ACK: [SRU][M][PATCH 0/2] disable shiftfs

[Tim Gardner]

On 10/5/23 3:49 AM, Andrea Righi wrote:
> BugLink: https://bugs.launchpad.net/bugs/2038522
> 
> [Impact]
> 
> Now that all the filesystems that we officially support have the
> idmapped mounts capability we can get rid of shiftfs.
> 
> The benefit of this change is that we don't have to maintain an
> out-of-tree filesystem anymore and we can completely rely on upstream
> features.
> 
> [Test case]
> 
> lxd was the main user of shiftfs to compensate the lack of idmapped
> mounts capability of certain filesystems, such as zfs / ceph, but now in
> mantic also these two filesystem received the support for idmapped
> mounts (support for zfs was introduced in 2.2.0~rc3 and for ceph see
> LP: #2032959).
> 
> The lxd team provided a positive feedback, testing the latest 6.5 Mantic
> kernel across all the supported filesystems with shiftfs disabled.
> 
> [Fix]
> 
> Disable shiftfs in the kernel config and enable unsafe idmapped mounts
> by default (default=on).
> 
> [Regression potential]
> 
> The support for idmapped mounts for the ceph filesystem is not applied
> upstream yet, so we may experience regressions in systems that are using
> this filesystem. Moreover disabling shiftfs may trigger failures in our
> testing (testing shiftfs capabilities will obviously fail) or break any
> other user-space application that is relying on shiftfs (however to our
> knowledge lxd was the only "official" user or shiftfs; for this reason
> we may also see potential regressions in lxd).
> 
> 
Acked-by: Tim Gardner <tim.gardner at canonical.com>
-- 
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Tim Gardner
Canonical, Inc