From 4d693d08607ab319095ec8942909df4b4aebdf66 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 12 Dec 2016 16:43:49 -0800 Subject: [PATCH] lib: radix-tree: update callback for changing leaf nodes Support handing __radix_tree_replace() a callback that gets invoked for all leaf nodes that change or get freed as a result of the slot replacement, to assist users tracking nodes with node->private_list. This prepares for putting page cache shadow entries into the radix tree root again and drastically simplifying the shadow tracking. Link: http://lkml.kernel.org/r/20161117193134.GD23430@cmpxchg.org Signed-off-by: Johannes Weiner Suggested-by: Jan Kara Reviewed-by: Jan Kara Cc: Kirill A. Shutemov Cc: Hugh Dickins Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dax.c | 3 ++- include/linux/radix-tree.h | 4 +++- lib/radix-tree.c | 42 ++++++++++++++++++++++++++------------ mm/shmem.c | 3 ++- 4 files changed, 36 insertions(+), 16 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 85930c2a2749..6916ed37d463 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -649,7 +649,8 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, ret = __radix_tree_lookup(page_tree, index, &node, &slot); WARN_ON_ONCE(ret != entry); - __radix_tree_replace(page_tree, node, slot, new_entry); + __radix_tree_replace(page_tree, node, slot, + new_entry, NULL, NULL); } if (vmf->flags & FAULT_FLAG_WRITE) radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 2d1b9b8be983..15c972ea9510 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -263,9 +263,11 @@ void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index, struct radix_tree_node **nodep, void ***slotp); void *radix_tree_lookup(struct radix_tree_root *, unsigned long); void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); +typedef void (*radix_tree_update_node_t)(struct radix_tree_node *, void *); void __radix_tree_replace(struct radix_tree_root *root, struct radix_tree_node *node, - void **slot, void *item); + void **slot, void *item, + radix_tree_update_node_t update_node, void *private); void radix_tree_replace_slot(struct radix_tree_root *root, void **slot, void *item); bool __radix_tree_delete_node(struct radix_tree_root *root, diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 5d8930f3b3d8..df4ff18dd63c 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -325,7 +325,6 @@ static void radix_tree_node_rcu_free(struct rcu_head *head) tag_clear(node, i, 0); node->slots[0] = NULL; - node->count = 0; kmem_cache_free(radix_tree_node_cachep, node); } @@ -542,7 +541,9 @@ out: * radix_tree_shrink - shrink radix tree to minimum height * @root radix tree root */ -static inline bool radix_tree_shrink(struct radix_tree_root *root) +static inline bool radix_tree_shrink(struct radix_tree_root *root, + radix_tree_update_node_t update_node, + void *private) { bool shrunk = false; @@ -597,8 +598,12 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root) * also results in a stale slot). So tag the slot as indirect * to force callers to retry. */ - if (!radix_tree_is_internal_node(child)) + node->count = 0; + if (!radix_tree_is_internal_node(child)) { node->slots[0] = RADIX_TREE_RETRY; + if (update_node) + update_node(node, private); + } radix_tree_node_free(node); shrunk = true; @@ -608,7 +613,8 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root) } static bool delete_node(struct radix_tree_root *root, - struct radix_tree_node *node) + struct radix_tree_node *node, + radix_tree_update_node_t update_node, void *private) { bool deleted = false; @@ -617,7 +623,8 @@ static bool delete_node(struct radix_tree_root *root, if (node->count) { if (node == entry_to_node(root->rnode)) - deleted |= radix_tree_shrink(root); + deleted |= radix_tree_shrink(root, update_node, + private); return deleted; } @@ -880,17 +887,20 @@ static void replace_slot(struct radix_tree_root *root, /** * __radix_tree_replace - replace item in a slot - * @root: radix tree root - * @node: pointer to tree node - * @slot: pointer to slot in @node - * @item: new item to store in the slot. + * @root: radix tree root + * @node: pointer to tree node + * @slot: pointer to slot in @node + * @item: new item to store in the slot. + * @update_node: callback for changing leaf nodes + * @private: private data to pass to @update_node * * For use with __radix_tree_lookup(). Caller must hold tree write locked * across slot lookup and replacement. */ void __radix_tree_replace(struct radix_tree_root *root, struct radix_tree_node *node, - void **slot, void *item) + void **slot, void *item, + radix_tree_update_node_t update_node, void *private) { /* * This function supports replacing exceptional entries and @@ -900,7 +910,13 @@ void __radix_tree_replace(struct radix_tree_root *root, replace_slot(root, node, slot, item, !node && slot != (void **)&root->rnode); - delete_node(root, node); + if (!node) + return; + + if (update_node) + update_node(node, private); + + delete_node(root, node, update_node, private); } /** @@ -1585,7 +1601,7 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) bool __radix_tree_delete_node(struct radix_tree_root *root, struct radix_tree_node *node) { - return delete_node(root, node); + return delete_node(root, node, NULL, NULL); } static inline void delete_sibling_entries(struct radix_tree_node *node, @@ -1642,7 +1658,7 @@ void *radix_tree_delete_item(struct radix_tree_root *root, node_tag_clear(root, node, tag, offset); delete_sibling_entries(node, node_to_entry(slot), offset); - __radix_tree_replace(root, node, slot, NULL); + __radix_tree_replace(root, node, slot, NULL, NULL, NULL); return entry; } diff --git a/mm/shmem.c b/mm/shmem.c index 3149ddee8f55..abd7403aba41 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -311,7 +311,8 @@ static int shmem_radix_tree_replace(struct address_space *mapping, return -ENOENT; if (item != expected) return -ENOENT; - __radix_tree_replace(&mapping->page_tree, node, pslot, replacement); + __radix_tree_replace(&mapping->page_tree, node, pslot, + replacement, NULL, NULL); return 0; } -- 2.20.1