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 #include "compression.h"
  29
  30 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  31                                    sizeof(struct btrfs_item) * 2) / \
  32                                   size) - 1))
  33
  34 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  35                                        PAGE_SIZE))
  36
  37 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
  38                                    sizeof(struct btrfs_ordered_sum)) / \
  39                                    sizeof(u32) * (r)->sectorsize)
  40
  41 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  42                              struct btrfs_root *root,
  43                              u64 objectid, u64 pos,
  44                              u64 disk_offset, u64 disk_num_bytes,
  45                              u64 num_bytes, u64 offset, u64 ram_bytes,
  46                              u8 compression, u8 encryption, u16 other_encoding)
  47 {
  48         int ret = 0;
  49         struct btrfs_file_extent_item *item;
  50         struct btrfs_key file_key;
  51         struct btrfs_path *path;
  52         struct extent_buffer *leaf;
  53
  54         path = btrfs_alloc_path();
  55         if (!path)
  56                 return -ENOMEM;
  57         file_key.objectid = objectid;
  58         file_key.offset = pos;
  59         file_key.type = BTRFS_EXTENT_DATA_KEY;
  60
  61         path->leave_spinning = 1;
  62         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  63                                       sizeof(*item));
  64         if (ret < 0)
  65                 goto out;
  66         BUG_ON(ret); /* Can't happen */
  67         leaf = path->nodes[0];
  68         item = btrfs_item_ptr(leaf, path->slots[0],
  69                               struct btrfs_file_extent_item);
  70         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  71         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  72         btrfs_set_file_extent_offset(leaf, item, offset);
  73         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  74         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  75         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  76         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  77         btrfs_set_file_extent_compression(leaf, item, compression);
  78         btrfs_set_file_extent_encryption(leaf, item, encryption);
  79         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  80
  81         btrfs_mark_buffer_dirty(leaf);
  82 out:
  83         btrfs_free_path(path);
  84         return ret;
  85 }
  86
  87 static struct btrfs_csum_item *
  88 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  89                   struct btrfs_root *root,
  90                   struct btrfs_path *path,
  91                   u64 bytenr, int cow)
  92 {
  93         int ret;
  94         struct btrfs_key file_key;
  95         struct btrfs_key found_key;
  96         struct btrfs_csum_item *item;
  97         struct extent_buffer *leaf;
  98         u64 csum_offset = 0;
  99         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 100         int csums_in_item;
 101
 102         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 103         file_key.offset = bytenr;
 104         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 105         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 106         if (ret < 0)
 107                 goto fail;
 108         leaf = path->nodes[0];
 109         if (ret > 0) {
 110                 ret = 1;
 111                 if (path->slots[0] == 0)
 112                         goto fail;
 113                 path->slots[0]--;
 114                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 115                 if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 116                         goto fail;
 117
 118                 csum_offset = (bytenr - found_key.offset) >>
 119                                 root->fs_info->sb->s_blocksize_bits;
 120                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 121                 csums_in_item /= csum_size;
 122
 123                 if (csum_offset == csums_in_item) {
 124                         ret = -EFBIG;
 125                         goto fail;
 126                 } else if (csum_offset > csums_in_item) {
 127                         goto fail;
 128                 }
 129         }
 130         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 131         item = (struct btrfs_csum_item *)((unsigned char *)item +
 132                                           csum_offset * csum_size);
 133         return item;
 134 fail:
 135         if (ret > 0)
 136                 ret = -ENOENT;
 137         return ERR_PTR(ret);
 138 }
 139
 140 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 141                              struct btrfs_root *root,
 142                              struct btrfs_path *path, u64 objectid,
 143                              u64 offset, int mod)
 144 {
 145         int ret;
 146         struct btrfs_key file_key;
 147         int ins_len = mod < 0 ? -1 : 0;
 148         int cow = mod != 0;
 149
 150         file_key.objectid = objectid;
 151         file_key.offset = offset;
 152         file_key.type = BTRFS_EXTENT_DATA_KEY;
 153         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 154         return ret;
 155 }
 156
 157 static void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)
 158 {
 159         kfree(bio->csum_allocated);
 160 }
 161
 162 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 163                                    struct inode *inode, struct bio *bio,
 164                                    u64 logical_offset, u32 *dst, int dio)
 165 {
 166         struct bio_vec *bvec;
 167         struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
 168         struct btrfs_csum_item *item = NULL;
 169         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 170         struct btrfs_path *path;
 171         u8 *csum;
 172         u64 offset = 0;
 173         u64 item_start_offset = 0;
 174         u64 item_last_offset = 0;
 175         u64 disk_bytenr;
 176         u64 page_bytes_left;
 177         u32 diff;
 178         int nblocks;
 179         int count = 0, i;
 180         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 181
 182         path = btrfs_alloc_path();
 183         if (!path)
 184                 return -ENOMEM;
 185
 186         nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
 187         if (!dst) {
 188                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 189                         btrfs_bio->csum_allocated = kmalloc_array(nblocks,
 190                                         csum_size, GFP_NOFS);
 191                         if (!btrfs_bio->csum_allocated) {
 192                                 btrfs_free_path(path);
 193                                 return -ENOMEM;
 194                         }
 195                         btrfs_bio->csum = btrfs_bio->csum_allocated;
 196                         btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
 197                 } else {
 198                         btrfs_bio->csum = btrfs_bio->csum_inline;
 199                 }
 200                 csum = btrfs_bio->csum;
 201         } else {
 202                 csum = (u8 *)dst;
 203         }
 204
 205         if (bio->bi_iter.bi_size > PAGE_SIZE * 8)
 206                 path->reada = READA_FORWARD;
 207
 208         WARN_ON(bio->bi_vcnt <= 0);
 209
 210         /*
 211          * the free space stuff is only read when it hasn't been
 212          * updated in the current transaction.  So, we can safely
 213          * read from the commit root and sidestep a nasty deadlock
 214          * between reading the free space cache and updating the csum tree.
 215          */
 216         if (btrfs_is_free_space_inode(inode)) {
 217                 path->search_commit_root = 1;
 218                 path->skip_locking = 1;
 219         }
 220
 221         disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
 222         if (dio)
 223                 offset = logical_offset;
 224
 225         bio_for_each_segment_all(bvec, bio, i) {
 226                 page_bytes_left = bvec->bv_len;
 227                 if (count)
 228                         goto next;
 229
 230                 if (!dio)
 231                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 232                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 233                                                (u32 *)csum, nblocks);
 234                 if (count)
 235                         goto found;
 236
 237                 if (!item || disk_bytenr < item_start_offset ||
 238                     disk_bytenr >= item_last_offset) {
 239                         struct btrfs_key found_key;
 240                         u32 item_size;
 241
 242                         if (item)
 243                                 btrfs_release_path(path);
 244                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 245                                                  path, disk_bytenr, 0);
 246                         if (IS_ERR(item)) {
 247                                 count = 1;
 248                                 memset(csum, 0, csum_size);
 249                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 250                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 251                                         set_extent_bits(io_tree, offset,
 252                                                 offset + root->sectorsize - 1,
 253                                                 EXTENT_NODATASUM);
 254                                 } else {
 255                                         btrfs_info_rl(BTRFS_I(inode)->root->fs_info,
 256                                                    "no csum found for inode %llu start %llu",
 257                                                btrfs_ino(inode), offset);
 258                                 }
 259                                 item = NULL;
 260                                 btrfs_release_path(path);
 261                                 goto found;
 262                         }
 263                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 264                                               path->slots[0]);
 265
 266                         item_start_offset = found_key.offset;
 267                         item_size = btrfs_item_size_nr(path->nodes[0],
 268                                                        path->slots[0]);
 269                         item_last_offset = item_start_offset +
 270                                 (item_size / csum_size) *
 271                                 root->sectorsize;
 272                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 273                                               struct btrfs_csum_item);
 274                 }
 275                 /*
 276                  * this byte range must be able to fit inside
 277                  * a single leaf so it will also fit inside a u32
 278                  */
 279                 diff = disk_bytenr - item_start_offset;
 280                 diff = diff / root->sectorsize;
 281                 diff = diff * csum_size;
 282                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 283                                             inode->i_sb->s_blocksize_bits);
 284                 read_extent_buffer(path->nodes[0], csum,
 285                                    ((unsigned long)item) + diff,
 286                                    csum_size * count);
 287 found:
 288                 csum += count * csum_size;
 289                 nblocks -= count;
 290 next:
 291                 while (count--) {
 292                         disk_bytenr += root->sectorsize;
 293                         offset += root->sectorsize;
 294                         page_bytes_left -= root->sectorsize;
 295                         if (!page_bytes_left)
 296                                 break; /* move to next bio */
 297                 }
 298         }
 299
 300         WARN_ON_ONCE(count);
 301         btrfs_free_path(path);
 302         return 0;
 303 }
 304
 305 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 306                           struct bio *bio, u32 *dst)
 307 {
 308         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 309 }
 310
 311 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 312                               struct bio *bio, u64 offset)
 313 {
 314         return __btrfs_lookup_bio_sums(root, inode, bio, offset, NULL, 1);
 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         ASSERT(IS_ALIGNED(start, root->sectorsize) &&
 333                IS_ALIGNED(end + 1, root->sectorsize));
 334
 335         path = btrfs_alloc_path();
 336         if (!path)
 337                 return -ENOMEM;
 338
 339         if (search_commit) {
 340                 path->skip_locking = 1;
 341                 path->reada = READA_FORWARD;
 342                 path->search_commit_root = 1;
 343         }
 344
 345         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 346         key.offset = start;
 347         key.type = BTRFS_EXTENT_CSUM_KEY;
 348
 349         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 350         if (ret < 0)
 351                 goto fail;
 352         if (ret > 0 && path->slots[0] > 0) {
 353                 leaf = path->nodes[0];
 354                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 355                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 356                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 357                         offset = (start - key.offset) >>
 358                                  root->fs_info->sb->s_blocksize_bits;
 359                         if (offset * csum_size <
 360                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 361                                 path->slots[0]--;
 362                 }
 363         }
 364
 365         while (start <= end) {
 366                 leaf = path->nodes[0];
 367                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 368                         ret = btrfs_next_leaf(root, path);
 369                         if (ret < 0)
 370                                 goto fail;
 371                         if (ret > 0)
 372                                 break;
 373                         leaf = path->nodes[0];
 374                 }
 375
 376                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 377                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 378                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 379                     key.offset > end)
 380                         break;
 381
 382                 if (key.offset > start)
 383                         start = key.offset;
 384
 385                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 386                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 387                 if (csum_end <= start) {
 388                         path->slots[0]++;
 389                         continue;
 390                 }
 391
 392                 csum_end = min(csum_end, end + 1);
 393                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 394                                       struct btrfs_csum_item);
 395                 while (start < csum_end) {
 396                         size = min_t(size_t, csum_end - start,
 397                                      MAX_ORDERED_SUM_BYTES(root));
 398                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 399                                        GFP_NOFS);
 400                         if (!sums) {
 401                                 ret = -ENOMEM;
 402                                 goto fail;
 403                         }
 404
 405                         sums->bytenr = start;
 406                         sums->len = (int)size;
 407
 408                         offset = (start - key.offset) >>
 409                                 root->fs_info->sb->s_blocksize_bits;
 410                         offset *= csum_size;
 411                         size >>= root->fs_info->sb->s_blocksize_bits;
 412
 413                         read_extent_buffer(path->nodes[0],
 414                                            sums->sums,
 415                                            ((unsigned long)item) + offset,
 416                                            csum_size * size);
 417
 418                         start += root->sectorsize * size;
 419                         list_add_tail(&sums->list, &tmplist);
 420                 }
 421                 path->slots[0]++;
 422         }
 423         ret = 0;
 424 fail:
 425         while (ret < 0 && !list_empty(&tmplist)) {
 426                 sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 427                 list_del(&sums->list);
 428                 kfree(sums);
 429         }
 430         list_splice_tail(&tmplist, list);
 431
 432         btrfs_free_path(path);
 433         return ret;
 434 }
 435
 436 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 437                        struct bio *bio, u64 file_start, int contig)
 438 {
 439         struct btrfs_ordered_sum *sums;
 440         struct btrfs_ordered_extent *ordered = NULL;
 441         char *data;
 442         struct bio_vec *bvec;
 443         int index;
 444         int nr_sectors;
 445         int i, j;
 446         unsigned long total_bytes = 0;
 447         unsigned long this_sum_bytes = 0;
 448         u64 offset;
 449
 450         WARN_ON(bio->bi_vcnt <= 0);
 451         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_iter.bi_size),
 452                        GFP_NOFS);
 453         if (!sums)
 454                 return -ENOMEM;
 455
 456         sums->len = bio->bi_iter.bi_size;
 457         INIT_LIST_HEAD(&sums->list);
 458
 459         if (contig)
 460                 offset = file_start;
 461         else
 462                 offset = 0; /* shut up gcc */
 463
 464         sums->bytenr = (u64)bio->bi_iter.bi_sector << 9;
 465         index = 0;
 466
 467         bio_for_each_segment_all(bvec, bio, j) {
 468                 if (!contig)
 469                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 470
 471                 if (!ordered) {
 472                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 473                         BUG_ON(!ordered); /* Logic error */
 474                 }
 475
 476                 data = kmap_atomic(bvec->bv_page);
 477
 478                 nr_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
 479                                                 bvec->bv_len + root->sectorsize
 480                                                 - 1);
 481
 482                 for (i = 0; i < nr_sectors; i++) {
 483                         if (offset >= ordered->file_offset + ordered->len ||
 484                                 offset < ordered->file_offset) {
 485                                 unsigned long bytes_left;
 486
 487                                 kunmap_atomic(data);
 488                                 sums->len = this_sum_bytes;
 489                                 this_sum_bytes = 0;
 490                                 btrfs_add_ordered_sum(inode, ordered, sums);
 491                                 btrfs_put_ordered_extent(ordered);
 492
 493                                 bytes_left = bio->bi_iter.bi_size - total_bytes;
 494
 495                                 sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 496                                         GFP_NOFS);
 497                                 BUG_ON(!sums); /* -ENOMEM */
 498                                 sums->len = bytes_left;
 499                                 ordered = btrfs_lookup_ordered_extent(inode,
 500                                                                 offset);
 501                                 ASSERT(ordered); /* Logic error */
 502                                 sums->bytenr = ((u64)bio->bi_iter.bi_sector << 9)
 503                                         + total_bytes;
 504                                 index = 0;
 505
 506                                 data = kmap_atomic(bvec->bv_page);
 507                         }
 508
 509                         sums->sums[index] = ~(u32)0;
 510                         sums->sums[index]
 511                                 = btrfs_csum_data(data + bvec->bv_offset
 512                                                 + (i * root->sectorsize),
 513                                                 sums->sums[index],
 514                                                 root->sectorsize);
 515                         btrfs_csum_final(sums->sums[index],
 516                                         (char *)(sums->sums + index));
 517                         index++;
 518                         offset += root->sectorsize;
 519                         this_sum_bytes += root->sectorsize;
 520                         total_bytes += root->sectorsize;
 521                 }
 522
 523                 kunmap_atomic(data);
 524         }
 525         this_sum_bytes = 0;
 526         btrfs_add_ordered_sum(inode, ordered, sums);
 527         btrfs_put_ordered_extent(ordered);
 528         return 0;
 529 }
 530
 531 /*
 532  * helper function for csum removal, this expects the
 533  * key to describe the csum pointed to by the path, and it expects
 534  * the csum to overlap the range [bytenr, len]
 535  *
 536  * The csum should not be entirely contained in the range and the
 537  * range should not be entirely contained in the csum.
 538  *
 539  * This calls btrfs_truncate_item with the correct args based on the
 540  * overlap, and fixes up the key as required.
 541  */
 542 static noinline void truncate_one_csum(struct btrfs_root *root,
 543                                        struct btrfs_path *path,
 544                                        struct btrfs_key *key,
 545                                        u64 bytenr, u64 len)
 546 {
 547         struct extent_buffer *leaf;
 548         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 549         u64 csum_end;
 550         u64 end_byte = bytenr + len;
 551         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 552
 553         leaf = path->nodes[0];
 554         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 555         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 556         csum_end += key->offset;
 557
 558         if (key->offset < bytenr && csum_end <= end_byte) {
 559                 /*
 560                  *         [ bytenr - len ]
 561                  *         [   ]
 562                  *   [csum     ]
 563                  *   A simple truncate off the end of the item
 564                  */
 565                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 566                 new_size *= csum_size;
 567                 btrfs_truncate_item(root, path, new_size, 1);
 568         } else if (key->offset >= bytenr && csum_end > end_byte &&
 569                    end_byte > key->offset) {
 570                 /*
 571                  *         [ bytenr - len ]
 572                  *                 [ ]
 573                  *                 [csum     ]
 574                  * we need to truncate from the beginning of the csum
 575                  */
 576                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 577                 new_size *= csum_size;
 578
 579                 btrfs_truncate_item(root, path, new_size, 0);
 580
 581                 key->offset = end_byte;
 582                 btrfs_set_item_key_safe(root->fs_info, path, key);
 583         } else {
 584                 BUG();
 585         }
 586 }
 587
 588 /*
 589  * deletes the csum items from the csum tree for a given
 590  * range of bytes.
 591  */
 592 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 593                     struct btrfs_root *root, u64 bytenr, u64 len)
 594 {
 595         struct btrfs_path *path;
 596         struct btrfs_key key;
 597         u64 end_byte = bytenr + len;
 598         u64 csum_end;
 599         struct extent_buffer *leaf;
 600         int ret;
 601         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 602         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 603
 604         root = root->fs_info->csum_root;
 605
 606         path = btrfs_alloc_path();
 607         if (!path)
 608                 return -ENOMEM;
 609
 610         while (1) {
 611                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 612                 key.offset = end_byte - 1;
 613                 key.type = BTRFS_EXTENT_CSUM_KEY;
 614
 615                 path->leave_spinning = 1;
 616                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 617                 if (ret > 0) {
 618                         if (path->slots[0] == 0)
 619                                 break;
 620                         path->slots[0]--;
 621                 } else if (ret < 0) {
 622                         break;
 623                 }
 624
 625                 leaf = path->nodes[0];
 626                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 627
 628                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 629                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 630                         break;
 631                 }
 632
 633                 if (key.offset >= end_byte)
 634                         break;
 635
 636                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 637                 csum_end <<= blocksize_bits;
 638                 csum_end += key.offset;
 639
 640                 /* this csum ends before we start, we're done */
 641                 if (csum_end <= bytenr)
 642                         break;
 643
 644                 /* delete the entire item, it is inside our range */
 645                 if (key.offset >= bytenr && csum_end <= end_byte) {
 646                         ret = btrfs_del_item(trans, root, path);
 647                         if (ret)
 648                                 goto out;
 649                         if (key.offset == bytenr)
 650                                 break;
 651                 } else if (key.offset < bytenr && csum_end > end_byte) {
 652                         unsigned long offset;
 653                         unsigned long shift_len;
 654                         unsigned long item_offset;
 655                         /*
 656                          *        [ bytenr - len ]
 657                          *     [csum                ]
 658                          *
 659                          * Our bytes are in the middle of the csum,
 660                          * we need to split this item and insert a new one.
 661                          *
 662                          * But we can't drop the path because the
 663                          * csum could change, get removed, extended etc.
 664                          *
 665                          * The trick here is the max size of a csum item leaves
 666                          * enough room in the tree block for a single
 667                          * item header.  So, we split the item in place,
 668                          * adding a new header pointing to the existing
 669                          * bytes.  Then we loop around again and we have
 670                          * a nicely formed csum item that we can neatly
 671                          * truncate.
 672                          */
 673                         offset = (bytenr - key.offset) >> blocksize_bits;
 674                         offset *= csum_size;
 675
 676                         shift_len = (len >> blocksize_bits) * csum_size;
 677
 678                         item_offset = btrfs_item_ptr_offset(leaf,
 679                                                             path->slots[0]);
 680
 681                         memzero_extent_buffer(leaf, item_offset + offset,
 682                                              shift_len);
 683                         key.offset = bytenr;
 684
 685                         /*
 686                          * btrfs_split_item returns -EAGAIN when the
 687                          * item changed size or key
 688                          */
 689                         ret = btrfs_split_item(trans, root, path, &key, offset);
 690                         if (ret && ret != -EAGAIN) {
 691                                 btrfs_abort_transaction(trans, ret);
 692                                 goto out;
 693                         }
 694
 695                         key.offset = end_byte - 1;
 696                 } else {
 697                         truncate_one_csum(root, path, &key, bytenr, len);
 698                         if (key.offset < bytenr)
 699                                 break;
 700                 }
 701                 btrfs_release_path(path);
 702         }
 703         ret = 0;
 704 out:
 705         btrfs_free_path(path);
 706         return ret;
 707 }
 708
 709 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 710                            struct btrfs_root *root,
 711                            struct btrfs_ordered_sum *sums)
 712 {
 713         struct btrfs_key file_key;
 714         struct btrfs_key found_key;
 715         struct btrfs_path *path;
 716         struct btrfs_csum_item *item;
 717         struct btrfs_csum_item *item_end;
 718         struct extent_buffer *leaf = NULL;
 719         u64 next_offset;
 720         u64 total_bytes = 0;
 721         u64 csum_offset;
 722         u64 bytenr;
 723         u32 nritems;
 724         u32 ins_size;
 725         int index = 0;
 726         int found_next;
 727         int ret;
 728         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 729
 730         path = btrfs_alloc_path();
 731         if (!path)
 732                 return -ENOMEM;
 733 again:
 734         next_offset = (u64)-1;
 735         found_next = 0;
 736         bytenr = sums->bytenr + total_bytes;
 737         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 738         file_key.offset = bytenr;
 739         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 740
 741         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 742         if (!IS_ERR(item)) {
 743                 ret = 0;
 744                 leaf = path->nodes[0];
 745                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 746                                           struct btrfs_csum_item);
 747                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 748                            btrfs_item_size_nr(leaf, path->slots[0]));
 749                 goto found;
 750         }
 751         ret = PTR_ERR(item);
 752         if (ret != -EFBIG && ret != -ENOENT)
 753                 goto fail_unlock;
 754
 755         if (ret == -EFBIG) {
 756                 u32 item_size;
 757                 /* we found one, but it isn't big enough yet */
 758                 leaf = path->nodes[0];
 759                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 760                 if ((item_size / csum_size) >=
 761                     MAX_CSUM_ITEMS(root, csum_size)) {
 762                         /* already at max size, make a new one */
 763                         goto insert;
 764                 }
 765         } else {
 766                 int slot = path->slots[0] + 1;
 767                 /* we didn't find a csum item, insert one */
 768                 nritems = btrfs_header_nritems(path->nodes[0]);
 769                 if (!nritems || (path->slots[0] >= nritems - 1)) {
 770                         ret = btrfs_next_leaf(root, path);
 771                         if (ret == 1)
 772                                 found_next = 1;
 773                         if (ret != 0)
 774                                 goto insert;
 775                         slot = path->slots[0];
 776                 }
 777                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 778                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 779                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 780                         found_next = 1;
 781                         goto insert;
 782                 }
 783                 next_offset = found_key.offset;
 784                 found_next = 1;
 785                 goto insert;
 786         }
 787
 788         /*
 789          * at this point, we know the tree has an item, but it isn't big
 790          * enough yet to put our csum in.  Grow it
 791          */
 792         btrfs_release_path(path);
 793         ret = btrfs_search_slot(trans, root, &file_key, path,
 794                                 csum_size, 1);
 795         if (ret < 0)
 796                 goto fail_unlock;
 797
 798         if (ret > 0) {
 799                 if (path->slots[0] == 0)
 800                         goto insert;
 801                 path->slots[0]--;
 802         }
 803
 804         leaf = path->nodes[0];
 805         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 806         csum_offset = (bytenr - found_key.offset) >>
 807                         root->fs_info->sb->s_blocksize_bits;
 808
 809         if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
 810             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 811             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 812                 goto insert;
 813         }
 814
 815         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 816             csum_size) {
 817                 int extend_nr;
 818                 u64 tmp;
 819                 u32 diff;
 820                 u32 free_space;
 821
 822                 if (btrfs_leaf_free_space(root, leaf) <
 823                                  sizeof(struct btrfs_item) + csum_size * 2)
 824                         goto insert;
 825
 826                 free_space = btrfs_leaf_free_space(root, leaf) -
 827                                          sizeof(struct btrfs_item) - csum_size;
 828                 tmp = sums->len - total_bytes;
 829                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 830                 WARN_ON(tmp < 1);
 831
 832                 extend_nr = max_t(int, 1, (int)tmp);
 833                 diff = (csum_offset + extend_nr) * csum_size;
 834                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 835
 836                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 837                 diff = min(free_space, diff);
 838                 diff /= csum_size;
 839                 diff *= csum_size;
 840
 841                 btrfs_extend_item(root, path, diff);
 842                 ret = 0;
 843                 goto csum;
 844         }
 845
 846 insert:
 847         btrfs_release_path(path);
 848         csum_offset = 0;
 849         if (found_next) {
 850                 u64 tmp;
 851
 852                 tmp = sums->len - total_bytes;
 853                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 854                 tmp = min(tmp, (next_offset - file_key.offset) >>
 855                                          root->fs_info->sb->s_blocksize_bits);
 856
 857                 tmp = max((u64)1, tmp);
 858                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 859                 ins_size = csum_size * tmp;
 860         } else {
 861                 ins_size = csum_size;
 862         }
 863         path->leave_spinning = 1;
 864         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 865                                       ins_size);
 866         path->leave_spinning = 0;
 867         if (ret < 0)
 868                 goto fail_unlock;
 869         if (WARN_ON(ret != 0))
 870                 goto fail_unlock;
 871         leaf = path->nodes[0];
 872 csum:
 873         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 874         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 875                                       btrfs_item_size_nr(leaf, path->slots[0]));
 876         item = (struct btrfs_csum_item *)((unsigned char *)item +
 877                                           csum_offset * csum_size);
 878 found:
 879         ins_size = (u32)(sums->len - total_bytes) >>
 880                    root->fs_info->sb->s_blocksize_bits;
 881         ins_size *= csum_size;
 882         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 883                               ins_size);
 884         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 885                             ins_size);
 886
 887         ins_size /= csum_size;
 888         total_bytes += ins_size * root->sectorsize;
 889         index += ins_size;
 890
 891         btrfs_mark_buffer_dirty(path->nodes[0]);
 892         if (total_bytes < sums->len) {
 893                 btrfs_release_path(path);
 894                 cond_resched();
 895                 goto again;
 896         }
 897 out:
 898         btrfs_free_path(path);
 899         return ret;
 900
 901 fail_unlock:
 902         goto out;
 903 }
 904
 905 void btrfs_extent_item_to_extent_map(struct inode *inode,
 906                                      const struct btrfs_path *path,
 907                                      struct btrfs_file_extent_item *fi,
 908                                      const bool new_inline,
 909                                      struct extent_map *em)
 910 {
 911         struct btrfs_root *root = BTRFS_I(inode)->root;
 912         struct extent_buffer *leaf = path->nodes[0];
 913         const int slot = path->slots[0];
 914         struct btrfs_key key;
 915         u64 extent_start, extent_end;
 916         u64 bytenr;
 917         u8 type = btrfs_file_extent_type(leaf, fi);
 918         int compress_type = btrfs_file_extent_compression(leaf, fi);
 919
 920         em->bdev = root->fs_info->fs_devices->latest_bdev;
 921         btrfs_item_key_to_cpu(leaf, &key, slot);
 922         extent_start = key.offset;
 923
 924         if (type == BTRFS_FILE_EXTENT_REG ||
 925             type == BTRFS_FILE_EXTENT_PREALLOC) {
 926                 extent_end = extent_start +
 927                         btrfs_file_extent_num_bytes(leaf, fi);
 928         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 929                 size_t size;
 930                 size = btrfs_file_extent_inline_len(leaf, slot, fi);
 931                 extent_end = ALIGN(extent_start + size, root->sectorsize);
 932         }
 933
 934         em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
 935         if (type == BTRFS_FILE_EXTENT_REG ||
 936             type == BTRFS_FILE_EXTENT_PREALLOC) {
 937                 em->start = extent_start;
 938                 em->len = extent_end - extent_start;
 939                 em->orig_start = extent_start -
 940                         btrfs_file_extent_offset(leaf, fi);
 941                 em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
 942                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 943                 if (bytenr == 0) {
 944                         em->block_start = EXTENT_MAP_HOLE;
 945                         return;
 946                 }
 947                 if (compress_type != BTRFS_COMPRESS_NONE) {
 948                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 949                         em->compress_type = compress_type;
 950                         em->block_start = bytenr;
 951                         em->block_len = em->orig_block_len;
 952                 } else {
 953                         bytenr += btrfs_file_extent_offset(leaf, fi);
 954                         em->block_start = bytenr;
 955                         em->block_len = em->len;
 956                         if (type == BTRFS_FILE_EXTENT_PREALLOC)
 957                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
 958                 }
 959         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 960                 em->block_start = EXTENT_MAP_INLINE;
 961                 em->start = extent_start;
 962                 em->len = extent_end - extent_start;
 963                 /*
 964                  * Initialize orig_start and block_len with the same values
 965                  * as in inode.c:btrfs_get_extent().
 966                  */
 967                 em->orig_start = EXTENT_MAP_HOLE;
 968                 em->block_len = (u64)-1;
 969                 if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
 970                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 971                         em->compress_type = compress_type;
 972                 }
 973         } else {
 974                 btrfs_err(root->fs_info,
 975                           "unknown file extent item type %d, inode %llu, offset %llu, root %llu",
 976                           type, btrfs_ino(inode), extent_start,
 977                           root->root_key.objectid);
 978         }
 979 }