fs/btrfs/file-item.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  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/bio.h>
  20 #include <linux/slab.h>
  21 #include <linux/pagemap.h>
  22 #include <linux/highmem.h>
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "transaction.h"
  26 #include "print-tree.h"
  27
  28 #define MAX_CSUM_ITEMS(r, size) ((((BTRFS_LEAF_DATA_SIZE(r) - \
  29                                    sizeof(struct btrfs_item) * 2) / \
  30                                   size) - 1))
  31
  32 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
  33                                    sizeof(struct btrfs_ordered_sum)) / \
  34                                    sizeof(struct btrfs_sector_sum) * \
  35                                    (r)->sectorsize - (r)->sectorsize)
  36
  37 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  38                              struct btrfs_root *root,
  39                              u64 objectid, u64 pos,
  40                              u64 disk_offset, u64 disk_num_bytes,
  41                              u64 num_bytes, u64 offset, u64 ram_bytes,
  42                              u8 compression, u8 encryption, u16 other_encoding)
  43 {
  44         int ret = 0;
  45         struct btrfs_file_extent_item *item;
  46         struct btrfs_key file_key;
  47         struct btrfs_path *path;
  48         struct extent_buffer *leaf;
  49
  50         path = btrfs_alloc_path();
  51         if (!path)
  52                 return -ENOMEM;
  53         file_key.objectid = objectid;
  54         file_key.offset = pos;
  55         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
  56
  57         path->leave_spinning = 1;
  58         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  59                                       sizeof(*item));
  60         if (ret < 0)
  61                 goto out;
  62         BUG_ON(ret);
  63         leaf = path->nodes[0];
  64         item = btrfs_item_ptr(leaf, path->slots[0],
  65                               struct btrfs_file_extent_item);
  66         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  67         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  68         btrfs_set_file_extent_offset(leaf, item, offset);
  69         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  70         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  71         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  72         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  73         btrfs_set_file_extent_compression(leaf, item, compression);
  74         btrfs_set_file_extent_encryption(leaf, item, encryption);
  75         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  76
  77         btrfs_mark_buffer_dirty(leaf);
  78 out:
  79         btrfs_free_path(path);
  80         return ret;
  81 }
  82
  83 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  84                                           struct btrfs_root *root,
  85                                           struct btrfs_path *path,
  86                                           u64 bytenr, int cow)
  87 {
  88         int ret;
  89         struct btrfs_key file_key;
  90         struct btrfs_key found_key;
  91         struct btrfs_csum_item *item;
  92         struct extent_buffer *leaf;
  93         u64 csum_offset = 0;
  94         u16 csum_size =
  95                 btrfs_super_csum_size(&root->fs_info->super_copy);
  96         int csums_in_item;
  97
  98         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
  99         file_key.offset = bytenr;
 100         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 101         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 102         if (ret < 0)
 103                 goto fail;
 104         leaf = path->nodes[0];
 105         if (ret > 0) {
 106                 ret = 1;
 107                 if (path->slots[0] == 0)
 108                         goto fail;
 109                 path->slots[0]--;
 110                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 111                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
 112                         goto fail;
 113
 114                 csum_offset = (bytenr - found_key.offset) >>
 115                                 root->fs_info->sb->s_blocksize_bits;
 116                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 117                 csums_in_item /= csum_size;
 118
 119                 if (csum_offset >= csums_in_item) {
 120                         ret = -EFBIG;
 121                         goto fail;
 122                 }
 123         }
 124         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 125         item = (struct btrfs_csum_item *)((unsigned char *)item +
 126                                           csum_offset * csum_size);
 127         return item;
 128 fail:
 129         if (ret > 0)
 130                 ret = -ENOENT;
 131         return ERR_PTR(ret);
 132 }
 133
 134
 135 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 136                              struct btrfs_root *root,
 137                              struct btrfs_path *path, u64 objectid,
 138                              u64 offset, int mod)
 139 {
 140         int ret;
 141         struct btrfs_key file_key;
 142         int ins_len = mod < 0 ? -1 : 0;
 143         int cow = mod != 0;
 144
 145         file_key.objectid = objectid;
 146         file_key.offset = offset;
 147         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 148         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 149         return ret;
 150 }
 151
 152
 153 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 154                                    struct inode *inode, struct bio *bio,
 155                                    u64 logical_offset, u32 *dst, int dio)
 156 {
 157         u32 sum;
 158         struct bio_vec *bvec = bio->bi_io_vec;
 159         int bio_index = 0;
 160         u64 offset = 0;
 161         u64 item_start_offset = 0;
 162         u64 item_last_offset = 0;
 163         u64 disk_bytenr;
 164         u32 diff;
 165         u16 csum_size =
 166                 btrfs_super_csum_size(&root->fs_info->super_copy);
 167         int ret;
 168         struct btrfs_path *path;
 169         struct btrfs_csum_item *item = NULL;
 170         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 171
 172         path = btrfs_alloc_path();
 173         if (!path)
 174                 return -ENOMEM;
 175         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 176                 path->reada = 2;
 177
 178         WARN_ON(bio->bi_vcnt <= 0);
 179
 180         disk_bytenr = (u64)bio->bi_sector << 9;
 181         if (dio)
 182                 offset = logical_offset;
 183         while (bio_index < bio->bi_vcnt) {
 184                 if (!dio)
 185                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 186                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
 187                 if (ret == 0)
 188                         goto found;
 189
 190                 if (!item || disk_bytenr < item_start_offset ||
 191                     disk_bytenr >= item_last_offset) {
 192                         struct btrfs_key found_key;
 193                         u32 item_size;
 194
 195                         if (item)
 196                                 btrfs_release_path(path);
 197                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 198                                                  path, disk_bytenr, 0);
 199                         if (IS_ERR(item)) {
 200                                 ret = PTR_ERR(item);
 201                                 if (ret == -ENOENT || ret == -EFBIG)
 202                                         ret = 0;
 203                                 sum = 0;
 204                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 205                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 206                                         set_extent_bits(io_tree, offset,
 207                                                 offset + bvec->bv_len - 1,
 208                                                 EXTENT_NODATASUM, GFP_NOFS);
 209                                 } else {
 210                                         printk(KERN_INFO "btrfs no csum found "
 211                                                "for inode %llu start %llu\n",
 212                                                (unsigned long long)
 213                                                btrfs_ino(inode),
 214                                                (unsigned long long)offset);
 215                                 }
 216                                 item = NULL;
 217                                 btrfs_release_path(path);
 218                                 goto found;
 219                         }
 220                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 221                                               path->slots[0]);
 222
 223                         item_start_offset = found_key.offset;
 224                         item_size = btrfs_item_size_nr(path->nodes[0],
 225                                                        path->slots[0]);
 226                         item_last_offset = item_start_offset +
 227                                 (item_size / csum_size) *
 228                                 root->sectorsize;
 229                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 230                                               struct btrfs_csum_item);
 231                 }
 232                 /*
 233                  * this byte range must be able to fit inside
 234                  * a single leaf so it will also fit inside a u32
 235                  */
 236                 diff = disk_bytenr - item_start_offset;
 237                 diff = diff / root->sectorsize;
 238                 diff = diff * csum_size;
 239
 240                 read_extent_buffer(path->nodes[0], &sum,
 241                                    ((unsigned long)item) + diff,
 242                                    csum_size);
 243 found:
 244                 if (dst)
 245                         *dst++ = sum;
 246                 else
 247                         set_state_private(io_tree, offset, sum);
 248                 disk_bytenr += bvec->bv_len;
 249                 offset += bvec->bv_len;
 250                 bio_index++;
 251                 bvec++;
 252         }
 253         btrfs_free_path(path);
 254         return 0;
 255 }
 256
 257 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 258                           struct bio *bio, u32 *dst)
 259 {
 260         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 261 }
 262
 263 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 264                               struct bio *bio, u64 offset, u32 *dst)
 265 {
 266         return __btrfs_lookup_bio_sums(root, inode, bio, offset, dst, 1);
 267 }
 268
 269 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 270                              struct list_head *list)
 271 {
 272         struct btrfs_key key;
 273         struct btrfs_path *path;
 274         struct extent_buffer *leaf;
 275         struct btrfs_ordered_sum *sums;
 276         struct btrfs_sector_sum *sector_sum;
 277         struct btrfs_csum_item *item;
 278         unsigned long offset;
 279         int ret;
 280         size_t size;
 281         u64 csum_end;
 282         u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
 283
 284         path = btrfs_alloc_path();
 285         BUG_ON(!path);
 286
 287         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 288         key.offset = start;
 289         key.type = BTRFS_EXTENT_CSUM_KEY;
 290
 291         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 292         if (ret < 0)
 293                 goto fail;
 294         if (ret > 0 && path->slots[0] > 0) {
 295                 leaf = path->nodes[0];
 296                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 297                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 298                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 299                         offset = (start - key.offset) >>
 300                                  root->fs_info->sb->s_blocksize_bits;
 301                         if (offset * csum_size <
 302                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 303                                 path->slots[0]--;
 304                 }
 305         }
 306
 307         while (start <= end) {
 308                 leaf = path->nodes[0];
 309                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 310                         ret = btrfs_next_leaf(root, path);
 311                         if (ret < 0)
 312                                 goto fail;
 313                         if (ret > 0)
 314                                 break;
 315                         leaf = path->nodes[0];
 316                 }
 317
 318                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 319                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 320                     key.type != BTRFS_EXTENT_CSUM_KEY)
 321                         break;
 322
 323                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 324                 if (key.offset > end)
 325                         break;
 326
 327                 if (key.offset > start)
 328                         start = key.offset;
 329
 330                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 331                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 332                 if (csum_end <= start) {
 333                         path->slots[0]++;
 334                         continue;
 335                 }
 336
 337                 csum_end = min(csum_end, end + 1);
 338                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 339                                       struct btrfs_csum_item);
 340                 while (start < csum_end) {
 341                         size = min_t(size_t, csum_end - start,
 342                                         MAX_ORDERED_SUM_BYTES(root));
 343                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 344                                         GFP_NOFS);
 345                         BUG_ON(!sums);
 346
 347                         sector_sum = sums->sums;
 348                         sums->bytenr = start;
 349                         sums->len = size;
 350
 351                         offset = (start - key.offset) >>
 352                                 root->fs_info->sb->s_blocksize_bits;
 353                         offset *= csum_size;
 354
 355                         while (size > 0) {
 356                                 read_extent_buffer(path->nodes[0],
 357                                                 &sector_sum->sum,
 358                                                 ((unsigned long)item) +
 359                                                 offset, csum_size);
 360                                 sector_sum->bytenr = start;
 361
 362                                 size -= root->sectorsize;
 363                                 start += root->sectorsize;
 364                                 offset += csum_size;
 365                                 sector_sum++;
 366                         }
 367                         list_add_tail(&sums->list, list);
 368                 }
 369                 path->slots[0]++;
 370         }
 371         ret = 0;
 372 fail:
 373         btrfs_free_path(path);
 374         return ret;
 375 }
 376
 377 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 378                        struct bio *bio, u64 file_start, int contig)
 379 {
 380         struct btrfs_ordered_sum *sums;
 381         struct btrfs_sector_sum *sector_sum;
 382         struct btrfs_ordered_extent *ordered;
 383         char *data;
 384         struct bio_vec *bvec = bio->bi_io_vec;
 385         int bio_index = 0;
 386         unsigned long total_bytes = 0;
 387         unsigned long this_sum_bytes = 0;
 388         u64 offset;
 389         u64 disk_bytenr;
 390
 391         WARN_ON(bio->bi_vcnt <= 0);
 392         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 393         if (!sums)
 394                 return -ENOMEM;
 395
 396         sector_sum = sums->sums;
 397         disk_bytenr = (u64)bio->bi_sector << 9;
 398         sums->len = bio->bi_size;
 399         INIT_LIST_HEAD(&sums->list);
 400
 401         if (contig)
 402                 offset = file_start;
 403         else
 404                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 405
 406         ordered = btrfs_lookup_ordered_extent(inode, offset);
 407         BUG_ON(!ordered);
 408         sums->bytenr = ordered->start;
 409
 410         while (bio_index < bio->bi_vcnt) {
 411                 if (!contig)
 412                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 413
 414                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
 415                     offset < ordered->file_offset)) {
 416                         unsigned long bytes_left;
 417                         sums->len = this_sum_bytes;
 418                         this_sum_bytes = 0;
 419                         btrfs_add_ordered_sum(inode, ordered, sums);
 420                         btrfs_put_ordered_extent(ordered);
 421
 422                         bytes_left = bio->bi_size - total_bytes;
 423
 424                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 425                                        GFP_NOFS);
 426                         BUG_ON(!sums);
 427                         sector_sum = sums->sums;
 428                         sums->len = bytes_left;
 429                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 430                         BUG_ON(!ordered);
 431                         sums->bytenr = ordered->start;
 432                 }
 433
 434                 data = kmap_atomic(bvec->bv_page, KM_USER0);
 435                 sector_sum->sum = ~(u32)0;
 436                 sector_sum->sum = btrfs_csum_data(root,
 437                                                   data + bvec->bv_offset,
 438                                                   sector_sum->sum,
 439                                                   bvec->bv_len);
 440                 kunmap_atomic(data, KM_USER0);
 441                 btrfs_csum_final(sector_sum->sum,
 442                                  (char *)&sector_sum->sum);
 443                 sector_sum->bytenr = disk_bytenr;
 444
 445                 sector_sum++;
 446                 bio_index++;
 447                 total_bytes += bvec->bv_len;
 448                 this_sum_bytes += bvec->bv_len;
 449                 disk_bytenr += bvec->bv_len;
 450                 offset += bvec->bv_len;
 451                 bvec++;
 452         }
 453         this_sum_bytes = 0;
 454         btrfs_add_ordered_sum(inode, ordered, sums);
 455         btrfs_put_ordered_extent(ordered);
 456         return 0;
 457 }
 458
 459 /*
 460  * helper function for csum removal, this expects the
 461  * key to describe the csum pointed to by the path, and it expects
 462  * the csum to overlap the range [bytenr, len]
 463  *
 464  * The csum should not be entirely contained in the range and the
 465  * range should not be entirely contained in the csum.
 466  *
 467  * This calls btrfs_truncate_item with the correct args based on the
 468  * overlap, and fixes up the key as required.
 469  */
 470 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
 471                                       struct btrfs_root *root,
 472                                       struct btrfs_path *path,
 473                                       struct btrfs_key *key,
 474                                       u64 bytenr, u64 len)
 475 {
 476         struct extent_buffer *leaf;
 477         u16 csum_size =
 478                 btrfs_super_csum_size(&root->fs_info->super_copy);
 479         u64 csum_end;
 480         u64 end_byte = bytenr + len;
 481         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 482         int ret;
 483
 484         leaf = path->nodes[0];
 485         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 486         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 487         csum_end += key->offset;
 488
 489         if (key->offset < bytenr && csum_end <= end_byte) {
 490                 /*
 491                  *         [ bytenr - len ]
 492                  *         [   ]
 493                  *   [csum     ]
 494                  *   A simple truncate off the end of the item
 495                  */
 496                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 497                 new_size *= csum_size;
 498                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
 499                 BUG_ON(ret);
 500         } else if (key->offset >= bytenr && csum_end > end_byte &&
 501                    end_byte > key->offset) {
 502                 /*
 503                  *         [ bytenr - len ]
 504                  *                 [ ]
 505                  *                 [csum     ]
 506                  * we need to truncate from the beginning of the csum
 507                  */
 508                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 509                 new_size *= csum_size;
 510
 511                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
 512                 BUG_ON(ret);
 513
 514                 key->offset = end_byte;
 515                 ret = btrfs_set_item_key_safe(trans, root, path, key);
 516                 BUG_ON(ret);
 517         } else {
 518                 BUG();
 519         }
 520         return 0;
 521 }
 522
 523 /*
 524  * deletes the csum items from the csum tree for a given
 525  * range of bytes.
 526  */
 527 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 528                     struct btrfs_root *root, u64 bytenr, u64 len)
 529 {
 530         struct btrfs_path *path;
 531         struct btrfs_key key;
 532         u64 end_byte = bytenr + len;
 533         u64 csum_end;
 534         struct extent_buffer *leaf;
 535         int ret;
 536         u16 csum_size =
 537                 btrfs_super_csum_size(&root->fs_info->super_copy);
 538         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 539
 540         root = root->fs_info->csum_root;
 541
 542         path = btrfs_alloc_path();
 543         if (!path)
 544                 return -ENOMEM;
 545
 546         while (1) {
 547                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 548                 key.offset = end_byte - 1;
 549                 key.type = BTRFS_EXTENT_CSUM_KEY;
 550
 551                 path->leave_spinning = 1;
 552                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 553                 if (ret > 0) {
 554                         if (path->slots[0] == 0)
 555                                 goto out;
 556                         path->slots[0]--;
 557                 } else if (ret < 0) {
 558                         goto out;
 559                 }
 560
 561                 leaf = path->nodes[0];
 562                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 563
 564                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 565                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 566                         break;
 567                 }
 568
 569                 if (key.offset >= end_byte)
 570                         break;
 571
 572                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 573                 csum_end <<= blocksize_bits;
 574                 csum_end += key.offset;
 575
 576                 /* this csum ends before we start, we're done */
 577                 if (csum_end <= bytenr)
 578                         break;
 579
 580                 /* delete the entire item, it is inside our range */
 581                 if (key.offset >= bytenr && csum_end <= end_byte) {
 582                         ret = btrfs_del_item(trans, root, path);
 583                         BUG_ON(ret);
 584                         if (key.offset == bytenr)
 585                                 break;
 586                 } else if (key.offset < bytenr && csum_end > end_byte) {
 587                         unsigned long offset;
 588                         unsigned long shift_len;
 589                         unsigned long item_offset;
 590                         /*
 591                          *        [ bytenr - len ]
 592                          *     [csum                ]
 593                          *
 594                          * Our bytes are in the middle of the csum,
 595                          * we need to split this item and insert a new one.
 596                          *
 597                          * But we can't drop the path because the
 598                          * csum could change, get removed, extended etc.
 599                          *
 600                          * The trick here is the max size of a csum item leaves
 601                          * enough room in the tree block for a single
 602                          * item header.  So, we split the item in place,
 603                          * adding a new header pointing to the existing
 604                          * bytes.  Then we loop around again and we have
 605                          * a nicely formed csum item that we can neatly
 606                          * truncate.
 607                          */
 608                         offset = (bytenr - key.offset) >> blocksize_bits;
 609                         offset *= csum_size;
 610
 611                         shift_len = (len >> blocksize_bits) * csum_size;
 612
 613                         item_offset = btrfs_item_ptr_offset(leaf,
 614                                                             path->slots[0]);
 615
 616                         memset_extent_buffer(leaf, 0, item_offset + offset,
 617                                              shift_len);
 618                         key.offset = bytenr;
 619
 620                         /*
 621                          * btrfs_split_item returns -EAGAIN when the
 622                          * item changed size or key
 623                          */
 624                         ret = btrfs_split_item(trans, root, path, &key, offset);
 625                         BUG_ON(ret && ret != -EAGAIN);
 626
 627                         key.offset = end_byte - 1;
 628                 } else {
 629                         ret = truncate_one_csum(trans, root, path,
 630                                                 &key, bytenr, len);
 631                         BUG_ON(ret);
 632                         if (key.offset < bytenr)
 633                                 break;
 634                 }
 635                 btrfs_release_path(path);
 636         }
 637 out:
 638         btrfs_free_path(path);
 639         return 0;
 640 }
 641
 642 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 643                            struct btrfs_root *root,
 644                            struct btrfs_ordered_sum *sums)
 645 {
 646         u64 bytenr;
 647         int ret;
 648         struct btrfs_key file_key;
 649         struct btrfs_key found_key;
 650         u64 next_offset;
 651         u64 total_bytes = 0;
 652         int found_next;
 653         struct btrfs_path *path;
 654         struct btrfs_csum_item *item;
 655         struct btrfs_csum_item *item_end;
 656         struct extent_buffer *leaf = NULL;
 657         u64 csum_offset;
 658         struct btrfs_sector_sum *sector_sum;
 659         u32 nritems;
 660         u32 ins_size;
 661         char *eb_map;
 662         char *eb_token;
 663         unsigned long map_len;
 664         unsigned long map_start;
 665         u16 csum_size =
 666                 btrfs_super_csum_size(&root->fs_info->super_copy);
 667
 668         path = btrfs_alloc_path();
 669         BUG_ON(!path);
 670         sector_sum = sums->sums;
 671 again:
 672         next_offset = (u64)-1;
 673         found_next = 0;
 674         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 675         file_key.offset = sector_sum->bytenr;
 676         bytenr = sector_sum->bytenr;
 677         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 678
 679         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 680         if (!IS_ERR(item)) {
 681                 leaf = path->nodes[0];
 682                 ret = 0;
 683                 goto found;
 684         }
 685         ret = PTR_ERR(item);
 686         if (ret != -EFBIG && ret != -ENOENT)
 687                 goto fail_unlock;
 688
 689         if (ret == -EFBIG) {
 690                 u32 item_size;
 691                 /* we found one, but it isn't big enough yet */
 692                 leaf = path->nodes[0];
 693                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 694                 if ((item_size / csum_size) >=
 695                     MAX_CSUM_ITEMS(root, csum_size)) {
 696                         /* already at max size, make a new one */
 697                         goto insert;
 698                 }
 699         } else {
 700                 int slot = path->slots[0] + 1;
 701                 /* we didn't find a csum item, insert one */
 702                 nritems = btrfs_header_nritems(path->nodes[0]);
 703                 if (path->slots[0] >= nritems - 1) {
 704                         ret = btrfs_next_leaf(root, path);
 705                         if (ret == 1)
 706                                 found_next = 1;
 707                         if (ret != 0)
 708                                 goto insert;
 709                         slot = 0;
 710                 }
 711                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 712                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 713                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 714                         found_next = 1;
 715                         goto insert;
 716                 }
 717                 next_offset = found_key.offset;
 718                 found_next = 1;
 719                 goto insert;
 720         }
 721
 722         /*
 723          * at this point, we know the tree has an item, but it isn't big
 724          * enough yet to put our csum in.  Grow it
 725          */
 726         btrfs_release_path(path);
 727         ret = btrfs_search_slot(trans, root, &file_key, path,
 728                                 csum_size, 1);
 729         if (ret < 0)
 730                 goto fail_unlock;
 731
 732         if (ret > 0) {
 733                 if (path->slots[0] == 0)
 734                         goto insert;
 735                 path->slots[0]--;
 736         }
 737
 738         leaf = path->nodes[0];
 739         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 740         csum_offset = (bytenr - found_key.offset) >>
 741                         root->fs_info->sb->s_blocksize_bits;
 742
 743         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 744             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 745             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 746                 goto insert;
 747         }
 748
 749         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
 750             csum_size) {
 751                 u32 diff = (csum_offset + 1) * csum_size;
 752
 753                 /*
 754                  * is the item big enough already?  we dropped our lock
 755                  * before and need to recheck
 756                  */
 757                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
 758                         goto csum;
 759
 760                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 761                 if (diff != csum_size)
 762                         goto insert;
 763
 764                 ret = btrfs_extend_item(trans, root, path, diff);
 765                 BUG_ON(ret);
 766                 goto csum;
 767         }
 768
 769 insert:
 770         btrfs_release_path(path);
 771         csum_offset = 0;
 772         if (found_next) {
 773                 u64 tmp = total_bytes + root->sectorsize;
 774                 u64 next_sector = sector_sum->bytenr;
 775                 struct btrfs_sector_sum *next = sector_sum + 1;
 776
 777                 while (tmp < sums->len) {
 778                         if (next_sector + root->sectorsize != next->bytenr)
 779                                 break;
 780                         tmp += root->sectorsize;
 781                         next_sector = next->bytenr;
 782                         next++;
 783                 }
 784                 tmp = min(tmp, next_offset - file_key.offset);
 785                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 786                 tmp = max((u64)1, tmp);
 787                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 788                 ins_size = csum_size * tmp;
 789         } else {
 790                 ins_size = csum_size;
 791         }
 792         path->leave_spinning = 1;
 793         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 794                                       ins_size);
 795         path->leave_spinning = 0;
 796         if (ret < 0)
 797                 goto fail_unlock;
 798         if (ret != 0) {
 799                 WARN_ON(1);
 800                 goto fail_unlock;
 801         }
 802 csum:
 803         leaf = path->nodes[0];
 804         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 805         ret = 0;
 806         item = (struct btrfs_csum_item *)((unsigned char *)item +
 807                                           csum_offset * csum_size);
 808 found:
 809         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 810         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 811                                       btrfs_item_size_nr(leaf, path->slots[0]));
 812         eb_token = NULL;
 813 next_sector:
 814
 815         if (!eb_token ||
 816            (unsigned long)item + csum_size >= map_start + map_len) {
 817                 int err;
 818
 819                 if (eb_token)
 820                         unmap_extent_buffer(leaf, eb_token, KM_USER1);
 821                 eb_token = NULL;
 822                 err = map_private_extent_buffer(leaf, (unsigned long)item,
 823                                                 csum_size,
 824                                                 &eb_token, &eb_map,
 825                                                 &map_start, &map_len, KM_USER1);
 826                 if (err)
 827                         eb_token = NULL;
 828         }
 829         if (eb_token) {
 830                 memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
 831                        &sector_sum->sum, csum_size);
 832         } else {
 833                 write_extent_buffer(leaf, &sector_sum->sum,
 834                                     (unsigned long)item, csum_size);
 835         }
 836
 837         total_bytes += root->sectorsize;
 838         sector_sum++;
 839         if (total_bytes < sums->len) {
 840                 item = (struct btrfs_csum_item *)((char *)item +
 841                                                   csum_size);
 842                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 843                     sector_sum->bytenr) {
 844                         bytenr = sector_sum->bytenr;
 845                         goto next_sector;
 846                 }
 847         }
 848         if (eb_token) {
 849                 unmap_extent_buffer(leaf, eb_token, KM_USER1);
 850                 eb_token = NULL;
 851         }
 852         btrfs_mark_buffer_dirty(path->nodes[0]);
 853         if (total_bytes < sums->len) {
 854                 btrfs_release_path(path);
 855                 cond_resched();
 856                 goto again;
 857         }
 858 out:
 859         btrfs_free_path(path);
 860         return ret;
 861
 862 fail_unlock:
 863         goto out;
 864 }