On Wed, 17 Jun 2009, David Howells wrote: > Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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. > > I think what Andreas means is open the directory at the root of the mounted > tree, i.e. "/afs" for AFS, and then do an ioctl() on that that emulates > pioctl(). I agree that that is what he means. What _I_ mean is that THIS IS IMPOSSIBLE TO DO FROM USER SPACE! Try it. Not doable. User space simply doesn't know enough, and has fundamental races with mount/umount. Sure, you can try to do it by trying to parse the pathname and looking in /etc/mtab or /proc/mounts. And I guarantee that the end result will be a buggy pile of sh*t. End result: you do need a new system call. I just don't think "pioctl()" is a good one. You'd be better off with some modification of open and then use ioctl. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
