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>

@@ -3491,33 +3491,36 @@
                 (void) zvol_remove_minor(zc->zc_name);
         return (err);
 }
 
 /*
- * inputs:
- * zc_name      name of dataset to rollback (to most recent snapshot)
+ * fsname is name of dataset to rollback (to most recent snapshot)
  *
- * outputs:     none
+ * innvl is not used.
+ *
+ * outnvl: "target" -> name of most recent snapshot
+ * }
  */
+/* ARGSUSED */
 static int
-zfs_ioc_rollback(zfs_cmd_t *zc)
+zfs_ioc_rollback(const char *fsname, nvlist_t *args, nvlist_t *outnvl)
 {
         zfsvfs_t *zfsvfs;
         int error;
 
-        if (getzfsvfs(zc->zc_name, &zfsvfs) == 0) {
+        if (getzfsvfs(fsname, &zfsvfs) == 0) {
                 error = zfs_suspend_fs(zfsvfs);
                 if (error == 0) {
                         int resume_err;
 
-                        error = dsl_dataset_rollback(zc->zc_name, zfsvfs);
-                        resume_err = zfs_resume_fs(zfsvfs, zc->zc_name);
+                        error = dsl_dataset_rollback(fsname, zfsvfs, outnvl);
+                        resume_err = zfs_resume_fs(zfsvfs, fsname);
                         error = error ? error : resume_err;
                 }
                 VFS_RELE(zfsvfs->z_vfs);
         } else {
-                error = dsl_dataset_rollback(zc->zc_name, NULL);
+                error = dsl_dataset_rollback(fsname, NULL, outnvl);
         }
         return (error);
 }
 
 static int

@@ -5325,10 +5328,14 @@
 
         zfs_ioctl_register("get_holds", ZFS_IOC_GET_HOLDS,
             zfs_ioc_get_holds, zfs_secpolicy_read, DATASET_NAME,
             POOL_CHECK_SUSPENDED, B_FALSE, B_FALSE);
 
+        zfs_ioctl_register("rollback", ZFS_IOC_ROLLBACK,
+            zfs_ioc_rollback, zfs_secpolicy_rollback, DATASET_NAME,
+            POOL_CHECK_SUSPENDED | POOL_CHECK_READONLY, B_FALSE, B_TRUE);
+
         /* IOCTLS that use the legacy function signature */
 
         zfs_ioctl_register_legacy(ZFS_IOC_POOL_FREEZE, zfs_ioc_pool_freeze,
             zfs_secpolicy_config, NO_NAME, B_FALSE, POOL_CHECK_READONLY);
 

@@ -5436,12 +5443,10 @@
 
         zfs_ioctl_register_dataset_modify(ZFS_IOC_SET_PROP, zfs_ioc_set_prop,
             zfs_secpolicy_none);
         zfs_ioctl_register_dataset_modify(ZFS_IOC_DESTROY, zfs_ioc_destroy,
             zfs_secpolicy_destroy);
-        zfs_ioctl_register_dataset_modify(ZFS_IOC_ROLLBACK, zfs_ioc_rollback,
-            zfs_secpolicy_rollback);
         zfs_ioctl_register_dataset_modify(ZFS_IOC_RENAME, zfs_ioc_rename,
             zfs_secpolicy_rename);
         zfs_ioctl_register_dataset_modify(ZFS_IOC_RECV, zfs_ioc_recv,
             zfs_secpolicy_recv);
         zfs_ioctl_register_dataset_modify(ZFS_IOC_PROMOTE, zfs_ioc_promote,