From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752777AbaEWJro (ORCPT ); Fri, 23 May 2014 05:47:44 -0400 Received: from mail-ee0-f44.google.com ([74.125.83.44]:57230 "EHLO mail-ee0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752181AbaEWJoB (ORCPT ); Fri, 23 May 2014 05:44:01 -0400 From: Miklos Szeredi To: viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, akpm@linux-foundation.org, apw@canonical.com, nbd@openwrt.org, neilb@suse.de, jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu, dhowells@redhat.com, sedat.dilek@gmail.com, hooanon05@yahoo.co.jp, mszeredi@suse.cz Subject: [PATCH 04/13] vfs: introduce clone_private_mount() Date: Fri, 23 May 2014 11:43:34 +0200 Message-Id: <1400838223-30844-5-git-send-email-miklos@szeredi.hu> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1400838223-30844-1-git-send-email-miklos@szeredi.hu> References: <1400838223-30844-1-git-send-email-miklos@szeredi.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi Overlayfs needs a private clone of the mount, so create a function for this and export to modules. Signed-off-by: Miklos Szeredi --- fs/namespace.c | 27 +++++++++++++++++++++++++++ include/linux/mount.h | 3 +++ 2 files changed, 30 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index 182bc41cd887..9ad57948f527 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1550,6 +1550,33 @@ void drop_collected_mounts(struct vfsmount *mnt) namespace_unlock(); } +/** + * clone_private_mount - create a private clone of a path + * + * This creates a new vfsmount, which will be the clone of @path. The new will + * not be attached anywhere in the namespace and will be private (i.e. changes + * to the originating mount won't be propagated into this). + * + * Release with mntput(). + */ +struct vfsmount *clone_private_mount(struct path *path) +{ + struct mount *old_mnt = real_mount(path->mnt); + struct mount *new_mnt; + + if (IS_MNT_UNBINDABLE(old_mnt)) + return ERR_PTR(-EINVAL); + + down_read(&namespace_sem); + new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); + up_read(&namespace_sem); + if (IS_ERR(new_mnt)) + return ERR_CAST(new_mnt); + + return &new_mnt->mnt; +} +EXPORT_SYMBOL_GPL(clone_private_mount); + int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, struct vfsmount *root) { diff --git a/include/linux/mount.h b/include/linux/mount.h index 839bac270904..31617fcfac8c 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -74,6 +74,9 @@ extern void mnt_pin(struct vfsmount *mnt); extern void mnt_unpin(struct vfsmount *mnt); extern int __mnt_is_readonly(struct vfsmount *mnt); +struct path; +extern struct vfsmount *clone_private_mount(struct path *path); + struct file_system_type; extern struct vfsmount *vfs_kern_mount(struct file_system_type *type, int flags, const char *name, -- 1.8.1.4