SMB3: Add defines for new negotiate contexts

See the latest MS-SMB2 protocol specification updates.
These will be needed for implementing compression support
on the wire for example.
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/smb2pdu.c

@@ -459,10 +459,7 @@ smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,
 	return rc;
 }
 
-
-#define SMB2_PREAUTH_INTEGRITY_CAPABILITIES	cpu_to_le16(1)
-#define SMB2_ENCRYPTION_CAPABILITIES		cpu_to_le16(2)
-#define SMB2_POSIX_EXTENSIONS_AVAILABLE		cpu_to_le16(0x100)
+/* For explanation of negotiate contexts see MS-SMB2 section 2.2.3.1 */
 
 static void
 build_preauth_ctxt(struct smb2_preauth_neg_context *pneg_ctxt)

fs/cifs/smb2pdu.h

@@ -251,6 +251,14 @@ struct smb2_negotiate_req {
 #define SMB2_NT_FIND			0x00100000
 #define SMB2_LARGE_FILES		0x00200000
 
+
+/* Negotiate Contexts - ContextTypes. See MS-SMB2 section 2.2.3.1 for details */
+#define SMB2_PREAUTH_INTEGRITY_CAPABILITIES	cpu_to_le16(1)
+#define SMB2_ENCRYPTION_CAPABILITIES		cpu_to_le16(2)
+#define SMB2_COMPRESSION_CAPABILITIES		cpu_to_le16(3)
+#define SMB2_NETNAME_NEGOTIATE_CONTEXT_ID	cpu_to_le16(5)
+#define SMB2_POSIX_EXTENSIONS_AVAILABLE		cpu_to_le16(0x100)
+
 struct smb2_neg_context {
 	__le16	ContextType;
 	__le16	DataLength;
@@ -288,6 +296,24 @@ struct smb2_encryption_neg_context {
 	__le16	Ciphers[1]; /* Ciphers[0] since only one used now */
 } __packed;
 
+/* See MS-SMB2 2.2.3.1.3 */
+#define SMB3_COMPRESS_NONE	0x0000
+#define SMB3_COMPRESS_LZNT1	0x0001
+#define SMB3_COMPRESS_LZ77	0x0002
+#define SMB3_COMPRESS_LZ77_HUFF	0x0003
+
+struct smb2_compression_capabilities_context {
+	__le16	CompressionAlgorithmCount;
+	__u16	Padding;
+	__u32	Reserved;
+	__u16	CompressionAlgorithms[1];
+} __packed;
+
+/*
+ * For smb2_netname_negotiate_context_id See MS-SMB2 2.2.3.1.4.
+ * Its struct simply contains NetName, an array of Unicode characters
+ */
+
 #define POSIX_CTXT_DATA_LEN	16
 struct smb2_posix_neg_context {
 	__le16	ContextType; /* 0x100 */