On 2015-10-16 13:41, Andreas Gruenbacher wrote: > On Fri, Oct 16, 2015 at 7:31 PM, Austin S Hemmelgarn > wrote: >> I would like to re-iterate, on both XFS and ext4, I _really_ think this >> should be a ro_compat flag, and not an incompat one. If a person has the >> ability to mount the FS (even if it's a read-only mount), then they by >> definition have read access to the file or partition that the filesystem is >> contained in, which means that any ACL's stored on the filesystem are >> functionally irrelevant, > > It is unfortunately not safe to make such a file system accessible to > other users, so the feature is not strictly read-only compatible. > OK, seeing as I wasn't particularly clear as to why I object to this in my other e-mail, let's try this again. Can you please explain exactly why it isn't safe to make such a filesystem accessible to other users? Because that _really_ sounds to me like you are trying to rely on this being un-mountable on a kernel that doesn't support richacls to try and provide the illusion of better security.