On Thu, Nov 21, 2013 at 11:45:41AM +0100, David Disseldorp wrote: > It depends on how the SMB server interprets the copy-chunk wire request. > On Btrfs, Samba can translate the request into a BTRFS_IOC_CLONE_RANGE > ioctl, in which case the same CoW semantics are observed[1]. See: > > https://wiki.samba.org/index.php/Server-Side_Copy#Btrfs_Enhanced_Server-Side_Copy_Offload > > By default however, Samba (and Windows) will perform the copy on the > server-side using regular reads/writes. A generic cp --offload or > similar would probably make more sense on the client side. I don't think it really matters what the optimal case is, it matters what the worst case is. Think about it - a reflink really just is a smart shortcut for copy + dedup, which a filesystem on the server could do anyway. On the other hand a user of cp --reflink expects it to be a quick operation. So it's time folks finally get the damn copyfile system call in, use that for CIFS, NFS and co, as well as letting btrfs optimize it. -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
