reboot: Implement zfs support

Implement full support for ZFS -k support. For ZFS, we have to set a
property that gets cleared by the boot loaeder for whether or not to
process nextboot.conf. Do this using system("zfsbootcfg..." rather than
coding the small subset of that program inline to avoid CDDL
contamination of reboot and the complications of disabling CDDL and/or
ZFS. The few bytes needed to implement reboot for systems with zfs is
not worth saving for systems w/o ZFS.

Only set nextboot_enable=YES for UFS filesystems. They are the only one
that need that as the first line. Its presence on ZFS can cause the
kernel to not be oneshot.

Sponsored by:		Netflix
Reviewed by:		kevans, kib
Differential Revision:	https://reviews.freebsd.org/D43824

1 files changed, 49 insertions, 9 deletions

diff --git a/sbin/reboot/reboot.c b/sbin/reboot/reboot.c
index d91fc6c97b0f..d598c857d255 100644
--- a/sbin/reboot/reboot.c
+++ b/sbin/reboot/reboot.c
@@ -31,6 +31,7 @@
 
 #include <sys/types.h>
 #include <sys/boottrace.h>
+#include <sys/mount.h>
 #include <sys/reboot.h>
 #include <sys/stat.h>
 #include <sys/sysctl.h>
@@ -56,11 +57,6 @@ static uint64_t get_pageins(void);
 
 static bool dohalt;
 
-static void
-write_nextboot(const char *fn, const char *kernel, bool force)
-{
-	FILE *fp;
-
 #define E(...) do {				\
 		if (force) {			\
 			warn( __VA_ARGS__ );	\
@@ -69,13 +65,58 @@ write_nextboot(const char *fn, const char *kernel, bool force)
 		err(1, __VA_ARGS__);		\
 	} while (0)				\
 
+static void
+zfsbootcfg(const char *pool, bool force)
+{
+	char *k;
+	int rv;
+
+	asprintf(&k,
+	    "zfsbootcfg -z %s -n freebsd:nvstore -k nextboot_enable -v YES",
+	    pool);
+	if (k == NULL)
+		E("No memory for zfsbootcfg");
+
+	rv = system(k);
+	if (rv == 0)
+		return;
+	if (rv == -1)
+		E("system zfsbootcfg");
+	if (rv == 127)
+		E("zfsbootcfg not found in path");
+	E("zfsbootcfg returned %d", rv);
+}
+
+static void
+write_nextboot(const char *fn, const char *kernel, bool force)
+{
+	FILE *fp;
+	struct statfs sfs;
+	bool supported = false;
+	bool zfs = false;
+
+	if (statfs("/boot", &sfs) != 0)
+		err(1, "statfs /boot");
+	if (strcmp(sfs.f_fstypename, "ufs") == 0) {
+		/*
+		 * Only UFS supports the full nextboot protocol.
+		 */
+		supported = true;
+	} else if (strcmp(sfs.f_fstypename, "zfs") == 0) {
+		zfs = true;
+	}
+
+	if (zfs) {
+		zfsbootcfg(sfs.f_mntfromname, force);
+	}
+
 	fp = fopen(fn, "w");
 	if (fp == NULL)
 		E("Can't create %s to boot %s", fn, kernel);
 
-	if (fprintf(fp,
-	    "nextboot_enable=\"YES\"\n"
-	    "kernel=\"%s\"\n", kernel) < 0) {
+	if (fprintf(fp,"%skernel=\"%s\"\n",
+	    supported ? "nextboot_enable=\"YES\"\n" : "",
+	    kernel) < 0) {
 		int e;
 
 		e = errno;
@@ -86,7 +127,6 @@ write_nextboot(const char *fn, const char *kernel, bool force)
 		E("Can't write %s", fn);
 	}
 	fclose(fp);
-#undef E
 }
 
 int