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) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  29                                    sizeof(struct btrfs_item) * 2) / \
  30                                   size) - 1))
  31
  32 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  33                                        PAGE_CACHE_SIZE))
  34
  35 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
  36                                    sizeof(struct btrfs_ordered_sum)) / \
  37                                    sizeof(struct btrfs_sector_sum) * \
  38                                    (r)->sectorsize - (r)->sectorsize)
  39
  40 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  41                              struct btrfs_root *root,
  42                              u64 objectid, u64 pos,
  43                              u64 disk_offset, u64 disk_num_bytes,
  44                              u64 num_bytes, u64 offset, u64 ram_bytes,
  45                              u8 compression, u8 encryption, u16 other_encoding)
  46 {
  47         int ret = 0;
  48         struct btrfs_file_extent_item *item;
  49         struct btrfs_key file_key;
  50         struct btrfs_path *path;
  51         struct extent_buffer *leaf;
  52
  53         path = btrfs_alloc_path();
  54         if (!path)
  55                 return -ENOMEM;
  56         file_key.objectid = objectid;
  57         file_key.offset = pos;
  58         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
  59
  60         path->leave_spinning = 1;
  61         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  62                                       sizeof(*item));
  63         if (ret < 0)
  64                 goto out;
  65         BUG_ON(ret); /* Can't happen */
  66         leaf = path->nodes[0];
  67         item = btrfs_item_ptr(leaf, path->slots[0],
  68                               struct btrfs_file_extent_item);
  69         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  70         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  71         btrfs_set_file_extent_offset(leaf, item, offset);
  72         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  73         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  74         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  75         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  76         btrfs_set_file_extent_compression(leaf, item, compression);
  77         btrfs_set_file_extent_encryption(leaf, item, encryption);
  78         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  79
  80         btrfs_mark_buffer_dirty(leaf);
  81 out:
  82         btrfs_free_path(path);
  83         return ret;
  84 }
  85
  86 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  87                                           struct btrfs_root *root,
  88                                           struct btrfs_path *path,
  89                                           u64 bytenr, int cow)
  90 {
  91         int ret;
  92         struct btrfs_key file_key;
  93         struct btrfs_key found_key;
  94         struct btrfs_csum_item *item;
  95         struct extent_buffer *leaf;
  96         u64 csum_offset = 0;
  97         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
  98         int csums_in_item;
  99
 100         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 101         file_key.offset = bytenr;
 102         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 103         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 104         if (ret < 0)
 105                 goto fail;
 106         leaf = path->nodes[0];
 107         if (ret > 0) {
 108                 ret = 1;
 109                 if (path->slots[0] == 0)
 110                         goto fail;
 111                 path->slots[0]--;
 112                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 113                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
 114                         goto fail;
 115
 116                 csum_offset = (bytenr - found_key.offset) >>
 117                                 root->fs_info->sb->s_blocksize_bits;
 118                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 119                 csums_in_item /= csum_size;
 120
 121                 if (csum_offset == csums_in_item) {
 122                         ret = -EFBIG;
 123                         goto fail;
 124                 } else if (csum_offset > csums_in_item) {
 125                         goto fail;
 126                 }
 127         }
 128         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 129         item = (struct btrfs_csum_item *)((unsigned char *)item +
 130                                           csum_offset * csum_size);
 131         return item;
 132 fail:
 133         if (ret > 0)
 134                 ret = -ENOENT;
 135         return ERR_PTR(ret);
 136 }
 137
 138 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 139                              struct btrfs_root *root,
 140                              struct btrfs_path *path, u64 objectid,
 141                              u64 offset, int mod)
 142 {
 143         int ret;
 144         struct btrfs_key file_key;
 145         int ins_len = mod < 0 ? -1 : 0;
 146         int cow = mod != 0;
 147
 148         file_key.objectid = objectid;
 149         file_key.offset = offset;
 150         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 151         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 152         return ret;
 153 }
 154
 155 u64 btrfs_file_extent_length(struct btrfs_path *path)
 156 {
 157         int extent_type;
 158         struct btrfs_file_extent_item *fi;
 159         u64 len;
 160
 161         fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
 162                             struct btrfs_file_extent_item);
 163         extent_type = btrfs_file_extent_type(path->nodes[0], fi);
 164
 165         if (extent_type == BTRFS_FILE_EXTENT_REG ||
 166             extent_type == BTRFS_FILE_EXTENT_PREALLOC)
 167                 len = btrfs_file_extent_num_bytes(path->nodes[0], fi);
 168         else if (extent_type == BTRFS_FILE_EXTENT_INLINE)
 169                 len = btrfs_file_extent_inline_len(path->nodes[0], fi);
 170         else
 171                 BUG();
 172
 173         return len;
 174 }
 175
 176 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 177                                    struct inode *inode, struct bio *bio,
 178                                    u64 logical_offset, u32 *dst, int dio)
 179 {
 180         u32 sum;
 181         struct bio_vec *bvec = bio->bi_io_vec;
 182         int bio_index = 0;
 183         u64 offset = 0;
 184         u64 item_start_offset = 0;
 185         u64 item_last_offset = 0;
 186         u64 disk_bytenr;
 187         u32 diff;
 188         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 189         int ret;
 190         struct btrfs_path *path;
 191         struct btrfs_csum_item *item = NULL;
 192         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 193
 194         path = btrfs_alloc_path();
 195         if (!path)
 196                 return -ENOMEM;
 197         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 198                 path->reada = 2;
 199
 200         WARN_ON(bio->bi_vcnt <= 0);
 201
 202         /*
 203          * the free space stuff is only read when it hasn't been
 204          * updated in the current transaction.  So, we can safely
 205          * read from the commit root and sidestep a nasty deadlock
 206          * between reading the free space cache and updating the csum tree.
 207          */
 208         if (btrfs_is_free_space_inode(inode)) {
 209                 path->search_commit_root = 1;
 210                 path->skip_locking = 1;
 211         }
 212
 213         disk_bytenr = (u64)bio->bi_sector << 9;
 214         if (dio)
 215                 offset = logical_offset;
 216         while (bio_index < bio->bi_vcnt) {
 217                 if (!dio)
 218                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 219                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
 220                 if (ret == 0)
 221                         goto found;
 222
 223                 if (!item || disk_bytenr < item_start_offset ||
 224                     disk_bytenr >= item_last_offset) {
 225                         struct btrfs_key found_key;
 226                         u32 item_size;
 227
 228                         if (item)
 229                                 btrfs_release_path(path);
 230                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 231                                                  path, disk_bytenr, 0);
 232                         if (IS_ERR(item)) {
 233                                 ret = PTR_ERR(item);
 234                                 if (ret == -ENOENT || ret == -EFBIG)
 235                                         ret = 0;
 236                                 sum = 0;
 237                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 238                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 239                                         set_extent_bits(io_tree, offset,
 240                                                 offset + bvec->bv_len - 1,
 241                                                 EXTENT_NODATASUM, GFP_NOFS);
 242                                 } else {
 243                                         printk(KERN_INFO "btrfs no csum found "
 244                                                "for inode %llu start %llu\n",
 245                                                (unsigned long long)
 246                                                btrfs_ino(inode),
 247                                                (unsigned long long)offset);
 248                                 }
 249                                 item = NULL;
 250                                 btrfs_release_path(path);
 251                                 goto found;
 252                         }
 253                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 254                                               path->slots[0]);
 255
 256                         item_start_offset = found_key.offset;
 257                         item_size = btrfs_item_size_nr(path->nodes[0],
 258                                                        path->slots[0]);
 259                         item_last_offset = item_start_offset +
 260                                 (item_size / csum_size) *
 261                                 root->sectorsize;
 262                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 263                                               struct btrfs_csum_item);
 264                 }
 265                 /*
 266                  * this byte range must be able to fit inside
 267                  * a single leaf so it will also fit inside a u32
 268                  */
 269                 diff = disk_bytenr - item_start_offset;
 270                 diff = diff / root->sectorsize;
 271                 diff = diff * csum_size;
 272
 273                 read_extent_buffer(path->nodes[0], &sum,
 274                                    ((unsigned long)item) + diff,
 275                                    csum_size);
 276 found:
 277                 if (dst)
 278                         *dst++ = sum;
 279                 else
 280                         set_state_private(io_tree, offset, sum);
 281                 disk_bytenr += bvec->bv_len;
 282                 offset += bvec->bv_len;
 283                 bio_index++;
 284                 bvec++;
 285         }
 286         btrfs_free_path(path);
 287         return 0;
 288 }
 289
 290 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 291                           struct bio *bio, u32 *dst)
 292 {
 293         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 294 }
 295
 296 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 297                               struct bio *bio, u64 offset)
 298 {
 299         return __btrfs_lookup_bio_sums(root, inode, bio, offset, NULL, 1);
 300 }
 301
 302 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 303                              struct list_head *list, int search_commit)
 304 {
 305         struct btrfs_key key;
 306         struct btrfs_path *path;
 307         struct extent_buffer *leaf;
 308         struct btrfs_ordered_sum *sums;
 309         struct btrfs_sector_sum *sector_sum;
 310         struct btrfs_csum_item *item;
 311         LIST_HEAD(tmplist);
 312         unsigned long offset;
 313         int ret;
 314         size_t size;
 315         u64 csum_end;
 316         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 317
 318         path = btrfs_alloc_path();
 319         if (!path)
 320                 return -ENOMEM;
 321
 322         if (search_commit) {
 323                 path->skip_locking = 1;
 324                 path->reada = 2;
 325                 path->search_commit_root = 1;
 326         }
 327
 328         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 329         key.offset = start;
 330         key.type = BTRFS_EXTENT_CSUM_KEY;
 331
 332         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 333         if (ret < 0)
 334                 goto fail;
 335         if (ret > 0 && path->slots[0] > 0) {
 336                 leaf = path->nodes[0];
 337                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 338                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 339                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 340                         offset = (start - key.offset) >>
 341                                  root->fs_info->sb->s_blocksize_bits;
 342                         if (offset * csum_size <
 343                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 344                                 path->slots[0]--;
 345                 }
 346         }
 347
 348         while (start <= end) {
 349                 leaf = path->nodes[0];
 350                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 351                         ret = btrfs_next_leaf(root, path);
 352                         if (ret < 0)
 353                                 goto fail;
 354                         if (ret > 0)
 355                                 break;
 356                         leaf = path->nodes[0];
 357                 }
 358
 359                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 360                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 361                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 362                     key.offset > end)
 363                         break;
 364
 365                 if (key.offset > start)
 366                         start = key.offset;
 367
 368                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 369                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 370                 if (csum_end <= start) {
 371                         path->slots[0]++;
 372                         continue;
 373                 }
 374
 375                 csum_end = min(csum_end, end + 1);
 376                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 377                                       struct btrfs_csum_item);
 378                 while (start < csum_end) {
 379                         size = min_t(size_t, csum_end - start,
 380                                         MAX_ORDERED_SUM_BYTES(root));
 381                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 382                                         GFP_NOFS);
 383                         if (!sums) {
 384                                 ret = -ENOMEM;
 385                                 goto fail;
 386                         }
 387
 388                         sector_sum = sums->sums;
 389                         sums->bytenr = start;
 390                         sums->len = size;
 391
 392                         offset = (start - key.offset) >>
 393                                 root->fs_info->sb->s_blocksize_bits;
 394                         offset *= csum_size;
 395
 396                         while (size > 0) {
 397                                 read_extent_buffer(path->nodes[0],
 398                                                 &sector_sum->sum,
 399                                                 ((unsigned long)item) +
 400                                                 offset, csum_size);
 401                                 sector_sum->bytenr = start;
 402
 403                                 size -= root->sectorsize;
 404                                 start += root->sectorsize;
 405                                 offset += csum_size;
 406                                 sector_sum++;
 407                         }
 408                         list_add_tail(&sums->list, &tmplist);
 409                 }
 410                 path->slots[0]++;
 411         }
 412         ret = 0;
 413 fail:
 414         while (ret < 0 && !list_empty(&tmplist)) {
 415                 sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
 416                 list_del(&sums->list);
 417                 kfree(sums);
 418         }
 419         list_splice_tail(&tmplist, list);
 420
 421         btrfs_free_path(path);
 422         return ret;
 423 }
 424
 425 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 426                        struct bio *bio, u64 file_start, int contig)
 427 {
 428         struct btrfs_ordered_sum *sums;
 429         struct btrfs_sector_sum *sector_sum;
 430         struct btrfs_ordered_extent *ordered;
 431         char *data;
 432         struct bio_vec *bvec = bio->bi_io_vec;
 433         int bio_index = 0;
 434         unsigned long total_bytes = 0;
 435         unsigned long this_sum_bytes = 0;
 436         u64 offset;
 437         u64 disk_bytenr;
 438
 439         WARN_ON(bio->bi_vcnt <= 0);
 440         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 441         if (!sums)
 442                 return -ENOMEM;
 443
 444         sector_sum = sums->sums;
 445         disk_bytenr = (u64)bio->bi_sector << 9;
 446         sums->len = bio->bi_size;
 447         INIT_LIST_HEAD(&sums->list);
 448
 449         if (contig)
 450                 offset = file_start;
 451         else
 452                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 453
 454         ordered = btrfs_lookup_ordered_extent(inode, offset);
 455         BUG_ON(!ordered); /* Logic error */
 456         sums->bytenr = ordered->start;
 457
 458         while (bio_index < bio->bi_vcnt) {
 459                 if (!contig)
 460                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 461
 462                 if (offset >= ordered->file_offset + ordered->len ||
 463                     offset < ordered->file_offset) {
 464                         unsigned long bytes_left;
 465                         sums->len = this_sum_bytes;
 466                         this_sum_bytes = 0;
 467                         btrfs_add_ordered_sum(inode, ordered, sums);
 468                         btrfs_put_ordered_extent(ordered);
 469
 470                         bytes_left = bio->bi_size - total_bytes;
 471
 472                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 473                                        GFP_NOFS);
 474                         BUG_ON(!sums); /* -ENOMEM */
 475                         sector_sum = sums->sums;
 476                         sums->len = bytes_left;
 477                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 478                         BUG_ON(!ordered); /* Logic error */
 479                         sums->bytenr = ordered->start;
 480                 }
 481
 482                 data = kmap_atomic(bvec->bv_page);
 483                 sector_sum->sum = ~(u32)0;
 484                 sector_sum->sum = btrfs_csum_data(data + bvec->bv_offset,
 485                                                   sector_sum->sum,
 486                                                   bvec->bv_len);
 487                 kunmap_atomic(data);
 488                 btrfs_csum_final(sector_sum->sum,
 489                                  (char *)&sector_sum->sum);
 490                 sector_sum->bytenr = disk_bytenr;
 491
 492                 sector_sum++;
 493                 bio_index++;
 494                 total_bytes += bvec->bv_len;
 495                 this_sum_bytes += bvec->bv_len;
 496                 disk_bytenr += bvec->bv_len;
 497                 offset += bvec->bv_len;
 498                 bvec++;
 499         }
 500         this_sum_bytes = 0;
 501         btrfs_add_ordered_sum(inode, ordered, sums);
 502         btrfs_put_ordered_extent(ordered);
 503         return 0;
 504 }
 505
 506 /*
 507  * helper function for csum removal, this expects the
 508  * key to describe the csum pointed to by the path, and it expects
 509  * the csum to overlap the range [bytenr, len]
 510  *
 511  * The csum should not be entirely contained in the range and the
 512  * range should not be entirely contained in the csum.
 513  *
 514  * This calls btrfs_truncate_item with the correct args based on the
 515  * overlap, and fixes up the key as required.
 516  */
 517 static noinline void truncate_one_csum(struct btrfs_trans_handle *trans,
 518                                        struct btrfs_root *root,
 519                                        struct btrfs_path *path,
 520                                        struct btrfs_key *key,
 521                                        u64 bytenr, u64 len)
 522 {
 523         struct extent_buffer *leaf;
 524         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 525         u64 csum_end;
 526         u64 end_byte = bytenr + len;
 527         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 528
 529         leaf = path->nodes[0];
 530         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 531         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 532         csum_end += key->offset;
 533
 534         if (key->offset < bytenr && csum_end <= end_byte) {
 535                 /*
 536                  *         [ bytenr - len ]
 537                  *         [   ]
 538                  *   [csum     ]
 539                  *   A simple truncate off the end of the item
 540                  */
 541                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 542                 new_size *= csum_size;
 543                 btrfs_truncate_item(trans, root, path, new_size, 1);
 544         } else if (key->offset >= bytenr && csum_end > end_byte &&
 545                    end_byte > key->offset) {
 546                 /*
 547                  *         [ bytenr - len ]
 548                  *                 [ ]
 549                  *                 [csum     ]
 550                  * we need to truncate from the beginning of the csum
 551                  */
 552                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 553                 new_size *= csum_size;
 554
 555                 btrfs_truncate_item(trans, root, path, new_size, 0);
 556
 557                 key->offset = end_byte;
 558                 btrfs_set_item_key_safe(trans, root, path, key);
 559         } else {
 560                 BUG();
 561         }
 562 }
 563
 564 /*
 565  * deletes the csum items from the csum tree for a given
 566  * range of bytes.
 567  */
 568 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 569                     struct btrfs_root *root, u64 bytenr, u64 len)
 570 {
 571         struct btrfs_path *path;
 572         struct btrfs_key key;
 573         u64 end_byte = bytenr + len;
 574         u64 csum_end;
 575         struct extent_buffer *leaf;
 576         int ret;
 577         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 578         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 579
 580         root = root->fs_info->csum_root;
 581
 582         path = btrfs_alloc_path();
 583         if (!path)
 584                 return -ENOMEM;
 585
 586         while (1) {
 587                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 588                 key.offset = end_byte - 1;
 589                 key.type = BTRFS_EXTENT_CSUM_KEY;
 590
 591                 path->leave_spinning = 1;
 592                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 593                 if (ret > 0) {
 594                         if (path->slots[0] == 0)
 595                                 break;
 596                         path->slots[0]--;
 597                 } else if (ret < 0) {
 598                         break;
 599                 }
 600
 601                 leaf = path->nodes[0];
 602                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 603
 604                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 605                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 606                         break;
 607                 }
 608
 609                 if (key.offset >= end_byte)
 610                         break;
 611
 612                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 613                 csum_end <<= blocksize_bits;
 614                 csum_end += key.offset;
 615
 616                 /* this csum ends before we start, we're done */
 617                 if (csum_end <= bytenr)
 618                         break;
 619
 620                 /* delete the entire item, it is inside our range */
 621                 if (key.offset >= bytenr && csum_end <= end_byte) {
 622                         ret = btrfs_del_item(trans, root, path);
 623                         if (ret)
 624                                 goto out;
 625                         if (key.offset == bytenr)
 626                                 break;
 627                 } else if (key.offset < bytenr && csum_end > end_byte) {
 628                         unsigned long offset;
 629                         unsigned long shift_len;
 630                         unsigned long item_offset;
 631                         /*
 632                          *        [ bytenr - len ]
 633                          *     [csum                ]
 634                          *
 635                          * Our bytes are in the middle of the csum,
 636                          * we need to split this item and insert a new one.
 637                          *
 638                          * But we can't drop the path because the
 639                          * csum could change, get removed, extended etc.
 640                          *
 641                          * The trick here is the max size of a csum item leaves
 642                          * enough room in the tree block for a single
 643                          * item header.  So, we split the item in place,
 644                          * adding a new header pointing to the existing
 645                          * bytes.  Then we loop around again and we have
 646                          * a nicely formed csum item that we can neatly
 647                          * truncate.
 648                          */
 649                         offset = (bytenr - key.offset) >> blocksize_bits;
 650                         offset *= csum_size;
 651
 652                         shift_len = (len >> blocksize_bits) * csum_size;
 653
 654                         item_offset = btrfs_item_ptr_offset(leaf,
 655                                                             path->slots[0]);
 656
 657                         memset_extent_buffer(leaf, 0, item_offset + offset,
 658                                              shift_len);
 659                         key.offset = bytenr;
 660
 661                         /*
 662                          * btrfs_split_item returns -EAGAIN when the
 663                          * item changed size or key
 664                          */
 665                         ret = btrfs_split_item(trans, root, path, &key, offset);
 666                         if (ret && ret != -EAGAIN) {
 667                                 btrfs_abort_transaction(trans, root, ret);
 668                                 goto out;
 669                         }
 670
 671                         key.offset = end_byte - 1;
 672                 } else {
 673                         truncate_one_csum(trans, root, path, &key, bytenr, len);
 674                         if (key.offset < bytenr)
 675                                 break;
 676                 }
 677                 btrfs_release_path(path);
 678         }
 679         ret = 0;
 680 out:
 681         btrfs_free_path(path);
 682         return ret;
 683 }
 684
 685 static u64 btrfs_sector_sum_left(struct btrfs_ordered_sum *sums,
 686                                  struct btrfs_sector_sum *sector_sum,
 687                                  u64 total_bytes, u64 sectorsize)
 688 {
 689         u64 tmp = sectorsize;
 690         u64 next_sector = sector_sum->bytenr;
 691         struct btrfs_sector_sum *next = sector_sum + 1;
 692
 693         while ((tmp + total_bytes) < sums->len) {
 694                 if (next_sector + sectorsize != next->bytenr)
 695                         break;
 696                 tmp += sectorsize;
 697                 next_sector = next->bytenr;
 698                 next++;
 699         }
 700         return tmp;
 701 }
 702
 703 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 704                            struct btrfs_root *root,
 705                            struct btrfs_ordered_sum *sums)
 706 {
 707         u64 bytenr;
 708         int ret;
 709         struct btrfs_key file_key;
 710         struct btrfs_key found_key;
 711         u64 next_offset;
 712         u64 total_bytes = 0;
 713         int found_next;
 714         struct btrfs_path *path;
 715         struct btrfs_csum_item *item;
 716         struct btrfs_csum_item *item_end;
 717         struct extent_buffer *leaf = NULL;
 718         u64 csum_offset;
 719         struct btrfs_sector_sum *sector_sum;
 720         u32 nritems;
 721         u32 ins_size;
 722         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 723
 724         path = btrfs_alloc_path();
 725         if (!path)
 726                 return -ENOMEM;
 727
 728         sector_sum = sums->sums;
 729 again:
 730         next_offset = (u64)-1;
 731         found_next = 0;
 732         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 733         file_key.offset = sector_sum->bytenr;
 734         bytenr = sector_sum->bytenr;
 735         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 736
 737         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 738         if (!IS_ERR(item)) {
 739                 leaf = path->nodes[0];
 740                 ret = 0;
 741                 goto found;
 742         }
 743         ret = PTR_ERR(item);
 744         if (ret != -EFBIG && ret != -ENOENT)
 745                 goto fail_unlock;
 746
 747         if (ret == -EFBIG) {
 748                 u32 item_size;
 749                 /* we found one, but it isn't big enough yet */
 750                 leaf = path->nodes[0];
 751                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 752                 if ((item_size / csum_size) >=
 753                     MAX_CSUM_ITEMS(root, csum_size)) {
 754                         /* already at max size, make a new one */
 755                         goto insert;
 756                 }
 757         } else {
 758                 int slot = path->slots[0] + 1;
 759                 /* we didn't find a csum item, insert one */
 760                 nritems = btrfs_header_nritems(path->nodes[0]);
 761                 if (path->slots[0] >= nritems - 1) {
 762                         ret = btrfs_next_leaf(root, path);
 763                         if (ret == 1)
 764                                 found_next = 1;
 765                         if (ret != 0)
 766                                 goto insert;
 767                         slot = 0;
 768                 }
 769                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 770                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 771                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 772                         found_next = 1;
 773                         goto insert;
 774                 }
 775                 next_offset = found_key.offset;
 776                 found_next = 1;
 777                 goto insert;
 778         }
 779
 780         /*
 781          * at this point, we know the tree has an item, but it isn't big
 782          * enough yet to put our csum in.  Grow it
 783          */
 784         btrfs_release_path(path);
 785         ret = btrfs_search_slot(trans, root, &file_key, path,
 786                                 csum_size, 1);
 787         if (ret < 0)
 788                 goto fail_unlock;
 789
 790         if (ret > 0) {
 791                 if (path->slots[0] == 0)
 792                         goto insert;
 793                 path->slots[0]--;
 794         }
 795
 796         leaf = path->nodes[0];
 797         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 798         csum_offset = (bytenr - found_key.offset) >>
 799                         root->fs_info->sb->s_blocksize_bits;
 800
 801         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 802             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 803             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 804                 goto insert;
 805         }
 806
 807         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 808             csum_size) {
 809                 int extend_nr;
 810                 u64 tmp;
 811                 u32 diff;
 812                 u32 free_space;
 813
 814                 if (btrfs_leaf_free_space(root, leaf) <
 815                                  sizeof(struct btrfs_item) + csum_size * 2)
 816                         goto insert;
 817
 818                 free_space = btrfs_leaf_free_space(root, leaf) -
 819                                          sizeof(struct btrfs_item) - csum_size;
 820                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 821                                             root->sectorsize);
 822                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 823                 WARN_ON(tmp < 1);
 824
 825                 extend_nr = max_t(int, 1, (int)tmp);
 826                 diff = (csum_offset + extend_nr) * csum_size;
 827                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 828
 829                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 830                 diff = min(free_space, diff);
 831                 diff /= csum_size;
 832                 diff *= csum_size;
 833
 834                 btrfs_extend_item(trans, root, path, diff);
 835                 goto csum;
 836         }
 837
 838 insert:
 839         btrfs_release_path(path);
 840         csum_offset = 0;
 841         if (found_next) {
 842                 u64 tmp;
 843
 844                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 845                                             root->sectorsize);
 846                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 847                 tmp = min(tmp, (next_offset - file_key.offset) >>
 848                                          root->fs_info->sb->s_blocksize_bits);
 849
 850                 tmp = max((u64)1, tmp);
 851                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 852                 ins_size = csum_size * tmp;
 853         } else {
 854                 ins_size = csum_size;
 855         }
 856         path->leave_spinning = 1;
 857         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 858                                       ins_size);
 859         path->leave_spinning = 0;
 860         if (ret < 0)
 861                 goto fail_unlock;
 862         if (ret != 0) {
 863                 WARN_ON(1);
 864                 goto fail_unlock;
 865         }
 866 csum:
 867         leaf = path->nodes[0];
 868         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 869         ret = 0;
 870         item = (struct btrfs_csum_item *)((unsigned char *)item +
 871                                           csum_offset * csum_size);
 872 found:
 873         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 874         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 875                                       btrfs_item_size_nr(leaf, path->slots[0]));
 876 next_sector:
 877
 878         write_extent_buffer(leaf, &sector_sum->sum, (unsigned long)item, csum_size);
 879
 880         total_bytes += root->sectorsize;
 881         sector_sum++;
 882         if (total_bytes < sums->len) {
 883                 item = (struct btrfs_csum_item *)((char *)item +
 884                                                   csum_size);
 885                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 886                     sector_sum->bytenr) {
 887                         bytenr = sector_sum->bytenr;
 888                         goto next_sector;
 889                 }
 890         }
 891
 892         btrfs_mark_buffer_dirty(path->nodes[0]);
 893         if (total_bytes < sums->len) {
 894                 btrfs_release_path(path);
 895                 cond_resched();
 896                 goto again;
 897         }
 898 out:
 899         btrfs_free_path(path);
 900         return ret;
 901
 902 fail_unlock:
 903         goto out;
 904 }