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-rw-r--r--lib/radix-tree.c121
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