diff options
Diffstat (limited to 'lib/radix-tree.c')
| -rw-r--r-- | lib/radix-tree.c | 121 |
1 files changed, 111 insertions, 10 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 7ea2e033d715..a2f9da59c197 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -823,8 +823,8 @@ unsigned long radix_tree_prev_hole(struct radix_tree_root *root, EXPORT_SYMBOL(radix_tree_prev_hole); static unsigned int -__lookup(struct radix_tree_node *slot, void ***results, unsigned long index, - unsigned int max_items, unsigned long *next_index) +__lookup(struct radix_tree_node *slot, void ***results, unsigned long *indices, + unsigned long index, unsigned int max_items, unsigned long *next_index) { unsigned int nr_found = 0; unsigned int shift, height; @@ -857,12 +857,16 @@ __lookup(struct radix_tree_node *slot, void ***results, unsigned long index, /* Bottom level: grab some items */ for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { - index++; if (slot->slots[i]) { - results[nr_found++] = &(slot->slots[i]); - if (nr_found == max_items) + results[nr_found] = &(slot->slots[i]); + if (indices) + indices[nr_found] = index; + if (++nr_found == max_items) { + index++; goto out; + } } + index++; } out: *next_index = index; @@ -918,8 +922,8 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results, if (cur_index > max_index) break; - slots_found = __lookup(node, (void ***)results + ret, cur_index, - max_items - ret, &next_index); + slots_found = __lookup(node, (void ***)results + ret, NULL, + cur_index, max_items - ret, &next_index); nr_found = 0; for (i = 0; i < slots_found; i++) { struct radix_tree_node *slot; @@ -944,6 +948,7 @@ EXPORT_SYMBOL(radix_tree_gang_lookup); * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree * @root: radix tree root * @results: where the results of the lookup are placed + * @indices: where their indices should be placed (but usually NULL) * @first_index: start the lookup from this key * @max_items: place up to this many items at *results * @@ -958,7 +963,8 @@ EXPORT_SYMBOL(radix_tree_gang_lookup); * protection, radix_tree_deref_slot may fail requiring a retry. */ unsigned int -radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, +radix_tree_gang_lookup_slot(struct radix_tree_root *root, + void ***results, unsigned long *indices, unsigned long first_index, unsigned int max_items) { unsigned long max_index; @@ -974,6 +980,8 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, if (first_index > 0) return 0; results[0] = (void **)&root->rnode; + if (indices) + indices[0] = 0; return 1; } node = indirect_to_ptr(node); @@ -987,8 +995,9 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, if (cur_index > max_index) break; - slots_found = __lookup(node, results + ret, cur_index, - max_items - ret, &next_index); + slots_found = __lookup(node, results + ret, + indices ? indices + ret : NULL, + cur_index, max_items - ret, &next_index); ret += slots_found; if (next_index == 0) break; @@ -1194,6 +1203,98 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, } EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); +#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP) +#include <linux/sched.h> /* for cond_resched() */ + +/* + * This linear search is at present only useful to shmem_unuse_inode(). + */ +static unsigned long __locate(struct radix_tree_node *slot, void *item, + unsigned long index, unsigned long *found_index) +{ + unsigned int shift, height; + unsigned long i; + + height = slot->height; + shift = (height-1) * RADIX_TREE_MAP_SHIFT; + + for ( ; height > 1; height--) { + i = (index >> shift) & RADIX_TREE_MAP_MASK; + for (;;) { + if (slot->slots[i] != NULL) + break; + index &= ~((1UL << shift) - 1); + index += 1UL << shift; + if (index == 0) + goto out; /* 32-bit wraparound */ + i++; + if (i == RADIX_TREE_MAP_SIZE) + goto out; + } + + shift -= RADIX_TREE_MAP_SHIFT; + slot = rcu_dereference_raw(slot->slots[i]); + if (slot == NULL) + goto out; + } + + /* Bottom level: check items */ + for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { + if (slot->slots[i] == item) { + *found_index = index + i; + index = 0; + goto out; + } + } + index += RADIX_TREE_MAP_SIZE; +out: + return index; +} + +/** + * radix_tree_locate_item - search through radix tree for item + * @root: radix tree root + * @item: item to be found + * + * Returns index where item was found, or -1 if not found. + * Caller must hold no lock (since this time-consuming function needs + * to be preemptible), and must check afterwards if item is still there. + */ +unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) +{ + struct radix_tree_node *node; + unsigned long max_index; + unsigned long cur_index = 0; + unsigned long found_index = -1; + + do { + rcu_read_lock(); + node = rcu_dereference_raw(root->rnode); + if (!radix_tree_is_indirect_ptr(node)) { + rcu_read_unlock(); + if (node == item) + found_index = 0; + break; + } + + node = indirect_to_ptr(node); + max_index = radix_tree_maxindex(node->height); + if (cur_index > max_index) + break; + + cur_index = __locate(node, item, cur_index, &found_index); + rcu_read_unlock(); + cond_resched(); + } while (cur_index != 0 && cur_index <= max_index); + + return found_index; +} +#else +unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) +{ + return -1; +} +#endif /* CONFIG_SHMEM && CONFIG_SWAP */ /** * radix_tree_shrink - shrink height of a radix tree to minimal |