[PATCH 03/16] vfs: Implement vfs_loopback_mount

[Eric W. Biederman]

Add a helper to turn a struct path into a mount.

Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
 fs/namespace.c        | 9 +++++++++
 include/linux/mount.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/fs/namespace.c b/fs/namespace.c
index 4fb1691b4355..714778360c2b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1047,6 +1047,15 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 	return ERR_PTR(err);
 }
 
+struct vfsmount *vfs_loopback_mount(struct path *path)
+{
+	struct mount *p;
+	p = clone_mnt(real_mount(path->mnt), path->dentry, 0);
+	if (IS_ERR(p))
+		return ERR_CAST(p);
+	return &p->mnt;
+}
+
 static void cleanup_mnt(struct mount *mnt)
 {
 	/*
diff --git a/include/linux/mount.h b/include/linux/mount.h
index f822c3c11377..8f6039ad898e 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -89,6 +89,7 @@ struct file_system_type;
 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 				      int flags, const char *name,
 				      void *data);
+struct vfsmount *vfs_loopback_mount(struct path *path);
 
 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 extern void mark_mounts_for_expiry(struct list_head *mounts);
-- 
2.8.1