fs/btrfs/file-item.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/bio.h>
   7 #include <linux/slab.h>
   8 #include <linux/pagemap.h>
   9 #include <linux/highmem.h>
  10 #include <linux/sched/mm.h>
  11 #include "ctree.h"
  12 #include "disk-io.h"
  13 #include "transaction.h"
  14 #include "volumes.h"
  15 #include "print-tree.h"
  16 #include "compression.h"
  17
  18 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  19                                    sizeof(struct btrfs_item) * 2) / \
  20                                   size) - 1))
  21
  22 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  23                                        PAGE_SIZE))
  24
  25 static inline u32 max_ordered_sum_bytes(struct btrfs_fs_info *fs_info,
  26                                         u16 csum_size)
  27 {
  28         u32 ncsums = (PAGE_SIZE - sizeof(struct btrfs_ordered_sum)) / csum_size;
  29
  30         return ncsums * fs_info->sectorsize;
  31 }
  32
  33 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  34                              struct btrfs_root *root,
  35                              u64 objectid, u64 pos,
  36                              u64 disk_offset, u64 disk_num_bytes,
  37                              u64 num_bytes, u64 offset, u64 ram_bytes,
  38                              u8 compression, u8 encryption, u16 other_encoding)
  39 {
  40         int ret = 0;
  41         struct btrfs_file_extent_item *item;
  42         struct btrfs_key file_key;
  43         struct btrfs_path *path;
  44         struct extent_buffer *leaf;
  45
  46         path = btrfs_alloc_path();
  47         if (!path)
  48                 return -ENOMEM;
  49         file_key.objectid = objectid;
  50         file_key.offset = pos;
  51         file_key.type = BTRFS_EXTENT_DATA_KEY;
  52
  53         path->leave_spinning = 1;
  54         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  55                                       sizeof(*item));
  56         if (ret < 0)
  57                 goto out;
  58         BUG_ON(ret); /* Can't happen */
  59         leaf = path->nodes[0];
  60         item = btrfs_item_ptr(leaf, path->slots[0],
  61                               struct btrfs_file_extent_item);
  62         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  63         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  64         btrfs_set_file_extent_offset(leaf, item, offset);
  65         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  66         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  67         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  68         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  69         btrfs_set_file_extent_compression(leaf, item, compression);
  70         btrfs_set_file_extent_encryption(leaf, item, encryption);
  71         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  72
  73         btrfs_mark_buffer_dirty(leaf);
  74 out:
  75         btrfs_free_path(path);
  76         return ret;
  77 }
  78
  79 static struct btrfs_csum_item *
  80 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  81                   struct btrfs_root *root,
  82                   struct btrfs_path *path,
  83                   u64 bytenr, int cow)
  84 {
  85         struct btrfs_fs_info *fs_info = root->fs_info;
  86         int ret;
  87         struct btrfs_key file_key;
  88         struct btrfs_key found_key;
  89         struct btrfs_csum_item *item;
  90         struct extent_buffer *leaf;
  91         u64 csum_offset = 0;
  92         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
  93         int csums_in_item;
  94
  95         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
  96         file_key.offset = bytenr;
  97         file_key.type = BTRFS_EXTENT_CSUM_KEY;
  98         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
  99         if (ret < 0)
 100                 goto fail;
 101         leaf = path->nodes[0];
 102         if (ret > 0) {
 103                 ret = 1;
 104                 if (path->slots[0] == 0)
 105                         goto fail;
 106                 path->slots[0]--;
 107                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 108                 if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 109                         goto fail;
 110
 111                 csum_offset = (bytenr - found_key.offset) >>
 112                                 fs_info->sb->s_blocksize_bits;
 113                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 114                 csums_in_item /= csum_size;
 115
 116                 if (csum_offset == csums_in_item) {
 117                         ret = -EFBIG;
 118                         goto fail;
 119                 } else if (csum_offset > csums_in_item) {
 120                         goto fail;
 121                 }
 122         }
 123         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 124         item = (struct btrfs_csum_item *)((unsigned char *)item +
 125                                           csum_offset * csum_size);
 126         return item;
 127 fail:
 128         if (ret > 0)
 129                 ret = -ENOENT;
 130         return ERR_PTR(ret);
 131 }
 132
 133 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 134                              struct btrfs_root *root,
 135                              struct btrfs_path *path, u64 objectid,
 136                              u64 offset, int mod)
 137 {
 138         int ret;
 139         struct btrfs_key file_key;
 140         int ins_len = mod < 0 ? -1 : 0;
 141         int cow = mod != 0;
 142
 143         file_key.objectid = objectid;
 144         file_key.offset = offset;
 145         file_key.type = BTRFS_EXTENT_DATA_KEY;
 146         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 147         return ret;
 148 }
 149
 150 static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
 151                                    u64 logical_offset, u8 *dst, int dio)
 152 {
 153         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 154         struct bio_vec bvec;
 155         struct bvec_iter iter;
 156         struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
 157         struct btrfs_csum_item *item = NULL;
 158         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 159         struct btrfs_path *path;
 160         u8 *csum;
 161         u64 offset = 0;
 162         u64 item_start_offset = 0;
 163         u64 item_last_offset = 0;
 164         u64 disk_bytenr;
 165         u64 page_bytes_left;
 166         u32 diff;
 167         int nblocks;
 168         int count = 0;
 169         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 170
 171         path = btrfs_alloc_path();
 172         if (!path)
 173                 return BLK_STS_RESOURCE;
 174
 175         nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
 176         if (!dst) {
 177                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 178                         btrfs_bio->csum = kmalloc_array(nblocks, csum_size,
 179                                                         GFP_NOFS);
 180                         if (!btrfs_bio->csum) {
 181                                 btrfs_free_path(path);
 182                                 return BLK_STS_RESOURCE;
 183                         }
 184                 } else {
 185                         btrfs_bio->csum = btrfs_bio->csum_inline;
 186                 }
 187                 csum = btrfs_bio->csum;
 188         } else {
 189                 csum = dst;
 190         }
 191
 192         if (bio->bi_iter.bi_size > PAGE_SIZE * 8)
 193                 path->reada = READA_FORWARD;
 194
 195         /*
 196          * the free space stuff is only read when it hasn't been
 197          * updated in the current transaction.  So, we can safely
 198          * read from the commit root and sidestep a nasty deadlock
 199          * between reading the free space cache and updating the csum tree.
 200          */
 201         if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
 202                 path->search_commit_root = 1;
 203                 path->skip_locking = 1;
 204         }
 205
 206         disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
 207         if (dio)
 208                 offset = logical_offset;
 209
 210         bio_for_each_segment(bvec, bio, iter) {
 211                 page_bytes_left = bvec.bv_len;
 212                 if (count)
 213                         goto next;
 214
 215                 if (!dio)
 216                         offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 217                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 218                                                csum, nblocks);
 219                 if (count)
 220                         goto found;
 221
 222                 if (!item || disk_bytenr < item_start_offset ||
 223                     disk_bytenr >= item_last_offset) {
 224                         struct btrfs_key found_key;
 225                         u32 item_size;
 226
 227                         if (item)
 228                                 btrfs_release_path(path);
 229                         item = btrfs_lookup_csum(NULL, fs_info->csum_root,
 230                                                  path, disk_bytenr, 0);
 231                         if (IS_ERR(item)) {
 232                                 count = 1;
 233                                 memset(csum, 0, csum_size);
 234                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 235                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 236                                         set_extent_bits(io_tree, offset,
 237                                                 offset + fs_info->sectorsize - 1,
 238                                                 EXTENT_NODATASUM);
 239                                 } else {
 240                                         btrfs_info_rl(fs_info,
 241                                                    "no csum found for inode %llu start %llu",
 242                                                btrfs_ino(BTRFS_I(inode)), offset);
 243                                 }
 244                                 item = NULL;
 245                                 btrfs_release_path(path);
 246                                 goto found;
 247                         }
 248                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 249                                               path->slots[0]);
 250
 251                         item_start_offset = found_key.offset;
 252                         item_size = btrfs_item_size_nr(path->nodes[0],
 253                                                        path->slots[0]);
 254                         item_last_offset = item_start_offset +
 255                                 (item_size / csum_size) *
 256                                 fs_info->sectorsize;
 257                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 258                                               struct btrfs_csum_item);
 259                 }
 260                 /*
 261                  * this byte range must be able to fit inside
 262                  * a single leaf so it will also fit inside a u32
 263                  */
 264                 diff = disk_bytenr - item_start_offset;
 265                 diff = diff / fs_info->sectorsize;
 266                 diff = diff * csum_size;
 267                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 268                                             inode->i_sb->s_blocksize_bits);
 269                 read_extent_buffer(path->nodes[0], csum,
 270                                    ((unsigned long)item) + diff,
 271                                    csum_size * count);
 272 found:
 273                 csum += count * csum_size;
 274                 nblocks -= count;
 275 next:
 276                 while (count--) {
 277                         disk_bytenr += fs_info->sectorsize;
 278                         offset += fs_info->sectorsize;
 279                         page_bytes_left -= fs_info->sectorsize;
 280                         if (!page_bytes_left)
 281                                 break; /* move to next bio */
 282                 }
 283         }
 284
 285         WARN_ON_ONCE(count);
 286         btrfs_free_path(path);
 287         return 0;
 288 }
 289
 290 blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
 291                                    u8 *dst)
 292 {
 293         return __btrfs_lookup_bio_sums(inode, bio, 0, dst, 0);
 294 }
 295
 296 blk_status_t btrfs_lookup_bio_sums_dio(struct inode *inode, struct bio *bio, u64 offset)
 297 {
 298         return __btrfs_lookup_bio_sums(inode, bio, offset, NULL, 1);
 299 }
 300
 301 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 302                              struct list_head *list, int search_commit)
 303 {
 304         struct btrfs_fs_info *fs_info = root->fs_info;
 305         struct btrfs_key key;
 306         struct btrfs_path *path;
 307         struct extent_buffer *leaf;
 308         struct btrfs_ordered_sum *sums;
 309         struct btrfs_csum_item *item;
 310         LIST_HEAD(tmplist);
 311         unsigned long offset;
 312         int ret;
 313         size_t size;
 314         u64 csum_end;
 315         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 316
 317         ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 318                IS_ALIGNED(end + 1, fs_info->sectorsize));
 319
 320         path = btrfs_alloc_path();
 321         if (!path)
 322                 return -ENOMEM;
 323
 324         if (search_commit) {
 325                 path->skip_locking = 1;
 326                 path->reada = READA_FORWARD;
 327                 path->search_commit_root = 1;
 328         }
 329
 330         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 331         key.offset = start;
 332         key.type = BTRFS_EXTENT_CSUM_KEY;
 333
 334         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 335         if (ret < 0)
 336                 goto fail;
 337         if (ret > 0 && path->slots[0] > 0) {
 338                 leaf = path->nodes[0];
 339                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 340                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 341                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 342                         offset = (start - key.offset) >>
 343                                  fs_info->sb->s_blocksize_bits;
 344                         if (offset * csum_size <
 345                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 346                                 path->slots[0]--;
 347                 }
 348         }
 349
 350         while (start <= end) {
 351                 leaf = path->nodes[0];
 352                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 353                         ret = btrfs_next_leaf(root, path);
 354                         if (ret < 0)
 355                                 goto fail;
 356                         if (ret > 0)
 357                                 break;
 358                         leaf = path->nodes[0];
 359                 }
 360
 361                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 362                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 363                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 364                     key.offset > end)
 365                         break;
 366
 367                 if (key.offset > start)
 368                         start = key.offset;
 369
 370                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 371                 csum_end = key.offset + (size / csum_size) * fs_info->sectorsize;
 372                 if (csum_end <= start) {
 373                         path->slots[0]++;
 374                         continue;
 375                 }
 376
 377                 csum_end = min(csum_end, end + 1);
 378                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 379                                       struct btrfs_csum_item);
 380                 while (start < csum_end) {
 381                         size = min_t(size_t, csum_end - start,
 382                                      max_ordered_sum_bytes(fs_info, csum_size));
 383                         sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
 384                                        GFP_NOFS);
 385                         if (!sums) {
 386                                 ret = -ENOMEM;
 387                                 goto fail;
 388                         }
 389
 390                         sums->bytenr = start;
 391                         sums->len = (int)size;
 392
 393                         offset = (start - key.offset) >>
 394                                 fs_info->sb->s_blocksize_bits;
 395                         offset *= csum_size;
 396                         size >>= fs_info->sb->s_blocksize_bits;
 397
 398                         read_extent_buffer(path->nodes[0],
 399                                            sums->sums,
 400                                            ((unsigned long)item) + offset,
 401                                            csum_size * size);
 402
 403                         start += fs_info->sectorsize * size;
 404                         list_add_tail(&sums->list, &tmplist);
 405                 }
 406                 path->slots[0]++;
 407         }
 408         ret = 0;
 409 fail:
 410         while (ret < 0 && !list_empty(&tmplist)) {
 411                 sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 412                 list_del(&sums->list);
 413                 kfree(sums);
 414         }
 415         list_splice_tail(&tmplist, list);
 416
 417         btrfs_free_path(path);
 418         return ret;
 419 }
 420
 421 /*
 422  * btrfs_csum_one_bio - Calculates checksums of the data contained inside a bio
 423  * @inode:       Owner of the data inside the bio
 424  * @bio:         Contains the data to be checksummed
 425  * @file_start:  offset in file this bio begins to describe
 426  * @contig:      Boolean. If true/1 means all bio vecs in this bio are
 427  *               contiguous and they begin at @file_start in the file. False/0
 428  *               means this bio can contains potentially discontigous bio vecs
 429  *               so the logical offset of each should be calculated separately.
 430  */
 431 blk_status_t btrfs_csum_one_bio(struct inode *inode, struct bio *bio,
 432                        u64 file_start, int contig)
 433 {
 434         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 435         struct btrfs_ordered_sum *sums;
 436         struct btrfs_ordered_extent *ordered = NULL;
 437         char *data;
 438         struct bvec_iter iter;
 439         struct bio_vec bvec;
 440         int index;
 441         int nr_sectors;
 442         unsigned long total_bytes = 0;
 443         unsigned long this_sum_bytes = 0;
 444         int i;
 445         u64 offset;
 446         unsigned nofs_flag;
 447         const u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 448
 449         nofs_flag = memalloc_nofs_save();
 450         sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
 451                        GFP_KERNEL);
 452         memalloc_nofs_restore(nofs_flag);
 453
 454         if (!sums)
 455                 return BLK_STS_RESOURCE;
 456
 457         sums->len = bio->bi_iter.bi_size;
 458         INIT_LIST_HEAD(&sums->list);
 459
 460         if (contig)
 461                 offset = file_start;
 462         else
 463                 offset = 0; /* shut up gcc */
 464
 465         sums->bytenr = (u64)bio->bi_iter.bi_sector << 9;
 466         index = 0;
 467
 468         bio_for_each_segment(bvec, bio, iter) {
 469                 if (!contig)
 470                         offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 471
 472                 if (!ordered) {
 473                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 474                         BUG_ON(!ordered); /* Logic error */
 475                 }
 476
 477                 nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info,
 478                                                  bvec.bv_len + fs_info->sectorsize
 479                                                  - 1);
 480
 481                 for (i = 0; i < nr_sectors; i++) {
 482                         u32 tmp;
 483
 484                         if (offset >= ordered->file_offset + ordered->len ||
 485                                 offset < ordered->file_offset) {
 486                                 unsigned long bytes_left;
 487
 488                                 sums->len = this_sum_bytes;
 489                                 this_sum_bytes = 0;
 490                                 btrfs_add_ordered_sum(ordered, sums);
 491                                 btrfs_put_ordered_extent(ordered);
 492
 493                                 bytes_left = bio->bi_iter.bi_size - total_bytes;
 494
 495                                 nofs_flag = memalloc_nofs_save();
 496                                 sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
 497                                                       bytes_left), GFP_KERNEL);
 498                                 memalloc_nofs_restore(nofs_flag);
 499                                 BUG_ON(!sums); /* -ENOMEM */
 500                                 sums->len = bytes_left;
 501                                 ordered = btrfs_lookup_ordered_extent(inode,
 502                                                                 offset);
 503                                 ASSERT(ordered); /* Logic error */
 504                                 sums->bytenr = ((u64)bio->bi_iter.bi_sector << 9)
 505                                         + total_bytes;
 506                                 index = 0;
 507                         }
 508
 509                         memset(&sums->sums[index], 0xff, csum_size);
 510                         data = kmap_atomic(bvec.bv_page);
 511                         tmp = btrfs_csum_data(data + bvec.bv_offset
 512                                                 + (i * fs_info->sectorsize),
 513                                                 *(u32 *)&sums->sums[index],
 514                                                 fs_info->sectorsize);
 515                         kunmap_atomic(data);
 516                         btrfs_csum_final(tmp,
 517                                         (char *)(sums->sums + index));
 518                         index += csum_size;
 519                         offset += fs_info->sectorsize;
 520                         this_sum_bytes += fs_info->sectorsize;
 521                         total_bytes += fs_info->sectorsize;
 522                 }
 523
 524         }
 525         this_sum_bytes = 0;
 526         btrfs_add_ordered_sum(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_fs_info *fs_info,
 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(fs_info->super_copy);
 549         u64 csum_end;
 550         u64 end_byte = bytenr + len;
 551         u32 blocksize_bits = 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 <<= 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(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(path, new_size, 0);
 580
 581                 key->offset = end_byte;
 582                 btrfs_set_item_key_safe(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_fs_info *fs_info, u64 bytenr, u64 len)
 594 {
 595         struct btrfs_root *root = fs_info->csum_root;
 596         struct btrfs_path *path;
 597         struct btrfs_key key;
 598         u64 end_byte = bytenr + len;
 599         u64 csum_end;
 600         struct extent_buffer *leaf;
 601         int ret;
 602         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 603         int blocksize_bits = fs_info->sb->s_blocksize_bits;
 604
 605         path = btrfs_alloc_path();
 606         if (!path)
 607                 return -ENOMEM;
 608
 609         while (1) {
 610                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 611                 key.offset = end_byte - 1;
 612                 key.type = BTRFS_EXTENT_CSUM_KEY;
 613
 614                 path->leave_spinning = 1;
 615                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 616                 if (ret > 0) {
 617                         if (path->slots[0] == 0)
 618                                 break;
 619                         path->slots[0]--;
 620                 } else if (ret < 0) {
 621                         break;
 622                 }
 623
 624                 leaf = path->nodes[0];
 625                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 626
 627                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 628                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 629                         break;
 630                 }
 631
 632                 if (key.offset >= end_byte)
 633                         break;
 634
 635                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 636                 csum_end <<= blocksize_bits;
 637                 csum_end += key.offset;
 638
 639                 /* this csum ends before we start, we're done */
 640                 if (csum_end <= bytenr)
 641                         break;
 642
 643                 /* delete the entire item, it is inside our range */
 644                 if (key.offset >= bytenr && csum_end <= end_byte) {
 645                         int del_nr = 1;
 646
 647                         /*
 648                          * Check how many csum items preceding this one in this
 649                          * leaf correspond to our range and then delete them all
 650                          * at once.
 651                          */
 652                         if (key.offset > bytenr && path->slots[0] > 0) {
 653                                 int slot = path->slots[0] - 1;
 654
 655                                 while (slot >= 0) {
 656                                         struct btrfs_key pk;
 657
 658                                         btrfs_item_key_to_cpu(leaf, &pk, slot);
 659                                         if (pk.offset < bytenr ||
 660                                             pk.type != BTRFS_EXTENT_CSUM_KEY ||
 661                                             pk.objectid !=
 662                                             BTRFS_EXTENT_CSUM_OBJECTID)
 663                                                 break;
 664                                         path->slots[0] = slot;
 665                                         del_nr++;
 666                                         key.offset = pk.offset;
 667                                         slot--;
 668                                 }
 669                         }
 670                         ret = btrfs_del_items(trans, root, path,
 671                                               path->slots[0], del_nr);
 672                         if (ret)
 673                                 goto out;
 674                         if (key.offset == bytenr)
 675                                 break;
 676                 } else if (key.offset < bytenr && csum_end > end_byte) {
 677                         unsigned long offset;
 678                         unsigned long shift_len;
 679                         unsigned long item_offset;
 680                         /*
 681                          *        [ bytenr - len ]
 682                          *     [csum                ]
 683                          *
 684                          * Our bytes are in the middle of the csum,
 685                          * we need to split this item and insert a new one.
 686                          *
 687                          * But we can't drop the path because the
 688                          * csum could change, get removed, extended etc.
 689                          *
 690                          * The trick here is the max size of a csum item leaves
 691                          * enough room in the tree block for a single
 692                          * item header.  So, we split the item in place,
 693                          * adding a new header pointing to the existing
 694                          * bytes.  Then we loop around again and we have
 695                          * a nicely formed csum item that we can neatly
 696                          * truncate.
 697                          */
 698                         offset = (bytenr - key.offset) >> blocksize_bits;
 699                         offset *= csum_size;
 700
 701                         shift_len = (len >> blocksize_bits) * csum_size;
 702
 703                         item_offset = btrfs_item_ptr_offset(leaf,
 704                                                             path->slots[0]);
 705
 706                         memzero_extent_buffer(leaf, item_offset + offset,
 707                                              shift_len);
 708                         key.offset = bytenr;
 709
 710                         /*
 711                          * btrfs_split_item returns -EAGAIN when the
 712                          * item changed size or key
 713                          */
 714                         ret = btrfs_split_item(trans, root, path, &key, offset);
 715                         if (ret && ret != -EAGAIN) {
 716                                 btrfs_abort_transaction(trans, ret);
 717                                 goto out;
 718                         }
 719
 720                         key.offset = end_byte - 1;
 721                 } else {
 722                         truncate_one_csum(fs_info, path, &key, bytenr, len);
 723                         if (key.offset < bytenr)
 724                                 break;
 725                 }
 726                 btrfs_release_path(path);
 727         }
 728         ret = 0;
 729 out:
 730         btrfs_free_path(path);
 731         return ret;
 732 }
 733
 734 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 735                            struct btrfs_root *root,
 736                            struct btrfs_ordered_sum *sums)
 737 {
 738         struct btrfs_fs_info *fs_info = root->fs_info;
 739         struct btrfs_key file_key;
 740         struct btrfs_key found_key;
 741         struct btrfs_path *path;
 742         struct btrfs_csum_item *item;
 743         struct btrfs_csum_item *item_end;
 744         struct extent_buffer *leaf = NULL;
 745         u64 next_offset;
 746         u64 total_bytes = 0;
 747         u64 csum_offset;
 748         u64 bytenr;
 749         u32 nritems;
 750         u32 ins_size;
 751         int index = 0;
 752         int found_next;
 753         int ret;
 754         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 755
 756         path = btrfs_alloc_path();
 757         if (!path)
 758                 return -ENOMEM;
 759 again:
 760         next_offset = (u64)-1;
 761         found_next = 0;
 762         bytenr = sums->bytenr + total_bytes;
 763         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 764         file_key.offset = bytenr;
 765         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 766
 767         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 768         if (!IS_ERR(item)) {
 769                 ret = 0;
 770                 leaf = path->nodes[0];
 771                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 772                                           struct btrfs_csum_item);
 773                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 774                            btrfs_item_size_nr(leaf, path->slots[0]));
 775                 goto found;
 776         }
 777         ret = PTR_ERR(item);
 778         if (ret != -EFBIG && ret != -ENOENT)
 779                 goto fail_unlock;
 780
 781         if (ret == -EFBIG) {
 782                 u32 item_size;
 783                 /* we found one, but it isn't big enough yet */
 784                 leaf = path->nodes[0];
 785                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 786                 if ((item_size / csum_size) >=
 787                     MAX_CSUM_ITEMS(fs_info, csum_size)) {
 788                         /* already at max size, make a new one */
 789                         goto insert;
 790                 }
 791         } else {
 792                 int slot = path->slots[0] + 1;
 793                 /* we didn't find a csum item, insert one */
 794                 nritems = btrfs_header_nritems(path->nodes[0]);
 795                 if (!nritems || (path->slots[0] >= nritems - 1)) {
 796                         ret = btrfs_next_leaf(root, path);
 797                         if (ret == 1)
 798                                 found_next = 1;
 799                         if (ret != 0)
 800                                 goto insert;
 801                         slot = path->slots[0];
 802                 }
 803                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 804                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 805                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 806                         found_next = 1;
 807                         goto insert;
 808                 }
 809                 next_offset = found_key.offset;
 810                 found_next = 1;
 811                 goto insert;
 812         }
 813
 814         /*
 815          * at this point, we know the tree has an item, but it isn't big
 816          * enough yet to put our csum in.  Grow it
 817          */
 818         btrfs_release_path(path);
 819         ret = btrfs_search_slot(trans, root, &file_key, path,
 820                                 csum_size, 1);
 821         if (ret < 0)
 822                 goto fail_unlock;
 823
 824         if (ret > 0) {
 825                 if (path->slots[0] == 0)
 826                         goto insert;
 827                 path->slots[0]--;
 828         }
 829
 830         leaf = path->nodes[0];
 831         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 832         csum_offset = (bytenr - found_key.offset) >>
 833                         fs_info->sb->s_blocksize_bits;
 834
 835         if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
 836             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 837             csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
 838                 goto insert;
 839         }
 840
 841         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 842             csum_size) {
 843                 int extend_nr;
 844                 u64 tmp;
 845                 u32 diff;
 846                 u32 free_space;
 847
 848                 if (btrfs_leaf_free_space(leaf) <
 849                                  sizeof(struct btrfs_item) + csum_size * 2)
 850                         goto insert;
 851
 852                 free_space = btrfs_leaf_free_space(leaf) -
 853                                          sizeof(struct btrfs_item) - csum_size;
 854                 tmp = sums->len - total_bytes;
 855                 tmp >>= fs_info->sb->s_blocksize_bits;
 856                 WARN_ON(tmp < 1);
 857
 858                 extend_nr = max_t(int, 1, (int)tmp);
 859                 diff = (csum_offset + extend_nr) * csum_size;
 860                 diff = min(diff,
 861                            MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
 862
 863                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 864                 diff = min(free_space, diff);
 865                 diff /= csum_size;
 866                 diff *= csum_size;
 867
 868                 btrfs_extend_item(path, diff);
 869                 ret = 0;
 870                 goto csum;
 871         }
 872
 873 insert:
 874         btrfs_release_path(path);
 875         csum_offset = 0;
 876         if (found_next) {
 877                 u64 tmp;
 878
 879                 tmp = sums->len - total_bytes;
 880                 tmp >>= fs_info->sb->s_blocksize_bits;
 881                 tmp = min(tmp, (next_offset - file_key.offset) >>
 882                                          fs_info->sb->s_blocksize_bits);
 883
 884                 tmp = max_t(u64, 1, tmp);
 885                 tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
 886                 ins_size = csum_size * tmp;
 887         } else {
 888                 ins_size = csum_size;
 889         }
 890         path->leave_spinning = 1;
 891         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 892                                       ins_size);
 893         path->leave_spinning = 0;
 894         if (ret < 0)
 895                 goto fail_unlock;
 896         if (WARN_ON(ret != 0))
 897                 goto fail_unlock;
 898         leaf = path->nodes[0];
 899 csum:
 900         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 901         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 902                                       btrfs_item_size_nr(leaf, path->slots[0]));
 903         item = (struct btrfs_csum_item *)((unsigned char *)item +
 904                                           csum_offset * csum_size);
 905 found:
 906         ins_size = (u32)(sums->len - total_bytes) >>
 907                    fs_info->sb->s_blocksize_bits;
 908         ins_size *= csum_size;
 909         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 910                               ins_size);
 911         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 912                             ins_size);
 913
 914         index += ins_size;
 915         ins_size /= csum_size;
 916         total_bytes += ins_size * fs_info->sectorsize;
 917
 918         btrfs_mark_buffer_dirty(path->nodes[0]);
 919         if (total_bytes < sums->len) {
 920                 btrfs_release_path(path);
 921                 cond_resched();
 922                 goto again;
 923         }
 924 out:
 925         btrfs_free_path(path);
 926         return ret;
 927
 928 fail_unlock:
 929         goto out;
 930 }
 931
 932 void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
 933                                      const struct btrfs_path *path,
 934                                      struct btrfs_file_extent_item *fi,
 935                                      const bool new_inline,
 936                                      struct extent_map *em)
 937 {
 938         struct btrfs_fs_info *fs_info = inode->root->fs_info;
 939         struct btrfs_root *root = inode->root;
 940         struct extent_buffer *leaf = path->nodes[0];
 941         const int slot = path->slots[0];
 942         struct btrfs_key key;
 943         u64 extent_start, extent_end;
 944         u64 bytenr;
 945         u8 type = btrfs_file_extent_type(leaf, fi);
 946         int compress_type = btrfs_file_extent_compression(leaf, fi);
 947
 948         em->bdev = fs_info->fs_devices->latest_bdev;
 949         btrfs_item_key_to_cpu(leaf, &key, slot);
 950         extent_start = key.offset;
 951
 952         if (type == BTRFS_FILE_EXTENT_REG ||
 953             type == BTRFS_FILE_EXTENT_PREALLOC) {
 954                 extent_end = extent_start +
 955                         btrfs_file_extent_num_bytes(leaf, fi);
 956         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 957                 size_t size;
 958                 size = btrfs_file_extent_ram_bytes(leaf, fi);
 959                 extent_end = ALIGN(extent_start + size,
 960                                    fs_info->sectorsize);
 961         }
 962
 963         em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
 964         if (type == BTRFS_FILE_EXTENT_REG ||
 965             type == BTRFS_FILE_EXTENT_PREALLOC) {
 966                 em->start = extent_start;
 967                 em->len = extent_end - extent_start;
 968                 em->orig_start = extent_start -
 969                         btrfs_file_extent_offset(leaf, fi);
 970                 em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
 971                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 972                 if (bytenr == 0) {
 973                         em->block_start = EXTENT_MAP_HOLE;
 974                         return;
 975                 }
 976                 if (compress_type != BTRFS_COMPRESS_NONE) {
 977                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 978                         em->compress_type = compress_type;
 979                         em->block_start = bytenr;
 980                         em->block_len = em->orig_block_len;
 981                 } else {
 982                         bytenr += btrfs_file_extent_offset(leaf, fi);
 983                         em->block_start = bytenr;
 984                         em->block_len = em->len;
 985                         if (type == BTRFS_FILE_EXTENT_PREALLOC)
 986                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
 987                 }
 988         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 989                 em->block_start = EXTENT_MAP_INLINE;
 990                 em->start = extent_start;
 991                 em->len = extent_end - extent_start;
 992                 /*
 993                  * Initialize orig_start and block_len with the same values
 994                  * as in inode.c:btrfs_get_extent().
 995                  */
 996                 em->orig_start = EXTENT_MAP_HOLE;
 997                 em->block_len = (u64)-1;
 998                 if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
 999                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1000                         em->compress_type = compress_type;
1001                 }
1002         } else {
1003                 btrfs_err(fs_info,
1004                           "unknown file extent item type %d, inode %llu, offset %llu, "
1005                           "root %llu", type, btrfs_ino(inode), extent_start,
1006                           root->root_key.objectid);
1007         }
1008 }