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