RE: [PATCH 1/2] xattr support for ext2fs

[LastAvengers]

> ext4 on Linux 4.5 already uses 7 for EXT4_XATTR_INDEX_SYSTEM
> but lists it in neither ext4_xattr_handler_map nor
> ext4_xattr_handlers. I think that means the index does not map
> to any prefix visible to user mode, not even to
> #define XATTR_SYSTEM_PREFIX "system.". Instead, ext4 uses
> { EXT4_XATTR_INDEX_SYSTEM, "data" } internally for inline data.
> http://lxr.free-electrons.com/ident?v=4.5;i=ext4_xattr_handler_map
>
> So if you use 7 then I think these xattrs will not be accessible
> from current Linux. And I think ext4 developers would not be
> happy to change ext4 to let them through if they intended
> EXT4_XATTR_INDEX_SYSTEM for ext4 internal use.

Thanks for your reminding, although the index 7 is not uesd in ext2
on Linux 4.5, I think it should keep consistent.

> (b) Store as { EXT4_ATTR_INDEX_USER = 1, "gnu.translator" }.
> On Linux, applications would see "user.gnu.translator".

This is a compromise way, but a bit strange.

> (c) Ask the ext4 developers to reserve a new index for "gnu.",
> and store as { EXT_ATTR_INDEX_GNU, "translator" }.

The hurd doesn't have ext4 support now, actually we should patch Linux's ext2.

I am not sure which way is better, try to discuss about this in #hurd.