From d604c324524bf61c68182bb27db64656a78fe911 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 20 May 2016 17:03:45 -0700 Subject: [PATCH] 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 Cc: Konstantin Khlebnikov Cc: Kirill Shutemov Cc: Jan Kara Cc: Neil Brown Cc: Ross Zwisler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/radix-tree.h | 9 +++-- lib/radix-tree.c | 76 +++++++++++++++++++++++--------------- mm/filemap.c | 23 ++---------- 3 files changed, 56 insertions(+), 52 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index bad63105e37e..11c8e7cc3920 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -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); diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 9d9b4b9af4b6..c7114d233b38 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -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 diff --git a/mm/filemap.c b/mm/filemap.c index b418405903bc..9665b1d4f318 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -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); -- 2.20.1