Messages in this thread | | | Date | Wed, 17 Jun 2009 09:09:47 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH 00/17] [RFC] AFS: Implement OpenAFS pioctls(version)s |
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On Wed, 17 Jun 2009, Andreas Dilger wrote: > > What about opening the mountpoint (which HAS to be available) and then > calling an ioctl() on that?
It's very hard to "open the mountpoint" in user space. How would you even do it? Remember: we're not living in the 1980's any more, and disco is dead. ABBA may have made a comeback, but static mountpoints are long gone, and won't be coming back.
These days, you can mount individual files, you can have per-process mounts, and automounters have been a fact for a long time.
So I _agree_ that pioctl's are problematic, but please don't argue against them using _stupid_ arguments. And "open the mountpoint" really is a stupid argument. It not only isn't possible to do in user space, but you may well want to do operations on a particular path, not just the mount.
So you'd need to open the file itself. Which might be a symlink or a device node, depending on the exact semantics of pioctl.
We've traditionally had that magic "open with flag=3" to do a magic open of device files without waiting, and we have O_NOFOLLOW to open symlinks without following them (sadly, it just errors out, rather than opening the symlink, but that's another detail).
So I think it should be solvable some way, but not by trying to find the mount point.
Linus
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