[LU-6990] write error: Invalid argument when trying to set nosquash_nids

• Status: Resolved
• Project: Lustre
• Affects Version/s: Lustre 2.5.4
• Fix Version/s: Lustre 2.8.0
• Type: Bug
• Priority: Minor
• Reporter: Bruno Travouillon (Inactive)
• Assignee: Emoly Liu
• Resolution: Fixed

Environment

Lustre 2.5.3.90

• Severity: 3

Description

Since our update from 2.5.3 to 2.5.3.90, we can't set the nosquash_nids parameter by writing into the procfile /proc/fs/lustre/mdt/scratch-MDT0000/nosquash_nids.

This is the method used by the shine tool for setting all the parameters.

[root@mds2 ~]# echo "192.168.101.13@tcp" > /proc/fs/lustre/mdt/scratch-MDT0000/nosquash_nids
-bash: echo: write error: Invalid argument

However, it works with 'lctl set_param' or 'echo -n'.

[root@mds2 ~]# echo -n "192.168.101.13@tcp" > /proc/fs/lustre/mdt/scratch-MDT0000/nosquash_nids
[root@mds2 ~]# cat /proc/fs/lustre/mdt/scratch-MDT0000/nosquash_nids
192.168.101.13@tcp
[root@mds2 ~]# lctl set_param mdt.scratch-MDT0000.nosquash_nids=192.168.0.13@tcp
mdt.scratch-MDT0000.nosquash_nids=192.168.0.13@tcp
[root@mds2 ~]# cat /proc/fs/lustre/mdt/scratch-MDT0000/nosquash_nids
192.168.0.13@tcp

It is related to LU-1778. The bug is in lprocfs_wr_nosquash_nids(). See lustre/obdclass/lprocfs_status.c (b2_5 branch, commit d82b4f54):

2789     if (count > 0 && kernbuf[count - 1] == '\n')
2790         kernbuf[count - 1] = '\0';

I don't understand why we need to replace \n by \0 since the nid parser seems to handle the newline.

Please let me know if you need further details.

Issue Links

• is related to: LU-1778 Root Squash is not always properly en...

Comments

[Peter Jones]

Emoly

Could you please assist with this one?

Thanks

Peter

[Emoly Liu]

Bruno, I think I know why that patch added "kernbuf[count - 1] = '\0';".
If you try to echo "NONE" to "clear" to parameter nosquash_nids against branch 2.5.3, you will see "write error: Invalid argument". Instead, that works well in 2.5.3.90.

I will post a patch to fix it.

[Gerrit Updater]

Emoly Liu ([e-mail]) uploaded a new patch: http://review.whamcloud.com/15985
Subject: LU-6990 lproc: set parameter nosquash_nids correctly
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 7d7d1e640e3b7576e88d4507e72e815ed0140981

[Gerrit Updater]

Grégoire Pichon ([e-mail]) uploaded a new patch: http://review.whamcloud.com/16034
Subject: LU-6990 lproc: set parameter nosquash_nids correctly
Project: fs/lustre-release
Branch: b2_5
Current Patch Set: 1
Commit: 84965970e51ad5b3c14d9abad3789192585be9bc

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/15985/
Subject: LU-6990 lproc: set parameter nosquash_nids correctly
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 62d3b85f7d82bf7c76a84326a22b3139678f9d97

[Joseph Gmitter (Inactive)]

Landed for 2.8.