From c12e51b07b3ac4c188fd91a82f96840fdb9cca6f Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 20 May 2016 17:03:10 -0700 Subject: [PATCH] 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 Reviewed-by: Ross Zwisler Cc: Konstantin Khlebnikov Cc: Kirill Shutemov Cc: Jan Kara Cc: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/radix-tree.h | 2 +- lib/radix-tree.c | 30 ++++++++++++++++-------------- 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; -- 2.20.1