LU-1320 llite: fix a race between readpage and releasepage

[fs/lustre-release.git] / lustre / llite / rw26.c

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index 3f8d583..4577bc8 100644 (file)
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -139,14 +139,51 @@ static void ll_invalidatepage(struct page *page, unsigned long offset)
 #else
 #define RELEASEPAGE_ARG_TYPE gfp_t
 #endif
-static int ll_releasepage(struct page *page, RELEASEPAGE_ARG_TYPE gfp_mask)
+static int ll_releasepage(struct page *vmpage, RELEASEPAGE_ARG_TYPE gfp_mask)
 {
-        void *cookie;
+        struct cl_env_nest nest;
+        struct lu_env     *env;
+        struct cl_object  *obj;
+        struct cl_page    *page;
+        struct address_space *mapping;
+        int result;
 
-        cookie = cl_env_reenter();
-        ll_invalidatepage(page, 0);
-        cl_env_reexit(cookie);
-        return 1;
+        LASSERT(PageLocked(vmpage));
+        if (PageWriteback(vmpage) || PageDirty(vmpage))
+                return 0;
+
+        mapping = vmpage->mapping;
+        if (mapping == NULL)
+                return 1;
+
+        obj = ll_i2info(mapping->host)->lli_clob;
+        if (obj == NULL)
+                return 1;
+
+        /* 1 for page allocator, 1 for cl_page and 1 for page cache */
+        if (page_count(vmpage) > 3)
+                return 0;
+
+        /* TODO: determine what gfp should be used by @gfp_mask. */
+        env = cl_env_nested_get(&nest);
+        if (IS_ERR(env))
+                /* If we can't allocate an env we won't call cl_page_put()
+                 * later on which further means it's impossible to drop
+                 * page refcount by cl_page, so ask kernel to not free
+                 * this page. */
+                return 0;
+
+        page = cl_vmpage_page(vmpage, obj);
+        result = page == NULL;
+        if (page != NULL) {
+                if (cfs_atomic_read(&page->cp_ref) == 1) {
+                        result = 1;
+                        cl_page_delete(env, page);
+                }
+                cl_page_put(env, page);
+        }
+        cl_env_nested_put(&nest, env);
+        return result;
 }
 
 static int ll_set_page_dirty(struct page *vmpage)