diff options
Diffstat (limited to 'lib/radix-tree.c')
| -rw-r--r-- | lib/radix-tree.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 86516f5588e3..e7964296fd50 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -73,11 +73,24 @@ static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; static struct kmem_cache *radix_tree_node_cachep; /* + * The radix tree is variable-height, so an insert operation not only has + * to build the branch to its corresponding item, it also has to build the + * branch to existing items if the size has to be increased (by + * radix_tree_extend). + * + * The worst case is a zero height tree with just a single item at index 0, + * and then inserting an item at index ULONG_MAX. This requires 2 new branches + * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. + * Hence: + */ +#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) + +/* * Per-cpu pool of preloaded nodes */ struct radix_tree_preload { int nr; - struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; + struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE]; }; static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; @@ -673,6 +686,9 @@ void **radix_tree_next_chunk(struct radix_tree_root *root, * during iterating; it can be zero only at the beginning. * And we cannot overflow iter->next_index in a single step, * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG. + * + * This condition also used by radix_tree_next_slot() to stop + * contiguous iterating, and forbid swithing to the next chunk. */ index = iter->next_index; if (!index && iter->index) |