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([2a00:1370:812d:8deb:5c9c:cef9:590c:9452]) by smtp.gmail.com with ESMTPSA id t184sm13770lff.250.2021.09.01.10.40.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Sep 2021 10:40:51 -0700 (PDT) Subject: Re: Backup failing with "failed to clone extents" error To: Darrell Enns , fdmanana@gmail.com Cc: linux-btrfs References: From: Andrei Borzenkov Message-ID: Date: Wed, 1 Sep 2021 20:40:50 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 01.09.2021 20:16, Darrell Enns wrote: > I'm not sure how this would happen. These subvolumes were all created > with snapper (snap-sync just calls snapper). They were not received > from another filesystem, and I don't think they've ever been RW > (unless snapper for some reason does that?). > > Received_uuid is actually the same on *all* my snapshots, and it's the > same as the original "@root" subvolume as well. Is each one supposed > to have a unique received_uuid? Received_uuid is expected to be managed by "btrfs receive" only. It can be seen as "dataset identifier" - identical received_uuid means both subvolumes have identical content (identical from btrfs point of view, having the same files is not enough). It is valid to cascade send/receive so if A was sent to B and then B was sent to C, both B and C will have identical received_uuid equal to A uuid because the have the same content (all three subvolumes are expected to be read-only and so cannot be changed). Unfortunately there are a lot of possibilities to completely break this workflow. Your case is one example. > Is this somehow because my "@root" > subvolume was originally created by receiving from another btrfs? > Most likely. Did you simply make received subvolume read-write?