[LU-12244] lfs check subcommand no longer works as non-root user

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Affects Version/s: Lustre 2.10.6
• Labels: llnl
• Environment: Client/Server: lustre-2.10.6_2.chaos-1.ch6.x86_64 ; kernel: 3.10.0-957.5.1.3chaos.ch6.x86_64
• Severity: 3
• Assignee: Peter Jones
• Reporter: Cameron Harr

Description

With the Lustre 2.10 client, non-root users appear to no longer be able to run "lfs check <servers|osts|mds>". Strace of the command shows a "Permission denied" error accessing /sys/kernel/debug/lustre/devices, resulting in the following error at runtime: error: check: mds status failed

Our Operations staff w/o root access needs "lfs check ..." functionality to monitor and fix file system issues, so fixing this issue would helpful for us.

statfs("/sys/kernel/debug/", {f_type=DEBUGFS_MAGIC, f_bsize=4096, f_blocks=0, f_bfree=0, f_bavail=0, f_files=0, f_ffree=0, f_fsid={0, 0}, f_namelen=255, f_frsize=4096, f_flags=ST_VALID|ST_RELATIME}) = 0
stat("/sys/fs/lnet/devices", 0x7fffffff8760) = -1 ENOENT (No such file or directory)
stat("/sys/fs/lustre/devices", 0x7fffffff8760) = -1 ENOENT (No such file or directory)
stat("/sys/kernel/debug/lnet/devices", 0x7fffffff8740) = -1 EACCES (Permission denied)
stat("/sys/kernel/debug/lustre/devices", 0x7fffffff8740) = -1 EACCES (Permission denied)
stat("/proc/fs/lnet/devices", 0x7fffffff8760) = -1 ENOENT (No such file or directory)
stat("/proc/fs/lustre/devices", 0x7fffffff8760) = -1 ENOENT (No such file or directory)
stat("/proc/sys/lnet/devices", 0x7fffffff8760) = -1 ENOENT (No such file or directory)
stat("/proc/sys/lustre/devices", 0x7fffffff8760) = -1 ENOENT (No such file or directory)
write(2, "error: check: mds status failed\n", 32error: check: mds status failed
) = 32
exit_group(2)                           = ?
+++ exited with 2 +++

Issue Links

• is related to: LU-11850 Relocating /proc/fs/lustre/ost to /sys/kernel/debug/lustre/ost prevents non-root access
• is related to: LU-8066 Move lustre procfs handling to sysfs and debugfs.

Comments

[Cameron Harr]

... And I had searched only on 2.10. Thanks.

[James A Simmons]

LU-11850 only impacts 2.12 LTS users. 

[Cameron Harr]

Thank you both. My search for related tickets missed LU-11850, which is very similar.

Sparing Redhat from some blame, we only recently started rolling out 2.10 clients (from 2.8) so this is only affecting us now.

[Andreas Dilger]

I've cherry-picked the patch to b2_10:

https://review.whamcloud.com/34782

[Andreas Dilger]

The move of the /proc/fs/lustre/devices file from procfs to debugfs was done as part of patch https://review.whamcloud.com/23428 "LU-8066 obdclass: move lustre sysctl to sysfs" landed for 2.9.56, so it has been in all 2.10 releases.

I suspect the reason it is a problem now is that RedHat has backported a change from newer kernels to their kernel that makes debugfs root-only.

[James A Simmons]

We have fixes for that which landed to newer lustre versions. You need patch:

https://review.whamcloud.com/33799