fs/btrfs/scrub.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2011, 2012 STRATO.  All rights reserved.
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/ratelimit.h>
   8 #include <linux/sched/mm.h>
   9 #include <crypto/hash.h>
  10 #include "ctree.h"
  11 #include "volumes.h"
  12 #include "disk-io.h"
  13 #include "ordered-data.h"
  14 #include "transaction.h"
  15 #include "backref.h"
  16 #include "extent_io.h"
  17 #include "dev-replace.h"
  18 #include "check-integrity.h"
  19 #include "rcu-string.h"
  20 #include "raid56.h"
  21
  22 /*
  23  * This is only the first step towards a full-features scrub. It reads all
  24  * extent and super block and verifies the checksums. In case a bad checksum
  25  * is found or the extent cannot be read, good data will be written back if
  26  * any can be found.
  27  *
  28  * Future enhancements:
  29  *  - In case an unrepairable extent is encountered, track which files are
  30  *    affected and report them
  31  *  - track and record media errors, throw out bad devices
  32  *  - add a mode to also read unallocated space
  33  */
  34
  35 struct scrub_block;
  36 struct scrub_ctx;
  37
  38 /*
  39  * the following three values only influence the performance.
  40  * The last one configures the number of parallel and outstanding I/O
  41  * operations. The first two values configure an upper limit for the number
  42  * of (dynamically allocated) pages that are added to a bio.
  43  */
  44 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  45 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  46 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  47
  48 /*
  49  * the following value times PAGE_SIZE needs to be large enough to match the
  50  * largest node/leaf/sector size that shall be supported.
  51  * Values larger than BTRFS_STRIPE_LEN are not supported.
  52  */
  53 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  54
  55 struct scrub_recover {
  56         refcount_t              refs;
  57         struct btrfs_bio        *bbio;
  58         u64                     map_length;
  59 };
  60
  61 struct scrub_page {
  62         struct scrub_block      *sblock;
  63         struct page             *page;
  64         struct btrfs_device     *dev;
  65         struct list_head        list;
  66         u64                     flags;  /* extent flags */
  67         u64                     generation;
  68         u64                     logical;
  69         u64                     physical;
  70         u64                     physical_for_dev_replace;
  71         atomic_t                refs;
  72         struct {
  73                 unsigned int    mirror_num:8;
  74                 unsigned int    have_csum:1;
  75                 unsigned int    io_error:1;
  76         };
  77         u8                      csum[BTRFS_CSUM_SIZE];
  78
  79         struct scrub_recover    *recover;
  80 };
  81
  82 struct scrub_bio {
  83         int                     index;
  84         struct scrub_ctx        *sctx;
  85         struct btrfs_device     *dev;
  86         struct bio              *bio;
  87         blk_status_t            status;
  88         u64                     logical;
  89         u64                     physical;
  90 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
  91         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
  92 #else
  93         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
  94 #endif
  95         int                     page_count;
  96         int                     next_free;
  97         struct btrfs_work       work;
  98 };
  99
 100 struct scrub_block {
 101         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 102         int                     page_count;
 103         atomic_t                outstanding_pages;
 104         refcount_t              refs; /* free mem on transition to zero */
 105         struct scrub_ctx        *sctx;
 106         struct scrub_parity     *sparity;
 107         struct {
 108                 unsigned int    header_error:1;
 109                 unsigned int    checksum_error:1;
 110                 unsigned int    no_io_error_seen:1;
 111                 unsigned int    generation_error:1; /* also sets header_error */
 112
 113                 /* The following is for the data used to check parity */
 114                 /* It is for the data with checksum */
 115                 unsigned int    data_corrected:1;
 116         };
 117         struct btrfs_work       work;
 118 };
 119
 120 /* Used for the chunks with parity stripe such RAID5/6 */
 121 struct scrub_parity {
 122         struct scrub_ctx        *sctx;
 123
 124         struct btrfs_device     *scrub_dev;
 125
 126         u64                     logic_start;
 127
 128         u64                     logic_end;
 129
 130         int                     nsectors;
 131
 132         u64                     stripe_len;
 133
 134         refcount_t              refs;
 135
 136         struct list_head        spages;
 137
 138         /* Work of parity check and repair */
 139         struct btrfs_work       work;
 140
 141         /* Mark the parity blocks which have data */
 142         unsigned long           *dbitmap;
 143
 144         /*
 145          * Mark the parity blocks which have data, but errors happen when
 146          * read data or check data
 147          */
 148         unsigned long           *ebitmap;
 149
 150         unsigned long           bitmap[0];
 151 };
 152
 153 struct scrub_ctx {
 154         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 155         struct btrfs_fs_info    *fs_info;
 156         int                     first_free;
 157         int                     curr;
 158         atomic_t                bios_in_flight;
 159         atomic_t                workers_pending;
 160         spinlock_t              list_lock;
 161         wait_queue_head_t       list_wait;
 162         u16                     csum_size;
 163         struct list_head        csum_list;
 164         atomic_t                cancel_req;
 165         int                     readonly;
 166         int                     pages_per_rd_bio;
 167
 168         int                     is_dev_replace;
 169
 170         struct scrub_bio        *wr_curr_bio;
 171         struct mutex            wr_lock;
 172         int                     pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 173         struct btrfs_device     *wr_tgtdev;
 174         bool                    flush_all_writes;
 175
 176         /*
 177          * statistics
 178          */
 179         struct btrfs_scrub_progress stat;
 180         spinlock_t              stat_lock;
 181
 182         /*
 183          * Use a ref counter to avoid use-after-free issues. Scrub workers
 184          * decrement bios_in_flight and workers_pending and then do a wakeup
 185          * on the list_wait wait queue. We must ensure the main scrub task
 186          * doesn't free the scrub context before or while the workers are
 187          * doing the wakeup() call.
 188          */
 189         refcount_t              refs;
 190 };
 191
 192 struct scrub_warning {
 193         struct btrfs_path       *path;
 194         u64                     extent_item_size;
 195         const char              *errstr;
 196         u64                     physical;
 197         u64                     logical;
 198         struct btrfs_device     *dev;
 199 };
 200
 201 struct full_stripe_lock {
 202         struct rb_node node;
 203         u64 logical;
 204         u64 refs;
 205         struct mutex mutex;
 206 };
 207
 208 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 209 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 210 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 211 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 212                                      struct scrub_block *sblocks_for_recheck);
 213 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 214                                 struct scrub_block *sblock,
 215                                 int retry_failed_mirror);
 216 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 217 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 218                                              struct scrub_block *sblock_good);
 219 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 220                                             struct scrub_block *sblock_good,
 221                                             int page_num, int force_write);
 222 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 223 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 224                                            int page_num);
 225 static int scrub_checksum_data(struct scrub_block *sblock);
 226 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 227 static int scrub_checksum_super(struct scrub_block *sblock);
 228 static void scrub_block_get(struct scrub_block *sblock);
 229 static void scrub_block_put(struct scrub_block *sblock);
 230 static void scrub_page_get(struct scrub_page *spage);
 231 static void scrub_page_put(struct scrub_page *spage);
 232 static void scrub_parity_get(struct scrub_parity *sparity);
 233 static void scrub_parity_put(struct scrub_parity *sparity);
 234 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 235                                     struct scrub_page *spage);
 236 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 237                        u64 physical, struct btrfs_device *dev, u64 flags,
 238                        u64 gen, int mirror_num, u8 *csum, int force,
 239                        u64 physical_for_dev_replace);
 240 static void scrub_bio_end_io(struct bio *bio);
 241 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 242 static void scrub_block_complete(struct scrub_block *sblock);
 243 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 244                                u64 extent_logical, u64 extent_len,
 245                                u64 *extent_physical,
 246                                struct btrfs_device **extent_dev,
 247                                int *extent_mirror_num);
 248 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 249                                     struct scrub_page *spage);
 250 static void scrub_wr_submit(struct scrub_ctx *sctx);
 251 static void scrub_wr_bio_end_io(struct bio *bio);
 252 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 253 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 254 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 255 static void scrub_put_ctx(struct scrub_ctx *sctx);
 256
 257 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
 258 {
 259         return page->recover &&
 260                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
 261 }
 262
 263 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 264 {
 265         refcount_inc(&sctx->refs);
 266         atomic_inc(&sctx->bios_in_flight);
 267 }
 268
 269 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 270 {
 271         atomic_dec(&sctx->bios_in_flight);
 272         wake_up(&sctx->list_wait);
 273         scrub_put_ctx(sctx);
 274 }
 275
 276 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 277 {
 278         while (atomic_read(&fs_info->scrub_pause_req)) {
 279                 mutex_unlock(&fs_info->scrub_lock);
 280                 wait_event(fs_info->scrub_pause_wait,
 281                    atomic_read(&fs_info->scrub_pause_req) == 0);
 282                 mutex_lock(&fs_info->scrub_lock);
 283         }
 284 }
 285
 286 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 287 {
 288         atomic_inc(&fs_info->scrubs_paused);
 289         wake_up(&fs_info->scrub_pause_wait);
 290 }
 291
 292 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 293 {
 294         mutex_lock(&fs_info->scrub_lock);
 295         __scrub_blocked_if_needed(fs_info);
 296         atomic_dec(&fs_info->scrubs_paused);
 297         mutex_unlock(&fs_info->scrub_lock);
 298
 299         wake_up(&fs_info->scrub_pause_wait);
 300 }
 301
 302 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 303 {
 304         scrub_pause_on(fs_info);
 305         scrub_pause_off(fs_info);
 306 }
 307
 308 /*
 309  * Insert new full stripe lock into full stripe locks tree
 310  *
 311  * Return pointer to existing or newly inserted full_stripe_lock structure if
 312  * everything works well.
 313  * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
 314  *
 315  * NOTE: caller must hold full_stripe_locks_root->lock before calling this
 316  * function
 317  */
 318 static struct full_stripe_lock *insert_full_stripe_lock(
 319                 struct btrfs_full_stripe_locks_tree *locks_root,
 320                 u64 fstripe_logical)
 321 {
 322         struct rb_node **p;
 323         struct rb_node *parent = NULL;
 324         struct full_stripe_lock *entry;
 325         struct full_stripe_lock *ret;
 326
 327         lockdep_assert_held(&locks_root->lock);
 328
 329         p = &locks_root->root.rb_node;
 330         while (*p) {
 331                 parent = *p;
 332                 entry = rb_entry(parent, struct full_stripe_lock, node);
 333                 if (fstripe_logical < entry->logical) {
 334                         p = &(*p)->rb_left;
 335                 } else if (fstripe_logical > entry->logical) {
 336                         p = &(*p)->rb_right;
 337                 } else {
 338                         entry->refs++;
 339                         return entry;
 340                 }
 341         }
 342
 343         /*
 344          * Insert new lock.
 345          */
 346         ret = kmalloc(sizeof(*ret), GFP_KERNEL);
 347         if (!ret)
 348                 return ERR_PTR(-ENOMEM);
 349         ret->logical = fstripe_logical;
 350         ret->refs = 1;
 351         mutex_init(&ret->mutex);
 352
 353         rb_link_node(&ret->node, parent, p);
 354         rb_insert_color(&ret->node, &locks_root->root);
 355         return ret;
 356 }
 357
 358 /*
 359  * Search for a full stripe lock of a block group
 360  *
 361  * Return pointer to existing full stripe lock if found
 362  * Return NULL if not found
 363  */
 364 static struct full_stripe_lock *search_full_stripe_lock(
 365                 struct btrfs_full_stripe_locks_tree *locks_root,
 366                 u64 fstripe_logical)
 367 {
 368         struct rb_node *node;
 369         struct full_stripe_lock *entry;
 370
 371         lockdep_assert_held(&locks_root->lock);
 372
 373         node = locks_root->root.rb_node;
 374         while (node) {
 375                 entry = rb_entry(node, struct full_stripe_lock, node);
 376                 if (fstripe_logical < entry->logical)
 377                         node = node->rb_left;
 378                 else if (fstripe_logical > entry->logical)
 379                         node = node->rb_right;
 380                 else
 381                         return entry;
 382         }
 383         return NULL;
 384 }
 385
 386 /*
 387  * Helper to get full stripe logical from a normal bytenr.
 388  *
 389  * Caller must ensure @cache is a RAID56 block group.
 390  */
 391 static u64 get_full_stripe_logical(struct btrfs_block_group_cache *cache,
 392                                    u64 bytenr)
 393 {
 394         u64 ret;
 395
 396         /*
 397          * Due to chunk item size limit, full stripe length should not be
 398          * larger than U32_MAX. Just a sanity check here.
 399          */
 400         WARN_ON_ONCE(cache->full_stripe_len >= U32_MAX);
 401
 402         /*
 403          * round_down() can only handle power of 2, while RAID56 full
 404          * stripe length can be 64KiB * n, so we need to manually round down.
 405          */
 406         ret = div64_u64(bytenr - cache->key.objectid, cache->full_stripe_len) *
 407                 cache->full_stripe_len + cache->key.objectid;
 408         return ret;
 409 }
 410
 411 /*
 412  * Lock a full stripe to avoid concurrency of recovery and read
 413  *
 414  * It's only used for profiles with parities (RAID5/6), for other profiles it
 415  * does nothing.
 416  *
 417  * Return 0 if we locked full stripe covering @bytenr, with a mutex held.
 418  * So caller must call unlock_full_stripe() at the same context.
 419  *
 420  * Return <0 if encounters error.
 421  */
 422 static int lock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 423                             bool *locked_ret)
 424 {
 425         struct btrfs_block_group_cache *bg_cache;
 426         struct btrfs_full_stripe_locks_tree *locks_root;
 427         struct full_stripe_lock *existing;
 428         u64 fstripe_start;
 429         int ret = 0;
 430
 431         *locked_ret = false;
 432         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 433         if (!bg_cache) {
 434                 ASSERT(0);
 435                 return -ENOENT;
 436         }
 437
 438         /* Profiles not based on parity don't need full stripe lock */
 439         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 440                 goto out;
 441         locks_root = &bg_cache->full_stripe_locks_root;
 442
 443         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 444
 445         /* Now insert the full stripe lock */
 446         mutex_lock(&locks_root->lock);
 447         existing = insert_full_stripe_lock(locks_root, fstripe_start);
 448         mutex_unlock(&locks_root->lock);
 449         if (IS_ERR(existing)) {
 450                 ret = PTR_ERR(existing);
 451                 goto out;
 452         }
 453         mutex_lock(&existing->mutex);
 454         *locked_ret = true;
 455 out:
 456         btrfs_put_block_group(bg_cache);
 457         return ret;
 458 }
 459
 460 /*
 461  * Unlock a full stripe.
 462  *
 463  * NOTE: Caller must ensure it's the same context calling corresponding
 464  * lock_full_stripe().
 465  *
 466  * Return 0 if we unlock full stripe without problem.
 467  * Return <0 for error
 468  */
 469 static int unlock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 470                               bool locked)
 471 {
 472         struct btrfs_block_group_cache *bg_cache;
 473         struct btrfs_full_stripe_locks_tree *locks_root;
 474         struct full_stripe_lock *fstripe_lock;
 475         u64 fstripe_start;
 476         bool freeit = false;
 477         int ret = 0;
 478
 479         /* If we didn't acquire full stripe lock, no need to continue */
 480         if (!locked)
 481                 return 0;
 482
 483         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 484         if (!bg_cache) {
 485                 ASSERT(0);
 486                 return -ENOENT;
 487         }
 488         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 489                 goto out;
 490
 491         locks_root = &bg_cache->full_stripe_locks_root;
 492         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 493
 494         mutex_lock(&locks_root->lock);
 495         fstripe_lock = search_full_stripe_lock(locks_root, fstripe_start);
 496         /* Unpaired unlock_full_stripe() detected */
 497         if (!fstripe_lock) {
 498                 WARN_ON(1);
 499                 ret = -ENOENT;
 500                 mutex_unlock(&locks_root->lock);
 501                 goto out;
 502         }
 503
 504         if (fstripe_lock->refs == 0) {
 505                 WARN_ON(1);
 506                 btrfs_warn(fs_info, "full stripe lock at %llu refcount underflow",
 507                         fstripe_lock->logical);
 508         } else {
 509                 fstripe_lock->refs--;
 510         }
 511
 512         if (fstripe_lock->refs == 0) {
 513                 rb_erase(&fstripe_lock->node, &locks_root->root);
 514                 freeit = true;
 515         }
 516         mutex_unlock(&locks_root->lock);
 517
 518         mutex_unlock(&fstripe_lock->mutex);
 519         if (freeit)
 520                 kfree(fstripe_lock);
 521 out:
 522         btrfs_put_block_group(bg_cache);
 523         return ret;
 524 }
 525
 526 static void scrub_free_csums(struct scrub_ctx *sctx)
 527 {
 528         while (!list_empty(&sctx->csum_list)) {
 529                 struct btrfs_ordered_sum *sum;
 530                 sum = list_first_entry(&sctx->csum_list,
 531                                        struct btrfs_ordered_sum, list);
 532                 list_del(&sum->list);
 533                 kfree(sum);
 534         }
 535 }
 536
 537 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 538 {
 539         int i;
 540
 541         if (!sctx)
 542                 return;
 543
 544         /* this can happen when scrub is cancelled */
 545         if (sctx->curr != -1) {
 546                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 547
 548                 for (i = 0; i < sbio->page_count; i++) {
 549                         WARN_ON(!sbio->pagev[i]->page);
 550                         scrub_block_put(sbio->pagev[i]->sblock);
 551                 }
 552                 bio_put(sbio->bio);
 553         }
 554
 555         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 556                 struct scrub_bio *sbio = sctx->bios[i];
 557
 558                 if (!sbio)
 559                         break;
 560                 kfree(sbio);
 561         }
 562
 563         kfree(sctx->wr_curr_bio);
 564         scrub_free_csums(sctx);
 565         kfree(sctx);
 566 }
 567
 568 static void scrub_put_ctx(struct scrub_ctx *sctx)
 569 {
 570         if (refcount_dec_and_test(&sctx->refs))
 571                 scrub_free_ctx(sctx);
 572 }
 573
 574 static noinline_for_stack struct scrub_ctx *scrub_setup_ctx(
 575                 struct btrfs_fs_info *fs_info, int is_dev_replace)
 576 {
 577         struct scrub_ctx *sctx;
 578         int             i;
 579
 580         sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 581         if (!sctx)
 582                 goto nomem;
 583         refcount_set(&sctx->refs, 1);
 584         sctx->is_dev_replace = is_dev_replace;
 585         sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 586         sctx->curr = -1;
 587         sctx->fs_info = fs_info;
 588         INIT_LIST_HEAD(&sctx->csum_list);
 589         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 590                 struct scrub_bio *sbio;
 591
 592                 sbio = kzalloc(sizeof(*sbio), GFP_KERNEL);
 593                 if (!sbio)
 594                         goto nomem;
 595                 sctx->bios[i] = sbio;
 596
 597                 sbio->index = i;
 598                 sbio->sctx = sctx;
 599                 sbio->page_count = 0;
 600                 btrfs_init_work(&sbio->work, btrfs_scrub_helper,
 601                                 scrub_bio_end_io_worker, NULL, NULL);
 602
 603                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 604                         sctx->bios[i]->next_free = i + 1;
 605                 else
 606                         sctx->bios[i]->next_free = -1;
 607         }
 608         sctx->first_free = 0;
 609         atomic_set(&sctx->bios_in_flight, 0);
 610         atomic_set(&sctx->workers_pending, 0);
 611         atomic_set(&sctx->cancel_req, 0);
 612         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 613
 614         spin_lock_init(&sctx->list_lock);
 615         spin_lock_init(&sctx->stat_lock);
 616         init_waitqueue_head(&sctx->list_wait);
 617
 618         WARN_ON(sctx->wr_curr_bio != NULL);
 619         mutex_init(&sctx->wr_lock);
 620         sctx->wr_curr_bio = NULL;
 621         if (is_dev_replace) {
 622                 WARN_ON(!fs_info->dev_replace.tgtdev);
 623                 sctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
 624                 sctx->wr_tgtdev = fs_info->dev_replace.tgtdev;
 625                 sctx->flush_all_writes = false;
 626         }
 627
 628         return sctx;
 629
 630 nomem:
 631         scrub_free_ctx(sctx);
 632         return ERR_PTR(-ENOMEM);
 633 }
 634
 635 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 636                                      void *warn_ctx)
 637 {
 638         u64 isize;
 639         u32 nlink;
 640         int ret;
 641         int i;
 642         unsigned nofs_flag;
 643         struct extent_buffer *eb;
 644         struct btrfs_inode_item *inode_item;
 645         struct scrub_warning *swarn = warn_ctx;
 646         struct btrfs_fs_info *fs_info = swarn->dev->fs_info;
 647         struct inode_fs_paths *ipath = NULL;
 648         struct btrfs_root *local_root;
 649         struct btrfs_key root_key;
 650         struct btrfs_key key;
 651
 652         root_key.objectid = root;
 653         root_key.type = BTRFS_ROOT_ITEM_KEY;
 654         root_key.offset = (u64)-1;
 655         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 656         if (IS_ERR(local_root)) {
 657                 ret = PTR_ERR(local_root);
 658                 goto err;
 659         }
 660
 661         /*
 662          * this makes the path point to (inum INODE_ITEM ioff)
 663          */
 664         key.objectid = inum;
 665         key.type = BTRFS_INODE_ITEM_KEY;
 666         key.offset = 0;
 667
 668         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 669         if (ret) {
 670                 btrfs_release_path(swarn->path);
 671                 goto err;
 672         }
 673
 674         eb = swarn->path->nodes[0];
 675         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 676                                         struct btrfs_inode_item);
 677         isize = btrfs_inode_size(eb, inode_item);
 678         nlink = btrfs_inode_nlink(eb, inode_item);
 679         btrfs_release_path(swarn->path);
 680
 681         /*
 682          * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
 683          * uses GFP_NOFS in this context, so we keep it consistent but it does
 684          * not seem to be strictly necessary.
 685          */
 686         nofs_flag = memalloc_nofs_save();
 687         ipath = init_ipath(4096, local_root, swarn->path);
 688         memalloc_nofs_restore(nofs_flag);
 689         if (IS_ERR(ipath)) {
 690                 ret = PTR_ERR(ipath);
 691                 ipath = NULL;
 692                 goto err;
 693         }
 694         ret = paths_from_inode(inum, ipath);
 695
 696         if (ret < 0)
 697                 goto err;
 698
 699         /*
 700          * we deliberately ignore the bit ipath might have been too small to
 701          * hold all of the paths here
 702          */
 703         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 704                 btrfs_warn_in_rcu(fs_info,
 705 "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu, length %llu, links %u (path: %s)",
 706                                   swarn->errstr, swarn->logical,
 707                                   rcu_str_deref(swarn->dev->name),
 708                                   swarn->physical,
 709                                   root, inum, offset,
 710                                   min(isize - offset, (u64)PAGE_SIZE), nlink,
 711                                   (char *)(unsigned long)ipath->fspath->val[i]);
 712
 713         free_ipath(ipath);
 714         return 0;
 715
 716 err:
 717         btrfs_warn_in_rcu(fs_info,
 718                           "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu: path resolving failed with ret=%d",
 719                           swarn->errstr, swarn->logical,
 720                           rcu_str_deref(swarn->dev->name),
 721                           swarn->physical,
 722                           root, inum, offset, ret);
 723
 724         free_ipath(ipath);
 725         return 0;
 726 }
 727
 728 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 729 {
 730         struct btrfs_device *dev;
 731         struct btrfs_fs_info *fs_info;
 732         struct btrfs_path *path;
 733         struct btrfs_key found_key;
 734         struct extent_buffer *eb;
 735         struct btrfs_extent_item *ei;
 736         struct scrub_warning swarn;
 737         unsigned long ptr = 0;
 738         u64 extent_item_pos;
 739         u64 flags = 0;
 740         u64 ref_root;
 741         u32 item_size;
 742         u8 ref_level = 0;
 743         int ret;
 744
 745         WARN_ON(sblock->page_count < 1);
 746         dev = sblock->pagev[0]->dev;
 747         fs_info = sblock->sctx->fs_info;
 748
 749         path = btrfs_alloc_path();
 750         if (!path)
 751                 return;
 752
 753         swarn.physical = sblock->pagev[0]->physical;
 754         swarn.logical = sblock->pagev[0]->logical;
 755         swarn.errstr = errstr;
 756         swarn.dev = NULL;
 757
 758         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 759                                   &flags);
 760         if (ret < 0)
 761                 goto out;
 762
 763         extent_item_pos = swarn.logical - found_key.objectid;
 764         swarn.extent_item_size = found_key.offset;
 765
 766         eb = path->nodes[0];
 767         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 768         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 769
 770         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 771                 do {
 772                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 773                                                       item_size, &ref_root,
 774                                                       &ref_level);
 775                         btrfs_warn_in_rcu(fs_info,
 776 "%s at logical %llu on dev %s, physical %llu: metadata %s (level %d) in tree %llu",
 777                                 errstr, swarn.logical,
 778                                 rcu_str_deref(dev->name),
 779                                 swarn.physical,
 780                                 ref_level ? "node" : "leaf",
 781                                 ret < 0 ? -1 : ref_level,
 782                                 ret < 0 ? -1 : ref_root);
 783                 } while (ret != 1);
 784                 btrfs_release_path(path);
 785         } else {
 786                 btrfs_release_path(path);
 787                 swarn.path = path;
 788                 swarn.dev = dev;
 789                 iterate_extent_inodes(fs_info, found_key.objectid,
 790                                         extent_item_pos, 1,
 791                                         scrub_print_warning_inode, &swarn, false);
 792         }
 793
 794 out:
 795         btrfs_free_path(path);
 796 }
 797
 798 static inline void scrub_get_recover(struct scrub_recover *recover)
 799 {
 800         refcount_inc(&recover->refs);
 801 }
 802
 803 static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
 804                                      struct scrub_recover *recover)
 805 {
 806         if (refcount_dec_and_test(&recover->refs)) {
 807                 btrfs_bio_counter_dec(fs_info);
 808                 btrfs_put_bbio(recover->bbio);
 809                 kfree(recover);
 810         }
 811 }
 812
 813 /*
 814  * scrub_handle_errored_block gets called when either verification of the
 815  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 816  * case, this function handles all pages in the bio, even though only one
 817  * may be bad.
 818  * The goal of this function is to repair the errored block by using the
 819  * contents of one of the mirrors.
 820  */
 821 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 822 {
 823         struct scrub_ctx *sctx = sblock_to_check->sctx;
 824         struct btrfs_device *dev;
 825         struct btrfs_fs_info *fs_info;
 826         u64 logical;
 827         unsigned int failed_mirror_index;
 828         unsigned int is_metadata;
 829         unsigned int have_csum;
 830         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 831         struct scrub_block *sblock_bad;
 832         int ret;
 833         int mirror_index;
 834         int page_num;
 835         int success;
 836         bool full_stripe_locked;
 837         unsigned int nofs_flag;
 838         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 839                                       DEFAULT_RATELIMIT_BURST);
 840
 841         BUG_ON(sblock_to_check->page_count < 1);
 842         fs_info = sctx->fs_info;
 843         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 844                 /*
 845                  * if we find an error in a super block, we just report it.
 846                  * They will get written with the next transaction commit
 847                  * anyway
 848                  */
 849                 spin_lock(&sctx->stat_lock);
 850                 ++sctx->stat.super_errors;
 851                 spin_unlock(&sctx->stat_lock);
 852                 return 0;
 853         }
 854         logical = sblock_to_check->pagev[0]->logical;
 855         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 856         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 857         is_metadata = !(sblock_to_check->pagev[0]->flags &
 858                         BTRFS_EXTENT_FLAG_DATA);
 859         have_csum = sblock_to_check->pagev[0]->have_csum;
 860         dev = sblock_to_check->pagev[0]->dev;
 861
 862         /*
 863          * We must use GFP_NOFS because the scrub task might be waiting for a
 864          * worker task executing this function and in turn a transaction commit
 865          * might be waiting the scrub task to pause (which needs to wait for all
 866          * the worker tasks to complete before pausing).
 867          * We do allocations in the workers through insert_full_stripe_lock()
 868          * and scrub_add_page_to_wr_bio(), which happens down the call chain of
 869          * this function.
 870          */
 871         nofs_flag = memalloc_nofs_save();
 872         /*
 873          * For RAID5/6, race can happen for a different device scrub thread.
 874          * For data corruption, Parity and Data threads will both try
 875          * to recovery the data.
 876          * Race can lead to doubly added csum error, or even unrecoverable
 877          * error.
 878          */
 879         ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
 880         if (ret < 0) {
 881                 memalloc_nofs_restore(nofs_flag);
 882                 spin_lock(&sctx->stat_lock);
 883                 if (ret == -ENOMEM)
 884                         sctx->stat.malloc_errors++;
 885                 sctx->stat.read_errors++;
 886                 sctx->stat.uncorrectable_errors++;
 887                 spin_unlock(&sctx->stat_lock);
 888                 return ret;
 889         }
 890
 891         /*
 892          * read all mirrors one after the other. This includes to
 893          * re-read the extent or metadata block that failed (that was
 894          * the cause that this fixup code is called) another time,
 895          * page by page this time in order to know which pages
 896          * caused I/O errors and which ones are good (for all mirrors).
 897          * It is the goal to handle the situation when more than one
 898          * mirror contains I/O errors, but the errors do not
 899          * overlap, i.e. the data can be repaired by selecting the
 900          * pages from those mirrors without I/O error on the
 901          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 902          * would be that mirror #1 has an I/O error on the first page,
 903          * the second page is good, and mirror #2 has an I/O error on
 904          * the second page, but the first page is good.
 905          * Then the first page of the first mirror can be repaired by
 906          * taking the first page of the second mirror, and the
 907          * second page of the second mirror can be repaired by
 908          * copying the contents of the 2nd page of the 1st mirror.
 909          * One more note: if the pages of one mirror contain I/O
 910          * errors, the checksum cannot be verified. In order to get
 911          * the best data for repairing, the first attempt is to find
 912          * a mirror without I/O errors and with a validated checksum.
 913          * Only if this is not possible, the pages are picked from
 914          * mirrors with I/O errors without considering the checksum.
 915          * If the latter is the case, at the end, the checksum of the
 916          * repaired area is verified in order to correctly maintain
 917          * the statistics.
 918          */
 919
 920         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
 921                                       sizeof(*sblocks_for_recheck), GFP_KERNEL);
 922         if (!sblocks_for_recheck) {
 923                 spin_lock(&sctx->stat_lock);
 924                 sctx->stat.malloc_errors++;
 925                 sctx->stat.read_errors++;
 926                 sctx->stat.uncorrectable_errors++;
 927                 spin_unlock(&sctx->stat_lock);
 928                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 929                 goto out;
 930         }
 931
 932         /* setup the context, map the logical blocks and alloc the pages */
 933         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
 934         if (ret) {
 935                 spin_lock(&sctx->stat_lock);
 936                 sctx->stat.read_errors++;
 937                 sctx->stat.uncorrectable_errors++;
 938                 spin_unlock(&sctx->stat_lock);
 939                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 940                 goto out;
 941         }
 942         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 943         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 944
 945         /* build and submit the bios for the failed mirror, check checksums */
 946         scrub_recheck_block(fs_info, sblock_bad, 1);
 947
 948         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 949             sblock_bad->no_io_error_seen) {
 950                 /*
 951                  * the error disappeared after reading page by page, or
 952                  * the area was part of a huge bio and other parts of the
 953                  * bio caused I/O errors, or the block layer merged several
 954                  * read requests into one and the error is caused by a
 955                  * different bio (usually one of the two latter cases is
 956                  * the cause)
 957                  */
 958                 spin_lock(&sctx->stat_lock);
 959                 sctx->stat.unverified_errors++;
 960                 sblock_to_check->data_corrected = 1;
 961                 spin_unlock(&sctx->stat_lock);
 962
 963                 if (sctx->is_dev_replace)
 964                         scrub_write_block_to_dev_replace(sblock_bad);
 965                 goto out;
 966         }
 967
 968         if (!sblock_bad->no_io_error_seen) {
 969                 spin_lock(&sctx->stat_lock);
 970                 sctx->stat.read_errors++;
 971                 spin_unlock(&sctx->stat_lock);
 972                 if (__ratelimit(&_rs))
 973                         scrub_print_warning("i/o error", sblock_to_check);
 974                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 975         } else if (sblock_bad->checksum_error) {
 976                 spin_lock(&sctx->stat_lock);
 977                 sctx->stat.csum_errors++;
 978                 spin_unlock(&sctx->stat_lock);
 979                 if (__ratelimit(&_rs))
 980                         scrub_print_warning("checksum error", sblock_to_check);
 981                 btrfs_dev_stat_inc_and_print(dev,
 982                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
 983         } else if (sblock_bad->header_error) {
 984                 spin_lock(&sctx->stat_lock);
 985                 sctx->stat.verify_errors++;
 986                 spin_unlock(&sctx->stat_lock);
 987                 if (__ratelimit(&_rs))
 988                         scrub_print_warning("checksum/header error",
 989                                             sblock_to_check);
 990                 if (sblock_bad->generation_error)
 991                         btrfs_dev_stat_inc_and_print(dev,
 992                                 BTRFS_DEV_STAT_GENERATION_ERRS);
 993                 else
 994                         btrfs_dev_stat_inc_and_print(dev,
 995                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
 996         }
 997
 998         if (sctx->readonly) {
 999                 ASSERT(!sctx->is_dev_replace);
1000                 goto out;
1001         }
1002
1003         /*
1004          * now build and submit the bios for the other mirrors, check
1005          * checksums.
1006          * First try to pick the mirror which is completely without I/O
1007          * errors and also does not have a checksum error.
1008          * If one is found, and if a checksum is present, the full block
1009          * that is known to contain an error is rewritten. Afterwards
1010          * the block is known to be corrected.
1011          * If a mirror is found which is completely correct, and no
1012          * checksum is present, only those pages are rewritten that had
1013          * an I/O error in the block to be repaired, since it cannot be
1014          * determined, which copy of the other pages is better (and it
1015          * could happen otherwise that a correct page would be
1016          * overwritten by a bad one).
1017          */
1018         for (mirror_index = 0; ;mirror_index++) {
1019                 struct scrub_block *sblock_other;
1020
1021                 if (mirror_index == failed_mirror_index)
1022                         continue;
1023
1024                 /* raid56's mirror can be more than BTRFS_MAX_MIRRORS */
1025                 if (!scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1026                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1027                                 break;
1028                         if (!sblocks_for_recheck[mirror_index].page_count)
1029                                 break;
1030
1031                         sblock_other = sblocks_for_recheck + mirror_index;
1032                 } else {
1033                         struct scrub_recover *r = sblock_bad->pagev[0]->recover;
1034                         int max_allowed = r->bbio->num_stripes -
1035                                                 r->bbio->num_tgtdevs;
1036
1037                         if (mirror_index >= max_allowed)
1038                                 break;
1039                         if (!sblocks_for_recheck[1].page_count)
1040                                 break;
1041
1042                         ASSERT(failed_mirror_index == 0);
1043                         sblock_other = sblocks_for_recheck + 1;
1044                         sblock_other->pagev[0]->mirror_num = 1 + mirror_index;
1045                 }
1046
1047                 /* build and submit the bios, check checksums */
1048                 scrub_recheck_block(fs_info, sblock_other, 0);
1049
1050                 if (!sblock_other->header_error &&
1051                     !sblock_other->checksum_error &&
1052                     sblock_other->no_io_error_seen) {
1053                         if (sctx->is_dev_replace) {
1054                                 scrub_write_block_to_dev_replace(sblock_other);
1055                                 goto corrected_error;
1056                         } else {
1057                                 ret = scrub_repair_block_from_good_copy(
1058                                                 sblock_bad, sblock_other);
1059                                 if (!ret)
1060                                         goto corrected_error;
1061                         }
1062                 }
1063         }
1064
1065         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1066                 goto did_not_correct_error;
1067
1068         /*
1069          * In case of I/O errors in the area that is supposed to be
1070          * repaired, continue by picking good copies of those pages.
1071          * Select the good pages from mirrors to rewrite bad pages from
1072          * the area to fix. Afterwards verify the checksum of the block
1073          * that is supposed to be repaired. This verification step is
1074          * only done for the purpose of statistic counting and for the
1075          * final scrub report, whether errors remain.
1076          * A perfect algorithm could make use of the checksum and try
1077          * all possible combinations of pages from the different mirrors
1078          * until the checksum verification succeeds. For example, when
1079          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1080          * of mirror #2 is readable but the final checksum test fails,
1081          * then the 2nd page of mirror #3 could be tried, whether now
1082          * the final checksum succeeds. But this would be a rare
1083          * exception and is therefore not implemented. At least it is
1084          * avoided that the good copy is overwritten.
1085          * A more useful improvement would be to pick the sectors
1086          * without I/O error based on sector sizes (512 bytes on legacy
1087          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1088          * mirror could be repaired by taking 512 byte of a different
1089          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1090          * area are unreadable.
1091          */
1092         success = 1;
1093         for (page_num = 0; page_num < sblock_bad->page_count;
1094              page_num++) {
1095                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1096                 struct scrub_block *sblock_other = NULL;
1097
1098                 /* skip no-io-error page in scrub */
1099                 if (!page_bad->io_error && !sctx->is_dev_replace)
1100                         continue;
1101
1102                 if (scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1103                         /*
1104                          * In case of dev replace, if raid56 rebuild process
1105                          * didn't work out correct data, then copy the content
1106                          * in sblock_bad to make sure target device is identical
1107                          * to source device, instead of writing garbage data in
1108                          * sblock_for_recheck array to target device.
1109                          */
1110                         sblock_other = NULL;
1111                 } else if (page_bad->io_error) {
1112                         /* try to find no-io-error page in mirrors */
1113                         for (mirror_index = 0;
1114                              mirror_index < BTRFS_MAX_MIRRORS &&
1115                              sblocks_for_recheck[mirror_index].page_count > 0;
1116                              mirror_index++) {
1117                                 if (!sblocks_for_recheck[mirror_index].
1118                                     pagev[page_num]->io_error) {
1119                                         sblock_other = sblocks_for_recheck +
1120                                                        mirror_index;
1121                                         break;
1122                                 }
1123                         }
1124                         if (!sblock_other)
1125                                 success = 0;
1126                 }
1127
1128                 if (sctx->is_dev_replace) {
1129                         /*
1130                          * did not find a mirror to fetch the page
1131                          * from. scrub_write_page_to_dev_replace()
1132                          * handles this case (page->io_error), by
1133                          * filling the block with zeros before
1134                          * submitting the write request
1135                          */
1136                         if (!sblock_other)
1137                                 sblock_other = sblock_bad;
1138
1139                         if (scrub_write_page_to_dev_replace(sblock_other,
1140                                                             page_num) != 0) {
1141                                 atomic64_inc(
1142                                         &fs_info->dev_replace.num_write_errors);
1143                                 success = 0;
1144                         }
1145                 } else if (sblock_other) {
1146                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1147                                                                sblock_other,
1148                                                                page_num, 0);
1149                         if (0 == ret)
1150                                 page_bad->io_error = 0;
1151                         else
1152                                 success = 0;
1153                 }
1154         }
1155
1156         if (success && !sctx->is_dev_replace) {
1157                 if (is_metadata || have_csum) {
1158                         /*
1159                          * need to verify the checksum now that all
1160                          * sectors on disk are repaired (the write
1161                          * request for data to be repaired is on its way).
1162                          * Just be lazy and use scrub_recheck_block()
1163                          * which re-reads the data before the checksum
1164                          * is verified, but most likely the data comes out
1165                          * of the page cache.
1166                          */
1167                         scrub_recheck_block(fs_info, sblock_bad, 1);
1168                         if (!sblock_bad->header_error &&
1169                             !sblock_bad->checksum_error &&
1170                             sblock_bad->no_io_error_seen)
1171                                 goto corrected_error;
1172                         else
1173                                 goto did_not_correct_error;
1174                 } else {
1175 corrected_error:
1176                         spin_lock(&sctx->stat_lock);
1177                         sctx->stat.corrected_errors++;
1178                         sblock_to_check->data_corrected = 1;
1179                         spin_unlock(&sctx->stat_lock);
1180                         btrfs_err_rl_in_rcu(fs_info,
1181                                 "fixed up error at logical %llu on dev %s",
1182                                 logical, rcu_str_deref(dev->name));
1183                 }
1184         } else {
1185 did_not_correct_error:
1186                 spin_lock(&sctx->stat_lock);
1187                 sctx->stat.uncorrectable_errors++;
1188                 spin_unlock(&sctx->stat_lock);
1189                 btrfs_err_rl_in_rcu(fs_info,
1190                         "unable to fixup (regular) error at logical %llu on dev %s",
1191                         logical, rcu_str_deref(dev->name));
1192         }
1193
1194 out:
1195         if (sblocks_for_recheck) {
1196                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1197                      mirror_index++) {
1198                         struct scrub_block *sblock = sblocks_for_recheck +
1199                                                      mirror_index;
1200                         struct scrub_recover *recover;
1201                         int page_index;
1202
1203                         for (page_index = 0; page_index < sblock->page_count;
1204                              page_index++) {
1205                                 sblock->pagev[page_index]->sblock = NULL;
1206                                 recover = sblock->pagev[page_index]->recover;
1207                                 if (recover) {
1208                                         scrub_put_recover(fs_info, recover);
1209                                         sblock->pagev[page_index]->recover =
1210                                                                         NULL;
1211                                 }
1212                                 scrub_page_put(sblock->pagev[page_index]);
1213                         }
1214                 }
1215                 kfree(sblocks_for_recheck);
1216         }
1217
1218         ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
1219         memalloc_nofs_restore(nofs_flag);
1220         if (ret < 0)
1221                 return ret;
1222         return 0;
1223 }
1224
1225 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1226 {
1227         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1228                 return 2;
1229         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1230                 return 3;
1231         else
1232                 return (int)bbio->num_stripes;
1233 }
1234
1235 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1236                                                  u64 *raid_map,
1237                                                  u64 mapped_length,
1238                                                  int nstripes, int mirror,
1239                                                  int *stripe_index,
1240                                                  u64 *stripe_offset)
1241 {
1242         int i;
1243
1244         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1245                 /* RAID5/6 */
1246                 for (i = 0; i < nstripes; i++) {
1247                         if (raid_map[i] == RAID6_Q_STRIPE ||
1248                             raid_map[i] == RAID5_P_STRIPE)
1249                                 continue;
1250
1251                         if (logical >= raid_map[i] &&
1252                             logical < raid_map[i] + mapped_length)
1253                                 break;
1254                 }
1255
1256                 *stripe_index = i;
1257                 *stripe_offset = logical - raid_map[i];
1258         } else {
1259                 /* The other RAID type */
1260                 *stripe_index = mirror;
1261                 *stripe_offset = 0;
1262         }
1263 }
1264
1265 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1266                                      struct scrub_block *sblocks_for_recheck)
1267 {
1268         struct scrub_ctx *sctx = original_sblock->sctx;
1269         struct btrfs_fs_info *fs_info = sctx->fs_info;
1270         u64 length = original_sblock->page_count * PAGE_SIZE;
1271         u64 logical = original_sblock->pagev[0]->logical;
1272         u64 generation = original_sblock->pagev[0]->generation;
1273         u64 flags = original_sblock->pagev[0]->flags;
1274         u64 have_csum = original_sblock->pagev[0]->have_csum;
1275         struct scrub_recover *recover;
1276         struct btrfs_bio *bbio;
1277         u64 sublen;
1278         u64 mapped_length;
1279         u64 stripe_offset;
1280         int stripe_index;
1281         int page_index = 0;
1282         int mirror_index;
1283         int nmirrors;
1284         int ret;
1285
1286         /*
1287          * note: the two members refs and outstanding_pages
1288          * are not used (and not set) in the blocks that are used for
1289          * the recheck procedure
1290          */
1291
1292         while (length > 0) {
1293                 sublen = min_t(u64, length, PAGE_SIZE);
1294                 mapped_length = sublen;
1295                 bbio = NULL;
1296
1297                 /*
1298                  * with a length of PAGE_SIZE, each returned stripe
1299                  * represents one mirror
1300                  */
1301                 btrfs_bio_counter_inc_blocked(fs_info);
1302                 ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
1303                                 logical, &mapped_length, &bbio);
1304                 if (ret || !bbio || mapped_length < sublen) {
1305                         btrfs_put_bbio(bbio);
1306                         btrfs_bio_counter_dec(fs_info);
1307                         return -EIO;
1308                 }
1309
1310                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1311                 if (!recover) {
1312                         btrfs_put_bbio(bbio);
1313                         btrfs_bio_counter_dec(fs_info);
1314                         return -ENOMEM;
1315                 }
1316
1317                 refcount_set(&recover->refs, 1);
1318                 recover->bbio = bbio;
1319                 recover->map_length = mapped_length;
1320
1321                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1322
1323                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1324
1325                 for (mirror_index = 0; mirror_index < nmirrors;
1326                      mirror_index++) {
1327                         struct scrub_block *sblock;
1328                         struct scrub_page *page;
1329
1330                         sblock = sblocks_for_recheck + mirror_index;
1331                         sblock->sctx = sctx;
1332
1333                         page = kzalloc(sizeof(*page), GFP_NOFS);
1334                         if (!page) {
1335 leave_nomem:
1336                                 spin_lock(&sctx->stat_lock);
1337                                 sctx->stat.malloc_errors++;
1338                                 spin_unlock(&sctx->stat_lock);
1339                                 scrub_put_recover(fs_info, recover);
1340                                 return -ENOMEM;
1341                         }
1342                         scrub_page_get(page);
1343                         sblock->pagev[page_index] = page;
1344                         page->sblock = sblock;
1345                         page->flags = flags;
1346                         page->generation = generation;
1347                         page->logical = logical;
1348                         page->have_csum = have_csum;
1349                         if (have_csum)
1350                                 memcpy(page->csum,
1351                                        original_sblock->pagev[0]->csum,
1352                                        sctx->csum_size);
1353
1354                         scrub_stripe_index_and_offset(logical,
1355                                                       bbio->map_type,
1356                                                       bbio->raid_map,
1357                                                       mapped_length,
1358                                                       bbio->num_stripes -
1359                                                       bbio->num_tgtdevs,
1360                                                       mirror_index,
1361                                                       &stripe_index,
1362                                                       &stripe_offset);
1363                         page->physical = bbio->stripes[stripe_index].physical +
1364                                          stripe_offset;
1365                         page->dev = bbio->stripes[stripe_index].dev;
1366
1367                         BUG_ON(page_index >= original_sblock->page_count);
1368                         page->physical_for_dev_replace =
1369                                 original_sblock->pagev[page_index]->
1370                                 physical_for_dev_replace;
1371                         /* for missing devices, dev->bdev is NULL */
1372                         page->mirror_num = mirror_index + 1;
1373                         sblock->page_count++;
1374                         page->page = alloc_page(GFP_NOFS);
1375                         if (!page->page)
1376                                 goto leave_nomem;
1377
1378                         scrub_get_recover(recover);
1379                         page->recover = recover;
1380                 }
1381                 scrub_put_recover(fs_info, recover);
1382                 length -= sublen;
1383                 logical += sublen;
1384                 page_index++;
1385         }
1386
1387         return 0;
1388 }
1389
1390 static void scrub_bio_wait_endio(struct bio *bio)
1391 {
1392         complete(bio->bi_private);
1393 }
1394
1395 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1396                                         struct bio *bio,
1397                                         struct scrub_page *page)
1398 {
1399         DECLARE_COMPLETION_ONSTACK(done);
1400         int ret;
1401         int mirror_num;
1402
1403         bio->bi_iter.bi_sector = page->logical >> 9;
1404         bio->bi_private = &done;
1405         bio->bi_end_io = scrub_bio_wait_endio;
1406
1407         mirror_num = page->sblock->pagev[0]->mirror_num;
1408         ret = raid56_parity_recover(fs_info, bio, page->recover->bbio,
1409                                     page->recover->map_length,
1410                                     mirror_num, 0);
1411         if (ret)
1412                 return ret;
1413
1414         wait_for_completion_io(&done);
1415         return blk_status_to_errno(bio->bi_status);
1416 }
1417
1418 static void scrub_recheck_block_on_raid56(struct btrfs_fs_info *fs_info,
1419                                           struct scrub_block *sblock)
1420 {
1421         struct scrub_page *first_page = sblock->pagev[0];
1422         struct bio *bio;
1423         int page_num;
1424
1425         /* All pages in sblock belong to the same stripe on the same device. */
1426         ASSERT(first_page->dev);
1427         if (!first_page->dev->bdev)
1428                 goto out;
1429
1430         bio = btrfs_io_bio_alloc(BIO_MAX_PAGES);
1431         bio_set_dev(bio, first_page->dev->bdev);
1432
1433         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1434                 struct scrub_page *page = sblock->pagev[page_num];
1435
1436                 WARN_ON(!page->page);
1437                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1438         }
1439
1440         if (scrub_submit_raid56_bio_wait(fs_info, bio, first_page)) {
1441                 bio_put(bio);
1442                 goto out;
1443         }
1444
1445         bio_put(bio);
1446
1447         scrub_recheck_block_checksum(sblock);
1448
1449         return;
1450 out:
1451         for (page_num = 0; page_num < sblock->page_count; page_num++)
1452                 sblock->pagev[page_num]->io_error = 1;
1453
1454         sblock->no_io_error_seen = 0;
1455 }
1456
1457 /*
1458  * this function will check the on disk data for checksum errors, header
1459  * errors and read I/O errors. If any I/O errors happen, the exact pages
1460  * which are errored are marked as being bad. The goal is to enable scrub
1461  * to take those pages that are not errored from all the mirrors so that
1462  * the pages that are errored in the just handled mirror can be repaired.
1463  */
1464 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1465                                 struct scrub_block *sblock,
1466                                 int retry_failed_mirror)
1467 {
1468         int page_num;
1469
1470         sblock->no_io_error_seen = 1;
1471
1472         /* short cut for raid56 */
1473         if (!retry_failed_mirror && scrub_is_page_on_raid56(sblock->pagev[0]))
1474                 return scrub_recheck_block_on_raid56(fs_info, sblock);
1475
1476         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1477                 struct bio *bio;
1478                 struct scrub_page *page = sblock->pagev[page_num];
1479
1480                 if (page->dev->bdev == NULL) {
1481                         page->io_error = 1;
1482                         sblock->no_io_error_seen = 0;
1483                         continue;
1484                 }
1485
1486                 WARN_ON(!page->page);
1487                 bio = btrfs_io_bio_alloc(1);
1488                 bio_set_dev(bio, page->dev->bdev);
1489
1490                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1491                 bio->bi_iter.bi_sector = page->physical >> 9;
1492                 bio->bi_opf = REQ_OP_READ;
1493
1494                 if (btrfsic_submit_bio_wait(bio)) {
1495                         page->io_error = 1;
1496                         sblock->no_io_error_seen = 0;
1497                 }
1498
1499                 bio_put(bio);
1500         }
1501
1502         if (sblock->no_io_error_seen)
1503                 scrub_recheck_block_checksum(sblock);
1504 }
1505
1506 static inline int scrub_check_fsid(u8 fsid[],
1507                                    struct scrub_page *spage)
1508 {
1509         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1510         int ret;
1511
1512         ret = memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1513         return !ret;
1514 }
1515
1516 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1517 {
1518         sblock->header_error = 0;
1519         sblock->checksum_error = 0;
1520         sblock->generation_error = 0;
1521
1522         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1523                 scrub_checksum_data(sblock);
1524         else
1525                 scrub_checksum_tree_block(sblock);
1526 }
1527
1528 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1529                                              struct scrub_block *sblock_good)
1530 {
1531         int page_num;
1532         int ret = 0;
1533
1534         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1535                 int ret_sub;
1536
1537                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1538                                                            sblock_good,
1539                                                            page_num, 1);
1540                 if (ret_sub)
1541                         ret = ret_sub;
1542         }
1543
1544         return ret;
1545 }
1546
1547 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1548                                             struct scrub_block *sblock_good,
1549                                             int page_num, int force_write)
1550 {
1551         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1552         struct scrub_page *page_good = sblock_good->pagev[page_num];
1553         struct btrfs_fs_info *fs_info = sblock_bad->sctx->fs_info;
1554
1555         BUG_ON(page_bad->page == NULL);
1556         BUG_ON(page_good->page == NULL);
1557         if (force_write || sblock_bad->header_error ||
1558             sblock_bad->checksum_error || page_bad->io_error) {
1559                 struct bio *bio;
1560                 int ret;
1561
1562                 if (!page_bad->dev->bdev) {
1563                         btrfs_warn_rl(fs_info,
1564                                 "scrub_repair_page_from_good_copy(bdev == NULL) is unexpected");
1565                         return -EIO;
1566                 }
1567
1568                 bio = btrfs_io_bio_alloc(1);
1569                 bio_set_dev(bio, page_bad->dev->bdev);
1570                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1571                 bio->bi_opf = REQ_OP_WRITE;
1572
1573                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1574                 if (PAGE_SIZE != ret) {
1575                         bio_put(bio);
1576                         return -EIO;
1577                 }
1578
1579                 if (btrfsic_submit_bio_wait(bio)) {
1580                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1581                                 BTRFS_DEV_STAT_WRITE_ERRS);
1582                         atomic64_inc(&fs_info->dev_replace.num_write_errors);
1583                         bio_put(bio);
1584                         return -EIO;
1585                 }
1586                 bio_put(bio);
1587         }
1588
1589         return 0;
1590 }
1591
1592 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1593 {
1594         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
1595         int page_num;
1596
1597         /*
1598          * This block is used for the check of the parity on the source device,
1599          * so the data needn't be written into the destination device.
1600          */
1601         if (sblock->sparity)
1602                 return;
1603
1604         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1605                 int ret;
1606
1607                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1608                 if (ret)
1609                         atomic64_inc(&fs_info->dev_replace.num_write_errors);
1610         }
1611 }
1612
1613 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1614                                            int page_num)
1615 {
1616         struct scrub_page *spage = sblock->pagev[page_num];
1617
1618         BUG_ON(spage->page == NULL);
1619         if (spage->io_error) {
1620                 void *mapped_buffer = kmap_atomic(spage->page);
1621
1622                 clear_page(mapped_buffer);
1623                 flush_dcache_page(spage->page);
1624                 kunmap_atomic(mapped_buffer);
1625         }
1626         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1627 }
1628
1629 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1630                                     struct scrub_page *spage)
1631 {
1632         struct scrub_bio *sbio;
1633         int ret;
1634
1635         mutex_lock(&sctx->wr_lock);
1636 again:
1637         if (!sctx->wr_curr_bio) {
1638                 sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
1639                                               GFP_KERNEL);
1640                 if (!sctx->wr_curr_bio) {
1641                         mutex_unlock(&sctx->wr_lock);
1642                         return -ENOMEM;
1643                 }
1644                 sctx->wr_curr_bio->sctx = sctx;
1645                 sctx->wr_curr_bio->page_count = 0;
1646         }
1647         sbio = sctx->wr_curr_bio;
1648         if (sbio->page_count == 0) {
1649                 struct bio *bio;
1650
1651                 sbio->physical = spage->physical_for_dev_replace;
1652                 sbio->logical = spage->logical;
1653                 sbio->dev = sctx->wr_tgtdev;
1654                 bio = sbio->bio;
1655                 if (!bio) {
1656                         bio = btrfs_io_bio_alloc(sctx->pages_per_wr_bio);
1657                         sbio->bio = bio;
1658                 }
1659
1660                 bio->bi_private = sbio;
1661                 bio->bi_end_io = scrub_wr_bio_end_io;
1662                 bio_set_dev(bio, sbio->dev->bdev);
1663                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1664                 bio->bi_opf = REQ_OP_WRITE;
1665                 sbio->status = 0;
1666         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1667                    spage->physical_for_dev_replace ||
1668                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1669                    spage->logical) {
1670                 scrub_wr_submit(sctx);
1671                 goto again;
1672         }
1673
1674         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1675         if (ret != PAGE_SIZE) {
1676                 if (sbio->page_count < 1) {
1677                         bio_put(sbio->bio);
1678                         sbio->bio = NULL;
1679                         mutex_unlock(&sctx->wr_lock);
1680                         return -EIO;
1681                 }
1682                 scrub_wr_submit(sctx);
1683                 goto again;
1684         }
1685
1686         sbio->pagev[sbio->page_count] = spage;
1687         scrub_page_get(spage);
1688         sbio->page_count++;
1689         if (sbio->page_count == sctx->pages_per_wr_bio)
1690                 scrub_wr_submit(sctx);
1691         mutex_unlock(&sctx->wr_lock);
1692
1693         return 0;
1694 }
1695
1696 static void scrub_wr_submit(struct scrub_ctx *sctx)
1697 {
1698         struct scrub_bio *sbio;
1699
1700         if (!sctx->wr_curr_bio)
1701                 return;
1702
1703         sbio = sctx->wr_curr_bio;
1704         sctx->wr_curr_bio = NULL;
1705         WARN_ON(!sbio->bio->bi_disk);
1706         scrub_pending_bio_inc(sctx);
1707         /* process all writes in a single worker thread. Then the block layer
1708          * orders the requests before sending them to the driver which
1709          * doubled the write performance on spinning disks when measured
1710          * with Linux 3.5 */
1711         btrfsic_submit_bio(sbio->bio);
1712 }
1713
1714 static void scrub_wr_bio_end_io(struct bio *bio)
1715 {
1716         struct scrub_bio *sbio = bio->bi_private;
1717         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
1718
1719         sbio->status = bio->bi_status;
1720         sbio->bio = bio;
1721
1722         btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
1723                          scrub_wr_bio_end_io_worker, NULL, NULL);
1724         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1725 }
1726
1727 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1728 {
1729         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1730         struct scrub_ctx *sctx = sbio->sctx;
1731         int i;
1732
1733         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1734         if (sbio->status) {
1735                 struct btrfs_dev_replace *dev_replace =
1736                         &sbio->sctx->fs_info->dev_replace;
1737
1738                 for (i = 0; i < sbio->page_count; i++) {
1739                         struct scrub_page *spage = sbio->pagev[i];
1740
1741                         spage->io_error = 1;
1742                         atomic64_inc(&dev_replace->num_write_errors);
1743                 }
1744         }
1745
1746         for (i = 0; i < sbio->page_count; i++)
1747                 scrub_page_put(sbio->pagev[i]);
1748
1749         bio_put(sbio->bio);
1750         kfree(sbio);
1751         scrub_pending_bio_dec(sctx);
1752 }
1753
1754 static int scrub_checksum(struct scrub_block *sblock)
1755 {
1756         u64 flags;
1757         int ret;
1758
1759         /*
1760          * No need to initialize these stats currently,
1761          * because this function only use return value
1762          * instead of these stats value.
1763          *
1764          * Todo:
1765          * always use stats
1766          */
1767         sblock->header_error = 0;
1768         sblock->generation_error = 0;
1769         sblock->checksum_error = 0;
1770
1771         WARN_ON(sblock->page_count < 1);
1772         flags = sblock->pagev[0]->flags;
1773         ret = 0;
1774         if (flags & BTRFS_EXTENT_FLAG_DATA)
1775                 ret = scrub_checksum_data(sblock);
1776         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1777                 ret = scrub_checksum_tree_block(sblock);
1778         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1779                 (void)scrub_checksum_super(sblock);
1780         else
1781                 WARN_ON(1);
1782         if (ret)
1783                 scrub_handle_errored_block(sblock);
1784
1785         return ret;
1786 }
1787
1788 static int scrub_checksum_data(struct scrub_block *sblock)
1789 {
1790         struct scrub_ctx *sctx = sblock->sctx;
1791         struct btrfs_fs_info *fs_info = sctx->fs_info;
1792         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1793         u8 csum[BTRFS_CSUM_SIZE];
1794         u8 *on_disk_csum;
1795         struct page *page;
1796         void *buffer;
1797         u64 len;
1798         int index;
1799
1800         BUG_ON(sblock->page_count < 1);
1801         if (!sblock->pagev[0]->have_csum)
1802                 return 0;
1803
1804         shash->tfm = fs_info->csum_shash;
1805         crypto_shash_init(shash);
1806
1807         on_disk_csum = sblock->pagev[0]->csum;
1808         page = sblock->pagev[0]->page;
1809         buffer = kmap_atomic(page);
1810
1811         len = sctx->fs_info->sectorsize;
1812         index = 0;
1813         for (;;) {
1814                 u64 l = min_t(u64, len, PAGE_SIZE);
1815
1816                 crypto_shash_update(shash, buffer, l);
1817                 kunmap_atomic(buffer);
1818                 len -= l;
1819                 if (len == 0)
1820                         break;
1821                 index++;
1822                 BUG_ON(index >= sblock->page_count);
1823                 BUG_ON(!sblock->pagev[index]->page);
1824                 page = sblock->pagev[index]->page;
1825                 buffer = kmap_atomic(page);
1826         }
1827
1828         crypto_shash_final(shash, csum);
1829         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1830                 sblock->checksum_error = 1;
1831
1832         return sblock->checksum_error;
1833 }
1834
1835 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1836 {
1837         struct scrub_ctx *sctx = sblock->sctx;
1838         struct btrfs_header *h;
1839         struct btrfs_fs_info *fs_info = sctx->fs_info;
1840         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1841         u8 calculated_csum[BTRFS_CSUM_SIZE];
1842         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1843         struct page *page;
1844         void *mapped_buffer;
1845         u64 mapped_size;
1846         void *p;
1847         u64 len;
1848         int index;
1849
1850         shash->tfm = fs_info->csum_shash;
1851         crypto_shash_init(shash);
1852
1853         BUG_ON(sblock->page_count < 1);
1854         page = sblock->pagev[0]->page;
1855         mapped_buffer = kmap_atomic(page);
1856         h = (struct btrfs_header *)mapped_buffer;
1857         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1858
1859         /*
1860          * we don't use the getter functions here, as we
1861          * a) don't have an extent buffer and
1862          * b) the page is already kmapped
1863          */
1864         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1865                 sblock->header_error = 1;
1866
1867         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
1868                 sblock->header_error = 1;
1869                 sblock->generation_error = 1;
1870         }
1871
1872         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
1873                 sblock->header_error = 1;
1874
1875         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1876                    BTRFS_UUID_SIZE))
1877                 sblock->header_error = 1;
1878
1879         len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
1880         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1881         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1882         index = 0;
1883         for (;;) {
1884                 u64 l = min_t(u64, len, mapped_size);
1885
1886                 crypto_shash_update(shash, p, l);
1887                 kunmap_atomic(mapped_buffer);
1888                 len -= l;
1889                 if (len == 0)
1890                         break;
1891                 index++;
1892                 BUG_ON(index >= sblock->page_count);
1893                 BUG_ON(!sblock->pagev[index]->page);
1894                 page = sblock->pagev[index]->page;
1895                 mapped_buffer = kmap_atomic(page);
1896                 mapped_size = PAGE_SIZE;
1897                 p = mapped_buffer;
1898         }
1899
1900         crypto_shash_final(shash, calculated_csum);
1901         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1902                 sblock->checksum_error = 1;
1903
1904         return sblock->header_error || sblock->checksum_error;
1905 }
1906
1907 static int scrub_checksum_super(struct scrub_block *sblock)
1908 {
1909         struct btrfs_super_block *s;
1910         struct scrub_ctx *sctx = sblock->sctx;
1911         struct btrfs_fs_info *fs_info = sctx->fs_info;
1912         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1913         u8 calculated_csum[BTRFS_CSUM_SIZE];
1914         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1915         struct page *page;
1916         void *mapped_buffer;
1917         u64 mapped_size;
1918         void *p;
1919         int fail_gen = 0;
1920         int fail_cor = 0;
1921         u64 len;
1922         int index;
1923
1924         shash->tfm = fs_info->csum_shash;
1925         crypto_shash_init(shash);
1926
1927         BUG_ON(sblock->page_count < 1);
1928         page = sblock->pagev[0]->page;
1929         mapped_buffer = kmap_atomic(page);
1930         s = (struct btrfs_super_block *)mapped_buffer;
1931         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1932
1933         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1934                 ++fail_cor;
1935
1936         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1937                 ++fail_gen;
1938
1939         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1940                 ++fail_cor;
1941
1942         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1943         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1944         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1945         index = 0;
1946         for (;;) {
1947                 u64 l = min_t(u64, len, mapped_size);
1948
1949                 crypto_shash_update(shash, p, l);
1950                 kunmap_atomic(mapped_buffer);
1951                 len -= l;
1952                 if (len == 0)
1953                         break;
1954                 index++;
1955                 BUG_ON(index >= sblock->page_count);
1956                 BUG_ON(!sblock->pagev[index]->page);
1957                 page = sblock->pagev[index]->page;
1958                 mapped_buffer = kmap_atomic(page);
1959                 mapped_size = PAGE_SIZE;
1960                 p = mapped_buffer;
1961         }
1962
1963         crypto_shash_final(shash, calculated_csum);
1964         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1965                 ++fail_cor;
1966
1967         if (fail_cor + fail_gen) {
1968                 /*
1969                  * if we find an error in a super block, we just report it.
1970                  * They will get written with the next transaction commit
1971                  * anyway
1972                  */
1973                 spin_lock(&sctx->stat_lock);
1974                 ++sctx->stat.super_errors;
1975                 spin_unlock(&sctx->stat_lock);
1976                 if (fail_cor)
1977                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1978                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1979                 else
1980                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1981                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1982         }
1983
1984         return fail_cor + fail_gen;
1985 }
1986
1987 static void scrub_block_get(struct scrub_block *sblock)
1988 {
1989         refcount_inc(&sblock->refs);
1990 }
1991
1992 static void scrub_block_put(struct scrub_block *sblock)
1993 {
1994         if (refcount_dec_and_test(&sblock->refs)) {
1995                 int i;
1996
1997                 if (sblock->sparity)
1998                         scrub_parity_put(sblock->sparity);
1999
2000                 for (i = 0; i < sblock->page_count; i++)
2001                         scrub_page_put(sblock->pagev[i]);
2002                 kfree(sblock);
2003         }
2004 }
2005
2006 static void scrub_page_get(struct scrub_page *spage)
2007 {
2008         atomic_inc(&spage->refs);
2009 }
2010
2011 static void scrub_page_put(struct scrub_page *spage)
2012 {
2013         if (atomic_dec_and_test(&spage->refs)) {
2014                 if (spage->page)
2015                         __free_page(spage->page);
2016                 kfree(spage);
2017         }
2018 }
2019
2020 static void scrub_submit(struct scrub_ctx *sctx)
2021 {
2022         struct scrub_bio *sbio;
2023
2024         if (sctx->curr == -1)
2025                 return;
2026
2027         sbio = sctx->bios[sctx->curr];
2028         sctx->curr = -1;
2029         scrub_pending_bio_inc(sctx);
2030         btrfsic_submit_bio(sbio->bio);
2031 }
2032
2033 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2034                                     struct scrub_page *spage)
2035 {
2036         struct scrub_block *sblock = spage->sblock;
2037         struct scrub_bio *sbio;
2038         int ret;
2039
2040 again:
2041         /*
2042          * grab a fresh bio or wait for one to become available
2043          */
2044         while (sctx->curr == -1) {
2045                 spin_lock(&sctx->list_lock);
2046                 sctx->curr = sctx->first_free;
2047                 if (sctx->curr != -1) {
2048                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2049                         sctx->bios[sctx->curr]->next_free = -1;
2050                         sctx->bios[sctx->curr]->page_count = 0;
2051                         spin_unlock(&sctx->list_lock);
2052                 } else {
2053                         spin_unlock(&sctx->list_lock);
2054                         wait_event(sctx->list_wait, sctx->first_free != -1);
2055                 }
2056         }
2057         sbio = sctx->bios[sctx->curr];
2058         if (sbio->page_count == 0) {
2059                 struct bio *bio;
2060
2061                 sbio->physical = spage->physical;
2062                 sbio->logical = spage->logical;
2063                 sbio->dev = spage->dev;
2064                 bio = sbio->bio;
2065                 if (!bio) {
2066                         bio = btrfs_io_bio_alloc(sctx->pages_per_rd_bio);
2067                         sbio->bio = bio;
2068                 }
2069
2070                 bio->bi_private = sbio;
2071                 bio->bi_end_io = scrub_bio_end_io;
2072                 bio_set_dev(bio, sbio->dev->bdev);
2073                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2074                 bio->bi_opf = REQ_OP_READ;
2075                 sbio->status = 0;
2076         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2077                    spage->physical ||
2078                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2079                    spage->logical ||
2080                    sbio->dev != spage->dev) {
2081                 scrub_submit(sctx);
2082                 goto again;
2083         }
2084
2085         sbio->pagev[sbio->page_count] = spage;
2086         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2087         if (ret != PAGE_SIZE) {
2088                 if (sbio->page_count < 1) {
2089                         bio_put(sbio->bio);
2090                         sbio->bio = NULL;
2091                         return -EIO;
2092                 }
2093                 scrub_submit(sctx);
2094                 goto again;
2095         }
2096
2097         scrub_block_get(sblock); /* one for the page added to the bio */
2098         atomic_inc(&sblock->outstanding_pages);
2099         sbio->page_count++;
2100         if (sbio->page_count == sctx->pages_per_rd_bio)
2101                 scrub_submit(sctx);
2102
2103         return 0;
2104 }
2105
2106 static void scrub_missing_raid56_end_io(struct bio *bio)
2107 {
2108         struct scrub_block *sblock = bio->bi_private;
2109         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
2110
2111         if (bio->bi_status)
2112                 sblock->no_io_error_seen = 0;
2113
2114         bio_put(bio);
2115
2116         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2117 }
2118
2119 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2120 {
2121         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2122         struct scrub_ctx *sctx = sblock->sctx;
2123         struct btrfs_fs_info *fs_info = sctx->fs_info;
2124         u64 logical;
2125         struct btrfs_device *dev;
2126
2127         logical = sblock->pagev[0]->logical;
2128         dev = sblock->pagev[0]->dev;
2129
2130         if (sblock->no_io_error_seen)
2131                 scrub_recheck_block_checksum(sblock);
2132
2133         if (!sblock->no_io_error_seen) {
2134                 spin_lock(&sctx->stat_lock);
2135                 sctx->stat.read_errors++;
2136                 spin_unlock(&sctx->stat_lock);
2137                 btrfs_err_rl_in_rcu(fs_info,
2138                         "IO error rebuilding logical %llu for dev %s",
2139                         logical, rcu_str_deref(dev->name));
2140         } else if (sblock->header_error || sblock->checksum_error) {
2141                 spin_lock(&sctx->stat_lock);
2142                 sctx->stat.uncorrectable_errors++;
2143                 spin_unlock(&sctx->stat_lock);
2144                 btrfs_err_rl_in_rcu(fs_info,
2145                         "failed to rebuild valid logical %llu for dev %s",
2146                         logical, rcu_str_deref(dev->name));
2147         } else {
2148                 scrub_write_block_to_dev_replace(sblock);
2149         }
2150
2151         scrub_block_put(sblock);
2152
2153         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2154                 mutex_lock(&sctx->wr_lock);
2155                 scrub_wr_submit(sctx);
2156                 mutex_unlock(&sctx->wr_lock);
2157         }
2158
2159         scrub_pending_bio_dec(sctx);
2160 }
2161
2162 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2163 {
2164         struct scrub_ctx *sctx = sblock->sctx;
2165         struct btrfs_fs_info *fs_info = sctx->fs_info;
2166         u64 length = sblock->page_count * PAGE_SIZE;
2167         u64 logical = sblock->pagev[0]->logical;
2168         struct btrfs_bio *bbio = NULL;
2169         struct bio *bio;
2170         struct btrfs_raid_bio *rbio;
2171         int ret;
2172         int i;
2173
2174         btrfs_bio_counter_inc_blocked(fs_info);
2175         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
2176                         &length, &bbio);
2177         if (ret || !bbio || !bbio->raid_map)
2178                 goto bbio_out;
2179
2180         if (WARN_ON(!sctx->is_dev_replace ||
2181                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2182                 /*
2183                  * We shouldn't be scrubbing a missing device. Even for dev
2184                  * replace, we should only get here for RAID 5/6. We either
2185                  * managed to mount something with no mirrors remaining or
2186                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2187                  */
2188                 goto bbio_out;
2189         }
2190
2191         bio = btrfs_io_bio_alloc(0);
2192         bio->bi_iter.bi_sector = logical >> 9;
2193         bio->bi_private = sblock;
2194         bio->bi_end_io = scrub_missing_raid56_end_io;
2195
2196         rbio = raid56_alloc_missing_rbio(fs_info, bio, bbio, length);
2197         if (!rbio)
2198                 goto rbio_out;
2199
2200         for (i = 0; i < sblock->page_count; i++) {
2201                 struct scrub_page *spage = sblock->pagev[i];
2202
2203                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2204         }
2205
2206         btrfs_init_work(&sblock->work, btrfs_scrub_helper,
2207                         scrub_missing_raid56_worker, NULL, NULL);
2208         scrub_block_get(sblock);
2209         scrub_pending_bio_inc(sctx);
2210         raid56_submit_missing_rbio(rbio);
2211         return;
2212
2213 rbio_out:
2214         bio_put(bio);
2215 bbio_out:
2216         btrfs_bio_counter_dec(fs_info);
2217         btrfs_put_bbio(bbio);
2218         spin_lock(&sctx->stat_lock);
2219         sctx->stat.malloc_errors++;
2220         spin_unlock(&sctx->stat_lock);
2221 }
2222
2223 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2224                        u64 physical, struct btrfs_device *dev, u64 flags,
2225                        u64 gen, int mirror_num, u8 *csum, int force,
2226                        u64 physical_for_dev_replace)
2227 {
2228         struct scrub_block *sblock;
2229         int index;
2230
2231         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2232         if (!sblock) {
2233                 spin_lock(&sctx->stat_lock);
2234                 sctx->stat.malloc_errors++;
2235                 spin_unlock(&sctx->stat_lock);
2236                 return -ENOMEM;
2237         }
2238
2239         /* one ref inside this function, plus one for each page added to
2240          * a bio later on */
2241         refcount_set(&sblock->refs, 1);
2242         sblock->sctx = sctx;
2243         sblock->no_io_error_seen = 1;
2244
2245         for (index = 0; len > 0; index++) {
2246                 struct scrub_page *spage;
2247                 u64 l = min_t(u64, len, PAGE_SIZE);
2248
2249                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2250                 if (!spage) {
2251 leave_nomem:
2252                         spin_lock(&sctx->stat_lock);
2253                         sctx->stat.malloc_errors++;
2254                         spin_unlock(&sctx->stat_lock);
2255                         scrub_block_put(sblock);
2256                         return -ENOMEM;
2257                 }
2258                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2259                 scrub_page_get(spage);
2260                 sblock->pagev[index] = spage;
2261                 spage->sblock = sblock;
2262                 spage->dev = dev;
2263                 spage->flags = flags;
2264                 spage->generation = gen;
2265                 spage->logical = logical;
2266                 spage->physical = physical;
2267                 spage->physical_for_dev_replace = physical_for_dev_replace;
2268                 spage->mirror_num = mirror_num;
2269                 if (csum) {
2270                         spage->have_csum = 1;
2271                         memcpy(spage->csum, csum, sctx->csum_size);
2272                 } else {
2273                         spage->have_csum = 0;
2274                 }
2275                 sblock->page_count++;
2276                 spage->page = alloc_page(GFP_KERNEL);
2277                 if (!spage->page)
2278                         goto leave_nomem;
2279                 len -= l;
2280                 logical += l;
2281                 physical += l;
2282                 physical_for_dev_replace += l;
2283         }
2284
2285         WARN_ON(sblock->page_count == 0);
2286         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2287                 /*
2288                  * This case should only be hit for RAID 5/6 device replace. See
2289                  * the comment in scrub_missing_raid56_pages() for details.
2290                  */
2291                 scrub_missing_raid56_pages(sblock);
2292         } else {
2293                 for (index = 0; index < sblock->page_count; index++) {
2294                         struct scrub_page *spage = sblock->pagev[index];
2295                         int ret;
2296
2297                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2298                         if (ret) {
2299                                 scrub_block_put(sblock);
2300                                 return ret;
2301                         }
2302                 }
2303
2304                 if (force)
2305                         scrub_submit(sctx);
2306         }
2307
2308         /* last one frees, either here or in bio completion for last page */
2309         scrub_block_put(sblock);
2310         return 0;
2311 }
2312
2313 static void scrub_bio_end_io(struct bio *bio)
2314 {
2315         struct scrub_bio *sbio = bio->bi_private;
2316         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
2317
2318         sbio->status = bio->bi_status;
2319         sbio->bio = bio;
2320
2321         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2322 }
2323
2324 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2325 {
2326         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2327         struct scrub_ctx *sctx = sbio->sctx;
2328         int i;
2329
2330         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2331         if (sbio->status) {
2332                 for (i = 0; i < sbio->page_count; i++) {
2333                         struct scrub_page *spage = sbio->pagev[i];
2334
2335                         spage->io_error = 1;
2336                         spage->sblock->no_io_error_seen = 0;
2337                 }
2338         }
2339
2340         /* now complete the scrub_block items that have all pages completed */
2341         for (i = 0; i < sbio->page_count; i++) {
2342                 struct scrub_page *spage = sbio->pagev[i];
2343                 struct scrub_block *sblock = spage->sblock;
2344
2345                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2346                         scrub_block_complete(sblock);
2347                 scrub_block_put(sblock);
2348         }
2349
2350         bio_put(sbio->bio);
2351         sbio->bio = NULL;
2352         spin_lock(&sctx->list_lock);
2353         sbio->next_free = sctx->first_free;
2354         sctx->first_free = sbio->index;
2355         spin_unlock(&sctx->list_lock);
2356
2357         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2358                 mutex_lock(&sctx->wr_lock);
2359                 scrub_wr_submit(sctx);
2360                 mutex_unlock(&sctx->wr_lock);
2361         }
2362
2363         scrub_pending_bio_dec(sctx);
2364 }
2365
2366 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2367                                        unsigned long *bitmap,
2368                                        u64 start, u64 len)
2369 {
2370         u64 offset;
2371         u64 nsectors64;
2372         u32 nsectors;
2373         int sectorsize = sparity->sctx->fs_info->sectorsize;
2374
2375         if (len >= sparity->stripe_len) {
2376                 bitmap_set(bitmap, 0, sparity->nsectors);
2377                 return;
2378         }
2379
2380         start -= sparity->logic_start;
2381         start = div64_u64_rem(start, sparity->stripe_len, &offset);
2382         offset = div_u64(offset, sectorsize);
2383         nsectors64 = div_u64(len, sectorsize);
2384
2385         ASSERT(nsectors64 < UINT_MAX);
2386         nsectors = (u32)nsectors64;
2387
2388         if (offset + nsectors <= sparity->nsectors) {
2389                 bitmap_set(bitmap, offset, nsectors);
2390                 return;
2391         }
2392
2393         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2394         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2395 }
2396
2397 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2398                                                    u64 start, u64 len)
2399 {
2400         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2401 }
2402
2403 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2404                                                   u64 start, u64 len)
2405 {
2406         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2407 }
2408
2409 static void scrub_block_complete(struct scrub_block *sblock)
2410 {
2411         int corrupted = 0;
2412
2413         if (!sblock->no_io_error_seen) {
2414                 corrupted = 1;
2415                 scrub_handle_errored_block(sblock);
2416         } else {
2417                 /*
2418                  * if has checksum error, write via repair mechanism in
2419                  * dev replace case, otherwise write here in dev replace
2420                  * case.
2421                  */
2422                 corrupted = scrub_checksum(sblock);
2423                 if (!corrupted && sblock->sctx->is_dev_replace)
2424                         scrub_write_block_to_dev_replace(sblock);
2425         }
2426
2427         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2428                 u64 start = sblock->pagev[0]->logical;
2429                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2430                           PAGE_SIZE;
2431
2432                 scrub_parity_mark_sectors_error(sblock->sparity,
2433                                                 start, end - start);
2434         }
2435 }
2436
2437 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2438 {
2439         struct btrfs_ordered_sum *sum = NULL;
2440         unsigned long index;
2441         unsigned long num_sectors;
2442
2443         while (!list_empty(&sctx->csum_list)) {
2444                 sum = list_first_entry(&sctx->csum_list,
2445                                        struct btrfs_ordered_sum, list);
2446                 if (sum->bytenr > logical)
2447                         return 0;
2448                 if (sum->bytenr + sum->len > logical)
2449                         break;
2450
2451                 ++sctx->stat.csum_discards;
2452                 list_del(&sum->list);
2453                 kfree(sum);
2454                 sum = NULL;
2455         }
2456         if (!sum)
2457                 return 0;
2458
2459         index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize);
2460         ASSERT(index < UINT_MAX);
2461
2462         num_sectors = sum->len / sctx->fs_info->sectorsize;
2463         memcpy(csum, sum->sums + index * sctx->csum_size, sctx->csum_size);
2464         if (index == num_sectors - 1) {
2465                 list_del(&sum->list);
2466                 kfree(sum);
2467         }
2468         return 1;
2469 }
2470
2471 /* scrub extent tries to collect up to 64 kB for each bio */
2472 static int scrub_extent(struct scrub_ctx *sctx, struct map_lookup *map,
2473                         u64 logical, u64 len,
2474                         u64 physical, struct btrfs_device *dev, u64 flags,
2475                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2476 {
2477         int ret;
2478         u8 csum[BTRFS_CSUM_SIZE];
2479         u32 blocksize;
2480
2481         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2482                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2483                         blocksize = map->stripe_len;
2484                 else
2485                         blocksize = sctx->fs_info->sectorsize;
2486                 spin_lock(&sctx->stat_lock);
2487                 sctx->stat.data_extents_scrubbed++;
2488                 sctx->stat.data_bytes_scrubbed += len;
2489                 spin_unlock(&sctx->stat_lock);
2490         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2491                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2492                         blocksize = map->stripe_len;
2493                 else
2494                         blocksize = sctx->fs_info->nodesize;
2495                 spin_lock(&sctx->stat_lock);
2496                 sctx->stat.tree_extents_scrubbed++;
2497                 sctx->stat.tree_bytes_scrubbed += len;
2498                 spin_unlock(&sctx->stat_lock);
2499         } else {
2500                 blocksize = sctx->fs_info->sectorsize;
2501                 WARN_ON(1);
2502         }
2503
2504         while (len) {
2505                 u64 l = min_t(u64, len, blocksize);
2506                 int have_csum = 0;
2507
2508                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2509                         /* push csums to sbio */
2510                         have_csum = scrub_find_csum(sctx, logical, csum);
2511                         if (have_csum == 0)
2512                                 ++sctx->stat.no_csum;
2513                 }
2514                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2515                                   mirror_num, have_csum ? csum : NULL, 0,
2516                                   physical_for_dev_replace);
2517                 if (ret)
2518                         return ret;
2519                 len -= l;
2520                 logical += l;
2521                 physical += l;
2522                 physical_for_dev_replace += l;
2523         }
2524         return 0;
2525 }
2526
2527 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2528                                   u64 logical, u64 len,
2529                                   u64 physical, struct btrfs_device *dev,
2530                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2531 {
2532         struct scrub_ctx *sctx = sparity->sctx;
2533         struct scrub_block *sblock;
2534         int index;
2535
2536         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2537         if (!sblock) {
2538                 spin_lock(&sctx->stat_lock);
2539                 sctx->stat.malloc_errors++;
2540                 spin_unlock(&sctx->stat_lock);
2541                 return -ENOMEM;
2542         }
2543
2544         /* one ref inside this function, plus one for each page added to
2545          * a bio later on */
2546         refcount_set(&sblock->refs, 1);
2547         sblock->sctx = sctx;
2548         sblock->no_io_error_seen = 1;
2549         sblock->sparity = sparity;
2550         scrub_parity_get(sparity);
2551
2552         for (index = 0; len > 0; index++) {
2553                 struct scrub_page *spage;
2554                 u64 l = min_t(u64, len, PAGE_SIZE);
2555
2556                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2557                 if (!spage) {
2558 leave_nomem:
2559                         spin_lock(&sctx->stat_lock);
2560                         sctx->stat.malloc_errors++;
2561                         spin_unlock(&sctx->stat_lock);
2562                         scrub_block_put(sblock);
2563                         return -ENOMEM;
2564                 }
2565                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2566                 /* For scrub block */
2567                 scrub_page_get(spage);
2568                 sblock->pagev[index] = spage;
2569                 /* For scrub parity */
2570                 scrub_page_get(spage);
2571                 list_add_tail(&spage->list, &sparity->spages);
2572                 spage->sblock = sblock;
2573                 spage->dev = dev;
2574                 spage->flags = flags;
2575                 spage->generation = gen;
2576                 spage->logical = logical;
2577                 spage->physical = physical;
2578                 spage->mirror_num = mirror_num;
2579                 if (csum) {
2580                         spage->have_csum = 1;
2581                         memcpy(spage->csum, csum, sctx->csum_size);
2582                 } else {
2583                         spage->have_csum = 0;
2584                 }
2585                 sblock->page_count++;
2586                 spage->page = alloc_page(GFP_KERNEL);
2587                 if (!spage->page)
2588                         goto leave_nomem;
2589                 len -= l;
2590                 logical += l;
2591                 physical += l;
2592         }
2593
2594         WARN_ON(sblock->page_count == 0);
2595         for (index = 0; index < sblock->page_count; index++) {
2596                 struct scrub_page *spage = sblock->pagev[index];
2597                 int ret;
2598
2599                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2600                 if (ret) {
2601                         scrub_block_put(sblock);
2602                         return ret;
2603                 }
2604         }
2605
2606         /* last one frees, either here or in bio completion for last page */
2607         scrub_block_put(sblock);
2608         return 0;
2609 }
2610
2611 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2612                                    u64 logical, u64 len,
2613                                    u64 physical, struct btrfs_device *dev,
2614                                    u64 flags, u64 gen, int mirror_num)
2615 {
2616         struct scrub_ctx *sctx = sparity->sctx;
2617         int ret;
2618         u8 csum[BTRFS_CSUM_SIZE];
2619         u32 blocksize;
2620
2621         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2622                 scrub_parity_mark_sectors_error(sparity, logical, len);
2623                 return 0;
2624         }
2625
2626         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2627                 blocksize = sparity->stripe_len;
2628         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2629                 blocksize = sparity->stripe_len;
2630         } else {
2631                 blocksize = sctx->fs_info->sectorsize;
2632                 WARN_ON(1);
2633         }
2634
2635         while (len) {
2636                 u64 l = min_t(u64, len, blocksize);
2637                 int have_csum = 0;
2638
2639                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2640                         /* push csums to sbio */
2641                         have_csum = scrub_find_csum(sctx, logical, csum);
2642                         if (have_csum == 0)
2643                                 goto skip;
2644                 }
2645                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2646                                              flags, gen, mirror_num,
2647                                              have_csum ? csum : NULL);
2648                 if (ret)
2649                         return ret;
2650 skip:
2651                 len -= l;
2652                 logical += l;
2653                 physical += l;
2654         }
2655         return 0;
2656 }
2657
2658 /*
2659  * Given a physical address, this will calculate it's
2660  * logical offset. if this is a parity stripe, it will return
2661  * the most left data stripe's logical offset.
2662  *
2663  * return 0 if it is a data stripe, 1 means parity stripe.
2664  */
2665 static int get_raid56_logic_offset(u64 physical, int num,
2666                                    struct map_lookup *map, u64 *offset,
2667                                    u64 *stripe_start)
2668 {
2669         int i;
2670         int j = 0;
2671         u64 stripe_nr;
2672         u64 last_offset;
2673         u32 stripe_index;
2674         u32 rot;
2675         const int data_stripes = nr_data_stripes(map);
2676
2677         last_offset = (physical - map->stripes[num].physical) * data_stripes;
2678         if (stripe_start)
2679                 *stripe_start = last_offset;
2680
2681         *offset = last_offset;
2682         for (i = 0; i < data_stripes; i++) {
2683                 *offset = last_offset + i * map->stripe_len;
2684
2685                 stripe_nr = div64_u64(*offset, map->stripe_len);
2686                 stripe_nr = div_u64(stripe_nr, data_stripes);
2687
2688                 /* Work out the disk rotation on this stripe-set */
2689                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2690                 /* calculate which stripe this data locates */
2691                 rot += i;
2692                 stripe_index = rot % map->num_stripes;
2693                 if (stripe_index == num)
2694                         return 0;
2695                 if (stripe_index < num)
2696                         j++;
2697         }
2698         *offset = last_offset + j * map->stripe_len;
2699         return 1;
2700 }
2701
2702 static void scrub_free_parity(struct scrub_parity *sparity)
2703 {
2704         struct scrub_ctx *sctx = sparity->sctx;
2705         struct scrub_page *curr, *next;
2706         int nbits;
2707
2708         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2709         if (nbits) {
2710                 spin_lock(&sctx->stat_lock);
2711                 sctx->stat.read_errors += nbits;
2712                 sctx->stat.uncorrectable_errors += nbits;
2713                 spin_unlock(&sctx->stat_lock);
2714         }
2715
2716         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2717                 list_del_init(&curr->list);
2718                 scrub_page_put(curr);
2719         }
2720
2721         kfree(sparity);
2722 }
2723
2724 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2725 {
2726         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2727                                                     work);
2728         struct scrub_ctx *sctx = sparity->sctx;
2729
2730         scrub_free_parity(sparity);
2731         scrub_pending_bio_dec(sctx);
2732 }
2733
2734 static void scrub_parity_bio_endio(struct bio *bio)
2735 {
2736         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
2737         struct btrfs_fs_info *fs_info = sparity->sctx->fs_info;
2738
2739         if (bio->bi_status)
2740                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2741                           sparity->nsectors);
2742
2743         bio_put(bio);
2744
2745         btrfs_init_work(&sparity->work, btrfs_scrubparity_helper,
2746                         scrub_parity_bio_endio_worker, NULL, NULL);
2747         btrfs_queue_work(fs_info->scrub_parity_workers, &sparity->work);
2748 }
2749
2750 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
2751 {
2752         struct scrub_ctx *sctx = sparity->sctx;
2753         struct btrfs_fs_info *fs_info = sctx->fs_info;
2754         struct bio *bio;
2755         struct btrfs_raid_bio *rbio;
2756         struct btrfs_bio *bbio = NULL;
2757         u64 length;
2758         int ret;
2759
2760         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
2761                            sparity->nsectors))
2762                 goto out;
2763
2764         length = sparity->logic_end - sparity->logic_start;
2765
2766         btrfs_bio_counter_inc_blocked(fs_info);
2767         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,
2768                                &length, &bbio);
2769         if (ret || !bbio || !bbio->raid_map)
2770                 goto bbio_out;
2771
2772         bio = btrfs_io_bio_alloc(0);
2773         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
2774         bio->bi_private = sparity;
2775         bio->bi_end_io = scrub_parity_bio_endio;
2776
2777         rbio = raid56_parity_alloc_scrub_rbio(fs_info, bio, bbio,
2778                                               length, sparity->scrub_dev,
2779                                               sparity->dbitmap,
2780                                               sparity->nsectors);
2781         if (!rbio)
2782                 goto rbio_out;
2783
2784         scrub_pending_bio_inc(sctx);
2785         raid56_parity_submit_scrub_rbio(rbio);
2786         return;
2787
2788 rbio_out:
2789         bio_put(bio);
2790 bbio_out:
2791         btrfs_bio_counter_dec(fs_info);
2792         btrfs_put_bbio(bbio);
2793         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2794                   sparity->nsectors);
2795         spin_lock(&sctx->stat_lock);
2796         sctx->stat.malloc_errors++;
2797         spin_unlock(&sctx->stat_lock);
2798 out:
2799         scrub_free_parity(sparity);
2800 }
2801
2802 static inline int scrub_calc_parity_bitmap_len(int nsectors)
2803 {
2804         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
2805 }
2806
2807 static void scrub_parity_get(struct scrub_parity *sparity)
2808 {
2809         refcount_inc(&sparity->refs);
2810 }
2811
2812 static void scrub_parity_put(struct scrub_parity *sparity)
2813 {
2814         if (!refcount_dec_and_test(&sparity->refs))
2815                 return;
2816
2817         scrub_parity_check_and_repair(sparity);
2818 }
2819
2820 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
2821                                                   struct map_lookup *map,
2822                                                   struct btrfs_device *sdev,
2823                                                   struct btrfs_path *path,
2824                                                   u64 logic_start,
2825                                                   u64 logic_end)
2826 {
2827         struct btrfs_fs_info *fs_info = sctx->fs_info;
2828         struct btrfs_root *root = fs_info->extent_root;
2829         struct btrfs_root *csum_root = fs_info->csum_root;
2830         struct btrfs_extent_item *extent;
2831         struct btrfs_bio *bbio = NULL;
2832         u64 flags;
2833         int ret;
2834         int slot;
2835         struct extent_buffer *l;
2836         struct btrfs_key key;
2837         u64 generation;
2838         u64 extent_logical;
2839         u64 extent_physical;
2840         u64 extent_len;
2841         u64 mapped_length;
2842         struct btrfs_device *extent_dev;
2843         struct scrub_parity *sparity;
2844         int nsectors;
2845         int bitmap_len;
2846         int extent_mirror_num;
2847         int stop_loop = 0;
2848
2849         nsectors = div_u64(map->stripe_len, fs_info->sectorsize);
2850         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
2851         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
2852                           GFP_NOFS);
2853         if (!sparity) {
2854                 spin_lock(&sctx->stat_lock);
2855                 sctx->stat.malloc_errors++;
2856                 spin_unlock(&sctx->stat_lock);
2857                 return -ENOMEM;
2858         }
2859
2860         sparity->stripe_len = map->stripe_len;
2861         sparity->nsectors = nsectors;
2862         sparity->sctx = sctx;
2863         sparity->scrub_dev = sdev;
2864         sparity->logic_start = logic_start;
2865         sparity->logic_end = logic_end;
2866         refcount_set(&sparity->refs, 1);
2867         INIT_LIST_HEAD(&sparity->spages);
2868         sparity->dbitmap = sparity->bitmap;
2869         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
2870
2871         ret = 0;
2872         while (logic_start < logic_end) {
2873                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2874                         key.type = BTRFS_METADATA_ITEM_KEY;
2875                 else
2876                         key.type = BTRFS_EXTENT_ITEM_KEY;
2877                 key.objectid = logic_start;
2878                 key.offset = (u64)-1;
2879
2880                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2881                 if (ret < 0)
2882                         goto out;
2883
2884                 if (ret > 0) {
2885                         ret = btrfs_previous_extent_item(root, path, 0);
2886                         if (ret < 0)
2887                                 goto out;
2888                         if (ret > 0) {
2889                                 btrfs_release_path(path);
2890                                 ret = btrfs_search_slot(NULL, root, &key,
2891                                                         path, 0, 0);
2892                                 if (ret < 0)
2893                                         goto out;
2894                         }
2895                 }
2896
2897                 stop_loop = 0;
2898                 while (1) {
2899                         u64 bytes;
2900
2901                         l = path->nodes[0];
2902                         slot = path->slots[0];
2903                         if (slot >= btrfs_header_nritems(l)) {
2904                                 ret = btrfs_next_leaf(root, path);
2905                                 if (ret == 0)
2906                                         continue;
2907                                 if (ret < 0)
2908                                         goto out;
2909
2910                                 stop_loop = 1;
2911                                 break;
2912                         }
2913                         btrfs_item_key_to_cpu(l, &key, slot);
2914
2915                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2916                             key.type != BTRFS_METADATA_ITEM_KEY)
2917                                 goto next;
2918
2919                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2920                                 bytes = fs_info->nodesize;
2921                         else
2922                                 bytes = key.offset;
2923
2924                         if (key.objectid + bytes <= logic_start)
2925                                 goto next;
2926
2927                         if (key.objectid >= logic_end) {
2928                                 stop_loop = 1;
2929                                 break;
2930                         }
2931
2932                         while (key.objectid >= logic_start + map->stripe_len)
2933                                 logic_start += map->stripe_len;
2934
2935                         extent = btrfs_item_ptr(l, slot,
2936                                                 struct btrfs_extent_item);
2937                         flags = btrfs_extent_flags(l, extent);
2938                         generation = btrfs_extent_generation(l, extent);
2939
2940                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
2941                             (key.objectid < logic_start ||
2942                              key.objectid + bytes >
2943                              logic_start + map->stripe_len)) {
2944                                 btrfs_err(fs_info,
2945                                           "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
2946                                           key.objectid, logic_start);
2947                                 spin_lock(&sctx->stat_lock);
2948                                 sctx->stat.uncorrectable_errors++;
2949                                 spin_unlock(&sctx->stat_lock);
2950                                 goto next;
2951                         }
2952 again:
2953                         extent_logical = key.objectid;
2954                         extent_len = bytes;
2955
2956                         if (extent_logical < logic_start) {
2957                                 extent_len -= logic_start - extent_logical;
2958                                 extent_logical = logic_start;
2959                         }
2960
2961                         if (extent_logical + extent_len >
2962                             logic_start + map->stripe_len)
2963                                 extent_len = logic_start + map->stripe_len -
2964                                              extent_logical;
2965
2966                         scrub_parity_mark_sectors_data(sparity, extent_logical,
2967                                                        extent_len);
2968
2969                         mapped_length = extent_len;
2970                         bbio = NULL;
2971                         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ,
2972                                         extent_logical, &mapped_length, &bbio,
2973                                         0);
2974                         if (!ret) {
2975                                 if (!bbio || mapped_length < extent_len)
2976                                         ret = -EIO;
2977                         }
2978                         if (ret) {
2979                                 btrfs_put_bbio(bbio);
2980                                 goto out;
2981                         }
2982                         extent_physical = bbio->stripes[0].physical;
2983                         extent_mirror_num = bbio->mirror_num;
2984                         extent_dev = bbio->stripes[0].dev;
2985                         btrfs_put_bbio(bbio);
2986
2987                         ret = btrfs_lookup_csums_range(csum_root,
2988                                                 extent_logical,
2989                                                 extent_logical + extent_len - 1,
2990                                                 &sctx->csum_list, 1);
2991                         if (ret)
2992                                 goto out;
2993
2994                         ret = scrub_extent_for_parity(sparity, extent_logical,
2995                                                       extent_len,
2996                                                       extent_physical,
2997                                                       extent_dev, flags,
2998                                                       generation,
2999                                                       extent_mirror_num);
3000
3001                         scrub_free_csums(sctx);
3002
3003                         if (ret)
3004                                 goto out;
3005
3006                         if (extent_logical + extent_len <
3007                             key.objectid + bytes) {
3008                                 logic_start += map->stripe_len;
3009
3010                                 if (logic_start >= logic_end) {
3011                                         stop_loop = 1;
3012                                         break;
3013                                 }
3014
3015                                 if (logic_start < key.objectid + bytes) {
3016                                         cond_resched();
3017                                         goto again;
3018                                 }
3019                         }
3020 next:
3021                         path->slots[0]++;
3022                 }
3023
3024                 btrfs_release_path(path);
3025
3026                 if (stop_loop)
3027                         break;
3028
3029                 logic_start += map->stripe_len;
3030         }
3031 out:
3032         if (ret < 0)
3033                 scrub_parity_mark_sectors_error(sparity, logic_start,
3034                                                 logic_end - logic_start);
3035         scrub_parity_put(sparity);
3036         scrub_submit(sctx);
3037         mutex_lock(&sctx->wr_lock);
3038         scrub_wr_submit(sctx);
3039         mutex_unlock(&sctx->wr_lock);
3040
3041         btrfs_release_path(path);
3042         return ret < 0 ? ret : 0;
3043 }
3044
3045 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3046                                            struct map_lookup *map,
3047                                            struct btrfs_device *scrub_dev,
3048                                            int num, u64 base, u64 length)
3049 {
3050         struct btrfs_path *path, *ppath;
3051         struct btrfs_fs_info *fs_info = sctx->fs_info;
3052         struct btrfs_root *root = fs_info->extent_root;
3053         struct btrfs_root *csum_root = fs_info->csum_root;
3054         struct btrfs_extent_item *extent;
3055         struct blk_plug plug;
3056         u64 flags;
3057         int ret;
3058         int slot;
3059         u64 nstripes;
3060         struct extent_buffer *l;
3061         u64 physical;
3062         u64 logical;
3063         u64 logic_end;
3064         u64 physical_end;
3065         u64 generation;
3066         int mirror_num;
3067         struct reada_control *reada1;
3068         struct reada_control *reada2;
3069         struct btrfs_key key;
3070         struct btrfs_key key_end;
3071         u64 increment = map->stripe_len;
3072         u64 offset;
3073         u64 extent_logical;
3074         u64 extent_physical;
3075         u64 extent_len;
3076         u64 stripe_logical;
3077         u64 stripe_end;
3078         struct btrfs_device *extent_dev;
3079         int extent_mirror_num;
3080         int stop_loop = 0;
3081
3082         physical = map->stripes[num].physical;
3083         offset = 0;
3084         nstripes = div64_u64(length, map->stripe_len);
3085         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3086                 offset = map->stripe_len * num;
3087                 increment = map->stripe_len * map->num_stripes;
3088                 mirror_num = 1;
3089         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3090                 int factor = map->num_stripes / map->sub_stripes;
3091                 offset = map->stripe_len * (num / map->sub_stripes);
3092                 increment = map->stripe_len * factor;
3093                 mirror_num = num % map->sub_stripes + 1;
3094         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1_MASK) {
3095                 increment = map->stripe_len;
3096                 mirror_num = num % map->num_stripes + 1;
3097         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3098                 increment = map->stripe_len;
3099                 mirror_num = num % map->num_stripes + 1;
3100         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3101                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3102                 increment = map->stripe_len * nr_data_stripes(map);
3103                 mirror_num = 1;
3104         } else {
3105                 increment = map->stripe_len;
3106                 mirror_num = 1;
3107         }
3108
3109         path = btrfs_alloc_path();
3110         if (!path)
3111                 return -ENOMEM;
3112
3113         ppath = btrfs_alloc_path();
3114         if (!ppath) {
3115                 btrfs_free_path(path);
3116                 return -ENOMEM;
3117         }
3118
3119         /*
3120          * work on commit root. The related disk blocks are static as
3121          * long as COW is applied. This means, it is save to rewrite
3122          * them to repair disk errors without any race conditions
3123          */
3124         path->search_commit_root = 1;
3125         path->skip_locking = 1;
3126
3127         ppath->search_commit_root = 1;
3128         ppath->skip_locking = 1;
3129         /*
3130          * trigger the readahead for extent tree csum tree and wait for
3131          * completion. During readahead, the scrub is officially paused
3132          * to not hold off transaction commits
3133          */
3134         logical = base + offset;
3135         physical_end = physical + nstripes * map->stripe_len;
3136         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3137                 get_raid56_logic_offset(physical_end, num,
3138                                         map, &logic_end, NULL);
3139                 logic_end += base;
3140         } else {
3141                 logic_end = logical + increment * nstripes;
3142         }
3143         wait_event(sctx->list_wait,
3144                    atomic_read(&sctx->bios_in_flight) == 0);
3145         scrub_blocked_if_needed(fs_info);
3146
3147         /* FIXME it might be better to start readahead at commit root */
3148         key.objectid = logical;
3149         key.type = BTRFS_EXTENT_ITEM_KEY;
3150         key.offset = (u64)0;
3151         key_end.objectid = logic_end;
3152         key_end.type = BTRFS_METADATA_ITEM_KEY;
3153         key_end.offset = (u64)-1;
3154         reada1 = btrfs_reada_add(root, &key, &key_end);
3155
3156         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3157         key.type = BTRFS_EXTENT_CSUM_KEY;
3158         key.offset = logical;
3159         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3160         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3161         key_end.offset = logic_end;
3162         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3163
3164         if (!IS_ERR(reada1))
3165                 btrfs_reada_wait(reada1);
3166         if (!IS_ERR(reada2))
3167                 btrfs_reada_wait(reada2);
3168
3169
3170         /*
3171          * collect all data csums for the stripe to avoid seeking during
3172          * the scrub. This might currently (crc32) end up to be about 1MB
3173          */
3174         blk_start_plug(&plug);
3175
3176         /*
3177          * now find all extents for each stripe and scrub them
3178          */
3179         ret = 0;
3180         while (physical < physical_end) {
3181                 /*
3182                  * canceled?
3183                  */
3184                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3185                     atomic_read(&sctx->cancel_req)) {
3186                         ret = -ECANCELED;
3187                         goto out;
3188                 }
3189                 /*
3190                  * check to see if we have to pause
3191                  */
3192                 if (atomic_read(&fs_info->scrub_pause_req)) {
3193                         /* push queued extents */
3194                         sctx->flush_all_writes = true;
3195                         scrub_submit(sctx);
3196                         mutex_lock(&sctx->wr_lock);
3197                         scrub_wr_submit(sctx);
3198                         mutex_unlock(&sctx->wr_lock);
3199                         wait_event(sctx->list_wait,
3200                                    atomic_read(&sctx->bios_in_flight) == 0);
3201                         sctx->flush_all_writes = false;
3202                         scrub_blocked_if_needed(fs_info);
3203                 }
3204
3205                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3206                         ret = get_raid56_logic_offset(physical, num, map,
3207                                                       &logical,
3208                                                       &stripe_logical);
3209                         logical += base;
3210                         if (ret) {
3211                                 /* it is parity strip */
3212                                 stripe_logical += base;
3213                                 stripe_end = stripe_logical + increment;
3214                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3215                                                           ppath, stripe_logical,
3216                                                           stripe_end);
3217                                 if (ret)
3218                                         goto out;
3219                                 goto skip;
3220                         }
3221                 }
3222
3223                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3224                         key.type = BTRFS_METADATA_ITEM_KEY;
3225                 else
3226                         key.type = BTRFS_EXTENT_ITEM_KEY;
3227                 key.objectid = logical;
3228                 key.offset = (u64)-1;
3229
3230                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3231                 if (ret < 0)
3232                         goto out;
3233
3234                 if (ret > 0) {
3235                         ret = btrfs_previous_extent_item(root, path, 0);
3236                         if (ret < 0)
3237                                 goto out;
3238                         if (ret > 0) {
3239                                 /* there's no smaller item, so stick with the
3240                                  * larger one */
3241                                 btrfs_release_path(path);
3242                                 ret = btrfs_search_slot(NULL, root, &key,
3243                                                         path, 0, 0);
3244                                 if (ret < 0)
3245                                         goto out;
3246                         }
3247                 }
3248
3249                 stop_loop = 0;
3250                 while (1) {
3251                         u64 bytes;
3252
3253                         l = path->nodes[0];
3254                         slot = path->slots[0];
3255                         if (slot >= btrfs_header_nritems(l)) {
3256                                 ret = btrfs_next_leaf(root, path);
3257                                 if (ret == 0)
3258                                         continue;
3259                                 if (ret < 0)
3260                                         goto out;
3261
3262                                 stop_loop = 1;
3263                                 break;
3264                         }
3265                         btrfs_item_key_to_cpu(l, &key, slot);
3266
3267                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3268                             key.type != BTRFS_METADATA_ITEM_KEY)
3269                                 goto next;
3270
3271                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3272                                 bytes = fs_info->nodesize;
3273                         else
3274                                 bytes = key.offset;
3275
3276                         if (key.objectid + bytes <= logical)
3277                                 goto next;
3278
3279                         if (key.objectid >= logical + map->stripe_len) {
3280                                 /* out of this device extent */
3281                                 if (key.objectid >= logic_end)
3282                                         stop_loop = 1;
3283                                 break;
3284                         }
3285
3286                         extent = btrfs_item_ptr(l, slot,
3287                                                 struct btrfs_extent_item);
3288                         flags = btrfs_extent_flags(l, extent);
3289                         generation = btrfs_extent_generation(l, extent);
3290
3291                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3292                             (key.objectid < logical ||
3293                              key.objectid + bytes >
3294                              logical + map->stripe_len)) {
3295                                 btrfs_err(fs_info,
3296                                            "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
3297                                        key.objectid, logical);
3298                                 spin_lock(&sctx->stat_lock);
3299                                 sctx->stat.uncorrectable_errors++;
3300                                 spin_unlock(&sctx->stat_lock);
3301                                 goto next;
3302                         }
3303
3304 again:
3305                         extent_logical = key.objectid;
3306                         extent_len = bytes;
3307
3308                         /*
3309                          * trim extent to this stripe
3310                          */
3311                         if (extent_logical < logical) {
3312                                 extent_len -= logical - extent_logical;
3313                                 extent_logical = logical;
3314                         }
3315                         if (extent_logical + extent_len >
3316                             logical + map->stripe_len) {
3317                                 extent_len = logical + map->stripe_len -
3318                                              extent_logical;
3319                         }
3320
3321                         extent_physical = extent_logical - logical + physical;
3322                         extent_dev = scrub_dev;
3323                         extent_mirror_num = mirror_num;
3324                         if (sctx->is_dev_replace)
3325                                 scrub_remap_extent(fs_info, extent_logical,
3326                                                    extent_len, &extent_physical,
3327                                                    &extent_dev,
3328                                                    &extent_mirror_num);
3329
3330                         ret = btrfs_lookup_csums_range(csum_root,
3331                                                        extent_logical,
3332                                                        extent_logical +
3333                                                        extent_len - 1,
3334                                                        &sctx->csum_list, 1);
3335                         if (ret)
3336                                 goto out;
3337
3338                         ret = scrub_extent(sctx, map, extent_logical, extent_len,
3339                                            extent_physical, extent_dev, flags,
3340                                            generation, extent_mirror_num,
3341                                            extent_logical - logical + physical);
3342
3343                         scrub_free_csums(sctx);
3344
3345                         if (ret)
3346                                 goto out;
3347
3348                         if (extent_logical + extent_len <
3349                             key.objectid + bytes) {
3350                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3351                                         /*
3352                                          * loop until we find next data stripe
3353                                          * or we have finished all stripes.
3354                                          */
3355 loop:
3356                                         physical += map->stripe_len;
3357                                         ret = get_raid56_logic_offset(physical,
3358                                                         num, map, &logical,
3359                                                         &stripe_logical);
3360                                         logical += base;
3361
3362                                         if (ret && physical < physical_end) {
3363                                                 stripe_logical += base;
3364                                                 stripe_end = stripe_logical +
3365                                                                 increment;
3366                                                 ret = scrub_raid56_parity(sctx,
3367                                                         map, scrub_dev, ppath,
3368                                                         stripe_logical,
3369                                                         stripe_end);
3370                                                 if (ret)
3371                                                         goto out;
3372                                                 goto loop;
3373                                         }
3374                                 } else {
3375                                         physical += map->stripe_len;
3376                                         logical += increment;
3377                                 }
3378                                 if (logical < key.objectid + bytes) {
3379                                         cond_resched();
3380                                         goto again;
3381                                 }
3382
3383                                 if (physical >= physical_end) {
3384                                         stop_loop = 1;
3385                                         break;
3386                                 }
3387                         }
3388 next:
3389                         path->slots[0]++;
3390                 }
3391                 btrfs_release_path(path);
3392 skip:
3393                 logical += increment;
3394                 physical += map->stripe_len;
3395                 spin_lock(&sctx->stat_lock);
3396                 if (stop_loop)
3397                         sctx->stat.last_physical = map->stripes[num].physical +
3398                                                    length;
3399                 else
3400                         sctx->stat.last_physical = physical;
3401                 spin_unlock(&sctx->stat_lock);
3402                 if (stop_loop)
3403                         break;
3404         }
3405 out:
3406         /* push queued extents */
3407         scrub_submit(sctx);
3408         mutex_lock(&sctx->wr_lock);
3409         scrub_wr_submit(sctx);
3410         mutex_unlock(&sctx->wr_lock);
3411
3412         blk_finish_plug(&plug);
3413         btrfs_free_path(path);
3414         btrfs_free_path(ppath);
3415         return ret < 0 ? ret : 0;
3416 }
3417
3418 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3419                                           struct btrfs_device *scrub_dev,
3420                                           u64 chunk_offset, u64 length,
3421                                           u64 dev_offset,
3422                                           struct btrfs_block_group_cache *cache)
3423 {
3424         struct btrfs_fs_info *fs_info = sctx->fs_info;
3425         struct extent_map_tree *map_tree = &fs_info->mapping_tree;
3426         struct map_lookup *map;
3427         struct extent_map *em;
3428         int i;
3429         int ret = 0;
3430
3431         read_lock(&map_tree->lock);
3432         em = lookup_extent_mapping(map_tree, chunk_offset, 1);
3433         read_unlock(&map_tree->lock);
3434
3435         if (!em) {
3436                 /*
3437                  * Might have been an unused block group deleted by the cleaner
3438                  * kthread or relocation.
3439                  */
3440                 spin_lock(&cache->lock);
3441                 if (!cache->removed)
3442                         ret = -EINVAL;
3443                 spin_unlock(&cache->lock);
3444
3445                 return ret;
3446         }
3447
3448         map = em->map_lookup;
3449         if (em->start != chunk_offset)
3450                 goto out;
3451
3452         if (em->len < length)
3453                 goto out;
3454
3455         for (i = 0; i < map->num_stripes; ++i) {
3456                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3457                     map->stripes[i].physical == dev_offset) {
3458                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3459                                            chunk_offset, length);
3460                         if (ret)
3461                                 goto out;
3462                 }
3463         }
3464 out:
3465         free_extent_map(em);
3466
3467         return ret;
3468 }
3469
3470 static noinline_for_stack
3471 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3472                            struct btrfs_device *scrub_dev, u64 start, u64 end)
3473 {
3474         struct btrfs_dev_extent *dev_extent = NULL;
3475         struct btrfs_path *path;
3476         struct btrfs_fs_info *fs_info = sctx->fs_info;
3477         struct btrfs_root *root = fs_info->dev_root;
3478         u64 length;
3479         u64 chunk_offset;
3480         int ret = 0;
3481         int ro_set;
3482         int slot;
3483         struct extent_buffer *l;
3484         struct btrfs_key key;
3485         struct btrfs_key found_key;
3486         struct btrfs_block_group_cache *cache;
3487         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3488
3489         path = btrfs_alloc_path();
3490         if (!path)
3491                 return -ENOMEM;
3492
3493         path->reada = READA_FORWARD;
3494         path->search_commit_root = 1;
3495         path->skip_locking = 1;
3496
3497         key.objectid = scrub_dev->devid;
3498         key.offset = 0ull;
3499         key.type = BTRFS_DEV_EXTENT_KEY;
3500
3501         while (1) {
3502                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3503                 if (ret < 0)
3504                         break;
3505                 if (ret > 0) {
3506                         if (path->slots[0] >=
3507                             btrfs_header_nritems(path->nodes[0])) {
3508                                 ret = btrfs_next_leaf(root, path);
3509                                 if (ret < 0)
3510                                         break;
3511                                 if (ret > 0) {
3512                                         ret = 0;
3513                                         break;
3514                                 }
3515                         } else {
3516                                 ret = 0;
3517                         }
3518                 }
3519
3520                 l = path->nodes[0];
3521                 slot = path->slots[0];
3522
3523                 btrfs_item_key_to_cpu(l, &found_key, slot);
3524
3525                 if (found_key.objectid != scrub_dev->devid)
3526                         break;
3527
3528                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3529                         break;
3530
3531                 if (found_key.offset >= end)
3532                         break;
3533
3534                 if (found_key.offset < key.offset)
3535                         break;
3536
3537                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3538                 length = btrfs_dev_extent_length(l, dev_extent);
3539
3540                 if (found_key.offset + length <= start)
3541                         goto skip;
3542
3543                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3544
3545                 /*
3546                  * get a reference on the corresponding block group to prevent
3547                  * the chunk from going away while we scrub it
3548                  */
3549                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3550
3551                 /* some chunks are removed but not committed to disk yet,
3552                  * continue scrubbing */
3553                 if (!cache)
3554                         goto skip;
3555
3556                 /*
3557                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3558                  * to avoid deadlock caused by:
3559                  * btrfs_inc_block_group_ro()
3560                  * -> btrfs_wait_for_commit()
3561                  * -> btrfs_commit_transaction()
3562                  * -> btrfs_scrub_pause()
3563                  */
3564                 scrub_pause_on(fs_info);
3565                 ret = btrfs_inc_block_group_ro(cache);
3566                 if (!ret && sctx->is_dev_replace) {
3567                         /*
3568                          * If we are doing a device replace wait for any tasks
3569                          * that started delalloc right before we set the block
3570                          * group to RO mode, as they might have just allocated
3571                          * an extent from it or decided they could do a nocow
3572                          * write. And if any such tasks did that, wait for their
3573                          * ordered extents to complete and then commit the
3574                          * current transaction, so that we can later see the new
3575                          * extent items in the extent tree - the ordered extents
3576                          * create delayed data references (for cow writes) when
3577                          * they complete, which will be run and insert the
3578                          * corresponding extent items into the extent tree when
3579                          * we commit the transaction they used when running
3580                          * inode.c:btrfs_finish_ordered_io(). We later use
3581                          * the commit root of the extent tree to find extents
3582                          * to copy from the srcdev into the tgtdev, and we don't
3583                          * want to miss any new extents.
3584                          */
3585                         btrfs_wait_block_group_reservations(cache);
3586                         btrfs_wait_nocow_writers(cache);
3587                         ret = btrfs_wait_ordered_roots(fs_info, U64_MAX,
3588                                                        cache->key.objectid,
3589                                                        cache->key.offset);
3590                         if (ret > 0) {
3591                                 struct btrfs_trans_handle *trans;
3592
3593                                 trans = btrfs_join_transaction(root);
3594                                 if (IS_ERR(trans))
3595                                         ret = PTR_ERR(trans);
3596                                 else
3597                                         ret = btrfs_commit_transaction(trans);
3598                                 if (ret) {
3599                                         scrub_pause_off(fs_info);
3600                                         btrfs_put_block_group(cache);
3601                                         break;
3602                                 }
3603                         }
3604                 }
3605                 scrub_pause_off(fs_info);
3606
3607                 if (ret == 0) {
3608                         ro_set = 1;
3609                 } else if (ret == -ENOSPC) {
3610                         /*
3611                          * btrfs_inc_block_group_ro return -ENOSPC when it
3612                          * failed in creating new chunk for metadata.
3613                          * It is not a problem for scrub/replace, because
3614                          * metadata are always cowed, and our scrub paused
3615                          * commit_transactions.
3616                          */
3617                         ro_set = 0;
3618                 } else {
3619                         btrfs_warn(fs_info,
3620                                    "failed setting block group ro: %d", ret);
3621                         btrfs_put_block_group(cache);
3622                         break;
3623                 }
3624
3625                 down_write(&fs_info->dev_replace.rwsem);
3626                 dev_replace->cursor_right = found_key.offset + length;
3627                 dev_replace->cursor_left = found_key.offset;
3628                 dev_replace->item_needs_writeback = 1;
3629                 up_write(&dev_replace->rwsem);
3630
3631                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3632                                   found_key.offset, cache);
3633
3634                 /*
3635                  * flush, submit all pending read and write bios, afterwards
3636                  * wait for them.
3637                  * Note that in the dev replace case, a read request causes
3638                  * write requests that are submitted in the read completion
3639                  * worker. Therefore in the current situation, it is required
3640                  * that all write requests are flushed, so that all read and
3641                  * write requests are really completed when bios_in_flight
3642                  * changes to 0.
3643                  */
3644                 sctx->flush_all_writes = true;
3645                 scrub_submit(sctx);
3646                 mutex_lock(&sctx->wr_lock);
3647                 scrub_wr_submit(sctx);
3648                 mutex_unlock(&sctx->wr_lock);
3649
3650                 wait_event(sctx->list_wait,
3651                            atomic_read(&sctx->bios_in_flight) == 0);
3652
3653                 scrub_pause_on(fs_info);
3654
3655                 /*
3656                  * must be called before we decrease @scrub_paused.
3657                  * make sure we don't block transaction commit while
3658                  * we are waiting pending workers finished.
3659                  */
3660                 wait_event(sctx->list_wait,
3661                            atomic_read(&sctx->workers_pending) == 0);
3662                 sctx->flush_all_writes = false;
3663
3664                 scrub_pause_off(fs_info);
3665
3666                 down_write(&fs_info->dev_replace.rwsem);
3667                 dev_replace->cursor_left = dev_replace->cursor_right;
3668                 dev_replace->item_needs_writeback = 1;
3669                 up_write(&fs_info->dev_replace.rwsem);
3670
3671                 if (ro_set)
3672                         btrfs_dec_block_group_ro(cache);
3673
3674                 /*
3675                  * We might have prevented the cleaner kthread from deleting
3676                  * this block group if it was already unused because we raced
3677                  * and set it to RO mode first. So add it back to the unused
3678                  * list, otherwise it might not ever be deleted unless a manual
3679                  * balance is triggered or it becomes used and unused again.
3680                  */
3681                 spin_lock(&cache->lock);
3682                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3683                     btrfs_block_group_used(&cache->item) == 0) {
3684                         spin_unlock(&cache->lock);
3685                         btrfs_mark_bg_unused(cache);
3686                 } else {
3687                         spin_unlock(&cache->lock);
3688                 }
3689
3690                 btrfs_put_block_group(cache);
3691                 if (ret)
3692                         break;
3693                 if (sctx->is_dev_replace &&
3694                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3695                         ret = -EIO;
3696                         break;
3697                 }
3698                 if (sctx->stat.malloc_errors > 0) {
3699                         ret = -ENOMEM;
3700                         break;
3701                 }
3702 skip:
3703                 key.offset = found_key.offset + length;
3704                 btrfs_release_path(path);
3705         }
3706
3707         btrfs_free_path(path);
3708
3709         return ret;
3710 }
3711
3712 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3713                                            struct btrfs_device *scrub_dev)
3714 {
3715         int     i;
3716         u64     bytenr;
3717         u64     gen;
3718         int     ret;
3719         struct btrfs_fs_info *fs_info = sctx->fs_info;
3720
3721         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
3722                 return -EIO;
3723
3724         /* Seed devices of a new filesystem has their own generation. */
3725         if (scrub_dev->fs_devices != fs_info->fs_devices)
3726                 gen = scrub_dev->generation;
3727         else
3728                 gen = fs_info->last_trans_committed;
3729
3730         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
3731                 bytenr = btrfs_sb_offset(i);
3732                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
3733                     scrub_dev->commit_total_bytes)
3734                         break;
3735
3736                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
3737                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
3738                                   NULL, 1, bytenr);
3739                 if (ret)
3740                         return ret;
3741         }
3742         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3743
3744         return 0;
3745 }
3746
3747 /*
3748  * get a reference count on fs_info->scrub_workers. start worker if necessary
3749  */
3750 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
3751                                                 int is_dev_replace)
3752 {
3753         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
3754         int max_active = fs_info->thread_pool_size;
3755
3756         lockdep_assert_held(&fs_info->scrub_lock);
3757
3758         if (refcount_read(&fs_info->scrub_workers_refcnt) == 0) {
3759                 ASSERT(fs_info->scrub_workers == NULL);
3760                 fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub",
3761                                 flags, is_dev_replace ? 1 : max_active, 4);
3762                 if (!fs_info->scrub_workers)
3763                         goto fail_scrub_workers;
3764
3765                 ASSERT(fs_info->scrub_wr_completion_workers == NULL);
3766                 fs_info->scrub_wr_completion_workers =
3767                         btrfs_alloc_workqueue(fs_info, "scrubwrc", flags,
3768                                               max_active, 2);
3769                 if (!fs_info->scrub_wr_completion_workers)
3770                         goto fail_scrub_wr_completion_workers;
3771
3772                 ASSERT(fs_info->scrub_parity_workers == NULL);
3773                 fs_info->scrub_parity_workers =
3774                         btrfs_alloc_workqueue(fs_info, "scrubparity", flags,
3775                                               max_active, 2);
3776                 if (!fs_info->scrub_parity_workers)
3777                         goto fail_scrub_parity_workers;
3778
3779                 refcount_set(&fs_info->scrub_workers_refcnt, 1);
3780         } else {
3781                 refcount_inc(&fs_info->scrub_workers_refcnt);
3782         }
3783         return 0;
3784
3785 fail_scrub_parity_workers:
3786         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3787 fail_scrub_wr_completion_workers:
3788         btrfs_destroy_workqueue(fs_info->scrub_workers);
3789 fail_scrub_workers:
3790         return -ENOMEM;
3791 }
3792
3793 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
3794                     u64 end, struct btrfs_scrub_progress *progress,
3795                     int readonly, int is_dev_replace)
3796 {
3797         struct scrub_ctx *sctx;
3798         int ret;
3799         struct btrfs_device *dev;
3800         unsigned int nofs_flag;
3801         struct btrfs_workqueue *scrub_workers = NULL;
3802         struct btrfs_workqueue *scrub_wr_comp = NULL;
3803         struct btrfs_workqueue *scrub_parity = NULL;
3804
3805         if (btrfs_fs_closing(fs_info))
3806                 return -EAGAIN;
3807
3808         if (fs_info->nodesize > BTRFS_STRIPE_LEN) {
3809                 /*
3810                  * in this case scrub is unable to calculate the checksum
3811                  * the way scrub is implemented. Do not handle this
3812                  * situation at all because it won't ever happen.
3813                  */
3814                 btrfs_err(fs_info,
3815                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
3816                        fs_info->nodesize,
3817                        BTRFS_STRIPE_LEN);
3818                 return -EINVAL;
3819         }
3820
3821         if (fs_info->sectorsize != PAGE_SIZE) {
3822                 /* not supported for data w/o checksums */
3823                 btrfs_err_rl(fs_info,
3824                            "scrub: size assumption sectorsize != PAGE_SIZE (%d != %lu) fails",
3825                        fs_info->sectorsize, PAGE_SIZE);
3826                 return -EINVAL;
3827         }
3828
3829         if (fs_info->nodesize >
3830             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
3831             fs_info->sectorsize > PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
3832                 /*
3833                  * would exhaust the array bounds of pagev member in
3834                  * struct scrub_block
3835                  */
3836                 btrfs_err(fs_info,
3837                           "scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
3838                        fs_info->nodesize,
3839                        SCRUB_MAX_PAGES_PER_BLOCK,
3840                        fs_info->sectorsize,
3841                        SCRUB_MAX_PAGES_PER_BLOCK);
3842                 return -EINVAL;
3843         }
3844
3845         /* Allocate outside of device_list_mutex */
3846         sctx = scrub_setup_ctx(fs_info, is_dev_replace);
3847         if (IS_ERR(sctx))
3848                 return PTR_ERR(sctx);
3849
3850         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3851         dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
3852         if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) &&
3853                      !is_dev_replace)) {
3854                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3855                 ret = -ENODEV;
3856                 goto out_free_ctx;
3857         }
3858
3859         if (!is_dev_replace && !readonly &&
3860             !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
3861                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3862                 btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable",
3863                                 rcu_str_deref(dev->name));
3864                 ret = -EROFS;
3865                 goto out_free_ctx;
3866         }
3867
3868         mutex_lock(&fs_info->scrub_lock);
3869         if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
3870             test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) {
3871                 mutex_unlock(&fs_info->scrub_lock);
3872                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3873                 ret = -EIO;
3874                 goto out_free_ctx;
3875         }
3876
3877         down_read(&fs_info->dev_replace.rwsem);
3878         if (dev->scrub_ctx ||
3879             (!is_dev_replace &&
3880              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
3881                 up_read(&fs_info->dev_replace.rwsem);
3882                 mutex_unlock(&fs_info->scrub_lock);
3883                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3884                 ret = -EINPROGRESS;
3885                 goto out_free_ctx;
3886         }
3887         up_read(&fs_info->dev_replace.rwsem);
3888
3889         ret = scrub_workers_get(fs_info, is_dev_replace);
3890         if (ret) {
3891                 mutex_unlock(&fs_info->scrub_lock);
3892                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3893                 goto out_free_ctx;
3894         }
3895
3896         sctx->readonly = readonly;
3897         dev->scrub_ctx = sctx;
3898         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3899
3900         /*
3901          * checking @scrub_pause_req here, we can avoid
3902          * race between committing transaction and scrubbing.
3903          */
3904         __scrub_blocked_if_needed(fs_info);
3905         atomic_inc(&fs_info->scrubs_running);
3906         mutex_unlock(&fs_info->scrub_lock);
3907
3908         /*
3909          * In order to avoid deadlock with reclaim when there is a transaction
3910          * trying to pause scrub, make sure we use GFP_NOFS for all the
3911          * allocations done at btrfs_scrub_pages() and scrub_pages_for_parity()
3912          * invoked by our callees. The pausing request is done when the
3913          * transaction commit starts, and it blocks the transaction until scrub
3914          * is paused (done at specific points at scrub_stripe() or right above
3915          * before incrementing fs_info->scrubs_running).
3916          */
3917         nofs_flag = memalloc_nofs_save();
3918         if (!is_dev_replace) {
3919                 btrfs_info(fs_info, "scrub: started on devid %llu", devid);
3920                 /*
3921                  * by holding device list mutex, we can
3922                  * kick off writing super in log tree sync.
3923                  */
3924                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
3925                 ret = scrub_supers(sctx, dev);
3926                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3927         }
3928
3929         if (!ret)
3930                 ret = scrub_enumerate_chunks(sctx, dev, start, end);
3931         memalloc_nofs_restore(nofs_flag);
3932
3933         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3934         atomic_dec(&fs_info->scrubs_running);
3935         wake_up(&fs_info->scrub_pause_wait);
3936
3937         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3938
3939         if (progress)
3940                 memcpy(progress, &sctx->stat, sizeof(*progress));
3941
3942         if (!is_dev_replace)
3943                 btrfs_info(fs_info, "scrub: %s on devid %llu with status: %d",
3944                         ret ? "not finished" : "finished", devid, ret);
3945
3946         mutex_lock(&fs_info->scrub_lock);
3947         dev->scrub_ctx = NULL;
3948         if (refcount_dec_and_test(&fs_info->scrub_workers_refcnt)) {
3949                 scrub_workers = fs_info->scrub_workers;
3950                 scrub_wr_comp = fs_info->scrub_wr_completion_workers;
3951                 scrub_parity = fs_info->scrub_parity_workers;
3952
3953                 fs_info->scrub_workers = NULL;
3954                 fs_info->scrub_wr_completion_workers = NULL;
3955                 fs_info->scrub_parity_workers = NULL;
3956         }
3957         mutex_unlock(&fs_info->scrub_lock);
3958
3959         btrfs_destroy_workqueue(scrub_workers);
3960         btrfs_destroy_workqueue(scrub_wr_comp);
3961         btrfs_destroy_workqueue(scrub_parity);
3962         scrub_put_ctx(sctx);
3963
3964         return ret;
3965
3966 out_free_ctx:
3967         scrub_free_ctx(sctx);
3968
3969         return ret;
3970 }
3971
3972 void btrfs_scrub_pause(struct btrfs_fs_info *fs_info)
3973 {
3974         mutex_lock(&fs_info->scrub_lock);
3975         atomic_inc(&fs_info->scrub_pause_req);
3976         while (atomic_read(&fs_info->scrubs_paused) !=
3977                atomic_read(&fs_info->scrubs_running)) {
3978                 mutex_unlock(&fs_info->scrub_lock);
3979                 wait_event(fs_info->scrub_pause_wait,
3980                            atomic_read(&fs_info->scrubs_paused) ==
3981                            atomic_read(&fs_info->scrubs_running));
3982                 mutex_lock(&fs_info->scrub_lock);
3983         }
3984         mutex_unlock(&fs_info->scrub_lock);
3985 }
3986
3987 void btrfs_scrub_continue(struct btrfs_fs_info *fs_info)
3988 {
3989         atomic_dec(&fs_info->scrub_pause_req);
3990         wake_up(&fs_info->scrub_pause_wait);
3991 }
3992
3993 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
3994 {
3995         mutex_lock(&fs_info->scrub_lock);
3996         if (!atomic_read(&fs_info->scrubs_running)) {
3997                 mutex_unlock(&fs_info->scrub_lock);
3998                 return -ENOTCONN;
3999         }
4000
4001         atomic_inc(&fs_info->scrub_cancel_req);
4002         while (atomic_read(&fs_info->scrubs_running)) {
4003                 mutex_unlock(&fs_info->scrub_lock);
4004                 wait_event(fs_info->scrub_pause_wait,
4005                            atomic_read(&fs_info->scrubs_running) == 0);
4006                 mutex_lock(&fs_info->scrub_lock);
4007         }
4008         atomic_dec(&fs_info->scrub_cancel_req);
4009         mutex_unlock(&fs_info->scrub_lock);
4010
4011         return 0;
4012 }
4013
4014 int btrfs_scrub_cancel_dev(struct btrfs_device *dev)
4015 {
4016         struct btrfs_fs_info *fs_info = dev->fs_info;
4017         struct scrub_ctx *sctx;
4018
4019         mutex_lock(&fs_info->scrub_lock);
4020         sctx = dev->scrub_ctx;
4021         if (!sctx) {
4022                 mutex_unlock(&fs_info->scrub_lock);
4023                 return -ENOTCONN;
4024         }
4025         atomic_inc(&sctx->cancel_req);
4026         while (dev->scrub_ctx) {
4027                 mutex_unlock(&fs_info->scrub_lock);
4028                 wait_event(fs_info->scrub_pause_wait,
4029                            dev->scrub_ctx == NULL);
4030                 mutex_lock(&fs_info->scrub_lock);
4031         }
4032         mutex_unlock(&fs_info->scrub_lock);
4033
4034         return 0;
4035 }
4036
4037 int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
4038                          struct btrfs_scrub_progress *progress)
4039 {
4040         struct btrfs_device *dev;
4041         struct scrub_ctx *sctx = NULL;
4042
4043         mutex_lock(&fs_info->fs_devices->device_list_mutex);
4044         dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
4045         if (dev)
4046                 sctx = dev->scrub_ctx;
4047         if (sctx)
4048                 memcpy(progress, &sctx->stat, sizeof(*progress));
4049         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4050
4051         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
4052 }
4053
4054 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
4055                                u64 extent_logical, u64 extent_len,
4056                                u64 *extent_physical,
4057                                struct btrfs_device **extent_dev,
4058                                int *extent_mirror_num)
4059 {
4060         u64 mapped_length;
4061         struct btrfs_bio *bbio = NULL;
4062         int ret;
4063
4064         mapped_length = extent_len;
4065         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, extent_logical,
4066                               &mapped_length, &bbio, 0);
4067         if (ret || !bbio || mapped_length < extent_len ||
4068             !bbio->stripes[0].dev->bdev) {
4069                 btrfs_put_bbio(bbio);
4070                 return;
4071         }
4072
4073         *extent_physical = bbio->stripes[0].physical;
4074         *extent_mirror_num = bbio->mirror_num;
4075         *extent_dev = bbio->stripes[0].dev;
4076         btrfs_put_bbio(bbio);
4077 }