Re: Does /var/shm still need to be mounted?

From: Tigran Aivazian (
Date: Fri Jun 02 2000 - 17:18:19 EST

On Fri, 2 Jun 2000, Tigran Aivazian wrote:

> On 2 Jun 2000, H. Peter Anvin wrote:
> > Followup to: <Pine.LNX.4.21.0006021321300.2581-100000@saturn.homenet>
> > By author: Tigran Aivazian <>
> > In newsgroup:
> > >
> > > did you look at kern_mount/umount interface that went into the kernel
> > > recently? Things like shm and pipefs should (and already are) mounted
> > > under artificially constructed root mountpoints like "pipe:" which are not
> > > visible for namelookups coming from userspace. Ok, it is not the case for
> > > shm currently (it is mounted on /) but perhaps it should be (i.e. the way
> > > root dentry should be allocated as for pipefs using d_alloc() directly
> > > instead of using generic d_alloc_root())?
> > >
> > > I cc'd Al Viro as I suspect he knows the answer to the above question.
> > >
> >
> > No, shmfs actually needs a real path. Not for SysV IPC, but for POSIX
> > IPC.
> >
> that is not an answer to the question I asked. If you read the sentence
> that has the question mark (not the subject) you will see that I was
> asking if the kern_mounted (and not the user-mounted) instance of shmfs
> has to be mounted under "/" or can it be done like for pipefs under an
> artificially constructed "shm:" like "pipe:"
> For this reason I cc'd Al Viro also - not to ask him a question on POSIX
> vs System V IPC but a question on root dentry allocation differences of
> pipefs vs shmfs. (I cc'd him again)

actually, on the second thought, I can imagine a requirement where your
answer actually answers my very question - but then another question
remains - why does it have to be specifically "/"? Or do you mean "since /
is always mounted then by assigning its name to root dentry of shmfs
instance we guarantee that it (in some sense) corresponds to a real path"?


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

This archive was generated by hypermail 2b29 : Wed Jun 07 2000 - 21:00:16 EST