[LU-1673] Locking issue with 1.8.x clients talking to 2.2 Servers

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Affects Version/s: Lustre 2.2.0
• Labels: client locking server
• Environment: client 1.8.x server 2.2
• Severity: 2

Epic

client locking server

• Assignee: Yang Sheng
• Reporter: ETHz Support (Inactive)

Description

We noticed that clients running Lustre 1.8.x seem to have trouble locking files hosted on 2.2 Servers.

Comments

[Peter Jones]

Yangsheng is working on creating patched RPMs

[ETHz Support (Inactive)]

Could you provide us patched rpms?

Thanks in advance

[Oleg Drokin]

flocks are only taken on MDS, so updating just MDS is fine.

[ETHz Support (Inactive)]

Would we have to patch only the MDS or also all OSTs?
Upgrading all OSTs requires quite some downtime :-/

Could you provide us the rpms patched for 2.2 servers?

Thanks in advance.

[Oleg Drokin]

Hm, I was under impression that the fix for this landed in time for 2.2, but alas.

The patch that fixes this could be found here: http://review.whamcloud.com/#change,2193

[Peter Jones]

Oleg is look into this one

[ETHz Support (Inactive)]

This simple C code is enough to reproduce the problem:

$ cat test.c
#include <sys/file.h>
#include <errno.h>

int main() {
int fd;
int r;

printf("-- starting --\n");

fd = open("locktest.txt", O_RDWR);
if(fd < 0)

{ printf("open failed\n"); exit(1); }

r = flock(fd, LOCK_EX|LOCK_NB);
if(r == -1)

{ printf("Error in flock: %d\n", errno); exit(1); }

flock(fd, LOCK_UN);
close(fd);
return 0;
}

Creating 'locktest.txt' on a 2.2 server (while using the 1.8) client + starting the application ~2-3 times causes flock() to fail:

rm -f locktest.txt ; touch locktest.txt ; for x in

{0..5}

; do ./a.out ; sleep 1 ; done
– starting –
-- starting –
Error in flock: 11
– starting –
Error in flock: 11
– starting –
Error in flock: 11
– starting –
Error in flock: 11
– starting –
Error in flock: 11

The 'EAGAIN' error will be gone after a couple of seconds (i suppose that's when the leaked lock timed out).

Note that exactly the same code works fine on:

• A 1.8.x client talking to 1.8.x servers
• A 2.2 client talking to 2.2 servers

The 1.8 client in my test is running:
$ cat /proc/fs/lustre/version
lustre: 1.8.7.80
kernel: patchless_client
build: ../lustre/scripts--PRISTINE-2.6.18-308.1.1.el5

The 2.2 servers are on:

bash-4.1$ uname -r
2.6.32-220.4.2.el6_lustre.x86_64

bash-4.1$ cat /proc/fs/lustre/version
lustre: 2.2.0
kernel: patchless_client
build: 2.2.0-RC2--PRISTINE-2.6.32-220.4.2.el6_lustre.x86_64

The filesystem is mounted via:
$ grep _xl /etc/fstab
10.201.62.13@o2ib:10.201.62.14@o2ib:/nero /cluster/scratch_xl lustre flock,_netdev 0 0