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 = bio->bi_io_vec;
 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 bio_index = 0;
 180         int count;
 181         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 182
 183         path = btrfs_alloc_path();
 184         if (!path)
 185                 return -ENOMEM;
 186
 187         nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
 188         if (!dst) {
 189                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 190                         btrfs_bio->csum_allocated = kmalloc_array(nblocks,
 191                                         csum_size, GFP_NOFS);
 192                         if (!btrfs_bio->csum_allocated) {
 193                                 btrfs_free_path(path);
 194                                 return -ENOMEM;
 195                         }
 196                         btrfs_bio->csum = btrfs_bio->csum_allocated;
 197                         btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
 198                 } else {
 199                         btrfs_bio->csum = btrfs_bio->csum_inline;
 200                 }
 201                 csum = btrfs_bio->csum;
 202         } else {
 203                 csum = (u8 *)dst;
 204         }
 205
 206         if (bio->bi_iter.bi_size > PAGE_SIZE * 8)
 207                 path->reada = READA_FORWARD;
 208
 209         WARN_ON(bio->bi_vcnt <= 0);
 210
 211         /*
 212          * the free space stuff is only read when it hasn't been
 213          * updated in the current transaction.  So, we can safely
 214          * read from the commit root and sidestep a nasty deadlock
 215          * between reading the free space cache and updating the csum tree.
 216          */
 217         if (btrfs_is_free_space_inode(inode)) {
 218                 path->search_commit_root = 1;
 219                 path->skip_locking = 1;
 220         }
 221
 222         disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
 223         if (dio)
 224                 offset = logical_offset;
 225
 226         page_bytes_left = bvec->bv_len;
 227         while (bio_index < bio->bi_vcnt) {
 228                 if (!dio)
 229                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 230                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 231                                                (u32 *)csum, nblocks);
 232                 if (count)
 233                         goto found;
 234
 235                 if (!item || disk_bytenr < item_start_offset ||
 236                     disk_bytenr >= item_last_offset) {
 237                         struct btrfs_key found_key;
 238                         u32 item_size;
 239
 240                         if (item)
 241                                 btrfs_release_path(path);
 242                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 243                                                  path, disk_bytenr, 0);
 244                         if (IS_ERR(item)) {
 245                                 count = 1;
 246                                 memset(csum, 0, csum_size);
 247                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 248                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 249                                         set_extent_bits(io_tree, offset,
 250                                                 offset + root->sectorsize - 1,
 251                                                 EXTENT_NODATASUM);
 252                                 } else {
 253                                         btrfs_info_rl(BTRFS_I(inode)->root->fs_info,
 254                                                    "no csum found for inode %llu start %llu",
 255                                                btrfs_ino(inode), offset);
 256                                 }
 257                                 item = NULL;
 258                                 btrfs_release_path(path);
 259                                 goto found;
 260                         }
 261                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 262                                               path->slots[0]);
 263
 264                         item_start_offset = found_key.offset;
 265                         item_size = btrfs_item_size_nr(path->nodes[0],
 266                                                        path->slots[0]);
 267                         item_last_offset = item_start_offset +
 268                                 (item_size / csum_size) *
 269                                 root->sectorsize;
 270                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 271                                               struct btrfs_csum_item);
 272                 }
 273                 /*
 274                  * this byte range must be able to fit inside
 275                  * a single leaf so it will also fit inside a u32
 276                  */
 277                 diff = disk_bytenr - item_start_offset;
 278                 diff = diff / root->sectorsize;
 279                 diff = diff * csum_size;
 280                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 281                                             inode->i_sb->s_blocksize_bits);
 282                 read_extent_buffer(path->nodes[0], csum,
 283                                    ((unsigned long)item) + diff,
 284                                    csum_size * count);
 285 found:
 286                 csum += count * csum_size;
 287                 nblocks -= count;
 288
 289                 while (count--) {
 290                         disk_bytenr += root->sectorsize;
 291                         offset += root->sectorsize;
 292                         page_bytes_left -= root->sectorsize;
 293                         if (!page_bytes_left) {
 294                                 bio_index++;
 295                                 /*
 296                                  * make sure we're still inside the
 297                                  * bio before we update page_bytes_left
 298                                  */
 299                                 if (bio_index >= bio->bi_vcnt) {
 300                                         WARN_ON_ONCE(count);
 301                                         goto done;
 302                                 }
 303                                 bvec++;
 304                                 page_bytes_left = bvec->bv_len;
 305                         }
 306
 307                 }
 308         }
 309
 310 done:
 311         btrfs_free_path(path);
 312         return 0;
 313 }
 314
 315 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 316                           struct bio *bio, u32 *dst)
 317 {
 318         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 319 }
 320
 321 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 322                               struct bio *bio, u64 offset)
 323 {
 324         return __btrfs_lookup_bio_sums(root, inode, bio, offset, NULL, 1);
 325 }
 326
 327 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 328                              struct list_head *list, int search_commit)
 329 {
 330         struct btrfs_key key;
 331         struct btrfs_path *path;
 332         struct extent_buffer *leaf;
 333         struct btrfs_ordered_sum *sums;
 334         struct btrfs_csum_item *item;
 335         LIST_HEAD(tmplist);
 336         unsigned long offset;
 337         int ret;
 338         size_t size;
 339         u64 csum_end;
 340         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 341
 342         ASSERT(IS_ALIGNED(start, root->sectorsize) &&
 343                IS_ALIGNED(end + 1, root->sectorsize));
 344
 345         path = btrfs_alloc_path();
 346         if (!path)
 347                 return -ENOMEM;
 348
 349         if (search_commit) {
 350                 path->skip_locking = 1;
 351                 path->reada = READA_FORWARD;
 352                 path->search_commit_root = 1;
 353         }
 354
 355         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 356         key.offset = start;
 357         key.type = BTRFS_EXTENT_CSUM_KEY;
 358
 359         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 360         if (ret < 0)
 361                 goto fail;
 362         if (ret > 0 && path->slots[0] > 0) {
 363                 leaf = path->nodes[0];
 364                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 365                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 366                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 367                         offset = (start - key.offset) >>
 368                                  root->fs_info->sb->s_blocksize_bits;
 369                         if (offset * csum_size <
 370                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 371                                 path->slots[0]--;
 372                 }
 373         }
 374
 375         while (start <= end) {
 376                 leaf = path->nodes[0];
 377                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 378                         ret = btrfs_next_leaf(root, path);
 379                         if (ret < 0)
 380                                 goto fail;
 381                         if (ret > 0)
 382                                 break;
 383                         leaf = path->nodes[0];
 384                 }
 385
 386                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 387                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 388                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 389                     key.offset > end)
 390                         break;
 391
 392                 if (key.offset > start)
 393                         start = key.offset;
 394
 395                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 396                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 397                 if (csum_end <= start) {
 398                         path->slots[0]++;
 399                         continue;
 400                 }
 401
 402                 csum_end = min(csum_end, end + 1);
 403                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 404                                       struct btrfs_csum_item);
 405                 while (start < csum_end) {
 406                         size = min_t(size_t, csum_end - start,
 407                                      MAX_ORDERED_SUM_BYTES(root));
 408                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 409                                        GFP_NOFS);
 410                         if (!sums) {
 411                                 ret = -ENOMEM;
 412                                 goto fail;
 413                         }
 414
 415                         sums->bytenr = start;
 416                         sums->len = (int)size;
 417
 418                         offset = (start - key.offset) >>
 419                                 root->fs_info->sb->s_blocksize_bits;
 420                         offset *= csum_size;
 421                         size >>= root->fs_info->sb->s_blocksize_bits;
 422
 423                         read_extent_buffer(path->nodes[0],
 424                                            sums->sums,
 425                                            ((unsigned long)item) + offset,
 426                                            csum_size * size);
 427
 428                         start += root->sectorsize * size;
 429                         list_add_tail(&sums->list, &tmplist);
 430                 }
 431                 path->slots[0]++;
 432         }
 433         ret = 0;
 434 fail:
 435         while (ret < 0 && !list_empty(&tmplist)) {
 436                 sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 437                 list_del(&sums->list);
 438                 kfree(sums);
 439         }
 440         list_splice_tail(&tmplist, list);
 441
 442         btrfs_free_path(path);
 443         return ret;
 444 }
 445
 446 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 447                        struct bio *bio, u64 file_start, int contig)
 448 {
 449         struct btrfs_ordered_sum *sums;
 450         struct btrfs_ordered_extent *ordered;
 451         char *data;
 452         struct bio_vec *bvec = bio->bi_io_vec;
 453         int bio_index = 0;
 454         int index;
 455         int nr_sectors;
 456         int i;
 457         unsigned long total_bytes = 0;
 458         unsigned long this_sum_bytes = 0;
 459         u64 offset;
 460
 461         WARN_ON(bio->bi_vcnt <= 0);
 462         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_iter.bi_size),
 463                        GFP_NOFS);
 464         if (!sums)
 465                 return -ENOMEM;
 466
 467         sums->len = bio->bi_iter.bi_size;
 468         INIT_LIST_HEAD(&sums->list);
 469
 470         if (contig)
 471                 offset = file_start;
 472         else
 473                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 474
 475         ordered = btrfs_lookup_ordered_extent(inode, offset);
 476         BUG_ON(!ordered); /* Logic error */
 477         sums->bytenr = (u64)bio->bi_iter.bi_sector << 9;
 478         index = 0;
 479
 480         while (bio_index < bio->bi_vcnt) {
 481                 if (!contig)
 482                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 483
 484                 data = kmap_atomic(bvec->bv_page);
 485
 486                 nr_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
 487                                                 bvec->bv_len + root->sectorsize
 488                                                 - 1);
 489
 490                 for (i = 0; i < nr_sectors; i++) {
 491                         if (offset >= ordered->file_offset + ordered->len ||
 492                                 offset < ordered->file_offset) {
 493                                 unsigned long bytes_left;
 494
 495                                 kunmap_atomic(data);
 496                                 sums->len = this_sum_bytes;
 497                                 this_sum_bytes = 0;
 498                                 btrfs_add_ordered_sum(inode, ordered, sums);
 499                                 btrfs_put_ordered_extent(ordered);
 500
 501                                 bytes_left = bio->bi_iter.bi_size - total_bytes;
 502
 503                                 sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 504                                         GFP_NOFS);
 505                                 BUG_ON(!sums); /* -ENOMEM */
 506                                 sums->len = bytes_left;
 507                                 ordered = btrfs_lookup_ordered_extent(inode,
 508                                                                 offset);
 509                                 ASSERT(ordered); /* Logic error */
 510                                 sums->bytenr = ((u64)bio->bi_iter.bi_sector << 9)
 511                                         + total_bytes;
 512                                 index = 0;
 513
 514                                 data = kmap_atomic(bvec->bv_page);
 515                         }
 516
 517                         sums->sums[index] = ~(u32)0;
 518                         sums->sums[index]
 519                                 = btrfs_csum_data(data + bvec->bv_offset
 520                                                 + (i * root->sectorsize),
 521                                                 sums->sums[index],
 522                                                 root->sectorsize);
 523                         btrfs_csum_final(sums->sums[index],
 524                                         (char *)(sums->sums + index));
 525                         index++;
 526                         offset += root->sectorsize;
 527                         this_sum_bytes += root->sectorsize;
 528                         total_bytes += root->sectorsize;
 529                 }
 530
 531                 kunmap_atomic(data);
 532
 533                 bio_index++;
 534                 bvec++;
 535         }
 536         this_sum_bytes = 0;
 537         btrfs_add_ordered_sum(inode, ordered, sums);
 538         btrfs_put_ordered_extent(ordered);
 539         return 0;
 540 }
 541
 542 /*
 543  * helper function for csum removal, this expects the
 544  * key to describe the csum pointed to by the path, and it expects
 545  * the csum to overlap the range [bytenr, len]
 546  *
 547  * The csum should not be entirely contained in the range and the
 548  * range should not be entirely contained in the csum.
 549  *
 550  * This calls btrfs_truncate_item with the correct args based on the
 551  * overlap, and fixes up the key as required.
 552  */
 553 static noinline void truncate_one_csum(struct btrfs_root *root,
 554                                        struct btrfs_path *path,
 555                                        struct btrfs_key *key,
 556                                        u64 bytenr, u64 len)
 557 {
 558         struct extent_buffer *leaf;
 559         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 560         u64 csum_end;
 561         u64 end_byte = bytenr + len;
 562         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 563
 564         leaf = path->nodes[0];
 565         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 566         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 567         csum_end += key->offset;
 568
 569         if (key->offset < bytenr && csum_end <= end_byte) {
 570                 /*
 571                  *         [ bytenr - len ]
 572                  *         [   ]
 573                  *   [csum     ]
 574                  *   A simple truncate off the end of the item
 575                  */
 576                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 577                 new_size *= csum_size;
 578                 btrfs_truncate_item(root, path, new_size, 1);
 579         } else if (key->offset >= bytenr && csum_end > end_byte &&
 580                    end_byte > key->offset) {
 581                 /*
 582                  *         [ bytenr - len ]
 583                  *                 [ ]
 584                  *                 [csum     ]
 585                  * we need to truncate from the beginning of the csum
 586                  */
 587                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 588                 new_size *= csum_size;
 589
 590                 btrfs_truncate_item(root, path, new_size, 0);
 591
 592                 key->offset = end_byte;
 593                 btrfs_set_item_key_safe(root->fs_info, path, key);
 594         } else {
 595                 BUG();
 596         }
 597 }
 598
 599 /*
 600  * deletes the csum items from the csum tree for a given
 601  * range of bytes.
 602  */
 603 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 604                     struct btrfs_root *root, u64 bytenr, u64 len)
 605 {
 606         struct btrfs_path *path;
 607         struct btrfs_key key;
 608         u64 end_byte = bytenr + len;
 609         u64 csum_end;
 610         struct extent_buffer *leaf;
 611         int ret = 0;
 612         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 613         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 614
 615         root = root->fs_info->csum_root;
 616
 617         path = btrfs_alloc_path();
 618         if (!path)
 619                 return -ENOMEM;
 620
 621         while (1) {
 622                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 623                 key.offset = end_byte - 1;
 624                 key.type = BTRFS_EXTENT_CSUM_KEY;
 625
 626                 path->leave_spinning = 1;
 627                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 628                 if (ret > 0) {
 629                         ret = 0;
 630                         if (path->slots[0] == 0)
 631                                 break;
 632                         path->slots[0]--;
 633                 } else if (ret < 0) {
 634                         break;
 635                 }
 636
 637                 leaf = path->nodes[0];
 638                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 639
 640                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 641                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 642                         break;
 643                 }
 644
 645                 if (key.offset >= end_byte)
 646                         break;
 647
 648                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 649                 csum_end <<= blocksize_bits;
 650                 csum_end += key.offset;
 651
 652                 /* this csum ends before we start, we're done */
 653                 if (csum_end <= bytenr)
 654                         break;
 655
 656                 /* delete the entire item, it is inside our range */
 657                 if (key.offset >= bytenr && csum_end <= end_byte) {
 658                         ret = btrfs_del_item(trans, root, path);
 659                         if (ret)
 660                                 break;
 661                         if (key.offset == bytenr)
 662                                 break;
 663                 } else if (key.offset < bytenr && csum_end > end_byte) {
 664                         unsigned long offset;
 665                         unsigned long shift_len;
 666                         unsigned long item_offset;
 667                         /*
 668                          *        [ bytenr - len ]
 669                          *     [csum                ]
 670                          *
 671                          * Our bytes are in the middle of the csum,
 672                          * we need to split this item and insert a new one.
 673                          *
 674                          * But we can't drop the path because the
 675                          * csum could change, get removed, extended etc.
 676                          *
 677                          * The trick here is the max size of a csum item leaves
 678                          * enough room in the tree block for a single
 679                          * item header.  So, we split the item in place,
 680                          * adding a new header pointing to the existing
 681                          * bytes.  Then we loop around again and we have
 682                          * a nicely formed csum item that we can neatly
 683                          * truncate.
 684                          */
 685                         offset = (bytenr - key.offset) >> blocksize_bits;
 686                         offset *= csum_size;
 687
 688                         shift_len = (len >> blocksize_bits) * csum_size;
 689
 690                         item_offset = btrfs_item_ptr_offset(leaf,
 691                                                             path->slots[0]);
 692
 693                         memset_extent_buffer(leaf, 0, item_offset + offset,
 694                                              shift_len);
 695                         key.offset = bytenr;
 696
 697                         /*
 698                          * btrfs_split_item returns -EAGAIN when the
 699                          * item changed size or key
 700                          */
 701                         ret = btrfs_split_item(trans, root, path, &key, offset);
 702                         if (ret && ret != -EAGAIN) {
 703                                 btrfs_abort_transaction(trans, ret);
 704                                 break;
 705                         }
 706                         ret = 0;
 707
 708                         key.offset = end_byte - 1;
 709                 } else {
 710                         truncate_one_csum(root, path, &key, bytenr, len);
 711                         if (key.offset < bytenr)
 712                                 break;
 713                 }
 714                 btrfs_release_path(path);
 715         }
 716         btrfs_free_path(path);
 717         return ret;
 718 }
 719
 720 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 721                            struct btrfs_root *root,
 722                            struct btrfs_ordered_sum *sums)
 723 {
 724         struct btrfs_key file_key;
 725         struct btrfs_key found_key;
 726         struct btrfs_path *path;
 727         struct btrfs_csum_item *item;
 728         struct btrfs_csum_item *item_end;
 729         struct extent_buffer *leaf = NULL;
 730         u64 next_offset;
 731         u64 total_bytes = 0;
 732         u64 csum_offset;
 733         u64 bytenr;
 734         u32 nritems;
 735         u32 ins_size;
 736         int index = 0;
 737         int found_next;
 738         int ret;
 739         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 740
 741         path = btrfs_alloc_path();
 742         if (!path)
 743                 return -ENOMEM;
 744 again:
 745         next_offset = (u64)-1;
 746         found_next = 0;
 747         bytenr = sums->bytenr + total_bytes;
 748         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 749         file_key.offset = bytenr;
 750         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 751
 752         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 753         if (!IS_ERR(item)) {
 754                 ret = 0;
 755                 leaf = path->nodes[0];
 756                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 757                                           struct btrfs_csum_item);
 758                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 759                            btrfs_item_size_nr(leaf, path->slots[0]));
 760                 goto found;
 761         }
 762         ret = PTR_ERR(item);
 763         if (ret != -EFBIG && ret != -ENOENT)
 764                 goto fail_unlock;
 765
 766         if (ret == -EFBIG) {
 767                 u32 item_size;
 768                 /* we found one, but it isn't big enough yet */
 769                 leaf = path->nodes[0];
 770                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 771                 if ((item_size / csum_size) >=
 772                     MAX_CSUM_ITEMS(root, csum_size)) {
 773                         /* already at max size, make a new one */
 774                         goto insert;
 775                 }
 776         } else {
 777                 int slot = path->slots[0] + 1;
 778                 /* we didn't find a csum item, insert one */
 779                 nritems = btrfs_header_nritems(path->nodes[0]);
 780                 if (!nritems || (path->slots[0] >= nritems - 1)) {
 781                         ret = btrfs_next_leaf(root, path);
 782                         if (ret < 0) {
 783                                 goto out;
 784                         } else if (ret > 0) {
 785                                 found_next = 1;
 786                                 goto insert;
 787                         }
 788                         slot = path->slots[0];
 789                 }
 790                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 791                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 792                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 793                         found_next = 1;
 794                         goto insert;
 795                 }
 796                 next_offset = found_key.offset;
 797                 found_next = 1;
 798                 goto insert;
 799         }
 800
 801         /*
 802          * at this point, we know the tree has an item, but it isn't big
 803          * enough yet to put our csum in.  Grow it
 804          */
 805         btrfs_release_path(path);
 806         ret = btrfs_search_slot(trans, root, &file_key, path,
 807                                 csum_size, 1);
 808         if (ret < 0)
 809                 goto fail_unlock;
 810
 811         if (ret > 0) {
 812                 if (path->slots[0] == 0)
 813                         goto insert;
 814                 path->slots[0]--;
 815         }
 816
 817         leaf = path->nodes[0];
 818         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 819         csum_offset = (bytenr - found_key.offset) >>
 820                         root->fs_info->sb->s_blocksize_bits;
 821
 822         if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
 823             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 824             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 825                 goto insert;
 826         }
 827
 828         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 829             csum_size) {
 830                 int extend_nr;
 831                 u64 tmp;
 832                 u32 diff;
 833                 u32 free_space;
 834
 835                 if (btrfs_leaf_free_space(root, leaf) <
 836                                  sizeof(struct btrfs_item) + csum_size * 2)
 837                         goto insert;
 838
 839                 free_space = btrfs_leaf_free_space(root, leaf) -
 840                                          sizeof(struct btrfs_item) - csum_size;
 841                 tmp = sums->len - total_bytes;
 842                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 843                 WARN_ON(tmp < 1);
 844
 845                 extend_nr = max_t(int, 1, (int)tmp);
 846                 diff = (csum_offset + extend_nr) * csum_size;
 847                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 848
 849                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 850                 diff = min(free_space, diff);
 851                 diff /= csum_size;
 852                 diff *= csum_size;
 853
 854                 btrfs_extend_item(root, path, diff);
 855                 ret = 0;
 856                 goto csum;
 857         }
 858
 859 insert:
 860         btrfs_release_path(path);
 861         csum_offset = 0;
 862         if (found_next) {
 863                 u64 tmp;
 864
 865                 tmp = sums->len - total_bytes;
 866                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 867                 tmp = min(tmp, (next_offset - file_key.offset) >>
 868                                          root->fs_info->sb->s_blocksize_bits);
 869
 870                 tmp = max((u64)1, tmp);
 871                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 872                 ins_size = csum_size * tmp;
 873         } else {
 874                 ins_size = csum_size;
 875         }
 876         path->leave_spinning = 1;
 877         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 878                                       ins_size);
 879         path->leave_spinning = 0;
 880         if (ret < 0)
 881                 goto fail_unlock;
 882         if (WARN_ON(ret != 0))
 883                 goto fail_unlock;
 884         leaf = path->nodes[0];
 885 csum:
 886         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 887         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 888                                       btrfs_item_size_nr(leaf, path->slots[0]));
 889         item = (struct btrfs_csum_item *)((unsigned char *)item +
 890                                           csum_offset * csum_size);
 891 found:
 892         ins_size = (u32)(sums->len - total_bytes) >>
 893                    root->fs_info->sb->s_blocksize_bits;
 894         ins_size *= csum_size;
 895         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 896                               ins_size);
 897         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 898                             ins_size);
 899
 900         ins_size /= csum_size;
 901         total_bytes += ins_size * root->sectorsize;
 902         index += ins_size;
 903
 904         btrfs_mark_buffer_dirty(path->nodes[0]);
 905         if (total_bytes < sums->len) {
 906                 btrfs_release_path(path);
 907                 cond_resched();
 908                 goto again;
 909         }
 910 out:
 911         btrfs_free_path(path);
 912         return ret;
 913
 914 fail_unlock:
 915         goto out;
 916 }
 917
 918 void btrfs_extent_item_to_extent_map(struct inode *inode,
 919                                      const struct btrfs_path *path,
 920                                      struct btrfs_file_extent_item *fi,
 921                                      const bool new_inline,
 922                                      struct extent_map *em)
 923 {
 924         struct btrfs_root *root = BTRFS_I(inode)->root;
 925         struct extent_buffer *leaf = path->nodes[0];
 926         const int slot = path->slots[0];
 927         struct btrfs_key key;
 928         u64 extent_start, extent_end;
 929         u64 bytenr;
 930         u8 type = btrfs_file_extent_type(leaf, fi);
 931         int compress_type = btrfs_file_extent_compression(leaf, fi);
 932
 933         em->bdev = root->fs_info->fs_devices->latest_bdev;
 934         btrfs_item_key_to_cpu(leaf, &key, slot);
 935         extent_start = key.offset;
 936
 937         if (type == BTRFS_FILE_EXTENT_REG ||
 938             type == BTRFS_FILE_EXTENT_PREALLOC) {
 939                 extent_end = extent_start +
 940                         btrfs_file_extent_num_bytes(leaf, fi);
 941         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 942                 size_t size;
 943                 size = btrfs_file_extent_inline_len(leaf, slot, fi);
 944                 extent_end = ALIGN(extent_start + size, root->sectorsize);
 945         }
 946
 947         em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
 948         if (type == BTRFS_FILE_EXTENT_REG ||
 949             type == BTRFS_FILE_EXTENT_PREALLOC) {
 950                 em->start = extent_start;
 951                 em->len = extent_end - extent_start;
 952                 em->orig_start = extent_start -
 953                         btrfs_file_extent_offset(leaf, fi);
 954                 em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
 955                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 956                 if (bytenr == 0) {
 957                         em->block_start = EXTENT_MAP_HOLE;
 958                         return;
 959                 }
 960                 if (compress_type != BTRFS_COMPRESS_NONE) {
 961                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 962                         em->compress_type = compress_type;
 963                         em->block_start = bytenr;
 964                         em->block_len = em->orig_block_len;
 965                 } else {
 966                         bytenr += btrfs_file_extent_offset(leaf, fi);
 967                         em->block_start = bytenr;
 968                         em->block_len = em->len;
 969                         if (type == BTRFS_FILE_EXTENT_PREALLOC)
 970                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
 971                 }
 972         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 973                 em->block_start = EXTENT_MAP_INLINE;
 974                 em->start = extent_start;
 975                 em->len = extent_end - extent_start;
 976                 /*
 977                  * Initialize orig_start and block_len with the same values
 978                  * as in inode.c:btrfs_get_extent().
 979                  */
 980                 em->orig_start = EXTENT_MAP_HOLE;
 981                 em->block_len = (u64)-1;
 982                 if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
 983                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 984                         em->compress_type = compress_type;
 985                 }
 986         } else {
 987                 btrfs_err(root->fs_info,
 988                           "unknown file extent item type %d, inode %llu, offset %llu, root %llu",
 989                           type, btrfs_ino(inode), extent_start,
 990                           root->root_key.objectid);
 991         }
 992 }