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 static struct btrfs_csum_item *
  87 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  88                   struct btrfs_root *root,
  89                   struct btrfs_path *path,
  90                   u64 bytenr, int cow)
  91 {
  92         int ret;
  93         struct btrfs_key file_key;
  94         struct btrfs_key found_key;
  95         struct btrfs_csum_item *item;
  96         struct extent_buffer *leaf;
  97         u64 csum_offset = 0;
  98         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
  99         int csums_in_item;
 100
 101         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 102         file_key.offset = bytenr;
 103         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 104         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 105         if (ret < 0)
 106                 goto fail;
 107         leaf = path->nodes[0];
 108         if (ret > 0) {
 109                 ret = 1;
 110                 if (path->slots[0] == 0)
 111                         goto fail;
 112                 path->slots[0]--;
 113                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 114                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
 115                         goto fail;
 116
 117                 csum_offset = (bytenr - found_key.offset) >>
 118                                 root->fs_info->sb->s_blocksize_bits;
 119                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 120                 csums_in_item /= csum_size;
 121
 122                 if (csum_offset == csums_in_item) {
 123                         ret = -EFBIG;
 124                         goto fail;
 125                 } else if (csum_offset > csums_in_item) {
 126                         goto fail;
 127                 }
 128         }
 129         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 130         item = (struct btrfs_csum_item *)((unsigned char *)item +
 131                                           csum_offset * csum_size);
 132         return item;
 133 fail:
 134         if (ret > 0)
 135                 ret = -ENOENT;
 136         return ERR_PTR(ret);
 137 }
 138
 139 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 140                              struct btrfs_root *root,
 141                              struct btrfs_path *path, u64 objectid,
 142                              u64 offset, int mod)
 143 {
 144         int ret;
 145         struct btrfs_key file_key;
 146         int ins_len = mod < 0 ? -1 : 0;
 147         int cow = mod != 0;
 148
 149         file_key.objectid = objectid;
 150         file_key.offset = offset;
 151         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 152         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 153         return ret;
 154 }
 155
 156 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 157                                    struct inode *inode, struct bio *bio,
 158                                    u64 logical_offset, u32 *dst, int dio)
 159 {
 160         u32 sum[16];
 161         int len;
 162         struct bio_vec *bvec = bio->bi_io_vec;
 163         int bio_index = 0;
 164         u64 offset = 0;
 165         u64 item_start_offset = 0;
 166         u64 item_last_offset = 0;
 167         u64 disk_bytenr;
 168         u32 diff;
 169         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 170         int count;
 171         struct btrfs_path *path;
 172         struct btrfs_csum_item *item = NULL;
 173         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 174
 175         path = btrfs_alloc_path();
 176         if (!path)
 177                 return -ENOMEM;
 178         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 179                 path->reada = 2;
 180
 181         WARN_ON(bio->bi_vcnt <= 0);
 182
 183         /*
 184          * the free space stuff is only read when it hasn't been
 185          * updated in the current transaction.  So, we can safely
 186          * read from the commit root and sidestep a nasty deadlock
 187          * between reading the free space cache and updating the csum tree.
 188          */
 189         if (btrfs_is_free_space_inode(inode)) {
 190                 path->search_commit_root = 1;
 191                 path->skip_locking = 1;
 192         }
 193
 194         disk_bytenr = (u64)bio->bi_sector << 9;
 195         if (dio)
 196                 offset = logical_offset;
 197         while (bio_index < bio->bi_vcnt) {
 198                 len = min_t(int, ARRAY_SIZE(sum), bio->bi_vcnt - bio_index);
 199                 if (!dio)
 200                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 201                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr, sum,
 202                                                len);
 203                 if (count)
 204                         goto found;
 205
 206                 if (!item || disk_bytenr < item_start_offset ||
 207                     disk_bytenr >= item_last_offset) {
 208                         struct btrfs_key found_key;
 209                         u32 item_size;
 210
 211                         if (item)
 212                                 btrfs_release_path(path);
 213                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 214                                                  path, disk_bytenr, 0);
 215                         if (IS_ERR(item)) {
 216                                 count = 1;
 217                                 sum[0] = 0;
 218                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 219                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 220                                         set_extent_bits(io_tree, offset,
 221                                                 offset + bvec->bv_len - 1,
 222                                                 EXTENT_NODATASUM, GFP_NOFS);
 223                                 } else {
 224                                         printk(KERN_INFO "btrfs no csum found "
 225                                                "for inode %llu start %llu\n",
 226                                                (unsigned long long)
 227                                                btrfs_ino(inode),
 228                                                (unsigned long long)offset);
 229                                 }
 230                                 item = NULL;
 231                                 btrfs_release_path(path);
 232                                 goto found;
 233                         }
 234                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 235                                               path->slots[0]);
 236
 237                         item_start_offset = found_key.offset;
 238                         item_size = btrfs_item_size_nr(path->nodes[0],
 239                                                        path->slots[0]);
 240                         item_last_offset = item_start_offset +
 241                                 (item_size / csum_size) *
 242                                 root->sectorsize;
 243                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 244                                               struct btrfs_csum_item);
 245                 }
 246                 /*
 247                  * this byte range must be able to fit inside
 248                  * a single leaf so it will also fit inside a u32
 249                  */
 250                 diff = disk_bytenr - item_start_offset;
 251                 diff = diff / root->sectorsize;
 252                 diff = diff * csum_size;
 253                 count = min_t(int, len, (item_last_offset - disk_bytenr) >>
 254                                         inode->i_sb->s_blocksize_bits);
 255                 read_extent_buffer(path->nodes[0], sum,
 256                                    ((unsigned long)item) + diff,
 257                                    csum_size * count);
 258 found:
 259                 if (dst) {
 260                         memcpy(dst, sum, count * csum_size);
 261                         dst += count;
 262                 } else {
 263                         if (dio)
 264                                 extent_cache_csums_dio(io_tree, offset, sum,
 265                                                        count);
 266                         else
 267                                 extent_cache_csums(io_tree, bio, bio_index, sum,
 268                                             count);
 269                 }
 270                 while (count--) {
 271                         disk_bytenr += bvec->bv_len;
 272                         offset += bvec->bv_len;
 273                         bio_index++;
 274                         bvec++;
 275                 }
 276         }
 277         btrfs_free_path(path);
 278         return 0;
 279 }
 280
 281 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 282                           struct bio *bio, u32 *dst)
 283 {
 284         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 285 }
 286
 287 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 288                               struct bio *bio, u64 offset)
 289 {
 290         return __btrfs_lookup_bio_sums(root, inode, bio, offset, NULL, 1);
 291 }
 292
 293 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 294                              struct list_head *list, int search_commit)
 295 {
 296         struct btrfs_key key;
 297         struct btrfs_path *path;
 298         struct extent_buffer *leaf;
 299         struct btrfs_ordered_sum *sums;
 300         struct btrfs_sector_sum *sector_sum;
 301         struct btrfs_csum_item *item;
 302         LIST_HEAD(tmplist);
 303         unsigned long offset;
 304         int ret;
 305         size_t size;
 306         u64 csum_end;
 307         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 308
 309         path = btrfs_alloc_path();
 310         if (!path)
 311                 return -ENOMEM;
 312
 313         if (search_commit) {
 314                 path->skip_locking = 1;
 315                 path->reada = 2;
 316                 path->search_commit_root = 1;
 317         }
 318
 319         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 320         key.offset = start;
 321         key.type = BTRFS_EXTENT_CSUM_KEY;
 322
 323         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 324         if (ret < 0)
 325                 goto fail;
 326         if (ret > 0 && path->slots[0] > 0) {
 327                 leaf = path->nodes[0];
 328                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 329                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 330                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 331                         offset = (start - key.offset) >>
 332                                  root->fs_info->sb->s_blocksize_bits;
 333                         if (offset * csum_size <
 334                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 335                                 path->slots[0]--;
 336                 }
 337         }
 338
 339         while (start <= end) {
 340                 leaf = path->nodes[0];
 341                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 342                         ret = btrfs_next_leaf(root, path);
 343                         if (ret < 0)
 344                                 goto fail;
 345                         if (ret > 0)
 346                                 break;
 347                         leaf = path->nodes[0];
 348                 }
 349
 350                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 351                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 352                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 353                     key.offset > end)
 354                         break;
 355
 356                 if (key.offset > start)
 357                         start = key.offset;
 358
 359                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 360                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 361                 if (csum_end <= start) {
 362                         path->slots[0]++;
 363                         continue;
 364                 }
 365
 366                 csum_end = min(csum_end, end + 1);
 367                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 368                                       struct btrfs_csum_item);
 369                 while (start < csum_end) {
 370                         size = min_t(size_t, csum_end - start,
 371                                         MAX_ORDERED_SUM_BYTES(root));
 372                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 373                                         GFP_NOFS);
 374                         if (!sums) {
 375                                 ret = -ENOMEM;
 376                                 goto fail;
 377                         }
 378
 379                         sector_sum = sums->sums;
 380                         sums->bytenr = start;
 381                         sums->len = size;
 382
 383                         offset = (start - key.offset) >>
 384                                 root->fs_info->sb->s_blocksize_bits;
 385                         offset *= csum_size;
 386
 387                         while (size > 0) {
 388                                 read_extent_buffer(path->nodes[0],
 389                                                 &sector_sum->sum,
 390                                                 ((unsigned long)item) +
 391                                                 offset, csum_size);
 392                                 sector_sum->bytenr = start;
 393
 394                                 size -= root->sectorsize;
 395                                 start += root->sectorsize;
 396                                 offset += csum_size;
 397                                 sector_sum++;
 398                         }
 399                         list_add_tail(&sums->list, &tmplist);
 400                 }
 401                 path->slots[0]++;
 402         }
 403         ret = 0;
 404 fail:
 405         while (ret < 0 && !list_empty(&tmplist)) {
 406                 sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
 407                 list_del(&sums->list);
 408                 kfree(sums);
 409         }
 410         list_splice_tail(&tmplist, list);
 411
 412         btrfs_free_path(path);
 413         return ret;
 414 }
 415
 416 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 417                        struct bio *bio, u64 file_start, int contig)
 418 {
 419         struct btrfs_ordered_sum *sums;
 420         struct btrfs_sector_sum *sector_sum;
 421         struct btrfs_ordered_extent *ordered;
 422         char *data;
 423         struct bio_vec *bvec = bio->bi_io_vec;
 424         int bio_index = 0;
 425         unsigned long total_bytes = 0;
 426         unsigned long this_sum_bytes = 0;
 427         u64 offset;
 428         u64 disk_bytenr;
 429
 430         WARN_ON(bio->bi_vcnt <= 0);
 431         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 432         if (!sums)
 433                 return -ENOMEM;
 434
 435         sector_sum = sums->sums;
 436         disk_bytenr = (u64)bio->bi_sector << 9;
 437         sums->len = bio->bi_size;
 438         INIT_LIST_HEAD(&sums->list);
 439
 440         if (contig)
 441                 offset = file_start;
 442         else
 443                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 444
 445         ordered = btrfs_lookup_ordered_extent(inode, offset);
 446         BUG_ON(!ordered); /* Logic error */
 447         sums->bytenr = ordered->start;
 448
 449         while (bio_index < bio->bi_vcnt) {
 450                 if (!contig)
 451                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 452
 453                 if (offset >= ordered->file_offset + ordered->len ||
 454                     offset < ordered->file_offset) {
 455                         unsigned long bytes_left;
 456                         sums->len = this_sum_bytes;
 457                         this_sum_bytes = 0;
 458                         btrfs_add_ordered_sum(inode, ordered, sums);
 459                         btrfs_put_ordered_extent(ordered);
 460
 461                         bytes_left = bio->bi_size - total_bytes;
 462
 463                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 464                                        GFP_NOFS);
 465                         BUG_ON(!sums); /* -ENOMEM */
 466                         sector_sum = sums->sums;
 467                         sums->len = bytes_left;
 468                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 469                         BUG_ON(!ordered); /* Logic error */
 470                         sums->bytenr = ordered->start;
 471                 }
 472
 473                 data = kmap_atomic(bvec->bv_page);
 474                 sector_sum->sum = ~(u32)0;
 475                 sector_sum->sum = btrfs_csum_data(data + bvec->bv_offset,
 476                                                   sector_sum->sum,
 477                                                   bvec->bv_len);
 478                 kunmap_atomic(data);
 479                 btrfs_csum_final(sector_sum->sum,
 480                                  (char *)&sector_sum->sum);
 481                 sector_sum->bytenr = disk_bytenr;
 482
 483                 sector_sum++;
 484                 bio_index++;
 485                 total_bytes += bvec->bv_len;
 486                 this_sum_bytes += bvec->bv_len;
 487                 disk_bytenr += bvec->bv_len;
 488                 offset += bvec->bv_len;
 489                 bvec++;
 490         }
 491         this_sum_bytes = 0;
 492         btrfs_add_ordered_sum(inode, ordered, sums);
 493         btrfs_put_ordered_extent(ordered);
 494         return 0;
 495 }
 496
 497 /*
 498  * helper function for csum removal, this expects the
 499  * key to describe the csum pointed to by the path, and it expects
 500  * the csum to overlap the range [bytenr, len]
 501  *
 502  * The csum should not be entirely contained in the range and the
 503  * range should not be entirely contained in the csum.
 504  *
 505  * This calls btrfs_truncate_item with the correct args based on the
 506  * overlap, and fixes up the key as required.
 507  */
 508 static noinline void truncate_one_csum(struct btrfs_root *root,
 509                                        struct btrfs_path *path,
 510                                        struct btrfs_key *key,
 511                                        u64 bytenr, u64 len)
 512 {
 513         struct extent_buffer *leaf;
 514         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 515         u64 csum_end;
 516         u64 end_byte = bytenr + len;
 517         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 518
 519         leaf = path->nodes[0];
 520         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 521         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 522         csum_end += key->offset;
 523
 524         if (key->offset < bytenr && csum_end <= end_byte) {
 525                 /*
 526                  *         [ bytenr - len ]
 527                  *         [   ]
 528                  *   [csum     ]
 529                  *   A simple truncate off the end of the item
 530                  */
 531                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 532                 new_size *= csum_size;
 533                 btrfs_truncate_item(root, path, new_size, 1);
 534         } else if (key->offset >= bytenr && csum_end > end_byte &&
 535                    end_byte > key->offset) {
 536                 /*
 537                  *         [ bytenr - len ]
 538                  *                 [ ]
 539                  *                 [csum     ]
 540                  * we need to truncate from the beginning of the csum
 541                  */
 542                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 543                 new_size *= csum_size;
 544
 545                 btrfs_truncate_item(root, path, new_size, 0);
 546
 547                 key->offset = end_byte;
 548                 btrfs_set_item_key_safe(root, path, key);
 549         } else {
 550                 BUG();
 551         }
 552 }
 553
 554 /*
 555  * deletes the csum items from the csum tree for a given
 556  * range of bytes.
 557  */
 558 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 559                     struct btrfs_root *root, u64 bytenr, u64 len)
 560 {
 561         struct btrfs_path *path;
 562         struct btrfs_key key;
 563         u64 end_byte = bytenr + len;
 564         u64 csum_end;
 565         struct extent_buffer *leaf;
 566         int ret;
 567         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 568         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 569
 570         root = root->fs_info->csum_root;
 571
 572         path = btrfs_alloc_path();
 573         if (!path)
 574                 return -ENOMEM;
 575
 576         while (1) {
 577                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 578                 key.offset = end_byte - 1;
 579                 key.type = BTRFS_EXTENT_CSUM_KEY;
 580
 581                 path->leave_spinning = 1;
 582                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 583                 if (ret > 0) {
 584                         if (path->slots[0] == 0)
 585                                 break;
 586                         path->slots[0]--;
 587                 } else if (ret < 0) {
 588                         break;
 589                 }
 590
 591                 leaf = path->nodes[0];
 592                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 593
 594                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 595                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 596                         break;
 597                 }
 598
 599                 if (key.offset >= end_byte)
 600                         break;
 601
 602                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 603                 csum_end <<= blocksize_bits;
 604                 csum_end += key.offset;
 605
 606                 /* this csum ends before we start, we're done */
 607                 if (csum_end <= bytenr)
 608                         break;
 609
 610                 /* delete the entire item, it is inside our range */
 611                 if (key.offset >= bytenr && csum_end <= end_byte) {
 612                         ret = btrfs_del_item(trans, root, path);
 613                         if (ret)
 614                                 goto out;
 615                         if (key.offset == bytenr)
 616                                 break;
 617                 } else if (key.offset < bytenr && csum_end > end_byte) {
 618                         unsigned long offset;
 619                         unsigned long shift_len;
 620                         unsigned long item_offset;
 621                         /*
 622                          *        [ bytenr - len ]
 623                          *     [csum                ]
 624                          *
 625                          * Our bytes are in the middle of the csum,
 626                          * we need to split this item and insert a new one.
 627                          *
 628                          * But we can't drop the path because the
 629                          * csum could change, get removed, extended etc.
 630                          *
 631                          * The trick here is the max size of a csum item leaves
 632                          * enough room in the tree block for a single
 633                          * item header.  So, we split the item in place,
 634                          * adding a new header pointing to the existing
 635                          * bytes.  Then we loop around again and we have
 636                          * a nicely formed csum item that we can neatly
 637                          * truncate.
 638                          */
 639                         offset = (bytenr - key.offset) >> blocksize_bits;
 640                         offset *= csum_size;
 641
 642                         shift_len = (len >> blocksize_bits) * csum_size;
 643
 644                         item_offset = btrfs_item_ptr_offset(leaf,
 645                                                             path->slots[0]);
 646
 647                         memset_extent_buffer(leaf, 0, item_offset + offset,
 648                                              shift_len);
 649                         key.offset = bytenr;
 650
 651                         /*
 652                          * btrfs_split_item returns -EAGAIN when the
 653                          * item changed size or key
 654                          */
 655                         ret = btrfs_split_item(trans, root, path, &key, offset);
 656                         if (ret && ret != -EAGAIN) {
 657                                 btrfs_abort_transaction(trans, root, ret);
 658                                 goto out;
 659                         }
 660
 661                         key.offset = end_byte - 1;
 662                 } else {
 663                         truncate_one_csum(root, path, &key, bytenr, len);
 664                         if (key.offset < bytenr)
 665                                 break;
 666                 }
 667                 btrfs_release_path(path);
 668         }
 669         ret = 0;
 670 out:
 671         btrfs_free_path(path);
 672         return ret;
 673 }
 674
 675 static u64 btrfs_sector_sum_left(struct btrfs_ordered_sum *sums,
 676                                  struct btrfs_sector_sum *sector_sum,
 677                                  u64 total_bytes, u64 sectorsize)
 678 {
 679         u64 tmp = sectorsize;
 680         u64 next_sector = sector_sum->bytenr;
 681         struct btrfs_sector_sum *next = sector_sum + 1;
 682
 683         while ((tmp + total_bytes) < sums->len) {
 684                 if (next_sector + sectorsize != next->bytenr)
 685                         break;
 686                 tmp += sectorsize;
 687                 next_sector = next->bytenr;
 688                 next++;
 689         }
 690         return tmp;
 691 }
 692
 693 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 694                            struct btrfs_root *root,
 695                            struct btrfs_ordered_sum *sums)
 696 {
 697         u64 bytenr;
 698         int ret;
 699         struct btrfs_key file_key;
 700         struct btrfs_key found_key;
 701         u64 next_offset;
 702         u64 total_bytes = 0;
 703         int found_next;
 704         struct btrfs_path *path;
 705         struct btrfs_csum_item *item;
 706         struct btrfs_csum_item *item_end;
 707         struct extent_buffer *leaf = NULL;
 708         u64 csum_offset;
 709         struct btrfs_sector_sum *sector_sum;
 710         u32 nritems;
 711         u32 ins_size;
 712         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 713
 714         path = btrfs_alloc_path();
 715         if (!path)
 716                 return -ENOMEM;
 717
 718         sector_sum = sums->sums;
 719 again:
 720         next_offset = (u64)-1;
 721         found_next = 0;
 722         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 723         file_key.offset = sector_sum->bytenr;
 724         bytenr = sector_sum->bytenr;
 725         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 726
 727         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
 728         if (!IS_ERR(item)) {
 729                 leaf = path->nodes[0];
 730                 ret = 0;
 731                 goto found;
 732         }
 733         ret = PTR_ERR(item);
 734         if (ret != -EFBIG && ret != -ENOENT)
 735                 goto fail_unlock;
 736
 737         if (ret == -EFBIG) {
 738                 u32 item_size;
 739                 /* we found one, but it isn't big enough yet */
 740                 leaf = path->nodes[0];
 741                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 742                 if ((item_size / csum_size) >=
 743                     MAX_CSUM_ITEMS(root, csum_size)) {
 744                         /* already at max size, make a new one */
 745                         goto insert;
 746                 }
 747         } else {
 748                 int slot = path->slots[0] + 1;
 749                 /* we didn't find a csum item, insert one */
 750                 nritems = btrfs_header_nritems(path->nodes[0]);
 751                 if (path->slots[0] >= nritems - 1) {
 752                         ret = btrfs_next_leaf(root, path);
 753                         if (ret == 1)
 754                                 found_next = 1;
 755                         if (ret != 0)
 756                                 goto insert;
 757                         slot = 0;
 758                 }
 759                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 760                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 761                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 762                         found_next = 1;
 763                         goto insert;
 764                 }
 765                 next_offset = found_key.offset;
 766                 found_next = 1;
 767                 goto insert;
 768         }
 769
 770         /*
 771          * at this point, we know the tree has an item, but it isn't big
 772          * enough yet to put our csum in.  Grow it
 773          */
 774         btrfs_release_path(path);
 775         ret = btrfs_search_slot(trans, root, &file_key, path,
 776                                 csum_size, 1);
 777         if (ret < 0)
 778                 goto fail_unlock;
 779
 780         if (ret > 0) {
 781                 if (path->slots[0] == 0)
 782                         goto insert;
 783                 path->slots[0]--;
 784         }
 785
 786         leaf = path->nodes[0];
 787         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 788         csum_offset = (bytenr - found_key.offset) >>
 789                         root->fs_info->sb->s_blocksize_bits;
 790
 791         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 792             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 793             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 794                 goto insert;
 795         }
 796
 797         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 798             csum_size) {
 799                 int extend_nr;
 800                 u64 tmp;
 801                 u32 diff;
 802                 u32 free_space;
 803
 804                 if (btrfs_leaf_free_space(root, leaf) <
 805                                  sizeof(struct btrfs_item) + csum_size * 2)
 806                         goto insert;
 807
 808                 free_space = btrfs_leaf_free_space(root, leaf) -
 809                                          sizeof(struct btrfs_item) - csum_size;
 810                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 811                                             root->sectorsize);
 812                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 813                 WARN_ON(tmp < 1);
 814
 815                 extend_nr = max_t(int, 1, (int)tmp);
 816                 diff = (csum_offset + extend_nr) * csum_size;
 817                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 818
 819                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 820                 diff = min(free_space, diff);
 821                 diff /= csum_size;
 822                 diff *= csum_size;
 823
 824                 btrfs_extend_item(root, path, diff);
 825                 goto csum;
 826         }
 827
 828 insert:
 829         btrfs_release_path(path);
 830         csum_offset = 0;
 831         if (found_next) {
 832                 u64 tmp;
 833
 834                 tmp = btrfs_sector_sum_left(sums, sector_sum, total_bytes,
 835                                             root->sectorsize);
 836                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 837                 tmp = min(tmp, (next_offset - file_key.offset) >>
 838                                          root->fs_info->sb->s_blocksize_bits);
 839
 840                 tmp = max((u64)1, tmp);
 841                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 842                 ins_size = csum_size * tmp;
 843         } else {
 844                 ins_size = csum_size;
 845         }
 846         path->leave_spinning = 1;
 847         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 848                                       ins_size);
 849         path->leave_spinning = 0;
 850         if (ret < 0)
 851                 goto fail_unlock;
 852         if (ret != 0) {
 853                 WARN_ON(1);
 854                 goto fail_unlock;
 855         }
 856 csum:
 857         leaf = path->nodes[0];
 858         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 859         ret = 0;
 860         item = (struct btrfs_csum_item *)((unsigned char *)item +
 861                                           csum_offset * csum_size);
 862 found:
 863         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 864         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
 865                                       btrfs_item_size_nr(leaf, path->slots[0]));
 866 next_sector:
 867
 868         write_extent_buffer(leaf, &sector_sum->sum, (unsigned long)item, csum_size);
 869
 870         total_bytes += root->sectorsize;
 871         sector_sum++;
 872         if (total_bytes < sums->len) {
 873                 item = (struct btrfs_csum_item *)((char *)item +
 874                                                   csum_size);
 875                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
 876                     sector_sum->bytenr) {
 877                         bytenr = sector_sum->bytenr;
 878                         goto next_sector;
 879                 }
 880         }
 881
 882         btrfs_mark_buffer_dirty(path->nodes[0]);
 883         if (total_bytes < sums->len) {
 884                 btrfs_release_path(path);
 885                 cond_resched();
 886                 goto again;
 887         }
 888 out:
 889         btrfs_free_path(path);
 890         return ret;
 891
 892 fail_unlock:
 893         goto out;
 894 }