Improve zpool labelclear
- As implemented the zpool labelclear command overwrites
the calculated offsets of all four vdev labels even when only a
single valid label is found. If the device as been re-purposed
but still contains a valid label this can result in space no
longer owned by ZFS being zeroed. Prevent this by verifying
every label removed is intact before it's overwritten.
- Address a small bug in zpool_do_labelclear() which prevented
labelclear from working on file vdevs. Only block devices support
BLKFLSBUF, try the ioctl() but when it's reported as unsupported
this should not be fatal.
- Fix zpool labelclear so it can be run on vdevs which were
removed from the pool with zpool remove. Additionally, allow
intact but partial labels to be cleared as in the case of a failed
zpool attach or zpool replace.
- Remove LABELCLEAR and LABELREAD variables for test cases.
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8500
Closes #8373
Closes #6261