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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 9BEFCC04AA7 for ; Mon, 13 May 2019 16:31:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 68D7B208CA for ; Mon, 13 May 2019 16:31:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729231AbfEMQbR (ORCPT ); Mon, 13 May 2019 12:31:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:35662 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727774AbfEMQbR (ORCPT ); Mon, 13 May 2019 12:31:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id ABB9FAF6E; Mon, 13 May 2019 16:31:15 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id CB085DA851; Mon, 13 May 2019 18:32:16 +0200 (CEST) Date: Mon, 13 May 2019 18:32:16 +0200 From: David Sterba To: fdmanana@kernel.org Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH] Btrfs: prevent send failures and crashes due to concurrent relocation Message-ID: <20190513163216.GF3138@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, fdmanana@kernel.org, linux-btrfs@vger.kernel.org References: <20190422154409.16323-1-fdmanana@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190422154409.16323-1-fdmanana@kernel.org> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Apr 22, 2019 at 04:44:09PM +0100, fdmanana@kernel.org wrote: > From: Filipe Manana > --- a/fs/btrfs/send.c > +++ b/fs/btrfs/send.c > @@ -6869,9 +6869,23 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) > if (ret) > goto out; > > + mutex_lock(&fs_info->balance_mutex); > + if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) { > + mutex_unlock(&fs_info->balance_mutex); > + btrfs_warn_rl(fs_info, > + "Can not run send because a balance operation is in progress"); > + ret = -EAGAIN; > + goto out; > + } > + fs_info->send_in_progress++; > + mutex_unlock(&fs_info->balance_mutex); This would be better in a helper that hides that the balance mutex from send. eg. if (!btrfs_send_can_start(fs_info) return -EAGAIN; > + > current->journal_info = BTRFS_SEND_TRANS_STUB; > ret = send_subvol(sctx); > current->journal_info = NULL; > + mutex_lock(&fs_info->balance_mutex); > + fs_info->send_in_progress--; > + mutex_unlock(&fs_info->balance_mutex); btrfs_send_end(); > if (ret < 0) > goto out; > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index db934ceae9c1..8145b62e3912 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -4203,6 +4203,14 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, > get_raid_name(meta_index), get_raid_name(data_index)); > } > > + if (fs_info->send_in_progress) { > + btrfs_warn_rl(fs_info, > +"Can not run balance while send operations are in progress (%d in progress)", > + fs_info->send_in_progress); > + ret = -EAGAIN; > + goto out; > + } Similar here. As the operation compatibility is done on the filesystem level, it would be better to hide all the logic in helpers, now that there's more than the per-subvolume send_in_progress.