f2fs: remove a redundant conditional expression

Avoid checking is_inode repeatedly, and make the logic
a little bit clearer.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -1996,10 +1996,10 @@ static inline block_t datablock_addr(struct inode *inode,
 	raw_node = F2FS_NODE(node_page);
 
 	/* from GC path only */
-	if (!inode) {
-		if (is_inode)
+	if (is_inode) {
+		if (!inode)
 			base = offset_in_addr(&raw_node->i);
-	} else if (f2fs_has_extra_attr(inode) && is_inode) {
+		else if (f2fs_has_extra_attr(inode))
 			base = get_extra_isize(inode);
 	}