bugfix: cannot mount LTFS tapes under Rocky Linux with lin_tape driver

[richard42]

Summary of changes

This pull request includes one bugfix.

Description

This is a very simple fix. The bug is pretty obvious. It causes all LTFS tape mounts to fail on our new Rocky Linux 8 machine using the lin_tape driver, with a log output like this:

c134 LTFS17089I Distribution: Rocky Linux release 8.7 (Green Obsidian).
c134 LTFS17089I Distribution: Rocky Linux release 8.7 (Green Obsidian).
c134 LTFS17089I Distribution: Rocky Linux release 8.7 (Green Obsidian).
c134 LTFS14064I Sync type is "unmount".
c134 LTFS17085I Plugin: Loading "lin_tape" tape backend.
c134 LTFS17085I Plugin: Loading "unified" iosched backend.
c134 LTFS14095I Set the tape device write-anywhere mode to avoid cartridge ejection.
c134 LTFS30416I lin_tape version is 3.0.64.
c134 LTFS30423I Opening a device through ibmtape driver (/dev/IBMtape1n).
c134 LTFS30428I Product ID is 'ULTRIUM-HH8     '.
c134 LTFS30429I Vendor ID is IBM     .
c134 LTFS30432I Firmware revision is P381.
c134 LTFS30433I Drive serial is 1097003951.
c134 LTFS17160I Maximum device block size is 1048576.
c134 LTFS11330I Loading cartridge.
c134 LTFS30472I Logical block protection is disabled.
c134 LTFS30457I Cannot get remaining capacity: get log page 0x17 failed (450).
c134 LTFS11332I Load successful.
c134 LTFS30457I Cannot get remaining capacity: get log page 0x17 failed (450).
c134 LTFS17157I Changing the drive setting to write-anywhere mode.
c134 LTFS11005I Mounting the volume.
c134 LTFS30472I Logical block protection is disabled.
c134 LTFS30457I Cannot get remaining capacity: get log page 0x17 failed (450).
c134 LTFS30457I Cannot get remaining capacity: get log page 0x17 failed (450).
c134 LTFS17168E Cannot read volume: medium is not partitioned.
c134 LTFS14013E Cannot mount the volume.
c134 LTFS30472I Logical block protection is disabled.

You can see the result of the bug - the lin_tape_ibmtape_remaining_capacity() function thinks that the lin_tape_ibmtape_logsense() failed because it returned the log page size (450) instead of the error code.

Type of change

Please delete items that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have confirmed my fix is effective or that my feature works

[piste-jp]

It looks this fix is not correct.

We changed the prototype of logsense method and it shall return the response length of log page.

The point you should take care is line 2266, the condition shall be if (rc < 0). (See same portion in sg_tape.c)
https://github.com/LinearTapeFileSystem/ltfs/blob/178a782ffed151ff890b41cfdf56f7b8343d3c45/src/tape_drivers/linux/lin_tape/lin_tape_ibmtape.c#L2265-2270

You can see the explanation of the prototype of logsense prototype.

https://github.com/LinearTapeFileSystem/ltfs/blob/178a782ffed151ff890b41cfdf56f7b8343d3c45/src/libltfs/tape_ops.h#L592-604

[richard42]

okay, thanks for reviewing this. I have pushed changes to the pull request which should fix all of the functions in lin_tape_ibmtape.c which call lin_tape_ibmtape_logsense() with the new return code semantic.

[piste-jp]

Hi, Thank you for your additional commit!

It is almost there. I just have one comment. Please let me know if you have opinion against your comment.

[richard42]

Okay I just pushed another commit to return "rc" instead of -1.

[piste-jp]

Thank you very much for your great contribution!

[piste-jp]

@juliocelon

Please push the Squash and merge button and merge this to the master branch.