Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762364AbXEXAkk (ORCPT ); Wed, 23 May 2007 20:40:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761486AbXEXAgs (ORCPT ); Wed, 23 May 2007 20:36:48 -0400 Received: from filer.fsl.cs.sunysb.edu ([130.245.126.2]:40235 "EHLO filer.fsl.cs.sunysb.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761262AbXEXAge (ORCPT ); Wed, 23 May 2007 20:36:34 -0400 From: "Josef 'Jeff' Sipek" To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: akpm@linux-foundation.org, Erez Zadok , "Josef 'Jeff' Sipek" Subject: [PATCH 16/21] Unionfs: Disallow setting leftmost branch to readonly Date: Wed, 23 May 2007 20:36:06 -0400 Message-Id: <11799669732839-git-send-email-jsipek@cs.sunysb.edu> X-Mailer: git-send-email 1.5.2.rc1.165.gaf9b In-Reply-To: <11799669712090-git-send-email-jsipek@cs.sunysb.edu> References: <11799669712090-git-send-email-jsipek@cs.sunysb.edu> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2157 Lines: 51 From: Erez Zadok Unionfs requires the leftmost branch to be writeable for copyup to work properly and simply. If, through branch-management commands (add, delete, or mode change), the leftmost branch will becomes readonly, then return an error (and tell the user to use "remount,ro" if they want a readonly union). [jsipek: fixed up to apply cleanly] Signed-off-by: Erez Zadok Signed-off-by: Josef 'Jeff' Sipek --- fs/unionfs/super.c | 16 ++++++++++++---- 1 files changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/unionfs/super.c b/fs/unionfs/super.c index 3dee863..446faf8 100644 --- a/fs/unionfs/super.c +++ b/fs/unionfs/super.c @@ -629,12 +629,20 @@ static int unionfs_remount_fs(struct super_block *sb, int *flags, out_no_change: /****************************************************************** - * WE'RE ALMOST DONE: see if we need to allocate a small-sized new - * vector, copy the vectors to their correct place, release the - * refcnt of the older ones, and return. - * Also handle invalidating any pages that will have to be re-read. + * WE'RE ALMOST DONE: check if leftmost branch might be read-only, + * see if we need to allocate a small-sized new vector, copy the + * vectors to their correct place, release the refcnt of the older + * ones, and return. Also handle invalidating any pages that will + * have to be re-read. *******************************************************************/ + if (!(tmp_data[0].branchperms & MAY_WRITE)) { + printk("unionfs: leftmost branch cannot be read-only " + "(use \"remount,ro\" to create a read-only union)\n"); + err = -EINVAL; + goto out_release; + } + /* (re)allocate space for new pointers to hidden dentry */ size = new_branches * sizeof(struct unionfs_data); new_data = krealloc(tmp_data, size, GFP_KERNEL); -- 1.5.2.rc1.165.gaf9b - 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/