3996 want a libzfs_core API to rollback to latest snapshot
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>

@@ -3516,11 +3516,10 @@
 int
 zfs_rollback(zfs_handle_t *zhp, zfs_handle_t *snap, boolean_t force)
 {
         rollback_data_t cb = { 0 };
         int err;
-        zfs_cmd_t zc = { 0 };
         boolean_t restore_resv = 0;
         uint64_t old_volsize, new_volsize;
         zfs_prop_t resv_prop;
 
         assert(zhp->zfs_type == ZFS_TYPE_FILESYSTEM ||

@@ -3548,26 +3547,19 @@
                 old_volsize = zfs_prop_get_int(zhp, ZFS_PROP_VOLSIZE);
                 restore_resv =
                     (old_volsize == zfs_prop_get_int(zhp, resv_prop));
         }
 
-        (void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
-
-        if (ZFS_IS_VOLUME(zhp))
-                zc.zc_objset_type = DMU_OST_ZVOL;
-        else
-                zc.zc_objset_type = DMU_OST_ZFS;
-
         /*
          * We rely on zfs_iter_children() to verify that there are no
          * newer snapshots for the given dataset.  Therefore, we can
          * simply pass the name on to the ioctl() call.  There is still
          * an unlikely race condition where the user has taken a
          * snapshot since we verified that this was the most recent.
-         *
          */
-        if ((err = zfs_ioctl(zhp->zfs_hdl, ZFS_IOC_ROLLBACK, &zc)) != 0) {
+        err = lzc_rollback(zhp->zfs_name, NULL, 0);
+        if (err != 0) {
                 (void) zfs_standard_error_fmt(zhp->zfs_hdl, errno,
                     dgettext(TEXT_DOMAIN, "cannot rollback '%s'"),
                     zhp->zfs_name);
                 return (err);
         }