Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030915AbaLLQ77 (ORCPT ); Fri, 12 Dec 2014 11:59:59 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:51790 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030729AbaLLQ76 (ORCPT ); Fri, 12 Dec 2014 11:59:58 -0500 Date: Fri, 12 Dec 2014 16:59:52 +0000 From: Al Viro To: Jeff Layton Cc: Linus Torvalds , 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: <20141212165952.GD22149@ZenIV.linux.org.uk> References: <1418238480-18857-1-git-send-email-jlayton@primarydata.com> <20141212021241.GA5944@ZenIV.linux.org.uk> <20141212030206.GA22149@ZenIV.linux.org.uk> <20141212065408.2f76c41e@tlielax.poochiereds.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141212065408.2f76c41e@tlielax.poochiereds.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 12, 2014 at 06:54:08AM -0500, Jeff Layton wrote: > > 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. > > I like the change overall -- it would certainly make my patch series > simpler, but what about pathwalking? We do take the fs->lock in > unlazy_walk. Is it possible we'd end up with more contention there? That would take a pathname lookup in kernel thread side of nfsd that * isn't single-component * isn't LOOKUP_ROOT one (i.e. vfs_path_lookup() or file_open_root()) and I would really hope we don't have such things. Any such a beast would allow probing the tree layout outside of what we export, to start with... AFAICS, we really don't have anything of that sort. Note that e.g. lookup_one_len() doesn't go anywhere near ->fs->lock... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/