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 <crypto/hash.h>
  12 #include "messages.h"
  13 #include "misc.h"
  14 #include "ctree.h"
  15 #include "disk-io.h"
  16 #include "transaction.h"
  17 #include "volumes.h"
  18 #include "print-tree.h"
  19 #include "compression.h"
  20 #include "fs.h"
  21 #include "accessors.h"
  22 #include "file-item.h"
  23 #include "super.h"
  24
  25 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  26                                    sizeof(struct btrfs_item) * 2) / \
  27                                   size) - 1))
  28
  29 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  30                                        PAGE_SIZE))
  31
  32 /*
  33  * Set inode's size according to filesystem options.
  34  *
  35  * @inode:      inode we want to update the disk_i_size for
  36  * @new_i_size: i_size we want to set to, 0 if we use i_size
  37  *
  38  * With NO_HOLES set this simply sets the disk_is_size to whatever i_size_read()
  39  * returns as it is perfectly fine with a file that has holes without hole file
  40  * extent items.
  41  *
  42  * However without NO_HOLES we need to only return the area that is contiguous
  43  * from the 0 offset of the file.  Otherwise we could end up adjust i_size up
  44  * to an extent that has a gap in between.
  45  *
  46  * Finally new_i_size should only be set in the case of truncate where we're not
  47  * ready to use i_size_read() as the limiter yet.
  48  */
  49 void btrfs_inode_safe_disk_i_size_write(struct btrfs_inode *inode, u64 new_i_size)
  50 {
  51         struct btrfs_fs_info *fs_info = inode->root->fs_info;
  52         u64 start, end, i_size;
  53         int ret;
  54
  55         i_size = new_i_size ?: i_size_read(&inode->vfs_inode);
  56         if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
  57                 inode->disk_i_size = i_size;
  58                 return;
  59         }
  60
  61         spin_lock(&inode->lock);
  62         ret = find_contiguous_extent_bit(&inode->file_extent_tree, 0, &start,
  63                                          &end, EXTENT_DIRTY);
  64         if (!ret && start == 0)
  65                 i_size = min(i_size, end + 1);
  66         else
  67                 i_size = 0;
  68         inode->disk_i_size = i_size;
  69         spin_unlock(&inode->lock);
  70 }
  71
  72 /*
  73  * Mark range within a file as having a new extent inserted.
  74  *
  75  * @inode: inode being modified
  76  * @start: start file offset of the file extent we've inserted
  77  * @len:   logical length of the file extent item
  78  *
  79  * Call when we are inserting a new file extent where there was none before.
  80  * Does not need to call this in the case where we're replacing an existing file
  81  * extent, however if not sure it's fine to call this multiple times.
  82  *
  83  * The start and len must match the file extent item, so thus must be sectorsize
  84  * aligned.
  85  */
  86 int btrfs_inode_set_file_extent_range(struct btrfs_inode *inode, u64 start,
  87                                       u64 len)
  88 {
  89         if (len == 0)
  90                 return 0;
  91
  92         ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize));
  93
  94         if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
  95                 return 0;
  96         return set_extent_bits(&inode->file_extent_tree, start, start + len - 1,
  97                                EXTENT_DIRTY);
  98 }
  99
 100 /*
 101  * Mark an inode range as not having a backing extent.
 102  *
 103  * @inode: inode being modified
 104  * @start: start file offset of the file extent we've inserted
 105  * @len:   logical length of the file extent item
 106  *
 107  * Called when we drop a file extent, for example when we truncate.  Doesn't
 108  * need to be called for cases where we're replacing a file extent, like when
 109  * we've COWed a file extent.
 110  *
 111  * The start and len must match the file extent item, so thus must be sectorsize
 112  * aligned.
 113  */
 114 int btrfs_inode_clear_file_extent_range(struct btrfs_inode *inode, u64 start,
 115                                         u64 len)
 116 {
 117         if (len == 0)
 118                 return 0;
 119
 120         ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize) ||
 121                len == (u64)-1);
 122
 123         if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
 124                 return 0;
 125         return clear_extent_bit(&inode->file_extent_tree, start,
 126                                 start + len - 1, EXTENT_DIRTY, NULL);
 127 }
 128
 129 static size_t bytes_to_csum_size(const struct btrfs_fs_info *fs_info, u32 bytes)
 130 {
 131         ASSERT(IS_ALIGNED(bytes, fs_info->sectorsize));
 132
 133         return (bytes >> fs_info->sectorsize_bits) * fs_info->csum_size;
 134 }
 135
 136 static size_t csum_size_to_bytes(const struct btrfs_fs_info *fs_info, u32 csum_size)
 137 {
 138         ASSERT(IS_ALIGNED(csum_size, fs_info->csum_size));
 139
 140         return (csum_size / fs_info->csum_size) << fs_info->sectorsize_bits;
 141 }
 142
 143 static inline u32 max_ordered_sum_bytes(const struct btrfs_fs_info *fs_info)
 144 {
 145         u32 max_csum_size = round_down(PAGE_SIZE - sizeof(struct btrfs_ordered_sum),
 146                                        fs_info->csum_size);
 147
 148         return csum_size_to_bytes(fs_info, max_csum_size);
 149 }
 150
 151 /*
 152  * Calculate the total size needed to allocate for an ordered sum structure
 153  * spanning @bytes in the file.
 154  */
 155 static int btrfs_ordered_sum_size(struct btrfs_fs_info *fs_info, unsigned long bytes)
 156 {
 157         return sizeof(struct btrfs_ordered_sum) + bytes_to_csum_size(fs_info, bytes);
 158 }
 159
 160 int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans,
 161                              struct btrfs_root *root,
 162                              u64 objectid, u64 pos, u64 num_bytes)
 163 {
 164         int ret = 0;
 165         struct btrfs_file_extent_item *item;
 166         struct btrfs_key file_key;
 167         struct btrfs_path *path;
 168         struct extent_buffer *leaf;
 169
 170         path = btrfs_alloc_path();
 171         if (!path)
 172                 return -ENOMEM;
 173         file_key.objectid = objectid;
 174         file_key.offset = pos;
 175         file_key.type = BTRFS_EXTENT_DATA_KEY;
 176
 177         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 178                                       sizeof(*item));
 179         if (ret < 0)
 180                 goto out;
 181         BUG_ON(ret); /* Can't happen */
 182         leaf = path->nodes[0];
 183         item = btrfs_item_ptr(leaf, path->slots[0],
 184                               struct btrfs_file_extent_item);
 185         btrfs_set_file_extent_disk_bytenr(leaf, item, 0);
 186         btrfs_set_file_extent_disk_num_bytes(leaf, item, 0);
 187         btrfs_set_file_extent_offset(leaf, item, 0);
 188         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
 189         btrfs_set_file_extent_ram_bytes(leaf, item, num_bytes);
 190         btrfs_set_file_extent_generation(leaf, item, trans->transid);
 191         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
 192         btrfs_set_file_extent_compression(leaf, item, 0);
 193         btrfs_set_file_extent_encryption(leaf, item, 0);
 194         btrfs_set_file_extent_other_encoding(leaf, item, 0);
 195
 196         btrfs_mark_buffer_dirty(leaf);
 197 out:
 198         btrfs_free_path(path);
 199         return ret;
 200 }
 201
 202 static struct btrfs_csum_item *
 203 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 204                   struct btrfs_root *root,
 205                   struct btrfs_path *path,
 206                   u64 bytenr, int cow)
 207 {
 208         struct btrfs_fs_info *fs_info = root->fs_info;
 209         int ret;
 210         struct btrfs_key file_key;
 211         struct btrfs_key found_key;
 212         struct btrfs_csum_item *item;
 213         struct extent_buffer *leaf;
 214         u64 csum_offset = 0;
 215         const u32 csum_size = fs_info->csum_size;
 216         int csums_in_item;
 217
 218         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 219         file_key.offset = bytenr;
 220         file_key.type = BTRFS_EXTENT_CSUM_KEY;
 221         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 222         if (ret < 0)
 223                 goto fail;
 224         leaf = path->nodes[0];
 225         if (ret > 0) {
 226                 ret = 1;
 227                 if (path->slots[0] == 0)
 228                         goto fail;
 229                 path->slots[0]--;
 230                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 231                 if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 232                         goto fail;
 233
 234                 csum_offset = (bytenr - found_key.offset) >>
 235                                 fs_info->sectorsize_bits;
 236                 csums_in_item = btrfs_item_size(leaf, path->slots[0]);
 237                 csums_in_item /= csum_size;
 238
 239                 if (csum_offset == csums_in_item) {
 240                         ret = -EFBIG;
 241                         goto fail;
 242                 } else if (csum_offset > csums_in_item) {
 243                         goto fail;
 244                 }
 245         }
 246         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 247         item = (struct btrfs_csum_item *)((unsigned char *)item +
 248                                           csum_offset * csum_size);
 249         return item;
 250 fail:
 251         if (ret > 0)
 252                 ret = -ENOENT;
 253         return ERR_PTR(ret);
 254 }
 255
 256 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 257                              struct btrfs_root *root,
 258                              struct btrfs_path *path, u64 objectid,
 259                              u64 offset, int mod)
 260 {
 261         struct btrfs_key file_key;
 262         int ins_len = mod < 0 ? -1 : 0;
 263         int cow = mod != 0;
 264
 265         file_key.objectid = objectid;
 266         file_key.offset = offset;
 267         file_key.type = BTRFS_EXTENT_DATA_KEY;
 268
 269         return btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 270 }
 271
 272 /*
 273  * Find checksums for logical bytenr range [disk_bytenr, disk_bytenr + len) and
 274  * store the result to @dst.
 275  *
 276  * Return >0 for the number of sectors we found.
 277  * Return 0 for the range [disk_bytenr, disk_bytenr + sectorsize) has no csum
 278  * for it. Caller may want to try next sector until one range is hit.
 279  * Return <0 for fatal error.
 280  */
 281 static int search_csum_tree(struct btrfs_fs_info *fs_info,
 282                             struct btrfs_path *path, u64 disk_bytenr,
 283                             u64 len, u8 *dst)
 284 {
 285         struct btrfs_root *csum_root;
 286         struct btrfs_csum_item *item = NULL;
 287         struct btrfs_key key;
 288         const u32 sectorsize = fs_info->sectorsize;
 289         const u32 csum_size = fs_info->csum_size;
 290         u32 itemsize;
 291         int ret;
 292         u64 csum_start;
 293         u64 csum_len;
 294
 295         ASSERT(IS_ALIGNED(disk_bytenr, sectorsize) &&
 296                IS_ALIGNED(len, sectorsize));
 297
 298         /* Check if the current csum item covers disk_bytenr */
 299         if (path->nodes[0]) {
 300                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 301                                       struct btrfs_csum_item);
 302                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 303                 itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
 304
 305                 csum_start = key.offset;
 306                 csum_len = (itemsize / csum_size) * sectorsize;
 307
 308                 if (in_range(disk_bytenr, csum_start, csum_len))
 309                         goto found;
 310         }
 311
 312         /* Current item doesn't contain the desired range, search again */
 313         btrfs_release_path(path);
 314         csum_root = btrfs_csum_root(fs_info, disk_bytenr);
 315         item = btrfs_lookup_csum(NULL, csum_root, path, disk_bytenr, 0);
 316         if (IS_ERR(item)) {
 317                 ret = PTR_ERR(item);
 318                 goto out;
 319         }
 320         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 321         itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
 322
 323         csum_start = key.offset;
 324         csum_len = (itemsize / csum_size) * sectorsize;
 325         ASSERT(in_range(disk_bytenr, csum_start, csum_len));
 326
 327 found:
 328         ret = (min(csum_start + csum_len, disk_bytenr + len) -
 329                    disk_bytenr) >> fs_info->sectorsize_bits;
 330         read_extent_buffer(path->nodes[0], dst, (unsigned long)item,
 331                         ret * csum_size);
 332 out:
 333         if (ret == -ENOENT || ret == -EFBIG)
 334                 ret = 0;
 335         return ret;
 336 }
 337
 338 /*
 339  * Locate the file_offset of @cur_disk_bytenr of a @bio.
 340  *
 341  * Bio of btrfs represents read range of
 342  * [bi_sector << 9, bi_sector << 9 + bi_size).
 343  * Knowing this, we can iterate through each bvec to locate the page belong to
 344  * @cur_disk_bytenr and get the file offset.
 345  *
 346  * @inode is used to determine if the bvec page really belongs to @inode.
 347  *
 348  * Return 0 if we can't find the file offset
 349  * Return >0 if we find the file offset and restore it to @file_offset_ret
 350  */
 351 static int search_file_offset_in_bio(struct bio *bio, struct inode *inode,
 352                                      u64 disk_bytenr, u64 *file_offset_ret)
 353 {
 354         struct bvec_iter iter;
 355         struct bio_vec bvec;
 356         u64 cur = bio->bi_iter.bi_sector << SECTOR_SHIFT;
 357         int ret = 0;
 358
 359         bio_for_each_segment(bvec, bio, iter) {
 360                 struct page *page = bvec.bv_page;
 361
 362                 if (cur > disk_bytenr)
 363                         break;
 364                 if (cur + bvec.bv_len <= disk_bytenr) {
 365                         cur += bvec.bv_len;
 366                         continue;
 367                 }
 368                 ASSERT(in_range(disk_bytenr, cur, bvec.bv_len));
 369                 if (page->mapping && page->mapping->host &&
 370                     page->mapping->host == inode) {
 371                         ret = 1;
 372                         *file_offset_ret = page_offset(page) + bvec.bv_offset +
 373                                            disk_bytenr - cur;
 374                         break;
 375                 }
 376         }
 377         return ret;
 378 }
 379
 380 /*
 381  * Lookup the checksum for the read bio in csum tree.
 382  *
 383  * @inode:  inode that the bio is for.
 384  * @bio:    bio to look up.
 385  * @dst:    Buffer of size nblocks * btrfs_super_csum_size() used to return
 386  *          checksum (nblocks = bio->bi_iter.bi_size / fs_info->sectorsize). If
 387  *          NULL, the checksum buffer is allocated and returned in
 388  *          btrfs_bio(bio)->csum instead.
 389  *
 390  * Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
 391  */
 392 blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst)
 393 {
 394         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 395         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 396         struct btrfs_bio *bbio = NULL;
 397         struct btrfs_path *path;
 398         const u32 sectorsize = fs_info->sectorsize;
 399         const u32 csum_size = fs_info->csum_size;
 400         u32 orig_len = bio->bi_iter.bi_size;
 401         u64 orig_disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
 402         u64 cur_disk_bytenr;
 403         u8 *csum;
 404         const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
 405         int count = 0;
 406         blk_status_t ret = BLK_STS_OK;
 407
 408         if ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) ||
 409             test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
 410                 return BLK_STS_OK;
 411
 412         /*
 413          * This function is only called for read bio.
 414          *
 415          * This means two things:
 416          * - All our csums should only be in csum tree
 417          *   No ordered extents csums, as ordered extents are only for write
 418          *   path.
 419          * - No need to bother any other info from bvec
 420          *   Since we're looking up csums, the only important info is the
 421          *   disk_bytenr and the length, which can be extracted from bi_iter
 422          *   directly.
 423          */
 424         ASSERT(bio_op(bio) == REQ_OP_READ);
 425         path = btrfs_alloc_path();
 426         if (!path)
 427                 return BLK_STS_RESOURCE;
 428
 429         if (!dst) {
 430                 bbio = btrfs_bio(bio);
 431
 432                 if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 433                         bbio->csum = kmalloc_array(nblocks, csum_size, GFP_NOFS);
 434                         if (!bbio->csum) {
 435                                 btrfs_free_path(path);
 436                                 return BLK_STS_RESOURCE;
 437                         }
 438                 } else {
 439                         bbio->csum = bbio->csum_inline;
 440                 }
 441                 csum = bbio->csum;
 442         } else {
 443                 csum = dst;
 444         }
 445
 446         /*
 447          * If requested number of sectors is larger than one leaf can contain,
 448          * kick the readahead for csum tree.
 449          */
 450         if (nblocks > fs_info->csums_per_leaf)
 451                 path->reada = READA_FORWARD;
 452
 453         /*
 454          * the free space stuff is only read when it hasn't been
 455          * updated in the current transaction.  So, we can safely
 456          * read from the commit root and sidestep a nasty deadlock
 457          * between reading the free space cache and updating the csum tree.
 458          */
 459         if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
 460                 path->search_commit_root = 1;
 461                 path->skip_locking = 1;
 462         }
 463
 464         for (cur_disk_bytenr = orig_disk_bytenr;
 465              cur_disk_bytenr < orig_disk_bytenr + orig_len;
 466              cur_disk_bytenr += (count * sectorsize)) {
 467                 u64 search_len = orig_disk_bytenr + orig_len - cur_disk_bytenr;
 468                 unsigned int sector_offset;
 469                 u8 *csum_dst;
 470
 471                 /*
 472                  * Although both cur_disk_bytenr and orig_disk_bytenr is u64,
 473                  * we're calculating the offset to the bio start.
 474                  *
 475                  * Bio size is limited to UINT_MAX, thus unsigned int is large
 476                  * enough to contain the raw result, not to mention the right
 477                  * shifted result.
 478                  */
 479                 ASSERT(cur_disk_bytenr - orig_disk_bytenr < UINT_MAX);
 480                 sector_offset = (cur_disk_bytenr - orig_disk_bytenr) >>
 481                                 fs_info->sectorsize_bits;
 482                 csum_dst = csum + sector_offset * csum_size;
 483
 484                 count = search_csum_tree(fs_info, path, cur_disk_bytenr,
 485                                          search_len, csum_dst);
 486                 if (count < 0) {
 487                         ret = errno_to_blk_status(count);
 488                         if (bbio)
 489                                 btrfs_bio_free_csum(bbio);
 490                         break;
 491                 }
 492
 493                 /*
 494                  * We didn't find a csum for this range.  We need to make sure
 495                  * we complain loudly about this, because we are not NODATASUM.
 496                  *
 497                  * However for the DATA_RELOC inode we could potentially be
 498                  * relocating data extents for a NODATASUM inode, so the inode
 499                  * itself won't be marked with NODATASUM, but the extent we're
 500                  * copying is in fact NODATASUM.  If we don't find a csum we
 501                  * assume this is the case.
 502                  */
 503                 if (count == 0) {
 504                         memset(csum_dst, 0, csum_size);
 505                         count = 1;
 506
 507                         if (BTRFS_I(inode)->root->root_key.objectid ==
 508                             BTRFS_DATA_RELOC_TREE_OBJECTID) {
 509                                 u64 file_offset;
 510                                 int ret;
 511
 512                                 ret = search_file_offset_in_bio(bio, inode,
 513                                                 cur_disk_bytenr, &file_offset);
 514                                 if (ret)
 515                                         set_extent_bits(io_tree, file_offset,
 516                                                 file_offset + sectorsize - 1,
 517                                                 EXTENT_NODATASUM);
 518                         } else {
 519                                 btrfs_warn_rl(fs_info,
 520                         "csum hole found for disk bytenr range [%llu, %llu)",
 521                                 cur_disk_bytenr, cur_disk_bytenr + sectorsize);
 522                         }
 523                 }
 524         }
 525
 526         btrfs_free_path(path);
 527         return ret;
 528 }
 529
 530 int btrfs_lookup_csums_list(struct btrfs_root *root, u64 start, u64 end,
 531                             struct list_head *list, int search_commit,
 532                             bool nowait)
 533 {
 534         struct btrfs_fs_info *fs_info = root->fs_info;
 535         struct btrfs_key key;
 536         struct btrfs_path *path;
 537         struct extent_buffer *leaf;
 538         struct btrfs_ordered_sum *sums;
 539         struct btrfs_csum_item *item;
 540         LIST_HEAD(tmplist);
 541         int ret;
 542
 543         ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 544                IS_ALIGNED(end + 1, fs_info->sectorsize));
 545
 546         path = btrfs_alloc_path();
 547         if (!path)
 548                 return -ENOMEM;
 549
 550         path->nowait = nowait;
 551         if (search_commit) {
 552                 path->skip_locking = 1;
 553                 path->reada = READA_FORWARD;
 554                 path->search_commit_root = 1;
 555         }
 556
 557         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 558         key.offset = start;
 559         key.type = BTRFS_EXTENT_CSUM_KEY;
 560
 561         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 562         if (ret < 0)
 563                 goto fail;
 564         if (ret > 0 && path->slots[0] > 0) {
 565                 leaf = path->nodes[0];
 566                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 567
 568                 /*
 569                  * There are two cases we can hit here for the previous csum
 570                  * item:
 571                  *
 572                  *              |<- search range ->|
 573                  *      |<- csum item ->|
 574                  *
 575                  * Or
 576                  *                              |<- search range ->|
 577                  *      |<- csum item ->|
 578                  *
 579                  * Check if the previous csum item covers the leading part of
 580                  * the search range.  If so we have to start from previous csum
 581                  * item.
 582                  */
 583                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 584                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 585                         if (bytes_to_csum_size(fs_info, start - key.offset) <
 586                             btrfs_item_size(leaf, path->slots[0] - 1))
 587                                 path->slots[0]--;
 588                 }
 589         }
 590
 591         while (start <= end) {
 592                 u64 csum_end;
 593
 594                 leaf = path->nodes[0];
 595                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 596                         ret = btrfs_next_leaf(root, path);
 597                         if (ret < 0)
 598                                 goto fail;
 599                         if (ret > 0)
 600                                 break;
 601                         leaf = path->nodes[0];
 602                 }
 603
 604                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 605                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 606                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 607                     key.offset > end)
 608                         break;
 609
 610                 if (key.offset > start)
 611                         start = key.offset;
 612
 613                 csum_end = key.offset + csum_size_to_bytes(fs_info,
 614                                         btrfs_item_size(leaf, path->slots[0]));
 615                 if (csum_end <= start) {
 616                         path->slots[0]++;
 617                         continue;
 618                 }
 619
 620                 csum_end = min(csum_end, end + 1);
 621                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 622                                       struct btrfs_csum_item);
 623                 while (start < csum_end) {
 624                         unsigned long offset;
 625                         size_t size;
 626
 627                         size = min_t(size_t, csum_end - start,
 628                                      max_ordered_sum_bytes(fs_info));
 629                         sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
 630                                        GFP_NOFS);
 631                         if (!sums) {
 632                                 ret = -ENOMEM;
 633                                 goto fail;
 634                         }
 635
 636                         sums->bytenr = start;
 637                         sums->len = (int)size;
 638
 639                         offset = bytes_to_csum_size(fs_info, start - key.offset);
 640
 641                         read_extent_buffer(path->nodes[0],
 642                                            sums->sums,
 643                                            ((unsigned long)item) + offset,
 644                                            bytes_to_csum_size(fs_info, size));
 645
 646                         start += size;
 647                         list_add_tail(&sums->list, &tmplist);
 648                 }
 649                 path->slots[0]++;
 650         }
 651         ret = 0;
 652 fail:
 653         while (ret < 0 && !list_empty(&tmplist)) {
 654                 sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 655                 list_del(&sums->list);
 656                 kfree(sums);
 657         }
 658         list_splice_tail(&tmplist, list);
 659
 660         btrfs_free_path(path);
 661         return ret;
 662 }
 663
 664 /*
 665  * Do the same work as btrfs_lookup_csums_list(), the difference is in how
 666  * we return the result.
 667  *
 668  * This version will set the corresponding bits in @csum_bitmap to represent
 669  * that there is a csum found.
 670  * Each bit represents a sector. Thus caller should ensure @csum_buf passed
 671  * in is large enough to contain all csums.
 672  */
 673 int btrfs_lookup_csums_bitmap(struct btrfs_root *root, u64 start, u64 end,
 674                               u8 *csum_buf, unsigned long *csum_bitmap)
 675 {
 676         struct btrfs_fs_info *fs_info = root->fs_info;
 677         struct btrfs_key key;
 678         struct btrfs_path *path;
 679         struct extent_buffer *leaf;
 680         struct btrfs_csum_item *item;
 681         const u64 orig_start = start;
 682         int ret;
 683
 684         ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 685                IS_ALIGNED(end + 1, fs_info->sectorsize));
 686
 687         path = btrfs_alloc_path();
 688         if (!path)
 689                 return -ENOMEM;
 690
 691         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 692         key.type = BTRFS_EXTENT_CSUM_KEY;
 693         key.offset = start;
 694
 695         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 696         if (ret < 0)
 697                 goto fail;
 698         if (ret > 0 && path->slots[0] > 0) {
 699                 leaf = path->nodes[0];
 700                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 701
 702                 /*
 703                  * There are two cases we can hit here for the previous csum
 704                  * item:
 705                  *
 706                  *              |<- search range ->|
 707                  *      |<- csum item ->|
 708                  *
 709                  * Or
 710                  *                              |<- search range ->|
 711                  *      |<- csum item ->|
 712                  *
 713                  * Check if the previous csum item covers the leading part of
 714                  * the search range.  If so we have to start from previous csum
 715                  * item.
 716                  */
 717                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 718                     key.type == BTRFS_EXTENT_CSUM_KEY) {
 719                         if (bytes_to_csum_size(fs_info, start - key.offset) <
 720                             btrfs_item_size(leaf, path->slots[0] - 1))
 721                                 path->slots[0]--;
 722                 }
 723         }
 724
 725         while (start <= end) {
 726                 u64 csum_end;
 727
 728                 leaf = path->nodes[0];
 729                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 730                         ret = btrfs_next_leaf(root, path);
 731                         if (ret < 0)
 732                                 goto fail;
 733                         if (ret > 0)
 734                                 break;
 735                         leaf = path->nodes[0];
 736                 }
 737
 738                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 739                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 740                     key.type != BTRFS_EXTENT_CSUM_KEY ||
 741                     key.offset > end)
 742                         break;
 743
 744                 if (key.offset > start)
 745                         start = key.offset;
 746
 747                 csum_end = key.offset + csum_size_to_bytes(fs_info,
 748                                         btrfs_item_size(leaf, path->slots[0]));
 749                 if (csum_end <= start) {
 750                         path->slots[0]++;
 751                         continue;
 752                 }
 753
 754                 csum_end = min(csum_end, end + 1);
 755                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 756                                       struct btrfs_csum_item);
 757                 while (start < csum_end) {
 758                         unsigned long offset;
 759                         size_t size;
 760                         u8 *csum_dest = csum_buf + bytes_to_csum_size(fs_info,
 761                                                 start - orig_start);
 762
 763                         size = min_t(size_t, csum_end - start, end + 1 - start);
 764
 765                         offset = bytes_to_csum_size(fs_info, start - key.offset);
 766
 767                         read_extent_buffer(path->nodes[0], csum_dest,
 768                                            ((unsigned long)item) + offset,
 769                                            bytes_to_csum_size(fs_info, size));
 770
 771                         bitmap_set(csum_bitmap,
 772                                 (start - orig_start) >> fs_info->sectorsize_bits,
 773                                 size >> fs_info->sectorsize_bits);
 774
 775                         start += size;
 776                 }
 777                 path->slots[0]++;
 778         }
 779         ret = 0;
 780 fail:
 781         btrfs_free_path(path);
 782         return ret;
 783 }
 784
 785 /*
 786  * Calculate checksums of the data contained inside a bio.
 787  *
 788  * @inode:       Owner of the data inside the bio
 789  * @bio:         Contains the data to be checksummed
 790  * @offset:      If (u64)-1, @bio may contain discontiguous bio vecs, so the
 791  *               file offsets are determined from the page offsets in the bio.
 792  *               Otherwise, this is the starting file offset of the bio vecs in
 793  *               @bio, which must be contiguous.
 794  * @one_ordered: If true, @bio only refers to one ordered extent.
 795  */
 796 blk_status_t btrfs_csum_one_bio(struct btrfs_inode *inode, struct bio *bio,
 797                                 u64 offset, bool one_ordered)
 798 {
 799         struct btrfs_fs_info *fs_info = inode->root->fs_info;
 800         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
 801         struct btrfs_ordered_sum *sums;
 802         struct btrfs_ordered_extent *ordered = NULL;
 803         const bool use_page_offsets = (offset == (u64)-1);
 804         char *data;
 805         struct bvec_iter iter;
 806         struct bio_vec bvec;
 807         int index;
 808         unsigned int blockcount;
 809         unsigned long total_bytes = 0;
 810         unsigned long this_sum_bytes = 0;
 811         int i;
 812         unsigned nofs_flag;
 813
 814         nofs_flag = memalloc_nofs_save();
 815         sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
 816                        GFP_KERNEL);
 817         memalloc_nofs_restore(nofs_flag);
 818
 819         if (!sums)
 820                 return BLK_STS_RESOURCE;
 821
 822         sums->len = bio->bi_iter.bi_size;
 823         INIT_LIST_HEAD(&sums->list);
 824
 825         sums->bytenr = bio->bi_iter.bi_sector << 9;
 826         index = 0;
 827
 828         shash->tfm = fs_info->csum_shash;
 829
 830         bio_for_each_segment(bvec, bio, iter) {
 831                 if (use_page_offsets)
 832                         offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 833
 834                 if (!ordered) {
 835                         ordered = btrfs_lookup_ordered_extent(inode, offset);
 836                         /*
 837                          * The bio range is not covered by any ordered extent,
 838                          * must be a code logic error.
 839                          */
 840                         if (unlikely(!ordered)) {
 841                                 WARN(1, KERN_WARNING
 842                         "no ordered extent for root %llu ino %llu offset %llu\n",
 843                                      inode->root->root_key.objectid,
 844                                      btrfs_ino(inode), offset);
 845                                 kvfree(sums);
 846                                 return BLK_STS_IOERR;
 847                         }
 848                 }
 849
 850                 blockcount = BTRFS_BYTES_TO_BLKS(fs_info,
 851                                                  bvec.bv_len + fs_info->sectorsize
 852                                                  - 1);
 853
 854                 for (i = 0; i < blockcount; i++) {
 855                         if (!one_ordered &&
 856                             !in_range(offset, ordered->file_offset,
 857                                       ordered->num_bytes)) {
 858                                 unsigned long bytes_left;
 859
 860                                 sums->len = this_sum_bytes;
 861                                 this_sum_bytes = 0;
 862                                 btrfs_add_ordered_sum(ordered, sums);
 863                                 btrfs_put_ordered_extent(ordered);
 864
 865                                 bytes_left = bio->bi_iter.bi_size - total_bytes;
 866
 867                                 nofs_flag = memalloc_nofs_save();
 868                                 sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
 869                                                       bytes_left), GFP_KERNEL);
 870                                 memalloc_nofs_restore(nofs_flag);
 871                                 BUG_ON(!sums); /* -ENOMEM */
 872                                 sums->len = bytes_left;
 873                                 ordered = btrfs_lookup_ordered_extent(inode,
 874                                                                 offset);
 875                                 ASSERT(ordered); /* Logic error */
 876                                 sums->bytenr = (bio->bi_iter.bi_sector << 9)
 877                                         + total_bytes;
 878                                 index = 0;
 879                         }
 880
 881                         data = bvec_kmap_local(&bvec);
 882                         crypto_shash_digest(shash,
 883                                             data + (i * fs_info->sectorsize),
 884                                             fs_info->sectorsize,
 885                                             sums->sums + index);
 886                         kunmap_local(data);
 887                         index += fs_info->csum_size;
 888                         offset += fs_info->sectorsize;
 889                         this_sum_bytes += fs_info->sectorsize;
 890                         total_bytes += fs_info->sectorsize;
 891                 }
 892
 893         }
 894         this_sum_bytes = 0;
 895         btrfs_add_ordered_sum(ordered, sums);
 896         btrfs_put_ordered_extent(ordered);
 897         return 0;
 898 }
 899
 900 /*
 901  * Remove one checksum overlapping a range.
 902  *
 903  * This expects the key to describe the csum pointed to by the path, and it
 904  * expects the csum to overlap the range [bytenr, len]
 905  *
 906  * The csum should not be entirely contained in the range and the range should
 907  * not be entirely contained in the csum.
 908  *
 909  * This calls btrfs_truncate_item with the correct args based on the overlap,
 910  * and fixes up the key as required.
 911  */
 912 static noinline void truncate_one_csum(struct btrfs_fs_info *fs_info,
 913                                        struct btrfs_path *path,
 914                                        struct btrfs_key *key,
 915                                        u64 bytenr, u64 len)
 916 {
 917         struct extent_buffer *leaf;
 918         const u32 csum_size = fs_info->csum_size;
 919         u64 csum_end;
 920         u64 end_byte = bytenr + len;
 921         u32 blocksize_bits = fs_info->sectorsize_bits;
 922
 923         leaf = path->nodes[0];
 924         csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
 925         csum_end <<= blocksize_bits;
 926         csum_end += key->offset;
 927
 928         if (key->offset < bytenr && csum_end <= end_byte) {
 929                 /*
 930                  *         [ bytenr - len ]
 931                  *         [   ]
 932                  *   [csum     ]
 933                  *   A simple truncate off the end of the item
 934                  */
 935                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 936                 new_size *= csum_size;
 937                 btrfs_truncate_item(path, new_size, 1);
 938         } else if (key->offset >= bytenr && csum_end > end_byte &&
 939                    end_byte > key->offset) {
 940                 /*
 941                  *         [ bytenr - len ]
 942                  *                 [ ]
 943                  *                 [csum     ]
 944                  * we need to truncate from the beginning of the csum
 945                  */
 946                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 947                 new_size *= csum_size;
 948
 949                 btrfs_truncate_item(path, new_size, 0);
 950
 951                 key->offset = end_byte;
 952                 btrfs_set_item_key_safe(fs_info, path, key);
 953         } else {
 954                 BUG();
 955         }
 956 }
 957
 958 /*
 959  * Delete the csum items from the csum tree for a given range of bytes.
 960  */
 961 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 962                     struct btrfs_root *root, u64 bytenr, u64 len)
 963 {
 964         struct btrfs_fs_info *fs_info = trans->fs_info;
 965         struct btrfs_path *path;
 966         struct btrfs_key key;
 967         u64 end_byte = bytenr + len;
 968         u64 csum_end;
 969         struct extent_buffer *leaf;
 970         int ret = 0;
 971         const u32 csum_size = fs_info->csum_size;
 972         u32 blocksize_bits = fs_info->sectorsize_bits;
 973
 974         ASSERT(root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID ||
 975                root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
 976
 977         path = btrfs_alloc_path();
 978         if (!path)
 979                 return -ENOMEM;
 980
 981         while (1) {
 982                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 983                 key.offset = end_byte - 1;
 984                 key.type = BTRFS_EXTENT_CSUM_KEY;
 985
 986                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 987                 if (ret > 0) {
 988                         ret = 0;
 989                         if (path->slots[0] == 0)
 990                                 break;
 991                         path->slots[0]--;
 992                 } else if (ret < 0) {
 993                         break;
 994                 }
 995
 996                 leaf = path->nodes[0];
 997                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 998
 999                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1000                     key.type != BTRFS_EXTENT_CSUM_KEY) {
1001                         break;
1002                 }
1003
1004                 if (key.offset >= end_byte)
1005                         break;
1006
1007                 csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
1008                 csum_end <<= blocksize_bits;
1009                 csum_end += key.offset;
1010
1011                 /* this csum ends before we start, we're done */
1012                 if (csum_end <= bytenr)
1013                         break;
1014
1015                 /* delete the entire item, it is inside our range */
1016                 if (key.offset >= bytenr && csum_end <= end_byte) {
1017                         int del_nr = 1;
1018
1019                         /*
1020                          * Check how many csum items preceding this one in this
1021                          * leaf correspond to our range and then delete them all
1022                          * at once.
1023                          */
1024                         if (key.offset > bytenr && path->slots[0] > 0) {
1025                                 int slot = path->slots[0] - 1;
1026
1027                                 while (slot >= 0) {
1028                                         struct btrfs_key pk;
1029
1030                                         btrfs_item_key_to_cpu(leaf, &pk, slot);
1031                                         if (pk.offset < bytenr ||
1032                                             pk.type != BTRFS_EXTENT_CSUM_KEY ||
1033                                             pk.objectid !=
1034                                             BTRFS_EXTENT_CSUM_OBJECTID)
1035                                                 break;
1036                                         path->slots[0] = slot;
1037                                         del_nr++;
1038                                         key.offset = pk.offset;
1039                                         slot--;
1040                                 }
1041                         }
1042                         ret = btrfs_del_items(trans, root, path,
1043                                               path->slots[0], del_nr);
1044                         if (ret)
1045                                 break;
1046                         if (key.offset == bytenr)
1047                                 break;
1048                 } else if (key.offset < bytenr && csum_end > end_byte) {
1049                         unsigned long offset;
1050                         unsigned long shift_len;
1051                         unsigned long item_offset;
1052                         /*
1053                          *        [ bytenr - len ]
1054                          *     [csum                ]
1055                          *
1056                          * Our bytes are in the middle of the csum,
1057                          * we need to split this item and insert a new one.
1058                          *
1059                          * But we can't drop the path because the
1060                          * csum could change, get removed, extended etc.
1061                          *
1062                          * The trick here is the max size of a csum item leaves
1063                          * enough room in the tree block for a single
1064                          * item header.  So, we split the item in place,
1065                          * adding a new header pointing to the existing
1066                          * bytes.  Then we loop around again and we have
1067                          * a nicely formed csum item that we can neatly
1068                          * truncate.
1069                          */
1070                         offset = (bytenr - key.offset) >> blocksize_bits;
1071                         offset *= csum_size;
1072
1073                         shift_len = (len >> blocksize_bits) * csum_size;
1074
1075                         item_offset = btrfs_item_ptr_offset(leaf,
1076                                                             path->slots[0]);
1077
1078                         memzero_extent_buffer(leaf, item_offset + offset,
1079                                              shift_len);
1080                         key.offset = bytenr;
1081
1082                         /*
1083                          * btrfs_split_item returns -EAGAIN when the
1084                          * item changed size or key
1085                          */
1086                         ret = btrfs_split_item(trans, root, path, &key, offset);
1087                         if (ret && ret != -EAGAIN) {
1088                                 btrfs_abort_transaction(trans, ret);
1089                                 break;
1090                         }
1091                         ret = 0;
1092
1093                         key.offset = end_byte - 1;
1094                 } else {
1095                         truncate_one_csum(fs_info, path, &key, bytenr, len);
1096                         if (key.offset < bytenr)
1097                                 break;
1098                 }
1099                 btrfs_release_path(path);
1100         }
1101         btrfs_free_path(path);
1102         return ret;
1103 }
1104
1105 static int find_next_csum_offset(struct btrfs_root *root,
1106                                  struct btrfs_path *path,
1107                                  u64 *next_offset)
1108 {
1109         const u32 nritems = btrfs_header_nritems(path->nodes[0]);
1110         struct btrfs_key found_key;
1111         int slot = path->slots[0] + 1;
1112         int ret;
1113
1114         if (nritems == 0 || slot >= nritems) {
1115                 ret = btrfs_next_leaf(root, path);
1116                 if (ret < 0) {
1117                         return ret;
1118                 } else if (ret > 0) {
1119                         *next_offset = (u64)-1;
1120                         return 0;
1121                 }
1122                 slot = path->slots[0];
1123         }
1124
1125         btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
1126
1127         if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1128             found_key.type != BTRFS_EXTENT_CSUM_KEY)
1129                 *next_offset = (u64)-1;
1130         else
1131                 *next_offset = found_key.offset;
1132
1133         return 0;
1134 }
1135
1136 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
1137                            struct btrfs_root *root,
1138                            struct btrfs_ordered_sum *sums)
1139 {
1140         struct btrfs_fs_info *fs_info = root->fs_info;
1141         struct btrfs_key file_key;
1142         struct btrfs_key found_key;
1143         struct btrfs_path *path;
1144         struct btrfs_csum_item *item;
1145         struct btrfs_csum_item *item_end;
1146         struct extent_buffer *leaf = NULL;
1147         u64 next_offset;
1148         u64 total_bytes = 0;
1149         u64 csum_offset;
1150         u64 bytenr;
1151         u32 ins_size;
1152         int index = 0;
1153         int found_next;
1154         int ret;
1155         const u32 csum_size = fs_info->csum_size;
1156
1157         path = btrfs_alloc_path();
1158         if (!path)
1159                 return -ENOMEM;
1160 again:
1161         next_offset = (u64)-1;
1162         found_next = 0;
1163         bytenr = sums->bytenr + total_bytes;
1164         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1165         file_key.offset = bytenr;
1166         file_key.type = BTRFS_EXTENT_CSUM_KEY;
1167
1168         item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
1169         if (!IS_ERR(item)) {
1170                 ret = 0;
1171                 leaf = path->nodes[0];
1172                 item_end = btrfs_item_ptr(leaf, path->slots[0],
1173                                           struct btrfs_csum_item);
1174                 item_end = (struct btrfs_csum_item *)((char *)item_end +
1175                            btrfs_item_size(leaf, path->slots[0]));
1176                 goto found;
1177         }
1178         ret = PTR_ERR(item);
1179         if (ret != -EFBIG && ret != -ENOENT)
1180                 goto out;
1181
1182         if (ret == -EFBIG) {
1183                 u32 item_size;
1184                 /* we found one, but it isn't big enough yet */
1185                 leaf = path->nodes[0];
1186                 item_size = btrfs_item_size(leaf, path->slots[0]);
1187                 if ((item_size / csum_size) >=
1188                     MAX_CSUM_ITEMS(fs_info, csum_size)) {
1189                         /* already at max size, make a new one */
1190                         goto insert;
1191                 }
1192         } else {
1193                 /* We didn't find a csum item, insert one. */
1194                 ret = find_next_csum_offset(root, path, &next_offset);
1195                 if (ret < 0)
1196                         goto out;
1197                 found_next = 1;
1198                 goto insert;
1199         }
1200
1201         /*
1202          * At this point, we know the tree has a checksum item that ends at an
1203          * offset matching the start of the checksum range we want to insert.
1204          * We try to extend that item as much as possible and then add as many
1205          * checksums to it as they fit.
1206          *
1207          * First check if the leaf has enough free space for at least one
1208          * checksum. If it has go directly to the item extension code, otherwise
1209          * release the path and do a search for insertion before the extension.
1210          */
1211         if (btrfs_leaf_free_space(leaf) >= csum_size) {
1212                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1213                 csum_offset = (bytenr - found_key.offset) >>
1214                         fs_info->sectorsize_bits;
1215                 goto extend_csum;
1216         }
1217
1218         btrfs_release_path(path);
1219         path->search_for_extension = 1;
1220         ret = btrfs_search_slot(trans, root, &file_key, path,
1221                                 csum_size, 1);
1222         path->search_for_extension = 0;
1223         if (ret < 0)
1224                 goto out;
1225
1226         if (ret > 0) {
1227                 if (path->slots[0] == 0)
1228                         goto insert;
1229                 path->slots[0]--;
1230         }
1231
1232         leaf = path->nodes[0];
1233         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1234         csum_offset = (bytenr - found_key.offset) >> fs_info->sectorsize_bits;
1235
1236         if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
1237             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1238             csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
1239                 goto insert;
1240         }
1241
1242 extend_csum:
1243         if (csum_offset == btrfs_item_size(leaf, path->slots[0]) /
1244             csum_size) {
1245                 int extend_nr;
1246                 u64 tmp;
1247                 u32 diff;
1248
1249                 tmp = sums->len - total_bytes;
1250                 tmp >>= fs_info->sectorsize_bits;
1251                 WARN_ON(tmp < 1);
1252                 extend_nr = max_t(int, 1, tmp);
1253
1254                 /*
1255                  * A log tree can already have checksum items with a subset of
1256                  * the checksums we are trying to log. This can happen after
1257                  * doing a sequence of partial writes into prealloc extents and
1258                  * fsyncs in between, with a full fsync logging a larger subrange
1259                  * of an extent for which a previous fast fsync logged a smaller
1260                  * subrange. And this happens in particular due to merging file
1261                  * extent items when we complete an ordered extent for a range
1262                  * covered by a prealloc extent - this is done at
1263                  * btrfs_mark_extent_written().
1264                  *
1265                  * So if we try to extend the previous checksum item, which has
1266                  * a range that ends at the start of the range we want to insert,
1267                  * make sure we don't extend beyond the start offset of the next
1268                  * checksum item. If we are at the last item in the leaf, then
1269                  * forget the optimization of extending and add a new checksum
1270                  * item - it is not worth the complexity of releasing the path,
1271                  * getting the first key for the next leaf, repeat the btree
1272                  * search, etc, because log trees are temporary anyway and it
1273                  * would only save a few bytes of leaf space.
1274                  */
1275                 if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
1276                         if (path->slots[0] + 1 >=
1277                             btrfs_header_nritems(path->nodes[0])) {
1278                                 ret = find_next_csum_offset(root, path, &next_offset);
1279                                 if (ret < 0)
1280                                         goto out;
1281                                 found_next = 1;
1282                                 goto insert;
1283                         }
1284
1285                         ret = find_next_csum_offset(root, path, &next_offset);
1286                         if (ret < 0)
1287                                 goto out;
1288
1289                         tmp = (next_offset - bytenr) >> fs_info->sectorsize_bits;
1290                         if (tmp <= INT_MAX)
1291                                 extend_nr = min_t(int, extend_nr, tmp);
1292                 }
1293
1294                 diff = (csum_offset + extend_nr) * csum_size;
1295                 diff = min(diff,
1296                            MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
1297
1298                 diff = diff - btrfs_item_size(leaf, path->slots[0]);
1299                 diff = min_t(u32, btrfs_leaf_free_space(leaf), diff);
1300                 diff /= csum_size;
1301                 diff *= csum_size;
1302
1303                 btrfs_extend_item(path, diff);
1304                 ret = 0;
1305                 goto csum;
1306         }
1307
1308 insert:
1309         btrfs_release_path(path);
1310         csum_offset = 0;
1311         if (found_next) {
1312                 u64 tmp;
1313
1314                 tmp = sums->len - total_bytes;
1315                 tmp >>= fs_info->sectorsize_bits;
1316                 tmp = min(tmp, (next_offset - file_key.offset) >>
1317                                          fs_info->sectorsize_bits);
1318
1319                 tmp = max_t(u64, 1, tmp);
1320                 tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
1321                 ins_size = csum_size * tmp;
1322         } else {
1323                 ins_size = csum_size;
1324         }
1325         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
1326                                       ins_size);
1327         if (ret < 0)
1328                 goto out;
1329         if (WARN_ON(ret != 0))
1330                 goto out;
1331         leaf = path->nodes[0];
1332 csum:
1333         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
1334         item_end = (struct btrfs_csum_item *)((unsigned char *)item +
1335                                       btrfs_item_size(leaf, path->slots[0]));
1336         item = (struct btrfs_csum_item *)((unsigned char *)item +
1337                                           csum_offset * csum_size);
1338 found:
1339         ins_size = (u32)(sums->len - total_bytes) >> fs_info->sectorsize_bits;
1340         ins_size *= csum_size;
1341         ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
1342                               ins_size);
1343         write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
1344                             ins_size);
1345
1346         index += ins_size;
1347         ins_size /= csum_size;
1348         total_bytes += ins_size * fs_info->sectorsize;
1349
1350         btrfs_mark_buffer_dirty(path->nodes[0]);
1351         if (total_bytes < sums->len) {
1352                 btrfs_release_path(path);
1353                 cond_resched();
1354                 goto again;
1355         }
1356 out:
1357         btrfs_free_path(path);
1358         return ret;
1359 }
1360
1361 void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
1362                                      const struct btrfs_path *path,
1363                                      struct btrfs_file_extent_item *fi,
1364                                      struct extent_map *em)
1365 {
1366         struct btrfs_fs_info *fs_info = inode->root->fs_info;
1367         struct btrfs_root *root = inode->root;
1368         struct extent_buffer *leaf = path->nodes[0];
1369         const int slot = path->slots[0];
1370         struct btrfs_key key;
1371         u64 extent_start, extent_end;
1372         u64 bytenr;
1373         u8 type = btrfs_file_extent_type(leaf, fi);
1374         int compress_type = btrfs_file_extent_compression(leaf, fi);
1375
1376         btrfs_item_key_to_cpu(leaf, &key, slot);
1377         extent_start = key.offset;
1378         extent_end = btrfs_file_extent_end(path);
1379         em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
1380         em->generation = btrfs_file_extent_generation(leaf, fi);
1381         if (type == BTRFS_FILE_EXTENT_REG ||
1382             type == BTRFS_FILE_EXTENT_PREALLOC) {
1383                 em->start = extent_start;
1384                 em->len = extent_end - extent_start;
1385                 em->orig_start = extent_start -
1386                         btrfs_file_extent_offset(leaf, fi);
1387                 em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
1388                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1389                 if (bytenr == 0) {
1390                         em->block_start = EXTENT_MAP_HOLE;
1391                         return;
1392                 }
1393                 if (compress_type != BTRFS_COMPRESS_NONE) {
1394                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1395                         em->compress_type = compress_type;
1396                         em->block_start = bytenr;
1397                         em->block_len = em->orig_block_len;
1398                 } else {
1399                         bytenr += btrfs_file_extent_offset(leaf, fi);
1400                         em->block_start = bytenr;
1401                         em->block_len = em->len;
1402                         if (type == BTRFS_FILE_EXTENT_PREALLOC)
1403                                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
1404                 }
1405         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
1406                 em->block_start = EXTENT_MAP_INLINE;
1407                 em->start = extent_start;
1408                 em->len = extent_end - extent_start;
1409                 /*
1410                  * Initialize orig_start and block_len with the same values
1411                  * as in inode.c:btrfs_get_extent().
1412                  */
1413                 em->orig_start = EXTENT_MAP_HOLE;
1414                 em->block_len = (u64)-1;
1415                 em->compress_type = compress_type;
1416                 if (compress_type != BTRFS_COMPRESS_NONE)
1417                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1418         } else {
1419                 btrfs_err(fs_info,
1420                           "unknown file extent item type %d, inode %llu, offset %llu, "
1421                           "root %llu", type, btrfs_ino(inode), extent_start,
1422                           root->root_key.objectid);
1423         }
1424 }
1425
1426 /*
1427  * Returns the end offset (non inclusive) of the file extent item the given path
1428  * points to. If it points to an inline extent, the returned offset is rounded
1429  * up to the sector size.
1430  */
1431 u64 btrfs_file_extent_end(const struct btrfs_path *path)
1432 {
1433         const struct extent_buffer *leaf = path->nodes[0];
1434         const int slot = path->slots[0];
1435         struct btrfs_file_extent_item *fi;
1436         struct btrfs_key key;
1437         u64 end;
1438
1439         btrfs_item_key_to_cpu(leaf, &key, slot);
1440         ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
1441         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1442
1443         if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
1444                 end = btrfs_file_extent_ram_bytes(leaf, fi);
1445                 end = ALIGN(key.offset + end, leaf->fs_info->sectorsize);
1446         } else {
1447                 end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1448         }
1449
1450         return end;
1451 }