Re: [RFC PATCH] file as directory

[Miklos Szeredi]

> > > As for unlink...  How do you deal with having that thing
> > > mounted, mounting something _under_ it (so that vfsmount would be kept
> > > busy) and then unlinking that sucker?
> >
> > Yeah, that's a good point.  Current patch doesn't deal with that.
> > Simplest solution could be to disallow submounting these.  Don't think
> > it makes much sense anyway.
> >
> 
> Hmm, think about /your/path/qemu-disk1.img/boot ,
> /your/path/qemu-disk2.img/usr , ...

I get it.

It could probably be done with a little added complexity.  For example
when a real mount is attached onto a dir-on-file mount, the
"mountedness" is propagated up to the dentry on the next real mount.

So in that case unlink won't be allowed, even if the immediate
attachment is a dir-on-file mount.

This is tricky to do right though.

Other possibility is to detach all mount trees attached to dentry on
unlink.

Miklos
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