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Message-ID: <20071122003211.GG114266761@sgi.com>
Date: Thu, 22 Nov 2007 11:32:11 +1100
From: David Chinner <dgc@....com>
To: xfs-oss <xfs@....sgi.com>
Cc: lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/9]: introduce radix_tree_gang_lookup_range
Introduce radix_tree_gang_lookup_range()
The inode clustering in XFS requires a gang lookup on the radix tree to
find all the inodes in the cluster. The gang lookup has to set the
maximum items to that of a fully populated cluster so we get all the
inodes in the cluster, but we only populate the radix tree sparsely (on
demand).
As a result, the gang lookup can search way, way past the index of end
of the cluster because it is looking for a fixed number of entries to
return.
We know we want to terminate the search at either a specific index or a
maximum number of items, so we need to add a "last_index" parameter to
the lookup.
Furthermore, the existing radix_tree_gang_lookup() can use this same
function if we define a RADIX_TREE_MAX_INDEX value so the search is not
limited by the last_index.
Signed-off-by: Dave Chinner <dgc@....com>
---
include/linux/radix-tree.h | 7 ++++-
lib/radix-tree.c | 55 ++++++++++++++++++++++++++++++++++++---------
2 files changed, 51 insertions(+), 11 deletions(-)
Index: 2.6.x-xfs-new/include/linux/radix-tree.h
===================================================================
--- 2.6.x-xfs-new.orig/include/linux/radix-tree.h 2007-11-22 10:25:23.834502553 +1100
+++ 2.6.x-xfs-new/include/linux/radix-tree.h 2007-11-22 10:31:46.689597763 +1100
@@ -98,10 +98,11 @@ do { \
* radix_tree_lookup
* radix_tree_tag_get
* radix_tree_gang_lookup
+ * radix_tree_gang_lookup_range
* radix_tree_gang_lookup_tag
* radix_tree_tagged
*
- * The first 4 functions are able to be called locklessly, using RCU. The
+ * The first 5 functions are able to be called locklessly, using RCU. The
* caller must ensure calls to these functions are made within rcu_read_lock()
* regions. Other readers (lock-free or otherwise) and modifications may be
* running concurrently.
@@ -155,6 +156,10 @@ void *radix_tree_delete(struct radix_tre
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items);
+unsigned int
+radix_tree_gang_lookup_range(struct radix_tree_root *root, void **results,
+ unsigned long first_index, unsigned long last_index,
+ unsigned int max_items);
int radix_tree_preload(gfp_t gfp_mask);
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *root,
Index: 2.6.x-xfs-new/lib/radix-tree.c
===================================================================
--- 2.6.x-xfs-new.orig/lib/radix-tree.c 2007-11-22 10:31:24.564425190 +1100
+++ 2.6.x-xfs-new/lib/radix-tree.c 2007-11-22 10:31:46.693597252 +1100
@@ -62,6 +62,8 @@ struct radix_tree_path {
#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
+#define RADIX_TREE_MAX_KEY ~0UL
+
static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
/*
@@ -599,7 +601,8 @@ EXPORT_SYMBOL(radix_tree_tag_get);
static unsigned int
__lookup(struct radix_tree_node *slot, void **results, unsigned long index,
- unsigned int max_items, unsigned long *next_index)
+ unsigned long last_index, unsigned int max_items,
+ unsigned long *next_index)
{
unsigned int nr_found = 0;
unsigned int shift, height;
@@ -640,6 +643,8 @@ __lookup(struct radix_tree_node *slot, v
if (nr_found == max_items)
goto out;
}
+ if (index > last_index)
+ goto out;
}
out:
*next_index = index;
@@ -647,27 +652,29 @@ out:
}
/**
- * radix_tree_gang_lookup - perform multiple lookup on a radix tree
+ * radix_tree_gang_lookup_range - perform multiple lookup on a radix tree
* @root: radix tree root
* @results: where the results of the lookup are placed
* @first_index: start the lookup from this key
+ * @last_index: end the lookup at this key
* @max_items: place up to this many items at *results
*
- * Performs an index-ascending scan of the tree for present items. Places
- * them at *@...ults and returns the number of items which were placed at
- * *@...ults.
+ * Performs an index-ascending scan of the tree for present items up to
+ * @last_index in the tree. Places them at *@...ults and returns the
+ * number of items which were placed at *@...ults.
*
* The implementation is naive.
*
- * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
+ * Like radix_tree_lookup, radix_tree_gang_lookup_range may be called under
* rcu_read_lock. In this case, rather than the returned results being
* an atomic snapshot of the tree at a single point in time, the semantics
* of an RCU protected gang lookup are as though multiple radix_tree_lookups
* have been issued in individual locks, and results stored in 'results'.
*/
unsigned int
-radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
- unsigned long first_index, unsigned int max_items)
+radix_tree_gang_lookup_range(struct radix_tree_root *root, void **results,
+ unsigned long first_index, unsigned long last_index,
+ unsigned int max_items)
{
unsigned long max_index;
struct radix_tree_node *node;
@@ -686,7 +693,7 @@ radix_tree_gang_lookup(struct radix_tree
return 1;
}
- max_index = radix_tree_maxindex(node->height);
+ max_index = min(last_index, radix_tree_maxindex(node->height));
ret = 0;
while (ret < max_items) {
@@ -695,7 +702,7 @@ radix_tree_gang_lookup(struct radix_tree
if (cur_index > max_index)
break;
- nr_found = __lookup(node, results + ret, cur_index,
+ nr_found = __lookup(node, results + ret, cur_index, max_index,
max_items - ret, &next_index);
ret += nr_found;
if (next_index == 0)
@@ -705,6 +712,34 @@ radix_tree_gang_lookup(struct radix_tree
return ret;
}
+EXPORT_SYMBOL(radix_tree_gang_lookup_range);
+
+/**
+ * radix_tree_gang_lookup - perform multiple lookup on a radix tree
+ * @root: radix tree root
+ * @results: where the results of the lookup are placed
+ * @first_index: start the lookup from this key
+ * @max_items: place up to this many items at *results
+ *
+ * Performs an index-ascending scan of the tree for present items. Places
+ * them at *@...ults and returns the number of items which were placed at
+ * *@...ults.
+ *
+ * The implementation is naive.
+ *
+ * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
+ * rcu_read_lock. In this case, rather than the returned results being
+ * an atomic snapshot of the tree at a single point in time, the semantics
+ * of an RCU protected gang lookup are as though multiple radix_tree_lookups
+ * have been issued in individual locks, and results stored in 'results'.
+ */
+unsigned int
+radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
+ unsigned long first_index, unsigned int max_items)
+{
+ return radix_tree_gang_lookup_range(root, results, first_index,
+ RADIX_TREE_MAX_KEY, max_items);
+}
EXPORT_SYMBOL(radix_tree_gang_lookup);
/*
-
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