zdev/dracut: add rd.zfcp cmdline option handling

Add parsing of dracut cmdline option "rd.zfcp=..." at initrd runtime.
It delegates configuration to chzdev.

Implement `dracut --print-cmdline` and `dracut --hostonly-cmdline` for
initrd build time. Emit an rd.zfcp option for each zfcp-attached SCSI disk
in dracut's device dependency graph (to mount the root-fs, or to access the
kdump target).

This allows a distribution independent device configuration.
Configuration is consistent by using chzdev as backend.
It also prevents duplicate activations of the same device.

Along with the existing functionality of zdev/dracut, it makes the
following dracut modules superfluous:
https://github.com/dracutdevs/dracut/tree/master/modules.d/95zfcp
[rd.zfcp.conf is no longer needed and thus ignored here; the preceding
 ("zdev/dracut: fix marking hostonly files so delete option works")
 makes rd.hostonly=0 work as a generic replacement]
https://github.com/dracutdevs/dracut/tree/master/modules.d/95zfcp_rules

Github-ID: https://github.com/ibm-s390-linux/s390-tools/pull/158
Acked-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/dracut/95zdev/zdev-lib.sh

@@ -25,3 +25,78 @@ zdev_is_kdump() {
     fi
     return 1
 }
+
+zdev_zfcp_auto_lun_scan_active() {
+    local _fcpdevsysfs=$1
+    local _porttype _lunscan
+    read -r _porttype < "$_fcpdevsysfs"/host*/fc_host/host*/port_type
+    read -r _lunscan < /sys/module/zfcp/parameters/allow_lun_scan
+    if [[ "$_porttype" == "NPIV VPORT" && "$_lunscan" == "Y" ]]; then
+        return 0
+    fi
+    return 1
+}
+
+# zdev_check_dev() can be extended for other device types such as DASD or PCIe
+zdev_check_dev() {
+    local _dev=$1
+    local _devsysfs _devtype _subsystem _driver
+    local _intlun _fcplun _scsitarget _wwpn _hbaid
+    _devsysfs=$(
+        cd -P /sys/dev/block/"$_dev" 2> /dev/null && echo "$PWD"
+             )
+    # This is roughly what systemd's udev-builtin-path_id does for zfcp:
+    while [[ -n "$_devsysfs" ]]; do
+        # ascend to parent: strip last path part
+        _devsysfs=${_devsysfs%/*}
+        _subsystem=$(
+            cd -P "$_devsysfs"/subsystem 2> /dev/null && echo "$PWD"
+              )
+        if [[ "${_subsystem##*/}" == "scsi" ]]; then
+            _devtype=$(grep "^DEVTYPE=" "$_devsysfs"/uevent)
+            # check for FCP LUN
+            if [[ "$_devtype" == "DEVTYPE=scsi_device" ]]; then
+                _intlun=${_devsysfs##*:}
+                # convert _intlun to _fcplun [int_to_scsilun()]
+                _fcplun=0
+                ((_fcplun |= (_intlun & 0x000000000000ffff) << 48))
+                ((_fcplun |= (_intlun & 0x00000000ffff0000) << 16))
+                ((_fcplun |= (_intlun & 0x0000ffff00000000) >> 16))
+                ((_fcplun |= (_intlun & 0xffff000000000000) >> 48))
+                printf -v _fcplun "0x%016x" "$_fcplun"
+                # bail out if not scsi_transport_fc
+                [[ "${_devsysfs/*rport-*/FOUND}" == "FOUND" ]] || return 0
+                continue
+            fi
+            # check for target WWPN
+            if [[ "$_devtype" == "DEVTYPE=scsi_target" ]]; then
+                _scsitarget=${_devsysfs##*/}
+                read -r _wwpn < "$_devsysfs/fc_transport/$_scsitarget/port_name"
+                continue
+            fi
+        fi
+        if [[ "${_subsystem##*/}" == "ccw" ]]; then
+            _driver=$(
+                cd -P "$_devsysfs"/driver 2> /dev/null && echo "$PWD"
+                  )
+            # check for FCP device (vHBA) bus-ID
+            if [[ "${_driver##*/}" == "zfcp" ]]; then
+                _hbaid=${_devsysfs##*/}
+                # drop full path and use zfcp auto LUN scan, if:
+                # - not building for kdump which has zfcp auto LUN scan off
+                # - and zfcp auto LUN scan is available
+                if ! zdev_is_kdump && \
+                        zdev_zfcp_auto_lun_scan_active "$_devsysfs"; then
+                    unset _wwpn
+                    unset _fcplun
+                fi
+                if [[ -n "$_wwpn" ]] && [[ -n "$_fcplun" ]]; then
+                    printf " rd.zfcp=%s,%s,%s\n" "$_hbaid" "$_wwpn" "$_fcplun"
+                else
+                    printf " rd.zfcp=%s\n" "$_hbaid"
+                fi
+                break
+            fi
+        fi
+    done
+}