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 <linux/sched/mm.h>
  22 #include "ctree.h"
  23 #include "volumes.h"
  24 #include "disk-io.h"
  25 #include "ordered-data.h"
  26 #include "transaction.h"
  27 #include "backref.h"
  28 #include "extent_io.h"
  29 #include "dev-replace.h"
  30 #include "check-integrity.h"
  31 #include "rcu-string.h"
  32 #include "raid56.h"
  33
  34 /*
  35  * This is only the first step towards a full-features scrub. It reads all
  36  * extent and super block and verifies the checksums. In case a bad checksum
  37  * is found or the extent cannot be read, good data will be written back if
  38  * any can be found.
  39  *
  40  * Future enhancements:
  41  *  - In case an unrepairable extent is encountered, track which files are
  42  *    affected and report them
  43  *  - track and record media errors, throw out bad devices
  44  *  - add a mode to also read unallocated space
  45  */
  46
  47 struct scrub_block;
  48 struct scrub_ctx;
  49
  50 /*
  51  * the following three values only influence the performance.
  52  * The last one configures the number of parallel and outstanding I/O
  53  * operations. The first two values configure an upper limit for the number
  54  * of (dynamically allocated) pages that are added to a bio.
  55  */
  56 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  57 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  58 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  59
  60 /*
  61  * the following value times PAGE_SIZE needs to be large enough to match the
  62  * largest node/leaf/sector size that shall be supported.
  63  * Values larger than BTRFS_STRIPE_LEN are not supported.
  64  */
  65 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  66
  67 struct scrub_recover {
  68         refcount_t              refs;
  69         struct btrfs_bio        *bbio;
  70         u64                     map_length;
  71 };
  72
  73 struct scrub_page {
  74         struct scrub_block      *sblock;
  75         struct page             *page;
  76         struct btrfs_device     *dev;
  77         struct list_head        list;
  78         u64                     flags;  /* extent flags */
  79         u64                     generation;
  80         u64                     logical;
  81         u64                     physical;
  82         u64                     physical_for_dev_replace;
  83         atomic_t                refs;
  84         struct {
  85                 unsigned int    mirror_num:8;
  86                 unsigned int    have_csum:1;
  87                 unsigned int    io_error:1;
  88         };
  89         u8                      csum[BTRFS_CSUM_SIZE];
  90
  91         struct scrub_recover    *recover;
  92 };
  93
  94 struct scrub_bio {
  95         int                     index;
  96         struct scrub_ctx        *sctx;
  97         struct btrfs_device     *dev;
  98         struct bio              *bio;
  99         blk_status_t            status;
 100         u64                     logical;
 101         u64                     physical;
 102 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
 103         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
 104 #else
 105         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
 106 #endif
 107         int                     page_count;
 108         int                     next_free;
 109         struct btrfs_work       work;
 110 };
 111
 112 struct scrub_block {
 113         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 114         int                     page_count;
 115         atomic_t                outstanding_pages;
 116         refcount_t              refs; /* free mem on transition to zero */
 117         struct scrub_ctx        *sctx;
 118         struct scrub_parity     *sparity;
 119         struct {
 120                 unsigned int    header_error:1;
 121                 unsigned int    checksum_error:1;
 122                 unsigned int    no_io_error_seen:1;
 123                 unsigned int    generation_error:1; /* also sets header_error */
 124
 125                 /* The following is for the data used to check parity */
 126                 /* It is for the data with checksum */
 127                 unsigned int    data_corrected:1;
 128         };
 129         struct btrfs_work       work;
 130 };
 131
 132 /* Used for the chunks with parity stripe such RAID5/6 */
 133 struct scrub_parity {
 134         struct scrub_ctx        *sctx;
 135
 136         struct btrfs_device     *scrub_dev;
 137
 138         u64                     logic_start;
 139
 140         u64                     logic_end;
 141
 142         int                     nsectors;
 143
 144         u64                     stripe_len;
 145
 146         refcount_t              refs;
 147
 148         struct list_head        spages;
 149
 150         /* Work of parity check and repair */
 151         struct btrfs_work       work;
 152
 153         /* Mark the parity blocks which have data */
 154         unsigned long           *dbitmap;
 155
 156         /*
 157          * Mark the parity blocks which have data, but errors happen when
 158          * read data or check data
 159          */
 160         unsigned long           *ebitmap;
 161
 162         unsigned long           bitmap[0];
 163 };
 164
 165 struct scrub_ctx {
 166         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 167         struct btrfs_fs_info    *fs_info;
 168         int                     first_free;
 169         int                     curr;
 170         atomic_t                bios_in_flight;
 171         atomic_t                workers_pending;
 172         spinlock_t              list_lock;
 173         wait_queue_head_t       list_wait;
 174         u16                     csum_size;
 175         struct list_head        csum_list;
 176         atomic_t                cancel_req;
 177         int                     readonly;
 178         int                     pages_per_rd_bio;
 179
 180         int                     is_dev_replace;
 181
 182         struct scrub_bio        *wr_curr_bio;
 183         struct mutex            wr_lock;
 184         int                     pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 185         struct btrfs_device     *wr_tgtdev;
 186         bool                    flush_all_writes;
 187
 188         /*
 189          * statistics
 190          */
 191         struct btrfs_scrub_progress stat;
 192         spinlock_t              stat_lock;
 193
 194         /*
 195          * Use a ref counter to avoid use-after-free issues. Scrub workers
 196          * decrement bios_in_flight and workers_pending and then do a wakeup
 197          * on the list_wait wait queue. We must ensure the main scrub task
 198          * doesn't free the scrub context before or while the workers are
 199          * doing the wakeup() call.
 200          */
 201         refcount_t              refs;
 202 };
 203
 204 struct scrub_fixup_nodatasum {
 205         struct scrub_ctx        *sctx;
 206         struct btrfs_device     *dev;
 207         u64                     logical;
 208         struct btrfs_root       *root;
 209         struct btrfs_work       work;
 210         int                     mirror_num;
 211 };
 212
 213 struct scrub_nocow_inode {
 214         u64                     inum;
 215         u64                     offset;
 216         u64                     root;
 217         struct list_head        list;
 218 };
 219
 220 struct scrub_copy_nocow_ctx {
 221         struct scrub_ctx        *sctx;
 222         u64                     logical;
 223         u64                     len;
 224         int                     mirror_num;
 225         u64                     physical_for_dev_replace;
 226         struct list_head        inodes;
 227         struct btrfs_work       work;
 228 };
 229
 230 struct scrub_warning {
 231         struct btrfs_path       *path;
 232         u64                     extent_item_size;
 233         const char              *errstr;
 234         sector_t                sector;
 235         u64                     logical;
 236         struct btrfs_device     *dev;
 237 };
 238
 239 struct full_stripe_lock {
 240         struct rb_node node;
 241         u64 logical;
 242         u64 refs;
 243         struct mutex mutex;
 244 };
 245
 246 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 247 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 248 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
 249 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
 250 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 251 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 252                                      struct scrub_block *sblocks_for_recheck);
 253 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 254                                 struct scrub_block *sblock,
 255                                 int retry_failed_mirror);
 256 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 257 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 258                                              struct scrub_block *sblock_good);
 259 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 260                                             struct scrub_block *sblock_good,
 261                                             int page_num, int force_write);
 262 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 263 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 264                                            int page_num);
 265 static int scrub_checksum_data(struct scrub_block *sblock);
 266 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 267 static int scrub_checksum_super(struct scrub_block *sblock);
 268 static void scrub_block_get(struct scrub_block *sblock);
 269 static void scrub_block_put(struct scrub_block *sblock);
 270 static void scrub_page_get(struct scrub_page *spage);
 271 static void scrub_page_put(struct scrub_page *spage);
 272 static void scrub_parity_get(struct scrub_parity *sparity);
 273 static void scrub_parity_put(struct scrub_parity *sparity);
 274 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 275                                     struct scrub_page *spage);
 276 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 277                        u64 physical, struct btrfs_device *dev, u64 flags,
 278                        u64 gen, int mirror_num, u8 *csum, int force,
 279                        u64 physical_for_dev_replace);
 280 static void scrub_bio_end_io(struct bio *bio);
 281 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 282 static void scrub_block_complete(struct scrub_block *sblock);
 283 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 284                                u64 extent_logical, u64 extent_len,
 285                                u64 *extent_physical,
 286                                struct btrfs_device **extent_dev,
 287                                int *extent_mirror_num);
 288 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 289                                     struct scrub_page *spage);
 290 static void scrub_wr_submit(struct scrub_ctx *sctx);
 291 static void scrub_wr_bio_end_io(struct bio *bio);
 292 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 293 static int write_page_nocow(struct scrub_ctx *sctx,
 294                             u64 physical_for_dev_replace, struct page *page);
 295 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
 296                                       struct scrub_copy_nocow_ctx *ctx);
 297 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 298                             int mirror_num, u64 physical_for_dev_replace);
 299 static void copy_nocow_pages_worker(struct btrfs_work *work);
 300 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 301 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 302 static void scrub_put_ctx(struct scrub_ctx *sctx);
 303
 304 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
 305 {
 306         return page->recover &&
 307                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
 308 }
 309
 310 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 311 {
 312         refcount_inc(&sctx->refs);
 313         atomic_inc(&sctx->bios_in_flight);
 314 }
 315
 316 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 317 {
 318         atomic_dec(&sctx->bios_in_flight);
 319         wake_up(&sctx->list_wait);
 320         scrub_put_ctx(sctx);
 321 }
 322
 323 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 324 {
 325         while (atomic_read(&fs_info->scrub_pause_req)) {
 326                 mutex_unlock(&fs_info->scrub_lock);
 327                 wait_event(fs_info->scrub_pause_wait,
 328                    atomic_read(&fs_info->scrub_pause_req) == 0);
 329                 mutex_lock(&fs_info->scrub_lock);
 330         }
 331 }
 332
 333 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 334 {
 335         atomic_inc(&fs_info->scrubs_paused);
 336         wake_up(&fs_info->scrub_pause_wait);
 337 }
 338
 339 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 340 {
 341         mutex_lock(&fs_info->scrub_lock);
 342         __scrub_blocked_if_needed(fs_info);
 343         atomic_dec(&fs_info->scrubs_paused);
 344         mutex_unlock(&fs_info->scrub_lock);
 345
 346         wake_up(&fs_info->scrub_pause_wait);
 347 }
 348
 349 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 350 {
 351         scrub_pause_on(fs_info);
 352         scrub_pause_off(fs_info);
 353 }
 354
 355 /*
 356  * Insert new full stripe lock into full stripe locks tree
 357  *
 358  * Return pointer to existing or newly inserted full_stripe_lock structure if
 359  * everything works well.
 360  * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
 361  *
 362  * NOTE: caller must hold full_stripe_locks_root->lock before calling this
 363  * function
 364  */
 365 static struct full_stripe_lock *insert_full_stripe_lock(
 366                 struct btrfs_full_stripe_locks_tree *locks_root,
 367                 u64 fstripe_logical)
 368 {
 369         struct rb_node **p;
 370         struct rb_node *parent = NULL;
 371         struct full_stripe_lock *entry;
 372         struct full_stripe_lock *ret;
 373
 374         WARN_ON(!mutex_is_locked(&locks_root->lock));
 375
 376         p = &locks_root->root.rb_node;
 377         while (*p) {
 378                 parent = *p;
 379                 entry = rb_entry(parent, struct full_stripe_lock, node);
 380                 if (fstripe_logical < entry->logical) {
 381                         p = &(*p)->rb_left;
 382                 } else if (fstripe_logical > entry->logical) {
 383                         p = &(*p)->rb_right;
 384                 } else {
 385                         entry->refs++;
 386                         return entry;
 387                 }
 388         }
 389
 390         /* Insert new lock */
 391         ret = kmalloc(sizeof(*ret), GFP_KERNEL);
 392         if (!ret)
 393                 return ERR_PTR(-ENOMEM);
 394         ret->logical = fstripe_logical;
 395         ret->refs = 1;
 396         mutex_init(&ret->mutex);
 397
 398         rb_link_node(&ret->node, parent, p);
 399         rb_insert_color(&ret->node, &locks_root->root);
 400         return ret;
 401 }
 402
 403 /*
 404  * Search for a full stripe lock of a block group
 405  *
 406  * Return pointer to existing full stripe lock if found
 407  * Return NULL if not found
 408  */
 409 static struct full_stripe_lock *search_full_stripe_lock(
 410                 struct btrfs_full_stripe_locks_tree *locks_root,
 411                 u64 fstripe_logical)
 412 {
 413         struct rb_node *node;
 414         struct full_stripe_lock *entry;
 415
 416         WARN_ON(!mutex_is_locked(&locks_root->lock));
 417
 418         node = locks_root->root.rb_node;
 419         while (node) {
 420                 entry = rb_entry(node, struct full_stripe_lock, node);
 421                 if (fstripe_logical < entry->logical)
 422                         node = node->rb_left;
 423                 else if (fstripe_logical > entry->logical)
 424                         node = node->rb_right;
 425                 else
 426                         return entry;
 427         }
 428         return NULL;
 429 }
 430
 431 /*
 432  * Helper to get full stripe logical from a normal bytenr.
 433  *
 434  * Caller must ensure @cache is a RAID56 block group.
 435  */
 436 static u64 get_full_stripe_logical(struct btrfs_block_group_cache *cache,
 437                                    u64 bytenr)
 438 {
 439         u64 ret;
 440
 441         /*
 442          * Due to chunk item size limit, full stripe length should not be
 443          * larger than U32_MAX. Just a sanity check here.
 444          */
 445         WARN_ON_ONCE(cache->full_stripe_len >= U32_MAX);
 446
 447         /*
 448          * round_down() can only handle power of 2, while RAID56 full
 449          * stripe length can be 64KiB * n, so we need to manually round down.
 450          */
 451         ret = div64_u64(bytenr - cache->key.objectid, cache->full_stripe_len) *
 452                 cache->full_stripe_len + cache->key.objectid;
 453         return ret;
 454 }
 455
 456 /*
 457  * Lock a full stripe to avoid concurrency of recovery and read
 458  *
 459  * It's only used for profiles with parities (RAID5/6), for other profiles it
 460  * does nothing.
 461  *
 462  * Return 0 if we locked full stripe covering @bytenr, with a mutex held.
 463  * So caller must call unlock_full_stripe() at the same context.
 464  *
 465  * Return <0 if encounters error.
 466  */
 467 static int lock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 468                             bool *locked_ret)
 469 {
 470         struct btrfs_block_group_cache *bg_cache;
 471         struct btrfs_full_stripe_locks_tree *locks_root;
 472         struct full_stripe_lock *existing;
 473         u64 fstripe_start;
 474         int ret = 0;
 475
 476         *locked_ret = false;
 477         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 478         if (!bg_cache) {
 479                 ASSERT(0);
 480                 return -ENOENT;
 481         }
 482
 483         /* Profiles not based on parity don't need full stripe lock */
 484         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 485                 goto out;
 486         locks_root = &bg_cache->full_stripe_locks_root;
 487
 488         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 489
 490         /* Now insert the full stripe lock */
 491         mutex_lock(&locks_root->lock);
 492         existing = insert_full_stripe_lock(locks_root, fstripe_start);
 493         mutex_unlock(&locks_root->lock);
 494         if (IS_ERR(existing)) {
 495                 ret = PTR_ERR(existing);
 496                 goto out;
 497         }
 498         mutex_lock(&existing->mutex);
 499         *locked_ret = true;
 500 out:
 501         btrfs_put_block_group(bg_cache);
 502         return ret;
 503 }
 504
 505 /*
 506  * Unlock a full stripe.
 507  *
 508  * NOTE: Caller must ensure it's the same context calling corresponding
 509  * lock_full_stripe().
 510  *
 511  * Return 0 if we unlock full stripe without problem.
 512  * Return <0 for error
 513  */
 514 static int unlock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 515                               bool locked)
 516 {
 517         struct btrfs_block_group_cache *bg_cache;
 518         struct btrfs_full_stripe_locks_tree *locks_root;
 519         struct full_stripe_lock *fstripe_lock;
 520         u64 fstripe_start;
 521         bool freeit = false;
 522         int ret = 0;
 523
 524         /* If we didn't acquire full stripe lock, no need to continue */
 525         if (!locked)
 526                 return 0;
 527
 528         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 529         if (!bg_cache) {
 530                 ASSERT(0);
 531                 return -ENOENT;
 532         }
 533         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 534                 goto out;
 535
 536         locks_root = &bg_cache->full_stripe_locks_root;
 537         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 538
 539         mutex_lock(&locks_root->lock);
 540         fstripe_lock = search_full_stripe_lock(locks_root, fstripe_start);
 541         /* Unpaired unlock_full_stripe() detected */
 542         if (!fstripe_lock) {
 543                 WARN_ON(1);
 544                 ret = -ENOENT;
 545                 mutex_unlock(&locks_root->lock);
 546                 goto out;
 547         }
 548
 549         if (fstripe_lock->refs == 0) {
 550                 WARN_ON(1);
 551                 btrfs_warn(fs_info, "full stripe lock at %llu refcount underflow",
 552                         fstripe_lock->logical);
 553         } else {
 554                 fstripe_lock->refs--;
 555         }
 556
 557         if (fstripe_lock->refs == 0) {
 558                 rb_erase(&fstripe_lock->node, &locks_root->root);
 559                 freeit = true;
 560         }
 561         mutex_unlock(&locks_root->lock);
 562
 563         mutex_unlock(&fstripe_lock->mutex);
 564         if (freeit)
 565                 kfree(fstripe_lock);
 566 out:
 567         btrfs_put_block_group(bg_cache);
 568         return ret;
 569 }
 570
 571 /*
 572  * used for workers that require transaction commits (i.e., for the
 573  * NOCOW case)
 574  */
 575 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
 576 {
 577         struct btrfs_fs_info *fs_info = sctx->fs_info;
 578
 579         refcount_inc(&sctx->refs);
 580         /*
 581          * increment scrubs_running to prevent cancel requests from
 582          * completing as long as a worker is running. we must also
 583          * increment scrubs_paused to prevent deadlocking on pause
 584          * requests used for transactions commits (as the worker uses a
 585          * transaction context). it is safe to regard the worker
 586          * as paused for all matters practical. effectively, we only
 587          * avoid cancellation requests from completing.
 588          */
 589         mutex_lock(&fs_info->scrub_lock);
 590         atomic_inc(&fs_info->scrubs_running);
 591         atomic_inc(&fs_info->scrubs_paused);
 592         mutex_unlock(&fs_info->scrub_lock);
 593
 594         /*
 595          * check if @scrubs_running=@scrubs_paused condition
 596          * inside wait_event() is not an atomic operation.
 597          * which means we may inc/dec @scrub_running/paused
 598          * at any time. Let's wake up @scrub_pause_wait as
 599          * much as we can to let commit transaction blocked less.
 600          */
 601         wake_up(&fs_info->scrub_pause_wait);
 602
 603         atomic_inc(&sctx->workers_pending);
 604 }
 605
 606 /* used for workers that require transaction commits */
 607 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
 608 {
 609         struct btrfs_fs_info *fs_info = sctx->fs_info;
 610
 611         /*
 612          * see scrub_pending_trans_workers_inc() why we're pretending
 613          * to be paused in the scrub counters
 614          */
 615         mutex_lock(&fs_info->scrub_lock);
 616         atomic_dec(&fs_info->scrubs_running);
 617         atomic_dec(&fs_info->scrubs_paused);
 618         mutex_unlock(&fs_info->scrub_lock);
 619         atomic_dec(&sctx->workers_pending);
 620         wake_up(&fs_info->scrub_pause_wait);
 621         wake_up(&sctx->list_wait);
 622         scrub_put_ctx(sctx);
 623 }
 624
 625 static void scrub_free_csums(struct scrub_ctx *sctx)
 626 {
 627         while (!list_empty(&sctx->csum_list)) {
 628                 struct btrfs_ordered_sum *sum;
 629                 sum = list_first_entry(&sctx->csum_list,
 630                                        struct btrfs_ordered_sum, list);
 631                 list_del(&sum->list);
 632                 kfree(sum);
 633         }
 634 }
 635
 636 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 637 {
 638         int i;
 639
 640         if (!sctx)
 641                 return;
 642
 643         /* this can happen when scrub is cancelled */
 644         if (sctx->curr != -1) {
 645                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 646
 647                 for (i = 0; i < sbio->page_count; i++) {
 648                         WARN_ON(!sbio->pagev[i]->page);
 649                         scrub_block_put(sbio->pagev[i]->sblock);
 650                 }
 651                 bio_put(sbio->bio);
 652         }
 653
 654         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 655                 struct scrub_bio *sbio = sctx->bios[i];
 656
 657                 if (!sbio)
 658                         break;
 659                 kfree(sbio);
 660         }
 661
 662         kfree(sctx->wr_curr_bio);
 663         scrub_free_csums(sctx);
 664         kfree(sctx);
 665 }
 666
 667 static void scrub_put_ctx(struct scrub_ctx *sctx)
 668 {
 669         if (refcount_dec_and_test(&sctx->refs))
 670                 scrub_free_ctx(sctx);
 671 }
 672
 673 static noinline_for_stack
 674 struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 675 {
 676         struct scrub_ctx *sctx;
 677         int             i;
 678         struct btrfs_fs_info *fs_info = dev->fs_info;
 679
 680         sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 681         if (!sctx)
 682                 goto nomem;
 683         refcount_set(&sctx->refs, 1);
 684         sctx->is_dev_replace = is_dev_replace;
 685         sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 686         sctx->curr = -1;
 687         sctx->fs_info = dev->fs_info;
 688         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 689                 struct scrub_bio *sbio;
 690
 691                 sbio = kzalloc(sizeof(*sbio), GFP_KERNEL);
 692                 if (!sbio)
 693                         goto nomem;
 694                 sctx->bios[i] = sbio;
 695
 696                 sbio->index = i;
 697                 sbio->sctx = sctx;
 698                 sbio->page_count = 0;
 699                 btrfs_init_work(&sbio->work, btrfs_scrub_helper,
 700                                 scrub_bio_end_io_worker, NULL, NULL);
 701
 702                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 703                         sctx->bios[i]->next_free = i + 1;
 704                 else
 705                         sctx->bios[i]->next_free = -1;
 706         }
 707         sctx->first_free = 0;
 708         atomic_set(&sctx->bios_in_flight, 0);
 709         atomic_set(&sctx->workers_pending, 0);
 710         atomic_set(&sctx->cancel_req, 0);
 711         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 712         INIT_LIST_HEAD(&sctx->csum_list);
 713
 714         spin_lock_init(&sctx->list_lock);
 715         spin_lock_init(&sctx->stat_lock);
 716         init_waitqueue_head(&sctx->list_wait);
 717
 718         WARN_ON(sctx->wr_curr_bio != NULL);
 719         mutex_init(&sctx->wr_lock);
 720         sctx->wr_curr_bio = NULL;
 721         if (is_dev_replace) {
 722                 WARN_ON(!fs_info->dev_replace.tgtdev);
 723                 sctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
 724                 sctx->wr_tgtdev = fs_info->dev_replace.tgtdev;
 725                 sctx->flush_all_writes = false;
 726         }
 727
 728         return sctx;
 729
 730 nomem:
 731         scrub_free_ctx(sctx);
 732         return ERR_PTR(-ENOMEM);
 733 }
 734
 735 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 736                                      void *warn_ctx)
 737 {
 738         u64 isize;
 739         u32 nlink;
 740         int ret;
 741         int i;
 742         unsigned nofs_flag;
 743         struct extent_buffer *eb;
 744         struct btrfs_inode_item *inode_item;
 745         struct scrub_warning *swarn = warn_ctx;
 746         struct btrfs_fs_info *fs_info = swarn->dev->fs_info;
 747         struct inode_fs_paths *ipath = NULL;
 748         struct btrfs_root *local_root;
 749         struct btrfs_key root_key;
 750         struct btrfs_key key;
 751
 752         root_key.objectid = root;
 753         root_key.type = BTRFS_ROOT_ITEM_KEY;
 754         root_key.offset = (u64)-1;
 755         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 756         if (IS_ERR(local_root)) {
 757                 ret = PTR_ERR(local_root);
 758                 goto err;
 759         }
 760
 761         /*
 762          * this makes the path point to (inum INODE_ITEM ioff)
 763          */
 764         key.objectid = inum;
 765         key.type = BTRFS_INODE_ITEM_KEY;
 766         key.offset = 0;
 767
 768         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 769         if (ret) {
 770                 btrfs_release_path(swarn->path);
 771                 goto err;
 772         }
 773
 774         eb = swarn->path->nodes[0];
 775         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 776                                         struct btrfs_inode_item);
 777         isize = btrfs_inode_size(eb, inode_item);
 778         nlink = btrfs_inode_nlink(eb, inode_item);
 779         btrfs_release_path(swarn->path);
 780
 781         /*
 782          * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
 783          * uses GFP_NOFS in this context, so we keep it consistent but it does
 784          * not seem to be strictly necessary.
 785          */
 786         nofs_flag = memalloc_nofs_save();
 787         ipath = init_ipath(4096, local_root, swarn->path);
 788         memalloc_nofs_restore(nofs_flag);
 789         if (IS_ERR(ipath)) {
 790                 ret = PTR_ERR(ipath);
 791                 ipath = NULL;
 792                 goto err;
 793         }
 794         ret = paths_from_inode(inum, ipath);
 795
 796         if (ret < 0)
 797                 goto err;
 798
 799         /*
 800          * we deliberately ignore the bit ipath might have been too small to
 801          * hold all of the paths here
 802          */
 803         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 804                 btrfs_warn_in_rcu(fs_info,
 805                                   "%s at logical %llu on dev %s, sector %llu, root %llu, inode %llu, offset %llu, length %llu, links %u (path: %s)",
 806                                   swarn->errstr, swarn->logical,
 807                                   rcu_str_deref(swarn->dev->name),
 808                                   (unsigned long long)swarn->sector,
 809                                   root, inum, offset,
 810                                   min(isize - offset, (u64)PAGE_SIZE), nlink,
 811                                   (char *)(unsigned long)ipath->fspath->val[i]);
 812
 813         free_ipath(ipath);
 814         return 0;
 815
 816 err:
 817         btrfs_warn_in_rcu(fs_info,
 818                           "%s at logical %llu on dev %s, sector %llu, root %llu, inode %llu, offset %llu: path resolving failed with ret=%d",
 819                           swarn->errstr, swarn->logical,
 820                           rcu_str_deref(swarn->dev->name),
 821                           (unsigned long long)swarn->sector,
 822                           root, inum, offset, ret);
 823
 824         free_ipath(ipath);
 825         return 0;
 826 }
 827
 828 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 829 {
 830         struct btrfs_device *dev;
 831         struct btrfs_fs_info *fs_info;
 832         struct btrfs_path *path;
 833         struct btrfs_key found_key;
 834         struct extent_buffer *eb;
 835         struct btrfs_extent_item *ei;
 836         struct scrub_warning swarn;
 837         unsigned long ptr = 0;
 838         u64 extent_item_pos;
 839         u64 flags = 0;
 840         u64 ref_root;
 841         u32 item_size;
 842         u8 ref_level = 0;
 843         int ret;
 844
 845         WARN_ON(sblock->page_count < 1);
 846         dev = sblock->pagev[0]->dev;
 847         fs_info = sblock->sctx->fs_info;
 848
 849         path = btrfs_alloc_path();
 850         if (!path)
 851                 return;
 852
 853         swarn.sector = (sblock->pagev[0]->physical) >> 9;
 854         swarn.logical = sblock->pagev[0]->logical;
 855         swarn.errstr = errstr;
 856         swarn.dev = NULL;
 857
 858         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 859                                   &flags);
 860         if (ret < 0)
 861                 goto out;
 862
 863         extent_item_pos = swarn.logical - found_key.objectid;
 864         swarn.extent_item_size = found_key.offset;
 865
 866         eb = path->nodes[0];
 867         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 868         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 869
 870         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 871                 do {
 872                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 873                                                       item_size, &ref_root,
 874                                                       &ref_level);
 875                         btrfs_warn_in_rcu(fs_info,
 876                                 "%s at logical %llu on dev %s, sector %llu: metadata %s (level %d) in tree %llu",
 877                                 errstr, swarn.logical,
 878                                 rcu_str_deref(dev->name),
 879                                 (unsigned long long)swarn.sector,
 880                                 ref_level ? "node" : "leaf",
 881                                 ret < 0 ? -1 : ref_level,
 882                                 ret < 0 ? -1 : ref_root);
 883                 } while (ret != 1);
 884                 btrfs_release_path(path);
 885         } else {
 886                 btrfs_release_path(path);
 887                 swarn.path = path;
 888                 swarn.dev = dev;
 889                 iterate_extent_inodes(fs_info, found_key.objectid,
 890                                         extent_item_pos, 1,
 891                                         scrub_print_warning_inode, &swarn);
 892         }
 893
 894 out:
 895         btrfs_free_path(path);
 896 }
 897
 898 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
 899 {
 900         struct page *page = NULL;
 901         unsigned long index;
 902         struct scrub_fixup_nodatasum *fixup = fixup_ctx;
 903         int ret;
 904         int corrected = 0;
 905         struct btrfs_key key;
 906         struct inode *inode = NULL;
 907         struct btrfs_fs_info *fs_info;
 908         u64 end = offset + PAGE_SIZE - 1;
 909         struct btrfs_root *local_root;
 910         int srcu_index;
 911
 912         key.objectid = root;
 913         key.type = BTRFS_ROOT_ITEM_KEY;
 914         key.offset = (u64)-1;
 915
 916         fs_info = fixup->root->fs_info;
 917         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
 918
 919         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
 920         if (IS_ERR(local_root)) {
 921                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 922                 return PTR_ERR(local_root);
 923         }
 924
 925         key.type = BTRFS_INODE_ITEM_KEY;
 926         key.objectid = inum;
 927         key.offset = 0;
 928         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
 929         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 930         if (IS_ERR(inode))
 931                 return PTR_ERR(inode);
 932
 933         index = offset >> PAGE_SHIFT;
 934
 935         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 936         if (!page) {
 937                 ret = -ENOMEM;
 938                 goto out;
 939         }
 940
 941         if (PageUptodate(page)) {
 942                 if (PageDirty(page)) {
 943                         /*
 944                          * we need to write the data to the defect sector. the
 945                          * data that was in that sector is not in memory,
 946                          * because the page was modified. we must not write the
 947                          * modified page to that sector.
 948                          *
 949                          * TODO: what could be done here: wait for the delalloc
 950                          *       runner to write out that page (might involve
 951                          *       COW) and see whether the sector is still
 952                          *       referenced afterwards.
 953                          *
 954                          * For the meantime, we'll treat this error
 955                          * incorrectable, although there is a chance that a
 956                          * later scrub will find the bad sector again and that
 957                          * there's no dirty page in memory, then.
 958                          */
 959                         ret = -EIO;
 960                         goto out;
 961                 }
 962                 ret = repair_io_failure(fs_info, inum, offset, PAGE_SIZE,
 963                                         fixup->logical, page,
 964                                         offset - page_offset(page),
 965                                         fixup->mirror_num);
 966                 unlock_page(page);
 967                 corrected = !ret;
 968         } else {
 969                 /*
 970                  * we need to get good data first. the general readpage path
 971                  * will call repair_io_failure for us, we just have to make
 972                  * sure we read the bad mirror.
 973                  */
 974                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 975                                         EXTENT_DAMAGED);
 976                 if (ret) {
 977                         /* set_extent_bits should give proper error */
 978                         WARN_ON(ret > 0);
 979                         if (ret > 0)
 980                                 ret = -EFAULT;
 981                         goto out;
 982                 }
 983
 984                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 985                                                 btrfs_get_extent,
 986                                                 fixup->mirror_num);
 987                 wait_on_page_locked(page);
 988
 989                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 990                                                 end, EXTENT_DAMAGED, 0, NULL);
 991                 if (!corrected)
 992                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 993                                                 EXTENT_DAMAGED);
 994         }
 995
 996 out:
 997         if (page)
 998                 put_page(page);
 999
1000         iput(inode);
1001
1002         if (ret < 0)
1003                 return ret;
1004
1005         if (ret == 0 && corrected) {
1006                 /*
1007                  * we only need to call readpage for one of the inodes belonging
1008                  * to this extent. so make iterate_extent_inodes stop
1009                  */
1010                 return 1;
1011         }
1012
1013         return -EIO;
1014 }
1015
1016 static void scrub_fixup_nodatasum(struct btrfs_work *work)
1017 {
1018         struct btrfs_fs_info *fs_info;
1019         int ret;
1020         struct scrub_fixup_nodatasum *fixup;
1021         struct scrub_ctx *sctx;
1022         struct btrfs_trans_handle *trans = NULL;
1023         struct btrfs_path *path;
1024         int uncorrectable = 0;
1025
1026         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
1027         sctx = fixup->sctx;
1028         fs_info = fixup->root->fs_info;
1029
1030         path = btrfs_alloc_path();
1031         if (!path) {
1032                 spin_lock(&sctx->stat_lock);
1033                 ++sctx->stat.malloc_errors;
1034                 spin_unlock(&sctx->stat_lock);
1035                 uncorrectable = 1;
1036                 goto out;
1037         }
1038
1039         trans = btrfs_join_transaction(fixup->root);
1040         if (IS_ERR(trans)) {
1041                 uncorrectable = 1;
1042                 goto out;
1043         }
1044
1045         /*
1046          * the idea is to trigger a regular read through the standard path. we
1047          * read a page from the (failed) logical address by specifying the
1048          * corresponding copynum of the failed sector. thus, that readpage is
1049          * expected to fail.
1050          * that is the point where on-the-fly error correction will kick in
1051          * (once it's finished) and rewrite the failed sector if a good copy
1052          * can be found.
1053          */
1054         ret = iterate_inodes_from_logical(fixup->logical, fs_info, path,
1055                                           scrub_fixup_readpage, fixup);
1056         if (ret < 0) {
1057                 uncorrectable = 1;
1058                 goto out;
1059         }
1060         WARN_ON(ret != 1);
1061
1062         spin_lock(&sctx->stat_lock);
1063         ++sctx->stat.corrected_errors;
1064         spin_unlock(&sctx->stat_lock);
1065
1066 out:
1067         if (trans && !IS_ERR(trans))
1068                 btrfs_end_transaction(trans);
1069         if (uncorrectable) {
1070                 spin_lock(&sctx->stat_lock);
1071                 ++sctx->stat.uncorrectable_errors;
1072                 spin_unlock(&sctx->stat_lock);
1073                 btrfs_dev_replace_stats_inc(
1074                         &fs_info->dev_replace.num_uncorrectable_read_errors);
1075                 btrfs_err_rl_in_rcu(fs_info,
1076                     "unable to fixup (nodatasum) error at logical %llu on dev %s",
1077                         fixup->logical, rcu_str_deref(fixup->dev->name));
1078         }
1079
1080         btrfs_free_path(path);
1081         kfree(fixup);
1082
1083         scrub_pending_trans_workers_dec(sctx);
1084 }
1085
1086 static inline void scrub_get_recover(struct scrub_recover *recover)
1087 {
1088         refcount_inc(&recover->refs);
1089 }
1090
1091 static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
1092                                      struct scrub_recover *recover)
1093 {
1094         if (refcount_dec_and_test(&recover->refs)) {
1095                 btrfs_bio_counter_dec(fs_info);
1096                 btrfs_put_bbio(recover->bbio);
1097                 kfree(recover);
1098         }
1099 }
1100
1101 /*
1102  * scrub_handle_errored_block gets called when either verification of the
1103  * pages failed or the bio failed to read, e.g. with EIO. In the latter
1104  * case, this function handles all pages in the bio, even though only one
1105  * may be bad.
1106  * The goal of this function is to repair the errored block by using the
1107  * contents of one of the mirrors.
1108  */
1109 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
1110 {
1111         struct scrub_ctx *sctx = sblock_to_check->sctx;
1112         struct btrfs_device *dev;
1113         struct btrfs_fs_info *fs_info;
1114         u64 length;
1115         u64 logical;
1116         unsigned int failed_mirror_index;
1117         unsigned int is_metadata;
1118         unsigned int have_csum;
1119         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
1120         struct scrub_block *sblock_bad;
1121         int ret;
1122         int mirror_index;
1123         int page_num;
1124         int success;
1125         bool full_stripe_locked;
1126         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
1127                                       DEFAULT_RATELIMIT_BURST);
1128
1129         BUG_ON(sblock_to_check->page_count < 1);
1130         fs_info = sctx->fs_info;
1131         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
1132                 /*
1133                  * if we find an error in a super block, we just report it.
1134                  * They will get written with the next transaction commit
1135                  * anyway
1136                  */
1137                 spin_lock(&sctx->stat_lock);
1138                 ++sctx->stat.super_errors;
1139                 spin_unlock(&sctx->stat_lock);
1140                 return 0;
1141         }
1142         length = sblock_to_check->page_count * PAGE_SIZE;
1143         logical = sblock_to_check->pagev[0]->logical;
1144         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
1145         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
1146         is_metadata = !(sblock_to_check->pagev[0]->flags &
1147                         BTRFS_EXTENT_FLAG_DATA);
1148         have_csum = sblock_to_check->pagev[0]->have_csum;
1149         dev = sblock_to_check->pagev[0]->dev;
1150
1151         /*
1152          * For RAID5/6, race can happen for a different device scrub thread.
1153          * For data corruption, Parity and Data threads will both try
1154          * to recovery the data.
1155          * Race can lead to doubly added csum error, or even unrecoverable
1156          * error.
1157          */
1158         ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
1159         if (ret < 0) {
1160                 spin_lock(&sctx->stat_lock);
1161                 if (ret == -ENOMEM)
1162                         sctx->stat.malloc_errors++;
1163                 sctx->stat.read_errors++;
1164                 sctx->stat.uncorrectable_errors++;
1165                 spin_unlock(&sctx->stat_lock);
1166                 return ret;
1167         }
1168
1169         /*
1170          * read all mirrors one after the other. This includes to
1171          * re-read the extent or metadata block that failed (that was
1172          * the cause that this fixup code is called) another time,
1173          * page by page this time in order to know which pages
1174          * caused I/O errors and which ones are good (for all mirrors).
1175          * It is the goal to handle the situation when more than one
1176          * mirror contains I/O errors, but the errors do not
1177          * overlap, i.e. the data can be repaired by selecting the
1178          * pages from those mirrors without I/O error on the
1179          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
1180          * would be that mirror #1 has an I/O error on the first page,
1181          * the second page is good, and mirror #2 has an I/O error on
1182          * the second page, but the first page is good.
1183          * Then the first page of the first mirror can be repaired by
1184          * taking the first page of the second mirror, and the
1185          * second page of the second mirror can be repaired by
1186          * copying the contents of the 2nd page of the 1st mirror.
1187          * One more note: if the pages of one mirror contain I/O
1188          * errors, the checksum cannot be verified. In order to get
1189          * the best data for repairing, the first attempt is to find
1190          * a mirror without I/O errors and with a validated checksum.
1191          * Only if this is not possible, the pages are picked from
1192          * mirrors with I/O errors without considering the checksum.
1193          * If the latter is the case, at the end, the checksum of the
1194          * repaired area is verified in order to correctly maintain
1195          * the statistics.
1196          */
1197
1198         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
1199                                       sizeof(*sblocks_for_recheck), GFP_NOFS);
1200         if (!sblocks_for_recheck) {
1201                 spin_lock(&sctx->stat_lock);
1202                 sctx->stat.malloc_errors++;
1203                 sctx->stat.read_errors++;
1204                 sctx->stat.uncorrectable_errors++;
1205                 spin_unlock(&sctx->stat_lock);
1206                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
1207                 goto out;
1208         }
1209
1210         /* setup the context, map the logical blocks and alloc the pages */
1211         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
1212         if (ret) {
1213                 spin_lock(&sctx->stat_lock);
1214                 sctx->stat.read_errors++;
1215                 sctx->stat.uncorrectable_errors++;
1216                 spin_unlock(&sctx->stat_lock);
1217                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
1218                 goto out;
1219         }
1220         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
1221         sblock_bad = sblocks_for_recheck + failed_mirror_index;
1222
1223         /* build and submit the bios for the failed mirror, check checksums */
1224         scrub_recheck_block(fs_info, sblock_bad, 1);
1225
1226         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
1227             sblock_bad->no_io_error_seen) {
1228                 /*
1229                  * the error disappeared after reading page by page, or
1230                  * the area was part of a huge bio and other parts of the
1231                  * bio caused I/O errors, or the block layer merged several
1232                  * read requests into one and the error is caused by a
1233                  * different bio (usually one of the two latter cases is
1234                  * the cause)
1235                  */
1236                 spin_lock(&sctx->stat_lock);
1237                 sctx->stat.unverified_errors++;
1238                 sblock_to_check->data_corrected = 1;
1239                 spin_unlock(&sctx->stat_lock);
1240
1241                 if (sctx->is_dev_replace)
1242                         scrub_write_block_to_dev_replace(sblock_bad);
1243                 goto out;
1244         }
1245
1246         if (!sblock_bad->no_io_error_seen) {
1247                 spin_lock(&sctx->stat_lock);
1248                 sctx->stat.read_errors++;
1249                 spin_unlock(&sctx->stat_lock);
1250                 if (__ratelimit(&_rs))
1251                         scrub_print_warning("i/o error", sblock_to_check);
1252                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
1253         } else if (sblock_bad->checksum_error) {
1254                 spin_lock(&sctx->stat_lock);
1255                 sctx->stat.csum_errors++;
1256                 spin_unlock(&sctx->stat_lock);
1257                 if (__ratelimit(&_rs))
1258                         scrub_print_warning("checksum error", sblock_to_check);
1259                 btrfs_dev_stat_inc_and_print(dev,
1260                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
1261         } else if (sblock_bad->header_error) {
1262                 spin_lock(&sctx->stat_lock);
1263                 sctx->stat.verify_errors++;
1264                 spin_unlock(&sctx->stat_lock);
1265                 if (__ratelimit(&_rs))
1266                         scrub_print_warning("checksum/header error",
1267                                             sblock_to_check);
1268                 if (sblock_bad->generation_error)
1269                         btrfs_dev_stat_inc_and_print(dev,
1270                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1271                 else
1272                         btrfs_dev_stat_inc_and_print(dev,
1273                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1274         }
1275
1276         if (sctx->readonly) {
1277                 ASSERT(!sctx->is_dev_replace);
1278                 goto out;
1279         }
1280
1281         /*
1282          * NOTE: Even for nodatasum case, it's still possible that it's a
1283          * compressed data extent, thus scrub_fixup_nodatasum(), which write
1284          * inode page cache onto disk, could cause serious data corruption.
1285          *
1286          * So here we could only read from disk, and hope our recovery could
1287          * reach disk before the newer write.
1288          */
1289         if (0 && !is_metadata && !have_csum) {
1290                 struct scrub_fixup_nodatasum *fixup_nodatasum;
1291
1292                 WARN_ON(sctx->is_dev_replace);
1293
1294                 /*
1295                  * !is_metadata and !have_csum, this means that the data
1296                  * might not be COWed, that it might be modified
1297                  * concurrently. The general strategy to work on the
1298                  * commit root does not help in the case when COW is not
1299                  * used.
1300                  */
1301                 fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum), GFP_NOFS);
1302                 if (!fixup_nodatasum)
1303                         goto did_not_correct_error;
1304                 fixup_nodatasum->sctx = sctx;
1305                 fixup_nodatasum->dev = dev;
1306                 fixup_nodatasum->logical = logical;
1307                 fixup_nodatasum->root = fs_info->extent_root;
1308                 fixup_nodatasum->mirror_num = failed_mirror_index + 1;
1309                 scrub_pending_trans_workers_inc(sctx);
1310                 btrfs_init_work(&fixup_nodatasum->work, btrfs_scrub_helper,
1311                                 scrub_fixup_nodatasum, NULL, NULL);
1312                 btrfs_queue_work(fs_info->scrub_workers,
1313                                  &fixup_nodatasum->work);
1314                 goto out;
1315         }
1316
1317         /*
1318          * now build and submit the bios for the other mirrors, check
1319          * checksums.
1320          * First try to pick the mirror which is completely without I/O
1321          * errors and also does not have a checksum error.
1322          * If one is found, and if a checksum is present, the full block
1323          * that is known to contain an error is rewritten. Afterwards
1324          * the block is known to be corrected.
1325          * If a mirror is found which is completely correct, and no
1326          * checksum is present, only those pages are rewritten that had
1327          * an I/O error in the block to be repaired, since it cannot be
1328          * determined, which copy of the other pages is better (and it
1329          * could happen otherwise that a correct page would be
1330          * overwritten by a bad one).
1331          */
1332         for (mirror_index = 0; ;mirror_index++) {
1333                 struct scrub_block *sblock_other;
1334
1335                 if (mirror_index == failed_mirror_index)
1336                         continue;
1337
1338                 /* raid56's mirror can be more than BTRFS_MAX_MIRRORS */
1339                 if (!scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1340                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1341                                 break;
1342                         if (!sblocks_for_recheck[mirror_index].page_count)
1343                                 break;
1344
1345                         sblock_other = sblocks_for_recheck + mirror_index;
1346                 } else {
1347                         struct scrub_recover *r = sblock_bad->pagev[0]->recover;
1348                         int max_allowed = r->bbio->num_stripes -
1349                                                 r->bbio->num_tgtdevs;
1350
1351                         if (mirror_index >= max_allowed)
1352                                 break;
1353                         if (!sblocks_for_recheck[1].page_count)
1354                                 break;
1355
1356                         ASSERT(failed_mirror_index == 0);
1357                         sblock_other = sblocks_for_recheck + 1;
1358                         sblock_other->pagev[0]->mirror_num = 1 + mirror_index;
1359                 }
1360
1361                 /* build and submit the bios, check checksums */
1362                 scrub_recheck_block(fs_info, sblock_other, 0);
1363
1364                 if (!sblock_other->header_error &&
1365                     !sblock_other->checksum_error &&
1366                     sblock_other->no_io_error_seen) {
1367                         if (sctx->is_dev_replace) {
1368                                 scrub_write_block_to_dev_replace(sblock_other);
1369                                 goto corrected_error;
1370                         } else {
1371                                 ret = scrub_repair_block_from_good_copy(
1372                                                 sblock_bad, sblock_other);
1373                                 if (!ret)
1374                                         goto corrected_error;
1375                         }
1376                 }
1377         }
1378
1379         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1380                 goto did_not_correct_error;
1381
1382         /*
1383          * In case of I/O errors in the area that is supposed to be
1384          * repaired, continue by picking good copies of those pages.
1385          * Select the good pages from mirrors to rewrite bad pages from
1386          * the area to fix. Afterwards verify the checksum of the block
1387          * that is supposed to be repaired. This verification step is
1388          * only done for the purpose of statistic counting and for the
1389          * final scrub report, whether errors remain.
1390          * A perfect algorithm could make use of the checksum and try
1391          * all possible combinations of pages from the different mirrors
1392          * until the checksum verification succeeds. For example, when
1393          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1394          * of mirror #2 is readable but the final checksum test fails,
1395          * then the 2nd page of mirror #3 could be tried, whether now
1396          * the final checksum succeeds. But this would be a rare
1397          * exception and is therefore not implemented. At least it is
1398          * avoided that the good copy is overwritten.
1399          * A more useful improvement would be to pick the sectors
1400          * without I/O error based on sector sizes (512 bytes on legacy
1401          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1402          * mirror could be repaired by taking 512 byte of a different
1403          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1404          * area are unreadable.
1405          */
1406         success = 1;
1407         for (page_num = 0; page_num < sblock_bad->page_count;
1408              page_num++) {
1409                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1410                 struct scrub_block *sblock_other = NULL;
1411
1412                 /* skip no-io-error page in scrub */
1413                 if (!page_bad->io_error && !sctx->is_dev_replace)
1414                         continue;
1415
1416                 /* try to find no-io-error page in mirrors */
1417                 if (page_bad->io_error) {
1418                         for (mirror_index = 0;
1419                              mirror_index < BTRFS_MAX_MIRRORS &&
1420                              sblocks_for_recheck[mirror_index].page_count > 0;
1421                              mirror_index++) {
1422                                 if (!sblocks_for_recheck[mirror_index].
1423                                     pagev[page_num]->io_error) {
1424                                         sblock_other = sblocks_for_recheck +
1425                                                        mirror_index;
1426                                         break;
1427                                 }
1428                         }
1429                         if (!sblock_other)
1430                                 success = 0;
1431                 }
1432
1433                 if (sctx->is_dev_replace) {
1434                         /*
1435                          * did not find a mirror to fetch the page
1436                          * from. scrub_write_page_to_dev_replace()
1437                          * handles this case (page->io_error), by
1438                          * filling the block with zeros before
1439                          * submitting the write request
1440                          */
1441                         if (!sblock_other)
1442                                 sblock_other = sblock_bad;
1443
1444                         if (scrub_write_page_to_dev_replace(sblock_other,
1445                                                             page_num) != 0) {
1446                                 btrfs_dev_replace_stats_inc(
1447                                         &fs_info->dev_replace.num_write_errors);
1448                                 success = 0;
1449                         }
1450                 } else if (sblock_other) {
1451                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1452                                                                sblock_other,
1453                                                                page_num, 0);
1454                         if (0 == ret)
1455                                 page_bad->io_error = 0;
1456                         else
1457                                 success = 0;
1458                 }
1459         }
1460
1461         if (success && !sctx->is_dev_replace) {
1462                 if (is_metadata || have_csum) {
1463                         /*
1464                          * need to verify the checksum now that all
1465                          * sectors on disk are repaired (the write
1466                          * request for data to be repaired is on its way).
1467                          * Just be lazy and use scrub_recheck_block()
1468                          * which re-reads the data before the checksum
1469                          * is verified, but most likely the data comes out
1470                          * of the page cache.
1471                          */
1472                         scrub_recheck_block(fs_info, sblock_bad, 1);
1473                         if (!sblock_bad->header_error &&
1474                             !sblock_bad->checksum_error &&
1475                             sblock_bad->no_io_error_seen)
1476                                 goto corrected_error;
1477                         else
1478                                 goto did_not_correct_error;
1479                 } else {
1480 corrected_error:
1481                         spin_lock(&sctx->stat_lock);
1482                         sctx->stat.corrected_errors++;
1483                         sblock_to_check->data_corrected = 1;
1484                         spin_unlock(&sctx->stat_lock);
1485                         btrfs_err_rl_in_rcu(fs_info,
1486                                 "fixed up error at logical %llu on dev %s",
1487                                 logical, rcu_str_deref(dev->name));
1488                 }
1489         } else {
1490 did_not_correct_error:
1491                 spin_lock(&sctx->stat_lock);
1492                 sctx->stat.uncorrectable_errors++;
1493                 spin_unlock(&sctx->stat_lock);
1494                 btrfs_err_rl_in_rcu(fs_info,
1495                         "unable to fixup (regular) error at logical %llu on dev %s",
1496                         logical, rcu_str_deref(dev->name));
1497         }
1498
1499 out:
1500         if (sblocks_for_recheck) {
1501                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1502                      mirror_index++) {
1503                         struct scrub_block *sblock = sblocks_for_recheck +
1504                                                      mirror_index;
1505                         struct scrub_recover *recover;
1506                         int page_index;
1507
1508                         for (page_index = 0; page_index < sblock->page_count;
1509                              page_index++) {
1510                                 sblock->pagev[page_index]->sblock = NULL;
1511                                 recover = sblock->pagev[page_index]->recover;
1512                                 if (recover) {
1513                                         scrub_put_recover(fs_info, recover);
1514                                         sblock->pagev[page_index]->recover =
1515                                                                         NULL;
1516                                 }
1517                                 scrub_page_put(sblock->pagev[page_index]);
1518                         }
1519                 }
1520                 kfree(sblocks_for_recheck);
1521         }
1522
1523         ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
1524         if (ret < 0)
1525                 return ret;
1526         return 0;
1527 }
1528
1529 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1530 {
1531         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1532                 return 2;
1533         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1534                 return 3;
1535         else
1536                 return (int)bbio->num_stripes;
1537 }
1538
1539 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1540                                                  u64 *raid_map,
1541                                                  u64 mapped_length,
1542                                                  int nstripes, int mirror,
1543                                                  int *stripe_index,
1544                                                  u64 *stripe_offset)
1545 {
1546         int i;
1547
1548         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1549                 /* RAID5/6 */
1550                 for (i = 0; i < nstripes; i++) {
1551                         if (raid_map[i] == RAID6_Q_STRIPE ||
1552                             raid_map[i] == RAID5_P_STRIPE)
1553                                 continue;
1554
1555                         if (logical >= raid_map[i] &&
1556                             logical < raid_map[i] + mapped_length)
1557                                 break;
1558                 }
1559
1560                 *stripe_index = i;
1561                 *stripe_offset = logical - raid_map[i];
1562         } else {
1563                 /* The other RAID type */
1564                 *stripe_index = mirror;
1565                 *stripe_offset = 0;
1566         }
1567 }
1568
1569 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1570                                      struct scrub_block *sblocks_for_recheck)
1571 {
1572         struct scrub_ctx *sctx = original_sblock->sctx;
1573         struct btrfs_fs_info *fs_info = sctx->fs_info;
1574         u64 length = original_sblock->page_count * PAGE_SIZE;
1575         u64 logical = original_sblock->pagev[0]->logical;
1576         u64 generation = original_sblock->pagev[0]->generation;
1577         u64 flags = original_sblock->pagev[0]->flags;
1578         u64 have_csum = original_sblock->pagev[0]->have_csum;
1579         struct scrub_recover *recover;
1580         struct btrfs_bio *bbio;
1581         u64 sublen;
1582         u64 mapped_length;
1583         u64 stripe_offset;
1584         int stripe_index;
1585         int page_index = 0;
1586         int mirror_index;
1587         int nmirrors;
1588         int ret;
1589
1590         /*
1591          * note: the two members refs and outstanding_pages
1592          * are not used (and not set) in the blocks that are used for
1593          * the recheck procedure
1594          */
1595
1596         while (length > 0) {
1597                 sublen = min_t(u64, length, PAGE_SIZE);
1598                 mapped_length = sublen;
1599                 bbio = NULL;
1600
1601                 /*
1602                  * with a length of PAGE_SIZE, each returned stripe
1603                  * represents one mirror
1604                  */
1605                 btrfs_bio_counter_inc_blocked(fs_info);
1606                 ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
1607                                 logical, &mapped_length, &bbio);
1608                 if (ret || !bbio || mapped_length < sublen) {
1609                         btrfs_put_bbio(bbio);
1610                         btrfs_bio_counter_dec(fs_info);
1611                         return -EIO;
1612                 }
1613
1614                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1615                 if (!recover) {
1616                         btrfs_put_bbio(bbio);
1617                         btrfs_bio_counter_dec(fs_info);
1618                         return -ENOMEM;
1619                 }
1620
1621                 refcount_set(&recover->refs, 1);
1622                 recover->bbio = bbio;
1623                 recover->map_length = mapped_length;
1624
1625                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1626
1627                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1628
1629                 for (mirror_index = 0; mirror_index < nmirrors;
1630                      mirror_index++) {
1631                         struct scrub_block *sblock;
1632                         struct scrub_page *page;
1633
1634                         sblock = sblocks_for_recheck + mirror_index;
1635                         sblock->sctx = sctx;
1636
1637                         page = kzalloc(sizeof(*page), GFP_NOFS);
1638                         if (!page) {
1639 leave_nomem:
1640                                 spin_lock(&sctx->stat_lock);
1641                                 sctx->stat.malloc_errors++;
1642                                 spin_unlock(&sctx->stat_lock);
1643                                 scrub_put_recover(fs_info, recover);
1644                                 return -ENOMEM;
1645                         }
1646                         scrub_page_get(page);
1647                         sblock->pagev[page_index] = page;
1648                         page->sblock = sblock;
1649                         page->flags = flags;
1650                         page->generation = generation;
1651                         page->logical = logical;
1652                         page->have_csum = have_csum;
1653                         if (have_csum)
1654                                 memcpy(page->csum,
1655                                        original_sblock->pagev[0]->csum,
1656                                        sctx->csum_size);
1657
1658                         scrub_stripe_index_and_offset(logical,
1659                                                       bbio->map_type,
1660                                                       bbio->raid_map,
1661                                                       mapped_length,
1662                                                       bbio->num_stripes -
1663                                                       bbio->num_tgtdevs,
1664                                                       mirror_index,
1665                                                       &stripe_index,
1666                                                       &stripe_offset);
1667                         page->physical = bbio->stripes[stripe_index].physical +
1668                                          stripe_offset;
1669                         page->dev = bbio->stripes[stripe_index].dev;
1670
1671                         BUG_ON(page_index >= original_sblock->page_count);
1672                         page->physical_for_dev_replace =
1673                                 original_sblock->pagev[page_index]->
1674                                 physical_for_dev_replace;
1675                         /* for missing devices, dev->bdev is NULL */
1676                         page->mirror_num = mirror_index + 1;
1677                         sblock->page_count++;
1678                         page->page = alloc_page(GFP_NOFS);
1679                         if (!page->page)
1680                                 goto leave_nomem;
1681
1682                         scrub_get_recover(recover);
1683                         page->recover = recover;
1684                 }
1685                 scrub_put_recover(fs_info, recover);
1686                 length -= sublen;
1687                 logical += sublen;
1688                 page_index++;
1689         }
1690
1691         return 0;
1692 }
1693
1694 struct scrub_bio_ret {
1695         struct completion event;
1696         blk_status_t status;
1697 };
1698
1699 static void scrub_bio_wait_endio(struct bio *bio)
1700 {
1701         struct scrub_bio_ret *ret = bio->bi_private;
1702
1703         ret->status = bio->bi_status;
1704         complete(&ret->event);
1705 }
1706
1707 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1708                                         struct bio *bio,
1709                                         struct scrub_page *page)
1710 {
1711         struct scrub_bio_ret done;
1712         int ret;
1713         int mirror_num;
1714
1715         init_completion(&done.event);
1716         done.status = 0;
1717         bio->bi_iter.bi_sector = page->logical >> 9;
1718         bio->bi_private = &done;
1719         bio->bi_end_io = scrub_bio_wait_endio;
1720
1721         mirror_num = page->sblock->pagev[0]->mirror_num;
1722         ret = raid56_parity_recover(fs_info, bio, page->recover->bbio,
1723                                     page->recover->map_length,
1724                                     mirror_num, 0);
1725         if (ret)
1726                 return ret;
1727
1728         wait_for_completion_io(&done.event);
1729         if (done.status)
1730                 return -EIO;
1731
1732         return 0;
1733 }
1734
1735 /*
1736  * this function will check the on disk data for checksum errors, header
1737  * errors and read I/O errors. If any I/O errors happen, the exact pages
1738  * which are errored are marked as being bad. The goal is to enable scrub
1739  * to take those pages that are not errored from all the mirrors so that
1740  * the pages that are errored in the just handled mirror can be repaired.
1741  */
1742 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1743                                 struct scrub_block *sblock,
1744                                 int retry_failed_mirror)
1745 {
1746         int page_num;
1747
1748         sblock->no_io_error_seen = 1;
1749
1750         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1751                 struct bio *bio;
1752                 struct scrub_page *page = sblock->pagev[page_num];
1753
1754                 if (page->dev->bdev == NULL) {
1755                         page->io_error = 1;
1756                         sblock->no_io_error_seen = 0;
1757                         continue;
1758                 }
1759
1760                 WARN_ON(!page->page);
1761                 bio = btrfs_io_bio_alloc(1);
1762                 bio_set_dev(bio, page->dev->bdev);
1763
1764                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1765                 if (!retry_failed_mirror && scrub_is_page_on_raid56(page)) {
1766                         if (scrub_submit_raid56_bio_wait(fs_info, bio, page)) {
1767                                 page->io_error = 1;
1768                                 sblock->no_io_error_seen = 0;
1769                         }
1770                 } else {
1771                         bio->bi_iter.bi_sector = page->physical >> 9;
1772                         bio_set_op_attrs(bio, REQ_OP_READ, 0);
1773
1774                         if (btrfsic_submit_bio_wait(bio)) {
1775                                 page->io_error = 1;
1776                                 sblock->no_io_error_seen = 0;
1777                         }
1778                 }
1779
1780                 bio_put(bio);
1781         }
1782
1783         if (sblock->no_io_error_seen)
1784                 scrub_recheck_block_checksum(sblock);
1785 }
1786
1787 static inline int scrub_check_fsid(u8 fsid[],
1788                                    struct scrub_page *spage)
1789 {
1790         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1791         int ret;
1792
1793         ret = memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1794         return !ret;
1795 }
1796
1797 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1798 {
1799         sblock->header_error = 0;
1800         sblock->checksum_error = 0;
1801         sblock->generation_error = 0;
1802
1803         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1804                 scrub_checksum_data(sblock);
1805         else
1806                 scrub_checksum_tree_block(sblock);
1807 }
1808
1809 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1810                                              struct scrub_block *sblock_good)
1811 {
1812         int page_num;
1813         int ret = 0;
1814
1815         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1816                 int ret_sub;
1817
1818                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1819                                                            sblock_good,
1820                                                            page_num, 1);
1821                 if (ret_sub)
1822                         ret = ret_sub;
1823         }
1824
1825         return ret;
1826 }
1827
1828 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1829                                             struct scrub_block *sblock_good,
1830                                             int page_num, int force_write)
1831 {
1832         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1833         struct scrub_page *page_good = sblock_good->pagev[page_num];
1834         struct btrfs_fs_info *fs_info = sblock_bad->sctx->fs_info;
1835
1836         BUG_ON(page_bad->page == NULL);
1837         BUG_ON(page_good->page == NULL);
1838         if (force_write || sblock_bad->header_error ||
1839             sblock_bad->checksum_error || page_bad->io_error) {
1840                 struct bio *bio;
1841                 int ret;
1842
1843                 if (!page_bad->dev->bdev) {
1844                         btrfs_warn_rl(fs_info,
1845                                 "scrub_repair_page_from_good_copy(bdev == NULL) is unexpected");
1846                         return -EIO;
1847                 }
1848
1849                 bio = btrfs_io_bio_alloc(1);
1850                 bio_set_dev(bio, page_bad->dev->bdev);
1851                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1852                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
1853
1854                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1855                 if (PAGE_SIZE != ret) {
1856                         bio_put(bio);
1857                         return -EIO;
1858                 }
1859
1860                 if (btrfsic_submit_bio_wait(bio)) {
1861                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1862                                 BTRFS_DEV_STAT_WRITE_ERRS);
1863                         btrfs_dev_replace_stats_inc(
1864                                 &fs_info->dev_replace.num_write_errors);
1865                         bio_put(bio);
1866                         return -EIO;
1867                 }
1868                 bio_put(bio);
1869         }
1870
1871         return 0;
1872 }
1873
1874 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1875 {
1876         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
1877         int page_num;
1878
1879         /*
1880          * This block is used for the check of the parity on the source device,
1881          * so the data needn't be written into the destination device.
1882          */
1883         if (sblock->sparity)
1884                 return;
1885
1886         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1887                 int ret;
1888
1889                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1890                 if (ret)
1891                         btrfs_dev_replace_stats_inc(
1892                                 &fs_info->dev_replace.num_write_errors);
1893         }
1894 }
1895
1896 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1897                                            int page_num)
1898 {
1899         struct scrub_page *spage = sblock->pagev[page_num];
1900
1901         BUG_ON(spage->page == NULL);
1902         if (spage->io_error) {
1903                 void *mapped_buffer = kmap_atomic(spage->page);
1904
1905                 clear_page(mapped_buffer);
1906                 flush_dcache_page(spage->page);
1907                 kunmap_atomic(mapped_buffer);
1908         }
1909         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1910 }
1911
1912 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1913                                     struct scrub_page *spage)
1914 {
1915         struct scrub_bio *sbio;
1916         int ret;
1917
1918         mutex_lock(&sctx->wr_lock);
1919 again:
1920         if (!sctx->wr_curr_bio) {
1921                 sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
1922                                               GFP_KERNEL);
1923                 if (!sctx->wr_curr_bio) {
1924                         mutex_unlock(&sctx->wr_lock);
1925                         return -ENOMEM;
1926                 }
1927                 sctx->wr_curr_bio->sctx = sctx;
1928                 sctx->wr_curr_bio->page_count = 0;
1929         }
1930         sbio = sctx->wr_curr_bio;
1931         if (sbio->page_count == 0) {
1932                 struct bio *bio;
1933
1934                 sbio->physical = spage->physical_for_dev_replace;
1935                 sbio->logical = spage->logical;
1936                 sbio->dev = sctx->wr_tgtdev;
1937                 bio = sbio->bio;
1938                 if (!bio) {
1939                         bio = btrfs_io_bio_alloc(sctx->pages_per_wr_bio);
1940                         sbio->bio = bio;
1941                 }
1942
1943                 bio->bi_private = sbio;
1944                 bio->bi_end_io = scrub_wr_bio_end_io;
1945                 bio_set_dev(bio, sbio->dev->bdev);
1946                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1947                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
1948                 sbio->status = 0;
1949         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1950                    spage->physical_for_dev_replace ||
1951                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1952                    spage->logical) {
1953                 scrub_wr_submit(sctx);
1954                 goto again;
1955         }
1956
1957         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1958         if (ret != PAGE_SIZE) {
1959                 if (sbio->page_count < 1) {
1960                         bio_put(sbio->bio);
1961                         sbio->bio = NULL;
1962                         mutex_unlock(&sctx->wr_lock);
1963                         return -EIO;
1964                 }
1965                 scrub_wr_submit(sctx);
1966                 goto again;
1967         }
1968
1969         sbio->pagev[sbio->page_count] = spage;
1970         scrub_page_get(spage);
1971         sbio->page_count++;
1972         if (sbio->page_count == sctx->pages_per_wr_bio)
1973                 scrub_wr_submit(sctx);
1974         mutex_unlock(&sctx->wr_lock);
1975
1976         return 0;
1977 }
1978
1979 static void scrub_wr_submit(struct scrub_ctx *sctx)
1980 {
1981         struct scrub_bio *sbio;
1982
1983         if (!sctx->wr_curr_bio)
1984                 return;
1985
1986         sbio = sctx->wr_curr_bio;
1987         sctx->wr_curr_bio = NULL;
1988         WARN_ON(!sbio->bio->bi_disk);
1989         scrub_pending_bio_inc(sctx);
1990         /* process all writes in a single worker thread. Then the block layer
1991          * orders the requests before sending them to the driver which
1992          * doubled the write performance on spinning disks when measured
1993          * with Linux 3.5 */
1994         btrfsic_submit_bio(sbio->bio);
1995 }
1996
1997 static void scrub_wr_bio_end_io(struct bio *bio)
1998 {
1999         struct scrub_bio *sbio = bio->bi_private;
2000         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
2001
2002         sbio->status = bio->bi_status;
2003         sbio->bio = bio;
2004
2005         btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
2006                          scrub_wr_bio_end_io_worker, NULL, NULL);
2007         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
2008 }
2009
2010 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
2011 {
2012         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2013         struct scrub_ctx *sctx = sbio->sctx;
2014         int i;
2015
2016         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
2017         if (sbio->status) {
2018                 struct btrfs_dev_replace *dev_replace =
2019                         &sbio->sctx->fs_info->dev_replace;
2020
2021                 for (i = 0; i < sbio->page_count; i++) {
2022                         struct scrub_page *spage = sbio->pagev[i];
2023
2024                         spage->io_error = 1;
2025                         btrfs_dev_replace_stats_inc(&dev_replace->
2026                                                     num_write_errors);
2027                 }
2028         }
2029
2030         for (i = 0; i < sbio->page_count; i++)
2031                 scrub_page_put(sbio->pagev[i]);
2032
2033         bio_put(sbio->bio);
2034         kfree(sbio);
2035         scrub_pending_bio_dec(sctx);
2036 }
2037
2038 static int scrub_checksum(struct scrub_block *sblock)
2039 {
2040         u64 flags;
2041         int ret;
2042
2043         /*
2044          * No need to initialize these stats currently,
2045          * because this function only use return value
2046          * instead of these stats value.
2047          *
2048          * Todo:
2049          * always use stats
2050          */
2051         sblock->header_error = 0;
2052         sblock->generation_error = 0;
2053         sblock->checksum_error = 0;
2054
2055         WARN_ON(sblock->page_count < 1);
2056         flags = sblock->pagev[0]->flags;
2057         ret = 0;
2058         if (flags & BTRFS_EXTENT_FLAG_DATA)
2059                 ret = scrub_checksum_data(sblock);
2060         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
2061                 ret = scrub_checksum_tree_block(sblock);
2062         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
2063                 (void)scrub_checksum_super(sblock);
2064         else
2065                 WARN_ON(1);
2066         if (ret)
2067                 scrub_handle_errored_block(sblock);
2068
2069         return ret;
2070 }
2071
2072 static int scrub_checksum_data(struct scrub_block *sblock)
2073 {
2074         struct scrub_ctx *sctx = sblock->sctx;
2075         u8 csum[BTRFS_CSUM_SIZE];
2076         u8 *on_disk_csum;
2077         struct page *page;
2078         void *buffer;
2079         u32 crc = ~(u32)0;
2080         u64 len;
2081         int index;
2082
2083         BUG_ON(sblock->page_count < 1);
2084         if (!sblock->pagev[0]->have_csum)
2085                 return 0;
2086
2087         on_disk_csum = sblock->pagev[0]->csum;
2088         page = sblock->pagev[0]->page;
2089         buffer = kmap_atomic(page);
2090
2091         len = sctx->fs_info->sectorsize;
2092         index = 0;
2093         for (;;) {
2094                 u64 l = min_t(u64, len, PAGE_SIZE);
2095
2096                 crc = btrfs_csum_data(buffer, crc, l);
2097                 kunmap_atomic(buffer);
2098                 len -= l;
2099                 if (len == 0)
2100                         break;
2101                 index++;
2102                 BUG_ON(index >= sblock->page_count);
2103                 BUG_ON(!sblock->pagev[index]->page);
2104                 page = sblock->pagev[index]->page;
2105                 buffer = kmap_atomic(page);
2106         }
2107
2108         btrfs_csum_final(crc, csum);
2109         if (memcmp(csum, on_disk_csum, sctx->csum_size))
2110                 sblock->checksum_error = 1;
2111
2112         return sblock->checksum_error;
2113 }
2114
2115 static int scrub_checksum_tree_block(struct scrub_block *sblock)
2116 {
2117         struct scrub_ctx *sctx = sblock->sctx;
2118         struct btrfs_header *h;
2119         struct btrfs_fs_info *fs_info = sctx->fs_info;
2120         u8 calculated_csum[BTRFS_CSUM_SIZE];
2121         u8 on_disk_csum[BTRFS_CSUM_SIZE];
2122         struct page *page;
2123         void *mapped_buffer;
2124         u64 mapped_size;
2125         void *p;
2126         u32 crc = ~(u32)0;
2127         u64 len;
2128         int index;
2129
2130         BUG_ON(sblock->page_count < 1);
2131         page = sblock->pagev[0]->page;
2132         mapped_buffer = kmap_atomic(page);
2133         h = (struct btrfs_header *)mapped_buffer;
2134         memcpy(on_disk_csum, h->csum, sctx->csum_size);
2135
2136         /*
2137          * we don't use the getter functions here, as we
2138          * a) don't have an extent buffer and
2139          * b) the page is already kmapped
2140          */
2141         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
2142                 sblock->header_error = 1;
2143
2144         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
2145                 sblock->header_error = 1;
2146                 sblock->generation_error = 1;
2147         }
2148
2149         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
2150                 sblock->header_error = 1;
2151
2152         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
2153                    BTRFS_UUID_SIZE))
2154                 sblock->header_error = 1;
2155
2156         len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
2157         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
2158         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
2159         index = 0;
2160         for (;;) {
2161                 u64 l = min_t(u64, len, mapped_size);
2162
2163                 crc = btrfs_csum_data(p, crc, l);
2164                 kunmap_atomic(mapped_buffer);
2165                 len -= l;
2166                 if (len == 0)
2167                         break;
2168                 index++;
2169                 BUG_ON(index >= sblock->page_count);
2170                 BUG_ON(!sblock->pagev[index]->page);
2171                 page = sblock->pagev[index]->page;
2172                 mapped_buffer = kmap_atomic(page);
2173                 mapped_size = PAGE_SIZE;
2174                 p = mapped_buffer;
2175         }
2176
2177         btrfs_csum_final(crc, calculated_csum);
2178         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
2179                 sblock->checksum_error = 1;
2180
2181         return sblock->header_error || sblock->checksum_error;
2182 }
2183
2184 static int scrub_checksum_super(struct scrub_block *sblock)
2185 {
2186         struct btrfs_super_block *s;
2187         struct scrub_ctx *sctx = sblock->sctx;
2188         u8 calculated_csum[BTRFS_CSUM_SIZE];
2189         u8 on_disk_csum[BTRFS_CSUM_SIZE];
2190         struct page *page;
2191         void *mapped_buffer;
2192         u64 mapped_size;
2193         void *p;
2194         u32 crc = ~(u32)0;
2195         int fail_gen = 0;
2196         int fail_cor = 0;
2197         u64 len;
2198         int index;
2199
2200         BUG_ON(sblock->page_count < 1);
2201         page = sblock->pagev[0]->page;
2202         mapped_buffer = kmap_atomic(page);
2203         s = (struct btrfs_super_block *)mapped_buffer;
2204         memcpy(on_disk_csum, s->csum, sctx->csum_size);
2205
2206         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
2207                 ++fail_cor;
2208
2209         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
2210                 ++fail_gen;
2211
2212         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
2213                 ++fail_cor;
2214
2215         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
2216         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
2217         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
2218         index = 0;
2219         for (;;) {
2220                 u64 l = min_t(u64, len, mapped_size);
2221
2222                 crc = btrfs_csum_data(p, crc, l);
2223                 kunmap_atomic(mapped_buffer);
2224                 len -= l;
2225                 if (len == 0)
2226                         break;
2227                 index++;
2228                 BUG_ON(index >= sblock->page_count);
2229                 BUG_ON(!sblock->pagev[index]->page);
2230                 page = sblock->pagev[index]->page;
2231                 mapped_buffer = kmap_atomic(page);
2232                 mapped_size = PAGE_SIZE;
2233                 p = mapped_buffer;
2234         }
2235
2236         btrfs_csum_final(crc, calculated_csum);
2237         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
2238                 ++fail_cor;
2239
2240         if (fail_cor + fail_gen) {
2241                 /*
2242                  * if we find an error in a super block, we just report it.
2243                  * They will get written with the next transaction commit
2244                  * anyway
2245                  */
2246                 spin_lock(&sctx->stat_lock);
2247                 ++sctx->stat.super_errors;
2248                 spin_unlock(&sctx->stat_lock);
2249                 if (fail_cor)
2250                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
2251                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
2252                 else
2253                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
2254                                 BTRFS_DEV_STAT_GENERATION_ERRS);
2255         }
2256
2257         return fail_cor + fail_gen;
2258 }
2259
2260 static void scrub_block_get(struct scrub_block *sblock)
2261 {
2262         refcount_inc(&sblock->refs);
2263 }
2264
2265 static void scrub_block_put(struct scrub_block *sblock)
2266 {
2267         if (refcount_dec_and_test(&sblock->refs)) {
2268                 int i;
2269
2270                 if (sblock->sparity)
2271                         scrub_parity_put(sblock->sparity);
2272
2273                 for (i = 0; i < sblock->page_count; i++)
2274                         scrub_page_put(sblock->pagev[i]);
2275                 kfree(sblock);
2276         }
2277 }
2278
2279 static void scrub_page_get(struct scrub_page *spage)
2280 {
2281         atomic_inc(&spage->refs);
2282 }
2283
2284 static void scrub_page_put(struct scrub_page *spage)
2285 {
2286         if (atomic_dec_and_test(&spage->refs)) {
2287                 if (spage->page)
2288                         __free_page(spage->page);
2289                 kfree(spage);
2290         }
2291 }
2292
2293 static void scrub_submit(struct scrub_ctx *sctx)
2294 {
2295         struct scrub_bio *sbio;
2296
2297         if (sctx->curr == -1)
2298                 return;
2299
2300         sbio = sctx->bios[sctx->curr];
2301         sctx->curr = -1;
2302         scrub_pending_bio_inc(sctx);
2303         btrfsic_submit_bio(sbio->bio);
2304 }
2305
2306 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2307                                     struct scrub_page *spage)
2308 {
2309         struct scrub_block *sblock = spage->sblock;
2310         struct scrub_bio *sbio;
2311         int ret;
2312
2313 again:
2314         /*
2315          * grab a fresh bio or wait for one to become available
2316          */
2317         while (sctx->curr == -1) {
2318                 spin_lock(&sctx->list_lock);
2319                 sctx->curr = sctx->first_free;
2320                 if (sctx->curr != -1) {
2321                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2322                         sctx->bios[sctx->curr]->next_free = -1;
2323                         sctx->bios[sctx->curr]->page_count = 0;
2324                         spin_unlock(&sctx->list_lock);
2325                 } else {
2326                         spin_unlock(&sctx->list_lock);
2327                         wait_event(sctx->list_wait, sctx->first_free != -1);
2328                 }
2329         }
2330         sbio = sctx->bios[sctx->curr];
2331         if (sbio->page_count == 0) {
2332                 struct bio *bio;
2333
2334                 sbio->physical = spage->physical;
2335                 sbio->logical = spage->logical;
2336                 sbio->dev = spage->dev;
2337                 bio = sbio->bio;
2338                 if (!bio) {
2339                         bio = btrfs_io_bio_alloc(sctx->pages_per_rd_bio);
2340                         sbio->bio = bio;
2341                 }
2342
2343                 bio->bi_private = sbio;
2344                 bio->bi_end_io = scrub_bio_end_io;
2345                 bio_set_dev(bio, sbio->dev->bdev);
2346                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2347                 bio_set_op_attrs(bio, REQ_OP_READ, 0);
2348                 sbio->status = 0;
2349         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2350                    spage->physical ||
2351                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2352                    spage->logical ||
2353                    sbio->dev != spage->dev) {
2354                 scrub_submit(sctx);
2355                 goto again;
2356         }
2357
2358         sbio->pagev[sbio->page_count] = spage;
2359         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2360         if (ret != PAGE_SIZE) {
2361                 if (sbio->page_count < 1) {
2362                         bio_put(sbio->bio);
2363                         sbio->bio = NULL;
2364                         return -EIO;
2365                 }
2366                 scrub_submit(sctx);
2367                 goto again;
2368         }
2369
2370         scrub_block_get(sblock); /* one for the page added to the bio */
2371         atomic_inc(&sblock->outstanding_pages);
2372         sbio->page_count++;
2373         if (sbio->page_count == sctx->pages_per_rd_bio)
2374                 scrub_submit(sctx);
2375
2376         return 0;
2377 }
2378
2379 static void scrub_missing_raid56_end_io(struct bio *bio)
2380 {
2381         struct scrub_block *sblock = bio->bi_private;
2382         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
2383
2384         if (bio->bi_status)
2385                 sblock->no_io_error_seen = 0;
2386
2387         bio_put(bio);
2388
2389         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2390 }
2391
2392 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2393 {
2394         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2395         struct scrub_ctx *sctx = sblock->sctx;
2396         struct btrfs_fs_info *fs_info = sctx->fs_info;
2397         u64 logical;
2398         struct btrfs_device *dev;
2399
2400         logical = sblock->pagev[0]->logical;
2401         dev = sblock->pagev[0]->dev;
2402
2403         if (sblock->no_io_error_seen)
2404                 scrub_recheck_block_checksum(sblock);
2405
2406         if (!sblock->no_io_error_seen) {
2407                 spin_lock(&sctx->stat_lock);
2408                 sctx->stat.read_errors++;
2409                 spin_unlock(&sctx->stat_lock);
2410                 btrfs_err_rl_in_rcu(fs_info,
2411                         "IO error rebuilding logical %llu for dev %s",
2412                         logical, rcu_str_deref(dev->name));
2413         } else if (sblock->header_error || sblock->checksum_error) {
2414                 spin_lock(&sctx->stat_lock);
2415                 sctx->stat.uncorrectable_errors++;
2416                 spin_unlock(&sctx->stat_lock);
2417                 btrfs_err_rl_in_rcu(fs_info,
2418                         "failed to rebuild valid logical %llu for dev %s",
2419                         logical, rcu_str_deref(dev->name));
2420         } else {
2421                 scrub_write_block_to_dev_replace(sblock);
2422         }
2423
2424         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2425                 mutex_lock(&sctx->wr_lock);
2426                 scrub_wr_submit(sctx);
2427                 mutex_unlock(&sctx->wr_lock);
2428         }
2429
2430         scrub_block_put(sblock);
2431         scrub_pending_bio_dec(sctx);
2432 }
2433
2434 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2435 {
2436         struct scrub_ctx *sctx = sblock->sctx;
2437         struct btrfs_fs_info *fs_info = sctx->fs_info;
2438         u64 length = sblock->page_count * PAGE_SIZE;
2439         u64 logical = sblock->pagev[0]->logical;
2440         struct btrfs_bio *bbio = NULL;
2441         struct bio *bio;
2442         struct btrfs_raid_bio *rbio;
2443         int ret;
2444         int i;
2445
2446         btrfs_bio_counter_inc_blocked(fs_info);
2447         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
2448                         &length, &bbio);
2449         if (ret || !bbio || !bbio->raid_map)
2450                 goto bbio_out;
2451
2452         if (WARN_ON(!sctx->is_dev_replace ||
2453                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2454                 /*
2455                  * We shouldn't be scrubbing a missing device. Even for dev
2456                  * replace, we should only get here for RAID 5/6. We either
2457                  * managed to mount something with no mirrors remaining or
2458                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2459                  */
2460                 goto bbio_out;
2461         }
2462
2463         bio = btrfs_io_bio_alloc(0);
2464         bio->bi_iter.bi_sector = logical >> 9;
2465         bio->bi_private = sblock;
2466         bio->bi_end_io = scrub_missing_raid56_end_io;
2467
2468         rbio = raid56_alloc_missing_rbio(fs_info, bio, bbio, length);
2469         if (!rbio)
2470                 goto rbio_out;
2471
2472         for (i = 0; i < sblock->page_count; i++) {
2473                 struct scrub_page *spage = sblock->pagev[i];
2474
2475                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2476         }
2477
2478         btrfs_init_work(&sblock->work, btrfs_scrub_helper,
2479                         scrub_missing_raid56_worker, NULL, NULL);
2480         scrub_block_get(sblock);
2481         scrub_pending_bio_inc(sctx);
2482         raid56_submit_missing_rbio(rbio);
2483         return;
2484
2485 rbio_out:
2486         bio_put(bio);
2487 bbio_out:
2488         btrfs_bio_counter_dec(fs_info);
2489         btrfs_put_bbio(bbio);
2490         spin_lock(&sctx->stat_lock);
2491         sctx->stat.malloc_errors++;
2492         spin_unlock(&sctx->stat_lock);
2493 }
2494
2495 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2496                        u64 physical, struct btrfs_device *dev, u64 flags,
2497                        u64 gen, int mirror_num, u8 *csum, int force,
2498                        u64 physical_for_dev_replace)
2499 {
2500         struct scrub_block *sblock;
2501         int index;
2502
2503         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2504         if (!sblock) {
2505                 spin_lock(&sctx->stat_lock);
2506                 sctx->stat.malloc_errors++;
2507                 spin_unlock(&sctx->stat_lock);
2508                 return -ENOMEM;
2509         }
2510
2511         /* one ref inside this function, plus one for each page added to
2512          * a bio later on */
2513         refcount_set(&sblock->refs, 1);
2514         sblock->sctx = sctx;
2515         sblock->no_io_error_seen = 1;
2516
2517         for (index = 0; len > 0; index++) {
2518                 struct scrub_page *spage;
2519                 u64 l = min_t(u64, len, PAGE_SIZE);
2520
2521                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2522                 if (!spage) {
2523 leave_nomem:
2524                         spin_lock(&sctx->stat_lock);
2525                         sctx->stat.malloc_errors++;
2526                         spin_unlock(&sctx->stat_lock);
2527                         scrub_block_put(sblock);
2528                         return -ENOMEM;
2529                 }
2530                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2531                 scrub_page_get(spage);
2532                 sblock->pagev[index] = spage;
2533                 spage->sblock = sblock;
2534                 spage->dev = dev;
2535                 spage->flags = flags;
2536                 spage->generation = gen;
2537                 spage->logical = logical;
2538                 spage->physical = physical;
2539                 spage->physical_for_dev_replace = physical_for_dev_replace;
2540                 spage->mirror_num = mirror_num;
2541                 if (csum) {
2542                         spage->have_csum = 1;
2543                         memcpy(spage->csum, csum, sctx->csum_size);
2544                 } else {
2545                         spage->have_csum = 0;
2546                 }
2547                 sblock->page_count++;
2548                 spage->page = alloc_page(GFP_KERNEL);
2549                 if (!spage->page)
2550                         goto leave_nomem;
2551                 len -= l;
2552                 logical += l;
2553                 physical += l;
2554                 physical_for_dev_replace += l;
2555         }
2556
2557         WARN_ON(sblock->page_count == 0);
2558         if (dev->missing) {
2559                 /*
2560                  * This case should only be hit for RAID 5/6 device replace. See
2561                  * the comment in scrub_missing_raid56_pages() for details.
2562                  */
2563                 scrub_missing_raid56_pages(sblock);
2564         } else {
2565                 for (index = 0; index < sblock->page_count; index++) {
2566                         struct scrub_page *spage = sblock->pagev[index];
2567                         int ret;
2568
2569                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2570                         if (ret) {
2571                                 scrub_block_put(sblock);
2572                                 return ret;
2573                         }
2574                 }
2575
2576                 if (force)
2577                         scrub_submit(sctx);
2578         }
2579
2580         /* last one frees, either here or in bio completion for last page */
2581         scrub_block_put(sblock);
2582         return 0;
2583 }
2584
2585 static void scrub_bio_end_io(struct bio *bio)
2586 {
2587         struct scrub_bio *sbio = bio->bi_private;
2588         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
2589
2590         sbio->status = bio->bi_status;
2591         sbio->bio = bio;
2592
2593         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2594 }
2595
2596 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2597 {
2598         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2599         struct scrub_ctx *sctx = sbio->sctx;
2600         int i;
2601
2602         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2603         if (sbio->status) {
2604                 for (i = 0; i < sbio->page_count; i++) {
2605                         struct scrub_page *spage = sbio->pagev[i];
2606
2607                         spage->io_error = 1;
2608                         spage->sblock->no_io_error_seen = 0;
2609                 }
2610         }
2611
2612         /* now complete the scrub_block items that have all pages completed */
2613         for (i = 0; i < sbio->page_count; i++) {
2614                 struct scrub_page *spage = sbio->pagev[i];
2615                 struct scrub_block *sblock = spage->sblock;
2616
2617                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2618                         scrub_block_complete(sblock);
2619                 scrub_block_put(sblock);
2620         }
2621
2622         bio_put(sbio->bio);
2623         sbio->bio = NULL;
2624         spin_lock(&sctx->list_lock);
2625         sbio->next_free = sctx->first_free;
2626         sctx->first_free = sbio->index;
2627         spin_unlock(&sctx->list_lock);
2628
2629         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2630                 mutex_lock(&sctx->wr_lock);
2631                 scrub_wr_submit(sctx);
2632                 mutex_unlock(&sctx->wr_lock);
2633         }
2634
2635         scrub_pending_bio_dec(sctx);
2636 }
2637
2638 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2639                                        unsigned long *bitmap,
2640                                        u64 start, u64 len)
2641 {
2642         u64 offset;
2643         u64 nsectors64;
2644         u32 nsectors;
2645         int sectorsize = sparity->sctx->fs_info->sectorsize;
2646
2647         if (len >= sparity->stripe_len) {
2648                 bitmap_set(bitmap, 0, sparity->nsectors);
2649                 return;
2650         }
2651
2652         start -= sparity->logic_start;
2653         start = div64_u64_rem(start, sparity->stripe_len, &offset);
2654         offset = div_u64(offset, sectorsize);
2655         nsectors64 = div_u64(len, sectorsize);
2656
2657         ASSERT(nsectors64 < UINT_MAX);
2658         nsectors = (u32)nsectors64;
2659
2660         if (offset + nsectors <= sparity->nsectors) {
2661                 bitmap_set(bitmap, offset, nsectors);
2662                 return;
2663         }
2664
2665         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2666         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2667 }
2668
2669 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2670                                                    u64 start, u64 len)
2671 {
2672         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2673 }
2674
2675 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2676                                                   u64 start, u64 len)
2677 {
2678         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2679 }
2680
2681 static void scrub_block_complete(struct scrub_block *sblock)
2682 {
2683         int corrupted = 0;
2684
2685         if (!sblock->no_io_error_seen) {
2686                 corrupted = 1;
2687                 scrub_handle_errored_block(sblock);
2688         } else {
2689                 /*
2690                  * if has checksum error, write via repair mechanism in
2691                  * dev replace case, otherwise write here in dev replace
2692                  * case.
2693                  */
2694                 corrupted = scrub_checksum(sblock);
2695                 if (!corrupted && sblock->sctx->is_dev_replace)
2696                         scrub_write_block_to_dev_replace(sblock);
2697         }
2698
2699         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2700                 u64 start = sblock->pagev[0]->logical;
2701                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2702                           PAGE_SIZE;
2703
2704                 scrub_parity_mark_sectors_error(sblock->sparity,
2705                                                 start, end - start);
2706         }
2707 }
2708
2709 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2710 {
2711         struct btrfs_ordered_sum *sum = NULL;
2712         unsigned long index;
2713         unsigned long num_sectors;
2714
2715         while (!list_empty(&sctx->csum_list)) {
2716                 sum = list_first_entry(&sctx->csum_list,
2717                                        struct btrfs_ordered_sum, list);
2718                 if (sum->bytenr > logical)
2719                         return 0;
2720                 if (sum->bytenr + sum->len > logical)
2721                         break;
2722
2723                 ++sctx->stat.csum_discards;
2724                 list_del(&sum->list);
2725                 kfree(sum);
2726                 sum = NULL;
2727         }
2728         if (!sum)
2729                 return 0;
2730
2731         index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize);
2732         ASSERT(index < UINT_MAX);
2733
2734         num_sectors = sum->len / sctx->fs_info->sectorsize;
2735         memcpy(csum, sum->sums + index, sctx->csum_size);
2736         if (index == num_sectors - 1) {
2737                 list_del(&sum->list);
2738                 kfree(sum);
2739         }
2740         return 1;
2741 }
2742
2743 /* scrub extent tries to collect up to 64 kB for each bio */
2744 static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
2745                         u64 physical, struct btrfs_device *dev, u64 flags,
2746                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2747 {
2748         int ret;
2749         u8 csum[BTRFS_CSUM_SIZE];
2750         u32 blocksize;
2751
2752         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2753                 blocksize = sctx->fs_info->sectorsize;
2754                 spin_lock(&sctx->stat_lock);
2755                 sctx->stat.data_extents_scrubbed++;
2756                 sctx->stat.data_bytes_scrubbed += len;
2757                 spin_unlock(&sctx->stat_lock);
2758         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2759                 blocksize = sctx->fs_info->nodesize;
2760                 spin_lock(&sctx->stat_lock);
2761                 sctx->stat.tree_extents_scrubbed++;
2762                 sctx->stat.tree_bytes_scrubbed += len;
2763                 spin_unlock(&sctx->stat_lock);
2764         } else {
2765                 blocksize = sctx->fs_info->sectorsize;
2766                 WARN_ON(1);
2767         }
2768
2769         while (len) {
2770                 u64 l = min_t(u64, len, blocksize);
2771                 int have_csum = 0;
2772
2773                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2774                         /* push csums to sbio */
2775                         have_csum = scrub_find_csum(sctx, logical, csum);
2776                         if (have_csum == 0)
2777                                 ++sctx->stat.no_csum;
2778                         if (0 && sctx->is_dev_replace && !have_csum) {
2779                                 ret = copy_nocow_pages(sctx, logical, l,
2780                                                        mirror_num,
2781                                                       physical_for_dev_replace);
2782                                 goto behind_scrub_pages;
2783                         }
2784                 }
2785                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2786                                   mirror_num, have_csum ? csum : NULL, 0,
2787                                   physical_for_dev_replace);
2788 behind_scrub_pages:
2789                 if (ret)
2790                         return ret;
2791                 len -= l;
2792                 logical += l;
2793                 physical += l;
2794                 physical_for_dev_replace += l;
2795         }
2796         return 0;
2797 }
2798
2799 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2800                                   u64 logical, u64 len,
2801                                   u64 physical, struct btrfs_device *dev,
2802                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2803 {
2804         struct scrub_ctx *sctx = sparity->sctx;
2805         struct scrub_block *sblock;
2806         int index;
2807
2808         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2809         if (!sblock) {
2810                 spin_lock(&sctx->stat_lock);
2811                 sctx->stat.malloc_errors++;
2812                 spin_unlock(&sctx->stat_lock);
2813                 return -ENOMEM;
2814         }
2815
2816         /* one ref inside this function, plus one for each page added to
2817          * a bio later on */
2818         refcount_set(&sblock->refs, 1);
2819         sblock->sctx = sctx;
2820         sblock->no_io_error_seen = 1;
2821         sblock->sparity = sparity;
2822         scrub_parity_get(sparity);
2823
2824         for (index = 0; len > 0; index++) {
2825                 struct scrub_page *spage;
2826                 u64 l = min_t(u64, len, PAGE_SIZE);
2827
2828                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2829                 if (!spage) {
2830 leave_nomem:
2831                         spin_lock(&sctx->stat_lock);
2832                         sctx->stat.malloc_errors++;
2833                         spin_unlock(&sctx->stat_lock);
2834                         scrub_block_put(sblock);
2835                         return -ENOMEM;
2836                 }
2837                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2838                 /* For scrub block */
2839                 scrub_page_get(spage);
2840                 sblock->pagev[index] = spage;
2841                 /* For scrub parity */
2842                 scrub_page_get(spage);
2843                 list_add_tail(&spage->list, &sparity->spages);
2844                 spage->sblock = sblock;
2845                 spage->dev = dev;
2846                 spage->flags = flags;
2847                 spage->generation = gen;
2848                 spage->logical = logical;
2849                 spage->physical = physical;
2850                 spage->mirror_num = mirror_num;
2851                 if (csum) {
2852                         spage->have_csum = 1;
2853                         memcpy(spage->csum, csum, sctx->csum_size);
2854                 } else {
2855                         spage->have_csum = 0;
2856                 }
2857                 sblock->page_count++;
2858                 spage->page = alloc_page(GFP_KERNEL);
2859                 if (!spage->page)
2860                         goto leave_nomem;
2861                 len -= l;
2862                 logical += l;
2863                 physical += l;
2864         }
2865
2866         WARN_ON(sblock->page_count == 0);
2867         for (index = 0; index < sblock->page_count; index++) {
2868                 struct scrub_page *spage = sblock->pagev[index];
2869                 int ret;
2870
2871                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2872                 if (ret) {
2873                         scrub_block_put(sblock);
2874                         return ret;
2875                 }
2876         }
2877
2878         /* last one frees, either here or in bio completion for last page */
2879         scrub_block_put(sblock);
2880         return 0;
2881 }
2882
2883 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2884                                    u64 logical, u64 len,
2885                                    u64 physical, struct btrfs_device *dev,
2886                                    u64 flags, u64 gen, int mirror_num)
2887 {
2888         struct scrub_ctx *sctx = sparity->sctx;
2889         int ret;
2890         u8 csum[BTRFS_CSUM_SIZE];
2891         u32 blocksize;
2892
2893         if (dev->missing) {
2894                 scrub_parity_mark_sectors_error(sparity, logical, len);
2895                 return 0;
2896         }
2897
2898         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2899                 blocksize = sctx->fs_info->sectorsize;
2900         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2901                 blocksize = sctx->fs_info->nodesize;
2902         } else {
2903                 blocksize = sctx->fs_info->sectorsize;
2904                 WARN_ON(1);
2905         }
2906
2907         while (len) {
2908                 u64 l = min_t(u64, len, blocksize);
2909                 int have_csum = 0;
2910
2911                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2912                         /* push csums to sbio */
2913                         have_csum = scrub_find_csum(sctx, logical, csum);
2914                         if (have_csum == 0)
2915                                 goto skip;
2916                 }
2917                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2918                                              flags, gen, mirror_num,
2919                                              have_csum ? csum : NULL);
2920                 if (ret)
2921                         return ret;
2922 skip:
2923                 len -= l;
2924                 logical += l;
2925                 physical += l;
2926         }
2927         return 0;
2928 }
2929
2930 /*
2931  * Given a physical address, this will calculate it's
2932  * logical offset. if this is a parity stripe, it will return
2933  * the most left data stripe's logical offset.
2934  *
2935  * return 0 if it is a data stripe, 1 means parity stripe.
2936  */
2937 static int get_raid56_logic_offset(u64 physical, int num,
2938                                    struct map_lookup *map, u64 *offset,
2939                                    u64 *stripe_start)
2940 {
2941         int i;
2942         int j = 0;
2943         u64 stripe_nr;
2944         u64 last_offset;
2945         u32 stripe_index;
2946         u32 rot;
2947
2948         last_offset = (physical - map->stripes[num].physical) *
2949                       nr_data_stripes(map);
2950         if (stripe_start)
2951                 *stripe_start = last_offset;
2952
2953         *offset = last_offset;
2954         for (i = 0; i < nr_data_stripes(map); i++) {
2955                 *offset = last_offset + i * map->stripe_len;
2956
2957                 stripe_nr = div64_u64(*offset, map->stripe_len);
2958                 stripe_nr = div_u64(stripe_nr, nr_data_stripes(map));
2959
2960                 /* Work out the disk rotation on this stripe-set */
2961                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2962                 /* calculate which stripe this data locates */
2963                 rot += i;
2964                 stripe_index = rot % map->num_stripes;
2965                 if (stripe_index == num)
2966                         return 0;
2967                 if (stripe_index < num)
2968                         j++;
2969         }
2970         *offset = last_offset + j * map->stripe_len;
2971         return 1;
2972 }
2973
2974 static void scrub_free_parity(struct scrub_parity *sparity)
2975 {
2976         struct scrub_ctx *sctx = sparity->sctx;
2977         struct scrub_page *curr, *next;
2978         int nbits;
2979
2980         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2981         if (nbits) {
2982                 spin_lock(&sctx->stat_lock);
2983                 sctx->stat.read_errors += nbits;
2984                 sctx->stat.uncorrectable_errors += nbits;
2985                 spin_unlock(&sctx->stat_lock);
2986         }
2987
2988         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2989                 list_del_init(&curr->list);
2990                 scrub_page_put(curr);
2991         }
2992
2993         kfree(sparity);
2994 }
2995
2996 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2997 {
2998         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2999                                                     work);
3000         struct scrub_ctx *sctx = sparity->sctx;
3001
3002         scrub_free_parity(sparity);
3003         scrub_pending_bio_dec(sctx);
3004 }
3005
3006 static void scrub_parity_bio_endio(struct bio *bio)
3007 {
3008         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
3009         struct btrfs_fs_info *fs_info = sparity->sctx->fs_info;
3010
3011         if (bio->bi_status)
3012                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
3013                           sparity->nsectors);
3014
3015         bio_put(bio);
3016
3017         btrfs_init_work(&sparity->work, btrfs_scrubparity_helper,
3018                         scrub_parity_bio_endio_worker, NULL, NULL);
3019         btrfs_queue_work(fs_info->scrub_parity_workers, &sparity->work);
3020 }
3021
3022 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
3023 {
3024         struct scrub_ctx *sctx = sparity->sctx;
3025         struct btrfs_fs_info *fs_info = sctx->fs_info;
3026         struct bio *bio;
3027         struct btrfs_raid_bio *rbio;
3028         struct btrfs_bio *bbio = NULL;
3029         u64 length;
3030         int ret;
3031
3032         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
3033                            sparity->nsectors))
3034                 goto out;
3035
3036         length = sparity->logic_end - sparity->logic_start;
3037
3038         btrfs_bio_counter_inc_blocked(fs_info);
3039         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,
3040                                &length, &bbio);
3041         if (ret || !bbio || !bbio->raid_map)
3042                 goto bbio_out;
3043
3044         bio = btrfs_io_bio_alloc(0);
3045         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
3046         bio->bi_private = sparity;
3047         bio->bi_end_io = scrub_parity_bio_endio;
3048
3049         rbio = raid56_parity_alloc_scrub_rbio(fs_info, bio, bbio,
3050                                               length, sparity->scrub_dev,
3051                                               sparity->dbitmap,
3052                                               sparity->nsectors);
3053         if (!rbio)
3054                 goto rbio_out;
3055
3056         scrub_pending_bio_inc(sctx);
3057         raid56_parity_submit_scrub_rbio(rbio);
3058         return;
3059
3060 rbio_out:
3061         bio_put(bio);
3062 bbio_out:
3063         btrfs_bio_counter_dec(fs_info);
3064         btrfs_put_bbio(bbio);
3065         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
3066                   sparity->nsectors);
3067         spin_lock(&sctx->stat_lock);
3068         sctx->stat.malloc_errors++;
3069         spin_unlock(&sctx->stat_lock);
3070 out:
3071         scrub_free_parity(sparity);
3072 }
3073
3074 static inline int scrub_calc_parity_bitmap_len(int nsectors)
3075 {
3076         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
3077 }
3078
3079 static void scrub_parity_get(struct scrub_parity *sparity)
3080 {
3081         refcount_inc(&sparity->refs);
3082 }
3083
3084 static void scrub_parity_put(struct scrub_parity *sparity)
3085 {
3086         if (!refcount_dec_and_test(&sparity->refs))
3087                 return;
3088
3089         scrub_parity_check_and_repair(sparity);
3090 }
3091
3092 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
3093                                                   struct map_lookup *map,
3094                                                   struct btrfs_device *sdev,
3095                                                   struct btrfs_path *path,
3096                                                   u64 logic_start,
3097                                                   u64 logic_end)
3098 {
3099         struct btrfs_fs_info *fs_info = sctx->fs_info;
3100         struct btrfs_root *root = fs_info->extent_root;
3101         struct btrfs_root *csum_root = fs_info->csum_root;
3102         struct btrfs_extent_item *extent;
3103         struct btrfs_bio *bbio = NULL;
3104         u64 flags;
3105         int ret;
3106         int slot;
3107         struct extent_buffer *l;
3108         struct btrfs_key key;
3109         u64 generation;
3110         u64 extent_logical;
3111         u64 extent_physical;
3112         u64 extent_len;
3113         u64 mapped_length;
3114         struct btrfs_device *extent_dev;
3115         struct scrub_parity *sparity;
3116         int nsectors;
3117         int bitmap_len;
3118         int extent_mirror_num;
3119         int stop_loop = 0;
3120
3121         nsectors = div_u64(map->stripe_len, fs_info->sectorsize);
3122         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
3123         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
3124                           GFP_NOFS);
3125         if (!sparity) {
3126                 spin_lock(&sctx->stat_lock);
3127                 sctx->stat.malloc_errors++;
3128                 spin_unlock(&sctx->stat_lock);
3129                 return -ENOMEM;
3130         }
3131
3132         sparity->stripe_len = map->stripe_len;
3133         sparity->nsectors = nsectors;
3134         sparity->sctx = sctx;
3135         sparity->scrub_dev = sdev;
3136         sparity->logic_start = logic_start;
3137         sparity->logic_end = logic_end;
3138         refcount_set(&sparity->refs, 1);
3139         INIT_LIST_HEAD(&sparity->spages);
3140         sparity->dbitmap = sparity->bitmap;
3141         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
3142
3143         ret = 0;
3144         while (logic_start < logic_end) {
3145                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3146                         key.type = BTRFS_METADATA_ITEM_KEY;
3147                 else
3148                         key.type = BTRFS_EXTENT_ITEM_KEY;
3149                 key.objectid = logic_start;
3150                 key.offset = (u64)-1;
3151
3152                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3153                 if (ret < 0)
3154                         goto out;
3155
3156                 if (ret > 0) {
3157                         ret = btrfs_previous_extent_item(root, path, 0);
3158                         if (ret < 0)
3159                                 goto out;
3160                         if (ret > 0) {
3161                                 btrfs_release_path(path);
3162                                 ret = btrfs_search_slot(NULL, root, &key,
3163                                                         path, 0, 0);
3164                                 if (ret < 0)
3165                                         goto out;
3166                         }
3167                 }
3168
3169                 stop_loop = 0;
3170                 while (1) {
3171                         u64 bytes;
3172
3173                         l = path->nodes[0];
3174                         slot = path->slots[0];
3175                         if (slot >= btrfs_header_nritems(l)) {
3176                                 ret = btrfs_next_leaf(root, path);
3177                                 if (ret == 0)
3178                                         continue;
3179                                 if (ret < 0)
3180                                         goto out;
3181
3182                                 stop_loop = 1;
3183                                 break;
3184                         }
3185                         btrfs_item_key_to_cpu(l, &key, slot);
3186
3187                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3188                             key.type != BTRFS_METADATA_ITEM_KEY)
3189                                 goto next;
3190
3191                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3192                                 bytes = fs_info->nodesize;
3193                         else
3194                                 bytes = key.offset;
3195
3196                         if (key.objectid + bytes <= logic_start)
3197                                 goto next;
3198
3199                         if (key.objectid >= logic_end) {
3200                                 stop_loop = 1;
3201                                 break;
3202                         }
3203
3204                         while (key.objectid >= logic_start + map->stripe_len)
3205                                 logic_start += map->stripe_len;
3206
3207                         extent = btrfs_item_ptr(l, slot,
3208                                                 struct btrfs_extent_item);
3209                         flags = btrfs_extent_flags(l, extent);
3210                         generation = btrfs_extent_generation(l, extent);
3211
3212                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3213                             (key.objectid < logic_start ||
3214                              key.objectid + bytes >
3215                              logic_start + map->stripe_len)) {
3216                                 btrfs_err(fs_info,
3217                                           "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
3218                                           key.objectid, logic_start);
3219                                 spin_lock(&sctx->stat_lock);
3220                                 sctx->stat.uncorrectable_errors++;
3221                                 spin_unlock(&sctx->stat_lock);
3222                                 goto next;
3223                         }
3224 again:
3225                         extent_logical = key.objectid;
3226                         extent_len = bytes;
3227
3228                         if (extent_logical < logic_start) {
3229                                 extent_len -= logic_start - extent_logical;
3230                                 extent_logical = logic_start;
3231                         }
3232
3233                         if (extent_logical + extent_len >
3234                             logic_start + map->stripe_len)
3235                                 extent_len = logic_start + map->stripe_len -
3236                                              extent_logical;
3237
3238                         scrub_parity_mark_sectors_data(sparity, extent_logical,
3239                                                        extent_len);
3240
3241                         mapped_length = extent_len;
3242                         bbio = NULL;
3243                         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ,
3244                                         extent_logical, &mapped_length, &bbio,
3245                                         0);
3246                         if (!ret) {
3247                                 if (!bbio || mapped_length < extent_len)
3248                                         ret = -EIO;
3249                         }
3250                         if (ret) {
3251                                 btrfs_put_bbio(bbio);
3252                                 goto out;
3253                         }
3254                         extent_physical = bbio->stripes[0].physical;
3255                         extent_mirror_num = bbio->mirror_num;
3256                         extent_dev = bbio->stripes[0].dev;
3257                         btrfs_put_bbio(bbio);
3258
3259                         ret = btrfs_lookup_csums_range(csum_root,
3260                                                 extent_logical,
3261                                                 extent_logical + extent_len - 1,
3262                                                 &sctx->csum_list, 1);
3263                         if (ret)
3264                                 goto out;
3265
3266                         ret = scrub_extent_for_parity(sparity, extent_logical,
3267                                                       extent_len,
3268                                                       extent_physical,
3269                                                       extent_dev, flags,
3270                                                       generation,
3271                                                       extent_mirror_num);
3272
3273                         scrub_free_csums(sctx);
3274
3275                         if (ret)
3276                                 goto out;
3277
3278                         if (extent_logical + extent_len <
3279                             key.objectid + bytes) {
3280                                 logic_start += map->stripe_len;
3281
3282                                 if (logic_start >= logic_end) {
3283                                         stop_loop = 1;
3284                                         break;
3285                                 }
3286
3287                                 if (logic_start < key.objectid + bytes) {
3288                                         cond_resched();
3289                                         goto again;
3290                                 }
3291                         }
3292 next:
3293                         path->slots[0]++;
3294                 }
3295
3296                 btrfs_release_path(path);
3297
3298                 if (stop_loop)
3299                         break;
3300
3301                 logic_start += map->stripe_len;
3302         }
3303 out:
3304         if (ret < 0)
3305                 scrub_parity_mark_sectors_error(sparity, logic_start,
3306                                                 logic_end - logic_start);
3307         scrub_parity_put(sparity);
3308         scrub_submit(sctx);
3309         mutex_lock(&sctx->wr_lock);
3310         scrub_wr_submit(sctx);
3311         mutex_unlock(&sctx->wr_lock);
3312
3313         btrfs_release_path(path);
3314         return ret < 0 ? ret : 0;
3315 }
3316
3317 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3318                                            struct map_lookup *map,
3319                                            struct btrfs_device *scrub_dev,
3320                                            int num, u64 base, u64 length,
3321                                            int is_dev_replace)
3322 {
3323         struct btrfs_path *path, *ppath;
3324         struct btrfs_fs_info *fs_info = sctx->fs_info;
3325         struct btrfs_root *root = fs_info->extent_root;
3326         struct btrfs_root *csum_root = fs_info->csum_root;
3327         struct btrfs_extent_item *extent;
3328         struct blk_plug plug;
3329         u64 flags;
3330         int ret;
3331         int slot;
3332         u64 nstripes;
3333         struct extent_buffer *l;
3334         u64 physical;
3335         u64 logical;
3336         u64 logic_end;
3337         u64 physical_end;
3338         u64 generation;
3339         int mirror_num;
3340         struct reada_control *reada1;
3341         struct reada_control *reada2;
3342         struct btrfs_key key;
3343         struct btrfs_key key_end;
3344         u64 increment = map->stripe_len;
3345         u64 offset;
3346         u64 extent_logical;
3347         u64 extent_physical;
3348         u64 extent_len;
3349         u64 stripe_logical;
3350         u64 stripe_end;
3351         struct btrfs_device *extent_dev;
3352         int extent_mirror_num;
3353         int stop_loop = 0;
3354
3355         physical = map->stripes[num].physical;
3356         offset = 0;
3357         nstripes = div64_u64(length, map->stripe_len);
3358         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3359                 offset = map->stripe_len * num;
3360                 increment = map->stripe_len * map->num_stripes;
3361                 mirror_num = 1;
3362         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3363                 int factor = map->num_stripes / map->sub_stripes;
3364                 offset = map->stripe_len * (num / map->sub_stripes);
3365                 increment = map->stripe_len * factor;
3366                 mirror_num = num % map->sub_stripes + 1;
3367         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
3368                 increment = map->stripe_len;
3369                 mirror_num = num % map->num_stripes + 1;
3370         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3371                 increment = map->stripe_len;
3372                 mirror_num = num % map->num_stripes + 1;
3373         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3374                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3375                 increment = map->stripe_len * nr_data_stripes(map);
3376                 mirror_num = 1;
3377         } else {
3378                 increment = map->stripe_len;
3379                 mirror_num = 1;
3380         }
3381
3382         path = btrfs_alloc_path();
3383         if (!path)
3384                 return -ENOMEM;
3385
3386         ppath = btrfs_alloc_path();
3387         if (!ppath) {
3388                 btrfs_free_path(path);
3389                 return -ENOMEM;
3390         }
3391
3392         /*
3393          * work on commit root. The related disk blocks are static as
3394          * long as COW is applied. This means, it is save to rewrite
3395          * them to repair disk errors without any race conditions
3396          */
3397         path->search_commit_root = 1;
3398         path->skip_locking = 1;
3399
3400         ppath->search_commit_root = 1;
3401         ppath->skip_locking = 1;
3402         /*
3403          * trigger the readahead for extent tree csum tree and wait for
3404          * completion. During readahead, the scrub is officially paused
3405          * to not hold off transaction commits
3406          */
3407         logical = base + offset;
3408         physical_end = physical + nstripes * map->stripe_len;
3409         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3410                 get_raid56_logic_offset(physical_end, num,
3411                                         map, &logic_end, NULL);
3412                 logic_end += base;
3413         } else {
3414                 logic_end = logical + increment * nstripes;
3415         }
3416         wait_event(sctx->list_wait,
3417                    atomic_read(&sctx->bios_in_flight) == 0);
3418         scrub_blocked_if_needed(fs_info);
3419
3420         /* FIXME it might be better to start readahead at commit root */
3421         key.objectid = logical;
3422         key.type = BTRFS_EXTENT_ITEM_KEY;
3423         key.offset = (u64)0;
3424         key_end.objectid = logic_end;
3425         key_end.type = BTRFS_METADATA_ITEM_KEY;
3426         key_end.offset = (u64)-1;
3427         reada1 = btrfs_reada_add(root, &key, &key_end);
3428
3429         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3430         key.type = BTRFS_EXTENT_CSUM_KEY;
3431         key.offset = logical;
3432         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3433         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3434         key_end.offset = logic_end;
3435         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3436
3437         if (!IS_ERR(reada1))
3438                 btrfs_reada_wait(reada1);
3439         if (!IS_ERR(reada2))
3440                 btrfs_reada_wait(reada2);
3441
3442
3443         /*
3444          * collect all data csums for the stripe to avoid seeking during
3445          * the scrub. This might currently (crc32) end up to be about 1MB
3446          */
3447         blk_start_plug(&plug);
3448
3449         /*
3450          * now find all extents for each stripe and scrub them
3451          */
3452         ret = 0;
3453         while (physical < physical_end) {
3454                 /*
3455                  * canceled?
3456                  */
3457                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3458                     atomic_read(&sctx->cancel_req)) {
3459                         ret = -ECANCELED;
3460                         goto out;
3461                 }
3462                 /*
3463                  * check to see if we have to pause
3464                  */
3465                 if (atomic_read(&fs_info->scrub_pause_req)) {
3466                         /* push queued extents */
3467                         sctx->flush_all_writes = true;
3468                         scrub_submit(sctx);
3469                         mutex_lock(&sctx->wr_lock);
3470                         scrub_wr_submit(sctx);
3471                         mutex_unlock(&sctx->wr_lock);
3472                         wait_event(sctx->list_wait,
3473                                    atomic_read(&sctx->bios_in_flight) == 0);
3474                         sctx->flush_all_writes = false;
3475                         scrub_blocked_if_needed(fs_info);
3476                 }
3477
3478                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3479                         ret = get_raid56_logic_offset(physical, num, map,
3480                                                       &logical,
3481                                                       &stripe_logical);
3482                         logical += base;
3483                         if (ret) {
3484                                 /* it is parity strip */
3485                                 stripe_logical += base;
3486                                 stripe_end = stripe_logical + increment;
3487                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3488                                                           ppath, stripe_logical,
3489                                                           stripe_end);
3490                                 if (ret)
3491                                         goto out;
3492                                 goto skip;
3493                         }
3494                 }
3495
3496                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3497                         key.type = BTRFS_METADATA_ITEM_KEY;
3498                 else
3499                         key.type = BTRFS_EXTENT_ITEM_KEY;
3500                 key.objectid = logical;
3501                 key.offset = (u64)-1;
3502
3503                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3504                 if (ret < 0)
3505                         goto out;
3506
3507                 if (ret > 0) {
3508                         ret = btrfs_previous_extent_item(root, path, 0);
3509                         if (ret < 0)
3510                                 goto out;
3511                         if (ret > 0) {
3512                                 /* there's no smaller item, so stick with the
3513                                  * larger one */
3514                                 btrfs_release_path(path);
3515                                 ret = btrfs_search_slot(NULL, root, &key,
3516                                                         path, 0, 0);
3517                                 if (ret < 0)
3518                                         goto out;
3519                         }
3520                 }
3521
3522                 stop_loop = 0;
3523                 while (1) {
3524                         u64 bytes;
3525
3526                         l = path->nodes[0];
3527                         slot = path->slots[0];
3528                         if (slot >= btrfs_header_nritems(l)) {
3529                                 ret = btrfs_next_leaf(root, path);
3530                                 if (ret == 0)
3531                                         continue;
3532                                 if (ret < 0)
3533                                         goto out;
3534
3535                                 stop_loop = 1;
3536                                 break;
3537                         }
3538                         btrfs_item_key_to_cpu(l, &key, slot);
3539
3540                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3541                             key.type != BTRFS_METADATA_ITEM_KEY)
3542                                 goto next;
3543
3544                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3545                                 bytes = fs_info->nodesize;
3546                         else
3547                                 bytes = key.offset;
3548
3549                         if (key.objectid + bytes <= logical)
3550                                 goto next;
3551
3552                         if (key.objectid >= logical + map->stripe_len) {
3553                                 /* out of this device extent */
3554                                 if (key.objectid >= logic_end)
3555                                         stop_loop = 1;
3556                                 break;
3557                         }
3558
3559                         extent = btrfs_item_ptr(l, slot,
3560                                                 struct btrfs_extent_item);
3561                         flags = btrfs_extent_flags(l, extent);
3562                         generation = btrfs_extent_generation(l, extent);
3563
3564                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3565                             (key.objectid < logical ||
3566                              key.objectid + bytes >
3567                              logical + map->stripe_len)) {
3568                                 btrfs_err(fs_info,
3569                                            "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
3570                                        key.objectid, logical);
3571                                 spin_lock(&sctx->stat_lock);
3572                                 sctx->stat.uncorrectable_errors++;
3573                                 spin_unlock(&sctx->stat_lock);
3574                                 goto next;
3575                         }
3576
3577 again:
3578                         extent_logical = key.objectid;
3579                         extent_len = bytes;
3580
3581                         /*
3582                          * trim extent to this stripe
3583                          */
3584                         if (extent_logical < logical) {
3585                                 extent_len -= logical - extent_logical;
3586                                 extent_logical = logical;
3587                         }
3588                         if (extent_logical + extent_len >
3589                             logical + map->stripe_len) {
3590                                 extent_len = logical + map->stripe_len -
3591                                              extent_logical;
3592                         }
3593
3594                         extent_physical = extent_logical - logical + physical;
3595                         extent_dev = scrub_dev;
3596                         extent_mirror_num = mirror_num;
3597                         if (is_dev_replace)
3598                                 scrub_remap_extent(fs_info, extent_logical,
3599                                                    extent_len, &extent_physical,
3600                                                    &extent_dev,
3601                                                    &extent_mirror_num);
3602
3603                         ret = btrfs_lookup_csums_range(csum_root,
3604                                                        extent_logical,
3605                                                        extent_logical +
3606                                                        extent_len - 1,
3607                                                        &sctx->csum_list, 1);
3608                         if (ret)
3609                                 goto out;
3610
3611                         ret = scrub_extent(sctx, extent_logical, extent_len,
3612                                            extent_physical, extent_dev, flags,
3613                                            generation, extent_mirror_num,
3614                                            extent_logical - logical + physical);
3615
3616                         scrub_free_csums(sctx);
3617
3618                         if (ret)
3619                                 goto out;
3620
3621                         if (extent_logical + extent_len <
3622                             key.objectid + bytes) {
3623                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3624                                         /*
3625                                          * loop until we find next data stripe
3626                                          * or we have finished all stripes.
3627                                          */
3628 loop:
3629                                         physical += map->stripe_len;
3630                                         ret = get_raid56_logic_offset(physical,
3631                                                         num, map, &logical,
3632                                                         &stripe_logical);
3633                                         logical += base;
3634
3635                                         if (ret && physical < physical_end) {
3636                                                 stripe_logical += base;
3637                                                 stripe_end = stripe_logical +
3638                                                                 increment;
3639                                                 ret = scrub_raid56_parity(sctx,
3640                                                         map, scrub_dev, ppath,
3641                                                         stripe_logical,
3642                                                         stripe_end);
3643                                                 if (ret)
3644                                                         goto out;
3645                                                 goto loop;
3646                                         }
3647                                 } else {
3648                                         physical += map->stripe_len;
3649                                         logical += increment;
3650                                 }
3651                                 if (logical < key.objectid + bytes) {
3652                                         cond_resched();
3653                                         goto again;
3654                                 }
3655
3656                                 if (physical >= physical_end) {
3657                                         stop_loop = 1;
3658                                         break;
3659                                 }
3660                         }
3661 next:
3662                         path->slots[0]++;
3663                 }
3664                 btrfs_release_path(path);
3665 skip:
3666                 logical += increment;
3667                 physical += map->stripe_len;
3668                 spin_lock(&sctx->stat_lock);
3669                 if (stop_loop)
3670                         sctx->stat.last_physical = map->stripes[num].physical +
3671                                                    length;
3672                 else
3673                         sctx->stat.last_physical = physical;
3674                 spin_unlock(&sctx->stat_lock);
3675                 if (stop_loop)
3676                         break;
3677         }
3678 out:
3679         /* push queued extents */
3680         scrub_submit(sctx);
3681         mutex_lock(&sctx->wr_lock);
3682         scrub_wr_submit(sctx);
3683         mutex_unlock(&sctx->wr_lock);
3684
3685         blk_finish_plug(&plug);
3686         btrfs_free_path(path);
3687         btrfs_free_path(ppath);
3688         return ret < 0 ? ret : 0;
3689 }
3690
3691 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3692                                           struct btrfs_device *scrub_dev,
3693                                           u64 chunk_offset, u64 length,
3694                                           u64 dev_offset,
3695                                           struct btrfs_block_group_cache *cache,
3696                                           int is_dev_replace)
3697 {
3698         struct btrfs_fs_info *fs_info = sctx->fs_info;
3699         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
3700         struct map_lookup *map;
3701         struct extent_map *em;
3702         int i;
3703         int ret = 0;
3704
3705         read_lock(&map_tree->map_tree.lock);
3706         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
3707         read_unlock(&map_tree->map_tree.lock);
3708
3709         if (!em) {
3710                 /*
3711                  * Might have been an unused block group deleted by the cleaner
3712                  * kthread or relocation.
3713                  */
3714                 spin_lock(&cache->lock);
3715                 if (!cache->removed)
3716                         ret = -EINVAL;
3717                 spin_unlock(&cache->lock);
3718
3719                 return ret;
3720         }
3721
3722         map = em->map_lookup;
3723         if (em->start != chunk_offset)
3724                 goto out;
3725
3726         if (em->len < length)
3727                 goto out;
3728
3729         for (i = 0; i < map->num_stripes; ++i) {
3730                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3731                     map->stripes[i].physical == dev_offset) {
3732                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3733                                            chunk_offset, length,
3734                                            is_dev_replace);
3735                         if (ret)
3736                                 goto out;
3737                 }
3738         }
3739 out:
3740         free_extent_map(em);
3741
3742         return ret;
3743 }
3744
3745 static noinline_for_stack
3746 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3747                            struct btrfs_device *scrub_dev, u64 start, u64 end,
3748                            int is_dev_replace)
3749 {
3750         struct btrfs_dev_extent *dev_extent = NULL;
3751         struct btrfs_path *path;
3752         struct btrfs_fs_info *fs_info = sctx->fs_info;
3753         struct btrfs_root *root = fs_info->dev_root;
3754         u64 length;
3755         u64 chunk_offset;
3756         int ret = 0;
3757         int ro_set;
3758         int slot;
3759         struct extent_buffer *l;
3760         struct btrfs_key key;
3761         struct btrfs_key found_key;
3762         struct btrfs_block_group_cache *cache;
3763         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3764
3765         path = btrfs_alloc_path();
3766         if (!path)
3767                 return -ENOMEM;
3768
3769         path->reada = READA_FORWARD;
3770         path->search_commit_root = 1;
3771         path->skip_locking = 1;
3772
3773         key.objectid = scrub_dev->devid;
3774         key.offset = 0ull;
3775         key.type = BTRFS_DEV_EXTENT_KEY;
3776
3777         while (1) {
3778                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3779                 if (ret < 0)
3780                         break;
3781                 if (ret > 0) {
3782                         if (path->slots[0] >=
3783                             btrfs_header_nritems(path->nodes[0])) {
3784                                 ret = btrfs_next_leaf(root, path);
3785                                 if (ret < 0)
3786                                         break;
3787                                 if (ret > 0) {
3788                                         ret = 0;
3789                                         break;
3790                                 }
3791                         } else {
3792                                 ret = 0;
3793                         }
3794                 }
3795
3796                 l = path->nodes[0];
3797                 slot = path->slots[0];
3798
3799                 btrfs_item_key_to_cpu(l, &found_key, slot);
3800
3801                 if (found_key.objectid != scrub_dev->devid)
3802                         break;
3803
3804                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3805                         break;
3806
3807                 if (found_key.offset >= end)
3808                         break;
3809
3810                 if (found_key.offset < key.offset)
3811                         break;
3812
3813                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3814                 length = btrfs_dev_extent_length(l, dev_extent);
3815
3816                 if (found_key.offset + length <= start)
3817                         goto skip;
3818
3819                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3820
3821                 /*
3822                  * get a reference on the corresponding block group to prevent
3823                  * the chunk from going away while we scrub it
3824                  */
3825                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3826
3827                 /* some chunks are removed but not committed to disk yet,
3828                  * continue scrubbing */
3829                 if (!cache)
3830                         goto skip;
3831
3832                 /*
3833                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3834                  * to avoid deadlock caused by:
3835                  * btrfs_inc_block_group_ro()
3836                  * -> btrfs_wait_for_commit()
3837                  * -> btrfs_commit_transaction()
3838                  * -> btrfs_scrub_pause()
3839                  */
3840                 scrub_pause_on(fs_info);
3841                 ret = btrfs_inc_block_group_ro(fs_info, cache);
3842                 if (!ret && is_dev_replace) {
3843                         /*
3844                          * If we are doing a device replace wait for any tasks
3845                          * that started dellaloc right before we set the block
3846                          * group to RO mode, as they might have just allocated
3847                          * an extent from it or decided they could do a nocow
3848                          * write. And if any such tasks did that, wait for their
3849                          * ordered extents to complete and then commit the
3850                          * current transaction, so that we can later see the new
3851                          * extent items in the extent tree - the ordered extents
3852                          * create delayed data references (for cow writes) when
3853                          * they complete, which will be run and insert the
3854                          * corresponding extent items into the extent tree when
3855                          * we commit the transaction they used when running
3856                          * inode.c:btrfs_finish_ordered_io(). We later use
3857                          * the commit root of the extent tree to find extents
3858                          * to copy from the srcdev into the tgtdev, and we don't
3859                          * want to miss any new extents.
3860                          */
3861                         btrfs_wait_block_group_reservations(cache);
3862                         btrfs_wait_nocow_writers(cache);
3863                         ret = btrfs_wait_ordered_roots(fs_info, U64_MAX,
3864                                                        cache->key.objectid,
3865                                                        cache->key.offset);
3866                         if (ret > 0) {
3867                                 struct btrfs_trans_handle *trans;
3868
3869                                 trans = btrfs_join_transaction(root);
3870                                 if (IS_ERR(trans))
3871                                         ret = PTR_ERR(trans);
3872                                 else
3873                                         ret = btrfs_commit_transaction(trans);
3874                                 if (ret) {
3875                                         scrub_pause_off(fs_info);
3876                                         btrfs_put_block_group(cache);
3877                                         break;
3878                                 }
3879                         }
3880                 }
3881                 scrub_pause_off(fs_info);
3882
3883                 if (ret == 0) {
3884                         ro_set = 1;
3885                 } else if (ret == -ENOSPC) {
3886                         /*
3887                          * btrfs_inc_block_group_ro return -ENOSPC when it
3888                          * failed in creating new chunk for metadata.
3889                          * It is not a problem for scrub/replace, because
3890                          * metadata are always cowed, and our scrub paused
3891                          * commit_transactions.
3892                          */
3893                         ro_set = 0;
3894                 } else {
3895                         btrfs_warn(fs_info,
3896                                    "failed setting block group ro: %d", ret);
3897                         btrfs_put_block_group(cache);
3898                         break;
3899                 }
3900
3901                 btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
3902                 dev_replace->cursor_right = found_key.offset + length;
3903                 dev_replace->cursor_left = found_key.offset;
3904                 dev_replace->item_needs_writeback = 1;
3905                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
3906                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3907                                   found_key.offset, cache, is_dev_replace);
3908
3909                 /*
3910                  * flush, submit all pending read and write bios, afterwards
3911                  * wait for them.
3912                  * Note that in the dev replace case, a read request causes
3913                  * write requests that are submitted in the read completion
3914                  * worker. Therefore in the current situation, it is required
3915                  * that all write requests are flushed, so that all read and
3916                  * write requests are really completed when bios_in_flight
3917                  * changes to 0.
3918                  */
3919                 sctx->flush_all_writes = true;
3920                 scrub_submit(sctx);
3921                 mutex_lock(&sctx->wr_lock);
3922                 scrub_wr_submit(sctx);
3923                 mutex_unlock(&sctx->wr_lock);
3924
3925                 wait_event(sctx->list_wait,
3926                            atomic_read(&sctx->bios_in_flight) == 0);
3927
3928                 scrub_pause_on(fs_info);
3929
3930                 /*
3931                  * must be called before we decrease @scrub_paused.
3932                  * make sure we don't block transaction commit while
3933                  * we are waiting pending workers finished.
3934                  */
3935                 wait_event(sctx->list_wait,
3936                            atomic_read(&sctx->workers_pending) == 0);
3937                 sctx->flush_all_writes = false;
3938
3939                 scrub_pause_off(fs_info);
3940
3941                 btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
3942                 dev_replace->cursor_left = dev_replace->cursor_right;
3943                 dev_replace->item_needs_writeback = 1;
3944                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
3945
3946                 if (ro_set)
3947                         btrfs_dec_block_group_ro(cache);
3948
3949                 /*
3950                  * We might have prevented the cleaner kthread from deleting
3951                  * this block group if it was already unused because we raced
3952                  * and set it to RO mode first. So add it back to the unused
3953                  * list, otherwise it might not ever be deleted unless a manual
3954                  * balance is triggered or it becomes used and unused again.
3955                  */
3956                 spin_lock(&cache->lock);
3957                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3958                     btrfs_block_group_used(&cache->item) == 0) {
3959                         spin_unlock(&cache->lock);
3960                         spin_lock(&fs_info->unused_bgs_lock);
3961                         if (list_empty(&cache->bg_list)) {
3962                                 btrfs_get_block_group(cache);
3963                                 list_add_tail(&cache->bg_list,
3964                                               &fs_info->unused_bgs);
3965                         }
3966                         spin_unlock(&fs_info->unused_bgs_lock);
3967                 } else {
3968                         spin_unlock(&cache->lock);
3969                 }
3970
3971                 btrfs_put_block_group(cache);
3972                 if (ret)
3973                         break;
3974                 if (is_dev_replace &&
3975                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3976                         ret = -EIO;
3977                         break;
3978                 }
3979                 if (sctx->stat.malloc_errors > 0) {
3980                         ret = -ENOMEM;
3981                         break;
3982                 }
3983 skip:
3984                 key.offset = found_key.offset + length;
3985                 btrfs_release_path(path);
3986         }
3987
3988         btrfs_free_path(path);
3989
3990         return ret;
3991 }
3992
3993 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3994                                            struct btrfs_device *scrub_dev)
3995 {
3996         int     i;
3997         u64     bytenr;
3998         u64     gen;
3999         int     ret;
4000         struct btrfs_fs_info *fs_info = sctx->fs_info;
4001
4002         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
4003                 return -EIO;
4004
4005         /* Seed devices of a new filesystem has their own generation. */
4006         if (scrub_dev->fs_devices != fs_info->fs_devices)
4007                 gen = scrub_dev->generation;
4008         else
4009                 gen = fs_info->last_trans_committed;
4010
4011         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
4012                 bytenr = btrfs_sb_offset(i);
4013                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
4014                     scrub_dev->commit_total_bytes)
4015                         break;
4016
4017                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
4018                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
4019                                   NULL, 1, bytenr);
4020                 if (ret)
4021                         return ret;
4022         }
4023         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
4024
4025         return 0;
4026 }
4027
4028 /*
4029  * get a reference count on fs_info->scrub_workers. start worker if necessary
4030  */
4031 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
4032                                                 int is_dev_replace)
4033 {
4034         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
4035         int max_active = fs_info->thread_pool_size;
4036
4037         if (fs_info->scrub_workers_refcnt == 0) {
4038                 fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub",
4039                                 flags, is_dev_replace ? 1 : max_active, 4);
4040                 if (!fs_info->scrub_workers)
4041                         goto fail_scrub_workers;
4042
4043                 fs_info->scrub_wr_completion_workers =
4044                         btrfs_alloc_workqueue(fs_info, "scrubwrc", flags,
4045                                               max_active, 2);
4046                 if (!fs_info->scrub_wr_completion_workers)
4047                         goto fail_scrub_wr_completion_workers;
4048
4049                 fs_info->scrub_nocow_workers =
4050                         btrfs_alloc_workqueue(fs_info, "scrubnc", flags, 1, 0);
4051                 if (!fs_info->scrub_nocow_workers)
4052                         goto fail_scrub_nocow_workers;
4053                 fs_info->scrub_parity_workers =
4054                         btrfs_alloc_workqueue(fs_info, "scrubparity", flags,
4055                                               max_active, 2);
4056                 if (!fs_info->scrub_parity_workers)
4057                         goto fail_scrub_parity_workers;
4058         }
4059         ++fs_info->scrub_workers_refcnt;
4060         return 0;
4061
4062 fail_scrub_parity_workers:
4063         btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
4064 fail_scrub_nocow_workers:
4065         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
4066 fail_scrub_wr_completion_workers:
4067         btrfs_destroy_workqueue(fs_info->scrub_workers);
4068 fail_scrub_workers:
4069         return -ENOMEM;
4070 }
4071
4072 static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
4073 {
4074         if (--fs_info->scrub_workers_refcnt == 0) {
4075                 btrfs_destroy_workqueue(fs_info->scrub_workers);
4076                 btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
4077                 btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
4078                 btrfs_destroy_workqueue(fs_info->scrub_parity_workers);
4079         }
4080         WARN_ON(fs_info->scrub_workers_refcnt < 0);
4081 }
4082
4083 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
4084                     u64 end, struct btrfs_scrub_progress *progress,
4085                     int readonly, int is_dev_replace)
4086 {
4087         struct scrub_ctx *sctx;
4088         int ret;
4089         struct btrfs_device *dev;
4090         struct rcu_string *name;
4091
4092         if (btrfs_fs_closing(fs_info))
4093                 return -EINVAL;
4094
4095         if (fs_info->nodesize > BTRFS_STRIPE_LEN) {
4096                 /*
4097                  * in this case scrub is unable to calculate the checksum
4098                  * the way scrub is implemented. Do not handle this
4099                  * situation at all because it won't ever happen.
4100                  */
4101                 btrfs_err(fs_info,
4102                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
4103                        fs_info->nodesize,
4104                        BTRFS_STRIPE_LEN);
4105                 return -EINVAL;
4106         }
4107
4108         if (fs_info->sectorsize != PAGE_SIZE) {
4109                 /* not supported for data w/o checksums */
4110                 btrfs_err_rl(fs_info,
4111                            "scrub: size assumption sectorsize != PAGE_SIZE (%d != %lu) fails",
4112                        fs_info->sectorsize, PAGE_SIZE);
4113                 return -EINVAL;
4114         }
4115
4116         if (fs_info->nodesize >
4117             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
4118             fs_info->sectorsize > PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
4119                 /*
4120                  * would exhaust the array bounds of pagev member in
4121                  * struct scrub_block
4122                  */
4123                 btrfs_err(fs_info,
4124                           "scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
4125                        fs_info->nodesize,
4126                        SCRUB_MAX_PAGES_PER_BLOCK,
4127                        fs_info->sectorsize,
4128                        SCRUB_MAX_PAGES_PER_BLOCK);
4129                 return -EINVAL;
4130         }
4131
4132
4133         mutex_lock(&fs_info->fs_devices->device_list_mutex);
4134         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
4135         if (!dev || (dev->missing && !is_dev_replace)) {
4136                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4137                 return -ENODEV;
4138         }
4139
4140         if (!is_dev_replace && !readonly && !dev->writeable) {
4141                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4142                 rcu_read_lock();
4143                 name = rcu_dereference(dev->name);
4144                 btrfs_err(fs_info, "scrub: device %s is not writable",
4145                           name->str);
4146                 rcu_read_unlock();
4147                 return -EROFS;
4148         }
4149
4150         mutex_lock(&fs_info->scrub_lock);
4151         if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
4152                 mutex_unlock(&fs_info->scrub_lock);
4153                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4154                 return -EIO;
4155         }
4156
4157         btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
4158         if (dev->scrub_device ||
4159             (!is_dev_replace &&
4160              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
4161                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
4162                 mutex_unlock(&fs_info->scrub_lock);
4163                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4164                 return -EINPROGRESS;
4165         }
4166         btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
4167
4168         ret = scrub_workers_get(fs_info, is_dev_replace);
4169         if (ret) {
4170                 mutex_unlock(&fs_info->scrub_lock);
4171                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4172                 return ret;
4173         }
4174
4175         sctx = scrub_setup_ctx(dev, is_dev_replace);
4176         if (IS_ERR(sctx)) {
4177                 mutex_unlock(&fs_info->scrub_lock);
4178                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4179                 scrub_workers_put(fs_info);
4180                 return PTR_ERR(sctx);
4181         }
4182         sctx->readonly = readonly;
4183         dev->scrub_device = sctx;
4184         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4185
4186         /*
4187          * checking @scrub_pause_req here, we can avoid
4188          * race between committing transaction and scrubbing.
4189          */
4190         __scrub_blocked_if_needed(fs_info);
4191         atomic_inc(&fs_info->scrubs_running);
4192         mutex_unlock(&fs_info->scrub_lock);
4193
4194         if (!is_dev_replace) {
4195                 /*
4196                  * by holding device list mutex, we can
4197                  * kick off writing super in log tree sync.
4198                  */
4199                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
4200                 ret = scrub_supers(sctx, dev);
4201                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4202         }
4203
4204         if (!ret)
4205                 ret = scrub_enumerate_chunks(sctx, dev, start, end,
4206                                              is_dev_replace);
4207
4208         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
4209         atomic_dec(&fs_info->scrubs_running);
4210         wake_up(&fs_info->scrub_pause_wait);
4211
4212         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
4213
4214         if (progress)
4215                 memcpy(progress, &sctx->stat, sizeof(*progress));
4216
4217         mutex_lock(&fs_info->scrub_lock);
4218         dev->scrub_device = NULL;
4219         scrub_workers_put(fs_info);
4220         mutex_unlock(&fs_info->scrub_lock);
4221
4222         scrub_put_ctx(sctx);
4223
4224         return ret;
4225 }
4226
4227 void btrfs_scrub_pause(struct btrfs_fs_info *fs_info)
4228 {
4229         mutex_lock(&fs_info->scrub_lock);
4230         atomic_inc(&fs_info->scrub_pause_req);
4231         while (atomic_read(&fs_info->scrubs_paused) !=
4232                atomic_read(&fs_info->scrubs_running)) {
4233                 mutex_unlock(&fs_info->scrub_lock);
4234                 wait_event(fs_info->scrub_pause_wait,
4235                            atomic_read(&fs_info->scrubs_paused) ==
4236                            atomic_read(&fs_info->scrubs_running));
4237                 mutex_lock(&fs_info->scrub_lock);
4238         }
4239         mutex_unlock(&fs_info->scrub_lock);
4240 }
4241
4242 void btrfs_scrub_continue(struct btrfs_fs_info *fs_info)
4243 {
4244         atomic_dec(&fs_info->scrub_pause_req);
4245         wake_up(&fs_info->scrub_pause_wait);
4246 }
4247
4248 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
4249 {
4250         mutex_lock(&fs_info->scrub_lock);
4251         if (!atomic_read(&fs_info->scrubs_running)) {
4252                 mutex_unlock(&fs_info->scrub_lock);
4253                 return -ENOTCONN;
4254         }
4255
4256         atomic_inc(&fs_info->scrub_cancel_req);
4257         while (atomic_read(&fs_info->scrubs_running)) {
4258                 mutex_unlock(&fs_info->scrub_lock);
4259                 wait_event(fs_info->scrub_pause_wait,
4260                            atomic_read(&fs_info->scrubs_running) == 0);
4261                 mutex_lock(&fs_info->scrub_lock);
4262         }
4263         atomic_dec(&fs_info->scrub_cancel_req);
4264         mutex_unlock(&fs_info->scrub_lock);
4265
4266         return 0;
4267 }
4268
4269 int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
4270                            struct btrfs_device *dev)
4271 {
4272         struct scrub_ctx *sctx;
4273
4274         mutex_lock(&fs_info->scrub_lock);
4275         sctx = dev->scrub_device;
4276         if (!sctx) {
4277                 mutex_unlock(&fs_info->scrub_lock);
4278                 return -ENOTCONN;
4279         }
4280         atomic_inc(&sctx->cancel_req);
4281         while (dev->scrub_device) {
4282                 mutex_unlock(&fs_info->scrub_lock);
4283                 wait_event(fs_info->scrub_pause_wait,
4284                            dev->scrub_device == NULL);
4285                 mutex_lock(&fs_info->scrub_lock);
4286         }
4287         mutex_unlock(&fs_info->scrub_lock);
4288
4289         return 0;
4290 }
4291
4292 int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
4293                          struct btrfs_scrub_progress *progress)
4294 {
4295         struct btrfs_device *dev;
4296         struct scrub_ctx *sctx = NULL;
4297
4298         mutex_lock(&fs_info->fs_devices->device_list_mutex);
4299         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
4300         if (dev)
4301                 sctx = dev->scrub_device;
4302         if (sctx)
4303                 memcpy(progress, &sctx->stat, sizeof(*progress));
4304         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4305
4306         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
4307 }
4308
4309 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
4310                                u64 extent_logical, u64 extent_len,
4311                                u64 *extent_physical,
4312                                struct btrfs_device **extent_dev,
4313                                int *extent_mirror_num)
4314 {
4315         u64 mapped_length;
4316         struct btrfs_bio *bbio = NULL;
4317         int ret;
4318
4319         mapped_length = extent_len;
4320         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, extent_logical,
4321                               &mapped_length, &bbio, 0);
4322         if (ret || !bbio || mapped_length < extent_len ||
4323             !bbio->stripes[0].dev->bdev) {
4324                 btrfs_put_bbio(bbio);
4325                 return;
4326         }
4327
4328         *extent_physical = bbio->stripes[0].physical;
4329         *extent_mirror_num = bbio->mirror_num;
4330         *extent_dev = bbio->stripes[0].dev;
4331         btrfs_put_bbio(bbio);
4332 }
4333
4334 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
4335                             int mirror_num, u64 physical_for_dev_replace)
4336 {
4337         struct scrub_copy_nocow_ctx *nocow_ctx;
4338         struct btrfs_fs_info *fs_info = sctx->fs_info;
4339
4340         nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
4341         if (!nocow_ctx) {
4342                 spin_lock(&sctx->stat_lock);
4343                 sctx->stat.malloc_errors++;
4344                 spin_unlock(&sctx->stat_lock);
4345                 return -ENOMEM;
4346         }
4347
4348         scrub_pending_trans_workers_inc(sctx);
4349
4350         nocow_ctx->sctx = sctx;
4351         nocow_ctx->logical = logical;
4352         nocow_ctx->len = len;
4353         nocow_ctx->mirror_num = mirror_num;
4354         nocow_ctx->physical_for_dev_replace = physical_for_dev_replace;
4355         btrfs_init_work(&nocow_ctx->work, btrfs_scrubnc_helper,
4356                         copy_nocow_pages_worker, NULL, NULL);
4357         INIT_LIST_HEAD(&nocow_ctx->inodes);
4358         btrfs_queue_work(fs_info->scrub_nocow_workers,
4359                          &nocow_ctx->work);
4360
4361         return 0;
4362 }
4363
4364 static int record_inode_for_nocow(u64 inum, u64 offset, u64 root, void *ctx)
4365 {
4366         struct scrub_copy_nocow_ctx *nocow_ctx = ctx;
4367         struct scrub_nocow_inode *nocow_inode;
4368
4369         nocow_inode = kzalloc(sizeof(*nocow_inode), GFP_NOFS);
4370         if (!nocow_inode)
4371                 return -ENOMEM;
4372         nocow_inode->inum = inum;
4373         nocow_inode->offset = offset;
4374         nocow_inode->root = root;
4375         list_add_tail(&nocow_inode->list, &nocow_ctx->inodes);
4376         return 0;
4377 }
4378
4379 #define COPY_COMPLETE 1
4380
4381 static void copy_nocow_pages_worker(struct btrfs_work *work)
4382 {
4383         struct scrub_copy_nocow_ctx *nocow_ctx =
4384                 container_of(work, struct scrub_copy_nocow_ctx, work);
4385         struct scrub_ctx *sctx = nocow_ctx->sctx;
4386         struct btrfs_fs_info *fs_info = sctx->fs_info;
4387         struct btrfs_root *root = fs_info->extent_root;
4388         u64 logical = nocow_ctx->logical;
4389         u64 len = nocow_ctx->len;
4390         int mirror_num = nocow_ctx->mirror_num;
4391         u64 physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
4392         int ret;
4393         struct btrfs_trans_handle *trans = NULL;
4394         struct btrfs_path *path;
4395         int not_written = 0;
4396
4397         path = btrfs_alloc_path();
4398         if (!path) {
4399                 spin_lock(&sctx->stat_lock);
4400                 sctx->stat.malloc_errors++;
4401                 spin_unlock(&sctx->stat_lock);
4402                 not_written = 1;
4403                 goto out;
4404         }
4405
4406         trans = btrfs_join_transaction(root);
4407         if (IS_ERR(trans)) {
4408                 not_written = 1;
4409                 goto out;
4410         }
4411
4412         ret = iterate_inodes_from_logical(logical, fs_info, path,
4413                                           record_inode_for_nocow, nocow_ctx);
4414         if (ret != 0 && ret != -ENOENT) {
4415                 btrfs_warn(fs_info,
4416                            "iterate_inodes_from_logical() failed: log %llu, phys %llu, len %llu, mir %u, ret %d",
4417                            logical, physical_for_dev_replace, len, mirror_num,
4418                            ret);
4419                 not_written = 1;
4420                 goto out;
4421         }
4422
4423         btrfs_end_transaction(trans);
4424         trans = NULL;
4425         while (!list_empty(&nocow_ctx->inodes)) {
4426                 struct scrub_nocow_inode *entry;
4427                 entry = list_first_entry(&nocow_ctx->inodes,
4428                                          struct scrub_nocow_inode,
4429                                          list);
4430                 list_del_init(&entry->list);
4431                 ret = copy_nocow_pages_for_inode(entry->inum, entry->offset,
4432                                                  entry->root, nocow_ctx);
4433                 kfree(entry);
4434                 if (ret == COPY_COMPLETE) {
4435                         ret = 0;
4436                         break;
4437                 } else if (ret) {
4438                         break;
4439                 }
4440         }
4441 out:
4442         while (!list_empty(&nocow_ctx->inodes)) {
4443                 struct scrub_nocow_inode *entry;
4444                 entry = list_first_entry(&nocow_ctx->inodes,
4445                                          struct scrub_nocow_inode,
4446                                          list);
4447                 list_del_init(&entry->list);
4448                 kfree(entry);
4449         }
4450         if (trans && !IS_ERR(trans))
4451                 btrfs_end_transaction(trans);
4452         if (not_written)
4453                 btrfs_dev_replace_stats_inc(&fs_info->dev_replace.
4454                                             num_uncorrectable_read_errors);
4455
4456         btrfs_free_path(path);
4457         kfree(nocow_ctx);
4458
4459         scrub_pending_trans_workers_dec(sctx);
4460 }
4461
4462 static int check_extent_to_block(struct btrfs_inode *inode, u64 start, u64 len,
4463                                  u64 logical)
4464 {
4465         struct extent_state *cached_state = NULL;
4466         struct btrfs_ordered_extent *ordered;
4467         struct extent_io_tree *io_tree;
4468         struct extent_map *em;
4469         u64 lockstart = start, lockend = start + len - 1;
4470         int ret = 0;
4471
4472         io_tree = &inode->io_tree;
4473
4474         lock_extent_bits(io_tree, lockstart, lockend, &cached_state);
4475         ordered = btrfs_lookup_ordered_range(inode, lockstart, len);
4476         if (ordered) {
4477                 btrfs_put_ordered_extent(ordered);
4478                 ret = 1;
4479                 goto out_unlock;
4480         }
4481
4482         em = btrfs_get_extent(inode, NULL, 0, start, len, 0);
4483         if (IS_ERR(em)) {
4484                 ret = PTR_ERR(em);
4485                 goto out_unlock;
4486         }
4487
4488         /*
4489          * This extent does not actually cover the logical extent anymore,
4490          * move on to the next inode.
4491          */
4492         if (em->block_start > logical ||
4493             em->block_start + em->block_len < logical + len) {
4494                 free_extent_map(em);
4495                 ret = 1;
4496                 goto out_unlock;
4497         }
4498         free_extent_map(em);
4499
4500 out_unlock:
4501         unlock_extent_cached(io_tree, lockstart, lockend, &cached_state,
4502                              GFP_NOFS);
4503         return ret;
4504 }
4505
4506 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
4507                                       struct scrub_copy_nocow_ctx *nocow_ctx)
4508 {
4509         struct btrfs_fs_info *fs_info = nocow_ctx->sctx->fs_info;
4510         struct btrfs_key key;
4511         struct inode *inode;
4512         struct page *page;
4513         struct btrfs_root *local_root;
4514         struct extent_io_tree *io_tree;
4515         u64 physical_for_dev_replace;
4516         u64 nocow_ctx_logical;
4517         u64 len = nocow_ctx->len;
4518         unsigned long index;
4519         int srcu_index;
4520         int ret = 0;
4521         int err = 0;
4522
4523         key.objectid = root;
4524         key.type = BTRFS_ROOT_ITEM_KEY;
4525         key.offset = (u64)-1;
4526
4527         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
4528
4529         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
4530         if (IS_ERR(local_root)) {
4531                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
4532                 return PTR_ERR(local_root);
4533         }
4534
4535         key.type = BTRFS_INODE_ITEM_KEY;
4536         key.objectid = inum;
4537         key.offset = 0;
4538         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
4539         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
4540         if (IS_ERR(inode))
4541                 return PTR_ERR(inode);
4542
4543         /* Avoid truncate/dio/punch hole.. */
4544         inode_lock(inode);
4545         inode_dio_wait(inode);
4546
4547         physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
4548         io_tree = &BTRFS_I(inode)->io_tree;
4549         nocow_ctx_logical = nocow_ctx->logical;
4550
4551         ret = check_extent_to_block(BTRFS_I(inode), offset, len,
4552                         nocow_ctx_logical);
4553         if (ret) {
4554                 ret = ret > 0 ? 0 : ret;
4555                 goto out;
4556         }
4557
4558         while (len >= PAGE_SIZE) {
4559                 index = offset >> PAGE_SHIFT;
4560 again:
4561                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
4562                 if (!page) {
4563                         btrfs_err(fs_info, "find_or_create_page() failed");
4564                         ret = -ENOMEM;
4565                         goto out;
4566                 }
4567
4568                 if (PageUptodate(page)) {
4569                         if (PageDirty(page))
4570                                 goto next_page;
4571                 } else {
4572                         ClearPageError(page);
4573                         err = extent_read_full_page(io_tree, page,
4574                                                            btrfs_get_extent,
4575                                                            nocow_ctx->mirror_num);
4576                         if (err) {
4577                                 ret = err;
4578                                 goto next_page;
4579                         }
4580
4581                         lock_page(page);
4582                         /*
4583                          * If the page has been remove from the page cache,
4584                          * the data on it is meaningless, because it may be
4585                          * old one, the new data may be written into the new
4586                          * page in the page cache.
4587                          */
4588                         if (page->mapping != inode->i_mapping) {
4589                                 unlock_page(page);
4590                                 put_page(page);
4591                                 goto again;
4592                         }
4593                         if (!PageUptodate(page)) {
4594                                 ret = -EIO;
4595                                 goto next_page;
4596                         }
4597                 }
4598
4599                 ret = check_extent_to_block(BTRFS_I(inode), offset, len,
4600                                             nocow_ctx_logical);
4601                 if (ret) {
4602                         ret = ret > 0 ? 0 : ret;
4603                         goto next_page;
4604                 }
4605
4606                 err = write_page_nocow(nocow_ctx->sctx,
4607                                        physical_for_dev_replace, page);
4608                 if (err)
4609                         ret = err;
4610 next_page:
4611                 unlock_page(page);
4612                 put_page(page);
4613
4614                 if (ret)
4615                         break;
4616
4617                 offset += PAGE_SIZE;
4618                 physical_for_dev_replace += PAGE_SIZE;
4619                 nocow_ctx_logical += PAGE_SIZE;
4620                 len -= PAGE_SIZE;
4621         }
4622         ret = COPY_COMPLETE;
4623 out:
4624         inode_unlock(inode);
4625         iput(inode);
4626         return ret;
4627 }
4628
4629 static int write_page_nocow(struct scrub_ctx *sctx,
4630                             u64 physical_for_dev_replace, struct page *page)
4631 {
4632         struct bio *bio;
4633         struct btrfs_device *dev;
4634         int ret;
4635
4636         dev = sctx->wr_tgtdev;
4637         if (!dev)
4638                 return -EIO;
4639         if (!dev->bdev) {
4640                 btrfs_warn_rl(dev->fs_info,
4641                         "scrub write_page_nocow(bdev == NULL) is unexpected");
4642                 return -EIO;
4643         }
4644         bio = btrfs_io_bio_alloc(1);
4645         bio->bi_iter.bi_size = 0;
4646         bio->bi_iter.bi_sector = physical_for_dev_replace >> 9;
4647         bio_set_dev(bio, dev->bdev);
4648         bio->bi_opf = REQ_OP_WRITE | REQ_SYNC;
4649         ret = bio_add_page(bio, page, PAGE_SIZE, 0);
4650         if (ret != PAGE_SIZE) {
4651 leave_with_eio:
4652                 bio_put(bio);
4653                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
4654                 return -EIO;
4655         }
4656
4657         if (btrfsic_submit_bio_wait(bio))
4658                 goto leave_with_eio;
4659
4660         bio_put(bio);
4661         return 0;
4662 }