readahead: remove one unnecessary radix tree lookup
Wu Fengguang [Tue, 16 Jun 2009 22:31:21 +0000 (15:31 -0700)]
(hit_readahead_marker != 0) means the page at @offset is present, so we
can search for non-present page starting from @offset+1.

Reported-by: Xu Chenfeng <xcf@ustc.edu.cn>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/readahead.c

index bd0f0e8..5673115 100644 (file)
@@ -395,7 +395,7 @@ ondemand_readahead(struct address_space *mapping,
                pgoff_t start;
 
                rcu_read_lock();
-               start = radix_tree_next_hole(&mapping->page_tree, offset,max+1);
+               start = radix_tree_next_hole(&mapping->page_tree, offset+1,max);
                rcu_read_unlock();
 
                if (!start || start - offset > max)