From patchwork Mon Nov 26 08:44:50 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miao Xie X-Patchwork-Id: 1800801 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id EC5753FC23 for ; Mon, 26 Nov 2012 08:44:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754093Ab2KZIo2 (ORCPT ); Mon, 26 Nov 2012 03:44:28 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:11030 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754086Ab2KZIo1 (ORCPT ); Mon, 26 Nov 2012 03:44:27 -0500 X-IronPort-AV: E=Sophos;i="4.83,319,1352044800"; d="scan'208";a="6276200" Received: from unknown (HELO tang.cn.fujitsu.com) ([10.167.250.3]) by song.cn.fujitsu.com with ESMTP; 26 Nov 2012 16:42:42 +0800 Received: from fnstmail02.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id qAQ8iQjb006745 for ; Mon, 26 Nov 2012 16:44:26 +0800 Received: from [10.167.225.199] ([10.167.225.199]) by fnstmail02.fnst.cn.fujitsu.com (Lotus Domino Release 8.5.3) with ESMTP id 2012112616440282-61083 ; Mon, 26 Nov 2012 16:44:02 +0800 Message-ID: <50B32C02.1090106@cn.fujitsu.com> Date: Mon, 26 Nov 2012 16:44:50 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Linux Btrfs Subject: [PATCH 6/9] Btrfs: get write access when removing a device References: <50B32ABF.7040803@cn.fujitsu.com> In-Reply-To: <50B32ABF.7040803@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/26 16:44:02, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/26 16:44:03, Serialize complete at 2012/11/26 16:44:03 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Steps to reproduce: # mkfs.btrfs -d single -m single # mount -o ro # mount -o ro # mount -o remount,rw # umount # btrfs device delete We can remove a device from a R/O filesystem. The reason is that we just check the R/O flag of the super block object. It is not enough, because the kernel may set the R/O flag only for the mount point. We need invoke mnt_want_write_file() to do a full check. Signed-off-by: Miao Xie --- fs/btrfs/ioctl.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index c4bcba5..5921bb9 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2248,16 +2248,18 @@ out: return ret; } -static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg) +static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) { + struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root; struct btrfs_ioctl_vol_args *vol_args; int ret; if (!capable(CAP_SYS_ADMIN)) return -EPERM; - if (root->fs_info->sb->s_flags & MS_RDONLY) - return -EROFS; + ret = mnt_want_write_file(file); + if (ret) + return ret; mutex_lock(&root->fs_info->volume_mutex); if (root->fs_info->balance_ctl) { @@ -2278,6 +2280,7 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg) kfree(vol_args); out: mutex_unlock(&root->fs_info->volume_mutex); + mnt_drop_write_file(file); return ret; } @@ -3766,7 +3769,7 @@ long btrfs_ioctl(struct file *file, unsigned int case BTRFS_IOC_ADD_DEV: return btrfs_ioctl_add_dev(root, argp); case BTRFS_IOC_RM_DEV: - return btrfs_ioctl_rm_dev(root, argp); + return btrfs_ioctl_rm_dev(file, argp); case BTRFS_IOC_FS_INFO: return btrfs_ioctl_fs_info(root, argp); case BTRFS_IOC_DEV_INFO: