mm: use lockless radix-tree probe

[linux-2.6-block.git] / mm / readahead.c

diff --git a/mm/readahead.c b/mm/readahead.c
index fc52f9f1b80cb08695c2379ed8faf5d761021293..c5c8981469e7078e9d107b95d574edbdff5b1c82 100644 (file)
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -149,20 +149,19 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
        /*
         * Preallocate as many pages as we will need.
         */
-       read_lock_irq(&mapping->tree_lock);
        for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
                pgoff_t page_offset = offset + page_idx;
 
                if (page_offset > end_index)
                        break;
 
+               rcu_read_lock();
                page = radix_tree_lookup(&mapping->page_tree, page_offset);
+               rcu_read_unlock();
                if (page)
                        continue;
 
-               read_unlock_irq(&mapping->tree_lock);
                page = page_cache_alloc_cold(mapping);
-               read_lock_irq(&mapping->tree_lock);
                if (!page)
                        break;
                page->index = page_offset;
@@ -171,7 +170,6 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
                        SetPageReadahead(page);
                ret++;
        }
-       read_unlock_irq(&mapping->tree_lock);
 
        /*
         * Now start the IO.  We ignore I/O errors - if the page is not