From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: radix-tree: rename INDIRECT_PTR to INTERNAL_NODE
The name RADIX_TREE_INDIRECT_PTR doesn't really match the meaning.
RADIX_TREE_INTERNAL_NODE is a better name.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Cc: Kirill Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/radix-tree.h | 30 +++++++++++++-----------------
lib/radix-tree.c | 2 +-
2 files changed, 14 insertions(+), 18 deletions(-)
diff -puN include/linux/radix-tree.h~radix-tree-rename-indirect_ptr-to-internal_node include/linux/radix-tree.h
--- a/include/linux/radix-tree.h~radix-tree-rename-indirect_ptr-to-internal_node
+++ a/include/linux/radix-tree.h
@@ -29,20 +29,16 @@
#include <linux/rcupdate.h>
/*
- * An indirect pointer (root->rnode pointing to a radix_tree_node, rather
- * than a data item) is signalled by the low bit set in the root->rnode
- * pointer.
- *
- * In this case root->height is > 0, but the indirect pointer tests are
- * needed for RCU lookups (because root->height is unreliable). The only
- * time callers need worry about this is when doing a lookup_slot under
- * RCU.
- *
- * Indirect pointer in fact is also used to tag the last pointer of a node
- * when it is shrunk, before we rcu free the node. See shrink code for
- * details.
+ * Entries in the radix tree have the low bit set if they refer to a
+ * radix_tree_node. If the low bit is clear then the entry is user data.
+ *
+ * We also use the low bit to indicate that the slot will be freed in the
+ * next RCU idle period, and users need to re-walk the tree to find the
+ * new slot for the index that they were looking for. See the comment in
+ * radix_tree_shrink() for details.
*/
-#define RADIX_TREE_INDIRECT_PTR 1
+#define RADIX_TREE_INTERNAL_NODE 1
+
/*
* A common use of the radix tree is to store pointers to struct pages;
* but shmem/tmpfs needs also to store swap entries in the same tree:
@@ -63,7 +59,7 @@
static inline int radix_tree_is_indirect_ptr(void *ptr)
{
- return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR);
+ return (int)((unsigned long)ptr & RADIX_TREE_INTERNAL_NODE);
}
/*** radix-tree API starts here ***/
@@ -228,7 +224,7 @@ static inline void *radix_tree_deref_slo
*/
static inline int radix_tree_deref_retry(void *arg)
{
- return unlikely((unsigned long)arg & RADIX_TREE_INDIRECT_PTR);
+ return unlikely(radix_tree_is_indirect_ptr(arg));
}
/**
@@ -250,7 +246,7 @@ static inline int radix_tree_exceptional
static inline int radix_tree_exception(void *arg)
{
return unlikely((unsigned long)arg &
- (RADIX_TREE_INDIRECT_PTR | RADIX_TREE_EXCEPTIONAL_ENTRY));
+ (RADIX_TREE_INTERNAL_NODE | RADIX_TREE_EXCEPTIONAL_ENTRY));
}
/**
@@ -448,7 +444,7 @@ radix_tree_chunk_size(struct radix_tree_
static inline void *indirect_to_ptr(void *ptr)
{
- return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
+ return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
}
/**
diff -puN lib/radix-tree.c~radix-tree-rename-indirect_ptr-to-internal_node lib/radix-tree.c
--- a/lib/radix-tree.c~radix-tree-rename-indirect_ptr-to-internal_node
+++ a/lib/radix-tree.c
@@ -68,7 +68,7 @@ static DEFINE_PER_CPU(struct radix_tree_
static inline void *ptr_to_indirect(void *ptr)
{
- return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR);
+ return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
}
#define RADIX_TREE_RETRY ptr_to_indirect(NULL)
_
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