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radix-tree: split node->path into offset and height

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Neither piece of information we're storing in node->path can be larger
than 64, so store each in its own unsigned char instead of shifting and
masking to store them both in an unsigned int.

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 17:03:07 -07:00
committed by Linus Torvalds
parent 2fcd9005cc
commit 0c7fa0a841
2 changed files with 19 additions and 26 deletions
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7
include/linux/radix-tree.h
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@@ -84,16 +84,13 @@ static inline int radix_tree_is_indirect_ptr(void *ptr)
#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
RADIX_TREE_MAP_SHIFT))
/* Height component in node->path */
#define RADIX_TREE_HEIGHT_SHIFT (RADIX_TREE_MAX_PATH + 1)
#define RADIX_TREE_HEIGHT_MASK ((1UL << RADIX_TREE_HEIGHT_SHIFT) - 1)
/* Internally used bits of node->count */
#define RADIX_TREE_COUNT_SHIFT (RADIX_TREE_MAP_SHIFT + 1)
#define RADIX_TREE_COUNT_MASK ((1UL << RADIX_TREE_COUNT_SHIFT) - 1)
struct radix_tree_node {
unsigned int path; /* Offset in parent & height from the bottom */
unsigned char height; /* From the bottom */
unsigned char offset; /* Slot offset in parent */
unsigned int count;
union {
struct {