On Thu, Apr 15, 2021 at 09:55:37AM +0200, Christoph Hellwig wrote: > On Thu, Apr 15, 2021 at 09:49:21AM +0200, Christian Brauner wrote: > > However, as a general way of advertising to users that ext4 supports > > idmapped mounts I don't necessarily see a problem with that. It doesn't > > have implications for other filesystems and ext4 already advertises > > other features in a similar way. > > I still think that is a very bad idea. idmapped mounts are foremost > a VFS feature, with just a tiny bit of glue in every file system that > does not affect the on-disk format. So any discovery for it needs > to be using VFS infrastructure. IMHO just trying to mount is the > proper way to do it, but if people want some other form of discovery > it needs to be something in generic code. I agree with you there. I think fsinfo() (Arguably a slimmed-down version of it.) would've been the best place for this.
