vfs: opencode mntget() mnt_set_mountpoint()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namespace.c

@@ -572,8 +572,9 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
 void mnt_set_mountpoint(struct mount *mnt, struct dentry *dentry,
 			struct mount *child_mnt)
 {
-	child_mnt->mnt_parent = real_mount(mntget(&mnt->mnt));
+	mnt_add_count(mnt, 1);	/* essentially, that's mntget */
 	child_mnt->mnt_mountpoint = dget(dentry);
+	child_mnt->mnt_parent = mnt;
 	spin_lock(&dentry->d_lock);
 	dentry->d_flags |= DCACHE_MOUNTED;
 	spin_unlock(&dentry->d_lock);