On Mon, Apr 13, 2020 at 09:00:25PM -0700, ira.weiny@xxxxxxxxx wrote: > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > Encryption and DAX are incompatible. Changing the DAX mode due to a > change in Encryption mode is wrong without a corresponding > address_space_operations update. > > Make the 2 options mutually exclusive by returning an error if DAX was > set first. > > Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> The encryption flag is inherited from the containing directory, and directories can't have the DAX flag set, so anything we do in ext4_set_context() will be safety belt / sanity checking in nature. But we *do* need to figure out what we do with mount -o dax=always when the file system might have encrypted files. My previous comments about the verity flag and dax flag applies here. Also note that encrypted files are read/write so we must never allow the combination of ENCRPYT_FL and DAX_FL. So that may be something where we should teach __ext4_iget() to check for this, and declare the file system as corrupted if it sees this combination. (For VERITY_FL && DAX_FL that is a combo that we might want to support in the future, so that's probably a case where arguably, we should just ignore the DAX_FL for now.) - Ted
