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lib: radix-tree: update callback for changing leaf nodes

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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 <hannes@cmpxchg.org>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2016-12-12 16:43:49 -08:00 committed by Linus Torvalds
parent f4b109c6da
commit 4d693d0860
4 changed files with 36 additions and 16 deletions
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3
fs/dax.c
View File

@ -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);

4
include/linux/radix-tree.h
View File

@ -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,

42
lib/radix-tree.c
View File

@ -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;
}

3
mm/shmem.c
View File

@ -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;
}