[PATCH 4/8] fs/namespace: implement mnt_clone_direct()

[Hannes Reinecke]

Implement mnt_clone_direct() to just clone an existing vfsmount.

Signed-off-by: Hannes Reinecke <hare at kernel.org>
---
 fs/namespace.c        | 11 +++++++++++
 include/linux/mount.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/fs/namespace.c b/fs/namespace.c
index fe919abd2f01..dfde8e3c7131 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1477,6 +1477,17 @@ struct vfsmount *mnt_clone_internal(const struct path *path)
 	return &p->mnt;
 }
 
+struct vfsmount *mnt_clone_direct(struct vfsmount *mnt, struct dentry *dentry)
+{
+	struct mount *p;
+
+	p = clone_mnt(real_mount(mnt), dentry, CL_SLAVE);
+	if (IS_ERR(p))
+		return ERR_CAST(p);
+	p->mnt.mnt_flags |= MNT_INTERNAL;
+	return &p->mnt;
+}
+
 /*
  * Returns the mount which either has the specified mnt_id, or has the next
  * smallest id afer the specified one.
diff --git a/include/linux/mount.h b/include/linux/mount.h
index acfe7ef86a1b..7e7e7d66c302 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -75,6 +75,7 @@ extern void mnt_drop_write_file(struct file *file);
 extern void mntput(struct vfsmount *mnt);
 extern struct vfsmount *mntget(struct vfsmount *mnt);
 extern void mnt_make_shortterm(struct vfsmount *mnt);
+extern struct vfsmount *mnt_clone_direct(struct vfsmount *mnt, struct dentry *dentry);
 extern struct vfsmount *mnt_clone_internal(const struct path *path);
 extern bool __mnt_is_readonly(const struct vfsmount *mnt);
 extern bool mnt_may_suid(struct vfsmount *mnt);
-- 
2.51.0