On 26.08.19 г. 10:40 ч., Qu Wenruo wrote:
> For the following items, key->objectid is inode number:
> - DIR_ITEM
> - DIR_INDEX
> - XATTR_ITEM
> - EXTENT_DATA
> - INODE_REF
>
> So in btrfs btree, such items must have its previous item shares the
> same objectid, e.g.:
> (257 INODE_ITEM 0)
> (257 DIR_INDEX xxx)
> (257 DIR_ITEM xxx)
> (258 INODE_ITEM 0)
> (258 INODE_REF 0)
> (258 XATTR_ITEM 0)
> (258 EXTENT_DATA 0)
>
> But if we have the following sequence, then there is definitely
> something wrong, normally some INODE_ITEM is missing, like:
> (257 INODE_ITEM 0)
> (257 DIR_INDEX xxx)
> (257 DIR_ITEM xxx)
> (258 XATTR_ITEM 0) <<< objecitd suddenly changed to 258
> (258 EXTENT_DATA 0)
>
> So just by checking the previous key for above inode based key types, we
> can detect missing inode item.
>
> For INODE_REF key type, the check will be added along with INODE_REF
> checker.
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/tree-checker.c | 25 +++++++++++++++++++++++--
> 1 file changed, 23 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index ccd5706199d7..636ce1b4566e 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -141,6 +141,19 @@ static int check_extent_data_item(struct extent_buffer *leaf,
> return -EUCLEAN;
> }
>
> + /*
> + * Previous key must have the same key->objectid (ino).
> + * It can be XATTR_ITEM, INODE_ITEM or just another EXTENT_DATA.
> + * But if objectids mismatch, it means we have a missing
> + * INODE_ITEM.
> + */
> + if (slot > 0 && prev_key->objectid != key->objectid) {
> + file_extent_err(leaf, slot,
> + "invalid previous key objectid, have %llu expect %llu",
> + prev_key->objectid, key->objectid);
> + return -EUCLEAN;
> + }
> +
> fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
>
> if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
> @@ -299,13 +312,21 @@ static void dir_item_err(const struct extent_buffer *eb, int slot,
> }
>
> static int check_dir_item(struct extent_buffer *leaf,
> - struct btrfs_key *key, int slot)
> + struct btrfs_key *key, struct btrfs_key *prev_key,
> + int slot)
> {
> struct btrfs_fs_info *fs_info = leaf->fs_info;
> struct btrfs_dir_item *di;
> u32 item_size = btrfs_item_size_nr(leaf, slot);
> u32 cur = 0;
>
> + /* Same check as in check_extent_data_item() */
> + if (slot > 0 && prev_key->objectid != key->objectid) {
> + dir_item_err(leaf, slot,
> + "invalid previous key objectid, have %llu expect %llu",
> + prev_key->objectid, key->objectid);
> + return -EUCLEAN;
> + }
> di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
> while (cur < item_size) {
> u32 name_len;
> @@ -841,7 +862,7 @@ static int check_leaf_item(struct extent_buffer *leaf,
> case BTRFS_DIR_ITEM_KEY:
> case BTRFS_DIR_INDEX_KEY:
> case BTRFS_XATTR_ITEM_KEY:
> - ret = check_dir_item(leaf, key, slot);
> + ret = check_dir_item(leaf, key, prev_key, slot);
> break;
> case BTRFS_BLOCK_GROUP_ITEM_KEY:
> ret = check_block_group_item(leaf, key, slot);
>
