From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752725Ab0GMHvW (ORCPT ); Tue, 13 Jul 2010 03:51:22 -0400 Received: from bld-mail19.adl2.internode.on.net ([150.101.137.104]:37589 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752129Ab0GMHvV (ORCPT ); Tue, 13 Jul 2010 03:51:21 -0400 From: Dave Chinner To: xfs@oss.sgi.com Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk Subject: [PATCH 2/2] blkdev: check for valid request queue before issuing flush Date: Tue, 13 Jul 2010 17:50:50 +1000 Message-Id: <1279007450-10457-3-git-send-email-david@fromorbit.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1279007450-10457-1-git-send-email-david@fromorbit.com> References: <1279007450-10457-1-git-send-email-david@fromorbit.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Chinner Issuing a blkdev_issue_flush() on an unconfigured loop device causes a panic as q->make_request_fn is not configured. This can occur when trying to mount the unconfigured loop device as an XFS filesystem. There are no guards that catch the bio before the request function is called because we don't add a payload to the bio. Instead, manually check this case as soon as we have a pointer to the queue to flush. Signed-off-by: Dave Chinner --- block/blk-barrier.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/block/blk-barrier.c b/block/blk-barrier.c index 0d710c9..0fd766e 100644 --- a/block/blk-barrier.c +++ b/block/blk-barrier.c @@ -319,6 +319,15 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, if (!q) return -ENXIO; + /* + * some block devices may not have their queue correctly set up here + * (e.g. loop device without a backing file) and so issuing a flush + * here will panic. Ensure there is a request function before issuing + * the barrier. + */ + if (!q->make_request_fn) + return -ENXIO; + bio = bio_alloc(gfp_mask, 0); bio->bi_end_io = bio_end_empty_barrier; bio->bi_bdev = bdev; -- 1.7.1