git.oblomov.eu Git - linux-2.6/blob - 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
  31 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
  32                                    sizeof(struct btrfs_ordered_sum)) / \
  33                                    sizeof(struct btrfs_sector_sum) * \
  34                                    (r)->sectorsize - (r)->sectorsize)
  35
  36 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  37                              struct btrfs_root *root,
  38                              u64 objectid, u64 pos,
  39                              u64 disk_offset, u64 disk_num_bytes,
  40                              u64 num_bytes, u64 offset, u64 ram_bytes,
  41                              u8 compression, u8 encryption, u16 other_encoding)
  42 {
  43         int ret = 0;
  44         struct btrfs_file_extent_item *item;
  45         struct btrfs_key file_key;
  46         struct btrfs_path *path;
  47         struct extent_buffer *leaf;
  48
  49         path = btrfs_alloc_path();
  50         BUG_ON(!path);
  51         file_key.objectid = objectid;
  52         file_key.offset = pos;
  53         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
  54
  55         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  56                                       sizeof(*item));
  57         if (ret < 0)
  58                 goto out;
  59         BUG_ON(ret);
  60         leaf = path->nodes[0];
  61         item = btrfs_item_ptr(leaf, path->slots[0],
  62                               struct btrfs_file_extent_item);
  63         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  64         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  65         btrfs_set_file_extent_offset(leaf, item, offset);
  66         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  67         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  68         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  69         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  70         btrfs_set_file_extent_compression(leaf, item, compression);
  71         btrfs_set_file_extent_encryption(leaf, item, encryption);
  72         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  73
  74         btrfs_mark_buffer_dirty(leaf);
  75 out:
  76         btrfs_free_path(path);
  77         return ret;
  78 }
  79
  80 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  81                                           struct btrfs_root *root,
  82                                           struct btrfs_path *path,
  83                                           u64 bytenr, int cow)
  84 {
  85         int ret;
  86         struct btrfs_key file_key;
  87         struct btrfs_key found_key;
  88         struct btrfs_csum_item *item;
  89         struct extent_buffer *leaf;
  90         u64 csum_offset = 0;
  91         u16 csum_size =
  92                 btrfs_super_csum_size(&root->fs_info->super_copy);
  93         int csums_in_item;
  94
  95         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
  96         file_key.offset = bytenr;
  97         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
  98         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
  99         if (ret < 0)
 100                 goto fail;
 101         leaf = path->nodes[0];
 102         if (ret > 0) {
 103                 ret = 1;
 104                 if (path->slots[0] == 0)
 105                         goto fail;
 106                 path->slots[0]--;
 107                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 108                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
 109                         goto fail;
 110
 111                 csum_offset = (bytenr - found_key.offset) >>
 112                                 root->fs_info->sb->s_blocksize_bits;
 113                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 114                 csums_in_item /= csum_size;
 115
 116                 if (csum_offset >= csums_in_item) {
 117                         ret = -EFBIG;
 118                         goto fail;
 119                 }
 120         }
 121         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 122         item = (struct btrfs_csum_item *)((unsigned char *)item +
 123                                           csum_offset * csum_size);
 124         return item;
 125 fail:
 126         if (ret > 0)
 127                 ret = -ENOENT;
 128         return ERR_PTR(ret);
 129 }
 130
 131
 132 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 133                              struct btrfs_root *root,
 134                              struct btrfs_path *path, u64 objectid,
 135                              u64 offset, int mod)
 136 {
 137         int ret;
 138         struct btrfs_key file_key;
 139         int ins_len = mod < 0 ? -1 : 0;
 140         int cow = mod != 0;
 141
 142         file_key.objectid = objectid;
 143         file_key.offset = offset;
 144         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 145         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 146         return ret;
 147 }
 148
 149
 150 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 151                           struct bio *bio, u32 *dst)
 152 {
 153         u32 sum;
 154         struct bio_vec *bvec = bio->bi_io_vec;
 155         int bio_index = 0;
 156         u64 offset;
 157         u64 item_start_offset = 0;
 158         u64 item_last_offset = 0;
 159         u64 disk_bytenr;
 160         u32 diff;
 161         u16 csum_size =
 162                 btrfs_super_csum_size(&root->fs_info->super_copy);
 163         int ret;
 164         struct btrfs_path *path;
 165         struct btrfs_csum_item *item = NULL;
 166         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 167
 168         path = btrfs_alloc_path();
 169         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 170                 path->reada = 2;
 171
 172         WARN_ON(bio->bi_vcnt <= 0);
 173
 174         disk_bytenr = (u64)bio->bi_sector << 9;
 175         while (bio_index < bio->bi_vcnt) {
 176                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 177                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
 178                 if (ret == 0)
 179                         goto found;
 180
 181                 if (!item || disk_bytenr < item_start_offset ||
 182                     disk_bytenr >= item_last_offset) {
 183                         struct btrfs_key found_key;
 184                         u32 item_size;
 185
 186                         if (item)
 187                                 btrfs_release_path(root, path);
 188                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 189                                                  path, disk_bytenr, 0);
 190                         if (IS_ERR(item)) {
 191                                 ret = PTR_ERR(item);
 192                                 if (ret == -ENOENT || ret == -EFBIG)
 193                                         ret = 0;
 194                                 sum = 0;
 195                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 196                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 197                                         set_extent_bits(io_tree, offset,
 198                                                 offset + bvec->bv_len - 1,
 199                                                 EXTENT_NODATASUM, GFP_NOFS);
 200                                 } else {
 201                                         printk(KERN_INFO "btrfs no csum found "
 202                                                "for inode %lu start %llu\n",
 203                                                inode->i_ino,
 204                                                (unsigned long long)offset);
 205                                 }
 206                                 item = NULL;
 207                                 btrfs_release_path(root, path);
 208                                 goto found;
 209                         }
 210                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 211                                               path->slots[0]);
 212
 213                         item_start_offset = found_key.offset;
 214                         item_size = btrfs_item_size_nr(path->nodes[0],
 215                                                        path->slots[0]);
 216                         item_last_offset = item_start_offset +
 217                                 (item_size / csum_size) *
 218                                 root->sectorsize;
 219                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 220                                               struct btrfs_csum_item);
 221                 }
 222                 /*
 223                  * this byte range must be able to fit inside
 224                  * a single leaf so it will also fit inside a u32
 225                  */
 226                 diff = disk_bytenr - item_start_offset;
 227                 diff = diff / root->sectorsize;
 228                 diff = diff * csum_size;
 229
 230                 read_extent_buffer(path->nodes[0], &sum,
 231                                    ((unsigned long)item) + diff,
 232                                    csum_size);
 233 found:
 234                 if (dst)
 235                         *dst++ = sum;
 236                 else
 237                         set_state_private(io_tree, offset, sum);
 238                 disk_bytenr += bvec->bv_len;
 239                 bio_index++;
 240                 bvec++;
 241         }
 242         btrfs_free_path(path);
 243         return 0;
 244 }
 245
 246 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 247                              struct list_head *list)
 248 {
 249         struct btrfs_key key;
 250         struct btrfs_path *path;
 251         struct extent_buffer *leaf;
 252         struct btrfs_ordered_sum *sums;
 253         struct btrfs_sector_sum *sector_sum;
 254         struct btrfs_csum_item *item;
 255         unsigned long offset;
 256         int ret;
 257         size_t size;
 258         u64 csum_end;
 259         u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
 260
 261         path = btrfs_alloc_path();
 262         BUG_ON(!path);
 263
 264         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 265         key.offset = start;
 266         key.type = BTRFS_EXTENT_CSUM_KEY;
 267
 268         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 269         if (ret < 0)
 270                 goto fail;
 271         if (ret > 0 && path->slots[0] > 0) {
 272                 leaf = path->nodes[0];
 273                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 274                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 275                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 276                         offset = (start - key.offset) >>
 277                                  root->fs_info->sb->s_blocksize_bits;
 278                         if (offset * csum_size <
 279                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 280                                 path->slots[0]--;
 281                 }
 282         }
 283
 284         while (start <= end) {
 285                 leaf = path->nodes[0];
 286                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 287                         ret = btrfs_next_leaf(root, path);
 288                         if (ret < 0)
 289                                 goto fail;
 290                         if (ret > 0)
 291                                 break;
 292                         leaf = path->nodes[0];
 293                 }
 294
 295                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 296                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 297                     key.type != BTRFS_EXTENT_CSUM_KEY)
 298                         break;
 299
 300                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 301                 if (key.offset > end)
 302                         break;
 303
 304                 if (key.offset > start)
 305                         start = key.offset;
 306
 307                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 308                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 309                 if (csum_end <= start) {
 310                         path->slots[0]++;
 311                         continue;
 312                 }
 313
 314                 csum_end = min(csum_end, end + 1);
 315                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 316                                       struct btrfs_csum_item);
 317                 while (start < csum_end) {
 318                         size = min_t(size_t, csum_end - start,
 319                                         MAX_ORDERED_SUM_BYTES(root));
 320                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 321                                         GFP_NOFS);
 322                         BUG_ON(!sums);
 323
 324                         sector_sum = sums->sums;
 325                         sums->bytenr = start;
 326                         sums->len = size;
 327
 328                         offset = (start - key.offset) >>
 329                                 root->fs_info->sb->s_blocksize_bits;
 330                         offset *= csum_size;
 331
 332                         while (size > 0) {
 333                                 read_extent_buffer(path->nodes[0],
 334                                                 &sector_sum->sum,
 335                                                 ((unsigned long)item) +
 336                                                 offset, csum_size);
 337                                 sector_sum->bytenr = start;
 338
 339                                 size -= root->sectorsize;
 340                                 start += root->sectorsize;
 341                                 offset += csum_size;
 342                                 sector_sum++;
 343                         }
 344                         list_add_tail(&sums->list, list);
 345                 }
 346                 path->slots[0]++;
 347         }
 348         ret = 0;
 349 fail:
 350         btrfs_free_path(path);
 351         return ret;
 352 }
 353
 354 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 355                        struct bio *bio, u64 file_start, int contig)
 356 {
 357         struct btrfs_ordered_sum *sums;
 358         struct btrfs_sector_sum *sector_sum;
 359         struct btrfs_ordered_extent *ordered;
 360         char *data;
 361         struct bio_vec *bvec = bio->bi_io_vec;
 362         int bio_index = 0;
 363         unsigned long total_bytes = 0;
 364         unsigned long this_sum_bytes = 0;
 365         u64 offset;
 366         u64 disk_bytenr;
 367
 368         WARN_ON(bio->bi_vcnt <= 0);
 369         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 370         if (!sums)
 371                 return -ENOMEM;
 372
 373         sector_sum = sums->sums;
 374         disk_bytenr = (u64)bio->bi_sector << 9;
 375         sums->len = bio->bi_size;
 376         INIT_LIST_HEAD(&sums->list);
 377
 378         if (contig)
 379                 offset = file_start;
 380         else
 381                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 382
 383         ordered = btrfs_lookup_ordered_extent(inode, offset);
 384         BUG_ON(!ordered);
 385         sums->bytenr = ordered->start;
 386
 387         while (bio_index < bio->bi_vcnt) {
 388                 if (!contig)
 389                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 390
 391                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
 392                     offset < ordered->file_offset)) {
 393                         unsigned long bytes_left;
 394                         sums->len = this_sum_bytes;
 395                         this_sum_bytes = 0;
 396                         btrfs_add_ordered_sum(inode, ordered, sums);
 397                         btrfs_put_ordered_extent(ordered);
 398
 399                         bytes_left = bio->bi_size - total_bytes;
 400
 401                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 402                                        GFP_NOFS);
 403                         BUG_ON(!sums);
 404                         sector_sum = sums->sums;
 405                         sums->len = bytes_left;
 406                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 407                         BUG_ON(!ordered);
 408                         sums->bytenr = ordered->start;
 409                 }
 410
 411                 data = kmap_atomic(bvec->bv_page, KM_USER0);
 412                 sector_sum->sum = ~(u32)0;
 413                 sector_sum->sum = btrfs_csum_data(root,
 414                                                   data + bvec->bv_offset,
 415                                                   sector_sum->sum,
 416                                                   bvec->bv_len);
 417                 kunmap_atomic(data, KM_USER0);
 418                 btrfs_csum_final(sector_sum->sum,
 419                                  (char *)&sector_sum->sum);
 420                 sector_sum->bytenr = disk_bytenr;
 421
 422                 sector_sum++;
 423                 bio_index++;
 424                 total_bytes += bvec->bv_len;
 425                 this_sum_bytes += bvec->bv_len;
 426                 disk_bytenr += bvec->bv_len;
 427                 offset += bvec->bv_len;
 428                 bvec++;
 429         }
 430         this_sum_bytes = 0;
 431         btrfs_add_ordered_sum(inode, ordered, sums);
 432         btrfs_put_ordered_extent(ordered);
 433         return 0;
 434 }
 435
 436 /*
 437  * helper function for csum removal, this expects the
 438  * key to describe the csum pointed to by the path, and it expects
 439  * the csum to overlap the range [bytenr, len]
 440  *
 441  * The csum should not be entirely contained in the range and the
 442  * range should not be entirely contained in the csum.
 443  *
 444  * This calls btrfs_truncate_item with the correct args based on the
 445  * overlap, and fixes up the key as required.
 446  */
 447 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
 448                                       struct btrfs_root *root,
 449                                       struct btrfs_path *path,
 450                                       struct btrfs_key *key,
 451                                       u64 bytenr, u64 len)
 452 {
 453         struct extent_buffer *leaf;
 454         u16 csum_size =
 455                 btrfs_super_csum_size(&root->fs_info->super_copy);
 456         u64 csum_end;
 457         u64 end_byte = bytenr + len;
 458         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 459         int ret;
 460
 461         leaf = path->nodes[0];
 462         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 463         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 464         csum_end += key->offset;
 465
 466         if (key->offset < bytenr && csum_end <= end_byte) {
 467                 /*
 468                  *         [ bytenr - len ]
 469                  *         [   ]
 470                  *   [csum     ]
 471                  *   A simple truncate off the end of the item
 472                  */
 473                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 474                 new_size *= csum_size;
 475                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
 476                 BUG_ON(ret);
 477         } else if (key->offset >= bytenr && csum_end > end_byte &&
 478                    end_byte > key->offset) {
 479                 /*
 480                  *         [ bytenr - len ]
 481                  *                 [ ]
 482                  *                 [csum     ]
 483                  * we need to truncate from the beginning of the csum
 484                  */
 485                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 486                 new_size *= csum_size;
 487
 488                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
 489                 BUG_ON(ret);
 490
 491                 key->offset = end_byte;
 492                 ret = btrfs_set_item_key_safe(trans, root, path, key);
 493                 BUG_ON(ret);
 494         } else {
 495                 BUG();
 496         }
 497         return 0;
 498 }
 499
 500 /*
 501  * deletes the csum items from the csum tree for a given
 502  * range of bytes.
 503  */
 504 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 505                     struct btrfs_root *root, u64 bytenr, u64 len)
 506 {
 507         struct btrfs_path *path;
 508         struct btrfs_key key;
 509         u64 end_byte = bytenr + len;
 510         u64 csum_end;
 511         struct extent_buffer *leaf;
 512         int ret;
 513         u16 csum_size =
 514                 btrfs_super_csum_size(&root->fs_info->super_copy);
 515         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 516
 517         root = root->fs_info->csum_root;
 518
 519         path = btrfs_alloc_path();
 520
 521         while (1) {
 522                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 523                 key.offset = end_byte - 1;
 524                 key.type = BTRFS_EXTENT_CSUM_KEY;
 525
 526                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 527                 if (ret > 0) {
 528                         if (path->slots[0] == 0)
 529                                 goto out;
 530                         path->slots[0]--;
 531                 }
 532                 leaf = path->nodes[0];
 533                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 534
 535                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 536                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 537                         break;
 538                 }
 539
 540                 if (key.offset >= end_byte)
 541                         break;
 542
 543                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 544                 csum_end <<= blocksize_bits;
 545                 csum_end += key.offset;
 546
 547                 /* this csum ends before we start, we're done */
 548                 if (csum_end <= bytenr)
 549                         break;
 550
 551                 /* delete the entire item, it is inside our range */
 552                 if (key.offset >= bytenr && csum_end <= end_byte) {
 553                         ret = btrfs_del_item(trans, root, path);
 554                         BUG_ON(ret);
 555                         if (key.offset == bytenr)
 556                                 break;
 557                 } else if (key.offset < bytenr && csum_end > end_byte) {
 558                         unsigned long offset;
 559                         unsigned long shift_len;
 560                         unsigned long item_offset;
 561                         /*
 562                          *        [ bytenr - len ]
 563                          *     [csum                ]
 564                          *
 565                          * Our bytes are in the middle of the csum,
 566                          * we need to split this item and insert a new one.
 567                          *
 568                          * But we can't drop the path because the
 569                          * csum could change, get removed, extended etc.
 570                          *
 571                          * The trick here is the max size of a csum item leaves
 572                          * enough room in the tree block for a single
 573                          * item header.  So, we split the item in place,
 574                          * adding a new header pointing to the existing
 575                          * bytes.  Then we loop around again and we have
 576                          * a nicely formed csum item that we can neatly
 577                          * truncate.
 578                          */
 579                         offset = (bytenr - key.offset) >> blocksize_bits;
 580                         offset *= csum_size;
 581
 582                         shift_len = (len >> blocksize_bits) * csum_size;
 583
 584                         item_offset = btrfs_item_ptr_offset(leaf,
 585                                                             path->slots[0]);
 586
 587                         memset_extent_buffer(leaf, 0, item_offset + offset,
 588                                              shift_len);
 589                         key.offset = bytenr;
 590
 591                         /*
 592                          * btrfs_split_item returns -EAGAIN when the
 593                          * item changed size or key
 594                          */
 595                         ret = btrfs_split_item(trans, root, path, &key, offset);
 596                         BUG_ON(ret && ret != -EAGAIN);
 597
 598                         key.offset = end_byte - 1;
 599                 } else {
 600                         ret = truncate_one_csum(trans, root, path,
 601                                                 &key, bytenr, len);
 602                         BUG_ON(ret);
 603                         if (key.offset < bytenr)
 604                                 break;
 605                 }
 606                 btrfs_release_path(root, path);
 607         }
 608 out:
 609         btrfs_free_path(path);
 610         return 0;
 611 }
 612
 613 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 614                            struct btrfs_root *root,
 615                            struct btrfs_ordered_sum *sums)
 616 {
 617         u64 bytenr;
 618         int ret;
 619         struct btrfs_key file_key;
 620         struct btrfs_key found_key;
 621         u64 next_offset;
 622         u64 total_bytes = 0;
 623         int found_next;
 624         struct btrfs_path *path;
 625         struct btrfs_csum_item *item;
 626         struct btrfs_csum_item *item_end;
 627         struct extent_buffer *leaf = NULL;
 628         u64 csum_offset;
 629         struct btrfs_sector_sum *sector_sum;
 630         u32 nritems;
 631         u32 ins_size;
 632         char *eb_map;
 633         char *eb_token;
 634         unsigned long map_len;
 635         unsigned long map_start;
 636         u16 csum_size =
 637                 btrfs_super_csum_size(&root->fs_info->super_copy);
 638
 639         path = btrfs_alloc_path();
 640         BUG_ON(!path);
 641         sector_sum = sums->sums;
 642 again:
 643         next_offset = (u64)-1;
 644         found_next = 0;
 645         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 646         file_key.offset = sector_sum->bytenr;
 647         bytenr = sector_sum->bytenr;
 648         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 649
 650         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 651         if (!IS_ERR(item)) {
 652                 leaf = path->nodes[0];
 653                 ret = 0;
 654                 goto found;
 655         }
 656         ret = PTR_ERR(item);
 657         if (ret == -EFBIG) {
 658                 u32 item_size;
 659                 /* we found one, but it isn't big enough yet */
 660                 leaf = path->nodes[0];
 661                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 662                 if ((item_size / csum_size) >=
 663                     MAX_CSUM_ITEMS(root, csum_size)) {
 664                         /* already at max size, make a new one */
 665                         goto insert;
 666                 }
 667         } else {
 668                 int slot = path->slots[0] + 1;
 669                 /* we didn't find a csum item, insert one */
 670                 nritems = btrfs_header_nritems(path->nodes[0]);
 671                 if (path->slots[0] >= nritems - 1) {
 672                         ret = btrfs_next_leaf(root, path);
 673                         if (ret == 1)
 674                                 found_next = 1;
 675                         if (ret != 0)
 676                                 goto insert;
 677                         slot = 0;
 678                 }
 679                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 680                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 681                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 682                         found_next = 1;
 683                         goto insert;
 684                 }
 685                 next_offset = found_key.offset;
 686                 found_next = 1;
 687                 goto insert;
 688         }
 689
 690         /*
 691          * at this point, we know the tree has an item, but it isn't big
 692          * enough yet to put our csum in.  Grow it
 693          */
 694         btrfs_release_path(root, path);
 695         ret = btrfs_search_slot(trans, root, &file_key, path,
 696                                 csum_size, 1);
 697         if (ret < 0)
 698                 goto fail_unlock;
 699
 700         if (ret > 0) {
 701                 if (path->slots[0] == 0)
 702                         goto insert;
 703                 path->slots[0]--;
 704         }
 705
 706         leaf = path->nodes[0];
 707         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 708         csum_offset = (bytenr - found_key.offset) >>
 709                         root->fs_info->sb->s_blocksize_bits;
 710
 711         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 712             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 713             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 714                 goto insert;
 715         }
 716
 717         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
 718             csum_size) {
 719                 u32 diff = (csum_offset + 1) * csum_size;
 720
 721                 /*
 722                  * is the item big enough already?  we dropped our lock
 723                  * before and need to recheck
 724                  */
 725                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
 726                         goto csum;
 727
 728                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 729                 if (diff != csum_size)
 730                         goto insert;
 731
 732                 ret = btrfs_extend_item(trans, root, path, diff);
 733                 BUG_ON(ret);
 734                 goto csum;
 735         }
 736
 737 insert:
 738         btrfs_release_path(root, path);
 739         csum_offset = 0;
 740         if (found_next) {
 741                 u64 tmp = total_bytes + root->sectorsize;
 742                 u64 next_sector = sector_sum->bytenr;
 743                 struct btrfs_sector_sum *next = sector_sum + 1;
 744
 745                 while (tmp < sums->len) {
 746                         if (next_sector + root->sectorsize != next->bytenr)
 747                                 break;
 748                         tmp += root->sectorsize;
 749                         next_sector = next->bytenr;
 750                         next++;
 751                 }
 752                 tmp = min(tmp, next_offset - file_key.offset);
 753                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 754                 tmp = max((u64)1, tmp);
 755                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 756                 ins_size = csum_size * tmp;
 757         } else {
 758                 ins_size = csum_size;
 759         }
 760         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 761                                       ins_size);
 762         if (ret < 0)
 763                 goto fail_unlock;
 764         if (ret != 0) {
 765                 WARN_ON(1);
 766                 goto fail_unlock;
 767         }
 768 csum:
 769         leaf = path->nodes[0];
 770         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 771         ret = 0;
 772         item = (struct btrfs_csum_item *)((unsigned char *)item +
 773                                           csum_offset * csum_size);
 774 found:
 775         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 776         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 777                                       btrfs_item_size_nr(leaf, path->slots[0]));
 778         eb_token = NULL;
 779         cond_resched();
 780 next_sector:
 781
 782         if (!eb_token ||
 783            (unsigned long)item + csum_size >= map_start + map_len) {
 784                 int err;
 785
 786                 if (eb_token)
 787                         unmap_extent_buffer(leaf, eb_token, KM_USER1);
 788                 eb_token = NULL;
 789                 err = map_private_extent_buffer(leaf, (unsigned long)item,
 790                                                 csum_size,
 791                                                 &eb_token, &eb_map,
 792                                                 &map_start, &map_len, KM_USER1);
 793                 if (err)
 794                         eb_token = NULL;
 795         }
 796         if (eb_token) {
 797                 memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
 798                        &sector_sum->sum, csum_size);
 799         } else {
 800                 write_extent_buffer(leaf, &sector_sum->sum,
 801                                     (unsigned long)item, csum_size);
 802         }
 803
 804         total_bytes += root->sectorsize;
 805         sector_sum++;
 806         if (total_bytes < sums->len) {
 807                 item = (struct btrfs_csum_item *)((char *)item +
 808                                                   csum_size);
 809                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 810                     sector_sum->bytenr) {
 811                         bytenr = sector_sum->bytenr;
 812                         goto next_sector;
 813                 }
 814         }
 815         if (eb_token) {
 816                 unmap_extent_buffer(leaf, eb_token, KM_USER1);
 817                 eb_token = NULL;
 818         }
 819         btrfs_mark_buffer_dirty(path->nodes[0]);
 820         cond_resched();
 821         if (total_bytes < sums->len) {
 822                 btrfs_release_path(root, path);
 823                 goto again;
 824         }
 825 out:
 826         btrfs_free_path(path);
 827         return ret;
 828
 829 fail_unlock:
 830         goto out;
 831 }