LU-3321 obdclass: Add a preallocated percpu cl_env

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

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index 0a4b9a9..18098dc 100644 (file)
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -118,49 +118,62 @@ static void ll_invalidatepage(struct page *vmpage, unsigned long offset)
 #endif
 static int ll_releasepage(struct page *vmpage, RELEASEPAGE_ARG_TYPE gfp_mask)
 {
-        struct cl_env_nest nest;
-        struct lu_env     *env;
-        struct cl_object  *obj;
-        struct cl_page    *page;
-        struct address_space *mapping;
-        int result;
+       struct lu_env           *env;
+       void                    *cookie;
+       struct cl_object        *obj;
+       struct cl_page          *page;
+       struct address_space    *mapping;
+       int result = 0;
+
+       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 caller, 1 for cl_page and 1 for page cache */
+       if (page_count(vmpage) > 3)
+               return 0;
+
+       page = cl_vmpage_page(vmpage, obj);
+       if (page == NULL)
+               return 1;
+
+       cookie = cl_env_reenter();
+       env = cl_env_percpu_get();
+       LASSERT(!IS_ERR(env));
+
+       if (!cl_page_in_use(page)) {
+               result = 1;
+               cl_page_delete(env, page);
+       }
 
-        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 (!cl_page_in_use(page)) {
-                        result = 1;
-                        cl_page_delete(env, page);
-                }
-                cl_page_put(env, page);
-        }
-        cl_env_nested_put(&nest, env);
-        return result;
+       /* To use percpu env array, the call path can not be rescheduled;
+        * otherwise percpu array will be messed if ll_releaspage() called
+        * again on the same CPU.
+        *
+        * If this page holds the last refc of cl_object, the following
+        * call path may cause reschedule:
+        *   cl_page_put -> cl_page_free -> cl_object_put ->
+        *     lu_object_put -> lu_object_free -> lov_delete_raid0 ->
+        *     cl_locks_prune.
+        *
+        * However, the kernel can't get rid of this inode until all pages have
+        * been cleaned up. Now that we hold page lock here, it's pretty safe
+        * that we won't get into object delete path.
+        */
+       LASSERT(cl_object_refc(obj) > 1);
+       cl_page_put(env, page);
+
+       cl_env_percpu_put(env);
+       cl_env_reexit(cookie);
+       return result;
 }
 
 static int ll_set_page_dirty(struct page *vmpage)