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| author | Ross Zwisler <ross.zwisler@linux.intel.com> | 2017-10-12 11:54:08 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2017-10-12 11:54:08 -0400 |
| commit | e9072d859df3e0f2c3ba450f0d1739595c2d5d13 (patch) | |
| tree | 8e91f9ce1bd1fdaf439d246e9d8045fd418a61d2 /fs/ext4/ioctl.c | |
| parent | 559db4c6d784ceedc2a5418ced4d357cb843e221 (diff) | |
| download | linux-e9072d859df3e0f2c3ba450f0d1739595c2d5d13.tar.gz linux-e9072d859df3e0f2c3ba450f0d1739595c2d5d13.tar.bz2 linux-e9072d859df3e0f2c3ba450f0d1739595c2d5d13.zip | |
ext4: prevent data corruption with journaling + DAX
The current code has the potential for data corruption when changing an
inode's journaling mode, as that can result in a subsequent unsafe change
in S_DAX.
I've captured an instance of this data corruption in the following fstest:
https://patchwork.kernel.org/patch/9948377/
Prevent this data corruption from happening by disallowing changes to the
journaling mode if the '-o dax' mount option was used. This means that for
a given filesystem we could have a mix of inodes using either DAX or
data journaling, but whatever state the inodes are in will be held for the
duration of the mount.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/ioctl.c')
| -rw-r--r-- | fs/ext4/ioctl.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index afb66d4ab5cf..b0b754b37c36 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -290,10 +290,20 @@ flags_err: if (err) goto flags_out; - if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) + if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) { + /* + * Changes to the journaling mode can cause unsafe changes to + * S_DAX if we are using the DAX mount option. + */ + if (test_opt(inode->i_sb, DAX)) { + err = -EBUSY; + goto flags_out; + } + err = ext4_change_inode_journal_flag(inode, jflag); - if (err) - goto flags_out; + if (err) + goto flags_out; + } if (migrate) { if (flags & EXT4_EXTENTS_FL) err = ext4_ext_migrate(inode); |