From c771d683a62e5d36bc46036f5c07f4f5bb7dda61 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Fri, 24 Oct 2014 00:14:36 +0200 Subject: vfs: introduce clone_private_mount() 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 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'fs') diff --git a/fs/namespace.c b/fs/namespace.c index fbba8b17330d..5b66b2b3624d 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1686,6 +1686,33 @@ 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) { -- cgit v1.2.3-58-ga151