Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753410Ab0DTDkQ (ORCPT ); Mon, 19 Apr 2010 23:40:16 -0400 Received: from bld-mail13.adl6.internode.on.net ([150.101.137.98]:55394 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752157Ab0DTDkN (ORCPT ); Mon, 19 Apr 2010 23:40:13 -0400 Date: Tue, 20 Apr 2010 13:40:05 +1000 From: Dave Chinner To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, xfs@oss.sgi.com Subject: [PATCH 5/4] writeback: limit write_cache_pages integrity scanning to current EOF Message-ID: <20100420034005.GA15130@dastard> References: <1271731314-5893-1-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1271731314-5893-1-git-send-email-david@fromorbit.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2221 Lines: 56 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. Signed-off-by: Dave Chinner --- mm/page-writeback.c | 15 +++++++++++++++ 1 files changed, 15 insertions(+), 0 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index e22af84..4ba2728 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -852,7 +852,22 @@ int write_cache_pages(struct address_space *mapping, if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) range_whole = 1; cycled = 1; /* ignore range_cyclic tests */ + + /* + * If this is a data integrity sync, cap the writeback to the + * current end of file. Any extension to the file that occurs + * after this is a new write and we don't need to write those + * pages out to fulfil our data integrity requirements. If we + * try to write them out, we can get stuck in this scan until + * the concurrent writer stops adding dirty pages and extending + * EOF. + */ + if (wbc->sync_mode == WB_SYNC_ALL && + wbc->range_end == LLONG_MAX) { + end = i_size_read(mapping->host) >> PAGE_CACHE_SHIFT; + } } + retry: done_index = index; while (!done && (index <= end)) { -- 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/