fs/btrfs/scrub.c

   1 /*
   2  * Copyright (C) 2011, 2012 STRATO.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/ratelimit.h>
  21 #include "ctree.h"
  22 #include "volumes.h"
  23 #include "disk-io.h"
  24 #include "ordered-data.h"
  25 #include "transaction.h"
  26 #include "backref.h"
  27 #include "extent_io.h"
  28 #include "dev-replace.h"
  29 #include "check-integrity.h"
  30 #include "rcu-string.h"
  31 #include "raid56.h"
  32
  33 /*
  34  * This is only the first step towards a full-features scrub. It reads all
  35  * extent and super block and verifies the checksums. In case a bad checksum
  36  * is found or the extent cannot be read, good data will be written back if
  37  * any can be found.
  38  *
  39  * Future enhancements:
  40  *  - In case an unrepairable extent is encountered, track which files are
  41  *    affected and report them
  42  *  - track and record media errors, throw out bad devices
  43  *  - add a mode to also read unallocated space
  44  */
  45
  46 struct scrub_block;
  47 struct scrub_ctx;
  48
  49 /*
  50  * the following three values only influence the performance.
  51  * The last one configures the number of parallel and outstanding I/O
  52  * operations. The first two values configure an upper limit for the number
  53  * of (dynamically allocated) pages that are added to a bio.
  54  */
  55 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  56 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  57 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  58
  59 /*
  60  * the following value times PAGE_SIZE needs to be large enough to match the
  61  * largest node/leaf/sector size that shall be supported.
  62  * Values larger than BTRFS_STRIPE_LEN are not supported.
  63  */
  64 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  65
  66 struct scrub_page {
  67         struct scrub_block      *sblock;
  68         struct page             *page;
  69         struct btrfs_device     *dev;
  70         u64                     flags;  /* extent flags */
  71         u64                     generation;
  72         u64                     logical;
  73         u64                     physical;
  74         u64                     physical_for_dev_replace;
  75         atomic_t                ref_count;
  76         struct {
  77                 unsigned int    mirror_num:8;
  78                 unsigned int    have_csum:1;
  79                 unsigned int    io_error:1;
  80         };
  81         u8                      csum[BTRFS_CSUM_SIZE];
  82 };
  83
  84 struct scrub_bio {
  85         int                     index;
  86         struct scrub_ctx        *sctx;
  87         struct btrfs_device     *dev;
  88         struct bio              *bio;
  89         int                     err;
  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         atomic_t                ref_count; /* free mem on transition to zero */
 107         struct scrub_ctx        *sctx;
 108         struct {
 109                 unsigned int    header_error:1;
 110                 unsigned int    checksum_error:1;
 111                 unsigned int    no_io_error_seen:1;
 112                 unsigned int    generation_error:1; /* also sets header_error */
 113         };
 114 };
 115
 116 struct scrub_wr_ctx {
 117         struct scrub_bio *wr_curr_bio;
 118         struct btrfs_device *tgtdev;
 119         int pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 120         atomic_t flush_all_writes;
 121         struct mutex wr_lock;
 122 };
 123
 124 struct scrub_ctx {
 125         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 126         struct btrfs_root       *dev_root;
 127         int                     first_free;
 128         int                     curr;
 129         atomic_t                bios_in_flight;
 130         atomic_t                workers_pending;
 131         spinlock_t              list_lock;
 132         wait_queue_head_t       list_wait;
 133         u16                     csum_size;
 134         struct list_head        csum_list;
 135         atomic_t                cancel_req;
 136         int                     readonly;
 137         int                     pages_per_rd_bio;
 138         u32                     sectorsize;
 139         u32                     nodesize;
 140         u32                     leafsize;
 141
 142         int                     is_dev_replace;
 143         struct scrub_wr_ctx     wr_ctx;
 144
 145         /*
 146          * statistics
 147          */
 148         struct btrfs_scrub_progress stat;
 149         spinlock_t              stat_lock;
 150 };
 151
 152 struct scrub_fixup_nodatasum {
 153         struct scrub_ctx        *sctx;
 154         struct btrfs_device     *dev;
 155         u64                     logical;
 156         struct btrfs_root       *root;
 157         struct btrfs_work       work;
 158         int                     mirror_num;
 159 };
 160
 161 struct scrub_nocow_inode {
 162         u64                     inum;
 163         u64                     offset;
 164         u64                     root;
 165         struct list_head        list;
 166 };
 167
 168 struct scrub_copy_nocow_ctx {
 169         struct scrub_ctx        *sctx;
 170         u64                     logical;
 171         u64                     len;
 172         int                     mirror_num;
 173         u64                     physical_for_dev_replace;
 174         struct list_head        inodes;
 175         struct btrfs_work       work;
 176 };
 177
 178 struct scrub_warning {
 179         struct btrfs_path       *path;
 180         u64                     extent_item_size;
 181         char                    *scratch_buf;
 182         char                    *msg_buf;
 183         const char              *errstr;
 184         sector_t                sector;
 185         u64                     logical;
 186         struct btrfs_device     *dev;
 187         int                     msg_bufsize;
 188         int                     scratch_bufsize;
 189 };
 190
 191
 192 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 193 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 194 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
 195 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
 196 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 197 static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
 198                                      struct btrfs_fs_info *fs_info,
 199                                      struct scrub_block *original_sblock,
 200                                      u64 length, u64 logical,
 201                                      struct scrub_block *sblocks_for_recheck);
 202 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 203                                 struct scrub_block *sblock, int is_metadata,
 204                                 int have_csum, u8 *csum, u64 generation,
 205                                 u16 csum_size);
 206 static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
 207                                          struct scrub_block *sblock,
 208                                          int is_metadata, int have_csum,
 209                                          const u8 *csum, u64 generation,
 210                                          u16 csum_size);
 211 static void scrub_complete_bio_end_io(struct bio *bio, int err);
 212 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 213                                              struct scrub_block *sblock_good,
 214                                              int force_write);
 215 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 216                                             struct scrub_block *sblock_good,
 217                                             int page_num, int force_write);
 218 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 219 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 220                                            int page_num);
 221 static int scrub_checksum_data(struct scrub_block *sblock);
 222 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 223 static int scrub_checksum_super(struct scrub_block *sblock);
 224 static void scrub_block_get(struct scrub_block *sblock);
 225 static void scrub_block_put(struct scrub_block *sblock);
 226 static void scrub_page_get(struct scrub_page *spage);
 227 static void scrub_page_put(struct scrub_page *spage);
 228 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 229                                     struct scrub_page *spage);
 230 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 231                        u64 physical, struct btrfs_device *dev, u64 flags,
 232                        u64 gen, int mirror_num, u8 *csum, int force,
 233                        u64 physical_for_dev_replace);
 234 static void scrub_bio_end_io(struct bio *bio, int err);
 235 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 236 static void scrub_block_complete(struct scrub_block *sblock);
 237 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 238                                u64 extent_logical, u64 extent_len,
 239                                u64 *extent_physical,
 240                                struct btrfs_device **extent_dev,
 241                                int *extent_mirror_num);
 242 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
 243                               struct scrub_wr_ctx *wr_ctx,
 244                               struct btrfs_fs_info *fs_info,
 245                               struct btrfs_device *dev,
 246                               int is_dev_replace);
 247 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx);
 248 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 249                                     struct scrub_page *spage);
 250 static void scrub_wr_submit(struct scrub_ctx *sctx);
 251 static void scrub_wr_bio_end_io(struct bio *bio, int err);
 252 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 253 static int write_page_nocow(struct scrub_ctx *sctx,
 254                             u64 physical_for_dev_replace, struct page *page);
 255 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
 256                                       struct scrub_copy_nocow_ctx *ctx);
 257 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 258                             int mirror_num, u64 physical_for_dev_replace);
 259 static void copy_nocow_pages_worker(struct btrfs_work *work);
 260
 261
 262 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 263 {
 264         atomic_inc(&sctx->bios_in_flight);
 265 }
 266
 267 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 268 {
 269         atomic_dec(&sctx->bios_in_flight);
 270         wake_up(&sctx->list_wait);
 271 }
 272
 273 /*
 274  * used for workers that require transaction commits (i.e., for the
 275  * NOCOW case)
 276  */
 277 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
 278 {
 279         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 280
 281         /*
 282          * increment scrubs_running to prevent cancel requests from
 283          * completing as long as a worker is running. we must also
 284          * increment scrubs_paused to prevent deadlocking on pause
 285          * requests used for transactions commits (as the worker uses a
 286          * transaction context). it is safe to regard the worker
 287          * as paused for all matters practical. effectively, we only
 288          * avoid cancellation requests from completing.
 289          */
 290         mutex_lock(&fs_info->scrub_lock);
 291         atomic_inc(&fs_info->scrubs_running);
 292         atomic_inc(&fs_info->scrubs_paused);
 293         mutex_unlock(&fs_info->scrub_lock);
 294         atomic_inc(&sctx->workers_pending);
 295 }
 296
 297 /* used for workers that require transaction commits */
 298 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
 299 {
 300         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 301
 302         /*
 303          * see scrub_pending_trans_workers_inc() why we're pretending
 304          * to be paused in the scrub counters
 305          */
 306         mutex_lock(&fs_info->scrub_lock);
 307         atomic_dec(&fs_info->scrubs_running);
 308         atomic_dec(&fs_info->scrubs_paused);
 309         mutex_unlock(&fs_info->scrub_lock);
 310         atomic_dec(&sctx->workers_pending);
 311         wake_up(&fs_info->scrub_pause_wait);
 312         wake_up(&sctx->list_wait);
 313 }
 314
 315 static void scrub_free_csums(struct scrub_ctx *sctx)
 316 {
 317         while (!list_empty(&sctx->csum_list)) {
 318                 struct btrfs_ordered_sum *sum;
 319                 sum = list_first_entry(&sctx->csum_list,
 320                                        struct btrfs_ordered_sum, list);
 321                 list_del(&sum->list);
 322                 kfree(sum);
 323         }
 324 }
 325
 326 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 327 {
 328         int i;
 329
 330         if (!sctx)
 331                 return;
 332
 333         scrub_free_wr_ctx(&sctx->wr_ctx);
 334
 335         /* this can happen when scrub is cancelled */
 336         if (sctx->curr != -1) {
 337                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 338
 339                 for (i = 0; i < sbio->page_count; i++) {
 340                         WARN_ON(!sbio->pagev[i]->page);
 341                         scrub_block_put(sbio->pagev[i]->sblock);
 342                 }
 343                 bio_put(sbio->bio);
 344         }
 345
 346         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 347                 struct scrub_bio *sbio = sctx->bios[i];
 348
 349                 if (!sbio)
 350                         break;
 351                 kfree(sbio);
 352         }
 353
 354         scrub_free_csums(sctx);
 355         kfree(sctx);
 356 }
 357
 358 static noinline_for_stack
 359 struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 360 {
 361         struct scrub_ctx *sctx;
 362         int             i;
 363         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 364         int pages_per_rd_bio;
 365         int ret;
 366
 367         /*
 368          * the setting of pages_per_rd_bio is correct for scrub but might
 369          * be wrong for the dev_replace code where we might read from
 370          * different devices in the initial huge bios. However, that
 371          * code is able to correctly handle the case when adding a page
 372          * to a bio fails.
 373          */
 374         if (dev->bdev)
 375                 pages_per_rd_bio = min_t(int, SCRUB_PAGES_PER_RD_BIO,
 376                                          bio_get_nr_vecs(dev->bdev));
 377         else
 378                 pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 379         sctx = kzalloc(sizeof(*sctx), GFP_NOFS);
 380         if (!sctx)
 381                 goto nomem;
 382         sctx->is_dev_replace = is_dev_replace;
 383         sctx->pages_per_rd_bio = pages_per_rd_bio;
 384         sctx->curr = -1;
 385         sctx->dev_root = dev->dev_root;
 386         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 387                 struct scrub_bio *sbio;
 388
 389                 sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
 390                 if (!sbio)
 391                         goto nomem;
 392                 sctx->bios[i] = sbio;
 393
 394                 sbio->index = i;
 395                 sbio->sctx = sctx;
 396                 sbio->page_count = 0;
 397                 sbio->work.func = scrub_bio_end_io_worker;
 398
 399                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 400                         sctx->bios[i]->next_free = i + 1;
 401                 else
 402                         sctx->bios[i]->next_free = -1;
 403         }
 404         sctx->first_free = 0;
 405         sctx->nodesize = dev->dev_root->nodesize;
 406         sctx->leafsize = dev->dev_root->leafsize;
 407         sctx->sectorsize = dev->dev_root->sectorsize;
 408         atomic_set(&sctx->bios_in_flight, 0);
 409         atomic_set(&sctx->workers_pending, 0);
 410         atomic_set(&sctx->cancel_req, 0);
 411         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 412         INIT_LIST_HEAD(&sctx->csum_list);
 413
 414         spin_lock_init(&sctx->list_lock);
 415         spin_lock_init(&sctx->stat_lock);
 416         init_waitqueue_head(&sctx->list_wait);
 417
 418         ret = scrub_setup_wr_ctx(sctx, &sctx->wr_ctx, fs_info,
 419                                  fs_info->dev_replace.tgtdev, is_dev_replace);
 420         if (ret) {
 421                 scrub_free_ctx(sctx);
 422                 return ERR_PTR(ret);
 423         }
 424         return sctx;
 425
 426 nomem:
 427         scrub_free_ctx(sctx);
 428         return ERR_PTR(-ENOMEM);
 429 }
 430
 431 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 432                                      void *warn_ctx)
 433 {
 434         u64 isize;
 435         u32 nlink;
 436         int ret;
 437         int i;
 438         struct extent_buffer *eb;
 439         struct btrfs_inode_item *inode_item;
 440         struct scrub_warning *swarn = warn_ctx;
 441         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
 442         struct inode_fs_paths *ipath = NULL;
 443         struct btrfs_root *local_root;
 444         struct btrfs_key root_key;
 445
 446         root_key.objectid = root;
 447         root_key.type = BTRFS_ROOT_ITEM_KEY;
 448         root_key.offset = (u64)-1;
 449         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 450         if (IS_ERR(local_root)) {
 451                 ret = PTR_ERR(local_root);
 452                 goto err;
 453         }
 454
 455         ret = inode_item_info(inum, 0, local_root, swarn->path);
 456         if (ret) {
 457                 btrfs_release_path(swarn->path);
 458                 goto err;
 459         }
 460
 461         eb = swarn->path->nodes[0];
 462         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 463                                         struct btrfs_inode_item);
 464         isize = btrfs_inode_size(eb, inode_item);
 465         nlink = btrfs_inode_nlink(eb, inode_item);
 466         btrfs_release_path(swarn->path);
 467
 468         ipath = init_ipath(4096, local_root, swarn->path);
 469         if (IS_ERR(ipath)) {
 470                 ret = PTR_ERR(ipath);
 471                 ipath = NULL;
 472                 goto err;
 473         }
 474         ret = paths_from_inode(inum, ipath);
 475
 476         if (ret < 0)
 477                 goto err;
 478
 479         /*
 480          * we deliberately ignore the bit ipath might have been too small to
 481          * hold all of the paths here
 482          */
 483         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 484                 printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev "
 485                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
 486                         "length %llu, links %u (path: %s)\n", swarn->errstr,
 487                         swarn->logical, rcu_str_deref(swarn->dev->name),
 488                         (unsigned long long)swarn->sector, root, inum, offset,
 489                         min(isize - offset, (u64)PAGE_SIZE), nlink,
 490                         (char *)(unsigned long)ipath->fspath->val[i]);
 491
 492         free_ipath(ipath);
 493         return 0;
 494
 495 err:
 496         printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev "
 497                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
 498                 "resolving failed with ret=%d\n", swarn->errstr,
 499                 swarn->logical, rcu_str_deref(swarn->dev->name),
 500                 (unsigned long long)swarn->sector, root, inum, offset, ret);
 501
 502         free_ipath(ipath);
 503         return 0;
 504 }
 505
 506 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 507 {
 508         struct btrfs_device *dev;
 509         struct btrfs_fs_info *fs_info;
 510         struct btrfs_path *path;
 511         struct btrfs_key found_key;
 512         struct extent_buffer *eb;
 513         struct btrfs_extent_item *ei;
 514         struct scrub_warning swarn;
 515         unsigned long ptr = 0;
 516         u64 extent_item_pos;
 517         u64 flags = 0;
 518         u64 ref_root;
 519         u32 item_size;
 520         u8 ref_level;
 521         const int bufsize = 4096;
 522         int ret;
 523
 524         WARN_ON(sblock->page_count < 1);
 525         dev = sblock->pagev[0]->dev;
 526         fs_info = sblock->sctx->dev_root->fs_info;
 527
 528         path = btrfs_alloc_path();
 529
 530         swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
 531         swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
 532         swarn.sector = (sblock->pagev[0]->physical) >> 9;
 533         swarn.logical = sblock->pagev[0]->logical;
 534         swarn.errstr = errstr;
 535         swarn.dev = NULL;
 536         swarn.msg_bufsize = bufsize;
 537         swarn.scratch_bufsize = bufsize;
 538
 539         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
 540                 goto out;
 541
 542         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 543                                   &flags);
 544         if (ret < 0)
 545                 goto out;
 546
 547         extent_item_pos = swarn.logical - found_key.objectid;
 548         swarn.extent_item_size = found_key.offset;
 549
 550         eb = path->nodes[0];
 551         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 552         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 553
 554         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 555                 do {
 556                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
 557                                                         &ref_root, &ref_level);
 558                         printk_in_rcu(KERN_WARNING
 559                                 "btrfs: %s at logical %llu on dev %s, "
 560                                 "sector %llu: metadata %s (level %d) in tree "
 561                                 "%llu\n", errstr, swarn.logical,
 562                                 rcu_str_deref(dev->name),
 563                                 (unsigned long long)swarn.sector,
 564                                 ref_level ? "node" : "leaf",
 565                                 ret < 0 ? -1 : ref_level,
 566                                 ret < 0 ? -1 : ref_root);
 567                 } while (ret != 1);
 568                 btrfs_release_path(path);
 569         } else {
 570                 btrfs_release_path(path);
 571                 swarn.path = path;
 572                 swarn.dev = dev;
 573                 iterate_extent_inodes(fs_info, found_key.objectid,
 574                                         extent_item_pos, 1,
 575                                         scrub_print_warning_inode, &swarn);
 576         }
 577
 578 out:
 579         btrfs_free_path(path);
 580         kfree(swarn.scratch_buf);
 581         kfree(swarn.msg_buf);
 582 }
 583
 584 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
 585 {
 586         struct page *page = NULL;
 587         unsigned long index;
 588         struct scrub_fixup_nodatasum *fixup = fixup_ctx;
 589         int ret;
 590         int corrected = 0;
 591         struct btrfs_key key;
 592         struct inode *inode = NULL;
 593         struct btrfs_fs_info *fs_info;
 594         u64 end = offset + PAGE_SIZE - 1;
 595         struct btrfs_root *local_root;
 596         int srcu_index;
 597
 598         key.objectid = root;
 599         key.type = BTRFS_ROOT_ITEM_KEY;
 600         key.offset = (u64)-1;
 601
 602         fs_info = fixup->root->fs_info;
 603         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
 604
 605         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
 606         if (IS_ERR(local_root)) {
 607                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 608                 return PTR_ERR(local_root);
 609         }
 610
 611         key.type = BTRFS_INODE_ITEM_KEY;
 612         key.objectid = inum;
 613         key.offset = 0;
 614         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
 615         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 616         if (IS_ERR(inode))
 617                 return PTR_ERR(inode);
 618
 619         index = offset >> PAGE_CACHE_SHIFT;
 620
 621         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 622         if (!page) {
 623                 ret = -ENOMEM;
 624                 goto out;
 625         }
 626
 627         if (PageUptodate(page)) {
 628                 if (PageDirty(page)) {
 629                         /*
 630                          * we need to write the data to the defect sector. the
 631                          * data that was in that sector is not in memory,
 632                          * because the page was modified. we must not write the
 633                          * modified page to that sector.
 634                          *
 635                          * TODO: what could be done here: wait for the delalloc
 636                          *       runner to write out that page (might involve
 637                          *       COW) and see whether the sector is still
 638                          *       referenced afterwards.
 639                          *
 640                          * For the meantime, we'll treat this error
 641                          * incorrectable, although there is a chance that a
 642                          * later scrub will find the bad sector again and that
 643                          * there's no dirty page in memory, then.
 644                          */
 645                         ret = -EIO;
 646                         goto out;
 647                 }
 648                 fs_info = BTRFS_I(inode)->root->fs_info;
 649                 ret = repair_io_failure(fs_info, offset, PAGE_SIZE,
 650                                         fixup->logical, page,
 651                                         fixup->mirror_num);
 652                 unlock_page(page);
 653                 corrected = !ret;
 654         } else {
 655                 /*
 656                  * we need to get good data first. the general readpage path
 657                  * will call repair_io_failure for us, we just have to make
 658                  * sure we read the bad mirror.
 659                  */
 660                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 661                                         EXTENT_DAMAGED, GFP_NOFS);
 662                 if (ret) {
 663                         /* set_extent_bits should give proper error */
 664                         WARN_ON(ret > 0);
 665                         if (ret > 0)
 666                                 ret = -EFAULT;
 667                         goto out;
 668                 }
 669
 670                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 671                                                 btrfs_get_extent,
 672                                                 fixup->mirror_num);
 673                 wait_on_page_locked(page);
 674
 675                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 676                                                 end, EXTENT_DAMAGED, 0, NULL);
 677                 if (!corrected)
 678                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 679                                                 EXTENT_DAMAGED, GFP_NOFS);
 680         }
 681
 682 out:
 683         if (page)
 684                 put_page(page);
 685         if (inode)
 686                 iput(inode);
 687
 688         if (ret < 0)
 689                 return ret;
 690
 691         if (ret == 0 && corrected) {
 692                 /*
 693                  * we only need to call readpage for one of the inodes belonging
 694                  * to this extent. so make iterate_extent_inodes stop
 695                  */
 696                 return 1;
 697         }
 698
 699         return -EIO;
 700 }
 701
 702 static void scrub_fixup_nodatasum(struct btrfs_work *work)
 703 {
 704         int ret;
 705         struct scrub_fixup_nodatasum *fixup;
 706         struct scrub_ctx *sctx;
 707         struct btrfs_trans_handle *trans = NULL;
 708         struct btrfs_fs_info *fs_info;
 709         struct btrfs_path *path;
 710         int uncorrectable = 0;
 711
 712         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
 713         sctx = fixup->sctx;
 714         fs_info = fixup->root->fs_info;
 715
 716         path = btrfs_alloc_path();
 717         if (!path) {
 718                 spin_lock(&sctx->stat_lock);
 719                 ++sctx->stat.malloc_errors;
 720                 spin_unlock(&sctx->stat_lock);
 721                 uncorrectable = 1;
 722                 goto out;
 723         }
 724
 725         trans = btrfs_join_transaction(fixup->root);
 726         if (IS_ERR(trans)) {
 727                 uncorrectable = 1;
 728                 goto out;
 729         }
 730
 731         /*
 732          * the idea is to trigger a regular read through the standard path. we
 733          * read a page from the (failed) logical address by specifying the
 734          * corresponding copynum of the failed sector. thus, that readpage is
 735          * expected to fail.
 736          * that is the point where on-the-fly error correction will kick in
 737          * (once it's finished) and rewrite the failed sector if a good copy
 738          * can be found.
 739          */
 740         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
 741                                                 path, scrub_fixup_readpage,
 742                                                 fixup);
 743         if (ret < 0) {
 744                 uncorrectable = 1;
 745                 goto out;
 746         }
 747         WARN_ON(ret != 1);
 748
 749         spin_lock(&sctx->stat_lock);
 750         ++sctx->stat.corrected_errors;
 751         spin_unlock(&sctx->stat_lock);
 752
 753 out:
 754         if (trans && !IS_ERR(trans))
 755                 btrfs_end_transaction(trans, fixup->root);
 756         if (uncorrectable) {
 757                 spin_lock(&sctx->stat_lock);
 758                 ++sctx->stat.uncorrectable_errors;
 759                 spin_unlock(&sctx->stat_lock);
 760                 btrfs_dev_replace_stats_inc(
 761                         &sctx->dev_root->fs_info->dev_replace.
 762                         num_uncorrectable_read_errors);
 763                 printk_ratelimited_in_rcu(KERN_ERR
 764                         "btrfs: unable to fixup (nodatasum) error at logical %llu on dev %s\n",
 765                         fixup->logical, rcu_str_deref(fixup->dev->name));
 766         }
 767
 768         btrfs_free_path(path);
 769         kfree(fixup);
 770
 771         scrub_pending_trans_workers_dec(sctx);
 772 }
 773
 774 /*
 775  * scrub_handle_errored_block gets called when either verification of the
 776  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 777  * case, this function handles all pages in the bio, even though only one
 778  * may be bad.
 779  * The goal of this function is to repair the errored block by using the
 780  * contents of one of the mirrors.
 781  */
 782 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 783 {
 784         struct scrub_ctx *sctx = sblock_to_check->sctx;
 785         struct btrfs_device *dev;
 786         struct btrfs_fs_info *fs_info;
 787         u64 length;
 788         u64 logical;
 789         u64 generation;
 790         unsigned int failed_mirror_index;
 791         unsigned int is_metadata;
 792         unsigned int have_csum;
 793         u8 *csum;
 794         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 795         struct scrub_block *sblock_bad;
 796         int ret;
 797         int mirror_index;
 798         int page_num;
 799         int success;
 800         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 801                                       DEFAULT_RATELIMIT_BURST);
 802
 803         BUG_ON(sblock_to_check->page_count < 1);
 804         fs_info = sctx->dev_root->fs_info;
 805         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 806                 /*
 807                  * if we find an error in a super block, we just report it.
 808                  * They will get written with the next transaction commit
 809                  * anyway
 810                  */
 811                 spin_lock(&sctx->stat_lock);
 812                 ++sctx->stat.super_errors;
 813                 spin_unlock(&sctx->stat_lock);
 814                 return 0;
 815         }
 816         length = sblock_to_check->page_count * PAGE_SIZE;
 817         logical = sblock_to_check->pagev[0]->logical;
 818         generation = sblock_to_check->pagev[0]->generation;
 819         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 820         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 821         is_metadata = !(sblock_to_check->pagev[0]->flags &
 822                         BTRFS_EXTENT_FLAG_DATA);
 823         have_csum = sblock_to_check->pagev[0]->have_csum;
 824         csum = sblock_to_check->pagev[0]->csum;
 825         dev = sblock_to_check->pagev[0]->dev;
 826
 827         if (sctx->is_dev_replace && !is_metadata && !have_csum) {
 828                 sblocks_for_recheck = NULL;
 829                 goto nodatasum_case;
 830         }
 831
 832         /*
 833          * read all mirrors one after the other. This includes to
 834          * re-read the extent or metadata block that failed (that was
 835          * the cause that this fixup code is called) another time,
 836          * page by page this time in order to know which pages
 837          * caused I/O errors and which ones are good (for all mirrors).
 838          * It is the goal to handle the situation when more than one
 839          * mirror contains I/O errors, but the errors do not
 840          * overlap, i.e. the data can be repaired by selecting the
 841          * pages from those mirrors without I/O error on the
 842          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 843          * would be that mirror #1 has an I/O error on the first page,
 844          * the second page is good, and mirror #2 has an I/O error on
 845          * the second page, but the first page is good.
 846          * Then the first page of the first mirror can be repaired by
 847          * taking the first page of the second mirror, and the
 848          * second page of the second mirror can be repaired by
 849          * copying the contents of the 2nd page of the 1st mirror.
 850          * One more note: if the pages of one mirror contain I/O
 851          * errors, the checksum cannot be verified. In order to get
 852          * the best data for repairing, the first attempt is to find
 853          * a mirror without I/O errors and with a validated checksum.
 854          * Only if this is not possible, the pages are picked from
 855          * mirrors with I/O errors without considering the checksum.
 856          * If the latter is the case, at the end, the checksum of the
 857          * repaired area is verified in order to correctly maintain
 858          * the statistics.
 859          */
 860
 861         sblocks_for_recheck = kzalloc(BTRFS_MAX_MIRRORS *
 862                                      sizeof(*sblocks_for_recheck),
 863                                      GFP_NOFS);
 864         if (!sblocks_for_recheck) {
 865                 spin_lock(&sctx->stat_lock);
 866                 sctx->stat.malloc_errors++;
 867                 sctx->stat.read_errors++;
 868                 sctx->stat.uncorrectable_errors++;
 869                 spin_unlock(&sctx->stat_lock);
 870                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 871                 goto out;
 872         }
 873
 874         /* setup the context, map the logical blocks and alloc the pages */
 875         ret = scrub_setup_recheck_block(sctx, fs_info, sblock_to_check, length,
 876                                         logical, sblocks_for_recheck);
 877         if (ret) {
 878                 spin_lock(&sctx->stat_lock);
 879                 sctx->stat.read_errors++;
 880                 sctx->stat.uncorrectable_errors++;
 881                 spin_unlock(&sctx->stat_lock);
 882                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 883                 goto out;
 884         }
 885         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 886         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 887
 888         /* build and submit the bios for the failed mirror, check checksums */
 889         scrub_recheck_block(fs_info, sblock_bad, is_metadata, have_csum,
 890                             csum, generation, sctx->csum_size);
 891
 892         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 893             sblock_bad->no_io_error_seen) {
 894                 /*
 895                  * the error disappeared after reading page by page, or
 896                  * the area was part of a huge bio and other parts of the
 897                  * bio caused I/O errors, or the block layer merged several
 898                  * read requests into one and the error is caused by a
 899                  * different bio (usually one of the two latter cases is
 900                  * the cause)
 901                  */
 902                 spin_lock(&sctx->stat_lock);
 903                 sctx->stat.unverified_errors++;
 904                 spin_unlock(&sctx->stat_lock);
 905
 906                 if (sctx->is_dev_replace)
 907                         scrub_write_block_to_dev_replace(sblock_bad);
 908                 goto out;
 909         }
 910
 911         if (!sblock_bad->no_io_error_seen) {
 912                 spin_lock(&sctx->stat_lock);
 913                 sctx->stat.read_errors++;
 914                 spin_unlock(&sctx->stat_lock);
 915                 if (__ratelimit(&_rs))
 916                         scrub_print_warning("i/o error", sblock_to_check);
 917                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 918         } else if (sblock_bad->checksum_error) {
 919                 spin_lock(&sctx->stat_lock);
 920                 sctx->stat.csum_errors++;
 921                 spin_unlock(&sctx->stat_lock);
 922                 if (__ratelimit(&_rs))
 923                         scrub_print_warning("checksum error", sblock_to_check);
 924                 btrfs_dev_stat_inc_and_print(dev,
 925                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
 926         } else if (sblock_bad->header_error) {
 927                 spin_lock(&sctx->stat_lock);
 928                 sctx->stat.verify_errors++;
 929                 spin_unlock(&sctx->stat_lock);
 930                 if (__ratelimit(&_rs))
 931                         scrub_print_warning("checksum/header error",
 932                                             sblock_to_check);
 933                 if (sblock_bad->generation_error)
 934                         btrfs_dev_stat_inc_and_print(dev,
 935                                 BTRFS_DEV_STAT_GENERATION_ERRS);
 936                 else
 937                         btrfs_dev_stat_inc_and_print(dev,
 938                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
 939         }
 940
 941         if (sctx->readonly && !sctx->is_dev_replace)
 942                 goto did_not_correct_error;
 943
 944         if (!is_metadata && !have_csum) {
 945                 struct scrub_fixup_nodatasum *fixup_nodatasum;
 946
 947 nodatasum_case:
 948                 WARN_ON(sctx->is_dev_replace);
 949
 950                 /*
 951                  * !is_metadata and !have_csum, this means that the data
 952                  * might not be COW'ed, that it might be modified
 953                  * concurrently. The general strategy to work on the
 954                  * commit root does not help in the case when COW is not
 955                  * used.
 956                  */
 957                 fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum), GFP_NOFS);
 958                 if (!fixup_nodatasum)
 959                         goto did_not_correct_error;
 960                 fixup_nodatasum->sctx = sctx;
 961                 fixup_nodatasum->dev = dev;
 962                 fixup_nodatasum->logical = logical;
 963                 fixup_nodatasum->root = fs_info->extent_root;
 964                 fixup_nodatasum->mirror_num = failed_mirror_index + 1;
 965                 scrub_pending_trans_workers_inc(sctx);
 966                 fixup_nodatasum->work.func = scrub_fixup_nodatasum;
 967                 btrfs_queue_worker(&fs_info->scrub_workers,
 968                                    &fixup_nodatasum->work);
 969                 goto out;
 970         }
 971
 972         /*
 973          * now build and submit the bios for the other mirrors, check
 974          * checksums.
 975          * First try to pick the mirror which is completely without I/O
 976          * errors and also does not have a checksum error.
 977          * If one is found, and if a checksum is present, the full block
 978          * that is known to contain an error is rewritten. Afterwards
 979          * the block is known to be corrected.
 980          * If a mirror is found which is completely correct, and no
 981          * checksum is present, only those pages are rewritten that had
 982          * an I/O error in the block to be repaired, since it cannot be
 983          * determined, which copy of the other pages is better (and it
 984          * could happen otherwise that a correct page would be
 985          * overwritten by a bad one).
 986          */
 987         for (mirror_index = 0;
 988              mirror_index < BTRFS_MAX_MIRRORS &&
 989              sblocks_for_recheck[mirror_index].page_count > 0;
 990              mirror_index++) {
 991                 struct scrub_block *sblock_other;
 992
 993                 if (mirror_index == failed_mirror_index)
 994                         continue;
 995                 sblock_other = sblocks_for_recheck + mirror_index;
 996
 997                 /* build and submit the bios, check checksums */
 998                 scrub_recheck_block(fs_info, sblock_other, is_metadata,
 999                                     have_csum, csum, generation,
1000                                     sctx->csum_size);
1001
1002                 if (!sblock_other->header_error &&
1003                     !sblock_other->checksum_error &&
1004                     sblock_other->no_io_error_seen) {
1005                         if (sctx->is_dev_replace) {
1006                                 scrub_write_block_to_dev_replace(sblock_other);
1007                         } else {
1008                                 int force_write = is_metadata || have_csum;
1009
1010                                 ret = scrub_repair_block_from_good_copy(
1011                                                 sblock_bad, sblock_other,
1012                                                 force_write);
1013                         }
1014                         if (0 == ret)
1015                                 goto corrected_error;
1016                 }
1017         }
1018
1019         /*
1020          * for dev_replace, pick good pages and write to the target device.
1021          */
1022         if (sctx->is_dev_replace) {
1023                 success = 1;
1024                 for (page_num = 0; page_num < sblock_bad->page_count;
1025                      page_num++) {
1026                         int sub_success;
1027
1028                         sub_success = 0;
1029                         for (mirror_index = 0;
1030                              mirror_index < BTRFS_MAX_MIRRORS &&
1031                              sblocks_for_recheck[mirror_index].page_count > 0;
1032                              mirror_index++) {
1033                                 struct scrub_block *sblock_other =
1034                                         sblocks_for_recheck + mirror_index;
1035                                 struct scrub_page *page_other =
1036                                         sblock_other->pagev[page_num];
1037
1038                                 if (!page_other->io_error) {
1039                                         ret = scrub_write_page_to_dev_replace(
1040                                                         sblock_other, page_num);
1041                                         if (ret == 0) {
1042                                                 /* succeeded for this page */
1043                                                 sub_success = 1;
1044                                                 break;
1045                                         } else {
1046                                                 btrfs_dev_replace_stats_inc(
1047                                                         &sctx->dev_root->
1048                                                         fs_info->dev_replace.
1049                                                         num_write_errors);
1050                                         }
1051                                 }
1052                         }
1053
1054                         if (!sub_success) {
1055                                 /*
1056                                  * did not find a mirror to fetch the page
1057                                  * from. scrub_write_page_to_dev_replace()
1058                                  * handles this case (page->io_error), by
1059                                  * filling the block with zeros before
1060                                  * submitting the write request
1061                                  */
1062                                 success = 0;
1063                                 ret = scrub_write_page_to_dev_replace(
1064                                                 sblock_bad, page_num);
1065                                 if (ret)
1066                                         btrfs_dev_replace_stats_inc(
1067                                                 &sctx->dev_root->fs_info->
1068                                                 dev_replace.num_write_errors);
1069                         }
1070                 }
1071
1072                 goto out;
1073         }
1074
1075         /*
1076          * for regular scrub, repair those pages that are errored.
1077          * In case of I/O errors in the area that is supposed to be
1078          * repaired, continue by picking good copies of those pages.
1079          * Select the good pages from mirrors to rewrite bad pages from
1080          * the area to fix. Afterwards verify the checksum of the block
1081          * that is supposed to be repaired. This verification step is
1082          * only done for the purpose of statistic counting and for the
1083          * final scrub report, whether errors remain.
1084          * A perfect algorithm could make use of the checksum and try
1085          * all possible combinations of pages from the different mirrors
1086          * until the checksum verification succeeds. For example, when
1087          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1088          * of mirror #2 is readable but the final checksum test fails,
1089          * then the 2nd page of mirror #3 could be tried, whether now
1090          * the final checksum succeedes. But this would be a rare
1091          * exception and is therefore not implemented. At least it is
1092          * avoided that the good copy is overwritten.
1093          * A more useful improvement would be to pick the sectors
1094          * without I/O error based on sector sizes (512 bytes on legacy
1095          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1096          * mirror could be repaired by taking 512 byte of a different
1097          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1098          * area are unreadable.
1099          */
1100
1101         /* can only fix I/O errors from here on */
1102         if (sblock_bad->no_io_error_seen)
1103                 goto did_not_correct_error;
1104
1105         success = 1;
1106         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1107                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1108
1109                 if (!page_bad->io_error)
1110                         continue;
1111
1112                 for (mirror_index = 0;
1113                      mirror_index < BTRFS_MAX_MIRRORS &&
1114                      sblocks_for_recheck[mirror_index].page_count > 0;
1115                      mirror_index++) {
1116                         struct scrub_block *sblock_other = sblocks_for_recheck +
1117                                                            mirror_index;
1118                         struct scrub_page *page_other = sblock_other->pagev[
1119                                                         page_num];
1120
1121                         if (!page_other->io_error) {
1122                                 ret = scrub_repair_page_from_good_copy(
1123                                         sblock_bad, sblock_other, page_num, 0);
1124                                 if (0 == ret) {
1125                                         page_bad->io_error = 0;
1126                                         break; /* succeeded for this page */
1127                                 }
1128                         }
1129                 }
1130
1131                 if (page_bad->io_error) {
1132                         /* did not find a mirror to copy the page from */
1133                         success = 0;
1134                 }
1135         }
1136
1137         if (success) {
1138                 if (is_metadata || have_csum) {
1139                         /*
1140                          * need to verify the checksum now that all
1141                          * sectors on disk are repaired (the write
1142                          * request for data to be repaired is on its way).
1143                          * Just be lazy and use scrub_recheck_block()
1144                          * which re-reads the data before the checksum
1145                          * is verified, but most likely the data comes out
1146                          * of the page cache.
1147                          */
1148                         scrub_recheck_block(fs_info, sblock_bad,
1149                                             is_metadata, have_csum, csum,
1150                                             generation, sctx->csum_size);
1151                         if (!sblock_bad->header_error &&
1152                             !sblock_bad->checksum_error &&
1153                             sblock_bad->no_io_error_seen)
1154                                 goto corrected_error;
1155                         else
1156                                 goto did_not_correct_error;
1157                 } else {
1158 corrected_error:
1159                         spin_lock(&sctx->stat_lock);
1160                         sctx->stat.corrected_errors++;
1161                         spin_unlock(&sctx->stat_lock);
1162                         printk_ratelimited_in_rcu(KERN_ERR
1163                                 "btrfs: fixed up error at logical %llu on dev %s\n",
1164                                 logical, rcu_str_deref(dev->name));
1165                 }
1166         } else {
1167 did_not_correct_error:
1168                 spin_lock(&sctx->stat_lock);
1169                 sctx->stat.uncorrectable_errors++;
1170                 spin_unlock(&sctx->stat_lock);
1171                 printk_ratelimited_in_rcu(KERN_ERR
1172                         "btrfs: unable to fixup (regular) error at logical %llu on dev %s\n",
1173                         logical, rcu_str_deref(dev->name));
1174         }
1175
1176 out:
1177         if (sblocks_for_recheck) {
1178                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1179                      mirror_index++) {
1180                         struct scrub_block *sblock = sblocks_for_recheck +
1181                                                      mirror_index;
1182                         int page_index;
1183
1184                         for (page_index = 0; page_index < sblock->page_count;
1185                              page_index++) {
1186                                 sblock->pagev[page_index]->sblock = NULL;
1187                                 scrub_page_put(sblock->pagev[page_index]);
1188                         }
1189                 }
1190                 kfree(sblocks_for_recheck);
1191         }
1192
1193         return 0;
1194 }
1195
1196 static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
1197                                      struct btrfs_fs_info *fs_info,
1198                                      struct scrub_block *original_sblock,
1199                                      u64 length, u64 logical,
1200                                      struct scrub_block *sblocks_for_recheck)
1201 {
1202         int page_index;
1203         int mirror_index;
1204         int ret;
1205
1206         /*
1207          * note: the two members ref_count and outstanding_pages
1208          * are not used (and not set) in the blocks that are used for
1209          * the recheck procedure
1210          */
1211
1212         page_index = 0;
1213         while (length > 0) {
1214                 u64 sublen = min_t(u64, length, PAGE_SIZE);
1215                 u64 mapped_length = sublen;
1216                 struct btrfs_bio *bbio = NULL;
1217
1218                 /*
1219                  * with a length of PAGE_SIZE, each returned stripe
1220                  * represents one mirror
1221                  */
1222                 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical,
1223                                       &mapped_length, &bbio, 0);
1224                 if (ret || !bbio || mapped_length < sublen) {
1225                         kfree(bbio);
1226                         return -EIO;
1227                 }
1228
1229                 BUG_ON(page_index >= SCRUB_PAGES_PER_RD_BIO);
1230                 for (mirror_index = 0; mirror_index < (int)bbio->num_stripes;
1231                      mirror_index++) {
1232                         struct scrub_block *sblock;
1233                         struct scrub_page *page;
1234
1235                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1236                                 continue;
1237
1238                         sblock = sblocks_for_recheck + mirror_index;
1239                         sblock->sctx = sctx;
1240                         page = kzalloc(sizeof(*page), GFP_NOFS);
1241                         if (!page) {
1242 leave_nomem:
1243                                 spin_lock(&sctx->stat_lock);
1244                                 sctx->stat.malloc_errors++;
1245                                 spin_unlock(&sctx->stat_lock);
1246                                 kfree(bbio);
1247                                 return -ENOMEM;
1248                         }
1249                         scrub_page_get(page);
1250                         sblock->pagev[page_index] = page;
1251                         page->logical = logical;
1252                         page->physical = bbio->stripes[mirror_index].physical;
1253                         BUG_ON(page_index >= original_sblock->page_count);
1254                         page->physical_for_dev_replace =
1255                                 original_sblock->pagev[page_index]->
1256                                 physical_for_dev_replace;
1257                         /* for missing devices, dev->bdev is NULL */
1258                         page->dev = bbio->stripes[mirror_index].dev;
1259                         page->mirror_num = mirror_index + 1;
1260                         sblock->page_count++;
1261                         page->page = alloc_page(GFP_NOFS);
1262                         if (!page->page)
1263                                 goto leave_nomem;
1264                 }
1265                 kfree(bbio);
1266                 length -= sublen;
1267                 logical += sublen;
1268                 page_index++;
1269         }
1270
1271         return 0;
1272 }
1273
1274 /*
1275  * this function will check the on disk data for checksum errors, header
1276  * errors and read I/O errors. If any I/O errors happen, the exact pages
1277  * which are errored are marked as being bad. The goal is to enable scrub
1278  * to take those pages that are not errored from all the mirrors so that
1279  * the pages that are errored in the just handled mirror can be repaired.
1280  */
1281 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1282                                 struct scrub_block *sblock, int is_metadata,
1283                                 int have_csum, u8 *csum, u64 generation,
1284                                 u16 csum_size)
1285 {
1286         int page_num;
1287
1288         sblock->no_io_error_seen = 1;
1289         sblock->header_error = 0;
1290         sblock->checksum_error = 0;
1291
1292         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1293                 struct bio *bio;
1294                 struct scrub_page *page = sblock->pagev[page_num];
1295                 DECLARE_COMPLETION_ONSTACK(complete);
1296
1297                 if (page->dev->bdev == NULL) {
1298                         page->io_error = 1;
1299                         sblock->no_io_error_seen = 0;
1300                         continue;
1301                 }
1302
1303                 WARN_ON(!page->page);
1304                 bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1305                 if (!bio) {
1306                         page->io_error = 1;
1307                         sblock->no_io_error_seen = 0;
1308                         continue;
1309                 }
1310                 bio->bi_bdev = page->dev->bdev;
1311                 bio->bi_sector = page->physical >> 9;
1312                 bio->bi_end_io = scrub_complete_bio_end_io;
1313                 bio->bi_private = &complete;
1314
1315                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1316                 btrfsic_submit_bio(READ, bio);
1317
1318                 /* this will also unplug the queue */
1319                 wait_for_completion(&complete);
1320
1321                 page->io_error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
1322                 if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1323                         sblock->no_io_error_seen = 0;
1324                 bio_put(bio);
1325         }
1326
1327         if (sblock->no_io_error_seen)
1328                 scrub_recheck_block_checksum(fs_info, sblock, is_metadata,
1329                                              have_csum, csum, generation,
1330                                              csum_size);
1331
1332         return;
1333 }
1334
1335 static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
1336                                          struct scrub_block *sblock,
1337                                          int is_metadata, int have_csum,
1338                                          const u8 *csum, u64 generation,
1339                                          u16 csum_size)
1340 {
1341         int page_num;
1342         u8 calculated_csum[BTRFS_CSUM_SIZE];
1343         u32 crc = ~(u32)0;
1344         void *mapped_buffer;
1345
1346         WARN_ON(!sblock->pagev[0]->page);
1347         if (is_metadata) {
1348                 struct btrfs_header *h;
1349
1350                 mapped_buffer = kmap_atomic(sblock->pagev[0]->page);
1351                 h = (struct btrfs_header *)mapped_buffer;
1352
1353                 if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h) ||
1354                     memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE) ||
1355                     memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1356                            BTRFS_UUID_SIZE)) {
1357                         sblock->header_error = 1;
1358                 } else if (generation != btrfs_stack_header_generation(h)) {
1359                         sblock->header_error = 1;
1360                         sblock->generation_error = 1;
1361                 }
1362                 csum = h->csum;
1363         } else {
1364                 if (!have_csum)
1365                         return;
1366
1367                 mapped_buffer = kmap_atomic(sblock->pagev[0]->page);
1368         }
1369
1370         for (page_num = 0;;) {
1371                 if (page_num == 0 && is_metadata)
1372                         crc = btrfs_csum_data(
1373                                 ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE,
1374                                 crc, PAGE_SIZE - BTRFS_CSUM_SIZE);
1375                 else
1376                         crc = btrfs_csum_data(mapped_buffer, crc, PAGE_SIZE);
1377
1378                 kunmap_atomic(mapped_buffer);
1379                 page_num++;
1380                 if (page_num >= sblock->page_count)
1381                         break;
1382                 WARN_ON(!sblock->pagev[page_num]->page);
1383
1384                 mapped_buffer = kmap_atomic(sblock->pagev[page_num]->page);
1385         }
1386
1387         btrfs_csum_final(crc, calculated_csum);
1388         if (memcmp(calculated_csum, csum, csum_size))
1389                 sblock->checksum_error = 1;
1390 }
1391
1392 static void scrub_complete_bio_end_io(struct bio *bio, int err)
1393 {
1394         complete((struct completion *)bio->bi_private);
1395 }
1396
1397 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1398                                              struct scrub_block *sblock_good,
1399                                              int force_write)
1400 {
1401         int page_num;
1402         int ret = 0;
1403
1404         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1405                 int ret_sub;
1406
1407                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1408                                                            sblock_good,
1409                                                            page_num,
1410                                                            force_write);
1411                 if (ret_sub)
1412                         ret = ret_sub;
1413         }
1414
1415         return ret;
1416 }
1417
1418 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1419                                             struct scrub_block *sblock_good,
1420                                             int page_num, int force_write)
1421 {
1422         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1423         struct scrub_page *page_good = sblock_good->pagev[page_num];
1424
1425         BUG_ON(page_bad->page == NULL);
1426         BUG_ON(page_good->page == NULL);
1427         if (force_write || sblock_bad->header_error ||
1428             sblock_bad->checksum_error || page_bad->io_error) {
1429                 struct bio *bio;
1430                 int ret;
1431                 DECLARE_COMPLETION_ONSTACK(complete);
1432
1433                 if (!page_bad->dev->bdev) {
1434                         printk_ratelimited(KERN_WARNING
1435                                 "btrfs: scrub_repair_page_from_good_copy(bdev == NULL) is unexpected!\n");
1436                         return -EIO;
1437                 }
1438
1439                 bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1440                 if (!bio)
1441                         return -EIO;
1442                 bio->bi_bdev = page_bad->dev->bdev;
1443                 bio->bi_sector = page_bad->physical >> 9;
1444                 bio->bi_end_io = scrub_complete_bio_end_io;
1445                 bio->bi_private = &complete;
1446
1447                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1448                 if (PAGE_SIZE != ret) {
1449                         bio_put(bio);
1450                         return -EIO;
1451                 }
1452                 btrfsic_submit_bio(WRITE, bio);
1453
1454                 /* this will also unplug the queue */
1455                 wait_for_completion(&complete);
1456                 if (!bio_flagged(bio, BIO_UPTODATE)) {
1457                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1458                                 BTRFS_DEV_STAT_WRITE_ERRS);
1459                         btrfs_dev_replace_stats_inc(
1460                                 &sblock_bad->sctx->dev_root->fs_info->
1461                                 dev_replace.num_write_errors);
1462                         bio_put(bio);
1463                         return -EIO;
1464                 }
1465                 bio_put(bio);
1466         }
1467
1468         return 0;
1469 }
1470
1471 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1472 {
1473         int page_num;
1474
1475         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1476                 int ret;
1477
1478                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1479                 if (ret)
1480                         btrfs_dev_replace_stats_inc(
1481                                 &sblock->sctx->dev_root->fs_info->dev_replace.
1482                                 num_write_errors);
1483         }
1484 }
1485
1486 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1487                                            int page_num)
1488 {
1489         struct scrub_page *spage = sblock->pagev[page_num];
1490
1491         BUG_ON(spage->page == NULL);
1492         if (spage->io_error) {
1493                 void *mapped_buffer = kmap_atomic(spage->page);
1494
1495                 memset(mapped_buffer, 0, PAGE_CACHE_SIZE);
1496                 flush_dcache_page(spage->page);
1497                 kunmap_atomic(mapped_buffer);
1498         }
1499         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1500 }
1501
1502 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1503                                     struct scrub_page *spage)
1504 {
1505         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1506         struct scrub_bio *sbio;
1507         int ret;
1508
1509         mutex_lock(&wr_ctx->wr_lock);
1510 again:
1511         if (!wr_ctx->wr_curr_bio) {
1512                 wr_ctx->wr_curr_bio = kzalloc(sizeof(*wr_ctx->wr_curr_bio),
1513                                               GFP_NOFS);
1514                 if (!wr_ctx->wr_curr_bio) {
1515                         mutex_unlock(&wr_ctx->wr_lock);
1516                         return -ENOMEM;
1517                 }
1518                 wr_ctx->wr_curr_bio->sctx = sctx;
1519                 wr_ctx->wr_curr_bio->page_count = 0;
1520         }
1521         sbio = wr_ctx->wr_curr_bio;
1522         if (sbio->page_count == 0) {
1523                 struct bio *bio;
1524
1525                 sbio->physical = spage->physical_for_dev_replace;
1526                 sbio->logical = spage->logical;
1527                 sbio->dev = wr_ctx->tgtdev;
1528                 bio = sbio->bio;
1529                 if (!bio) {
1530                         bio = btrfs_io_bio_alloc(GFP_NOFS, wr_ctx->pages_per_wr_bio);
1531                         if (!bio) {
1532                                 mutex_unlock(&wr_ctx->wr_lock);
1533                                 return -ENOMEM;
1534                         }
1535                         sbio->bio = bio;
1536                 }
1537
1538                 bio->bi_private = sbio;
1539                 bio->bi_end_io = scrub_wr_bio_end_io;
1540                 bio->bi_bdev = sbio->dev->bdev;
1541                 bio->bi_sector = sbio->physical >> 9;
1542                 sbio->err = 0;
1543         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1544                    spage->physical_for_dev_replace ||
1545                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1546                    spage->logical) {
1547                 scrub_wr_submit(sctx);
1548                 goto again;
1549         }
1550
1551         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1552         if (ret != PAGE_SIZE) {
1553                 if (sbio->page_count < 1) {
1554                         bio_put(sbio->bio);
1555                         sbio->bio = NULL;
1556                         mutex_unlock(&wr_ctx->wr_lock);
1557                         return -EIO;
1558                 }
1559                 scrub_wr_submit(sctx);
1560                 goto again;
1561         }
1562
1563         sbio->pagev[sbio->page_count] = spage;
1564         scrub_page_get(spage);
1565         sbio->page_count++;
1566         if (sbio->page_count == wr_ctx->pages_per_wr_bio)
1567                 scrub_wr_submit(sctx);
1568         mutex_unlock(&wr_ctx->wr_lock);
1569
1570         return 0;
1571 }
1572
1573 static void scrub_wr_submit(struct scrub_ctx *sctx)
1574 {
1575         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1576         struct scrub_bio *sbio;
1577
1578         if (!wr_ctx->wr_curr_bio)
1579                 return;
1580
1581         sbio = wr_ctx->wr_curr_bio;
1582         wr_ctx->wr_curr_bio = NULL;
1583         WARN_ON(!sbio->bio->bi_bdev);
1584         scrub_pending_bio_inc(sctx);
1585         /* process all writes in a single worker thread. Then the block layer
1586          * orders the requests before sending them to the driver which
1587          * doubled the write performance on spinning disks when measured
1588          * with Linux 3.5 */
1589         btrfsic_submit_bio(WRITE, sbio->bio);
1590 }
1591
1592 static void scrub_wr_bio_end_io(struct bio *bio, int err)
1593 {
1594         struct scrub_bio *sbio = bio->bi_private;
1595         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
1596
1597         sbio->err = err;
1598         sbio->bio = bio;
1599
1600         sbio->work.func = scrub_wr_bio_end_io_worker;
1601         btrfs_queue_worker(&fs_info->scrub_wr_completion_workers, &sbio->work);
1602 }
1603
1604 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1605 {
1606         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1607         struct scrub_ctx *sctx = sbio->sctx;
1608         int i;
1609
1610         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1611         if (sbio->err) {
1612                 struct btrfs_dev_replace *dev_replace =
1613                         &sbio->sctx->dev_root->fs_info->dev_replace;
1614
1615                 for (i = 0; i < sbio->page_count; i++) {
1616                         struct scrub_page *spage = sbio->pagev[i];
1617
1618                         spage->io_error = 1;
1619                         btrfs_dev_replace_stats_inc(&dev_replace->
1620                                                     num_write_errors);
1621                 }
1622         }
1623
1624         for (i = 0; i < sbio->page_count; i++)
1625                 scrub_page_put(sbio->pagev[i]);
1626
1627         bio_put(sbio->bio);
1628         kfree(sbio);
1629         scrub_pending_bio_dec(sctx);
1630 }
1631
1632 static int scrub_checksum(struct scrub_block *sblock)
1633 {
1634         u64 flags;
1635         int ret;
1636
1637         WARN_ON(sblock->page_count < 1);
1638         flags = sblock->pagev[0]->flags;
1639         ret = 0;
1640         if (flags & BTRFS_EXTENT_FLAG_DATA)
1641                 ret = scrub_checksum_data(sblock);
1642         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1643                 ret = scrub_checksum_tree_block(sblock);
1644         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1645                 (void)scrub_checksum_super(sblock);
1646         else
1647                 WARN_ON(1);
1648         if (ret)
1649                 scrub_handle_errored_block(sblock);
1650
1651         return ret;
1652 }
1653
1654 static int scrub_checksum_data(struct scrub_block *sblock)
1655 {
1656         struct scrub_ctx *sctx = sblock->sctx;
1657         u8 csum[BTRFS_CSUM_SIZE];
1658         u8 *on_disk_csum;
1659         struct page *page;
1660         void *buffer;
1661         u32 crc = ~(u32)0;
1662         int fail = 0;
1663         u64 len;
1664         int index;
1665
1666         BUG_ON(sblock->page_count < 1);
1667         if (!sblock->pagev[0]->have_csum)
1668                 return 0;
1669
1670         on_disk_csum = sblock->pagev[0]->csum;
1671         page = sblock->pagev[0]->page;
1672         buffer = kmap_atomic(page);
1673
1674         len = sctx->sectorsize;
1675         index = 0;
1676         for (;;) {
1677                 u64 l = min_t(u64, len, PAGE_SIZE);
1678
1679                 crc = btrfs_csum_data(buffer, crc, l);
1680                 kunmap_atomic(buffer);
1681                 len -= l;
1682                 if (len == 0)
1683                         break;
1684                 index++;
1685                 BUG_ON(index >= sblock->page_count);
1686                 BUG_ON(!sblock->pagev[index]->page);
1687                 page = sblock->pagev[index]->page;
1688                 buffer = kmap_atomic(page);
1689         }
1690
1691         btrfs_csum_final(crc, csum);
1692         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1693                 fail = 1;
1694
1695         return fail;
1696 }
1697
1698 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1699 {
1700         struct scrub_ctx *sctx = sblock->sctx;
1701         struct btrfs_header *h;
1702         struct btrfs_root *root = sctx->dev_root;
1703         struct btrfs_fs_info *fs_info = root->fs_info;
1704         u8 calculated_csum[BTRFS_CSUM_SIZE];
1705         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1706         struct page *page;
1707         void *mapped_buffer;
1708         u64 mapped_size;
1709         void *p;
1710         u32 crc = ~(u32)0;
1711         int fail = 0;
1712         int crc_fail = 0;
1713         u64 len;
1714         int index;
1715
1716         BUG_ON(sblock->page_count < 1);
1717         page = sblock->pagev[0]->page;
1718         mapped_buffer = kmap_atomic(page);
1719         h = (struct btrfs_header *)mapped_buffer;
1720         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1721
1722         /*
1723          * we don't use the getter functions here, as we
1724          * a) don't have an extent buffer and
1725          * b) the page is already kmapped
1726          */
1727
1728         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1729                 ++fail;
1730
1731         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h))
1732                 ++fail;
1733
1734         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
1735                 ++fail;
1736
1737         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1738                    BTRFS_UUID_SIZE))
1739                 ++fail;
1740
1741         WARN_ON(sctx->nodesize != sctx->leafsize);
1742         len = sctx->nodesize - BTRFS_CSUM_SIZE;
1743         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1744         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1745         index = 0;
1746         for (;;) {
1747                 u64 l = min_t(u64, len, mapped_size);
1748
1749                 crc = btrfs_csum_data(p, crc, l);
1750                 kunmap_atomic(mapped_buffer);
1751                 len -= l;
1752                 if (len == 0)
1753                         break;
1754                 index++;
1755                 BUG_ON(index >= sblock->page_count);
1756                 BUG_ON(!sblock->pagev[index]->page);
1757                 page = sblock->pagev[index]->page;
1758                 mapped_buffer = kmap_atomic(page);
1759                 mapped_size = PAGE_SIZE;
1760                 p = mapped_buffer;
1761         }
1762
1763         btrfs_csum_final(crc, calculated_csum);
1764         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1765                 ++crc_fail;
1766
1767         return fail || crc_fail;
1768 }
1769
1770 static int scrub_checksum_super(struct scrub_block *sblock)
1771 {
1772         struct btrfs_super_block *s;
1773         struct scrub_ctx *sctx = sblock->sctx;
1774         struct btrfs_root *root = sctx->dev_root;
1775         struct btrfs_fs_info *fs_info = root->fs_info;
1776         u8 calculated_csum[BTRFS_CSUM_SIZE];
1777         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1778         struct page *page;
1779         void *mapped_buffer;
1780         u64 mapped_size;
1781         void *p;
1782         u32 crc = ~(u32)0;
1783         int fail_gen = 0;
1784         int fail_cor = 0;
1785         u64 len;
1786         int index;
1787
1788         BUG_ON(sblock->page_count < 1);
1789         page = sblock->pagev[0]->page;
1790         mapped_buffer = kmap_atomic(page);
1791         s = (struct btrfs_super_block *)mapped_buffer;
1792         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1793
1794         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1795                 ++fail_cor;
1796
1797         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1798                 ++fail_gen;
1799
1800         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
1801                 ++fail_cor;
1802
1803         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1804         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1805         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1806         index = 0;
1807         for (;;) {
1808                 u64 l = min_t(u64, len, mapped_size);
1809
1810                 crc = btrfs_csum_data(p, crc, l);
1811                 kunmap_atomic(mapped_buffer);
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                 mapped_buffer = kmap_atomic(page);
1820                 mapped_size = PAGE_SIZE;
1821                 p = mapped_buffer;
1822         }
1823
1824         btrfs_csum_final(crc, calculated_csum);
1825         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1826                 ++fail_cor;
1827
1828         if (fail_cor + fail_gen) {
1829                 /*
1830                  * if we find an error in a super block, we just report it.
1831                  * They will get written with the next transaction commit
1832                  * anyway
1833                  */
1834                 spin_lock(&sctx->stat_lock);
1835                 ++sctx->stat.super_errors;
1836                 spin_unlock(&sctx->stat_lock);
1837                 if (fail_cor)
1838                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1839                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1840                 else
1841                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1842                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1843         }
1844
1845         return fail_cor + fail_gen;
1846 }
1847
1848 static void scrub_block_get(struct scrub_block *sblock)
1849 {
1850         atomic_inc(&sblock->ref_count);
1851 }
1852
1853 static void scrub_block_put(struct scrub_block *sblock)
1854 {
1855         if (atomic_dec_and_test(&sblock->ref_count)) {
1856                 int i;
1857
1858                 for (i = 0; i < sblock->page_count; i++)
1859                         scrub_page_put(sblock->pagev[i]);
1860                 kfree(sblock);
1861         }
1862 }
1863
1864 static void scrub_page_get(struct scrub_page *spage)
1865 {
1866         atomic_inc(&spage->ref_count);
1867 }
1868
1869 static void scrub_page_put(struct scrub_page *spage)
1870 {
1871         if (atomic_dec_and_test(&spage->ref_count)) {
1872                 if (spage->page)
1873                         __free_page(spage->page);
1874                 kfree(spage);
1875         }
1876 }
1877
1878 static void scrub_submit(struct scrub_ctx *sctx)
1879 {
1880         struct scrub_bio *sbio;
1881
1882         if (sctx->curr == -1)
1883                 return;
1884
1885         sbio = sctx->bios[sctx->curr];
1886         sctx->curr = -1;
1887         scrub_pending_bio_inc(sctx);
1888
1889         if (!sbio->bio->bi_bdev) {
1890                 /*
1891                  * this case should not happen. If btrfs_map_block() is
1892                  * wrong, it could happen for dev-replace operations on
1893                  * missing devices when no mirrors are available, but in
1894                  * this case it should already fail the mount.
1895                  * This case is handled correctly (but _very_ slowly).
1896                  */
1897                 printk_ratelimited(KERN_WARNING
1898                         "btrfs: scrub_submit(bio bdev == NULL) is unexpected!\n");
1899                 bio_endio(sbio->bio, -EIO);
1900         } else {
1901                 btrfsic_submit_bio(READ, sbio->bio);
1902         }
1903 }
1904
1905 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
1906                                     struct scrub_page *spage)
1907 {
1908         struct scrub_block *sblock = spage->sblock;
1909         struct scrub_bio *sbio;
1910         int ret;
1911
1912 again:
1913         /*
1914          * grab a fresh bio or wait for one to become available
1915          */
1916         while (sctx->curr == -1) {
1917                 spin_lock(&sctx->list_lock);
1918                 sctx->curr = sctx->first_free;
1919                 if (sctx->curr != -1) {
1920                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
1921                         sctx->bios[sctx->curr]->next_free = -1;
1922                         sctx->bios[sctx->curr]->page_count = 0;
1923                         spin_unlock(&sctx->list_lock);
1924                 } else {
1925                         spin_unlock(&sctx->list_lock);
1926                         wait_event(sctx->list_wait, sctx->first_free != -1);
1927                 }
1928         }
1929         sbio = sctx->bios[sctx->curr];
1930         if (sbio->page_count == 0) {
1931                 struct bio *bio;
1932
1933                 sbio->physical = spage->physical;
1934                 sbio->logical = spage->logical;
1935                 sbio->dev = spage->dev;
1936                 bio = sbio->bio;
1937                 if (!bio) {
1938                         bio = btrfs_io_bio_alloc(GFP_NOFS, sctx->pages_per_rd_bio);
1939                         if (!bio)
1940                                 return -ENOMEM;
1941                         sbio->bio = bio;
1942                 }
1943
1944                 bio->bi_private = sbio;
1945                 bio->bi_end_io = scrub_bio_end_io;
1946                 bio->bi_bdev = sbio->dev->bdev;
1947                 bio->bi_sector = sbio->physical >> 9;
1948                 sbio->err = 0;
1949         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1950                    spage->physical ||
1951                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1952                    spage->logical ||
1953                    sbio->dev != spage->dev) {
1954                 scrub_submit(sctx);
1955                 goto again;
1956         }
1957
1958         sbio->pagev[sbio->page_count] = spage;
1959         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1960         if (ret != PAGE_SIZE) {
1961                 if (sbio->page_count < 1) {
1962                         bio_put(sbio->bio);
1963                         sbio->bio = NULL;
1964                         return -EIO;
1965                 }
1966                 scrub_submit(sctx);
1967                 goto again;
1968         }
1969
1970         scrub_block_get(sblock); /* one for the page added to the bio */
1971         atomic_inc(&sblock->outstanding_pages);
1972         sbio->page_count++;
1973         if (sbio->page_count == sctx->pages_per_rd_bio)
1974                 scrub_submit(sctx);
1975
1976         return 0;
1977 }
1978
1979 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
1980                        u64 physical, struct btrfs_device *dev, u64 flags,
1981                        u64 gen, int mirror_num, u8 *csum, int force,
1982                        u64 physical_for_dev_replace)
1983 {
1984         struct scrub_block *sblock;
1985         int index;
1986
1987         sblock = kzalloc(sizeof(*sblock), GFP_NOFS);
1988         if (!sblock) {
1989                 spin_lock(&sctx->stat_lock);
1990                 sctx->stat.malloc_errors++;
1991                 spin_unlock(&sctx->stat_lock);
1992                 return -ENOMEM;
1993         }
1994
1995         /* one ref inside this function, plus one for each page added to
1996          * a bio later on */
1997         atomic_set(&sblock->ref_count, 1);
1998         sblock->sctx = sctx;
1999         sblock->no_io_error_seen = 1;
2000
2001         for (index = 0; len > 0; index++) {
2002                 struct scrub_page *spage;
2003                 u64 l = min_t(u64, len, PAGE_SIZE);
2004
2005                 spage = kzalloc(sizeof(*spage), GFP_NOFS);
2006                 if (!spage) {
2007 leave_nomem:
2008                         spin_lock(&sctx->stat_lock);
2009                         sctx->stat.malloc_errors++;
2010                         spin_unlock(&sctx->stat_lock);
2011                         scrub_block_put(sblock);
2012                         return -ENOMEM;
2013                 }
2014                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2015                 scrub_page_get(spage);
2016                 sblock->pagev[index] = spage;
2017                 spage->sblock = sblock;
2018                 spage->dev = dev;
2019                 spage->flags = flags;
2020                 spage->generation = gen;
2021                 spage->logical = logical;
2022                 spage->physical = physical;
2023                 spage->physical_for_dev_replace = physical_for_dev_replace;
2024                 spage->mirror_num = mirror_num;
2025                 if (csum) {
2026                         spage->have_csum = 1;
2027                         memcpy(spage->csum, csum, sctx->csum_size);
2028                 } else {
2029                         spage->have_csum = 0;
2030                 }
2031                 sblock->page_count++;
2032                 spage->page = alloc_page(GFP_NOFS);
2033                 if (!spage->page)
2034                         goto leave_nomem;
2035                 len -= l;
2036                 logical += l;
2037                 physical += l;
2038                 physical_for_dev_replace += l;
2039         }
2040
2041         WARN_ON(sblock->page_count == 0);
2042         for (index = 0; index < sblock->page_count; index++) {
2043                 struct scrub_page *spage = sblock->pagev[index];
2044                 int ret;
2045
2046                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2047                 if (ret) {
2048                         scrub_block_put(sblock);
2049                         return ret;
2050                 }
2051         }
2052
2053         if (force)
2054                 scrub_submit(sctx);
2055
2056         /* last one frees, either here or in bio completion for last page */
2057         scrub_block_put(sblock);
2058         return 0;
2059 }
2060
2061 static void scrub_bio_end_io(struct bio *bio, int err)
2062 {
2063         struct scrub_bio *sbio = bio->bi_private;
2064         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
2065
2066         sbio->err = err;
2067         sbio->bio = bio;
2068
2069         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
2070 }
2071
2072 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2073 {
2074         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2075         struct scrub_ctx *sctx = sbio->sctx;
2076         int i;
2077
2078         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2079         if (sbio->err) {
2080                 for (i = 0; i < sbio->page_count; i++) {
2081                         struct scrub_page *spage = sbio->pagev[i];
2082
2083                         spage->io_error = 1;
2084                         spage->sblock->no_io_error_seen = 0;
2085                 }
2086         }
2087
2088         /* now complete the scrub_block items that have all pages completed */
2089         for (i = 0; i < sbio->page_count; i++) {
2090                 struct scrub_page *spage = sbio->pagev[i];
2091                 struct scrub_block *sblock = spage->sblock;
2092
2093                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2094                         scrub_block_complete(sblock);
2095                 scrub_block_put(sblock);
2096         }
2097
2098         bio_put(sbio->bio);
2099         sbio->bio = NULL;
2100         spin_lock(&sctx->list_lock);
2101         sbio->next_free = sctx->first_free;
2102         sctx->first_free = sbio->index;
2103         spin_unlock(&sctx->list_lock);
2104
2105         if (sctx->is_dev_replace &&
2106             atomic_read(&sctx->wr_ctx.flush_all_writes)) {
2107                 mutex_lock(&sctx->wr_ctx.wr_lock);
2108                 scrub_wr_submit(sctx);
2109                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2110         }
2111
2112         scrub_pending_bio_dec(sctx);
2113 }
2114
2115 static void scrub_block_complete(struct scrub_block *sblock)
2116 {
2117         if (!sblock->no_io_error_seen) {
2118                 scrub_handle_errored_block(sblock);
2119         } else {
2120                 /*
2121                  * if has checksum error, write via repair mechanism in
2122                  * dev replace case, otherwise write here in dev replace
2123                  * case.
2124                  */
2125                 if (!scrub_checksum(sblock) && sblock->sctx->is_dev_replace)
2126                         scrub_write_block_to_dev_replace(sblock);
2127         }
2128 }
2129
2130 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u64 len,
2131                            u8 *csum)
2132 {
2133         struct btrfs_ordered_sum *sum = NULL;
2134         unsigned long index;
2135         unsigned long num_sectors;
2136
2137         while (!list_empty(&sctx->csum_list)) {
2138                 sum = list_first_entry(&sctx->csum_list,
2139                                        struct btrfs_ordered_sum, list);
2140                 if (sum->bytenr > logical)
2141                         return 0;
2142                 if (sum->bytenr + sum->len > logical)
2143                         break;
2144
2145                 ++sctx->stat.csum_discards;
2146                 list_del(&sum->list);
2147                 kfree(sum);
2148                 sum = NULL;
2149         }
2150         if (!sum)
2151                 return 0;
2152
2153         index = ((u32)(logical - sum->bytenr)) / sctx->sectorsize;
2154         num_sectors = sum->len / sctx->sectorsize;
2155         memcpy(csum, sum->sums + index, sctx->csum_size);
2156         if (index == num_sectors - 1) {
2157                 list_del(&sum->list);
2158                 kfree(sum);
2159         }
2160         return 1;
2161 }
2162
2163 /* scrub extent tries to collect up to 64 kB for each bio */
2164 static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
2165                         u64 physical, struct btrfs_device *dev, u64 flags,
2166                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2167 {
2168         int ret;
2169         u8 csum[BTRFS_CSUM_SIZE];
2170         u32 blocksize;
2171
2172         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2173                 blocksize = sctx->sectorsize;
2174                 spin_lock(&sctx->stat_lock);
2175                 sctx->stat.data_extents_scrubbed++;
2176                 sctx->stat.data_bytes_scrubbed += len;
2177                 spin_unlock(&sctx->stat_lock);
2178         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2179                 WARN_ON(sctx->nodesize != sctx->leafsize);
2180                 blocksize = sctx->nodesize;
2181                 spin_lock(&sctx->stat_lock);
2182                 sctx->stat.tree_extents_scrubbed++;
2183                 sctx->stat.tree_bytes_scrubbed += len;
2184                 spin_unlock(&sctx->stat_lock);
2185         } else {
2186                 blocksize = sctx->sectorsize;
2187                 WARN_ON(1);
2188         }
2189
2190         while (len) {
2191                 u64 l = min_t(u64, len, blocksize);
2192                 int have_csum = 0;
2193
2194                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2195                         /* push csums to sbio */
2196                         have_csum = scrub_find_csum(sctx, logical, l, csum);
2197                         if (have_csum == 0)
2198                                 ++sctx->stat.no_csum;
2199                         if (sctx->is_dev_replace && !have_csum) {
2200                                 ret = copy_nocow_pages(sctx, logical, l,
2201                                                        mirror_num,
2202                                                       physical_for_dev_replace);
2203                                 goto behind_scrub_pages;
2204                         }
2205                 }
2206                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2207                                   mirror_num, have_csum ? csum : NULL, 0,
2208                                   physical_for_dev_replace);
2209 behind_scrub_pages:
2210                 if (ret)
2211                         return ret;
2212                 len -= l;
2213                 logical += l;
2214                 physical += l;
2215                 physical_for_dev_replace += l;
2216         }
2217         return 0;
2218 }
2219
2220 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
2221                                            struct map_lookup *map,
2222                                            struct btrfs_device *scrub_dev,
2223                                            int num, u64 base, u64 length,
2224                                            int is_dev_replace)
2225 {
2226         struct btrfs_path *path;
2227         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
2228         struct btrfs_root *root = fs_info->extent_root;
2229         struct btrfs_root *csum_root = fs_info->csum_root;
2230         struct btrfs_extent_item *extent;
2231         struct blk_plug plug;
2232         u64 flags;
2233         int ret;
2234         int slot;
2235         u64 nstripes;
2236         struct extent_buffer *l;
2237         struct btrfs_key key;
2238         u64 physical;
2239         u64 logical;
2240         u64 logic_end;
2241         u64 generation;
2242         int mirror_num;
2243         struct reada_control *reada1;
2244         struct reada_control *reada2;
2245         struct btrfs_key key_start;
2246         struct btrfs_key key_end;
2247         u64 increment = map->stripe_len;
2248         u64 offset;
2249         u64 extent_logical;
2250         u64 extent_physical;
2251         u64 extent_len;
2252         struct btrfs_device *extent_dev;
2253         int extent_mirror_num;
2254         int stop_loop;
2255
2256         if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
2257                          BTRFS_BLOCK_GROUP_RAID6)) {
2258                 if (num >= nr_data_stripes(map)) {
2259                         return 0;
2260                 }
2261         }
2262
2263         nstripes = length;
2264         offset = 0;
2265         do_div(nstripes, map->stripe_len);
2266         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
2267                 offset = map->stripe_len * num;
2268                 increment = map->stripe_len * map->num_stripes;
2269                 mirror_num = 1;
2270         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
2271                 int factor = map->num_stripes / map->sub_stripes;
2272                 offset = map->stripe_len * (num / map->sub_stripes);
2273                 increment = map->stripe_len * factor;
2274                 mirror_num = num % map->sub_stripes + 1;
2275         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
2276                 increment = map->stripe_len;
2277                 mirror_num = num % map->num_stripes + 1;
2278         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
2279                 increment = map->stripe_len;
2280                 mirror_num = num % map->num_stripes + 1;
2281         } else {
2282                 increment = map->stripe_len;
2283                 mirror_num = 1;
2284         }
2285
2286         path = btrfs_alloc_path();
2287         if (!path)
2288                 return -ENOMEM;
2289
2290         /*
2291          * work on commit root. The related disk blocks are static as
2292          * long as COW is applied. This means, it is save to rewrite
2293          * them to repair disk errors without any race conditions
2294          */
2295         path->search_commit_root = 1;
2296         path->skip_locking = 1;
2297
2298         /*
2299          * trigger the readahead for extent tree csum tree and wait for
2300          * completion. During readahead, the scrub is officially paused
2301          * to not hold off transaction commits
2302          */
2303         logical = base + offset;
2304
2305         wait_event(sctx->list_wait,
2306                    atomic_read(&sctx->bios_in_flight) == 0);
2307         atomic_inc(&fs_info->scrubs_paused);
2308         wake_up(&fs_info->scrub_pause_wait);
2309
2310         /* FIXME it might be better to start readahead at commit root */
2311         key_start.objectid = logical;
2312         key_start.type = BTRFS_EXTENT_ITEM_KEY;
2313         key_start.offset = (u64)0;
2314         key_end.objectid = base + offset + nstripes * increment;
2315         key_end.type = BTRFS_METADATA_ITEM_KEY;
2316         key_end.offset = (u64)-1;
2317         reada1 = btrfs_reada_add(root, &key_start, &key_end);
2318
2319         key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
2320         key_start.type = BTRFS_EXTENT_CSUM_KEY;
2321         key_start.offset = logical;
2322         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
2323         key_end.type = BTRFS_EXTENT_CSUM_KEY;
2324         key_end.offset = base + offset + nstripes * increment;
2325         reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);
2326
2327         if (!IS_ERR(reada1))
2328                 btrfs_reada_wait(reada1);
2329         if (!IS_ERR(reada2))
2330                 btrfs_reada_wait(reada2);
2331
2332         mutex_lock(&fs_info->scrub_lock);
2333         while (atomic_read(&fs_info->scrub_pause_req)) {
2334                 mutex_unlock(&fs_info->scrub_lock);
2335                 wait_event(fs_info->scrub_pause_wait,
2336                    atomic_read(&fs_info->scrub_pause_req) == 0);
2337                 mutex_lock(&fs_info->scrub_lock);
2338         }
2339         atomic_dec(&fs_info->scrubs_paused);
2340         mutex_unlock(&fs_info->scrub_lock);
2341         wake_up(&fs_info->scrub_pause_wait);
2342
2343         /*
2344          * collect all data csums for the stripe to avoid seeking during
2345          * the scrub. This might currently (crc32) end up to be about 1MB
2346          */
2347         blk_start_plug(&plug);
2348
2349         /*
2350          * now find all extents for each stripe and scrub them
2351          */
2352         logical = base + offset;
2353         physical = map->stripes[num].physical;
2354         logic_end = logical + increment * nstripes;
2355         ret = 0;
2356         while (logical < logic_end) {
2357                 /*
2358                  * canceled?
2359                  */
2360                 if (atomic_read(&fs_info->scrub_cancel_req) ||
2361                     atomic_read(&sctx->cancel_req)) {
2362                         ret = -ECANCELED;
2363                         goto out;
2364                 }
2365                 /*
2366                  * check to see if we have to pause
2367                  */
2368                 if (atomic_read(&fs_info->scrub_pause_req)) {
2369                         /* push queued extents */
2370                         atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
2371                         scrub_submit(sctx);
2372                         mutex_lock(&sctx->wr_ctx.wr_lock);
2373                         scrub_wr_submit(sctx);
2374                         mutex_unlock(&sctx->wr_ctx.wr_lock);
2375                         wait_event(sctx->list_wait,
2376                                    atomic_read(&sctx->bios_in_flight) == 0);
2377                         atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
2378                         atomic_inc(&fs_info->scrubs_paused);
2379                         wake_up(&fs_info->scrub_pause_wait);
2380                         mutex_lock(&fs_info->scrub_lock);
2381                         while (atomic_read(&fs_info->scrub_pause_req)) {
2382                                 mutex_unlock(&fs_info->scrub_lock);
2383                                 wait_event(fs_info->scrub_pause_wait,
2384                                    atomic_read(&fs_info->scrub_pause_req) == 0);
2385                                 mutex_lock(&fs_info->scrub_lock);
2386                         }
2387                         atomic_dec(&fs_info->scrubs_paused);
2388                         mutex_unlock(&fs_info->scrub_lock);
2389                         wake_up(&fs_info->scrub_pause_wait);
2390                 }
2391
2392                 key.objectid = logical;
2393                 key.type = BTRFS_EXTENT_ITEM_KEY;
2394                 key.offset = (u64)-1;
2395
2396                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2397                 if (ret < 0)
2398                         goto out;
2399
2400                 if (ret > 0) {
2401                         ret = btrfs_previous_item(root, path, 0,
2402                                                   BTRFS_EXTENT_ITEM_KEY);
2403                         if (ret < 0)
2404                                 goto out;
2405                         if (ret > 0) {
2406                                 /* there's no smaller item, so stick with the
2407                                  * larger one */
2408                                 btrfs_release_path(path);
2409                                 ret = btrfs_search_slot(NULL, root, &key,
2410                                                         path, 0, 0);
2411                                 if (ret < 0)
2412                                         goto out;
2413                         }
2414                 }
2415
2416                 stop_loop = 0;
2417                 while (1) {
2418                         u64 bytes;
2419
2420                         l = path->nodes[0];
2421                         slot = path->slots[0];
2422                         if (slot >= btrfs_header_nritems(l)) {
2423                                 ret = btrfs_next_leaf(root, path);
2424                                 if (ret == 0)
2425                                         continue;
2426                                 if (ret < 0)
2427                                         goto out;
2428
2429                                 stop_loop = 1;
2430                                 break;
2431                         }
2432                         btrfs_item_key_to_cpu(l, &key, slot);
2433
2434                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2435                                 bytes = root->leafsize;
2436                         else
2437                                 bytes = key.offset;
2438
2439                         if (key.objectid + bytes <= logical)
2440                                 goto next;
2441
2442                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2443                             key.type != BTRFS_METADATA_ITEM_KEY)
2444                                 goto next;
2445
2446                         if (key.objectid >= logical + map->stripe_len) {
2447                                 /* out of this device extent */
2448                                 if (key.objectid >= logic_end)
2449                                         stop_loop = 1;
2450                                 break;
2451                         }
2452
2453                         extent = btrfs_item_ptr(l, slot,
2454                                                 struct btrfs_extent_item);
2455                         flags = btrfs_extent_flags(l, extent);
2456                         generation = btrfs_extent_generation(l, extent);
2457
2458                         if (key.objectid < logical &&
2459                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
2460                                 printk(KERN_ERR
2461                                        "btrfs scrub: tree block %llu spanning "
2462                                        "stripes, ignored. logical=%llu\n",
2463                                        key.objectid, logical);
2464                                 goto next;
2465                         }
2466
2467 again:
2468                         extent_logical = key.objectid;
2469                         extent_len = bytes;
2470
2471                         /*
2472                          * trim extent to this stripe
2473                          */
2474                         if (extent_logical < logical) {
2475                                 extent_len -= logical - extent_logical;
2476                                 extent_logical = logical;
2477                         }
2478                         if (extent_logical + extent_len >
2479                             logical + map->stripe_len) {
2480                                 extent_len = logical + map->stripe_len -
2481                                              extent_logical;
2482                         }
2483
2484                         extent_physical = extent_logical - logical + physical;
2485                         extent_dev = scrub_dev;
2486                         extent_mirror_num = mirror_num;
2487                         if (is_dev_replace)
2488                                 scrub_remap_extent(fs_info, extent_logical,
2489                                                    extent_len, &extent_physical,
2490                                                    &extent_dev,
2491                                                    &extent_mirror_num);
2492
2493                         ret = btrfs_lookup_csums_range(csum_root, logical,
2494                                                 logical + map->stripe_len - 1,
2495                                                 &sctx->csum_list, 1);
2496                         if (ret)
2497                                 goto out;
2498
2499                         ret = scrub_extent(sctx, extent_logical, extent_len,
2500                                            extent_physical, extent_dev, flags,
2501                                            generation, extent_mirror_num,
2502                                            extent_logical - logical + physical);
2503                         if (ret)
2504                                 goto out;
2505
2506                         scrub_free_csums(sctx);
2507                         if (extent_logical + extent_len <
2508                             key.objectid + bytes) {
2509                                 logical += increment;
2510                                 physical += map->stripe_len;
2511
2512                                 if (logical < key.objectid + bytes) {
2513                                         cond_resched();
2514                                         goto again;
2515                                 }
2516
2517                                 if (logical >= logic_end) {
2518                                         stop_loop = 1;
2519                                         break;
2520                                 }
2521                         }
2522 next:
2523                         path->slots[0]++;
2524                 }
2525                 btrfs_release_path(path);
2526                 logical += increment;
2527                 physical += map->stripe_len;
2528                 spin_lock(&sctx->stat_lock);
2529                 if (stop_loop)
2530                         sctx->stat.last_physical = map->stripes[num].physical +
2531                                                    length;
2532                 else
2533                         sctx->stat.last_physical = physical;
2534                 spin_unlock(&sctx->stat_lock);
2535                 if (stop_loop)
2536                         break;
2537         }
2538 out:
2539         /* push queued extents */
2540         scrub_submit(sctx);
2541         mutex_lock(&sctx->wr_ctx.wr_lock);
2542         scrub_wr_submit(sctx);
2543         mutex_unlock(&sctx->wr_ctx.wr_lock);
2544
2545         blk_finish_plug(&plug);
2546         btrfs_free_path(path);
2547         return ret < 0 ? ret : 0;
2548 }
2549
2550 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
2551                                           struct btrfs_device *scrub_dev,
2552                                           u64 chunk_tree, u64 chunk_objectid,
2553                                           u64 chunk_offset, u64 length,
2554                                           u64 dev_offset, int is_dev_replace)
2555 {
2556         struct btrfs_mapping_tree *map_tree =
2557                 &sctx->dev_root->fs_info->mapping_tree;
2558         struct map_lookup *map;
2559         struct extent_map *em;
2560         int i;
2561         int ret = 0;
2562
2563         read_lock(&map_tree->map_tree.lock);
2564         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
2565         read_unlock(&map_tree->map_tree.lock);
2566
2567         if (!em)
2568                 return -EINVAL;
2569
2570         map = (struct map_lookup *)em->bdev;
2571         if (em->start != chunk_offset)
2572                 goto out;
2573
2574         if (em->len < length)
2575                 goto out;
2576
2577         for (i = 0; i < map->num_stripes; ++i) {
2578                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
2579                     map->stripes[i].physical == dev_offset) {
2580                         ret = scrub_stripe(sctx, map, scrub_dev, i,
2581                                            chunk_offset, length,
2582                                            is_dev_replace);
2583                         if (ret)
2584                                 goto out;
2585                 }
2586         }
2587 out:
2588         free_extent_map(em);
2589
2590         return ret;
2591 }
2592
2593 static noinline_for_stack
2594 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
2595                            struct btrfs_device *scrub_dev, u64 start, u64 end,
2596                            int is_dev_replace)
2597 {
2598         struct btrfs_dev_extent *dev_extent = NULL;
2599         struct btrfs_path *path;
2600         struct btrfs_root *root = sctx->dev_root;
2601         struct btrfs_fs_info *fs_info = root->fs_info;
2602         u64 length;
2603         u64 chunk_tree;
2604         u64 chunk_objectid;
2605         u64 chunk_offset;
2606         int ret;
2607         int slot;
2608         struct extent_buffer *l;
2609         struct btrfs_key key;
2610         struct btrfs_key found_key;
2611         struct btrfs_block_group_cache *cache;
2612         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
2613
2614         path = btrfs_alloc_path();
2615         if (!path)
2616                 return -ENOMEM;
2617
2618         path->reada = 2;
2619         path->search_commit_root = 1;
2620         path->skip_locking = 1;
2621
2622         key.objectid = scrub_dev->devid;
2623         key.offset = 0ull;
2624         key.type = BTRFS_DEV_EXTENT_KEY;
2625
2626         while (1) {
2627                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2628                 if (ret < 0)
2629                         break;
2630                 if (ret > 0) {
2631                         if (path->slots[0] >=
2632                             btrfs_header_nritems(path->nodes[0])) {
2633                                 ret = btrfs_next_leaf(root, path);
2634                                 if (ret)
2635                                         break;
2636                         }
2637                 }
2638
2639                 l = path->nodes[0];
2640                 slot = path->slots[0];
2641
2642                 btrfs_item_key_to_cpu(l, &found_key, slot);
2643
2644                 if (found_key.objectid != scrub_dev->devid)
2645                         break;
2646
2647                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
2648                         break;
2649
2650                 if (found_key.offset >= end)
2651                         break;
2652
2653                 if (found_key.offset < key.offset)
2654                         break;
2655
2656                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
2657                 length = btrfs_dev_extent_length(l, dev_extent);
2658
2659                 if (found_key.offset + length <= start) {
2660                         key.offset = found_key.offset + length;
2661                         btrfs_release_path(path);
2662                         continue;
2663                 }
2664
2665                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
2666                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
2667                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
2668
2669                 /*
2670                  * get a reference on the corresponding block group to prevent
2671                  * the chunk from going away while we scrub it
2672                  */
2673                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
2674                 if (!cache) {
2675                         ret = -ENOENT;
2676                         break;
2677                 }
2678                 dev_replace->cursor_right = found_key.offset + length;
2679                 dev_replace->cursor_left = found_key.offset;
2680                 dev_replace->item_needs_writeback = 1;
2681                 ret = scrub_chunk(sctx, scrub_dev, chunk_tree, chunk_objectid,
2682                                   chunk_offset, length, found_key.offset,
2683                                   is_dev_replace);
2684
2685                 /*
2686                  * flush, submit all pending read and write bios, afterwards
2687                  * wait for them.
2688                  * Note that in the dev replace case, a read request causes
2689                  * write requests that are submitted in the read completion
2690                  * worker. Therefore in the current situation, it is required
2691                  * that all write requests are flushed, so that all read and
2692                  * write requests are really completed when bios_in_flight
2693                  * changes to 0.
2694                  */
2695                 atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
2696                 scrub_submit(sctx);
2697                 mutex_lock(&sctx->wr_ctx.wr_lock);
2698                 scrub_wr_submit(sctx);
2699                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2700
2701                 wait_event(sctx->list_wait,
2702                            atomic_read(&sctx->bios_in_flight) == 0);
2703                 atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
2704                 atomic_inc(&fs_info->scrubs_paused);
2705                 wake_up(&fs_info->scrub_pause_wait);
2706                 wait_event(sctx->list_wait,
2707                            atomic_read(&sctx->workers_pending) == 0);
2708
2709                 mutex_lock(&fs_info->scrub_lock);
2710                 while (atomic_read(&fs_info->scrub_pause_req)) {
2711                         mutex_unlock(&fs_info->scrub_lock);
2712                         wait_event(fs_info->scrub_pause_wait,
2713                            atomic_read(&fs_info->scrub_pause_req) == 0);
2714                         mutex_lock(&fs_info->scrub_lock);
2715                 }
2716                 atomic_dec(&fs_info->scrubs_paused);
2717                 mutex_unlock(&fs_info->scrub_lock);
2718                 wake_up(&fs_info->scrub_pause_wait);
2719
2720                 dev_replace->cursor_left = dev_replace->cursor_right;
2721                 dev_replace->item_needs_writeback = 1;
2722                 btrfs_put_block_group(cache);
2723                 if (ret)
2724                         break;
2725                 if (is_dev_replace &&
2726                     atomic64_read(&dev_replace->num_write_errors) > 0) {
2727                         ret = -EIO;
2728                         break;
2729                 }
2730                 if (sctx->stat.malloc_errors > 0) {
2731                         ret = -ENOMEM;
2732                         break;
2733                 }
2734
2735                 key.offset = found_key.offset + length;
2736                 btrfs_release_path(path);
2737         }
2738
2739         btrfs_free_path(path);
2740
2741         /*
2742          * ret can still be 1 from search_slot or next_leaf,
2743          * that's not an error
2744          */
2745         return ret < 0 ? ret : 0;
2746 }
2747
2748 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
2749                                            struct btrfs_device *scrub_dev)
2750 {
2751         int     i;
2752         u64     bytenr;
2753         u64     gen;
2754         int     ret;
2755         struct btrfs_root *root = sctx->dev_root;
2756
2757         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
2758                 return -EIO;
2759
2760         gen = root->fs_info->last_trans_committed;
2761
2762         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
2763                 bytenr = btrfs_sb_offset(i);
2764                 if (bytenr + BTRFS_SUPER_INFO_SIZE > scrub_dev->total_bytes)
2765                         break;
2766
2767                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
2768                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
2769                                   NULL, 1, bytenr);
2770                 if (ret)
2771                         return ret;
2772         }
2773         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
2774
2775         return 0;
2776 }
2777
2778 /*
2779  * get a reference count on fs_info->scrub_workers. start worker if necessary
2780  */
2781 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
2782                                                 int is_dev_replace)
2783 {
2784         int ret = 0;
2785
2786         mutex_lock(&fs_info->scrub_lock);
2787         if (fs_info->scrub_workers_refcnt == 0) {
2788                 if (is_dev_replace)
2789                         btrfs_init_workers(&fs_info->scrub_workers, "scrub", 1,
2790                                         &fs_info->generic_worker);
2791                 else
2792                         btrfs_init_workers(&fs_info->scrub_workers, "scrub",
2793                                         fs_info->thread_pool_size,
2794                                         &fs_info->generic_worker);
2795                 fs_info->scrub_workers.idle_thresh = 4;
2796                 ret = btrfs_start_workers(&fs_info->scrub_workers);
2797                 if (ret)
2798                         goto out;
2799                 btrfs_init_workers(&fs_info->scrub_wr_completion_workers,
2800                                    "scrubwrc",
2801                                    fs_info->thread_pool_size,
2802                                    &fs_info->generic_worker);
2803                 fs_info->scrub_wr_completion_workers.idle_thresh = 2;
2804                 ret = btrfs_start_workers(
2805                                 &fs_info->scrub_wr_completion_workers);
2806                 if (ret)
2807                         goto out;
2808                 btrfs_init_workers(&fs_info->scrub_nocow_workers, "scrubnc", 1,
2809                                    &fs_info->generic_worker);
2810                 ret = btrfs_start_workers(&fs_info->scrub_nocow_workers);
2811                 if (ret)
2812                         goto out;
2813         }
2814         ++fs_info->scrub_workers_refcnt;
2815 out:
2816         mutex_unlock(&fs_info->scrub_lock);
2817
2818         return ret;
2819 }
2820
2821 static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
2822 {
2823         mutex_lock(&fs_info->scrub_lock);
2824         if (--fs_info->scrub_workers_refcnt == 0) {
2825                 btrfs_stop_workers(&fs_info->scrub_workers);
2826                 btrfs_stop_workers(&fs_info->scrub_wr_completion_workers);
2827                 btrfs_stop_workers(&fs_info->scrub_nocow_workers);
2828         }
2829         WARN_ON(fs_info->scrub_workers_refcnt < 0);
2830         mutex_unlock(&fs_info->scrub_lock);
2831 }
2832
2833 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
2834                     u64 end, struct btrfs_scrub_progress *progress,
2835                     int readonly, int is_dev_replace)
2836 {
2837         struct scrub_ctx *sctx;
2838         int ret;
2839         struct btrfs_device *dev;
2840
2841         if (btrfs_fs_closing(fs_info))
2842                 return -EINVAL;
2843
2844         /*
2845          * check some assumptions
2846          */
2847         if (fs_info->chunk_root->nodesize != fs_info->chunk_root->leafsize) {
2848                 printk(KERN_ERR
2849                        "btrfs_scrub: size assumption nodesize == leafsize (%d == %d) fails\n",
2850                        fs_info->chunk_root->nodesize,
2851                        fs_info->chunk_root->leafsize);
2852                 return -EINVAL;
2853         }
2854
2855         if (fs_info->chunk_root->nodesize > BTRFS_STRIPE_LEN) {
2856                 /*
2857                  * in this case scrub is unable to calculate the checksum
2858                  * the way scrub is implemented. Do not handle this
2859                  * situation at all because it won't ever happen.
2860                  */
2861                 printk(KERN_ERR
2862                        "btrfs_scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails\n",
2863                        fs_info->chunk_root->nodesize, BTRFS_STRIPE_LEN);
2864                 return -EINVAL;
2865         }
2866
2867         if (fs_info->chunk_root->sectorsize != PAGE_SIZE) {
2868                 /* not supported for data w/o checksums */
2869                 printk(KERN_ERR
2870                        "btrfs_scrub: size assumption sectorsize != PAGE_SIZE (%d != %lu) fails\n",
2871                        fs_info->chunk_root->sectorsize, PAGE_SIZE);
2872                 return -EINVAL;
2873         }
2874
2875         if (fs_info->chunk_root->nodesize >
2876             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
2877             fs_info->chunk_root->sectorsize >
2878             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
2879                 /*
2880                  * would exhaust the array bounds of pagev member in
2881                  * struct scrub_block
2882                  */
2883                 pr_err("btrfs_scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails\n",
2884                        fs_info->chunk_root->nodesize,
2885                        SCRUB_MAX_PAGES_PER_BLOCK,
2886                        fs_info->chunk_root->sectorsize,
2887                        SCRUB_MAX_PAGES_PER_BLOCK);
2888                 return -EINVAL;
2889         }
2890
2891         ret = scrub_workers_get(fs_info, is_dev_replace);
2892         if (ret)
2893                 return ret;
2894
2895         mutex_lock(&fs_info->fs_devices->device_list_mutex);
2896         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
2897         if (!dev || (dev->missing && !is_dev_replace)) {
2898                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2899                 scrub_workers_put(fs_info);
2900                 return -ENODEV;
2901         }
2902         mutex_lock(&fs_info->scrub_lock);
2903
2904         if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
2905                 mutex_unlock(&fs_info->scrub_lock);
2906                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2907                 scrub_workers_put(fs_info);
2908                 return -EIO;
2909         }
2910
2911         btrfs_dev_replace_lock(&fs_info->dev_replace);
2912         if (dev->scrub_device ||
2913             (!is_dev_replace &&
2914              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
2915                 btrfs_dev_replace_unlock(&fs_info->dev_replace);
2916                 mutex_unlock(&fs_info->scrub_lock);
2917                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2918                 scrub_workers_put(fs_info);
2919                 return -EINPROGRESS;
2920         }
2921         btrfs_dev_replace_unlock(&fs_info->dev_replace);
2922         sctx = scrub_setup_ctx(dev, is_dev_replace);
2923         if (IS_ERR(sctx)) {
2924                 mutex_unlock(&fs_info->scrub_lock);
2925                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2926                 scrub_workers_put(fs_info);
2927                 return PTR_ERR(sctx);
2928         }
2929         sctx->readonly = readonly;
2930         dev->scrub_device = sctx;
2931
2932         atomic_inc(&fs_info->scrubs_running);
2933         mutex_unlock(&fs_info->scrub_lock);
2934         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2935
2936         if (!is_dev_replace) {
2937                 down_read(&fs_info->scrub_super_lock);
2938                 ret = scrub_supers(sctx, dev);
2939                 up_read(&fs_info->scrub_super_lock);
2940         }
2941
2942         if (!ret)
2943                 ret = scrub_enumerate_chunks(sctx, dev, start, end,
2944                                              is_dev_replace);
2945
2946         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
2947         atomic_dec(&fs_info->scrubs_running);
2948         wake_up(&fs_info->scrub_pause_wait);
2949
2950         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
2951
2952         if (progress)
2953                 memcpy(progress, &sctx->stat, sizeof(*progress));
2954
2955         mutex_lock(&fs_info->scrub_lock);
2956         dev->scrub_device = NULL;
2957         mutex_unlock(&fs_info->scrub_lock);
2958
2959         scrub_free_ctx(sctx);
2960         scrub_workers_put(fs_info);
2961
2962         return ret;
2963 }
2964
2965 void btrfs_scrub_pause(struct btrfs_root *root)
2966 {
2967         struct btrfs_fs_info *fs_info = root->fs_info;
2968
2969         mutex_lock(&fs_info->scrub_lock);
2970         atomic_inc(&fs_info->scrub_pause_req);
2971         while (atomic_read(&fs_info->scrubs_paused) !=
2972                atomic_read(&fs_info->scrubs_running)) {
2973                 mutex_unlock(&fs_info->scrub_lock);
2974                 wait_event(fs_info->scrub_pause_wait,
2975                            atomic_read(&fs_info->scrubs_paused) ==
2976                            atomic_read(&fs_info->scrubs_running));
2977                 mutex_lock(&fs_info->scrub_lock);
2978         }
2979         mutex_unlock(&fs_info->scrub_lock);
2980 }
2981
2982 void btrfs_scrub_continue(struct btrfs_root *root)
2983 {
2984         struct btrfs_fs_info *fs_info = root->fs_info;
2985
2986         atomic_dec(&fs_info->scrub_pause_req);
2987         wake_up(&fs_info->scrub_pause_wait);
2988 }
2989
2990 void btrfs_scrub_pause_super(struct btrfs_root *root)
2991 {
2992         down_write(&root->fs_info->scrub_super_lock);
2993 }
2994
2995 void btrfs_scrub_continue_super(struct btrfs_root *root)
2996 {
2997         up_write(&root->fs_info->scrub_super_lock);
2998 }
2999
3000 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
3001 {
3002         mutex_lock(&fs_info->scrub_lock);
3003         if (!atomic_read(&fs_info->scrubs_running)) {
3004                 mutex_unlock(&fs_info->scrub_lock);
3005                 return -ENOTCONN;
3006         }
3007
3008         atomic_inc(&fs_info->scrub_cancel_req);
3009         while (atomic_read(&fs_info->scrubs_running)) {
3010                 mutex_unlock(&fs_info->scrub_lock);
3011                 wait_event(fs_info->scrub_pause_wait,
3012                            atomic_read(&fs_info->scrubs_running) == 0);
3013                 mutex_lock(&fs_info->scrub_lock);
3014         }
3015         atomic_dec(&fs_info->scrub_cancel_req);
3016         mutex_unlock(&fs_info->scrub_lock);
3017
3018         return 0;
3019 }
3020
3021 int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
3022                            struct btrfs_device *dev)
3023 {
3024         struct scrub_ctx *sctx;
3025
3026         mutex_lock(&fs_info->scrub_lock);
3027         sctx = dev->scrub_device;
3028         if (!sctx) {
3029                 mutex_unlock(&fs_info->scrub_lock);
3030                 return -ENOTCONN;
3031         }
3032         atomic_inc(&sctx->cancel_req);
3033         while (dev->scrub_device) {
3034                 mutex_unlock(&fs_info->scrub_lock);
3035                 wait_event(fs_info->scrub_pause_wait,
3036                            dev->scrub_device == NULL);
3037                 mutex_lock(&fs_info->scrub_lock);
3038         }
3039         mutex_unlock(&fs_info->scrub_lock);
3040
3041         return 0;
3042 }
3043
3044 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
3045                          struct btrfs_scrub_progress *progress)
3046 {
3047         struct btrfs_device *dev;
3048         struct scrub_ctx *sctx = NULL;
3049
3050         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
3051         dev = btrfs_find_device(root->fs_info, devid, NULL, NULL);
3052         if (dev)
3053                 sctx = dev->scrub_device;
3054         if (sctx)
3055                 memcpy(progress, &sctx->stat, sizeof(*progress));
3056         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
3057
3058         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
3059 }
3060
3061 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
3062                                u64 extent_logical, u64 extent_len,
3063                                u64 *extent_physical,
3064                                struct btrfs_device **extent_dev,
3065                                int *extent_mirror_num)
3066 {
3067         u64 mapped_length;
3068         struct btrfs_bio *bbio = NULL;
3069         int ret;
3070
3071         mapped_length = extent_len;
3072         ret = btrfs_map_block(fs_info, READ, extent_logical,
3073                               &mapped_length, &bbio, 0);
3074         if (ret || !bbio || mapped_length < extent_len ||
3075             !bbio->stripes[0].dev->bdev) {
3076                 kfree(bbio);
3077                 return;
3078         }
3079
3080         *extent_physical = bbio->stripes[0].physical;
3081         *extent_mirror_num = bbio->mirror_num;
3082         *extent_dev = bbio->stripes[0].dev;
3083         kfree(bbio);
3084 }
3085
3086 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
3087                               struct scrub_wr_ctx *wr_ctx,
3088                               struct btrfs_fs_info *fs_info,
3089                               struct btrfs_device *dev,
3090                               int is_dev_replace)
3091 {
3092         WARN_ON(wr_ctx->wr_curr_bio != NULL);
3093
3094         mutex_init(&wr_ctx->wr_lock);
3095         wr_ctx->wr_curr_bio = NULL;
3096         if (!is_dev_replace)
3097                 return 0;
3098
3099         WARN_ON(!dev->bdev);
3100         wr_ctx->pages_per_wr_bio = min_t(int, SCRUB_PAGES_PER_WR_BIO,
3101                                          bio_get_nr_vecs(dev->bdev));
3102         wr_ctx->tgtdev = dev;
3103         atomic_set(&wr_ctx->flush_all_writes, 0);
3104         return 0;
3105 }
3106
3107 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
3108 {
3109         mutex_lock(&wr_ctx->wr_lock);
3110         kfree(wr_ctx->wr_curr_bio);
3111         wr_ctx->wr_curr_bio = NULL;
3112         mutex_unlock(&wr_ctx->wr_lock);
3113 }
3114
3115 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
3116                             int mirror_num, u64 physical_for_dev_replace)
3117 {
3118         struct scrub_copy_nocow_ctx *nocow_ctx;
3119         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
3120
3121         nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
3122         if (!nocow_ctx) {
3123                 spin_lock(&sctx->stat_lock);
3124                 sctx->stat.malloc_errors++;
3125                 spin_unlock(&sctx->stat_lock);
3126                 return -ENOMEM;
3127         }
3128
3129         scrub_pending_trans_workers_inc(sctx);
3130
3131         nocow_ctx->sctx = sctx;
3132         nocow_ctx->logical = logical;
3133         nocow_ctx->len = len;
3134         nocow_ctx->mirror_num = mirror_num;
3135         nocow_ctx->physical_for_dev_replace = physical_for_dev_replace;
3136         nocow_ctx->work.func = copy_nocow_pages_worker;
3137         INIT_LIST_HEAD(&nocow_ctx->inodes);
3138         btrfs_queue_worker(&fs_info->scrub_nocow_workers,
3139                            &nocow_ctx->work);
3140
3141         return 0;
3142 }
3143
3144 static int record_inode_for_nocow(u64 inum, u64 offset, u64 root, void *ctx)
3145 {
3146         struct scrub_copy_nocow_ctx *nocow_ctx = ctx;
3147         struct scrub_nocow_inode *nocow_inode;
3148
3149         nocow_inode = kzalloc(sizeof(*nocow_inode), GFP_NOFS);
3150         if (!nocow_inode)
3151                 return -ENOMEM;
3152         nocow_inode->inum = inum;
3153         nocow_inode->offset = offset;
3154         nocow_inode->root = root;
3155         list_add_tail(&nocow_inode->list, &nocow_ctx->inodes);
3156         return 0;
3157 }
3158
3159 #define COPY_COMPLETE 1
3160
3161 static void copy_nocow_pages_worker(struct btrfs_work *work)
3162 {
3163         struct scrub_copy_nocow_ctx *nocow_ctx =
3164                 container_of(work, struct scrub_copy_nocow_ctx, work);
3165         struct scrub_ctx *sctx = nocow_ctx->sctx;
3166         u64 logical = nocow_ctx->logical;
3167         u64 len = nocow_ctx->len;
3168         int mirror_num = nocow_ctx->mirror_num;
3169         u64 physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
3170         int ret;
3171         struct btrfs_trans_handle *trans = NULL;
3172         struct btrfs_fs_info *fs_info;
3173         struct btrfs_path *path;
3174         struct btrfs_root *root;
3175         int not_written = 0;
3176
3177         fs_info = sctx->dev_root->fs_info;
3178         root = fs_info->extent_root;
3179
3180         path = btrfs_alloc_path();
3181         if (!path) {
3182                 spin_lock(&sctx->stat_lock);
3183                 sctx->stat.malloc_errors++;
3184                 spin_unlock(&sctx->stat_lock);
3185                 not_written = 1;
3186                 goto out;
3187         }
3188
3189         trans = btrfs_join_transaction(root);
3190         if (IS_ERR(trans)) {
3191                 not_written = 1;
3192                 goto out;
3193         }
3194
3195         ret = iterate_inodes_from_logical(logical, fs_info, path,
3196                                           record_inode_for_nocow, nocow_ctx);
3197         if (ret != 0 && ret != -ENOENT) {
3198                 pr_warn("iterate_inodes_from_logical() failed: log %llu, phys %llu, len %llu, mir %u, ret %d\n",
3199                         logical, physical_for_dev_replace, len, mirror_num,
3200                         ret);
3201                 not_written = 1;
3202                 goto out;
3203         }
3204
3205         btrfs_end_transaction(trans, root);
3206         trans = NULL;
3207         while (!list_empty(&nocow_ctx->inodes)) {
3208                 struct scrub_nocow_inode *entry;
3209                 entry = list_first_entry(&nocow_ctx->inodes,
3210                                          struct scrub_nocow_inode,
3211                                          list);
3212                 list_del_init(&entry->list);
3213                 ret = copy_nocow_pages_for_inode(entry->inum, entry->offset,
3214                                                  entry->root, nocow_ctx);
3215                 kfree(entry);
3216                 if (ret == COPY_COMPLETE) {
3217                         ret = 0;
3218                         break;
3219                 } else if (ret) {
3220                         break;
3221                 }
3222         }
3223 out:
3224         while (!list_empty(&nocow_ctx->inodes)) {
3225                 struct scrub_nocow_inode *entry;
3226                 entry = list_first_entry(&nocow_ctx->inodes,
3227                                          struct scrub_nocow_inode,
3228                                          list);
3229                 list_del_init(&entry->list);
3230                 kfree(entry);
3231         }
3232         if (trans && !IS_ERR(trans))
3233                 btrfs_end_transaction(trans, root);
3234         if (not_written)
3235                 btrfs_dev_replace_stats_inc(&fs_info->dev_replace.
3236                                             num_uncorrectable_read_errors);
3237
3238         btrfs_free_path(path);
3239         kfree(nocow_ctx);
3240
3241         scrub_pending_trans_workers_dec(sctx);
3242 }
3243
3244 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
3245                                       struct scrub_copy_nocow_ctx *nocow_ctx)
3246 {
3247         struct btrfs_fs_info *fs_info = nocow_ctx->sctx->dev_root->fs_info;
3248         struct btrfs_key key;
3249         struct inode *inode;
3250         struct page *page;
3251         struct btrfs_root *local_root;
3252         struct btrfs_ordered_extent *ordered;
3253         struct extent_map *em;
3254         struct extent_state *cached_state = NULL;
3255         struct extent_io_tree *io_tree;
3256         u64 physical_for_dev_replace;
3257         u64 len = nocow_ctx->len;
3258         u64 lockstart = offset, lockend = offset + len - 1;
3259         unsigned long index;
3260         int srcu_index;
3261         int ret = 0;
3262         int err = 0;
3263
3264         key.objectid = root;
3265         key.type = BTRFS_ROOT_ITEM_KEY;
3266         key.offset = (u64)-1;
3267
3268         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
3269
3270         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
3271         if (IS_ERR(local_root)) {
3272                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
3273                 return PTR_ERR(local_root);
3274         }
3275
3276         key.type = BTRFS_INODE_ITEM_KEY;
3277         key.objectid = inum;
3278         key.offset = 0;
3279         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
3280         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
3281         if (IS_ERR(inode))
3282                 return PTR_ERR(inode);
3283
3284         /* Avoid truncate/dio/punch hole.. */
3285         mutex_lock(&inode->i_mutex);
3286         inode_dio_wait(inode);
3287
3288         physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
3289         io_tree = &BTRFS_I(inode)->io_tree;
3290
3291         lock_extent_bits(io_tree, lockstart, lockend, 0, &cached_state);
3292         ordered = btrfs_lookup_ordered_range(inode, lockstart, len);
3293         if (ordered) {
3294                 btrfs_put_ordered_extent(ordered);
3295                 goto out_unlock;
3296         }
3297
3298         em = btrfs_get_extent(inode, NULL, 0, lockstart, len, 0);
3299         if (IS_ERR(em)) {
3300                 ret = PTR_ERR(em);
3301                 goto out_unlock;
3302         }
3303
3304         /*
3305          * This extent does not actually cover the logical extent anymore,
3306          * move on to the next inode.
3307          */
3308         if (em->block_start > nocow_ctx->logical ||
3309             em->block_start + em->block_len < nocow_ctx->logical + len) {
3310                 free_extent_map(em);
3311                 goto out_unlock;
3312         }
3313         free_extent_map(em);
3314
3315         while (len >= PAGE_CACHE_SIZE) {
3316                 index = offset >> PAGE_CACHE_SHIFT;
3317 again:
3318                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
3319                 if (!page) {
3320                         pr_err("find_or_create_page() failed\n");
3321                         ret = -ENOMEM;
3322                         goto out;
3323                 }
3324
3325                 if (PageUptodate(page)) {
3326                         if (PageDirty(page))
3327                                 goto next_page;
3328                 } else {
3329                         ClearPageError(page);
3330                         err = extent_read_full_page_nolock(io_tree, page,
3331                                                            btrfs_get_extent,
3332                                                            nocow_ctx->mirror_num);
3333                         if (err) {
3334                                 ret = err;
3335                                 goto next_page;
3336                         }
3337
3338                         lock_page(page);
3339                         /*
3340                          * If the page has been remove from the page cache,
3341                          * the data on it is meaningless, because it may be
3342                          * old one, the new data may be written into the new
3343                          * page in the page cache.
3344                          */
3345                         if (page->mapping != inode->i_mapping) {
3346                                 unlock_page(page);
3347                                 page_cache_release(page);
3348                                 goto again;
3349                         }
3350                         if (!PageUptodate(page)) {
3351                                 ret = -EIO;
3352                                 goto next_page;
3353                         }
3354                 }
3355                 err = write_page_nocow(nocow_ctx->sctx,
3356                                        physical_for_dev_replace, page);
3357                 if (err)
3358                         ret = err;
3359 next_page:
3360                 unlock_page(page);
3361                 page_cache_release(page);
3362
3363                 if (ret)
3364                         break;
3365
3366                 offset += PAGE_CACHE_SIZE;
3367                 physical_for_dev_replace += PAGE_CACHE_SIZE;
3368                 len -= PAGE_CACHE_SIZE;
3369         }
3370         ret = COPY_COMPLETE;
3371 out_unlock:
3372         unlock_extent_cached(io_tree, lockstart, lockend, &cached_state,
3373                              GFP_NOFS);
3374 out:
3375         mutex_unlock(&inode->i_mutex);
3376         iput(inode);
3377         return ret;
3378 }
3379
3380 static int write_page_nocow(struct scrub_ctx *sctx,
3381                             u64 physical_for_dev_replace, struct page *page)
3382 {
3383         struct bio *bio;
3384         struct btrfs_device *dev;
3385         int ret;
3386         DECLARE_COMPLETION_ONSTACK(compl);
3387
3388         dev = sctx->wr_ctx.tgtdev;
3389         if (!dev)
3390                 return -EIO;
3391         if (!dev->bdev) {
3392                 printk_ratelimited(KERN_WARNING
3393                         "btrfs: scrub write_page_nocow(bdev == NULL) is unexpected!\n");
3394                 return -EIO;
3395         }
3396         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
3397         if (!bio) {
3398                 spin_lock(&sctx->stat_lock);
3399                 sctx->stat.malloc_errors++;
3400                 spin_unlock(&sctx->stat_lock);
3401                 return -ENOMEM;
3402         }
3403         bio->bi_private = &compl;
3404         bio->bi_end_io = scrub_complete_bio_end_io;
3405         bio->bi_size = 0;
3406         bio->bi_sector = physical_for_dev_replace >> 9;
3407         bio->bi_bdev = dev->bdev;
3408         ret = bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
3409         if (ret != PAGE_CACHE_SIZE) {
3410 leave_with_eio:
3411                 bio_put(bio);
3412                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
3413                 return -EIO;
3414         }
3415         btrfsic_submit_bio(WRITE_SYNC, bio);
3416         wait_for_completion(&compl);
3417
3418         if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
3419                 goto leave_with_eio;
3420
3421         bio_put(bio);
3422         return 0;
3423 }