From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from rcsinet15.oracle.com ([148.87.113.117]:16463 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934463Ab2DLPmS convert rfc822-to-8bit (ORCPT ); Thu, 12 Apr 2012 11:42:18 -0400 From: Chuck Lever Content-Type: text/plain; charset=us-ascii Subject: global openowner_id and lockowner_id Date: Thu, 12 Apr 2012 11:42:13 -0400 Message-Id: <58E57AF8-1636-4017-93C0-8520488ED866@oracle.com> Cc: Linux NFS Mailing List To: Trond Myklebust Mime-Version: 1.0 (Apple Message framework v1257) Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi- Changing the SETCLIENTID boot verifier so it is global for the whole client exposes a problem with how we allocate state owners. A quick umount / mount sequence destroys all state on the client. But since the client now always uses the same boot verifier and nfs_client_id4 string, the server no longer recognizes a client reboot. FOr a fresh mount, the client may perform a SETCLIENTID, but it is treated as a callback update (state is not purged) if the client's lease has not yet expired. Our state owners are generated from a pair of ida structures in the nfs_server for that mount. They always start from zero after a mount operation. Likewise, the sequence IDs for these state owners are also reset by umount / mount. Note that each mount point gets a fresh nfs_server, so these structures are not retained across umount / mount. This means umount / mount with no lease expiry starts to re-play state owners with reset sequence IDs. Servers don't really care for that behavior. I have a test case that reliably gets a BAD_SEQID error from a server after a quick umount / mount followed by a single file creation. Now that we are about to switch to using more-or-less global SETCLIENTID boot verifiers, it seems to me that we really want a global openowner_id and lockowner_id as well. The performance impact of such a change might be acceptable because we cache and reuse state owners now. Thoughts? -- Chuck Lever chuck[dot]lever[at]oracle[dot]com