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Fri, 20 Aug 2021 00:56:55 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzprV+jrLA+4uPS+ZyqJ7gv+ptJT251D4sNMgjs68jKEdIyvF0qGglclvSBRZW2dHXFU79a9A== X-Received: by 2002:a05:600c:1d11:: with SMTP id l17mr2481883wms.58.1629446215111; Fri, 20 Aug 2021 00:56:55 -0700 (PDT) Received: from dresden.str.redhat.com ([2a02:908:1e46:160:b272:8083:d5:bc7d]) by smtp.gmail.com with ESMTPSA id e14sm320714wrr.6.2021.08.20.00.56.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Aug 2021 00:56:54 -0700 (PDT) Subject: Re: [qemu-web PATCH] Add a blog post about FUSE block exports To: Stefan Hajnoczi References: <20210819102501.69638-1-hreitz@redhat.com> From: Hanna Reitz Message-ID: <46a68d5c-cfc1-e521-8c6b-90eb74c85ede@redhat.com> Date: Fri, 20 Aug 2021 09:56:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=216.205.24.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -60 X-Spam_score: -6.1 X-Spam_bar: ------ X-Spam_report: (-6.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-2.591, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 19.08.21 18:23, Stefan Hajnoczi wrote: > On Thu, Aug 19, 2021 at 12:25:01PM +0200, Hanna Reitz wrote: >> This post explains when FUSE block exports are useful, how they work, >> and that it is fun to export an image file on its own path so it looks >> like your image file (in whatever format it was) is a raw image now. >> >> Signed-off-by: Hanna Reitz >> --- >> You can also find this patch here: >> https://gitlab.com/hreitz/qemu-web fuse-blkexport-v1 >> >> My first patch to qemu-web, so I hope I am not doing anything overly >> stupid here (adding SVGs with extremely long lines comes to mind)... >> --- >> _posts/2021-08-18-fuse-blkexport.md | 488 ++++++++++++++++++++++ >> screenshots/2021-08-18-block-graph-a.svg | 2 + >> screenshots/2021-08-18-block-graph-b.svg | 2 + >> screenshots/2021-08-18-block-graph-c.svg | 2 + >> screenshots/2021-08-18-block-graph-d.svg | 2 + >> screenshots/2021-08-18-block-graph-e.svg | 2 + >> screenshots/2021-08-18-root-directory.svg | 2 + >> screenshots/2021-08-18-root-file.svg | 2 + >> 8 files changed, 502 insertions(+) >> create mode 100644 _posts/2021-08-18-fuse-blkexport.md >> create mode 100644 screenshots/2021-08-18-block-graph-a.svg >> create mode 100644 screenshots/2021-08-18-block-graph-b.svg >> create mode 100644 screenshots/2021-08-18-block-graph-c.svg >> create mode 100644 screenshots/2021-08-18-block-graph-d.svg >> create mode 100644 screenshots/2021-08-18-block-graph-e.svg >> create mode 100644 screenshots/2021-08-18-root-directory.svg >> create mode 100644 screenshots/2021-08-18-root-file.svg > Great! Two ideas: > > It would be nice to include a shoutout to libguestfs and mention that > libguestfs avoids exposing the host kernel's file systems and partion > code to untrusted disk images. If you don't mount the image then the > FUSE export has similar security properties. Oh, right!  Absolutely. Though now I do wonder why one would actually want to use QEMU’s FUSE exports then... Looks like the performance isn’t as bad as I claimed (for me around 1.5G/s for reading/writing from/to a raw image on tmpfs), so perhaps that’s one point.  Another is probably that FUSE exports are better suited when you actually want access to the whole image.  I guess. > This is a long blog post. One idea is to show a quickstart > qemu-storage-daemon FUSE export command-line in the beginning before > explaining all the details. That way people who just want to see what > this is about can get an idea without learning all the background first. Sounds good, will do.  Thanks! Hanna