I was wondering about the cross-fs copy through copy_file_range. It seems current implement has below check, that disables such copy. 1577 /* this could be relaxed once a method supports cross-fs copies */ 1578 if (inode_in->i_sb != inode_out->i_sb) 1579 return -EXDEV; May I know what are the thoughts behind disabling cross-fs copy? Code has the comment "once a method supports", but that leaves me wondering exactly what 'method' is expected, and from whom. I disabled the check, and copy across volumes seemed to work fine. At least for a single file (1G size), with no data mismatch, and faster speed than regular copy. -- Joshi
