From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 1A7686B0085 for ; Tue, 9 Nov 2010 21:44:56 -0500 (EST) Message-Id: <20101110024224.144021908@intel.com> Date: Wed, 10 Nov 2010 10:35:05 +0800 From: Wu Fengguang Subject: [PATCH 5/5] writeback: check skipped pages on WB_SYNC_ALL References: <20101110023500.404859581@intel.com> Content-Disposition: inline; filename=writeback-warn-sync-skipped_pages.patch Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Johannes Weiner , Wu Fengguang , Christoph Hellwig , Jan Engelhardt , LKML List-ID: In WB_SYNC_ALL mode, filesystems are not expected to skip dirty pages on temporal lock contentions or non fatal errors, otherwise sync() will return without actually syncing the skipped pages. Add a check to catch possible redirty_page_for_writepage() callers that violate this expectation. I'd recommend to keep this check in -mm tree for some time and fixup the possible warnings before pushing it to upstream. If some FS triggers this warning and it's non-trivial to fix the FS, we'll have to work out a sync retry scheme for skipped pages. Signed-off-by: Wu Fengguang --- fs/fs-writeback.c | 6 ++++++ 1 file changed, 6 insertions(+) --- linux-next.orig/fs/fs-writeback.c 2010-11-10 07:04:43.000000000 +0800 +++ linux-next/fs/fs-writeback.c 2010-11-10 07:11:03.000000000 +0800 @@ -527,6 +527,12 @@ static int writeback_sb_inodes(struct su * buffers. Skip this inode for now. */ redirty_tail(inode); + /* + * There's no logic to retry skipped pages for sync(), + * filesystems are assumed not to skip dirty pages on + * temporal lock contentions or non fatal errors. + */ + WARN_ON_ONCE(wbc->sync_mode == WB_SYNC_ALL); } spin_unlock(&inode_lock); iput(inode); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org