cifs: Identify a connection by a conn_id.

Introduced a new field conn_id in TCP_Server_Info structure.
This is a non-persistent unique identifier maintained by the client
for a connection to a file server. For this, a global counter named
tcpSesNextId is maintained. On allocating a new TCP_Server_Info,
this counter is incremented and assigned.

Changed the dynamic tracepoints related to reconnects and
crediting to be more informative (with conn_id printed).
Debugging a crediting issue helped me understand the
important things to print here.

Always call dynamic tracepoints outside the scope of spinlocks.
To do this, copy out the credits and in_flight fields of the
server struct before dropping the lock.

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

1 files changed, 47 insertions, 16 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 84d1f265aa1d..fe171ccbe8e3 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -63,17 +63,19 @@ smb2_add_credits(struct TCP_Server_Info *server,
 		 const struct cifs_credits *credits, const int optype)
 {
 	int *val, rc = -1;
+	int scredits, in_flight;
 	unsigned int add = credits->value;
 	unsigned int instance = credits->instance;
 	bool reconnect_detected = false;
+	bool reconnect_with_invalid_credits = false;
 
 	spin_lock(&server->req_lock);
 	val = server->ops->get_credits_field(server, optype);
 
 	/* eg found case where write overlapping reconnect messed up credits */
 	if (((optype & CIFS_OP_MASK) == CIFS_NEG_OP) && (*val != 0))
-		trace_smb3_reconnect_with_invalid_credits(server->CurrentMid,
-			server->hostname, *val, add);
+		reconnect_with_invalid_credits = true;
+
 	if ((instance == 0) || (instance == server->reconnect_instance))
 		*val += add;
 	else
@@ -99,14 +101,26 @@ smb2_add_credits(struct TCP_Server_Info *server,
 			server->oplock_credits++;
 		}
 	}
+	scredits = *val;
+	in_flight = server->in_flight;
 	spin_unlock(&server->req_lock);
 	wake_up(&server->request_q);
 
 	if (reconnect_detected) {
+		trace_smb3_reconnect_detected(server->CurrentMid,
+			server->conn_id, server->hostname, scredits, add, in_flight);
+
 		cifs_dbg(FYI, "trying to put %d credits from the old server instance %d\n",
 			 add, instance);
 	}
 
+	if (reconnect_with_invalid_credits) {
+		trace_smb3_reconnect_with_invalid_credits(server->CurrentMid,
+			server->conn_id, server->hostname, scredits, add, in_flight);
+		cifs_dbg(FYI, "Negotiate operation when server credits is non-zero. Optype: %d, server credits: %d, credits added: %d\n",
+			 optype, scredits, add);
+	}
+
 	if (server->tcpStatus == CifsNeedReconnect
 	    || server->tcpStatus == CifsExiting)
 		return;
@@ -125,23 +139,30 @@ smb2_add_credits(struct TCP_Server_Info *server,
 		cifs_dbg(FYI, "disabling oplocks\n");
 		break;
 	default:
-		trace_smb3_add_credits(server->CurrentMid,
-			server->hostname, rc, add);
-		cifs_dbg(FYI, "%s: added %u credits total=%d\n", __func__, add, rc);
+		/* change_conf rebalanced credits for different types */
+		break;
 	}
+
+	trace_smb3_add_credits(server->CurrentMid,
+			server->conn_id, server->hostname, scredits, add, in_flight);
+	cifs_dbg(FYI, "%s: added %u credits total=%d\n", __func__, add, scredits);
 }
 
 static void
 smb2_set_credits(struct TCP_Server_Info *server, const int val)
 {
+	int scredits, in_flight;
+
 	spin_lock(&server->req_lock);
 	server->credits = val;
 	if (val == 1)
 		server->reconnect_instance++;
+	scredits = server->credits;
+	in_flight = server->in_flight;
 	spin_unlock(&server->req_lock);
 
 	trace_smb3_set_credits(server->CurrentMid,
-			server->hostname, val, val);
+			server->conn_id, server->hostname, scredits, val, in_flight);
 	cifs_dbg(FYI, "%s: set %u credits\n", __func__, val);
 
 	/* don't log while holding the lock */
@@ -173,7 +194,7 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 		      unsigned int *num, struct cifs_credits *credits)
 {
 	int rc = 0;
-	unsigned int scredits;
+	unsigned int scredits, in_flight;
 
 	spin_lock(&server->req_lock);
 	while (1) {
@@ -210,17 +231,18 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 				DIV_ROUND_UP(*num, SMB2_MAX_BUFFER_SIZE);
 			credits->instance = server->reconnect_instance;
 			server->credits -= credits->value;
-			scredits = server->credits;
 			server->in_flight++;
 			if (server->in_flight > server->max_in_flight)
 				server->max_in_flight = server->in_flight;
 			break;
 		}
 	}
+	scredits = server->credits;
+	in_flight = server->in_flight;
 	spin_unlock(&server->req_lock);
 
 	trace_smb3_add_credits(server->CurrentMid,
-			server->hostname, scredits, -(credits->value));
+			server->conn_id, server->hostname, scredits, -(credits->value), in_flight);
 	cifs_dbg(FYI, "%s: removed %u credits total=%d\n",
 			__func__, credits->value, scredits);
 
@@ -233,14 +255,14 @@ smb2_adjust_credits(struct TCP_Server_Info *server,
 		    const unsigned int payload_size)
 {
 	int new_val = DIV_ROUND_UP(payload_size, SMB2_MAX_BUFFER_SIZE);
-	int scredits;
+	int scredits, in_flight;
 
 	if (!credits->value || credits->value == new_val)
 		return 0;
 
 	if (credits->value < new_val) {
 		trace_smb3_too_many_credits(server->CurrentMid,
-				server->hostname, 0, credits->value - new_val);
+				server->conn_id, server->hostname, 0, credits->value - new_val, 0);
 		cifs_server_dbg(VFS, "request has less credits (%d) than required (%d)",
 				credits->value, new_val);
 
@@ -250,9 +272,13 @@ smb2_adjust_credits(struct TCP_Server_Info *server,
 	spin_lock(&server->req_lock);
 
 	if (server->reconnect_instance != credits->instance) {
+		scredits = server->credits;
+		in_flight = server->in_flight;
 		spin_unlock(&server->req_lock);
+
 		trace_smb3_reconnect_detected(server->CurrentMid,
-			server->hostname, 0, 0);
+			server->conn_id, server->hostname, scredits,
+			credits->value - new_val, in_flight);
 		cifs_server_dbg(VFS, "trying to return %d credits to old session\n",
 			 credits->value - new_val);
 		return -EAGAIN;
@@ -260,15 +286,18 @@ smb2_adjust_credits(struct TCP_Server_Info *server,
 
 	server->credits += credits->value - new_val;
 	scredits = server->credits;
+	in_flight = server->in_flight;
 	spin_unlock(&server->req_lock);
 	wake_up(&server->request_q);
-	credits->value = new_val;
 
 	trace_smb3_add_credits(server->CurrentMid,
-			server->hostname, scredits, credits->value - new_val);
+			server->conn_id, server->hostname, scredits,
+			credits->value - new_val, in_flight);
 	cifs_dbg(FYI, "%s: adjust added %u credits total=%d\n",
 			__func__, credits->value - new_val, scredits);
 
+	credits->value = new_val;
+
 	return 0;
 }
 
@@ -2371,7 +2400,7 @@ static bool
 smb2_is_status_pending(char *buf, struct TCP_Server_Info *server)
 {
 	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)buf;
-	int scredits;
+	int scredits, in_flight;
 
 	if (shdr->Status != STATUS_PENDING)
 		return false;
@@ -2380,11 +2409,13 @@ smb2_is_status_pending(char *buf, struct TCP_Server_Info *server)
 		spin_lock(&server->req_lock);
 		server->credits += le16_to_cpu(shdr->CreditRequest);
 		scredits = server->credits;
+		in_flight = server->in_flight;
 		spin_unlock(&server->req_lock);
 		wake_up(&server->request_q);
 
 		trace_smb3_add_credits(server->CurrentMid,
-				server->hostname, scredits, le16_to_cpu(shdr->CreditRequest));
+				server->conn_id, server->hostname, scredits,
+				le16_to_cpu(shdr->CreditRequest), in_flight);
 		cifs_dbg(FYI, "%s: status pending add %u credits total=%d\n",
 				__func__, le16_to_cpu(shdr->CreditRequest), scredits);
 	}