kernel/fs/btrfs/file-item.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/bio.h>
  20 #include <linux/slab.h>
  21 #include <linux/pagemap.h>
  22 #include <linux/highmem.h>
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "transaction.h"
  26 #include "volumes.h"
  27 #include "print-tree.h"
  28
  29 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  30                                    sizeof(struct btrfs_item) * 2) / \
  31                                   size) - 1))
  32
  33 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  34                                        PAGE_CACHE_SIZE))
  35
  36 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
  37                                    sizeof(struct btrfs_ordered_sum)) / \
  38                                    sizeof(u32) * (r)->sectorsize)
  39
  40 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  41                              struct btrfs_root *root,
  42                              u64 objectid, u64 pos,
  43                              u64 disk_offset, u64 disk_num_bytes,
  44                              u64 num_bytes, u64 offset, u64 ram_bytes,
  45                              u8 compression, u8 encryption, u16 other_encoding)
  46 {
  47         int ret = 0;
  48         struct btrfs_file_extent_item *item;
  49         struct btrfs_key file_key;
  50         struct btrfs_path *path;
  51         struct extent_buffer *leaf;
  52
  53         path = btrfs_alloc_path();
  54         if (!path)
  55                 return -ENOMEM;
  56         file_key.objectid = objectid;
  57         file_key.offset = pos;
  58         file_key.type = BTRFS_EXTENT_DATA_KEY;
  59
  60         path->leave_spinning = 1;
  61         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  62                                       sizeof(*item));
  63         if (ret < 0)
  64                 goto out;
  65         BUG_ON(ret); /* Can't happen */
  66         leaf = path->nodes[0];
  67         item = btrfs_item_ptr(leaf, path->slots[0],
  68                               struct btrfs_file_extent_item);
  69         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  70         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  71         btrfs_set_file_extent_offset(leaf, item, offset);
  72         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  73         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  74         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  75         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  76         btrfs_set_file_extent_compression(leaf, item, compression);
  77         btrfs_set_file_extent_encryption(leaf, item, encryption);
  78         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  79
  80         btrfs_mark_buffer_dirty(leaf);
  81 out:
  82         btrfs_free_path(path);
  83         return ret;
  84 }
  85
  86 static struct btrfs_csum_item *
  87 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  88                   struct btrfs_root *root,
  89                   struct btrfs_path *path,
  90                   u64 bytenr, int cow)
  91 {
  92         int ret;
  93         struct btrfs_key file_key;
  94         struct btrfs_key found_key;
  95         struct btrfs_csum_item *item;
  96         struct extent_buffer *leaf;
  97         u64 csum_offset = 0;
  98         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
  99         int csums_in_item;
 100
 101         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 102         file_key.offset = bytenr;
 103         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 104         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 105         if (ret < 0)
 106                 goto fail;
 107         leaf = path->nodes[0];
 108         if (ret > 0) {
 109                 ret = 1;
 110                 if (path->slots[0] == 0)
 111                         goto fail;
 112                 path->slots[0]--;
 113                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 114                 if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 115                         goto fail;
 116
 117                 csum_offset = (bytenr - found_key.offset) >>
 118                                 root->fs_info->sb->s_blocksize_bits;
 119                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 120                 csums_in_item /= csum_size;
 121
 122                 if (csum_offset == csums_in_item) {
 123                         ret = -EFBIG;
 124                         goto fail;
 125                 } else if (csum_offset > csums_in_item) {
 126                         goto fail;
 127                 }
 128         }
 129         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 130         item = (struct btrfs_csum_item *)((unsigned char *)item +
 131                                           csum_offset * csum_size);
 132         return item;
 133 fail:
 134         if (ret > 0)
 135                 ret = -ENOENT;
 136         return ERR_PTR(ret);
 137 }
 138
 139 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 140                              struct btrfs_root *root,
 141                              struct btrfs_path *path, u64 objectid,
 142                              u64 offset, int mod)
 143 {
 144         int ret;
 145         struct btrfs_key file_key;
 146         int ins_len = mod < 0 ? -1 : 0;
 147         int cow = mod != 0;
 148
 149         file_key.objectid = objectid;
 150         file_key.offset = offset;
 151         file_key.type = BTRFS_EXTENT_DATA_KEY;
 152         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 153         return ret;
 154 }
 155
 156 static void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)
 157 {
 158         kfree(bio->csum_allocated);
 159 }
 160
 161 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 162                                    struct inode *inode, struct bio *bio,
 163                                    u64 logical_offset, u32 *dst, int dio)
 164 {
 165         struct bio_vec *bvec = bio->bi_io_vec;
 166         struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
 167         struct btrfs_csum_item *item = NULL;
 168         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 169         struct btrfs_path *path;
 170         u8 *csum;
 171         u64 offset = 0;
 172         u64 item_start_offset = 0;
 173         u64 item_last_offset = 0;
 174         u64 disk_bytenr;
 175         u32 diff;
 176         int nblocks;
 177         int bio_index = 0;
 178         int count;
 179         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 180
 181         path = btrfs_alloc_path();
 182         if (!path)
 183                 return -ENOMEM;
 184
 185         nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
 186         if (!dst) {
 187                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 188                         btrfs_bio->csum_allocated = kmalloc_array(nblocks,
 189                                         csum_size, GFP_NOFS);
 190                         if (!btrfs_bio->csum_allocated) {
 191                                 btrfs_free_path(path);
 192                                 return -ENOMEM;
 193                         }
 194                         btrfs_bio->csum = btrfs_bio->csum_allocated;
 195                         btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
 196                 } else {
 197                         btrfs_bio->csum = btrfs_bio->csum_inline;
 198                 }
 199                 csum = btrfs_bio->csum;
 200         } else {
 201                 csum = (u8 *)dst;
 202         }
 203
 204         if (bio->bi_iter.bi_size > PAGE_CACHE_SIZE * 8)
 205                 path->reada = 2;
 206
 207         WARN_ON(bio->bi_vcnt <= 0);
 208
 209         /*
 210          * the free space stuff is only read when it hasn't been
 211          * updated in the current transaction.  So, we can safely
 212          * read from the commit root and sidestep a nasty deadlock
 213          * between reading the free space cache and updating the csum tree.
 214          */
 215         if (btrfs_is_free_space_inode(inode)) {
 216                 path->search_commit_root = 1;
 217                 path->skip_locking = 1;
 218         }
 219
 220         disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
 221         if (dio)
 222                 offset = logical_offset;
 223         while (bio_index < bio->bi_vcnt) {
 224                 if (!dio)
 225                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 226                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 227                                                (u32 *)csum, nblocks);
 228                 if (count)
 229                         goto found;
 230
 231                 if (!item || disk_bytenr < item_start_offset ||
 232                     disk_bytenr >= item_last_offset) {
 233                         struct btrfs_key found_key;
 234                         u32 item_size;
 235
 236                         if (item)
 237                                 btrfs_release_path(path);
 238                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
 239                                                  path, disk_bytenr, 0);
 240                         if (IS_ERR(item)) {
 241                                 count = 1;
 242                                 memset(csum, 0, csum_size);
 243                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 244                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 245                                         set_extent_bits(io_tree, offset,
 246                                                 offset + bvec->bv_len - 1,
 247                                                 EXTENT_NODATASUM, GFP_NOFS);
 248                                 } else {
 249                                         btrfs_info(BTRFS_I(inode)->root->fs_info,
 250                                                    "no csum found for inode %llu start %llu",
 251                                                btrfs_ino(inode), offset);
 252                                 }
 253                                 item = NULL;
 254                                 btrfs_release_path(path);
 255                                 goto found;
 256                         }
 257                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 258                                               path->slots[0]);
 259
 260                         item_start_offset = found_key.offset;
 261                         item_size = btrfs_item_size_nr(path->nodes[0],
 262                                                        path->slots[0]);
 263                         item_last_offset = item_start_offset +
 264                                 (item_size / csum_size) *
 265                                 root->sectorsize;
 266                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 267                                               struct btrfs_csum_item);
 268                 }
 269                 /*
 270                  * this byte range must be able to fit inside
 271                  * a single leaf so it will also fit inside a u32
 272                  */
 273                 diff = disk_bytenr - item_start_offset;
 274                 diff = diff / root->sectorsize;
 275                 diff = diff * csum_size;
 276                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 277                                             inode->i_sb->s_blocksize_bits);
 278                 read_extent_buffer(path->nodes[0], csum,
 279                                    ((unsigned long)item) + diff,
 280                                    csum_size * count);
 281 found:
 282                 csum += count * csum_size;
 283                 nblocks -= count;
 284                 bio_index += count;
 285                 while (count--) {
 286                         disk_bytenr += bvec->bv_len;
 287                         offset += bvec->bv_len;
 288                         bvec++;
 289                 }
 290         }
 291         btrfs_free_path(path);
 292         return 0;
 293 }
 294
 295 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 296                           struct bio *bio, u32 *dst)
 297 {
 298         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
 299 }
 300
 301 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 302                               struct bio *bio, u64 offset)
 303 {
 304         return __btrfs_lookup_bio_sums(root, inode, bio, offset, NULL, 1);
 305 }
 306
 307 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 308                              struct list_head *list, int search_commit)
 309 {
 310         struct btrfs_key key;
 311         struct btrfs_path *path;
 312         struct extent_buffer *leaf;
 313         struct btrfs_ordered_sum *sums;
 314         struct btrfs_csum_item *item;
 315         LIST_HEAD(tmplist);
 316         unsigned long offset;
 317         int ret;
 318         size_t size;
 319         u64 csum_end;
 320         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 321
 322         ASSERT(IS_ALIGNED(start, root->sectorsize) &&
 323                IS_ALIGNED(end + 1, root->sectorsize));
 324
 325         path = btrfs_alloc_path();
 326         if (!path)
 327                 return -ENOMEM;
 328
 329         if (search_commit) {
 330                 path->skip_locking = 1;
 331                 path->reada = 2;
 332                 path->search_commit_root = 1;
 333         }
 334
 335         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 336         key.offset = start;
 337         key.type = BTRFS_EXTENT_CSUM_KEY;
 338
 339         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 340         if (ret < 0)
 341                 goto fail;
 342         if (ret > 0 && path->slots[0] > 0) {
 343                 leaf = path->nodes[0];
 344                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 345                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 346                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 347                         offset = (start - key.offset) >>
 348                                  root->fs_info->sb->s_blocksize_bits;
 349                         if (offset * csum_size <
 350                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 351                                 path->slots[0]--;
 352                 }
 353         }
 354
 355         while (start <= end) {
 356                 leaf = path->nodes[0];
 357                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 358                         ret = btrfs_next_leaf(root, path);
 359                         if (ret < 0)
 360                                 goto fail;
 361                         if (ret > 0)
 362                                 break;
 363                         leaf = path->nodes[0];
 364                 }
 365
 366                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 367                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 368                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 369                     key.offset > end)
 370                         break;
 371
 372                 if (key.offset > start)
 373                         start = key.offset;
 374
 375                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 376                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
 377                 if (csum_end <= start) {
 378                         path->slots[0]++;
 379                         continue;
 380                 }
 381
 382                 csum_end = min(csum_end, end + 1);
 383                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 384                                       struct btrfs_csum_item);
 385                 while (start < csum_end) {
 386                         size = min_t(size_t, csum_end - start,
 387                                      MAX_ORDERED_SUM_BYTES(root));
 388                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
 389                                        GFP_NOFS);
 390                         if (!sums) {
 391                                 ret = -ENOMEM;
 392                                 goto fail;
 393                         }
 394
 395                         sums->bytenr = start;
 396                         sums->len = (int)size;
 397
 398                         offset = (start - key.offset) >>
 399                                 root->fs_info->sb->s_blocksize_bits;
 400                         offset *= csum_size;
 401                         size >>= root->fs_info->sb->s_blocksize_bits;
 402
 403                         read_extent_buffer(path->nodes[0],
 404                                            sums->sums,
 405                                            ((unsigned long)item) + offset,
 406                                            csum_size * size);
 407
 408                         start += root->sectorsize * size;
 409                         list_add_tail(&sums->list, &tmplist);
 410                 }
 411                 path->slots[0]++;
 412         }
 413         ret = 0;
 414 fail:
 415         while (ret < 0 && !list_empty(&tmplist)) {
 416                 sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 417                 list_del(&sums->list);
 418                 kfree(sums);
 419         }
 420         list_splice_tail(&tmplist, list);
 421
 422         btrfs_free_path(path);
 423         return ret;
 424 }
 425
 426 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 427                        struct bio *bio, u64 file_start, int contig)
 428 {
 429         struct btrfs_ordered_sum *sums;
 430         struct btrfs_ordered_extent *ordered;
 431         char *data;
 432         struct bio_vec *bvec = bio->bi_io_vec;
 433         int bio_index = 0;
 434         int index;
 435         unsigned long total_bytes = 0;
 436         unsigned long this_sum_bytes = 0;
 437         u64 offset;
 438
 439         WARN_ON(bio->bi_vcnt <= 0);
 440         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_iter.bi_size),
 441                        GFP_NOFS);
 442         if (!sums)
 443                 return -ENOMEM;
 444
 445         sums->len = bio->bi_iter.bi_size;
 446         INIT_LIST_HEAD(&sums->list);
 447
 448         if (contig)
 449                 offset = file_start;
 450         else
 451                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 452
 453         ordered = btrfs_lookup_ordered_extent(inode, offset);
 454         BUG_ON(!ordered); /* Logic error */
 455         sums->bytenr = (u64)bio->bi_iter.bi_sector << 9;
 456         index = 0;
 457
 458         while (bio_index < bio->bi_vcnt) {
 459                 if (!contig)
 460                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 461
 462                 if (offset >= ordered->file_offset + ordered->len ||
 463                     offset < ordered->file_offset) {
 464                         unsigned long bytes_left;
 465                         sums->len = this_sum_bytes;
 466                         this_sum_bytes = 0;
 467                         btrfs_add_ordered_sum(inode, ordered, sums);
 468                         btrfs_put_ordered_extent(ordered);
 469
 470                         bytes_left = bio->bi_iter.bi_size - total_bytes;
 471
 472                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
 473                                        GFP_NOFS);
 474                         BUG_ON(!sums); /* -ENOMEM */
 475                         sums->len = bytes_left;
 476                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 477                         BUG_ON(!ordered); /* Logic error */
 478                         sums->bytenr = ((u64)bio->bi_iter.bi_sector << 9) +
 479                                        total_bytes;
 480                         index = 0;
 481                 }
 482
 483                 data = kmap_atomic(bvec->bv_page);
 484                 sums->sums[index] = ~(u32)0;
 485                 sums->sums[index] = btrfs_csum_data(data + bvec->bv_offset,
 486                                                     sums->sums[index],
 487                                                     bvec->bv_len);
 488                 kunmap_atomic(data);
 489                 btrfs_csum_final(sums->sums[index],
 490                                  (char *)(sums->sums + index));
 491
 492                 bio_index++;
 493                 index++;
 494                 total_bytes += bvec->bv_len;
 495                 this_sum_bytes += bvec->bv_len;
 496                 offset += bvec->bv_len;
 497                 bvec++;
 498         }
 499         this_sum_bytes = 0;
 500         btrfs_add_ordered_sum(inode, ordered, sums);
 501         btrfs_put_ordered_extent(ordered);
 502         return 0;
 503 }
 504
 505 /*
 506  * helper function for csum removal, this expects the
 507  * key to describe the csum pointed to by the path, and it expects
 508  * the csum to overlap the range [bytenr, len]
 509  *
 510  * The csum should not be entirely contained in the range and the
 511  * range should not be entirely contained in the csum.
 512  *
 513  * This calls btrfs_truncate_item with the correct args based on the
 514  * overlap, and fixes up the key as required.
 515  */
 516 static noinline void truncate_one_csum(struct btrfs_root *root,
 517                                        struct btrfs_path *path,
 518                                        struct btrfs_key *key,
 519                                        u64 bytenr, u64 len)
 520 {
 521         struct extent_buffer *leaf;
 522         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 523         u64 csum_end;
 524         u64 end_byte = bytenr + len;
 525         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 526
 527         leaf = path->nodes[0];
 528         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 529         csum_end <<= root->fs_info->sb->s_blocksize_bits;
 530         csum_end += key->offset;
 531
 532         if (key->offset < bytenr && csum_end <= end_byte) {
 533                 /*
 534                  *         [ bytenr - len ]
 535                  *         [   ]
 536                  *   [csum     ]
 537                  *   A simple truncate off the end of the item
 538                  */
 539                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 540                 new_size *= csum_size;
 541                 btrfs_truncate_item(root, path, new_size, 1);
 542         } else if (key->offset >= bytenr && csum_end > end_byte &&
 543                    end_byte > key->offset) {
 544                 /*
 545                  *         [ bytenr - len ]
 546                  *                 [ ]
 547                  *                 [csum     ]
 548                  * we need to truncate from the beginning of the csum
 549                  */
 550                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 551                 new_size *= csum_size;
 552
 553                 btrfs_truncate_item(root, path, new_size, 0);
 554
 555                 key->offset = end_byte;
 556                 btrfs_set_item_key_safe(root->fs_info, path, key);
 557         } else {
 558                 BUG();
 559         }
 560 }
 561
 562 /*
 563  * deletes the csum items from the csum tree for a given
 564  * range of bytes.
 565  */
 566 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 567                     struct btrfs_root *root, u64 bytenr, u64 len)
 568 {
 569         struct btrfs_path *path;
 570         struct btrfs_key key;
 571         u64 end_byte = bytenr + len;
 572         u64 csum_end;
 573         struct extent_buffer *leaf;
 574         int ret;
 575         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 576         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 577
 578         root = root->fs_info->csum_root;
 579
 580         path = btrfs_alloc_path();
 581         if (!path)
 582                 return -ENOMEM;
 583
 584         while (1) {
 585                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 586                 key.offset = end_byte - 1;
 587                 key.type = BTRFS_EXTENT_CSUM_KEY;
 588
 589                 path->leave_spinning = 1;
 590                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 591                 if (ret > 0) {
 592                         if (path->slots[0] == 0)
 593                                 break;
 594                         path->slots[0]--;
 595                 } else if (ret < 0) {
 596                         break;
 597                 }
 598
 599                 leaf = path->nodes[0];
 600                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 601
 602                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 603                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 604                         break;
 605                 }
 606
 607                 if (key.offset >= end_byte)
 608                         break;
 609
 610                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 611                 csum_end <<= blocksize_bits;
 612                 csum_end += key.offset;
 613
 614                 /* this csum ends before we start, we're done */
 615                 if (csum_end <= bytenr)
 616                         break;
 617
 618                 /* delete the entire item, it is inside our range */
 619                 if (key.offset >= bytenr && csum_end <= end_byte) {
 620                         ret = btrfs_del_item(trans, root, path);
 621                         if (ret)
 622                                 goto out;
 623                         if (key.offset == bytenr)
 624                                 break;
 625                 } else if (key.offset < bytenr && csum_end > end_byte) {
 626                         unsigned long offset;
 627                         unsigned long shift_len;
 628                         unsigned long item_offset;
 629                         /*
 630                          *        [ bytenr - len ]
 631                          *     [csum                ]
 632                          *
 633                          * Our bytes are in the middle of the csum,
 634                          * we need to split this item and insert a new one.
 635                          *
 636                          * But we can't drop the path because the
 637                          * csum could change, get removed, extended etc.
 638                          *
 639                          * The trick here is the max size of a csum item leaves
 640                          * enough room in the tree block for a single
 641                          * item header.  So, we split the item in place,
 642                          * adding a new header pointing to the existing
 643                          * bytes.  Then we loop around again and we have
 644                          * a nicely formed csum item that we can neatly
 645                          * truncate.
 646                          */
 647                         offset = (bytenr - key.offset) >> blocksize_bits;
 648                         offset *= csum_size;
 649
 650                         shift_len = (len >> blocksize_bits) * csum_size;
 651
 652                         item_offset = btrfs_item_ptr_offset(leaf,
 653                                                             path->slots[0]);
 654
 655                         memset_extent_buffer(leaf, 0, item_offset + offset,
 656                                              shift_len);
 657                         key.offset = bytenr;
 658
 659                         /*
 660                          * btrfs_split_item returns -EAGAIN when the
 661                          * item changed size or key
 662                          */
 663                         ret = btrfs_split_item(trans, root, path, &key, offset);
 664                         if (ret && ret != -EAGAIN) {
 665                                 btrfs_abort_transaction(trans, root, ret);
 666                                 goto out;
 667                         }
 668
 669                         key.offset = end_byte - 1;
 670                 } else {
 671                         truncate_one_csum(root, path, &key, bytenr, len);
 672                         if (key.offset < bytenr)
 673                                 break;
 674                 }
 675                 btrfs_release_path(path);
 676         }
 677         ret = 0;
 678 out:
 679         btrfs_free_path(path);
 680         return ret;
 681 }
 682
 683 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 684                            struct btrfs_root *root,
 685                            struct btrfs_ordered_sum *sums)
 686 {
 687         struct btrfs_key file_key;
 688         struct btrfs_key found_key;
 689         struct btrfs_path *path;
 690         struct btrfs_csum_item *item;
 691         struct btrfs_csum_item *item_end;
 692         struct extent_buffer *leaf = NULL;
 693         u64 next_offset;
 694         u64 total_bytes = 0;
 695         u64 csum_offset;
 696         u64 bytenr;
 697         u32 nritems;
 698         u32 ins_size;
 699         int index = 0;
 700         int found_next;
 701         int ret;
 702         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 703
 704         path = btrfs_alloc_path();
 705         if (!path)
 706                 return -ENOMEM;
 707 again:
 708         next_offset = (u64)-1;
 709         found_next = 0;
 710         bytenr = sums->bytenr + total_bytes;
 711         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 712         file_key.offset = bytenr;
 713         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 714
 715         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 716         if (!IS_ERR(item)) {
 717                 ret = 0;
 718                 leaf = path->nodes[0];
 719                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 720                                           struct btrfs_csum_item);
 721                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 722                            btrfs_item_size_nr(leaf, path->slots[0]));
 723                 goto found;
 724         }
 725         ret = PTR_ERR(item);
 726         if (ret != -EFBIG && ret != -ENOENT)
 727                 goto fail_unlock;
 728
 729         if (ret == -EFBIG) {
 730                 u32 item_size;
 731                 /* we found one, but it isn't big enough yet */
 732                 leaf = path->nodes[0];
 733                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 734                 if ((item_size / csum_size) >=
 735                     MAX_CSUM_ITEMS(root, csum_size)) {
 736                         /* already at max size, make a new one */
 737                         goto insert;
 738                 }
 739         } else {
 740                 int slot = path->slots[0] + 1;
 741                 /* we didn't find a csum item, insert one */
 742                 nritems = btrfs_header_nritems(path->nodes[0]);
 743                 if (!nritems || (path->slots[0] >= nritems - 1)) {
 744                         ret = btrfs_next_leaf(root, path);
 745                         if (ret == 1)
 746                                 found_next = 1;
 747                         if (ret != 0)
 748                                 goto insert;
 749                         slot = path->slots[0];
 750                 }
 751                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 752                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 753                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 754                         found_next = 1;
 755                         goto insert;
 756                 }
 757                 next_offset = found_key.offset;
 758                 found_next = 1;
 759                 goto insert;
 760         }
 761
 762         /*
 763          * at this point, we know the tree has an item, but it isn't big
 764          * enough yet to put our csum in.  Grow it
 765          */
 766         btrfs_release_path(path);
 767         ret = btrfs_search_slot(trans, root, &file_key, path,
 768                                 csum_size, 1);
 769         if (ret < 0)
 770                 goto fail_unlock;
 771
 772         if (ret > 0) {
 773                 if (path->slots[0] == 0)
 774                         goto insert;
 775                 path->slots[0]--;
 776         }
 777
 778         leaf = path->nodes[0];
 779         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 780         csum_offset = (bytenr - found_key.offset) >>
 781                         root->fs_info->sb->s_blocksize_bits;
 782
 783         if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
 784             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 785             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
 786                 goto insert;
 787         }
 788
 789         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 790             csum_size) {
 791                 int extend_nr;
 792                 u64 tmp;
 793                 u32 diff;
 794                 u32 free_space;
 795
 796                 if (btrfs_leaf_free_space(root, leaf) <
 797                                  sizeof(struct btrfs_item) + csum_size * 2)
 798                         goto insert;
 799
 800                 free_space = btrfs_leaf_free_space(root, leaf) -
 801                                          sizeof(struct btrfs_item) - csum_size;
 802                 tmp = sums->len - total_bytes;
 803                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 804                 WARN_ON(tmp < 1);
 805
 806                 extend_nr = max_t(int, 1, (int)tmp);
 807                 diff = (csum_offset + extend_nr) * csum_size;
 808                 diff = min(diff, MAX_CSUM_ITEMS(root, csum_size) * csum_size);
 809
 810                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 811                 diff = min(free_space, diff);
 812                 diff /= csum_size;
 813                 diff *= csum_size;
 814
 815                 btrfs_extend_item(root, path, diff);
 816                 ret = 0;
 817                 goto csum;
 818         }
 819
 820 insert:
 821         btrfs_release_path(path);
 822         csum_offset = 0;
 823         if (found_next) {
 824                 u64 tmp;
 825
 826                 tmp = sums->len - total_bytes;
 827                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 828                 tmp = min(tmp, (next_offset - file_key.offset) >>
 829                                          root->fs_info->sb->s_blocksize_bits);
 830
 831                 tmp = max((u64)1, tmp);
 832                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
 833                 ins_size = csum_size * tmp;
 834         } else {
 835                 ins_size = csum_size;
 836         }
 837         path->leave_spinning = 1;
 838         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 839                                       ins_size);
 840         path->leave_spinning = 0;
 841         if (ret < 0)
 842                 goto fail_unlock;
 843         if (WARN_ON(ret != 0))
 844                 goto fail_unlock;
 845         leaf = path->nodes[0];
 846 csum:
 847         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 848         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 849                                       btrfs_item_size_nr(leaf, path->slots[0]));
 850         item = (struct btrfs_csum_item *)((unsigned char *)item +
 851                                           csum_offset * csum_size);
 852 found:
 853         ins_size = (u32)(sums->len - total_bytes) >>
 854                    root->fs_info->sb->s_blocksize_bits;
 855         ins_size *= csum_size;
 856         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 857                               ins_size);
 858         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 859                             ins_size);
 860
 861         ins_size /= csum_size;
 862         total_bytes += ins_size * root->sectorsize;
 863         index += ins_size;
 864
 865         btrfs_mark_buffer_dirty(path->nodes[0]);
 866         if (total_bytes < sums->len) {
 867                 btrfs_release_path(path);
 868                 cond_resched();
 869                 goto again;
 870         }
 871 out:
 872         btrfs_free_path(path);
 873         return ret;
 874
 875 fail_unlock:
 876         goto out;
 877 }
 878
 879 void btrfs_extent_item_to_extent_map(struct inode *inode,
 880                                      const struct btrfs_path *path,
 881                                      struct btrfs_file_extent_item *fi,
 882                                      const bool new_inline,
 883                                      struct extent_map *em)
 884 {
 885         struct btrfs_root *root = BTRFS_I(inode)->root;
 886         struct extent_buffer *leaf = path->nodes[0];
 887         const int slot = path->slots[0];
 888         struct btrfs_key key;
 889         u64 extent_start, extent_end;
 890         u64 bytenr;
 891         u8 type = btrfs_file_extent_type(leaf, fi);
 892         int compress_type = btrfs_file_extent_compression(leaf, fi);
 893
 894         em->bdev = root->fs_info->fs_devices->latest_bdev;
 895         btrfs_item_key_to_cpu(leaf, &key, slot);
 896         extent_start = key.offset;
 897
 898         if (type == BTRFS_FILE_EXTENT_REG ||
 899             type == BTRFS_FILE_EXTENT_PREALLOC) {
 900                 extent_end = extent_start +
 901                         btrfs_file_extent_num_bytes(leaf, fi);
 902         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 903                 size_t size;
 904                 size = btrfs_file_extent_inline_len(leaf, slot, fi);
 905                 extent_end = ALIGN(extent_start + size, root->sectorsize);
 906         }
 907
 908         em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
 909         if (type == BTRFS_FILE_EXTENT_REG ||
 910             type == BTRFS_FILE_EXTENT_PREALLOC) {
 911                 em->start = extent_start;
 912                 em->len = extent_end - extent_start;
 913                 em->orig_start = extent_start -
 914                         btrfs_file_extent_offset(leaf, fi);
 915                 em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
 916                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 917                 if (bytenr == 0) {
 918                         em->block_start = EXTENT_MAP_HOLE;
 919                         return;
 920                 }
 921                 if (compress_type != BTRFS_COMPRESS_NONE) {
 922                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 923                         em->compress_type = compress_type;
 924                         em->block_start = bytenr;
 925                         em->block_len = em->orig_block_len;
 926                 } else {
 927                         bytenr += btrfs_file_extent_offset(leaf, fi);
 928                         em->block_start = bytenr;
 929                         em->block_len = em->len;
 930                         if (type == BTRFS_FILE_EXTENT_PREALLOC)
 931                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
 932                 }
 933         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 934                 em->block_start = EXTENT_MAP_INLINE;
 935                 em->start = extent_start;
 936                 em->len = extent_end - extent_start;
 937                 /*
 938                  * Initialize orig_start and block_len with the same values
 939                  * as in inode.c:btrfs_get_extent().
 940                  */
 941                 em->orig_start = EXTENT_MAP_HOLE;
 942                 em->block_len = (u64)-1;
 943                 if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
 944                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 945                         em->compress_type = compress_type;
 946                 }
 947         } else {
 948                 btrfs_err(root->fs_info,
 949                           "unknown file extent item type %d, inode %llu, offset %llu, root %llu",
 950                           type, btrfs_ino(inode), extent_start,
 951                           root->root_key.objectid);
 952         }
 953 }