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Commit 4d693d08 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarJan 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f4b109c6

fs/dax.c

+2 −1
Original line number Diff line number Diff line
@@ -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);

include/linux/radix-tree.h

+3 −1
Original line number Diff line number Diff line
@@ -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,

lib/radix-tree.c

+29 −13
Original line number Diff line number Diff line
@@ -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;

		}
@@ -884,13 +891,16 @@ static void replace_slot(struct radix_tree_root *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;

}

mm/shmem.c

+2 −1
Original line number Diff line number Diff line
@@ -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;

}