[PATCH v2 26/29] radix-tree: Rewrite radix_tree_locate_item

Matthew Wilcox
2016-04-14T14:26:49Z

Use the new multi-order support functions to rewrite
radix_tree_locate_item(). Modify the locate tests to test multiorder
entries too.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
lib/radix-tree.c | 90 ++++++++++++++++++++---------------------
tools/testing/radix-tree/main.c | 30 ++++++++------
2 files changed, 63 insertions(+), 57 deletions(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 9b5d8a9..c08b1b6 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1303,58 +1303,55 @@ EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
#include <linux/sched.h> /* for cond_resched() */

+struct locate_info {
+ unsigned long found_index;
+ bool stop;
+};
+
/*
* This linear search is at present only useful to shmem_unuse_inode().
*/
static unsigned long __locate(struct radix_tree_node *slot, void *item,
- unsigned long index, unsigned long *found_index)
+ unsigned long index, struct locate_info *info)
{
unsigned int shift, height;
- unsigned long i;
+ unsigned long base, i;

height = slot->path & RADIX_TREE_HEIGHT_MASK;
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+ shift = height * RADIX_TREE_MAP_SHIFT;

- for ( ; height > 1; height--) {
- i = (index >> shift) & RADIX_TREE_MAP_MASK;
- for (;;) {
- if (slot->slots[i] != NULL)
- break;
- index &= ~((1UL << shift) - 1);
- index += 1UL << shift;
- if (index == 0)
- goto out; /* 32-bit wraparound */
- i++;
- if (i == RADIX_TREE_MAP_SIZE)
+ do {
+ shift -= RADIX_TREE_MAP_SHIFT;
+ base = index & ~((1UL << shift) - 1);
+
+ for (i = (index >> shift) & RADIX_TREE_MAP_MASK;
+ i < RADIX_TREE_MAP_SIZE;
+ i++, index = base + (i << shift)) {
+ struct radix_tree_node *node =
+ rcu_dereference_raw(slot->slots[i]);
+ if (node == RADIX_TREE_RETRY)
goto out;
- }
-
- slot = rcu_dereference_raw(slot->slots[i]);
- if (slot == NULL)
- goto out;
- if (!radix_tree_is_indirect_ptr(slot)) {
- if (slot == item) {
- *found_index = index + i;
- index = 0;
- } else {
- index += shift;
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (node == item) {
+ info->found_index = index;
+ info->stop = true;
+ goto out;
+ }
+ continue;
}
- goto out;
+ node = indirect_to_ptr(node);
+ if (is_sibling_entry(slot, node))
+ continue;
+ slot = node;
+ break;
}
- slot = indirect_to_ptr(slot);
- shift -= RADIX_TREE_MAP_SHIFT;
- }
+ if (i == RADIX_TREE_MAP_SIZE)
+ break;
+ } while (shift);

- /* Bottom level: check items */
- for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
- if (slot->slots[i] == item) {
- *found_index = index + i;
- index = 0;
- goto out;
- }
- }
- index += RADIX_TREE_MAP_SIZE;
out:
+ if ((index == 0) && (i == RADIX_TREE_MAP_SIZE))
+ info->stop = true;
return index;
}

@@ -1372,7 +1369,10 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
struct radix_tree_node *node;
unsigned long max_index;
unsigned long cur_index = 0;
- unsigned long found_index = -1;
+ struct locate_info info = {
+ .found_index = -1,
+ .stop = false,
+ };

do {
rcu_read_lock();
@@ -1380,24 +1380,24 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
if (!radix_tree_is_indirect_ptr(node)) {
rcu_read_unlock();
if (node == item)
- found_index = 0;
+ info.found_index = 0;
break;
}

node = indirect_to_ptr(node);
- max_index = radix_tree_maxindex(node->path &
- RADIX_TREE_HEIGHT_MASK);
+
+ max_index = node_maxindex(node);
if (cur_index > max_index) {
rcu_read_unlock();
break;
}

- cur_index = __locate(node, item, cur_index, &found_index);
+ cur_index = __locate(node, item, cur_index, &info);
rcu_read_unlock();
cond_resched();
- } while (cur_index != 0 && cur_index <= max_index);
+ } while (!info.stop && cur_index <= max_index);

- return found_index;
+ return info.found_index;
}
#else
unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index b6a700b..65231e9 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -232,17 +232,18 @@ void copy_tag_check(void)
item_kill_tree(&tree);
}

-void __locate_check(struct radix_tree_root *tree, unsigned long index)
+void __locate_check(struct radix_tree_root *tree, unsigned long index,
+ unsigned order)
{
struct item *item;
unsigned long index2;

- item_insert(tree, index);
+ item_insert_order(tree, index, order);
item = item_lookup(tree, index);
index2 = radix_tree_locate_item(tree, item);
if (index != index2) {
- printf("index %ld inserted; found %ld\n",
- index, index2);
+ printf("index %ld order %d inserted; found %ld\n",
+ index, order, index2);
abort();
}
}
@@ -250,21 +251,26 @@ void __locate_check(struct radix_tree_root *tree, unsigned long index)
static void locate_check(void)
{
RADIX_TREE(tree, GFP_KERNEL);
+ unsigned order;
unsigned long offset, index;

- for (offset = 0; offset < (1 << 3); offset++) {
- for (index = 0; index < (1UL << 5); index++) {
- __locate_check(&tree, index + offset);
- }
- if (radix_tree_locate_item(&tree, &tree) != -1)
- abort();
+ for (order = 0; order < 20; order++) {
+ for (offset = 0; offset < (1 << (order + 3));
+ offset += (1UL << order)) {
+ for (index = 0; index < (1UL << (order + 5));
+ index += (1UL << order)) {
+ __locate_check(&tree, index + offset, order);
+ }
+ if (radix_tree_locate_item(&tree, &tree) != -1)
+ abort();

- item_kill_tree(&tree);
+ item_kill_tree(&tree);
+ }
}

if (radix_tree_locate_item(&tree, &tree) != -1)
abort();
- __locate_check(&tree, -1);
+ __locate_check(&tree, -1, 0);
if (radix_tree_locate_item(&tree, &tree) != -1)
abort();
item_kill_tree(&tree);
--
2.8.0.rc3