switch create_read_pipe() to alloc_file()

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

fs/pipe.c

@@ -1029,20 +1029,14 @@ void free_write_pipe(struct file *f)
 
 struct file *create_read_pipe(struct file *wrf, int flags)
 {
-	struct file *f = get_empty_filp();
+	/* Grab pipe from the writer */
+	struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
+				    &read_pipefifo_fops);
 	if (!f)
 		return ERR_PTR(-ENFILE);
 
-	/* Grab pipe from the writer */
-	f->f_path = wrf->f_path;
 	path_get(&wrf->f_path);
-	f->f_mapping = wrf->f_path.dentry->d_inode->i_mapping;
-
-	f->f_pos = 0;
 	f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
-	f->f_op = &read_pipefifo_fops;
-	f->f_mode = FMODE_READ;
-	f->f_version = 0;
 
 	return f;
 }