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-rw-r--r--lib/radix-tree.c143
1 files changed, 85 insertions, 58 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 88511c3805ad..c0bd4a914803 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -137,18 +137,31 @@ out:
static inline void tag_set(struct radix_tree_node *node, 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)
{
- __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)
{
- 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, int tag)
+{
+ int idx;
+ for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
+ if (node->tags[tag][idx])
+ return 1;
+ }
+ return 0;
}
/*
@@ -185,15 +198,9 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
* into the newly-pushed top-level node(s)
*/
for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
- int idx;
-
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 {
@@ -246,7 +253,7 @@ 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 +271,16 @@ 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;
}
@@ -367,7 +372,8 @@ 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;
@@ -427,13 +433,11 @@ 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:
@@ -674,6 +678,29 @@ 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
* @index: index key
@@ -691,6 +718,8 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
void *ret = NULL;
char tags[RADIX_TREE_TAGS];
int nr_cleared_tags;
+ int tag;
+ int offset;
height = root->height;
if (index > radix_tree_maxindex(height))
@@ -701,16 +730,14 @@ 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 +750,39 @@ 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 = 0;
+ for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
+ if (tag_get(pathp->node, tag, pathp->offset)) {
+ tag_clear(pathp->node, tag, pathp->offset);
+ tags[tag] = 0;
+ nr_cleared_tags++;
+ } else
+ tags[tag] = 1;
+ }
- nr_cleared_tags = RADIX_TREE_TAGS;
+ for (pathp--; nr_cleared_tags && pathp->node; pathp--) {
for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
- int idx;
-
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);
@@ -770,15 +801,11 @@ EXPORT_SYMBOL(radix_tree_delete);
*/
int radix_tree_tagged(struct radix_tree_root *root, 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);
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-07 04:23:30 +0100