On Tue, Mar 9, 2021 at 5:27 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> Commit a888db310195 ("ovl: fix regression with re-formatted lower
> squashfs") attempted to fix a regression with existing setups that
> use a practice that we are trying to discourage.
>
> The discourage part was described this way in the commit message:
> "To avoid the reported regression while still allowing the new features
> with single lower squashfs, do not allow decoding origin with lower null
> uuid unless user opted-in to one of the new features that require
> following the lower inode of non-dir upper (index, xino, metacopy)."
>
> The three mentioned features are disabled by default in Kconfig, so
> it was assumed that if they are enabled, the user opted-in for them.
> Apparently, distros started to configure CONFIG_OVERLAY_FS_XINO_AUTO=y
> some time ago, so users upgrading their kernels can still be affected
> by said regression even though they never opted-in for any new feature.
>
> To fix this, treat "xino=on" as "user opted-in", but not "xino=auto".
> Since we are changing the behavior of "xino=auto" to no longer follow
> to lower origin with null uuid, take this one step further and disable
> xino in that corner case. To be consistent, disable xino also in cases
> of lower fs without file handle support and upper fs without xattr
> support.
>
> Update documentation w.r.t the new "xino=auto" behavior and fix the out
> dated bits of documentation regarding "xino" and regarding offline
> modifications to lower layers.
>
> Link: https://lore.kernel.org/linux-unionfs/b36a429d7c563730c28d763d4d57a6fc30508a4f.1615216996.git.kevin@xxxxxxxxxxxxxxx/
> Fixes: a888db310195 ("ovl: fix regression with re-formatted lower squashfs")
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>
> Miklos,
>
> What do you think about this?
Applied. I removed the Fixes: tag for fear of too eager backport
bots, the said commit is mentioned in the header, so no information is
lost.
Thanks,
Miklos
