8264 want support for promoting datasets in libzfs_core

@@ -29,10 +29,11 @@
  * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
  * Copyright 2016 Toomas Soome <tsoome@me.com>
+ * Copyright 2017 RackTop Systems.
  */
 
 /*
  * ZFS ioctls.
  *

@@ -4700,28 +4701,60 @@
         return (0);
 }
 /*
  * inputs:
  * zc_name      name of filesystem
- * zc_value     name of origin snapshot
  *
  * outputs:
  * zc_string    name of conflicting snapshot, if there is one
  */
 static int
 zfs_ioc_promote(zfs_cmd_t *zc)
 {
+        dsl_pool_t *dp;
+        dsl_dataset_t *ds, *ods;
+        char origin[ZFS_MAX_DATASET_NAME_LEN];
         char *cp;
+        int error;
 
+        error = dsl_pool_hold(zc->zc_name, FTAG, &dp);
+        if (error != 0)
+                return (error);
+
+        error = dsl_dataset_hold(dp, zc->zc_name, FTAG, &ds);
+        if (error != 0) {
+                dsl_pool_rele(dp, FTAG);
+                return (error);
+        }
+
+        if (!dsl_dir_is_clone(ds->ds_dir)) {
+                dsl_dataset_rele(ds, FTAG);
+                dsl_pool_rele(dp, FTAG);
+                return (SET_ERROR(EINVAL));
+        }
+
+        error = dsl_dataset_hold_obj(dp,
+            dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &ods);
+        if (error != 0) {
+                dsl_dataset_rele(ds, FTAG);
+                dsl_pool_rele(dp, FTAG);
+                return (error);
+        }
+
+        dsl_dataset_name(ods, origin);
+        dsl_dataset_rele(ods, FTAG);
+        dsl_dataset_rele(ds, FTAG);
+        dsl_pool_rele(dp, FTAG);
+
         /*
          * We don't need to unmount *all* the origin fs's snapshots, but
          * it's easier.
          */
-        cp = strchr(zc->zc_value, '@');
+        cp = strchr(origin, '@');
         if (cp)
                 *cp = '\0';
-        (void) dmu_objset_find(zc->zc_value,
+        (void) dmu_objset_find(origin,
             zfs_unmount_snap_cb, NULL, DS_FIND_SNAPSHOTS);
         return (dsl_dataset_promote(zc->zc_name, zc->zc_string));
 }
 
 /*