[PATCH 30/32] readahead: debug radix tree new functions

Wu Fengguang
2006-05-27T15:51:52Z

[-- Attachment #1: readahead-debug-radix-tree.patch --]
[-- Type: text/plain, Size: 1653 bytes --]

Do some sanity checkings on the newly added radix tree code.

Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---

mm/readahead.c | 19 +++++++++++++++++++
1 files changed, 19 insertions(+)

--- linux-2.6.17-rc4-mm3.orig/mm/readahead.c
+++ linux-2.6.17-rc4-mm3/mm/readahead.c
@@ -70,6 +70,8 @@ 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 */
@@ -1294,6 +1296,16 @@ 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(!__probe_page(mapping, index));
+ WARN_ON(ra_index < index);
+ if (ra_index != index && !__probe_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(__probe_page(mapping, ra_index));
+#endif
read_unlock_irq(&mapping->tree_lock);

if (ra_index <= index + max_scan)
@@ -1377,6 +1389,13 @@ static unsigned long query_page_cache_se
read_lock_irq(&mapping->tree_lock);
index = radix_tree_scan_hole_backward(&mapping->page_tree,
offset - 1, ra_max);
+#ifdef DEBUG_READAHEAD_RADIXTREE
+ WARN_ON(index > offset - 1);
+ if (index != offset - 1)
+ WARN_ON(!__probe_page(mapping, index + 1));
+ if (index && offset - 1 - index < ra_max)
+ WARN_ON(__probe_page(mapping, index));
+#endif

*remain = offset - index;

--