Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9]

Andy Lutomirski [off-list ref] wrote:

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I tend to think that this *should* fail using the new API.  The semantics
of the second mount request are bizarre at best.

You still have to support existing behaviour lest you break userspace.

I assume the existing behavior is that a bind mount is created?  If so, the
new mount(8) tool could do it in user code.

You have a race there.

Also you can't currently directly create a bind mount from userspace as you
can only bind from another path point - which you may not be able to access
(either by permission failure or because it's not in your mount namespace).

David