nvmfd: Permit setting the MAXH2CDATA value via -H

This value is advertised to the remote host for TCP associations and
determines the maximum data payload size the remote host is permitted
to transmit in a single PDU.

Sponsored by:	Chelsio Communications

usr.sbin/nvmfd/discovery.c

@@ -109,7 +109,7 @@ init_discovery(void)
 	aparams.tcp.pda = 0;
 	aparams.tcp.header_digests = header_digests;
 	aparams.tcp.data_digests = data_digests;
-	aparams.tcp.maxh2cdata = 256 * 1024;
+	aparams.tcp.maxh2cdata = maxh2cdata;
 	discovery_na = nvmf_allocate_association(NVMF_TRTYPE_TCP, true,
 	    &aparams);
 	if (discovery_na == NULL)

usr.sbin/nvmfd/internal.h

@@ -24,6 +24,7 @@ extern bool data_digests;
 extern bool header_digests;
 extern bool flow_control_disable;
 extern bool kernel_io;
+extern uint32_t maxh2cdata;
 
 /* controller.c */
 void	controller_handle_admin_commands(struct controller *c,

usr.sbin/nvmfd/io.c

@@ -57,7 +57,7 @@ init_io(const char *subnqn)
 	aparams.tcp.pda = 0;
 	aparams.tcp.header_digests = header_digests;
 	aparams.tcp.data_digests = data_digests;
-	aparams.tcp.maxh2cdata = 256 * 1024;
+	aparams.tcp.maxh2cdata = maxh2cdata;
 	io_na = nvmf_allocate_association(NVMF_TRTYPE_TCP, true,
 	    &aparams);
 	if (io_na == NULL)

usr.sbin/nvmfd/nvmfd.8

@@ -13,12 +13,14 @@
 .Nm
 .Fl K
 .Op Fl dFGg
+.Op Fl H Ar MAXH2CDATA
 .Op Fl P Ar port
 .Op Fl p Ar port
 .Op Fl t Ar transport
 .Op Fl n Ar subnqn
 .Nm
 .Op Fl dFGg
+.Op Fl H Ar MAXH2CDATA
 .Op Fl P Ar port
 .Op Fl p Ar port
 .Op Fl t Ar transport
@@ -42,6 +44,11 @@ Permit remote hosts to disable SQ flow control.
 Permit remote hosts to enable PDU data digests for the TCP transport.
 .It Fl g
 Permit remote hosts to enable PDU header digests for the TCP transport.
+.It Fl H
+Set the MAXH2CDATA value advertised to the remote host for the TCP transport.
+This value is in bytes and determines the maximum data payload size for
+data PDUs sent by the remote host.
+The value must be at least 4096 and defaults to 256KiB.
 .It Fl K
 Enable kernel mode which hands off incoming I/O controller connections to
 .Xr nvmft 4 .
@@ -121,5 +128,4 @@ should be merged into
 .Xr ctld 8 .
 .Pp
 Additional parameters such as
-.Va MAXH2CDATA
-and queue sizes should be configurable.
+queue sizes should be configurable.

usr.sbin/nvmfd/nvmfd.c

@@ -18,6 +18,7 @@
 #include <libutil.h>
 #include <netdb.h>
 #include <signal.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -29,15 +30,16 @@ bool data_digests = false;
 bool header_digests = false;
 bool flow_control_disable = false;
 bool kernel_io = false;
+uint32_t maxh2cdata = 256 * 1024;
 
 static const char *subnqn;
 static volatile bool quit = false;
 
 static void
 usage(void)
 {
-	fprintf(stderr, "nvmfd -K [-dFGg] [-P port] [-p port] [-t transport] [-n subnqn]\n"
-	    "nvmfd [-dFGg] [-P port] [-p port] [-t transport] [-n subnqn]\n"
+	fprintf(stderr, "nvmfd -K [-dFGg] [-H MAXH2CDATA] [-P port] [-p port] [-t transport] [-n subnqn]\n"
+	    "nvmfd [-dFGg] [-H MAXH2CDATA] [-P port] [-p port] [-t transport] [-n subnqn]\n"
 	    "\tdevice [device [...]]\n"
 	    "\n"
 	    "Devices use one of the following syntaxes:\n"
@@ -150,6 +152,7 @@ main(int ac, char **av)
 	struct pidfh *pfh;
 	const char *dport, *ioport, *transport;
 	pid_t pid;
+	uint64_t value;
 	int ch, error, kqfd;
 	bool daemonize;
 	static char nqn[NVMF_NQN_MAX_LEN];
@@ -162,7 +165,7 @@ main(int ac, char **av)
 	ioport = "0";
 	subnqn = NULL;
 	transport = "tcp";
-	while ((ch = getopt(ac, av, "dFgGKn:P:p:t:")) != -1) {
+	while ((ch = getopt(ac, av, "dFgGH:Kn:P:p:t:")) != -1) {
 		switch (ch) {
 		case 'd':
 			daemonize = false;
@@ -176,6 +179,14 @@ main(int ac, char **av)
 		case 'g':
 			header_digests = true;
 			break;
+		case 'H':
+			if (expand_number(optarg, &value) != 0)
+				errx(1, "Invalid MAXH2CDATA value %s", optarg);
+			if (value < 4096 || value > UINT32_MAX ||
+			    value % 4 != 0)
+				errx(1, "Invalid MAXH2CDATA value %s", optarg);
+			maxh2cdata = value;
+			break;
 		case 'K':
 			kernel_io = true;
 			break;