[CIFS] Fix build warning

Fix build warning in Shirish's recent SMB3 signing patch
which occurs when SMB2 support is disabled in Kconfig.

fs/built-in.o: In function `cifs_setup_session':
>> (.text+0xa1767): undefined reference to `generate_smb3signingkey'

Pointed out by: automated 0-DAY kernel build testing backend
Intel Open Source Technology Center

CC: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifsglob.h

@@ -365,6 +365,8 @@ struct smb_version_operations {
 	void (*set_lease_key)(struct inode *, struct cifs_fid *fid);
 	/* generate new lease key */
 	void (*new_lease_key)(struct cifs_fid *fid);
+	/* The next two functions will need to be changed to per smb session */
+	void (*generate_signingkey)(struct TCP_Server_Info *server);
 	int (*calc_signature)(struct smb_rqst *rqst,
 				   struct TCP_Server_Info *server);
 };

fs/cifs/cifsproto.h

@@ -436,7 +436,7 @@ extern int setup_ntlmv2_rsp(struct cifs_ses *, const struct nls_table *);
 extern int cifs_crypto_shash_allocate(struct TCP_Server_Info *);
 extern void cifs_crypto_shash_release(struct TCP_Server_Info *);
 extern int calc_seckey(struct cifs_ses *);
-extern int generate_smb3signingkey(struct TCP_Server_Info *);
+extern void generate_smb3signingkey(struct TCP_Server_Info *);
 
 #ifdef CONFIG_CIFS_WEAK_PW_HASH
 extern int calc_lanman_hash(const char *password, const char *cryptkey,

fs/cifs/connect.c

@@ -3841,7 +3841,8 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
 			server->sequence_number = 0x2;
 			server->session_estab = true;
 			ses->auth_key.response = NULL;
-			generate_smb3signingkey(server);
+			if (server->ops->generate_signingkey)
+				server->ops->generate_signingkey(server);
 		}
 		mutex_unlock(&server->srv_mutex);
 

fs/cifs/smb2ops.c

@@ -709,6 +709,7 @@ struct smb_version_operations smb30_operations = {
 	.get_lease_key = smb2_get_lease_key,
 	.set_lease_key = smb2_set_lease_key,
 	.new_lease_key = smb2_new_lease_key,
+	.generate_signingkey = generate_smb3signingkey,
 	.calc_signature = smb3_calc_signature,
 };
 

fs/cifs/smb2transport.c

@@ -116,7 +116,7 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	return rc;
 }
 
-int
+void
 generate_smb3signingkey(struct TCP_Server_Info *server)
 {
 	unsigned char zero = 0x0;
@@ -187,7 +187,7 @@ generate_smb3signingkey(struct TCP_Server_Info *server)
 	memcpy(server->smb3signingkey, hashptr, SMB3_SIGNKEY_SIZE);
 
 smb3signkey_ret:
-	return rc;
+	return;
 }
 
 int