Merge branch 'dev/rename-keys' into for-chris-4.6

fs/btrfs/ctree.h

@@ -100,6 +100,9 @@ struct btrfs_ordered_sum;
 /* tracks free space in block groups. */
 #define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL
 
+/* device stats in the device tree */
+#define BTRFS_DEV_STATS_OBJECTID 0ULL
+
 /* for storing balance parameters in the root tree */
 #define BTRFS_BALANCE_OBJECTID -4ULL
 
@@ -2185,13 +2188,43 @@ struct btrfs_ioctl_defrag_range_args {
  */
 #define BTRFS_QGROUP_RELATION_KEY       246
 
+/*
+ * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
+ */
 #define BTRFS_BALANCE_ITEM_KEY	248
 
 /*
- * Persistantly stores the io stats in the device tree.
- * One key for all stats, (0, BTRFS_DEV_STATS_KEY, devid).
+ * The key type for tree items that are stored persistently, but do not need to
+ * exist for extended period of time. The items can exist in any tree.
+ *
+ * [subtype, BTRFS_TEMPORARY_ITEM_KEY, data]
+ *
+ * Existing items:
+ *
+ * - balance status item
+ *   (BTRFS_BALANCE_OBJECTID, BTRFS_TEMPORARY_ITEM_KEY, 0)
+ */
+#define BTRFS_TEMPORARY_ITEM_KEY	248
+
+/*
+ * Obsolete name, see BTRFS_PERSISTENT_ITEM_KEY
+ */
+#define BTRFS_DEV_STATS_KEY		249
+
+/*
+ * The key type for tree items that are stored persistently and usually exist
+ * for a long period, eg. filesystem lifetime. The item kinds can be status
+ * information, stats or preference values. The item can exist in any tree.
+ *
+ * [subtype, BTRFS_PERSISTENT_ITEM_KEY, data]
+ *
+ * Existing items:
+ *
+ * - device statistics, store IO stats in the device tree, one key for all
+ *   stats
+ *   (BTRFS_DEV_STATS_OBJECTID, BTRFS_DEV_STATS_KEY, 0)
  */
-#define BTRFS_DEV_STATS_KEY	249
+#define BTRFS_PERSISTENT_ITEM_KEY	249
 
 /*
  * Persistantly stores the device replace state in the device tree.

fs/btrfs/print-tree.c

@@ -295,8 +295,27 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 			       btrfs_dev_extent_chunk_offset(l, dev_extent),
 			       btrfs_dev_extent_length(l, dev_extent));
 			break;
-		case BTRFS_DEV_STATS_KEY:
-			printk(KERN_INFO "\t\tdevice stats\n");
+		case BTRFS_PERSISTENT_ITEM_KEY:
+			printk(KERN_INFO "\t\tpersistent item objectid %llu offset %llu\n",
+					key.objectid, key.offset);
+			switch (key.objectid) {
+			case BTRFS_DEV_STATS_OBJECTID:
+				printk(KERN_INFO "\t\tdevice stats\n");
+				break;
+			default:
+				printk(KERN_INFO "\t\tunknown persistent item\n");
+			}
+			break;
+		case BTRFS_TEMPORARY_ITEM_KEY:
+			printk(KERN_INFO "\t\ttemporary item objectid %llu offset %llu\n",
+					key.objectid, key.offset);
+			switch (key.objectid) {
+			case BTRFS_BALANCE_OBJECTID:
+				printk(KERN_INFO "\t\tbalance status\n");
+				break;
+			default:
+				printk(KERN_INFO "\t\tunknown temporary item\n");
+			}
 			break;
 		case BTRFS_DEV_REPLACE_KEY:
 			printk(KERN_INFO "\t\tdev replace\n");

fs/btrfs/volumes.c

@@ -2967,7 +2967,7 @@ static int insert_balance_item(struct btrfs_root *root,
 	}
 
 	key.objectid = BTRFS_BALANCE_OBJECTID;
-	key.type = BTRFS_BALANCE_ITEM_KEY;
+	key.type = BTRFS_TEMPORARY_ITEM_KEY;
 	key.offset = 0;
 
 	ret = btrfs_insert_empty_item(trans, root, path, &key,
@@ -3016,7 +3016,7 @@ static int del_balance_item(struct btrfs_root *root)
 	}
 
 	key.objectid = BTRFS_BALANCE_OBJECTID;
-	key.type = BTRFS_BALANCE_ITEM_KEY;
+	key.type = BTRFS_TEMPORARY_ITEM_KEY;
 	key.offset = 0;
 
 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
@@ -3868,7 +3868,7 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info)
 		return -ENOMEM;
 
 	key.objectid = BTRFS_BALANCE_OBJECTID;
-	key.type = BTRFS_BALANCE_ITEM_KEY;
+	key.type = BTRFS_TEMPORARY_ITEM_KEY;
 	key.offset = 0;
 
 	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
@@ -6706,8 +6706,8 @@ int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info)
 		int item_size;
 		struct btrfs_dev_stats_item *ptr;
 
-		key.objectid = 0;
-		key.type = BTRFS_DEV_STATS_KEY;
+		key.objectid = BTRFS_DEV_STATS_OBJECTID;
+		key.type = BTRFS_PERSISTENT_ITEM_KEY;
 		key.offset = device->devid;
 		ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
 		if (ret) {
@@ -6754,8 +6754,8 @@ static int update_dev_stat_item(struct btrfs_trans_handle *trans,
 	int ret;
 	int i;
 
-	key.objectid = 0;
-	key.type = BTRFS_DEV_STATS_KEY;
+	key.objectid = BTRFS_DEV_STATS_OBJECTID;
+	key.type = BTRFS_PERSISTENT_ITEM_KEY;
 	key.offset = device->devid;
 
 	path = btrfs_alloc_path();