Fix match_server check to allow for auto dialect negotiate

When using multidialect negotiate (default or specifying vers=3.0 which
allows any smb3 dialect), fix how we check for an existing server session.
Before this fix if you mounted a second time to the same server (e.g. a
different share on the same server) we would only reuse the existing smb
session if a single dialect were requested (e.g. specifying vers=2.1 or vers=3.0
or vers=3.1.1 on the mount command). If a default mount (e.g. not
specifying vers=) is done then would always create a new socket connection
and SMB3 (or SMB3.1.1) session each time we connect to a different share
on the same server rather than reusing the existing one.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/connect.c

@@ -2544,8 +2544,15 @@ static int match_server(struct TCP_Server_Info *server, struct smb_vol *vol)
 	if (vol->nosharesock)
 		return 0;
 
-	/* BB update this for smb3any and default case */
+	/* If multidialect negotiation see if existing sessions match one */
-	if ((server->vals != vol->vals) || (server->ops != vol->ops))
+	if (strcmp(vol->vals->version_string, SMB3ANY_VERSION_STRING) == 0) {
+		if (server->vals->protocol_id < SMB30_PROT_ID)
+			return 0;
+	} else if (strcmp(vol->vals->version_string,
+		   SMBDEFAULT_VERSION_STRING) == 0) {
+		if (server->vals->protocol_id < SMB21_PROT_ID)
+			return 0;
+	} else if ((server->vals != vol->vals) || (server->ops != vol->ops))
 		return 0;
 
 	if (!net_eq(cifs_net_ns(server), current->nsproxy->net_ns))

fs/cifs/smb1ops.c

@@ -1233,6 +1233,7 @@ struct smb_version_operations smb1_operations = {
 
 struct smb_version_values smb1_values = {
 	.version_string = SMB1_VERSION_STRING,
+	.protocol_id = SMB10_PROT_ID,
 	.large_lock_type = LOCKING_ANDX_LARGE_FILES,
 	.exclusive_lock_type = 0,
 	.shared_lock_type = LOCKING_ANDX_SHARED_LOCK,

fs/cifs/smb2pdu.h

@@ -227,6 +227,7 @@ struct smb2_negotiate_req {
 } __packed;
 
 /* Dialects */
+#define SMB10_PROT_ID 0x0000 /* local only, not sent on wire w/CIFS negprot */
 #define SMB20_PROT_ID 0x0202
 #define SMB21_PROT_ID 0x0210
 #define SMB30_PROT_ID 0x0300