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Date: Thu, 14 Apr 2016 10:37:06 -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 03/19] radix-tree: Split node->path into offset and height
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@...ux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
---
include/linux/radix-tree.h | 7 ++-----
lib/radix-tree.c | 38 +++++++++++++++++---------------------
2 files changed, 19 insertions(+), 26 deletions(-)
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 8558d52..2d2ad9d 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -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 {
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 746a240..d42c5b5 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -218,15 +218,15 @@ radix_tree_find_next_bit(const unsigned long *addr,
}
#ifndef __KERNEL__
-static void dump_node(struct radix_tree_node *node, unsigned offset,
+static void dump_node(struct radix_tree_node *node,
unsigned shift, unsigned long index)
{
unsigned long i;
- pr_debug("radix node: %p offset %d tags %lx %lx %lx path %x count %d parent %p\n",
- node, offset,
+ pr_debug("radix node: %p offset %d tags %lx %lx %lx height %d count %d parent %p\n",
+ node, node->offset,
node->tags[0][0], node->tags[1][0], node->tags[2][0],
- node->path, node->count, node->parent);
+ node->height, node->count, node->parent);
for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
unsigned long first = index | (i << shift);
@@ -243,7 +243,7 @@ static void dump_node(struct radix_tree_node *node, unsigned offset,
pr_debug("radix entry %p offset %ld indices %ld-%ld\n",
entry, i, first, last);
} else {
- dump_node(indirect_to_ptr(entry), i,
+ dump_node(indirect_to_ptr(entry),
shift - RADIX_TREE_MAP_SHIFT, first);
}
}
@@ -257,7 +257,7 @@ static void radix_tree_dump(struct radix_tree_root *root)
root->gfp_mask >> __GFP_BITS_SHIFT);
if (!radix_tree_is_indirect_ptr(root->rnode))
return;
- dump_node(indirect_to_ptr(root->rnode), 0,
+ dump_node(indirect_to_ptr(root->rnode),
(root->height - 1) * RADIX_TREE_MAP_SHIFT, 0);
}
#endif
@@ -421,7 +421,7 @@ static inline unsigned long radix_tree_maxindex(unsigned int height)
static inline unsigned long node_maxindex(struct radix_tree_node *node)
{
- return radix_tree_maxindex(node->path & RADIX_TREE_HEIGHT_MASK);
+ return radix_tree_maxindex(node->height);
}
static unsigned radix_tree_load_root(struct radix_tree_root *root,
@@ -434,8 +434,7 @@ static unsigned radix_tree_load_root(struct radix_tree_root *root,
if (likely(radix_tree_is_indirect_ptr(node))) {
node = indirect_to_ptr(node);
*maxindex = node_maxindex(node);
- return (node->path & RADIX_TREE_HEIGHT_MASK) *
- RADIX_TREE_MAP_SHIFT;
+ return node->height * RADIX_TREE_MAP_SHIFT;
}
*maxindex = 0;
@@ -476,9 +475,10 @@ static int radix_tree_extend(struct radix_tree_root *root,
}
/* Increase the height. */
- newheight = root->height+1;
- BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK);
- node->path = newheight;
+ newheight = root->height + 1;
+ BUG_ON(newheight > BITS_PER_LONG);
+ node->height = newheight;
+ node->offset = 0;
node->count = 1;
node->parent = NULL;
slot = root->rnode;
@@ -546,13 +546,13 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
slot = radix_tree_node_alloc(root);
if (!slot)
return -ENOMEM;
- slot->path = height;
+ slot->height = height;
+ slot->offset = offset;
slot->parent = node;
if (node) {
rcu_assign_pointer(node->slots[offset],
ptr_to_indirect(slot));
node->count++;
- slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT;
} else
rcu_assign_pointer(root->rnode,
ptr_to_indirect(slot));
@@ -1319,11 +1319,10 @@ struct locate_info {
static unsigned long __locate(struct radix_tree_node *slot, void *item,
unsigned long index, struct locate_info *info)
{
- unsigned int shift, height;
+ unsigned int shift;
unsigned long base, i;
- height = slot->path & RADIX_TREE_HEIGHT_MASK;
- shift = height * RADIX_TREE_MAP_SHIFT;
+ shift = slot->height * RADIX_TREE_MAP_SHIFT;
do {
shift -= RADIX_TREE_MAP_SHIFT;
@@ -1509,10 +1508,7 @@ bool __radix_tree_delete_node(struct radix_tree_root *root,
parent = node->parent;
if (parent) {
- unsigned int offset;
-
- offset = node->path >> RADIX_TREE_HEIGHT_SHIFT;
- parent->slots[offset] = NULL;
+ parent->slots[node->offset] = NULL;
parent->count--;
} else {
root_tag_clear_all(root);
--
2.8.0.rc3
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