On Fri, Dec 12, 2014 at 03:02:06AM +0000, Al Viro wrote: > On Thu, Dec 11, 2014 at 06:29:37PM -0800, Linus Torvalds wrote: > > On Thu, Dec 11, 2014 at 6:12 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > > > > Linus, do you see any problems with the following patch (against the mainline)? > > > > Not concpetually, but create_kthread() uses CLONE_FS, and I don't > > think it's just umask that things like nfsd want to avoid sharing. > > What about all the *other* fields? > > > > Just as an example: even if all the threads actually end up all having > > the same global root, what about contention on 'fs->lock'? > > > > I have *not* looked at the details, and maybe there's some reason I'm > > completely off, but it worries me. > > Umm... I would be very surprised if it turned out to be a problem. > nfsd really doesn't give a fuck about its cwd and root - not in the > thread side of things. And (un)exporting is (a) not on a hot path > and (b) not done from a kernel thread anyway. fh_to_dentry and friends > doesn't care about root/cwd, etc. > > I don't see anything that could cause that kind of issues. PS: I haven't checked if lustre is trying to avoid that kind of contention; it might be, but I would consider having those threads resolve _any_ kind of pathnames from root or cwd as serious bug - after all, we are not guaranteed that filesystem in question is reachable from the namespace PID 1 is running it. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
