Piteball/android_kernel_google_msm
1
0
Fork 0
mirror of https://github.com/followmsi/android_kernel_google_msm.git synced 2024-11-06 23:17:41 +00:00
Code Issues Projects Releases Wiki Activity

[PATCH] radix-tree: reduce tree height upon partial truncation

Browse source 
Shrink the height of a radix tree when it is partially truncated - we only do
shrinkage of full truncation at present.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin 2006-01-08 01:01:41 -08:00 committed by Linus Torvalds
parent d5274261ea
commit a5f51c9667
1 changed files with 36 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

46
lib/radix-tree.c
View file

@ -253,7 +253,7 @@ int radix_tree_insert(struct radix_tree_root *root,
shift = (height-1) * RADIX_TREE_MAP_SHIFT; shift = (height-1) * RADIX_TREE_MAP_SHIFT;
offset = 0; /* uninitialised var warning */ offset = 0; /* uninitialised var warning */
while (height > 0) { do {
if (slot == NULL) { if (slot == NULL) {
/* Have to add a child node. */ /* Have to add a child node. */
if (!(slot = radix_tree_node_alloc(root))) if (!(slot = radix_tree_node_alloc(root)))
@ -271,18 +271,16 @@ int radix_tree_insert(struct radix_tree_root *root,
slot = node->slots[offset]; slot = node->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--; height--;
} } while (height > 0);
if (slot != NULL) if (slot != NULL)
return -EEXIST; return -EEXIST;
if (node) { BUG_ON(!node);
node->count++; node->count++;
node->slots[offset] = item; node->slots[offset] = item;
BUG_ON(tag_get(node, 0, offset)); BUG_ON(tag_get(node, 0, offset));
BUG_ON(tag_get(node, 1, offset)); BUG_ON(tag_get(node, 1, offset));
} else
root->rnode = item;
return 0; return 0;
} }
@ -679,6 +677,29 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
} }
EXPORT_SYMBOL(radix_tree_gang_lookup_tag); 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 * radix_tree_delete - delete an item from a radix tree
* @root: radix tree root * @root: radix tree root
@ -755,8 +776,13 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
/* Now free the nodes we do not need anymore */ /* Now free the nodes we do not need anymore */
for (pathp = orig_pathp; pathp->node; pathp--) { for (pathp = orig_pathp; pathp->node; pathp--) {
pathp->node->slots[pathp->offset] = NULL; 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; goto out;
}
/* Node with zero slots in use so free it */ /* Node with zero slots in use so free it */
radix_tree_node_free(pathp->node); radix_tree_node_free(pathp->node);