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radix-tree: introduce radix_tree_replace_clear_tags()

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In addition to replacing the entry, we also clear all associated tags.
This is really a one-off special for page_cache_tree_delete() which had
far too much detailed knowledge about how the radix tree works.

For efficiency, factor node_tag_clear() out of radix_tree_tag_clear() It
can be used by radix_tree_delete_item() as well as
radix_tree_replace_clear_tags().

Signed-off-by: Matthew Wilcox <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Kirill Shutemov <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Ross Zwisler <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Matthew Wilcox 2016-05-20 17:03:45 -07:00 • committed by Linus Torvalds
commit d604c32452
3 changed files with 56 additions and 52 deletions
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76
lib/radix-tree.c
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@ -740,6 +740,26 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
}
EXPORT_SYMBOL(radix_tree_tag_set);
static void node_tag_clear(struct radix_tree_root *root,
struct radix_tree_node *node,
unsigned int tag, unsigned int offset)
{
while (node) {
if (!tag_get(node, tag, offset))
return;
tag_clear(node, tag, offset);
if (any_tag_set(node, tag))
return;
offset = node->offset;
node = node->parent;
}
/* clear the root's tag bit */
if (root_tag_get(root, tag))
root_tag_clear(root, tag);
}
/**
* radix_tree_tag_clear - clear a tag on a radix tree node
* @root: radix tree root
@ -776,28 +796,9 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
offset = radix_tree_descend(parent, &node, offset);
}
if (node == NULL)
goto out;
if (node)
node_tag_clear(root, parent, tag, offset);
index >>= shift;
while (parent) {
if (!tag_get(parent, tag, offset))
goto out;
tag_clear(parent, tag, offset);
if (any_tag_set(parent, tag))
goto out;
index >>= RADIX_TREE_MAP_SHIFT;
offset = index & RADIX_TREE_MAP_MASK;
parent = parent->parent;
}
/* clear the root's tag bit */
if (root_tag_get(root, tag))
root_tag_clear(root, tag);
out:
return node;
}
EXPORT_SYMBOL(radix_tree_tag_clear);
@ -1525,14 +1526,9 @@ void *radix_tree_delete_item(struct radix_tree_root *root,
offset = get_slot_offset(node, slot);
/*
* Clear all tags associated with the item to be deleted.
* This way of doing it would be inefficient, but seldom is any set.
*/
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
if (tag_get(node, tag, offset))
radix_tree_tag_clear(root, index, tag);
}
/* Clear all tags associated with the item to be deleted. */
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
delete_sibling_entries(node, node_to_entry(slot), offset);
node->slots[offset] = NULL;
@ -1559,6 +1555,28 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
}
EXPORT_SYMBOL(radix_tree_delete);
struct radix_tree_node *radix_tree_replace_clear_tags(
struct radix_tree_root *root,
unsigned long index, void *entry)
{
struct radix_tree_node *node;
void **slot;
__radix_tree_lookup(root, index, &node, &slot);
if (node) {
unsigned int tag, offset = get_slot_offset(node, slot);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
} else {
/* Clear root node tags */
root->gfp_mask &= __GFP_BITS_MASK;
}
radix_tree_replace_slot(slot, entry);
return node;
}
/**
* radix_tree_tagged - test whether any items in the tree are tagged
* @root: radix tree root