Btrfs: Add backing store, memory management

ctree: ctree.o

	gcc -g -O2 -Wall -o ctree ctree.c

CFLAGS= -g -Wall

.c.o:

	$(CC) $(CFLAGS) -c $<

ctree: ctree.o disk-io.h ctree.h disk-io.o radix-tree.o radix-tree.h

	gcc $(CFLAGS) -o ctree ctree.o disk-io.o radix-tree.o

clean:

	rm ctree ctree.o

	rm ctree *.o

#ifndef __CTREE__

#define __CTREE__

#define CTREE_BLOCKSIZE 4096

struct key {

	u64 objectid;

	u32 flags;

	u64 offset;

} __attribute__ ((__packed__));

struct header {

	u64 fsid[2]; /* FS specific uuid */

	u64 blocknr;

	u64 parentid;

	u32 csum;

	u32 ham;

	u16 nritems;

	u16 flags;

} __attribute__ ((__packed__));

#define NODEPTRS_PER_BLOCK ((CTREE_BLOCKSIZE - sizeof(struct header)) / \

			    (sizeof(struct key) + sizeof(u64)))

#define LEVEL_BITS 3

#define MAX_LEVEL (1 << LEVEL_BITS)

#define node_level(f) ((f) & (MAX_LEVEL-1))

#define is_leaf(f) (node_level(f) == 0)

struct tree_buffer;

struct ctree_root {

	struct tree_buffer *node;

	int fp;

	struct radix_tree_root cache_radix;

};

struct item {

	struct key key;

	u16 offset;

	u16 size;

} __attribute__ ((__packed__));

#define LEAF_DATA_SIZE (CTREE_BLOCKSIZE - sizeof(struct header))

struct leaf {

	struct header header;

	union {

		struct item items[LEAF_DATA_SIZE/sizeof(struct item)];

		u8 data[CTREE_BLOCKSIZE-sizeof(struct header)];

	};

} __attribute__ ((__packed__));

struct node {

	struct header header;

	struct key keys[NODEPTRS_PER_BLOCK];

	u64 blockptrs[NODEPTRS_PER_BLOCK];

} __attribute__ ((__packed__));

struct ctree_path {

	struct tree_buffer *nodes[MAX_LEVEL];

	int slots[MAX_LEVEL];

};

#endif

#ifndef __DISKIO__

#define __DISKIO__

struct tree_buffer {

	u64 blocknr;

	int count;

	union {

		struct node node;

		struct leaf leaf;

	};

};

struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr);

int write_tree_block(struct ctree_root *root, struct tree_buffer *buf);

struct ctree_root *open_ctree(char *filename);

int close_ctree(struct ctree_root *root);

void tree_block_release(struct ctree_root *root, struct tree_buffer *buf);

struct tree_buffer *alloc_free_block(struct ctree_root *root);

int update_root_block(struct ctree_root *root);

#endif