When an IO fails then zio_vdev_io_done() can call vdev_probe()
to determine the health of the vdev. This is safe as long as
the original zio was submitted with zio_wait() and holds the
SCL_STATE_ALL lock over the operation.
If zio_no_wait() was used then the done callback will submit
the probe IO outside the SCL_STATE_ALL lock and hit this
ASSERT in zio_create()
Resolve the issue by only allowing vdev_probe() to be called
when there's a waiter indicating the caller is using zio_wait().
This assumes that caller is still holding SCL_STATE_ALL.
This issue isn't MMP specific but was surfaced when testing.
Without this patch it can be reproduced by running:
zpool set multihost on <pool>
zinject -d <vdev> -e io -T write -f 50 <pool> -L uber
Reviewed-by: Olaf Faaland <faaland1@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Don Brady <don.brady@intel.com>
Closes #745
Closes #6279