FreeBSD boot code reminder after zpool upgrade

There used to be a warning after upgrading a zpool in FreeBSD, so users
won't forget to update the boot loader that pool is booted from.

This change brings this warning back, but only if the bootfs property
is set on the pool, which should be sufficient for the vast majority of
FreeBSD installations. People running something custom are most likely
aware of what to do after an upgrade in their specific environment.

Functionality is implemented in an OS specific helper function.

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Co-authored-by: Michael Gmelin <grembo@FreeBSD.org>
Signed-off-by: Michael Gmelin <grembo@FreeBSD.org>
Closes openzfs#12099
Closes openzfs#12104

cmd/zpool/os/freebsd/zpool_vdev_os.c

@@ -101,3 +101,18 @@ check_sector_size_database(char *path, int *sector_size)
 {
 	return (0);
 }
+
+void
+after_zpool_upgrade(zpool_handle_t *zhp)
+{
+	char bootfs[ZPOOL_MAXPROPLEN];
+
+	if (zpool_get_prop(zhp, ZPOOL_PROP_BOOTFS, bootfs,
+	    sizeof (bootfs), NULL, B_FALSE) == 0 &&
+	    strcmp(bootfs, "-") != 0) {
+		(void) printf(gettext("Pool '%s' has the bootfs "
+		    "property set, you might need to update\nthe boot "
+		    "code. See gptzfsboot(8) and loader.efi(8) for "
+		    "details.\n"), zpool_get_name(zhp));
+	}
+}

cmd/zpool/os/linux/zpool_vdev_os.c

@@ -405,3 +405,8 @@ check_device(const char *path, boolean_t force,
 
 	return (error);
 }
+
+void
+after_zpool_upgrade(zpool_handle_t *zhp)
+{
+}

cmd/zpool/zpool_main.c

@@ -8858,7 +8858,7 @@ upgrade_cb(zpool_handle_t *zhp, void *arg)
 	upgrade_cbdata_t *cbp = arg;
 	nvlist_t *config;
 	uint64_t version;
-	boolean_t printnl = B_FALSE;
+	boolean_t modified_pool = B_FALSE;
 	int ret;
 
 	config = zpool_get_config(zhp, NULL);
@@ -8872,7 +8872,7 @@ upgrade_cb(zpool_handle_t *zhp, void *arg)
 		ret = upgrade_version(zhp, cbp->cb_version);
 		if (ret != 0)
 			return (ret);
-		printnl = B_TRUE;
+		modified_pool = B_TRUE;
 
 		/*
 		 * If they did "zpool upgrade -a", then we could
@@ -8892,12 +8892,13 @@ upgrade_cb(zpool_handle_t *zhp, void *arg)
 
 		if (count > 0) {
 			cbp->cb_first = B_FALSE;
-			printnl = B_TRUE;
+			modified_pool = B_TRUE;
 		}
 	}
 
-	if (printnl) {
-		(void) printf(gettext("\n"));
+	if (modified_pool) {
+		(void) printf("\n");
+		(void) after_zpool_upgrade(zhp);
 	}
 
 	return (0);
@@ -9010,7 +9011,7 @@ upgrade_list_disabled_cb(zpool_handle_t *zhp, void *arg)
 static int
 upgrade_one(zpool_handle_t *zhp, void *data)
 {
-	boolean_t printnl = B_FALSE;
+	boolean_t modified_pool = B_FALSE;
 	upgrade_cbdata_t *cbp = data;
 	uint64_t cur_version;
 	int ret;
@@ -9038,7 +9039,7 @@ upgrade_one(zpool_handle_t *zhp, void *data)
 	}
 
 	if (cur_version != cbp->cb_version) {
-		printnl = B_TRUE;
+		modified_pool = B_TRUE;
 		ret = upgrade_version(zhp, cbp->cb_version);
 		if (ret != 0)
 			return (ret);
@@ -9051,16 +9052,17 @@ upgrade_one(zpool_handle_t *zhp, void *data)
 			return (ret);
 
 		if (count != 0) {
-			printnl = B_TRUE;
+			modified_pool = B_TRUE;
 		} else if (cur_version == SPA_VERSION) {
 			(void) printf(gettext("Pool '%s' already has all "
 			    "supported and requested features enabled.\n"),
 			    zpool_get_name(zhp));
 		}
 	}
 
-	if (printnl) {
-		(void) printf(gettext("\n"));
+	if (modified_pool) {
+		(void) printf("\n");
+		(void) after_zpool_upgrade(zhp);
 	}
 
 	return (0);

cmd/zpool/zpool_util.h

@@ -129,6 +129,7 @@ int check_device(const char *path, boolean_t force,
 boolean_t check_sector_size_database(char *path, int *sector_size);
 void vdev_error(const char *fmt, ...);
 int check_file(const char *file, boolean_t force, boolean_t isspare);
+void after_zpool_upgrade(zpool_handle_t *zhp);
 
 #ifdef	__cplusplus
 }