From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Linux Memory Management <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH 2.6.13] lockless pagecache 4/7
Date: Fri, 02 Sep 2005 16:30:58 +1000 [thread overview]
Message-ID: <4317F1A2.8030605@yahoo.com.au> (raw)
In-Reply-To: <4317F17F.5050306@yahoo.com.au>
[-- Attachment #1: Type: text/plain, Size: 33 bytes --]
4/7
--
SUSE Labs, Novell Inc.
[-- Attachment #2: radix-tree-lookup_slot.patch --]
[-- Type: text/plain, Size: 2627 bytes --]
From: Hans Reiser <reiser@namesys.com>
Reiser4 uses radix trees to solve a trouble reiser4_readdir has serving nfs
requests.
Unfortunately, radix tree api lacks an operation suitable for modifying
existing entry. This patch adds radix_tree_lookup_slot which returns pointer
to found item within the tree. That location can be then updated.
Index: linux-2.6/include/linux/radix-tree.h
===================================================================
--- linux-2.6.orig/include/linux/radix-tree.h
+++ linux-2.6/include/linux/radix-tree.h
@@ -46,6 +46,7 @@ do { \
int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
+void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
Index: linux-2.6/lib/radix-tree.c
===================================================================
--- linux-2.6.orig/lib/radix-tree.c
+++ linux-2.6/lib/radix-tree.c
@@ -276,14 +276,8 @@ int radix_tree_insert(struct radix_tree_
}
EXPORT_SYMBOL(radix_tree_insert);
-/**
- * radix_tree_lookup - perform lookup operation on a radix tree
- * @root: radix tree root
- * @index: index key
- *
- * Lookup the item at the position @index in the radix tree @root.
- */
-void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+static inline void **__lookup_slot(struct radix_tree_root *root,
+ unsigned long index)
{
unsigned int height, shift;
struct radix_tree_node **slot;
@@ -306,7 +300,36 @@ void *radix_tree_lookup(struct radix_tre
height--;
}
- return *slot;
+ return (void **)slot;
+}
+
+/**
+ * radix_tree_lookup_slot - lookup a slot in a radix tree
+ * @root: radix tree root
+ * @index: index key
+ *
+ * Lookup the slot corresponding to the position @index in the radix tree
+ * @root. This is useful for update-if-exists operations.
+ */
+void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
+{
+ return __lookup_slot(root, index);
+}
+EXPORT_SYMBOL(radix_tree_lookup_slot);
+
+/**
+ * radix_tree_lookup - perform lookup operation on a radix tree
+ * @root: radix tree root
+ * @index: index key
+ *
+ * Lookup the item at the position @index in the radix tree @root.
+ */
+void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+{
+ void **slot;
+
+ slot = __lookup_slot(root, index);
+ return slot != NULL ? *slot : NULL;
}
EXPORT_SYMBOL(radix_tree_lookup);
next prev parent reply other threads:[~2005-09-02 6:30 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-02 6:25 New lockless pagecache Nick Piggin
2005-09-02 6:28 ` [PATCH 2.6.13] lockless pagecache 1/7 Nick Piggin
2005-09-02 6:29 ` [PATCH 2.6.13] lockless pagecache 2/7 Nick Piggin
2005-09-02 6:30 ` [PATCH 2.6.13] lockless pagecache 3/7 Nick Piggin
2005-09-02 6:30 ` Nick Piggin [this message]
2005-09-02 6:31 ` [PATCH 2.6.13] lockless pagecache 5/7 Nick Piggin
2005-09-02 6:32 ` [PATCH 2.6.13] lockless pagecache 6/7 Nick Piggin
2005-09-02 6:32 ` [PATCH 2.6.13] lockless pagecache 7/7 Nick Piggin
2005-09-09 13:00 ` Christoph Lameter
2005-09-09 15:23 ` Nick Piggin
2005-09-09 5:36 ` [PATCH 2.6.13] lockless pagecache 5/7 Christoph Lameter
2005-09-09 6:22 ` Nick Piggin
2005-09-02 13:08 ` [PATCH 2.6.13] lockless pagecache 2/7 Alan Cox
2005-09-02 20:41 ` Andi Kleen
2005-09-02 21:12 ` David S. Miller
2005-09-02 21:43 ` Nick Piggin
2005-09-02 21:22 ` Nick Piggin
2005-09-02 21:31 ` David S. Miller
2005-09-02 21:47 ` Nick Piggin
2005-09-02 21:57 ` David S. Miller
2005-09-02 23:57 ` Alan Cox
2005-09-03 1:40 ` Nick Piggin
2005-09-03 17:31 ` Alan Cox
2005-09-04 1:01 ` Nick Piggin
2005-09-04 8:20 ` Alan Cox
2005-09-06 1:03 ` Nick Piggin
2005-09-02 18:26 ` Christoph Lameter
2005-09-02 21:26 ` Nick Piggin
2005-09-03 1:33 ` Christoph Lameter
2005-09-02 6:45 ` New lockless pagecache Nick Piggin
2005-09-15 19:50 ` Alok kataria
2005-09-16 3:12 ` Nick Piggin
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