From: Trond Myklebust Subject: Re: [PATCH 5/9] rpc: call release_pipe only on last close Date: Mon, 10 Nov 2008 15:21:55 -0500 Message-ID: <1226348515.7599.52.camel@heimdal.trondhjem.org> References: <1226264683-28650-2-git-send-email-bfields@citi.umich.edu> <1226264683-28650-3-git-send-email-bfields@citi.umich.edu> <1226264683-28650-4-git-send-email-bfields@citi.umich.edu> <1226264683-28650-5-git-send-email-bfields@citi.umich.edu> <1226264683-28650-6-git-send-email-bfields@citi.umich.edu> <1226344297.7599.41.camel@heimdal.trondhjem.org> <20081110194900.GD19053@fieldses.org> <1226347279.7599.47.camel@heimdal.trondhjem.org> <20081110200727.GE19053@fieldses.org> <1226347898.7599.49.camel@heimdal.trondhjem.org> <20081110201708.GF19053@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain Cc: aglo@citi.umich.edu, kwc@citi.umich.edu, linux-nfs@vger.kernel.org To: "J. Bruce Fields" Return-path: Received: from mx2.netapp.com ([216.240.18.37]:59473 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751498AbYKJUWR (ORCPT ); Mon, 10 Nov 2008 15:22:17 -0500 In-Reply-To: <20081110201708.GF19053@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, 2008-11-10 at 15:17 -0500, J. Bruce Fields wrote: > On Mon, Nov 10, 2008 at 03:11:38PM -0500, Trond Myklebust wrote: > > On Mon, 2008-11-10 at 15:07 -0500, J. Bruce Fields wrote: > > > > > Again, I'm dealing with that case by calling release_pipe() from > > > rpc_close_pipes(), just as the current code does--the only change being > > > to do that only when there are still opens: > > > > > > last_close = rpci->nreaders != 0 || rpci->nwriters != 0; > > > rpci->nreaders = 0; > > > ... > > > rpci->nwriters = 0; > > > if (last_close && ops->release_pipe) > > > ops->release_pipe(inode); > > > > Which means that if the kernel calls rpc_close_pipes() before gssd has > > managed to close, then you _NEVER_ call ops->release_pipe()... > > So, I take "before gssd has managed to close" to mean that gssd is still > holding the file open. Thus the statement > > last_close = rpci->nreaders != 0 || rpci->nwriters != 0; > > evaluates to true; either nreaders or nwriters must be nonzero. > > (And note the open and close code that modifes nreaders and nwriters is > all serialized with this code by the i_mutex.) > > --b. Exactly... That is a very common situation that happens pretty much every time you unmount. The kernel closes the pipe on its side, and removes the dentry; it doesn't wait for gssd to close the pipe. Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com