Only automatically mount a clone when 'canmount == on'.

According to the man page, "When the noauto option is set, a dataset
can only be mounted and unmounted explicitly. The dataset is not
mounted automatically when the dataset is created or imported ...."

When cloning a dataset the canmount property was not being honored.
This patch adds the required check to achieve the behavior described
in the man page.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2241

cmd/zfs/zfs_main.c

@@ -648,6 +648,7 @@ zfs_do_clone(int argc, char **argv)
 	/* create the mountpoint if necessary */
 	if (ret == 0) {
 		zfs_handle_t *clone;
+		int canmount = ZFS_CANMOUNT_OFF;
 
 		if (log_history) {
 			(void) zpool_log_history(g_zfs, history_str);
@@ -656,7 +657,17 @@ zfs_do_clone(int argc, char **argv)
 
 		clone = zfs_open(g_zfs, argv[1], ZFS_TYPE_DATASET);
 		if (clone != NULL) {
-			if (zfs_get_type(clone) != ZFS_TYPE_VOLUME)
+			/*
+			 * if the user doesn't want the dataset automatically
+			 * mounted, then skip the mount/share step.
+			 */
+			if (zfs_prop_valid_for_type(ZFS_PROP_CANMOUNT,
+			    zfs_get_type(clone), B_FALSE))
+				canmount = zfs_prop_get_int(clone,
+				    ZFS_PROP_CANMOUNT);
+
+			if (zfs_get_type(clone) != ZFS_TYPE_VOLUME &&
+			    canmount == ZFS_CANMOUNT_ON)
 				if ((ret = zfs_mount(clone, NULL, 0)) == 0)
 					ret = zfs_share(clone);
 			zfs_close(clone);