From patchwork Thu Aug 20 09:18:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 265843 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 88189C433E1 for ; Thu, 20 Aug 2020 09:35:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6275B2173E for ; Thu, 20 Aug 2020 09:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597916144; bh=+iu7Ap2ptMWD3TekcfG5/6x2zhfygQLXp2wM0sPiqD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=yDQMrPVgqG0o2aXF4tsOD7+yNuQNSpFkzfrOYPCpzaaIPjXbbnYw1SLfhO3GlZwiX uIlyHdSfc+VqbENYP2G+xpvKAuX1TuGn3syPvasfRQ5zvhAR7iogeVTvywlp/+TXLj QA6Ty8cXr8MGSJCc5dquapr9zyyMs7vz8aMXUyBU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727976AbgHTJff (ORCPT ); Thu, 20 Aug 2020 05:35:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:49232 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728341AbgHTJfe (ORCPT ); Thu, 20 Aug 2020 05:35:34 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A58CC20724; Thu, 20 Aug 2020 09:35:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597916134; bh=+iu7Ap2ptMWD3TekcfG5/6x2zhfygQLXp2wM0sPiqD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=azgzkq7uKDJeoJ17HhBb1nKks/CMXaoBFnr5DSR17TGN1vhNoOmjjA9D8ZptK2x+C u8CegL+AuQDZDnVnjfrlg0M2ZHx+2Z3QlYchqpMqpNlV/qeInQzndKFNb1YvHsNSL9 LjTxUr5qxqbv4E2Me/0OtMa722xH4HeSA93gcEIA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qu Wenruo , David Sterba Subject: [PATCH 5.7 022/204] btrfs: relocation: review the call sites which can be interrupted by signal Date: Thu, 20 Aug 2020 11:18:39 +0200 Message-Id: <20200820091607.369022615@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820091606.194320503@linuxfoundation.org> References: <20200820091606.194320503@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Qu Wenruo commit 44d354abf33e92a5e73b965c84caf5a5d5e58a0b upstream. Since most metadata reservation calls can return -EINTR when get interrupted by fatal signal, we need to review the all the metadata reservation call sites. In relocation code, the metadata reservation happens in the following sites: - btrfs_block_rsv_refill() in merge_reloc_root() merge_reloc_root() is a pretty critical section, we don't want to be interrupted by signal, so change the flush status to BTRFS_RESERVE_FLUSH_LIMIT, so it won't get interrupted by signal. Since such change can be ENPSPC-prone, also shrink the amount of metadata to reserve least amount avoid deadly ENOSPC there. - btrfs_block_rsv_refill() in reserve_metadata_space() It calls with BTRFS_RESERVE_FLUSH_LIMIT, which won't get interrupted by signal. - btrfs_block_rsv_refill() in prepare_to_relocate() - btrfs_block_rsv_add() in prepare_to_relocate() - btrfs_block_rsv_refill() in relocate_block_group() - btrfs_delalloc_reserve_metadata() in relocate_file_extent_cluster() - btrfs_start_transaction() in relocate_block_group() - btrfs_start_transaction() in create_reloc_inode() Can be interrupted by fatal signal and we can handle it easily. For these call sites, just catch the -EINTR value in btrfs_balance() and count them as canceled. CC: stable@vger.kernel.org # 5.4+ Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/relocation.c | 12 ++++++++++-- fs/btrfs/volumes.c | 17 ++++++++++++++++- 2 files changed, 26 insertions(+), 3 deletions(-) --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2402,12 +2402,20 @@ static noinline_for_stack int merge_relo btrfs_unlock_up_safe(path, 0); } - min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; + /* + * In merge_reloc_root(), we modify the upper level pointer to swap the + * tree blocks between reloc tree and subvolume tree. Thus for tree + * block COW, we COW at most from level 1 to root level for each tree. + * + * Thus the needed metadata size is at most root_level * nodesize, + * and * 2 since we have two trees to COW. + */ + min_reserved = fs_info->nodesize * btrfs_root_level(root_item) * 2; memset(&next_key, 0, sizeof(next_key)); while (1) { ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved, - BTRFS_RESERVE_FLUSH_ALL); + BTRFS_RESERVE_FLUSH_LIMIT); if (ret) { err = ret; goto out; --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4154,7 +4154,22 @@ int btrfs_balance(struct btrfs_fs_info * mutex_lock(&fs_info->balance_mutex); if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) btrfs_info(fs_info, "balance: paused"); - else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req)) + /* + * Balance can be canceled by: + * + * - Regular cancel request + * Then ret == -ECANCELED and balance_cancel_req > 0 + * + * - Fatal signal to "btrfs" process + * Either the signal caught by wait_reserve_ticket() and callers + * got -EINTR, or caught by btrfs_should_cancel_balance() and + * got -ECANCELED. + * Either way, in this case balance_cancel_req = 0, and + * ret == -EINTR or ret == -ECANCELED. + * + * So here we only check the return value to catch canceled balance. + */ + else if (ret == -ECANCELED || ret == -EINTR) btrfs_info(fs_info, "balance: canceled"); else btrfs_info(fs_info, "balance: ended with status: %d", ret);