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Commit db050f29 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
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radix-tree: add missing sibling entry functionality 



The code I previously added to enable multiorder radix tree entries was
untested and therefore buggy.  This commit adds the support functions
that Ross and I decided were necessary over a four-week period of
iterating various designs.

Signed-off-by: default avatarMatthew Wilcox <willy@linux.intel.com>
Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 57578c2e

lib/radix-tree.c

+40 −0
Original line number Diff line number Diff line
@@ -80,6 +80,46 @@ static inline void *indirect_to_ptr(void *ptr) 
	return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);

}



#ifdef CONFIG_RADIX_TREE_MULTIORDER

/* Sibling slots point directly to another slot in the same node */

static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)

{

	void **ptr = node;

	return (parent->slots <= ptr) &&

			(ptr < parent->slots + RADIX_TREE_MAP_SIZE);

}

#else

static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)

{

	return false;

}

#endif



static inline unsigned long get_slot_offset(struct radix_tree_node *parent,

						 void **slot)

{

	return slot - parent->slots;

}



static unsigned radix_tree_descend(struct radix_tree_node *parent,

				struct radix_tree_node **nodep, unsigned offset)

{

	void **entry = rcu_dereference_raw(parent->slots[offset]);



#ifdef CONFIG_RADIX_TREE_MULTIORDER

	if (radix_tree_is_indirect_ptr(entry)) {

		unsigned long siboff = get_slot_offset(parent, entry);

		if (siboff < RADIX_TREE_MAP_SIZE) {

			offset = siboff;

			entry = rcu_dereference_raw(parent->slots[offset]);

		}

	}

#endif



	*nodep = (void *)entry;

	return offset;

}



static inline gfp_t root_gfp_mask(struct radix_tree_root *root)

{

	return root->gfp_mask & __GFP_BITS_MASK;