From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: [PATCH 03/35] writeback: prevent duplicate balance_dirty_pages_ratelimited() calls Date: Mon, 13 Dec 2010 22:46:49 +0800 Message-ID: <20101213150326.733656527@intel.com> References: <20101213144646.341970461@intel.com> Return-path: Received: from kanga.kvack.org ([205.233.56.17]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PSA1C-0001Xb-1e for glkm-linux-mm-2@m.gmane.org; Mon, 13 Dec 2010 16:08:51 +0100 Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 6BD946B008A for ; Mon, 13 Dec 2010 10:08:48 -0500 (EST) Content-Disposition: inline; filename=writeback-fix-duplicate-bdp-calls.patch Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Jan Kara , Wu Fengguang , Christoph Hellwig , Trond Myklebust , Dave Chinner , Theodore Ts'o , Chris Mason , Peter Zijlstra , Mel Gorman , Rik van Riel , KOSAKI Motohiro , Greg Thelen , Minchan Kim , linux-mm , linux-fsdevel@vger.kernel.org, LKML List-Id: linux-mm.kvack.org When dd in 512bytes, balance_dirty_pages_ratelimited() used to be called 8 times for the same page, even if the page is only dirtied once. Fix it with a (slightly racy) PageDirty() test. Signed-off-by: Wu Fengguang --- mm/filemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- linux-next.orig/mm/filemap.c 2010-12-13 21:45:57.000000000 +0800 +++ linux-next/mm/filemap.c 2010-12-13 21:46:11.000000000 +0800 @@ -2244,6 +2244,7 @@ static ssize_t generic_perform_write(str long status = 0; ssize_t written = 0; unsigned int flags = 0; + unsigned int dirty; /* * Copies from kernel address space cannot fail (NFSD is a big user). @@ -2292,6 +2293,7 @@ again: pagefault_enable(); flush_dcache_page(page); + dirty = PageDirty(page); mark_page_accessed(page); status = a_ops->write_end(file, mapping, pos, bytes, copied, page, fsdata); @@ -2318,7 +2320,8 @@ again: pos += copied; written += copied; - balance_dirty_pages_ratelimited(mapping); + if (!dirty) + balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); -- 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