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xarray: Change definition of sibling entries

Telusuri Sumber 
Instead of storing a pointer to the slot containing the canonical entry,
store the offset of the slot.  Produces slightly more efficient code
(~300 bytes) and simplifies the implementation.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
This commit is contained in:
Matthew Wilcox
2017-11-03 23:09:45 -04:00
orang tua 3159f943aa
melakukan 02c02bf12c
6 mengubah file dengan 121 tambahan dan 50 penghapusan
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7
lib/Kconfig
Melihat File

@@ -399,8 +399,15 @@ config INTERVAL_TREE
for more information.
config XARRAY_MULTI
bool
help
Support entries which occupy multiple consecutive indices in the
XArray.
config RADIX_TREE_MULTIORDER
bool
select XARRAY_MULTI
config ASSOCIATIVE_ARRAY
bool

64
lib/radix-tree.c
Melihat File

@@ -38,6 +38,7 @@
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/xarray.h>
/* Number of nodes in fully populated tree of given height */
@@ -98,24 +99,7 @@ static inline void *node_to_entry(void *ptr)
return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
}
#define RADIX_TREE_RETRY node_to_entry(NULL)
#ifdef CONFIG_RADIX_TREE_MULTIORDER
/* Sibling slots point directly to another slot in the same node */
static inline
bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
{
void __rcu **ptr = node;
return (parent->slots <= ptr) &&
(ptr < parent->slots + RADIX_TREE_MAP_SIZE);
}
#else
static inline
bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
{
return false;
}
#endif
#define RADIX_TREE_RETRY XA_RETRY_ENTRY
static inline unsigned long
get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
@@ -129,16 +113,10 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
#ifdef CONFIG_RADIX_TREE_MULTIORDER
if (radix_tree_is_internal_node(entry)) {
if (is_sibling_entry(parent, entry)) {
void __rcu **sibentry;
sibentry = (void __rcu **) entry_to_node(entry);
offset = get_slot_offset(parent, sibentry);
entry = rcu_dereference_raw(*sibentry);
}
if (xa_is_sibling(entry)) {
offset = xa_to_sibling(entry);
entry = rcu_dereference_raw(parent->slots[offset]);
}
#endif
*nodep = (void *)entry;
return offset;
@@ -300,10 +278,10 @@ static void dump_node(struct radix_tree_node *node, unsigned long index)
} else if (!radix_tree_is_internal_node(entry)) {
pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
entry, i, first, last, node);
} else if (is_sibling_entry(node, entry)) {
} else if (xa_is_sibling(entry)) {
pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
entry, i, first, last, node,
*(void **)entry_to_node(entry));
node->slots[xa_to_sibling(entry)]);
} else {
dump_node(entry_to_node(entry), first);
}
@@ -881,8 +859,7 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
for (;;) {
void *entry = rcu_dereference_raw(child->slots[offset]);
if (radix_tree_is_internal_node(entry) && child->shift &&
!is_sibling_entry(child, entry)) {
if (xa_is_node(entry) && child->shift) {
child = entry_to_node(entry);
offset = 0;
continue;
@@ -904,7 +881,7 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
static inline int insert_entries(struct radix_tree_node *node,
void __rcu **slot, void *item, unsigned order, bool replace)
{
struct radix_tree_node *child;
void *sibling;
unsigned i, n, tag, offset, tags = 0;
if (node) {
@@ -922,7 +899,7 @@ static inline int insert_entries(struct radix_tree_node *node,
offset = offset & ~(n - 1);
slot = &node->slots[offset];
}
child = node_to_entry(slot);
sibling = xa_mk_sibling(offset);
for (i = 0; i < n; i++) {
if (slot[i]) {
@@ -939,7 +916,7 @@ static inline int insert_entries(struct radix_tree_node *node,
for (i = 0; i < n; i++) {
struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
if (i) {
rcu_assign_pointer(slot[i], child);
rcu_assign_pointer(slot[i], sibling);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_clear(node, tag, offset + i);
@@ -949,9 +926,7 @@ static inline int insert_entries(struct radix_tree_node *node,
if (tags & (1 << tag))
tag_set(node, tag, offset);
}
if (radix_tree_is_internal_node(old) &&
!is_sibling_entry(node, old) &&
(old != RADIX_TREE_RETRY))
if (xa_is_node(old))
radix_tree_free_nodes(old);
if (xa_is_value(old))
node->exceptional--;
@@ -1112,10 +1087,10 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
void __rcu **slot, int count, int exceptional)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
void *ptr = node_to_entry(slot);
unsigned offset = get_slot_offset(node, slot) + 1;
unsigned offset = get_slot_offset(node, slot);
void *ptr = xa_mk_sibling(offset);
while (offset < RADIX_TREE_MAP_SIZE) {
while (++offset < RADIX_TREE_MAP_SIZE) {
if (rcu_dereference_raw(node->slots[offset]) != ptr)
break;
if (count < 0) {
@@ -1123,7 +1098,6 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
node->count--;
}
node->exceptional += exceptional;
offset++;
}
#endif
}
@@ -1319,8 +1293,7 @@ int radix_tree_split(struct radix_tree_root *root, unsigned long index,
tags |= 1 << tag;
for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
if (!is_sibling_entry(parent,
rcu_dereference_raw(parent->slots[end])))
if (!xa_is_sibling(rcu_dereference_raw(parent->slots[end])))
break;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
@@ -1618,7 +1591,7 @@ static void __rcu **skip_siblings(struct radix_tree_node **nodep,
{
while (iter->index < iter->next_index) {
*nodep = rcu_dereference_raw(*slot);
if (*nodep && !is_sibling_entry(iter->node, *nodep))
if (*nodep && !xa_is_sibling(*nodep))
return slot;
slot++;
iter->index = __radix_tree_iter_add(iter, 1);
@@ -1769,7 +1742,7 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
while (++offset < RADIX_TREE_MAP_SIZE) {
void *slot = rcu_dereference_raw(
node->slots[offset]);
if (is_sibling_entry(node, slot))
if (xa_is_sibling(slot))
continue;
if (slot)
break;
@@ -2283,6 +2256,7 @@ void __init radix_tree_init(void)
BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
sizeof(struct radix_tree_node), 0,
SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,