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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 <willy@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2016-05-20 17:03:45 -07:00 committed by Linus Torvalds
parent 89148aa402
commit d604c32452
3 changed files with 56 additions and 52 deletions
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9
include/linux/radix-tree.h
View File

@ -281,9 +281,12 @@ bool __radix_tree_delete_node(struct radix_tree_root *root,
struct radix_tree_node *node);
void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items);
struct radix_tree_node *radix_tree_replace_clear_tags(
struct radix_tree_root *root,
unsigned long index, void *entry);
unsigned int radix_tree_gang_lookup(struct radix_tree_root *root,
void **results, unsigned long first_index,
unsigned int max_items);
unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root,
void ***results, unsigned long *indices,
unsigned long first_index, unsigned int max_items);

76
lib/radix-tree.c
View File

@ -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

23
mm/filemap.c
View File

@ -114,14 +114,11 @@ static void page_cache_tree_delete(struct address_space *mapping,
struct page *page, void *shadow)
{
struct radix_tree_node *node;
unsigned long index;
unsigned int offset;
unsigned int tag;
void **slot;
VM_BUG_ON(!PageLocked(page));
__radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
node = radix_tree_replace_clear_tags(&mapping->page_tree, page->index,
shadow);
if (shadow) {
mapping->nrexceptional++;
@ -135,23 +132,9 @@ static void page_cache_tree_delete(struct address_space *mapping,
}
mapping->nrpages--;
if (!node) {
/* Clear direct pointer tags in root node */
mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
radix_tree_replace_slot(slot, shadow);
if (!node)
return;
}
/* Clear tree tags for the removed page */
index = page->index;
offset = index & RADIX_TREE_MAP_MASK;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
if (test_bit(offset, node->tags[tag]))
radix_tree_tag_clear(&mapping->page_tree, index, tag);
}
/* Delete page, swap shadow entry */
radix_tree_replace_slot(slot, shadow);
workingset_node_pages_dec(node);
if (shadow)
workingset_node_shadows_inc(node);