fs/cifs: don't translate SFM_SLASH (U+F026) to backslash

BugLink: https://bugs.launchpad.net/bugs/1798770

[ Upstream commit c15e3f19 ]

When a Mac client saves an item containing a backslash to a file server
the backslash is represented in the CIFS/SMB protocol as as U+F026.
Before this change, listing a directory containing an item with a
backslash in its name will return that item with the backslash
represented with a true backslash character (U+005C) because
convert_sfm_character mapped U+F026 to U+005C when interpretting the
CIFS/SMB protocol response.  However, attempting to open or stat the
path using a true backslash will result in an error because
convert_to_sfm_char does not map U+005C back to U+F026 causing the
CIFS/SMB request to be made with the backslash represented as U+005C.

This change simply prevents the U+F026 to U+005C conversion from
happenning.  This is analogous to how the code does not do any
translation of UNI_SLASH (U+F000).
Signed-off-by: Jon Kuhn <jkuhn@barracuda.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/cifs/cifs_unicode.c

@@ -101,9 +101,6 @@ convert_sfm_char(const __u16 src_char, char *target)
 	case SFM_LESSTHAN:
 		*target = '<';
 		break;
-	case SFM_SLASH:
-		*target = '\\';
-		break;
 	case SFM_SPACE:
 		*target = ' ';
 		break;