X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fradix-tree.c;h=7097bb239e406b2ccca5772cb9516e852498f9ef;hb=ce362c009250340358a7221f3cdb7954cbf19c01;hp=88511c3805ad77fc9515b7a75bdc52e09a6393df;hpb=7079060f3e86ea4c1d4e9c1e356592ef9dcaaa1f;p=linux-2.6 diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 88511c3805..7097bb239e 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -37,7 +37,6 @@ #else #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ #endif -#define RADIX_TREE_TAGS 2 #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) @@ -48,7 +47,7 @@ struct radix_tree_node { unsigned int count; void *slots[RADIX_TREE_MAP_SIZE]; - unsigned long tags[RADIX_TREE_TAGS][RADIX_TREE_TAG_LONGS]; + unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; }; struct radix_tree_path { @@ -135,20 +134,36 @@ out: return ret; } -static inline void tag_set(struct radix_tree_node *node, int tag, int offset) +static inline void tag_set(struct radix_tree_node *node, unsigned int tag, + int offset) { - if (!test_bit(offset, &node->tags[tag][0])) - __set_bit(offset, &node->tags[tag][0]); + __set_bit(offset, node->tags[tag]); } -static inline void tag_clear(struct radix_tree_node *node, int tag, int offset) +static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, + int offset) { - __clear_bit(offset, &node->tags[tag][0]); + __clear_bit(offset, node->tags[tag]); } -static inline int tag_get(struct radix_tree_node *node, int tag, int offset) +static inline int tag_get(struct radix_tree_node *node, unsigned int tag, + int offset) { - return test_bit(offset, &node->tags[tag][0]); + return test_bit(offset, node->tags[tag]); +} + +/* + * Returns 1 if any slot in the node has this tag set. + * Otherwise returns 0. + */ +static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) +{ + int idx; + for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { + if (node->tags[tag][idx]) + return 1; + } + return 0; } /* @@ -167,7 +182,7 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) { struct radix_tree_node *node; unsigned int height; - char tags[RADIX_TREE_TAGS]; + char tags[RADIX_TREE_MAX_TAGS]; int tag; /* Figure out what the height should be. */ @@ -184,16 +199,10 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) * Prepare the tag status of the top-level node for propagation * into the newly-pushed top-level node(s) */ - for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { - int idx; - + for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { tags[tag] = 0; - for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { - if (root->rnode->tags[tag][idx]) { - tags[tag] = 1; - break; - } - } + if (any_tag_set(root->rnode, tag)) + tags[tag] = 1; } do { @@ -204,7 +213,7 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) node->slots[0] = root->rnode; /* Propagate the aggregated tag info into the new root */ - for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { + for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { if (tags[tag]) tag_set(node, tag, 0); } @@ -246,7 +255,7 @@ int radix_tree_insert(struct radix_tree_root *root, shift = (height-1) * RADIX_TREE_MAP_SHIFT; offset = 0; /* uninitialised var warning */ - while (height > 0) { + do { if (slot == NULL) { /* Have to add a child node. */ if (!(slot = radix_tree_node_alloc(root))) @@ -264,18 +273,16 @@ int radix_tree_insert(struct radix_tree_root *root, slot = node->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; height--; - } + } while (height > 0); if (slot != NULL) return -EEXIST; - if (node) { - node->count++; - node->slots[offset] = item; - BUG_ON(tag_get(node, 0, offset)); - BUG_ON(tag_get(node, 1, offset)); - } else - root->rnode = item; + BUG_ON(!node); + node->count++; + node->slots[offset] = item; + BUG_ON(tag_get(node, 0, offset)); + BUG_ON(tag_get(node, 1, offset)); return 0; } @@ -344,14 +351,15 @@ EXPORT_SYMBOL(radix_tree_lookup); * @index: index key * @tag: tag index * - * Set the search tag corresponging to @index in the radix tree. From + * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) + * corresponding to @index in the radix tree. From * the root all the way down to the leaf node. * * Returns the address of the tagged item. Setting a tag on a not-present * item is a bug. */ void *radix_tree_tag_set(struct radix_tree_root *root, - unsigned long index, int tag) + unsigned long index, unsigned int tag) { unsigned int height, shift; struct radix_tree_node *slot; @@ -367,7 +375,8 @@ void *radix_tree_tag_set(struct radix_tree_root *root, int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - tag_set(slot, tag, offset); + if (!tag_get(slot, tag, offset)) + tag_set(slot, tag, offset); slot = slot->slots[offset]; BUG_ON(slot == NULL); shift -= RADIX_TREE_MAP_SHIFT; @@ -384,7 +393,8 @@ EXPORT_SYMBOL(radix_tree_tag_set); * @index: index key * @tag: tag index * - * Clear the search tag corresponging to @index in the radix tree. If + * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) + * corresponding to @index in the radix tree. If * this causes the leaf node to have no tags set then clear the tag in the * next-to-leaf node, etc. * @@ -392,7 +402,7 @@ EXPORT_SYMBOL(radix_tree_tag_set); * has the same return value and semantics as radix_tree_lookup(). */ void *radix_tree_tag_clear(struct radix_tree_root *root, - unsigned long index, int tag) + unsigned long index, unsigned int tag) { struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; struct radix_tree_node *slot; @@ -427,13 +437,11 @@ void *radix_tree_tag_clear(struct radix_tree_root *root, goto out; do { - int idx; - + if (!tag_get(pathp->node, tag, pathp->offset)) + goto out; tag_clear(pathp->node, tag, pathp->offset); - for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { - if (pathp->node->tags[tag][idx]) - goto out; - } + if (any_tag_set(pathp->node, tag)) + goto out; pathp--; } while (pathp->node); out: @@ -446,7 +454,7 @@ EXPORT_SYMBOL(radix_tree_tag_clear); * radix_tree_tag_get - get a tag on a radix tree node * @root: radix tree root * @index: index key - * @tag: tag index + * @tag: tag index (< RADIX_TREE_MAX_TAGS) * * Return values: * @@ -455,7 +463,7 @@ EXPORT_SYMBOL(radix_tree_tag_clear); * -1: tag present, unset */ int radix_tree_tag_get(struct radix_tree_root *root, - unsigned long index, int tag) + unsigned long index, unsigned int tag) { unsigned int height, shift; struct radix_tree_node *slot; @@ -588,7 +596,7 @@ EXPORT_SYMBOL(radix_tree_gang_lookup); */ static unsigned int __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index, - unsigned int max_items, unsigned long *next_index, int tag) + unsigned int max_items, unsigned long *next_index, unsigned int tag) { unsigned int nr_found = 0; unsigned int shift; @@ -642,7 +650,7 @@ out: * @results: where the results of the lookup are placed * @first_index: start the lookup from this key * @max_items: place up to this many items at *results - * @tag: the tag index + * @tag: the tag index (< RADIX_TREE_MAX_TAGS) * * Performs an index-ascending scan of the tree for present items which * have the tag indexed by @tag set. Places the items at *@results and @@ -650,7 +658,8 @@ out: */ unsigned int radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, - unsigned long first_index, unsigned int max_items, int tag) + unsigned long first_index, unsigned int max_items, + unsigned int tag) { const unsigned long max_index = radix_tree_maxindex(root->height); unsigned long cur_index = first_index; @@ -673,6 +682,29 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, } EXPORT_SYMBOL(radix_tree_gang_lookup_tag); +/** + * radix_tree_shrink - shrink height of a radix tree to minimal + * @root radix tree root + */ +static inline void radix_tree_shrink(struct radix_tree_root *root) +{ + /* try to shrink tree height */ + while (root->height > 1 && + root->rnode->count == 1 && + root->rnode->slots[0]) { + struct radix_tree_node *to_free = root->rnode; + + root->rnode = to_free->slots[0]; + root->height--; + /* must only free zeroed nodes into the slab */ + tag_clear(to_free, 0, 0); + tag_clear(to_free, 1, 0); + to_free->slots[0] = NULL; + to_free->count = 0; + radix_tree_node_free(to_free); + } +} + /** * radix_tree_delete - delete an item from a radix tree * @root: radix tree root @@ -689,8 +721,10 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) struct radix_tree_node *slot; unsigned int height, shift; void *ret = NULL; - char tags[RADIX_TREE_TAGS]; + char tags[RADIX_TREE_MAX_TAGS]; int nr_cleared_tags; + int tag; + int offset; height = root->height; if (index > radix_tree_maxindex(height)) @@ -701,16 +735,14 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) slot = root->rnode; for ( ; height > 0; height--) { - int offset; - if (slot == NULL) goto out; + pathp++; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - pathp[1].offset = offset; - pathp[1].node = slot; + pathp->offset = offset; + pathp->node = slot; slot = slot->slots[offset]; - pathp++; shift -= RADIX_TREE_MAP_SHIFT; } @@ -723,35 +755,41 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) /* * Clear all tags associated with the just-deleted item */ - memset(tags, 0, sizeof(tags)); - do { - int tag; - - nr_cleared_tags = RADIX_TREE_TAGS; - for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { - int idx; + nr_cleared_tags = 0; + for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { + tags[tag] = 1; + if (tag_get(pathp->node, tag, pathp->offset)) { + tag_clear(pathp->node, tag, pathp->offset); + if (!any_tag_set(pathp->node, tag)) { + tags[tag] = 0; + nr_cleared_tags++; + } + } + } + for (pathp--; nr_cleared_tags && pathp->node; pathp--) { + for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { if (tags[tag]) continue; tag_clear(pathp->node, tag, pathp->offset); - - for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { - if (pathp->node->tags[tag][idx]) { - tags[tag] = 1; - nr_cleared_tags--; - break; - } + if (any_tag_set(pathp->node, tag)) { + tags[tag] = 1; + nr_cleared_tags--; } } - pathp--; - } while (pathp->node && nr_cleared_tags); + } /* Now free the nodes we do not need anymore */ for (pathp = orig_pathp; pathp->node; pathp--) { pathp->node->slots[pathp->offset] = NULL; - if (--pathp->node->count) + pathp->node->count--; + + if (pathp->node->count) { + if (pathp->node == root->rnode) + radix_tree_shrink(root); goto out; + } /* Node with zero slots in use so free it */ radix_tree_node_free(pathp->node); @@ -768,17 +806,13 @@ EXPORT_SYMBOL(radix_tree_delete); * @root: radix tree root * @tag: tag to test */ -int radix_tree_tagged(struct radix_tree_root *root, int tag) +int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) { - int idx; - - if (!root->rnode) - return 0; - for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { - if (root->rnode->tags[tag][idx]) - return 1; - } - return 0; + struct radix_tree_node *rnode; + rnode = root->rnode; + if (!rnode) + return 0; + return any_tag_set(rnode, tag); } EXPORT_SYMBOL(radix_tree_tagged);