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