Implement tell and seek for tapes

[tjwoodall]

tgtadm --op update --mode sys --name State -v offline tgt-admin -e -c /etc/tgt/targets.conf
tgtadm --op update --mode sys --name State -v ready

iscsiadm --mode node --targetname iqn.2007-03:virtual-tape:hostname --portal ${iscsi_host} --login mtx -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-3-changer load 1 0 mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst rewind mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst tell At block 1.
mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst fsf mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst tell At block 327.
mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst eod mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst tell At block 2882.
mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst bsf mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst tell At block 2880.
mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst seek 300 At block 300.
mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst bsr mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst tell At block 299.
mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst fsr mt-st -f /dev/tape/by-path/ip-fd01:8b0:bfcd:100:216:3eff:fee0:7253:3260-iscsi-iqn.2007-03:virtual-tape:hostname-lun-1-nst tell At block 300.

[tjwoodall]

This has been implemented very quickly and I'm not very familiar with how scsi works, but at least on linux appears to do the right thing.

How it was tested is documented in the commit log.

[Copilot]

Pull request overview

Adds support for tape position reporting (“tell”) and repositioning (“seek”) by wiring up the relevant SCSI opcode(s) to the SSC backing store implementation.

Changes:

• Route the SCSI SEEK_10 (0x2b) opcode to the SSC request handler.
• Extend bs_ssc to support larger block deltas (int64_t) for spacing/seeking.
• Implement basic READ_POSITION and SEEK_10 handling in the tape backing store path.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
usr/ssc.c	Enables SSC handling for the 0x2b opcode by mapping it to ssc_rw.
usr/bs_ssc.c	Implements SEEK_10 and updates READ_POSITION response behavior and block spacing types.

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[tjwoodall]

FWIW, I'm using this here: https://sourceforge.net/p/dump/code/ci/v0.4b55-wip/ for testing.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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