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| author | Theodore Ts'o <tytso@mit.edu> | 2014-03-24 14:43:12 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-03-24 14:43:12 -0400 |
| commit | 5f16f3225b06242a9ee876f07c1c9b6ed36a22b6 (patch) | |
| tree | cebecf399c2d9ef5b0a24902638cb37d2e9e092b /fs/ext4 | |
| parent | ed3654eb981fd44694b4d2a636e13f998bc10e7f (diff) | |
| download | linux-5f16f3225b06242a9ee876f07c1c9b6ed36a22b6.tar.bz2 | |
ext4: atomically set inode->i_flags in ext4_set_inode_flags()
Use cmpxchg() to atomically set i_flags instead of clearing out the
S_IMMUTABLE, S_APPEND, etc. flags and then setting them from the
EXT4_IMMUTABLE_FL, EXT4_APPEND_FL flags, since this opens up a race
where an immutable file has the immutable flag cleared for a brief
window of time.
Reported-by: John Sullivan <jsrhbz@kanargh.force9.co.uk>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/inode.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index b5e182acf9b9..df067c3c6c93 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3938,18 +3938,20 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc) void ext4_set_inode_flags(struct inode *inode) { unsigned int flags = EXT4_I(inode)->i_flags; + unsigned int new_fl = 0; - inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); if (flags & EXT4_SYNC_FL) - inode->i_flags |= S_SYNC; + new_fl |= S_SYNC; if (flags & EXT4_APPEND_FL) - inode->i_flags |= S_APPEND; + new_fl |= S_APPEND; if (flags & EXT4_IMMUTABLE_FL) - inode->i_flags |= S_IMMUTABLE; + new_fl |= S_IMMUTABLE; if (flags & EXT4_NOATIME_FL) - inode->i_flags |= S_NOATIME; + new_fl |= S_NOATIME; if (flags & EXT4_DIRSYNC_FL) - inode->i_flags |= S_DIRSYNC; + new_fl |= S_DIRSYNC; + inode_set_flags(inode, new_fl, + S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); } /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */ |