btrfs-progs v7.1
See https://btrfs.readthedocs.io for more information.

Performing full device TRIM /dev/loop1 (5.00GiB) ...
NOTE: default settings have changed in version 6.19 (supported since linux 6.1):
      - enable block-group-tree (-O bgt)

Label:              (null)
UUID:               53ad173c-210c-4b1e-8804-42467bf32308
Node size:          4096
Sector size:        4096	(CPU page size: 4096)
Filesystem size:    5.00GiB
Block group profiles:
  Data:             single            8.00MiB
  Metadata:         DUP             256.00MiB
  System:           DUP               8.00MiB
SSD detected:       yes
Zoned device:       no
Features:           extref, skinny-metadata, no-holes, free-space-tree, block-group-tree
Checksum:           crc32c
Number of devices:  1
Devices:
   ID        SIZE  PATH      
    1     5.00GiB  /dev/loop1

Create subvolume '/mnt/scratch/S1'
Create readonly snapshot of '/mnt/scratch/S1' in '/mnt/scratch/S2'
S1 id 256 root level 3 files 30000
Delete subvolume 256 (no-commit): '/mnt/scratch/S1'
first run interrupted at drop key (4535) level 3
resume 0: drop key (4535) level 3
resume 1: drop key (4535) level 3
resume 2: drop key (4535) level 3
resume 3: drop key (4535) level 3
resume 4: drop key (4535) level 3
Waiting for 1 subvolume
Subvolume id 256 is gone (1/1)
umount: /mnt/scratch: not mounted.