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Date: Thu, 14 Apr 2016 10:37:20 -0400
From: Matthew Wilcox <willy@...ux.intel.com>
To: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Matthew Wilcox <willy@...ux.intel.com>, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
Konstantin Khlebnikov <koct9i@...il.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Jan Kara <jack@...e.com>, Neil Brown <neilb@...e.de>,
Ross Zwisler <ross.zwisler@...ux.intel.com>
Subject: [PATCH 17/19] radix-tree: Make radix_tree_descend() more useful
Now that the shift amount is stored in the node, radix_tree_descend()
can calculate offset itself from index, which removes several lines of
code from each of the tree walkers.
Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>
---
lib/radix-tree.c | 78 +++++++++++++++++++-------------------------------------
1 file changed, 26 insertions(+), 52 deletions(-)
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 4574848..8ee2447 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -94,9 +94,10 @@ static inline unsigned long get_slot_offset(struct radix_tree_node *parent,
return slot - parent->slots;
}
-static unsigned radix_tree_descend(struct radix_tree_node *parent,
- struct radix_tree_node **nodep, unsigned offset)
+static unsigned int radix_tree_descend(struct radix_tree_node *parent,
+ struct radix_tree_node **nodep, unsigned long index)
{
+ unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
void **entry = rcu_dereference_raw(parent->slots[offset]);
#ifdef CONFIG_RADIX_TREE_MULTIORDER
@@ -536,8 +537,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
/* Go a level down */
node = entry_to_node(child);
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- offset = radix_tree_descend(node, &child, offset);
+ offset = radix_tree_descend(node, &child, index);
slot = &node->slots[offset];
}
@@ -625,13 +625,12 @@ void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
- unsigned int shift;
void **slot;
restart:
parent = NULL;
slot = (void **)&root->rnode;
- shift = radix_tree_load_root(root, &node, &maxindex);
+ radix_tree_load_root(root, &node, &maxindex);
if (index > maxindex)
return NULL;
@@ -641,9 +640,7 @@ void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
if (node == RADIX_TREE_RETRY)
goto restart;
parent = entry_to_node(node);
- shift -= RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- offset = radix_tree_descend(parent, &node, offset);
+ offset = radix_tree_descend(parent, &node, index);
slot = parent->slots + offset;
}
@@ -713,19 +710,15 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
- unsigned int shift;
- shift = radix_tree_load_root(root, &node, &maxindex);
+ radix_tree_load_root(root, &node, &maxindex);
BUG_ON(index > maxindex);
while (radix_tree_is_internal_node(node)) {
unsigned offset;
- shift -= RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
-
parent = entry_to_node(node);
- offset = radix_tree_descend(parent, &node, offset);
+ offset = radix_tree_descend(parent, &node, index);
BUG_ON(!node);
if (!tag_get(parent, tag, offset))
@@ -779,21 +772,17 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
- unsigned int shift;
int uninitialized_var(offset);
- shift = radix_tree_load_root(root, &node, &maxindex);
+ radix_tree_load_root(root, &node, &maxindex);
if (index > maxindex)
return NULL;
parent = NULL;
while (radix_tree_is_internal_node(node)) {
- shift -= RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
-
parent = entry_to_node(node);
- offset = radix_tree_descend(parent, &node, offset);
+ offset = radix_tree_descend(parent, &node, index);
}
if (node)
@@ -823,25 +812,21 @@ int radix_tree_tag_get(struct radix_tree_root *root,
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
- unsigned int shift;
if (!root_tag_get(root, tag))
return 0;
- shift = radix_tree_load_root(root, &node, &maxindex);
+ radix_tree_load_root(root, &node, &maxindex);
if (index > maxindex)
return 0;
if (node == NULL)
return 0;
while (radix_tree_is_internal_node(node)) {
- int offset;
-
- shift -= RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ unsigned offset;
parent = entry_to_node(node);
- offset = radix_tree_descend(parent, &node, offset);
+ offset = radix_tree_descend(parent, &node, index);
if (!node)
return 0;
@@ -874,7 +859,7 @@ static inline void __set_iter_shift(struct radix_tree_iter *iter,
void **radix_tree_next_chunk(struct radix_tree_root *root,
struct radix_tree_iter *iter, unsigned flags)
{
- unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
+ unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
struct radix_tree_node *node, *child;
unsigned long index, offset, maxindex;
@@ -895,7 +880,7 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
return NULL;
restart:
- shift = radix_tree_load_root(root, &child, &maxindex);
+ radix_tree_load_root(root, &child, &maxindex);
if (index > maxindex)
return NULL;
if (!child)
@@ -912,9 +897,7 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
do {
node = entry_to_node(child);
- shift -= RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- offset = radix_tree_descend(node, &child, offset);
+ offset = radix_tree_descend(node, &child, index);
if ((flags & RADIX_TREE_ITER_TAGGED) ?
!tag_get(node, tag, offset) : !child) {
@@ -936,7 +919,7 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
break;
}
index &= ~node_maxindex(node);
- index += offset << shift;
+ index += offset << node->shift;
/* Overflow after ~0UL */
if (!index)
return NULL;
@@ -952,7 +935,7 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
/* Update the iterator state */
iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
iter->next_index = (index | node_maxindex(node)) + 1;
- __set_iter_shift(iter, shift);
+ __set_iter_shift(iter, node->shift);
/* Construct iter->tags bit-mask from node->tags[tag] array */
if (flags & RADIX_TREE_ITER_TAGGED) {
@@ -1010,10 +993,10 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
{
struct radix_tree_node *parent, *node, *child;
unsigned long maxindex;
- unsigned int shift = radix_tree_load_root(root, &child, &maxindex);
unsigned long tagged = 0;
unsigned long index = *first_indexp;
+ radix_tree_load_root(root, &child, &maxindex);
last_index = min(last_index, maxindex);
if (index > last_index)
return 0;
@@ -1030,11 +1013,9 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
}
node = entry_to_node(child);
- shift -= RADIX_TREE_MAP_SHIFT;
for (;;) {
- unsigned offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- offset = radix_tree_descend(node, &child, offset);
+ unsigned offset = radix_tree_descend(node, &child, index);
if (!child)
goto next;
if (!tag_get(node, iftag, offset))
@@ -1042,7 +1023,6 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
/* Sibling slots never have tags set on them */
if (radix_tree_is_internal_node(child)) {
node = entry_to_node(child);
- shift -= RADIX_TREE_MAP_SHIFT;
continue;
}
@@ -1063,12 +1043,12 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
tag_set(parent, settag, offset);
}
next:
- /* Go to next item at level determined by 'shift' */
- index = ((index >> shift) + 1) << shift;
+ /* Go to next entry in node */
+ index = ((index >> node->shift) + 1) << node->shift;
/* Overflow can happen when last_index is ~0UL... */
if (index > last_index || !index)
break;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ offset = (index >> node->shift) & RADIX_TREE_MAP_MASK;
while (offset == 0) {
/*
* We've fully scanned this node. Go up. Because
@@ -1076,8 +1056,7 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
* we do below cannot wander astray.
*/
node = node->parent;
- shift += RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ offset = (index >> node->shift) & RADIX_TREE_MAP_MASK;
}
if (is_sibling_entry(node, node->slots[offset]))
goto next;
@@ -1275,13 +1254,10 @@ struct locate_info {
static unsigned long __locate(struct radix_tree_node *slot, void *item,
unsigned long index, struct locate_info *info)
{
- unsigned int shift;
unsigned long base, i;
- shift = slot->shift + RADIX_TREE_MAP_SHIFT;
-
do {
- shift -= RADIX_TREE_MAP_SHIFT;
+ unsigned int shift = slot->shift;
base = index & ~((1UL << shift) - 1);
for (i = (index >> shift) & RADIX_TREE_MAP_MASK;
@@ -1305,9 +1281,7 @@ static unsigned long __locate(struct radix_tree_node *slot, void *item,
slot = node;
break;
}
- if (i == RADIX_TREE_MAP_SIZE)
- break;
- } while (shift);
+ } while (i < RADIX_TREE_MAP_SIZE);
out:
if ((index == 0) && (i == RADIX_TREE_MAP_SIZE))
--
2.8.0.rc3
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