X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2Fradix-tree.c;h=a2f9da59c1970cfab2a55c94f43da8843551ef05;hb=2355e4290336fcda4b4a799448f745155a000226;hp=7ea2e033d7153ad23de9dc02c0c0786abc1e11e2;hpb=020abf03cd659388f94cb328e1e1df0656e0d7ff;p=firefly-linux-kernel-4.4.55.git

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