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