From mboxrd@z Thu Jan 1 00:00:00 1970 From: npiggin@suse.de Subject: [patch 3/9] mm: write_cache_pages writepage error fix Date: Wed, 29 Oct 2008 01:47:18 +1100 Message-ID: <20081028145734.064303000@nick.local0.net> References: <20081028144715.683011000@suse.de> Cc: linux-fsdevel@vger.kernel.org, Dave Chinner , Chris Mason To: akpm@linux-foundation.org Return-path: Received: from cantor.suse.de ([195.135.220.2]:47931 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752928AbYJ1PBM (ORCPT ); Tue, 28 Oct 2008 11:01:12 -0400 Content-Disposition: inline; filename=mm-wcp-writepage-error-fix.patch Sender: linux-fsdevel-owner@vger.kernel.org List-ID: In write_cache_pages, if ret signals a real error, but we still have some pages left in the pagevec, done would be set to 1, but the remaining pages would continue to be processed and ret will be overwritten in the process. It could easily be overwritten with success, and thus success will be returned even if there is an error. Thus the caller is told all writes succeeded, wheras in reality some did not. Fix this by bailing immediately if there is an error, and retaining the first error code. This is a data interity bug. Signed-off-by: Nick Piggin --- Index: linux-2.6/mm/page-writeback.c =================================================================== --- linux-2.6.orig/mm/page-writeback.c +++ linux-2.6/mm/page-writeback.c @@ -944,12 +944,26 @@ retry: } ret = (*writepage)(page, wbc, data); + if (unlikely(ret)) { + if (ret == AOP_WRITEPAGE_ACTIVATE) { + unlock_page(page); + ret = 0; + } else { + /* + * done_index is set past this page, + * so media errors will not choke + * background writeout for the entire + * file. This has consequences for + * range_cyclic semantics (ie. it may + * not be suitable for data integrity + * writeout). + */ + done = 1; + break; + } + } - if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) { - unlock_page(page); - ret = 0; - } - if (ret || (--nr_to_write <= 0)) + if (--nr_to_write <= 0) done = 1; if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; --