From: Qu Wenruo <wqu@suse.com>
To: linux-btrfs@vger.kernel.org
Subject: [PATCH 0/2] btrfs: tree-checker: Add checks to detect missing INODE_ITEM
Date: Mon, 26 Aug 2019 15:40:37 +0800 [thread overview]
Message-ID: <20190826074039.28517-1-wqu@suse.com> (raw)
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.
In this patchset, we will enhance existing check_dir_item() and
check_extent_data_item() to detect missing INODE_ITEM first, then add
INODE_REF checker.
So now we can cover the INODE_ITEM missing case in tree-checker without
much cost, but achieve the check which is normally done by btrfs-check.
(I'm already a little concerned about the fact that kernel tree-checker
is getting stronger and stronger while btrfs-progs can't fix all
problems)
Of course, there is still a limitation that the first key of a leaf
can't be verified, but we have already cover all the rest keys, which is
way better than "good enough"(TM).
Qu Wenruo (2):
btrfs: tree-checker: Try to detect missing INODE_ITEM
btrfs: tree-checker: Add check for INODE_REF
fs/btrfs/tree-checker.c | 78 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 76 insertions(+), 2 deletions(-)
--
2.23.0
next reply other threads:[~2019-08-26 7:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 7:40 Qu Wenruo [this message]
2019-08-26 7:40 ` [PATCH 1/2] btrfs: tree-checker: Try to detect missing INODE_ITEM Qu Wenruo
2019-08-26 11:46 ` Nikolay Borisov
2019-08-26 7:40 ` [PATCH 2/2] btrfs: tree-checker: Add check for INODE_REF Qu Wenruo
2019-08-26 11:45 ` Nikolay Borisov
2019-08-26 11:50 ` Qu Wenruo
2019-09-23 15:45 ` David Sterba
2019-09-23 15:47 ` David Sterba
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