[Samba] Documentation/Feature Clarification Request: Server Side Copy and VFS_FRUIT

[Andrew Walker]

On Wed, May 21, 2025 at 1:47 AM Ralph Boehme via samba <
samba at lists.samba.org> wrote:

> There are two styles of SSC:
> - the "normal" protocol style called copy-chunk, where the copy is
> requested in IO ranges by the client and performed server-side
> - the Apple way enabled by fruit:copyfile where the client requests the
> *whole* file to be copied in one request to be performed by the server
>
>
Ralph, I looked at MacOS client code recently and saw they're using a
compounded CREATE /  FSCTL_SRV_REQUEST_RESUME_KEY / CLOSE to determine
whether copy-chunk is supported on the SMB server during mount_smbfs
operations. Samba is failing with the compounded request with
STATUS_INTERNAL_ERROR because of going async in a compounded request. This
causes MacOS client to flag samba as not supporting server-side copy. A
fairly trivial change to set the defer time for
FSCTL_SRV_REQUEST_RESUME_KEY to zero results in MacOS properly identifying
support for copy-chunk and server-side copy to work. I'll make a merge
request later today.

- Andrew