1 /* 2 * Copyright (C) 2011 Red Hat, Inc. 3 * 4 * This file is released under the GPL. 5 */ 6 #ifndef _LINUX_DM_BTREE_H 7 #define _LINUX_DM_BTREE_H 8 9 #include "dm-block-manager.h" 10 11 struct dm_transaction_manager; 12 13 /*----------------------------------------------------------------*/ 14 15 /* 16 * Annotations used to check on-disk metadata is handled as little-endian. 17 */ 18 #ifdef __CHECKER__ 19 # define __dm_written_to_disk(x) __releases(x) 20 # define __dm_reads_from_disk(x) __acquires(x) 21 # define __dm_bless_for_disk(x) __acquire(x) 22 # define __dm_unbless_for_disk(x) __release(x) 23 #else 24 # define __dm_written_to_disk(x) 25 # define __dm_reads_from_disk(x) 26 # define __dm_bless_for_disk(x) 27 # define __dm_unbless_for_disk(x) 28 #endif 29 30 /*----------------------------------------------------------------*/ 31 32 /* 33 * Manipulates hierarchical B+ trees with 64-bit keys and arbitrary-sized 34 * values. 35 */ 36 37 /* 38 * Information about the values stored within the btree. 39 */ 40 struct dm_btree_value_type { 41 void *context; 42 43 /* 44 * The size in bytes of each value. 45 */ 46 uint32_t size; 47 48 /* 49 * Any of these methods can be safely set to NULL if you do not 50 * need the corresponding feature. 51 */ 52 53 /* 54 * The btree is making a duplicate of the value, for instance 55 * because previously-shared btree nodes have now diverged. 56 * @value argument is the new copy that the copy function may modify. 57 * (Probably it just wants to increment a reference count 58 * somewhere.) This method is _not_ called for insertion of a new 59 * value: It is assumed the ref count is already 1. 60 */ 61 void (*inc)(void *context, void *value); 62 63 /* 64 * This value is being deleted. The btree takes care of freeing 65 * the memory pointed to by @value. Often the del function just 66 * needs to decrement a reference count somewhere. 67 */ 68 void (*dec)(void *context, void *value); 69 70 /* 71 * A test for equality between two values. When a value is 72 * overwritten with a new one, the old one has the dec method 73 * called _unless_ the new and old value are deemed equal. 74 */ 75 int (*equal)(void *context, void *value1, void *value2); 76 }; 77 78 /* 79 * The shape and contents of a btree. 80 */ 81 struct dm_btree_info { 82 struct dm_transaction_manager *tm; 83 84 /* 85 * Number of nested btrees. (Not the depth of a single tree.) 86 */ 87 unsigned levels; 88 struct dm_btree_value_type value_type; 89 }; 90 91 /* 92 * Set up an empty tree. O(1). 93 */ 94 int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root); 95 96 /* 97 * Delete a tree. O(n) - this is the slow one! It can also block, so 98 * please don't call it on an IO path. 99 */ 100 int dm_btree_del(struct dm_btree_info *info, dm_block_t root); 101 102 /* 103 * All the lookup functions return -ENODATA if the key cannot be found. 104 */ 105 106 /* 107 * Tries to find a key that matches exactly. O(ln(n)) 108 */ 109 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root, 110 uint64_t *keys, void *value_le); 111 112 /* 113 * Insertion (or overwrite an existing value). O(ln(n)) 114 */ 115 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root, 116 uint64_t *keys, void *value, dm_block_t *new_root) 117 __dm_written_to_disk(value); 118 119 /* 120 * A variant of insert that indicates whether it actually inserted or just 121 * overwrote. Useful if you're keeping track of the number of entries in a 122 * tree. 123 */ 124 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root, 125 uint64_t *keys, void *value, dm_block_t *new_root, 126 int *inserted) 127 __dm_written_to_disk(value); 128 129 /* 130 * Remove a key if present. This doesn't remove empty sub trees. Normally 131 * subtrees represent a separate entity, like a snapshot map, so this is 132 * correct behaviour. O(ln(n)). 133 */ 134 int dm_btree_remove(struct dm_btree_info *info, dm_block_t root, 135 uint64_t *keys, dm_block_t *new_root); 136 137 /* 138 * Returns < 0 on failure. Otherwise the number of key entries that have 139 * been filled out. Remember trees can have zero entries, and as such have 140 * no highest key. 141 */ 142 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root, 143 uint64_t *result_keys); 144 145 #endif /* _LINUX_DM_BTREE_H */ 146