Return-Path: Received: from mail-ig0-f170.google.com ([209.85.213.170]:34495 "EHLO mail-ig0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753082AbbJMQYN (ORCPT ); Tue, 13 Oct 2015 12:24:13 -0400 Received: by igbni9 with SMTP id ni9so61042627igb.1 for ; Tue, 13 Oct 2015 09:24:12 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: Date: Tue, 13 Oct 2015 12:24:12 -0400 Message-ID: Subject: Re: [PATCH 1/1] Adding issync field to delegreturn_exit tracepoint From: Olga Kornievskaia To: Trond Myklebust Cc: linux-nfs Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, Oct 13, 2015 at 10:13 AM, Olga Kornievskaia wrote: > On Tue, Oct 13, 2015 at 9:27 AM, Trond Myklebust > wrote: >> On Tue, Oct 13, 2015 at 8:26 AM, Olga Kornievskaia wrote: >>> >>> On Mon, Oct 12, 2015 at 11:47 PM, Trond Myklebust >>> wrote: >>> > On Mon, Oct 12, 2015 at 5:55 PM, Olga Kornievskaia wrote: >>> >> It'll be nice to know when we return delegations synchronously or not. >>> > >>> > Why? This patch forces us to carry an otherwise completely unnecessary >>> > parameter, so at the very minimum we should have a discussion of what >>> > the real use cases are. >>> >>> I used it to diagnose the race of open and delegreturn. If it's kept >> >> How were you using it? > > I added two more traces points in the beginning of delegreturn and in > nfs4_do_open before sending the rpc. I can see that a given file > handle: > -- delegreturn prepare tracepoint is happening, > -- then the tracepoint of before sending the open is logged, > -- then delegreturn prepare is logged again, > -- then tracepoint for nfs4_open_file which is after receiving reply > to the open from the server > -- then delegreturn_exit tracepoint > > kworker/1:0H-14168 [001] .... 576.571636: > nfs4_delegreturn_prepare: error=0 (OK) dev=00:2a fhandle=0x84792ca9 > issync=0 > > hammer-13955 [000] .... 576.942632: nfs4_open_file_begin: > flags=32768 (0x8000) fmode=READ|0x801c fileid=00:2a:0 > fhandle=0x00000000 name=00:2a:904/000002CB.ham > > hammer-13955 [001] .... 577.043084: nfs4_open_file: > error=0 (OK) flags=32768 (0x8000) fmode=READ|0x801c fileid=00:2a:7708 > fhandle=0x84792ca9 name=00:2a:904/000002CB.ham > > kworker/0:1H-431 [000] .... 577.064013: > nfs4_delegreturn_prepare: error=0 (OK) dev=00:2a fhandle=0x84792ca9 > issync=0 > > kworker/0:1H-431 [000] .... 577.101076: nfs4_delegreturn_exit: > error=0 (OK) dev=00:2a fhandle=0x84792ca9 > > kworker/0:1H-431 [000] .... 577.113021: nfs4_read: > error=-10025 (BAD_STATEID) fileid=00:2a:7708 fhandle=0x84792ca9 > offset=0 count=64 > > >> >>> that some delegreturns are synchronous and others are not I think the >>> information is useful. >> >> The only difference between synchronous and asynchronous in this case >> is whether or not the process that launched the delegreturn actually >> waits for it to complete; a signal could easily prevent it from doing >> so without interrupting the delegreturn call itself. >> IOW: for complete information when debugging races here, you really >> need to examine the return value from the wait call. >> >>> Speaking of there is a race between state manager thread returning >>> used delegations and new open. Previously I thought it was evict >>> inode... >> >> Is this with commit 5e99b532bb95 ("nfs4: reset states to use >> open_stateid when returning delegation voluntarily") applied? > > No I have not. I will try that. Thanks. This patch does not help. The race is still present.