fs/btrfs/scrub.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2011, 2012 STRATO.  All rights reserved.
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/ratelimit.h>
   8 #include <linux/sched/mm.h>
   9 #include <crypto/hash.h>
  10 #include "ctree.h"
  11 #include "discard.h"
  12 #include "volumes.h"
  13 #include "disk-io.h"
  14 #include "ordered-data.h"
  15 #include "transaction.h"
  16 #include "backref.h"
  17 #include "extent_io.h"
  18 #include "dev-replace.h"
  19 #include "check-integrity.h"
  20 #include "rcu-string.h"
  21 #include "raid56.h"
  22 #include "block-group.h"
  23
  24 /*
  25  * This is only the first step towards a full-features scrub. It reads all
  26  * extent and super block and verifies the checksums. In case a bad checksum
  27  * is found or the extent cannot be read, good data will be written back if
  28  * any can be found.
  29  *
  30  * Future enhancements:
  31  *  - In case an unrepairable extent is encountered, track which files are
  32  *    affected and report them
  33  *  - track and record media errors, throw out bad devices
  34  *  - add a mode to also read unallocated space
  35  */
  36
  37 struct scrub_block;
  38 struct scrub_ctx;
  39
  40 /*
  41  * the following three values only influence the performance.
  42  * The last one configures the number of parallel and outstanding I/O
  43  * operations. The first two values configure an upper limit for the number
  44  * of (dynamically allocated) pages that are added to a bio.
  45  */
  46 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  47 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  48 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  49
  50 /*
  51  * the following value times PAGE_SIZE needs to be large enough to match the
  52  * largest node/leaf/sector size that shall be supported.
  53  * Values larger than BTRFS_STRIPE_LEN are not supported.
  54  */
  55 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  56
  57 struct scrub_recover {
  58         refcount_t              refs;
  59         struct btrfs_bio        *bbio;
  60         u64                     map_length;
  61 };
  62
  63 struct scrub_page {
  64         struct scrub_block      *sblock;
  65         struct page             *page;
  66         struct btrfs_device     *dev;
  67         struct list_head        list;
  68         u64                     flags;  /* extent flags */
  69         u64                     generation;
  70         u64                     logical;
  71         u64                     physical;
  72         u64                     physical_for_dev_replace;
  73         atomic_t                refs;
  74         struct {
  75                 unsigned int    mirror_num:8;
  76                 unsigned int    have_csum:1;
  77                 unsigned int    io_error:1;
  78         };
  79         u8                      csum[BTRFS_CSUM_SIZE];
  80
  81         struct scrub_recover    *recover;
  82 };
  83
  84 struct scrub_bio {
  85         int                     index;
  86         struct scrub_ctx        *sctx;
  87         struct btrfs_device     *dev;
  88         struct bio              *bio;
  89         blk_status_t            status;
  90         u64                     logical;
  91         u64                     physical;
  92 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
  93         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
  94 #else
  95         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
  96 #endif
  97         int                     page_count;
  98         int                     next_free;
  99         struct btrfs_work       work;
 100 };
 101
 102 struct scrub_block {
 103         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 104         int                     page_count;
 105         atomic_t                outstanding_pages;
 106         refcount_t              refs; /* free mem on transition to zero */
 107         struct scrub_ctx        *sctx;
 108         struct scrub_parity     *sparity;
 109         struct {
 110                 unsigned int    header_error:1;
 111                 unsigned int    checksum_error:1;
 112                 unsigned int    no_io_error_seen:1;
 113                 unsigned int    generation_error:1; /* also sets header_error */
 114
 115                 /* The following is for the data used to check parity */
 116                 /* It is for the data with checksum */
 117                 unsigned int    data_corrected:1;
 118         };
 119         struct btrfs_work       work;
 120 };
 121
 122 /* Used for the chunks with parity stripe such RAID5/6 */
 123 struct scrub_parity {
 124         struct scrub_ctx        *sctx;
 125
 126         struct btrfs_device     *scrub_dev;
 127
 128         u64                     logic_start;
 129
 130         u64                     logic_end;
 131
 132         int                     nsectors;
 133
 134         u64                     stripe_len;
 135
 136         refcount_t              refs;
 137
 138         struct list_head        spages;
 139
 140         /* Work of parity check and repair */
 141         struct btrfs_work       work;
 142
 143         /* Mark the parity blocks which have data */
 144         unsigned long           *dbitmap;
 145
 146         /*
 147          * Mark the parity blocks which have data, but errors happen when
 148          * read data or check data
 149          */
 150         unsigned long           *ebitmap;
 151
 152         unsigned long           bitmap[];
 153 };
 154
 155 struct scrub_ctx {
 156         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 157         struct btrfs_fs_info    *fs_info;
 158         int                     first_free;
 159         int                     curr;
 160         atomic_t                bios_in_flight;
 161         atomic_t                workers_pending;
 162         spinlock_t              list_lock;
 163         wait_queue_head_t       list_wait;
 164         u16                     csum_size;
 165         struct list_head        csum_list;
 166         atomic_t                cancel_req;
 167         int                     readonly;
 168         int                     pages_per_rd_bio;
 169
 170         int                     is_dev_replace;
 171
 172         struct scrub_bio        *wr_curr_bio;
 173         struct mutex            wr_lock;
 174         int                     pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 175         struct btrfs_device     *wr_tgtdev;
 176         bool                    flush_all_writes;
 177
 178         /*
 179          * statistics
 180          */
 181         struct btrfs_scrub_progress stat;
 182         spinlock_t              stat_lock;
 183
 184         /*
 185          * Use a ref counter to avoid use-after-free issues. Scrub workers
 186          * decrement bios_in_flight and workers_pending and then do a wakeup
 187          * on the list_wait wait queue. We must ensure the main scrub task
 188          * doesn't free the scrub context before or while the workers are
 189          * doing the wakeup() call.
 190          */
 191         refcount_t              refs;
 192 };
 193
 194 struct scrub_warning {
 195         struct btrfs_path       *path;
 196         u64                     extent_item_size;
 197         const char              *errstr;
 198         u64                     physical;
 199         u64                     logical;
 200         struct btrfs_device     *dev;
 201 };
 202
 203 struct full_stripe_lock {
 204         struct rb_node node;
 205         u64 logical;
 206         u64 refs;
 207         struct mutex mutex;
 208 };
 209
 210 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 211 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 212 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 213 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 214                                      struct scrub_block *sblocks_for_recheck);
 215 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 216                                 struct scrub_block *sblock,
 217                                 int retry_failed_mirror);
 218 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 219 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 220                                              struct scrub_block *sblock_good);
 221 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 222                                             struct scrub_block *sblock_good,
 223                                             int page_num, int force_write);
 224 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 225 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 226                                            int page_num);
 227 static int scrub_checksum_data(struct scrub_block *sblock);
 228 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 229 static int scrub_checksum_super(struct scrub_block *sblock);
 230 static void scrub_block_get(struct scrub_block *sblock);
 231 static void scrub_block_put(struct scrub_block *sblock);
 232 static void scrub_page_get(struct scrub_page *spage);
 233 static void scrub_page_put(struct scrub_page *spage);
 234 static void scrub_parity_get(struct scrub_parity *sparity);
 235 static void scrub_parity_put(struct scrub_parity *sparity);
 236 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 237                                     struct scrub_page *spage);
 238 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 239                        u64 physical, struct btrfs_device *dev, u64 flags,
 240                        u64 gen, int mirror_num, u8 *csum, int force,
 241                        u64 physical_for_dev_replace);
 242 static void scrub_bio_end_io(struct bio *bio);
 243 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 244 static void scrub_block_complete(struct scrub_block *sblock);
 245 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 246                                u64 extent_logical, u64 extent_len,
 247                                u64 *extent_physical,
 248                                struct btrfs_device **extent_dev,
 249                                int *extent_mirror_num);
 250 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 251                                     struct scrub_page *spage);
 252 static void scrub_wr_submit(struct scrub_ctx *sctx);
 253 static void scrub_wr_bio_end_io(struct bio *bio);
 254 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 255 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 256 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 257 static void scrub_put_ctx(struct scrub_ctx *sctx);
 258
 259 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
 260 {
 261         return page->recover &&
 262                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
 263 }
 264
 265 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 266 {
 267         refcount_inc(&sctx->refs);
 268         atomic_inc(&sctx->bios_in_flight);
 269 }
 270
 271 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 272 {
 273         atomic_dec(&sctx->bios_in_flight);
 274         wake_up(&sctx->list_wait);
 275         scrub_put_ctx(sctx);
 276 }
 277
 278 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 279 {
 280         while (atomic_read(&fs_info->scrub_pause_req)) {
 281                 mutex_unlock(&fs_info->scrub_lock);
 282                 wait_event(fs_info->scrub_pause_wait,
 283                    atomic_read(&fs_info->scrub_pause_req) == 0);
 284                 mutex_lock(&fs_info->scrub_lock);
 285         }
 286 }
 287
 288 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 289 {
 290         atomic_inc(&fs_info->scrubs_paused);
 291         wake_up(&fs_info->scrub_pause_wait);
 292 }
 293
 294 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 295 {
 296         mutex_lock(&fs_info->scrub_lock);
 297         __scrub_blocked_if_needed(fs_info);
 298         atomic_dec(&fs_info->scrubs_paused);
 299         mutex_unlock(&fs_info->scrub_lock);
 300
 301         wake_up(&fs_info->scrub_pause_wait);
 302 }
 303
 304 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 305 {
 306         scrub_pause_on(fs_info);
 307         scrub_pause_off(fs_info);
 308 }
 309
 310 /*
 311  * Insert new full stripe lock into full stripe locks tree
 312  *
 313  * Return pointer to existing or newly inserted full_stripe_lock structure if
 314  * everything works well.
 315  * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
 316  *
 317  * NOTE: caller must hold full_stripe_locks_root->lock before calling this
 318  * function
 319  */
 320 static struct full_stripe_lock *insert_full_stripe_lock(
 321                 struct btrfs_full_stripe_locks_tree *locks_root,
 322                 u64 fstripe_logical)
 323 {
 324         struct rb_node **p;
 325         struct rb_node *parent = NULL;
 326         struct full_stripe_lock *entry;
 327         struct full_stripe_lock *ret;
 328
 329         lockdep_assert_held(&locks_root->lock);
 330
 331         p = &locks_root->root.rb_node;
 332         while (*p) {
 333                 parent = *p;
 334                 entry = rb_entry(parent, struct full_stripe_lock, node);
 335                 if (fstripe_logical < entry->logical) {
 336                         p = &(*p)->rb_left;
 337                 } else if (fstripe_logical > entry->logical) {
 338                         p = &(*p)->rb_right;
 339                 } else {
 340                         entry->refs++;
 341                         return entry;
 342                 }
 343         }
 344
 345         /*
 346          * Insert new lock.
 347          */
 348         ret = kmalloc(sizeof(*ret), GFP_KERNEL);
 349         if (!ret)
 350                 return ERR_PTR(-ENOMEM);
 351         ret->logical = fstripe_logical;
 352         ret->refs = 1;
 353         mutex_init(&ret->mutex);
 354
 355         rb_link_node(&ret->node, parent, p);
 356         rb_insert_color(&ret->node, &locks_root->root);
 357         return ret;
 358 }
 359
 360 /*
 361  * Search for a full stripe lock of a block group
 362  *
 363  * Return pointer to existing full stripe lock if found
 364  * Return NULL if not found
 365  */
 366 static struct full_stripe_lock *search_full_stripe_lock(
 367                 struct btrfs_full_stripe_locks_tree *locks_root,
 368                 u64 fstripe_logical)
 369 {
 370         struct rb_node *node;
 371         struct full_stripe_lock *entry;
 372
 373         lockdep_assert_held(&locks_root->lock);
 374
 375         node = locks_root->root.rb_node;
 376         while (node) {
 377                 entry = rb_entry(node, struct full_stripe_lock, node);
 378                 if (fstripe_logical < entry->logical)
 379                         node = node->rb_left;
 380                 else if (fstripe_logical > entry->logical)
 381                         node = node->rb_right;
 382                 else
 383                         return entry;
 384         }
 385         return NULL;
 386 }
 387
 388 /*
 389  * Helper to get full stripe logical from a normal bytenr.
 390  *
 391  * Caller must ensure @cache is a RAID56 block group.
 392  */
 393 static u64 get_full_stripe_logical(struct btrfs_block_group *cache, 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->start, cache->full_stripe_len) *
 408                         cache->full_stripe_len + cache->start;
 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 *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 *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 key;
 651
 652         local_root = btrfs_get_fs_root(fs_info, root, true);
 653         if (IS_ERR(local_root)) {
 654                 ret = PTR_ERR(local_root);
 655                 goto err;
 656         }
 657
 658         /*
 659          * this makes the path point to (inum INODE_ITEM ioff)
 660          */
 661         key.objectid = inum;
 662         key.type = BTRFS_INODE_ITEM_KEY;
 663         key.offset = 0;
 664
 665         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 666         if (ret) {
 667                 btrfs_put_root(local_root);
 668                 btrfs_release_path(swarn->path);
 669                 goto err;
 670         }
 671
 672         eb = swarn->path->nodes[0];
 673         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 674                                         struct btrfs_inode_item);
 675         isize = btrfs_inode_size(eb, inode_item);
 676         nlink = btrfs_inode_nlink(eb, inode_item);
 677         btrfs_release_path(swarn->path);
 678
 679         /*
 680          * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
 681          * uses GFP_NOFS in this context, so we keep it consistent but it does
 682          * not seem to be strictly necessary.
 683          */
 684         nofs_flag = memalloc_nofs_save();
 685         ipath = init_ipath(4096, local_root, swarn->path);
 686         memalloc_nofs_restore(nofs_flag);
 687         if (IS_ERR(ipath)) {
 688                 btrfs_put_root(local_root);
 689                 ret = PTR_ERR(ipath);
 690                 ipath = NULL;
 691                 goto err;
 692         }
 693         ret = paths_from_inode(inum, ipath);
 694
 695         if (ret < 0)
 696                 goto err;
 697
 698         /*
 699          * we deliberately ignore the bit ipath might have been too small to
 700          * hold all of the paths here
 701          */
 702         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 703                 btrfs_warn_in_rcu(fs_info,
 704 "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu, length %llu, links %u (path: %s)",
 705                                   swarn->errstr, swarn->logical,
 706                                   rcu_str_deref(swarn->dev->name),
 707                                   swarn->physical,
 708                                   root, inum, offset,
 709                                   min(isize - offset, (u64)PAGE_SIZE), nlink,
 710                                   (char *)(unsigned long)ipath->fspath->val[i]);
 711
 712         btrfs_put_root(local_root);
 713         free_ipath(ipath);
 714         return 0;
 715
 716 err:
 717         btrfs_warn_in_rcu(fs_info,
 718                           "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu: path resolving failed with ret=%d",
 719                           swarn->errstr, swarn->logical,
 720                           rcu_str_deref(swarn->dev->name),
 721                           swarn->physical,
 722                           root, inum, offset, ret);
 723
 724         free_ipath(ipath);
 725         return 0;
 726 }
 727
 728 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 729 {
 730         struct btrfs_device *dev;
 731         struct btrfs_fs_info *fs_info;
 732         struct btrfs_path *path;
 733         struct btrfs_key found_key;
 734         struct extent_buffer *eb;
 735         struct btrfs_extent_item *ei;
 736         struct scrub_warning swarn;
 737         unsigned long ptr = 0;
 738         u64 extent_item_pos;
 739         u64 flags = 0;
 740         u64 ref_root;
 741         u32 item_size;
 742         u8 ref_level = 0;
 743         int ret;
 744
 745         WARN_ON(sblock->page_count < 1);
 746         dev = sblock->pagev[0]->dev;
 747         fs_info = sblock->sctx->fs_info;
 748
 749         path = btrfs_alloc_path();
 750         if (!path)
 751                 return;
 752
 753         swarn.physical = sblock->pagev[0]->physical;
 754         swarn.logical = sblock->pagev[0]->logical;
 755         swarn.errstr = errstr;
 756         swarn.dev = NULL;
 757
 758         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 759                                   &flags);
 760         if (ret < 0)
 761                 goto out;
 762
 763         extent_item_pos = swarn.logical - found_key.objectid;
 764         swarn.extent_item_size = found_key.offset;
 765
 766         eb = path->nodes[0];
 767         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 768         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 769
 770         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 771                 do {
 772                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 773                                                       item_size, &ref_root,
 774                                                       &ref_level);
 775                         btrfs_warn_in_rcu(fs_info,
 776 "%s at logical %llu on dev %s, physical %llu: metadata %s (level %d) in tree %llu",
 777                                 errstr, swarn.logical,
 778                                 rcu_str_deref(dev->name),
 779                                 swarn.physical,
 780                                 ref_level ? "node" : "leaf",
 781                                 ret < 0 ? -1 : ref_level,
 782                                 ret < 0 ? -1 : ref_root);
 783                 } while (ret != 1);
 784                 btrfs_release_path(path);
 785         } else {
 786                 btrfs_release_path(path);
 787                 swarn.path = path;
 788                 swarn.dev = dev;
 789                 iterate_extent_inodes(fs_info, found_key.objectid,
 790                                         extent_item_pos, 1,
 791                                         scrub_print_warning_inode, &swarn, false);
 792         }
 793
 794 out:
 795         btrfs_free_path(path);
 796 }
 797
 798 static inline void scrub_get_recover(struct scrub_recover *recover)
 799 {
 800         refcount_inc(&recover->refs);
 801 }
 802
 803 static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
 804                                      struct scrub_recover *recover)
 805 {
 806         if (refcount_dec_and_test(&recover->refs)) {
 807                 btrfs_bio_counter_dec(fs_info);
 808                 btrfs_put_bbio(recover->bbio);
 809                 kfree(recover);
 810         }
 811 }
 812
 813 /*
 814  * scrub_handle_errored_block gets called when either verification of the
 815  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 816  * case, this function handles all pages in the bio, even though only one
 817  * may be bad.
 818  * The goal of this function is to repair the errored block by using the
 819  * contents of one of the mirrors.
 820  */
 821 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 822 {
 823         struct scrub_ctx *sctx = sblock_to_check->sctx;
 824         struct btrfs_device *dev;
 825         struct btrfs_fs_info *fs_info;
 826         u64 logical;
 827         unsigned int failed_mirror_index;
 828         unsigned int is_metadata;
 829         unsigned int have_csum;
 830         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 831         struct scrub_block *sblock_bad;
 832         int ret;
 833         int mirror_index;
 834         int page_num;
 835         int success;
 836         bool full_stripe_locked;
 837         unsigned int nofs_flag;
 838         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 839                                       DEFAULT_RATELIMIT_BURST);
 840
 841         BUG_ON(sblock_to_check->page_count < 1);
 842         fs_info = sctx->fs_info;
 843         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 844                 /*
 845                  * if we find an error in a super block, we just report it.
 846                  * They will get written with the next transaction commit
 847                  * anyway
 848                  */
 849                 spin_lock(&sctx->stat_lock);
 850                 ++sctx->stat.super_errors;
 851                 spin_unlock(&sctx->stat_lock);
 852                 return 0;
 853         }
 854         logical = sblock_to_check->pagev[0]->logical;
 855         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 856         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 857         is_metadata = !(sblock_to_check->pagev[0]->flags &
 858                         BTRFS_EXTENT_FLAG_DATA);
 859         have_csum = sblock_to_check->pagev[0]->have_csum;
 860         dev = sblock_to_check->pagev[0]->dev;
 861
 862         /*
 863          * We must use GFP_NOFS because the scrub task might be waiting for a
 864          * worker task executing this function and in turn a transaction commit
 865          * might be waiting the scrub task to pause (which needs to wait for all
 866          * the worker tasks to complete before pausing).
 867          * We do allocations in the workers through insert_full_stripe_lock()
 868          * and scrub_add_page_to_wr_bio(), which happens down the call chain of
 869          * this function.
 870          */
 871         nofs_flag = memalloc_nofs_save();
 872         /*
 873          * For RAID5/6, race can happen for a different device scrub thread.
 874          * For data corruption, Parity and Data threads will both try
 875          * to recovery the data.
 876          * Race can lead to doubly added csum error, or even unrecoverable
 877          * error.
 878          */
 879         ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
 880         if (ret < 0) {
 881                 memalloc_nofs_restore(nofs_flag);
 882                 spin_lock(&sctx->stat_lock);
 883                 if (ret == -ENOMEM)
 884                         sctx->stat.malloc_errors++;
 885                 sctx->stat.read_errors++;
 886                 sctx->stat.uncorrectable_errors++;
 887                 spin_unlock(&sctx->stat_lock);
 888                 return ret;
 889         }
 890
 891         /*
 892          * read all mirrors one after the other. This includes to
 893          * re-read the extent or metadata block that failed (that was
 894          * the cause that this fixup code is called) another time,
 895          * page by page this time in order to know which pages
 896          * caused I/O errors and which ones are good (for all mirrors).
 897          * It is the goal to handle the situation when more than one
 898          * mirror contains I/O errors, but the errors do not
 899          * overlap, i.e. the data can be repaired by selecting the
 900          * pages from those mirrors without I/O error on the
 901          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 902          * would be that mirror #1 has an I/O error on the first page,
 903          * the second page is good, and mirror #2 has an I/O error on
 904          * the second page, but the first page is good.
 905          * Then the first page of the first mirror can be repaired by
 906          * taking the first page of the second mirror, and the
 907          * second page of the second mirror can be repaired by
 908          * copying the contents of the 2nd page of the 1st mirror.
 909          * One more note: if the pages of one mirror contain I/O
 910          * errors, the checksum cannot be verified. In order to get
 911          * the best data for repairing, the first attempt is to find
 912          * a mirror without I/O errors and with a validated checksum.
 913          * Only if this is not possible, the pages are picked from
 914          * mirrors with I/O errors without considering the checksum.
 915          * If the latter is the case, at the end, the checksum of the
 916          * repaired area is verified in order to correctly maintain
 917          * the statistics.
 918          */
 919
 920         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
 921                                       sizeof(*sblocks_for_recheck), GFP_KERNEL);
 922         if (!sblocks_for_recheck) {
 923                 spin_lock(&sctx->stat_lock);
 924                 sctx->stat.malloc_errors++;
 925                 sctx->stat.read_errors++;
 926                 sctx->stat.uncorrectable_errors++;
 927                 spin_unlock(&sctx->stat_lock);
 928                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 929                 goto out;
 930         }
 931
 932         /* setup the context, map the logical blocks and alloc the pages */
 933         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
 934         if (ret) {
 935                 spin_lock(&sctx->stat_lock);
 936                 sctx->stat.read_errors++;
 937                 sctx->stat.uncorrectable_errors++;
 938                 spin_unlock(&sctx->stat_lock);
 939                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 940                 goto out;
 941         }
 942         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 943         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 944
 945         /* build and submit the bios for the failed mirror, check checksums */
 946         scrub_recheck_block(fs_info, sblock_bad, 1);
 947
 948         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 949             sblock_bad->no_io_error_seen) {
 950                 /*
 951                  * the error disappeared after reading page by page, or
 952                  * the area was part of a huge bio and other parts of the
 953                  * bio caused I/O errors, or the block layer merged several
 954                  * read requests into one and the error is caused by a
 955                  * different bio (usually one of the two latter cases is
 956                  * the cause)
 957                  */
 958                 spin_lock(&sctx->stat_lock);
 959                 sctx->stat.unverified_errors++;
 960                 sblock_to_check->data_corrected = 1;
 961                 spin_unlock(&sctx->stat_lock);
 962
 963                 if (sctx->is_dev_replace)
 964                         scrub_write_block_to_dev_replace(sblock_bad);
 965                 goto out;
 966         }
 967
 968         if (!sblock_bad->no_io_error_seen) {
 969                 spin_lock(&sctx->stat_lock);
 970                 sctx->stat.read_errors++;
 971                 spin_unlock(&sctx->stat_lock);
 972                 if (__ratelimit(&_rs))
 973                         scrub_print_warning("i/o error", sblock_to_check);
 974                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 975         } else if (sblock_bad->checksum_error) {
 976                 spin_lock(&sctx->stat_lock);
 977                 sctx->stat.csum_errors++;
 978                 spin_unlock(&sctx->stat_lock);
 979                 if (__ratelimit(&_rs))
 980                         scrub_print_warning("checksum error", sblock_to_check);
 981                 btrfs_dev_stat_inc_and_print(dev,
 982                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
 983         } else if (sblock_bad->header_error) {
 984                 spin_lock(&sctx->stat_lock);
 985                 sctx->stat.verify_errors++;
 986                 spin_unlock(&sctx->stat_lock);
 987                 if (__ratelimit(&_rs))
 988                         scrub_print_warning("checksum/header error",
 989                                             sblock_to_check);
 990                 if (sblock_bad->generation_error)
 991                         btrfs_dev_stat_inc_and_print(dev,
 992                                 BTRFS_DEV_STAT_GENERATION_ERRS);
 993                 else
 994                         btrfs_dev_stat_inc_and_print(dev,
 995                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
 996         }
 997
 998         if (sctx->readonly) {
 999                 ASSERT(!sctx->is_dev_replace);
1000                 goto out;
1001         }
1002
1003         /*
1004          * now build and submit the bios for the other mirrors, check
1005          * checksums.
1006          * First try to pick the mirror which is completely without I/O
1007          * errors and also does not have a checksum error.
1008          * If one is found, and if a checksum is present, the full block
1009          * that is known to contain an error is rewritten. Afterwards
1010          * the block is known to be corrected.
1011          * If a mirror is found which is completely correct, and no
1012          * checksum is present, only those pages are rewritten that had
1013          * an I/O error in the block to be repaired, since it cannot be
1014          * determined, which copy of the other pages is better (and it
1015          * could happen otherwise that a correct page would be
1016          * overwritten by a bad one).
1017          */
1018         for (mirror_index = 0; ;mirror_index++) {
1019                 struct scrub_block *sblock_other;
1020
1021                 if (mirror_index == failed_mirror_index)
1022                         continue;
1023
1024                 /* raid56's mirror can be more than BTRFS_MAX_MIRRORS */
1025                 if (!scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1026                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1027                                 break;
1028                         if (!sblocks_for_recheck[mirror_index].page_count)
1029                                 break;
1030
1031                         sblock_other = sblocks_for_recheck + mirror_index;
1032                 } else {
1033                         struct scrub_recover *r = sblock_bad->pagev[0]->recover;
1034                         int max_allowed = r->bbio->num_stripes -
1035                                                 r->bbio->num_tgtdevs;
1036
1037                         if (mirror_index >= max_allowed)
1038                                 break;
1039                         if (!sblocks_for_recheck[1].page_count)
1040                                 break;
1041
1042                         ASSERT(failed_mirror_index == 0);
1043                         sblock_other = sblocks_for_recheck + 1;
1044                         sblock_other->pagev[0]->mirror_num = 1 + mirror_index;
1045                 }
1046
1047                 /* build and submit the bios, check checksums */
1048                 scrub_recheck_block(fs_info, sblock_other, 0);
1049
1050                 if (!sblock_other->header_error &&
1051                     !sblock_other->checksum_error &&
1052                     sblock_other->no_io_error_seen) {
1053                         if (sctx->is_dev_replace) {
1054                                 scrub_write_block_to_dev_replace(sblock_other);
1055                                 goto corrected_error;
1056                         } else {
1057                                 ret = scrub_repair_block_from_good_copy(
1058                                                 sblock_bad, sblock_other);
1059                                 if (!ret)
1060                                         goto corrected_error;
1061                         }
1062                 }
1063         }
1064
1065         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1066                 goto did_not_correct_error;
1067
1068         /*
1069          * In case of I/O errors in the area that is supposed to be
1070          * repaired, continue by picking good copies of those pages.
1071          * Select the good pages from mirrors to rewrite bad pages from
1072          * the area to fix. Afterwards verify the checksum of the block
1073          * that is supposed to be repaired. This verification step is
1074          * only done for the purpose of statistic counting and for the
1075          * final scrub report, whether errors remain.
1076          * A perfect algorithm could make use of the checksum and try
1077          * all possible combinations of pages from the different mirrors
1078          * until the checksum verification succeeds. For example, when
1079          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1080          * of mirror #2 is readable but the final checksum test fails,
1081          * then the 2nd page of mirror #3 could be tried, whether now
1082          * the final checksum succeeds. But this would be a rare
1083          * exception and is therefore not implemented. At least it is
1084          * avoided that the good copy is overwritten.
1085          * A more useful improvement would be to pick the sectors
1086          * without I/O error based on sector sizes (512 bytes on legacy
1087          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1088          * mirror could be repaired by taking 512 byte of a different
1089          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1090          * area are unreadable.
1091          */
1092         success = 1;
1093         for (page_num = 0; page_num < sblock_bad->page_count;
1094              page_num++) {
1095                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1096                 struct scrub_block *sblock_other = NULL;
1097
1098                 /* skip no-io-error page in scrub */
1099                 if (!page_bad->io_error && !sctx->is_dev_replace)
1100                         continue;
1101
1102                 if (scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1103                         /*
1104                          * In case of dev replace, if raid56 rebuild process
1105                          * didn't work out correct data, then copy the content
1106                          * in sblock_bad to make sure target device is identical
1107                          * to source device, instead of writing garbage data in
1108                          * sblock_for_recheck array to target device.
1109                          */
1110                         sblock_other = NULL;
1111                 } else if (page_bad->io_error) {
1112                         /* try to find no-io-error page in mirrors */
1113                         for (mirror_index = 0;
1114                              mirror_index < BTRFS_MAX_MIRRORS &&
1115                              sblocks_for_recheck[mirror_index].page_count > 0;
1116                              mirror_index++) {
1117                                 if (!sblocks_for_recheck[mirror_index].
1118                                     pagev[page_num]->io_error) {
1119                                         sblock_other = sblocks_for_recheck +
1120                                                        mirror_index;
1121                                         break;
1122                                 }
1123                         }
1124                         if (!sblock_other)
1125                                 success = 0;
1126                 }
1127
1128                 if (sctx->is_dev_replace) {
1129                         /*
1130                          * did not find a mirror to fetch the page
1131                          * from. scrub_write_page_to_dev_replace()
1132                          * handles this case (page->io_error), by
1133                          * filling the block with zeros before
1134                          * submitting the write request
1135                          */
1136                         if (!sblock_other)
1137                                 sblock_other = sblock_bad;
1138
1139                         if (scrub_write_page_to_dev_replace(sblock_other,
1140                                                             page_num) != 0) {
1141                                 atomic64_inc(
1142                                         &fs_info->dev_replace.num_write_errors);
1143                                 success = 0;
1144                         }
1145                 } else if (sblock_other) {
1146                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1147                                                                sblock_other,
1148                                                                page_num, 0);
1149                         if (0 == ret)
1150                                 page_bad->io_error = 0;
1151                         else
1152                                 success = 0;
1153                 }
1154         }
1155
1156         if (success && !sctx->is_dev_replace) {
1157                 if (is_metadata || have_csum) {
1158                         /*
1159                          * need to verify the checksum now that all
1160                          * sectors on disk are repaired (the write
1161                          * request for data to be repaired is on its way).
1162                          * Just be lazy and use scrub_recheck_block()
1163                          * which re-reads the data before the checksum
1164                          * is verified, but most likely the data comes out
1165                          * of the page cache.
1166                          */
1167                         scrub_recheck_block(fs_info, sblock_bad, 1);
1168                         if (!sblock_bad->header_error &&
1169                             !sblock_bad->checksum_error &&
1170                             sblock_bad->no_io_error_seen)
1171                                 goto corrected_error;
1172                         else
1173                                 goto did_not_correct_error;
1174                 } else {
1175 corrected_error:
1176                         spin_lock(&sctx->stat_lock);
1177                         sctx->stat.corrected_errors++;
1178                         sblock_to_check->data_corrected = 1;
1179                         spin_unlock(&sctx->stat_lock);
1180                         btrfs_err_rl_in_rcu(fs_info,
1181                                 "fixed up error at logical %llu on dev %s",
1182                                 logical, rcu_str_deref(dev->name));
1183                 }
1184         } else {
1185 did_not_correct_error:
1186                 spin_lock(&sctx->stat_lock);
1187                 sctx->stat.uncorrectable_errors++;
1188                 spin_unlock(&sctx->stat_lock);
1189                 btrfs_err_rl_in_rcu(fs_info,
1190                         "unable to fixup (regular) error at logical %llu on dev %s",
1191                         logical, rcu_str_deref(dev->name));
1192         }
1193
1194 out:
1195         if (sblocks_for_recheck) {
1196                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1197                      mirror_index++) {
1198                         struct scrub_block *sblock = sblocks_for_recheck +
1199                                                      mirror_index;
1200                         struct scrub_recover *recover;
1201                         int page_index;
1202
1203                         for (page_index = 0; page_index < sblock->page_count;
1204                              page_index++) {
1205                                 sblock->pagev[page_index]->sblock = NULL;
1206                                 recover = sblock->pagev[page_index]->recover;
1207                                 if (recover) {
1208                                         scrub_put_recover(fs_info, recover);
1209                                         sblock->pagev[page_index]->recover =
1210                                                                         NULL;
1211                                 }
1212                                 scrub_page_put(sblock->pagev[page_index]);
1213                         }
1214                 }
1215                 kfree(sblocks_for_recheck);
1216         }
1217
1218         ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
1219         memalloc_nofs_restore(nofs_flag);
1220         if (ret < 0)
1221                 return ret;
1222         return 0;
1223 }
1224
1225 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1226 {
1227         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1228                 return 2;
1229         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1230                 return 3;
1231         else
1232                 return (int)bbio->num_stripes;
1233 }
1234
1235 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1236                                                  u64 *raid_map,
1237                                                  u64 mapped_length,
1238                                                  int nstripes, int mirror,
1239                                                  int *stripe_index,
1240                                                  u64 *stripe_offset)
1241 {
1242         int i;
1243
1244         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1245                 /* RAID5/6 */
1246                 for (i = 0; i < nstripes; i++) {
1247                         if (raid_map[i] == RAID6_Q_STRIPE ||
1248                             raid_map[i] == RAID5_P_STRIPE)
1249                                 continue;
1250
1251                         if (logical >= raid_map[i] &&
1252                             logical < raid_map[i] + mapped_length)
1253                                 break;
1254                 }
1255
1256                 *stripe_index = i;
1257                 *stripe_offset = logical - raid_map[i];
1258         } else {
1259                 /* The other RAID type */
1260                 *stripe_index = mirror;
1261                 *stripe_offset = 0;
1262         }
1263 }
1264
1265 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1266                                      struct scrub_block *sblocks_for_recheck)
1267 {
1268         struct scrub_ctx *sctx = original_sblock->sctx;
1269         struct btrfs_fs_info *fs_info = sctx->fs_info;
1270         u64 length = original_sblock->page_count * PAGE_SIZE;
1271         u64 logical = original_sblock->pagev[0]->logical;
1272         u64 generation = original_sblock->pagev[0]->generation;
1273         u64 flags = original_sblock->pagev[0]->flags;
1274         u64 have_csum = original_sblock->pagev[0]->have_csum;
1275         struct scrub_recover *recover;
1276         struct btrfs_bio *bbio;
1277         u64 sublen;
1278         u64 mapped_length;
1279         u64 stripe_offset;
1280         int stripe_index;
1281         int page_index = 0;
1282         int mirror_index;
1283         int nmirrors;
1284         int ret;
1285
1286         /*
1287          * note: the two members refs and outstanding_pages
1288          * are not used (and not set) in the blocks that are used for
1289          * the recheck procedure
1290          */
1291
1292         while (length > 0) {
1293                 sublen = min_t(u64, length, PAGE_SIZE);
1294                 mapped_length = sublen;
1295                 bbio = NULL;
1296
1297                 /*
1298                  * with a length of PAGE_SIZE, each returned stripe
1299                  * represents one mirror
1300                  */
1301                 btrfs_bio_counter_inc_blocked(fs_info);
1302                 ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
1303                                 logical, &mapped_length, &bbio);
1304                 if (ret || !bbio || mapped_length < sublen) {
1305                         btrfs_put_bbio(bbio);
1306                         btrfs_bio_counter_dec(fs_info);
1307                         return -EIO;
1308                 }
1309
1310                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1311                 if (!recover) {
1312                         btrfs_put_bbio(bbio);
1313                         btrfs_bio_counter_dec(fs_info);
1314                         return -ENOMEM;
1315                 }
1316
1317                 refcount_set(&recover->refs, 1);
1318                 recover->bbio = bbio;
1319                 recover->map_length = mapped_length;
1320
1321                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1322
1323                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1324
1325                 for (mirror_index = 0; mirror_index < nmirrors;
1326                      mirror_index++) {
1327                         struct scrub_block *sblock;
1328                         struct scrub_page *page;
1329
1330                         sblock = sblocks_for_recheck + mirror_index;
1331                         sblock->sctx = sctx;
1332
1333                         page = kzalloc(sizeof(*page), GFP_NOFS);
1334                         if (!page) {
1335 leave_nomem:
1336                                 spin_lock(&sctx->stat_lock);
1337                                 sctx->stat.malloc_errors++;
1338                                 spin_unlock(&sctx->stat_lock);
1339                                 scrub_put_recover(fs_info, recover);
1340                                 return -ENOMEM;
1341                         }
1342                         scrub_page_get(page);
1343                         sblock->pagev[page_index] = page;
1344                         page->sblock = sblock;
1345                         page->flags = flags;
1346                         page->generation = generation;
1347                         page->logical = logical;
1348                         page->have_csum = have_csum;
1349                         if (have_csum)
1350                                 memcpy(page->csum,
1351                                        original_sblock->pagev[0]->csum,
1352                                        sctx->csum_size);
1353
1354                         scrub_stripe_index_and_offset(logical,
1355                                                       bbio->map_type,
1356                                                       bbio->raid_map,
1357                                                       mapped_length,
1358                                                       bbio->num_stripes -
1359                                                       bbio->num_tgtdevs,
1360                                                       mirror_index,
1361                                                       &stripe_index,
1362                                                       &stripe_offset);
1363                         page->physical = bbio->stripes[stripe_index].physical +
1364                                          stripe_offset;
1365                         page->dev = bbio->stripes[stripe_index].dev;
1366
1367                         BUG_ON(page_index >= original_sblock->page_count);
1368                         page->physical_for_dev_replace =
1369                                 original_sblock->pagev[page_index]->
1370                                 physical_for_dev_replace;
1371                         /* for missing devices, dev->bdev is NULL */
1372                         page->mirror_num = mirror_index + 1;
1373                         sblock->page_count++;
1374                         page->page = alloc_page(GFP_NOFS);
1375                         if (!page->page)
1376                                 goto leave_nomem;
1377
1378                         scrub_get_recover(recover);
1379                         page->recover = recover;
1380                 }
1381                 scrub_put_recover(fs_info, recover);
1382                 length -= sublen;
1383                 logical += sublen;
1384                 page_index++;
1385         }
1386
1387         return 0;
1388 }
1389
1390 static void scrub_bio_wait_endio(struct bio *bio)
1391 {
1392         complete(bio->bi_private);
1393 }
1394
1395 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1396                                         struct bio *bio,
1397                                         struct scrub_page *page)
1398 {
1399         DECLARE_COMPLETION_ONSTACK(done);
1400         int ret;
1401         int mirror_num;
1402
1403         bio->bi_iter.bi_sector = page->logical >> 9;
1404         bio->bi_private = &done;
1405         bio->bi_end_io = scrub_bio_wait_endio;
1406
1407         mirror_num = page->sblock->pagev[0]->mirror_num;
1408         ret = raid56_parity_recover(fs_info, bio, page->recover->bbio,
1409                                     page->recover->map_length,
1410                                     mirror_num, 0);
1411         if (ret)
1412                 return ret;
1413
1414         wait_for_completion_io(&done);
1415         return blk_status_to_errno(bio->bi_status);
1416 }
1417
1418 static void scrub_recheck_block_on_raid56(struct btrfs_fs_info *fs_info,
1419                                           struct scrub_block *sblock)
1420 {
1421         struct scrub_page *first_page = sblock->pagev[0];
1422         struct bio *bio;
1423         int page_num;
1424
1425         /* All pages in sblock belong to the same stripe on the same device. */
1426         ASSERT(first_page->dev);
1427         if (!first_page->dev->bdev)
1428                 goto out;
1429
1430         bio = btrfs_io_bio_alloc(BIO_MAX_PAGES);
1431         bio_set_dev(bio, first_page->dev->bdev);
1432
1433         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1434                 struct scrub_page *page = sblock->pagev[page_num];
1435
1436                 WARN_ON(!page->page);
1437                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1438         }
1439
1440         if (scrub_submit_raid56_bio_wait(fs_info, bio, first_page)) {
1441                 bio_put(bio);
1442                 goto out;
1443         }
1444
1445         bio_put(bio);
1446
1447         scrub_recheck_block_checksum(sblock);
1448
1449         return;
1450 out:
1451         for (page_num = 0; page_num < sblock->page_count; page_num++)
1452                 sblock->pagev[page_num]->io_error = 1;
1453
1454         sblock->no_io_error_seen = 0;
1455 }
1456
1457 /*
1458  * this function will check the on disk data for checksum errors, header
1459  * errors and read I/O errors. If any I/O errors happen, the exact pages
1460  * which are errored are marked as being bad. The goal is to enable scrub
1461  * to take those pages that are not errored from all the mirrors so that
1462  * the pages that are errored in the just handled mirror can be repaired.
1463  */
1464 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1465                                 struct scrub_block *sblock,
1466                                 int retry_failed_mirror)
1467 {
1468         int page_num;
1469
1470         sblock->no_io_error_seen = 1;
1471
1472         /* short cut for raid56 */
1473         if (!retry_failed_mirror && scrub_is_page_on_raid56(sblock->pagev[0]))
1474                 return scrub_recheck_block_on_raid56(fs_info, sblock);
1475
1476         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1477                 struct bio *bio;
1478                 struct scrub_page *page = sblock->pagev[page_num];
1479
1480                 if (page->dev->bdev == NULL) {
1481                         page->io_error = 1;
1482                         sblock->no_io_error_seen = 0;
1483                         continue;
1484                 }
1485
1486                 WARN_ON(!page->page);
1487                 bio = btrfs_io_bio_alloc(1);
1488                 bio_set_dev(bio, page->dev->bdev);
1489
1490                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1491                 bio->bi_iter.bi_sector = page->physical >> 9;
1492                 bio->bi_opf = REQ_OP_READ;
1493
1494                 if (btrfsic_submit_bio_wait(bio)) {
1495                         page->io_error = 1;
1496                         sblock->no_io_error_seen = 0;
1497                 }
1498
1499                 bio_put(bio);
1500         }
1501
1502         if (sblock->no_io_error_seen)
1503                 scrub_recheck_block_checksum(sblock);
1504 }
1505
1506 static inline int scrub_check_fsid(u8 fsid[],
1507                                    struct scrub_page *spage)
1508 {
1509         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1510         int ret;
1511
1512         ret = memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1513         return !ret;
1514 }
1515
1516 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1517 {
1518         sblock->header_error = 0;
1519         sblock->checksum_error = 0;
1520         sblock->generation_error = 0;
1521
1522         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1523                 scrub_checksum_data(sblock);
1524         else
1525                 scrub_checksum_tree_block(sblock);
1526 }
1527
1528 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1529                                              struct scrub_block *sblock_good)
1530 {
1531         int page_num;
1532         int ret = 0;
1533
1534         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1535                 int ret_sub;
1536
1537                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1538                                                            sblock_good,
1539                                                            page_num, 1);
1540                 if (ret_sub)
1541                         ret = ret_sub;
1542         }
1543
1544         return ret;
1545 }
1546
1547 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1548                                             struct scrub_block *sblock_good,
1549                                             int page_num, int force_write)
1550 {
1551         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1552         struct scrub_page *page_good = sblock_good->pagev[page_num];
1553         struct btrfs_fs_info *fs_info = sblock_bad->sctx->fs_info;
1554
1555         BUG_ON(page_bad->page == NULL);
1556         BUG_ON(page_good->page == NULL);
1557         if (force_write || sblock_bad->header_error ||
1558             sblock_bad->checksum_error || page_bad->io_error) {
1559                 struct bio *bio;
1560                 int ret;
1561
1562                 if (!page_bad->dev->bdev) {
1563                         btrfs_warn_rl(fs_info,
1564                                 "scrub_repair_page_from_good_copy(bdev == NULL) is unexpected");
1565                         return -EIO;
1566                 }
1567
1568                 bio = btrfs_io_bio_alloc(1);
1569                 bio_set_dev(bio, page_bad->dev->bdev);
1570                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1571                 bio->bi_opf = REQ_OP_WRITE;
1572
1573                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1574                 if (PAGE_SIZE != ret) {
1575                         bio_put(bio);
1576                         return -EIO;
1577                 }
1578
1579                 if (btrfsic_submit_bio_wait(bio)) {
1580                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1581                                 BTRFS_DEV_STAT_WRITE_ERRS);
1582                         atomic64_inc(&fs_info->dev_replace.num_write_errors);
1583                         bio_put(bio);
1584                         return -EIO;
1585                 }
1586                 bio_put(bio);
1587         }
1588
1589         return 0;
1590 }
1591
1592 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1593 {
1594         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
1595         int page_num;
1596
1597         /*
1598          * This block is used for the check of the parity on the source device,
1599          * so the data needn't be written into the destination device.
1600          */
1601         if (sblock->sparity)
1602                 return;
1603
1604         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1605                 int ret;
1606
1607                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1608                 if (ret)
1609                         atomic64_inc(&fs_info->dev_replace.num_write_errors);
1610         }
1611 }
1612
1613 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1614                                            int page_num)
1615 {
1616         struct scrub_page *spage = sblock->pagev[page_num];
1617
1618         BUG_ON(spage->page == NULL);
1619         if (spage->io_error)
1620                 clear_page(page_address(spage->page));
1621
1622         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1623 }
1624
1625 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1626                                     struct scrub_page *spage)
1627 {
1628         struct scrub_bio *sbio;
1629         int ret;
1630
1631         mutex_lock(&sctx->wr_lock);
1632 again:
1633         if (!sctx->wr_curr_bio) {
1634                 sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
1635                                               GFP_KERNEL);
1636                 if (!sctx->wr_curr_bio) {
1637                         mutex_unlock(&sctx->wr_lock);
1638                         return -ENOMEM;
1639                 }
1640                 sctx->wr_curr_bio->sctx = sctx;
1641                 sctx->wr_curr_bio->page_count = 0;
1642         }
1643         sbio = sctx->wr_curr_bio;
1644         if (sbio->page_count == 0) {
1645                 struct bio *bio;
1646
1647                 sbio->physical = spage->physical_for_dev_replace;
1648                 sbio->logical = spage->logical;
1649                 sbio->dev = sctx->wr_tgtdev;
1650                 bio = sbio->bio;
1651                 if (!bio) {
1652                         bio = btrfs_io_bio_alloc(sctx->pages_per_wr_bio);
1653                         sbio->bio = bio;
1654                 }
1655
1656                 bio->bi_private = sbio;
1657                 bio->bi_end_io = scrub_wr_bio_end_io;
1658                 bio_set_dev(bio, sbio->dev->bdev);
1659                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1660                 bio->bi_opf = REQ_OP_WRITE;
1661                 sbio->status = 0;
1662         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1663                    spage->physical_for_dev_replace ||
1664                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1665                    spage->logical) {
1666                 scrub_wr_submit(sctx);
1667                 goto again;
1668         }
1669
1670         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1671         if (ret != PAGE_SIZE) {
1672                 if (sbio->page_count < 1) {
1673                         bio_put(sbio->bio);
1674                         sbio->bio = NULL;
1675                         mutex_unlock(&sctx->wr_lock);
1676                         return -EIO;
1677                 }
1678                 scrub_wr_submit(sctx);
1679                 goto again;
1680         }
1681
1682         sbio->pagev[sbio->page_count] = spage;
1683         scrub_page_get(spage);
1684         sbio->page_count++;
1685         if (sbio->page_count == sctx->pages_per_wr_bio)
1686                 scrub_wr_submit(sctx);
1687         mutex_unlock(&sctx->wr_lock);
1688
1689         return 0;
1690 }
1691
1692 static void scrub_wr_submit(struct scrub_ctx *sctx)
1693 {
1694         struct scrub_bio *sbio;
1695
1696         if (!sctx->wr_curr_bio)
1697                 return;
1698
1699         sbio = sctx->wr_curr_bio;
1700         sctx->wr_curr_bio = NULL;
1701         WARN_ON(!sbio->bio->bi_disk);
1702         scrub_pending_bio_inc(sctx);
1703         /* process all writes in a single worker thread. Then the block layer
1704          * orders the requests before sending them to the driver which
1705          * doubled the write performance on spinning disks when measured
1706          * with Linux 3.5 */
1707         btrfsic_submit_bio(sbio->bio);
1708 }
1709
1710 static void scrub_wr_bio_end_io(struct bio *bio)
1711 {
1712         struct scrub_bio *sbio = bio->bi_private;
1713         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
1714
1715         sbio->status = bio->bi_status;
1716         sbio->bio = bio;
1717
1718         btrfs_init_work(&sbio->work, scrub_wr_bio_end_io_worker, NULL, NULL);
1719         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1720 }
1721
1722 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1723 {
1724         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1725         struct scrub_ctx *sctx = sbio->sctx;
1726         int i;
1727
1728         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1729         if (sbio->status) {
1730                 struct btrfs_dev_replace *dev_replace =
1731                         &sbio->sctx->fs_info->dev_replace;
1732
1733                 for (i = 0; i < sbio->page_count; i++) {
1734                         struct scrub_page *spage = sbio->pagev[i];
1735
1736                         spage->io_error = 1;
1737                         atomic64_inc(&dev_replace->num_write_errors);
1738                 }
1739         }
1740
1741         for (i = 0; i < sbio->page_count; i++)
1742                 scrub_page_put(sbio->pagev[i]);
1743
1744         bio_put(sbio->bio);
1745         kfree(sbio);
1746         scrub_pending_bio_dec(sctx);
1747 }
1748
1749 static int scrub_checksum(struct scrub_block *sblock)
1750 {
1751         u64 flags;
1752         int ret;
1753
1754         /*
1755          * No need to initialize these stats currently,
1756          * because this function only use return value
1757          * instead of these stats value.
1758          *
1759          * Todo:
1760          * always use stats
1761          */
1762         sblock->header_error = 0;
1763         sblock->generation_error = 0;
1764         sblock->checksum_error = 0;
1765
1766         WARN_ON(sblock->page_count < 1);
1767         flags = sblock->pagev[0]->flags;
1768         ret = 0;
1769         if (flags & BTRFS_EXTENT_FLAG_DATA)
1770                 ret = scrub_checksum_data(sblock);
1771         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1772                 ret = scrub_checksum_tree_block(sblock);
1773         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1774                 (void)scrub_checksum_super(sblock);
1775         else
1776                 WARN_ON(1);
1777         if (ret)
1778                 scrub_handle_errored_block(sblock);
1779
1780         return ret;
1781 }
1782
1783 static int scrub_checksum_data(struct scrub_block *sblock)
1784 {
1785         struct scrub_ctx *sctx = sblock->sctx;
1786         struct btrfs_fs_info *fs_info = sctx->fs_info;
1787         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1788         u8 csum[BTRFS_CSUM_SIZE];
1789         u8 *on_disk_csum;
1790         struct page *page;
1791         void *buffer;
1792         u64 len;
1793         int index;
1794
1795         BUG_ON(sblock->page_count < 1);
1796         if (!sblock->pagev[0]->have_csum)
1797                 return 0;
1798
1799         shash->tfm = fs_info->csum_shash;
1800         crypto_shash_init(shash);
1801
1802         on_disk_csum = sblock->pagev[0]->csum;
1803         page = sblock->pagev[0]->page;
1804         buffer = page_address(page);
1805
1806         len = sctx->fs_info->sectorsize;
1807         index = 0;
1808         for (;;) {
1809                 u64 l = min_t(u64, len, PAGE_SIZE);
1810
1811                 crypto_shash_update(shash, buffer, l);
1812                 len -= l;
1813                 if (len == 0)
1814                         break;
1815                 index++;
1816                 BUG_ON(index >= sblock->page_count);
1817                 BUG_ON(!sblock->pagev[index]->page);
1818                 page = sblock->pagev[index]->page;
1819                 buffer = page_address(page);
1820         }
1821
1822         crypto_shash_final(shash, csum);
1823         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1824                 sblock->checksum_error = 1;
1825
1826         return sblock->checksum_error;
1827 }
1828
1829 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1830 {
1831         struct scrub_ctx *sctx = sblock->sctx;
1832         struct btrfs_header *h;
1833         struct btrfs_fs_info *fs_info = sctx->fs_info;
1834         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1835         u8 calculated_csum[BTRFS_CSUM_SIZE];
1836         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1837         struct page *page;
1838         void *mapped_buffer;
1839         u64 mapped_size;
1840         void *p;
1841         u64 len;
1842         int index;
1843
1844         shash->tfm = fs_info->csum_shash;
1845         crypto_shash_init(shash);
1846
1847         BUG_ON(sblock->page_count < 1);
1848         page = sblock->pagev[0]->page;
1849         mapped_buffer = page_address(page);
1850         h = (struct btrfs_header *)mapped_buffer;
1851         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1852
1853         /*
1854          * we don't use the getter functions here, as we
1855          * a) don't have an extent buffer and
1856          * b) the page is already kmapped
1857          */
1858         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1859                 sblock->header_error = 1;
1860
1861         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
1862                 sblock->header_error = 1;
1863                 sblock->generation_error = 1;
1864         }
1865
1866         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
1867                 sblock->header_error = 1;
1868
1869         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1870                    BTRFS_UUID_SIZE))
1871                 sblock->header_error = 1;
1872
1873         len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
1874         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1875         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1876         index = 0;
1877         for (;;) {
1878                 u64 l = min_t(u64, len, mapped_size);
1879
1880                 crypto_shash_update(shash, p, l);
1881                 len -= l;
1882                 if (len == 0)
1883                         break;
1884                 index++;
1885                 BUG_ON(index >= sblock->page_count);
1886                 BUG_ON(!sblock->pagev[index]->page);
1887                 page = sblock->pagev[index]->page;
1888                 mapped_buffer = page_address(page);
1889                 mapped_size = PAGE_SIZE;
1890                 p = mapped_buffer;
1891         }
1892
1893         crypto_shash_final(shash, calculated_csum);
1894         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1895                 sblock->checksum_error = 1;
1896
1897         return sblock->header_error || sblock->checksum_error;
1898 }
1899
1900 static int scrub_checksum_super(struct scrub_block *sblock)
1901 {
1902         struct btrfs_super_block *s;
1903         struct scrub_ctx *sctx = sblock->sctx;
1904         struct btrfs_fs_info *fs_info = sctx->fs_info;
1905         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1906         u8 calculated_csum[BTRFS_CSUM_SIZE];
1907         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1908         struct page *page;
1909         void *mapped_buffer;
1910         u64 mapped_size;
1911         void *p;
1912         int fail_gen = 0;
1913         int fail_cor = 0;
1914         u64 len;
1915         int index;
1916
1917         shash->tfm = fs_info->csum_shash;
1918         crypto_shash_init(shash);
1919
1920         BUG_ON(sblock->page_count < 1);
1921         page = sblock->pagev[0]->page;
1922         mapped_buffer = page_address(page);
1923         s = (struct btrfs_super_block *)mapped_buffer;
1924         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1925
1926         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1927                 ++fail_cor;
1928
1929         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1930                 ++fail_gen;
1931
1932         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1933                 ++fail_cor;
1934
1935         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1936         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1937         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1938         index = 0;
1939         for (;;) {
1940                 u64 l = min_t(u64, len, mapped_size);
1941
1942                 crypto_shash_update(shash, p, l);
1943                 len -= l;
1944                 if (len == 0)
1945                         break;
1946                 index++;
1947                 BUG_ON(index >= sblock->page_count);
1948                 BUG_ON(!sblock->pagev[index]->page);
1949                 page = sblock->pagev[index]->page;
1950                 mapped_buffer = page_address(page);
1951                 mapped_size = PAGE_SIZE;
1952                 p = mapped_buffer;
1953         }
1954
1955         crypto_shash_final(shash, calculated_csum);
1956         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1957                 ++fail_cor;
1958
1959         if (fail_cor + fail_gen) {
1960                 /*
1961                  * if we find an error in a super block, we just report it.
1962                  * They will get written with the next transaction commit
1963                  * anyway
1964                  */
1965                 spin_lock(&sctx->stat_lock);
1966                 ++sctx->stat.super_errors;
1967                 spin_unlock(&sctx->stat_lock);
1968                 if (fail_cor)
1969                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1970                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1971                 else
1972                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1973                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1974         }
1975
1976         return fail_cor + fail_gen;
1977 }
1978
1979 static void scrub_block_get(struct scrub_block *sblock)
1980 {
1981         refcount_inc(&sblock->refs);
1982 }
1983
1984 static void scrub_block_put(struct scrub_block *sblock)
1985 {
1986         if (refcount_dec_and_test(&sblock->refs)) {
1987                 int i;
1988
1989                 if (sblock->sparity)
1990                         scrub_parity_put(sblock->sparity);
1991
1992                 for (i = 0; i < sblock->page_count; i++)
1993                         scrub_page_put(sblock->pagev[i]);
1994                 kfree(sblock);
1995         }
1996 }
1997
1998 static void scrub_page_get(struct scrub_page *spage)
1999 {
2000         atomic_inc(&spage->refs);
2001 }
2002
2003 static void scrub_page_put(struct scrub_page *spage)
2004 {
2005         if (atomic_dec_and_test(&spage->refs)) {
2006                 if (spage->page)
2007                         __free_page(spage->page);
2008                 kfree(spage);
2009         }
2010 }
2011
2012 static void scrub_submit(struct scrub_ctx *sctx)
2013 {
2014         struct scrub_bio *sbio;
2015
2016         if (sctx->curr == -1)
2017                 return;
2018
2019         sbio = sctx->bios[sctx->curr];
2020         sctx->curr = -1;
2021         scrub_pending_bio_inc(sctx);
2022         btrfsic_submit_bio(sbio->bio);
2023 }
2024
2025 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2026                                     struct scrub_page *spage)
2027 {
2028         struct scrub_block *sblock = spage->sblock;
2029         struct scrub_bio *sbio;
2030         int ret;
2031
2032 again:
2033         /*
2034          * grab a fresh bio or wait for one to become available
2035          */
2036         while (sctx->curr == -1) {
2037                 spin_lock(&sctx->list_lock);
2038                 sctx->curr = sctx->first_free;
2039                 if (sctx->curr != -1) {
2040                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2041                         sctx->bios[sctx->curr]->next_free = -1;
2042                         sctx->bios[sctx->curr]->page_count = 0;
2043                         spin_unlock(&sctx->list_lock);
2044                 } else {
2045                         spin_unlock(&sctx->list_lock);
2046                         wait_event(sctx->list_wait, sctx->first_free != -1);
2047                 }
2048         }
2049         sbio = sctx->bios[sctx->curr];
2050         if (sbio->page_count == 0) {
2051                 struct bio *bio;
2052
2053                 sbio->physical = spage->physical;
2054                 sbio->logical = spage->logical;
2055                 sbio->dev = spage->dev;
2056                 bio = sbio->bio;
2057                 if (!bio) {
2058                         bio = btrfs_io_bio_alloc(sctx->pages_per_rd_bio);
2059                         sbio->bio = bio;
2060                 }
2061
2062                 bio->bi_private = sbio;
2063                 bio->bi_end_io = scrub_bio_end_io;
2064                 bio_set_dev(bio, sbio->dev->bdev);
2065                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2066                 bio->bi_opf = REQ_OP_READ;
2067                 sbio->status = 0;
2068         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2069                    spage->physical ||
2070                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2071                    spage->logical ||
2072                    sbio->dev != spage->dev) {
2073                 scrub_submit(sctx);
2074                 goto again;
2075         }
2076
2077         sbio->pagev[sbio->page_count] = spage;
2078         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2079         if (ret != PAGE_SIZE) {
2080                 if (sbio->page_count < 1) {
2081                         bio_put(sbio->bio);
2082                         sbio->bio = NULL;
2083                         return -EIO;
2084                 }
2085                 scrub_submit(sctx);
2086                 goto again;
2087         }
2088
2089         scrub_block_get(sblock); /* one for the page added to the bio */
2090         atomic_inc(&sblock->outstanding_pages);
2091         sbio->page_count++;
2092         if (sbio->page_count == sctx->pages_per_rd_bio)
2093                 scrub_submit(sctx);
2094
2095         return 0;
2096 }
2097
2098 static void scrub_missing_raid56_end_io(struct bio *bio)
2099 {
2100         struct scrub_block *sblock = bio->bi_private;
2101         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
2102
2103         if (bio->bi_status)
2104                 sblock->no_io_error_seen = 0;
2105
2106         bio_put(bio);
2107
2108         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2109 }
2110
2111 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2112 {
2113         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2114         struct scrub_ctx *sctx = sblock->sctx;
2115         struct btrfs_fs_info *fs_info = sctx->fs_info;
2116         u64 logical;
2117         struct btrfs_device *dev;
2118
2119         logical = sblock->pagev[0]->logical;
2120         dev = sblock->pagev[0]->dev;
2121
2122         if (sblock->no_io_error_seen)
2123                 scrub_recheck_block_checksum(sblock);
2124
2125         if (!sblock->no_io_error_seen) {
2126                 spin_lock(&sctx->stat_lock);
2127                 sctx->stat.read_errors++;
2128                 spin_unlock(&sctx->stat_lock);
2129                 btrfs_err_rl_in_rcu(fs_info,
2130                         "IO error rebuilding logical %llu for dev %s",
2131                         logical, rcu_str_deref(dev->name));
2132         } else if (sblock->header_error || sblock->checksum_error) {
2133                 spin_lock(&sctx->stat_lock);
2134                 sctx->stat.uncorrectable_errors++;
2135                 spin_unlock(&sctx->stat_lock);
2136                 btrfs_err_rl_in_rcu(fs_info,
2137                         "failed to rebuild valid logical %llu for dev %s",
2138                         logical, rcu_str_deref(dev->name));
2139         } else {
2140                 scrub_write_block_to_dev_replace(sblock);
2141         }
2142
2143         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2144                 mutex_lock(&sctx->wr_lock);
2145                 scrub_wr_submit(sctx);
2146                 mutex_unlock(&sctx->wr_lock);
2147         }
2148
2149         scrub_block_put(sblock);
2150         scrub_pending_bio_dec(sctx);
2151 }
2152
2153 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2154 {
2155         struct scrub_ctx *sctx = sblock->sctx;
2156         struct btrfs_fs_info *fs_info = sctx->fs_info;
2157         u64 length = sblock->page_count * PAGE_SIZE;
2158         u64 logical = sblock->pagev[0]->logical;
2159         struct btrfs_bio *bbio = NULL;
2160         struct bio *bio;
2161         struct btrfs_raid_bio *rbio;
2162         int ret;
2163         int i;
2164
2165         btrfs_bio_counter_inc_blocked(fs_info);
2166         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
2167                         &length, &bbio);
2168         if (ret || !bbio || !bbio->raid_map)
2169                 goto bbio_out;
2170
2171         if (WARN_ON(!sctx->is_dev_replace ||
2172                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2173                 /*
2174                  * We shouldn't be scrubbing a missing device. Even for dev
2175                  * replace, we should only get here for RAID 5/6. We either
2176                  * managed to mount something with no mirrors remaining or
2177                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2178                  */
2179                 goto bbio_out;
2180         }
2181
2182         bio = btrfs_io_bio_alloc(0);
2183         bio->bi_iter.bi_sector = logical >> 9;
2184         bio->bi_private = sblock;
2185         bio->bi_end_io = scrub_missing_raid56_end_io;
2186
2187         rbio = raid56_alloc_missing_rbio(fs_info, bio, bbio, length);
2188         if (!rbio)
2189                 goto rbio_out;
2190
2191         for (i = 0; i < sblock->page_count; i++) {
2192                 struct scrub_page *spage = sblock->pagev[i];
2193
2194                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2195         }
2196
2197         btrfs_init_work(&sblock->work, scrub_missing_raid56_worker, NULL, NULL);
2198         scrub_block_get(sblock);
2199         scrub_pending_bio_inc(sctx);
2200         raid56_submit_missing_rbio(rbio);
2201         return;
2202
2203 rbio_out:
2204         bio_put(bio);
2205 bbio_out:
2206         btrfs_bio_counter_dec(fs_info);
2207         btrfs_put_bbio(bbio);
2208         spin_lock(&sctx->stat_lock);
2209         sctx->stat.malloc_errors++;
2210         spin_unlock(&sctx->stat_lock);
2211 }
2212
2213 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2214                        u64 physical, struct btrfs_device *dev, u64 flags,
2215                        u64 gen, int mirror_num, u8 *csum, int force,
2216                        u64 physical_for_dev_replace)
2217 {
2218         struct scrub_block *sblock;
2219         int index;
2220
2221         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2222         if (!sblock) {
2223                 spin_lock(&sctx->stat_lock);
2224                 sctx->stat.malloc_errors++;
2225                 spin_unlock(&sctx->stat_lock);
2226                 return -ENOMEM;
2227         }
2228
2229         /* one ref inside this function, plus one for each page added to
2230          * a bio later on */
2231         refcount_set(&sblock->refs, 1);
2232         sblock->sctx = sctx;
2233         sblock->no_io_error_seen = 1;
2234
2235         for (index = 0; len > 0; index++) {
2236                 struct scrub_page *spage;
2237                 u64 l = min_t(u64, len, PAGE_SIZE);
2238
2239                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2240                 if (!spage) {
2241 leave_nomem:
2242                         spin_lock(&sctx->stat_lock);
2243                         sctx->stat.malloc_errors++;
2244                         spin_unlock(&sctx->stat_lock);
2245                         scrub_block_put(sblock);
2246                         return -ENOMEM;
2247                 }
2248                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2249                 scrub_page_get(spage);
2250                 sblock->pagev[index] = spage;
2251                 spage->sblock = sblock;
2252                 spage->dev = dev;
2253                 spage->flags = flags;
2254                 spage->generation = gen;
2255                 spage->logical = logical;
2256                 spage->physical = physical;
2257                 spage->physical_for_dev_replace = physical_for_dev_replace;
2258                 spage->mirror_num = mirror_num;
2259                 if (csum) {
2260                         spage->have_csum = 1;
2261                         memcpy(spage->csum, csum, sctx->csum_size);
2262                 } else {
2263                         spage->have_csum = 0;
2264                 }
2265                 sblock->page_count++;
2266                 spage->page = alloc_page(GFP_KERNEL);
2267                 if (!spage->page)
2268                         goto leave_nomem;
2269                 len -= l;
2270                 logical += l;
2271                 physical += l;
2272                 physical_for_dev_replace += l;
2273         }
2274
2275         WARN_ON(sblock->page_count == 0);
2276         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2277                 /*
2278                  * This case should only be hit for RAID 5/6 device replace. See
2279                  * the comment in scrub_missing_raid56_pages() for details.
2280                  */
2281                 scrub_missing_raid56_pages(sblock);
2282         } else {
2283                 for (index = 0; index < sblock->page_count; index++) {
2284                         struct scrub_page *spage = sblock->pagev[index];
2285                         int ret;
2286
2287                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2288                         if (ret) {
2289                                 scrub_block_put(sblock);
2290                                 return ret;
2291                         }
2292                 }
2293
2294                 if (force)
2295                         scrub_submit(sctx);
2296         }
2297
2298         /* last one frees, either here or in bio completion for last page */
2299         scrub_block_put(sblock);
2300         return 0;
2301 }
2302
2303 static void scrub_bio_end_io(struct bio *bio)
2304 {
2305         struct scrub_bio *sbio = bio->bi_private;
2306         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
2307
2308         sbio->status = bio->bi_status;
2309         sbio->bio = bio;
2310
2311         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2312 }
2313
2314 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2315 {
2316         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2317         struct scrub_ctx *sctx = sbio->sctx;
2318         int i;
2319
2320         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2321         if (sbio->status) {
2322                 for (i = 0; i < sbio->page_count; i++) {
2323                         struct scrub_page *spage = sbio->pagev[i];
2324
2325                         spage->io_error = 1;
2326                         spage->sblock->no_io_error_seen = 0;
2327                 }
2328         }
2329
2330         /* now complete the scrub_block items that have all pages completed */
2331         for (i = 0; i < sbio->page_count; i++) {
2332                 struct scrub_page *spage = sbio->pagev[i];
2333                 struct scrub_block *sblock = spage->sblock;
2334
2335                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2336                         scrub_block_complete(sblock);
2337                 scrub_block_put(sblock);
2338         }
2339
2340         bio_put(sbio->bio);
2341         sbio->bio = NULL;
2342         spin_lock(&sctx->list_lock);
2343         sbio->next_free = sctx->first_free;
2344         sctx->first_free = sbio->index;
2345         spin_unlock(&sctx->list_lock);
2346
2347         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2348                 mutex_lock(&sctx->wr_lock);
2349                 scrub_wr_submit(sctx);
2350                 mutex_unlock(&sctx->wr_lock);
2351         }
2352
2353         scrub_pending_bio_dec(sctx);
2354 }
2355
2356 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2357                                        unsigned long *bitmap,
2358                                        u64 start, u64 len)
2359 {
2360         u64 offset;
2361         u64 nsectors64;
2362         u32 nsectors;
2363         int sectorsize = sparity->sctx->fs_info->sectorsize;
2364
2365         if (len >= sparity->stripe_len) {
2366                 bitmap_set(bitmap, 0, sparity->nsectors);
2367                 return;
2368         }
2369
2370         start -= sparity->logic_start;
2371         start = div64_u64_rem(start, sparity->stripe_len, &offset);
2372         offset = div_u64(offset, sectorsize);
2373         nsectors64 = div_u64(len, sectorsize);
2374
2375         ASSERT(nsectors64 < UINT_MAX);
2376         nsectors = (u32)nsectors64;
2377
2378         if (offset + nsectors <= sparity->nsectors) {
2379                 bitmap_set(bitmap, offset, nsectors);
2380                 return;
2381         }
2382
2383         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2384         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2385 }
2386
2387 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2388                                                    u64 start, u64 len)
2389 {
2390         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2391 }
2392
2393 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2394                                                   u64 start, u64 len)
2395 {
2396         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2397 }
2398
2399 static void scrub_block_complete(struct scrub_block *sblock)
2400 {
2401         int corrupted = 0;
2402
2403         if (!sblock->no_io_error_seen) {
2404                 corrupted = 1;
2405                 scrub_handle_errored_block(sblock);
2406         } else {
2407                 /*
2408                  * if has checksum error, write via repair mechanism in
2409                  * dev replace case, otherwise write here in dev replace
2410                  * case.
2411                  */
2412                 corrupted = scrub_checksum(sblock);
2413                 if (!corrupted && sblock->sctx->is_dev_replace)
2414                         scrub_write_block_to_dev_replace(sblock);
2415         }
2416
2417         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2418                 u64 start = sblock->pagev[0]->logical;
2419                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2420                           PAGE_SIZE;
2421
2422                 scrub_parity_mark_sectors_error(sblock->sparity,
2423                                                 start, end - start);
2424         }
2425 }
2426
2427 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2428 {
2429         struct btrfs_ordered_sum *sum = NULL;
2430         unsigned long index;
2431         unsigned long num_sectors;
2432
2433         while (!list_empty(&sctx->csum_list)) {
2434                 sum = list_first_entry(&sctx->csum_list,
2435                                        struct btrfs_ordered_sum, list);
2436                 if (sum->bytenr > logical)
2437                         return 0;
2438                 if (sum->bytenr + sum->len > logical)
2439                         break;
2440
2441                 ++sctx->stat.csum_discards;
2442                 list_del(&sum->list);
2443                 kfree(sum);
2444                 sum = NULL;
2445         }
2446         if (!sum)
2447                 return 0;
2448
2449         index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize);
2450         ASSERT(index < UINT_MAX);
2451
2452         num_sectors = sum->len / sctx->fs_info->sectorsize;
2453         memcpy(csum, sum->sums + index * sctx->csum_size, sctx->csum_size);
2454         if (index == num_sectors - 1) {
2455                 list_del(&sum->list);
2456                 kfree(sum);
2457         }
2458         return 1;
2459 }
2460
2461 /* scrub extent tries to collect up to 64 kB for each bio */
2462 static int scrub_extent(struct scrub_ctx *sctx, struct map_lookup *map,
2463                         u64 logical, u64 len,
2464                         u64 physical, struct btrfs_device *dev, u64 flags,
2465                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2466 {
2467         int ret;
2468         u8 csum[BTRFS_CSUM_SIZE];
2469         u32 blocksize;
2470
2471         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2472                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2473                         blocksize = map->stripe_len;
2474                 else
2475                         blocksize = sctx->fs_info->sectorsize;
2476                 spin_lock(&sctx->stat_lock);
2477                 sctx->stat.data_extents_scrubbed++;
2478                 sctx->stat.data_bytes_scrubbed += len;
2479                 spin_unlock(&sctx->stat_lock);
2480         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2481                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2482                         blocksize = map->stripe_len;
2483                 else
2484                         blocksize = sctx->fs_info->nodesize;
2485                 spin_lock(&sctx->stat_lock);
2486                 sctx->stat.tree_extents_scrubbed++;
2487                 sctx->stat.tree_bytes_scrubbed += len;
2488                 spin_unlock(&sctx->stat_lock);
2489         } else {
2490                 blocksize = sctx->fs_info->sectorsize;
2491                 WARN_ON(1);
2492         }
2493
2494         while (len) {
2495                 u64 l = min_t(u64, len, blocksize);
2496                 int have_csum = 0;
2497
2498                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2499                         /* push csums to sbio */
2500                         have_csum = scrub_find_csum(sctx, logical, csum);
2501                         if (have_csum == 0)
2502                                 ++sctx->stat.no_csum;
2503                 }
2504                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2505                                   mirror_num, have_csum ? csum : NULL, 0,
2506                                   physical_for_dev_replace);
2507                 if (ret)
2508                         return ret;
2509                 len -= l;
2510                 logical += l;
2511                 physical += l;
2512                 physical_for_dev_replace += l;
2513         }
2514         return 0;
2515 }
2516
2517 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2518                                   u64 logical, u64 len,
2519                                   u64 physical, struct btrfs_device *dev,
2520                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2521 {
2522         struct scrub_ctx *sctx = sparity->sctx;
2523         struct scrub_block *sblock;
2524         int index;
2525
2526         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2527         if (!sblock) {
2528                 spin_lock(&sctx->stat_lock);
2529                 sctx->stat.malloc_errors++;
2530                 spin_unlock(&sctx->stat_lock);
2531                 return -ENOMEM;
2532         }
2533
2534         /* one ref inside this function, plus one for each page added to
2535          * a bio later on */
2536         refcount_set(&sblock->refs, 1);
2537         sblock->sctx = sctx;
2538         sblock->no_io_error_seen = 1;
2539         sblock->sparity = sparity;
2540         scrub_parity_get(sparity);
2541
2542         for (index = 0; len > 0; index++) {
2543                 struct scrub_page *spage;
2544                 u64 l = min_t(u64, len, PAGE_SIZE);
2545
2546                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2547                 if (!spage) {
2548 leave_nomem:
2549                         spin_lock(&sctx->stat_lock);
2550                         sctx->stat.malloc_errors++;
2551                         spin_unlock(&sctx->stat_lock);
2552                         scrub_block_put(sblock);
2553                         return -ENOMEM;
2554                 }
2555                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2556                 /* For scrub block */
2557                 scrub_page_get(spage);
2558                 sblock->pagev[index] = spage;
2559                 /* For scrub parity */
2560                 scrub_page_get(spage);
2561                 list_add_tail(&spage->list, &sparity->spages);
2562                 spage->sblock = sblock;
2563                 spage->dev = dev;
2564                 spage->flags = flags;
2565                 spage->generation = gen;
2566                 spage->logical = logical;
2567                 spage->physical = physical;
2568                 spage->mirror_num = mirror_num;
2569                 if (csum) {
2570                         spage->have_csum = 1;
2571                         memcpy(spage->csum, csum, sctx->csum_size);
2572                 } else {
2573                         spage->have_csum = 0;
2574                 }
2575                 sblock->page_count++;
2576                 spage->page = alloc_page(GFP_KERNEL);
2577                 if (!spage->page)
2578                         goto leave_nomem;
2579                 len -= l;
2580                 logical += l;
2581                 physical += l;
2582         }
2583
2584         WARN_ON(sblock->page_count == 0);
2585         for (index = 0; index < sblock->page_count; index++) {
2586                 struct scrub_page *spage = sblock->pagev[index];
2587                 int ret;
2588
2589                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2590                 if (ret) {
2591                         scrub_block_put(sblock);
2592                         return ret;
2593                 }
2594         }
2595
2596         /* last one frees, either here or in bio completion for last page */
2597         scrub_block_put(sblock);
2598         return 0;
2599 }
2600
2601 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2602                                    u64 logical, u64 len,
2603                                    u64 physical, struct btrfs_device *dev,
2604                                    u64 flags, u64 gen, int mirror_num)
2605 {
2606         struct scrub_ctx *sctx = sparity->sctx;
2607         int ret;
2608         u8 csum[BTRFS_CSUM_SIZE];
2609         u32 blocksize;
2610
2611         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2612                 scrub_parity_mark_sectors_error(sparity, logical, len);
2613                 return 0;
2614         }
2615
2616         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2617                 blocksize = sparity->stripe_len;
2618         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2619                 blocksize = sparity->stripe_len;
2620         } else {
2621                 blocksize = sctx->fs_info->sectorsize;
2622                 WARN_ON(1);
2623         }
2624
2625         while (len) {
2626                 u64 l = min_t(u64, len, blocksize);
2627                 int have_csum = 0;
2628
2629                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2630                         /* push csums to sbio */
2631                         have_csum = scrub_find_csum(sctx, logical, csum);
2632                         if (have_csum == 0)
2633                                 goto skip;
2634                 }
2635                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2636                                              flags, gen, mirror_num,
2637                                              have_csum ? csum : NULL);
2638                 if (ret)
2639                         return ret;
2640 skip:
2641                 len -= l;
2642                 logical += l;
2643                 physical += l;
2644         }
2645         return 0;
2646 }
2647
2648 /*
2649  * Given a physical address, this will calculate it's
2650  * logical offset. if this is a parity stripe, it will return
2651  * the most left data stripe's logical offset.
2652  *
2653  * return 0 if it is a data stripe, 1 means parity stripe.
2654  */
2655 static int get_raid56_logic_offset(u64 physical, int num,
2656                                    struct map_lookup *map, u64 *offset,
2657                                    u64 *stripe_start)
2658 {
2659         int i;
2660         int j = 0;
2661         u64 stripe_nr;
2662         u64 last_offset;
2663         u32 stripe_index;
2664         u32 rot;
2665         const int data_stripes = nr_data_stripes(map);
2666
2667         last_offset = (physical - map->stripes[num].physical) * data_stripes;
2668         if (stripe_start)
2669                 *stripe_start = last_offset;
2670
2671         *offset = last_offset;
2672         for (i = 0; i < data_stripes; i++) {
2673                 *offset = last_offset + i * map->stripe_len;
2674
2675                 stripe_nr = div64_u64(*offset, map->stripe_len);
2676                 stripe_nr = div_u64(stripe_nr, data_stripes);
2677
2678                 /* Work out the disk rotation on this stripe-set */
2679                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2680                 /* calculate which stripe this data locates */
2681                 rot += i;
2682                 stripe_index = rot % map->num_stripes;
2683                 if (stripe_index == num)
2684                         return 0;
2685                 if (stripe_index < num)
2686                         j++;
2687         }
2688         *offset = last_offset + j * map->stripe_len;
2689         return 1;
2690 }
2691
2692 static void scrub_free_parity(struct scrub_parity *sparity)
2693 {
2694         struct scrub_ctx *sctx = sparity->sctx;
2695         struct scrub_page *curr, *next;
2696         int nbits;
2697
2698         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2699         if (nbits) {
2700                 spin_lock(&sctx->stat_lock);
2701                 sctx->stat.read_errors += nbits;
2702                 sctx->stat.uncorrectable_errors += nbits;
2703                 spin_unlock(&sctx->stat_lock);
2704         }
2705
2706         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2707                 list_del_init(&curr->list);
2708                 scrub_page_put(curr);
2709         }
2710
2711         kfree(sparity);
2712 }
2713
2714 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2715 {
2716         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2717                                                     work);
2718         struct scrub_ctx *sctx = sparity->sctx;
2719
2720         scrub_free_parity(sparity);
2721         scrub_pending_bio_dec(sctx);
2722 }
2723
2724 static void scrub_parity_bio_endio(struct bio *bio)
2725 {
2726         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
2727         struct btrfs_fs_info *fs_info = sparity->sctx->fs_info;
2728
2729         if (bio->bi_status)
2730                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2731                           sparity->nsectors);
2732
2733         bio_put(bio);
2734
2735         btrfs_init_work(&sparity->work, scrub_parity_bio_endio_worker, NULL,
2736                         NULL);
2737         btrfs_queue_work(fs_info->scrub_parity_workers, &sparity->work);
2738 }
2739
2740 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
2741 {
2742         struct scrub_ctx *sctx = sparity->sctx;
2743         struct btrfs_fs_info *fs_info = sctx->fs_info;
2744         struct bio *bio;
2745         struct btrfs_raid_bio *rbio;
2746         struct btrfs_bio *bbio = NULL;
2747         u64 length;
2748         int ret;
2749
2750         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
2751                            sparity->nsectors))
2752                 goto out;
2753
2754         length = sparity->logic_end - sparity->logic_start;
2755
2756         btrfs_bio_counter_inc_blocked(fs_info);
2757         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,
2758                                &length, &bbio);
2759         if (ret || !bbio || !bbio->raid_map)
2760                 goto bbio_out;
2761
2762         bio = btrfs_io_bio_alloc(0);
2763         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
2764         bio->bi_private = sparity;
2765         bio->bi_end_io = scrub_parity_bio_endio;
2766
2767         rbio = raid56_parity_alloc_scrub_rbio(fs_info, bio, bbio,
2768                                               length, sparity->scrub_dev,
2769                                               sparity->dbitmap,
2770                                               sparity->nsectors);
2771         if (!rbio)
2772                 goto rbio_out;
2773
2774         scrub_pending_bio_inc(sctx);
2775         raid56_parity_submit_scrub_rbio(rbio);
2776         return;
2777
2778 rbio_out:
2779         bio_put(bio);
2780 bbio_out:
2781         btrfs_bio_counter_dec(fs_info);
2782         btrfs_put_bbio(bbio);
2783         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2784                   sparity->nsectors);
2785         spin_lock(&sctx->stat_lock);
2786         sctx->stat.malloc_errors++;
2787         spin_unlock(&sctx->stat_lock);
2788 out:
2789         scrub_free_parity(sparity);
2790 }
2791
2792 static inline int scrub_calc_parity_bitmap_len(int nsectors)
2793 {
2794         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
2795 }
2796
2797 static void scrub_parity_get(struct scrub_parity *sparity)
2798 {
2799         refcount_inc(&sparity->refs);
2800 }
2801
2802 static void scrub_parity_put(struct scrub_parity *sparity)
2803 {
2804         if (!refcount_dec_and_test(&sparity->refs))
2805                 return;
2806
2807         scrub_parity_check_and_repair(sparity);
2808 }
2809
2810 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
2811                                                   struct map_lookup *map,
2812                                                   struct btrfs_device *sdev,
2813                                                   struct btrfs_path *path,
2814                                                   u64 logic_start,
2815                                                   u64 logic_end)
2816 {
2817         struct btrfs_fs_info *fs_info = sctx->fs_info;
2818         struct btrfs_root *root = fs_info->extent_root;
2819         struct btrfs_root *csum_root = fs_info->csum_root;
2820         struct btrfs_extent_item *extent;
2821         struct btrfs_bio *bbio = NULL;
2822         u64 flags;
2823         int ret;
2824         int slot;
2825         struct extent_buffer *l;
2826         struct btrfs_key key;
2827         u64 generation;
2828         u64 extent_logical;
2829         u64 extent_physical;
2830         u64 extent_len;
2831         u64 mapped_length;
2832         struct btrfs_device *extent_dev;
2833         struct scrub_parity *sparity;
2834         int nsectors;
2835         int bitmap_len;
2836         int extent_mirror_num;
2837         int stop_loop = 0;
2838
2839         nsectors = div_u64(map->stripe_len, fs_info->sectorsize);
2840         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
2841         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
2842                           GFP_NOFS);
2843         if (!sparity) {
2844                 spin_lock(&sctx->stat_lock);
2845                 sctx->stat.malloc_errors++;
2846                 spin_unlock(&sctx->stat_lock);
2847                 return -ENOMEM;
2848         }
2849
2850         sparity->stripe_len = map->stripe_len;
2851         sparity->nsectors = nsectors;
2852         sparity->sctx = sctx;
2853         sparity->scrub_dev = sdev;
2854         sparity->logic_start = logic_start;
2855         sparity->logic_end = logic_end;
2856         refcount_set(&sparity->refs, 1);
2857         INIT_LIST_HEAD(&sparity->spages);
2858         sparity->dbitmap = sparity->bitmap;
2859         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
2860
2861         ret = 0;
2862         while (logic_start < logic_end) {
2863                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2864                         key.type = BTRFS_METADATA_ITEM_KEY;
2865                 else
2866                         key.type = BTRFS_EXTENT_ITEM_KEY;
2867                 key.objectid = logic_start;
2868                 key.offset = (u64)-1;
2869
2870                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2871                 if (ret < 0)
2872                         goto out;
2873
2874                 if (ret > 0) {
2875                         ret = btrfs_previous_extent_item(root, path, 0);
2876                         if (ret < 0)
2877                                 goto out;
2878                         if (ret > 0) {
2879                                 btrfs_release_path(path);
2880                                 ret = btrfs_search_slot(NULL, root, &key,
2881                                                         path, 0, 0);
2882                                 if (ret < 0)
2883                                         goto out;
2884                         }
2885                 }
2886
2887                 stop_loop = 0;
2888                 while (1) {
2889                         u64 bytes;
2890
2891                         l = path->nodes[0];
2892                         slot = path->slots[0];
2893                         if (slot >= btrfs_header_nritems(l)) {
2894                                 ret = btrfs_next_leaf(root, path);
2895                                 if (ret == 0)
2896                                         continue;
2897                                 if (ret < 0)
2898                                         goto out;
2899
2900                                 stop_loop = 1;
2901                                 break;
2902                         }
2903                         btrfs_item_key_to_cpu(l, &key, slot);
2904
2905                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2906                             key.type != BTRFS_METADATA_ITEM_KEY)
2907                                 goto next;
2908
2909                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2910                                 bytes = fs_info->nodesize;
2911                         else
2912                                 bytes = key.offset;
2913
2914                         if (key.objectid + bytes <= logic_start)
2915                                 goto next;
2916
2917                         if (key.objectid >= logic_end) {
2918                                 stop_loop = 1;
2919                                 break;
2920                         }
2921
2922                         while (key.objectid >= logic_start + map->stripe_len)
2923                                 logic_start += map->stripe_len;
2924
2925                         extent = btrfs_item_ptr(l, slot,
2926                                                 struct btrfs_extent_item);
2927                         flags = btrfs_extent_flags(l, extent);
2928                         generation = btrfs_extent_generation(l, extent);
2929
2930                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
2931                             (key.objectid < logic_start ||
2932                              key.objectid + bytes >
2933                              logic_start + map->stripe_len)) {
2934                                 btrfs_err(fs_info,
2935                                           "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
2936                                           key.objectid, logic_start);
2937                                 spin_lock(&sctx->stat_lock);
2938                                 sctx->stat.uncorrectable_errors++;
2939                                 spin_unlock(&sctx->stat_lock);
2940                                 goto next;
2941                         }
2942 again:
2943                         extent_logical = key.objectid;
2944                         extent_len = bytes;
2945
2946                         if (extent_logical < logic_start) {
2947                                 extent_len -= logic_start - extent_logical;
2948                                 extent_logical = logic_start;
2949                         }
2950
2951                         if (extent_logical + extent_len >
2952                             logic_start + map->stripe_len)
2953                                 extent_len = logic_start + map->stripe_len -
2954                                              extent_logical;
2955
2956                         scrub_parity_mark_sectors_data(sparity, extent_logical,
2957                                                        extent_len);
2958
2959                         mapped_length = extent_len;
2960                         bbio = NULL;
2961                         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ,
2962                                         extent_logical, &mapped_length, &bbio,
2963                                         0);
2964                         if (!ret) {
2965                                 if (!bbio || mapped_length < extent_len)
2966                                         ret = -EIO;
2967                         }
2968                         if (ret) {
2969                                 btrfs_put_bbio(bbio);
2970                                 goto out;
2971                         }
2972                         extent_physical = bbio->stripes[0].physical;
2973                         extent_mirror_num = bbio->mirror_num;
2974                         extent_dev = bbio->stripes[0].dev;
2975                         btrfs_put_bbio(bbio);
2976
2977                         ret = btrfs_lookup_csums_range(csum_root,
2978                                                 extent_logical,
2979                                                 extent_logical + extent_len - 1,
2980                                                 &sctx->csum_list, 1);
2981                         if (ret)
2982                                 goto out;
2983
2984                         ret = scrub_extent_for_parity(sparity, extent_logical,
2985                                                       extent_len,
2986                                                       extent_physical,
2987                                                       extent_dev, flags,
2988                                                       generation,
2989                                                       extent_mirror_num);
2990
2991                         scrub_free_csums(sctx);
2992
2993                         if (ret)
2994                                 goto out;
2995
2996                         if (extent_logical + extent_len <
2997                             key.objectid + bytes) {
2998                                 logic_start += map->stripe_len;
2999
3000                                 if (logic_start >= logic_end) {
3001                                         stop_loop = 1;
3002                                         break;
3003                                 }
3004
3005                                 if (logic_start < key.objectid + bytes) {
3006                                         cond_resched();
3007                                         goto again;
3008                                 }
3009                         }
3010 next:
3011                         path->slots[0]++;
3012                 }
3013
3014                 btrfs_release_path(path);
3015
3016                 if (stop_loop)
3017                         break;
3018
3019                 logic_start += map->stripe_len;
3020         }
3021 out:
3022         if (ret < 0)
3023                 scrub_parity_mark_sectors_error(sparity, logic_start,
3024                                                 logic_end - logic_start);
3025         scrub_parity_put(sparity);
3026         scrub_submit(sctx);
3027         mutex_lock(&sctx->wr_lock);
3028         scrub_wr_submit(sctx);
3029         mutex_unlock(&sctx->wr_lock);
3030
3031         btrfs_release_path(path);
3032         return ret < 0 ? ret : 0;
3033 }
3034
3035 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3036                                            struct map_lookup *map,
3037                                            struct btrfs_device *scrub_dev,
3038                                            int num, u64 base, u64 length,
3039                                            struct btrfs_block_group *cache)
3040 {
3041         struct btrfs_path *path, *ppath;
3042         struct btrfs_fs_info *fs_info = sctx->fs_info;
3043         struct btrfs_root *root = fs_info->extent_root;
3044         struct btrfs_root *csum_root = fs_info->csum_root;
3045         struct btrfs_extent_item *extent;
3046         struct blk_plug plug;
3047         u64 flags;
3048         int ret;
3049         int slot;
3050         u64 nstripes;
3051         struct extent_buffer *l;
3052         u64 physical;
3053         u64 logical;
3054         u64 logic_end;
3055         u64 physical_end;
3056         u64 generation;
3057         int mirror_num;
3058         struct reada_control *reada1;
3059         struct reada_control *reada2;
3060         struct btrfs_key key;
3061         struct btrfs_key key_end;
3062         u64 increment = map->stripe_len;
3063         u64 offset;
3064         u64 extent_logical;
3065         u64 extent_physical;
3066         u64 extent_len;
3067         u64 stripe_logical;
3068         u64 stripe_end;
3069         struct btrfs_device *extent_dev;
3070         int extent_mirror_num;
3071         int stop_loop = 0;
3072
3073         physical = map->stripes[num].physical;
3074         offset = 0;
3075         nstripes = div64_u64(length, map->stripe_len);
3076         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3077                 offset = map->stripe_len * num;
3078                 increment = map->stripe_len * map->num_stripes;
3079                 mirror_num = 1;
3080         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3081                 int factor = map->num_stripes / map->sub_stripes;
3082                 offset = map->stripe_len * (num / map->sub_stripes);
3083                 increment = map->stripe_len * factor;
3084                 mirror_num = num % map->sub_stripes + 1;
3085         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1_MASK) {
3086                 increment = map->stripe_len;
3087                 mirror_num = num % map->num_stripes + 1;
3088         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3089                 increment = map->stripe_len;
3090                 mirror_num = num % map->num_stripes + 1;
3091         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3092                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3093                 increment = map->stripe_len * nr_data_stripes(map);
3094                 mirror_num = 1;
3095         } else {
3096                 increment = map->stripe_len;
3097                 mirror_num = 1;
3098         }
3099
3100         path = btrfs_alloc_path();
3101         if (!path)
3102                 return -ENOMEM;
3103
3104         ppath = btrfs_alloc_path();
3105         if (!ppath) {
3106                 btrfs_free_path(path);
3107                 return -ENOMEM;
3108         }
3109
3110         /*
3111          * work on commit root. The related disk blocks are static as
3112          * long as COW is applied. This means, it is save to rewrite
3113          * them to repair disk errors without any race conditions
3114          */
3115         path->search_commit_root = 1;
3116         path->skip_locking = 1;
3117
3118         ppath->search_commit_root = 1;
3119         ppath->skip_locking = 1;
3120         /*
3121          * trigger the readahead for extent tree csum tree and wait for
3122          * completion. During readahead, the scrub is officially paused
3123          * to not hold off transaction commits
3124          */
3125         logical = base + offset;
3126         physical_end = physical + nstripes * map->stripe_len;
3127         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3128                 get_raid56_logic_offset(physical_end, num,
3129                                         map, &logic_end, NULL);
3130                 logic_end += base;
3131         } else {
3132                 logic_end = logical + increment * nstripes;
3133         }
3134         wait_event(sctx->list_wait,
3135                    atomic_read(&sctx->bios_in_flight) == 0);
3136         scrub_blocked_if_needed(fs_info);
3137
3138         /* FIXME it might be better to start readahead at commit root */
3139         key.objectid = logical;
3140         key.type = BTRFS_EXTENT_ITEM_KEY;
3141         key.offset = (u64)0;
3142         key_end.objectid = logic_end;
3143         key_end.type = BTRFS_METADATA_ITEM_KEY;
3144         key_end.offset = (u64)-1;
3145         reada1 = btrfs_reada_add(root, &key, &key_end);
3146
3147         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3148         key.type = BTRFS_EXTENT_CSUM_KEY;
3149         key.offset = logical;
3150         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3151         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3152         key_end.offset = logic_end;
3153         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3154
3155         if (!IS_ERR(reada1))
3156                 btrfs_reada_wait(reada1);
3157         if (!IS_ERR(reada2))
3158                 btrfs_reada_wait(reada2);
3159
3160
3161         /*
3162          * collect all data csums for the stripe to avoid seeking during
3163          * the scrub. This might currently (crc32) end up to be about 1MB
3164          */
3165         blk_start_plug(&plug);
3166
3167         /*
3168          * now find all extents for each stripe and scrub them
3169          */
3170         ret = 0;
3171         while (physical < physical_end) {
3172                 /*
3173                  * canceled?
3174                  */
3175                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3176                     atomic_read(&sctx->cancel_req)) {
3177                         ret = -ECANCELED;
3178                         goto out;
3179                 }
3180                 /*
3181                  * check to see if we have to pause
3182                  */
3183                 if (atomic_read(&fs_info->scrub_pause_req)) {
3184                         /* push queued extents */
3185                         sctx->flush_all_writes = true;
3186                         scrub_submit(sctx);
3187                         mutex_lock(&sctx->wr_lock);
3188                         scrub_wr_submit(sctx);
3189                         mutex_unlock(&sctx->wr_lock);
3190                         wait_event(sctx->list_wait,
3191                                    atomic_read(&sctx->bios_in_flight) == 0);
3192                         sctx->flush_all_writes = false;
3193                         scrub_blocked_if_needed(fs_info);
3194                 }
3195
3196                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3197                         ret = get_raid56_logic_offset(physical, num, map,
3198                                                       &logical,
3199                                                       &stripe_logical);
3200                         logical += base;
3201                         if (ret) {
3202                                 /* it is parity strip */
3203                                 stripe_logical += base;
3204                                 stripe_end = stripe_logical + increment;
3205                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3206                                                           ppath, stripe_logical,
3207                                                           stripe_end);
3208                                 if (ret)
3209                                         goto out;
3210                                 goto skip;
3211                         }
3212                 }
3213
3214                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3215                         key.type = BTRFS_METADATA_ITEM_KEY;
3216                 else
3217                         key.type = BTRFS_EXTENT_ITEM_KEY;
3218                 key.objectid = logical;
3219                 key.offset = (u64)-1;
3220
3221                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3222                 if (ret < 0)
3223                         goto out;
3224
3225                 if (ret > 0) {
3226                         ret = btrfs_previous_extent_item(root, path, 0);
3227                         if (ret < 0)
3228                                 goto out;
3229                         if (ret > 0) {
3230                                 /* there's no smaller item, so stick with the
3231                                  * larger one */
3232                                 btrfs_release_path(path);
3233                                 ret = btrfs_search_slot(NULL, root, &key,
3234                                                         path, 0, 0);
3235                                 if (ret < 0)
3236                                         goto out;
3237                         }
3238                 }
3239
3240                 stop_loop = 0;
3241                 while (1) {
3242                         u64 bytes;
3243
3244                         l = path->nodes[0];
3245                         slot = path->slots[0];
3246                         if (slot >= btrfs_header_nritems(l)) {
3247                                 ret = btrfs_next_leaf(root, path);
3248                                 if (ret == 0)
3249                                         continue;
3250                                 if (ret < 0)
3251                                         goto out;
3252
3253                                 stop_loop = 1;
3254                                 break;
3255                         }
3256                         btrfs_item_key_to_cpu(l, &key, slot);
3257
3258                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3259                             key.type != BTRFS_METADATA_ITEM_KEY)
3260                                 goto next;
3261
3262                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3263                                 bytes = fs_info->nodesize;
3264                         else
3265                                 bytes = key.offset;
3266
3267                         if (key.objectid + bytes <= logical)
3268                                 goto next;
3269
3270                         if (key.objectid >= logical + map->stripe_len) {
3271                                 /* out of this device extent */
3272                                 if (key.objectid >= logic_end)
3273                                         stop_loop = 1;
3274                                 break;
3275                         }
3276
3277                         /*
3278                          * If our block group was removed in the meanwhile, just
3279                          * stop scrubbing since there is no point in continuing.
3280                          * Continuing would prevent reusing its device extents
3281                          * for new block groups for a long time.
3282                          */
3283                         spin_lock(&cache->lock);
3284                         if (cache->removed) {
3285                                 spin_unlock(&cache->lock);
3286                                 ret = 0;
3287                                 goto out;
3288                         }
3289                         spin_unlock(&cache->lock);
3290
3291                         extent = btrfs_item_ptr(l, slot,
3292                                                 struct btrfs_extent_item);
3293                         flags = btrfs_extent_flags(l, extent);
3294                         generation = btrfs_extent_generation(l, extent);
3295
3296                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3297                             (key.objectid < logical ||
3298                              key.objectid + bytes >
3299                              logical + map->stripe_len)) {
3300                                 btrfs_err(fs_info,
3301                                            "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
3302                                        key.objectid, logical);
3303                                 spin_lock(&sctx->stat_lock);
3304                                 sctx->stat.uncorrectable_errors++;
3305                                 spin_unlock(&sctx->stat_lock);
3306                                 goto next;
3307                         }
3308
3309 again:
3310                         extent_logical = key.objectid;
3311                         extent_len = bytes;
3312
3313                         /*
3314                          * trim extent to this stripe
3315                          */
3316                         if (extent_logical < logical) {
3317                                 extent_len -= logical - extent_logical;
3318                                 extent_logical = logical;
3319                         }
3320                         if (extent_logical + extent_len >
3321                             logical + map->stripe_len) {
3322                                 extent_len = logical + map->stripe_len -
3323                                              extent_logical;
3324                         }
3325
3326                         extent_physical = extent_logical - logical + physical;
3327                         extent_dev = scrub_dev;
3328                         extent_mirror_num = mirror_num;
3329                         if (sctx->is_dev_replace)
3330                                 scrub_remap_extent(fs_info, extent_logical,
3331                                                    extent_len, &extent_physical,
3332                                                    &extent_dev,
3333                                                    &extent_mirror_num);
3334
3335                         if (flags & BTRFS_EXTENT_FLAG_DATA) {
3336                                 ret = btrfs_lookup_csums_range(csum_root,
3337                                                 extent_logical,
3338                                                 extent_logical + extent_len - 1,
3339                                                 &sctx->csum_list, 1);
3340                                 if (ret)
3341                                         goto out;
3342                         }
3343
3344                         ret = scrub_extent(sctx, map, extent_logical, extent_len,
3345                                            extent_physical, extent_dev, flags,
3346                                            generation, extent_mirror_num,
3347                                            extent_logical - logical + physical);
3348
3349                         scrub_free_csums(sctx);
3350
3351                         if (ret)
3352                                 goto out;
3353
3354                         if (extent_logical + extent_len <
3355                             key.objectid + bytes) {
3356                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3357                                         /*
3358                                          * loop until we find next data stripe
3359                                          * or we have finished all stripes.
3360                                          */
3361 loop:
3362                                         physical += map->stripe_len;
3363                                         ret = get_raid56_logic_offset(physical,
3364                                                         num, map, &logical,
3365                                                         &stripe_logical);
3366                                         logical += base;
3367
3368                                         if (ret && physical < physical_end) {
3369                                                 stripe_logical += base;
3370                                                 stripe_end = stripe_logical +
3371                                                                 increment;
3372                                                 ret = scrub_raid56_parity(sctx,
3373                                                         map, scrub_dev, ppath,
3374                                                         stripe_logical,
3375                                                         stripe_end);
3376                                                 if (ret)
3377                                                         goto out;
3378                                                 goto loop;
3379                                         }
3380                                 } else {
3381                                         physical += map->stripe_len;
3382                                         logical += increment;
3383                                 }
3384                                 if (logical < key.objectid + bytes) {
3385                                         cond_resched();
3386                                         goto again;
3387                                 }
3388
3389                                 if (physical >= physical_end) {
3390                                         stop_loop = 1;
3391                                         break;
3392                                 }
3393                         }
3394 next:
3395                         path->slots[0]++;
3396                 }
3397                 btrfs_release_path(path);
3398 skip:
3399                 logical += increment;
3400                 physical += map->stripe_len;
3401                 spin_lock(&sctx->stat_lock);
3402                 if (stop_loop)
3403                         sctx->stat.last_physical = map->stripes[num].physical +
3404                                                    length;
3405                 else
3406                         sctx->stat.last_physical = physical;
3407                 spin_unlock(&sctx->stat_lock);
3408                 if (stop_loop)
3409                         break;
3410         }
3411 out:
3412         /* push queued extents */
3413         scrub_submit(sctx);
3414         mutex_lock(&sctx->wr_lock);
3415         scrub_wr_submit(sctx);
3416         mutex_unlock(&sctx->wr_lock);
3417
3418         blk_finish_plug(&plug);
3419         btrfs_free_path(path);
3420         btrfs_free_path(ppath);
3421         return ret < 0 ? ret : 0;
3422 }
3423
3424 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3425                                           struct btrfs_device *scrub_dev,
3426                                           u64 chunk_offset, u64 length,
3427                                           u64 dev_offset,
3428                                           struct btrfs_block_group *cache)
3429 {
3430         struct btrfs_fs_info *fs_info = sctx->fs_info;
3431         struct extent_map_tree *map_tree = &fs_info->mapping_tree;
3432         struct map_lookup *map;
3433         struct extent_map *em;
3434         int i;
3435         int ret = 0;
3436
3437         read_lock(&map_tree->lock);
3438         em = lookup_extent_mapping(map_tree, chunk_offset, 1);
3439         read_unlock(&map_tree->lock);
3440
3441         if (!em) {
3442                 /*
3443                  * Might have been an unused block group deleted by the cleaner
3444                  * kthread or relocation.
3445                  */
3446                 spin_lock(&cache->lock);
3447                 if (!cache->removed)
3448                         ret = -EINVAL;
3449                 spin_unlock(&cache->lock);
3450
3451                 return ret;
3452         }
3453
3454         map = em->map_lookup;
3455         if (em->start != chunk_offset)
3456                 goto out;
3457
3458         if (em->len < length)
3459                 goto out;
3460
3461         for (i = 0; i < map->num_stripes; ++i) {
3462                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3463                     map->stripes[i].physical == dev_offset) {
3464                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3465                                            chunk_offset, length, cache);
3466                         if (ret)
3467                                 goto out;
3468                 }
3469         }
3470 out:
3471         free_extent_map(em);
3472
3473         return ret;
3474 }
3475
3476 static noinline_for_stack
3477 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3478                            struct btrfs_device *scrub_dev, u64 start, u64 end)
3479 {
3480         struct btrfs_dev_extent *dev_extent = NULL;
3481         struct btrfs_path *path;
3482         struct btrfs_fs_info *fs_info = sctx->fs_info;
3483         struct btrfs_root *root = fs_info->dev_root;
3484         u64 length;
3485         u64 chunk_offset;
3486         int ret = 0;
3487         int ro_set;
3488         int slot;
3489         struct extent_buffer *l;
3490         struct btrfs_key key;
3491         struct btrfs_key found_key;
3492         struct btrfs_block_group *cache;
3493         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3494
3495         path = btrfs_alloc_path();
3496         if (!path)
3497                 return -ENOMEM;
3498
3499         path->reada = READA_FORWARD;
3500         path->search_commit_root = 1;
3501         path->skip_locking = 1;
3502
3503         key.objectid = scrub_dev->devid;
3504         key.offset = 0ull;
3505         key.type = BTRFS_DEV_EXTENT_KEY;
3506
3507         while (1) {
3508                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3509                 if (ret < 0)
3510                         break;
3511                 if (ret > 0) {
3512                         if (path->slots[0] >=
3513                             btrfs_header_nritems(path->nodes[0])) {
3514                                 ret = btrfs_next_leaf(root, path);
3515                                 if (ret < 0)
3516                                         break;
3517                                 if (ret > 0) {
3518                                         ret = 0;
3519                                         break;
3520                                 }
3521                         } else {
3522                                 ret = 0;
3523                         }
3524                 }
3525
3526                 l = path->nodes[0];
3527                 slot = path->slots[0];
3528
3529                 btrfs_item_key_to_cpu(l, &found_key, slot);
3530
3531                 if (found_key.objectid != scrub_dev->devid)
3532                         break;
3533
3534                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3535                         break;
3536
3537                 if (found_key.offset >= end)
3538                         break;
3539
3540                 if (found_key.offset < key.offset)
3541                         break;
3542
3543                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3544                 length = btrfs_dev_extent_length(l, dev_extent);
3545
3546                 if (found_key.offset + length <= start)
3547                         goto skip;
3548
3549                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3550
3551                 /*
3552                  * get a reference on the corresponding block group to prevent
3553                  * the chunk from going away while we scrub it
3554                  */
3555                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3556
3557                 /* some chunks are removed but not committed to disk yet,
3558                  * continue scrubbing */
3559                 if (!cache)
3560                         goto skip;
3561
3562                 /*
3563                  * Make sure that while we are scrubbing the corresponding block
3564                  * group doesn't get its logical address and its device extents
3565                  * reused for another block group, which can possibly be of a
3566                  * different type and different profile. We do this to prevent
3567                  * false error detections and crashes due to bogus attempts to
3568                  * repair extents.
3569                  */
3570                 spin_lock(&cache->lock);
3571                 if (cache->removed) {
3572                         spin_unlock(&cache->lock);
3573                         btrfs_put_block_group(cache);
3574                         goto skip;
3575                 }
3576                 btrfs_freeze_block_group(cache);
3577                 spin_unlock(&cache->lock);
3578
3579                 /*
3580                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3581                  * to avoid deadlock caused by:
3582                  * btrfs_inc_block_group_ro()
3583                  * -> btrfs_wait_for_commit()
3584                  * -> btrfs_commit_transaction()
3585                  * -> btrfs_scrub_pause()
3586                  */
3587                 scrub_pause_on(fs_info);
3588
3589                 /*
3590                  * Don't do chunk preallocation for scrub.
3591                  *
3592                  * This is especially important for SYSTEM bgs, or we can hit
3593                  * -EFBIG from btrfs_finish_chunk_alloc() like:
3594                  * 1. The only SYSTEM bg is marked RO.
3595                  *    Since SYSTEM bg is small, that's pretty common.
3596                  * 2. New SYSTEM bg will be allocated
3597                  *    Due to regular version will allocate new chunk.
3598                  * 3. New SYSTEM bg is empty and will get cleaned up
3599                  *    Before cleanup really happens, it's marked RO again.
3600                  * 4. Empty SYSTEM bg get scrubbed
3601                  *    We go back to 2.
3602                  *
3603                  * This can easily boost the amount of SYSTEM chunks if cleaner
3604                  * thread can't be triggered fast enough, and use up all space
3605                  * of btrfs_super_block::sys_chunk_array
3606                  *
3607                  * While for dev replace, we need to try our best to mark block
3608                  * group RO, to prevent race between:
3609                  * - Write duplication
3610                  *   Contains latest data
3611                  * - Scrub copy
3612                  *   Contains data from commit tree
3613                  *
3614                  * If target block group is not marked RO, nocow writes can
3615                  * be overwritten by scrub copy, causing data corruption.
3616                  * So for dev-replace, it's not allowed to continue if a block
3617                  * group is not RO.
3618                  */
3619                 ret = btrfs_inc_block_group_ro(cache, sctx->is_dev_replace);
3620                 if (ret == 0) {
3621                         ro_set = 1;
3622                 } else if (ret == -ENOSPC && !sctx->is_dev_replace) {
3623                         /*
3624                          * btrfs_inc_block_group_ro return -ENOSPC when it
3625                          * failed in creating new chunk for metadata.
3626                          * It is not a problem for scrub, because
3627                          * metadata are always cowed, and our scrub paused
3628                          * commit_transactions.
3629                          */
3630                         ro_set = 0;
3631                 } else {
3632                         btrfs_warn(fs_info,
3633                                    "failed setting block group ro: %d", ret);
3634                         btrfs_unfreeze_block_group(cache);
3635                         btrfs_put_block_group(cache);
3636                         scrub_pause_off(fs_info);
3637                         break;
3638                 }
3639
3640                 /*
3641                  * Now the target block is marked RO, wait for nocow writes to
3642                  * finish before dev-replace.
3643                  * COW is fine, as COW never overwrites extents in commit tree.
3644                  */
3645                 if (sctx->is_dev_replace) {
3646                         btrfs_wait_nocow_writers(cache);
3647                         btrfs_wait_ordered_roots(fs_info, U64_MAX, cache->start,
3648                                         cache->length);
3649                 }
3650
3651                 scrub_pause_off(fs_info);
3652                 down_write(&dev_replace->rwsem);
3653                 dev_replace->cursor_right = found_key.offset + length;
3654                 dev_replace->cursor_left = found_key.offset;
3655                 dev_replace->item_needs_writeback = 1;
3656                 up_write(&dev_replace->rwsem);
3657
3658                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3659                                   found_key.offset, cache);
3660
3661                 /*
3662                  * flush, submit all pending read and write bios, afterwards
3663                  * wait for them.
3664                  * Note that in the dev replace case, a read request causes
3665                  * write requests that are submitted in the read completion
3666                  * worker. Therefore in the current situation, it is required
3667                  * that all write requests are flushed, so that all read and
3668                  * write requests are really completed when bios_in_flight
3669                  * changes to 0.
3670                  */
3671                 sctx->flush_all_writes = true;
3672                 scrub_submit(sctx);
3673                 mutex_lock(&sctx->wr_lock);
3674                 scrub_wr_submit(sctx);
3675                 mutex_unlock(&sctx->wr_lock);
3676
3677                 wait_event(sctx->list_wait,
3678                            atomic_read(&sctx->bios_in_flight) == 0);
3679
3680                 scrub_pause_on(fs_info);
3681
3682                 /*
3683                  * must be called before we decrease @scrub_paused.
3684                  * make sure we don't block transaction commit while
3685                  * we are waiting pending workers finished.
3686                  */
3687                 wait_event(sctx->list_wait,
3688                            atomic_read(&sctx->workers_pending) == 0);
3689                 sctx->flush_all_writes = false;
3690
3691                 scrub_pause_off(fs_info);
3692
3693                 down_write(&dev_replace->rwsem);
3694                 dev_replace->cursor_left = dev_replace->cursor_right;
3695                 dev_replace->item_needs_writeback = 1;
3696                 up_write(&dev_replace->rwsem);
3697
3698                 if (ro_set)
3699                         btrfs_dec_block_group_ro(cache);
3700
3701                 /*
3702                  * We might have prevented the cleaner kthread from deleting
3703                  * this block group if it was already unused because we raced
3704                  * and set it to RO mode first. So add it back to the unused
3705                  * list, otherwise it might not ever be deleted unless a manual
3706                  * balance is triggered or it becomes used and unused again.
3707                  */
3708                 spin_lock(&cache->lock);
3709                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3710                     cache->used == 0) {
3711                         spin_unlock(&cache->lock);
3712                         if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
3713                                 btrfs_discard_queue_work(&fs_info->discard_ctl,
3714                                                          cache);
3715                         else
3716                                 btrfs_mark_bg_unused(cache);
3717                 } else {
3718                         spin_unlock(&cache->lock);
3719                 }
3720
3721                 btrfs_unfreeze_block_group(cache);
3722                 btrfs_put_block_group(cache);
3723                 if (ret)
3724                         break;
3725                 if (sctx->is_dev_replace &&
3726                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3727                         ret = -EIO;
3728                         break;
3729                 }
3730                 if (sctx->stat.malloc_errors > 0) {
3731                         ret = -ENOMEM;
3732                         break;
3733                 }
3734 skip:
3735                 key.offset = found_key.offset + length;
3736                 btrfs_release_path(path);
3737         }
3738
3739         btrfs_free_path(path);
3740
3741         return ret;
3742 }
3743
3744 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3745                                            struct btrfs_device *scrub_dev)
3746 {
3747         int     i;
3748         u64     bytenr;
3749         u64     gen;
3750         int     ret;
3751         struct btrfs_fs_info *fs_info = sctx->fs_info;
3752
3753         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
3754                 return -EIO;
3755
3756         /* Seed devices of a new filesystem has their own generation. */
3757         if (scrub_dev->fs_devices != fs_info->fs_devices)
3758                 gen = scrub_dev->generation;
3759         else
3760                 gen = fs_info->last_trans_committed;
3761
3762         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
3763                 bytenr = btrfs_sb_offset(i);
3764                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
3765                     scrub_dev->commit_total_bytes)
3766                         break;
3767
3768                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
3769                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
3770                                   NULL, 1, bytenr);
3771                 if (ret)
3772                         return ret;
3773         }
3774         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3775
3776         return 0;
3777 }
3778
3779 /*
3780  * get a reference count on fs_info->scrub_workers. start worker if necessary
3781  */
3782 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
3783                                                 int is_dev_replace)
3784 {
3785         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
3786         int max_active = fs_info->thread_pool_size;
3787
3788         lockdep_assert_held(&fs_info->scrub_lock);
3789
3790         if (refcount_read(&fs_info->scrub_workers_refcnt) == 0) {
3791                 ASSERT(fs_info->scrub_workers == NULL);
3792                 fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub",
3793                                 flags, is_dev_replace ? 1 : max_active, 4);
3794                 if (!fs_info->scrub_workers)
3795                         goto fail_scrub_workers;
3796
3797                 ASSERT(fs_info->scrub_wr_completion_workers == NULL);
3798                 fs_info->scrub_wr_completion_workers =
3799                         btrfs_alloc_workqueue(fs_info, "scrubwrc", flags,
3800                                               max_active, 2);
3801                 if (!fs_info->scrub_wr_completion_workers)
3802                         goto fail_scrub_wr_completion_workers;
3803
3804                 ASSERT(fs_info->scrub_parity_workers == NULL);
3805                 fs_info->scrub_parity_workers =
3806                         btrfs_alloc_workqueue(fs_info, "scrubparity", flags,
3807                                               max_active, 2);
3808                 if (!fs_info->scrub_parity_workers)
3809                         goto fail_scrub_parity_workers;
3810
3811                 refcount_set(&fs_info->scrub_workers_refcnt, 1);
3812         } else {
3813                 refcount_inc(&fs_info->scrub_workers_refcnt);
3814         }
3815         return 0;
3816
3817 fail_scrub_parity_workers:
3818         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3819 fail_scrub_wr_completion_workers:
3820         btrfs_destroy_workqueue(fs_info->scrub_workers);
3821 fail_scrub_workers:
3822         return -ENOMEM;
3823 }
3824
3825 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
3826                     u64 end, struct btrfs_scrub_progress *progress,
3827                     int readonly, int is_dev_replace)
3828 {
3829         struct scrub_ctx *sctx;
3830         int ret;
3831         struct btrfs_device *dev;
3832         unsigned int nofs_flag;
3833         struct btrfs_workqueue *scrub_workers = NULL;
3834         struct btrfs_workqueue *scrub_wr_comp = NULL;
3835         struct btrfs_workqueue *scrub_parity = NULL;
3836
3837         if (btrfs_fs_closing(fs_info))
3838                 return -EAGAIN;
3839
3840         if (fs_info->nodesize > BTRFS_STRIPE_LEN) {
3841                 /*
3842                  * in this case scrub is unable to calculate the checksum
3843                  * the way scrub is implemented. Do not handle this
3844                  * situation at all because it won't ever happen.
3845                  */
3846                 btrfs_err(fs_info,
3847                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
3848                        fs_info->nodesize,
3849                        BTRFS_STRIPE_LEN);
3850                 return -EINVAL;
3851         }
3852
3853         if (fs_info->sectorsize != PAGE_SIZE) {
3854                 /* not supported for data w/o checksums */
3855                 btrfs_err_rl(fs_info,
3856                            "scrub: size assumption sectorsize != PAGE_SIZE (%d != %lu) fails",
3857                        fs_info->sectorsize, PAGE_SIZE);
3858                 return -EINVAL;
3859         }
3860
3861         if (fs_info->nodesize >
3862             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
3863             fs_info->sectorsize > PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
3864                 /*
3865                  * would exhaust the array bounds of pagev member in
3866                  * struct scrub_block
3867                  */
3868                 btrfs_err(fs_info,
3869                           "scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
3870                        fs_info->nodesize,
3871                        SCRUB_MAX_PAGES_PER_BLOCK,
3872                        fs_info->sectorsize,
3873                        SCRUB_MAX_PAGES_PER_BLOCK);
3874                 return -EINVAL;
3875         }
3876
3877         /* Allocate outside of device_list_mutex */
3878         sctx = scrub_setup_ctx(fs_info, is_dev_replace);
3879         if (IS_ERR(sctx))
3880                 return PTR_ERR(sctx);
3881
3882         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3883         dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
3884         if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) &&
3885                      !is_dev_replace)) {
3886                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3887                 ret = -ENODEV;
3888                 goto out_free_ctx;
3889         }
3890
3891         if (!is_dev_replace && !readonly &&
3892             !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
3893                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3894                 btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable",
3895                                 rcu_str_deref(dev->name));
3896                 ret = -EROFS;
3897                 goto out_free_ctx;
3898         }
3899
3900         mutex_lock(&fs_info->scrub_lock);
3901         if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
3902             test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) {
3903                 mutex_unlock(&fs_info->scrub_lock);
3904                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3905                 ret = -EIO;
3906                 goto out_free_ctx;
3907         }
3908
3909         down_read(&fs_info->dev_replace.rwsem);
3910         if (dev->scrub_ctx ||
3911             (!is_dev_replace &&
3912              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
3913                 up_read(&fs_info->dev_replace.rwsem);
3914                 mutex_unlock(&fs_info->scrub_lock);
3915                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3916                 ret = -EINPROGRESS;
3917                 goto out_free_ctx;
3918         }
3919         up_read(&fs_info->dev_replace.rwsem);
3920
3921         ret = scrub_workers_get(fs_info, is_dev_replace);
3922         if (ret) {
3923                 mutex_unlock(&fs_info->scrub_lock);
3924                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3925                 goto out_free_ctx;
3926         }
3927
3928         sctx->readonly = readonly;
3929         dev->scrub_ctx = sctx;
3930         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3931
3932         /*
3933          * checking @scrub_pause_req here, we can avoid
3934          * race between committing transaction and scrubbing.
3935          */
3936         __scrub_blocked_if_needed(fs_info);
3937         atomic_inc(&fs_info->scrubs_running);
3938         mutex_unlock(&fs_info->scrub_lock);
3939
3940         /*
3941          * In order to avoid deadlock with reclaim when there is a transaction
3942          * trying to pause scrub, make sure we use GFP_NOFS for all the
3943          * allocations done at btrfs_scrub_pages() and scrub_pages_for_parity()
3944          * invoked by our callees. The pausing request is done when the
3945          * transaction commit starts, and it blocks the transaction until scrub
3946          * is paused (done at specific points at scrub_stripe() or right above
3947          * before incrementing fs_info->scrubs_running).
3948          */
3949         nofs_flag = memalloc_nofs_save();
3950         if (!is_dev_replace) {
3951                 btrfs_info(fs_info, "scrub: started on devid %llu", devid);
3952                 /*
3953                  * by holding device list mutex, we can
3954                  * kick off writing super in log tree sync.
3955                  */
3956                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
3957                 ret = scrub_supers(sctx, dev);
3958                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3959         }
3960
3961         if (!ret)
3962                 ret = scrub_enumerate_chunks(sctx, dev, start, end);
3963         memalloc_nofs_restore(nofs_flag);
3964
3965         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3966         atomic_dec(&fs_info->scrubs_running);
3967         wake_up(&fs_info->scrub_pause_wait);
3968
3969         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3970
3971         if (progress)
3972                 memcpy(progress, &sctx->stat, sizeof(*progress));
3973
3974         if (!is_dev_replace)
3975                 btrfs_info(fs_info, "scrub: %s on devid %llu with status: %d",
3976                         ret ? "not finished" : "finished", devid, ret);
3977
3978         mutex_lock(&fs_info->scrub_lock);
3979         dev->scrub_ctx = NULL;
3980         if (refcount_dec_and_test(&fs_info->scrub_workers_refcnt)) {
3981                 scrub_workers = fs_info->scrub_workers;
3982                 scrub_wr_comp = fs_info->scrub_wr_completion_workers;
3983                 scrub_parity = fs_info->scrub_parity_workers;
3984
3985                 fs_info->scrub_workers = NULL;
3986                 fs_info->scrub_wr_completion_workers = NULL;
3987                 fs_info->scrub_parity_workers = NULL;
3988         }
3989         mutex_unlock(&fs_info->scrub_lock);
3990
3991         btrfs_destroy_workqueue(scrub_workers);
3992         btrfs_destroy_workqueue(scrub_wr_comp);
3993         btrfs_destroy_workqueue(scrub_parity);
3994         scrub_put_ctx(sctx);
3995
3996         return ret;
3997
3998 out_free_ctx:
3999         scrub_free_ctx(sctx);
4000
4001         return ret;
4002 }
4003
4004 void btrfs_scrub_pause(struct btrfs_fs_info *fs_info)
4005 {
4006         mutex_lock(&fs_info->scrub_lock);
4007         atomic_inc(&fs_info->scrub_pause_req);
4008         while (atomic_read(&fs_info->scrubs_paused) !=
4009                atomic_read(&fs_info->scrubs_running)) {
4010                 mutex_unlock(&fs_info->scrub_lock);
4011                 wait_event(fs_info->scrub_pause_wait,
4012                            atomic_read(&fs_info->scrubs_paused) ==
4013                            atomic_read(&fs_info->scrubs_running));
4014                 mutex_lock(&fs_info->scrub_lock);
4015         }
4016         mutex_unlock(&fs_info->scrub_lock);
4017 }
4018
4019 void btrfs_scrub_continue(struct btrfs_fs_info *fs_info)
4020 {
4021         atomic_dec(&fs_info->scrub_pause_req);
4022         wake_up(&fs_info->scrub_pause_wait);
4023 }
4024
4025 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
4026 {
4027         mutex_lock(&fs_info->scrub_lock);
4028         if (!atomic_read(&fs_info->scrubs_running)) {
4029                 mutex_unlock(&fs_info->scrub_lock);
4030                 return -ENOTCONN;
4031         }
4032
4033         atomic_inc(&fs_info->scrub_cancel_req);
4034         while (atomic_read(&fs_info->scrubs_running)) {
4035                 mutex_unlock(&fs_info->scrub_lock);
4036                 wait_event(fs_info->scrub_pause_wait,
4037                            atomic_read(&fs_info->scrubs_running) == 0);
4038                 mutex_lock(&fs_info->scrub_lock);
4039         }
4040         atomic_dec(&fs_info->scrub_cancel_req);
4041         mutex_unlock(&fs_info->scrub_lock);
4042
4043         return 0;
4044 }
4045
4046 int btrfs_scrub_cancel_dev(struct btrfs_device *dev)
4047 {
4048         struct btrfs_fs_info *fs_info = dev->fs_info;
4049         struct scrub_ctx *sctx;
4050
4051         mutex_lock(&fs_info->scrub_lock);
4052         sctx = dev->scrub_ctx;
4053         if (!sctx) {
4054                 mutex_unlock(&fs_info->scrub_lock);
4055                 return -ENOTCONN;
4056         }
4057         atomic_inc(&sctx->cancel_req);
4058         while (dev->scrub_ctx) {
4059                 mutex_unlock(&fs_info->scrub_lock);
4060                 wait_event(fs_info->scrub_pause_wait,
4061                            dev->scrub_ctx == NULL);
4062                 mutex_lock(&fs_info->scrub_lock);
4063         }
4064         mutex_unlock(&fs_info->scrub_lock);
4065
4066         return 0;
4067 }
4068
4069 int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
4070                          struct btrfs_scrub_progress *progress)
4071 {
4072         struct btrfs_device *dev;
4073         struct scrub_ctx *sctx = NULL;
4074
4075         mutex_lock(&fs_info->fs_devices->device_list_mutex);
4076         dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
4077         if (dev)
4078                 sctx = dev->scrub_ctx;
4079         if (sctx)
4080                 memcpy(progress, &sctx->stat, sizeof(*progress));
4081         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4082
4083         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
4084 }
4085
4086 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
4087                                u64 extent_logical, u64 extent_len,
4088                                u64 *extent_physical,
4089                                struct btrfs_device **extent_dev,
4090                                int *extent_mirror_num)
4091 {
4092         u64 mapped_length;
4093         struct btrfs_bio *bbio = NULL;
4094         int ret;
4095
4096         mapped_length = extent_len;
4097         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, extent_logical,
4098                               &mapped_length, &bbio, 0);
4099         if (ret || !bbio || mapped_length < extent_len ||
4100             !bbio->stripes[0].dev->bdev) {
4101                 btrfs_put_bbio(bbio);
4102                 return;
4103         }
4104
4105         *extent_physical = bbio->stripes[0].physical;
4106         *extent_mirror_num = bbio->mirror_num;
4107         *extent_dev = bbio->stripes[0].dev;
4108         btrfs_put_bbio(bbio);
4109 }