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radix-tree: add missing sibling entry functionality

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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: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2016-05-20 17:01:57 -07:00 committed by Linus Torvalds
parent 57578c2ea2
commit db050f2924
1 changed files with 40 additions and 0 deletions
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40
lib/radix-tree.c
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@ -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;