Hi Cephers,
We encountered a problem when using CephFS + Samba, which fails the reconnection phase of MDS respawn.
Reproduce steps:
1. kernel mount CephFS to a Samba server
2. re-export the mount point by Samba
3. connect to Samba server from a Windows 7 client, and copy a large file (4GB) to the shared directory
4. during copy process, restart the active (and the only one) MDS
5. MDS then gives up reconnecting to the kernel client after timeout
As a result, all client requests will hang for like forever :<
I did a few extra tests, which proved that this issue will not occur when using kernel client directly nor via
NFS re-export. From the syslog I found the following error (with dynamic debug enabled):
Sep 6 20:34:41 trusty81 kernel: [465858.676638] ceph: mds0 caps stale
Sep 6 20:34:41 trusty81 kernel: [465859.123780] ceph: mds0 reconnect start
Sep 6 20:34:41 trusty81 kernel: [465859.125113] ceph: session ffff8801121f7000 state reconnecting
Sep 6 20:34:41 trusty81 kernel: [465859.126306] ceph: counted 0 flock locks and 0 fcntl locks
Sep 6 20:34:41 trusty81 kernel: [465859.126349] ceph: encoding 0 flock and 0 fcntl locksceph: counted 1 flock locks and 0 fcntl locks
Sep 6 20:34:41 trusty81 kernel: [465859.128575] ceph: encoding 1 flock and 0 fcntl locksceph: Have unknown lock type 32
Sep 6 20:34:41 trusty81 kernel: [465859.129795] ceph: error -22 preparing reconnect for mds0
It looks like the CIFS workload generates an invalid lock type, but I’m not sure about this. Any suggestions?
PS:
1. Samba version: 4.3.9, kernel version: 3.19.0-25-generic
2. I also tried a newer kernel (4.4.0-31-generic), but with no luck
Feb 11 11:41:52 xerus101 kernel: [ 836.960441] ceph: mds0 reconnect start
Feb 11 11:41:52 xerus101 kernel: [ 836.960494] ceph: error -22 preparing reconnect for mds0
Regards,
---Sandy
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