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[16];
 181         int len;
 182         struct bio_vec *bvec = bio->bi_io_vec;
 183         int bio_index = 0;
 184         u64 offset = 0;
 185         u64 item_start_offset = 0;
 186         u64 item_last_offset = 0;
 187         u64 disk_bytenr;
 188         u32 diff;
 189         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 190         int count;
 191         struct btrfs_path *path;
 192         struct btrfs_csum_item *item = NULL;
 193         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 194
 195         path = btrfs_alloc_path();
 196         if (!path)
 197                 return -ENOMEM;
 198         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 199                 path->reada = 2;
 200
 201         WARN_ON(bio->bi_vcnt <= 0);
 202
 203         /*
 204          * the free space stuff is only read when it hasn't been
 205          * updated in the current transaction.  So, we can safely
 206          * read from the commit root and sidestep a nasty deadlock
 207          * between reading the free space cache and updating the csum tree.
 208          */
 209         if (btrfs_is_free_space_inode(inode)) {
 210                 path->search_commit_root = 1;
 211                 path->skip_locking = 1;
 212         }
 213
 214         disk_bytenr = (u64)bio->bi_sector << 9;
 215         if (dio)
 216                 offset = logical_offset;
 217         while (bio_index < bio->bi_vcnt) {
 218                 len = min_t(int, ARRAY_SIZE(sum), bio->bi_vcnt - bio_index);
 219                 if (!dio)
 220                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 221                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr, sum,
 222                                                len);
 223                 if (count)
 224                         goto found;
 225
 226                 if (!item || disk_bytenr < item_start_offset ||
 227                     disk_bytenr >= item_last_offset) {
 228                         struct btrfs_key found_key;
 229                         u32 item_size;
 230
 231                         if (item)
 232                                 btrfs_release_path(path);
 233                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 234                                                  path, disk_bytenr, 0);
 235                         if (IS_ERR(item)) {
 236                                 count = 1;
 237                                 sum[0] = 0;
 238                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 239                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 240                                         set_extent_bits(io_tree, offset,
 241                                                 offset + bvec->bv_len - 1,
 242                                                 EXTENT_NODATASUM, GFP_NOFS);
 243                                 } else {
 244                                         printk(KERN_INFO "btrfs no csum found "
 245                                                "for inode %llu start %llu\n",
 246                                                (unsigned long long)
 247                                                btrfs_ino(inode),
 248                                                (unsigned long long)offset);
 249                                 }
 250                                 item = NULL;
 251                                 btrfs_release_path(path);
 252                                 goto found;
 253                         }
 254                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 255                                               path->slots[0]);
 256
 257                         item_start_offset = found_key.offset;
 258                         item_size = btrfs_item_size_nr(path->nodes[0],
 259                                                        path->slots[0]);
 260                         item_last_offset = item_start_offset +
 261                                 (item_size / csum_size) *
 262                                 root->sectorsize;
 263                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 264                                               struct btrfs_csum_item);
 265                 }
 266                 /*
 267                  * this byte range must be able to fit inside
 268                  * a single leaf so it will also fit inside a u32
 269                  */
 270                 diff = disk_bytenr - item_start_offset;
 271                 diff = diff / root->sectorsize;
 272                 diff = diff * csum_size;
 273                 count = min_t(int, len, (item_last_offset - disk_bytenr) >>
 274                                         inode->i_sb->s_blocksize_bits);
 275                 read_extent_buffer(path->nodes[0], sum,
 276                                    ((unsigned long)item) + diff,
 277                                    csum_size * count);
 278 found:
 279                 if (dst) {
 280                         memcpy(dst, sum, count * csum_size);
 281                         dst += count;
 282                 } else {
 283                         if (dio)
 284                                 extent_cache_csums_dio(io_tree, offset, sum,
 285                                                        count);
 286                         else
 287                                 extent_cache_csums(io_tree, bio, bio_index, sum,
 288                                             count);
 289                 }
 290                 while (count--) {
 291                         disk_bytenr += bvec->bv_len;
 292                         offset += bvec->bv_len;
 293                         bio_index++;
 294                         bvec++;
 295                 }
 296         }
 297         btrfs_free_path(path);
 298         return 0;
 299 }
 300
 301 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 302                           struct bio *bio, u32 *dst)
 303 {
 304         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 305 }
 306
 307 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 308                               struct bio *bio, u64 offset)
 309 {
 310         return __btrfs_lookup_bio_sums(root, inode, bio, offset, NULL, 1);
 311 }
 312
 313 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 314                              struct list_head *list, int search_commit)
 315 {
 316         struct btrfs_key key;
 317         struct btrfs_path *path;
 318         struct extent_buffer *leaf;
 319         struct btrfs_ordered_sum *sums;
 320         struct btrfs_sector_sum *sector_sum;
 321         struct btrfs_csum_item *item;
 322         LIST_HEAD(tmplist);
 323         unsigned long offset;
 324         int ret;
 325         size_t size;
 326         u64 csum_end;
 327         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 328
 329         path = btrfs_alloc_path();
 330         if (!path)
 331                 return -ENOMEM;
 332
 333         if (search_commit) {
 334                 path->skip_locking = 1;
 335                 path->reada = 2;
 336                 path->search_commit_root = 1;
 337         }
 338
 339         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 340         key.offset = start;
 341         key.type = BTRFS_EXTENT_CSUM_KEY;
 342
 343         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 344         if (ret < 0)
 345                 goto fail;
 346         if (ret > 0 && path->slots[0] > 0) {
 347                 leaf = path->nodes[0];
 348                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 349                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 350                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 351                         offset = (start - key.offset) >>
 352                                  root->fs_info->sb->s_blocksize_bits;
 353                         if (offset * csum_size <
 354                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 355                                 path->slots[0]--;
 356                 }
 357         }
 358
 359         while (start <= end) {
 360                 leaf = path->nodes[0];
 361                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 362                         ret = btrfs_next_leaf(root, path);
 363                         if (ret < 0)
 364                                 goto fail;
 365                         if (ret > 0)
 366                                 break;
 367                         leaf = path->nodes[0];
 368                 }
 369
 370                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 371                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 372                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 373                     key.offset > end)
 374                         break;
 375
 376                 if (key.offset > start)
 377                         start = key.offset;
 378
 379                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 380                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 381                 if (csum_end <= start) {
 382                         path->slots[0]++;
 383                         continue;
 384                 }
 385
 386                 csum_end = min(csum_end, end + 1);
 387                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 388                                       struct btrfs_csum_item);
 389                 while (start < csum_end) {
 390                         size = min_t(size_t, csum_end - start,
 391                                         MAX_ORDERED_SUM_BYTES(root));
 392                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 393                                         GFP_NOFS);
 394                         if (!sums) {
 395                                 ret = -ENOMEM;
 396                                 goto fail;
 397                         }
 398
 399                         sector_sum = sums->sums;
 400                         sums->bytenr = start;
 401                         sums->len = size;
 402
 403                         offset = (start - key.offset) >>
 404                                 root->fs_info->sb->s_blocksize_bits;
 405                         offset *= csum_size;
 406
 407                         while (size > 0) {
 408                                 read_extent_buffer(path->nodes[0],
 409                                                 &sector_sum->sum,
 410                                                 ((unsigned long)item) +
 411                                                 offset, csum_size);
 412                                 sector_sum->bytenr = start;
 413
 414                                 size -= root->sectorsize;
 415                                 start += root->sectorsize;
 416                                 offset += csum_size;
 417                                 sector_sum++;
 418                         }
 419                         list_add_tail(&sums->list, &tmplist);
 420                 }
 421                 path->slots[0]++;
 422         }
 423         ret = 0;
 424 fail:
 425         while (ret < 0 && !list_empty(&tmplist)) {
 426                 sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
 427                 list_del(&sums->list);
 428                 kfree(sums);
 429         }
 430         list_splice_tail(&tmplist, list);
 431
 432         btrfs_free_path(path);
 433         return ret;
 434 }
 435
 436 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 437                        struct bio *bio, u64 file_start, int contig)
 438 {
 439         struct btrfs_ordered_sum *sums;
 440         struct btrfs_sector_sum *sector_sum;
 441         struct btrfs_ordered_extent *ordered;
 442         char *data;
 443         struct bio_vec *bvec = bio->bi_io_vec;
 444         int bio_index = 0;
 445         unsigned long total_bytes = 0;
 446         unsigned long this_sum_bytes = 0;
 447         u64 offset;
 448         u64 disk_bytenr;
 449
 450         WARN_ON(bio->bi_vcnt <= 0);
 451         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 452         if (!sums)
 453                 return -ENOMEM;
 454
 455         sector_sum = sums->sums;
 456         disk_bytenr = (u64)bio->bi_sector << 9;
 457         sums->len = bio->bi_size;
 458         INIT_LIST_HEAD(&sums->list);
 459
 460         if (contig)
 461                 offset = file_start;
 462         else
 463                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 464
 465         ordered = btrfs_lookup_ordered_extent(inode, offset);
 466         BUG_ON(!ordered); /* Logic error */
 467         sums->bytenr = ordered->start;
 468
 469         while (bio_index < bio->bi_vcnt) {
 470                 if (!contig)
 471                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 472
 473                 if (offset >= ordered->file_offset + ordered->len ||
 474                     offset < ordered->file_offset) {
 475                         unsigned long bytes_left;
 476                         sums->len = this_sum_bytes;
 477                         this_sum_bytes = 0;
 478                         btrfs_add_ordered_sum(inode, ordered, sums);
 479                         btrfs_put_ordered_extent(ordered);
 480
 481                         bytes_left = bio->bi_size - total_bytes;
 482
 483                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 484                                        GFP_NOFS);
 485                         BUG_ON(!sums); /* -ENOMEM */
 486                         sector_sum = sums->sums;
 487                         sums->len = bytes_left;
 488                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 489                         BUG_ON(!ordered); /* Logic error */
 490                         sums->bytenr = ordered->start;
 491                 }
 492
 493                 data = kmap_atomic(bvec->bv_page);
 494                 sector_sum->sum = ~(u32)0;
 495                 sector_sum->sum = btrfs_csum_data(data + bvec->bv_offset,
 496                                                   sector_sum->sum,
 497                                                   bvec->bv_len);
 498                 kunmap_atomic(data);
 499                 btrfs_csum_final(sector_sum->sum,
 500                                  (char *)&sector_sum->sum);
 501                 sector_sum->bytenr = disk_bytenr;
 502
 503                 sector_sum++;
 504                 bio_index++;
 505                 total_bytes += bvec->bv_len;
 506                 this_sum_bytes += bvec->bv_len;
 507                 disk_bytenr += bvec->bv_len;
 508                 offset += bvec->bv_len;
 509                 bvec++;
 510         }
 511         this_sum_bytes = 0;
 512         btrfs_add_ordered_sum(inode, ordered, sums);
 513         btrfs_put_ordered_extent(ordered);
 514         return 0;
 515 }
 516
 517 /*
 518  * helper function for csum removal, this expects the
 519  * key to describe the csum pointed to by the path, and it expects
 520  * the csum to overlap the range [bytenr, len]
 521  *
 522  * The csum should not be entirely contained in the range and the
 523  * range should not be entirely contained in the csum.
 524  *
 525  * This calls btrfs_truncate_item with the correct args based on the
 526  * overlap, and fixes up the key as required.
 527  */
 528 static noinline void truncate_one_csum(struct btrfs_root *root,
 529                                        struct btrfs_path *path,
 530                                        struct btrfs_key *key,
 531                                        u64 bytenr, u64 len)
 532 {
 533         struct extent_buffer *leaf;
 534         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 535         u64 csum_end;
 536         u64 end_byte = bytenr + len;
 537         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 538
 539         leaf = path->nodes[0];
 540         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 541         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 542         csum_end += key->offset;
 543
 544         if (key->offset < bytenr && csum_end <= end_byte) {
 545                 /*
 546                  *         [ bytenr - len ]
 547                  *         [   ]
 548                  *   [csum     ]
 549                  *   A simple truncate off the end of the item
 550                  */
 551                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 552                 new_size *= csum_size;
 553                 btrfs_truncate_item(root, path, new_size, 1);
 554         } else if (key->offset >= bytenr && csum_end > end_byte &&
 555                    end_byte > key->offset) {
 556                 /*
 557                  *         [ bytenr - len ]
 558                  *                 [ ]
 559                  *                 [csum     ]
 560                  * we need to truncate from the beginning of the csum
 561                  */
 562                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 563                 new_size *= csum_size;
 564
 565                 btrfs_truncate_item(root, path, new_size, 0);
 566
 567                 key->offset = end_byte;
 568                 btrfs_set_item_key_safe(root, path, key);
 569         } else {
 570                 BUG();
 571         }
 572 }
 573
 574 /*
 575  * deletes the csum items from the csum tree for a given
 576  * range of bytes.
 577  */
 578 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 579                     struct btrfs_root *root, u64 bytenr, u64 len)
 580 {
 581         struct btrfs_path *path;
 582         struct btrfs_key key;
 583         u64 end_byte = bytenr + len;
 584         u64 csum_end;
 585         struct extent_buffer *leaf;
 586         int ret;
 587         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 588         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 589
 590         root = root->fs_info->csum_root;
 591
 592         path = btrfs_alloc_path();
 593         if (!path)
 594                 return -ENOMEM;
 595
 596         while (1) {
 597                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 598                 key.offset = end_byte - 1;
 599                 key.type = BTRFS_EXTENT_CSUM_KEY;
 600
 601                 path->leave_spinning = 1;
 602                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 603                 if (ret > 0) {
 604                         if (path->slots[0] == 0)
 605                                 break;
 606                         path->slots[0]--;
 607                 } else if (ret < 0) {
 608                         break;
 609                 }
 610
 611                 leaf = path->nodes[0];
 612                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 613
 614                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 615                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 616                         break;
 617                 }
 618
 619                 if (key.offset >= end_byte)
 620                         break;
 621
 622                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 623                 csum_end <<= blocksize_bits;
 624                 csum_end += key.offset;
 625
 626                 /* this csum ends before we start, we're done */
 627                 if (csum_end <= bytenr)
 628                         break;
 629
 630                 /* delete the entire item, it is inside our range */
 631                 if (key.offset >= bytenr && csum_end <= end_byte) {
 632                         ret = btrfs_del_item(trans, root, path);
 633                         if (ret)
 634                                 goto out;
 635                         if (key.offset == bytenr)
 636                                 break;
 637                 } else if (key.offset < bytenr && csum_end > end_byte) {
 638                         unsigned long offset;
 639                         unsigned long shift_len;
 640                         unsigned long item_offset;
 641                         /*
 642                          *        [ bytenr - len ]
 643                          *     [csum                ]
 644                          *
 645                          * Our bytes are in the middle of the csum,
 646                          * we need to split this item and insert a new one.
 647                          *
 648                          * But we can't drop the path because the
 649                          * csum could change, get removed, extended etc.
 650                          *
 651                          * The trick here is the max size of a csum item leaves
 652                          * enough room in the tree block for a single
 653                          * item header.  So, we split the item in place,
 654                          * adding a new header pointing to the existing
 655                          * bytes.  Then we loop around again and we have
 656                          * a nicely formed csum item that we can neatly
 657                          * truncate.
 658                          */
 659                         offset = (bytenr - key.offset) >> blocksize_bits;
 660                         offset *= csum_size;
 661
 662                         shift_len = (len >> blocksize_bits) * csum_size;
 663
 664                         item_offset = btrfs_item_ptr_offset(leaf,
 665                                                             path->slots[0]);
 666
 667                         memset_extent_buffer(leaf, 0, item_offset + offset,
 668                                              shift_len);
 669                         key.offset = bytenr;
 670
 671                         /*
 672                          * btrfs_split_item returns -EAGAIN when the
 673                          * item changed size or key
 674                          */
 675                         ret = btrfs_split_item(trans, root, path, &key, offset);
 676                         if (ret && ret != -EAGAIN) {
 677                                 btrfs_abort_transaction(trans, root, ret);
 678                                 goto out;
 679                         }
 680
 681                         key.offset = end_byte - 1;
 682                 } else {
 683                         truncate_one_csum(root, path, &key, bytenr, len);
 684                         if (key.offset < bytenr)
 685                                 break;
 686                 }
 687                 btrfs_release_path(path);
 688         }
 689         ret = 0;
 690 out:
 691         btrfs_free_path(path);
 692         return ret;
 693 }
 694
 695 static u64 btrfs_sector_sum_left(struct btrfs_ordered_sum *sums,
 696                                  struct btrfs_sector_sum *sector_sum,
 697                                  u64 total_bytes, u64 sectorsize)
 698 {
 699         u64 tmp = sectorsize;
 700         u64 next_sector = sector_sum->bytenr;
 701         struct btrfs_sector_sum *next = sector_sum + 1;
 702
 703         while ((tmp + total_bytes) < sums->len) {
 704                 if (next_sector + sectorsize != next->bytenr)
 705                         break;
 706                 tmp += sectorsize;
 707                 next_sector = next->bytenr;
 708                 next++;
 709         }
 710         return tmp;
 711 }
 712
 713 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 714                            struct btrfs_root *root,
 715                            struct btrfs_ordered_sum *sums)
 716 {
 717         u64 bytenr;
 718         int ret;
 719         struct btrfs_key file_key;
 720         struct btrfs_key found_key;
 721         u64 next_offset;
 722         u64 total_bytes = 0;
 723         int found_next;
 724         struct btrfs_path *path;
 725         struct btrfs_csum_item *item;
 726         struct btrfs_csum_item *item_end;
 727         struct extent_buffer *leaf = NULL;
 728         u64 csum_offset;
 729         struct btrfs_sector_sum *sector_sum;
 730         u32 nritems;
 731         u32 ins_size;
 732         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 733
 734         path = btrfs_alloc_path();
 735         if (!path)
 736                 return -ENOMEM;
 737
 738         sector_sum = sums->sums;
 739 again:
 740         next_offset = (u64)-1;
 741         found_next = 0;
 742         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 743         file_key.offset = sector_sum->bytenr;
 744         bytenr = sector_sum->bytenr;
 745         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 746
 747         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 748         if (!IS_ERR(item)) {
 749                 leaf = path->nodes[0];
 750                 ret = 0;
 751                 goto found;
 752         }
 753         ret = PTR_ERR(item);
 754         if (ret != -EFBIG && ret != -ENOENT)
 755                 goto fail_unlock;
 756
 757         if (ret == -EFBIG) {
 758                 u32 item_size;
 759                 /* we found one, but it isn't big enough yet */
 760                 leaf = path->nodes[0];
 761                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 762                 if ((item_size / csum_size) >=
 763                     MAX_CSUM_ITEMS(root, csum_size)) {
 764                         /* already at max size, make a new one */
 765                         goto insert;
 766                 }
 767         } else {
 768                 int slot = path->slots[0] + 1;
 769                 /* we didn't find a csum item, insert one */
 770                 nritems = btrfs_header_nritems(path->nodes[0]);
 771                 if (path->slots[0] >= nritems - 1) {
 772                         ret = btrfs_next_leaf(root, path);
 773                         if (ret == 1)
 774                                 found_next = 1;
 775                         if (ret != 0)
 776                                 goto insert;
 777                         slot = 0;
 778                 }
 779                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 780                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 781                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 782                         found_next = 1;
 783                         goto insert;
 784                 }
 785                 next_offset = found_key.offset;
 786                 found_next = 1;
 787                 goto insert;
 788         }
 789
 790         /*
 791          * at this point, we know the tree has an item, but it isn't big
 792          * enough yet to put our csum in.  Grow it
 793          */
 794         btrfs_release_path(path);
 795         ret = btrfs_search_slot(trans, root, &file_key, path,
 796                                 csum_size, 1);
 797         if (ret < 0)
 798                 goto fail_unlock;
 799
 800         if (ret > 0) {
 801                 if (path->slots[0] == 0)
 802                         goto insert;
 803                 path->slots[0]--;
 804         }
 805
 806         leaf = path->nodes[0];
 807         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 808         csum_offset = (bytenr - found_key.offset) >>
 809                         root->fs_info->sb->s_blocksize_bits;
 810
 811         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 812             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 813             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 814                 goto insert;
 815         }
 816
 817         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 818             csum_size) {
 819                 int extend_nr;
 820                 u64 tmp;
 821                 u32 diff;
 822                 u32 free_space;
 823
 824                 if (btrfs_leaf_free_space(root, leaf) <
 825                                  sizeof(struct btrfs_item) + csum_size * 2)
 826                         goto insert;
 827
 828                 free_space = btrfs_leaf_free_space(root, leaf) -
 829                                          sizeof(struct btrfs_item) - csum_size;
 830                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 831                                             root->sectorsize);
 832                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 833                 WARN_ON(tmp < 1);
 834
 835                 extend_nr = max_t(int, 1, (int)tmp);
 836                 diff = (csum_offset + extend_nr) * csum_size;
 837                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 838
 839                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 840                 diff = min(free_space, diff);
 841                 diff /= csum_size;
 842                 diff *= csum_size;
 843
 844                 btrfs_extend_item(root, path, diff);
 845                 goto csum;
 846         }
 847
 848 insert:
 849         btrfs_release_path(path);
 850         csum_offset = 0;
 851         if (found_next) {
 852                 u64 tmp;
 853
 854                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 855                                             root->sectorsize);
 856                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 857                 tmp = min(tmp, (next_offset - file_key.offset) >>
 858                                          root->fs_info->sb->s_blocksize_bits);
 859
 860                 tmp = max((u64)1, tmp);
 861                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 862                 ins_size = csum_size * tmp;
 863         } else {
 864                 ins_size = csum_size;
 865         }
 866         path->leave_spinning = 1;
 867         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 868                                       ins_size);
 869         path->leave_spinning = 0;
 870         if (ret < 0)
 871                 goto fail_unlock;
 872         if (ret != 0) {
 873                 WARN_ON(1);
 874                 goto fail_unlock;
 875         }
 876 csum:
 877         leaf = path->nodes[0];
 878         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 879         ret = 0;
 880         item = (struct btrfs_csum_item *)((unsigned char *)item +
 881                                           csum_offset * csum_size);
 882 found:
 883         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 884         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 885                                       btrfs_item_size_nr(leaf, path->slots[0]));
 886 next_sector:
 887
 888         write_extent_buffer(leaf, &sector_sum->sum, (unsigned long)item, csum_size);
 889
 890         total_bytes += root->sectorsize;
 891         sector_sum++;
 892         if (total_bytes < sums->len) {
 893                 item = (struct btrfs_csum_item *)((char *)item +
 894                                                   csum_size);
 895                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 896                     sector_sum->bytenr) {
 897                         bytenr = sector_sum->bytenr;
 898                         goto next_sector;
 899                 }
 900         }
 901
 902         btrfs_mark_buffer_dirty(path->nodes[0]);
 903         if (total_bytes < sums->len) {
 904                 btrfs_release_path(path);
 905                 cond_resched();
 906                 goto again;
 907         }
 908 out:
 909         btrfs_free_path(path);
 910         return ret;
 911
 912 fail_unlock:
 913         goto out;
 914 }