ksmbd: add default data stream name in FILE_STREAM_INFORMATION

Windows client expect to get default stream name(::DATA) in
FILE_STREAM_INFORMATION response even if there is no stream data in file.
This patch fix update failure when writing ppt or doc files.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-By: Tom Talpey <tom@talpey.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/smb2pdu.c

@@ -4428,17 +4428,15 @@ static void get_file_stream_info(struct ksmbd_work *work,
 		file_info->NextEntryOffset = cpu_to_le32(next);
 	}
 
-	if (nbytes) {
+	if (!S_ISDIR(stat.mode)) {
 		file_info = (struct smb2_file_stream_info *)
 			&rsp->Buffer[nbytes];
 		streamlen = smbConvertToUTF16((__le16 *)file_info->StreamName,
 					      "::$DATA", 7, conn->local_nls, 0);
 		streamlen *= 2;
 		file_info->StreamNameLength = cpu_to_le32(streamlen);
-		file_info->StreamSize = S_ISDIR(stat.mode) ? 0 :
-			cpu_to_le64(stat.size);
-		file_info->StreamAllocationSize = S_ISDIR(stat.mode) ? 0 :
-			cpu_to_le64(stat.size);
+		file_info->StreamSize = 0;
+		file_info->StreamAllocationSize = 0;
 		nbytes += sizeof(struct smb2_file_stream_info) + streamlen;
 	}