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 "ctree.h"
  10 #include "volumes.h"
  11 #include "disk-io.h"
  12 #include "ordered-data.h"
  13 #include "transaction.h"
  14 #include "backref.h"
  15 #include "extent_io.h"
  16 #include "dev-replace.h"
  17 #include "check-integrity.h"
  18 #include "rcu-string.h"
  19 #include "raid56.h"
  20
  21 /*
  22  * This is only the first step towards a full-features scrub. It reads all
  23  * extent and super block and verifies the checksums. In case a bad checksum
  24  * is found or the extent cannot be read, good data will be written back if
  25  * any can be found.
  26  *
  27  * Future enhancements:
  28  *  - In case an unrepairable extent is encountered, track which files are
  29  *    affected and report them
  30  *  - track and record media errors, throw out bad devices
  31  *  - add a mode to also read unallocated space
  32  */
  33
  34 struct scrub_block;
  35 struct scrub_ctx;
  36
  37 /*
  38  * the following three values only influence the performance.
  39  * The last one configures the number of parallel and outstanding I/O
  40  * operations. The first two values configure an upper limit for the number
  41  * of (dynamically allocated) pages that are added to a bio.
  42  */
  43 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  44 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  45 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  46
  47 /*
  48  * the following value times PAGE_SIZE needs to be large enough to match the
  49  * largest node/leaf/sector size that shall be supported.
  50  * Values larger than BTRFS_STRIPE_LEN are not supported.
  51  */
  52 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  53
  54 struct scrub_recover {
  55         refcount_t              refs;
  56         struct btrfs_bio        *bbio;
  57         u64                     map_length;
  58 };
  59
  60 struct scrub_page {
  61         struct scrub_block      *sblock;
  62         struct page             *page;
  63         struct btrfs_device     *dev;
  64         struct list_head        list;
  65         u64                     flags;  /* extent flags */
  66         u64                     generation;
  67         u64                     logical;
  68         u64                     physical;
  69         u64                     physical_for_dev_replace;
  70         atomic_t                refs;
  71         struct {
  72                 unsigned int    mirror_num:8;
  73                 unsigned int    have_csum:1;
  74                 unsigned int    io_error:1;
  75         };
  76         u8                      csum[BTRFS_CSUM_SIZE];
  77
  78         struct scrub_recover    *recover;
  79 };
  80
  81 struct scrub_bio {
  82         int                     index;
  83         struct scrub_ctx        *sctx;
  84         struct btrfs_device     *dev;
  85         struct bio              *bio;
  86         blk_status_t            status;
  87         u64                     logical;
  88         u64                     physical;
  89 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
  90         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
  91 #else
  92         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
  93 #endif
  94         int                     page_count;
  95         int                     next_free;
  96         struct btrfs_work       work;
  97 };
  98
  99 struct scrub_block {
 100         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 101         int                     page_count;
 102         atomic_t                outstanding_pages;
 103         refcount_t              refs; /* free mem on transition to zero */
 104         struct scrub_ctx        *sctx;
 105         struct scrub_parity     *sparity;
 106         struct {
 107                 unsigned int    header_error:1;
 108                 unsigned int    checksum_error:1;
 109                 unsigned int    no_io_error_seen:1;
 110                 unsigned int    generation_error:1; /* also sets header_error */
 111
 112                 /* The following is for the data used to check parity */
 113                 /* It is for the data with checksum */
 114                 unsigned int    data_corrected:1;
 115         };
 116         struct btrfs_work       work;
 117 };
 118
 119 /* Used for the chunks with parity stripe such RAID5/6 */
 120 struct scrub_parity {
 121         struct scrub_ctx        *sctx;
 122
 123         struct btrfs_device     *scrub_dev;
 124
 125         u64                     logic_start;
 126
 127         u64                     logic_end;
 128
 129         int                     nsectors;
 130
 131         u64                     stripe_len;
 132
 133         refcount_t              refs;
 134
 135         struct list_head        spages;
 136
 137         /* Work of parity check and repair */
 138         struct btrfs_work       work;
 139
 140         /* Mark the parity blocks which have data */
 141         unsigned long           *dbitmap;
 142
 143         /*
 144          * Mark the parity blocks which have data, but errors happen when
 145          * read data or check data
 146          */
 147         unsigned long           *ebitmap;
 148
 149         unsigned long           bitmap[0];
 150 };
 151
 152 struct scrub_ctx {
 153         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 154         struct btrfs_fs_info    *fs_info;
 155         int                     first_free;
 156         int                     curr;
 157         atomic_t                bios_in_flight;
 158         atomic_t                workers_pending;
 159         spinlock_t              list_lock;
 160         wait_queue_head_t       list_wait;
 161         u16                     csum_size;
 162         struct list_head        csum_list;
 163         atomic_t                cancel_req;
 164         int                     readonly;
 165         int                     pages_per_rd_bio;
 166
 167         int                     is_dev_replace;
 168
 169         struct scrub_bio        *wr_curr_bio;
 170         struct mutex            wr_lock;
 171         int                     pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 172         struct btrfs_device     *wr_tgtdev;
 173         bool                    flush_all_writes;
 174
 175         /*
 176          * statistics
 177          */
 178         struct btrfs_scrub_progress stat;
 179         spinlock_t              stat_lock;
 180
 181         /*
 182          * Use a ref counter to avoid use-after-free issues. Scrub workers
 183          * decrement bios_in_flight and workers_pending and then do a wakeup
 184          * on the list_wait wait queue. We must ensure the main scrub task
 185          * doesn't free the scrub context before or while the workers are
 186          * doing the wakeup() call.
 187          */
 188         refcount_t              refs;
 189 };
 190
 191 struct scrub_warning {
 192         struct btrfs_path       *path;
 193         u64                     extent_item_size;
 194         const char              *errstr;
 195         u64                     physical;
 196         u64                     logical;
 197         struct btrfs_device     *dev;
 198 };
 199
 200 struct full_stripe_lock {
 201         struct rb_node node;
 202         u64 logical;
 203         u64 refs;
 204         struct mutex mutex;
 205 };
 206
 207 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 208 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 209 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 210 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 211                                      struct scrub_block *sblocks_for_recheck);
 212 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 213                                 struct scrub_block *sblock,
 214                                 int retry_failed_mirror);
 215 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 216 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 217                                              struct scrub_block *sblock_good);
 218 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 219                                             struct scrub_block *sblock_good,
 220                                             int page_num, int force_write);
 221 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 222 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 223                                            int page_num);
 224 static int scrub_checksum_data(struct scrub_block *sblock);
 225 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 226 static int scrub_checksum_super(struct scrub_block *sblock);
 227 static void scrub_block_get(struct scrub_block *sblock);
 228 static void scrub_block_put(struct scrub_block *sblock);
 229 static void scrub_page_get(struct scrub_page *spage);
 230 static void scrub_page_put(struct scrub_page *spage);
 231 static void scrub_parity_get(struct scrub_parity *sparity);
 232 static void scrub_parity_put(struct scrub_parity *sparity);
 233 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 234                                     struct scrub_page *spage);
 235 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 236                        u64 physical, struct btrfs_device *dev, u64 flags,
 237                        u64 gen, int mirror_num, u8 *csum, int force,
 238                        u64 physical_for_dev_replace);
 239 static void scrub_bio_end_io(struct bio *bio);
 240 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 241 static void scrub_block_complete(struct scrub_block *sblock);
 242 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 243                                u64 extent_logical, u64 extent_len,
 244                                u64 *extent_physical,
 245                                struct btrfs_device **extent_dev,
 246                                int *extent_mirror_num);
 247 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 248                                     struct scrub_page *spage);
 249 static void scrub_wr_submit(struct scrub_ctx *sctx);
 250 static void scrub_wr_bio_end_io(struct bio *bio);
 251 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 252 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 253 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 254 static void scrub_put_ctx(struct scrub_ctx *sctx);
 255
 256 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
 257 {
 258         return page->recover &&
 259                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
 260 }
 261
 262 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 263 {
 264         refcount_inc(&sctx->refs);
 265         atomic_inc(&sctx->bios_in_flight);
 266 }
 267
 268 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 269 {
 270         atomic_dec(&sctx->bios_in_flight);
 271         wake_up(&sctx->list_wait);
 272         scrub_put_ctx(sctx);
 273 }
 274
 275 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 276 {
 277         while (atomic_read(&fs_info->scrub_pause_req)) {
 278                 mutex_unlock(&fs_info->scrub_lock);
 279                 wait_event(fs_info->scrub_pause_wait,
 280                    atomic_read(&fs_info->scrub_pause_req) == 0);
 281                 mutex_lock(&fs_info->scrub_lock);
 282         }
 283 }
 284
 285 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 286 {
 287         atomic_inc(&fs_info->scrubs_paused);
 288         wake_up(&fs_info->scrub_pause_wait);
 289 }
 290
 291 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 292 {
 293         mutex_lock(&fs_info->scrub_lock);
 294         __scrub_blocked_if_needed(fs_info);
 295         atomic_dec(&fs_info->scrubs_paused);
 296         mutex_unlock(&fs_info->scrub_lock);
 297
 298         wake_up(&fs_info->scrub_pause_wait);
 299 }
 300
 301 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 302 {
 303         scrub_pause_on(fs_info);
 304         scrub_pause_off(fs_info);
 305 }
 306
 307 /*
 308  * Insert new full stripe lock into full stripe locks tree
 309  *
 310  * Return pointer to existing or newly inserted full_stripe_lock structure if
 311  * everything works well.
 312  * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
 313  *
 314  * NOTE: caller must hold full_stripe_locks_root->lock before calling this
 315  * function
 316  */
 317 static struct full_stripe_lock *insert_full_stripe_lock(
 318                 struct btrfs_full_stripe_locks_tree *locks_root,
 319                 u64 fstripe_logical)
 320 {
 321         struct rb_node **p;
 322         struct rb_node *parent = NULL;
 323         struct full_stripe_lock *entry;
 324         struct full_stripe_lock *ret;
 325
 326         lockdep_assert_held(&locks_root->lock);
 327
 328         p = &locks_root->root.rb_node;
 329         while (*p) {
 330                 parent = *p;
 331                 entry = rb_entry(parent, struct full_stripe_lock, node);
 332                 if (fstripe_logical < entry->logical) {
 333                         p = &(*p)->rb_left;
 334                 } else if (fstripe_logical > entry->logical) {
 335                         p = &(*p)->rb_right;
 336                 } else {
 337                         entry->refs++;
 338                         return entry;
 339                 }
 340         }
 341
 342         /* Insert new lock */
 343         ret = kmalloc(sizeof(*ret), GFP_KERNEL);
 344         if (!ret)
 345                 return ERR_PTR(-ENOMEM);
 346         ret->logical = fstripe_logical;
 347         ret->refs = 1;
 348         mutex_init(&ret->mutex);
 349
 350         rb_link_node(&ret->node, parent, p);
 351         rb_insert_color(&ret->node, &locks_root->root);
 352         return ret;
 353 }
 354
 355 /*
 356  * Search for a full stripe lock of a block group
 357  *
 358  * Return pointer to existing full stripe lock if found
 359  * Return NULL if not found
 360  */
 361 static struct full_stripe_lock *search_full_stripe_lock(
 362                 struct btrfs_full_stripe_locks_tree *locks_root,
 363                 u64 fstripe_logical)
 364 {
 365         struct rb_node *node;
 366         struct full_stripe_lock *entry;
 367
 368         lockdep_assert_held(&locks_root->lock);
 369
 370         node = locks_root->root.rb_node;
 371         while (node) {
 372                 entry = rb_entry(node, struct full_stripe_lock, node);
 373                 if (fstripe_logical < entry->logical)
 374                         node = node->rb_left;
 375                 else if (fstripe_logical > entry->logical)
 376                         node = node->rb_right;
 377                 else
 378                         return entry;
 379         }
 380         return NULL;
 381 }
 382
 383 /*
 384  * Helper to get full stripe logical from a normal bytenr.
 385  *
 386  * Caller must ensure @cache is a RAID56 block group.
 387  */
 388 static u64 get_full_stripe_logical(struct btrfs_block_group_cache *cache,
 389                                    u64 bytenr)
 390 {
 391         u64 ret;
 392
 393         /*
 394          * Due to chunk item size limit, full stripe length should not be
 395          * larger than U32_MAX. Just a sanity check here.
 396          */
 397         WARN_ON_ONCE(cache->full_stripe_len >= U32_MAX);
 398
 399         /*
 400          * round_down() can only handle power of 2, while RAID56 full
 401          * stripe length can be 64KiB * n, so we need to manually round down.
 402          */
 403         ret = div64_u64(bytenr - cache->key.objectid, cache->full_stripe_len) *
 404                 cache->full_stripe_len + cache->key.objectid;
 405         return ret;
 406 }
 407
 408 /*
 409  * Lock a full stripe to avoid concurrency of recovery and read
 410  *
 411  * It's only used for profiles with parities (RAID5/6), for other profiles it
 412  * does nothing.
 413  *
 414  * Return 0 if we locked full stripe covering @bytenr, with a mutex held.
 415  * So caller must call unlock_full_stripe() at the same context.
 416  *
 417  * Return <0 if encounters error.
 418  */
 419 static int lock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 420                             bool *locked_ret)
 421 {
 422         struct btrfs_block_group_cache *bg_cache;
 423         struct btrfs_full_stripe_locks_tree *locks_root;
 424         struct full_stripe_lock *existing;
 425         u64 fstripe_start;
 426         int ret = 0;
 427
 428         *locked_ret = false;
 429         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 430         if (!bg_cache) {
 431                 ASSERT(0);
 432                 return -ENOENT;
 433         }
 434
 435         /* Profiles not based on parity don't need full stripe lock */
 436         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 437                 goto out;
 438         locks_root = &bg_cache->full_stripe_locks_root;
 439
 440         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 441
 442         /* Now insert the full stripe lock */
 443         mutex_lock(&locks_root->lock);
 444         existing = insert_full_stripe_lock(locks_root, fstripe_start);
 445         mutex_unlock(&locks_root->lock);
 446         if (IS_ERR(existing)) {
 447                 ret = PTR_ERR(existing);
 448                 goto out;
 449         }
 450         mutex_lock(&existing->mutex);
 451         *locked_ret = true;
 452 out:
 453         btrfs_put_block_group(bg_cache);
 454         return ret;
 455 }
 456
 457 /*
 458  * Unlock a full stripe.
 459  *
 460  * NOTE: Caller must ensure it's the same context calling corresponding
 461  * lock_full_stripe().
 462  *
 463  * Return 0 if we unlock full stripe without problem.
 464  * Return <0 for error
 465  */
 466 static int unlock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 467                               bool locked)
 468 {
 469         struct btrfs_block_group_cache *bg_cache;
 470         struct btrfs_full_stripe_locks_tree *locks_root;
 471         struct full_stripe_lock *fstripe_lock;
 472         u64 fstripe_start;
 473         bool freeit = false;
 474         int ret = 0;
 475
 476         /* If we didn't acquire full stripe lock, no need to continue */
 477         if (!locked)
 478                 return 0;
 479
 480         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 481         if (!bg_cache) {
 482                 ASSERT(0);
 483                 return -ENOENT;
 484         }
 485         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 486                 goto out;
 487
 488         locks_root = &bg_cache->full_stripe_locks_root;
 489         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 490
 491         mutex_lock(&locks_root->lock);
 492         fstripe_lock = search_full_stripe_lock(locks_root, fstripe_start);
 493         /* Unpaired unlock_full_stripe() detected */
 494         if (!fstripe_lock) {
 495                 WARN_ON(1);
 496                 ret = -ENOENT;
 497                 mutex_unlock(&locks_root->lock);
 498                 goto out;
 499         }
 500
 501         if (fstripe_lock->refs == 0) {
 502                 WARN_ON(1);
 503                 btrfs_warn(fs_info, "full stripe lock at %llu refcount underflow",
 504                         fstripe_lock->logical);
 505         } else {
 506                 fstripe_lock->refs--;
 507         }
 508
 509         if (fstripe_lock->refs == 0) {
 510                 rb_erase(&fstripe_lock->node, &locks_root->root);
 511                 freeit = true;
 512         }
 513         mutex_unlock(&locks_root->lock);
 514
 515         mutex_unlock(&fstripe_lock->mutex);
 516         if (freeit)
 517                 kfree(fstripe_lock);
 518 out:
 519         btrfs_put_block_group(bg_cache);
 520         return ret;
 521 }
 522
 523 static void scrub_free_csums(struct scrub_ctx *sctx)
 524 {
 525         while (!list_empty(&sctx->csum_list)) {
 526                 struct btrfs_ordered_sum *sum;
 527                 sum = list_first_entry(&sctx->csum_list,
 528                                        struct btrfs_ordered_sum, list);
 529                 list_del(&sum->list);
 530                 kfree(sum);
 531         }
 532 }
 533
 534 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 535 {
 536         int i;
 537
 538         if (!sctx)
 539                 return;
 540
 541         /* this can happen when scrub is cancelled */
 542         if (sctx->curr != -1) {
 543                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 544
 545                 for (i = 0; i < sbio->page_count; i++) {
 546                         WARN_ON(!sbio->pagev[i]->page);
 547                         scrub_block_put(sbio->pagev[i]->sblock);
 548                 }
 549                 bio_put(sbio->bio);
 550         }
 551
 552         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 553                 struct scrub_bio *sbio = sctx->bios[i];
 554
 555                 if (!sbio)
 556                         break;
 557                 kfree(sbio);
 558         }
 559
 560         kfree(sctx->wr_curr_bio);
 561         scrub_free_csums(sctx);
 562         kfree(sctx);
 563 }
 564
 565 static void scrub_put_ctx(struct scrub_ctx *sctx)
 566 {
 567         if (refcount_dec_and_test(&sctx->refs))
 568                 scrub_free_ctx(sctx);
 569 }
 570
 571 static noinline_for_stack
 572 struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 573 {
 574         struct scrub_ctx *sctx;
 575         int             i;
 576         struct btrfs_fs_info *fs_info = dev->fs_info;
 577
 578         sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 579         if (!sctx)
 580                 goto nomem;
 581         refcount_set(&sctx->refs, 1);
 582         sctx->is_dev_replace = is_dev_replace;
 583         sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 584         sctx->curr = -1;
 585         sctx->fs_info = dev->fs_info;
 586         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 587                 struct scrub_bio *sbio;
 588
 589                 sbio = kzalloc(sizeof(*sbio), GFP_KERNEL);
 590                 if (!sbio)
 591                         goto nomem;
 592                 sctx->bios[i] = sbio;
 593
 594                 sbio->index = i;
 595                 sbio->sctx = sctx;
 596                 sbio->page_count = 0;
 597                 btrfs_init_work(&sbio->work, btrfs_scrub_helper,
 598                                 scrub_bio_end_io_worker, NULL, NULL);
 599
 600                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 601                         sctx->bios[i]->next_free = i + 1;
 602                 else
 603                         sctx->bios[i]->next_free = -1;
 604         }
 605         sctx->first_free = 0;
 606         atomic_set(&sctx->bios_in_flight, 0);
 607         atomic_set(&sctx->workers_pending, 0);
 608         atomic_set(&sctx->cancel_req, 0);
 609         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 610         INIT_LIST_HEAD(&sctx->csum_list);
 611
 612         spin_lock_init(&sctx->list_lock);
 613         spin_lock_init(&sctx->stat_lock);
 614         init_waitqueue_head(&sctx->list_wait);
 615
 616         WARN_ON(sctx->wr_curr_bio != NULL);
 617         mutex_init(&sctx->wr_lock);
 618         sctx->wr_curr_bio = NULL;
 619         if (is_dev_replace) {
 620                 WARN_ON(!fs_info->dev_replace.tgtdev);
 621                 sctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
 622                 sctx->wr_tgtdev = fs_info->dev_replace.tgtdev;
 623                 sctx->flush_all_writes = false;
 624         }
 625
 626         return sctx;
 627
 628 nomem:
 629         scrub_free_ctx(sctx);
 630         return ERR_PTR(-ENOMEM);
 631 }
 632
 633 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 634                                      void *warn_ctx)
 635 {
 636         u64 isize;
 637         u32 nlink;
 638         int ret;
 639         int i;
 640         unsigned nofs_flag;
 641         struct extent_buffer *eb;
 642         struct btrfs_inode_item *inode_item;
 643         struct scrub_warning *swarn = warn_ctx;
 644         struct btrfs_fs_info *fs_info = swarn->dev->fs_info;
 645         struct inode_fs_paths *ipath = NULL;
 646         struct btrfs_root *local_root;
 647         struct btrfs_key root_key;
 648         struct btrfs_key key;
 649
 650         root_key.objectid = root;
 651         root_key.type = BTRFS_ROOT_ITEM_KEY;
 652         root_key.offset = (u64)-1;
 653         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 654         if (IS_ERR(local_root)) {
 655                 ret = PTR_ERR(local_root);
 656                 goto err;
 657         }
 658
 659         /*
 660          * this makes the path point to (inum INODE_ITEM ioff)
 661          */
 662         key.objectid = inum;
 663         key.type = BTRFS_INODE_ITEM_KEY;
 664         key.offset = 0;
 665
 666         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 667         if (ret) {
 668                 btrfs_release_path(swarn->path);
 669                 goto err;
 670         }
 671
 672         eb = swarn->path->nodes[0];
 673         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 674                                         struct btrfs_inode_item);
 675         isize = btrfs_inode_size(eb, inode_item);
 676         nlink = btrfs_inode_nlink(eb, inode_item);
 677         btrfs_release_path(swarn->path);
 678
 679         /*
 680          * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
 681          * uses GFP_NOFS in this context, so we keep it consistent but it does
 682          * not seem to be strictly necessary.
 683          */
 684         nofs_flag = memalloc_nofs_save();
 685         ipath = init_ipath(4096, local_root, swarn->path);
 686         memalloc_nofs_restore(nofs_flag);
 687         if (IS_ERR(ipath)) {
 688                 ret = PTR_ERR(ipath);
 689                 ipath = NULL;
 690                 goto err;
 691         }
 692         ret = paths_from_inode(inum, ipath);
 693
 694         if (ret < 0)
 695                 goto err;
 696
 697         /*
 698          * we deliberately ignore the bit ipath might have been too small to
 699          * hold all of the paths here
 700          */
 701         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 702                 btrfs_warn_in_rcu(fs_info,
 703 "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu, length %llu, links %u (path: %s)",
 704                                   swarn->errstr, swarn->logical,
 705                                   rcu_str_deref(swarn->dev->name),
 706                                   swarn->physical,
 707                                   root, inum, offset,
 708                                   min(isize - offset, (u64)PAGE_SIZE), nlink,
 709                                   (char *)(unsigned long)ipath->fspath->val[i]);
 710
 711         free_ipath(ipath);
 712         return 0;
 713
 714 err:
 715         btrfs_warn_in_rcu(fs_info,
 716                           "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu: path resolving failed with ret=%d",
 717                           swarn->errstr, swarn->logical,
 718                           rcu_str_deref(swarn->dev->name),
 719                           swarn->physical,
 720                           root, inum, offset, ret);
 721
 722         free_ipath(ipath);
 723         return 0;
 724 }
 725
 726 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 727 {
 728         struct btrfs_device *dev;
 729         struct btrfs_fs_info *fs_info;
 730         struct btrfs_path *path;
 731         struct btrfs_key found_key;
 732         struct extent_buffer *eb;
 733         struct btrfs_extent_item *ei;
 734         struct scrub_warning swarn;
 735         unsigned long ptr = 0;
 736         u64 extent_item_pos;
 737         u64 flags = 0;
 738         u64 ref_root;
 739         u32 item_size;
 740         u8 ref_level = 0;
 741         int ret;
 742
 743         WARN_ON(sblock->page_count < 1);
 744         dev = sblock->pagev[0]->dev;
 745         fs_info = sblock->sctx->fs_info;
 746
 747         path = btrfs_alloc_path();
 748         if (!path)
 749                 return;
 750
 751         swarn.physical = sblock->pagev[0]->physical;
 752         swarn.logical = sblock->pagev[0]->logical;
 753         swarn.errstr = errstr;
 754         swarn.dev = NULL;
 755
 756         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 757                                   &flags);
 758         if (ret < 0)
 759                 goto out;
 760
 761         extent_item_pos = swarn.logical - found_key.objectid;
 762         swarn.extent_item_size = found_key.offset;
 763
 764         eb = path->nodes[0];
 765         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 766         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 767
 768         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 769                 do {
 770                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 771                                                       item_size, &ref_root,
 772                                                       &ref_level);
 773                         btrfs_warn_in_rcu(fs_info,
 774 "%s at logical %llu on dev %s, physical %llu: metadata %s (level %d) in tree %llu",
 775                                 errstr, swarn.logical,
 776                                 rcu_str_deref(dev->name),
 777                                 swarn.physical,
 778                                 ref_level ? "node" : "leaf",
 779                                 ret < 0 ? -1 : ref_level,
 780                                 ret < 0 ? -1 : ref_root);
 781                 } while (ret != 1);
 782                 btrfs_release_path(path);
 783         } else {
 784                 btrfs_release_path(path);
 785                 swarn.path = path;
 786                 swarn.dev = dev;
 787                 iterate_extent_inodes(fs_info, found_key.objectid,
 788                                         extent_item_pos, 1,
 789                                         scrub_print_warning_inode, &swarn, false);
 790         }
 791
 792 out:
 793         btrfs_free_path(path);
 794 }
 795
 796 static inline void scrub_get_recover(struct scrub_recover *recover)
 797 {
 798         refcount_inc(&recover->refs);
 799 }
 800
 801 static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
 802                                      struct scrub_recover *recover)
 803 {
 804         if (refcount_dec_and_test(&recover->refs)) {
 805                 btrfs_bio_counter_dec(fs_info);
 806                 btrfs_put_bbio(recover->bbio);
 807                 kfree(recover);
 808         }
 809 }
 810
 811 /*
 812  * scrub_handle_errored_block gets called when either verification of the
 813  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 814  * case, this function handles all pages in the bio, even though only one
 815  * may be bad.
 816  * The goal of this function is to repair the errored block by using the
 817  * contents of one of the mirrors.
 818  */
 819 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 820 {
 821         struct scrub_ctx *sctx = sblock_to_check->sctx;
 822         struct btrfs_device *dev;
 823         struct btrfs_fs_info *fs_info;
 824         u64 logical;
 825         unsigned int failed_mirror_index;
 826         unsigned int is_metadata;
 827         unsigned int have_csum;
 828         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 829         struct scrub_block *sblock_bad;
 830         int ret;
 831         int mirror_index;
 832         int page_num;
 833         int success;
 834         bool full_stripe_locked;
 835         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 836                                       DEFAULT_RATELIMIT_BURST);
 837
 838         BUG_ON(sblock_to_check->page_count < 1);
 839         fs_info = sctx->fs_info;
 840         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 841                 /*
 842                  * if we find an error in a super block, we just report it.
 843                  * They will get written with the next transaction commit
 844                  * anyway
 845                  */
 846                 spin_lock(&sctx->stat_lock);
 847                 ++sctx->stat.super_errors;
 848                 spin_unlock(&sctx->stat_lock);
 849                 return 0;
 850         }
 851         logical = sblock_to_check->pagev[0]->logical;
 852         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 853         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 854         is_metadata = !(sblock_to_check->pagev[0]->flags &
 855                         BTRFS_EXTENT_FLAG_DATA);
 856         have_csum = sblock_to_check->pagev[0]->have_csum;
 857         dev = sblock_to_check->pagev[0]->dev;
 858
 859         /*
 860          * For RAID5/6, race can happen for a different device scrub thread.
 861          * For data corruption, Parity and Data threads will both try
 862          * to recovery the data.
 863          * Race can lead to doubly added csum error, or even unrecoverable
 864          * error.
 865          */
 866         ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
 867         if (ret < 0) {
 868                 spin_lock(&sctx->stat_lock);
 869                 if (ret == -ENOMEM)
 870                         sctx->stat.malloc_errors++;
 871                 sctx->stat.read_errors++;
 872                 sctx->stat.uncorrectable_errors++;
 873                 spin_unlock(&sctx->stat_lock);
 874                 return ret;
 875         }
 876
 877         /*
 878          * read all mirrors one after the other. This includes to
 879          * re-read the extent or metadata block that failed (that was
 880          * the cause that this fixup code is called) another time,
 881          * page by page this time in order to know which pages
 882          * caused I/O errors and which ones are good (for all mirrors).
 883          * It is the goal to handle the situation when more than one
 884          * mirror contains I/O errors, but the errors do not
 885          * overlap, i.e. the data can be repaired by selecting the
 886          * pages from those mirrors without I/O error on the
 887          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 888          * would be that mirror #1 has an I/O error on the first page,
 889          * the second page is good, and mirror #2 has an I/O error on
 890          * the second page, but the first page is good.
 891          * Then the first page of the first mirror can be repaired by
 892          * taking the first page of the second mirror, and the
 893          * second page of the second mirror can be repaired by
 894          * copying the contents of the 2nd page of the 1st mirror.
 895          * One more note: if the pages of one mirror contain I/O
 896          * errors, the checksum cannot be verified. In order to get
 897          * the best data for repairing, the first attempt is to find
 898          * a mirror without I/O errors and with a validated checksum.
 899          * Only if this is not possible, the pages are picked from
 900          * mirrors with I/O errors without considering the checksum.
 901          * If the latter is the case, at the end, the checksum of the
 902          * repaired area is verified in order to correctly maintain
 903          * the statistics.
 904          */
 905
 906         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
 907                                       sizeof(*sblocks_for_recheck), GFP_NOFS);
 908         if (!sblocks_for_recheck) {
 909                 spin_lock(&sctx->stat_lock);
 910                 sctx->stat.malloc_errors++;
 911                 sctx->stat.read_errors++;
 912                 sctx->stat.uncorrectable_errors++;
 913                 spin_unlock(&sctx->stat_lock);
 914                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 915                 goto out;
 916         }
 917
 918         /* setup the context, map the logical blocks and alloc the pages */
 919         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
 920         if (ret) {
 921                 spin_lock(&sctx->stat_lock);
 922                 sctx->stat.read_errors++;
 923                 sctx->stat.uncorrectable_errors++;
 924                 spin_unlock(&sctx->stat_lock);
 925                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 926                 goto out;
 927         }
 928         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 929         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 930
 931         /* build and submit the bios for the failed mirror, check checksums */
 932         scrub_recheck_block(fs_info, sblock_bad, 1);
 933
 934         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 935             sblock_bad->no_io_error_seen) {
 936                 /*
 937                  * the error disappeared after reading page by page, or
 938                  * the area was part of a huge bio and other parts of the
 939                  * bio caused I/O errors, or the block layer merged several
 940                  * read requests into one and the error is caused by a
 941                  * different bio (usually one of the two latter cases is
 942                  * the cause)
 943                  */
 944                 spin_lock(&sctx->stat_lock);
 945                 sctx->stat.unverified_errors++;
 946                 sblock_to_check->data_corrected = 1;
 947                 spin_unlock(&sctx->stat_lock);
 948
 949                 if (sctx->is_dev_replace)
 950                         scrub_write_block_to_dev_replace(sblock_bad);
 951                 goto out;
 952         }
 953
 954         if (!sblock_bad->no_io_error_seen) {
 955                 spin_lock(&sctx->stat_lock);
 956                 sctx->stat.read_errors++;
 957                 spin_unlock(&sctx->stat_lock);
 958                 if (__ratelimit(&_rs))
 959                         scrub_print_warning("i/o error", sblock_to_check);
 960                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 961         } else if (sblock_bad->checksum_error) {
 962                 spin_lock(&sctx->stat_lock);
 963                 sctx->stat.csum_errors++;
 964                 spin_unlock(&sctx->stat_lock);
 965                 if (__ratelimit(&_rs))
 966                         scrub_print_warning("checksum error", sblock_to_check);
 967                 btrfs_dev_stat_inc_and_print(dev,
 968                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
 969         } else if (sblock_bad->header_error) {
 970                 spin_lock(&sctx->stat_lock);
 971                 sctx->stat.verify_errors++;
 972                 spin_unlock(&sctx->stat_lock);
 973                 if (__ratelimit(&_rs))
 974                         scrub_print_warning("checksum/header error",
 975                                             sblock_to_check);
 976                 if (sblock_bad->generation_error)
 977                         btrfs_dev_stat_inc_and_print(dev,
 978                                 BTRFS_DEV_STAT_GENERATION_ERRS);
 979                 else
 980                         btrfs_dev_stat_inc_and_print(dev,
 981                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
 982         }
 983
 984         if (sctx->readonly) {
 985                 ASSERT(!sctx->is_dev_replace);
 986                 goto out;
 987         }
 988
 989         /*
 990          * now build and submit the bios for the other mirrors, check
 991          * checksums.
 992          * First try to pick the mirror which is completely without I/O
 993          * errors and also does not have a checksum error.
 994          * If one is found, and if a checksum is present, the full block
 995          * that is known to contain an error is rewritten. Afterwards
 996          * the block is known to be corrected.
 997          * If a mirror is found which is completely correct, and no
 998          * checksum is present, only those pages are rewritten that had
 999          * an I/O error in the block to be repaired, since it cannot be
1000          * determined, which copy of the other pages is better (and it
1001          * could happen otherwise that a correct page would be
1002          * overwritten by a bad one).
1003          */
1004         for (mirror_index = 0; ;mirror_index++) {
1005                 struct scrub_block *sblock_other;
1006
1007                 if (mirror_index == failed_mirror_index)
1008                         continue;
1009
1010                 /* raid56's mirror can be more than BTRFS_MAX_MIRRORS */
1011                 if (!scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1012                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1013                                 break;
1014                         if (!sblocks_for_recheck[mirror_index].page_count)
1015                                 break;
1016
1017                         sblock_other = sblocks_for_recheck + mirror_index;
1018                 } else {
1019                         struct scrub_recover *r = sblock_bad->pagev[0]->recover;
1020                         int max_allowed = r->bbio->num_stripes -
1021                                                 r->bbio->num_tgtdevs;
1022
1023                         if (mirror_index >= max_allowed)
1024                                 break;
1025                         if (!sblocks_for_recheck[1].page_count)
1026                                 break;
1027
1028                         ASSERT(failed_mirror_index == 0);
1029                         sblock_other = sblocks_for_recheck + 1;
1030                         sblock_other->pagev[0]->mirror_num = 1 + mirror_index;
1031                 }
1032
1033                 /* build and submit the bios, check checksums */
1034                 scrub_recheck_block(fs_info, sblock_other, 0);
1035
1036                 if (!sblock_other->header_error &&
1037                     !sblock_other->checksum_error &&
1038                     sblock_other->no_io_error_seen) {
1039                         if (sctx->is_dev_replace) {
1040                                 scrub_write_block_to_dev_replace(sblock_other);
1041                                 goto corrected_error;
1042                         } else {
1043                                 ret = scrub_repair_block_from_good_copy(
1044                                                 sblock_bad, sblock_other);
1045                                 if (!ret)
1046                                         goto corrected_error;
1047                         }
1048                 }
1049         }
1050
1051         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1052                 goto did_not_correct_error;
1053
1054         /*
1055          * In case of I/O errors in the area that is supposed to be
1056          * repaired, continue by picking good copies of those pages.
1057          * Select the good pages from mirrors to rewrite bad pages from
1058          * the area to fix. Afterwards verify the checksum of the block
1059          * that is supposed to be repaired. This verification step is
1060          * only done for the purpose of statistic counting and for the
1061          * final scrub report, whether errors remain.
1062          * A perfect algorithm could make use of the checksum and try
1063          * all possible combinations of pages from the different mirrors
1064          * until the checksum verification succeeds. For example, when
1065          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1066          * of mirror #2 is readable but the final checksum test fails,
1067          * then the 2nd page of mirror #3 could be tried, whether now
1068          * the final checksum succeeds. But this would be a rare
1069          * exception and is therefore not implemented. At least it is
1070          * avoided that the good copy is overwritten.
1071          * A more useful improvement would be to pick the sectors
1072          * without I/O error based on sector sizes (512 bytes on legacy
1073          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1074          * mirror could be repaired by taking 512 byte of a different
1075          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1076          * area are unreadable.
1077          */
1078         success = 1;
1079         for (page_num = 0; page_num < sblock_bad->page_count;
1080              page_num++) {
1081                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1082                 struct scrub_block *sblock_other = NULL;
1083
1084                 /* skip no-io-error page in scrub */
1085                 if (!page_bad->io_error && !sctx->is_dev_replace)
1086                         continue;
1087
1088                 if (scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1089                         /*
1090                          * In case of dev replace, if raid56 rebuild process
1091                          * didn't work out correct data, then copy the content
1092                          * in sblock_bad to make sure target device is identical
1093                          * to source device, instead of writing garbage data in
1094                          * sblock_for_recheck array to target device.
1095                          */
1096                         sblock_other = NULL;
1097                 } else if (page_bad->io_error) {
1098                         /* try to find no-io-error page in mirrors */
1099                         for (mirror_index = 0;
1100                              mirror_index < BTRFS_MAX_MIRRORS &&
1101                              sblocks_for_recheck[mirror_index].page_count > 0;
1102                              mirror_index++) {
1103                                 if (!sblocks_for_recheck[mirror_index].
1104                                     pagev[page_num]->io_error) {
1105                                         sblock_other = sblocks_for_recheck +
1106                                                        mirror_index;
1107                                         break;
1108                                 }
1109                         }
1110                         if (!sblock_other)
1111                                 success = 0;
1112                 }
1113
1114                 if (sctx->is_dev_replace) {
1115                         /*
1116                          * did not find a mirror to fetch the page
1117                          * from. scrub_write_page_to_dev_replace()
1118                          * handles this case (page->io_error), by
1119                          * filling the block with zeros before
1120                          * submitting the write request
1121                          */
1122                         if (!sblock_other)
1123                                 sblock_other = sblock_bad;
1124
1125                         if (scrub_write_page_to_dev_replace(sblock_other,
1126                                                             page_num) != 0) {
1127                                 btrfs_dev_replace_stats_inc(
1128                                         &fs_info->dev_replace.num_write_errors);
1129                                 success = 0;
1130                         }
1131                 } else if (sblock_other) {
1132                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1133                                                                sblock_other,
1134                                                                page_num, 0);
1135                         if (0 == ret)
1136                                 page_bad->io_error = 0;
1137                         else
1138                                 success = 0;
1139                 }
1140         }
1141
1142         if (success && !sctx->is_dev_replace) {
1143                 if (is_metadata || have_csum) {
1144                         /*
1145                          * need to verify the checksum now that all
1146                          * sectors on disk are repaired (the write
1147                          * request for data to be repaired is on its way).
1148                          * Just be lazy and use scrub_recheck_block()
1149                          * which re-reads the data before the checksum
1150                          * is verified, but most likely the data comes out
1151                          * of the page cache.
1152                          */
1153                         scrub_recheck_block(fs_info, sblock_bad, 1);
1154                         if (!sblock_bad->header_error &&
1155                             !sblock_bad->checksum_error &&
1156                             sblock_bad->no_io_error_seen)
1157                                 goto corrected_error;
1158                         else
1159                                 goto did_not_correct_error;
1160                 } else {
1161 corrected_error:
1162                         spin_lock(&sctx->stat_lock);
1163                         sctx->stat.corrected_errors++;
1164                         sblock_to_check->data_corrected = 1;
1165                         spin_unlock(&sctx->stat_lock);
1166                         btrfs_err_rl_in_rcu(fs_info,
1167                                 "fixed up error at logical %llu on dev %s",
1168                                 logical, rcu_str_deref(dev->name));
1169                 }
1170         } else {
1171 did_not_correct_error:
1172                 spin_lock(&sctx->stat_lock);
1173                 sctx->stat.uncorrectable_errors++;
1174                 spin_unlock(&sctx->stat_lock);
1175                 btrfs_err_rl_in_rcu(fs_info,
1176                         "unable to fixup (regular) error at logical %llu on dev %s",
1177                         logical, rcu_str_deref(dev->name));
1178         }
1179
1180 out:
1181         if (sblocks_for_recheck) {
1182                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1183                      mirror_index++) {
1184                         struct scrub_block *sblock = sblocks_for_recheck +
1185                                                      mirror_index;
1186                         struct scrub_recover *recover;
1187                         int page_index;
1188
1189                         for (page_index = 0; page_index < sblock->page_count;
1190                              page_index++) {
1191                                 sblock->pagev[page_index]->sblock = NULL;
1192                                 recover = sblock->pagev[page_index]->recover;
1193                                 if (recover) {
1194                                         scrub_put_recover(fs_info, recover);
1195                                         sblock->pagev[page_index]->recover =
1196                                                                         NULL;
1197                                 }
1198                                 scrub_page_put(sblock->pagev[page_index]);
1199                         }
1200                 }
1201                 kfree(sblocks_for_recheck);
1202         }
1203
1204         ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
1205         if (ret < 0)
1206                 return ret;
1207         return 0;
1208 }
1209
1210 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1211 {
1212         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1213                 return 2;
1214         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1215                 return 3;
1216         else
1217                 return (int)bbio->num_stripes;
1218 }
1219
1220 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1221                                                  u64 *raid_map,
1222                                                  u64 mapped_length,
1223                                                  int nstripes, int mirror,
1224                                                  int *stripe_index,
1225                                                  u64 *stripe_offset)
1226 {
1227         int i;
1228
1229         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1230                 /* RAID5/6 */
1231                 for (i = 0; i < nstripes; i++) {
1232                         if (raid_map[i] == RAID6_Q_STRIPE ||
1233                             raid_map[i] == RAID5_P_STRIPE)
1234                                 continue;
1235
1236                         if (logical >= raid_map[i] &&
1237                             logical < raid_map[i] + mapped_length)
1238                                 break;
1239                 }
1240
1241                 *stripe_index = i;
1242                 *stripe_offset = logical - raid_map[i];
1243         } else {
1244                 /* The other RAID type */
1245                 *stripe_index = mirror;
1246                 *stripe_offset = 0;
1247         }
1248 }
1249
1250 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1251                                      struct scrub_block *sblocks_for_recheck)
1252 {
1253         struct scrub_ctx *sctx = original_sblock->sctx;
1254         struct btrfs_fs_info *fs_info = sctx->fs_info;
1255         u64 length = original_sblock->page_count * PAGE_SIZE;
1256         u64 logical = original_sblock->pagev[0]->logical;
1257         u64 generation = original_sblock->pagev[0]->generation;
1258         u64 flags = original_sblock->pagev[0]->flags;
1259         u64 have_csum = original_sblock->pagev[0]->have_csum;
1260         struct scrub_recover *recover;
1261         struct btrfs_bio *bbio;
1262         u64 sublen;
1263         u64 mapped_length;
1264         u64 stripe_offset;
1265         int stripe_index;
1266         int page_index = 0;
1267         int mirror_index;
1268         int nmirrors;
1269         int ret;
1270
1271         /*
1272          * note: the two members refs and outstanding_pages
1273          * are not used (and not set) in the blocks that are used for
1274          * the recheck procedure
1275          */
1276
1277         while (length > 0) {
1278                 sublen = min_t(u64, length, PAGE_SIZE);
1279                 mapped_length = sublen;
1280                 bbio = NULL;
1281
1282                 /*
1283                  * with a length of PAGE_SIZE, each returned stripe
1284                  * represents one mirror
1285                  */
1286                 btrfs_bio_counter_inc_blocked(fs_info);
1287                 ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
1288                                 logical, &mapped_length, &bbio);
1289                 if (ret || !bbio || mapped_length < sublen) {
1290                         btrfs_put_bbio(bbio);
1291                         btrfs_bio_counter_dec(fs_info);
1292                         return -EIO;
1293                 }
1294
1295                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1296                 if (!recover) {
1297                         btrfs_put_bbio(bbio);
1298                         btrfs_bio_counter_dec(fs_info);
1299                         return -ENOMEM;
1300                 }
1301
1302                 refcount_set(&recover->refs, 1);
1303                 recover->bbio = bbio;
1304                 recover->map_length = mapped_length;
1305
1306                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1307
1308                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1309
1310                 for (mirror_index = 0; mirror_index < nmirrors;
1311                      mirror_index++) {
1312                         struct scrub_block *sblock;
1313                         struct scrub_page *page;
1314
1315                         sblock = sblocks_for_recheck + mirror_index;
1316                         sblock->sctx = sctx;
1317
1318                         page = kzalloc(sizeof(*page), GFP_NOFS);
1319                         if (!page) {
1320 leave_nomem:
1321                                 spin_lock(&sctx->stat_lock);
1322                                 sctx->stat.malloc_errors++;
1323                                 spin_unlock(&sctx->stat_lock);
1324                                 scrub_put_recover(fs_info, recover);
1325                                 return -ENOMEM;
1326                         }
1327                         scrub_page_get(page);
1328                         sblock->pagev[page_index] = page;
1329                         page->sblock = sblock;
1330                         page->flags = flags;
1331                         page->generation = generation;
1332                         page->logical = logical;
1333                         page->have_csum = have_csum;
1334                         if (have_csum)
1335                                 memcpy(page->csum,
1336                                        original_sblock->pagev[0]->csum,
1337                                        sctx->csum_size);
1338
1339                         scrub_stripe_index_and_offset(logical,
1340                                                       bbio->map_type,
1341                                                       bbio->raid_map,
1342                                                       mapped_length,
1343                                                       bbio->num_stripes -
1344                                                       bbio->num_tgtdevs,
1345                                                       mirror_index,
1346                                                       &stripe_index,
1347                                                       &stripe_offset);
1348                         page->physical = bbio->stripes[stripe_index].physical +
1349                                          stripe_offset;
1350                         page->dev = bbio->stripes[stripe_index].dev;
1351
1352                         BUG_ON(page_index >= original_sblock->page_count);
1353                         page->physical_for_dev_replace =
1354                                 original_sblock->pagev[page_index]->
1355                                 physical_for_dev_replace;
1356                         /* for missing devices, dev->bdev is NULL */
1357                         page->mirror_num = mirror_index + 1;
1358                         sblock->page_count++;
1359                         page->page = alloc_page(GFP_NOFS);
1360                         if (!page->page)
1361                                 goto leave_nomem;
1362
1363                         scrub_get_recover(recover);
1364                         page->recover = recover;
1365                 }
1366                 scrub_put_recover(fs_info, recover);
1367                 length -= sublen;
1368                 logical += sublen;
1369                 page_index++;
1370         }
1371
1372         return 0;
1373 }
1374
1375 static void scrub_bio_wait_endio(struct bio *bio)
1376 {
1377         complete(bio->bi_private);
1378 }
1379
1380 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1381                                         struct bio *bio,
1382                                         struct scrub_page *page)
1383 {
1384         DECLARE_COMPLETION_ONSTACK(done);
1385         int ret;
1386         int mirror_num;
1387
1388         bio->bi_iter.bi_sector = page->logical >> 9;
1389         bio->bi_private = &done;
1390         bio->bi_end_io = scrub_bio_wait_endio;
1391
1392         mirror_num = page->sblock->pagev[0]->mirror_num;
1393         ret = raid56_parity_recover(fs_info, bio, page->recover->bbio,
1394                                     page->recover->map_length,
1395                                     mirror_num, 0);
1396         if (ret)
1397                 return ret;
1398
1399         wait_for_completion_io(&done);
1400         return blk_status_to_errno(bio->bi_status);
1401 }
1402
1403 static void scrub_recheck_block_on_raid56(struct btrfs_fs_info *fs_info,
1404                                           struct scrub_block *sblock)
1405 {
1406         struct scrub_page *first_page = sblock->pagev[0];
1407         struct bio *bio;
1408         int page_num;
1409
1410         /* All pages in sblock belong to the same stripe on the same device. */
1411         ASSERT(first_page->dev);
1412         if (!first_page->dev->bdev)
1413                 goto out;
1414
1415         bio = btrfs_io_bio_alloc(BIO_MAX_PAGES);
1416         bio_set_dev(bio, first_page->dev->bdev);
1417
1418         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1419                 struct scrub_page *page = sblock->pagev[page_num];
1420
1421                 WARN_ON(!page->page);
1422                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1423         }
1424
1425         if (scrub_submit_raid56_bio_wait(fs_info, bio, first_page)) {
1426                 bio_put(bio);
1427                 goto out;
1428         }
1429
1430         bio_put(bio);
1431
1432         scrub_recheck_block_checksum(sblock);
1433
1434         return;
1435 out:
1436         for (page_num = 0; page_num < sblock->page_count; page_num++)
1437                 sblock->pagev[page_num]->io_error = 1;
1438
1439         sblock->no_io_error_seen = 0;
1440 }
1441
1442 /*
1443  * this function will check the on disk data for checksum errors, header
1444  * errors and read I/O errors. If any I/O errors happen, the exact pages
1445  * which are errored are marked as being bad. The goal is to enable scrub
1446  * to take those pages that are not errored from all the mirrors so that
1447  * the pages that are errored in the just handled mirror can be repaired.
1448  */
1449 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1450                                 struct scrub_block *sblock,
1451                                 int retry_failed_mirror)
1452 {
1453         int page_num;
1454
1455         sblock->no_io_error_seen = 1;
1456
1457         /* short cut for raid56 */
1458         if (!retry_failed_mirror && scrub_is_page_on_raid56(sblock->pagev[0]))
1459                 return scrub_recheck_block_on_raid56(fs_info, sblock);
1460
1461         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1462                 struct bio *bio;
1463                 struct scrub_page *page = sblock->pagev[page_num];
1464
1465                 if (page->dev->bdev == NULL) {
1466                         page->io_error = 1;
1467                         sblock->no_io_error_seen = 0;
1468                         continue;
1469                 }
1470
1471                 WARN_ON(!page->page);
1472                 bio = btrfs_io_bio_alloc(1);
1473                 bio_set_dev(bio, page->dev->bdev);
1474
1475                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1476                 bio->bi_iter.bi_sector = page->physical >> 9;
1477                 bio->bi_opf = REQ_OP_READ;
1478
1479                 if (btrfsic_submit_bio_wait(bio)) {
1480                         page->io_error = 1;
1481                         sblock->no_io_error_seen = 0;
1482                 }
1483
1484                 bio_put(bio);
1485         }
1486
1487         if (sblock->no_io_error_seen)
1488                 scrub_recheck_block_checksum(sblock);
1489 }
1490
1491 static inline int scrub_check_fsid(u8 fsid[],
1492                                    struct scrub_page *spage)
1493 {
1494         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1495         int ret;
1496
1497         ret = memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1498         return !ret;
1499 }
1500
1501 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1502 {
1503         sblock->header_error = 0;
1504         sblock->checksum_error = 0;
1505         sblock->generation_error = 0;
1506
1507         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1508                 scrub_checksum_data(sblock);
1509         else
1510                 scrub_checksum_tree_block(sblock);
1511 }
1512
1513 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1514                                              struct scrub_block *sblock_good)
1515 {
1516         int page_num;
1517         int ret = 0;
1518
1519         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1520                 int ret_sub;
1521
1522                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1523                                                            sblock_good,
1524                                                            page_num, 1);
1525                 if (ret_sub)
1526                         ret = ret_sub;
1527         }
1528
1529         return ret;
1530 }
1531
1532 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1533                                             struct scrub_block *sblock_good,
1534                                             int page_num, int force_write)
1535 {
1536         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1537         struct scrub_page *page_good = sblock_good->pagev[page_num];
1538         struct btrfs_fs_info *fs_info = sblock_bad->sctx->fs_info;
1539
1540         BUG_ON(page_bad->page == NULL);
1541         BUG_ON(page_good->page == NULL);
1542         if (force_write || sblock_bad->header_error ||
1543             sblock_bad->checksum_error || page_bad->io_error) {
1544                 struct bio *bio;
1545                 int ret;
1546
1547                 if (!page_bad->dev->bdev) {
1548                         btrfs_warn_rl(fs_info,
1549                                 "scrub_repair_page_from_good_copy(bdev == NULL) is unexpected");
1550                         return -EIO;
1551                 }
1552
1553                 bio = btrfs_io_bio_alloc(1);
1554                 bio_set_dev(bio, page_bad->dev->bdev);
1555                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1556                 bio->bi_opf = REQ_OP_WRITE;
1557
1558                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1559                 if (PAGE_SIZE != ret) {
1560                         bio_put(bio);
1561                         return -EIO;
1562                 }
1563
1564                 if (btrfsic_submit_bio_wait(bio)) {
1565                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1566                                 BTRFS_DEV_STAT_WRITE_ERRS);
1567                         btrfs_dev_replace_stats_inc(
1568                                 &fs_info->dev_replace.num_write_errors);
1569                         bio_put(bio);
1570                         return -EIO;
1571                 }
1572                 bio_put(bio);
1573         }
1574
1575         return 0;
1576 }
1577
1578 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1579 {
1580         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
1581         int page_num;
1582
1583         /*
1584          * This block is used for the check of the parity on the source device,
1585          * so the data needn't be written into the destination device.
1586          */
1587         if (sblock->sparity)
1588                 return;
1589
1590         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1591                 int ret;
1592
1593                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1594                 if (ret)
1595                         btrfs_dev_replace_stats_inc(
1596                                 &fs_info->dev_replace.num_write_errors);
1597         }
1598 }
1599
1600 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1601                                            int page_num)
1602 {
1603         struct scrub_page *spage = sblock->pagev[page_num];
1604
1605         BUG_ON(spage->page == NULL);
1606         if (spage->io_error) {
1607                 void *mapped_buffer = kmap_atomic(spage->page);
1608
1609                 clear_page(mapped_buffer);
1610                 flush_dcache_page(spage->page);
1611                 kunmap_atomic(mapped_buffer);
1612         }
1613         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1614 }
1615
1616 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1617                                     struct scrub_page *spage)
1618 {
1619         struct scrub_bio *sbio;
1620         int ret;
1621
1622         mutex_lock(&sctx->wr_lock);
1623 again:
1624         if (!sctx->wr_curr_bio) {
1625                 sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
1626                                               GFP_KERNEL);
1627                 if (!sctx->wr_curr_bio) {
1628                         mutex_unlock(&sctx->wr_lock);
1629                         return -ENOMEM;
1630                 }
1631                 sctx->wr_curr_bio->sctx = sctx;
1632                 sctx->wr_curr_bio->page_count = 0;
1633         }
1634         sbio = sctx->wr_curr_bio;
1635         if (sbio->page_count == 0) {
1636                 struct bio *bio;
1637
1638                 sbio->physical = spage->physical_for_dev_replace;
1639                 sbio->logical = spage->logical;
1640                 sbio->dev = sctx->wr_tgtdev;
1641                 bio = sbio->bio;
1642                 if (!bio) {
1643                         bio = btrfs_io_bio_alloc(sctx->pages_per_wr_bio);
1644                         sbio->bio = bio;
1645                 }
1646
1647                 bio->bi_private = sbio;
1648                 bio->bi_end_io = scrub_wr_bio_end_io;
1649                 bio_set_dev(bio, sbio->dev->bdev);
1650                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1651                 bio->bi_opf = REQ_OP_WRITE;
1652                 sbio->status = 0;
1653         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1654                    spage->physical_for_dev_replace ||
1655                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1656                    spage->logical) {
1657                 scrub_wr_submit(sctx);
1658                 goto again;
1659         }
1660
1661         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1662         if (ret != PAGE_SIZE) {
1663                 if (sbio->page_count < 1) {
1664                         bio_put(sbio->bio);
1665                         sbio->bio = NULL;
1666                         mutex_unlock(&sctx->wr_lock);
1667                         return -EIO;
1668                 }
1669                 scrub_wr_submit(sctx);
1670                 goto again;
1671         }
1672
1673         sbio->pagev[sbio->page_count] = spage;
1674         scrub_page_get(spage);
1675         sbio->page_count++;
1676         if (sbio->page_count == sctx->pages_per_wr_bio)
1677                 scrub_wr_submit(sctx);
1678         mutex_unlock(&sctx->wr_lock);
1679
1680         return 0;
1681 }
1682
1683 static void scrub_wr_submit(struct scrub_ctx *sctx)
1684 {
1685         struct scrub_bio *sbio;
1686
1687         if (!sctx->wr_curr_bio)
1688                 return;
1689
1690         sbio = sctx->wr_curr_bio;
1691         sctx->wr_curr_bio = NULL;
1692         WARN_ON(!sbio->bio->bi_disk);
1693         scrub_pending_bio_inc(sctx);
1694         /* process all writes in a single worker thread. Then the block layer
1695          * orders the requests before sending them to the driver which
1696          * doubled the write performance on spinning disks when measured
1697          * with Linux 3.5 */
1698         btrfsic_submit_bio(sbio->bio);
1699 }
1700
1701 static void scrub_wr_bio_end_io(struct bio *bio)
1702 {
1703         struct scrub_bio *sbio = bio->bi_private;
1704         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
1705
1706         sbio->status = bio->bi_status;
1707         sbio->bio = bio;
1708
1709         btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
1710                          scrub_wr_bio_end_io_worker, NULL, NULL);
1711         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1712 }
1713
1714 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1715 {
1716         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1717         struct scrub_ctx *sctx = sbio->sctx;
1718         int i;
1719
1720         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1721         if (sbio->status) {
1722                 struct btrfs_dev_replace *dev_replace =
1723                         &sbio->sctx->fs_info->dev_replace;
1724
1725                 for (i = 0; i < sbio->page_count; i++) {
1726                         struct scrub_page *spage = sbio->pagev[i];
1727
1728                         spage->io_error = 1;
1729                         btrfs_dev_replace_stats_inc(&dev_replace->
1730                                                     num_write_errors);
1731                 }
1732         }
1733
1734         for (i = 0; i < sbio->page_count; i++)
1735                 scrub_page_put(sbio->pagev[i]);
1736
1737         bio_put(sbio->bio);
1738         kfree(sbio);
1739         scrub_pending_bio_dec(sctx);
1740 }
1741
1742 static int scrub_checksum(struct scrub_block *sblock)
1743 {
1744         u64 flags;
1745         int ret;
1746
1747         /*
1748          * No need to initialize these stats currently,
1749          * because this function only use return value
1750          * instead of these stats value.
1751          *
1752          * Todo:
1753          * always use stats
1754          */
1755         sblock->header_error = 0;
1756         sblock->generation_error = 0;
1757         sblock->checksum_error = 0;
1758
1759         WARN_ON(sblock->page_count < 1);
1760         flags = sblock->pagev[0]->flags;
1761         ret = 0;
1762         if (flags & BTRFS_EXTENT_FLAG_DATA)
1763                 ret = scrub_checksum_data(sblock);
1764         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1765                 ret = scrub_checksum_tree_block(sblock);
1766         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1767                 (void)scrub_checksum_super(sblock);
1768         else
1769                 WARN_ON(1);
1770         if (ret)
1771                 scrub_handle_errored_block(sblock);
1772
1773         return ret;
1774 }
1775
1776 static int scrub_checksum_data(struct scrub_block *sblock)
1777 {
1778         struct scrub_ctx *sctx = sblock->sctx;
1779         u8 csum[BTRFS_CSUM_SIZE];
1780         u8 *on_disk_csum;
1781         struct page *page;
1782         void *buffer;
1783         u32 crc = ~(u32)0;
1784         u64 len;
1785         int index;
1786
1787         BUG_ON(sblock->page_count < 1);
1788         if (!sblock->pagev[0]->have_csum)
1789                 return 0;
1790
1791         on_disk_csum = sblock->pagev[0]->csum;
1792         page = sblock->pagev[0]->page;
1793         buffer = kmap_atomic(page);
1794
1795         len = sctx->fs_info->sectorsize;
1796         index = 0;
1797         for (;;) {
1798                 u64 l = min_t(u64, len, PAGE_SIZE);
1799
1800                 crc = btrfs_csum_data(buffer, crc, l);
1801                 kunmap_atomic(buffer);
1802                 len -= l;
1803                 if (len == 0)
1804                         break;
1805                 index++;
1806                 BUG_ON(index >= sblock->page_count);
1807                 BUG_ON(!sblock->pagev[index]->page);
1808                 page = sblock->pagev[index]->page;
1809                 buffer = kmap_atomic(page);
1810         }
1811
1812         btrfs_csum_final(crc, csum);
1813         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1814                 sblock->checksum_error = 1;
1815
1816         return sblock->checksum_error;
1817 }
1818
1819 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1820 {
1821         struct scrub_ctx *sctx = sblock->sctx;
1822         struct btrfs_header *h;
1823         struct btrfs_fs_info *fs_info = sctx->fs_info;
1824         u8 calculated_csum[BTRFS_CSUM_SIZE];
1825         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1826         struct page *page;
1827         void *mapped_buffer;
1828         u64 mapped_size;
1829         void *p;
1830         u32 crc = ~(u32)0;
1831         u64 len;
1832         int index;
1833
1834         BUG_ON(sblock->page_count < 1);
1835         page = sblock->pagev[0]->page;
1836         mapped_buffer = kmap_atomic(page);
1837         h = (struct btrfs_header *)mapped_buffer;
1838         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1839
1840         /*
1841          * we don't use the getter functions here, as we
1842          * a) don't have an extent buffer and
1843          * b) the page is already kmapped
1844          */
1845         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1846                 sblock->header_error = 1;
1847
1848         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
1849                 sblock->header_error = 1;
1850                 sblock->generation_error = 1;
1851         }
1852
1853         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
1854                 sblock->header_error = 1;
1855
1856         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1857                    BTRFS_UUID_SIZE))
1858                 sblock->header_error = 1;
1859
1860         len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
1861         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1862         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1863         index = 0;
1864         for (;;) {
1865                 u64 l = min_t(u64, len, mapped_size);
1866
1867                 crc = btrfs_csum_data(p, crc, l);
1868                 kunmap_atomic(mapped_buffer);
1869                 len -= l;
1870                 if (len == 0)
1871                         break;
1872                 index++;
1873                 BUG_ON(index >= sblock->page_count);
1874                 BUG_ON(!sblock->pagev[index]->page);
1875                 page = sblock->pagev[index]->page;
1876                 mapped_buffer = kmap_atomic(page);
1877                 mapped_size = PAGE_SIZE;
1878                 p = mapped_buffer;
1879         }
1880
1881         btrfs_csum_final(crc, calculated_csum);
1882         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1883                 sblock->checksum_error = 1;
1884
1885         return sblock->header_error || sblock->checksum_error;
1886 }
1887
1888 static int scrub_checksum_super(struct scrub_block *sblock)
1889 {
1890         struct btrfs_super_block *s;
1891         struct scrub_ctx *sctx = sblock->sctx;
1892         u8 calculated_csum[BTRFS_CSUM_SIZE];
1893         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1894         struct page *page;
1895         void *mapped_buffer;
1896         u64 mapped_size;
1897         void *p;
1898         u32 crc = ~(u32)0;
1899         int fail_gen = 0;
1900         int fail_cor = 0;
1901         u64 len;
1902         int index;
1903
1904         BUG_ON(sblock->page_count < 1);
1905         page = sblock->pagev[0]->page;
1906         mapped_buffer = kmap_atomic(page);
1907         s = (struct btrfs_super_block *)mapped_buffer;
1908         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1909
1910         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1911                 ++fail_cor;
1912
1913         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1914                 ++fail_gen;
1915
1916         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1917                 ++fail_cor;
1918
1919         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1920         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1921         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1922         index = 0;
1923         for (;;) {
1924                 u64 l = min_t(u64, len, mapped_size);
1925
1926                 crc = btrfs_csum_data(p, crc, l);
1927                 kunmap_atomic(mapped_buffer);
1928                 len -= l;
1929                 if (len == 0)
1930                         break;
1931                 index++;
1932                 BUG_ON(index >= sblock->page_count);
1933                 BUG_ON(!sblock->pagev[index]->page);
1934                 page = sblock->pagev[index]->page;
1935                 mapped_buffer = kmap_atomic(page);
1936                 mapped_size = PAGE_SIZE;
1937                 p = mapped_buffer;
1938         }
1939
1940         btrfs_csum_final(crc, calculated_csum);
1941         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1942                 ++fail_cor;
1943
1944         if (fail_cor + fail_gen) {
1945                 /*
1946                  * if we find an error in a super block, we just report it.
1947                  * They will get written with the next transaction commit
1948                  * anyway
1949                  */
1950                 spin_lock(&sctx->stat_lock);
1951                 ++sctx->stat.super_errors;
1952                 spin_unlock(&sctx->stat_lock);
1953                 if (fail_cor)
1954                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1955                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1956                 else
1957                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1958                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1959         }
1960
1961         return fail_cor + fail_gen;
1962 }
1963
1964 static void scrub_block_get(struct scrub_block *sblock)
1965 {
1966         refcount_inc(&sblock->refs);
1967 }
1968
1969 static void scrub_block_put(struct scrub_block *sblock)
1970 {
1971         if (refcount_dec_and_test(&sblock->refs)) {
1972                 int i;
1973
1974                 if (sblock->sparity)
1975                         scrub_parity_put(sblock->sparity);
1976
1977                 for (i = 0; i < sblock->page_count; i++)
1978                         scrub_page_put(sblock->pagev[i]);
1979                 kfree(sblock);
1980         }
1981 }
1982
1983 static void scrub_page_get(struct scrub_page *spage)
1984 {
1985         atomic_inc(&spage->refs);
1986 }
1987
1988 static void scrub_page_put(struct scrub_page *spage)
1989 {
1990         if (atomic_dec_and_test(&spage->refs)) {
1991                 if (spage->page)
1992                         __free_page(spage->page);
1993                 kfree(spage);
1994         }
1995 }
1996
1997 static void scrub_submit(struct scrub_ctx *sctx)
1998 {
1999         struct scrub_bio *sbio;
2000
2001         if (sctx->curr == -1)
2002                 return;
2003
2004         sbio = sctx->bios[sctx->curr];
2005         sctx->curr = -1;
2006         scrub_pending_bio_inc(sctx);
2007         btrfsic_submit_bio(sbio->bio);
2008 }
2009
2010 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2011                                     struct scrub_page *spage)
2012 {
2013         struct scrub_block *sblock = spage->sblock;
2014         struct scrub_bio *sbio;
2015         int ret;
2016
2017 again:
2018         /*
2019          * grab a fresh bio or wait for one to become available
2020          */
2021         while (sctx->curr == -1) {
2022                 spin_lock(&sctx->list_lock);
2023                 sctx->curr = sctx->first_free;
2024                 if (sctx->curr != -1) {
2025                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2026                         sctx->bios[sctx->curr]->next_free = -1;
2027                         sctx->bios[sctx->curr]->page_count = 0;
2028                         spin_unlock(&sctx->list_lock);
2029                 } else {
2030                         spin_unlock(&sctx->list_lock);
2031                         wait_event(sctx->list_wait, sctx->first_free != -1);
2032                 }
2033         }
2034         sbio = sctx->bios[sctx->curr];
2035         if (sbio->page_count == 0) {
2036                 struct bio *bio;
2037
2038                 sbio->physical = spage->physical;
2039                 sbio->logical = spage->logical;
2040                 sbio->dev = spage->dev;
2041                 bio = sbio->bio;
2042                 if (!bio) {
2043                         bio = btrfs_io_bio_alloc(sctx->pages_per_rd_bio);
2044                         sbio->bio = bio;
2045                 }
2046
2047                 bio->bi_private = sbio;
2048                 bio->bi_end_io = scrub_bio_end_io;
2049                 bio_set_dev(bio, sbio->dev->bdev);
2050                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2051                 bio->bi_opf = REQ_OP_READ;
2052                 sbio->status = 0;
2053         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2054                    spage->physical ||
2055                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2056                    spage->logical ||
2057                    sbio->dev != spage->dev) {
2058                 scrub_submit(sctx);
2059                 goto again;
2060         }
2061
2062         sbio->pagev[sbio->page_count] = spage;
2063         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2064         if (ret != PAGE_SIZE) {
2065                 if (sbio->page_count < 1) {
2066                         bio_put(sbio->bio);
2067                         sbio->bio = NULL;
2068                         return -EIO;
2069                 }
2070                 scrub_submit(sctx);
2071                 goto again;
2072         }
2073
2074         scrub_block_get(sblock); /* one for the page added to the bio */
2075         atomic_inc(&sblock->outstanding_pages);
2076         sbio->page_count++;
2077         if (sbio->page_count == sctx->pages_per_rd_bio)
2078                 scrub_submit(sctx);
2079
2080         return 0;
2081 }
2082
2083 static void scrub_missing_raid56_end_io(struct bio *bio)
2084 {
2085         struct scrub_block *sblock = bio->bi_private;
2086         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
2087
2088         if (bio->bi_status)
2089                 sblock->no_io_error_seen = 0;
2090
2091         bio_put(bio);
2092
2093         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2094 }
2095
2096 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2097 {
2098         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2099         struct scrub_ctx *sctx = sblock->sctx;
2100         struct btrfs_fs_info *fs_info = sctx->fs_info;
2101         u64 logical;
2102         struct btrfs_device *dev;
2103
2104         logical = sblock->pagev[0]->logical;
2105         dev = sblock->pagev[0]->dev;
2106
2107         if (sblock->no_io_error_seen)
2108                 scrub_recheck_block_checksum(sblock);
2109
2110         if (!sblock->no_io_error_seen) {
2111                 spin_lock(&sctx->stat_lock);
2112                 sctx->stat.read_errors++;
2113                 spin_unlock(&sctx->stat_lock);
2114                 btrfs_err_rl_in_rcu(fs_info,
2115                         "IO error rebuilding logical %llu for dev %s",
2116                         logical, rcu_str_deref(dev->name));
2117         } else if (sblock->header_error || sblock->checksum_error) {
2118                 spin_lock(&sctx->stat_lock);
2119                 sctx->stat.uncorrectable_errors++;
2120                 spin_unlock(&sctx->stat_lock);
2121                 btrfs_err_rl_in_rcu(fs_info,
2122                         "failed to rebuild valid logical %llu for dev %s",
2123                         logical, rcu_str_deref(dev->name));
2124         } else {
2125                 scrub_write_block_to_dev_replace(sblock);
2126         }
2127
2128         scrub_block_put(sblock);
2129
2130         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2131                 mutex_lock(&sctx->wr_lock);
2132                 scrub_wr_submit(sctx);
2133                 mutex_unlock(&sctx->wr_lock);
2134         }
2135
2136         scrub_pending_bio_dec(sctx);
2137 }
2138
2139 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2140 {
2141         struct scrub_ctx *sctx = sblock->sctx;
2142         struct btrfs_fs_info *fs_info = sctx->fs_info;
2143         u64 length = sblock->page_count * PAGE_SIZE;
2144         u64 logical = sblock->pagev[0]->logical;
2145         struct btrfs_bio *bbio = NULL;
2146         struct bio *bio;
2147         struct btrfs_raid_bio *rbio;
2148         int ret;
2149         int i;
2150
2151         btrfs_bio_counter_inc_blocked(fs_info);
2152         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
2153                         &length, &bbio);
2154         if (ret || !bbio || !bbio->raid_map)
2155                 goto bbio_out;
2156
2157         if (WARN_ON(!sctx->is_dev_replace ||
2158                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2159                 /*
2160                  * We shouldn't be scrubbing a missing device. Even for dev
2161                  * replace, we should only get here for RAID 5/6. We either
2162                  * managed to mount something with no mirrors remaining or
2163                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2164                  */
2165                 goto bbio_out;
2166         }
2167
2168         bio = btrfs_io_bio_alloc(0);
2169         bio->bi_iter.bi_sector = logical >> 9;
2170         bio->bi_private = sblock;
2171         bio->bi_end_io = scrub_missing_raid56_end_io;
2172
2173         rbio = raid56_alloc_missing_rbio(fs_info, bio, bbio, length);
2174         if (!rbio)
2175                 goto rbio_out;
2176
2177         for (i = 0; i < sblock->page_count; i++) {
2178                 struct scrub_page *spage = sblock->pagev[i];
2179
2180                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2181         }
2182
2183         btrfs_init_work(&sblock->work, btrfs_scrub_helper,
2184                         scrub_missing_raid56_worker, NULL, NULL);
2185         scrub_block_get(sblock);
2186         scrub_pending_bio_inc(sctx);
2187         raid56_submit_missing_rbio(rbio);
2188         return;
2189
2190 rbio_out:
2191         bio_put(bio);
2192 bbio_out:
2193         btrfs_bio_counter_dec(fs_info);
2194         btrfs_put_bbio(bbio);
2195         spin_lock(&sctx->stat_lock);
2196         sctx->stat.malloc_errors++;
2197         spin_unlock(&sctx->stat_lock);
2198 }
2199
2200 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2201                        u64 physical, struct btrfs_device *dev, u64 flags,
2202                        u64 gen, int mirror_num, u8 *csum, int force,
2203                        u64 physical_for_dev_replace)
2204 {
2205         struct scrub_block *sblock;
2206         int index;
2207
2208         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2209         if (!sblock) {
2210                 spin_lock(&sctx->stat_lock);
2211                 sctx->stat.malloc_errors++;
2212                 spin_unlock(&sctx->stat_lock);
2213                 return -ENOMEM;
2214         }
2215
2216         /* one ref inside this function, plus one for each page added to
2217          * a bio later on */
2218         refcount_set(&sblock->refs, 1);
2219         sblock->sctx = sctx;
2220         sblock->no_io_error_seen = 1;
2221
2222         for (index = 0; len > 0; index++) {
2223                 struct scrub_page *spage;
2224                 u64 l = min_t(u64, len, PAGE_SIZE);
2225
2226                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2227                 if (!spage) {
2228 leave_nomem:
2229                         spin_lock(&sctx->stat_lock);
2230                         sctx->stat.malloc_errors++;
2231                         spin_unlock(&sctx->stat_lock);
2232                         scrub_block_put(sblock);
2233                         return -ENOMEM;
2234                 }
2235                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2236                 scrub_page_get(spage);
2237                 sblock->pagev[index] = spage;
2238                 spage->sblock = sblock;
2239                 spage->dev = dev;
2240                 spage->flags = flags;
2241                 spage->generation = gen;
2242                 spage->logical = logical;
2243                 spage->physical = physical;
2244                 spage->physical_for_dev_replace = physical_for_dev_replace;
2245                 spage->mirror_num = mirror_num;
2246                 if (csum) {
2247                         spage->have_csum = 1;
2248                         memcpy(spage->csum, csum, sctx->csum_size);
2249                 } else {
2250                         spage->have_csum = 0;
2251                 }
2252                 sblock->page_count++;
2253                 spage->page = alloc_page(GFP_KERNEL);
2254                 if (!spage->page)
2255                         goto leave_nomem;
2256                 len -= l;
2257                 logical += l;
2258                 physical += l;
2259                 physical_for_dev_replace += l;
2260         }
2261
2262         WARN_ON(sblock->page_count == 0);
2263         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2264                 /*
2265                  * This case should only be hit for RAID 5/6 device replace. See
2266                  * the comment in scrub_missing_raid56_pages() for details.
2267                  */
2268                 scrub_missing_raid56_pages(sblock);
2269         } else {
2270                 for (index = 0; index < sblock->page_count; index++) {
2271                         struct scrub_page *spage = sblock->pagev[index];
2272                         int ret;
2273
2274                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2275                         if (ret) {
2276                                 scrub_block_put(sblock);
2277                                 return ret;
2278                         }
2279                 }
2280
2281                 if (force)
2282                         scrub_submit(sctx);
2283         }
2284
2285         /* last one frees, either here or in bio completion for last page */
2286         scrub_block_put(sblock);
2287         return 0;
2288 }
2289
2290 static void scrub_bio_end_io(struct bio *bio)
2291 {
2292         struct scrub_bio *sbio = bio->bi_private;
2293         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
2294
2295         sbio->status = bio->bi_status;
2296         sbio->bio = bio;
2297
2298         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2299 }
2300
2301 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2302 {
2303         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2304         struct scrub_ctx *sctx = sbio->sctx;
2305         int i;
2306
2307         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2308         if (sbio->status) {
2309                 for (i = 0; i < sbio->page_count; i++) {
2310                         struct scrub_page *spage = sbio->pagev[i];
2311
2312                         spage->io_error = 1;
2313                         spage->sblock->no_io_error_seen = 0;
2314                 }
2315         }
2316
2317         /* now complete the scrub_block items that have all pages completed */
2318         for (i = 0; i < sbio->page_count; i++) {
2319                 struct scrub_page *spage = sbio->pagev[i];
2320                 struct scrub_block *sblock = spage->sblock;
2321
2322                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2323                         scrub_block_complete(sblock);
2324                 scrub_block_put(sblock);
2325         }
2326
2327         bio_put(sbio->bio);
2328         sbio->bio = NULL;
2329         spin_lock(&sctx->list_lock);
2330         sbio->next_free = sctx->first_free;
2331         sctx->first_free = sbio->index;
2332         spin_unlock(&sctx->list_lock);
2333
2334         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2335                 mutex_lock(&sctx->wr_lock);
2336                 scrub_wr_submit(sctx);
2337                 mutex_unlock(&sctx->wr_lock);
2338         }
2339
2340         scrub_pending_bio_dec(sctx);
2341 }
2342
2343 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2344                                        unsigned long *bitmap,
2345                                        u64 start, u64 len)
2346 {
2347         u64 offset;
2348         u64 nsectors64;
2349         u32 nsectors;
2350         int sectorsize = sparity->sctx->fs_info->sectorsize;
2351
2352         if (len >= sparity->stripe_len) {
2353                 bitmap_set(bitmap, 0, sparity->nsectors);
2354                 return;
2355         }
2356
2357         start -= sparity->logic_start;
2358         start = div64_u64_rem(start, sparity->stripe_len, &offset);
2359         offset = div_u64(offset, sectorsize);
2360         nsectors64 = div_u64(len, sectorsize);
2361
2362         ASSERT(nsectors64 < UINT_MAX);
2363         nsectors = (u32)nsectors64;
2364
2365         if (offset + nsectors <= sparity->nsectors) {
2366                 bitmap_set(bitmap, offset, nsectors);
2367                 return;
2368         }
2369
2370         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2371         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2372 }
2373
2374 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2375                                                    u64 start, u64 len)
2376 {
2377         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2378 }
2379
2380 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2381                                                   u64 start, u64 len)
2382 {
2383         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2384 }
2385
2386 static void scrub_block_complete(struct scrub_block *sblock)
2387 {
2388         int corrupted = 0;
2389
2390         if (!sblock->no_io_error_seen) {
2391                 corrupted = 1;
2392                 scrub_handle_errored_block(sblock);
2393         } else {
2394                 /*
2395                  * if has checksum error, write via repair mechanism in
2396                  * dev replace case, otherwise write here in dev replace
2397                  * case.
2398                  */
2399                 corrupted = scrub_checksum(sblock);
2400                 if (!corrupted && sblock->sctx->is_dev_replace)
2401                         scrub_write_block_to_dev_replace(sblock);
2402         }
2403
2404         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2405                 u64 start = sblock->pagev[0]->logical;
2406                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2407                           PAGE_SIZE;
2408
2409                 scrub_parity_mark_sectors_error(sblock->sparity,
2410                                                 start, end - start);
2411         }
2412 }
2413
2414 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2415 {
2416         struct btrfs_ordered_sum *sum = NULL;
2417         unsigned long index;
2418         unsigned long num_sectors;
2419
2420         while (!list_empty(&sctx->csum_list)) {
2421                 sum = list_first_entry(&sctx->csum_list,
2422                                        struct btrfs_ordered_sum, list);
2423                 if (sum->bytenr > logical)
2424                         return 0;
2425                 if (sum->bytenr + sum->len > logical)
2426                         break;
2427
2428                 ++sctx->stat.csum_discards;
2429                 list_del(&sum->list);
2430                 kfree(sum);
2431                 sum = NULL;
2432         }
2433         if (!sum)
2434                 return 0;
2435
2436         index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize);
2437         ASSERT(index < UINT_MAX);
2438
2439         num_sectors = sum->len / sctx->fs_info->sectorsize;
2440         memcpy(csum, sum->sums + index, sctx->csum_size);
2441         if (index == num_sectors - 1) {
2442                 list_del(&sum->list);
2443                 kfree(sum);
2444         }
2445         return 1;
2446 }
2447
2448 /* scrub extent tries to collect up to 64 kB for each bio */
2449 static int scrub_extent(struct scrub_ctx *sctx, struct map_lookup *map,
2450                         u64 logical, u64 len,
2451                         u64 physical, struct btrfs_device *dev, u64 flags,
2452                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2453 {
2454         int ret;
2455         u8 csum[BTRFS_CSUM_SIZE];
2456         u32 blocksize;
2457
2458         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2459                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2460                         blocksize = map->stripe_len;
2461                 else
2462                         blocksize = sctx->fs_info->sectorsize;
2463                 spin_lock(&sctx->stat_lock);
2464                 sctx->stat.data_extents_scrubbed++;
2465                 sctx->stat.data_bytes_scrubbed += len;
2466                 spin_unlock(&sctx->stat_lock);
2467         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2468                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2469                         blocksize = map->stripe_len;
2470                 else
2471                         blocksize = sctx->fs_info->nodesize;
2472                 spin_lock(&sctx->stat_lock);
2473                 sctx->stat.tree_extents_scrubbed++;
2474                 sctx->stat.tree_bytes_scrubbed += len;
2475                 spin_unlock(&sctx->stat_lock);
2476         } else {
2477                 blocksize = sctx->fs_info->sectorsize;
2478                 WARN_ON(1);
2479         }
2480
2481         while (len) {
2482                 u64 l = min_t(u64, len, blocksize);
2483                 int have_csum = 0;
2484
2485                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2486                         /* push csums to sbio */
2487                         have_csum = scrub_find_csum(sctx, logical, csum);
2488                         if (have_csum == 0)
2489                                 ++sctx->stat.no_csum;
2490                 }
2491                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2492                                   mirror_num, have_csum ? csum : NULL, 0,
2493                                   physical_for_dev_replace);
2494                 if (ret)
2495                         return ret;
2496                 len -= l;
2497                 logical += l;
2498                 physical += l;
2499                 physical_for_dev_replace += l;
2500         }
2501         return 0;
2502 }
2503
2504 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2505                                   u64 logical, u64 len,
2506                                   u64 physical, struct btrfs_device *dev,
2507                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2508 {
2509         struct scrub_ctx *sctx = sparity->sctx;
2510         struct scrub_block *sblock;
2511         int index;
2512
2513         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2514         if (!sblock) {
2515                 spin_lock(&sctx->stat_lock);
2516                 sctx->stat.malloc_errors++;
2517                 spin_unlock(&sctx->stat_lock);
2518                 return -ENOMEM;
2519         }
2520
2521         /* one ref inside this function, plus one for each page added to
2522          * a bio later on */
2523         refcount_set(&sblock->refs, 1);
2524         sblock->sctx = sctx;
2525         sblock->no_io_error_seen = 1;
2526         sblock->sparity = sparity;
2527         scrub_parity_get(sparity);
2528
2529         for (index = 0; len > 0; index++) {
2530                 struct scrub_page *spage;
2531                 u64 l = min_t(u64, len, PAGE_SIZE);
2532
2533                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2534                 if (!spage) {
2535 leave_nomem:
2536                         spin_lock(&sctx->stat_lock);
2537                         sctx->stat.malloc_errors++;
2538                         spin_unlock(&sctx->stat_lock);
2539                         scrub_block_put(sblock);
2540                         return -ENOMEM;
2541                 }
2542                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2543                 /* For scrub block */
2544                 scrub_page_get(spage);
2545                 sblock->pagev[index] = spage;
2546                 /* For scrub parity */
2547                 scrub_page_get(spage);
2548                 list_add_tail(&spage->list, &sparity->spages);
2549                 spage->sblock = sblock;
2550                 spage->dev = dev;
2551                 spage->flags = flags;
2552                 spage->generation = gen;
2553                 spage->logical = logical;
2554                 spage->physical = physical;
2555                 spage->mirror_num = mirror_num;
2556                 if (csum) {
2557                         spage->have_csum = 1;
2558                         memcpy(spage->csum, csum, sctx->csum_size);
2559                 } else {
2560                         spage->have_csum = 0;
2561                 }
2562                 sblock->page_count++;
2563                 spage->page = alloc_page(GFP_KERNEL);
2564                 if (!spage->page)
2565                         goto leave_nomem;
2566                 len -= l;
2567                 logical += l;
2568                 physical += l;
2569         }
2570
2571         WARN_ON(sblock->page_count == 0);
2572         for (index = 0; index < sblock->page_count; index++) {
2573                 struct scrub_page *spage = sblock->pagev[index];
2574                 int ret;
2575
2576                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2577                 if (ret) {
2578                         scrub_block_put(sblock);
2579                         return ret;
2580                 }
2581         }
2582
2583         /* last one frees, either here or in bio completion for last page */
2584         scrub_block_put(sblock);
2585         return 0;
2586 }
2587
2588 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2589                                    u64 logical, u64 len,
2590                                    u64 physical, struct btrfs_device *dev,
2591                                    u64 flags, u64 gen, int mirror_num)
2592 {
2593         struct scrub_ctx *sctx = sparity->sctx;
2594         int ret;
2595         u8 csum[BTRFS_CSUM_SIZE];
2596         u32 blocksize;
2597
2598         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2599                 scrub_parity_mark_sectors_error(sparity, logical, len);
2600                 return 0;
2601         }
2602
2603         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2604                 blocksize = sparity->stripe_len;
2605         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2606                 blocksize = sparity->stripe_len;
2607         } else {
2608                 blocksize = sctx->fs_info->sectorsize;
2609                 WARN_ON(1);
2610         }
2611
2612         while (len) {
2613                 u64 l = min_t(u64, len, blocksize);
2614                 int have_csum = 0;
2615
2616                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2617                         /* push csums to sbio */
2618                         have_csum = scrub_find_csum(sctx, logical, csum);
2619                         if (have_csum == 0)
2620                                 goto skip;
2621                 }
2622                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2623                                              flags, gen, mirror_num,
2624                                              have_csum ? csum : NULL);
2625                 if (ret)
2626                         return ret;
2627 skip:
2628                 len -= l;
2629                 logical += l;
2630                 physical += l;
2631         }
2632         return 0;
2633 }
2634
2635 /*
2636  * Given a physical address, this will calculate it's
2637  * logical offset. if this is a parity stripe, it will return
2638  * the most left data stripe's logical offset.
2639  *
2640  * return 0 if it is a data stripe, 1 means parity stripe.
2641  */
2642 static int get_raid56_logic_offset(u64 physical, int num,
2643                                    struct map_lookup *map, u64 *offset,
2644                                    u64 *stripe_start)
2645 {
2646         int i;
2647         int j = 0;
2648         u64 stripe_nr;
2649         u64 last_offset;
2650         u32 stripe_index;
2651         u32 rot;
2652
2653         last_offset = (physical - map->stripes[num].physical) *
2654                       nr_data_stripes(map);
2655         if (stripe_start)
2656                 *stripe_start = last_offset;
2657
2658         *offset = last_offset;
2659         for (i = 0; i < nr_data_stripes(map); i++) {
2660                 *offset = last_offset + i * map->stripe_len;
2661
2662                 stripe_nr = div64_u64(*offset, map->stripe_len);
2663                 stripe_nr = div_u64(stripe_nr, nr_data_stripes(map));
2664
2665                 /* Work out the disk rotation on this stripe-set */
2666                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2667                 /* calculate which stripe this data locates */
2668                 rot += i;
2669                 stripe_index = rot % map->num_stripes;
2670                 if (stripe_index == num)
2671                         return 0;
2672                 if (stripe_index < num)
2673                         j++;
2674         }
2675         *offset = last_offset + j * map->stripe_len;
2676         return 1;
2677 }
2678
2679 static void scrub_free_parity(struct scrub_parity *sparity)
2680 {
2681         struct scrub_ctx *sctx = sparity->sctx;
2682         struct scrub_page *curr, *next;
2683         int nbits;
2684
2685         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2686         if (nbits) {
2687                 spin_lock(&sctx->stat_lock);
2688                 sctx->stat.read_errors += nbits;
2689                 sctx->stat.uncorrectable_errors += nbits;
2690                 spin_unlock(&sctx->stat_lock);
2691         }
2692
2693         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2694                 list_del_init(&curr->list);
2695                 scrub_page_put(curr);
2696         }
2697
2698         kfree(sparity);
2699 }
2700
2701 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2702 {
2703         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2704                                                     work);
2705         struct scrub_ctx *sctx = sparity->sctx;
2706
2707         scrub_free_parity(sparity);
2708         scrub_pending_bio_dec(sctx);
2709 }
2710
2711 static void scrub_parity_bio_endio(struct bio *bio)
2712 {
2713         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
2714         struct btrfs_fs_info *fs_info = sparity->sctx->fs_info;
2715
2716         if (bio->bi_status)
2717                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2718                           sparity->nsectors);
2719
2720         bio_put(bio);
2721
2722         btrfs_init_work(&sparity->work, btrfs_scrubparity_helper,
2723                         scrub_parity_bio_endio_worker, NULL, NULL);
2724         btrfs_queue_work(fs_info->scrub_parity_workers, &sparity->work);
2725 }
2726
2727 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
2728 {
2729         struct scrub_ctx *sctx = sparity->sctx;
2730         struct btrfs_fs_info *fs_info = sctx->fs_info;
2731         struct bio *bio;
2732         struct btrfs_raid_bio *rbio;
2733         struct btrfs_bio *bbio = NULL;
2734         u64 length;
2735         int ret;
2736
2737         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
2738                            sparity->nsectors))
2739                 goto out;
2740
2741         length = sparity->logic_end - sparity->logic_start;
2742
2743         btrfs_bio_counter_inc_blocked(fs_info);
2744         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,
2745                                &length, &bbio);
2746         if (ret || !bbio || !bbio->raid_map)
2747                 goto bbio_out;
2748
2749         bio = btrfs_io_bio_alloc(0);
2750         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
2751         bio->bi_private = sparity;
2752         bio->bi_end_io = scrub_parity_bio_endio;
2753
2754         rbio = raid56_parity_alloc_scrub_rbio(fs_info, bio, bbio,
2755                                               length, sparity->scrub_dev,
2756                                               sparity->dbitmap,
2757                                               sparity->nsectors);
2758         if (!rbio)
2759                 goto rbio_out;
2760
2761         scrub_pending_bio_inc(sctx);
2762         raid56_parity_submit_scrub_rbio(rbio);
2763         return;
2764
2765 rbio_out:
2766         bio_put(bio);
2767 bbio_out:
2768         btrfs_bio_counter_dec(fs_info);
2769         btrfs_put_bbio(bbio);
2770         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2771                   sparity->nsectors);
2772         spin_lock(&sctx->stat_lock);
2773         sctx->stat.malloc_errors++;
2774         spin_unlock(&sctx->stat_lock);
2775 out:
2776         scrub_free_parity(sparity);
2777 }
2778
2779 static inline int scrub_calc_parity_bitmap_len(int nsectors)
2780 {
2781         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
2782 }
2783
2784 static void scrub_parity_get(struct scrub_parity *sparity)
2785 {
2786         refcount_inc(&sparity->refs);
2787 }
2788
2789 static void scrub_parity_put(struct scrub_parity *sparity)
2790 {
2791         if (!refcount_dec_and_test(&sparity->refs))
2792                 return;
2793
2794         scrub_parity_check_and_repair(sparity);
2795 }
2796
2797 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
2798                                                   struct map_lookup *map,
2799                                                   struct btrfs_device *sdev,
2800                                                   struct btrfs_path *path,
2801                                                   u64 logic_start,
2802                                                   u64 logic_end)
2803 {
2804         struct btrfs_fs_info *fs_info = sctx->fs_info;
2805         struct btrfs_root *root = fs_info->extent_root;
2806         struct btrfs_root *csum_root = fs_info->csum_root;
2807         struct btrfs_extent_item *extent;
2808         struct btrfs_bio *bbio = NULL;
2809         u64 flags;
2810         int ret;
2811         int slot;
2812         struct extent_buffer *l;
2813         struct btrfs_key key;
2814         u64 generation;
2815         u64 extent_logical;
2816         u64 extent_physical;
2817         u64 extent_len;
2818         u64 mapped_length;
2819         struct btrfs_device *extent_dev;
2820         struct scrub_parity *sparity;
2821         int nsectors;
2822         int bitmap_len;
2823         int extent_mirror_num;
2824         int stop_loop = 0;
2825
2826         nsectors = div_u64(map->stripe_len, fs_info->sectorsize);
2827         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
2828         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
2829                           GFP_NOFS);
2830         if (!sparity) {
2831                 spin_lock(&sctx->stat_lock);
2832                 sctx->stat.malloc_errors++;
2833                 spin_unlock(&sctx->stat_lock);
2834                 return -ENOMEM;
2835         }
2836
2837         sparity->stripe_len = map->stripe_len;
2838         sparity->nsectors = nsectors;
2839         sparity->sctx = sctx;
2840         sparity->scrub_dev = sdev;
2841         sparity->logic_start = logic_start;
2842         sparity->logic_end = logic_end;
2843         refcount_set(&sparity->refs, 1);
2844         INIT_LIST_HEAD(&sparity->spages);
2845         sparity->dbitmap = sparity->bitmap;
2846         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
2847
2848         ret = 0;
2849         while (logic_start < logic_end) {
2850                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2851                         key.type = BTRFS_METADATA_ITEM_KEY;
2852                 else
2853                         key.type = BTRFS_EXTENT_ITEM_KEY;
2854                 key.objectid = logic_start;
2855                 key.offset = (u64)-1;
2856
2857                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2858                 if (ret < 0)
2859                         goto out;
2860
2861                 if (ret > 0) {
2862                         ret = btrfs_previous_extent_item(root, path, 0);
2863                         if (ret < 0)
2864                                 goto out;
2865                         if (ret > 0) {
2866                                 btrfs_release_path(path);
2867                                 ret = btrfs_search_slot(NULL, root, &key,
2868                                                         path, 0, 0);
2869                                 if (ret < 0)
2870                                         goto out;
2871                         }
2872                 }
2873
2874                 stop_loop = 0;
2875                 while (1) {
2876                         u64 bytes;
2877
2878                         l = path->nodes[0];
2879                         slot = path->slots[0];
2880                         if (slot >= btrfs_header_nritems(l)) {
2881                                 ret = btrfs_next_leaf(root, path);
2882                                 if (ret == 0)
2883                                         continue;
2884                                 if (ret < 0)
2885                                         goto out;
2886
2887                                 stop_loop = 1;
2888                                 break;
2889                         }
2890                         btrfs_item_key_to_cpu(l, &key, slot);
2891
2892                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2893                             key.type != BTRFS_METADATA_ITEM_KEY)
2894                                 goto next;
2895
2896                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2897                                 bytes = fs_info->nodesize;
2898                         else
2899                                 bytes = key.offset;
2900
2901                         if (key.objectid + bytes <= logic_start)
2902                                 goto next;
2903
2904                         if (key.objectid >= logic_end) {
2905                                 stop_loop = 1;
2906                                 break;
2907                         }
2908
2909                         while (key.objectid >= logic_start + map->stripe_len)
2910                                 logic_start += map->stripe_len;
2911
2912                         extent = btrfs_item_ptr(l, slot,
2913                                                 struct btrfs_extent_item);
2914                         flags = btrfs_extent_flags(l, extent);
2915                         generation = btrfs_extent_generation(l, extent);
2916
2917                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
2918                             (key.objectid < logic_start ||
2919                              key.objectid + bytes >
2920                              logic_start + map->stripe_len)) {
2921                                 btrfs_err(fs_info,
2922                                           "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
2923                                           key.objectid, logic_start);
2924                                 spin_lock(&sctx->stat_lock);
2925                                 sctx->stat.uncorrectable_errors++;
2926                                 spin_unlock(&sctx->stat_lock);
2927                                 goto next;
2928                         }
2929 again:
2930                         extent_logical = key.objectid;
2931                         extent_len = bytes;
2932
2933                         if (extent_logical < logic_start) {
2934                                 extent_len -= logic_start - extent_logical;
2935                                 extent_logical = logic_start;
2936                         }
2937
2938                         if (extent_logical + extent_len >
2939                             logic_start + map->stripe_len)
2940                                 extent_len = logic_start + map->stripe_len -
2941                                              extent_logical;
2942
2943                         scrub_parity_mark_sectors_data(sparity, extent_logical,
2944                                                        extent_len);
2945
2946                         mapped_length = extent_len;
2947                         bbio = NULL;
2948                         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ,
2949                                         extent_logical, &mapped_length, &bbio,
2950                                         0);
2951                         if (!ret) {
2952                                 if (!bbio || mapped_length < extent_len)
2953                                         ret = -EIO;
2954                         }
2955                         if (ret) {
2956                                 btrfs_put_bbio(bbio);
2957                                 goto out;
2958                         }
2959                         extent_physical = bbio->stripes[0].physical;
2960                         extent_mirror_num = bbio->mirror_num;
2961                         extent_dev = bbio->stripes[0].dev;
2962                         btrfs_put_bbio(bbio);
2963
2964                         ret = btrfs_lookup_csums_range(csum_root,
2965                                                 extent_logical,
2966                                                 extent_logical + extent_len - 1,
2967                                                 &sctx->csum_list, 1);
2968                         if (ret)
2969                                 goto out;
2970
2971                         ret = scrub_extent_for_parity(sparity, extent_logical,
2972                                                       extent_len,
2973                                                       extent_physical,
2974                                                       extent_dev, flags,
2975                                                       generation,
2976                                                       extent_mirror_num);
2977
2978                         scrub_free_csums(sctx);
2979
2980                         if (ret)
2981                                 goto out;
2982
2983                         if (extent_logical + extent_len <
2984                             key.objectid + bytes) {
2985                                 logic_start += map->stripe_len;
2986
2987                                 if (logic_start >= logic_end) {
2988                                         stop_loop = 1;
2989                                         break;
2990                                 }
2991
2992                                 if (logic_start < key.objectid + bytes) {
2993                                         cond_resched();
2994                                         goto again;
2995                                 }
2996                         }
2997 next:
2998                         path->slots[0]++;
2999                 }
3000
3001                 btrfs_release_path(path);
3002
3003                 if (stop_loop)
3004                         break;
3005
3006                 logic_start += map->stripe_len;
3007         }
3008 out:
3009         if (ret < 0)
3010                 scrub_parity_mark_sectors_error(sparity, logic_start,
3011                                                 logic_end - logic_start);
3012         scrub_parity_put(sparity);
3013         scrub_submit(sctx);
3014         mutex_lock(&sctx->wr_lock);
3015         scrub_wr_submit(sctx);
3016         mutex_unlock(&sctx->wr_lock);
3017
3018         btrfs_release_path(path);
3019         return ret < 0 ? ret : 0;
3020 }
3021
3022 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3023                                            struct map_lookup *map,
3024                                            struct btrfs_device *scrub_dev,
3025                                            int num, u64 base, u64 length)
3026 {
3027         struct btrfs_path *path, *ppath;
3028         struct btrfs_fs_info *fs_info = sctx->fs_info;
3029         struct btrfs_root *root = fs_info->extent_root;
3030         struct btrfs_root *csum_root = fs_info->csum_root;
3031         struct btrfs_extent_item *extent;
3032         struct blk_plug plug;
3033         u64 flags;
3034         int ret;
3035         int slot;
3036         u64 nstripes;
3037         struct extent_buffer *l;
3038         u64 physical;
3039         u64 logical;
3040         u64 logic_end;
3041         u64 physical_end;
3042         u64 generation;
3043         int mirror_num;
3044         struct reada_control *reada1;
3045         struct reada_control *reada2;
3046         struct btrfs_key key;
3047         struct btrfs_key key_end;
3048         u64 increment = map->stripe_len;
3049         u64 offset;
3050         u64 extent_logical;
3051         u64 extent_physical;
3052         u64 extent_len;
3053         u64 stripe_logical;
3054         u64 stripe_end;
3055         struct btrfs_device *extent_dev;
3056         int extent_mirror_num;
3057         int stop_loop = 0;
3058
3059         physical = map->stripes[num].physical;
3060         offset = 0;
3061         nstripes = div64_u64(length, map->stripe_len);
3062         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3063                 offset = map->stripe_len * num;
3064                 increment = map->stripe_len * map->num_stripes;
3065                 mirror_num = 1;
3066         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3067                 int factor = map->num_stripes / map->sub_stripes;
3068                 offset = map->stripe_len * (num / map->sub_stripes);
3069                 increment = map->stripe_len * factor;
3070                 mirror_num = num % map->sub_stripes + 1;
3071         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
3072                 increment = map->stripe_len;
3073                 mirror_num = num % map->num_stripes + 1;
3074         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3075                 increment = map->stripe_len;
3076                 mirror_num = num % map->num_stripes + 1;
3077         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3078                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3079                 increment = map->stripe_len * nr_data_stripes(map);
3080                 mirror_num = 1;
3081         } else {
3082                 increment = map->stripe_len;
3083                 mirror_num = 1;
3084         }
3085
3086         path = btrfs_alloc_path();
3087         if (!path)
3088                 return -ENOMEM;
3089
3090         ppath = btrfs_alloc_path();
3091         if (!ppath) {
3092                 btrfs_free_path(path);
3093                 return -ENOMEM;
3094         }
3095
3096         /*
3097          * work on commit root. The related disk blocks are static as
3098          * long as COW is applied. This means, it is save to rewrite
3099          * them to repair disk errors without any race conditions
3100          */
3101         path->search_commit_root = 1;
3102         path->skip_locking = 1;
3103
3104         ppath->search_commit_root = 1;
3105         ppath->skip_locking = 1;
3106         /*
3107          * trigger the readahead for extent tree csum tree and wait for
3108          * completion. During readahead, the scrub is officially paused
3109          * to not hold off transaction commits
3110          */
3111         logical = base + offset;
3112         physical_end = physical + nstripes * map->stripe_len;
3113         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3114                 get_raid56_logic_offset(physical_end, num,
3115                                         map, &logic_end, NULL);
3116                 logic_end += base;
3117         } else {
3118                 logic_end = logical + increment * nstripes;
3119         }
3120         wait_event(sctx->list_wait,
3121                    atomic_read(&sctx->bios_in_flight) == 0);
3122         scrub_blocked_if_needed(fs_info);
3123
3124         /* FIXME it might be better to start readahead at commit root */
3125         key.objectid = logical;
3126         key.type = BTRFS_EXTENT_ITEM_KEY;
3127         key.offset = (u64)0;
3128         key_end.objectid = logic_end;
3129         key_end.type = BTRFS_METADATA_ITEM_KEY;
3130         key_end.offset = (u64)-1;
3131         reada1 = btrfs_reada_add(root, &key, &key_end);
3132
3133         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3134         key.type = BTRFS_EXTENT_CSUM_KEY;
3135         key.offset = logical;
3136         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3137         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3138         key_end.offset = logic_end;
3139         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3140
3141         if (!IS_ERR(reada1))
3142                 btrfs_reada_wait(reada1);
3143         if (!IS_ERR(reada2))
3144                 btrfs_reada_wait(reada2);
3145
3146
3147         /*
3148          * collect all data csums for the stripe to avoid seeking during
3149          * the scrub. This might currently (crc32) end up to be about 1MB
3150          */
3151         blk_start_plug(&plug);
3152
3153         /*
3154          * now find all extents for each stripe and scrub them
3155          */
3156         ret = 0;
3157         while (physical < physical_end) {
3158                 /*
3159                  * canceled?
3160                  */
3161                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3162                     atomic_read(&sctx->cancel_req)) {
3163                         ret = -ECANCELED;
3164                         goto out;
3165                 }
3166                 /*
3167                  * check to see if we have to pause
3168                  */
3169                 if (atomic_read(&fs_info->scrub_pause_req)) {
3170                         /* push queued extents */
3171                         sctx->flush_all_writes = true;
3172                         scrub_submit(sctx);
3173                         mutex_lock(&sctx->wr_lock);
3174                         scrub_wr_submit(sctx);
3175                         mutex_unlock(&sctx->wr_lock);
3176                         wait_event(sctx->list_wait,
3177                                    atomic_read(&sctx->bios_in_flight) == 0);
3178                         sctx->flush_all_writes = false;
3179                         scrub_blocked_if_needed(fs_info);
3180                 }
3181
3182                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3183                         ret = get_raid56_logic_offset(physical, num, map,
3184                                                       &logical,
3185                                                       &stripe_logical);
3186                         logical += base;
3187                         if (ret) {
3188                                 /* it is parity strip */
3189                                 stripe_logical += base;
3190                                 stripe_end = stripe_logical + increment;
3191                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3192                                                           ppath, stripe_logical,
3193                                                           stripe_end);
3194                                 if (ret)
3195                                         goto out;
3196                                 goto skip;
3197                         }
3198                 }
3199
3200                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3201                         key.type = BTRFS_METADATA_ITEM_KEY;
3202                 else
3203                         key.type = BTRFS_EXTENT_ITEM_KEY;
3204                 key.objectid = logical;
3205                 key.offset = (u64)-1;
3206
3207                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3208                 if (ret < 0)
3209                         goto out;
3210
3211                 if (ret > 0) {
3212                         ret = btrfs_previous_extent_item(root, path, 0);
3213                         if (ret < 0)
3214                                 goto out;
3215                         if (ret > 0) {
3216                                 /* there's no smaller item, so stick with the
3217                                  * larger one */
3218                                 btrfs_release_path(path);
3219                                 ret = btrfs_search_slot(NULL, root, &key,
3220                                                         path, 0, 0);
3221                                 if (ret < 0)
3222                                         goto out;
3223                         }
3224                 }
3225
3226                 stop_loop = 0;
3227                 while (1) {
3228                         u64 bytes;
3229
3230                         l = path->nodes[0];
3231                         slot = path->slots[0];
3232                         if (slot >= btrfs_header_nritems(l)) {
3233                                 ret = btrfs_next_leaf(root, path);
3234                                 if (ret == 0)
3235                                         continue;
3236                                 if (ret < 0)
3237                                         goto out;
3238
3239                                 stop_loop = 1;
3240                                 break;
3241                         }
3242                         btrfs_item_key_to_cpu(l, &key, slot);
3243
3244                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3245                             key.type != BTRFS_METADATA_ITEM_KEY)
3246                                 goto next;
3247
3248                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3249                                 bytes = fs_info->nodesize;
3250                         else
3251                                 bytes = key.offset;
3252
3253                         if (key.objectid + bytes <= logical)
3254                                 goto next;
3255
3256                         if (key.objectid >= logical + map->stripe_len) {
3257                                 /* out of this device extent */
3258                                 if (key.objectid >= logic_end)
3259                                         stop_loop = 1;
3260                                 break;
3261                         }
3262
3263                         extent = btrfs_item_ptr(l, slot,
3264                                                 struct btrfs_extent_item);
3265                         flags = btrfs_extent_flags(l, extent);
3266                         generation = btrfs_extent_generation(l, extent);
3267
3268                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3269                             (key.objectid < logical ||
3270                              key.objectid + bytes >
3271                              logical + map->stripe_len)) {
3272                                 btrfs_err(fs_info,
3273                                            "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
3274                                        key.objectid, logical);
3275                                 spin_lock(&sctx->stat_lock);
3276                                 sctx->stat.uncorrectable_errors++;
3277                                 spin_unlock(&sctx->stat_lock);
3278                                 goto next;
3279                         }
3280
3281 again:
3282                         extent_logical = key.objectid;
3283                         extent_len = bytes;
3284
3285                         /*
3286                          * trim extent to this stripe
3287                          */
3288                         if (extent_logical < logical) {
3289                                 extent_len -= logical - extent_logical;
3290                                 extent_logical = logical;
3291                         }
3292                         if (extent_logical + extent_len >
3293                             logical + map->stripe_len) {
3294                                 extent_len = logical + map->stripe_len -
3295                                              extent_logical;
3296                         }
3297
3298                         extent_physical = extent_logical - logical + physical;
3299                         extent_dev = scrub_dev;
3300                         extent_mirror_num = mirror_num;
3301                         if (sctx->is_dev_replace)
3302                                 scrub_remap_extent(fs_info, extent_logical,
3303                                                    extent_len, &extent_physical,
3304                                                    &extent_dev,
3305                                                    &extent_mirror_num);
3306
3307                         ret = btrfs_lookup_csums_range(csum_root,
3308                                                        extent_logical,
3309                                                        extent_logical +
3310                                                        extent_len - 1,
3311                                                        &sctx->csum_list, 1);
3312                         if (ret)
3313                                 goto out;
3314
3315                         ret = scrub_extent(sctx, map, extent_logical, extent_len,
3316                                            extent_physical, extent_dev, flags,
3317                                            generation, extent_mirror_num,
3318                                            extent_logical - logical + physical);
3319
3320                         scrub_free_csums(sctx);
3321
3322                         if (ret)
3323                                 goto out;
3324
3325                         if (extent_logical + extent_len <
3326                             key.objectid + bytes) {
3327                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3328                                         /*
3329                                          * loop until we find next data stripe
3330                                          * or we have finished all stripes.
3331                                          */
3332 loop:
3333                                         physical += map->stripe_len;
3334                                         ret = get_raid56_logic_offset(physical,
3335                                                         num, map, &logical,
3336                                                         &stripe_logical);
3337                                         logical += base;
3338
3339                                         if (ret && physical < physical_end) {
3340                                                 stripe_logical += base;
3341                                                 stripe_end = stripe_logical +
3342                                                                 increment;
3343                                                 ret = scrub_raid56_parity(sctx,
3344                                                         map, scrub_dev, ppath,
3345                                                         stripe_logical,
3346                                                         stripe_end);
3347                                                 if (ret)
3348                                                         goto out;
3349                                                 goto loop;
3350                                         }
3351                                 } else {
3352                                         physical += map->stripe_len;
3353                                         logical += increment;
3354                                 }
3355                                 if (logical < key.objectid + bytes) {
3356                                         cond_resched();
3357                                         goto again;
3358                                 }
3359
3360                                 if (physical >= physical_end) {
3361                                         stop_loop = 1;
3362                                         break;
3363                                 }
3364                         }
3365 next:
3366                         path->slots[0]++;
3367                 }
3368                 btrfs_release_path(path);
3369 skip:
3370                 logical += increment;
3371                 physical += map->stripe_len;
3372                 spin_lock(&sctx->stat_lock);
3373                 if (stop_loop)
3374                         sctx->stat.last_physical = map->stripes[num].physical +
3375                                                    length;
3376                 else
3377                         sctx->stat.last_physical = physical;
3378                 spin_unlock(&sctx->stat_lock);
3379                 if (stop_loop)
3380                         break;
3381         }
3382 out:
3383         /* push queued extents */
3384         scrub_submit(sctx);
3385         mutex_lock(&sctx->wr_lock);
3386         scrub_wr_submit(sctx);
3387         mutex_unlock(&sctx->wr_lock);
3388
3389         blk_finish_plug(&plug);
3390         btrfs_free_path(path);
3391         btrfs_free_path(ppath);
3392         return ret < 0 ? ret : 0;
3393 }
3394
3395 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3396                                           struct btrfs_device *scrub_dev,
3397                                           u64 chunk_offset, u64 length,
3398                                           u64 dev_offset,
3399                                           struct btrfs_block_group_cache *cache)
3400 {
3401         struct btrfs_fs_info *fs_info = sctx->fs_info;
3402         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
3403         struct map_lookup *map;
3404         struct extent_map *em;
3405         int i;
3406         int ret = 0;
3407
3408         read_lock(&map_tree->map_tree.lock);
3409         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
3410         read_unlock(&map_tree->map_tree.lock);
3411
3412         if (!em) {
3413                 /*
3414                  * Might have been an unused block group deleted by the cleaner
3415                  * kthread or relocation.
3416                  */
3417                 spin_lock(&cache->lock);
3418                 if (!cache->removed)
3419                         ret = -EINVAL;
3420                 spin_unlock(&cache->lock);
3421
3422                 return ret;
3423         }
3424
3425         map = em->map_lookup;
3426         if (em->start != chunk_offset)
3427                 goto out;
3428
3429         if (em->len < length)
3430                 goto out;
3431
3432         for (i = 0; i < map->num_stripes; ++i) {
3433                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3434                     map->stripes[i].physical == dev_offset) {
3435                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3436                                            chunk_offset, length);
3437                         if (ret)
3438                                 goto out;
3439                 }
3440         }
3441 out:
3442         free_extent_map(em);
3443
3444         return ret;
3445 }
3446
3447 static noinline_for_stack
3448 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3449                            struct btrfs_device *scrub_dev, u64 start, u64 end)
3450 {
3451         struct btrfs_dev_extent *dev_extent = NULL;
3452         struct btrfs_path *path;
3453         struct btrfs_fs_info *fs_info = sctx->fs_info;
3454         struct btrfs_root *root = fs_info->dev_root;
3455         u64 length;
3456         u64 chunk_offset;
3457         int ret = 0;
3458         int ro_set;
3459         int slot;
3460         struct extent_buffer *l;
3461         struct btrfs_key key;
3462         struct btrfs_key found_key;
3463         struct btrfs_block_group_cache *cache;
3464         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3465
3466         path = btrfs_alloc_path();
3467         if (!path)
3468                 return -ENOMEM;
3469
3470         path->reada = READA_FORWARD;
3471         path->search_commit_root = 1;
3472         path->skip_locking = 1;
3473
3474         key.objectid = scrub_dev->devid;
3475         key.offset = 0ull;
3476         key.type = BTRFS_DEV_EXTENT_KEY;
3477
3478         while (1) {
3479                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3480                 if (ret < 0)
3481                         break;
3482                 if (ret > 0) {
3483                         if (path->slots[0] >=
3484                             btrfs_header_nritems(path->nodes[0])) {
3485                                 ret = btrfs_next_leaf(root, path);
3486                                 if (ret < 0)
3487                                         break;
3488                                 if (ret > 0) {
3489                                         ret = 0;
3490                                         break;
3491                                 }
3492                         } else {
3493                                 ret = 0;
3494                         }
3495                 }
3496
3497                 l = path->nodes[0];
3498                 slot = path->slots[0];
3499
3500                 btrfs_item_key_to_cpu(l, &found_key, slot);
3501
3502                 if (found_key.objectid != scrub_dev->devid)
3503                         break;
3504
3505                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3506                         break;
3507
3508                 if (found_key.offset >= end)
3509                         break;
3510
3511                 if (found_key.offset < key.offset)
3512                         break;
3513
3514                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3515                 length = btrfs_dev_extent_length(l, dev_extent);
3516
3517                 if (found_key.offset + length <= start)
3518                         goto skip;
3519
3520                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3521
3522                 /*
3523                  * get a reference on the corresponding block group to prevent
3524                  * the chunk from going away while we scrub it
3525                  */
3526                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3527
3528                 /* some chunks are removed but not committed to disk yet,
3529                  * continue scrubbing */
3530                 if (!cache)
3531                         goto skip;
3532
3533                 /*
3534                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3535                  * to avoid deadlock caused by:
3536                  * btrfs_inc_block_group_ro()
3537                  * -> btrfs_wait_for_commit()
3538                  * -> btrfs_commit_transaction()
3539                  * -> btrfs_scrub_pause()
3540                  */
3541                 scrub_pause_on(fs_info);
3542                 ret = btrfs_inc_block_group_ro(cache);
3543                 if (!ret && sctx->is_dev_replace) {
3544                         /*
3545                          * If we are doing a device replace wait for any tasks
3546                          * that started dellaloc right before we set the block
3547                          * group to RO mode, as they might have just allocated
3548                          * an extent from it or decided they could do a nocow
3549                          * write. And if any such tasks did that, wait for their
3550                          * ordered extents to complete and then commit the
3551                          * current transaction, so that we can later see the new
3552                          * extent items in the extent tree - the ordered extents
3553                          * create delayed data references (for cow writes) when
3554                          * they complete, which will be run and insert the
3555                          * corresponding extent items into the extent tree when
3556                          * we commit the transaction they used when running
3557                          * inode.c:btrfs_finish_ordered_io(). We later use
3558                          * the commit root of the extent tree to find extents
3559                          * to copy from the srcdev into the tgtdev, and we don't
3560                          * want to miss any new extents.
3561                          */
3562                         btrfs_wait_block_group_reservations(cache);
3563                         btrfs_wait_nocow_writers(cache);
3564                         ret = btrfs_wait_ordered_roots(fs_info, U64_MAX,
3565                                                        cache->key.objectid,
3566                                                        cache->key.offset);
3567                         if (ret > 0) {
3568                                 struct btrfs_trans_handle *trans;
3569
3570                                 trans = btrfs_join_transaction(root);
3571                                 if (IS_ERR(trans))
3572                                         ret = PTR_ERR(trans);
3573                                 else
3574                                         ret = btrfs_commit_transaction(trans);
3575                                 if (ret) {
3576                                         scrub_pause_off(fs_info);
3577                                         btrfs_put_block_group(cache);
3578                                         break;
3579                                 }
3580                         }
3581                 }
3582                 scrub_pause_off(fs_info);
3583
3584                 if (ret == 0) {
3585                         ro_set = 1;
3586                 } else if (ret == -ENOSPC) {
3587                         /*
3588                          * btrfs_inc_block_group_ro return -ENOSPC when it
3589                          * failed in creating new chunk for metadata.
3590                          * It is not a problem for scrub/replace, because
3591                          * metadata are always cowed, and our scrub paused
3592                          * commit_transactions.
3593                          */
3594                         ro_set = 0;
3595                 } else {
3596                         btrfs_warn(fs_info,
3597                                    "failed setting block group ro: %d", ret);
3598                         btrfs_put_block_group(cache);
3599                         break;
3600                 }
3601
3602                 btrfs_dev_replace_write_lock(&fs_info->dev_replace);
3603                 dev_replace->cursor_right = found_key.offset + length;
3604                 dev_replace->cursor_left = found_key.offset;
3605                 dev_replace->item_needs_writeback = 1;
3606                 btrfs_dev_replace_write_unlock(&fs_info->dev_replace);
3607                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3608                                   found_key.offset, cache);
3609
3610                 /*
3611                  * flush, submit all pending read and write bios, afterwards
3612                  * wait for them.
3613                  * Note that in the dev replace case, a read request causes
3614                  * write requests that are submitted in the read completion
3615                  * worker. Therefore in the current situation, it is required
3616                  * that all write requests are flushed, so that all read and
3617                  * write requests are really completed when bios_in_flight
3618                  * changes to 0.
3619                  */
3620                 sctx->flush_all_writes = true;
3621                 scrub_submit(sctx);
3622                 mutex_lock(&sctx->wr_lock);
3623                 scrub_wr_submit(sctx);
3624                 mutex_unlock(&sctx->wr_lock);
3625
3626                 wait_event(sctx->list_wait,
3627                            atomic_read(&sctx->bios_in_flight) == 0);
3628
3629                 scrub_pause_on(fs_info);
3630
3631                 /*
3632                  * must be called before we decrease @scrub_paused.
3633                  * make sure we don't block transaction commit while
3634                  * we are waiting pending workers finished.
3635                  */
3636                 wait_event(sctx->list_wait,
3637                            atomic_read(&sctx->workers_pending) == 0);
3638                 sctx->flush_all_writes = false;
3639
3640                 scrub_pause_off(fs_info);
3641
3642                 btrfs_dev_replace_write_lock(&fs_info->dev_replace);
3643                 dev_replace->cursor_left = dev_replace->cursor_right;
3644                 dev_replace->item_needs_writeback = 1;
3645                 btrfs_dev_replace_write_unlock(&fs_info->dev_replace);
3646
3647                 if (ro_set)
3648                         btrfs_dec_block_group_ro(cache);
3649
3650                 /*
3651                  * We might have prevented the cleaner kthread from deleting
3652                  * this block group if it was already unused because we raced
3653                  * and set it to RO mode first. So add it back to the unused
3654                  * list, otherwise it might not ever be deleted unless a manual
3655                  * balance is triggered or it becomes used and unused again.
3656                  */
3657                 spin_lock(&cache->lock);
3658                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3659                     btrfs_block_group_used(&cache->item) == 0) {
3660                         spin_unlock(&cache->lock);
3661                         btrfs_mark_bg_unused(cache);
3662                 } else {
3663                         spin_unlock(&cache->lock);
3664                 }
3665
3666                 btrfs_put_block_group(cache);
3667                 if (ret)
3668                         break;
3669                 if (sctx->is_dev_replace &&
3670                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3671                         ret = -EIO;
3672                         break;
3673                 }
3674                 if (sctx->stat.malloc_errors > 0) {
3675                         ret = -ENOMEM;
3676                         break;
3677                 }
3678 skip:
3679                 key.offset = found_key.offset + length;
3680                 btrfs_release_path(path);
3681         }
3682
3683         btrfs_free_path(path);
3684
3685         return ret;
3686 }
3687
3688 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3689                                            struct btrfs_device *scrub_dev)
3690 {
3691         int     i;
3692         u64     bytenr;
3693         u64     gen;
3694         int     ret;
3695         struct btrfs_fs_info *fs_info = sctx->fs_info;
3696
3697         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
3698                 return -EIO;
3699
3700         /* Seed devices of a new filesystem has their own generation. */
3701         if (scrub_dev->fs_devices != fs_info->fs_devices)
3702                 gen = scrub_dev->generation;
3703         else
3704                 gen = fs_info->last_trans_committed;
3705
3706         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
3707                 bytenr = btrfs_sb_offset(i);
3708                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
3709                     scrub_dev->commit_total_bytes)
3710                         break;
3711
3712                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
3713                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
3714                                   NULL, 1, bytenr);
3715                 if (ret)
3716                         return ret;
3717         }
3718         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3719
3720         return 0;
3721 }
3722
3723 /*
3724  * get a reference count on fs_info->scrub_workers. start worker if necessary
3725  */
3726 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
3727                                                 int is_dev_replace)
3728 {
3729         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
3730         int max_active = fs_info->thread_pool_size;
3731
3732         if (fs_info->scrub_workers_refcnt == 0) {
3733                 fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub",
3734                                 flags, is_dev_replace ? 1 : max_active, 4);
3735                 if (!fs_info->scrub_workers)
3736                         goto fail_scrub_workers;
3737
3738                 fs_info->scrub_wr_completion_workers =
3739                         btrfs_alloc_workqueue(fs_info, "scrubwrc", flags,
3740                                               max_active, 2);
3741                 if (!fs_info->scrub_wr_completion_workers)
3742                         goto fail_scrub_wr_completion_workers;
3743
3744                 fs_info->scrub_parity_workers =
3745                         btrfs_alloc_workqueue(fs_info, "scrubparity", flags,
3746                                               max_active, 2);
3747                 if (!fs_info->scrub_parity_workers)
3748                         goto fail_scrub_parity_workers;
3749         }
3750         ++fs_info->scrub_workers_refcnt;
3751         return 0;
3752
3753 fail_scrub_parity_workers:
3754         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3755 fail_scrub_wr_completion_workers:
3756         btrfs_destroy_workqueue(fs_info->scrub_workers);
3757 fail_scrub_workers:
3758         return -ENOMEM;
3759 }
3760
3761 static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
3762 {
3763         if (--fs_info->scrub_workers_refcnt == 0) {
3764                 btrfs_destroy_workqueue(fs_info->scrub_workers);
3765                 btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3766                 btrfs_destroy_workqueue(fs_info->scrub_parity_workers);
3767         }
3768         WARN_ON(fs_info->scrub_workers_refcnt < 0);
3769 }
3770
3771 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
3772                     u64 end, struct btrfs_scrub_progress *progress,
3773                     int readonly, int is_dev_replace)
3774 {
3775         struct scrub_ctx *sctx;
3776         int ret;
3777         struct btrfs_device *dev;
3778
3779         if (btrfs_fs_closing(fs_info))
3780                 return -EINVAL;
3781
3782         if (fs_info->nodesize > BTRFS_STRIPE_LEN) {
3783                 /*
3784                  * in this case scrub is unable to calculate the checksum
3785                  * the way scrub is implemented. Do not handle this
3786                  * situation at all because it won't ever happen.
3787                  */
3788                 btrfs_err(fs_info,
3789                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
3790                        fs_info->nodesize,
3791                        BTRFS_STRIPE_LEN);
3792                 return -EINVAL;
3793         }
3794
3795         if (fs_info->sectorsize != PAGE_SIZE) {
3796                 /* not supported for data w/o checksums */
3797                 btrfs_err_rl(fs_info,
3798                            "scrub: size assumption sectorsize != PAGE_SIZE (%d != %lu) fails",
3799                        fs_info->sectorsize, PAGE_SIZE);
3800                 return -EINVAL;
3801         }
3802
3803         if (fs_info->nodesize >
3804             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
3805             fs_info->sectorsize > PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
3806                 /*
3807                  * would exhaust the array bounds of pagev member in
3808                  * struct scrub_block
3809                  */
3810                 btrfs_err(fs_info,
3811                           "scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
3812                        fs_info->nodesize,
3813                        SCRUB_MAX_PAGES_PER_BLOCK,
3814                        fs_info->sectorsize,
3815                        SCRUB_MAX_PAGES_PER_BLOCK);
3816                 return -EINVAL;
3817         }
3818
3819
3820         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3821         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
3822         if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) &&
3823                      !is_dev_replace)) {
3824                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3825                 return -ENODEV;
3826         }
3827
3828         if (!is_dev_replace && !readonly &&
3829             !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
3830                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3831                 btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable",
3832                                 rcu_str_deref(dev->name));
3833                 return -EROFS;
3834         }
3835
3836         mutex_lock(&fs_info->scrub_lock);
3837         if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
3838             test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) {
3839                 mutex_unlock(&fs_info->scrub_lock);
3840                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3841                 return -EIO;
3842         }
3843
3844         btrfs_dev_replace_read_lock(&fs_info->dev_replace);
3845         if (dev->scrub_ctx ||
3846             (!is_dev_replace &&
3847              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
3848                 btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
3849                 mutex_unlock(&fs_info->scrub_lock);
3850                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3851                 return -EINPROGRESS;
3852         }
3853         btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
3854
3855         ret = scrub_workers_get(fs_info, is_dev_replace);
3856         if (ret) {
3857                 mutex_unlock(&fs_info->scrub_lock);
3858                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3859                 return ret;
3860         }
3861
3862         sctx = scrub_setup_ctx(dev, is_dev_replace);
3863         if (IS_ERR(sctx)) {
3864                 mutex_unlock(&fs_info->scrub_lock);
3865                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3866                 scrub_workers_put(fs_info);
3867                 return PTR_ERR(sctx);
3868         }
3869         sctx->readonly = readonly;
3870         dev->scrub_ctx = sctx;
3871         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3872
3873         /*
3874          * checking @scrub_pause_req here, we can avoid
3875          * race between committing transaction and scrubbing.
3876          */
3877         __scrub_blocked_if_needed(fs_info);
3878         atomic_inc(&fs_info->scrubs_running);
3879         mutex_unlock(&fs_info->scrub_lock);
3880
3881         if (!is_dev_replace) {
3882                 /*
3883                  * by holding device list mutex, we can
3884                  * kick off writing super in log tree sync.
3885                  */
3886                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
3887                 ret = scrub_supers(sctx, dev);
3888                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3889         }
3890
3891         if (!ret)
3892                 ret = scrub_enumerate_chunks(sctx, dev, start, end);
3893
3894         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3895         atomic_dec(&fs_info->scrubs_running);
3896         wake_up(&fs_info->scrub_pause_wait);
3897
3898         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3899
3900         if (progress)
3901                 memcpy(progress, &sctx->stat, sizeof(*progress));
3902
3903         mutex_lock(&fs_info->scrub_lock);
3904         dev->scrub_ctx = NULL;
3905         scrub_workers_put(fs_info);
3906         mutex_unlock(&fs_info->scrub_lock);
3907
3908         scrub_put_ctx(sctx);
3909
3910         return ret;
3911 }
3912
3913 void btrfs_scrub_pause(struct btrfs_fs_info *fs_info)
3914 {
3915         mutex_lock(&fs_info->scrub_lock);
3916         atomic_inc(&fs_info->scrub_pause_req);
3917         while (atomic_read(&fs_info->scrubs_paused) !=
3918                atomic_read(&fs_info->scrubs_running)) {
3919                 mutex_unlock(&fs_info->scrub_lock);
3920                 wait_event(fs_info->scrub_pause_wait,
3921                            atomic_read(&fs_info->scrubs_paused) ==
3922                            atomic_read(&fs_info->scrubs_running));
3923                 mutex_lock(&fs_info->scrub_lock);
3924         }
3925         mutex_unlock(&fs_info->scrub_lock);
3926 }
3927
3928 void btrfs_scrub_continue(struct btrfs_fs_info *fs_info)
3929 {
3930         atomic_dec(&fs_info->scrub_pause_req);
3931         wake_up(&fs_info->scrub_pause_wait);
3932 }
3933
3934 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
3935 {
3936         mutex_lock(&fs_info->scrub_lock);
3937         if (!atomic_read(&fs_info->scrubs_running)) {
3938                 mutex_unlock(&fs_info->scrub_lock);
3939                 return -ENOTCONN;
3940         }
3941
3942         atomic_inc(&fs_info->scrub_cancel_req);
3943         while (atomic_read(&fs_info->scrubs_running)) {
3944                 mutex_unlock(&fs_info->scrub_lock);
3945                 wait_event(fs_info->scrub_pause_wait,
3946                            atomic_read(&fs_info->scrubs_running) == 0);
3947                 mutex_lock(&fs_info->scrub_lock);
3948         }
3949         atomic_dec(&fs_info->scrub_cancel_req);
3950         mutex_unlock(&fs_info->scrub_lock);
3951
3952         return 0;
3953 }
3954
3955 int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
3956                            struct btrfs_device *dev)
3957 {
3958         struct scrub_ctx *sctx;
3959
3960         mutex_lock(&fs_info->scrub_lock);
3961         sctx = dev->scrub_ctx;
3962         if (!sctx) {
3963                 mutex_unlock(&fs_info->scrub_lock);
3964                 return -ENOTCONN;
3965         }
3966         atomic_inc(&sctx->cancel_req);
3967         while (dev->scrub_ctx) {
3968                 mutex_unlock(&fs_info->scrub_lock);
3969                 wait_event(fs_info->scrub_pause_wait,
3970                            dev->scrub_ctx == NULL);
3971                 mutex_lock(&fs_info->scrub_lock);
3972         }
3973         mutex_unlock(&fs_info->scrub_lock);
3974
3975         return 0;
3976 }
3977
3978 int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
3979                          struct btrfs_scrub_progress *progress)
3980 {
3981         struct btrfs_device *dev;
3982         struct scrub_ctx *sctx = NULL;
3983
3984         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3985         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
3986         if (dev)
3987                 sctx = dev->scrub_ctx;
3988         if (sctx)
3989                 memcpy(progress, &sctx->stat, sizeof(*progress));
3990         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3991
3992         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
3993 }
3994
3995 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
3996                                u64 extent_logical, u64 extent_len,
3997                                u64 *extent_physical,
3998                                struct btrfs_device **extent_dev,
3999                                int *extent_mirror_num)
4000 {
4001         u64 mapped_length;
4002         struct btrfs_bio *bbio = NULL;
4003         int ret;
4004
4005         mapped_length = extent_len;
4006         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, extent_logical,
4007                               &mapped_length, &bbio, 0);
4008         if (ret || !bbio || mapped_length < extent_len ||
4009             !bbio->stripes[0].dev->bdev) {
4010                 btrfs_put_bbio(bbio);
4011                 return;
4012         }
4013
4014         *extent_physical = bbio->stripes[0].physical;
4015         *extent_mirror_num = bbio->mirror_num;
4016         *extent_dev = bbio->stripes[0].dev;
4017         btrfs_put_bbio(bbio);
4018 }