diff options
| -rw-r--r-- | include/linux/radix-tree.h | 4 | ||||
| -rw-r--r-- | lib/radix-tree.c | 94 |
2 files changed, 98 insertions, 0 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 55ca73cf25e..a4b00e9cca9 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -192,6 +192,10 @@ unsigned int radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, unsigned long first_index, unsigned int max_items, unsigned int tag); +unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, + unsigned long *first_indexp, unsigned long last_index, + unsigned long nr_to_tag, + unsigned int fromtag, unsigned int totag); int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag); static inline void radix_tree_preload_end(void) diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 05da38bcc29..e907858498a 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -609,6 +609,100 @@ int radix_tree_tag_get(struct radix_tree_root *root, EXPORT_SYMBOL(radix_tree_tag_get); /** + * radix_tree_range_tag_if_tagged - for each item in given range set given + * tag if item has another tag set + * @root: radix tree root + * @first_indexp: pointer to a starting index of a range to scan + * @last_index: last index of a range to scan + * @nr_to_tag: maximum number items to tag + * @iftag: tag index to test + * @settag: tag index to set if tested tag is set + * + * This function scans range of radix tree from first_index to last_index + * (inclusive). For each item in the range if iftag is set, the function sets + * also settag. The function stops either after tagging nr_to_tag items or + * after reaching last_index. + * + * The function returns number of leaves where the tag was set and sets + * *first_indexp to the first unscanned index. + */ +unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, + unsigned long *first_indexp, unsigned long last_index, + unsigned long nr_to_tag, + unsigned int iftag, unsigned int settag) +{ + unsigned int height = root->height, shift; + unsigned long tagged = 0, index = *first_indexp; + struct radix_tree_node *open_slots[height], *slot; + + last_index = min(last_index, radix_tree_maxindex(height)); + if (index > last_index) + return 0; + if (!nr_to_tag) + return 0; + if (!root_tag_get(root, iftag)) { + *first_indexp = last_index + 1; + return 0; + } + if (height == 0) { + *first_indexp = last_index + 1; + root_tag_set(root, settag); + return 1; + } + + shift = (height - 1) * RADIX_TREE_MAP_SHIFT; + slot = radix_tree_indirect_to_ptr(root->rnode); + + for (;;) { + int offset; + + offset = (index >> shift) & RADIX_TREE_MAP_MASK; + if (!slot->slots[offset]) + goto next; + if (!tag_get(slot, iftag, offset)) + goto next; + tag_set(slot, settag, offset); + if (height == 1) { + tagged++; + goto next; + } + /* Go down one level */ + height--; + shift -= RADIX_TREE_MAP_SHIFT; + open_slots[height] = slot; + slot = slot->slots[offset]; + continue; +next: + /* Go to next item at level determined by 'shift' */ + index = ((index >> shift) + 1) << shift; + if (index > last_index) + break; + if (tagged >= nr_to_tag) + break; + while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) { + /* + * We've fully scanned this node. Go up. Because + * last_index is guaranteed to be in the tree, what + * we do below cannot wander astray. + */ + slot = open_slots[height]; + height++; + shift += RADIX_TREE_MAP_SHIFT; + } + } + /* + * The iftag must have been set somewhere because otherwise + * we would return immediated at the beginning of the function + */ + root_tag_set(root, settag); + *first_indexp = index; + + return tagged; +} +EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); + + +/** * radix_tree_next_hole - find the next hole (not-present entry) * @root: tree root * @index: index key |