[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v2 00/20] block/export: Allow exporting BDSs via FUSE
From: |
Daniel P . Berrangé |
Subject: |
Re: [PATCH v2 00/20] block/export: Allow exporting BDSs via FUSE |
Date: |
Tue, 22 Sep 2020 16:58:38 +0100 |
User-agent: |
Mutt/1.14.6 (2020-07-11) |
On Tue, Sep 22, 2020 at 12:49:12PM +0200, Max Reitz wrote:
> Based-on: <20200907182011.521007-1-kwolf@redhat.com>
> (“block/export: Add infrastructure and QAPI for block exports”)
>
> (Though its patch 16 needs a s/= \&blk_exp_nbd/= drv/ on top.)
>
> v1: https://lists.nongnu.org/archive/html/qemu-block/2019-12/msg00451.html
>
> Branch: https://github.com/XanClic/qemu.git fuse-exports-v2
> Branch: https://git.xanclic.moe/XanClic/qemu.git fuse-exports-v2
>
>
> Hi,
>
> Ever since I found out that you can mount FUSE filesystems on regular
> files (not just directories), I had the idea of adding FUSE block
> exports to qemu where you can export block nodes as raw images. The
> best thing is that you’d be able to mount an image on itself, so
> whatever format it may be in, qemu lets it appear as a raw image (and
> you can then use regular tools like dd on it).
>
> The performance is quite bad so far, but we can always try to improve it
> if the need arises. For now I consider it mostly a cute feature to get
> easy access to the raw contents of image files in any format (without
> requiring root rights).
Aside from the iotests, so you forsee any particular use cases
where this feature is desirable / important ?
Looking at it from a security POV, I'm not thrilled about the
idea of granting QEMU permission to use the mount syscall for
seccomp or SELinux. IOW, I expect this feature won't be something
we want to expose in QEMU guests managed by libvirt, which would
limit how widely it can be used.
QEMU can export NBD. Would it make sense to do this as an NBD
client ? There's already https://libguestfs.org/nbdfuse.1.html
but IIUC that exposes it as a file within a dir. Presumably
it is not too hard to make it support exposing it directly as
a file too.
I wonder how performance compares between your native FUSE
impl in QEMU vs NBD FUSE ?
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
- [PATCH v2 11/20] iotests: Derive image names from $TEST_IMG, (continued)
- [PATCH v2 11/20] iotests: Derive image names from $TEST_IMG, Max Reitz, 2020/09/22
- [PATCH v2 12/20] iotests/091: Use _cleanup_qemu instad of "wait", Max Reitz, 2020/09/22
- [PATCH v2 13/20] iotests: Restrict some Python tests to file, Max Reitz, 2020/09/22
- [PATCH v2 14/20] iotests: Let _make_test_img guess $TEST_IMG_FILE, Max Reitz, 2020/09/22
- [PATCH v2 16/20] storage-daemon: Call bdrv_close_all() on exit, Max Reitz, 2020/09/22
- [PATCH v2 15/20] iotests/287: Clean up subshell test image, Max Reitz, 2020/09/22
- [PATCH v2 17/20] iotests: Give access to the qemu-storage-daemon, Max Reitz, 2020/09/22
- [PATCH v2 18/20] iotests: Allow testing FUSE exports, Max Reitz, 2020/09/22
- [PATCH v2 19/20] iotests: Enable fuse for many tests, Max Reitz, 2020/09/22
- [PATCH v2 20/20] iotests/308: Add test for FUSE exports, Max Reitz, 2020/09/22
- Re: [PATCH v2 00/20] block/export: Allow exporting BDSs via FUSE,
Daniel P . Berrangé <=