mm: speculative page references

[firefly-linux-kernel-4.4.55.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 2d3ec1ffc66e1621b3db99a4105fb92115804e82..4e182a9a14c05185043ded08a4d50137cd88a810 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -442,39 +442,43 @@ int filemap_write_and_wait_range(struct address_space *mapping,
 }
 
 /**
- * add_to_page_cache - add newly allocated pagecache pages
+ * add_to_page_cache_locked - add a locked page to the pagecache
  * @page:      page to add
  * @mapping:   the page's address_space
  * @offset:    page index
  * @gfp_mask:  page allocation mode
  *
- * This function is used to add newly allocated pagecache pages;
- * the page is new, so we can just run SetPageLocked() against it.
- * The other page state flags were set by rmqueue().
- *
+ * This function is used to add a page to the pagecache. It must be locked.
  * This function does not add the page to the LRU.  The caller must do that.
  */
-int add_to_page_cache(struct page *page, struct address_space *mapping,
+int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
                pgoff_t offset, gfp_t gfp_mask)
 {
-       int error = mem_cgroup_cache_charge(page, current->mm,
+       int error;
+
+       VM_BUG_ON(!PageLocked(page));
+
+       error = mem_cgroup_cache_charge(page, current->mm,
                                        gfp_mask & ~__GFP_HIGHMEM);
        if (error)
                goto out;
 
        error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
        if (error == 0) {
+               page_cache_get(page);
+               page->mapping = mapping;
+               page->index = offset;
+
                write_lock_irq(&mapping->tree_lock);
                error = radix_tree_insert(&mapping->page_tree, offset, page);
-               if (!error) {
-                       page_cache_get(page);
-                       SetPageLocked(page);
-                       page->mapping = mapping;
-                       page->index = offset;
+               if (likely(!error)) {
                        mapping->nrpages++;
                        __inc_zone_page_state(page, NR_FILE_PAGES);
-               } else
+               } else {
+                       page->mapping = NULL;
                        mem_cgroup_uncharge_cache_page(page);
+                       page_cache_release(page);
+               }
 
                write_unlock_irq(&mapping->tree_lock);
                radix_tree_preload_end();
@@ -483,7 +487,7 @@ int add_to_page_cache(struct page *page, struct address_space *mapping,
 out:
        return error;
 }
-EXPORT_SYMBOL(add_to_page_cache);
+EXPORT_SYMBOL(add_to_page_cache_locked);
 
 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
                                pgoff_t offset, gfp_t gfp_mask)