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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/btree.h>#include <linux/cache.h>#include <linux/kernel.h>#include <linux/slab.h>#include <linux/module.h>
#define NODESIZE MAX(L1_CACHE_BYTES, 128)
struct btree_geo { int keylen; int no_pairs; int no_longs;};
struct btree_geo btree_geo32 = { .keylen = 1, .no_pairs = NODESIZE / sizeof(long) / 2, .no_longs = NODESIZE / sizeof(long) / 2,};EXPORT_SYMBOL_GPL(btree_geo32);
#define LONG_PER_U64 (64 / BITS_PER_LONG)struct btree_geo btree_geo64 = { .keylen = LONG_PER_U64, .no_pairs = NODESIZE / sizeof(long) / (1 + LONG_PER_U64), .no_longs = LONG_PER_U64 * (NODESIZE / sizeof(long) / (1 + LONG_PER_U64)),};EXPORT_SYMBOL_GPL(btree_geo64);
struct btree_geo btree_geo128 = { .keylen = 2 * LONG_PER_U64, .no_pairs = NODESIZE / sizeof(long) / (1 + 2 * LONG_PER_U64), .no_longs = 2 * LONG_PER_U64 * (NODESIZE / sizeof(long) / (1 + 2 * LONG_PER_U64)),};EXPORT_SYMBOL_GPL(btree_geo128);
#define MAX_KEYLEN (2 * LONG_PER_U64)
static struct kmem_cache *btree_cachep;
void *btree_alloc(gfp_t gfp_mask, void *pool_data){ return kmem_cache_alloc(btree_cachep, gfp_mask);}EXPORT_SYMBOL_GPL(btree_alloc);
void btree_free(void *element, void *pool_data){ kmem_cache_free(btree_cachep, element);}EXPORT_SYMBOL_GPL(btree_free);
static unsigned long *btree_node_alloc(struct btree_head *head, gfp_t gfp){ unsigned long *node;
node = mempool_alloc(head->mempool, gfp); if (likely(node)) memset(node, 0, NODESIZE); return node;}
static int longcmp(const unsigned long *l1, const unsigned long *l2, size_t n){ size_t i;
for (i = 0; i < n; i++) { if (l1[i] < l2[i]) return -1; if (l1[i] > l2[i]) return 1; } return 0;}
static unsigned long *longcpy(unsigned long *dest, const unsigned long *src, size_t n){ size_t i;
for (i = 0; i < n; i++) dest[i] = src[i]; return dest;}
static unsigned long *longset(unsigned long *s, unsigned long c, size_t n){ size_t i;
for (i = 0; i < n; i++) s[i] = c; return s;}
static void dec_key(struct btree_geo *geo, unsigned long *key){ unsigned long val; int i;
for (i = geo->keylen - 1; i >= 0; i--) { val = key[i]; key[i] = val - 1; if (val) break; }}
static unsigned long *bkey(struct btree_geo *geo, unsigned long *node, int n){ return &node[n * geo->keylen];}
static void *bval(struct btree_geo *geo, unsigned long *node, int n){ return (void *)node[geo->no_longs + n];}
static void setkey(struct btree_geo *geo, unsigned long *node, int n, unsigned long *key){ longcpy(bkey(geo, node, n), key, geo->keylen);}
static void setval(struct btree_geo *geo, unsigned long *node, int n, void *val){ node[geo->no_longs + n] = (unsigned long) val;}
static void clearpair(struct btree_geo *geo, unsigned long *node, int n){ longset(bkey(geo, node, n), 0, geo->keylen); node[geo->no_longs + n] = 0;}
static inline void __btree_init(struct btree_head *head){ head->node = NULL; head->height = 0;}
void btree_init_mempool(struct btree_head *head, mempool_t *mempool){ __btree_init(head); head->mempool = mempool;}EXPORT_SYMBOL_GPL(btree_init_mempool);
int btree_init(struct btree_head *head){ __btree_init(head); head->mempool = mempool_create(0, btree_alloc, btree_free, NULL); if (!head->mempool) return -ENOMEM; return 0;}EXPORT_SYMBOL_GPL(btree_init);
void btree_destroy(struct btree_head *head){ mempool_free(head->node, head->mempool); mempool_destroy(head->mempool); head->mempool = NULL;}EXPORT_SYMBOL_GPL(btree_destroy);
void *btree_last(struct btree_head *head, struct btree_geo *geo, unsigned long *key){ int height = head->height; unsigned long *node = head->node;
if (height == 0) return NULL;
for ( ; height > 1; height--) node = bval(geo, node, 0);
longcpy(key, bkey(geo, node, 0), geo->keylen); return bval(geo, node, 0);}EXPORT_SYMBOL_GPL(btree_last);
static int keycmp(struct btree_geo *geo, unsigned long *node, int pos, unsigned long *key){ return longcmp(bkey(geo, node, pos), key, geo->keylen);}
static int keyzero(struct btree_geo *geo, unsigned long *key){ int i;
for (i = 0; i < geo->keylen; i++) if (key[i]) return 0;
return 1;}
static void *btree_lookup_node(struct btree_head *head, struct btree_geo *geo, unsigned long *key){ int i, height = head->height; unsigned long *node = head->node;
if (height == 0) return NULL;
for ( ; height > 1; height--) { for (i = 0; i < geo->no_pairs; i++) if (keycmp(geo, node, i, key) <= 0) break; if (i == geo->no_pairs) return NULL; node = bval(geo, node, i); if (!node) return NULL; } return node;}
void *btree_lookup(struct btree_head *head, struct btree_geo *geo, unsigned long *key){ int i; unsigned long *node;
node = btree_lookup_node(head, geo, key); if (!node) return NULL;
for (i = 0; i < geo->no_pairs; i++) if (keycmp(geo, node, i, key) == 0) return bval(geo, node, i); return NULL;}EXPORT_SYMBOL_GPL(btree_lookup);
int btree_update(struct btree_head *head, struct btree_geo *geo, unsigned long *key, void *val){ int i; unsigned long *node;
node = btree_lookup_node(head, geo, key); if (!node) return -ENOENT;
for (i = 0; i < geo->no_pairs; i++) if (keycmp(geo, node, i, key) == 0) { setval(geo, node, i, val); return 0; } return -ENOENT;}EXPORT_SYMBOL_GPL(btree_update);
/* * Usually this function is quite similar to normal lookup. But the key of * a parent node may be smaller than the smallest key of all its siblings. * In such a case we cannot just return NULL, as we have only proven that no * key smaller than __key, but larger than this parent key exists. * So we set __key to the parent key and retry. We have to use the smallest * such parent key, which is the last parent key we encountered. */void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, unsigned long *__key){ int i, height; unsigned long *node, *oldnode; unsigned long *retry_key = NULL, key[MAX_KEYLEN];
if (keyzero(geo, __key)) return NULL;
if (head->height == 0) return NULL; longcpy(key, __key, geo->keylen);retry: dec_key(geo, key);
node = head->node; for (height = head->height ; height > 1; height--) { for (i = 0; i < geo->no_pairs; i++) if (keycmp(geo, node, i, key) <= 0) break; if (i == geo->no_pairs) goto miss; oldnode = node; node = bval(geo, node, i); if (!node) goto miss; retry_key = bkey(geo, oldnode, i); }
if (!node) goto miss;
for (i = 0; i < geo->no_pairs; i++) { if (keycmp(geo, node, i, key) <= 0) { if (bval(geo, node, i)) { longcpy(__key, bkey(geo, node, i), geo->keylen); return bval(geo, node, i); } else goto miss; } }miss: if (retry_key) { longcpy(key, retry_key, geo->keylen); retry_key = NULL; goto retry; } return NULL;}EXPORT_SYMBOL_GPL(btree_get_prev);
static int getpos(struct btree_geo *geo, unsigned long *node, unsigned long *key){ int i;
for (i = 0; i < geo->no_pairs; i++) { if (keycmp(geo, node, i, key) <= 0) break; } return i;}
static int getfill(struct btree_geo *geo, unsigned long *node, int start){ int i;
for (i = start; i < geo->no_pairs; i++) if (!bval(geo, node, i)) break; return i;}
/* * locate the correct leaf node in the btree */static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo, unsigned long *key, int level){ unsigned long *node = head->node; int i, height;
for (height = head->height; height > level; height--) { for (i = 0; i < geo->no_pairs; i++) if (keycmp(geo, node, i, key) <= 0) break;
if ((i == geo->no_pairs) || !bval(geo, node, i)) { /* right-most key is too large, update it */ /* FIXME: If the right-most key on higher levels is * always zero, this wouldn't be necessary. */ i--; setkey(geo, node, i, key); } BUG_ON(i < 0); node = bval(geo, node, i); } BUG_ON(!node); return node;}
static int btree_grow(struct btree_head *head, struct btree_geo *geo, gfp_t gfp){ unsigned long *node; int fill;
node = btree_node_alloc(head, gfp); if (!node) return -ENOMEM; if (head->node) { fill = getfill(geo, head->node, 0); setkey(geo, node, 0, bkey(geo, head->node, fill - 1)); setval(geo, node, 0, head->node); } head->node = node; head->height++; return 0;}
static void btree_shrink(struct btree_head *head, struct btree_geo *geo){ unsigned long *node; int fill;
if (head->height <= 1) return;
node = head->node; fill = getfill(geo, node, 0); BUG_ON(fill > 1); head->node = bval(geo, node, 0); head->height--; mempool_free(node, head->mempool);}
static int btree_insert_level(struct btree_head *head, struct btree_geo *geo, unsigned long *key, void *val, int level, gfp_t gfp){ unsigned long *node; int i, pos, fill, err;
BUG_ON(!val); if (head->height < level) { err = btree_grow(head, geo, gfp); if (err) return err; }
retry: node = find_level(head, geo, key, level); pos = getpos(geo, node, key); fill = getfill(geo, node, pos); /* two identical keys are not allowed */ BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0);
if (fill == geo->no_pairs) { /* need to split node */ unsigned long *new;
new = btree_node_alloc(head, gfp); if (!new) return -ENOMEM; err = btree_insert_level(head, geo, bkey(geo, node, fill / 2 - 1), new, level + 1, gfp); if (err) { mempool_free(new, head->mempool); return err; } for (i = 0; i < fill / 2; i++) { setkey(geo, new, i, bkey(geo, node, i)); setval(geo, new, i, bval(geo, node, i)); setkey(geo, node, i, bkey(geo, node, i + fill / 2)); setval(geo, node, i, bval(geo, node, i + fill / 2)); clearpair(geo, node, i + fill / 2); } if (fill & 1) { setkey(geo, node, i, bkey(geo, node, fill - 1)); setval(geo, node, i, bval(geo, node, fill - 1)); clearpair(geo, node, fill - 1); } goto retry; } BUG_ON(fill >= geo->no_pairs);
/* shift and insert */ for (i = fill; i > pos; i--) { setkey(geo, node, i, bkey(geo, node, i - 1)); setval(geo, node, i, bval(geo, node, i - 1)); } setkey(geo, node, pos, key); setval(geo, node, pos, val);
return 0;}
int btree_insert(struct btree_head *head, struct btree_geo *geo, unsigned long *key, void *val, gfp_t gfp){ BUG_ON(!val); return btree_insert_level(head, geo, key, val, 1, gfp);}EXPORT_SYMBOL_GPL(btree_insert);
static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, unsigned long *key, int level);static void merge(struct btree_head *head, struct btree_geo *geo, int level, unsigned long *left, int lfill, unsigned long *right, int rfill, unsigned long *parent, int lpos){ int i;
for (i = 0; i < rfill; i++) { /* Move all keys to the left */ setkey(geo, left, lfill + i, bkey(geo, right, i)); setval(geo, left, lfill + i, bval(geo, right, i)); } /* Exchange left and right child in parent */ setval(geo, parent, lpos, right); setval(geo, parent, lpos + 1, left); /* Remove left (formerly right) child from parent */ btree_remove_level(head, geo, bkey(geo, parent, lpos), level + 1); mempool_free(right, head->mempool);}
static void rebalance(struct btree_head *head, struct btree_geo *geo, unsigned long *key, int level, unsigned long *child, int fill){ unsigned long *parent, *left = NULL, *right = NULL; int i, no_left, no_right;
if (fill == 0) { /* Because we don't steal entries from a neighbour, this case * can happen. Parent node contains a single child, this * node, so merging with a sibling never happens. */ btree_remove_level(head, geo, key, level + 1); mempool_free(child, head->mempool); return; }
parent = find_level(head, geo, key, level + 1); i = getpos(geo, parent, key); BUG_ON(bval(geo, parent, i) != child);
if (i > 0) { left = bval(geo, parent, i - 1); no_left = getfill(geo, left, 0); if (fill + no_left <= geo->no_pairs) { merge(head, geo, level, left, no_left, child, fill, parent, i - 1); return; } } if (i + 1 < getfill(geo, parent, i)) { right = bval(geo, parent, i + 1); no_right = getfill(geo, right, 0); if (fill + no_right <= geo->no_pairs) { merge(head, geo, level, child, fill, right, no_right, parent, i); return; } } /* * We could also try to steal one entry from the left or right * neighbor. By not doing so we changed the invariant from * "all nodes are at least half full" to "no two neighboring * nodes can be merged". Which means that the average fill of * all nodes is still half or better. */}
static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, unsigned long *key, int level){ unsigned long *node; int i, pos, fill; void *ret;
if (level > head->height) { /* we recursed all the way up */ head->height = 0; head->node = NULL; return NULL; }
node = find_level(head, geo, key, level); pos = getpos(geo, node, key); fill = getfill(geo, node, pos); if ((level == 1) && (keycmp(geo, node, pos, key) != 0)) return NULL; ret = bval(geo, node, pos);
/* remove and shift */ for (i = pos; i < fill - 1; i++) { setkey(geo, node, i, bkey(geo, node, i + 1)); setval(geo, node, i, bval(geo, node, i + 1)); } clearpair(geo, node, fill - 1);
if (fill - 1 < geo->no_pairs / 2) { if (level < head->height) rebalance(head, geo, key, level, node, fill - 1); else if (fill - 1 == 1) btree_shrink(head, geo); }
return ret;}
void *btree_remove(struct btree_head *head, struct btree_geo *geo, unsigned long *key){ if (head->height == 0) return NULL;
return btree_remove_level(head, geo, key, 1);}EXPORT_SYMBOL_GPL(btree_remove);
int btree_merge(struct btree_head *target, struct btree_head *victim, struct btree_geo *geo, gfp_t gfp){ unsigned long key[MAX_KEYLEN]; unsigned long dup[MAX_KEYLEN]; void *val; int err;
BUG_ON(target == victim);
if (!(target->node)) { /* target is empty, just copy fields over */ target->node = victim->node; target->height = victim->height; __btree_init(victim); return 0; }
/* TODO: This needs some optimizations. Currently we do three tree * walks to remove a single object from the victim. */ for (;;) { val = btree_last(victim, geo, key); if (!val) break; err = btree_insert(target, geo, key, val, gfp); if (err) return err; /* We must make a copy of the key, as the original will get * mangled inside btree_remove. */ longcpy(dup, key, geo->keylen); btree_remove(victim, geo, dup); } return 0;}EXPORT_SYMBOL_GPL(btree_merge);
static size_t __btree_for_each(struct btree_head *head, struct btree_geo *geo, unsigned long *node, unsigned long opaque, void (*func)(void *elem, unsigned long opaque, unsigned long *key, size_t index, void *func2), void *func2, int reap, int height, size_t count){ int i; unsigned long *child;
for (i = 0; i < geo->no_pairs; i++) { child = bval(geo, node, i); if (!child) break; if (height > 1) count = __btree_for_each(head, geo, child, opaque, func, func2, reap, height - 1, count); else func(child, opaque, bkey(geo, node, i), count++, func2); } if (reap) mempool_free(node, head->mempool); return count;}
static void empty(void *elem, unsigned long opaque, unsigned long *key, size_t index, void *func2){}
void visitorl(void *elem, unsigned long opaque, unsigned long *key, size_t index, void *__func){ visitorl_t func = __func;
func(elem, opaque, *key, index);}EXPORT_SYMBOL_GPL(visitorl);
void visitor32(void *elem, unsigned long opaque, unsigned long *__key, size_t index, void *__func){ visitor32_t func = __func; u32 *key = (void *)__key;
func(elem, opaque, *key, index);}EXPORT_SYMBOL_GPL(visitor32);
void visitor64(void *elem, unsigned long opaque, unsigned long *__key, size_t index, void *__func){ visitor64_t func = __func; u64 *key = (void *)__key;
func(elem, opaque, *key, index);}EXPORT_SYMBOL_GPL(visitor64);
void visitor128(void *elem, unsigned long opaque, unsigned long *__key, size_t index, void *__func){ visitor128_t func = __func; u64 *key = (void *)__key;
func(elem, opaque, key[0], key[1], index);}EXPORT_SYMBOL_GPL(visitor128);
size_t btree_visitor(struct btree_head *head, struct btree_geo *geo, unsigned long opaque, void (*func)(void *elem, unsigned long opaque, unsigned long *key, size_t index, void *func2), void *func2){ size_t count = 0;
if (!func2) func = empty; if (head->node) count = __btree_for_each(head, geo, head->node, opaque, func, func2, 0, head->height, 0); return count;}EXPORT_SYMBOL_GPL(btree_visitor);
size_t btree_grim_visitor(struct btree_head *head, struct btree_geo *geo, unsigned long opaque, void (*func)(void *elem, unsigned long opaque, unsigned long *key, size_t index, void *func2), void *func2){ size_t count = 0;
if (!func2) func = empty; if (head->node) count = __btree_for_each(head, geo, head->node, opaque, func, func2, 1, head->height, 0); __btree_init(head); return count;}EXPORT_SYMBOL_GPL(btree_grim_visitor);
static int __init btree_module_init(void){ btree_cachep = kmem_cache_create("btree_node", NODESIZE, 0, SLAB_HWCACHE_ALIGN, NULL); return 0;}
static void __exit btree_module_exit(void){ kmem_cache_destroy(btree_cachep);}
/* If core code starts using btree, initialization should happen even earlier */module_init(btree_module_init);module_exit(btree_module_exit);
MODULE_AUTHOR("Joern Engel <joern@logfs.org>");MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>");