From 0c7fa0a8418cbe0e8963fe36db9575d03b8589f7 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 20 May 2016 17:03:07 -0700 Subject: [PATCH] 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 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 | 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 8558d52e1c7b..2d2ad9d685a3 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 75944e42e4a0..dd04b51e5fbb 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 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; @@ -1508,10 +1507,7 @@ 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); -- 2.25.1