Return-Path: linux-kernel-owner@vger.kernel.org From: Jeff Layton Date: Sat, 13 Dec 2014 09:06:45 -0500 To: Al Viro Cc: Jeff Layton , 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: <20141213090645.62fd5348@tlielax.poochiereds.net> In-Reply-To: <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> <20141212165952.GD22149@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: On Fri, 12 Dec 2014 16:59:52 +0000 Al Viro wrote: > 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... Ahh right. Ok, then I don't see any issue with this so far. Maybe worth letting it stew in -next once -rc1 ships? Thanks! Acked-by: Jeff Layton