From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [PATCH 02/10] ovl: minimal remount support. Date: Mon, 06 Sep 2010 10:50:28 +1000 Message-ID: <20100906005028.20775.41803.stgit@localhost.localdomain> References: <20100906004829.20775.68828.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Miklos Szeredi Return-path: In-Reply-To: <20100906004829.20775.68828.stgit@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org As overlayfs reflects the 'readonly' mount status in write-access to the upper filesystem, we must handle remount and either drop or take write access when the ro status changes. Signed-off-by: NeilBrown --- fs/overlayfs/overlayfs.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-) diff --git a/fs/overlayfs/overlayfs.c b/fs/overlayfs/overlayfs.c index 0ddfeec..4e032e8 100644 --- a/fs/overlayfs/overlayfs.c +++ b/fs/overlayfs/overlayfs.c @@ -1685,8 +1685,28 @@ static void ovl_put_super(struct super_block *sb) kfree(ufs); } +static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data) +{ + int flags = *flagsp; + struct ovl_fs *ufs = sb->s_fs_info; + + /* When remounting rw or ro, we need to adjust the write access to the + * upper fs. + */ + if (((flags ^ sb->s_flags) & MS_RDONLY) == 0) + /* No change to readonly status */ + return 0; + + if (flags & MS_RDONLY) { + mnt_drop_write(ufs->upper_mnt); + return 0; + } else + return mnt_want_write(ufs->upper_mnt); +} + static const struct super_operations ovl_super_operations = { .put_super = ovl_put_super, + .remount_fs = ovl_remount_fs, }; struct ovl_config {