root/fs/btrfs/scrub.c

DEFINITIONS

1. scrub_is_page_on_raid56
2. scrub_pending_bio_inc
3. scrub_pending_bio_dec
4. __scrub_blocked_if_needed
5. scrub_pause_on
6. scrub_pause_off
7. scrub_blocked_if_needed
8. insert_full_stripe_lock
9. search_full_stripe_lock
10. get_full_stripe_logical
11. lock_full_stripe
12. unlock_full_stripe
13. scrub_free_csums
14. scrub_free_ctx
15. scrub_put_ctx
16. scrub_setup_ctx
17. scrub_print_warning_inode
18. scrub_print_warning
19. scrub_get_recover
20. scrub_put_recover
21. scrub_handle_errored_block
22. scrub_nr_raid_mirrors
23. scrub_stripe_index_and_offset
24. scrub_setup_recheck_block
25. scrub_bio_wait_endio
26. scrub_submit_raid56_bio_wait
27. scrub_recheck_block_on_raid56
28. scrub_recheck_block
29. scrub_check_fsid
30. scrub_recheck_block_checksum
31. scrub_repair_block_from_good_copy
32. scrub_repair_page_from_good_copy
33. scrub_write_block_to_dev_replace
34. scrub_write_page_to_dev_replace
35. scrub_add_page_to_wr_bio
36. scrub_wr_submit
37. scrub_wr_bio_end_io
38. scrub_wr_bio_end_io_worker
39. scrub_checksum
40. scrub_checksum_data
41. scrub_checksum_tree_block
42. scrub_checksum_super
43. scrub_block_get
44. scrub_block_put
45. scrub_page_get
46. scrub_page_put
47. scrub_submit
48. scrub_add_page_to_rd_bio
49. scrub_missing_raid56_end_io
50. scrub_missing_raid56_worker
51. scrub_missing_raid56_pages
52. scrub_pages
53. scrub_bio_end_io
54. scrub_bio_end_io_worker
55. __scrub_mark_bitmap
56. scrub_parity_mark_sectors_error
57. scrub_parity_mark_sectors_data
58. scrub_block_complete
59. scrub_find_csum
60. scrub_extent
61. scrub_pages_for_parity
62. scrub_extent_for_parity
63. get_raid56_logic_offset
64. scrub_free_parity
65. scrub_parity_bio_endio_worker
66. scrub_parity_bio_endio
67. scrub_parity_check_and_repair
68. scrub_calc_parity_bitmap_len
69. scrub_parity_get
70. scrub_parity_put
71. scrub_raid56_parity
72. scrub_stripe
73. scrub_chunk
74. scrub_enumerate_chunks
75. scrub_supers
76. scrub_workers_get
77. btrfs_scrub_dev
78. btrfs_scrub_pause
79. btrfs_scrub_continue
80. btrfs_scrub_cancel
81. btrfs_scrub_cancel_dev
82. btrfs_scrub_progress
83. scrub_remap_extent

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