Hi Jeremy, On Wed, 9 Nov 2022 11:24:26 -0800, Jeremy Allison via samba-technical wrote: > On Wed, Nov 09, 2022 at 10:47:41AM -0800, Jeremy Allison wrote: > > > >So it *looks* like the copy_file_range() syscall will internally > >call the equivalent of FICLONERANGE if the underlying file > >system supports it. > > > >So maybe the right fix is to remove the FICLONERANGE specific > >code from our vfs_btrfs.c and just always use copy_file_range(). > > > >Any comments from other Samba Team members ? > > So right now Steve what is preventing FSCTL_DUP_EXTENTS_TO_FILE > from working against anything other then btrfs on Samba is the > following code: > > source3/smbd/smb2_ioctl_filesys.c:fsctl_dup_extents_send() > > 180 if ((dst_fsp->conn->fs_capabilities > 181 & FILE_SUPPORTS_BLOCK_REFCOUNTING) == 0) { > 182 DBG_INFO("FS does not advertise block refcounting support\n"); > 183 tevent_req_nterror(req, NT_STATUS_INVALID_DEVICE_REQUEST); > 184 return tevent_req_post(req, ev); > 185 } > > because currently only the vfs_btrfs module reports FILE_SUPPORTS_BLOCK_REFCOUNTING, > not vfs_default. > > and also in: > > source3/modules/vfs_default.c:vfswrap_offload_write_send() > > 2194 case FSCTL_DUP_EXTENTS_TO_FILE: > 2195 DBG_DEBUG("COW clones not supported by vfs_default\n"); > 2196 tevent_req_nterror(req, NT_STATUS_INVALID_PARAMETER); > 2197 return tevent_req_post(req, ev); > > but looking at vfs_btrfs it looks like that code should > probably also be in vfswrap_offload_read_send() as well > and the error code should be NT_STATUS_INVALID_DEVICE_REQUEST. > > We also need to duplicate the logic in vfs_btrfs for > handling FSCTL_DUP_EXTENTS_TO_FILE into VFS default, > gated on support for the copy_file_range() system > call (which would set FILE_SUPPORTS_BLOCK_REFCOUNTING > in the fs_capabilities return from vfs_default). > > I think this is doable with some work... I think it's doable too :-). As indicated in my other mail, I think FICLONERANGE will need to be used for FSCTL_DUP_EXTENTS_TO_FILE instead of copy_file_range(). I'm not sure how to best handle FILE_SUPPORTS_BLOCK_REFCOUNTING - ideally we'd set it for Btrfs and XFS(reflink=1) backed shares only. Another option might be to advertise FILE_SUPPORTS_BLOCK_REFCOUNTING and then propagate errors up to the client if FICLONERANGE fails for FSCTL_DUP_EXTENTS_TO_FILE. Client copy fallback would work, but the extra request overhead would be ugly. Cheers, David