From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o59LAAUs032677 for ; Wed, 9 Jun 2010 16:10:10 -0500 Received: from smtp1.linux-foundation.org (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id AD51815919C6 for ; Wed, 9 Jun 2010 14:15:45 -0700 (PDT) Received: from smtp1.linux-foundation.org (smtp1.linux-foundation.org [140.211.169.13]) by cuda.sgi.com with ESMTP id UEeOcOHFSbEFW85X for ; Wed, 09 Jun 2010 14:15:45 -0700 (PDT) Date: Wed, 9 Jun 2010 14:12:08 -0700 From: Andrew Morton Subject: Re: [PATCH 3/3] writeback: limit write_cache_pages integrity scanning to current EOF Message-Id: <20100609141208.a1babcf4.akpm@linux-foundation.org> In-Reply-To: <1276043840-1946-4-git-send-email-david@fromorbit.com> References: <1276043840-1946-1-git-send-email-david@fromorbit.com> <1276043840-1946-4-git-send-email-david@fromorbit.com> Mime-Version: 1.0 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, stable@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com On Wed, 9 Jun 2010 10:37:20 +1000 Dave Chinner wrote: > From: Dave Chinner > > sync can currently take a really long time if a concurrent writer is > extending a file. The problem is that the dirty pages on the address > space grow in the same direction as write_cache_pages scans, so if > the writer keeps ahead of writeback, the writeback will not > terminate until the writer stops adding dirty pages. > > For a data integrity sync, we only need to write the pages dirty at > the time we start the writeback, so we can stop scanning once we get > to the page that was at the end of the file at the time the scan > started. > > This will prevent operations like copying a large file preventing > sync from completing as it will not write back pages that were > dirtied after the sync was started. This does not impact the > existing integrity guarantees, as any dirty page (old or new) > within the EOF range at the start of the scan will still be > captured. > > This patch will not prevent sync from blocking on large writes into > holes. That requires more complex intervention while this patch only > addresses the common append-case of this sync holdoff. > I don't know if this regression sucks enough to warrant backporting, but the fix is simple and is independent of [1/3] and [2/3]. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs