ext4: use ERR_PTR() abstraction for ext4_append()

Use ERR_PTR()/IS_ERR() abstraction instead of passing in a separate
pointer to an integer for the error code, as a code cleanup.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -707,6 +707,8 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
 	/* ensure we send some value back into *errp */
 	*errp = 0;
 
+	if (create && err == 0)
+		err = -ENOSPC;	/* should never happen */
 	if (err < 0)
 		*errp = err;
 	if (err <= 0)