On 23.03.2018 16:48, Nikolay Borisov wrote:
> When checking the validity of a DIR_ITEM item the index variable
> is explicitly set to -1 so that the index check in find_inode_ref()
> is ignored. This is necessary due to possible name collisions in DIR_ITEMS
> (i.e multiple files with the same crc32c for their names, resulting in the
> identical key->offset). Currently the code is broken due to index being set to
> -1 at the beginning of check_dir_item and subsequently reset to the index found
> in find_inode_ref. On subsequent iterations of the while loop in check_dir_items
> we are going to erroneously perform index checking, since index is not -1 but
> whatever the index value of the last handled INODE_REF ITEM.
> Without this patch check in lowmem mode produces the following false warnings
> positivess:
>
> ERROR: root 5 INODE REF[1991456, 256] name 5ab4e28b~~~~~~~~QBXUT2GBJDRT5CB6ZWAJVDHK filetype 1 missing
>
> But the items for this name are in fact correct:
>
> ------------------SNIP------------------------
> item 13 key (256 DIR_ITEM 4227063046) itemoff 2945 itemsize 140
> location key (220890 INODE_ITEM 0) type FILE
> transid 2278 data_len 0 name_len 40
> name: 5ab4e1bb~~~~~~~~65KNTAWVJ5VD4SV2R3BKFCXL
> location key (1991456 INODE_ITEM 0) type FILE
> transid 2285 data_len 0 name_len 40
> name: 5ab4e28b~~~~~~~~QBXUT2GBJDRT5CB6ZWAJVDHK
>
> item 21 key (1991456 INODE_REF 256) itemoff 2104 itemsize 50
> index 1934146 namelen 40 name: 5ab4e28b~~~~~~~~QBXUT2GBJDRT5CB6ZWAJVDHK
> -------------------SNIP-------------------------
>
> Fix this by moving the code setting index at the beginning of the while
> loop. This ensure that for each item in DIR_ITEM we have index set
> correctly.
>
> Fixes: 564901eac7a4 ("btrfs-progs: check: introduce print_dir_item_err()")
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
Ping
> check/mode-lowmem.c | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
> index 2982e92..8bd50d1 100644
> --- a/check/mode-lowmem.c
> +++ b/check/mode-lowmem.c
> @@ -1217,14 +1217,6 @@ static int check_dir_item(struct btrfs_root *root, struct btrfs_key *di_key,
> int tmp_err;
> int need_research = 0;
>
> - /*
> - * For DIR_ITEM set index to (u64)-1, so that find_inode_ref
> - * ignore index check.
> - */
> - if (di_key->type == BTRFS_DIR_INDEX_KEY)
> - index = di_key->offset;
> - else
> - index = (u64)-1;
> begin:
> err = 0;
> cur = 0;
> @@ -1254,6 +1246,15 @@ begin:
> memset(namebuf, 0, sizeof(namebuf) / sizeof(*namebuf));
>
> while (cur < total) {
> + /*
> + * For DIR_ITEM set index to (u64)-1, so that find_inode_ref
> + * ignore index check.
> + */
> + if (di_key->type == BTRFS_DIR_INDEX_KEY)
> + index = di_key->offset;
> + else
> + index = (u64)-1;
> +
> data_len = btrfs_dir_data_len(node, di);
> tmp_err = 0;
> if (data_len)
>
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