149 lines
4.2 KiB
C
149 lines
4.2 KiB
C
#ifndef __CTREE__
|
|
#define __CTREE__
|
|
|
|
#define CTREE_BLOCKSIZE 1024
|
|
|
|
/*
|
|
* the key defines the order in the tree, and so it also defines (optimal)
|
|
* block layout. objectid corresonds to the inode number. The flags
|
|
* tells us things about the object, and is a kind of stream selector.
|
|
* so for a given inode, keys with flags of 1 might refer to the inode
|
|
* data, flags of 2 may point to file data in the btree and flags == 3
|
|
* may point to extents.
|
|
*
|
|
* offset is the starting byte offset for this key in the stream.
|
|
*/
|
|
struct key {
|
|
u64 objectid;
|
|
u32 flags;
|
|
u64 offset;
|
|
} __attribute__ ((__packed__));
|
|
|
|
/*
|
|
* every tree block (leaf or node) starts with this header.
|
|
*/
|
|
struct header {
|
|
u64 fsid[2]; /* FS specific uuid */
|
|
u64 blocknr; /* which block this node is supposed to live in */
|
|
u64 parentid; /* objectid of the tree root */
|
|
u32 csum;
|
|
u32 ham;
|
|
u16 nritems;
|
|
u16 flags;
|
|
/* generation flags to be added */
|
|
} __attribute__ ((__packed__));
|
|
|
|
#define NODEPTRS_PER_BLOCK ((CTREE_BLOCKSIZE - sizeof(struct header)) / \
|
|
(sizeof(struct key) + sizeof(u64)))
|
|
|
|
#define MAX_LEVEL 8
|
|
#define node_level(f) ((f) & (MAX_LEVEL-1))
|
|
#define is_leaf(f) (node_level(f) == 0)
|
|
|
|
struct tree_buffer;
|
|
|
|
/*
|
|
* in ram representation of the tree. extent_root is used for all allocations
|
|
* and for the extent tree extent_root root. current_insert is used
|
|
* only for the extent tree.
|
|
*/
|
|
struct ctree_root {
|
|
struct tree_buffer *node;
|
|
struct ctree_root *extent_root;
|
|
struct key current_insert;
|
|
int fp;
|
|
struct radix_tree_root cache_radix;
|
|
};
|
|
|
|
/*
|
|
* describes a tree on disk
|
|
*/
|
|
struct ctree_root_info {
|
|
u64 fsid[2]; /* FS specific uuid */
|
|
u64 blocknr; /* blocknr of this block */
|
|
u64 objectid; /* inode number of this root */
|
|
u64 tree_root; /* the tree root block */
|
|
u32 csum;
|
|
u32 ham;
|
|
u64 snapuuid[2]; /* root specific uuid */
|
|
} __attribute__ ((__packed__));
|
|
|
|
/*
|
|
* the super block basically lists the main trees of the FS
|
|
* it currently lacks any block count etc etc
|
|
*/
|
|
struct ctree_super_block {
|
|
struct ctree_root_info root_info;
|
|
struct ctree_root_info extent_info;
|
|
} __attribute__ ((__packed__));
|
|
|
|
/*
|
|
* A leaf is full of items. The exact type of item is defined by
|
|
* the key flags parameter. offset and size tell us where to find
|
|
* the item in the leaf (relative to the start of the data area)
|
|
*/
|
|
struct item {
|
|
struct key key;
|
|
u16 offset;
|
|
u16 size;
|
|
} __attribute__ ((__packed__));
|
|
|
|
/*
|
|
* leaves have an item area and a data area:
|
|
* [item0, item1....itemN] [free space] [dataN...data1, data0]
|
|
*
|
|
* The data is separate from the items to get the keys closer together
|
|
* during searches.
|
|
*/
|
|
#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__));
|
|
|
|
/*
|
|
* all non-leaf blocks are nodes, they hold only keys and pointers to
|
|
* other blocks
|
|
*/
|
|
struct node {
|
|
struct header header;
|
|
struct key keys[NODEPTRS_PER_BLOCK];
|
|
u64 blockptrs[NODEPTRS_PER_BLOCK];
|
|
} __attribute__ ((__packed__));
|
|
|
|
/*
|
|
* items in the extent btree are used to record the objectid of the
|
|
* owner of the block and the number of references
|
|
*/
|
|
struct extent_item {
|
|
u32 refs;
|
|
u64 owner;
|
|
} __attribute__ ((__packed__));
|
|
|
|
/*
|
|
* ctree_paths remember the path taken from the root down to the leaf.
|
|
* level 0 is always the leaf, and nodes[1...MAX_LEVEL] will point
|
|
* to any other levels that are present.
|
|
*
|
|
* The slots array records the index of the item or block pointer
|
|
* used while walking the tree.
|
|
*/
|
|
struct ctree_path {
|
|
struct tree_buffer *nodes[MAX_LEVEL];
|
|
int slots[MAX_LEVEL];
|
|
};
|
|
|
|
struct tree_buffer *alloc_free_block(struct ctree_root *root);
|
|
int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks);
|
|
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p, int ins_len);
|
|
void release_path(struct ctree_root *root, struct ctree_path *p);
|
|
void init_path(struct ctree_path *p);
|
|
int del_item(struct ctree_root *root, struct ctree_path *path);
|
|
int insert_item(struct ctree_root *root, struct key *key, void *data, int data_size);
|
|
int next_leaf(struct ctree_root *root, struct ctree_path *path);
|
|
int leaf_free_space(struct leaf *leaf);
|
|
#endif
|