Re: Xattr issues with overlayfs

[hujianyang <hujianyang@huawei.com>]

On 2014/11/25 22:41, Miklos Szeredi wrote:
> 
> No, I don't think this makes any sense.  Maintenance can be done by
> unmounting the overlay and doing modification directly on the upper
> layer.  After this is done (adding/removing opaque flag, adding
> removing whiteouts, etc) the overlay can be mounted again and the
> modifications will be applied.

Yes, we can remove overlayfs_xattr directly on upper files.

> 
> I don't think online modification of the internal attributes of the
> overlay makes much sense.
> 
> Except maybe, maybe a privileged undelete, but even that one is
> tricky: the whiteout was either from deletion of the lower layer or
> the upper layer file, the later not being undeleteable.  But the two
> cases are currently indistinguishable, so the undelete would always
> recover the lower layer file, which is probably not what the user
> wants and might cause more harm than good.
>

Agree.

Thanks for your explanation. Now I know "trusted.overlay.opaque" can
be set in userspace, but this xattr is set on files in upper filesystem,
not directly on files in overlayfs.


Thanks~!

Hu