Add an internal tag to identify special entries that are accounted in node->special in addition to node->count.
With this in place, the next patch can restore refault detection in single-page files. It will also move the shadow count from the upper bits of count to the new special counter, and then shrink count to a char as well; the growth of struct radix_tree_node is temporary. Signed-off-by: Johannes Weiner <[email protected]> --- include/linux/radix-tree.h | 10 ++++++---- lib/radix-tree.c | 14 ++++++++++---- 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 756b2909467e..2e1c9added23 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -68,7 +68,8 @@ enum radix_tree_tags { /* Freely allocatable radix tree user tags */ RADIX_TREE_NR_USER_TAGS = 3, /* Radix tree internal tags */ - RADIX_TREE_NR_TAGS = RADIX_TREE_NR_USER_TAGS, + RADIX_TREE_TAG_SPECIAL = RADIX_TREE_NR_USER_TAGS, + RADIX_TREE_NR_TAGS, }; #ifndef RADIX_TREE_MAP_SHIFT @@ -90,9 +91,10 @@ enum radix_tree_tags { #define RADIX_TREE_COUNT_MASK ((1UL << RADIX_TREE_COUNT_SHIFT) - 1) struct radix_tree_node { - unsigned char shift; /* Bits remaining in each slot */ - unsigned char offset; /* Slot offset in parent */ - unsigned int count; + unsigned char shift; /* Bits remaining in each slot */ + unsigned char offset; /* Slot offset in parent */ + unsigned int count; /* Total entry count */ + unsigned char special; /* Special entry count */ union { struct { /* Used when ascending tree */ diff --git a/lib/radix-tree.c b/lib/radix-tree.c index bb6ddfb60557..e58cff1d97ed 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -220,10 +220,10 @@ static void dump_node(struct radix_tree_node *node, unsigned long index) { unsigned long i; - pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d parent %p\n", + pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d special %d parent %p\n", node, node->offset, node->tags[0][0], node->tags[1][0], node->tags[2][0], - node->shift, node->count, node->parent); + node->shift, node->count, node->special, node->parent); for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { unsigned long first = index | (i << node->shift); @@ -522,9 +522,15 @@ static int radix_tree_extend(struct radix_tree_root *root, node->offset = 0; node->count = 1; node->parent = NULL; - if (radix_tree_is_internal_node(slot)) - entry_to_node(slot)->parent = node; node->slots[0] = slot; + /* Extending an existing node or root->rnode? */ + if (radix_tree_is_internal_node(slot)) { + entry_to_node(slot)->parent = node; + } else { + /* Moving a special root->rnode to a node */ + if (root_tag_get(root, RADIX_TREE_TAG_SPECIAL)) + node->special = 1; + } slot = node_to_entry(node); rcu_assign_pointer(root->rnode, slot); shift += RADIX_TREE_MAP_SHIFT; -- 2.10.0
