Some deficiencies with the Samba VFS that I think need to e rectified ...

[Richard Sharpe]

On Tue, Dec 10, 2013 at 3:09 PM, Jeremy Allison <jra at samba.org> wrote:
> On Tue, Dec 10, 2013 at 02:33:52PM -0800, Richard Sharpe wrote:
>> On Tue, Dec 10, 2013 at 1:46 PM, Volker Lendecke
>> <Volker.Lendecke at sernet.de> wrote:
>> > On Tue, Dec 10, 2013 at 10:39:21AM -0800, Richard Sharpe wrote:
>> >> I agree pretty much with these needs. However, one of the things that
>> >> is motivating my grumbling is that we are making too many changes to
>> >> Samba, which makes life difficult for us down the road.
>> >
>> > Can you share more of your requirements and the details of
>> > what you are doing? In the other mail today you wrote about
>> > findings with regards to previous versions. Do your VFS
>> > change requests have anything to do with that? I'm asking
>> > because maybe someone on this list has good ideas how to
>> > meet your requirements. If you need to develop in private,
>> > then fine too.
>>
>> Well, it does and it doesn't.
>>
>> 1. We want to introduce fake directories for a couple of reasons. One
>> of those was to support things like ~snapshot, although that is going
>> to go away. A nice way to do this is to bury it in our VFS module but
>> it is quite hard. If we had and FSP associated with each dptr (or
>> whatever) then we could hang an FSP extension off it so we could keep
>> some state.
>
> The fix here is to replace the return from opendir/fdopendir
> from an OS-defined opaque DIR *, to an opaque SMB_DIR *, which
> can contain whatever the VFS requires. readdir(), seekdir(),
> telldir(), rewinndir() then need to be updated.
>
> This only formalizes what VFS modules like CEPH already
> do - for example:
>
> static DIR *cephwrap_fdopendir(struct vfs_handle_struct *handle,
>                                struct files_struct *fsp,
>                                const char *mask,
>                                uint32 attributes)
> {...
>         ret = ceph_opendir(handle->data, fsp->fsp_name->base_name, &result);
>         if (ret < 0) {
>                 result = NULL;
>                 errno = -ret; /* We return result which is NULL in this case */
>         }
>
>         DEBUG(10, ("[CEPH] fdopendir(...) = %d\n", ret));
>         return (DIR *) result;
> }
>
> So it's easy to keep state here, and other VFS modules
> already do it.

Sigh, since I was involved with that way back I should have remembered this ...

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)