fs/btrfs/file-item.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/bio.h>
   7 #include <linux/slab.h>
   8 #include <linux/pagemap.h>
   9 #include <linux/highmem.h>
  10 #include <linux/sched/mm.h>
  11 #include "ctree.h"
  12 #include "disk-io.h"
  13 #include "transaction.h"
  14 #include "volumes.h"
  15 #include "print-tree.h"
  16 #include "compression.h"
  17
  18 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  19                                    sizeof(struct btrfs_item) * 2) / \
  20                                   size) - 1))
  21
  22 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  23                                        PAGE_SIZE))
  24
  25 #define MAX_ORDERED_SUM_BYTES(fs_info) ((PAGE_SIZE - \
  26                                    sizeof(struct btrfs_ordered_sum)) / \
  27                                    sizeof(u32) * (fs_info)->sectorsize)
  28
  29 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  30                              struct btrfs_root *root,
  31                              u64 objectid, u64 pos,
  32                              u64 disk_offset, u64 disk_num_bytes,
  33                              u64 num_bytes, u64 offset, u64 ram_bytes,
  34                              u8 compression, u8 encryption, u16 other_encoding)
  35 {
  36         int ret = 0;
  37         struct btrfs_file_extent_item *item;
  38         struct btrfs_key file_key;
  39         struct btrfs_path *path;
  40         struct extent_buffer *leaf;
  41
  42         path = btrfs_alloc_path();
  43         if (!path)
  44                 return -ENOMEM;
  45         file_key.objectid = objectid;
  46         file_key.offset = pos;
  47         file_key.type = BTRFS_EXTENT_DATA_KEY;
  48
  49         path->leave_spinning = 1;
  50         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  51                                       sizeof(*item));
  52         if (ret < 0)
  53                 goto out;
  54         BUG_ON(ret); /* Can't happen */
  55         leaf = path->nodes[0];
  56         item = btrfs_item_ptr(leaf, path->slots[0],
  57                               struct btrfs_file_extent_item);
  58         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
  59         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  60         btrfs_set_file_extent_offset(leaf, item, offset);
  61         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  62         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
  63         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  64         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  65         btrfs_set_file_extent_compression(leaf, item, compression);
  66         btrfs_set_file_extent_encryption(leaf, item, encryption);
  67         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
  68
  69         btrfs_mark_buffer_dirty(leaf);
  70 out:
  71         btrfs_free_path(path);
  72         return ret;
  73 }
  74
  75 static struct btrfs_csum_item *
  76 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  77                   struct btrfs_root *root,
  78                   struct btrfs_path *path,
  79                   u64 bytenr, int cow)
  80 {
  81         struct btrfs_fs_info *fs_info = root->fs_info;
  82         int ret;
  83         struct btrfs_key file_key;
  84         struct btrfs_key found_key;
  85         struct btrfs_csum_item *item;
  86         struct extent_buffer *leaf;
  87         u64 csum_offset = 0;
  88         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
  89         int csums_in_item;
  90
  91         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
  92         file_key.offset = bytenr;
  93         file_key.type = BTRFS_EXTENT_CSUM_KEY;
  94         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
  95         if (ret < 0)
  96                 goto fail;
  97         leaf = path->nodes[0];
  98         if (ret > 0) {
  99                 ret = 1;
 100                 if (path->slots[0] == 0)
 101                         goto fail;
 102                 path->slots[0]--;
 103                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 104                 if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 105                         goto fail;
 106
 107                 csum_offset = (bytenr - found_key.offset) >>
 108                                 fs_info->sb->s_blocksize_bits;
 109                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
 110                 csums_in_item /= csum_size;
 111
 112                 if (csum_offset == csums_in_item) {
 113                         ret = -EFBIG;
 114                         goto fail;
 115                 } else if (csum_offset > csums_in_item) {
 116                         goto fail;
 117                 }
 118         }
 119         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 120         item = (struct btrfs_csum_item *)((unsigned char *)item +
 121                                           csum_offset * csum_size);
 122         return item;
 123 fail:
 124         if (ret > 0)
 125                 ret = -ENOENT;
 126         return ERR_PTR(ret);
 127 }
 128
 129 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 130                              struct btrfs_root *root,
 131                              struct btrfs_path *path, u64 objectid,
 132                              u64 offset, int mod)
 133 {
 134         int ret;
 135         struct btrfs_key file_key;
 136         int ins_len = mod < 0 ? -1 : 0;
 137         int cow = mod != 0;
 138
 139         file_key.objectid = objectid;
 140         file_key.offset = offset;
 141         file_key.type = BTRFS_EXTENT_DATA_KEY;
 142         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 143         return ret;
 144 }
 145
 146 static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
 147                                    u64 logical_offset, u32 *dst, int dio)
 148 {
 149         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 150         struct bio_vec bvec;
 151         struct bvec_iter iter;
 152         struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
 153         struct btrfs_csum_item *item = NULL;
 154         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 155         struct btrfs_path *path;
 156         u8 *csum;
 157         u64 offset = 0;
 158         u64 item_start_offset = 0;
 159         u64 item_last_offset = 0;
 160         u64 disk_bytenr;
 161         u64 page_bytes_left;
 162         u32 diff;
 163         int nblocks;
 164         int count = 0;
 165         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 166
 167         path = btrfs_alloc_path();
 168         if (!path)
 169                 return BLK_STS_RESOURCE;
 170
 171         nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
 172         if (!dst) {
 173                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 174                         btrfs_bio->csum = kmalloc_array(nblocks, csum_size,
 175                                                         GFP_NOFS);
 176                         if (!btrfs_bio->csum) {
 177                                 btrfs_free_path(path);
 178                                 return BLK_STS_RESOURCE;
 179                         }
 180                 } else {
 181                         btrfs_bio->csum = btrfs_bio->csum_inline;
 182                 }
 183                 csum = btrfs_bio->csum;
 184         } else {
 185                 csum = (u8 *)dst;
 186         }
 187
 188         if (bio->bi_iter.bi_size > PAGE_SIZE * 8)
 189                 path->reada = READA_FORWARD;
 190
 191         /*
 192          * the free space stuff is only read when it hasn't been
 193          * updated in the current transaction.  So, we can safely
 194          * read from the commit root and sidestep a nasty deadlock
 195          * between reading the free space cache and updating the csum tree.
 196          */
 197         if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
 198                 path->search_commit_root = 1;
 199                 path->skip_locking = 1;
 200         }
 201
 202         disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
 203         if (dio)
 204                 offset = logical_offset;
 205
 206         bio_for_each_segment(bvec, bio, iter) {
 207                 page_bytes_left = bvec.bv_len;
 208                 if (count)
 209                         goto next;
 210
 211                 if (!dio)
 212                         offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 213                 count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 214                                                (u32 *)csum, nblocks);
 215                 if (count)
 216                         goto found;
 217
 218                 if (!item || disk_bytenr < item_start_offset ||
 219                     disk_bytenr >= item_last_offset) {
 220                         struct btrfs_key found_key;
 221                         u32 item_size;
 222
 223                         if (item)
 224                                 btrfs_release_path(path);
 225                         item = btrfs_lookup_csum(NULL, fs_info->csum_root,
 226                                                  path, disk_bytenr, 0);
 227                         if (IS_ERR(item)) {
 228                                 count = 1;
 229                                 memset(csum, 0, csum_size);
 230                                 if (BTRFS_I(inode)->root->root_key.objectid ==
 231                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
 232                                         set_extent_bits(io_tree, offset,
 233                                                 offset + fs_info->sectorsize - 1,
 234                                                 EXTENT_NODATASUM);
 235                                 } else {
 236                                         btrfs_info_rl(fs_info,
 237                                                    "no csum found for inode %llu start %llu",
 238                                                btrfs_ino(BTRFS_I(inode)), offset);
 239                                 }
 240                                 item = NULL;
 241                                 btrfs_release_path(path);
 242                                 goto found;
 243                         }
 244                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 245                                               path->slots[0]);
 246
 247                         item_start_offset = found_key.offset;
 248                         item_size = btrfs_item_size_nr(path->nodes[0],
 249                                                        path->slots[0]);
 250                         item_last_offset = item_start_offset +
 251                                 (item_size / csum_size) *
 252                                 fs_info->sectorsize;
 253                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 254                                               struct btrfs_csum_item);
 255                 }
 256                 /*
 257                  * this byte range must be able to fit inside
 258                  * a single leaf so it will also fit inside a u32
 259                  */
 260                 diff = disk_bytenr - item_start_offset;
 261                 diff = diff / fs_info->sectorsize;
 262                 diff = diff * csum_size;
 263                 count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
 264                                             inode->i_sb->s_blocksize_bits);
 265                 read_extent_buffer(path->nodes[0], csum,
 266                                    ((unsigned long)item) + diff,
 267                                    csum_size * count);
 268 found:
 269                 csum += count * csum_size;
 270                 nblocks -= count;
 271 next:
 272                 while (count--) {
 273                         disk_bytenr += fs_info->sectorsize;
 274                         offset += fs_info->sectorsize;
 275                         page_bytes_left -= fs_info->sectorsize;
 276                         if (!page_bytes_left)
 277                                 break; /* move to next bio */
 278                 }
 279         }
 280
 281         WARN_ON_ONCE(count);
 282         btrfs_free_path(path);
 283         return 0;
 284 }
 285
 286 blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u32 *dst)
 287 {
 288         return __btrfs_lookup_bio_sums(inode, bio, 0, dst, 0);
 289 }
 290
 291 blk_status_t btrfs_lookup_bio_sums_dio(struct inode *inode, struct bio *bio, u64 offset)
 292 {
 293         return __btrfs_lookup_bio_sums(inode, bio, offset, NULL, 1);
 294 }
 295
 296 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 297                              struct list_head *list, int search_commit)
 298 {
 299         struct btrfs_fs_info *fs_info = root->fs_info;
 300         struct btrfs_key key;
 301         struct btrfs_path *path;
 302         struct extent_buffer *leaf;
 303         struct btrfs_ordered_sum *sums;
 304         struct btrfs_csum_item *item;
 305         LIST_HEAD(tmplist);
 306         unsigned long offset;
 307         int ret;
 308         size_t size;
 309         u64 csum_end;
 310         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 311
 312         ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 313                IS_ALIGNED(end + 1, fs_info->sectorsize));
 314
 315         path = btrfs_alloc_path();
 316         if (!path)
 317                 return -ENOMEM;
 318
 319         if (search_commit) {
 320                 path->skip_locking = 1;
 321                 path->reada = READA_FORWARD;
 322                 path->search_commit_root = 1;
 323         }
 324
 325         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 326         key.offset = start;
 327         key.type = BTRFS_EXTENT_CSUM_KEY;
 328
 329         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 330         if (ret < 0)
 331                 goto fail;
 332         if (ret > 0 && path->slots[0] > 0) {
 333                 leaf = path->nodes[0];
 334                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 335                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 336                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 337                         offset = (start - key.offset) >>
 338                                  fs_info->sb->s_blocksize_bits;
 339                         if (offset * csum_size <
 340                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
 341                                 path->slots[0]--;
 342                 }
 343         }
 344
 345         while (start <= end) {
 346                 leaf = path->nodes[0];
 347                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 348                         ret = btrfs_next_leaf(root, path);
 349                         if (ret < 0)
 350                                 goto fail;
 351                         if (ret > 0)
 352                                 break;
 353                         leaf = path->nodes[0];
 354                 }
 355
 356                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 357                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 358                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 359                     key.offset > end)
 360                         break;
 361
 362                 if (key.offset > start)
 363                         start = key.offset;
 364
 365                 size = btrfs_item_size_nr(leaf, path->slots[0]);
 366                 csum_end = key.offset + (size / csum_size) * fs_info->sectorsize;
 367                 if (csum_end <= start) {
 368                         path->slots[0]++;
 369                         continue;
 370                 }
 371
 372                 csum_end = min(csum_end, end + 1);
 373                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 374                                       struct btrfs_csum_item);
 375                 while (start < csum_end) {
 376                         size = min_t(size_t, csum_end - start,
 377                                      MAX_ORDERED_SUM_BYTES(fs_info));
 378                         sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
 379                                        GFP_NOFS);
 380                         if (!sums) {
 381                                 ret = -ENOMEM;
 382                                 goto fail;
 383                         }
 384
 385                         sums->bytenr = start;
 386                         sums->len = (int)size;
 387
 388                         offset = (start - key.offset) >>
 389                                 fs_info->sb->s_blocksize_bits;
 390                         offset *= csum_size;
 391                         size >>= fs_info->sb->s_blocksize_bits;
 392
 393                         read_extent_buffer(path->nodes[0],
 394                                            sums->sums,
 395                                            ((unsigned long)item) + offset,
 396                                            csum_size * size);
 397
 398                         start += fs_info->sectorsize * size;
 399                         list_add_tail(&sums->list, &tmplist);
 400                 }
 401                 path->slots[0]++;
 402         }
 403         ret = 0;
 404 fail:
 405         while (ret < 0 && !list_empty(&tmplist)) {
 406                 sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 407                 list_del(&sums->list);
 408                 kfree(sums);
 409         }
 410         list_splice_tail(&tmplist, list);
 411
 412         btrfs_free_path(path);
 413         return ret;
 414 }
 415
 416 blk_status_t btrfs_csum_one_bio(struct inode *inode, struct bio *bio,
 417                        u64 file_start, int contig)
 418 {
 419         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 420         struct btrfs_ordered_sum *sums;
 421         struct btrfs_ordered_extent *ordered = NULL;
 422         char *data;
 423         struct bvec_iter iter;
 424         struct bio_vec bvec;
 425         int index;
 426         int nr_sectors;
 427         unsigned long total_bytes = 0;
 428         unsigned long this_sum_bytes = 0;
 429         int i;
 430         u64 offset;
 431         unsigned nofs_flag;
 432
 433         nofs_flag = memalloc_nofs_save();
 434         sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
 435                        GFP_KERNEL);
 436         memalloc_nofs_restore(nofs_flag);
 437
 438         if (!sums)
 439                 return BLK_STS_RESOURCE;
 440
 441         sums->len = bio->bi_iter.bi_size;
 442         INIT_LIST_HEAD(&sums->list);
 443
 444         if (contig)
 445                 offset = file_start;
 446         else
 447                 offset = 0; /* shut up gcc */
 448
 449         sums->bytenr = (u64)bio->bi_iter.bi_sector << 9;
 450         index = 0;
 451
 452         bio_for_each_segment(bvec, bio, iter) {
 453                 if (!contig)
 454                         offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 455
 456                 if (!ordered) {
 457                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 458                         BUG_ON(!ordered); /* Logic error */
 459                 }
 460
 461                 nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info,
 462                                                  bvec.bv_len + fs_info->sectorsize
 463                                                  - 1);
 464
 465                 for (i = 0; i < nr_sectors; i++) {
 466                         if (offset >= ordered->file_offset + ordered->len ||
 467                                 offset < ordered->file_offset) {
 468                                 unsigned long bytes_left;
 469
 470                                 sums->len = this_sum_bytes;
 471                                 this_sum_bytes = 0;
 472                                 btrfs_add_ordered_sum(inode, ordered, sums);
 473                                 btrfs_put_ordered_extent(ordered);
 474
 475                                 bytes_left = bio->bi_iter.bi_size - total_bytes;
 476
 477                                 nofs_flag = memalloc_nofs_save();
 478                                 sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
 479                                                       bytes_left), GFP_KERNEL);
 480                                 memalloc_nofs_restore(nofs_flag);
 481                                 BUG_ON(!sums); /* -ENOMEM */
 482                                 sums->len = bytes_left;
 483                                 ordered = btrfs_lookup_ordered_extent(inode,
 484                                                                 offset);
 485                                 ASSERT(ordered); /* Logic error */
 486                                 sums->bytenr = ((u64)bio->bi_iter.bi_sector << 9)
 487                                         + total_bytes;
 488                                 index = 0;
 489                         }
 490
 491                         sums->sums[index] = ~(u32)0;
 492                         data = kmap_atomic(bvec.bv_page);
 493                         sums->sums[index]
 494                                 = btrfs_csum_data(data + bvec.bv_offset
 495                                                 + (i * fs_info->sectorsize),
 496                                                 sums->sums[index],
 497                                                 fs_info->sectorsize);
 498                         kunmap_atomic(data);
 499                         btrfs_csum_final(sums->sums[index],
 500                                         (char *)(sums->sums + index));
 501                         index++;
 502                         offset += fs_info->sectorsize;
 503                         this_sum_bytes += fs_info->sectorsize;
 504                         total_bytes += fs_info->sectorsize;
 505                 }
 506
 507         }
 508         this_sum_bytes = 0;
 509         btrfs_add_ordered_sum(inode, ordered, sums);
 510         btrfs_put_ordered_extent(ordered);
 511         return 0;
 512 }
 513
 514 /*
 515  * helper function for csum removal, this expects the
 516  * key to describe the csum pointed to by the path, and it expects
 517  * the csum to overlap the range [bytenr, len]
 518  *
 519  * The csum should not be entirely contained in the range and the
 520  * range should not be entirely contained in the csum.
 521  *
 522  * This calls btrfs_truncate_item with the correct args based on the
 523  * overlap, and fixes up the key as required.
 524  */
 525 static noinline void truncate_one_csum(struct btrfs_fs_info *fs_info,
 526                                        struct btrfs_path *path,
 527                                        struct btrfs_key *key,
 528                                        u64 bytenr, u64 len)
 529 {
 530         struct extent_buffer *leaf;
 531         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 532         u64 csum_end;
 533         u64 end_byte = bytenr + len;
 534         u32 blocksize_bits = fs_info->sb->s_blocksize_bits;
 535
 536         leaf = path->nodes[0];
 537         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 538         csum_end <<= fs_info->sb->s_blocksize_bits;
 539         csum_end += key->offset;
 540
 541         if (key->offset < bytenr && csum_end <= end_byte) {
 542                 /*
 543                  *         [ bytenr - len ]
 544                  *         [   ]
 545                  *   [csum     ]
 546                  *   A simple truncate off the end of the item
 547                  */
 548                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 549                 new_size *= csum_size;
 550                 btrfs_truncate_item(fs_info, path, new_size, 1);
 551         } else if (key->offset >= bytenr && csum_end > end_byte &&
 552                    end_byte > key->offset) {
 553                 /*
 554                  *         [ bytenr - len ]
 555                  *                 [ ]
 556                  *                 [csum     ]
 557                  * we need to truncate from the beginning of the csum
 558                  */
 559                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 560                 new_size *= csum_size;
 561
 562                 btrfs_truncate_item(fs_info, path, new_size, 0);
 563
 564                 key->offset = end_byte;
 565                 btrfs_set_item_key_safe(fs_info, path, key);
 566         } else {
 567                 BUG();
 568         }
 569 }
 570
 571 /*
 572  * deletes the csum items from the csum tree for a given
 573  * range of bytes.
 574  */
 575 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 576                     struct btrfs_fs_info *fs_info, u64 bytenr, u64 len)
 577 {
 578         struct btrfs_root *root = fs_info->csum_root;
 579         struct btrfs_path *path;
 580         struct btrfs_key key;
 581         u64 end_byte = bytenr + len;
 582         u64 csum_end;
 583         struct extent_buffer *leaf;
 584         int ret;
 585         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 586         int blocksize_bits = fs_info->sb->s_blocksize_bits;
 587
 588         path = btrfs_alloc_path();
 589         if (!path)
 590                 return -ENOMEM;
 591
 592         while (1) {
 593                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 594                 key.offset = end_byte - 1;
 595                 key.type = BTRFS_EXTENT_CSUM_KEY;
 596
 597                 path->leave_spinning = 1;
 598                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 599                 if (ret > 0) {
 600                         if (path->slots[0] == 0)
 601                                 break;
 602                         path->slots[0]--;
 603                 } else if (ret < 0) {
 604                         break;
 605                 }
 606
 607                 leaf = path->nodes[0];
 608                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 609
 610                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 611                     key.type != BTRFS_EXTENT_CSUM_KEY) {
 612                         break;
 613                 }
 614
 615                 if (key.offset >= end_byte)
 616                         break;
 617
 618                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
 619                 csum_end <<= blocksize_bits;
 620                 csum_end += key.offset;
 621
 622                 /* this csum ends before we start, we're done */
 623                 if (csum_end <= bytenr)
 624                         break;
 625
 626                 /* delete the entire item, it is inside our range */
 627                 if (key.offset >= bytenr && csum_end <= end_byte) {
 628                         int del_nr = 1;
 629
 630                         /*
 631                          * Check how many csum items preceding this one in this
 632                          * leaf correspond to our range and then delete them all
 633                          * at once.
 634                          */
 635                         if (key.offset > bytenr && path->slots[0] > 0) {
 636                                 int slot = path->slots[0] - 1;
 637
 638                                 while (slot >= 0) {
 639                                         struct btrfs_key pk;
 640
 641                                         btrfs_item_key_to_cpu(leaf, &pk, slot);
 642                                         if (pk.offset < bytenr ||
 643                                             pk.type != BTRFS_EXTENT_CSUM_KEY ||
 644                                             pk.objectid !=
 645                                             BTRFS_EXTENT_CSUM_OBJECTID)
 646                                                 break;
 647                                         path->slots[0] = slot;
 648                                         del_nr++;
 649                                         key.offset = pk.offset;
 650                                         slot--;
 651                                 }
 652                         }
 653                         ret = btrfs_del_items(trans, root, path,
 654                                               path->slots[0], del_nr);
 655                         if (ret)
 656                                 goto out;
 657                         if (key.offset == bytenr)
 658                                 break;
 659                 } else if (key.offset < bytenr && csum_end > end_byte) {
 660                         unsigned long offset;
 661                         unsigned long shift_len;
 662                         unsigned long item_offset;
 663                         /*
 664                          *        [ bytenr - len ]
 665                          *     [csum                ]
 666                          *
 667                          * Our bytes are in the middle of the csum,
 668                          * we need to split this item and insert a new one.
 669                          *
 670                          * But we can't drop the path because the
 671                          * csum could change, get removed, extended etc.
 672                          *
 673                          * The trick here is the max size of a csum item leaves
 674                          * enough room in the tree block for a single
 675                          * item header.  So, we split the item in place,
 676                          * adding a new header pointing to the existing
 677                          * bytes.  Then we loop around again and we have
 678                          * a nicely formed csum item that we can neatly
 679                          * truncate.
 680                          */
 681                         offset = (bytenr - key.offset) >> blocksize_bits;
 682                         offset *= csum_size;
 683
 684                         shift_len = (len >> blocksize_bits) * csum_size;
 685
 686                         item_offset = btrfs_item_ptr_offset(leaf,
 687                                                             path->slots[0]);
 688
 689                         memzero_extent_buffer(leaf, item_offset + offset,
 690                                              shift_len);
 691                         key.offset = bytenr;
 692
 693                         /*
 694                          * btrfs_split_item returns -EAGAIN when the
 695                          * item changed size or key
 696                          */
 697                         ret = btrfs_split_item(trans, root, path, &key, offset);
 698                         if (ret && ret != -EAGAIN) {
 699                                 btrfs_abort_transaction(trans, ret);
 700                                 goto out;
 701                         }
 702
 703                         key.offset = end_byte - 1;
 704                 } else {
 705                         truncate_one_csum(fs_info, path, &key, bytenr, len);
 706                         if (key.offset < bytenr)
 707                                 break;
 708                 }
 709                 btrfs_release_path(path);
 710         }
 711         ret = 0;
 712 out:
 713         btrfs_free_path(path);
 714         return ret;
 715 }
 716
 717 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 718                            struct btrfs_root *root,
 719                            struct btrfs_ordered_sum *sums)
 720 {
 721         struct btrfs_fs_info *fs_info = root->fs_info;
 722         struct btrfs_key file_key;
 723         struct btrfs_key found_key;
 724         struct btrfs_path *path;
 725         struct btrfs_csum_item *item;
 726         struct btrfs_csum_item *item_end;
 727         struct extent_buffer *leaf = NULL;
 728         u64 next_offset;
 729         u64 total_bytes = 0;
 730         u64 csum_offset;
 731         u64 bytenr;
 732         u32 nritems;
 733         u32 ins_size;
 734         int index = 0;
 735         int found_next;
 736         int ret;
 737         u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
 738
 739         path = btrfs_alloc_path();
 740         if (!path)
 741                 return -ENOMEM;
 742 again:
 743         next_offset = (u64)-1;
 744         found_next = 0;
 745         bytenr = sums->bytenr + total_bytes;
 746         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 747         file_key.offset = bytenr;
 748         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 749
 750         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
 751         if (!IS_ERR(item)) {
 752                 ret = 0;
 753                 leaf = path->nodes[0];
 754                 item_end = btrfs_item_ptr(leaf, path->slots[0],
 755                                           struct btrfs_csum_item);
 756                 item_end = (struct btrfs_csum_item *)((char *)item_end +
 757                            btrfs_item_size_nr(leaf, path->slots[0]));
 758                 goto found;
 759         }
 760         ret = PTR_ERR(item);
 761         if (ret != -EFBIG && ret != -ENOENT)
 762                 goto fail_unlock;
 763
 764         if (ret == -EFBIG) {
 765                 u32 item_size;
 766                 /* we found one, but it isn't big enough yet */
 767                 leaf = path->nodes[0];
 768                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 769                 if ((item_size / csum_size) >=
 770                     MAX_CSUM_ITEMS(fs_info, csum_size)) {
 771                         /* already at max size, make a new one */
 772                         goto insert;
 773                 }
 774         } else {
 775                 int slot = path->slots[0] + 1;
 776                 /* we didn't find a csum item, insert one */
 777                 nritems = btrfs_header_nritems(path->nodes[0]);
 778                 if (!nritems || (path->slots[0] >= nritems - 1)) {
 779                         ret = btrfs_next_leaf(root, path);
 780                         if (ret == 1)
 781                                 found_next = 1;
 782                         if (ret != 0)
 783                                 goto insert;
 784                         slot = path->slots[0];
 785                 }
 786                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 787                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 788                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
 789                         found_next = 1;
 790                         goto insert;
 791                 }
 792                 next_offset = found_key.offset;
 793                 found_next = 1;
 794                 goto insert;
 795         }
 796
 797         /*
 798          * at this point, we know the tree has an item, but it isn't big
 799          * enough yet to put our csum in.  Grow it
 800          */
 801         btrfs_release_path(path);
 802         ret = btrfs_search_slot(trans, root, &file_key, path,
 803                                 csum_size, 1);
 804         if (ret < 0)
 805                 goto fail_unlock;
 806
 807         if (ret > 0) {
 808                 if (path->slots[0] == 0)
 809                         goto insert;
 810                 path->slots[0]--;
 811         }
 812
 813         leaf = path->nodes[0];
 814         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 815         csum_offset = (bytenr - found_key.offset) >>
 816                         fs_info->sb->s_blocksize_bits;
 817
 818         if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
 819             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 820             csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
 821                 goto insert;
 822         }
 823
 824         if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
 825             csum_size) {
 826                 int extend_nr;
 827                 u64 tmp;
 828                 u32 diff;
 829                 u32 free_space;
 830
 831                 if (btrfs_leaf_free_space(leaf) <
 832                                  sizeof(struct btrfs_item) + csum_size * 2)
 833                         goto insert;
 834
 835                 free_space = btrfs_leaf_free_space(leaf) -
 836                                          sizeof(struct btrfs_item) - csum_size;
 837                 tmp = sums->len - total_bytes;
 838                 tmp >>= fs_info->sb->s_blocksize_bits;
 839                 WARN_ON(tmp < 1);
 840
 841                 extend_nr = max_t(int, 1, (int)tmp);
 842                 diff = (csum_offset + extend_nr) * csum_size;
 843                 diff = min(diff,
 844                            MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
 845
 846                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 847                 diff = min(free_space, diff);
 848                 diff /= csum_size;
 849                 diff *= csum_size;
 850
 851                 btrfs_extend_item(fs_info, path, diff);
 852                 ret = 0;
 853                 goto csum;
 854         }
 855
 856 insert:
 857         btrfs_release_path(path);
 858         csum_offset = 0;
 859         if (found_next) {
 860                 u64 tmp;
 861
 862                 tmp = sums->len - total_bytes;
 863                 tmp >>= fs_info->sb->s_blocksize_bits;
 864                 tmp = min(tmp, (next_offset - file_key.offset) >>
 865                                          fs_info->sb->s_blocksize_bits);
 866
 867                 tmp = max_t(u64, 1, tmp);
 868                 tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
 869                 ins_size = csum_size * tmp;
 870         } else {
 871                 ins_size = csum_size;
 872         }
 873         path->leave_spinning = 1;
 874         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 875                                       ins_size);
 876         path->leave_spinning = 0;
 877         if (ret < 0)
 878                 goto fail_unlock;
 879         if (WARN_ON(ret != 0))
 880                 goto fail_unlock;
 881         leaf = path->nodes[0];
 882 csum:
 883         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 884         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
 885                                       btrfs_item_size_nr(leaf, path->slots[0]));
 886         item = (struct btrfs_csum_item *)((unsigned char *)item +
 887                                           csum_offset * csum_size);
 888 found:
 889         ins_size = (u32)(sums->len - total_bytes) >>
 890                    fs_info->sb->s_blocksize_bits;
 891         ins_size *= csum_size;
 892         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
 893                               ins_size);
 894         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
 895                             ins_size);
 896
 897         ins_size /= csum_size;
 898         total_bytes += ins_size * fs_info->sectorsize;
 899         index += ins_size;
 900
 901         btrfs_mark_buffer_dirty(path->nodes[0]);
 902         if (total_bytes < sums->len) {
 903                 btrfs_release_path(path);
 904                 cond_resched();
 905                 goto again;
 906         }
 907 out:
 908         btrfs_free_path(path);
 909         return ret;
 910
 911 fail_unlock:
 912         goto out;
 913 }
 914
 915 void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
 916                                      const struct btrfs_path *path,
 917                                      struct btrfs_file_extent_item *fi,
 918                                      const bool new_inline,
 919                                      struct extent_map *em)
 920 {
 921         struct btrfs_fs_info *fs_info = inode->root->fs_info;
 922         struct btrfs_root *root = inode->root;
 923         struct extent_buffer *leaf = path->nodes[0];
 924         const int slot = path->slots[0];
 925         struct btrfs_key key;
 926         u64 extent_start, extent_end;
 927         u64 bytenr;
 928         u8 type = btrfs_file_extent_type(leaf, fi);
 929         int compress_type = btrfs_file_extent_compression(leaf, fi);
 930
 931         em->bdev = fs_info->fs_devices->latest_bdev;
 932         btrfs_item_key_to_cpu(leaf, &key, slot);
 933         extent_start = key.offset;
 934
 935         if (type == BTRFS_FILE_EXTENT_REG ||
 936             type == BTRFS_FILE_EXTENT_PREALLOC) {
 937                 extent_end = extent_start +
 938                         btrfs_file_extent_num_bytes(leaf, fi);
 939         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 940                 size_t size;
 941                 size = btrfs_file_extent_ram_bytes(leaf, fi);
 942                 extent_end = ALIGN(extent_start + size,
 943                                    fs_info->sectorsize);
 944         }
 945
 946         em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
 947         if (type == BTRFS_FILE_EXTENT_REG ||
 948             type == BTRFS_FILE_EXTENT_PREALLOC) {
 949                 em->start = extent_start;
 950                 em->len = extent_end - extent_start;
 951                 em->orig_start = extent_start -
 952                         btrfs_file_extent_offset(leaf, fi);
 953                 em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
 954                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 955                 if (bytenr == 0) {
 956                         em->block_start = EXTENT_MAP_HOLE;
 957                         return;
 958                 }
 959                 if (compress_type != BTRFS_COMPRESS_NONE) {
 960                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 961                         em->compress_type = compress_type;
 962                         em->block_start = bytenr;
 963                         em->block_len = em->orig_block_len;
 964                 } else {
 965                         bytenr += btrfs_file_extent_offset(leaf, fi);
 966                         em->block_start = bytenr;
 967                         em->block_len = em->len;
 968                         if (type == BTRFS_FILE_EXTENT_PREALLOC)
 969                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
 970                 }
 971         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
 972                 em->block_start = EXTENT_MAP_INLINE;
 973                 em->start = extent_start;
 974                 em->len = extent_end - extent_start;
 975                 /*
 976                  * Initialize orig_start and block_len with the same values
 977                  * as in inode.c:btrfs_get_extent().
 978                  */
 979                 em->orig_start = EXTENT_MAP_HOLE;
 980                 em->block_len = (u64)-1;
 981                 if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
 982                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 983                         em->compress_type = compress_type;
 984                 }
 985         } else {
 986                 btrfs_err(fs_info,
 987                           "unknown file extent item type %d, inode %llu, offset %llu, "
 988                           "root %llu", type, btrfs_ino(inode), extent_start,
 989                           root->root_key.objectid);
 990         }
 991 }