When a da or ada device dissappears, outstanding IOs fail with
ENXIO, not EIO. The check for EIO was probably copied from Illumos,
where that is indeed the correct errno.
Without this change, pulling a busy drive from a zpool would usually
turn it into UNAVAIL, even though pulling an idle drive would turn
it into REMOVED. With this change, it is REMOVED every time.
Also, vdev_geom_io_intr shouldn't do zfs_post_remove, because that
results in devd getting two resource.fs.zfs.removed events. The
comment said that the event had to be sent directly instead of
through the async removal thread because "the DE engine is using
this information to discard prevoius I/O errors". However, the fact
that vdev_geom_io_intr was never actually sending the events until
now, and that vdev_geom_orphan never sent them at all, and that
vdev_geom_orphan usually gets called about 2 seconds after the
actual removal, means that FreeBSD's userland can cope with a late
event just fine.
Approved by: ken (mentor)
Sponsored by: Spectra Logic Corporation
MFC after: 4 weeks
03e85c2d9b