Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751489AbWHYUOx (ORCPT ); Fri, 25 Aug 2006 16:14:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751497AbWHYUOx (ORCPT ); Fri, 25 Aug 2006 16:14:53 -0400 Received: from pat.uio.no ([129.240.10.4]:17356 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S1751489AbWHYUOv (ORCPT ); Fri, 25 Aug 2006 16:14:51 -0400 Subject: Re: [PATCH 4/4] nfs: deadlock prevention for NFS From: Trond Myklebust To: Peter Zijlstra Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Indan Zupancic , Evgeniy Polyakov , Daniel Phillips , Rik van Riel , David Miller In-Reply-To: <20060825154027.24271.43168.sendpatchset@twins> References: <20060825153946.24271.42758.sendpatchset@twins> <20060825154027.24271.43168.sendpatchset@twins> Content-Type: text/plain Date: Fri, 25 Aug 2006 16:14:40 -0400 Message-Id: <1156536880.5927.29.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=-3.061, required 12, autolearn=disabled, AWL 1.94, UIO_MAIL_IS_INTERNAL -5.00) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4333 Lines: 141 Grumble... If your patches are targetting NFS, could you please at the very least Cc nfs@lists.sourceforge.net and/or myself. On Fri, 2006-08-25 at 17:40 +0200, Peter Zijlstra wrote: > Provide a proper a_ops->swapfile() implementation for NFS. This will > set the NFS socket to SOCK_VMIO and put the socket reconnection under > PF_MEMALLOC (I hope this is enough, otherwise more work needs to be done). > > Signed-off-by: Peter Zijlstra > --- > fs/nfs/file.c | 21 ++++++++++++++++++++- > include/linux/sunrpc/xprt.h | 4 +++- > net/sunrpc/xprtsock.c | 16 ++++++++++++++++ > 3 files changed, 39 insertions(+), 2 deletions(-) > > Index: linux-2.6/fs/nfs/file.c > =================================================================== > --- linux-2.6.orig/fs/nfs/file.c > +++ linux-2.6/fs/nfs/file.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -317,7 +318,25 @@ static int nfs_release_page(struct page > > static int nfs_swapfile(struct address_space *mapping, int enable) > { > - return 0; > + int err = -EINVAL; > + struct rpc_clnt *client = NFS_CLIENT(mapping->host); > + struct sock *sk = client->cl_xprt->inet; > + > + if (enable) { > + client->cl_xprt->swapper = 1; > + /* > + * keep one extra sock reference so the reserve won't dip > + * when the socket gets reconnected. > + */ > + sk_adjust_memalloc(1, 1); > + err = sk_set_vmio(sk); > + } else if (client->cl_xprt->swapper) { > + client->cl_xprt->swapper = 0; > + sk_adjust_memalloc(-1, -1); > + err = sk_clear_vmio(sk); > + } > + > + return err; > } This all belongs in net/sunrpc/xprtsock.c. The NFS code has no business screwing around with the internals of the sunrpc transport. > const struct address_space_operations nfs_file_aops = { > Index: linux-2.6/net/sunrpc/xprtsock.c > =================================================================== > --- linux-2.6.orig/net/sunrpc/xprtsock.c > +++ linux-2.6/net/sunrpc/xprtsock.c > @@ -1014,6 +1014,7 @@ static void xs_udp_connect_worker(void * > { > struct rpc_xprt *xprt = (struct rpc_xprt *) args; > struct socket *sock = xprt->sock; > + unsigned long pflags = current->flags; > int err, status = -EIO; > > if (xprt->shutdown || xprt->addr.sin_port == 0) > @@ -1021,6 +1022,9 @@ static void xs_udp_connect_worker(void * > > dprintk("RPC: xs_udp_connect_worker for xprt %p\n", xprt); > > + if (xprt->swapper) > + current->flags |= PF_MEMALLOC; > + > /* Start by resetting any existing state */ > xs_close(xprt); > > @@ -1054,6 +1058,9 @@ static void xs_udp_connect_worker(void * > xprt->sock = sock; > xprt->inet = sk; > > + if (xprt->swapper) > + sk_set_vmio(sk); > + > write_unlock_bh(&sk->sk_callback_lock); > } > xs_udp_do_set_buffer_size(xprt); > @@ -1061,6 +1068,7 @@ static void xs_udp_connect_worker(void * > out: > xprt_wake_pending_tasks(xprt, status); > xprt_clear_connecting(xprt); > + current->flags = pflags; > } > > /* > @@ -1097,11 +1105,15 @@ static void xs_tcp_connect_worker(void * > { > struct rpc_xprt *xprt = (struct rpc_xprt *)args; > struct socket *sock = xprt->sock; > + unsigned long pflags = current->flags; > int err, status = -EIO; > > if (xprt->shutdown || xprt->addr.sin_port == 0) > goto out; > > + if (xprt->swapper) > + current->flags |= PF_MEMALLOC; > + > dprintk("RPC: xs_tcp_connect_worker for xprt %p\n", xprt); > > if (!xprt->sock) { > @@ -1170,10 +1182,14 @@ static void xs_tcp_connect_worker(void * > break; > } > } > + > + if (xprt->swapper) > + sk_set_vmio(xprt->inet); > out: > xprt_wake_pending_tasks(xprt, status); > out_clear: > xprt_clear_connecting(xprt); > + current->flags = pflags; > } How does this guarantee that the socket reconnection won't fail? Also, what about the case of rpc_malloc()? Can't that cause rpciod to deadlock when you add NFS swap into the equation? Cheers, Trond - 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/