reflink block size

$ ./testall.sh
Creating FS with block size of 65536
mount: /home/teknoraver/src/fs: fsconfig system call failed: Function not implemented.
       dmesg(1) may have more information after failed mount system call.
umount: xfs: not mounted.
Creating FS with block size of 32768
mount: /home/teknoraver/src/fs: fsconfig system call failed: Function not implemented.
       dmesg(1) may have more information after failed mount system call.
umount: xfs: not mounted.
Creating FS with block size of 16384
page: 16K
Trying block size 16384K.. OK
Trying block size 8192K.. errno = 22
Creating FS with block size of 8192
page: 16K
Trying block size 16384K.. OK
Trying block size 8192K.. OK
Trying block size 4096K.. errno = 22
Creating FS with block size of 4096
page: 16K
Trying block size 16384K.. OK
Trying block size 8192K.. OK
Trying block size 4096K.. OK
Trying block size 2048K.. errno = 22
Creating FS with block size of 2048
page: 16K
Trying block size 16384K.. OK
Trying block size 8192K.. OK
Trying block size 4096K.. OK
Trying block size 2048K.. OK
Trying block size 1024K.. errno = 22
Creating FS with block size of 1024
page: 16K
Trying block size 16384K.. OK
Trying block size 8192K.. OK
Trying block size 4096K.. OK
Trying block size 2048K.. OK
Trying block size 1024K.. OK
Trying block size 512K.. errno = 22
Creating FS with block size of 512
Minimum block size for CRC enabled filesystems is 1024 bytes.
Usage: mkfs.xfs
/* blocksize */         [-b size=num]
/* config file */       [-c options=xxx]
/* metadata */          [-m crc=0|1,finobt=0|1,uuid=xxx,rmapbt=0|1,reflink=0|1,
                            inobtcount=0|1,bigtime=0|1]
/* data subvol */       [-d agcount=n,agsize=n,file,name=xxx,size=num,
                            (sunit=value,swidth=value|su=num,sw=num|noalign),
                            sectsize=num
/* force overwrite */   [-f]
/* inode size */        [-i perblock=n|size=num,maxpct=n,attr=0|1|2,
                            projid32bit=0|1,sparse=0|1,nrext64=0|1]
/* no discard */        [-K]
/* log subvol */        [-l agnum=n,internal,size=num,logdev=xxx,version=n
                            sunit=value|su=num,sectsize=num,lazy-count=0|1]
/* label */             [-L label (maximum 12 characters)]
/* naming */            [-n size=num,version=2|ci,ftype=0|1]
/* no-op info only */   [-N]
/* prototype file */    [-p fname]
/* quiet */             [-q]
/* realtime subvol */   [-r extsize=num,size=num,rtdev=xxx]
/* sectorsize */        [-s size=num]
/* version */           [-V]
                        devicename
<devicename> is required unless -d name=xxx is given.
<num> is xxx (bytes), xxxs (sectors), xxxb (fs blocks), xxxk (xxx KiB),
      xxxm (xxx MiB), xxxg (xxx GiB), xxxt (xxx TiB) or xxxp (xxx PiB).
<value> is xxx (512 byte blocks).
umount: xfs: not mounted.