On Mon, Sep 11, 2017 at 11:05:22PM -0600, Ross Zwisler wrote: > If an inode has inline data it is currently prevented from using DAX by a > check in ext4_set_inode_flags(). When the inode grows inline data via > ext4_create_inline_data() or removes its inline data via > ext4_destroy_inline_data_nolock(), the value of S_DAX can change. > > Currently these changes are unsafe because we don't hold off page faults > and I/O, write back dirty radix tree entries and invalidate all mappings. > There are also issues with mm-level races when changing the value of S_DAX, > as well as issues with the VM_MIXEDMAP flag: > > https://www.spinics.net/lists/linux-xfs/msg09859.html > > The unsafe transition of S_DAX can reliably cause data corruption, as shown > by the following fstest: > > https://patchwork.kernel.org/patch/9948381/ > > Fix this issue by preventing the DAX mount option from being used on > filesystems that were created to support inline data. Inline data is an > option given to mkfs.ext4. > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > CC: stable@xxxxxxxxxxxxxxx Thanks, applied. - Ted
