[PATCH 7/9] lib: radix-tree: update callback for changing leaf nodes
From: Johannes Weiner
Date: Thu Nov 17 2016 - 14:31:43 EST
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.
Suggested-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
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 @@ static int radix_tree_extend(struct radix_tree_root *root,
* 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 7f3a08df25c9..62ac381069fc 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;
}
--
2.10.2