From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o585f1tj193948 for ; Tue, 8 Jun 2010 00:41:01 -0500 Received: from mx2.suse.de (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 74DD43A149F for ; Mon, 7 Jun 2010 22:43:32 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by cuda.sgi.com with ESMTP id woekTSMvkqTggbFG for ; Mon, 07 Jun 2010 22:43:32 -0700 (PDT) Date: Tue, 8 Jun 2010 15:43:30 +1000 From: Nick Piggin Subject: Re: [PATCH 4/6] writeback: pay attention to wbc->nr_to_write in write_cache_pages Message-ID: <20100608054330.GS26335@laptop> References: <1275957487-23633-1-git-send-email-david@fromorbit.com> <1275957487-23633-5-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1275957487-23633-5-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com On Tue, Jun 08, 2010 at 10:38:05AM +1000, Dave Chinner wrote: > From: Dave Chinner > > If a filesystem writes more than one page in ->writepage, write_cache_pages > fails to notice this and continues to attempt writeback when wbc->nr_to_write > has gone negative - this trace was captured from XFS: > > > wbc_writeback_start: towrt=1024 > wbc_writepage: towrt=1024 > wbc_writepage: towrt=0 > wbc_writepage: towrt=-1 > wbc_writepage: towrt=-5 > wbc_writepage: towrt=-21 > wbc_writepage: towrt=-85 > > This has adverse effects on filesystem writeback behaviour. write_cache_pages() > needs to terminate after a certain number of pages are written, not after a > certain number of calls to ->writepage are made. This is a regression > introduced by 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4 ("vfs: Add > no_nrwrite_index_update writeback control flag"), but cannot be reverted > directly due to subsequent bug fixes that have gone in on top of it. > > Signed-off-by: Dave Chinner > Reviewed-by: Christoph Hellwig Acked-by: Nick Piggin _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs