Comment # 6 on bug 1201114 from Gene Snider

It's not btrfs specific, here's the log for the same operations on an ext4
partition.

Jul 08 11:44:23 Mobile-PC sudo[3379]:     gene : TTY=pts/0 ; PWD=/home/gene ;
USER=root ; COMMAND=/usr/bin/umount -v -R /mnt/chroot
Jul 08 11:44:23 Mobile-PC sudo[3379]: pam_unix(sudo:session): session opened
for user root(uid=0) by (uid=1000)
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-kernel-security.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC sudo[3379]: pam_unix(sudo:session): session closed
for user root
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-kernel-config.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-fs-fuse-connections.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-kernel-tracing.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-kernel-debug.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-fs-bpf.mount: Deactivated
successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]:
mnt-chroot-sys-firmware-efi-efivars.mount: Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-fs-pstore.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys-fs-cgroup.mount:
Deactivated successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot-sys.mount: Deactivated
successfully.
Jul 08 11:44:23 Mobile-PC systemd[1]: mnt-chroot.mount: Deactivated
successfully.
Jul 08 11:44:23 Mobile-PC systemd[1448]: Created slice User Background Tasks
Slice.
Jul 08 11:44:23 Mobile-PC systemd[1448]: Starting Cleanup of User's Temporary
Files and Directories...
Jul 08 11:44:23 Mobile-PC systemd[1448]: Finished Cleanup of User's Temporary
Files and Directories.

> # unplug

Jul 08 11:44:36 Mobile-PC kernel: usb 2-1: USB disconnect, device number 2
Jul 08 11:44:36 Mobile-PC kernel: device offline error, dev sdb, sector 0 op
0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0
Jul 08 11:44:36 Mobile-PC systemd[1]: Stopping Sabrent-Samsung temperature
monitor daemon, started by udev rule...
Jul 08 11:44:36 Mobile-PC systemd[1]: Sabrent-Samsung-tempd.service:
Deactivated successfully.
Jul 08 11:44:36 Mobile-PC systemd[1]: Stopped Sabrent-Samsung temperature
monitor daemon, started by udev rule.
Jul 08 11:44:36 Mobile-PC systemd[1]: Sabrent-Samsung-tempd.service: Consumed
1.867s CPU time.
Jul 08 11:44:36 Mobile-PC kernel: sd 2:0:0:0: [sdb] Synchronizing SCSI cache
Jul 08 11:44:36 Mobile-PC kernel: sd 2:0:0:0: [sdb] Synchronize Cache(10)
failed: Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK

> sudo rmdir /mnt/chroot

Jul 08 11:44:47 Mobile-PC sudo[3426]:     gene : TTY=pts/0 ; PWD=/home/gene ;
USER=root ; COMMAND=/usr/bin/rmdir /mnt/chroot
Jul 08 11:44:47 Mobile-PC sudo[3426]: pam_unix(sudo:session): session opened
for user root(uid=0) by (uid=1000)
Jul 08 11:44:47 Mobile-PC kernel: Buffer I/O error on dev sdb3, logical block
1081344, lost sync page write
Jul 08 11:44:47 Mobile-PC kernel: JBD2: Error -5 detected when updating journal
superblock for sdb3-8.
Jul 08 11:44:47 Mobile-PC kernel: Aborting journal on device sdb3-8.
Jul 08 11:44:47 Mobile-PC kernel: Buffer I/O error on dev sdb3, logical block
1081344, lost sync page write
Jul 08 11:44:47 Mobile-PC kernel: JBD2: Error -5 detected when updating journal
superblock for sdb3-8.
Jul 08 11:44:47 Mobile-PC kernel: EXT4-fs error (device sdb3):
ext4_put_super:1226: comm rmdir: Couldn't clean up the journal
Jul 08 11:44:47 Mobile-PC kernel: EXT4-fs (sdb3): Remounting filesystem
read-only
Jul 08 11:44:47 Mobile-PC sudo[3426]: pam_unix(sudo:session): session closed
for user root

Lots of different error messages, but that's expected.

Gene