init: add an init_chown helper

Add a simple helper to chown with a kernel space file name and switch
the early init code over to it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/open.c b/fs/open.c
index f62f475..49960a1 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -639,7 +639,7 @@ SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 	return do_fchmodat(AT_FDCWD, filename, mode);
 }
 
-static int chown_common(const struct path *path, uid_t user, gid_t group)
+int chown_common(const struct path *path, uid_t user, gid_t group)
 {
 	struct inode *inode = path->dentry->d_inode;
 	struct inode *delegated_inode = NULL;