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Subject[PATCH 31/33] readahead: debug radix tree new functions
Do some sanity checkings on the newly added radix tree code.

Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
mm/readahead.c | 24 ++++++++++++++++++++++++
1 files changed, 24 insertions(+)
--- linux-2.6.17-rc4-mm3.orig/mm/readahead.c
+++ linux-2.6.17-rc4-mm3/mm/readahead.c
@@ -63,6 +63,8 @@ enum ra_class {
RA_CLASS_COUNT
};

+#define DEBUG_READAHEAD_RADIXTREE
+
/* Read-ahead events to be accounted. */
enum ra_event {
RA_EVENT_CACHE_MISS, /* read cache misses */
@@ -1315,6 +1317,16 @@ static pgoff_t find_segtail(struct addre
cond_resched();
read_lock_irq(&mapping->tree_lock);
ra_index = radix_tree_scan_hole(&mapping->page_tree, index, max_scan);
+#ifdef DEBUG_READAHEAD_RADIXTREE
+ BUG_ON(!__find_page(mapping, index));
+ WARN_ON(ra_index < index);
+ if (ra_index != index && !__find_page(mapping, ra_index - 1))
+ printk(KERN_ERR "radix_tree_scan_hole(index=%lu ra_index=%lu "
+ "max_scan=%lu nrpages=%lu) fooled!\n",
+ index, ra_index, max_scan, mapping->nrpages);
+ if (ra_index != ~0UL && ra_index - index < max_scan)
+ WARN_ON(__find_page(mapping, ra_index));
+#endif
read_unlock_irq(&mapping->tree_lock);

if (ra_index <= index + max_scan)
@@ -1407,6 +1419,13 @@ static unsigned long query_page_cache_se
read_lock_irq(&mapping->tree_lock);
index = radix_tree_scan_hole_backward(&mapping->page_tree,
offset, ra_max);
+#ifdef DEBUG_READAHEAD_RADIXTREE
+ WARN_ON(index > offset);
+ if (index != offset)
+ WARN_ON(!__find_page(mapping, index + 1));
+ if (index && offset - index < ra_max)
+ WARN_ON(__find_page(mapping, index));
+#endif
read_unlock_irq(&mapping->tree_lock);

*remain = offset - index;
@@ -1442,6 +1461,11 @@ static unsigned long query_page_cache_se
struct radix_tree_node *node;
node = radix_tree_cache_lookup_parent(&mapping->page_tree,
&cache, offset - count, 1);
+#ifdef DEBUG_READAHEAD_RADIXTREE
+ if (node != radix_tree_lookup_parent(&mapping->page_tree,
+ offset - count, 1))
+ BUG();
+#endif
if (!node)
break;
}
--
-
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