On Fri, 11 Jun 2021 at 09:31, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> Taking a step back.
>
> The main problem this is trying to solve is losing persistent inode flags
> on copy-up.
>
> If this was just NOATIME and SYNC the solution would have been
> simple - copy up the flags along with other metadata we copy up.
>
> We wouldn't even need to limit ourselves to the 4 vfs inode flags
> in ovl_copyflags(). We could add the the copied up flags more
> fs specific flags that we know to be safe and rational to copy
> such as NOCOW, NODUMP and DIRSYNC.
>
> The secondary problem is that copying IMMUTABLE/APPEND
> to upper inode on copy up is not an option, so the solution is to
> store those properties in an xattr.
>
> I think we should split the solution to the primary and secondary
> problems and avoid an over-designed generic future extendable
> xflags xattr feature.
>
> So I am leaning towards a more focused solution for
> IMMUTABLE/APPEND in the form of either two boolean
> xattr overlay.{immutable,appendonly} or one single bytes
> xattr overlay.protected.
Makes sense.
Not sure how you'd make it single byte and user friendly at the same
time. I.e. how'd you represent +ia?. Otherwise I'm fine with either.
Thanks,
Miklos
