From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 82AEC6B021A for ; Wed, 26 May 2010 11:58:06 -0400 (EDT) Subject: Re: [PATCH] do_generic_file_read: clear page errors when issuing a fresh read of the page From: Larry Woodman In-Reply-To: <20100526114940.49f51028@annuminas.surriel.com> References: <20100526114940.49f51028@annuminas.surriel.com> Content-Type: text/plain Date: Wed, 26 May 2010 12:02:52 -0400 Message-Id: <1274889772.20515.103.camel@dhcp-100-19-198.bos.redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jmoyer@redhat.com, torvalds@linux-foundation.org List-ID: On Wed, 2010-05-26 at 11:49 -0400, Rik van Riel wrote: > From: Jeff Moyer > > I/O errors can happen due to temporary failures, like multipath > errors or losing network contact with the iSCSI server. Because > of that, the VM will retry readpage on the page. > > However, do_generic_file_read does not clear PG_error. This > causes the system to be unable to actually use the data in the > page cache page, even if the subsequent readpage completes > successfully! > > The function filemap_fault has had a ClearPageError before > readpage forever. This patch simply adds the same to > do_generic_file_read. > > Signed-off-by: Rik van Riel > Signed-off-by: Jeff Moyer > --- > mm/filemap.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > Index: linux-2.6.34/mm/filemap.c > =================================================================== > --- linux-2.6.34.orig/mm/filemap.c > +++ linux-2.6.34/mm/filemap.c > @@ -1106,6 +1106,12 @@ page_not_up_to_date_locked: > } > > readpage: > + /* > + * A previous I/O error may have been due to temporary > + * failures, eg. multipath errors. > + * PG_error will be set again if readpage fails. > + */ > + ClearPageError(page); > /* Start the actual read. The read will unlock the page. */ > error = mapping->a_ops->readpage(filp, page); > Acked-by: Larry Woodman -- 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/ . Don't email: email@kvack.org