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 "volumes.h"
  27 #include "print-tree.h"
  28
  29 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  30                                    sizeof(struct btrfs_item) * 2) / \
  31                                   size) - 1))
  32
  33 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  34                                        PAGE_CACHE_SIZE))
  35
  36 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
  37                                    sizeof(struct btrfs_ordered_sum)) / \
  38                                    sizeof(u32) * (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 void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)
 157 {
 158         kfree(bio->csum_allocated);
 159 }
 160
 161 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 162                                    struct inode *inode, struct bio *bio,
 163                                    u64 logical_offset, u32 *dst, int dio)
 164 {
 165         struct bio_vec *bvec = bio->bi_io_vec;
 166         struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
 167         struct btrfs_csum_item *item = NULL;
 168         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 169         struct btrfs_path *path;
 170         u8 *csum;
 171         u64 offset = 0;
 172         u64 item_start_offset = 0;
 173         u64 item_last_offset = 0;
 174         u64 disk_bytenr;
 175         u32 diff;
 176         int nblocks;
 177         int bio_index = 0;
 178         int count;
 179         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 180
 181         path = btrfs_alloc_path();
 182         if (!path)
 183                 return -ENOMEM;
 184
 185         nblocks = bio->bi_size >> inode->i_sb->s_blocksize_bits;
 186         if (!dst) {
 187                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 188                         btrfs_bio->csum_allocated = kmalloc(nblocks * csum_size,
 189                                                             GFP_NOFS);
 190                         if (!btrfs_bio->csum_allocated) {
 191                                 btrfs_free_path(path);
 192                                 return -ENOMEM;
 193                         }
 194                         btrfs_bio->csum = btrfs_bio->csum_allocated;
 195                         btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
 196                 } else {
 197                         btrfs_bio->csum = btrfs_bio->csum_inline;
 198                 }
 199                 csum = btrfs_bio->csum;
 200         } else {
 201                 csum = (u8 *)dst;
 202         }
 203
 204         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
 205                 path->reada = 2;
 206
 207         WARN_ON(bio->bi_vcnt <= 0);
 208
 209         /*
 210          * the free space stuff is only read when it hasn't been
 211          * updated in the current transaction.  So, we can safely
 212          * read from the commit root and sidestep a nasty deadlock
 213          * between reading the free space cache and updating the csum tree.
 214          */
 215         if (btrfs_is_free_space_inode(inode)) {
 216                 path->search_commit_root = 1;
 217                 path->skip_locking = 1;
 218         }
 219
 220         disk_bytenr = (u64)bio->bi_sector << 9;
 221         if (dio)
 222                 offset = logical_offset;
 223         while (bio_index < bio->bi_vcnt) {
 224                 if (!dio)
 225                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 226                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 227                                                (u32 *)csum, nblocks);
 228                 if (count)
 229                         goto found;
 230
 231                 if (!item || disk_bytenr < item_start_offset ||
 232                     disk_bytenr >= item_last_offset) {
 233                         struct btrfs_key found_key;
 234                         u32 item_size;
 235
 236                         if (item)
 237                                 btrfs_release_path(path);
 238                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 239                                                  path, disk_bytenr, 0);
 240                         if (IS_ERR(item)) {
 241                                 count = 1;
 242                                 memset(csum, 0, csum_size);
 243                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 244                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 245                                         set_extent_bits(io_tree, offset,
 246                                                 offset + bvec->bv_len - 1,
 247                                                 EXTENT_NODATASUM, GFP_NOFS);
 248                                 } else {
 249                                         printk(KERN_INFO "btrfs no csum found "
 250                                                "for inode %llu start %llu\n",
 251                                                btrfs_ino(inode), offset);
 252                                 }
 253                                 item = NULL;
 254                                 btrfs_release_path(path);
 255                                 goto found;
 256                         }
 257                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 258                                               path->slots[0]);
 259
 260                         item_start_offset = found_key.offset;
 261                         item_size = btrfs_item_size_nr(path->nodes[0],
 262                                                        path->slots[0]);
 263                         item_last_offset = item_start_offset +
 264                                 (item_size / csum_size) *
 265                                 root->sectorsize;
 266                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 267                                               struct btrfs_csum_item);
 268                 }
 269                 /*
 270                  * this byte range must be able to fit inside
 271                  * a single leaf so it will also fit inside a u32
 272                  */
 273                 diff = disk_bytenr - item_start_offset;
 274                 diff = diff / root->sectorsize;
 275                 diff = diff * csum_size;
 276                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 277                                             inode->i_sb->s_blocksize_bits);
 278                 read_extent_buffer(path->nodes[0], csum,
 279                                    ((unsigned long)item) + diff,
 280                                    csum_size * count);
 281 found:
 282                 csum += count * csum_size;
 283                 nblocks -= count;
 284                 while (count--) {
 285                         disk_bytenr += bvec->bv_len;
 286                         offset += bvec->bv_len;
 287                         bio_index++;
 288                         bvec++;
 289                 }
 290         }
 291         btrfs_free_path(path);
 292         return 0;
 293 }
 294
 295 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 296                           struct bio *bio, u32 *dst)
 297 {
 298         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 299 }
 300
 301 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 302                               struct btrfs_dio_private *dip, struct bio *bio,
 303                               u64 offset)
 304 {
 305         int len = (bio->bi_sector << 9) - dip->disk_bytenr;
 306         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 307         int ret;
 308
 309         len >>= inode->i_sb->s_blocksize_bits;
 310         len *= csum_size;
 311
 312         ret = __btrfs_lookup_bio_sums(root, inode, bio, offset,
 313                                       (u32 *)(dip->csum + len), 1);
 314         return ret;
 315 }
 316
 317 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 318                              struct list_head *list, int search_commit)
 319 {
 320         struct btrfs_key key;
 321         struct btrfs_path *path;
 322         struct extent_buffer *leaf;
 323         struct btrfs_ordered_sum *sums;
 324         struct btrfs_csum_item *item;
 325         LIST_HEAD(tmplist);
 326         unsigned long offset;
 327         int ret;
 328         size_t size;
 329         u64 csum_end;
 330         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 331
 332         path = btrfs_alloc_path();
 333         if (!path)
 334                 return -ENOMEM;
 335
 336         if (search_commit) {
 337                 path->skip_locking = 1;
 338                 path->reada = 2;
 339                 path->search_commit_root = 1;
 340         }
 341
 342         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 343         key.offset = start;
 344         key.type = BTRFS_EXTENT_CSUM_KEY;
 345
 346         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 347         if (ret < 0)
 348                 goto fail;
 349         if (ret > 0 && path->slots[0] > 0) {
 350                 leaf = path->nodes[0];
 351                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 352                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 353                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 354                         offset = (start - key.offset) >>
 355                                  root->fs_info->sb->s_blocksize_bits;
 356                         if (offset * csum_size <
 357                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 358                                 path->slots[0]--;
 359                 }
 360         }
 361
 362         while (start <= end) {
 363                 leaf = path->nodes[0];
 364                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 365                         ret = btrfs_next_leaf(root, path);
 366                         if (ret < 0)
 367                                 goto fail;
 368                         if (ret > 0)
 369                                 break;
 370                         leaf = path->nodes[0];
 371                 }
 372
 373                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 374                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 375                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 376                     key.offset > end)
 377                         break;
 378
 379                 if (key.offset > start)
 380                         start = key.offset;
 381
 382                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 383                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 384                 if (csum_end <= start) {
 385                         path->slots[0]++;
 386                         continue;
 387                 }
 388
 389                 csum_end = min(csum_end, end + 1);
 390                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 391                                       struct btrfs_csum_item);
 392                 while (start < csum_end) {
 393                         size = min_t(size_t, csum_end - start,
 394                                      MAX_ORDERED_SUM_BYTES(root));
 395                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 396                                        GFP_NOFS);
 397                         if (!sums) {
 398                                 ret = -ENOMEM;
 399                                 goto fail;
 400                         }
 401
 402                         sums->bytenr = start;
 403                         sums->len = (int)size;
 404
 405                         offset = (start - key.offset) >>
 406                                 root->fs_info->sb->s_blocksize_bits;
 407                         offset *= csum_size;
 408                         size >>= root->fs_info->sb->s_blocksize_bits;
 409
 410                         read_extent_buffer(path->nodes[0],
 411                                            sums->sums,
 412                                            ((unsigned long)item) + offset,
 413                                            csum_size * size);
 414
 415                         start += root->sectorsize * size;
 416                         list_add_tail(&sums->list, &tmplist);
 417                 }
 418                 path->slots[0]++;
 419         }
 420         ret = 0;
 421 fail:
 422         while (ret < 0 && !list_empty(&tmplist)) {
 423                 sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
 424                 list_del(&sums->list);
 425                 kfree(sums);
 426         }
 427         list_splice_tail(&tmplist, list);
 428
 429         btrfs_free_path(path);
 430         return ret;
 431 }
 432
 433 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 434                        struct bio *bio, u64 file_start, int contig)
 435 {
 436         struct btrfs_ordered_sum *sums;
 437         struct btrfs_ordered_extent *ordered;
 438         char *data;
 439         struct bio_vec *bvec = bio->bi_io_vec;
 440         int bio_index = 0;
 441         int index;
 442         unsigned long total_bytes = 0;
 443         unsigned long this_sum_bytes = 0;
 444         u64 offset;
 445
 446         WARN_ON(bio->bi_vcnt <= 0);
 447         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 448         if (!sums)
 449                 return -ENOMEM;
 450
 451         sums->len = bio->bi_size;
 452         INIT_LIST_HEAD(&sums->list);
 453
 454         if (contig)
 455                 offset = file_start;
 456         else
 457                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 458
 459         ordered = btrfs_lookup_ordered_extent(inode, offset);
 460         BUG_ON(!ordered); /* Logic error */
 461         sums->bytenr = (u64)bio->bi_sector << 9;
 462         index = 0;
 463
 464         while (bio_index < bio->bi_vcnt) {
 465                 if (!contig)
 466                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 467
 468                 if (offset >= ordered->file_offset + ordered->len ||
 469                     offset < ordered->file_offset) {
 470                         unsigned long bytes_left;
 471                         sums->len = this_sum_bytes;
 472                         this_sum_bytes = 0;
 473                         btrfs_add_ordered_sum(inode, ordered, sums);
 474                         btrfs_put_ordered_extent(ordered);
 475
 476                         bytes_left = bio->bi_size - total_bytes;
 477
 478                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 479                                        GFP_NOFS);
 480                         BUG_ON(!sums); /* -ENOMEM */
 481                         sums->len = bytes_left;
 482                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 483                         BUG_ON(!ordered); /* Logic error */
 484                         sums->bytenr = ((u64)bio->bi_sector << 9) +
 485                                        total_bytes;
 486                         index = 0;
 487                 }
 488
 489                 data = kmap_atomic(bvec->bv_page);
 490                 sums->sums[index] = ~(u32)0;
 491                 sums->sums[index] = btrfs_csum_data(data + bvec->bv_offset,
 492                                                     sums->sums[index],
 493                                                     bvec->bv_len);
 494                 kunmap_atomic(data);
 495                 btrfs_csum_final(sums->sums[index],
 496                                  (char *)(sums->sums + index));
 497
 498                 bio_index++;
 499                 index++;
 500                 total_bytes += bvec->bv_len;
 501                 this_sum_bytes += bvec->bv_len;
 502                 offset += bvec->bv_len;
 503                 bvec++;
 504         }
 505         this_sum_bytes = 0;
 506         btrfs_add_ordered_sum(inode, ordered, sums);
 507         btrfs_put_ordered_extent(ordered);
 508         return 0;
 509 }
 510
 511 /*
 512  * helper function for csum removal, this expects the
 513  * key to describe the csum pointed to by the path, and it expects
 514  * the csum to overlap the range [bytenr, len]
 515  *
 516  * The csum should not be entirely contained in the range and the
 517  * range should not be entirely contained in the csum.
 518  *
 519  * This calls btrfs_truncate_item with the correct args based on the
 520  * overlap, and fixes up the key as required.
 521  */
 522 static noinline void truncate_one_csum(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(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(root, path, new_size, 0);
 560
 561                 key->offset = end_byte;
 562                 btrfs_set_item_key_safe(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(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 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 690                            struct btrfs_root *root,
 691                            struct btrfs_ordered_sum *sums)
 692 {
 693         struct btrfs_key file_key;
 694         struct btrfs_key found_key;
 695         struct btrfs_path *path;
 696         struct btrfs_csum_item *item;
 697         struct btrfs_csum_item *item_end;
 698         struct extent_buffer *leaf = NULL;
 699         u64 next_offset;
 700         u64 total_bytes = 0;
 701         u64 csum_offset;
 702         u64 bytenr;
 703         u32 nritems;
 704         u32 ins_size;
 705         int index = 0;
 706         int found_next;
 707         int ret;
 708         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 709
 710         path = btrfs_alloc_path();
 711         if (!path)
 712                 return -ENOMEM;
 713 again:
 714         next_offset = (u64)-1;
 715         found_next = 0;
 716         bytenr = sums->bytenr + total_bytes;
 717         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 718         file_key.offset = bytenr;
 719         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 720
 721         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 722         if (!IS_ERR(item)) {
 723                 ret = 0;
 724                 leaf = path->nodes[0];
 725                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 726                                           struct btrfs_csum_item);
 727                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 728                            btrfs_item_size_nr(leaf, path->slots[0]));
 729                 goto found;
 730         }
 731         ret = PTR_ERR(item);
 732         if (ret != -EFBIG && ret != -ENOENT)
 733                 goto fail_unlock;
 734
 735         if (ret == -EFBIG) {
 736                 u32 item_size;
 737                 /* we found one, but it isn't big enough yet */
 738                 leaf = path->nodes[0];
 739                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 740                 if ((item_size / csum_size) >=
 741                     MAX_CSUM_ITEMS(root, csum_size)) {
 742                         /* already at max size, make a new one */
 743                         goto insert;
 744                 }
 745         } else {
 746                 int slot = path->slots[0] + 1;
 747                 /* we didn't find a csum item, insert one */
 748                 nritems = btrfs_header_nritems(path->nodes[0]);
 749                 if (path->slots[0] >= nritems - 1) {
 750                         ret = btrfs_next_leaf(root, path);
 751                         if (ret == 1)
 752                                 found_next = 1;
 753                         if (ret != 0)
 754                                 goto insert;
 755                         slot = 0;
 756                 }
 757                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 758                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 759                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 760                         found_next = 1;
 761                         goto insert;
 762                 }
 763                 next_offset = found_key.offset;
 764                 found_next = 1;
 765                 goto insert;
 766         }
 767
 768         /*
 769          * at this point, we know the tree has an item, but it isn't big
 770          * enough yet to put our csum in.  Grow it
 771          */
 772         btrfs_release_path(path);
 773         ret = btrfs_search_slot(trans, root, &file_key, path,
 774                                 csum_size, 1);
 775         if (ret < 0)
 776                 goto fail_unlock;
 777
 778         if (ret > 0) {
 779                 if (path->slots[0] == 0)
 780                         goto insert;
 781                 path->slots[0]--;
 782         }
 783
 784         leaf = path->nodes[0];
 785         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 786         csum_offset = (bytenr - found_key.offset) >>
 787                         root->fs_info->sb->s_blocksize_bits;
 788
 789         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
 790             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 791             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 792                 goto insert;
 793         }
 794
 795         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 796             csum_size) {
 797                 int extend_nr;
 798                 u64 tmp;
 799                 u32 diff;
 800                 u32 free_space;
 801
 802                 if (btrfs_leaf_free_space(root, leaf) <
 803                                  sizeof(struct btrfs_item) + csum_size * 2)
 804                         goto insert;
 805
 806                 free_space = btrfs_leaf_free_space(root, leaf) -
 807                                          sizeof(struct btrfs_item) - csum_size;
 808                 tmp = sums->len - total_bytes;
 809                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 810                 WARN_ON(tmp < 1);
 811
 812                 extend_nr = max_t(int, 1, (int)tmp);
 813                 diff = (csum_offset + extend_nr) * csum_size;
 814                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 815
 816                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 817                 diff = min(free_space, diff);
 818                 diff /= csum_size;
 819                 diff *= csum_size;
 820
 821                 btrfs_extend_item(root, path, diff);
 822                 ret = 0;
 823                 goto csum;
 824         }
 825
 826 insert:
 827         btrfs_release_path(path);
 828         csum_offset = 0;
 829         if (found_next) {
 830                 u64 tmp;
 831
 832                 tmp = sums->len - total_bytes;
 833                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 834                 tmp = min(tmp, (next_offset - file_key.offset) >>
 835                                          root->fs_info->sb->s_blocksize_bits);
 836
 837                 tmp = max((u64)1, tmp);
 838                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 839                 ins_size = csum_size * tmp;
 840         } else {
 841                 ins_size = csum_size;
 842         }
 843         path->leave_spinning = 1;
 844         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 845                                       ins_size);
 846         path->leave_spinning = 0;
 847         if (ret < 0)
 848                 goto fail_unlock;
 849         if (ret != 0) {
 850                 WARN_ON(1);
 851                 goto fail_unlock;
 852         }
 853         leaf = path->nodes[0];
 854 csum:
 855         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 856         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 857                                       btrfs_item_size_nr(leaf, path->slots[0]));
 858         item = (struct btrfs_csum_item *)((unsigned char *)item +
 859                                           csum_offset * csum_size);
 860 found:
 861         ins_size = (u32)(sums->len - total_bytes) >>
 862                    root->fs_info->sb->s_blocksize_bits;
 863         ins_size *= csum_size;
 864         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 865                               ins_size);
 866         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 867                             ins_size);
 868
 869         ins_size /= csum_size;
 870         total_bytes += ins_size * root->sectorsize;
 871         index += ins_size;
 872
 873         btrfs_mark_buffer_dirty(path->nodes[0]);
 874         if (total_bytes < sums->len) {
 875                 btrfs_release_path(path);
 876                 cond_resched();
 877                 goto again;
 878         }
 879 out:
 880         btrfs_free_path(path);
 881         return ret;
 882
 883 fail_unlock:
 884         goto out;
 885 }