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