![Joe Thornber](/assets/img/avatar_default.png)
Add dm_btree_walk to iterate through the contents of a btree. This will be used by the dm cache target. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
155 lines
4.3 KiB
C
155 lines
4.3 KiB
C
/*
|
|
* Copyright (C) 2011 Red Hat, Inc.
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
#ifndef _LINUX_DM_BTREE_H
|
|
#define _LINUX_DM_BTREE_H
|
|
|
|
#include "dm-block-manager.h"
|
|
|
|
struct dm_transaction_manager;
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Annotations used to check on-disk metadata is handled as little-endian.
|
|
*/
|
|
#ifdef __CHECKER__
|
|
# define __dm_written_to_disk(x) __releases(x)
|
|
# define __dm_reads_from_disk(x) __acquires(x)
|
|
# define __dm_bless_for_disk(x) __acquire(x)
|
|
# define __dm_unbless_for_disk(x) __release(x)
|
|
#else
|
|
# define __dm_written_to_disk(x)
|
|
# define __dm_reads_from_disk(x)
|
|
# define __dm_bless_for_disk(x)
|
|
# define __dm_unbless_for_disk(x)
|
|
#endif
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Manipulates hierarchical B+ trees with 64-bit keys and arbitrary-sized
|
|
* values.
|
|
*/
|
|
|
|
/*
|
|
* Information about the values stored within the btree.
|
|
*/
|
|
struct dm_btree_value_type {
|
|
void *context;
|
|
|
|
/*
|
|
* The size in bytes of each value.
|
|
*/
|
|
uint32_t size;
|
|
|
|
/*
|
|
* Any of these methods can be safely set to NULL if you do not
|
|
* need the corresponding feature.
|
|
*/
|
|
|
|
/*
|
|
* The btree is making a duplicate of the value, for instance
|
|
* because previously-shared btree nodes have now diverged.
|
|
* @value argument is the new copy that the copy function may modify.
|
|
* (Probably it just wants to increment a reference count
|
|
* somewhere.) This method is _not_ called for insertion of a new
|
|
* value: It is assumed the ref count is already 1.
|
|
*/
|
|
void (*inc)(void *context, const void *value);
|
|
|
|
/*
|
|
* This value is being deleted. The btree takes care of freeing
|
|
* the memory pointed to by @value. Often the del function just
|
|
* needs to decrement a reference count somewhere.
|
|
*/
|
|
void (*dec)(void *context, const void *value);
|
|
|
|
/*
|
|
* A test for equality between two values. When a value is
|
|
* overwritten with a new one, the old one has the dec method
|
|
* called _unless_ the new and old value are deemed equal.
|
|
*/
|
|
int (*equal)(void *context, const void *value1, const void *value2);
|
|
};
|
|
|
|
/*
|
|
* The shape and contents of a btree.
|
|
*/
|
|
struct dm_btree_info {
|
|
struct dm_transaction_manager *tm;
|
|
|
|
/*
|
|
* Number of nested btrees. (Not the depth of a single tree.)
|
|
*/
|
|
unsigned levels;
|
|
struct dm_btree_value_type value_type;
|
|
};
|
|
|
|
/*
|
|
* Set up an empty tree. O(1).
|
|
*/
|
|
int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root);
|
|
|
|
/*
|
|
* Delete a tree. O(n) - this is the slow one! It can also block, so
|
|
* please don't call it on an IO path.
|
|
*/
|
|
int dm_btree_del(struct dm_btree_info *info, dm_block_t root);
|
|
|
|
/*
|
|
* All the lookup functions return -ENODATA if the key cannot be found.
|
|
*/
|
|
|
|
/*
|
|
* Tries to find a key that matches exactly. O(ln(n))
|
|
*/
|
|
int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
|
|
uint64_t *keys, void *value_le);
|
|
|
|
/*
|
|
* Insertion (or overwrite an existing value). O(ln(n))
|
|
*/
|
|
int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
|
|
uint64_t *keys, void *value, dm_block_t *new_root)
|
|
__dm_written_to_disk(value);
|
|
|
|
/*
|
|
* A variant of insert that indicates whether it actually inserted or just
|
|
* overwrote. Useful if you're keeping track of the number of entries in a
|
|
* tree.
|
|
*/
|
|
int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
|
|
uint64_t *keys, void *value, dm_block_t *new_root,
|
|
int *inserted)
|
|
__dm_written_to_disk(value);
|
|
|
|
/*
|
|
* Remove a key if present. This doesn't remove empty sub trees. Normally
|
|
* subtrees represent a separate entity, like a snapshot map, so this is
|
|
* correct behaviour. O(ln(n)).
|
|
*/
|
|
int dm_btree_remove(struct dm_btree_info *info, dm_block_t root,
|
|
uint64_t *keys, dm_block_t *new_root);
|
|
|
|
/*
|
|
* Returns < 0 on failure. Otherwise the number of key entries that have
|
|
* been filled out. Remember trees can have zero entries, and as such have
|
|
* no highest key.
|
|
*/
|
|
int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
|
|
uint64_t *result_keys);
|
|
|
|
/*
|
|
* Iterate through the a btree, calling fn() on each entry.
|
|
* It only works for single level trees and is internally recursive, so
|
|
* monitor stack usage carefully.
|
|
*/
|
|
int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
|
|
int (*fn)(void *context, uint64_t *keys, void *leaf),
|
|
void *context);
|
|
|
|
#endif /* _LINUX_DM_BTREE_H */
|