From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47921C433ED for ; Thu, 20 May 2021 20:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B44361355 for ; Thu, 20 May 2021 20:47:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229556AbhETUsn (ORCPT ); Thu, 20 May 2021 16:48:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbhETUsm (ORCPT ); Thu, 20 May 2021 16:48:42 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B55EC061574 for ; Thu, 20 May 2021 13:47:20 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id DC28A64B9; Thu, 20 May 2021 16:47:19 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org DC28A64B9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1621543639; bh=/b4c7sRN8d6Ihrd6N+FuW1cnNOjt1+j5HMW7YDhcQh4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=e0B06wm0b2jdSsJP8BxZjAm8Wb5to7Hd5FmUhvcqkb1kFAMKTFwLjrZhqX2LWFO1z gZ3Wzsb4EaD2LKSVZQLmYAeW1NbP0zsKnFQ8e0rngQNEYIpdIjv3oF8HCBYzGd1gCK IUCT5xBrVu8Va+lAqCc3/dljtGLNlwGpmQV/2VN8= Date: Thu, 20 May 2021 16:47:19 -0400 From: "bfields@fieldses.org" To: Trond Myklebust Cc: "linux-nfs@vger.kernel.org" Subject: Re: [PATCH 1/4] NFSv4: Fix delegation return in cases where we have to retry Message-ID: <20210520204719.GB10415@fieldses.org> References: <20210520163902.215745-1-trondmy@kernel.org> <20210520163902.215745-2-trondmy@kernel.org> <20210520182901.GA8759@fieldses.org> <2b24ca81205cca400910bbbdc29d54aafccefe00.camel@hammerspace.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2b24ca81205cca400910bbbdc29d54aafccefe00.camel@hammerspace.com> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Thu, May 20, 2021 at 07:08:24PM +0000, Trond Myklebust wrote: > On Thu, 2021-05-20 at 14:29 -0400, J. Bruce Fields wrote: > > On Thu, May 20, 2021 at 12:38:59PM -0400, trondmy@kernel.org wrote: > > > From: Trond Myklebust > > > > > > If we're unable to immediately recover all locks because the server > > > is > > > unable to immediately service our reclaim calls, then we want to > > > retry > > > after we've finished servicing all the other asynchronous > > > delegation > > > returns on our queue. > > > > So, there's a situation where the server can't service a reclaim > > until > > some other delegation is returned?  I'm not seeing how that happens. > > > > I can and I do... pNFS can be complicated... I don't doubt you, but does everyone get this but me? Is it too complicated to explain? --b. > > > --b. > > > > > > > > Signed-off-by: Trond Myklebust > > > --- > > >  fs/nfs/delegation.c | 71 +++++++++++++++++++++++++++++++++++------ > > > ---- > > >  fs/nfs/delegation.h |  1 + > > >  fs/nfs/nfs4_fs.h    |  1 + > > >  3 files changed, 58 insertions(+), 15 deletions(-) > > > > > > diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c > > > index e6ec6f09ac6e..7c45ac3c3b0b 100644 > > > --- a/fs/nfs/delegation.c > > > +++ b/fs/nfs/delegation.c > > > @@ -75,6 +75,13 @@ void nfs_mark_delegation_referenced(struct > > > nfs_delegation *delegation) > > >         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags); > > >  } > > >   > > > +static void nfs_mark_return_delegation(struct nfs_server *server, > > > +                                      struct nfs_delegation > > > *delegation) > > > +{ > > > +       set_bit(NFS_DELEGATION_RETURN, &delegation->flags); > > > +       set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client- > > > >cl_state); > > > +} > > > + > > >  static bool > > >  nfs4_is_valid_delegation(const struct nfs_delegation *delegation, > > >                 fmode_t flags) > > > @@ -293,6 +300,7 @@ nfs_start_delegation_return_locked(struct > > > nfs_inode *nfsi) > > >                 goto out; > > >         spin_lock(&delegation->lock); > > >         if (!test_and_set_bit(NFS_DELEGATION_RETURNING, > > > &delegation->flags)) { > > > +               clear_bit(NFS_DELEGATION_RETURN_DELAYED, > > > &delegation->flags); > > >                 /* Refcount matched in nfs_end_delegation_return() > > > */ > > >                 ret = nfs_get_delegation(delegation); > > >         } > > > @@ -314,16 +322,17 @@ nfs_start_delegation_return(struct nfs_inode > > > *nfsi) > > >         return delegation; > > >  } > > >   > > > -static void > > > -nfs_abort_delegation_return(struct nfs_delegation *delegation, > > > -               struct nfs_client *clp) > > > +static void nfs_abort_delegation_return(struct nfs_delegation > > > *delegation, > > > +                                       struct nfs_client *clp, int > > > err) > > >  { > > >   > > >         spin_lock(&delegation->lock); > > >         clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags); > > > -       set_bit(NFS_DELEGATION_RETURN, &delegation->flags); > > > +       if (err == -EAGAIN) { > > > +               set_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation- > > > >flags); > > > +               set_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp- > > > >cl_state); > > > +       } > > >         spin_unlock(&delegation->lock); > > > -       set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state); > > >  } > > >   > > >  static struct nfs_delegation * > > > @@ -539,7 +548,7 @@ static int nfs_end_delegation_return(struct > > > inode *inode, struct nfs_delegation > > >         } while (err == 0); > > >   > > >         if (err) { > > > -               nfs_abort_delegation_return(delegation, clp); > > > +               nfs_abort_delegation_return(delegation, clp, err); > > >                 goto out; > > >         } > > >   > > > @@ -568,6 +577,7 @@ static bool nfs_delegation_need_return(struct > > > nfs_delegation *delegation) > > >         if (ret) > > >                 clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, > > > &delegation->flags); > > >         if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) > > > || > > > +           test_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation- > > > >flags) || > > >             test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) > > >                 ret = false; > > >   > > > @@ -647,6 +657,38 @@ static int > > > nfs_server_return_marked_delegations(struct nfs_server *server, > > >         return err; > > >  } > > >   > > > +static bool nfs_server_clear_delayed_delegations(struct nfs_server > > > *server) > > > +{ > > > +       struct nfs_delegation *d; > > > +       bool ret = false; > > > + > > > +       list_for_each_entry_rcu (d, &server->delegations, > > > super_list) { > > > +               if (!test_bit(NFS_DELEGATION_RETURN_DELAYED, &d- > > > >flags)) > > > +                       continue; > > > +               nfs_mark_return_delegation(server, d); > > > +               clear_bit(NFS_DELEGATION_RETURN_DELAYED, &d- > > > >flags); > > > +               ret = true; > > > +       } > > > +       return ret; > > > +} > > > + > > > +static bool nfs_client_clear_delayed_delegations(struct nfs_client > > > *clp) > > > +{ > > > +       struct nfs_server *server; > > > +       bool ret = false; > > > + > > > +       if (!test_and_clear_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp- > > > >cl_state)) > > > +               goto out; > > > +       rcu_read_lock(); > > > +       list_for_each_entry_rcu (server, &clp->cl_superblocks, > > > client_link) { > > > +               if (nfs_server_clear_delayed_delegations(server)) > > > +                       ret = true; > > > +       } > > > +       rcu_read_unlock(); > > > +out: > > > +       return ret; > > > +} > > > + > > >  /** > > >   * nfs_client_return_marked_delegations - return previously marked > > > delegations > > >   * @clp: nfs_client to process > > > @@ -659,8 +701,14 @@ static int > > > nfs_server_return_marked_delegations(struct nfs_server *server, > > >   */ > > >  int nfs_client_return_marked_delegations(struct nfs_client *clp) > > >  { > > > -       return nfs_client_for_each_server(clp, > > > -                       nfs_server_return_marked_delegations, > > > NULL); > > > +       int err = nfs_client_for_each_server( > > > +               clp, nfs_server_return_marked_delegations, NULL); > > > +       if (err) > > > +               return err; > > > +       /* If a return was delayed, sleep to prevent hard looping > > > */ > > > +       if (nfs_client_clear_delayed_delegations(clp)) > > > +               ssleep(1); > > > +       return 0; > > >  } > > >   > > >  /** > > > @@ -775,13 +823,6 @@ static void > > > nfs_mark_return_if_closed_delegation(struct nfs_server *server, > > >         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client- > > > >cl_state); > > >  } > > >   > > > -static void nfs_mark_return_delegation(struct nfs_server *server, > > > -               struct nfs_delegation *delegation) > > > -{ > > > -       set_bit(NFS_DELEGATION_RETURN, &delegation->flags); > > > -       set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client- > > > >cl_state); > > > -} > > > - > > >  static bool nfs_server_mark_return_all_delegations(struct > > > nfs_server *server) > > >  { > > >         struct nfs_delegation *delegation; > > > diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h > > > index c19b4fd20781..1c378992b7c0 100644 > > > --- a/fs/nfs/delegation.h > > > +++ b/fs/nfs/delegation.h > > > @@ -36,6 +36,7 @@ enum { > > >         NFS_DELEGATION_REVOKED, > > >         NFS_DELEGATION_TEST_EXPIRED, > > >         NFS_DELEGATION_INODE_FREEING, > > > +       NFS_DELEGATION_RETURN_DELAYED, > > >  }; > > >   > > >  int nfs_inode_set_delegation(struct inode *inode, const struct > > > cred *cred, > > > diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h > > > index 065cb04222a1..4c44322c2643 100644 > > > --- a/fs/nfs/nfs4_fs.h > > > +++ b/fs/nfs/nfs4_fs.h > > > @@ -45,6 +45,7 @@ enum nfs4_client_state { > > >         NFS4CLNT_RECALL_RUNNING, > > >         NFS4CLNT_RECALL_ANY_LAYOUT_READ, > > >         NFS4CLNT_RECALL_ANY_LAYOUT_RW, > > > +       NFS4CLNT_DELEGRETURN_DELAYED, > > >  }; > > >   > > >  #define NFS4_RENEW_TIMEOUT             0x01 > > > -- > > > 2.31.1 > > -- > Trond Myklebust > Linux NFS client maintainer, Hammerspace > trond.myklebust@hammerspace.com > >