Return-Path: Received: from mx2.netapp.com ([216.240.18.37]:42898 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751541Ab0LWATV convert rfc822-to-8bit (ORCPT ); Wed, 22 Dec 2010 19:19:21 -0500 Subject: Re: [PATCH 15/15] pnfs: layout roc code Content-Type: text/plain; charset=us-ascii From: Fred Isaman In-Reply-To: <1293055210.6422.23.camel@heimdal.trondhjem.org> Date: Wed, 22 Dec 2010 19:19:19 -0500 Cc: linux-nfs@vger.kernel.org Message-Id: <8EF8E6E3-D746-4E1E-BFCB-143921A5A76E@netapp.com> References: <1292990449-20057-1-git-send-email-iisaman@netapp.com> <1292990449-20057-16-git-send-email-iisaman@netapp.com> <1293055210.6422.23.camel@heimdal.trondhjem.org> To: Trond Myklebust Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Dec 22, 2010, at 5:00 PM, Trond Myklebust wrote: > On Tue, 2010-12-21 at 23:00 -0500, Fred Isaman wrote: >> A lsyout can request return-on-close. How this interacts with the >> forgetful model of never sending LAYOUTRETURNS is a bit ambiguous. >> We forget any layouts marked roc, and wait for them to be completely >> forgotten before continuing with the close. In addition, to compensate >> for races with any inflight LAYOUTGETs, and the fact that we do not get >> any layout stateid back from the server, we set the barrier to the worst >> case scenario of current_seqid + number of outstanding LAYOUTGETS. >> >> Signed-off-by: Fred Isaman >> --- >> fs/nfs/inode.c | 1 + >> fs/nfs/nfs4_fs.h | 2 +- >> fs/nfs/nfs4proc.c | 21 +++++++++++- >> fs/nfs/nfs4state.c | 7 +++- >> fs/nfs/pnfs.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++ >> fs/nfs/pnfs.h | 28 ++++++++++++++++ >> include/linux/nfs_fs.h | 1 + >> 7 files changed, 138 insertions(+), 5 deletions(-) >> >> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c >> index 43a69da..c64bb40 100644 >> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h >> index 29d504d..90515de 100644 >> --- a/include/linux/nfs_fs.h >> +++ b/include/linux/nfs_fs.h >> @@ -190,6 +190,7 @@ struct nfs_inode { >> struct rw_semaphore rwsem; >> >> /* pNFS layout information */ >> + struct rpc_wait_queue lo_rpcwaitq; >> struct pnfs_layout_hdr *layout; >> #endif /* CONFIG_NFS_V4*/ >> #ifdef CONFIG_NFS_FSCACHE > > I believe that I've asked this before. Why do we need a per-inode > rpc_wait_queue just to support pnfs? That's a significant expansion of > an already bloated structure. > > Can we please either make this a single per-filesystem wait queue, or > else possibly a pool of wait queues? > > Trond This was introduced to avoid deadlocks that were occurring when we had a single wait queue. However, the deadlocks I remember were due to a combination of the fact that, at the time, we handled EAGAIN errors of IO outside the RPC code, and we sent LAYOUTRETURN on such error. Since we do neither now, I believe a single per-filesystem wait queue will suffice. Anyone disagree? Fred > > -- > Trond Myklebust > Linux NFS client maintainer > > NetApp > Trond.Myklebust@netapp.com > www.netapp.com >