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iSCSILogicalUnit: add block size override and backstore type selection #2148

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e31468d
iSCSILogicalUnit: add block_size parameter for lio-t and scst
ryan-ronnander Apr 10, 2026
fcab653
iSCSILogicalUnit: add scst_bstype parameter for SCST handler selection
ryan-ronnander Apr 11, 2026
2cbca1f
iSCSILogicalUnit: add scst_bstype and liot_bstype to unsupported para…
ryan-ronnander Apr 11, 2026
146da1e
iSCSILogicalUnit: fix lio-t configfs paths for fileio and pscsi backs…
ryan-ronnander Apr 11, 2026
8f9f820
iSCSILogicalUnit: add emulate_write_cache parameter for lio-t
ryan-ronnander Apr 11, 2026
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127 changes: 111 additions & 16 deletions heartbeat/iSCSILogicalUnit.in
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,11 @@ OCF_RESKEY_lio_iblock=${OCF_RESKEY_lio_iblock:-$OCF_RESKEY_lio_iblock_default}
# Set LIO-T backend default as 'block'
OCF_RESKEY_liot_bstype_default="block"
: ${OCF_RESKEY_liot_bstype=${OCF_RESKEY_liot_bstype_default}}
OCF_RESKEY_block_size_default=""
: ${OCF_RESKEY_block_size=${OCF_RESKEY_block_size_default}}
# Set SCST backing store type default as 'vdisk_blockio'
OCF_RESKEY_scst_bstype_default="vdisk_blockio"
: ${OCF_RESKEY_scst_bstype=${OCF_RESKEY_scst_bstype_default}}

## tgt specifics
# tgt has "backing store type" and "backing store open flags",
Expand Down Expand Up @@ -188,6 +193,20 @@ Setting this integer to 1 will enable CAW IOCTL emulation.
<content type="integer" />
</parameter>

<parameter name="emulate_write_cache" required="0" unique="0">
<longdesc lang="en">
Enable or disable write-back caching for this Logical Unit.
Setting to 1 enables write-back caching (the default for fileio
backstores). Setting to 0 disables it, enabling write-through mode.
Write-through mode is recommended for HA configurations to ensure
data is flushed to disk before the iSCSI write is acknowledged.
Requires the lio-t implementation. For SCST, use the
"scst_write_cache" parameter instead.
</longdesc>
<shortdesc lang="en">Write-back cache (0 or 1)</shortdesc>
<content type="integer" />
</parameter>

<parameter name="vendor_id" required="0" unique="0">
<longdesc lang="en">
The SCSI vendor ID to be configured for this Logical Unit.
Expand Down Expand Up @@ -294,6 +313,31 @@ Do not use PSCSI unless you know exactly how it will be used.
<content type="string" default="${OCF_RESKEY_liot_bstype_default}"/>
</parameter>

<parameter name="block_size" required="0" unique="0">
<longdesc lang="en">
Override the block size presented to initiators for this
Logical Unit. Accepted values are 512, 1024, 2048, or 4096.
This sets the block_size attribute in the LIO kernel target
(configfs) or the blocksize attribute in SCST.
Requires the lio-t or scst implementation.
If unset, the kernel default (typically 512) is used.
</longdesc>
<shortdesc lang="en">Block size (512, 1024, 2048, or 4096)</shortdesc>
<content type="integer" default="${OCF_RESKEY_block_size_default}"/>
</parameter>

<parameter name="scst_bstype" required="0" unique="0">
<longdesc lang="en">
SCST device handler to use when creating the backstore.
Use "vdisk_blockio" for direct I/O (the default) or
"vdisk_fileio" for page cache backed I/O. The fileio handler
is required when presenting smaller block sizes on 4K-native
backing devices. Requires the scst implementation.
</longdesc>
<shortdesc lang="en">SCST device handler (vdisk_blockio or vdisk_fileio)</shortdesc>
<content type="string" default="${OCF_RESKEY_scst_bstype_default}"/>
</parameter>

</parameters>

<actions>
Expand Down Expand Up @@ -430,7 +474,13 @@ iSCSILogicalUnit_start() {
lio-t)
ocf_take_lock $TARGETLOCKFILE
ocf_release_lock_on_exit $TARGETLOCKFILE
iblock_attrib_path="/sys/kernel/config/target/core/iblock_*/${OCF_RESOURCE_INSTANCE}/attrib"
# Map liot_bstype to the configfs core directory name
case "${OCF_RESKEY_liot_bstype}" in
block) liot_configfs_core="iblock_*" ;;
fileio) liot_configfs_core="fileio_*" ;;
pscsi) liot_configfs_core="pscsi_*" ;;
esac
liot_core_path="/sys/kernel/config/target/core/${liot_configfs_core}/${OCF_RESOURCE_INSTANCE}"
# For lio, we first have to create a target device, then
# add it to the Target Portal Group as an LU.
# Handle differently 'block', 'fileio' and 'pscsi'
Expand All @@ -447,10 +497,13 @@ iSCSILogicalUnit_start() {
ocf_run targetcli /backstores/${OCF_RESKEY_liot_bstype} create ${OCF_RESOURCE_INSTANCE} ${OCF_RESKEY_path} || exit $OCF_ERR_GENERIC
fi
if [ -n "${OCF_RESKEY_scsi_sn}" ]; then
echo ${OCF_RESKEY_scsi_sn} > /sys/kernel/config/target/core/iblock_*/${OCF_RESOURCE_INSTANCE}/wwn/vpd_unit_serial
echo ${OCF_RESKEY_scsi_sn} > ${liot_core_path}/wwn/vpd_unit_serial
fi
if [ -n "${OCF_RESKEY_product_id}" ]; then
echo "${OCF_RESKEY_product_id}" > /sys/kernel/config/target/core/iblock_*/${OCF_RESOURCE_INSTANCE}/wwn/product_id
echo "${OCF_RESKEY_product_id}" > ${liot_core_path}/wwn/product_id
fi
if [ -n "${OCF_RESKEY_block_size}" ]; then
echo ${OCF_RESKEY_block_size} > ${liot_core_path}/attrib/block_size || exit $OCF_ERR_GENERIC
fi

ocf_run targetcli /iscsi/${OCF_RESKEY_target_iqn}/tpg1/luns create /backstores/${OCF_RESKEY_liot_bstype}/${OCF_RESOURCE_INSTANCE} ${OCF_RESKEY_lun} || exit $OCF_ERR_GENERIC
Expand All @@ -476,17 +529,24 @@ iSCSILogicalUnit_start() {
fi

if [ -n "${OCF_RESKEY_emulate_tpu}" ]; then
echo ${OCF_RESKEY_emulate_tpu} > ${iblock_attrib_path}/emulate_tpu || exit $OCF_ERR_GENERIC
echo ${OCF_RESKEY_emulate_tpu} > ${liot_core_path}/attrib/emulate_tpu || exit $OCF_ERR_GENERIC
fi
if [ -n "${OCF_RESKEY_emulate_3pc}" ]; then
echo ${OCF_RESKEY_emulate_3pc} > ${iblock_attrib_path}/emulate_3pc || exit $OCF_ERR_GENERIC
echo ${OCF_RESKEY_emulate_3pc} > ${liot_core_path}/attrib/emulate_3pc || exit $OCF_ERR_GENERIC
fi
if [ -n "${OCF_RESKEY_emulate_caw}" ]; then
echo ${OCF_RESKEY_emulate_caw} > ${iblock_attrib_path}/emulate_caw || exit $OCF_ERR_GENERIC
echo ${OCF_RESKEY_emulate_caw} > ${liot_core_path}/attrib/emulate_caw || exit $OCF_ERR_GENERIC
fi
if [ -n "${OCF_RESKEY_emulate_write_cache}" ]; then
echo ${OCF_RESKEY_emulate_write_cache} > ${liot_core_path}/attrib/emulate_write_cache || exit $OCF_ERR_GENERIC
fi
;;
scst)
ocf_run scstadmin -open_dev "${OCF_RESOURCE_INSTANCE}" -handler vdisk_blockio -attributes "filename=${OCF_RESKEY_path},nv_cache=0,write_through=1"
local scst_attrs="filename=${OCF_RESKEY_path},nv_cache=0,write_through=1"
if [ -n "${OCF_RESKEY_block_size}" ]; then
scst_attrs="${scst_attrs},blocksize=${OCF_RESKEY_block_size}"
fi
ocf_run scstadmin -open_dev "${OCF_RESOURCE_INSTANCE}" -handler ${OCF_RESKEY_scst_bstype} -attributes "${scst_attrs}"
if [ -n "${OCF_RESKEY_scsi_sn}" ]; then
ocf_run scstadmin -set_dev_attr "${OCF_RESOURCE_INSTANCE}" -attributes "usn=${OCF_RESKEY_scsi_sn}" -force -noprompt
fi
Expand Down Expand Up @@ -577,7 +637,7 @@ iSCSILogicalUnit_stop() {
;;
scst)
ocf_run -warn scstadmin -rem_lun ${OCF_RESKEY_lun} -driver iscsi -target "${OCF_RESKEY_target_iqn}" -force -noprompt
ocf_run scstadmin -close_dev "${OCF_RESOURCE_INSTANCE}" -handler vdisk_blockio -force -noprompt
ocf_run scstadmin -close_dev "${OCF_RESOURCE_INSTANCE}" -handler ${OCF_RESKEY_scst_bstype} -force -noprompt
;;
esac

Expand Down Expand Up @@ -631,9 +691,14 @@ iSCSILogicalUnit_monitor() {
configfs_path="/sys/kernel/config/target/iscsi/${OCF_RESKEY_target_iqn}/tpgt_1/lun/lun_${OCF_RESKEY_lun}/*/udev_path"
[ -e ${configfs_path} ] && [ `cat ${configfs_path}` = "${OCF_RESKEY_path}" ] && return $OCF_SUCCESS

# if we aren't activated, is a block device still left over?
block_configfs_path="/sys/kernel/config/target/core/iblock_*/${OCF_RESOURCE_INSTANCE}/udev_path"
[ -e ${block_configfs_path} ] && ocf_log warn "existing block without an active lun: ${block_configfs_path}"
# if we aren't activated, is a backstore still left over?
case "${OCF_RESKEY_liot_bstype}" in
block) liot_configfs_core="iblock_*" ;;
fileio) liot_configfs_core="fileio_*" ;;
pscsi) liot_configfs_core="pscsi_*" ;;
esac
block_configfs_path="/sys/kernel/config/target/core/${liot_configfs_core}/${OCF_RESOURCE_INSTANCE}/udev_path"
[ -e ${block_configfs_path} ] && ocf_log warn "existing backstore without an active lun: ${block_configfs_path}"
[ -e ${block_configfs_path} ] && return $OCF_ERR_GENERIC
;;
scst)
Expand All @@ -657,6 +722,36 @@ iSCSILogicalUnit_validate() {
fi
done

# Validate scst_bstype
case "${OCF_RESKEY_scst_bstype}" in
vdisk_blockio|vdisk_fileio)
;;
*)
ocf_exit_reason "Invalid scst_bstype ${OCF_RESKEY_scst_bstype} (must be vdisk_blockio or vdisk_fileio)"
exit $OCF_ERR_CONFIGURED
;;
esac
if [ "${OCF_RESKEY_scst_bstype}" != "${OCF_RESKEY_scst_bstype_default}" ] && [ "${OCF_RESKEY_implementation}" != "scst" ]; then
ocf_exit_reason "scst_bstype is only supported with the scst implementation"
exit $OCF_ERR_CONFIGURED
fi

# Validate block_size if set
if [ -n "${OCF_RESKEY_block_size}" ]; then
case "${OCF_RESKEY_block_size}" in
512|1024|2048|4096)
;;
*)
ocf_exit_reason "Invalid block_size ${OCF_RESKEY_block_size} (must be 512, 1024, 2048, or 4096)"
exit $OCF_ERR_CONFIGURED
;;
esac
if [ "${OCF_RESKEY_implementation}" != "lio-t" ] && [ "${OCF_RESKEY_implementation}" != "scst" ]; then
ocf_exit_reason "block_size is only supported with the lio-t or scst implementation"
exit $OCF_ERR_CONFIGURED
fi
fi

# Is the configured implementation supported?
case "$OCF_RESKEY_implementation" in
"iet"|"tgt"|"lio"|"lio-t"|"scst")
Expand Down Expand Up @@ -722,19 +817,19 @@ iSCSILogicalUnit_validate() {
iet)
# IET does not support setting the vendor and product ID
# (it always uses "IET" and "VIRTUAL-DISK")
unsupported_params="vendor_id product_id allowed_initiators lio_iblock tgt_bstype tgt_bsoflags tgt_bsopts tgt_device_type emulate_tpu emulate_3pc emulate_caw liot_bstype"
unsupported_params="vendor_id product_id allowed_initiators lio_iblock tgt_bstype tgt_bsoflags tgt_bsopts tgt_device_type emulate_tpu emulate_3pc emulate_caw emulate_write_cache liot_bstype scst_bstype"
;;
tgt)
unsupported_params="allowed_initiators lio_iblock emulate_tpu emulate_3pc emulate_caw liot_bstype"
unsupported_params="allowed_initiators lio_iblock emulate_tpu emulate_3pc emulate_caw emulate_write_cache liot_bstype scst_bstype"
;;
lio)
unsupported_params="scsi_id vendor_id product_id tgt_bstype tgt_bsoflags tgt_bsopts tgt_device_type emulate_tpu emulate_3pc emulate_caw liot_bstype"
unsupported_params="scsi_id vendor_id product_id tgt_bstype tgt_bsoflags tgt_bsopts tgt_device_type emulate_tpu emulate_3pc emulate_caw emulate_write_cache liot_bstype scst_bstype"
;;
lio-t)
unsupported_params="scsi_id vendor_id tgt_bstype tgt_bsoflags tgt_bsopts tgt_device_type lio_iblock"
unsupported_params="scsi_id vendor_id tgt_bstype tgt_bsoflags tgt_bsopts tgt_device_type lio_iblock scst_bstype"
;;
scst)
unsupported_params="scsi_id emulate_tpu emulate_3pc emulate_caw"
unsupported_params="scsi_id emulate_tpu emulate_3pc emulate_caw emulate_write_cache liot_bstype"
;;
esac

Expand Down