On Tue, Feb 07, 2017 at 11:02:03AM -0800, James Bottomley wrote: > > Another option would be to require something like a project as used > > for project quotas as the root. This would also be conveniant as it > > could storge the used remapping tables. > > So this would be like the current project quota except set on a > subtree? I could see it being done that way but I don't see what > advantage it has over using flags in the subtree itself (the mapping is > known based on the mount namespace, so there's really only a single bit > of information to store). projects (which are the underling concept for project quotas) are per-subtree in practice - the flag is set on an inode and then all directories and files underneath inherit the project ID, hardlinking outside a project is prohinited.