From 28de03cb0aa69a75c51ee9dcf68942319eefed0b Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.mason@oracle.com>
Date: Mon, 15 Oct 2007 16:25:41 -0400
Subject: Create a slightly more generic extent-caching structure

---
 extent-cache.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 extent-cache.c

(limited to 'extent-cache.c')

diff --git a/extent-cache.c b/extent-cache.c
new file mode 100644
index 00000000..cfc6b639
--- /dev/null
+++ b/extent-cache.c
@@ -0,0 +1,160 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include "kerncompat.h"
+#include "extent-cache.h"
+
+void cache_tree_init(struct cache_tree *tree)
+{
+	tree->root.rb_node = NULL;
+}
+
+static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
+				   u64 size, struct rb_node *node)
+{
+	struct rb_node ** p = &root->rb_node;
+	struct rb_node * parent = NULL;
+	struct cache_extent *entry;
+
+	while(*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct cache_extent, rb_node);
+
+		if (offset + size <= entry->start)
+			p = &(*p)->rb_left;
+		else if (offset >= entry->start + entry->size)
+			p = &(*p)->rb_right;
+		else
+			return parent;
+	}
+
+	entry = rb_entry(parent, struct cache_extent, rb_node);
+	rb_link_node(node, parent, p);
+	rb_insert_color(node, root);
+	return NULL;
+}
+
+static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
+				     u64 size, struct rb_node **prev_ret)
+{
+	struct rb_node * n = root->rb_node;
+	struct rb_node *prev = NULL;
+	struct cache_extent *entry;
+	struct cache_extent *prev_entry = NULL;
+
+	while(n) {
+		entry = rb_entry(n, struct cache_extent, rb_node);
+		prev = n;
+		prev_entry = entry;
+
+		if (offset + size <= entry->start)
+			n = n->rb_left;
+		else if (offset >= entry->start + entry->size)
+			n = n->rb_right;
+		else
+			return n;
+	}
+	if (!prev_ret)
+		return NULL;
+
+	while(prev && offset >= prev_entry->start + prev_entry->size) {
+		prev = rb_next(prev);
+		prev_entry = rb_entry(prev, struct cache_extent, rb_node);
+	}
+	*prev_ret = prev;
+	return NULL;
+}
+
+struct cache_extent *alloc_cache_extent(u64 start, u64 size)
+{
+	struct cache_extent *pe = malloc(sizeof(*pe));
+
+	if (!pe)
+		return pe;
+	pe->start = start;
+	pe->size = size;
+	return pe;
+}
+
+int insert_existing_cache_extent(struct cache_tree *tree,
+				 struct cache_extent *pe)
+{
+	struct rb_node *found;
+
+	found = tree_insert(&tree->root, pe->start, pe->size, &pe->rb_node);
+	if (found)
+		return -EEXIST;
+	return 0;
+}
+
+int insert_cache_extent(struct cache_tree *tree, u64 start, u64 size)
+{
+	struct cache_extent *pe = alloc_cache_extent(start, size);
+	int ret;
+	ret = insert_existing_cache_extent(tree, pe);
+	if (ret)
+		free(pe);
+	return ret;
+}
+
+struct cache_extent *find_cache_extent(struct cache_tree *tree,
+					   u64 start, u64 size)
+{
+	struct rb_node *prev;
+	struct rb_node *ret;
+	struct cache_extent *entry;
+	ret = __tree_search(&tree->root, start, size, &prev);
+	if (!ret)
+		return NULL;
+
+	entry = rb_entry(ret, struct cache_extent, rb_node);
+	return entry;
+}
+
+struct cache_extent *find_first_cache_extent(struct cache_tree *tree,
+						 u64 start)
+{
+	struct rb_node *prev;
+	struct rb_node *ret;
+	struct cache_extent *entry;
+
+	ret = __tree_search(&tree->root, start, 1, &prev);
+	if (!ret)
+		ret = prev;
+	if (!ret)
+		return NULL;
+	entry = rb_entry(ret, struct cache_extent, rb_node);
+	return entry;
+}
+
+struct cache_extent *next_cache_extent(struct cache_extent *pe)
+{
+	struct rb_node *node = rb_next(&pe->rb_node);
+
+	if (!node)
+		return NULL;
+	return rb_entry(node, struct cache_extent, rb_node);
+}
+
+void remove_cache_extent(struct cache_tree *tree,
+				 struct cache_extent *pe)
+{
+	rb_erase(&pe->rb_node, &tree->root);
+}
+
-- 
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