Allow ZVOL bookmarks to be listed recursively

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #4503
Closes #5072

cmd/zfs/zfs_iter.c

@@ -444,13 +444,13 @@ zfs_for_each(int argc, char **argv, int flags, zfs_type_t types,
 
 		/*
 		 * If we're recursive, then we always allow filesystems as
-		 * arguments.  If we also are interested in snapshots, then we
-		 * can take volumes as well.
+		 * arguments.  If we also are interested in snapshots or
+		 * bookmarks, then we can take volumes as well.
 		 */
 		argtype = types;
 		if (flags & ZFS_ITER_RECURSE) {
 			argtype |= ZFS_TYPE_FILESYSTEM;
-			if (types & ZFS_TYPE_SNAPSHOT)
+			if (types & (ZFS_TYPE_SNAPSHOT | ZFS_TYPE_BOOKMARK))
 				argtype |= ZFS_TYPE_VOLUME;
 		}