Add zgenhostid utility script

Turning the multihost property on requires that a hostid be set to allow
ZFS to determine when a foreign system is attemping to import a pool.
The error message instructing the user to set a hostid refers to
genhostid(1).

Genhostid(1) is not available on SUSE Linux.  This commit adds a script
modeled after genhostid(1) for those users.

Zgenhostid checks for an /etc/hostid file; if it does not exist, it
creates one and stores a value.  If the user has provided a hostid as an
argument, that value is used.  Otherwise, a random hostid is generated
and stored.

This differs from the CENTOS 6/7 versions of genhostid, which overwrite
the /etc/hostid file even though their manpages state otherwise.

A man page for zgenhostid is added. The one for genhostid is in (1), but
I put zgenhostid in (8) because I believe it's more appropriate.

The mmp tests are modified to use zgenhostid to set the hostid instead
of using the spl_hostid module parameter.  zgenhostid will not replace
an existing /etc/hostid file, so new mmp_clear_hostid calls are
required.

Reviewed-by: Giuseppe Di Natale <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Olaf Faaland <[email protected]>
Closes #6358
Closes #6379

1 files changed, 2 insertions, 2 deletions

diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index 8d04f7725..f597109d2 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -2177,7 +2177,7 @@ show_import(nvlist_t *config)
 			break;
 		case ZPOOL_STATUS_HOSTID_REQUIRED:
 			(void) printf(gettext(" action: Set a unique system "
-			    "hostid with the genhostid(1) command.\n"));
+			    "hostid with the zgenhostid(8) command.\n"));
 			break;
 		default:
 			(void) printf(gettext(" action: The pool cannot be "
@@ -2304,7 +2304,7 @@ do_import(nvlist_t *config, const char *newname, const char *mntopts,
 			(void) fprintf(stderr, gettext("Cannot import '%s': "
 			    "pool has the multihost property on and the\n"
 			    "system's hostid is not set. Set a unique hostid "
-			    "with the genhostid(1) command.\n"), name);
+			    "with the zgenhostid(8) command.\n"), name);
 		} else {
 			char *hostname = "<unknown>";
 			uint64_t timestamp = 0;