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# Copyright (c) 2017 Spectra Logic Corporation
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#
# Routines that use gnop(8) to simulate devices that can disappear at any time
#

# Create a gnop device on top of a real device.  Don't use the full extent; use
# a portion in the middle so that any ZFS label present on the real device
# won't be present on the gnop device and vice versa.
function create_gnop
{
	# Name of disk to use, with or without /dev/
	typeset disk=$1
	# Optional physical path to use
	typeset physpath=$2
	# size of disk in bytes
	typeset -li disk_size
	# disk size, rounded down to multiple of 16384
	typeset -li disk_size_rounded
	# size of the nop device in bytes
	typeset -li nop_size
	# offset of the beginning of the nop device in bytes
	typeset -li nop_offset
	typeset args

	disk_size=`diskinfo $disk | cut -f 3`
	# Round it down so the nop device will be 4k-aligned
	disk_size_rounded=$(( ${disk_size} / 16384 * 16384 ))
	nop_size=$(( ${disk_size_rounded} / 4 ))
	nop_offset=${nop_size}
	args="-s ${nop_size} -o ${nop_offset}"
	if [ -n "$physpath" ]; then
		args="$args -z $physpath"
	fi

	gnop create ${args} ${disk}
}

# Create multiple gnop devices
function create_gnops
{
	typeset disk
	for disk in $@; do
		create_gnop "$disk" || return 1
	done
	return 0
}

# Destroy a gnop device.  
function destroy_gnop
{
	# Name of the underlying (non-gnop) device
	typeset disk=$1

	# Use "-f" so we can destroy a gnop with a consumer (like ZFS)
	gnop destroy -f ${disk}.nop

	# Wait for it to disappear
	for i in `seq 5`; do
		gnop status ${disk}.nop >/dev/null 2>/dev/null || break
		sleep $i
	done
}

# Destroy multiple gnop devices.  Attempt to destroy them all, ignoring errors
function destroy_gnops
{
	typeset disk
	for disk in $@; do
		destroy_gnop "$disk"
	done
	return 0
}