From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 271D8C4338F for ; Mon, 26 Jul 2021 15:42:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 155C960F59 for ; Mon, 26 Jul 2021 15:42:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235654AbhGZPB4 (ORCPT ); Mon, 26 Jul 2021 11:01:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:41148 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235666AbhGZPBv (ORCPT ); Mon, 26 Jul 2021 11:01:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C2A4760F42; Mon, 26 Jul 2021 15:42:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627314140; bh=iDqe+YqHANkXWXYqqQYcozsSGPuDUT7Mv1NOc64he0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zWASkK41P5hWRya5BMTaaNcEpGBG2ck2Em85kN18xbeuex50PBcb0HFiCkRaUMgjM 2zoj76rjqLSfriK+7R/RlqlV9oo4oGC376ruEoNoLTUM4Rs3VD1Zw6VijHLjHAUsw+ 6Chb3iCJ7RUri3LtAJLk6oyn3PcaiEAyOhEjxiIE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Sterba , Sudip Mukherjee Subject: [PATCH 4.4 47/47] btrfs: compression: dont try to compress if we dont have enough pages Date: Mon, 26 Jul 2021 17:39:05 +0200 Message-Id: <20210726153824.455518827@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210726153822.980271128@linuxfoundation.org> References: <20210726153822.980271128@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Sterba commit f2165627319ffd33a6217275e5690b1ab5c45763 upstream The early check if we should attempt compression does not take into account the number of input pages. It can happen that there's only one page, eg. a tail page after some ranges of the BTRFS_MAX_UNCOMPRESSED have been processed, or an isolated page that won't be converted to an inline extent. The single page would be compressed but a later check would drop it again because the result size must be at least one block shorter than the input. That can never work with just one page. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: David Sterba [sudip: adjust context] Signed-off-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -476,7 +476,7 @@ again: * inode has not been flagged as nocompress. This flag can * change at any time if we discover bad compression ratios. */ - if (inode_need_compress(inode)) { + if (nr_pages > 1 && inode_need_compress(inode)) { WARN_ON(pages); pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); if (!pages) {