Re: How to figure out which block device has been created by tcm_loop?

[Ming Lin <mlin@xxxxxxxxxx>]

On Fri, 2015-09-25 at 20:00 -0700, Sheng Yang wrote:
> Hi,
> 
> I got hard time to determine which block device was created when I was
> using tcm_loop.
> 
> Normally I would just take a look at dmesg, see sda or sdb got
> attached etc, but that's not a reliable way of doing it I guess.
> 
> I also found the device showed up in "udevadm monitor", but unable to
> find a way to associate with the original device I created from TCM
> either.
> 
> Here is the commands I've used to create the device(with tcmu-runner
> running with file_handler demo code). I guess it's possible associate
> with iscsi name somehow:
> 
> mkdir -p /sys/kernel/config/target/core/user_1/test
> echo dev_size=1024000000 > /sys/kernel/config/target/core/user_1/test/control
> echo dev_config=file//root/test >
> /sys/kernel/config/target/core/user_1/test/control
> echo 1 > /sys/kernel/config/target/core/user_1/test/enable
> 
> mkdir -p /sys/kernel/config/target/loopback/naa.60014059436855c1/tpgt_1
> echo "naa.60014051153c198a" >
> /sys/kernel/config/target/loopback/naa.60014059436855c1/tpgt_1/nexus
> mkdir -p /sys/kernel/config/target/loopback/naa.60014059436855c1/tpgt_1/lun/lun_0
> ln -s /sys/kernel/config/target/core/user_1/test
> /sys/kernel/config/target/loopback/naa.60014059436855c1/tpgt_1/lun/lun_0/c68d79910b

You can get scsi port/lun from the configfs.

Try below script.
The only missing part is I don't how to map wwn to SCSI host number.
So you need to modify the hard-coded map_wwn_to_host().

mlin@ssi:~$ ./tcm.sh 
/sys/kernel/config/target/loopback/naa.6000000000000001/tpgt_1/lun/lun_0:/dev/sdd
/sys/kernel/config/target/loopback/naa.6000000000000001/tpgt_1/lun/lun_1:/dev/sde
/sys/kernel/config/target/loopback/naa.6000000000000001/tpgt_5/lun/lun_3:/dev/sdf
/sys/kernel/config/target/loopback/naa.60014055f195952b/tpgt_1/lun/lun_0:/dev/sdc

------

#!/bin/bash
#tcm.sh

tcm_loop_dir=/sys/kernel/config/target/loopback

function get_wwns()
{
	ls $tcm_loop_dir |grep naa
}

#$1: wwn
function map_wwn_to_host()
{
	local wwn=$1
	#TDB: how to map wwn to SCSI host number???
	#I don't know, just hard code it now
	#run "lsscsi -H" to see the scsi host number
	if [ "$wwn" = "naa.6000000000000001" ] ; then
		echo 7
	else
		echo 6
	fi
}

#$1:wwn 
function get_ports()
{
	local wwn=$1
	local wwn_path=${tcm_loop_dir}/${wwn}
	ls $wwn_path |grep tpgt_ | awk -F"tpgt_" '{print $2}'
}

#$1:wwn
#$2:port
function get_luns()
{
	local wwn=$1
	local port=$2
	lun_path=${tcm_loop_dir}/${wwn}/tpgt_${port}/lun
	ls $lun_path |grep lun_ | awk -F"lun_" '{print $2}'
}

#$1: host
#$2: port
#$3: lun
function get_one_dev()
{
	local host=$1
	local port=$2
	local lun=$3
	local id=$host:0:$port:$lun

	lsscsi | grep $id | awk '{print $6}'
}

function get_all_devs()
{
	local host
	local port
	local lun
	local wwn

	for wwn in `get_wwns` ; do
		host=`map_wwn_to_host $wwn`
		for port in `get_ports $wwn` ; do
			for lun in `get_luns $wwn $port` ; do
				echo -n $tcm_loop_dir/$wwn/tpgt_$port/lun/lun_$lun:
				get_one_dev $host $port $lun
			done
		done
	done
}

get_all_devs




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