ext4: prevent data corruption with journaling + DAX

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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

...

This commit is contained in:

Ross Zwisler 2017-10-12 11:54:08 -04:00 • committed by Theodore Ts'o

parent 559db4c6d7

commit e9072d859d

2 changed files with 13 additions and 8 deletions

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5

fs/ext4/inode.c

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16

fs/ext4/ioctl.c

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