Split iscsi(4) ctl frontend off of ctl(4) as cfiscsi(4)

The goal of this work is to remove the explicit dependency for ctl(4)
on iscsi(4), so end-users without iscsi(4) support in the kernel can
use ctl(4) for its other functions.

This allows those without iscsi(4) support built into the kernel to use
ctl(4) as a test mechanism. As a sidenote, this was possible around the
10.0-RELEASE period, but made impossible for end-users without iscsi(4)
between 10.0-RELEASE and 11.0-RELEASE.

Automatically load cfiscsi(4) from ctladm(8) and ctld(8) for backwards
compatibility with previously releases. The automatic loading feature is
compiled into the beforementioned tools if MK_ISCSI == yes when building
world.

Add a manpage for cfiscsi(4) and refer to it in ctl(4).

Differential Revision:	D10099
MFC after:	2 months
Relnotes:	yes
Reviewed by:	mav, trasz
Sponsored by:	Dell EMC Isilon

4 files changed, 29 insertions, 0 deletions

diff --git a/usr.sbin/ctladm/Makefile b/usr.sbin/ctladm/Makefile
index c5e7e87f7a72..5b74668bf571 100644
--- a/usr.sbin/ctladm/Makefile
+++ b/usr.sbin/ctladm/Makefile
@@ -1,5 +1,7 @@
 # $FreeBSD$
 
+.include <src.opts.mk>
+
 PROG=		ctladm
 SRCS=		ctladm.c util.c ctl_util.c ctl_scsi_all.c
 .PATH:		${SRCTOP}/sys/cam/ctl
@@ -17,4 +19,8 @@ WARNS?= 3
 LIBADD=		cam sbuf bsdxml util
 MAN=		ctladm.8
 
+.if ${MK_ISCSI} != "no"
+CFLAGS+=	-DWANT_ISCSI
+.endif
+
 .include <bsd.prog.mk>
diff --git a/usr.sbin/ctladm/ctladm.c b/usr.sbin/ctladm/ctladm.c
index cedfb12115ad..dffa3734ec4b 100644
--- a/usr.sbin/ctladm/ctladm.c
+++ b/usr.sbin/ctladm/ctladm.c
@@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/callout.h>
 #include <sys/ioctl.h>
 #include <sys/linker.h>
+#include <sys/module.h>
 #include <sys/queue.h>
 #include <sys/sbuf.h>
 #include <sys/stat.h>
@@ -4152,6 +4153,13 @@ main(int argc, char **argv)
 			retval = 1;
 			goto bailout;
 		}
+#ifdef	WANT_ISCSI
+		else {
+			if (modfind("cfiscsi") == -1 &&
+			    kldload("cfiscsi") == -1)
+				warn("couldn't load cfiscsi");
+		}
+#endif
 	} else if ((command != CTLADM_CMD_HELP)
 		&& ((cmdargs & CTLADM_ARG_DEVICE) == 0)) {
 		fprintf(stderr, "%s: you must specify a device with the "
diff --git a/usr.sbin/ctld/Makefile b/usr.sbin/ctld/Makefile
index 7c342568fe35..944b94d663c8 100644
--- a/usr.sbin/ctld/Makefile
+++ b/usr.sbin/ctld/Makefile
@@ -1,5 +1,7 @@
 # $FreeBSD$
 
+.include <src.opts.mk>
+
 CFLAGS+=-I${SRCTOP}/contrib/libucl/include
 .PATH:  ${SRCTOP}/contrib/libucl/include
 
@@ -21,4 +23,8 @@ CLEANFILES=	y.tab.c y.tab.h y.output
 WARNS?=		6
 NO_WMISSING_VARIABLE_DECLARATIONS=
 
+.if ${MK_ISCSI} != "no"
+CFLAGS+=	-DWANT_ISCSI
+.endif
+
 .include <bsd.prog.mk>
diff --git a/usr.sbin/ctld/kernel.c b/usr.sbin/ctld/kernel.c
index b646bc7795ab..b56364a1463e 100644
--- a/usr.sbin/ctld/kernel.c
+++ b/usr.sbin/ctld/kernel.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/callout.h>
 #include <sys/ioctl.h>
 #include <sys/linker.h>
+#include <sys/module.h>
 #include <sys/queue.h>
 #include <sys/sbuf.h>
 #include <sys/stat.h>
@@ -90,6 +91,14 @@ kernel_init(void)
 	}
 	if (ctl_fd < 0)
 		log_err(1, "failed to open %s", CTL_DEFAULT_DEV);
+#ifdef	WANT_ISCSI
+	else {
+		saved_errno = errno;
+		if (modfind("cfiscsi") == -1 && kldload("cfiscsi") == -1)
+			log_warn("couldn't load cfiscsi");
+		errno = saved_errno;
+	}
+#endif
 }
 
 /*