On Tue, Jun 20, 2017 at 04:35:48PM +0200, Alexander Peganz wrote: > Hello everyone, > > I intend to provide different "views" of the data stored on btrfs subvolumes. > e.g. mount a subvolume in location A rw; and ro in location B while > also overwriting uids, gids, and permissions. > In the past I have been using fuse.bindfs for this. Now I'm trying to > find out if there is a 'native' way to do this in btrfs, and if it > works by design or by accident (I wouldn't want to rely on something > that might go away in a newer kernel version). > > So here goes: > Do different uid/gid/... mount options for different subvolumes work? No. uid= and gid= mount options don't work at all for btrfs (or on most other filesystems with their own concept of file ownership). You can't arbitrarily change the ownership of files like this -- except for filesystems like FAT, which don't have the concept at all. > Or does the first mounted subvolume "win"? See above. The options don't do anything. > Can a subvolume be mounted more than once (I guess not, but btrfs > might surprise me)? Yes. > Is there some completely different way I don't know about to do this > in btrfs that might not even have anything to do with mount options? If you want to do it, it'll _have_ to be done without mount options, because the options you're proposing to use don't work. As far as I know, there's no mount option for this in btrfs (or any other POSIX filesystem), and there are no plans to implement such a feature. > If there is no magical btrfs way, does fuse.bindfs play nice with > btrfs or should I be worried? We haven't had any complaints about it that I'm aware of. Hugo. -- Hugo Mills | I believe that it's closely correlated with the hugo@... carfax.org.uk | aeroswine coefficient http://carfax.org.uk/ | PGP: E2AB1DE4 | Adrian Bridgett
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