Return-Path: Received: from mail.kernel.org ([198.145.29.99]:53436 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730783AbeLFOsQ (ORCPT ); Thu, 6 Dec 2018 09:48:16 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , Qu Wenruo , David Sterba , Ben Hutchings Subject: [PATCH 4.9 077/101] btrfs: tree-check: reduce stack consumption in check_dir_item Date: Thu, 6 Dec 2018 15:39:16 +0100 Message-Id: <20181206143016.555628642@linuxfoundation.org> In-Reply-To: <20181206143011.174892052@linuxfoundation.org> References: <20181206143011.174892052@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Sterba commit e2683fc9d219430f5b78889b50cde7f40efeba7b upstream. I've noticed that the updated item checker stack consumption increased dramatically in 542f5385e20cf97447 ("btrfs: tree-checker: Add checker for dir item") tree-checker.c:check_leaf +552 (176 -> 728) The array is 255 bytes long, dynamic allocation would slow down the sanity checks so it's more reasonable to keep it on-stack. Moving the variable to the scope of use reduces the stack usage again tree-checker.c:check_leaf -264 (728 -> 464) Reviewed-by: Josef Bacik Reviewed-by: Qu Wenruo Signed-off-by: David Sterba Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/tree-checker.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -212,7 +212,6 @@ static int check_dir_item(struct btrfs_r di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); while (cur < item_size) { - char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)]; u32 name_len; u32 data_len; u32 max_name_len; @@ -295,6 +294,8 @@ static int check_dir_item(struct btrfs_r */ if (key->type == BTRFS_DIR_ITEM_KEY || key->type == BTRFS_XATTR_ITEM_KEY) { + char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)]; + read_extent_buffer(leaf, namebuf, (unsigned long)(di + 1), name_len); name_hash = btrfs_name_hash(namebuf, name_len);