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         if (!path)
  52                 return -ENOMEM;
  53         file_key.objectid = objectid;
  54         file_key.offset = pos;
  55         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
  56
  57         path->leave_spinning = 1;
  58         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  59                                       sizeof(*item));
  60         if (ret < 0)
  61                 goto out;
  62         BUG_ON(ret);
  63         leaf = path->nodes[0];
  64         item = btrfs_item_ptr(leaf, path->slots[0],
  65                               struct btrfs_file_extent_item);
  66         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  67         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  68         btrfs_set_file_extent_offset(leaf, item, offset);
  69         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  70         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  71         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  72         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  73         btrfs_set_file_extent_compression(leaf, item, compression);
  74         btrfs_set_file_extent_encryption(leaf, item, encryption);
  75         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  76
  77         btrfs_mark_buffer_dirty(leaf);
  78 out:
  79         btrfs_free_path(path);
  80         return ret;
  81 }
  82
  83 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  84                                           struct btrfs_root *root,
  85                                           struct btrfs_path *path,
  86                                           u64 bytenr, int cow)
  87 {
  88         int ret;
  89         struct btrfs_key file_key;
  90         struct btrfs_key found_key;
  91         struct btrfs_csum_item *item;
  92         struct extent_buffer *leaf;
  93         u64 csum_offset = 0;
  94         u16 csum_size =
  95                 btrfs_super_csum_size(&root->fs_info->super_copy);
  96         int csums_in_item;
  97
  98         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
  99         file_key.offset = bytenr;
 100         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 101         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 102         if (ret < 0)
 103                 goto fail;
 104         leaf = path->nodes[0];
 105         if (ret > 0) {
 106                 ret = 1;
 107                 if (path->slots[0] == 0)
 108                         goto fail;
 109                 path->slots[0]--;
 110                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 111                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
 112                         goto fail;
 113
 114                 csum_offset = (bytenr - found_key.offset) >>
 115                                 root->fs_info->sb->s_blocksize_bits;
 116                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 117                 csums_in_item /= csum_size;
 118
 119                 if (csum_offset >= csums_in_item) {
 120                         ret = -EFBIG;
 121                         goto fail;
 122                 }
 123         }
 124         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 125         item = (struct btrfs_csum_item *)((unsigned char *)item +
 126                                           csum_offset * csum_size);
 127         return item;
 128 fail:
 129         if (ret > 0)
 130                 ret = -ENOENT;
 131         return ERR_PTR(ret);
 132 }
 133
 134
 135 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 136                              struct btrfs_root *root,
 137                              struct btrfs_path *path, u64 objectid,
 138                              u64 offset, int mod)
 139 {
 140         int ret;
 141         struct btrfs_key file_key;
 142         int ins_len = mod < 0 ? -1 : 0;
 143         int cow = mod != 0;
 144
 145         file_key.objectid = objectid;
 146         file_key.offset = offset;
 147         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 148         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 149         return ret;
 150 }
 151
 152
 153 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 154                                    struct inode *inode, struct bio *bio,
 155                                    u64 logical_offset, u32 *dst, int dio)
 156 {
 157         u32 sum;
 158         struct bio_vec *bvec = bio->bi_io_vec;
 159         int bio_index = 0;
 160         u64 offset = 0;
 161         u64 item_start_offset = 0;
 162         u64 item_last_offset = 0;
 163         u64 disk_bytenr;
 164         u32 diff;
 165         u16 csum_size =
 166                 btrfs_super_csum_size(&root->fs_info->super_copy);
 167         int ret;
 168         struct btrfs_path *path;
 169         struct btrfs_csum_item *item = NULL;
 170         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 171
 172         path = btrfs_alloc_path();
 173         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 174                 path->reada = 2;
 175
 176         WARN_ON(bio->bi_vcnt <= 0);
 177
 178         disk_bytenr = (u64)bio->bi_sector << 9;
 179         if (dio)
 180                 offset = logical_offset;
 181         while (bio_index < bio->bi_vcnt) {
 182                 if (!dio)
 183                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 184                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
 185                 if (ret == 0)
 186                         goto found;
 187
 188                 if (!item || disk_bytenr < item_start_offset ||
 189                     disk_bytenr >= item_last_offset) {
 190                         struct btrfs_key found_key;
 191                         u32 item_size;
 192
 193                         if (item)
 194                                 btrfs_release_path(root, path);
 195                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 196                                                  path, disk_bytenr, 0);
 197                         if (IS_ERR(item)) {
 198                                 ret = PTR_ERR(item);
 199                                 if (ret == -ENOENT || ret == -EFBIG)
 200                                         ret = 0;
 201                                 sum = 0;
 202                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 203                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 204                                         set_extent_bits(io_tree, offset,
 205                                                 offset + bvec->bv_len - 1,
 206                                                 EXTENT_NODATASUM, GFP_NOFS);
 207                                 } else {
 208                                         printk(KERN_INFO "btrfs no csum found "
 209                                                "for inode %lu start %llu\n",
 210                                                inode->i_ino,
 211                                                (unsigned long long)offset);
 212                                 }
 213                                 item = NULL;
 214                                 btrfs_release_path(root, path);
 215                                 goto found;
 216                         }
 217                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 218                                               path->slots[0]);
 219
 220                         item_start_offset = found_key.offset;
 221                         item_size = btrfs_item_size_nr(path->nodes[0],
 222                                                        path->slots[0]);
 223                         item_last_offset = item_start_offset +
 224                                 (item_size / csum_size) *
 225                                 root->sectorsize;
 226                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 227                                               struct btrfs_csum_item);
 228                 }
 229                 /*
 230                  * this byte range must be able to fit inside
 231                  * a single leaf so it will also fit inside a u32
 232                  */
 233                 diff = disk_bytenr - item_start_offset;
 234                 diff = diff / root->sectorsize;
 235                 diff = diff * csum_size;
 236
 237                 read_extent_buffer(path->nodes[0], &sum,
 238                                    ((unsigned long)item) + diff,
 239                                    csum_size);
 240 found:
 241                 if (dst)
 242                         *dst++ = sum;
 243                 else
 244                         set_state_private(io_tree, offset, sum);
 245                 disk_bytenr += bvec->bv_len;
 246                 offset += bvec->bv_len;
 247                 bio_index++;
 248                 bvec++;
 249         }
 250         btrfs_free_path(path);
 251         return 0;
 252 }
 253
 254 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 255                           struct bio *bio, u32 *dst)
 256 {
 257         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 258 }
 259
 260 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 261                               struct bio *bio, u64 offset, u32 *dst)
 262 {
 263         return __btrfs_lookup_bio_sums(root, inode, bio, offset, dst, 1);
 264 }
 265
 266 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 267                              struct list_head *list)
 268 {
 269         struct btrfs_key key;
 270         struct btrfs_path *path;
 271         struct extent_buffer *leaf;
 272         struct btrfs_ordered_sum *sums;
 273         struct btrfs_sector_sum *sector_sum;
 274         struct btrfs_csum_item *item;
 275         unsigned long offset;
 276         int ret;
 277         size_t size;
 278         u64 csum_end;
 279         u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
 280
 281         path = btrfs_alloc_path();
 282         BUG_ON(!path);
 283
 284         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 285         key.offset = start;
 286         key.type = BTRFS_EXTENT_CSUM_KEY;
 287
 288         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 289         if (ret < 0)
 290                 goto fail;
 291         if (ret > 0 && path->slots[0] > 0) {
 292                 leaf = path->nodes[0];
 293                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 294                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 295                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 296                         offset = (start - key.offset) >>
 297                                  root->fs_info->sb->s_blocksize_bits;
 298                         if (offset * csum_size <
 299                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 300                                 path->slots[0]--;
 301                 }
 302         }
 303
 304         while (start <= end) {
 305                 leaf = path->nodes[0];
 306                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 307                         ret = btrfs_next_leaf(root, path);
 308                         if (ret < 0)
 309                                 goto fail;
 310                         if (ret > 0)
 311                                 break;
 312                         leaf = path->nodes[0];
 313                 }
 314
 315                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 316                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 317                     key.type != BTRFS_EXTENT_CSUM_KEY)
 318                         break;
 319
 320                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 321                 if (key.offset > end)
 322                         break;
 323
 324                 if (key.offset > start)
 325                         start = key.offset;
 326
 327                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 328                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 329                 if (csum_end <= start) {
 330                         path->slots[0]++;
 331                         continue;
 332                 }
 333
 334                 csum_end = min(csum_end, end + 1);
 335                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 336                                       struct btrfs_csum_item);
 337                 while (start < csum_end) {
 338                         size = min_t(size_t, csum_end - start,
 339                                         MAX_ORDERED_SUM_BYTES(root));
 340                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 341                                         GFP_NOFS);
 342                         BUG_ON(!sums);
 343
 344                         sector_sum = sums->sums;
 345                         sums->bytenr = start;
 346                         sums->len = size;
 347
 348                         offset = (start - key.offset) >>
 349                                 root->fs_info->sb->s_blocksize_bits;
 350                         offset *= csum_size;
 351
 352                         while (size > 0) {
 353                                 read_extent_buffer(path->nodes[0],
 354                                                 &sector_sum->sum,
 355                                                 ((unsigned long)item) +
 356                                                 offset, csum_size);
 357                                 sector_sum->bytenr = start;
 358
 359                                 size -= root->sectorsize;
 360                                 start += root->sectorsize;
 361                                 offset += csum_size;
 362                                 sector_sum++;
 363                         }
 364                         list_add_tail(&sums->list, list);
 365                 }
 366                 path->slots[0]++;
 367         }
 368         ret = 0;
 369 fail:
 370         btrfs_free_path(path);
 371         return ret;
 372 }
 373
 374 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 375                        struct bio *bio, u64 file_start, int contig)
 376 {
 377         struct btrfs_ordered_sum *sums;
 378         struct btrfs_sector_sum *sector_sum;
 379         struct btrfs_ordered_extent *ordered;
 380         char *data;
 381         struct bio_vec *bvec = bio->bi_io_vec;
 382         int bio_index = 0;
 383         unsigned long total_bytes = 0;
 384         unsigned long this_sum_bytes = 0;
 385         u64 offset;
 386         u64 disk_bytenr;
 387
 388         WARN_ON(bio->bi_vcnt <= 0);
 389         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 390         if (!sums)
 391                 return -ENOMEM;
 392
 393         sector_sum = sums->sums;
 394         disk_bytenr = (u64)bio->bi_sector << 9;
 395         sums->len = bio->bi_size;
 396         INIT_LIST_HEAD(&sums->list);
 397
 398         if (contig)
 399                 offset = file_start;
 400         else
 401                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 402
 403         ordered = btrfs_lookup_ordered_extent(inode, offset);
 404         BUG_ON(!ordered);
 405         sums->bytenr = ordered->start;
 406
 407         while (bio_index < bio->bi_vcnt) {
 408                 if (!contig)
 409                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 410
 411                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
 412                     offset < ordered->file_offset)) {
 413                         unsigned long bytes_left;
 414                         sums->len = this_sum_bytes;
 415                         this_sum_bytes = 0;
 416                         btrfs_add_ordered_sum(inode, ordered, sums);
 417                         btrfs_put_ordered_extent(ordered);
 418
 419                         bytes_left = bio->bi_size - total_bytes;
 420
 421                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 422                                        GFP_NOFS);
 423                         BUG_ON(!sums);
 424                         sector_sum = sums->sums;
 425                         sums->len = bytes_left;
 426                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 427                         BUG_ON(!ordered);
 428                         sums->bytenr = ordered->start;
 429                 }
 430
 431                 data = kmap_atomic(bvec->bv_page, KM_USER0);
 432                 sector_sum->sum = ~(u32)0;
 433                 sector_sum->sum = btrfs_csum_data(root,
 434                                                   data + bvec->bv_offset,
 435                                                   sector_sum->sum,
 436                                                   bvec->bv_len);
 437                 kunmap_atomic(data, KM_USER0);
 438                 btrfs_csum_final(sector_sum->sum,
 439                                  (char *)&sector_sum->sum);
 440                 sector_sum->bytenr = disk_bytenr;
 441
 442                 sector_sum++;
 443                 bio_index++;
 444                 total_bytes += bvec->bv_len;
 445                 this_sum_bytes += bvec->bv_len;
 446                 disk_bytenr += bvec->bv_len;
 447                 offset += bvec->bv_len;
 448                 bvec++;
 449         }
 450         this_sum_bytes = 0;
 451         btrfs_add_ordered_sum(inode, ordered, sums);
 452         btrfs_put_ordered_extent(ordered);
 453         return 0;
 454 }
 455
 456 /*
 457  * helper function for csum removal, this expects the
 458  * key to describe the csum pointed to by the path, and it expects
 459  * the csum to overlap the range [bytenr, len]
 460  *
 461  * The csum should not be entirely contained in the range and the
 462  * range should not be entirely contained in the csum.
 463  *
 464  * This calls btrfs_truncate_item with the correct args based on the
 465  * overlap, and fixes up the key as required.
 466  */
 467 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
 468                                       struct btrfs_root *root,
 469                                       struct btrfs_path *path,
 470                                       struct btrfs_key *key,
 471                                       u64 bytenr, u64 len)
 472 {
 473         struct extent_buffer *leaf;
 474         u16 csum_size =
 475                 btrfs_super_csum_size(&root->fs_info->super_copy);
 476         u64 csum_end;
 477         u64 end_byte = bytenr + len;
 478         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 479         int ret;
 480
 481         leaf = path->nodes[0];
 482         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 483         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 484         csum_end += key->offset;
 485
 486         if (key->offset < bytenr && csum_end <= end_byte) {
 487                 /*
 488                  *         [ bytenr - len ]
 489                  *         [   ]
 490                  *   [csum     ]
 491                  *   A simple truncate off the end of the item
 492                  */
 493                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 494                 new_size *= csum_size;
 495                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
 496                 BUG_ON(ret);
 497         } else if (key->offset >= bytenr && csum_end > end_byte &&
 498                    end_byte > key->offset) {
 499                 /*
 500                  *         [ bytenr - len ]
 501                  *                 [ ]
 502                  *                 [csum     ]
 503                  * we need to truncate from the beginning of the csum
 504                  */
 505                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 506                 new_size *= csum_size;
 507
 508                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
 509                 BUG_ON(ret);
 510
 511                 key->offset = end_byte;
 512                 ret = btrfs_set_item_key_safe(trans, root, path, key);
 513                 BUG_ON(ret);
 514         } else {
 515                 BUG();
 516         }
 517         return 0;
 518 }
 519
 520 /*
 521  * deletes the csum items from the csum tree for a given
 522  * range of bytes.
 523  */
 524 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 525                     struct btrfs_root *root, u64 bytenr, u64 len)
 526 {
 527         struct btrfs_path *path;
 528         struct btrfs_key key;
 529         u64 end_byte = bytenr + len;
 530         u64 csum_end;
 531         struct extent_buffer *leaf;
 532         int ret;
 533         u16 csum_size =
 534                 btrfs_super_csum_size(&root->fs_info->super_copy);
 535         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 536
 537         root = root->fs_info->csum_root;
 538
 539         path = btrfs_alloc_path();
 540         if (!path)
 541                 return -ENOMEM;
 542
 543         while (1) {
 544                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 545                 key.offset = end_byte - 1;
 546                 key.type = BTRFS_EXTENT_CSUM_KEY;
 547
 548                 path->leave_spinning = 1;
 549                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 550                 if (ret > 0) {
 551                         if (path->slots[0] == 0)
 552                                 goto out;
 553                         path->slots[0]--;
 554                 } else if (ret < 0) {
 555                         goto out;
 556                 }
 557
 558                 leaf = path->nodes[0];
 559                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 560
 561                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 562                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 563                         break;
 564                 }
 565
 566                 if (key.offset >= end_byte)
 567                         break;
 568
 569                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 570                 csum_end <<= blocksize_bits;
 571                 csum_end += key.offset;
 572
 573                 /* this csum ends before we start, we're done */
 574                 if (csum_end <= bytenr)
 575                         break;
 576
 577                 /* delete the entire item, it is inside our range */
 578                 if (key.offset >= bytenr && csum_end <= end_byte) {
 579                         ret = btrfs_del_item(trans, root, path);
 580                         BUG_ON(ret);
 581                         if (key.offset == bytenr)
 582                                 break;
 583                 } else if (key.offset < bytenr && csum_end > end_byte) {
 584                         unsigned long offset;
 585                         unsigned long shift_len;
 586                         unsigned long item_offset;
 587                         /*
 588                          *        [ bytenr - len ]
 589                          *     [csum                ]
 590                          *
 591                          * Our bytes are in the middle of the csum,
 592                          * we need to split this item and insert a new one.
 593                          *
 594                          * But we can't drop the path because the
 595                          * csum could change, get removed, extended etc.
 596                          *
 597                          * The trick here is the max size of a csum item leaves
 598                          * enough room in the tree block for a single
 599                          * item header.  So, we split the item in place,
 600                          * adding a new header pointing to the existing
 601                          * bytes.  Then we loop around again and we have
 602                          * a nicely formed csum item that we can neatly
 603                          * truncate.
 604                          */
 605                         offset = (bytenr - key.offset) >> blocksize_bits;
 606                         offset *= csum_size;
 607
 608                         shift_len = (len >> blocksize_bits) * csum_size;
 609
 610                         item_offset = btrfs_item_ptr_offset(leaf,
 611                                                             path->slots[0]);
 612
 613                         memset_extent_buffer(leaf, 0, item_offset + offset,
 614                                              shift_len);
 615                         key.offset = bytenr;
 616
 617                         /*
 618                          * btrfs_split_item returns -EAGAIN when the
 619                          * item changed size or key
 620                          */
 621                         ret = btrfs_split_item(trans, root, path, &key, offset);
 622                         BUG_ON(ret && ret != -EAGAIN);
 623
 624                         key.offset = end_byte - 1;
 625                 } else {
 626                         ret = truncate_one_csum(trans, root, path,
 627                                                 &key, bytenr, len);
 628                         BUG_ON(ret);
 629                         if (key.offset < bytenr)
 630                                 break;
 631                 }
 632                 btrfs_release_path(root, path);
 633         }
 634 out:
 635         btrfs_free_path(path);
 636         return 0;
 637 }
 638
 639 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 640                            struct btrfs_root *root,
 641                            struct btrfs_ordered_sum *sums)
 642 {
 643         u64 bytenr;
 644         int ret;
 645         struct btrfs_key file_key;
 646         struct btrfs_key found_key;
 647         u64 next_offset;
 648         u64 total_bytes = 0;
 649         int found_next;
 650         struct btrfs_path *path;
 651         struct btrfs_csum_item *item;
 652         struct btrfs_csum_item *item_end;
 653         struct extent_buffer *leaf = NULL;
 654         u64 csum_offset;
 655         struct btrfs_sector_sum *sector_sum;
 656         u32 nritems;
 657         u32 ins_size;
 658         char *eb_map;
 659         char *eb_token;
 660         unsigned long map_len;
 661         unsigned long map_start;
 662         u16 csum_size =
 663                 btrfs_super_csum_size(&root->fs_info->super_copy);
 664
 665         path = btrfs_alloc_path();
 666         BUG_ON(!path);
 667         sector_sum = sums->sums;
 668 again:
 669         next_offset = (u64)-1;
 670         found_next = 0;
 671         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 672         file_key.offset = sector_sum->bytenr;
 673         bytenr = sector_sum->bytenr;
 674         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 675
 676         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 677         if (!IS_ERR(item)) {
 678                 leaf = path->nodes[0];
 679                 ret = 0;
 680                 goto found;
 681         }
 682         ret = PTR_ERR(item);
 683         if (ret != -EFBIG && ret != -ENOENT)
 684                 goto fail_unlock;
 685
 686         if (ret == -EFBIG) {
 687                 u32 item_size;
 688                 /* we found one, but it isn't big enough yet */
 689                 leaf = path->nodes[0];
 690                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 691                 if ((item_size / csum_size) >=
 692                     MAX_CSUM_ITEMS(root, csum_size)) {
 693                         /* already at max size, make a new one */
 694                         goto insert;
 695                 }
 696         } else {
 697                 int slot = path->slots[0] + 1;
 698                 /* we didn't find a csum item, insert one */
 699                 nritems = btrfs_header_nritems(path->nodes[0]);
 700                 if (path->slots[0] >= nritems - 1) {
 701                         ret = btrfs_next_leaf(root, path);
 702                         if (ret == 1)
 703                                 found_next = 1;
 704                         if (ret != 0)
 705                                 goto insert;
 706                         slot = 0;
 707                 }
 708                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 709                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 710                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 711                         found_next = 1;
 712                         goto insert;
 713                 }
 714                 next_offset = found_key.offset;
 715                 found_next = 1;
 716                 goto insert;
 717         }
 718
 719         /*
 720          * at this point, we know the tree has an item, but it isn't big
 721          * enough yet to put our csum in.  Grow it
 722          */
 723         btrfs_release_path(root, path);
 724         ret = btrfs_search_slot(trans, root, &file_key, path,
 725                                 csum_size, 1);
 726         if (ret < 0)
 727                 goto fail_unlock;
 728
 729         if (ret > 0) {
 730                 if (path->slots[0] == 0)
 731                         goto insert;
 732                 path->slots[0]--;
 733         }
 734
 735         leaf = path->nodes[0];
 736         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 737         csum_offset = (bytenr - found_key.offset) >>
 738                         root->fs_info->sb->s_blocksize_bits;
 739
 740         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 741             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 742             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 743                 goto insert;
 744         }
 745
 746         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
 747             csum_size) {
 748                 u32 diff = (csum_offset + 1) * csum_size;
 749
 750                 /*
 751                  * is the item big enough already?  we dropped our lock
 752                  * before and need to recheck
 753                  */
 754                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
 755                         goto csum;
 756
 757                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 758                 if (diff != csum_size)
 759                         goto insert;
 760
 761                 ret = btrfs_extend_item(trans, root, path, diff);
 762                 BUG_ON(ret);
 763                 goto csum;
 764         }
 765
 766 insert:
 767         btrfs_release_path(root, path);
 768         csum_offset = 0;
 769         if (found_next) {
 770                 u64 tmp = total_bytes + root->sectorsize;
 771                 u64 next_sector = sector_sum->bytenr;
 772                 struct btrfs_sector_sum *next = sector_sum + 1;
 773
 774                 while (tmp < sums->len) {
 775                         if (next_sector + root->sectorsize != next->bytenr)
 776                                 break;
 777                         tmp += root->sectorsize;
 778                         next_sector = next->bytenr;
 779                         next++;
 780                 }
 781                 tmp = min(tmp, next_offset - file_key.offset);
 782                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 783                 tmp = max((u64)1, tmp);
 784                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 785                 ins_size = csum_size * tmp;
 786         } else {
 787                 ins_size = csum_size;
 788         }
 789         path->leave_spinning = 1;
 790         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 791                                       ins_size);
 792         path->leave_spinning = 0;
 793         if (ret < 0)
 794                 goto fail_unlock;
 795         if (ret != 0) {
 796                 WARN_ON(1);
 797                 goto fail_unlock;
 798         }
 799 csum:
 800         leaf = path->nodes[0];
 801         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 802         ret = 0;
 803         item = (struct btrfs_csum_item *)((unsigned char *)item +
 804                                           csum_offset * csum_size);
 805 found:
 806         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 807         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 808                                       btrfs_item_size_nr(leaf, path->slots[0]));
 809         eb_token = NULL;
 810 next_sector:
 811
 812         if (!eb_token ||
 813            (unsigned long)item + csum_size >= map_start + map_len) {
 814                 int err;
 815
 816                 if (eb_token)
 817                         unmap_extent_buffer(leaf, eb_token, KM_USER1);
 818                 eb_token = NULL;
 819                 err = map_private_extent_buffer(leaf, (unsigned long)item,
 820                                                 csum_size,
 821                                                 &eb_token, &eb_map,
 822                                                 &map_start, &map_len, KM_USER1);
 823                 if (err)
 824                         eb_token = NULL;
 825         }
 826         if (eb_token) {
 827                 memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
 828                        &sector_sum->sum, csum_size);
 829         } else {
 830                 write_extent_buffer(leaf, &sector_sum->sum,
 831                                     (unsigned long)item, csum_size);
 832         }
 833
 834         total_bytes += root->sectorsize;
 835         sector_sum++;
 836         if (total_bytes < sums->len) {
 837                 item = (struct btrfs_csum_item *)((char *)item +
 838                                                   csum_size);
 839                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 840                     sector_sum->bytenr) {
 841                         bytenr = sector_sum->bytenr;
 842                         goto next_sector;
 843                 }
 844         }
 845         if (eb_token) {
 846                 unmap_extent_buffer(leaf, eb_token, KM_USER1);
 847                 eb_token = NULL;
 848         }
 849         btrfs_mark_buffer_dirty(path->nodes[0]);
 850         if (total_bytes < sums->len) {
 851                 btrfs_release_path(root, path);
 852                 cond_resched();
 853                 goto again;
 854         }
 855 out:
 856         btrfs_free_path(path);
 857         return ret;
 858
 859 fail_unlock:
 860         goto out;
 861 }