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authorMatthew Wilcox <willy@linux.intel.com>2016-05-21 03:03:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-21 03:58:30 +0300
commitc12e51b07b3ac4c188fd91a82f96840fdb9cca6f (patch)
tree13f432c3419297b6994905f9bb2eb9b934bc614d
parent0c7fa0a8418cbe0e8963fe36db9575d03b8589f7 (diff)
downloadlinux-c12e51b07b3ac4c188fd91a82f96840fdb9cca6f.tar.xz
radix-tree: replace node->height with node->shift
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>
-rw-r--r--include/linux/radix-tree.h2
-rw-r--r--lib/radix-tree.c30
2 files changed, 17 insertions, 15 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 2d2ad9d685a3..037458257e12 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -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)
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 int count;
union {
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index dd04b51e5fbb..648da9080418 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -223,10 +223,10 @@ static void dump_node(struct radix_tree_node *node,
{
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->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++) {
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];
}
+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)
{
- return radix_tree_maxindex(node->height);
+ return shift_maxindex(node->shift);
}
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))) {
node = indirect_to_ptr(node);
*maxindex = node_maxindex(node);
- return node->height * RADIX_TREE_MAP_SHIFT;
+ return node->shift + RADIX_TREE_MAP_SHIFT;
}
*maxindex = 0;
@@ -475,9 +480,9 @@ static int radix_tree_extend(struct radix_tree_root *root,
}
/* Increase the height. */
- newheight = root->height + 1;
+ newheight = root->height;
BUG_ON(newheight > BITS_PER_LONG);
- node->height = newheight;
+ node->shift = newheight * RADIX_TREE_MAP_SHIFT;
node->offset = 0;
node->count = 1;
node->parent = NULL;
@@ -490,7 +495,7 @@ static int radix_tree_extend(struct radix_tree_root *root,
node->slots[0] = slot;
node = ptr_to_indirect(node);
rcu_assign_pointer(root->rnode, node);
- root->height = newheight;
+ root->height = ++newheight;
} while (height > root->height);
out:
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;
unsigned long maxindex;
- unsigned int height, shift, offset;
+ unsigned int shift, offset;
unsigned long max = index | ((1UL << order) - 1);
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 */
while (shift > order) {
+ shift -= RADIX_TREE_MAP_SHIFT;
if (slot == NULL) {
/* Have to add a child node. */
slot = radix_tree_node_alloc(root);
if (!slot)
return -ENOMEM;
- slot->height = height;
+ slot->shift = shift;
slot->offset = offset;
slot->parent = node;
if (node) {
@@ -560,8 +564,6 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
break;
/* Go a level down */
- height--;
- shift -= RADIX_TREE_MAP_SHIFT;
node = indirect_to_ptr(slot);
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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 long i;
- shift = slot->height * RADIX_TREE_MAP_SHIFT;
+ shift = slot->shift + RADIX_TREE_MAP_SHIFT;
do {
shift -= RADIX_TREE_MAP_SHIFT;