From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 15792] ext4_inode_inode->i_flags modification is racy
Date: Thu, 15 Apr 2010 22:31:58 GMT
Message-ID: <201004152231.o3FMVwAT001332@demeter.kernel.org>
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--- Comment #2 from Dmitry Monakhov 2010-04-15 22:31:55 ---
The oops happens because non tested branch was triggered.
./fs/ext4/extents.c
3477: if (unlikely(EXT4_I(inode)->i_flags & EXT4_EOFBLOCKS_FL)) {
if (unlikely(!eh->eh_entries)) {
EXT4_ERROR_INODE(inode,
"eh->eh_entries == 0 ee_block %d",
ex->ee_block);
### OOPS here because ex == NULL ^^^^^^^^^^^^^^^^^^^^^^^^
err = -EIO;
goto out2;
}
Bug was introduced by following commit:
commit 273df556b6ee2065bfe96edab5888d3dc9b108d8
Author: Frank Mayhar
Date: Tue Mar 2 11:46:09 2010 -0500
And in fact it is rather trivial to fix.
But most interesting question what the hell we are doing on that error path?
inode has EXT4_EOFBLOCKS_FL flag enabled but eh->eh_entries, and in fact
after adding more debug information i've found that inode is simply blockless.
i_blocks == 0, i_size == 0.
I've collected per-inode i_flag modification history (see an attachment)
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