When lowmem fsck tries to find backref of a specified file extent, it searches inlined data ref first.
However, extent data ref contains owner root objectid, inode number and calculated offset (file offset - extent offset). The code only checks owner root objectid, not checking inode number nor calculated offset. This makes lowmem mode fails to detect any backref mismatch if there is a inlined data ref with the same owner objectid. Fix it by also checking extent data ref's objectid and offset. Fixes: b0d360b541f0 ("btrfs-progs: check: introduce function to check data backref in extent tree") Reported-by: Chris Murphy <ch...@colorremedies.com> Signed-off-by: Qu Wenruo <w...@suse.com> --- cmds-check.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/cmds-check.c b/cmds-check.c index 5c822b848608..0ceff5b7bbea 100644 --- a/cmds-check.c +++ b/cmds-check.c @@ -10411,11 +10411,11 @@ static int check_extent_data_item(struct btrfs_root *root, u64 disk_num_bytes; u64 extent_num_bytes; u64 extent_flags; + u64 offset; u32 item_size; unsigned long end; unsigned long ptr; int type; - u64 ref_root; int found_dbackref = 0; int err = 0; int ret; @@ -10431,6 +10431,7 @@ static int check_extent_data_item(struct btrfs_root *root, disk_bytenr = btrfs_file_extent_disk_bytenr(eb, fi); disk_num_bytes = btrfs_file_extent_disk_num_bytes(eb, fi); extent_num_bytes = btrfs_file_extent_num_bytes(eb, fi); + offset = btrfs_file_extent_offset(eb, fi); /* Check unaligned disk_num_bytes and num_bytes */ if (!IS_ALIGNED(disk_num_bytes, root->fs_info->sectorsize)) { @@ -10483,13 +10484,22 @@ static int check_extent_data_item(struct btrfs_root *root, ptr = (unsigned long)iref; end = (unsigned long)ei + item_size; while (ptr < end) { + u64 ref_root; + u64 ref_objectid; + u64 ref_offset; + iref = (struct btrfs_extent_inline_ref *)ptr; type = btrfs_extent_inline_ref_type(leaf, iref); dref = (struct btrfs_extent_data_ref *)(&iref->offset); if (type == BTRFS_EXTENT_DATA_REF_KEY) { ref_root = btrfs_extent_data_ref_root(leaf, dref); - if (ref_root == owner || ref_root == root->objectid) + ref_objectid = btrfs_extent_data_ref_objectid(leaf, dref); + ref_offset = btrfs_extent_data_ref_offset(leaf, dref); + + if ((ref_root == owner || ref_root == root->objectid) && + ref_objectid == fi_key.objectid && + ref_offset == fi_key.offset - offset) found_dbackref = 1; } else if (type == BTRFS_SHARED_DATA_REF_KEY) { found_dbackref = !check_tree_block_ref(root, NULL, -- 2.15.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html