From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: radix-tree: introduce radix_tree_replace_clear_tags()
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@xxxxxxxxxxxxxxx>
Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Cc: Kirill Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/radix-tree.h | 9 ++--
lib/radix-tree.c | 76 +++++++++++++++++++++--------------
mm/filemap.c | 23 +---------
3 files changed, 56 insertions(+), 52 deletions(-)
diff -puN include/linux/radix-tree.h~radix-tree-introduce-radix_tree_replace_clear_tags include/linux/radix-tree.h
--- a/include/linux/radix-tree.h~radix-tree-introduce-radix_tree_replace_clear_tags
+++ a/include/linux/radix-tree.h
@@ -281,9 +281,12 @@ bool __radix_tree_delete_node(struct rad
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);
diff -puN lib/radix-tree.c~radix-tree-introduce-radix_tree_replace_clear_tags lib/radix-tree.c
--- a/lib/radix-tree.c~radix-tree-introduce-radix_tree_replace_clear_tags
+++ a/lib/radix-tree.c
@@ -740,6 +740,26 @@ void *radix_tree_tag_set(struct radix_tr
}
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_
offset = radix_tree_descend(parent, &node, offset);
}
- if (node == NULL)
- goto out;
-
- 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;
- }
+ if (node)
+ node_tag_clear(root, parent, tag, offset);
- /* 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 radi
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_tre
}
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
diff -puN mm/filemap.c~radix-tree-introduce-radix_tree_replace_clear_tags mm/filemap.c
--- a/mm/filemap.c~radix-tree-introduce-radix_tree_replace_clear_tags
+++ a/mm/filemap.c
@@ -114,14 +114,11 @@ static void page_cache_tree_delete(struc
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(struc
}
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);
_
--
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