Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753692AbZIRGkL (ORCPT ); Fri, 18 Sep 2009 02:40:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753369AbZIRGkJ (ORCPT ); Fri, 18 Sep 2009 02:40:09 -0400 Received: from brick.kernel.dk ([93.163.65.50]:50806 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752759AbZIRGkF (ORCPT ); Fri, 18 Sep 2009 02:40:05 -0400 Date: Fri, 18 Sep 2009 08:40:07 +0200 From: Jens Axboe To: Trond Myklebust Cc: Linux Kernel , a.p.zijlstra@chello.nl Subject: Re: [PATCH] nfs: fix bdi_unregister() before sb kill Message-ID: <20090918064006.GU23126@kernel.dk> References: <20090917124233.GJ23126@kernel.dk> <20090917194027.GS23126@kernel.dk> <1253229410.2783.16.camel@heimdal.trondhjem.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1253229410.2783.16.camel@heimdal.trondhjem.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1637 Lines: 40 On Thu, Sep 17 2009, Trond Myklebust wrote: > On Thu, 2009-09-17 at 21:40 +0200, Jens Axboe wrote: > > On Thu, Sep 17 2009, Jens Axboe wrote: > > > Hi, > > > > > > This can cause a hang on NFS umount, since the bdi gets pruned before we > > > flush any pending dirty IO. Peter, can you check whether it fixes your > > > issue? > > > > There's another problem with NFS && backing devices. NFS may call > > bdi_destroy() on a bdi without ever called bdi_init(). This was always a > > bad idea, now it's an issue. > > > > So, Trond, can I safely add a server->flags private flag to indicate > > that we have called bdi_init()? Then nfs_free_server() knows when to > > call bdi_destroy(). Seems like the safest fix, since error handling is > > currently 'just call nfs_free_server()'. > > Urgh... Is there any reason why we can't just move the call to > bdi_init() into nfs_bdi_register()? It seems bizarre to have to > initialise the backing_dev_info twice like this... No reason at all, I don't know why it was implemented that way originally. > If we do that, then we can just look at the BDI_registered state flag in > order to figure out if we need to call bdi_unregister() That's not exactly pretty either, diving into internal bdi details to find out if we did an init/register of the device. BDI_registered is just a debug flag, it may even go away again shortly. -- Jens Axboe -- 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/