fail_page_alloc: simplify debugfs initialization

Now cleanup_fault_attr_dentries() recursively removes a directory, So we
can simplify the error handling in the initialization code and no need
to hold dentry structs for each debugfs file.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -1370,21 +1370,12 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 
 #ifdef CONFIG_FAIL_PAGE_ALLOC
 
-static struct fail_page_alloc_attr {
+static struct {
 	struct fault_attr attr;
 
 	u32 ignore_gfp_highmem;
 	u32 ignore_gfp_wait;
 	u32 min_order;
-
-#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
-
-	struct dentry *ignore_gfp_highmem_file;
-	struct dentry *ignore_gfp_wait_file;
-	struct dentry *min_order_file;
-
-#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
-
 } fail_page_alloc = {
 	.attr = FAULT_ATTR_INITIALIZER,
 	.ignore_gfp_wait = 1,
@@ -1424,30 +1415,24 @@ static int __init fail_page_alloc_debugfs(void)
 				       "fail_page_alloc");
 	if (err)
 		return err;
+
 	dir = fail_page_alloc.attr.dir;
 
-	fail_page_alloc.ignore_gfp_wait_file =
-		debugfs_create_bool("ignore-gfp-wait", mode, dir,
-				      &fail_page_alloc.ignore_gfp_wait);
-
-	fail_page_alloc.ignore_gfp_highmem_file =
-		debugfs_create_bool("ignore-gfp-highmem", mode, dir,
-				      &fail_page_alloc.ignore_gfp_highmem);
-	fail_page_alloc.min_order_file =
-		debugfs_create_u32("min-order", mode, dir,
-				   &fail_page_alloc.min_order);
-
-	if (!fail_page_alloc.ignore_gfp_wait_file ||
-            !fail_page_alloc.ignore_gfp_highmem_file ||
-            !fail_page_alloc.min_order_file) {
-		err = -ENOMEM;
-		debugfs_remove(fail_page_alloc.ignore_gfp_wait_file);
-		debugfs_remove(fail_page_alloc.ignore_gfp_highmem_file);
-		debugfs_remove(fail_page_alloc.min_order_file);
-		cleanup_fault_attr_dentries(&fail_page_alloc.attr);
-	}
+	if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
+				&fail_page_alloc.ignore_gfp_wait))
+		goto fail;
+	if (!debugfs_create_bool("ignore-gfp-highmem", mode, dir,
+				&fail_page_alloc.ignore_gfp_highmem))
+		goto fail;
+	if (!debugfs_create_u32("min-order", mode, dir,
+				&fail_page_alloc.min_order))
+		goto fail;
+
+	return 0;
+fail:
+	cleanup_fault_attr_dentries(&fail_page_alloc.attr);
 
-	return err;
+	return -ENOMEM;
 }
 
 late_initcall(fail_page_alloc_debugfs);