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authorRoss Zwisler <ross.zwisler@linux.intel.com>2017-10-12 18:54:08 +0300
committerTheodore Ts'o <tytso@mit.edu>2017-10-12 18:54:08 +0300
commite9072d859df3e0f2c3ba450f0d1739595c2d5d13 (patch)
tree8e91f9ce1bd1fdaf439d246e9d8045fd418a61d2 /fs/ext4/ioctl.c
parent559db4c6d784ceedc2a5418ced4d357cb843e221 (diff)
downloadlinux-e9072d859df3e0f2c3ba450f0d1739595c2d5d13.tar.xz
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.c16
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);