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radix-tree: replace node->height with node->shift

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node->shift represents the shift necessary for looking in the slots
array at this level.  It is equal to the old (node->height - 1) *
RADIX_TREE_MAP_SHIFT.

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 17:03:10 -07:00 committed by Linus Torvalds
parent 0c7fa0a841
commit c12e51b07b
2 changed files with 17 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/radix-tree.h
View File

@ -89,7 +89,7 @@ static inline int radix_tree_is_indirect_ptr(void *ptr)
#define RADIX_TREE_COUNT_MASK ((1UL << RADIX_TREE_COUNT_SHIFT) - 1) #define RADIX_TREE_COUNT_MASK ((1UL << RADIX_TREE_COUNT_SHIFT) - 1)
struct radix_tree_node { struct radix_tree_node {
unsigned char height; /* From the bottom */ unsigned char shift; /* Bits remaining in each slot */
unsigned char offset; /* Slot offset in parent */ unsigned char offset; /* Slot offset in parent */
unsigned int count; unsigned int count;
union { union {

30
lib/radix-tree.c
View File

@ -223,10 +223,10 @@ static void dump_node(struct radix_tree_node *node,
{ {
unsigned long i; unsigned long i;
pr_debug("radix node: %p offset %d tags %lx %lx %lx height %d count %d parent %p\n", pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d parent %p\n",
node, node->offset, node, node->offset,
node->tags[0][0], node->tags[1][0], node->tags[2][0], node->tags[0][0], node->tags[1][0], node->tags[2][0],
node->height, node->count, node->parent); node->shift, node->count, node->parent);
for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
unsigned long first = index | (i << shift); unsigned long first = index | (i << shift);
@ -419,9 +419,14 @@ static inline unsigned long radix_tree_maxindex(unsigned int height)
return height_to_maxindex[height]; return height_to_maxindex[height];
} }
static inline unsigned long shift_maxindex(unsigned int shift)
{
return (RADIX_TREE_MAP_SIZE << shift) - 1;
}
static inline unsigned long node_maxindex(struct radix_tree_node *node) static inline unsigned long node_maxindex(struct radix_tree_node *node)
{ {
return radix_tree_maxindex(node->height); return shift_maxindex(node->shift);
} }
static unsigned radix_tree_load_root(struct radix_tree_root *root, static unsigned radix_tree_load_root(struct radix_tree_root *root,
@ -434,7 +439,7 @@ static unsigned radix_tree_load_root(struct radix_tree_root *root,
if (likely(radix_tree_is_indirect_ptr(node))) { if (likely(radix_tree_is_indirect_ptr(node))) {
node = indirect_to_ptr(node); node = indirect_to_ptr(node);
*maxindex = node_maxindex(node); *maxindex = node_maxindex(node);
return node->height * RADIX_TREE_MAP_SHIFT; return node->shift + RADIX_TREE_MAP_SHIFT;
} }
*maxindex = 0; *maxindex = 0;
@ -475,9 +480,9 @@ static int radix_tree_extend(struct radix_tree_root *root,
} }
/* Increase the height. */ /* Increase the height. */
newheight = root->height + 1; newheight = root->height;
BUG_ON(newheight > BITS_PER_LONG); BUG_ON(newheight > BITS_PER_LONG);
node->height = newheight; node->shift = newheight * RADIX_TREE_MAP_SHIFT;
node->offset = 0; node->offset = 0;
node->count = 1; node->count = 1;
node->parent = NULL; node->parent = NULL;
@ -490,7 +495,7 @@ static int radix_tree_extend(struct radix_tree_root *root,
node->slots[0] = slot; node->slots[0] = slot;
node = ptr_to_indirect(node); node = ptr_to_indirect(node);
rcu_assign_pointer(root->rnode, node); rcu_assign_pointer(root->rnode, node);
root->height = newheight; root->height = ++newheight;
} while (height > root->height); } while (height > root->height);
out: out:
return height * RADIX_TREE_MAP_SHIFT; return height * RADIX_TREE_MAP_SHIFT;
@ -519,7 +524,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
{ {
struct radix_tree_node *node = NULL, *slot; struct radix_tree_node *node = NULL, *slot;
unsigned long maxindex; unsigned long maxindex;
unsigned int height, shift, offset; unsigned int shift, offset;
unsigned long max = index | ((1UL << order) - 1); unsigned long max = index | ((1UL << order) - 1);
shift = radix_tree_load_root(root, &slot, &maxindex); shift = radix_tree_load_root(root, &slot, &maxindex);
@ -537,16 +542,15 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
} }
} }
height = root->height;
offset = 0; /* uninitialised var warning */ offset = 0; /* uninitialised var warning */
while (shift > order) { while (shift > order) {
shift -= RADIX_TREE_MAP_SHIFT;
if (slot == NULL) { if (slot == NULL) {
/* Have to add a child node. */ /* Have to add a child node. */
slot = radix_tree_node_alloc(root); slot = radix_tree_node_alloc(root);
if (!slot) if (!slot)
return -ENOMEM; return -ENOMEM;
slot->height = height; slot->shift = shift;
slot->offset = offset; slot->offset = offset;
slot->parent = node; slot->parent = node;
if (node) { if (node) {
@ -560,8 +564,6 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
break; break;
/* Go a level down */ /* Go a level down */
height--;
shift -= RADIX_TREE_MAP_SHIFT;
node = indirect_to_ptr(slot); node = indirect_to_ptr(slot);
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
offset = radix_tree_descend(node, &slot, offset); offset = radix_tree_descend(node, &slot, offset);
@ -1322,7 +1324,7 @@ static unsigned long __locate(struct radix_tree_node *slot, void *item,
unsigned int shift; unsigned int shift;
unsigned long i; unsigned long i;
shift = slot->height * RADIX_TREE_MAP_SHIFT; shift = slot->shift + RADIX_TREE_MAP_SHIFT;
do { do {
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;