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