f2fs: skip punching hole in special condition

Now punching hole in directory is not supported in f2fs, so let's limit file
type in punch_hole().

In addition, in punch_hole if offset is exceed file size, we should skip
punching hole.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -658,6 +658,13 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len)
 	loff_t off_start, off_end;
 	int ret = 0;
 
+	if (!S_ISREG(inode->i_mode))
+		return -EOPNOTSUPP;
+
+	/* skip punching hole beyond i_size */
+	if (offset >= inode->i_size)
+		return ret;
+
 	ret = f2fs_convert_inline_data(inode, MAX_INLINE_DATA + 1, NULL);
 	if (ret)
 		return ret;