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 (!path)
 174                 return -ENOMEM;
 175         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 176                 path->reada = 2;
 177
 178         WARN_ON(bio->bi_vcnt <= 0);
 179
 180         disk_bytenr = (u64)bio->bi_sector << 9;
 181         if (dio)
 182                 offset = logical_offset;
 183         while (bio_index < bio->bi_vcnt) {
 184                 if (!dio)
 185                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 186                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
 187                 if (ret == 0)
 188                         goto found;
 189
 190                 if (!item || disk_bytenr < item_start_offset ||
 191                     disk_bytenr >= item_last_offset) {
 192                         struct btrfs_key found_key;
 193                         u32 item_size;
 194
 195                         if (item)
 196                                 btrfs_release_path(path);
 197                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 198                                                  path, disk_bytenr, 0);
 199                         if (IS_ERR(item)) {
 200                                 ret = PTR_ERR(item);
 201                                 if (ret == -ENOENT || ret == -EFBIG)
 202                                         ret = 0;
 203                                 sum = 0;
 204                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 205                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 206                                         set_extent_bits(io_tree, offset,
 207                                                 offset + bvec->bv_len - 1,
 208                                                 EXTENT_NODATASUM, GFP_NOFS);
 209                                 } else {
 210                                         printk(KERN_INFO "btrfs no csum found "
 211                                                "for inode %lu start %llu\n",
 212                                                inode->i_ino,
 213                                                (unsigned long long)offset);
 214                                 }
 215                                 item = NULL;
 216                                 btrfs_release_path(path);
 217                                 goto found;
 218                         }
 219                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 220                                               path->slots[0]);
 221
 222                         item_start_offset = found_key.offset;
 223                         item_size = btrfs_item_size_nr(path->nodes[0],
 224                                                        path->slots[0]);
 225                         item_last_offset = item_start_offset +
 226                                 (item_size / csum_size) *
 227                                 root->sectorsize;
 228                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 229                                               struct btrfs_csum_item);
 230                 }
 231                 /*
 232                  * this byte range must be able to fit inside
 233                  * a single leaf so it will also fit inside a u32
 234                  */
 235                 diff = disk_bytenr - item_start_offset;
 236                 diff = diff / root->sectorsize;
 237                 diff = diff * csum_size;
 238
 239                 read_extent_buffer(path->nodes[0], &sum,
 240                                    ((unsigned long)item) + diff,
 241                                    csum_size);
 242 found:
 243                 if (dst)
 244                         *dst++ = sum;
 245                 else
 246                         set_state_private(io_tree, offset, sum);
 247                 disk_bytenr += bvec->bv_len;
 248                 offset += bvec->bv_len;
 249                 bio_index++;
 250                 bvec++;
 251         }
 252         btrfs_free_path(path);
 253         return 0;
 254 }
 255
 256 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 257                           struct bio *bio, u32 *dst)
 258 {
 259         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 260 }
 261
 262 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 263                               struct bio *bio, u64 offset, u32 *dst)
 264 {
 265         return __btrfs_lookup_bio_sums(root, inode, bio, offset, dst, 1);
 266 }
 267
 268 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 269                              struct list_head *list)
 270 {
 271         struct btrfs_key key;
 272         struct btrfs_path *path;
 273         struct extent_buffer *leaf;
 274         struct btrfs_ordered_sum *sums;
 275         struct btrfs_sector_sum *sector_sum;
 276         struct btrfs_csum_item *item;
 277         unsigned long offset;
 278         int ret;
 279         size_t size;
 280         u64 csum_end;
 281         u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
 282
 283         path = btrfs_alloc_path();
 284         BUG_ON(!path);
 285
 286         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 287         key.offset = start;
 288         key.type = BTRFS_EXTENT_CSUM_KEY;
 289
 290         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 291         if (ret < 0)
 292                 goto fail;
 293         if (ret > 0 && path->slots[0] > 0) {
 294                 leaf = path->nodes[0];
 295                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 296                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 297                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 298                         offset = (start - key.offset) >>
 299                                  root->fs_info->sb->s_blocksize_bits;
 300                         if (offset * csum_size <
 301                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 302                                 path->slots[0]--;
 303                 }
 304         }
 305
 306         while (start <= end) {
 307                 leaf = path->nodes[0];
 308                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 309                         ret = btrfs_next_leaf(root, path);
 310                         if (ret < 0)
 311                                 goto fail;
 312                         if (ret > 0)
 313                                 break;
 314                         leaf = path->nodes[0];
 315                 }
 316
 317                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 318                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 319                     key.type != BTRFS_EXTENT_CSUM_KEY)
 320                         break;
 321
 322                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 323                 if (key.offset > end)
 324                         break;
 325
 326                 if (key.offset > start)
 327                         start = key.offset;
 328
 329                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 330                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 331                 if (csum_end <= start) {
 332                         path->slots[0]++;
 333                         continue;
 334                 }
 335
 336                 csum_end = min(csum_end, end + 1);
 337                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 338                                       struct btrfs_csum_item);
 339                 while (start < csum_end) {
 340                         size = min_t(size_t, csum_end - start,
 341                                         MAX_ORDERED_SUM_BYTES(root));
 342                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 343                                         GFP_NOFS);
 344                         BUG_ON(!sums);
 345
 346                         sector_sum = sums->sums;
 347                         sums->bytenr = start;
 348                         sums->len = size;
 349
 350                         offset = (start - key.offset) >>
 351                                 root->fs_info->sb->s_blocksize_bits;
 352                         offset *= csum_size;
 353
 354                         while (size > 0) {
 355                                 read_extent_buffer(path->nodes[0],
 356                                                 &sector_sum->sum,
 357                                                 ((unsigned long)item) +
 358                                                 offset, csum_size);
 359                                 sector_sum->bytenr = start;
 360
 361                                 size -= root->sectorsize;
 362                                 start += root->sectorsize;
 363                                 offset += csum_size;
 364                                 sector_sum++;
 365                         }
 366                         list_add_tail(&sums->list, list);
 367                 }
 368                 path->slots[0]++;
 369         }
 370         ret = 0;
 371 fail:
 372         btrfs_free_path(path);
 373         return ret;
 374 }
 375
 376 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 377                        struct bio *bio, u64 file_start, int contig)
 378 {
 379         struct btrfs_ordered_sum *sums;
 380         struct btrfs_sector_sum *sector_sum;
 381         struct btrfs_ordered_extent *ordered;
 382         char *data;
 383         struct bio_vec *bvec = bio->bi_io_vec;
 384         int bio_index = 0;
 385         unsigned long total_bytes = 0;
 386         unsigned long this_sum_bytes = 0;
 387         u64 offset;
 388         u64 disk_bytenr;
 389
 390         WARN_ON(bio->bi_vcnt <= 0);
 391         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 392         if (!sums)
 393                 return -ENOMEM;
 394
 395         sector_sum = sums->sums;
 396         disk_bytenr = (u64)bio->bi_sector << 9;
 397         sums->len = bio->bi_size;
 398         INIT_LIST_HEAD(&sums->list);
 399
 400         if (contig)
 401                 offset = file_start;
 402         else
 403                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 404
 405         ordered = btrfs_lookup_ordered_extent(inode, offset);
 406         BUG_ON(!ordered);
 407         sums->bytenr = ordered->start;
 408
 409         while (bio_index < bio->bi_vcnt) {
 410                 if (!contig)
 411                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 412
 413                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
 414                     offset < ordered->file_offset)) {
 415                         unsigned long bytes_left;
 416                         sums->len = this_sum_bytes;
 417                         this_sum_bytes = 0;
 418                         btrfs_add_ordered_sum(inode, ordered, sums);
 419                         btrfs_put_ordered_extent(ordered);
 420
 421                         bytes_left = bio->bi_size - total_bytes;
 422
 423                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 424                                        GFP_NOFS);
 425                         BUG_ON(!sums);
 426                         sector_sum = sums->sums;
 427                         sums->len = bytes_left;
 428                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 429                         BUG_ON(!ordered);
 430                         sums->bytenr = ordered->start;
 431                 }
 432
 433                 data = kmap_atomic(bvec->bv_page, KM_USER0);
 434                 sector_sum->sum = ~(u32)0;
 435                 sector_sum->sum = btrfs_csum_data(root,
 436                                                   data + bvec->bv_offset,
 437                                                   sector_sum->sum,
 438                                                   bvec->bv_len);
 439                 kunmap_atomic(data, KM_USER0);
 440                 btrfs_csum_final(sector_sum->sum,
 441                                  (char *)&sector_sum->sum);
 442                 sector_sum->bytenr = disk_bytenr;
 443
 444                 sector_sum++;
 445                 bio_index++;
 446                 total_bytes += bvec->bv_len;
 447                 this_sum_bytes += bvec->bv_len;
 448                 disk_bytenr += bvec->bv_len;
 449                 offset += bvec->bv_len;
 450                 bvec++;
 451         }
 452         this_sum_bytes = 0;
 453         btrfs_add_ordered_sum(inode, ordered, sums);
 454         btrfs_put_ordered_extent(ordered);
 455         return 0;
 456 }
 457
 458 /*
 459  * helper function for csum removal, this expects the
 460  * key to describe the csum pointed to by the path, and it expects
 461  * the csum to overlap the range [bytenr, len]
 462  *
 463  * The csum should not be entirely contained in the range and the
 464  * range should not be entirely contained in the csum.
 465  *
 466  * This calls btrfs_truncate_item with the correct args based on the
 467  * overlap, and fixes up the key as required.
 468  */
 469 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
 470                                       struct btrfs_root *root,
 471                                       struct btrfs_path *path,
 472                                       struct btrfs_key *key,
 473                                       u64 bytenr, u64 len)
 474 {
 475         struct extent_buffer *leaf;
 476         u16 csum_size =
 477                 btrfs_super_csum_size(&root->fs_info->super_copy);
 478         u64 csum_end;
 479         u64 end_byte = bytenr + len;
 480         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 481         int ret;
 482
 483         leaf = path->nodes[0];
 484         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 485         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 486         csum_end += key->offset;
 487
 488         if (key->offset < bytenr && csum_end <= end_byte) {
 489                 /*
 490                  *         [ bytenr - len ]
 491                  *         [   ]
 492                  *   [csum     ]
 493                  *   A simple truncate off the end of the item
 494                  */
 495                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 496                 new_size *= csum_size;
 497                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
 498                 BUG_ON(ret);
 499         } else if (key->offset >= bytenr && csum_end > end_byte &&
 500                    end_byte > key->offset) {
 501                 /*
 502                  *         [ bytenr - len ]
 503                  *                 [ ]
 504                  *                 [csum     ]
 505                  * we need to truncate from the beginning of the csum
 506                  */
 507                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 508                 new_size *= csum_size;
 509
 510                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
 511                 BUG_ON(ret);
 512
 513                 key->offset = end_byte;
 514                 ret = btrfs_set_item_key_safe(trans, root, path, key);
 515                 BUG_ON(ret);
 516         } else {
 517                 BUG();
 518         }
 519         return 0;
 520 }
 521
 522 /*
 523  * deletes the csum items from the csum tree for a given
 524  * range of bytes.
 525  */
 526 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 527                     struct btrfs_root *root, u64 bytenr, u64 len)
 528 {
 529         struct btrfs_path *path;
 530         struct btrfs_key key;
 531         u64 end_byte = bytenr + len;
 532         u64 csum_end;
 533         struct extent_buffer *leaf;
 534         int ret;
 535         u16 csum_size =
 536                 btrfs_super_csum_size(&root->fs_info->super_copy);
 537         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 538
 539         root = root->fs_info->csum_root;
 540
 541         path = btrfs_alloc_path();
 542         if (!path)
 543                 return -ENOMEM;
 544
 545         while (1) {
 546                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 547                 key.offset = end_byte - 1;
 548                 key.type = BTRFS_EXTENT_CSUM_KEY;
 549
 550                 path->leave_spinning = 1;
 551                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 552                 if (ret > 0) {
 553                         if (path->slots[0] == 0)
 554                                 goto out;
 555                         path->slots[0]--;
 556                 } else if (ret < 0) {
 557                         goto out;
 558                 }
 559
 560                 leaf = path->nodes[0];
 561                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 562
 563                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 564                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 565                         break;
 566                 }
 567
 568                 if (key.offset >= end_byte)
 569                         break;
 570
 571                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 572                 csum_end <<= blocksize_bits;
 573                 csum_end += key.offset;
 574
 575                 /* this csum ends before we start, we're done */
 576                 if (csum_end <= bytenr)
 577                         break;
 578
 579                 /* delete the entire item, it is inside our range */
 580                 if (key.offset >= bytenr && csum_end <= end_byte) {
 581                         ret = btrfs_del_item(trans, root, path);
 582                         BUG_ON(ret);
 583                         if (key.offset == bytenr)
 584                                 break;
 585                 } else if (key.offset < bytenr && csum_end > end_byte) {
 586                         unsigned long offset;
 587                         unsigned long shift_len;
 588                         unsigned long item_offset;
 589                         /*
 590                          *        [ bytenr - len ]
 591                          *     [csum                ]
 592                          *
 593                          * Our bytes are in the middle of the csum,
 594                          * we need to split this item and insert a new one.
 595                          *
 596                          * But we can't drop the path because the
 597                          * csum could change, get removed, extended etc.
 598                          *
 599                          * The trick here is the max size of a csum item leaves
 600                          * enough room in the tree block for a single
 601                          * item header.  So, we split the item in place,
 602                          * adding a new header pointing to the existing
 603                          * bytes.  Then we loop around again and we have
 604                          * a nicely formed csum item that we can neatly
 605                          * truncate.
 606                          */
 607                         offset = (bytenr - key.offset) >> blocksize_bits;
 608                         offset *= csum_size;
 609
 610                         shift_len = (len >> blocksize_bits) * csum_size;
 611
 612                         item_offset = btrfs_item_ptr_offset(leaf,
 613                                                             path->slots[0]);
 614
 615                         memset_extent_buffer(leaf, 0, item_offset + offset,
 616                                              shift_len);
 617                         key.offset = bytenr;
 618
 619                         /*
 620                          * btrfs_split_item returns -EAGAIN when the
 621                          * item changed size or key
 622                          */
 623                         ret = btrfs_split_item(trans, root, path, &key, offset);
 624                         BUG_ON(ret && ret != -EAGAIN);
 625
 626                         key.offset = end_byte - 1;
 627                 } else {
 628                         ret = truncate_one_csum(trans, root, path,
 629                                                 &key, bytenr, len);
 630                         BUG_ON(ret);
 631                         if (key.offset < bytenr)
 632                                 break;
 633                 }
 634                 btrfs_release_path(path);
 635         }
 636 out:
 637         btrfs_free_path(path);
 638         return 0;
 639 }
 640
 641 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 642                            struct btrfs_root *root,
 643                            struct btrfs_ordered_sum *sums)
 644 {
 645         u64 bytenr;
 646         int ret;
 647         struct btrfs_key file_key;
 648         struct btrfs_key found_key;
 649         u64 next_offset;
 650         u64 total_bytes = 0;
 651         int found_next;
 652         struct btrfs_path *path;
 653         struct btrfs_csum_item *item;
 654         struct btrfs_csum_item *item_end;
 655         struct extent_buffer *leaf = NULL;
 656         u64 csum_offset;
 657         struct btrfs_sector_sum *sector_sum;
 658         u32 nritems;
 659         u32 ins_size;
 660         char *eb_map;
 661         char *eb_token;
 662         unsigned long map_len;
 663         unsigned long map_start;
 664         u16 csum_size =
 665                 btrfs_super_csum_size(&root->fs_info->super_copy);
 666
 667         path = btrfs_alloc_path();
 668         BUG_ON(!path);
 669         sector_sum = sums->sums;
 670 again:
 671         next_offset = (u64)-1;
 672         found_next = 0;
 673         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 674         file_key.offset = sector_sum->bytenr;
 675         bytenr = sector_sum->bytenr;
 676         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 677
 678         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 679         if (!IS_ERR(item)) {
 680                 leaf = path->nodes[0];
 681                 ret = 0;
 682                 goto found;
 683         }
 684         ret = PTR_ERR(item);
 685         if (ret != -EFBIG && ret != -ENOENT)
 686                 goto fail_unlock;
 687
 688         if (ret == -EFBIG) {
 689                 u32 item_size;
 690                 /* we found one, but it isn't big enough yet */
 691                 leaf = path->nodes[0];
 692                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 693                 if ((item_size / csum_size) >=
 694                     MAX_CSUM_ITEMS(root, csum_size)) {
 695                         /* already at max size, make a new one */
 696                         goto insert;
 697                 }
 698         } else {
 699                 int slot = path->slots[0] + 1;
 700                 /* we didn't find a csum item, insert one */
 701                 nritems = btrfs_header_nritems(path->nodes[0]);
 702                 if (path->slots[0] >= nritems - 1) {
 703                         ret = btrfs_next_leaf(root, path);
 704                         if (ret == 1)
 705                                 found_next = 1;
 706                         if (ret != 0)
 707                                 goto insert;
 708                         slot = 0;
 709                 }
 710                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 711                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 712                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 713                         found_next = 1;
 714                         goto insert;
 715                 }
 716                 next_offset = found_key.offset;
 717                 found_next = 1;
 718                 goto insert;
 719         }
 720
 721         /*
 722          * at this point, we know the tree has an item, but it isn't big
 723          * enough yet to put our csum in.  Grow it
 724          */
 725         btrfs_release_path(path);
 726         ret = btrfs_search_slot(trans, root, &file_key, path,
 727                                 csum_size, 1);
 728         if (ret < 0)
 729                 goto fail_unlock;
 730
 731         if (ret > 0) {
 732                 if (path->slots[0] == 0)
 733                         goto insert;
 734                 path->slots[0]--;
 735         }
 736
 737         leaf = path->nodes[0];
 738         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 739         csum_offset = (bytenr - found_key.offset) >>
 740                         root->fs_info->sb->s_blocksize_bits;
 741
 742         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 743             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 744             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 745                 goto insert;
 746         }
 747
 748         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
 749             csum_size) {
 750                 u32 diff = (csum_offset + 1) * csum_size;
 751
 752                 /*
 753                  * is the item big enough already?  we dropped our lock
 754                  * before and need to recheck
 755                  */
 756                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
 757                         goto csum;
 758
 759                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 760                 if (diff != csum_size)
 761                         goto insert;
 762
 763                 ret = btrfs_extend_item(trans, root, path, diff);
 764                 BUG_ON(ret);
 765                 goto csum;
 766         }
 767
 768 insert:
 769         btrfs_release_path(path);
 770         csum_offset = 0;
 771         if (found_next) {
 772                 u64 tmp = total_bytes + root->sectorsize;
 773                 u64 next_sector = sector_sum->bytenr;
 774                 struct btrfs_sector_sum *next = sector_sum + 1;
 775
 776                 while (tmp < sums->len) {
 777                         if (next_sector + root->sectorsize != next->bytenr)
 778                                 break;
 779                         tmp += root->sectorsize;
 780                         next_sector = next->bytenr;
 781                         next++;
 782                 }
 783                 tmp = min(tmp, next_offset - file_key.offset);
 784                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 785                 tmp = max((u64)1, tmp);
 786                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 787                 ins_size = csum_size * tmp;
 788         } else {
 789                 ins_size = csum_size;
 790         }
 791         path->leave_spinning = 1;
 792         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 793                                       ins_size);
 794         path->leave_spinning = 0;
 795         if (ret < 0)
 796                 goto fail_unlock;
 797         if (ret != 0) {
 798                 WARN_ON(1);
 799                 goto fail_unlock;
 800         }
 801 csum:
 802         leaf = path->nodes[0];
 803         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 804         ret = 0;
 805         item = (struct btrfs_csum_item *)((unsigned char *)item +
 806                                           csum_offset * csum_size);
 807 found:
 808         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 809         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 810                                       btrfs_item_size_nr(leaf, path->slots[0]));
 811         eb_token = NULL;
 812 next_sector:
 813
 814         if (!eb_token ||
 815            (unsigned long)item + csum_size >= map_start + map_len) {
 816                 int err;
 817
 818                 if (eb_token)
 819                         unmap_extent_buffer(leaf, eb_token, KM_USER1);
 820                 eb_token = NULL;
 821                 err = map_private_extent_buffer(leaf, (unsigned long)item,
 822                                                 csum_size,
 823                                                 &eb_token, &eb_map,
 824                                                 &map_start, &map_len, KM_USER1);
 825                 if (err)
 826                         eb_token = NULL;
 827         }
 828         if (eb_token) {
 829                 memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
 830                        &sector_sum->sum, csum_size);
 831         } else {
 832                 write_extent_buffer(leaf, &sector_sum->sum,
 833                                     (unsigned long)item, csum_size);
 834         }
 835
 836         total_bytes += root->sectorsize;
 837         sector_sum++;
 838         if (total_bytes < sums->len) {
 839                 item = (struct btrfs_csum_item *)((char *)item +
 840                                                   csum_size);
 841                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 842                     sector_sum->bytenr) {
 843                         bytenr = sector_sum->bytenr;
 844                         goto next_sector;
 845                 }
 846         }
 847         if (eb_token) {
 848                 unmap_extent_buffer(leaf, eb_token, KM_USER1);
 849                 eb_token = NULL;
 850         }
 851         btrfs_mark_buffer_dirty(path->nodes[0]);
 852         if (total_bytes < sums->len) {
 853                 btrfs_release_path(path);
 854                 cond_resched();
 855                 goto again;
 856         }
 857 out:
 858         btrfs_free_path(path);
 859         return ret;
 860
 861 fail_unlock:
 862         goto out;
 863 }