Comment 1 for bug 1790831

------- Comment From <email address hidden> 2018-09-05 05:36 EDT-------
Description: lstape, lsluns: handle non-zfcp; lin_tape multiple paths

Symptom: lstape shows unexpected additional Device suffix numbers in
excess output columns for each additional path of the same
tape/changer driven by the IBM lin_tape device driver
(independent of actual path failover enablement in lin_tape).
It also shows a wrong number of found devices in the header
(without --scsi-only).

lstape prints error about "Unexpected extra argument:" and the
usage for "sg_inq" along with wrong tabular output.

lsluns prints ENOENT error text for "cat" on SCSI device sysfs
attributes hba_id, wwpn, and fcp_lun.

lstape with --verbose option prints ENOENT error text for
"cat" on SCSI device sysfs attributes hba_id and wwpn.

lstape man page: Description of --type and <devbusid> filter
for channel tapes is incomplete. SCSI output description is
incomplete.

lstape shows "N/A" instead of the HBA device bus-ID with
virtio-scsi-ccw.

Problem: s390-tools-1.8.0 before the first upstream commit b627b8d8e1ab
("Initial s390-tools-2.0.0 import") introduced SCSI
tape/changer output for lstape. It used the SCSI device serial
number as lookup key to find a match in IBM lin_tape device
driver proc-fs output for a given SCSI device name. Multiple
paths to the same tape/changer have the same serial number.
Multiple matches cause excess arguments to printf. Explaining
the resulting output, the bash man page says: "The format is
reused as necessary to consume all of the arguments." This
also causes a wrong number of found devices.

The default bash settings have nullglob disabled so if
$SCSI_DEV/scsi_generic* aka
/sys/bus/scsi/devices/*:*:*:*/scsi_generic* does not match
anything, it leaves the glob pattern unmodified and
SG_DEV=$(basename $SG_DEV/*) results in the literal "*". If
$SG_INQ exists, it invoked sg_inq with more than the one
allowed positional argument for a SCSI generic device node
"sg_inq /dev/*". Causing error messages and the usage of
sg_inq to land in $TAPE_SERIAL.

lsluns iterates SCSI generic devices and unconditionally
reads zfcp-specific SCSI device sysfs attributes hba_id, wwpn,
and fcp_lun.

lstape --verbose unconditionally reads zfcp-specific SCSI
device sysfs attributes hba_id and wwpn.

<devbusid> filter missing from synopsis. <device-type> example
at wrong place with <devbusid> filter. <devbusid> filter
option description is a duplicate of <device-type> filter
option description. SCSI output description misses fields.

Lstape only used the zfcp-specific sysfs attribute hba_id.

Solution: Prefer sysfs to find lin_tape device name for SCSI device.
Fallback: The lin_tape proc-fs output format has changed over
the years. The HBA device driver string can contain whitespace
(e.g. "Virtio SCSI HBA") and breaks the field numbers with
tokenized parsing. Grep for the SCSI device name as word (to
skip names with same substring, such as 0:0:1:1 also matching
0:0:1:10) and cut the first field 'Number' (lin_tape device
name suffix). If there is no SCSI column at all [lin_tape
before v2.2.0] (and no SCSI LLDD or other column with a name
accidentally matching an existing SCSI device name), we get no
match and better bail out with the initialized "N/A" for the
lstape column "Device".

To not have to rely on the nullglob setting, explicitly check
for the existence of $SCSI_DEV/scsi_generic before evaluating
SG_DEV=$(basename $SG_DEV/*). Also handle availability of
sg_inq but absence of scsi_generic individually to provide the
user with a hint if only sg is missing.

Simply skip non-zfcp SCSI devices, such as iSCSI or
virtio-scsi-ccw, to not erroneously access absent attributes.

Assume "N/A" for HBA and WWPN of non-zfcp SCSI devices, such
as iSCSI or virtio-scsi-ccw, to not erroneously access absent
zfcp-specific sysfs attributes.

Add <devbusid> filter to synopsis. Move <device-type> example
to <device-type> option. Replace <devbusid> filter option
description. Move existing SCSI output description to a new
subsection and add description of missing fields.

Also search sysfs for an ancestor with subsystem ccw.

Reproduction: Attach more than one path to the same SCSI tape or changer and
load the IBM lin_tape device driver.

Unload sg kernel module.

Attach non-zfcp SCSI devices such as iSCSI or virtio-scsi-ccw.

Attach non-zfcp SCSI devices such as iSCSI or virtio-scsi-ccw.

man lstape

Attach SCSI tape or changer with virtio-scsi-ccw to a KVM
guest and run "lstape --verbose".

This fix will be introduced with s390-tools 2.7.0

https://github.com/ibm-s390-tools/s390-tools/commits/master

Following git-commits are required
ef4dc7a45b1b80c58076a0a317245569d84b2754
cdc787db1ba17dd2c0ed841fd7443bc32be63b65
80e0c41b896e1eeffc594416b4c2787ed29363b6
eba744a25edcc7202068c1d46fd99d4c98c1acf2
4cf8f5f46c0f80b49a2a70854372289c3fda932b
b9b3d2d23069e021693a251a3aadd4eefc30e6ea
34260f17360f1034c562c941b0f879c2204e40b7
d5291eed1c46e1c97831e771b2975575ba268992