difficulty reusing disks after destroying ZFS filesystems

[hugues]

After some heavy use of a disk-base ZFS filesystem, I decided to
destroy it in order to reuse the space (this is a test machine).

# zfs status pool0

pool: pool0
state: ONLINE
status: CLEAN
config:

NAME STATE READ WRITE CKSUM
pool0 ONLINE 0 0 0
sdc1 ONLINE 0 0 0

errors: No known data errors


# zfs destroy pool0/backup
[lots of churning]

# zpool destroy pool0
[more churning]

From then on I'm expecting to be able to reuse /dev/sdc1

# zpool create newtest /dev/sdc1
error: /dev/sdc1 busy

This kept repeating, /dev/sdc1 had become unavailable for some reason.
Unloading the kernel module did not help.

However, a reboot of the entire machine did help. I was able to reuse /
dev/sdc