From patchwork Thu Feb 9 12:44:26 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 9564459 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1932460572 for ; Thu, 9 Feb 2017 12:45:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EEB5E28499 for ; Thu, 9 Feb 2017 12:45:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E25EF284D1; Thu, 9 Feb 2017 12:45:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 997B828503 for ; Thu, 9 Feb 2017 12:45:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751795AbdBIMpv (ORCPT ); Thu, 9 Feb 2017 07:45:51 -0500 Received: from mx2.suse.de ([195.135.220.15]:34585 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751546AbdBIMpu (ORCPT ); Thu, 9 Feb 2017 07:45:50 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B2E77ADA7; Thu, 9 Feb 2017 12:44:43 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 22B3C1E10AC; Thu, 9 Feb 2017 13:44:43 +0100 (CET) From: Jan Kara To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Tejun Heo , Dan Williams , Thiago Jung Bauermann , NeilBrown , Jan Kara Subject: [PATCH 03/10] block: Revalidate i_bdev reference in bd_aquire() Date: Thu, 9 Feb 2017 13:44:26 +0100 Message-Id: <20170209124433.2626-4-jack@suse.cz> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20170209124433.2626-1-jack@suse.cz> References: <20170209124433.2626-1-jack@suse.cz> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When a device gets removed, block device inode unhashed so that it is not used anymore (bdget() will not find it anymore). Later when a new device gets created with the same device number, we create new block device inode. However there may be file system device inodes whose i_bdev still points to the original block device inode and thus we get two active block device inodes for the same device. They will share the same gendisk so the only visible differences will be that page caches will not be coherent and BDIs will be different (the old block device inode still points to unregistered BDI). Fix the problem by checking in bd_acquire() whether i_bdev still points to active block device inode and re-lookup the block device if not. That way any open of a block device happening after the old device has been removed will get correct block device inode. Signed-off-by: Jan Kara --- fs/block_dev.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 601b71b76d7f..360439373a66 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1043,13 +1043,22 @@ static struct block_device *bd_acquire(struct inode *inode) spin_lock(&bdev_lock); bdev = inode->i_bdev; - if (bdev) { + if (bdev && !inode_unhashed(bdev->bd_inode)) { bdgrab(bdev); spin_unlock(&bdev_lock); return bdev; } spin_unlock(&bdev_lock); + /* + * i_bdev references block device inode that was already shut down + * (corresponding device got removed). Remove the reference and look + * up block device inode again just in case new device got + * reestablished under the same device number. + */ + if (bdev) + bd_forget(bdev); + bdev = bdget(inode->i_rdev); if (bdev) { spin_lock(&bdev_lock);