On 03/23/2018 10:48 PM, 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 <nbori...@suse.com>
Looks good to me.
Reviewed-by: Su Yue <suy.f...@cn.fujitsu.com>
---
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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