mm: readahead scan lockless

radix_tree_next_hole() is implemented as a series of radix_tree_lookup()s. So it can be called locklessly, under rcu_read_lock(). Signed-off-by: Nick Piggin <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Reviewed-by: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
oleg-nesterov · Jul 26, 2008 · 30002ed · 30002ed
1 parent 652ea69
commit 30002ed
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/mm/readahead.c b/mm/readahead.c
@@ -382,9 +382,9 @@ ondemand_readahead(struct address_space *mapping,
 	if (hit_readahead_marker) {
 		pgoff_t start;
 
-		read_lock_irq(&mapping->tree_lock);
-		start = radix_tree_next_hole(&mapping->page_tree, offset, max+1);
-		read_unlock_irq(&mapping->tree_lock);
+		rcu_read_lock();
+		start = radix_tree_next_hole(&mapping->page_tree, offset,max+1);
+		rcu_read_unlock();
 
 		if (!start || start - offset > max)
 			return 0;