search for: _require_scratchdev

...ase we do mkfs $* $SCRATCH_DEV Then btrfs will always show the lowest devid in /proc/mounts to maintain consistency, so even though we do mount /dev/sda $SCRATCH_MNT, you will see /dev/sdb as the mounted device in /proc/mounts. So then say the next test wants to just use $SCRATCH_DEV, it will do _require_scratchdev which will check to see if $SCRATCH_DEV is mounted, which it will look like it is not because /proc/mounts shows /dev/sdb instead of /dev/sda, and so it won''t umount $SCRATCH_MNT, and then that test will fail because we can''t mkfs the device because it is busy. I reproduced this...