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(fs_info) ((PAGE_SIZE - \
  38                                    sizeof(struct btrfs_ordered_sum)) / \
  39                                    sizeof(u32) * (fs_info)->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         struct btrfs_fs_info *fs_info = root->fs_info;
  94         int ret;
  95         struct btrfs_key file_key;
  96         struct btrfs_key found_key;
  97         struct btrfs_csum_item *item;
  98         struct extent_buffer *leaf;
  99         u64 csum_offset = 0;
 100         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 101         int csums_in_item;
 102
 103         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 104         file_key.offset = bytenr;
 105         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 106         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 107         if (ret < 0)
 108                 goto fail;
 109         leaf = path->nodes[0];
 110         if (ret > 0) {
 111                 ret = 1;
 112                 if (path->slots[0] == 0)
 113                         goto fail;
 114                 path->slots[0]--;
 115                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 116                 if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 117                         goto fail;
 118
 119                 csum_offset = (bytenr - found_key.offset) >>
 120                                 fs_info->sb->s_blocksize_bits;
 121                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 122                 csums_in_item /= csum_size;
 123
 124                 if (csum_offset == csums_in_item) {
 125                         ret = -EFBIG;
 126                         goto fail;
 127                 } else if (csum_offset > csums_in_item) {
 128                         goto fail;
 129                 }
 130         }
 131         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 132         item = (struct btrfs_csum_item *)((unsigned char *)item +
 133                                           csum_offset * csum_size);
 134         return item;
 135 fail:
 136         if (ret > 0)
 137                 ret = -ENOENT;
 138         return ERR_PTR(ret);
 139 }
 140
 141 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 142                              struct btrfs_root *root,
 143                              struct btrfs_path *path, u64 objectid,
 144                              u64 offset, int mod)
 145 {
 146         int ret;
 147         struct btrfs_key file_key;
 148         int ins_len = mod < 0 ? -1 : 0;
 149         int cow = mod != 0;
 150
 151         file_key.objectid = objectid;
 152         file_key.offset = offset;
 153         file_key.type = BTRFS_EXTENT_DATA_KEY;
 154         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 155         return ret;
 156 }
 157
 158 static void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)
 159 {
 160         kfree(bio->csum_allocated);
 161 }
 162
 163 static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
 164                                    u64 logical_offset, u32 *dst, int dio)
 165 {
 166         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 167         struct bio_vec bvec;
 168         struct bvec_iter iter;
 169         struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
 170         struct btrfs_csum_item *item = NULL;
 171         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 172         struct btrfs_path *path;
 173         u8 *csum;
 174         u64 offset = 0;
 175         u64 item_start_offset = 0;
 176         u64 item_last_offset = 0;
 177         u64 disk_bytenr;
 178         u64 page_bytes_left;
 179         u32 diff;
 180         int nblocks;
 181         int count = 0;
 182         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 183
 184         path = btrfs_alloc_path();
 185         if (!path)
 186                 return BLK_STS_RESOURCE;
 187
 188         nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
 189         if (!dst) {
 190                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 191                         btrfs_bio->csum_allocated = kmalloc_array(nblocks,
 192                                         csum_size, GFP_NOFS);
 193                         if (!btrfs_bio->csum_allocated) {
 194                                 btrfs_free_path(path);
 195                                 return BLK_STS_RESOURCE;
 196                         }
 197                         btrfs_bio->csum = btrfs_bio->csum_allocated;
 198                         btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
 199                 } else {
 200                         btrfs_bio->csum = btrfs_bio->csum_inline;
 201                 }
 202                 csum = btrfs_bio->csum;
 203         } else {
 204                 csum = (u8 *)dst;
 205         }
 206
 207         if (bio->bi_iter.bi_size > PAGE_SIZE * 8)
 208                 path->reada = READA_FORWARD;
 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(BTRFS_I(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(bvec, bio, iter) {
 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, 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 + fs_info->sectorsize - 1,
 253                                                 EXTENT_NODATASUM);
 254                                 } else {
 255                                         btrfs_info_rl(fs_info,
 256                                                    "no csum found for inode %llu start %llu",
 257                                                btrfs_ino(BTRFS_I(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                                 fs_info->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 / fs_info->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 += fs_info->sectorsize;
 293                         offset += fs_info->sectorsize;
 294                         page_bytes_left -= fs_info->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 blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u32 *dst)
 306 {
 307         return __btrfs_lookup_bio_sums(inode, bio, 0, dst, 0);
 308 }
 309
 310 blk_status_t btrfs_lookup_bio_sums_dio(struct inode *inode, struct bio *bio, u64 offset)
 311 {
 312         return __btrfs_lookup_bio_sums(inode, bio, offset, NULL, 1);
 313 }
 314
 315 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 316                              struct list_head *list, int search_commit)
 317 {
 318         struct btrfs_fs_info *fs_info = root->fs_info;
 319         struct btrfs_key key;
 320         struct btrfs_path *path;
 321         struct extent_buffer *leaf;
 322         struct btrfs_ordered_sum *sums;
 323         struct btrfs_csum_item *item;
 324         LIST_HEAD(tmplist);
 325         unsigned long offset;
 326         int ret;
 327         size_t size;
 328         u64 csum_end;
 329         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 330
 331         ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 332                IS_ALIGNED(end + 1, fs_info->sectorsize));
 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 = READA_FORWARD;
 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                                  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) * fs_info->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(fs_info));
 397                         sums = kzalloc(btrfs_ordered_sum_size(fs_info, 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                                 fs_info->sb->s_blocksize_bits;
 409                         offset *= csum_size;
 410                         size >>= 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 += fs_info->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.next, 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 blk_status_t btrfs_csum_one_bio(struct inode *inode, struct bio *bio,
 436                        u64 file_start, int contig)
 437 {
 438         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 439         struct btrfs_ordered_sum *sums;
 440         struct btrfs_ordered_extent *ordered = NULL;
 441         char *data;
 442         struct bvec_iter iter;
 443         struct bio_vec bvec;
 444         int index;
 445         int nr_sectors;
 446         unsigned long total_bytes = 0;
 447         unsigned long this_sum_bytes = 0;
 448         int i;
 449         u64 offset;
 450
 451         sums = kzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
 452                        GFP_NOFS);
 453         if (!sums)
 454                 return BLK_STS_RESOURCE;
 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(bvec, bio, iter) {
 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(fs_info,
 479                                                  bvec.bv_len + fs_info->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(fs_info, 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 * fs_info->sectorsize),
 513                                                 sums->sums[index],
 514                                                 fs_info->sectorsize);
 515                         btrfs_csum_final(sums->sums[index],
 516                                         (char *)(sums->sums + index));
 517                         index++;
 518                         offset += fs_info->sectorsize;
 519                         this_sum_bytes += fs_info->sectorsize;
 520                         total_bytes += fs_info->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_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(fs_info, 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(fs_info, 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(fs_info, leaf) <
 849                                  sizeof(struct btrfs_item) + csum_size * 2)
 850                         goto insert;
 851
 852                 free_space = btrfs_leaf_free_space(fs_info, 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(fs_info, 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         ins_size /= csum_size;
 915         total_bytes += ins_size * fs_info->sectorsize;
 916         index += ins_size;
 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 = btrfs_sb(inode->vfs_inode.i_sb);
 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_inline_len(leaf, slot, 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 }