Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756024AbaGHAxM (ORCPT ); Mon, 7 Jul 2014 20:53:12 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55571 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753531AbaGGXyR (ORCPT ); Mon, 7 Jul 2014 19:54:17 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bill , NeilBrown Subject: [PATCH 3.15 106/122] md: flush writes before starting a recovery. Date: Mon, 7 Jul 2014 16:57:48 -0700 Message-Id: <20140707235737.423020524@linuxfoundation.org> X-Mailer: git-send-email 2.0.0.254.g50f84e3 In-Reply-To: <20140707235734.234226883@linuxfoundation.org> References: <20140707235734.234226883@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit 133d4527eab8d199a62eee6bd433f0776842df2e upstream. When we write to a degraded array which has a bitmap, we make sure the relevant bit in the bitmap remains set when the write completes (so a 're-add' can quickly rebuilt a temporarily-missing device). If, immediately after such a write starts, we incorporate a spare, commence recovery, and skip over the region where the write is happening (because the 'needs recovery' flag isn't set yet), then that write will not get to the new device. Once the recovery finishes the new device will be trusted, but will have incorrect data, leading to possible corruption. We cannot set the 'needs recovery' flag when we start the write as we do not know easily if the write will be "degraded" or not. That depends on details of the particular raid level and particular write request. This patch fixes a corruption issue of long standing and so it suitable for any -stable kernel. It applied correctly to 3.0 at least and will minor editing to earlier kernels. Reported-by: Bill Tested-by: Bill Link: http://lkml.kernel.org/r/53A518BB.60709@sbcglobal.net Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7491,6 +7491,19 @@ void md_do_sync(struct md_thread *thread rdev->recovery_offset < j) j = rdev->recovery_offset; rcu_read_unlock(); + + /* If there is a bitmap, we need to make sure all + * writes that started before we added a spare + * complete before we start doing a recovery. + * Otherwise the write might complete and (via + * bitmap_endwrite) set a bit in the bitmap after the + * recovery has checked that bit and skipped that + * region. + */ + if (mddev->bitmap) { + mddev->pers->quiesce(mddev, 1); + mddev->pers->quiesce(mddev, 0); + } } printk(KERN_INFO "md: %s of RAID array %s\n", desc, mdname(mddev)); -- 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/