We can totally use rsync to write to an SMB (Windows) share mounted under Linux. However, mapping file owner and permission meta data might not be directly possible: it’s expected to get errors such as Operation not permitted during chown). In that case, we can use the rsync arguments --no-perms --no-owner --no-group:

$ rsync -a --no-perms --no-owner --no-group --info=progress2 --stats \
    * /run/user/1000/gvfs/smb-share:server=ubernas.local,share=sharename/dir1/
142,632,841,229  99%   19.84MB/s    1:54:15 (xfr#47707, to-chk=0/52365)   

Number of files: 52,365 (reg: 47,712, dir: 4,653)
Number of created files: 52,287 (reg: 47,707, dir: 4,580)
Number of deleted files: 0
Number of regular files transferred: 47,707
Total file size: 142,877,892,266 bytes
Total transferred file size: 142,632,841,229 bytes
Literal data: 142,632,841,229 bytes
Matched data: 0 bytes
File list size: 1,572,683
File list generation time: 0.001 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 142,671,262,831
Total bytes received: 935,054

sent 142,671,262,831 bytes  received 935,054 bytes  20,805,278.58 bytes/sec
total size is 142,877,892,266  speedup is 1.00

This is a lossy process; in my case, I was totally OK with losing the unixy file owner/group/permission information and to instead just inherit the windowsy default file permission/owner on the target file system.