On Mon, 2020-01-13 at 10:59 +0800, Ian Kent wrote: > > > 3) is _anything_ besides root directory ever created in direct > > autofs > > superblocks by anyone? If not, why does autofs_lookup() even > > bother > > to > > do anything there? IOW, why not have it return ERR_PTR(-ENOENT) > > immediately > > for direct ones? Or am I missing something and it is, in fact, > > possible > > to have the daemon create something in those? > > Short answer is no, longer answer is directories "shouldn't" ever > be created inside direct mount points. > > The thing is that the multi-mount map construct can be used with > direct mounts too, but they must always have a real mount at the > base because they are direct mounts. So processes should not be > able to walk into them while they are being mounted (constructed). > > But I'm pretty sure it's rare (maybe not done at all) that this > map construct is used with direct mounts. This isn't right. There's actually nothing stopping a user from using a direct map entry that's a multi-mount without an actual mount at its root. So there could be directories created under these, it's just not usually done. I'm pretty sure I don't check and disallow this. Ian