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                         break;
 363
 364                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 365                 if (key.offset > end)
 366                         break;
 367
 368                 if (key.offset > start)
 369                         start = key.offset;
 370
 371                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 372                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 373                 if (csum_end <= start) {
 374                         path->slots[0]++;
 375                         continue;
 376                 }
 377
 378                 csum_end = min(csum_end, end + 1);
 379                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 380                                       struct btrfs_csum_item);
 381                 while (start < csum_end) {
 382                         size = min_t(size_t, csum_end - start,
 383                                         MAX_ORDERED_SUM_BYTES(root));
 384                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 385                                         GFP_NOFS);
 386                         if (!sums) {
 387                                 ret = -ENOMEM;
 388                                 goto fail;
 389                         }
 390
 391                         sector_sum = sums->sums;
 392                         sums->bytenr = start;
 393                         sums->len = size;
 394
 395                         offset = (start - key.offset) >>
 396                                 root->fs_info->sb->s_blocksize_bits;
 397                         offset *= csum_size;
 398
 399                         while (size > 0) {
 400                                 read_extent_buffer(path->nodes[0],
 401                                                 &sector_sum->sum,
 402                                                 ((unsigned long)item) +
 403                                                 offset, csum_size);
 404                                 sector_sum->bytenr = start;
 405
 406                                 size -= root->sectorsize;
 407                                 start += root->sectorsize;
 408                                 offset += csum_size;
 409                                 sector_sum++;
 410                         }
 411                         list_add_tail(&sums->list, &tmplist);
 412                 }
 413                 path->slots[0]++;
 414         }
 415         ret = 0;
 416 fail:
 417         while (ret < 0 && !list_empty(&tmplist)) {
 418                 sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
 419                 list_del(&sums->list);
 420                 kfree(sums);
 421         }
 422         list_splice_tail(&tmplist, list);
 423
 424         btrfs_free_path(path);
 425         return ret;
 426 }
 427
 428 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 429                        struct bio *bio, u64 file_start, int contig)
 430 {
 431         struct btrfs_ordered_sum *sums;
 432         struct btrfs_sector_sum *sector_sum;
 433         struct btrfs_ordered_extent *ordered;
 434         char *data;
 435         struct bio_vec *bvec = bio->bi_io_vec;
 436         int bio_index = 0;
 437         unsigned long total_bytes = 0;
 438         unsigned long this_sum_bytes = 0;
 439         u64 offset;
 440         u64 disk_bytenr;
 441
 442         WARN_ON(bio->bi_vcnt <= 0);
 443         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 444         if (!sums)
 445                 return -ENOMEM;
 446
 447         sector_sum = sums->sums;
 448         disk_bytenr = (u64)bio->bi_sector << 9;
 449         sums->len = bio->bi_size;
 450         INIT_LIST_HEAD(&sums->list);
 451
 452         if (contig)
 453                 offset = file_start;
 454         else
 455                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 456
 457         ordered = btrfs_lookup_ordered_extent(inode, offset);
 458         BUG_ON(!ordered); /* Logic error */
 459         sums->bytenr = ordered->start;
 460
 461         while (bio_index < bio->bi_vcnt) {
 462                 if (!contig)
 463                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 464
 465                 if (offset >= ordered->file_offset + ordered->len ||
 466                     offset < ordered->file_offset) {
 467                         unsigned long bytes_left;
 468                         sums->len = this_sum_bytes;
 469                         this_sum_bytes = 0;
 470                         btrfs_add_ordered_sum(inode, ordered, sums);
 471                         btrfs_put_ordered_extent(ordered);
 472
 473                         bytes_left = bio->bi_size - total_bytes;
 474
 475                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 476                                        GFP_NOFS);
 477                         BUG_ON(!sums); /* -ENOMEM */
 478                         sector_sum = sums->sums;
 479                         sums->len = bytes_left;
 480                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 481                         BUG_ON(!ordered); /* Logic error */
 482                         sums->bytenr = ordered->start;
 483                 }
 484
 485                 data = kmap_atomic(bvec->bv_page);
 486                 sector_sum->sum = ~(u32)0;
 487                 sector_sum->sum = btrfs_csum_data(root,
 488                                                   data + bvec->bv_offset,
 489                                                   sector_sum->sum,
 490                                                   bvec->bv_len);
 491                 kunmap_atomic(data);
 492                 btrfs_csum_final(sector_sum->sum,
 493                                  (char *)&sector_sum->sum);
 494                 sector_sum->bytenr = disk_bytenr;
 495
 496                 sector_sum++;
 497                 bio_index++;
 498                 total_bytes += bvec->bv_len;
 499                 this_sum_bytes += bvec->bv_len;
 500                 disk_bytenr += bvec->bv_len;
 501                 offset += bvec->bv_len;
 502                 bvec++;
 503         }
 504         this_sum_bytes = 0;
 505         btrfs_add_ordered_sum(inode, ordered, sums);
 506         btrfs_put_ordered_extent(ordered);
 507         return 0;
 508 }
 509
 510 /*
 511  * helper function for csum removal, this expects the
 512  * key to describe the csum pointed to by the path, and it expects
 513  * the csum to overlap the range [bytenr, len]
 514  *
 515  * The csum should not be entirely contained in the range and the
 516  * range should not be entirely contained in the csum.
 517  *
 518  * This calls btrfs_truncate_item with the correct args based on the
 519  * overlap, and fixes up the key as required.
 520  */
 521 static noinline void truncate_one_csum(struct btrfs_trans_handle *trans,
 522                                        struct btrfs_root *root,
 523                                        struct btrfs_path *path,
 524                                        struct btrfs_key *key,
 525                                        u64 bytenr, u64 len)
 526 {
 527         struct extent_buffer *leaf;
 528         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 529         u64 csum_end;
 530         u64 end_byte = bytenr + len;
 531         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 532
 533         leaf = path->nodes[0];
 534         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 535         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 536         csum_end += key->offset;
 537
 538         if (key->offset < bytenr && csum_end <= end_byte) {
 539                 /*
 540                  *         [ bytenr - len ]
 541                  *         [   ]
 542                  *   [csum     ]
 543                  *   A simple truncate off the end of the item
 544                  */
 545                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 546                 new_size *= csum_size;
 547                 btrfs_truncate_item(trans, root, path, new_size, 1);
 548         } else if (key->offset >= bytenr && csum_end > end_byte &&
 549                    end_byte > key->offset) {
 550                 /*
 551                  *         [ bytenr - len ]
 552                  *                 [ ]
 553                  *                 [csum     ]
 554                  * we need to truncate from the beginning of the csum
 555                  */
 556                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 557                 new_size *= csum_size;
 558
 559                 btrfs_truncate_item(trans, root, path, new_size, 0);
 560
 561                 key->offset = end_byte;
 562                 btrfs_set_item_key_safe(trans, root, path, key);
 563         } else {
 564                 BUG();
 565         }
 566 }
 567
 568 /*
 569  * deletes the csum items from the csum tree for a given
 570  * range of bytes.
 571  */
 572 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 573                     struct btrfs_root *root, u64 bytenr, u64 len)
 574 {
 575         struct btrfs_path *path;
 576         struct btrfs_key key;
 577         u64 end_byte = bytenr + len;
 578         u64 csum_end;
 579         struct extent_buffer *leaf;
 580         int ret;
 581         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 582         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 583
 584         root = root->fs_info->csum_root;
 585
 586         path = btrfs_alloc_path();
 587         if (!path)
 588                 return -ENOMEM;
 589
 590         while (1) {
 591                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 592                 key.offset = end_byte - 1;
 593                 key.type = BTRFS_EXTENT_CSUM_KEY;
 594
 595                 path->leave_spinning = 1;
 596                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 597                 if (ret > 0) {
 598                         if (path->slots[0] == 0)
 599                                 break;
 600                         path->slots[0]--;
 601                 } else if (ret < 0) {
 602                         break;
 603                 }
 604
 605                 leaf = path->nodes[0];
 606                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 607
 608                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 609                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 610                         break;
 611                 }
 612
 613                 if (key.offset >= end_byte)
 614                         break;
 615
 616                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 617                 csum_end <<= blocksize_bits;
 618                 csum_end += key.offset;
 619
 620                 /* this csum ends before we start, we're done */
 621                 if (csum_end <= bytenr)
 622                         break;
 623
 624                 /* delete the entire item, it is inside our range */
 625                 if (key.offset >= bytenr && csum_end <= end_byte) {
 626                         ret = btrfs_del_item(trans, root, path);
 627                         if (ret)
 628                                 goto out;
 629                         if (key.offset == bytenr)
 630                                 break;
 631                 } else if (key.offset < bytenr && csum_end > end_byte) {
 632                         unsigned long offset;
 633                         unsigned long shift_len;
 634                         unsigned long item_offset;
 635                         /*
 636                          *        [ bytenr - len ]
 637                          *     [csum                ]
 638                          *
 639                          * Our bytes are in the middle of the csum,
 640                          * we need to split this item and insert a new one.
 641                          *
 642                          * But we can't drop the path because the
 643                          * csum could change, get removed, extended etc.
 644                          *
 645                          * The trick here is the max size of a csum item leaves
 646                          * enough room in the tree block for a single
 647                          * item header.  So, we split the item in place,
 648                          * adding a new header pointing to the existing
 649                          * bytes.  Then we loop around again and we have
 650                          * a nicely formed csum item that we can neatly
 651                          * truncate.
 652                          */
 653                         offset = (bytenr - key.offset) >> blocksize_bits;
 654                         offset *= csum_size;
 655
 656                         shift_len = (len >> blocksize_bits) * csum_size;
 657
 658                         item_offset = btrfs_item_ptr_offset(leaf,
 659                                                             path->slots[0]);
 660
 661                         memset_extent_buffer(leaf, 0, item_offset + offset,
 662                                              shift_len);
 663                         key.offset = bytenr;
 664
 665                         /*
 666                          * btrfs_split_item returns -EAGAIN when the
 667                          * item changed size or key
 668                          */
 669                         ret = btrfs_split_item(trans, root, path, &key, offset);
 670                         if (ret && ret != -EAGAIN) {
 671                                 btrfs_abort_transaction(trans, root, ret);
 672                                 goto out;
 673                         }
 674
 675                         key.offset = end_byte - 1;
 676                 } else {
 677                         truncate_one_csum(trans, root, path, &key, bytenr, len);
 678                         if (key.offset < bytenr)
 679                                 break;
 680                 }
 681                 btrfs_release_path(path);
 682         }
 683         ret = 0;
 684 out:
 685         btrfs_free_path(path);
 686         return ret;
 687 }
 688
 689 static u64 btrfs_sector_sum_left(struct btrfs_ordered_sum *sums,
 690                                  struct btrfs_sector_sum *sector_sum,
 691                                  u64 total_bytes, u64 sectorsize)
 692 {
 693         u64 tmp = sectorsize;
 694         u64 next_sector = sector_sum->bytenr;
 695         struct btrfs_sector_sum *next = sector_sum + 1;
 696
 697         while ((tmp + total_bytes) < sums->len) {
 698                 if (next_sector + sectorsize != next->bytenr)
 699                         break;
 700                 tmp += sectorsize;
 701                 next_sector = next->bytenr;
 702                 next++;
 703         }
 704         return tmp;
 705 }
 706
 707 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 708                            struct btrfs_root *root,
 709                            struct btrfs_ordered_sum *sums)
 710 {
 711         u64 bytenr;
 712         int ret;
 713         struct btrfs_key file_key;
 714         struct btrfs_key found_key;
 715         u64 next_offset;
 716         u64 total_bytes = 0;
 717         int found_next;
 718         struct btrfs_path *path;
 719         struct btrfs_csum_item *item;
 720         struct btrfs_csum_item *item_end;
 721         struct extent_buffer *leaf = NULL;
 722         u64 csum_offset;
 723         struct btrfs_sector_sum *sector_sum;
 724         u32 nritems;
 725         u32 ins_size;
 726         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 727
 728         path = btrfs_alloc_path();
 729         if (!path)
 730                 return -ENOMEM;
 731
 732         sector_sum = sums->sums;
 733 again:
 734         next_offset = (u64)-1;
 735         found_next = 0;
 736         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 737         file_key.offset = sector_sum->bytenr;
 738         bytenr = sector_sum->bytenr;
 739         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 740
 741         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 742         if (!IS_ERR(item)) {
 743                 leaf = path->nodes[0];
 744                 ret = 0;
 745                 goto found;
 746         }
 747         ret = PTR_ERR(item);
 748         if (ret != -EFBIG && ret != -ENOENT)
 749                 goto fail_unlock;
 750
 751         if (ret == -EFBIG) {
 752                 u32 item_size;
 753                 /* we found one, but it isn't big enough yet */
 754                 leaf = path->nodes[0];
 755                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 756                 if ((item_size / csum_size) >=
 757                     MAX_CSUM_ITEMS(root, csum_size)) {
 758                         /* already at max size, make a new one */
 759                         goto insert;
 760                 }
 761         } else {
 762                 int slot = path->slots[0] + 1;
 763                 /* we didn't find a csum item, insert one */
 764                 nritems = btrfs_header_nritems(path->nodes[0]);
 765                 if (path->slots[0] >= nritems - 1) {
 766                         ret = btrfs_next_leaf(root, path);
 767                         if (ret == 1)
 768                                 found_next = 1;
 769                         if (ret != 0)
 770                                 goto insert;
 771                         slot = 0;
 772                 }
 773                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 774                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 775                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 776                         found_next = 1;
 777                         goto insert;
 778                 }
 779                 next_offset = found_key.offset;
 780                 found_next = 1;
 781                 goto insert;
 782         }
 783
 784         /*
 785          * at this point, we know the tree has an item, but it isn't big
 786          * enough yet to put our csum in.  Grow it
 787          */
 788         btrfs_release_path(path);
 789         ret = btrfs_search_slot(trans, root, &file_key, path,
 790                                 csum_size, 1);
 791         if (ret < 0)
 792                 goto fail_unlock;
 793
 794         if (ret > 0) {
 795                 if (path->slots[0] == 0)
 796                         goto insert;
 797                 path->slots[0]--;
 798         }
 799
 800         leaf = path->nodes[0];
 801         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 802         csum_offset = (bytenr - found_key.offset) >>
 803                         root->fs_info->sb->s_blocksize_bits;
 804
 805         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 806             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 807             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 808                 goto insert;
 809         }
 810
 811         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 812             csum_size) {
 813                 int extend_nr;
 814                 u64 tmp;
 815                 u32 diff;
 816                 u32 free_space;
 817
 818                 if (btrfs_leaf_free_space(root, leaf) <
 819                                  sizeof(struct btrfs_item) + csum_size * 2)
 820                         goto insert;
 821
 822                 free_space = btrfs_leaf_free_space(root, leaf) -
 823                                          sizeof(struct btrfs_item) - csum_size;
 824                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 825                                             root->sectorsize);
 826                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 827                 WARN_ON(tmp < 1);
 828
 829                 extend_nr = max_t(int, 1, (int)tmp);
 830                 diff = (csum_offset + extend_nr) * csum_size;
 831                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 832
 833                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 834                 diff = min(free_space, diff);
 835                 diff /= csum_size;
 836                 diff *= csum_size;
 837
 838                 btrfs_extend_item(trans, root, path, diff);
 839                 goto csum;
 840         }
 841
 842 insert:
 843         btrfs_release_path(path);
 844         csum_offset = 0;
 845         if (found_next) {
 846                 u64 tmp;
 847
 848                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 849                                             root->sectorsize);
 850                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 851                 tmp = min(tmp, (next_offset - file_key.offset) >>
 852                                          root->fs_info->sb->s_blocksize_bits);
 853
 854                 tmp = max((u64)1, tmp);
 855                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 856                 ins_size = csum_size * tmp;
 857         } else {
 858                 ins_size = csum_size;
 859         }
 860         path->leave_spinning = 1;
 861         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 862                                       ins_size);
 863         path->leave_spinning = 0;
 864         if (ret < 0)
 865                 goto fail_unlock;
 866         if (ret != 0) {
 867                 WARN_ON(1);
 868                 goto fail_unlock;
 869         }
 870 csum:
 871         leaf = path->nodes[0];
 872         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 873         ret = 0;
 874         item = (struct btrfs_csum_item *)((unsigned char *)item +
 875                                           csum_offset * csum_size);
 876 found:
 877         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 878         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 879                                       btrfs_item_size_nr(leaf, path->slots[0]));
 880 next_sector:
 881
 882         write_extent_buffer(leaf, &sector_sum->sum, (unsigned long)item, csum_size);
 883
 884         total_bytes += root->sectorsize;
 885         sector_sum++;
 886         if (total_bytes < sums->len) {
 887                 item = (struct btrfs_csum_item *)((char *)item +
 888                                                   csum_size);
 889                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 890                     sector_sum->bytenr) {
 891                         bytenr = sector_sum->bytenr;
 892                         goto next_sector;
 893                 }
 894         }
 895
 896         btrfs_mark_buffer_dirty(path->nodes[0]);
 897         if (total_bytes < sums->len) {
 898                 btrfs_release_path(path);
 899                 cond_resched();
 900                 goto again;
 901         }
 902 out:
 903         btrfs_free_path(path);
 904         return ret;
 905
 906 fail_unlock:
 907         goto out;
 908 }