[LU-9067] lctl dl command fails on el6

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.10.0
• Severity: 3
• Assignee: James A Simmons
• Reporter: Bob Glossman (Inactive)

Description

This problem has been seen on el6.8. The command 'lctl dl' fails.

This appears to be due to the "devices" entry used by the command being missing.
In older e6.x versions it is /proc/fs/lustre/devices.
In some newer distros, for example el7.3, it is /sys/kernel/debug/lustre/devices.

There isn't any lustre "devices" file anywhere in /proc or /sys. Don't know exactly why not.

Issue Links

• is related to: LU-8066 Move lustre procfs handling to sysfs and debugfs.

Comments

[James A Simmons]

Patch has landed

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/25182/
Subject: LU-9067 utils: ensure debugfs is mounted
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: e53bbbc510f9ac96f2556131c405c7e5c749cc27

[James A Simmons]

Should be landing very soon

[Bob Glossman (Inactive)]

more on master:
https://testing.hpdd.intel.com/test_sets/ad39ea70-fc88-11e6-b542-5254006e85c2
https://testing.hpdd.intel.com/test_sets/06f1473c-fd17-11e6-a77a-5254006e85c2

I think this problem is blocking all el6 tests on master atm.
The only reason it isn't causing more fallout is the fact that el7 is the default test distro for master. Not a problem on el7.

[James A Simmons]

I updated the patch so if mtab is a real file it will add a debugfs entry.

[Bob Glossman (Inactive)]

yes, el6 is old school. Still maintains mtab as a real, separate file. Not linked to /proc/mounts. All distros used to be that way.

[James A Simmons]

Newer distros symlink mtab to /proc/mounts but that is not the case for RHEL6. Luckly their is a function to add entries to mtab.

[Bob Glossman (Inactive)]

James,
Back to my original criticism of your original fix on your latest rev:

The patch seems to work, but by calling mount() directly debugfs isn't added to mtab Therefore it doesn't show up as visibly mounted in the 'mount' command. It does appear in /proc/mounts.

I see nothing that restricts it to el6 or happening only at module load time, as mentioned in your comment (above).

[Bob Glossman (Inactive)]

not an issue on SLES11 or SLES12. debugfs mounted there. el6 is the only context I can find where it's not mounted by default.

In sles11 it's mounted via fstab.
In sles12 it's mounted via systemd, just like el7.

[James A Simmons]

Does SLES11 have this issue also? I see my Cray system its mounted but I wonder in general. I have an idea!!! What about calling sys_mount when the libcfs modules loads? We can make it conditional only for RHEL6 and that way it only would happen at module load. Does that sound reasonable?