--- a/cp/fs/Makefile	Mon Apr 25 09:10:57 2011 -0400
+++ b/cp/fs/Makefile	Mon Apr 25 09:15:18 2011 -0400
@@ -1,1 +1,1 @@
-objs-fs := bdev.o edf.o
+objs-fs := bdev.o edf.o bcache.o

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cp/fs/bcache.c	Mon Apr 25 09:15:18 2011 -0400
@@ -0,0 +1,124 @@
+/*
+ * (C) Copyright 2007-2011  Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+ *
+ * This file is released under the GPLv2.  See the COPYING file for more
+ * details.
+ */
+
+#include <list.h>
+#include <mutex.h>
+#include <buddy.h>
+#include <slab.h>
+#include <edf.h>
+#include <bdev.h>
+#include <bcache.h>
+
+struct bcache_entry {
+	struct list_head bcache;
+
+	int level; /* 0 = data */
+	u32 blk;
+
+	u32 lba;
+	void *data;
+};
+
+static struct bcache_entry *__bcache_add(struct file *file, int level, u32 blk,
+					 u32 lba)
+{
+	struct bcache_entry *ent;
+
+	ent = malloc(sizeof(struct bcache_entry), ZONE_NORMAL);
+	if (!ent)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&ent->bcache);
+	ent->level = level;
+	ent->blk   = blk;
+	ent->lba   = lba;
+	ent->data  = NULL;
+
+	list_add_tail(&ent->bcache, &file->bcache);
+
+	return ent;
+}
+
+int bcache_add(struct file *file, int level, u32 blk, u32 lba)
+{
+	struct bcache_entry *ent;
+
+	ent = __bcache_add(file, level, blk, lba);
+
+	return IS_ERR(ent) ? PTR_ERR(ent) : 0;
+}
+
+void *bcache_read(struct file *file, int level, u32 blk)
+{
+	struct bcache_entry *cur;
+	struct page *page;
+	void *buf;
+	u32 *ptrs;
+	u32 nblk, off;
+	int ret;
+
+	BUG_ON(level > file->FST.NLVL);
+
+	list_for_each_entry(cur, &file->bcache, bcache) {
+		if ((cur->level == level) && (cur->blk == blk))
+			goto found;
+	}
+
+	if (level == file->FST.NLVL) {
+		/* we can get the lba for this from the FST */
+		cur = __bcache_add(file, level, 0, file->FST.FOP);
+		if (IS_ERR(cur))
+			return cur;
+
+		goto found;
+	} else {
+		/* we need to read the pointer block one level up */
+		off = blk % (file->fs->ADT.DBSIZ / 4);
+		nblk = blk / (file->fs->ADT.DBSIZ / 4);
+
+		/*
+		 * WARNING: recursive call below!
+		 *
+		 * Thankfully, there is a bound on the number of levels - 2
+		 * pointer blocks worth & 1 data block level.
+		 */
+		ptrs = bcache_read(file, level+1, nblk);
+		if (IS_ERR(ptrs))
+			return ptrs;
+
+		/* add the pointer to the cache
+		 *
+		 * FIXME: since we read the whole block, we should probably
+		 * add all the pointers to the cache
+		 */
+		cur = __bcache_add(file, level, blk, ptrs[off]);
+		if (IS_ERR(cur))
+			return cur;
+
+		goto found;
+	}
+	return ERR_PTR(-EFAULT);
+
+found:
+	if (cur->data)
+		return cur->data;
+
+	page = alloc_pages(0, ZONE_NORMAL);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	buf = page_to_addr(page);
+
+	ret = bdev_read_block(file->fs->dev, buf, cur->lba);
+	if (ret) {
+		free_pages(buf, 0);
+		return ERR_PTR(ret);
+	}
+
+	cur->data = buf;
+	return buf;
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cp/include/bcache.h	Mon Apr 25 09:15:18 2011 -0400
@@ -0,0 +1,16 @@
+/*
+ * (C) Copyright 2007-2011  Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+ *
+ * This file is released under the GPLv2.  See the COPYING file for more
+ * details.
+ */
+
+#ifndef __BCACHE_H
+#define __BCACHE_H
+
+#include <edf.h>
+
+extern int bcache_add(struct file *file, int level, u32 blk, u32 lba);
+extern void *bcache_read(struct file *file, int level, u32 blk);
+
+#endif