QA output created by 242
btrfs-progs v5.15 
See http://btrfs.wiki.kernel.org for more information.

NOTE: several default settings have changed in version 5.15, please make sure
      this does not affect your deployments:
      - DUP for metadata (-m dup)
      - enabled no-holes (-O no-holes)
      - enabled free-space-tree (-R free-space-tree)

Label:              (null)
UUID:               7e612b63-2b57-4c13-8829-99e7c9e2c61a
Node size:          16384
Sector size:        4096
Filesystem size:    20.00GiB
Block group profiles:
  Data:             RAID1             1.00GiB
  Metadata:         RAID1           256.00MiB
  System:           RAID1             8.00MiB
SSD detected:       no
Zoned device:       no
Incompat features:  extref, skinny-metadata, no-holes
Runtime features:   free-space-tree
Checksum:           crc32c
Number of devices:  2
Devices:
   ID        SIZE  PATH
    1    10.00GiB  /dev/mapper/vg0-lv9
    2    10.00GiB  /dev/mapper/vg0-lv8

wrote 10485760/10485760 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
File foo data:
0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab
*
10485760