[RFC PATCH 04/17] btrfs: priority alloc: add functions to create/remove priority trees

[Su Yue <suy.fnst@cn.fujitsu.com>]

Introduce create_priority_trees() to create priority trees in
space_info.
Introduce remove_priority_trees() to remove priority trees in
space_info.

Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
---
 fs/btrfs/extent-tree.c | 94 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0f4c5b1e0bcc..787a68b5bdcb 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11250,3 +11250,97 @@ static int compute_priority_level(struct btrfs_fs_info *fs_info,
 
 	return level;
 }
+
+static inline bool
+is_priority_alloc_enabled(struct btrfs_fs_info *fs_info)
+{
+	if (btrfs_test_opt(fs_info, PRIORITY_USAGE))
+		return true;
+	return false;
+}
+
+static void init_priority_tree(struct btrfs_priority_tree *pt, int level)
+{
+	pt->block_groups = RB_ROOT;
+	init_rwsem(&pt->groups_sem);
+	pt->level = level;
+}
+
+static void remove_priority_trees(struct btrfs_fs_info *fs_info,
+				  struct btrfs_space_info *space_info)
+{
+	struct rb_root *root;
+	struct btrfs_priority_tree *pt, *next_pt;
+	int i;
+
+	if (!is_priority_alloc_enabled(fs_info))
+		return;
+
+	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
+		root = &space_info->priority_trees[i];
+		rbtree_postorder_for_each_entry_safe(pt, next_pt, root, node) {
+			kfree(pt);
+		}
+		space_info->priority_trees[i] = RB_ROOT;
+	}
+}
+
+static int insert_priority_tree(struct rb_root *root,
+				struct btrfs_priority_tree *pt)
+{
+	struct rb_node **p = &root->rb_node;
+	struct rb_node *parent = NULL;
+	struct btrfs_priority_tree *tmp;
+
+	while (*p) {
+		parent = *p;
+		tmp = rb_entry(parent, struct btrfs_priority_tree, node);
+		if (pt->level > tmp->level)
+			p = &(*p)->rb_left;
+		else if (pt->level < tmp->level)
+			p = &(*p)->rb_right;
+		else
+			return -EEXIST;
+	}
+
+	rb_link_node(&pt->node, parent, p);
+	rb_insert_color(&pt->node, root);
+	return 0;
+}
+
+static int create_priority_trees(struct btrfs_fs_info *fs_info,
+				 struct btrfs_space_info *space_info)
+{
+	struct rb_root *root;
+	struct btrfs_priority_tree *pt;
+	int ret = 0;
+	int i, level, max_level;
+	u64 priority;
+
+	if (!is_priority_alloc_enabled(fs_info))
+		return 0;
+
+	if (btrfs_test_opt(fs_info, PRIORITY_USAGE)) {
+		priority = (u8)100 << PRIORITY_USAGE_SHIFT;
+		max_level = compute_priority_level(fs_info, priority);
+	}
+	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
+		root = &space_info->priority_trees[i];
+
+		for (level = 0; level <= max_level; level++) {
+			pt = kzalloc(sizeof(*pt), GFP_NOFS);
+			if (!pt) {
+				ret = -ENOMEM;
+				break;
+			}
+			init_priority_tree(pt, level);
+			ret = insert_priority_tree(root, pt);
+			if (ret)
+				break;
+		}
+	}
+
+	if (ret)
+		remove_priority_trees(fs_info, space_info);
+	return ret;
+}
-- 
2.19.1