CIFS: add SFM mapping for 0x01-0x1F

Hi,

attached patch adds more missing mappings for the 0x01-0x1f range. Please
review, if you're fine with it, considere it also for stable.

Björn

>From a97720c26db2ee77d4e798e3d383fcb6a348bd29 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Jacke?= <bjacke@samba.org>
Date: Wed, 31 May 2017 22:48:41 +0200
Subject: [PATCH] cifs: add SFM mapping for 0x01-0x1F

0x1-0x1F has to be mapped to 0xF001-0xF01F
Signed-off-by: Bjoern Jacke <bjacke@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifs_unicode.c

@@ -79,6 +79,10 @@ convert_sfu_char(const __u16 src_char, char *target)
 static bool
 convert_sfm_char(const __u16 src_char, char *target)
 {
+	if (src_char >= 0xF001 && src_char <= 0xF01F) {
+		*target = src_char - 0xF000;
+		return true;
+	}
 	switch (src_char) {
 	case SFM_COLON:
 		*target = ':';
@@ -417,6 +421,10 @@ static __le16 convert_to_sfm_char(char src_char, bool end_of_string)
 {
 	__le16 dest_char;
 
+	if (src_char >= 0x01 && src_char <= 0x1F) {
+		dest_char = cpu_to_le16(src_char + 0xF000);
+		return dest_char;
+	}
 	switch (src_char) {
 	case ':':
 		dest_char = cpu_to_le16(SFM_COLON);