
2784         if (ret || !bbio || !bbio->raid_map)
2785                 goto bbio_out;
2786
2787         bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
2788         if (!bio)
2789                 goto bbio_out;
2790
2791         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
2792         bio->bi_private = sparity;
2793         bio->bi_end_io = scrub_parity_bio_endio;
2794
2795         rbio = raid56_parity_alloc_scrub_rbio(sctx->dev_root, bio, bbio,
2796                                               length, sparity->scrub_dev,
2797                                               sparity->dbitmap,
2798                                               sparity->nsectors);
2799         if (!rbio)
2800                 goto rbio_out;
2801
2802         list_for_each_entry(spage, &sparity->spages, list)
2803                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2804
2805         scrub_pending_bio_inc(sctx);
2806         raid56_parity_submit_scrub_rbio(rbio);
2807         return;
2808
2809 rbio_out:
2810         bio_put(bio);
2811 bbio_out:
2812         btrfs_put_bbio(bbio);
2813         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2814                   sparity->nsectors);
2815         spin_lock(&sctx->stat_lock);
2816         sctx->stat.malloc_errors++;
2817         spin_unlock(&sctx->stat_lock);
2818 out:
2819         scrub_free_parity(sparity);
2820 }
2821
2822 static inline int scrub_calc_parity_bitmap_len(int nsectors)
2823 {
2824         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
2825 }
2826
2827 static void scrub_parity_get(struct scrub_parity *sparity)
2828 {
2829         atomic_inc(&sparity->refs);
2830 }
2831
2832 static void scrub_parity_put(struct scrub_parity *sparity)
2833 {
2834         if (!atomic_dec_and_test(&sparity->refs))
2835                 return;
2836
2837         scrub_parity_check_and_repair(sparity);
2838 }
2839
2840 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
2841                                                   struct map_lookup *map,
2842                                                   struct btrfs_device *sdev,
2843                                                   struct btrfs_path *path,
2844                                                   u64 logic_start,
2845                                                   u64 logic_end)
2846 {
2847         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
2848         struct btrfs_root *root = fs_info->extent_root;
2849         struct btrfs_root *csum_root = fs_info->csum_root;
2850         struct btrfs_extent_item *extent;
2851         struct btrfs_bio *bbio = NULL;
2852         u64 flags;
2853         int ret;
2854         int slot;
2855         struct extent_buffer *l;
2856         struct btrfs_key key;
2857         u64 generation;
2858         u64 extent_logical;
2859         u64 extent_physical;
2860         u64 extent_len;
2861         u64 mapped_length;
2862         struct btrfs_device *extent_dev;
2863         struct scrub_parity *sparity;
2864         int nsectors;
2865         int bitmap_len;
2866         int extent_mirror_num;
2867         int stop_loop = 0;
2868
2869         nsectors = div_u64(map->stripe_len, root->sectorsize);
2870         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
2871         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
2872                           GFP_NOFS);
2873         if (!sparity) {
2874                 spin_lock(&sctx->stat_lock);
2875                 sctx->stat.malloc_errors++;
2876                 spin_unlock(&sctx->stat_lock);
2877                 return -ENOMEM;
2878         }
2879
2880         sparity->stripe_len = map->stripe_len;
2881         sparity->nsectors = nsectors;
2882         sparity->sctx = sctx;
2883         sparity->scrub_dev = sdev;
2884         sparity->logic_start = logic_start;
2885         sparity->logic_end = logic_end;
2886         atomic_set(&sparity->refs, 1);
2887         INIT_LIST_HEAD(&sparity->spages);
2888         sparity->dbitmap = sparity->bitmap;
2889         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
2890
2891         ret = 0;
2892         while (logic_start < logic_end) {
2893                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2894                         key.type = BTRFS_METADATA_ITEM_KEY;
2895                 else
2896                         key.type = BTRFS_EXTENT_ITEM_KEY;
2897                 key.objectid = logic_start;
2898                 key.offset = (u64)-1;
2899
2900                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2901                 if (ret < 0)
2902                         goto out;
2903
2904                 if (ret > 0) {
2905                         ret = btrfs_previous_extent_item(root, path, 0);
2906                         if (ret < 0)
2907                                 goto out;
2908                         if (ret > 0) {
2909                                 btrfs_release_path(path);
2910                                 ret = btrfs_search_slot(NULL, root, &key,
2911                                                         path, 0, 0);
2912                                 if (ret < 0)
2913                                         goto out;
2914                         }
2915                 }
2916
2917                 stop_loop = 0;
2918                 while (1) {
2919                         u64 bytes;
2920
2921                         l = path->nodes[0];
2922                         slot = path->slots[0];
2923                         if (slot >= btrfs_header_nritems(l)) {
2924                                 ret = btrfs_next_leaf(root, path);
2925                                 if (ret == 0)
2926                                         continue;
2927                                 if (ret < 0)
2928                                         goto out;
2929
2930                                 stop_loop = 1;
2931                                 break;
2932                         }
2933                         btrfs_item_key_to_cpu(l, &key, slot);
2934
2935                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2936                             key.type != BTRFS_METADATA_ITEM_KEY)
2937                                 goto next;
2938
2939                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2940                                 bytes = root->nodesize;
2941                         else
2942                                 bytes = key.offset;
2943
2944                         if (key.objectid + bytes <= logic_start)
2945                                 goto next;
2946
2947                         if (key.objectid >= logic_end) {
2948                                 stop_loop = 1;
2949                                 break;
2950                         }
2951
2952                         while (key.objectid >= logic_start + map->stripe_len)
2953                                 logic_start += map->stripe_len;
2954
2955                         extent = btrfs_item_ptr(l, slot,
2956                                                 struct btrfs_extent_item);
2957                         flags = btrfs_extent_flags(l, extent);
2958                         generation = btrfs_extent_generation(l, extent);
2959
2960                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
2961                             (key.objectid < logic_start ||
2962                              key.objectid + bytes >
2963                              logic_start + map->stripe_len)) {
2964                                 btrfs_err(fs_info, "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
2965                                           key.objectid, logic_start);
2966                                 spin_lock(&sctx->stat_lock);
2967                                 sctx->stat.uncorrectable_errors++;
2968                                 spin_unlock(&sctx->stat_lock);
2969                                 goto next;
2970                         }
2971 again:
2972                         extent_logical = key.objectid;
2973                         extent_len = bytes;
2974
2975                         if (extent_logical < logic_start) {
2976                                 extent_len -= logic_start - extent_logical;
2977                                 extent_logical = logic_start;
2978                         }
2979
2980                         if (extent_logical + extent_len >
2981                             logic_start + map->stripe_len)
2982                                 extent_len = logic_start + map->stripe_len -
2983                                              extent_logical;
2984
2985                         scrub_parity_mark_sectors_data(sparity, extent_logical,
2986                                                        extent_len);
2987
2988                         mapped_length = extent_len;
2989                         bbio = NULL;
2990                         ret = btrfs_map_block(fs_info, READ, extent_logical,
2991                                               &mapped_length, &bbio, 0);
2992                         if (!ret) {
2993                                 if (!bbio || mapped_length < extent_len)
2994                                         ret = -EIO;
2995                         }
2996                         if (ret) {
2997                                 btrfs_put_bbio(bbio);
2998                                 goto out;
2999                         }
3000                         extent_physical = bbio->stripes[0].physical;
3001                         extent_mirror_num = bbio->mirror_num;
3002                         extent_dev = bbio->stripes[0].dev;
3003                         btrfs_put_bbio(bbio);
3004
3005                         ret = btrfs_lookup_csums_range(csum_root,
3006                                                 extent_logical,
3007                                                 extent_logical + extent_len - 1,
3008                                                 &sctx->csum_list, 1);
3009                         if (ret)
3010                                 goto out;
3011
3012                         ret = scrub_extent_for_parity(sparity, extent_logical,
3013                                                       extent_len,
3014                                                       extent_physical,
3015                                                       extent_dev, flags,
3016                                                       generation,
3017                                                       extent_mirror_num);
3018
3019                         scrub_free_csums(sctx);
3020
3021                         if (ret)
3022                                 goto out;
3023
3024                         if (extent_logical + extent_len <
3025                             key.objectid + bytes) {
3026                                 logic_start += map->stripe_len;
3027
3028                                 if (logic_start >= logic_end) {
3029                                         stop_loop = 1;
3030                                         break;
3031                                 }
3032
3033                                 if (logic_start < key.objectid + bytes) {
3034                                         cond_resched();
3035                                         goto again;
3036                                 }
3037                         }
3038 next:
3039                         path->slots[0]++;
3040                 }
3041
3042                 btrfs_release_path(path);
3043
3044                 if (stop_loop)
3045                         break;
3046
3047                 logic_start += map->stripe_len;
3048         }
3049 out:
3050         if (ret < 0)
3051                 scrub_parity_mark_sectors_error(sparity, logic_start,
3052                                                 logic_end - logic_start);
3053         scrub_parity_put(sparity);
3054         scrub_submit(sctx);
3055         mutex_lock(&sctx->wr_ctx.wr_lock);
3056         scrub_wr_submit(sctx);
3057         mutex_unlock(&sctx->wr_ctx.wr_lock);
3058
3059         btrfs_release_path(path);
3060         return ret < 0 ? ret : 0;
3061 }
3062
3063 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3064                                            struct map_lookup *map,
3065                                            struct btrfs_device *scrub_dev,
3066                                            int num, u64 base, u64 length,
3067                                            int is_dev_replace)
3068 {
3069         struct btrfs_path *path, *ppath;
3070         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
3071         struct btrfs_root *root = fs_info->extent_root;
3072         struct btrfs_root *csum_root = fs_info->csum_root;
3073         struct btrfs_extent_item *extent;
3074         struct blk_plug plug;
3075         u64 flags;
3076         int ret;
3077         int slot;
3078         u64 nstripes;
3079         struct extent_buffer *l;
3080         u64 physical;
3081         u64 logical;
3082         u64 logic_end;
3083         u64 physical_end;
3084         u64 generation;
3085         int mirror_num;
3086         struct reada_control *reada1;
3087         struct reada_control *reada2;
3088         struct btrfs_key key;
3089         struct btrfs_key key_end;
3090         u64 increment = map->stripe_len;
3091         u64 offset;
3092         u64 extent_logical;
3093         u64 extent_physical;
3094         u64 extent_len;
3095         u64 stripe_logical;
3096         u64 stripe_end;
3097         struct btrfs_device *extent_dev;
3098         int extent_mirror_num;
3099         int stop_loop = 0;
3100
3101         physical = map->stripes[num].physical;
3102         offset = 0;
3103         nstripes = div_u64(length, map->stripe_len);
3104         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3105                 offset = map->stripe_len * num;
3106                 increment = map->stripe_len * map->num_stripes;
3107                 mirror_num = 1;
3108         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3109                 int factor = map->num_stripes / map->sub_stripes;
3110                 offset = map->stripe_len * (num / map->sub_stripes);
3111                 increment = map->stripe_len * factor;
3112                 mirror_num = num % map->sub_stripes + 1;
3113         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
3114                 increment = map->stripe_len;
3115                 mirror_num = num % map->num_stripes + 1;
3116         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3117                 increment = map->stripe_len;
3118                 mirror_num = num % map->num_stripes + 1;
3119         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3120                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3121                 increment = map->stripe_len * nr_data_stripes(map);
3122                 mirror_num = 1;
3123         } else {
3124                 increment = map->stripe_len;
3125                 mirror_num = 1;
3126         }
3127
3128         path = btrfs_alloc_path();
3129         if (!path)
3130                 return -ENOMEM;
3131
3132         ppath = btrfs_alloc_path();
3133         if (!ppath) {
3134                 btrfs_free_path(path);
3135                 return -ENOMEM;
3136         }
3137
3138         /*
3139          * work on commit root. The related disk blocks are static as
3140          * long as COW is applied. This means, it is save to rewrite
3141          * them to repair disk errors without any race conditions
3142          */
3143         path->search_commit_root = 1;
3144         path->skip_locking = 1;
3145
3146         ppath->search_commit_root = 1;
3147         ppath->skip_locking = 1;
3148         /*
3149          * trigger the readahead for extent tree csum tree and wait for
3150          * completion. During readahead, the scrub is officially paused
3151          * to not hold off transaction commits
3152          */
3153         logical = base + offset;
3154         physical_end = physical + nstripes * map->stripe_len;
3155         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3156                 get_raid56_logic_offset(physical_end, num,
3157                                         map, &logic_end, NULL);
3158                 logic_end += base;
3159         } else {
3160                 logic_end = logical + increment * nstripes;
3161         }
3162         wait_event(sctx->list_wait,
3163                    atomic_read(&sctx->bios_in_flight) == 0);
3164         scrub_blocked_if_needed(fs_info);
3165
3166         /* FIXME it might be better to start readahead at commit root */
3167         key.objectid = logical;
3168         key.type = BTRFS_EXTENT_ITEM_KEY;
3169         key.offset = (u64)0;
3170         key_end.objectid = logic_end;
3171         key_end.type = BTRFS_METADATA_ITEM_KEY;
3172         key_end.offset = (u64)-1;
3173         reada1 = btrfs_reada_add(root, &key, &key_end);
3174
3175         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3176         key.type = BTRFS_EXTENT_CSUM_KEY;
3177         key.offset = logical;
3178         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3179         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3180         key_end.offset = logic_end;
3181         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3182
3183         if (!IS_ERR(reada1))
3184                 btrfs_reada_wait(reada1);
3185         if (!IS_ERR(reada2))
3186                 btrfs_reada_wait(reada2);
3187
3188
3189         /*
3190          * collect all data csums for the stripe to avoid seeking during
3191          * the scrub. This might currently (crc32) end up to be about 1MB
3192          */
3193         blk_start_plug(&plug);
3194
3195         /*
3196          * now find all extents for each stripe and scrub them
3197          */
3198         ret = 0;
3199         while (physical < physical_end) {
3200                 /*
3201                  * canceled?
3202                  */
3203                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3204                     atomic_read(&sctx->cancel_req)) {
3205                         ret = -ECANCELED;
3206                         goto out;
3207                 }
3208                 /*
3209                  * check to see if we have to pause
3210                  */
3211                 if (atomic_read(&fs_info->scrub_pause_req)) {
3212                         /* push queued extents */
3213                         atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
3214                         scrub_submit(sctx);
3215                         mutex_lock(&sctx->wr_ctx.wr_lock);
3216                         scrub_wr_submit(sctx);
3217                         mutex_unlock(&sctx->wr_ctx.wr_lock);
3218                         wait_event(sctx->list_wait,
3219                                    atomic_read(&sctx->bios_in_flight) == 0);
3220                         atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
3221                         scrub_blocked_if_needed(fs_info);
3222                 }
3223
3224                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3225                         ret = get_raid56_logic_offset(physical, num, map,
3226                                                       &logical,
3227                                                       &stripe_logical);
3228                         logical += base;
3229                         if (ret) {
3230                                 /* it is parity strip */
3231                                 stripe_logical += base;
3232                                 stripe_end = stripe_logical + increment;
3233                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3234                                                           ppath, stripe_logical,
3235                                                           stripe_end);
3236                                 if (ret)
3237                                         goto out;
3238                                 goto skip;
3239                         }
3240                 }
3241
3242                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3243                         key.type = BTRFS_METADATA_ITEM_KEY;
3244                 else
3245                         key.type = BTRFS_EXTENT_ITEM_KEY;
3246                 key.objectid = logical;
3247                 key.offset = (u64)-1;
3248
3249                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3250                 if (ret < 0)
3251                         goto out;
3252
3253                 if (ret > 0) {
3254                         ret = btrfs_previous_extent_item(root, path, 0);
3255                         if (ret < 0)
3256                                 goto out;
3257                         if (ret > 0) {
3258                                 /* there's no smaller item, so stick with the
3259                                  * larger one */
3260                                 btrfs_release_path(path);
3261                                 ret = btrfs_search_slot(NULL, root, &key,
3262                                                         path, 0, 0);
3263                                 if (ret < 0)
3264                                         goto out;
3265                         }
3266                 }
3267
3268                 stop_loop = 0;
3269                 while (1) {
3270                         u64 bytes;
3271
3272                         l = path->nodes[0];
3273                         slot = path->slots[0];
3274                         if (slot >= btrfs_header_nritems(l)) {
3275                                 ret = btrfs_next_leaf(root, path);
3276                                 if (ret == 0)
3277                                         continue;
3278                                 if (ret < 0)
3279                                         goto out;
3280
3281                                 stop_loop = 1;
3282                                 break;
3283                         }
3284                         btrfs_item_key_to_cpu(l, &key, slot);
3285
3286                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3287                             key.type != BTRFS_METADATA_ITEM_KEY)
3288                                 goto next;
3289
3290                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3291                                 bytes = root->nodesize;
3292                         else
3293                                 bytes = key.offset;
3294
3295                         if (key.objectid + bytes <= logical)
3296                                 goto next;
3297
3298                         if (key.objectid >= logical + map->stripe_len) {
3299                                 /* out of this device extent */
3300                                 if (key.objectid >= logic_end)
3301                                         stop_loop = 1;
3302                                 break;
3303                         }
3304
3305                         extent = btrfs_item_ptr(l, slot,
3306                                                 struct btrfs_extent_item);
3307                         flags = btrfs_extent_flags(l, extent);
3308                         generation = btrfs_extent_generation(l, extent);
3309
3310                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3311                             (key.objectid < logical ||
3312                              key.objectid + bytes >
3313                              logical + map->stripe_len)) {
3314                                 btrfs_err(fs_info,
3315                                            "scrub: tree block %llu spanning "
3316                                            "stripes, ignored. logical=%llu",
3317                                        key.objectid, logical);
3318                                 spin_lock(&sctx->stat_lock);
3319                                 sctx->stat.uncorrectable_errors++;
3320                                 spin_unlock(&sctx->stat_lock);
3321                                 goto next;
3322                         }
3323
3324 again:
3325                         extent_logical = key.objectid;
3326                         extent_len = bytes;
3327
3328                         /*
3329                          * trim extent to this stripe
3330                          */
3331                         if (extent_logical < logical) {
3332                                 extent_len -= logical - extent_logical;
3333                                 extent_logical = logical;
3334                         }
3335                         if (extent_logical + extent_len >
3336                             logical + map->stripe_len) {
3337                                 extent_len = logical + map->stripe_len -
3338                                              extent_logical;
3339                         }
3340
3341                         extent_physical = extent_logical - logical + physical;
3342                         extent_dev = scrub_dev;
3343                         extent_mirror_num = mirror_num;
3344                         if (is_dev_replace)
3345                                 scrub_remap_extent(fs_info, extent_logical,
3346                                                    extent_len, &extent_physical,
3347                                                    &extent_dev,
3348                                                    &extent_mirror_num);
3349
3350                         ret = btrfs_lookup_csums_range(csum_root,
3351                                                        extent_logical,
3352                                                        extent_logical +
3353                                                        extent_len - 1,
3354                                                        &sctx->csum_list, 1);
3355                         if (ret)
3356                                 goto out;
3357
3358                         ret = scrub_extent(sctx, extent_logical, extent_len,
3359                                            extent_physical, extent_dev, flags,
3360                                            generation, extent_mirror_num,
3361                                            extent_logical - logical + physical);
3362
3363                         scrub_free_csums(sctx);
3364
3365                         if (ret)
3366                                 goto out;
3367
3368                         if (extent_logical + extent_len <
3369                             key.objectid + bytes) {
3370                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3371                                         /*
3372                                          * loop until we find next data stripe
3373                                          * or we have finished all stripes.
3374                                          */
3375 loop:
3376                                         physical += map->stripe_len;
3377                                         ret = get_raid56_logic_offset(physical,
3378                                                         num, map, &logical,
3379                                                         &stripe_logical);
3380                                         logical += base;
3381
3382                                         if (ret && physical < physical_end) {
3383                                                 stripe_logical += base;
3384                                                 stripe_end = stripe_logical +
3385                                                                 increment;
3386                                                 ret = scrub_raid56_parity(sctx,
3387                                                         map, scrub_dev, ppath,
3388                                                         stripe_logical,
3389                                                         stripe_end);
3390                                                 if (ret)
3391                                                         goto out;
3392                                                 goto loop;
3393                                         }
3394                                 } else {
3395                                         physical += map->stripe_len;
3396                                         logical += increment;
3397                                 }
3398                                 if (logical < key.objectid + bytes) {
3399                                         cond_resched();
3400                                         goto again;
3401                                 }
3402
3403                                 if (physical >= physical_end) {
3404                                         stop_loop = 1;
3405                                         break;
3406                                 }
3407                         }
3408 next:
3409                         path->slots[0]++;
3410                 }
3411                 btrfs_release_path(path);
3412 skip:
3413                 logical += increment;
3414                 physical += map->stripe_len;
3415                 spin_lock(&sctx->stat_lock);
3416                 if (stop_loop)
3417                         sctx->stat.last_physical = map->stripes[num].physical +
3418                                                    length;
3419                 else
3420                         sctx->stat.last_physical = physical;
3421                 spin_unlock(&sctx->stat_lock);
3422                 if (stop_loop)
3423                         break;
3424         }
3425 out:
3426         /* push queued extents */
3427         scrub_submit(sctx);
3428         mutex_lock(&sctx->wr_ctx.wr_lock);
3429         scrub_wr_submit(sctx);
3430         mutex_unlock(&sctx->wr_ctx.wr_lock);
3431
3432         blk_finish_plug(&plug);
3433         btrfs_free_path(path);
3434         btrfs_free_path(ppath);
3435         return ret < 0 ? ret : 0;
3436 }
3437
3438 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3439                                           struct btrfs_device *scrub_dev,
3440                                           u64 chunk_offset, u64 length,
3441                                           u64 dev_offset,
3442                                           struct btrfs_block_group_cache *cache,
3443                                           int is_dev_replace)
3444 {
3445         struct btrfs_mapping_tree *map_tree =
3446                 &sctx->dev_root->fs_info->mapping_tree;
3447         struct map_lookup *map;
3448         struct extent_map *em;
3449         int i;
3450         int ret = 0;
3451
3452         read_lock(&map_tree->map_tree.lock);
3453         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
3454         read_unlock(&map_tree->map_tree.lock);
3455
3456         if (!em) {
3457                 /*
3458                  * Might have been an unused block group deleted by the cleaner
3459                  * kthread or relocation.
3460                  */
3461                 spin_lock(&cache->lock);
3462                 if (!cache->removed)
3463                         ret = -EINVAL;
3464                 spin_unlock(&cache->lock);
3465
3466                 return ret;
3467         }
3468
3469         map = em->map_lookup;
3470         if (em->start != chunk_offset)
3471                 goto out;
3472
3473         if (em->len < length)
3474                 goto out;
3475
3476         for (i = 0; i < map->num_stripes; ++i) {
3477                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3478                     map->stripes[i].physical == dev_offset) {
3479                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3480                                            chunk_offset, length,
3481                                            is_dev_replace);
3482                         if (ret)
3483                                 goto out;
3484                 }
3485         }
3486 out:
3487         free_extent_map(em);
3488
3489         return ret;
3490 }
3491
3492 static noinline_for_stack
3493 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3494                            struct btrfs_device *scrub_dev, u64 start, u64 end,
3495                            int is_dev_replace)
3496 {
3497         struct btrfs_dev_extent *dev_extent = NULL;
3498         struct btrfs_path *path;
3499         struct btrfs_root *root = sctx->dev_root;
3500         struct btrfs_fs_info *fs_info = root->fs_info;
3501         u64 length;
3502         u64 chunk_offset;
3503         int ret = 0;
3504         int ro_set;
3505         int slot;
3506         struct extent_buffer *l;
3507         struct btrfs_key key;
3508         struct btrfs_key found_key;
3509         struct btrfs_block_group_cache *cache;
3510         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3511
3512         path = btrfs_alloc_path();
3513         if (!path)
3514                 return -ENOMEM;
3515
3516         path->reada = READA_FORWARD;
3517         path->search_commit_root = 1;
3518         path->skip_locking = 1;
3519
3520         key.objectid = scrub_dev->devid;
3521         key.offset = 0ull;
3522         key.type = BTRFS_DEV_EXTENT_KEY;
3523
3524         while (1) {
3525                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3526                 if (ret < 0)
3527                         break;
3528                 if (ret > 0) {
3529                         if (path->slots[0] >=
3530                             btrfs_header_nritems(path->nodes[0])) {
3531                                 ret = btrfs_next_leaf(root, path);
3532                                 if (ret < 0)
3533                                         break;
3534                                 if (ret > 0) {
3535                                         ret = 0;
3536                                         break;
3537                                 }
3538                         } else {
3539                                 ret = 0;
3540                         }
3541                 }
3542
3543                 l = path->nodes[0];
3544                 slot = path->slots[0];
3545
3546                 btrfs_item_key_to_cpu(l, &found_key, slot);
3547
3548                 if (found_key.objectid != scrub_dev->devid)
3549                         break;
3550
3551                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3552                         break;
3553
3554                 if (found_key.offset >= end)
3555                         break;
3556
3557                 if (found_key.offset < key.offset)
3558                         break;
3559
3560                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3561                 length = btrfs_dev_extent_length(l, dev_extent);
3562
3563                 if (found_key.offset + length <= start)
3564                         goto skip;
3565
3566                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3567
3568                 /*
3569                  * get a reference on the corresponding block group to prevent
3570                  * the chunk from going away while we scrub it
3571                  */
3572                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3573
3574                 /* some chunks are removed but not committed to disk yet,
3575                  * continue scrubbing */
3576                 if (!cache)
3577                         goto skip;
3578
3579                 /*
3580                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3581                  * to avoid deadlock caused by:
3582                  * btrfs_inc_block_group_ro()
3583                  * -> btrfs_wait_for_commit()
3584                  * -> btrfs_commit_transaction()
3585                  * -> btrfs_scrub_pause()
3586                  */
3587                 scrub_pause_on(fs_info);
3588                 ret = btrfs_inc_block_group_ro(root, cache);
3589                 if (!ret && is_dev_replace) {
3590                         /*
3591                          * If we are doing a device replace wait for any tasks
3592                          * that started dellaloc right before we set the block
3593                          * group to RO mode, as they might have just allocated
3594                          * an extent from it or decided they could do a nocow
3595                          * write. And if any such tasks did that, wait for their
3596                          * ordered extents to complete and then commit the
3597                          * current transaction, so that we can later see the new
3598                          * extent items in the extent tree - the ordered extents
3599                          * create delayed data references (for cow writes) when
3600                          * they complete, which will be run and insert the
3601                          * corresponding extent items into the extent tree when
3602                          * we commit the transaction they used when running
3603                          * inode.c:btrfs_finish_ordered_io(). We later use
3604                          * the commit root of the extent tree to find extents
3605                          * to copy from the srcdev into the tgtdev, and we don't
3606                          * want to miss any new extents.
3607                          */
3608                         btrfs_wait_block_group_reservations(cache);
3609                         btrfs_wait_nocow_writers(cache);
3610                         ret = btrfs_wait_ordered_roots(fs_info, -1,
3611                                                        cache->key.objectid,
3612                                                        cache->key.offset);
3613                         if (ret > 0) {
3614                                 struct btrfs_trans_handle *trans;
3615
3616                                 trans = btrfs_join_transaction(root);
3617                                 if (IS_ERR(trans))
3618                                         ret = PTR_ERR(trans);
3619                                 else
3620                                         ret = btrfs_commit_transaction(trans,
3621                                                                        root);
3622                                 if (ret) {
3623                                         scrub_pause_off(fs_info);
3624                                         btrfs_put_block_group(cache);
3625                                         break;
3626                                 }
3627                         }
3628                 }
3629                 scrub_pause_off(fs_info);
3630
3631                 if (ret == 0) {
3632                         ro_set = 1;
3633                 } else if (ret == -ENOSPC) {
3634                         /*
3635                          * btrfs_inc_block_group_ro return -ENOSPC when it
3636                          * failed in creating new chunk for metadata.
3637                          * It is not a problem for scrub/replace, because
3638                          * metadata are always cowed, and our scrub paused
3639                          * commit_transactions.
3640                          */
3641                         ro_set = 0;
3642                 } else {
3643                         btrfs_warn(fs_info, "failed setting block group ro, ret=%d\n",
3644                                    ret);
3645                         btrfs_put_block_group(cache);
3646                         break;
3647                 }
3648
3649                 btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
3650                 dev_replace->cursor_right = found_key.offset + length;
3651                 dev_replace->cursor_left = found_key.offset;
3652                 dev_replace->item_needs_writeback = 1;
3653                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
3654                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3655                                   found_key.offset, cache, is_dev_replace);
3656
3657                 /*
3658                  * flush, submit all pending read and write bios, afterwards
3659                  * wait for them.
3660                  * Note that in the dev replace case, a read request causes
3661                  * write requests that are submitted in the read completion
3662                  * worker. Therefore in the current situation, it is required
3663                  * that all write requests are flushed, so that all read and
3664                  * write requests are really completed when bios_in_flight
3665                  * changes to 0.
3666                  */
3667                 atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
3668                 scrub_submit(sctx);
3669                 mutex_lock(&sctx->wr_ctx.wr_lock);
3670                 scrub_wr_submit(sctx);
3671                 mutex_unlock(&sctx->wr_ctx.wr_lock);
3672
3673                 wait_event(sctx->list_wait,
3674                            atomic_read(&sctx->bios_in_flight) == 0);
3675
3676                 scrub_pause_on(fs_info);
3677
3678                 /*
3679                  * must be called before we decrease @scrub_paused.
3680                  * make sure we don't block transaction commit while
3681                  * we are waiting pending workers finished.
3682                  */
3683                 wait_event(sctx->list_wait,
3684                            atomic_read(&sctx->workers_pending) == 0);
3685                 atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
3686
3687                 scrub_pause_off(fs_info);
3688
3689                 btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
3690                 dev_replace->cursor_left = dev_replace->cursor_right;
3691                 dev_replace->item_needs_writeback = 1;
3692                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
3693
3694                 if (ro_set)
3695                         btrfs_dec_block_group_ro(root, cache);
3696
3697                 /*
3698                  * We might have prevented the cleaner kthread from deleting
3699                  * this block group if it was already unused because we raced
3700                  * and set it to RO mode first. So add it back to the unused
3701                  * list, otherwise it might not ever be deleted unless a manual
3702                  * balance is triggered or it becomes used and unused again.
3703                  */
3704                 spin_lock(&cache->lock);
3705                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3706                     btrfs_block_group_used(&cache->item) == 0) {
3707                         spin_unlock(&cache->lock);
3708                         spin_lock(&fs_info->unused_bgs_lock);
3709                         if (list_empty(&cache->bg_list)) {
3710                                 btrfs_get_block_group(cache);
3711                                 list_add_tail(&cache->bg_list,
3712                                               &fs_info->unused_bgs);
3713                         }
3714                         spin_unlock(&fs_info->unused_bgs_lock);
3715                 } else {
3716                         spin_unlock(&cache->lock);
3717                 }
3718
3719                 btrfs_put_block_group(cache);
3720                 if (ret)
3721                         break;
3722                 if (is_dev_replace &&
3723                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3724                         ret = -EIO;
3725                         break;
3726                 }
3727                 if (sctx->stat.malloc_errors > 0) {
3728                         ret = -ENOMEM;
3729                         break;
3730                 }
3731 skip:
3732                 key.offset = found_key.offset + length;
3733                 btrfs_release_path(path);
3734         }
3735
3736         btrfs_free_path(path);
3737
3738         return ret;
3739 }
3740
3741 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3742                                            struct btrfs_device *scrub_dev)
3743 {
3744         int     i;
3745         u64     bytenr;
3746         u64     gen;
3747         int     ret;
3748         struct btrfs_root *root = sctx->dev_root;
3749
3750         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
3751                 return -EIO;
3752
3753         /* Seed devices of a new filesystem has their own generation. */
3754         if (scrub_dev->fs_devices != root->fs_info->fs_devices)
3755                 gen = scrub_dev->generation;
3756         else
3757                 gen = root->fs_info->last_trans_committed;
3758
3759         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
3760                 bytenr = btrfs_sb_offset(i);
3761                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
3762                     scrub_dev->commit_total_bytes)
3763                         break;
3764
3765                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
3766                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
3767                                   NULL, 1, bytenr);
3768                 if (ret)
3769                         return ret;
3770         }
3771         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3772
3773         return 0;
3774 }
3775
3776 /*
3777  * get a reference count on fs_info->scrub_workers. start worker if necessary
3778  */
3779 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
3780                                                 int is_dev_replace)
3781 {
3782         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
3783         int max_active = fs_info->thread_pool_size;
3784
3785         if (fs_info->scrub_workers_refcnt == 0) {
3786                 if (is_dev_replace)
3787                         fs_info->scrub_workers =
3788                                 btrfs_alloc_workqueue("scrub", flags,
3789                                                       1, 4);
3790                 else
3791                         fs_info->scrub_workers =
3792                                 btrfs_alloc_workqueue("scrub", flags,
3793                                                       max_active, 4);
3794                 if (!fs_info->scrub_workers)
3795                         goto fail_scrub_workers;
3796
3797                 fs_info->scrub_wr_completion_workers =
3798                         btrfs_alloc_workqueue("scrubwrc", flags,
3799                                               max_active, 2);
3800                 if (!fs_info->scrub_wr_completion_workers)
3801                         goto fail_scrub_wr_completion_workers;
3802
3803                 fs_info->scrub_nocow_workers =
3804                         btrfs_alloc_workqueue("scrubnc", flags, 1, 0);
3805                 if (!fs_info->scrub_nocow_workers)
3806                         goto fail_scrub_nocow_workers;
3807                 fs_info->scrub_parity_workers =
3808                         btrfs_alloc_workqueue("scrubparity", flags,
3809                                               max_active, 2);
3810                 if (!fs_info->scrub_parity_workers)
3811                         goto fail_scrub_parity_workers;
3812         }
3813         ++fs_info->scrub_workers_refcnt;
3814         return 0;
3815
3816 fail_scrub_parity_workers:
3817         btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
3818 fail_scrub_nocow_workers:
3819         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3820 fail_scrub_wr_completion_workers:
3821         btrfs_destroy_workqueue(fs_info->scrub_workers);
3822 fail_scrub_workers:
3823         return -ENOMEM;
3824 }
3825
3826 static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
3827 {
3828         if (--fs_info->scrub_workers_refcnt == 0) {
3829                 btrfs_destroy_workqueue(fs_info->scrub_workers);
3830                 btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3831                 btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
3832                 btrfs_destroy_workqueue(fs_info->scrub_parity_workers);
3833         }
3834         WARN_ON(fs_info->scrub_workers_refcnt < 0);
3835 }
3836
3837 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
3838                     u64 end, struct btrfs_scrub_progress *progress,
3839                     int readonly, int is_dev_replace)
3840 {
3841         struct scrub_ctx *sctx;
3842         int ret;
3843         struct btrfs_device *dev;
3844         struct rcu_string *name;
3845
3846         if (btrfs_fs_closing(fs_info))
3847                 return -EINVAL;
3848
3849         if (fs_info->chunk_root->nodesize > BTRFS_STRIPE_LEN) {
3850                 /*
3851                  * in this case scrub is unable to calculate the checksum
3852                  * the way scrub is implemented. Do not handle this
3853                  * situation at all because it won't ever happen.
3854                  */
3855                 btrfs_err(fs_info,
3856                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
3857                        fs_info->chunk_root->nodesize, BTRFS_STRIPE_LEN);
3858                 return -EINVAL;
3859         }
3860
3861         if (fs_info->chunk_root->sectorsize != PAGE_SIZE) {
3862                 /* not supported for data w/o checksums */
3863                 btrfs_err(fs_info,
3864                            "scrub: size assumption sectorsize != PAGE_SIZE "
3865                            "(%d != %lu) fails",
3866                        fs_info->chunk_root->sectorsize, PAGE_SIZE);
3867                 return -EINVAL;
3868         }
3869
3870         if (fs_info->chunk_root->nodesize >
3871             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
3872             fs_info->chunk_root->sectorsize >
3873             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
3874                 /*
3875                  * would exhaust the array bounds of pagev member in
3876                  * struct scrub_block
3877                  */
3878                 btrfs_err(fs_info, "scrub: size assumption nodesize and sectorsize "
3879                            "<= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
3880                        fs_info->chunk_root->nodesize,
3881                        SCRUB_MAX_PAGES_PER_BLOCK,
3882                        fs_info->chunk_root->sectorsize,
3883                        SCRUB_MAX_PAGES_PER_BLOCK);
3884                 return -EINVAL;
3885         }
3886
3887
3888         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3889         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
3890         if (!dev || (dev->missing && !is_dev_replace)) {
3891                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3892                 return -ENODEV;
3893         }
3894
3895         if (!is_dev_replace && !readonly && !dev->writeable) {
3896                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3897                 rcu_read_lock();
3898                 name = rcu_dereference(dev->name);
3899                 btrfs_err(fs_info, "scrub: device %s is not writable",
3900                           name->str);
3901                 rcu_read_unlock();
3902                 return -EROFS;
3903         }
3904
3905         mutex_lock(&fs_info->scrub_lock);
3906         if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
3907                 mutex_unlock(&fs_info->scrub_lock);
3908                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3909                 return -EIO;
3910         }
3911
3912         btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
3913         if (dev->scrub_device ||
3914             (!is_dev_replace &&
3915              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
3916                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
3917                 mutex_unlock(&fs_info->scrub_lock);
3918                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3919                 return -EINPROGRESS;
3920         }
3921         btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
3922
3923         ret = scrub_workers_get(fs_info, is_dev_replace);
3924         if (ret) {
3925                 mutex_unlock(&fs_info->scrub_lock);
3926                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3927                 return ret;
3928         }
3929
3930         sctx = scrub_setup_ctx(dev, is_dev_replace);
3931         if (IS_ERR(sctx)) {
3932                 mutex_unlock(&fs_info->scrub_lock);
3933                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3934                 scrub_workers_put(fs_info);
3935                 return PTR_ERR(sctx);
3936         }
3937         sctx->readonly = readonly;
3938         dev->scrub_device = sctx;
3939         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3940
3941         /*
3942          * checking @scrub_pause_req here, we can avoid
3943          * race between committing transaction and scrubbing.
3944          */
3945         __scrub_blocked_if_needed(fs_info);
3946         atomic_inc(&fs_info->scrubs_running);
3947         mutex_unlock(&fs_info->scrub_lock);
3948
3949         if (!is_dev_replace) {
3950                 /*
3951                  * by holding device list mutex, we can
3952                  * kick off writing super in log tree sync.
3953                  */
3954                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
3955                 ret = scrub_supers(sctx, dev);
3956                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3957         }
3958
3959         if (!ret)
3960                 ret = scrub_enumerate_chunks(sctx, dev, start, end,
3961                                              is_dev_replace);
3962
3963         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3964         atomic_dec(&fs_info->scrubs_running);
3965         wake_up(&fs_info->scrub_pause_wait);
3966
3967         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3968
3969         if (progress)
3970                 memcpy(progress, &sctx->stat, sizeof(*progress));
3971
3972         mutex_lock(&fs_info->scrub_lock);
3973         dev->scrub_device = NULL;
3974         scrub_workers_put(fs_info);
3975         mutex_unlock(&fs_info->scrub_lock);
3976
3977         scrub_put_ctx(sctx);
3978
3979         return ret;
3980 }
3981
3982 void btrfs_scrub_pause(struct btrfs_root *root)
3983 {
3984         struct btrfs_fs_info *fs_info = root->fs_info;
3985
3986         mutex_lock(&fs_info->scrub_lock);
3987         atomic_inc(&fs_info->scrub_pause_req);
3988         while (atomic_read(&fs_info->scrubs_paused) !=
3989                atomic_read(&fs_info->scrubs_running)) {
3990                 mutex_unlock(&fs_info->scrub_lock);
3991                 wait_event(fs_info->scrub_pause_wait,
3992                            atomic_read(&fs_info->scrubs_paused) ==
3993                            atomic_read(&fs_info->scrubs_running));
3994                 mutex_lock(&fs_info->scrub_lock);
3995         }
3996         mutex_unlock(&fs_info->scrub_lock);
3997 }
3998
3999 void btrfs_scrub_continue(struct btrfs_root *root)
4000 {
4001         struct btrfs_fs_info *fs_info = root->fs_info;
4002
4003         atomic_dec(&fs_info->scrub_pause_req);
4004         wake_up(&fs_info->scrub_pause_wait);
4005 }
4006
4007 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
4008 {
4009         mutex_lock(&fs_info->scrub_lock);
4010         if (!atomic_read(&fs_info->scrubs_running)) {
4011                 mutex_unlock(&fs_info->scrub_lock);
4012                 return -ENOTCONN;
4013         }
4014
4015         atomic_inc(&fs_info->scrub_cancel_req);
4016         while (atomic_read(&fs_info->scrubs_running)) {
4017                 mutex_unlock(&fs_info->scrub_lock);
4018                 wait_event(fs_info->scrub_pause_wait,
4019                            atomic_read(&fs_info->scrubs_running) == 0);
4020                 mutex_lock(&fs_info->scrub_lock);
4021         }
4022         atomic_dec(&fs_info->scrub_cancel_req);
4023         mutex_unlock(&fs_info->scrub_lock);
4024
4025         return 0;
4026 }
4027
4028 int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
4029                            struct btrfs_device *dev)
4030 {
4031         struct scrub_ctx *sctx;
4032
4033         mutex_lock(&fs_info->scrub_lock);
4034         sctx = dev->scrub_device;
4035         if (!sctx) {
4036                 mutex_unlock(&fs_info->scrub_lock);
4037                 return -ENOTCONN;
4038         }
4039         atomic_inc(&sctx->cancel_req);
4040         while (dev->scrub_device) {
4041                 mutex_unlock(&fs_info->scrub_lock);
4042                 wait_event(fs_info->scrub_pause_wait,
4043                            dev->scrub_device == NULL);
4044                 mutex_lock(&fs_info->scrub_lock);
4045         }
4046         mutex_unlock(&fs_info->scrub_lock);
4047
4048         return 0;
4049 }
4050
4051 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
4052                          struct btrfs_scrub_progress *progress)
4053 {
4054         struct btrfs_device *dev;
4055         struct scrub_ctx *sctx = NULL;
4056
4057         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
4058         dev = btrfs_find_device(root->fs_info, devid, NULL, NULL);
4059         if (dev)
4060                 sctx = dev->scrub_device;
4061         if (sctx)
4062                 memcpy(progress, &sctx->stat, sizeof(*progress));
4063         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
4064
4065         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
4066 }
4067
4068 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
4069                                u64 extent_logical, u64 extent_len,
4070                                u64 *extent_physical,
4071                                struct btrfs_device **extent_dev,
4072                                int *extent_mirror_num)
4073 {
4074         u64 mapped_length;
4075         struct btrfs_bio *bbio = NULL;
4076         int ret;
4077
4078         mapped_length = extent_len;
4079         ret = btrfs_map_block(fs_info, READ, extent_logical,
4080                               &mapped_length, &bbio, 0);
4081         if (ret || !bbio || mapped_length < extent_len ||
4082             !bbio->stripes[0].dev->bdev) {
4083                 btrfs_put_bbio(bbio);
4084                 return;
4085         }
4086
4087         *extent_physical = bbio->stripes[0].physical;
4088         *extent_mirror_num = bbio->mirror_num;
4089         *extent_dev = bbio->stripes[0].dev;
4090         btrfs_put_bbio(bbio);
4091 }
4092
4093 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
4094                               struct scrub_wr_ctx *wr_ctx,
4095                               struct btrfs_fs_info *fs_info,
4096                               struct btrfs_device *dev,
4097                               int is_dev_replace)
4098 {
4099         WARN_ON(wr_ctx->wr_curr_bio != NULL);
4100
4101         mutex_init(&wr_ctx->wr_lock);
4102         wr_ctx->wr_curr_bio = NULL;
4103         if (!is_dev_replace)
4104                 return 0;
4105
4106         WARN_ON(!dev->bdev);
4107         wr_ctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
4108         wr_ctx->tgtdev = dev;
4109         atomic_set(&wr_ctx->flush_all_writes, 0);
4110         return 0;
4111 }
4112
4113 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
4114 {
4115         mutex_lock(&wr_ctx->wr_lock);
4116         kfree(wr_ctx->wr_curr_bio);
4117         wr_ctx->wr_curr_bio = NULL;
4118         mutex_unlock(&wr_ctx->wr_lock);
4119 }
4120
4121 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
4122                             int mirror_num, u64 physical_for_dev_replace)
4123 {
4124         struct scrub_copy_nocow_ctx *nocow_ctx;
4125         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
4126
4127         nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
4128         if (!nocow_ctx) {
4129                 spin_lock(&sctx->stat_lock);
4130                 sctx->stat.malloc_errors++;
4131                 spin_unlock(&sctx->stat_lock);
4132                 return -ENOMEM;
4133         }
4134
4135         scrub_pending_trans_workers_inc(sctx);
4136
4137         nocow_ctx->sctx = sctx;
4138         nocow_ctx->logical = logical;
4139         nocow_ctx->len = len;
4140         nocow_ctx->mirror_num = mirror_num;
4141         nocow_ctx->physical_for_dev_replace = physical_for_dev_replace;
4142         btrfs_init_work(&nocow_ctx->work, btrfs_scrubnc_helper,
4143                         copy_nocow_pages_worker, NULL, NULL);
4144         INIT_LIST_HEAD(&nocow_ctx->inodes);
4145         btrfs_queue_work(fs_info->scrub_nocow_workers,
4146                          &nocow_ctx->work);
4147
4148         return 0;
4149 }
4150
4151 static int record_inode_for_nocow(u64 inum, u64 offset, u64 root, void *ctx)
4152 {
4153         struct scrub_copy_nocow_ctx *nocow_ctx = ctx;
4154         struct scrub_nocow_inode *nocow_inode;
4155
4156         nocow_inode = kzalloc(sizeof(*nocow_inode), GFP_NOFS);
4157         if (!nocow_inode)
4158                 return -ENOMEM;
4159         nocow_inode->inum = inum;
4160         nocow_inode->offset = offset;
4161         nocow_inode->root = root;
4162         list_add_tail(&nocow_inode->list, &nocow_ctx->inodes);
4163         return 0;
4164 }
4165
4166 #define COPY_COMPLETE 1
4167
4168 static void copy_nocow_pages_worker(struct btrfs_work *work)
4169 {
4170         struct scrub_copy_nocow_ctx *nocow_ctx =
4171                 container_of(work, struct scrub_copy_nocow_ctx, work);
4172         struct scrub_ctx *sctx = nocow_ctx->sctx;
4173         u64 logical = nocow_ctx->logical;
4174         u64 len = nocow_ctx->len;
4175         int mirror_num = nocow_ctx->mirror_num;
4176         u64 physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
4177         int ret;
4178         struct btrfs_trans_handle *trans = NULL;
4179         struct btrfs_fs_info *fs_info;
4180         struct btrfs_path *path;
4181         struct btrfs_root *root;
4182         int not_written = 0;
4183
4184         fs_info = sctx->dev_root->fs_info;
4185         root = fs_info->extent_root;
4186
4187         path = btrfs_alloc_path();
4188         if (!path) {
4189                 spin_lock(&sctx->stat_lock);
4190                 sctx->stat.malloc_errors++;
4191                 spin_unlock(&sctx->stat_lock);
4192                 not_written = 1;
4193                 goto out;
4194         }
4195
4196         trans = btrfs_join_transaction(root);
4197         if (IS_ERR(trans)) {
4198                 not_written = 1;
4199                 goto out;
4200         }
4201
4202         ret = iterate_inodes_from_logical(logical, fs_info, path,
4203                                           record_inode_for_nocow, nocow_ctx);
4204         if (ret != 0 && ret != -ENOENT) {
4205                 btrfs_warn(fs_info, "iterate_inodes_from_logical() failed: log %llu, "
4206                         "phys %llu, len %llu, mir %u, ret %d",
4207                         logical, physical_for_dev_replace, len, mirror_num,
4208                         ret);
4209                 not_written = 1;
4210                 goto out;
4211         }
4212
4213         btrfs_end_transaction(trans, root);
4214         trans = NULL;
4215         while (!list_empty(&nocow_ctx->inodes)) {
4216                 struct scrub_nocow_inode *entry;
4217                 entry = list_first_entry(&nocow_ctx->inodes,
4218                                          struct scrub_nocow_inode,
4219                                          list);
4220                 list_del_init(&entry->list);
4221                 ret = copy_nocow_pages_for_inode(entry->inum, entry->offset,
4222                                                  entry->root, nocow_ctx);
4223                 kfree(entry);
4224                 if (ret == COPY_COMPLETE) {
4225                         ret = 0;
4226                         break;
4227                 } else if (ret) {
4228                         break;
4229                 }
4230         }
4231 out:
4232         while (!list_empty(&nocow_ctx->inodes)) {
4233                 struct scrub_nocow_inode *entry;
4234                 entry = list_first_entry(&nocow_ctx->inodes,
4235                                          struct scrub_nocow_inode,
4236                                          list);
4237                 list_del_init(&entry->list);
4238                 kfree(entry);
4239         }
4240         if (trans && !IS_ERR(trans))
4241                 btrfs_end_transaction(trans, root);
4242         if (not_written)
4243                 btrfs_dev_replace_stats_inc(&fs_info->dev_replace.
4244                                             num_uncorrectable_read_errors);
4245
4246         btrfs_free_path(path);
4247         kfree(nocow_ctx);
4248
4249         scrub_pending_trans_workers_dec(sctx);
4250 }
4251
4252 static int check_extent_to_block(struct inode *inode, u64 start, u64 len,
4253                                  u64 logical)
4254 {
4255         struct extent_state *cached_state = NULL;
4256         struct btrfs_ordered_extent *ordered;
4257         struct extent_io_tree *io_tree;
4258         struct extent_map *em;
4259         u64 lockstart = start, lockend = start + len - 1;
4260         int ret = 0;
4261
4262         io_tree = &BTRFS_I(inode)->io_tree;
4263
4264         lock_extent_bits(io_tree, lockstart, lockend, &cached_state);
4265         ordered = btrfs_lookup_ordered_range(inode, lockstart, len);
4266         if (ordered) {
4267                 btrfs_put_ordered_extent(ordered);
4268                 ret = 1;
4269                 goto out_unlock;
4270         }
4271
4272         em = btrfs_get_extent(inode, NULL, 0, start, len, 0);
4273         if (IS_ERR(em)) {
4274                 ret = PTR_ERR(em);
4275                 goto out_unlock;
4276         }
4277
4278         /*
4279          * This extent does not actually cover the logical extent anymore,
4280          * move on to the next inode.
4281          */
4282         if (em->block_start > logical ||
4283             em->block_start + em->block_len < logical + len) {
4284                 free_extent_map(em);
4285                 ret = 1;
4286                 goto out_unlock;
4287         }
4288         free_extent_map(em);
4289
4290 out_unlock:
4291         unlock_extent_cached(io_tree, lockstart, lockend, &cached_state,
4292                              GFP_NOFS);
4293         return ret;
4294 }
4295
4296 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
4297                                       struct scrub_copy_nocow_ctx *nocow_ctx)
4298 {
4299         struct btrfs_fs_info *fs_info = nocow_ctx->sctx->dev_root->fs_info;
4300         struct btrfs_key key;
4301         struct inode *inode;
4302         struct page *page;
4303         struct btrfs_root *local_root;
4304         struct extent_io_tree *io_tree;
4305         u64 physical_for_dev_replace;
4306         u64 nocow_ctx_logical;
4307         u64 len = nocow_ctx->len;
4308         unsigned long index;
4309         int srcu_index;
4310         int ret = 0;
4311         int err = 0;
4312
4313         key.objectid = root;
4314         key.type = BTRFS_ROOT_ITEM_KEY;
4315         key.offset = (u64)-1;
4316
4317         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
4318
4319         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
4320         if (IS_ERR(local_root)) {
4321                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
4322                 return PTR_ERR(local_root);
4323         }
4324
4325         key.type = BTRFS_INODE_ITEM_KEY;
4326         key.objectid = inum;
4327         key.offset = 0;
4328         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
4329         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
4330         if (IS_ERR(inode))
4331                 return PTR_ERR(inode);
4332
4333         /* Avoid truncate/dio/punch hole.. */
4334         inode_lock(inode);
4335         inode_dio_wait(inode);
4336
4337         physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
4338         io_tree = &BTRFS_I(inode)->io_tree;
4339         nocow_ctx_logical = nocow_ctx->logical;
4340
4341         ret = check_extent_to_block(inode, offset, len, nocow_ctx_logical);
4342         if (ret) {
4343                 ret = ret > 0 ? 0 : ret;
4344                 goto out;
4345         }
4346
4347         while (len >= PAGE_SIZE) {
4348                 index = offset >> PAGE_SHIFT;
4349 again:
4350                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
4351                 if (!page) {
4352                         btrfs_err(fs_info, "find_or_create_page() failed");
4353                         ret = -ENOMEM;
4354                         goto out;
4355                 }
4356
4357                 if (PageUptodate(page)) {
4358                         if (PageDirty(page))
4359                                 goto next_page;
4360                 } else {
4361                         ClearPageError(page);
4362                         err = extent_read_full_page(io_tree, page,
4363                                                            btrfs_get_extent,
4364                                                            nocow_ctx->mirror_num);
4365                         if (err) {
4366                                 ret = err;
4367                                 goto next_page;
4368                         }
4369
4370                         lock_page(page);
4371                         /*
4372                          * If the page has been remove from the page cache,
4373                          * the data on it is meaningless, because it may be
4374                          * old one, the new data may be written into the new
4375                          * page in the page cache.
4376                          */
4377                         if (page->mapping != inode->i_mapping) {
4378                                 unlock_page(page);
4379                                 put_page(page);
4380                                 goto again;
4381                         }
4382                         if (!PageUptodate(page)) {
4383                                 ret = -EIO;
4384                                 goto next_page;
4385                         }
4386                 }
4387
4388                 ret = check_extent_to_block(inode, offset, len,
4389                                             nocow_ctx_logical);
4390                 if (ret) {
4391                         ret = ret > 0 ? 0 : ret;
4392                         goto next_page;
4393                 }
4394
4395                 err = write_page_nocow(nocow_ctx->sctx,
4396                                        physical_for_dev_replace, page);
4397                 if (err)
4398                         ret = err;
4399 next_page:
4400                 unlock_page(page);
4401                 put_page(page);
4402
4403                 if (ret)
4404                         break;
4405
4406                 offset += PAGE_SIZE;
4407                 physical_for_dev_replace += PAGE_SIZE;
4408                 nocow_ctx_logical += PAGE_SIZE;
4409                 len -= PAGE_SIZE;
4410         }
4411         ret = COPY_COMPLETE;
4412 out:
4413         inode_unlock(inode);
4414         iput(inode);
4415         return ret;
4416 }
4417
4418 static int write_page_nocow(struct scrub_ctx *sctx,
4419                             u64 physical_for_dev_replace, struct page *page)
4420 {
4421         struct bio *bio;
4422         struct btrfs_device *dev;
4423         int ret;
4424
4425         dev = sctx->wr_ctx.tgtdev;
4426         if (!dev)
4427                 return -EIO;
4428         if (!dev->bdev) {
4429                 btrfs_warn_rl(dev->dev_root->fs_info,
4430                         "scrub write_page_nocow(bdev == NULL) is unexpected");
4431                 return -EIO;
4432         }
4433         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
4434         if (!bio) {
4435                 spin_lock(&sctx->stat_lock);
4436                 sctx->stat.malloc_errors++;
4437                 spin_unlock(&sctx->stat_lock);
4438                 return -ENOMEM;
4439         }
4440         bio->bi_iter.bi_size = 0;
4441         bio->bi_iter.bi_sector = physical_for_dev_replace >> 9;
4442         bio->bi_bdev = dev->bdev;
4443         bio_set_op_attrs(bio, REQ_OP_WRITE, WRITE_SYNC);
4444         ret = bio_add_page(bio, page, PAGE_SIZE, 0);
4445         if (ret != PAGE_SIZE) {
4446 leave_with_eio:
4447                 bio_put(bio);
4448                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
4449                 return -EIO;
4450         }
4451
4452         if (btrfsic_submit_bio_wait(bio))
4453                 goto leave_with_eio;
4454
4455         bio_put(bio);
4456         return 0;
4457 }