Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753555Ab0HDPks (ORCPT ); Wed, 4 Aug 2010 11:40:48 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:54770 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754442Ab0HDPkn (ORCPT ); Wed, 4 Aug 2010 11:40:43 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=W0Q1jXKn53UB60NLhMZhEfLYMJr2Ir2SYQi3OlQM2JxNMFSTkMUanxUAStoTz7y73R cgq1hPF8DnnP8XbhteNoUZbn6WMo/zRpqfQvDZk3Yd7DZ4TfQVyikt3bjazFYTOxjD9r 4NAI914hR7X/Pk/XMKGiE10TGzdUfRYPpFu8E= Message-ID: <4C598A0B.9000301@gmail.com> Date: Wed, 04 Aug 2010 17:40:59 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.7) Gecko/20100713 Thunderbird/3.1.1 MIME-Version: 1.0 To: Jens Axboe CC: "Rafael J. Wysocki" , Linux Kernel Mailing List , Maciej Rutecki , Andrew Morton , Kernel Testers List , Network Development , Linux ACPI , Linux PM List , Linux SCSI List , Linux Wireless List , DRI , Linus Torvalds , stable@kernel.org, Maciej Rutecki Subject: [PATCH block#for-2.6.36] block_dev: always serialize exclusive open attempts References: <2dWFdr9kTFM.A.P0D.spXVMB@chimera> <4C56F30D.3020304@kernel.org> In-Reply-To: <4C56F30D.3020304@kernel.org> X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1707 Lines: 45 bd_prepare_to_claim() incorrectly allowed multiple attempts for exclusive open to progress in parallel if the attempting holders are identical. This triggered BUG_ON() as reported in the following bug. https://bugzilla.kernel.org/show_bug.cgi?id=16393 __bd_abort_claiming() is used to finish claiming blocks and doesn't work if multiple openers are inside a claiming block. Allowing multiple parallel open attempts to continue doesn't gain anything as those are serialized down in the call chain anyway. Fix it by always allowing only single open attempt in a claiming block. This problem can easily be reproduced by adding a delay after bd_prepare_to_claim() and attempting to mount two partitions of a disk. stable: only applicable to v2.6.35 Signed-off-by: Tejun Heo Reported-by: Maciej Rutecki Cc: stable@kernel.org --- fs/block_dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 99d6af8..b3171fb 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -681,8 +681,8 @@ retry: if (!bd_may_claim(bdev, whole, holder)) return -EBUSY; - /* if someone else is claiming, wait for it to finish */ - if (whole->bd_claiming && whole->bd_claiming != holder) { + /* if claiming is already in progress, wait for it to finish */ + if (whole->bd_claiming) { wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); DEFINE_WAIT(wait); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/