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                                                (unsigned long long)
 252                                                btrfs_ino(inode),
 253                                                (unsigned long long)offset);
 254                                 }
 255                                 item = NULL;
 256                                 btrfs_release_path(path);
 257                                 goto found;
 258                         }
 259                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 260                                               path->slots[0]);
 261
 262                         item_start_offset = found_key.offset;
 263                         item_size = btrfs_item_size_nr(path->nodes[0],
 264                                                        path->slots[0]);
 265                         item_last_offset = item_start_offset +
 266                                 (item_size / csum_size) *
 267                                 root->sectorsize;
 268                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 269                                               struct btrfs_csum_item);
 270                 }
 271                 /*
 272                  * this byte range must be able to fit inside
 273                  * a single leaf so it will also fit inside a u32
 274                  */
 275                 diff = disk_bytenr - item_start_offset;
 276                 diff = diff / root->sectorsize;
 277                 diff = diff * csum_size;
 278                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 279                                             inode->i_sb->s_blocksize_bits);
 280                 read_extent_buffer(path->nodes[0], csum,
 281                                    ((unsigned long)item) + diff,
 282                                    csum_size * count);
 283 found:
 284                 csum += count * csum_size;
 285                 nblocks -= count;
 286                 while (count--) {
 287                         disk_bytenr += bvec->bv_len;
 288                         offset += bvec->bv_len;
 289                         bio_index++;
 290                         bvec++;
 291                 }
 292         }
 293         btrfs_free_path(path);
 294         return 0;
 295 }
 296
 297 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 298                           struct bio *bio, u32 *dst)
 299 {
 300         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 301 }
 302
 303 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 304                               struct btrfs_dio_private *dip, struct bio *bio,
 305                               u64 offset)
 306 {
 307         int len = (bio->bi_sector << 9) - dip->disk_bytenr;
 308         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 309         int ret;
 310
 311         len >>= inode->i_sb->s_blocksize_bits;
 312         len *= csum_size;
 313
 314         ret = __btrfs_lookup_bio_sums(root, inode, bio, offset,
 315                                       (u32 *)(dip->csum + len), 1);
 316         return ret;
 317 }
 318
 319 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 320                              struct list_head *list, int search_commit)
 321 {
 322         struct btrfs_key key;
 323         struct btrfs_path *path;
 324         struct extent_buffer *leaf;
 325         struct btrfs_ordered_sum *sums;
 326         struct btrfs_csum_item *item;
 327         LIST_HEAD(tmplist);
 328         unsigned long offset;
 329         int ret;
 330         size_t size;
 331         u64 csum_end;
 332         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 333
 334         path = btrfs_alloc_path();
 335         if (!path)
 336                 return -ENOMEM;
 337
 338         if (search_commit) {
 339                 path->skip_locking = 1;
 340                 path->reada = 2;
 341                 path->search_commit_root = 1;
 342         }
 343
 344         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 345         key.offset = start;
 346         key.type = BTRFS_EXTENT_CSUM_KEY;
 347
 348         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 349         if (ret < 0)
 350                 goto fail;
 351         if (ret > 0 && path->slots[0] > 0) {
 352                 leaf = path->nodes[0];
 353                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 354                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 355                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 356                         offset = (start - key.offset) >>
 357                                  root->fs_info->sb->s_blocksize_bits;
 358                         if (offset * csum_size <
 359                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 360                                 path->slots[0]--;
 361                 }
 362         }
 363
 364         while (start <= end) {
 365                 leaf = path->nodes[0];
 366                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 367                         ret = btrfs_next_leaf(root, path);
 368                         if (ret < 0)
 369                                 goto fail;
 370                         if (ret > 0)
 371                                 break;
 372                         leaf = path->nodes[0];
 373                 }
 374
 375                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 376                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 377                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 378                     key.offset > end)
 379                         break;
 380
 381                 if (key.offset > start)
 382                         start = key.offset;
 383
 384                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 385                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 386                 if (csum_end <= start) {
 387                         path->slots[0]++;
 388                         continue;
 389                 }
 390
 391                 csum_end = min(csum_end, end + 1);
 392                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 393                                       struct btrfs_csum_item);
 394                 while (start < csum_end) {
 395                         size = min_t(size_t, csum_end - start,
 396                                      MAX_ORDERED_SUM_BYTES(root));
 397                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 398                                        GFP_NOFS);
 399                         if (!sums) {
 400                                 ret = -ENOMEM;
 401                                 goto fail;
 402                         }
 403
 404                         sums->bytenr = start;
 405                         sums->len = (int)size;
 406
 407                         offset = (start - key.offset) >>
 408                                 root->fs_info->sb->s_blocksize_bits;
 409                         offset *= csum_size;
 410                         size >>= root->fs_info->sb->s_blocksize_bits;
 411
 412                         read_extent_buffer(path->nodes[0],
 413                                            sums->sums,
 414                                            ((unsigned long)item) + offset,
 415                                            csum_size * size);
 416
 417                         start += root->sectorsize * size;
 418                         list_add_tail(&sums->list, &tmplist);
 419                 }
 420                 path->slots[0]++;
 421         }
 422         ret = 0;
 423 fail:
 424         while (ret < 0 && !list_empty(&tmplist)) {
 425                 sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
 426                 list_del(&sums->list);
 427                 kfree(sums);
 428         }
 429         list_splice_tail(&tmplist, list);
 430
 431         btrfs_free_path(path);
 432         return ret;
 433 }
 434
 435 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 436                        struct bio *bio, u64 file_start, int contig)
 437 {
 438         struct btrfs_ordered_sum *sums;
 439         struct btrfs_ordered_extent *ordered;
 440         char *data;
 441         struct bio_vec *bvec = bio->bi_io_vec;
 442         int bio_index = 0;
 443         int index;
 444         unsigned long total_bytes = 0;
 445         unsigned long this_sum_bytes = 0;
 446         u64 offset;
 447
 448         WARN_ON(bio->bi_vcnt <= 0);
 449         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
 450         if (!sums)
 451                 return -ENOMEM;
 452
 453         sums->len = bio->bi_size;
 454         INIT_LIST_HEAD(&sums->list);
 455
 456         if (contig)
 457                 offset = file_start;
 458         else
 459                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 460
 461         ordered = btrfs_lookup_ordered_extent(inode, offset);
 462         BUG_ON(!ordered); /* Logic error */
 463         sums->bytenr = (u64)bio->bi_sector << 9;
 464         index = 0;
 465
 466         while (bio_index < bio->bi_vcnt) {
 467                 if (!contig)
 468                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 469
 470                 if (offset >= ordered->file_offset + ordered->len ||
 471                     offset < ordered->file_offset) {
 472                         unsigned long bytes_left;
 473                         sums->len = this_sum_bytes;
 474                         this_sum_bytes = 0;
 475                         btrfs_add_ordered_sum(inode, ordered, sums);
 476                         btrfs_put_ordered_extent(ordered);
 477
 478                         bytes_left = bio->bi_size - total_bytes;
 479
 480                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 481                                        GFP_NOFS);
 482                         BUG_ON(!sums); /* -ENOMEM */
 483                         sums->len = bytes_left;
 484                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 485                         BUG_ON(!ordered); /* Logic error */
 486                         sums->bytenr = ((u64)bio->bi_sector << 9) +
 487                                        total_bytes;
 488                         index = 0;
 489                 }
 490
 491                 data = kmap_atomic(bvec->bv_page);
 492                 sums->sums[index] = ~(u32)0;
 493                 sums->sums[index] = btrfs_csum_data(data + bvec->bv_offset,
 494                                                     sums->sums[index],
 495                                                     bvec->bv_len);
 496                 kunmap_atomic(data);
 497                 btrfs_csum_final(sums->sums[index],
 498                                  (char *)(sums->sums + index));
 499
 500                 bio_index++;
 501                 index++;
 502                 total_bytes += bvec->bv_len;
 503                 this_sum_bytes += bvec->bv_len;
 504                 offset += bvec->bv_len;
 505                 bvec++;
 506         }
 507         this_sum_bytes = 0;
 508         btrfs_add_ordered_sum(inode, ordered, sums);
 509         btrfs_put_ordered_extent(ordered);
 510         return 0;
 511 }
 512
 513 /*
 514  * helper function for csum removal, this expects the
 515  * key to describe the csum pointed to by the path, and it expects
 516  * the csum to overlap the range [bytenr, len]
 517  *
 518  * The csum should not be entirely contained in the range and the
 519  * range should not be entirely contained in the csum.
 520  *
 521  * This calls btrfs_truncate_item with the correct args based on the
 522  * overlap, and fixes up the key as required.
 523  */
 524 static noinline void truncate_one_csum(struct btrfs_root *root,
 525                                        struct btrfs_path *path,
 526                                        struct btrfs_key *key,
 527                                        u64 bytenr, u64 len)
 528 {
 529         struct extent_buffer *leaf;
 530         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 531         u64 csum_end;
 532         u64 end_byte = bytenr + len;
 533         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 534
 535         leaf = path->nodes[0];
 536         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 537         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 538         csum_end += key->offset;
 539
 540         if (key->offset < bytenr && csum_end <= end_byte) {
 541                 /*
 542                  *         [ bytenr - len ]
 543                  *         [   ]
 544                  *   [csum     ]
 545                  *   A simple truncate off the end of the item
 546                  */
 547                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 548                 new_size *= csum_size;
 549                 btrfs_truncate_item(root, path, new_size, 1);
 550         } else if (key->offset >= bytenr && csum_end > end_byte &&
 551                    end_byte > key->offset) {
 552                 /*
 553                  *         [ bytenr - len ]
 554                  *                 [ ]
 555                  *                 [csum     ]
 556                  * we need to truncate from the beginning of the csum
 557                  */
 558                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 559                 new_size *= csum_size;
 560
 561                 btrfs_truncate_item(root, path, new_size, 0);
 562
 563                 key->offset = end_byte;
 564                 btrfs_set_item_key_safe(root, path, key);
 565         } else {
 566                 BUG();
 567         }
 568 }
 569
 570 /*
 571  * deletes the csum items from the csum tree for a given
 572  * range of bytes.
 573  */
 574 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 575                     struct btrfs_root *root, u64 bytenr, u64 len)
 576 {
 577         struct btrfs_path *path;
 578         struct btrfs_key key;
 579         u64 end_byte = bytenr + len;
 580         u64 csum_end;
 581         struct extent_buffer *leaf;
 582         int ret;
 583         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 584         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 585
 586         root = root->fs_info->csum_root;
 587
 588         path = btrfs_alloc_path();
 589         if (!path)
 590                 return -ENOMEM;
 591
 592         while (1) {
 593                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 594                 key.offset = end_byte - 1;
 595                 key.type = BTRFS_EXTENT_CSUM_KEY;
 596
 597                 path->leave_spinning = 1;
 598                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 599                 if (ret > 0) {
 600                         if (path->slots[0] == 0)
 601                                 break;
 602                         path->slots[0]--;
 603                 } else if (ret < 0) {
 604                         break;
 605                 }
 606
 607                 leaf = path->nodes[0];
 608                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 609
 610                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 611                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 612                         break;
 613                 }
 614
 615                 if (key.offset >= end_byte)
 616                         break;
 617
 618                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 619                 csum_end <<= blocksize_bits;
 620                 csum_end += key.offset;
 621
 622                 /* this csum ends before we start, we're done */
 623                 if (csum_end <= bytenr)
 624                         break;
 625
 626                 /* delete the entire item, it is inside our range */
 627                 if (key.offset >= bytenr && csum_end <= end_byte) {
 628                         ret = btrfs_del_item(trans, root, path);
 629                         if (ret)
 630                                 goto out;
 631                         if (key.offset == bytenr)
 632                                 break;
 633                 } else if (key.offset < bytenr && csum_end > end_byte) {
 634                         unsigned long offset;
 635                         unsigned long shift_len;
 636                         unsigned long item_offset;
 637                         /*
 638                          *        [ bytenr - len ]
 639                          *     [csum                ]
 640                          *
 641                          * Our bytes are in the middle of the csum,
 642                          * we need to split this item and insert a new one.
 643                          *
 644                          * But we can't drop the path because the
 645                          * csum could change, get removed, extended etc.
 646                          *
 647                          * The trick here is the max size of a csum item leaves
 648                          * enough room in the tree block for a single
 649                          * item header.  So, we split the item in place,
 650                          * adding a new header pointing to the existing
 651                          * bytes.  Then we loop around again and we have
 652                          * a nicely formed csum item that we can neatly
 653                          * truncate.
 654                          */
 655                         offset = (bytenr - key.offset) >> blocksize_bits;
 656                         offset *= csum_size;
 657
 658                         shift_len = (len >> blocksize_bits) * csum_size;
 659
 660                         item_offset = btrfs_item_ptr_offset(leaf,
 661                                                             path->slots[0]);
 662
 663                         memset_extent_buffer(leaf, 0, item_offset + offset,
 664                                              shift_len);
 665                         key.offset = bytenr;
 666
 667                         /*
 668                          * btrfs_split_item returns -EAGAIN when the
 669                          * item changed size or key
 670                          */
 671                         ret = btrfs_split_item(trans, root, path, &key, offset);
 672                         if (ret && ret != -EAGAIN) {
 673                                 btrfs_abort_transaction(trans, root, ret);
 674                                 goto out;
 675                         }
 676
 677                         key.offset = end_byte - 1;
 678                 } else {
 679                         truncate_one_csum(root, path, &key, bytenr, len);
 680                         if (key.offset < bytenr)
 681                                 break;
 682                 }
 683                 btrfs_release_path(path);
 684         }
 685         ret = 0;
 686 out:
 687         btrfs_free_path(path);
 688         return ret;
 689 }
 690
 691 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 692                            struct btrfs_root *root,
 693                            struct btrfs_ordered_sum *sums)
 694 {
 695         struct btrfs_key file_key;
 696         struct btrfs_key found_key;
 697         struct btrfs_path *path;
 698         struct btrfs_csum_item *item;
 699         struct btrfs_csum_item *item_end;
 700         struct extent_buffer *leaf = NULL;
 701         u64 next_offset;
 702         u64 total_bytes = 0;
 703         u64 csum_offset;
 704         u64 bytenr;
 705         u32 nritems;
 706         u32 ins_size;
 707         int index = 0;
 708         int found_next;
 709         int ret;
 710         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 711
 712         path = btrfs_alloc_path();
 713         if (!path)
 714                 return -ENOMEM;
 715 again:
 716         next_offset = (u64)-1;
 717         found_next = 0;
 718         bytenr = sums->bytenr + total_bytes;
 719         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 720         file_key.offset = bytenr;
 721         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
 722
 723         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 724         if (!IS_ERR(item)) {
 725                 ret = 0;
 726                 leaf = path->nodes[0];
 727                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 728                                           struct btrfs_csum_item);
 729                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 730                            btrfs_item_size_nr(leaf, path->slots[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 = sums->len - total_bytes;
 811                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 812                 WARN_ON(tmp < 1);
 813
 814                 extend_nr = max_t(int, 1, (int)tmp);
 815                 diff = (csum_offset + extend_nr) * csum_size;
 816                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 817
 818                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 819                 diff = min(free_space, diff);
 820                 diff /= csum_size;
 821                 diff *= csum_size;
 822
 823                 btrfs_extend_item(root, path, diff);
 824                 ret = 0;
 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 = sums->len - total_bytes;
 835                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 836                 tmp = min(tmp, (next_offset - file_key.offset) >>
 837                                          root->fs_info->sb->s_blocksize_bits);
 838
 839                 tmp = max((u64)1, tmp);
 840                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 841                 ins_size = csum_size * tmp;
 842         } else {
 843                 ins_size = csum_size;
 844         }
 845         path->leave_spinning = 1;
 846         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 847                                       ins_size);
 848         path->leave_spinning = 0;
 849         if (ret < 0)
 850                 goto fail_unlock;
 851         if (ret != 0) {
 852                 WARN_ON(1);
 853                 goto fail_unlock;
 854         }
 855         leaf = path->nodes[0];
 856 csum:
 857         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 858         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 859                                       btrfs_item_size_nr(leaf, path->slots[0]));
 860         item = (struct btrfs_csum_item *)((unsigned char *)item +
 861                                           csum_offset * csum_size);
 862 found:
 863         ins_size = (u32)(sums->len - total_bytes) >>
 864                    root->fs_info->sb->s_blocksize_bits;
 865         ins_size *= csum_size;
 866         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 867                               ins_size);
 868         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 869                             ins_size);
 870
 871         ins_size /= csum_size;
 872         total_bytes += ins_size * root->sectorsize;
 873         index += ins_size;
 874
 875         btrfs_mark_buffer_dirty(path->nodes[0]);
 876         if (total_bytes < sums->len) {
 877                 btrfs_release_path(path);
 878                 cond_resched();
 879                 goto again;
 880         }
 881 out:
 882         btrfs_free_path(path);
 883         return ret;
 884
 885 fail_unlock:
 886         goto out;
 887 }