ksmbd: don't terminate inactive sessions after a few seconds

Steve reported that inactive sessions are terminated after a few
seconds. ksmbd terminate when receiving -EAGAIN error from
kernel_recvmsg(). -EAGAIN means there is no data available in timeout.
So ksmbd should keep connection with unlimited retries instead of
terminating inactive sessions.

Cc: stable@vger.kernel.org
Reported-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/connection.c

@@ -298,7 +298,7 @@ int ksmbd_conn_handler_loop(void *p)
 		kvfree(conn->request_buf);
 		conn->request_buf = NULL;
 
-		size = t->ops->read(t, hdr_buf, sizeof(hdr_buf));
+		size = t->ops->read(t, hdr_buf, sizeof(hdr_buf), -1);
 		if (size != sizeof(hdr_buf))
 			break;
 
@@ -344,7 +344,7 @@ int ksmbd_conn_handler_loop(void *p)
 		 * We already read 4 bytes to find out PDU size, now
 		 * read in PDU
 		 */
-		size = t->ops->read(t, conn->request_buf + 4, pdu_size);
+		size = t->ops->read(t, conn->request_buf + 4, pdu_size, 2);
 		if (size < 0) {
 			pr_err("sock_read failed: %d\n", size);
 			break;

fs/ksmbd/connection.h

@@ -114,7 +114,8 @@ struct ksmbd_transport_ops {
 	int (*prepare)(struct ksmbd_transport *t);
 	void (*disconnect)(struct ksmbd_transport *t);
 	void (*shutdown)(struct ksmbd_transport *t);
-	int (*read)(struct ksmbd_transport *t, char *buf, unsigned int size);
+	int (*read)(struct ksmbd_transport *t, char *buf,
+		    unsigned int size, int max_retries);
 	int (*writev)(struct ksmbd_transport *t, struct kvec *iovs, int niov,
 		      int size, bool need_invalidate_rkey,
 		      unsigned int remote_key);

fs/ksmbd/transport_rdma.c

@@ -670,7 +670,7 @@ static int smb_direct_post_recv(struct smb_direct_transport *t,
 }
 
 static int smb_direct_read(struct ksmbd_transport *t, char *buf,
-			   unsigned int size)
+			   unsigned int size, int unused)
 {
 	struct smb_direct_recvmsg *recvmsg;
 	struct smb_direct_data_transfer *data_transfer;

fs/ksmbd/transport_tcp.c

@@ -291,16 +291,18 @@ static int ksmbd_tcp_run_kthread(struct interface *iface)
 
 /**
  * ksmbd_tcp_readv() - read data from socket in given iovec
- * @t:		TCP transport instance
- * @iov_orig:	base IO vector
- * @nr_segs:	number of segments in base iov
- * @to_read:	number of bytes to read from socket
+ * @t:			TCP transport instance
+ * @iov_orig:		base IO vector
+ * @nr_segs:		number of segments in base iov
+ * @to_read:		number of bytes to read from socket
+ * @max_retries:	maximum retry count
  *
  * Return:	on success return number of bytes read from socket,
  *		otherwise return error number
  */
 static int ksmbd_tcp_readv(struct tcp_transport *t, struct kvec *iov_orig,
-			   unsigned int nr_segs, unsigned int to_read)
+			   unsigned int nr_segs, unsigned int to_read,
+			   int max_retries)
 {
 	int length = 0;
 	int total_read;
@@ -308,7 +310,6 @@ static int ksmbd_tcp_readv(struct tcp_transport *t, struct kvec *iov_orig,
 	struct msghdr ksmbd_msg;
 	struct kvec *iov;
 	struct ksmbd_conn *conn = KSMBD_TRANS(t)->conn;
-	int max_retry = 2;
 
 	iov = get_conn_iovec(t, nr_segs);
 	if (!iov)
@@ -335,14 +336,23 @@ static int ksmbd_tcp_readv(struct tcp_transport *t, struct kvec *iov_orig,
 		} else if (conn->status == KSMBD_SESS_NEED_RECONNECT) {
 			total_read = -EAGAIN;
 			break;
-		} else if ((length == -ERESTARTSYS || length == -EAGAIN) &&
-			   max_retry) {
+		} else if (length == -ERESTARTSYS || length == -EAGAIN) {
+			/*
+			 * If max_retries is negative, Allow unlimited
+			 * retries to keep connection with inactive sessions.
+			 */
+			if (max_retries == 0) {
+				total_read = length;
+				break;
+			} else if (max_retries > 0) {
+				max_retries--;
+			}
+
 			usleep_range(1000, 2000);
 			length = 0;
-			max_retry--;
 			continue;
 		} else if (length <= 0) {
-			total_read = -EAGAIN;
+			total_read = length;
 			break;
 		}
 	}
@@ -358,14 +368,15 @@ static int ksmbd_tcp_readv(struct tcp_transport *t, struct kvec *iov_orig,
  * Return:	on success return number of bytes read from socket,
  *		otherwise return error number
  */
-static int ksmbd_tcp_read(struct ksmbd_transport *t, char *buf, unsigned int to_read)
+static int ksmbd_tcp_read(struct ksmbd_transport *t, char *buf,
+			  unsigned int to_read, int max_retries)
 {
 	struct kvec iov;
 
 	iov.iov_base = buf;
 	iov.iov_len = to_read;
 
-	return ksmbd_tcp_readv(TCP_TRANS(t), &iov, 1, to_read);
+	return ksmbd_tcp_readv(TCP_TRANS(t), &iov, 1, to_read, max_retries);
 }
 
 static int ksmbd_tcp_writev(struct ksmbd_transport *t, struct kvec *iov,