Add .zfs control directory

[zfs.git] / module / zfs / dmu_objset.c

diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c
index 0703a94..1d0b461 100644 (file)
--- a/module/zfs/dmu_objset.c
+++ b/module/zfs/dmu_objset.c
@@ -1584,6 +1584,41 @@ dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
        return (0);
 }
 
+/*
+ * Determine the objset id for a given snapshot name.
+ */
+int
+dmu_snapshot_id(objset_t *os, const char *snapname, uint64_t *idp)
+{
+       dsl_dataset_t *ds = os->os_dsl_dataset;
+       zap_cursor_t cursor;
+       zap_attribute_t attr;
+       int error;
+
+       if (ds->ds_phys->ds_snapnames_zapobj == 0)
+               return (ENOENT);
+
+       zap_cursor_init(&cursor, ds->ds_dir->dd_pool->dp_meta_objset,
+           ds->ds_phys->ds_snapnames_zapobj);
+
+       error = zap_cursor_move_to_key(&cursor, snapname, MT_EXACT);
+       if (error) {
+               zap_cursor_fini(&cursor);
+               return (error);
+       }
+
+       error = zap_cursor_retrieve(&cursor, &attr);
+       if (error) {
+               zap_cursor_fini(&cursor);
+               return (error);
+       }
+
+       *idp = attr.za_first_integer;
+       zap_cursor_fini(&cursor);
+
+       return (0);
+}
+
 int
 dmu_dir_list_next(objset_t *os, int namelen, char *name,
     uint64_t *idp, uint64_t *offp)