1 files changed, 153 insertions, 24 deletions

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 92cdd9936e3..6f412ab4c24 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -28,7 +28,6 @@
 #include <linux/slab.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
-#include <linux/gfp.h>
 #include <linux/string.h>
 #include <linux/bitops.h>
 #include <linux/rcupdate.h>
@@ -50,7 +49,7 @@ struct radix_tree_node {
 	unsigned int	height;		/* Height from the bottom */
 	unsigned int	count;
 	struct rcu_head	rcu_head;
-	void		*slots[RADIX_TREE_MAP_SIZE];
+	void __rcu	*slots[RADIX_TREE_MAP_SIZE];
 	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
 };
 
@@ -175,14 +174,16 @@ static void radix_tree_node_rcu_free(struct rcu_head *head)
 {
 	struct radix_tree_node *node =
 			container_of(head, struct radix_tree_node, rcu_head);
+	int i;
 
 	/*
 	 * must only free zeroed nodes into the slab. radix_tree_shrink
 	 * can leave us with a non-NULL entry in the first slot, so clear
 	 * that here to make sure.
 	 */
-	tag_clear(node, 0, 0);
-	tag_clear(node, 1, 0);
+	for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
+		tag_clear(node, i, 0);
+
 	node->slots[0] = NULL;
 	node->count = 0;
 
@@ -364,7 +365,7 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root,
 	unsigned int height, shift;
 	struct radix_tree_node *node, **slot;
 
-	node = rcu_dereference(root->rnode);
+	node = rcu_dereference_raw(root->rnode);
 	if (node == NULL)
 		return NULL;
 
@@ -384,7 +385,7 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root,
 	do {
 		slot = (struct radix_tree_node **)
 			(node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
-		node = rcu_dereference(*slot);
+		node = rcu_dereference_raw(*slot);
 		if (node == NULL)
 			return NULL;
 
@@ -556,6 +557,10 @@ EXPORT_SYMBOL(radix_tree_tag_clear);
  *
  *  0: tag not present or not set
  *  1: tag set
+ *
+ * Note that the return value of this function may not be relied on, even if
+ * the RCU lock is held, unless tag modification and node deletion are excluded
+ * from concurrency.
  */
 int radix_tree_tag_get(struct radix_tree_root *root,
 			unsigned long index, unsigned int tag)
@@ -568,7 +573,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
 	if (!root_tag_get(root, tag))
 		return 0;
 
-	node = rcu_dereference(root->rnode);
+	node = rcu_dereference_raw(root->rnode);
 	if (node == NULL)
 		return 0;
 
@@ -596,13 +601,9 @@ int radix_tree_tag_get(struct radix_tree_root *root,
 		 */
 		if (!tag_get(node, tag, offset))
 			saw_unset_tag = 1;
-		if (height == 1) {
-			int ret = tag_get(node, tag, offset);
-
-			BUG_ON(ret && saw_unset_tag);
-			return !!ret;
-		}
-		node = rcu_dereference(node->slots[offset]);
+		if (height == 1)
+			return !!tag_get(node, tag, offset);
+		node = rcu_dereference_raw(node->slots[offset]);
 		shift -= RADIX_TREE_MAP_SHIFT;
 		height--;
 	}
@@ -610,6 +611,134 @@ 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 tags must be set from the leaf level only and propagated back up the
+ * path to the root. We must do this so that we resolve the full path before
+ * setting any tags on intermediate nodes. If we set tags as we descend, then
+ * we can get to the leaf node and find that the index that has the iftag
+ * set is outside the range we are scanning. This reults in dangling tags and
+ * can lead to problems with later tag operations (e.g. livelocks on lookups).
+ *
+ * The function returns number of leaves where the tag was set and sets
+ * *first_indexp to the first unscanned index.
+ * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
+ * be prepared to handle that.
+ */
+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;
+	struct radix_tree_path path[height];
+	struct radix_tree_path *pathp = path;
+	struct radix_tree_node *slot;
+	unsigned int shift;
+	unsigned long tagged = 0;
+	unsigned long index = *first_indexp;
+
+	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);
+
+	/*
+	 * we fill the path from (root->height - 2) to 0, leaving the index at
+	 * (root->height - 1) as a terminator. Zero the node in the terminator
+	 * so that we can use this to end walk loops back up the path.
+	 */
+	path[height - 1].node = NULL;
+
+	for (;;) {
+		int offset;
+
+		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+		if (!slot->slots[offset])
+			goto next;
+		if (!tag_get(slot, iftag, offset))
+			goto next;
+		if (height > 1) {
+			/* Go down one level */
+			height--;
+			shift -= RADIX_TREE_MAP_SHIFT;
+			path[height - 1].node = slot;
+			path[height - 1].offset = offset;
+			slot = slot->slots[offset];
+			continue;
+		}
+
+		/* tag the leaf */
+		tagged++;
+		tag_set(slot, settag, offset);
+
+		/* walk back up the path tagging interior nodes */
+		pathp = &path[0];
+		while (pathp->node) {
+			/* stop if we find a node with the tag already set */
+			if (tag_get(pathp->node, settag, pathp->offset))
+				break;
+			tag_set(pathp->node, settag, pathp->offset);
+			pathp++;
+		}
+
+next:
+		/* Go to next item at level determined by 'shift' */
+		index = ((index >> shift) + 1) << shift;
+		/* Overflow can happen when last_index is ~0UL... */
+		if (index > last_index || !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 = path[height - 1].node;
+			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
@@ -657,7 +786,7 @@ EXPORT_SYMBOL(radix_tree_next_hole);
  *
  *	Returns: the index of the hole if found, otherwise returns an index
  *	outside of the set specified (in which case 'index - return >= max_scan'
- *	will be true). In rare cases of wrap-around, LONG_MAX will be returned.
+ *	will be true). In rare cases of wrap-around, ULONG_MAX will be returned.
  *
  *	radix_tree_next_hole may be called under rcu_read_lock. However, like
  *	radix_tree_gang_lookup, this will not atomically search a snapshot of
@@ -675,7 +804,7 @@ unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
 		if (!radix_tree_lookup(root, index))
 			break;
 		index--;
-		if (index == LONG_MAX)
+		if (index == ULONG_MAX)
 			break;
 	}
 
@@ -711,7 +840,7 @@ __lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
 		}
 
 		shift -= RADIX_TREE_MAP_SHIFT;
-		slot = rcu_dereference(slot->slots[i]);
+		slot = rcu_dereference_raw(slot->slots[i]);
 		if (slot == NULL)
 			goto out;
 	}
@@ -758,7 +887,7 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
 	unsigned long cur_index = first_index;
 	unsigned int ret;
 
-	node = rcu_dereference(root->rnode);
+	node = rcu_dereference_raw(root->rnode);
 	if (!node)
 		return 0;
 
@@ -787,7 +916,7 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
 			slot = *(((void ***)results)[ret + i]);
 			if (!slot)
 				continue;
-			results[ret + nr_found] = rcu_dereference(slot);
+			results[ret + nr_found] = rcu_dereference_raw(slot);
 			nr_found++;
 		}
 		ret += nr_found;
@@ -826,7 +955,7 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
 	unsigned long cur_index = first_index;
 	unsigned int ret;
 
-	node = rcu_dereference(root->rnode);
+	node = rcu_dereference_raw(root->rnode);
 	if (!node)
 		return 0;
 
@@ -915,7 +1044,7 @@ __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
 			}
 		}
 		shift -= RADIX_TREE_MAP_SHIFT;
-		slot = rcu_dereference(slot->slots[i]);
+		slot = rcu_dereference_raw(slot->slots[i]);
 		if (slot == NULL)
 			break;
 	}
@@ -951,7 +1080,7 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
 	if (!root_tag_get(root, tag))
 		return 0;
 
-	node = rcu_dereference(root->rnode);
+	node = rcu_dereference_raw(root->rnode);
 	if (!node)
 		return 0;
 
@@ -980,7 +1109,7 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
 			slot = *(((void ***)results)[ret + i]);
 			if (!slot)
 				continue;
-			results[ret + nr_found] = rcu_dereference(slot);
+			results[ret + nr_found] = rcu_dereference_raw(slot);
 			nr_found++;
 		}
 		ret += nr_found;
@@ -1020,7 +1149,7 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
 	if (!root_tag_get(root, tag))
 		return 0;
 
-	node = rcu_dereference(root->rnode);
+	node = rcu_dereference_raw(root->rnode);
 	if (!node)
 		return 0;