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=-20.2 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, USER_AGENT_GIT autolearn=ham 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 7CA7EC07E9D for ; Mon, 19 Jul 2021 16:10:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 646BB6141A for ; Mon, 19 Jul 2021 16:10:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346579AbhGSP30 (ORCPT ); Mon, 19 Jul 2021 11:29:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:40236 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348198AbhGSPYi (ORCPT ); Mon, 19 Jul 2021 11:24:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9A42F613FE; Mon, 19 Jul 2021 16:03:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626710581; bh=xxsBuwLGjTFe88cs4CLFygPNJoQvsK31NzBoSy1dToU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O/SOKQ8/gSgkGQ7sfyBuhjM7Y8QyuEUh7bp7nOaf/oVk/GqklwxO6XScoashq4A8K PNyYwdJCjeMMJ/6erBZ/gMCliWQaToU6C790cTgSzwgGv07gqIUaXBR3DiMf1NsyVw e/RmGbDr3URMNj6D0cr9T0vCtUsKLCDEla8xAc88= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johannes Thumshirn , David Sterba Subject: [PATCH 5.13 032/351] btrfs: dont block if we cant acquire the reclaim lock Date: Mon, 19 Jul 2021 16:49:38 +0200 Message-Id: <20210719144945.592297152@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144944.537151528@linuxfoundation.org> References: <20210719144944.537151528@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: stable@vger.kernel.org From: Johannes Thumshirn commit 9cc0b837e14ae913581ec1ea6e979a738f71b0fd upstream. If we can't acquire the reclaim_bgs_lock on block group reclaim, we block until it is free. This can potentially stall for a long time. While reclaim of block groups is necessary for a good user experience on a zoned file system, there still is no need to block as it is best effort only, just like when we're deleting unused block groups. CC: stable@vger.kernel.org # 5.13 Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/block-group.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1499,7 +1499,15 @@ void btrfs_reclaim_bgs_work(struct work_ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) return; - mutex_lock(&fs_info->reclaim_bgs_lock); + /* + * Long running balances can keep us blocked here for eternity, so + * simply skip reclaim if we're unable to get the mutex. + */ + if (!mutex_trylock(&fs_info->reclaim_bgs_lock)) { + btrfs_exclop_finish(fs_info); + return; + } + spin_lock(&fs_info->unused_bgs_lock); while (!list_empty(&fs_info->reclaim_bgs)) { bg = list_first_entry(&fs_info->reclaim_bgs,