From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id D3A11A941 for ; Tue, 5 Apr 2022 09:28:42 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id C60D61DC4F for ; Tue, 5 Apr 2022 09:28:42 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 2E5211DC45 for ; Tue, 5 Apr 2022 09:28:42 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id F090041CC7 for ; Tue, 5 Apr 2022 09:28:41 +0200 (CEST) Message-ID: <0b5a5b19-df4c-0289-4b13-8443f7f7635d@proxmox.com> Date: Tue, 5 Apr 2022 09:28:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Content-Language: en-US To: Proxmox VE development discussion , =?UTF-8?Q?Fabian_Gr=c3=bcnbichler?= References: <20220401152424.3811621-1-a.lauterer@proxmox.com> <20220401152424.3811621-2-a.lauterer@proxmox.com> <1649084728.7liqfd2nmz.astroid@nora.none> From: Aaron Lauterer In-Reply-To: <1649084728.7liqfd2nmz.astroid@nora.none> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.344 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.631 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record T_SCC_BODY_TEXT_LINE -0.01 - URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [rbdplugin.pm] Subject: Re: [pve-devel] [RFC qemu-server] clone disk: fix #3970 catch same source and destination X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Apr 2022 07:28:42 -0000 On 4/4/22 17:26, Fabian Grünbichler wrote: > On April 1, 2022 5:24 pm, Aaron Lauterer wrote: >> In rare situations, it could happen that the source and target path is >> the same. For example, if the disk image is to be copied from one RBD >> storage to another one on different Ceph clusters but the pools have the >> same name. >> >> In this situation, the clone operation will clone it to the same image and >> one will end up with an empty destination volume. >> >> This patch does not solve the underlying issue, but is a first step to >> avoid potential data loss, for example when the 'delete source' option >> is enabled as well. >> >> We also need to delete the newly created image right away because the >> regular cleanup gets confused and tries to remove the source image. This >> will fail and we have an orphaned image which cannot be removed easily >> because the same underlying root cause (same path) will falsely trigger >> the "Drive::is_volume_in_use" check. > > isn't this technically - just like for the container case - a problem in > general, not just for cloning a disk? I haven't tested this in practice, > but since you already have the reproducing setup ;) > > e.g., given the following: > - storage A, krbd, cluster A, pool foo > - storage B, krbd, cluster B, pool foo > - VM 123, with scsi0: A:vm-123-disk-0 and no volumes on B > - qm set 123 -scsi1: B:1 > > next free slot on B is 'vm-123-disk-0', which will be allocated. mapping > will skip the map part, since the RBD path already exists (provided > scsi0's volume is already activated). the returned path will point to > the mapped blockdev corresponding to A:vm-123-disk-0, not B:.. > > guest writes to scsi1, likely corrupting whatever is on scsi0, since > most things that tend to get put on guest disks are not > multi-writer-safe (or something along the way notices it?) > > if the above is the case, it might actually be prudent to just put the > check from your other patch into RBDPlugin.pm 's alloc method (and > clone and rename?) since we'd want to block any allocations on affected > systems? Tested it and yep... unfortunately the wrong disk is attached. I am going to implement the check in the RBDPlugin.pm.