CIFS: Add capability to send SMB2 negotiate message

and add negotiate request type to let set_credits know that
we are only on negotiate stage and no need to make a decision
about disabling echos and oplocks.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/Makefile

@@ -16,4 +16,5 @@ cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o cifs_dfs_ref.o
 
 cifs-$(CONFIG_CIFS_FSCACHE) += fscache.o cache.o
 
-cifs-$(CONFIG_CIFS_SMB2) += smb2ops.o smb2maperror.o smb2transport.o smb2misc.o
+cifs-$(CONFIG_CIFS_SMB2) += smb2ops.o smb2maperror.o smb2transport.o \
+			    smb2misc.o smb2pdu.o

fs/cifs/cifsglob.h

@@ -313,6 +313,12 @@ get_rfc1002_length(void *buf)
 	return be32_to_cpu(*((__be32 *)buf));
 }
 
+static inline void
+inc_rfc1001_len(void *buf, int count)
+{
+	be32_add_cpu((__be32 *)buf, count);
+}
+
 struct TCP_Server_Info {
 	struct list_head tcp_ses_list;
 	struct list_head smb_ses_list;
@@ -393,6 +399,10 @@ struct TCP_Server_Info {
 	atomic_t in_send; /* requests trying to send */
 	atomic_t num_waiters;   /* blocked waiting to get in sendrecv */
 #endif
+#ifdef CONFIG_CIFS_SMB2
+	unsigned int	max_read;
+	unsigned int	max_write;
+#endif /* CONFIG_CIFS_SMB2 */
 };
 
 static inline unsigned int
@@ -986,7 +996,8 @@ static inline void free_dfs_info_array(struct dfs_info3_param *param,
 /* Type of request operation */
 #define   CIFS_ECHO_OP      0x080    /* echo request */
 #define   CIFS_OBREAK_OP   0x0100    /* oplock break request */
-#define   CIFS_OP_MASK     0x0180    /* mask request type */
+#define   CIFS_NEG_OP      0x0200    /* negotiate request */
+#define   CIFS_OP_MASK     0x0380    /* mask request type */
 
 /* Security Flags: indicate type of session setup needed */
 #define   CIFSSEC_MAY_SIGN	0x00001

fs/cifs/cifssmb.c

@@ -388,13 +388,6 @@ static int validate_t2(struct smb_t2_rsp *pSMB)
 	return -EINVAL;
 }
 
-static inline void inc_rfc1001_len(void *pSMB, int count)
-{
-	struct smb_hdr *hdr = (struct smb_hdr *)pSMB;
-
-	be32_add_cpu(&hdr->smb_buf_length, count);
-}
-
 int
 CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
 {

fs/cifs/smb2misc.c

@@ -199,7 +199,7 @@ static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
  * Returns the pointer to the beginning of the data area. Length of the data
  * area and the offset to it (from the beginning of the smb are also returned.
  */
-static char *
+char *
 smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 {
 	*off = 0;
@@ -218,6 +218,11 @@ smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 	 */
 	switch (hdr->Command) {
 	case SMB2_NEGOTIATE:
+		*off = le16_to_cpu(
+		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
+		*len = le16_to_cpu(
+		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
+		break;
 	case SMB2_SESSION_SETUP:
 	case SMB2_CREATE:
 	case SMB2_READ:

fs/cifs/smb2ops.c

@@ -61,7 +61,7 @@ smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add,
 	val = server->ops->get_credits_field(server, optype);
 	*val += add;
 	server->in_flight--;
-	if (server->in_flight == 0)
+	if (server->in_flight == 0 && (optype & CIFS_OP_MASK) != CIFS_NEG_OP)
 		rc = change_conf(server);
 	spin_unlock(&server->req_lock);
 	wake_up(&server->request_q);
@@ -139,6 +139,24 @@ smb2_dump_detail(void *buf)
 #endif
 }
 
+static bool
+smb2_need_neg(struct TCP_Server_Info *server)
+{
+	return server->max_read == 0;
+}
+
+static int
+smb2_negotiate(const unsigned int xid, struct cifs_ses *ses)
+{
+	int rc;
+	ses->server->CurrentMid = 0;
+	rc = SMB2_negotiate(xid, ses);
+	/* BB we probably don't need to retry with modern servers */
+	if (rc == -EAGAIN)
+		rc = -EHOSTDOWN;
+	return rc;
+}
+
 struct smb_version_operations smb21_operations = {
 	.setup_request = smb2_setup_request,
 	.check_receive = smb2_check_receive,
@@ -150,6 +168,8 @@ struct smb_version_operations smb21_operations = {
 	.find_mid = smb2_find_mid,
 	.check_message = smb2_check_message,
 	.dump_detail = smb2_dump_detail,
+	.need_neg = smb2_need_neg,
+	.negotiate = smb2_negotiate,
 };
 
 struct smb_version_values smb21_values = {