samba - Mar 2019 - Enable XAT_OFFLINE extended attribute in Samba

My goal is to use the Offline file attribute of Windows when sharing 
with Samba:

https://docs.microsoft.com/en-us/dotnet/api/system.io.fileattributes?redirectedfrom=MSDN&view=netframework-4.7.2

It works when I share ZFS filesystem using the native ZFS CIFS sharing, 
but it fails when I share the same ZFS with Samba, that is the Offline 
files are not showed in Windows Client


Il 3/4/2019 8:06 PM, Jeremy Allison via samba ha
scritto:
> On Mon, Mar 04, 2019 at 06:39:21PM +0000, Rowland Penny wrote:
>> On Mon, 4 Mar 2019 10:25:59 -0800
>> Jeremy Allison via samba <samba at lists.samba.org> wrote:
>>
>>> On Mon, Mar 04, 2019 at 04:48:56PM +0100, Andrea Cucciarre' via
samba
>>> wrote:
>>>> Hello,
>>>>
>>>> Does Samba support XAT_OFFLINE and XAT_ONLINE extended
attribute?
>>>> I have enabled "ea support = yes" but it seems to
have no effect on
>>>> that.
>>> Googling for XAT_OFFLINE or XAT_ONLINE doesn't return anything.
>> Yeh, my Googlefu is better than somebody who works for Google ;-)
> Oh the shame, the shame :-). Having said that I am at
> a conference and really should be paying attention to the
> lectures :-).
>
>> It seems to be something to do with ZFS on illumos:
>>
>>
https://github.com/openzfs/openzfs/blob/master/usr/src/uts/common/fs/xattr.c
> Thnaks Rowland, I'll take a look !
>

On Tue, Mar 05, 2019 at 01:14:00PM +0100, Andrea Cucciarre'
wrote:
> My goal is to use the Offline file attribute of Windows when sharing with
> Samba:
> 
>
https://docs.microsoft.com/en-us/dotnet/api/system.io.fileattributes?redirectedfrom=MSDN&view=netframework-4.7.2
> 
> It works when I share ZFS filesystem using the native ZFS CIFS sharing, but
> it fails when I share the same ZFS with Samba, that is the Offline files
are
> not showed in Windows Client
Got it. Currently, Samba uses the dmapi API to
check if a file has been migrated to external
storage, and to cope with reads/writes against
it.

Look at the VFS module source3/modules/vfs_tsmsm.c
which, as decribed, is:

  Samba VFS module for handling offline files
  with Tivoli Storage Manager Space Management

You would need to create a similar VFS module
on ZFS to expose the FILE_ATTRIBUTE_OFFLINE
flag to the client. Mostly it'll be wrapping
the [f]get_dos_attributes() VFS calls.

A bit fiddly, but doable (especially by companies
used to Samba coding internals).

Jeremy.

Thanks for the suggestion Jeremy, we are going to build our own module

Andrea

Il 3/5/2019 8:28 PM, Jeremy Allison ha scritto:
> On Tue, Mar 05, 2019 at 01:14:00PM +0100, Andrea Cucciarre' wrote:
>> My goal is to use the Offline file attribute of Windows when sharing
with
>> Samba:
>>
>>
https://docs.microsoft.com/en-us/dotnet/api/system.io.fileattributes?redirectedfrom=MSDN&view=netframework-4.7.2
>>
>> It works when I share ZFS filesystem using the native ZFS CIFS sharing,
but
>> it fails when I share the same ZFS with Samba, that is the Offline
files are
>> not showed in Windows Client
> Got it. Currently, Samba uses the dmapi API to
> check if a file has been migrated to external
> storage, and to cope with reads/writes against
> it.
>
> Look at the VFS module source3/modules/vfs_tsmsm.c
> which, as decribed, is:
>
>    Samba VFS module for handling offline files
>    with Tivoli Storage Manager Space Management
>
> You would need to create a similar VFS module
> on ZFS to expose the FILE_ATTRIBUTE_OFFLINE
> flag to the client. Mostly it'll be wrapping
> the [f]get_dos_attributes() VFS calls.
>
> A bit fiddly, but doable (especially by companies
> used to Samba coding internals).
>
> Jeremy.

On Tue, 5 Mar 2019 11:28:25 -0800, Jeremy Allison via samba wrote:
> Got it. Currently, Samba uses the dmapi API to
> check if a file has been migrated to external
> storage, and to cope with reads/writes against
> it.
> 
> Look at the VFS module source3/modules/vfs_tsmsm.c
> which, as decribed, is:
> 
>   Samba VFS module for handling offline files
>   with Tivoli Storage Manager Space Management
> 
> You would need to create a similar VFS module
> on ZFS to expose the FILE_ATTRIBUTE_OFFLINE
> flag to the client. Mostly it'll be wrapping
> the [f]get_dos_attributes() VFS calls.
IIUC, DMAPI will never make it into mainline. It'd be good if we could
settle on a standard xattr or statx flag for offline files on Linux /
BSD, which could then be used by FSes offering some form of HSM.
Extending user.DOSATTRIB might be an option, but wouldn't be too
friendly to other potential external consumers.

Cheers, David