with xfsdump-2.2.48 and presumably later, qa test 042 is doing:

_do "Run xfs_fsr on filesystem" "$XFS_FSR_PROG -v $SCRATCH_DEV"

after creating a fragmented file on that device, yet somehow it is not finding
or defragmenting that file.

look at 042.full:

--- xfs_bmap -v /mnt/scratch/fragmented
/mnt/scratch/fragmented:
 EXT: FILE-OFFSET      BLOCK-RANGE      AG AG-OFFSET        TOTAL
   0: [0..4967]:       93336..98303      2 (27800..32767)    4968
   1: [4968..5095]:    77272..77399      2 (11736..11863)     128

<snip>

 457: [19416..19423]:  45112..45119      1 (12344..12351)       8
--- sum /mnt/scratch/fragmented >/tmp/10530.sum1
--- rm -rf /mnt/scratch/{pad,hole*}
--- /usr/sbin/xfs_fsr -v /dev/sdb3
/mnt/scratch start inode=0
--- xfs_bmap -v /mnt/scratch/fragmented
/mnt/scratch/fragmented:
 EXT: FILE-OFFSET      BLOCK-RANGE      AG AG-OFFSET        TOTAL
   0: [0..4967]:       93336..98303      2 (27800..32767)    4968
   1: [4968..5095]:    77272..77399      2 (11736..11863)     128
   2: [5096..5223]:    75872..75999      2 (10336..10463)     128
   3: [5224..5351]:    68984..69111      2 (3448..3575)       128

<snip>

 456: [19408..19415]:  45096..45103      1 (12328..12335)       8
 457: [19416..19423]:  45112..45119      1 (12344..12351)       8
--- src/fill2fs_check /tmp/10530.manifest
--- sum /mnt/scratch/fragmented >/tmp/10530.sum2
--- diff /tmp/10530.sum1 /tmp/10530.sum2
--- _check_scratch_fs

pointing it at the mountpoint (/mnt/scratch) seems to behave the same.

pointing it directly at /mnt/scratch/fragmented works fine.