From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 3/4] writeback: pay attention to wbc->nr_to_write in write_cache_pages Date: Thu, 29 Apr 2010 14:39:31 -0700 Message-ID: <20100429143931.331c2bab.akpm@linux-foundation.org> References: <1271731314-5893-1-git-send-email-david@fromorbit.com> <1271731314-5893-4-git-send-email-david@fromorbit.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, "Theodore Ts'o" , linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" , xfs@oss.sgi.com To: Dave Chinner Return-path: In-Reply-To: <1271731314-5893-4-git-send-email-david@fromorbit.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com List-Id: linux-fsdevel.vger.kernel.org On Tue, 20 Apr 2010 12:41:53 +1000 Dave Chinner wrote: > 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 > Bug. AFAIT it's a regression introduced by : commit 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4 : Author: Aneesh Kumar K.V : AuthorDate: Thu Oct 16 10:09:17 2008 -0400 : Commit: Theodore Ts'o : CommitDate: Thu Oct 16 10:09:17 2008 -0400 : : vfs: Add no_nrwrite_index_update writeback control flag I suggest that what you do here is remove the local `nr_to_write' from write_cache_pages() and go back to directly using wbc->nr_to_write within the loop. And thus we restore the convention that if the fs writes back more than a single page, it subtracts (nr_written - 1) from wbc->nr_to_write. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs