Return-Path: linux-nfs-owner@vger.kernel.org Received: from zeniv.linux.org.uk ([195.92.253.2]:49042 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751217AbaLLDCJ (ORCPT ); Thu, 11 Dec 2014 22:02:09 -0500 Date: Fri, 12 Dec 2014 03:02:06 +0000 From: Al Viro To: Linus Torvalds Cc: Jeff Layton , Bruce Fields , Linux Kernel Mailing List , Linux NFS Mailing List , Tejun Heo , NeilBrown Subject: Re: [PATCH v2 00/16] nfsd/sunrpc: add support for a workqueue-based nfsd Message-ID: <20141212030206.GA22149@ZenIV.linux.org.uk> References: <1418238480-18857-1-git-send-email-jlayton@primarydata.com> <20141212021241.GA5944@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Dec 11, 2014 at 06:29:37PM -0800, Linus Torvalds wrote: > On Thu, Dec 11, 2014 at 6:12 PM, Al Viro 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.