Return-Path: Received: from mail-qg0-f46.google.com ([209.85.192.46]:33278 "EHLO mail-qg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752691AbcDNO3s (ORCPT ); Thu, 14 Apr 2016 10:29:48 -0400 Received: by mail-qg0-f46.google.com with SMTP id j35so63812407qge.0 for ; Thu, 14 Apr 2016 07:29:48 -0700 (PDT) Message-ID: <1460644183.2913.2.camel@poochiereds.net> Subject: Re: [PATCH 6/8] nfs: have ff_layout_get_ds_cred take a reference to the cred From: Jeff Layton To: trond.myklebust@primarydata.com Cc: linux-nfs@vger.kernel.org Date: Thu, 14 Apr 2016 10:29:43 -0400 In-Reply-To: <1460637425-1580-7-git-send-email-jeff.layton@primarydata.com> References: <1460637425-1580-1-git-send-email-jeff.layton@primarydata.com> <1460637425-1580-7-git-send-email-jeff.layton@primarydata.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, 2016-04-14 at 08:37 -0400, Jeff Layton wrote: > In later patches, we're going to want to allow the creds to be updated > when we get a new layout with updated creds. Have this function take > a reference to the cred that is later put once the call has been > dispatched. > > Also, prepare for this change by ensuring we follow RCU rules when > getting a reference to the cred as well. > > Signed-off-by: Jeff Layton > --- >  fs/nfs/flexfilelayout/flexfilelayout.c    |  9 ++++++--- >  fs/nfs/flexfilelayout/flexfilelayoutdev.c | 30 ++++++++++++++++++++++++++---- >  2 files changed, 32 insertions(+), 7 deletions(-) > > diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c > index 0cb1abd535e3..ba48fdf960e0 100644 > --- a/fs/nfs/flexfilelayout/flexfilelayout.c > +++ b/fs/nfs/flexfilelayout/flexfilelayout.c > @@ -1737,7 +1737,7 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr) >     vers == 3 ? &ff_layout_read_call_ops_v3 : >         &ff_layout_read_call_ops_v4, >     0, RPC_TASK_SOFTCONN); > - > + put_rpccred(ds_cred); >   return PNFS_ATTEMPTED; >   >  out_failed: > @@ -1798,6 +1798,7 @@ ff_layout_write_pagelist(struct nfs_pgio_header *hdr, int sync) >     vers == 3 ? &ff_layout_write_call_ops_v3 : >         &ff_layout_write_call_ops_v4, >     sync, RPC_TASK_SOFTCONN); > + put_rpccred(ds_cred); >   return PNFS_ATTEMPTED; >  } >   > @@ -1824,7 +1825,7 @@ static int ff_layout_initiate_commit(struct nfs_commit_data *data, int how) >   struct rpc_clnt *ds_clnt; >   struct rpc_cred *ds_cred; >   u32 idx; > - int vers; > + int vers, ret; >   struct nfs_fh *fh; >   >   idx = calc_ds_index_from_commit(lseg, data->ds_commit_index); > @@ -1854,10 +1855,12 @@ static int ff_layout_initiate_commit(struct nfs_commit_data *data, int how) >   if (fh) >   data->args.fh = fh; >   > - return nfs_initiate_commit(ds_clnt, data, ds->ds_clp->rpc_ops, > + ret = nfs_initiate_commit(ds_clnt, data, ds->ds_clp->rpc_ops, >      vers == 3 ? &ff_layout_commit_call_ops_v3 : >          &ff_layout_commit_call_ops_v4, >      how, RPC_TASK_SOFTCONN); > + put_rpccred(ds_cred); > + return ret; >  out_err: >   pnfs_generic_prepare_to_resend_writes(data); >   pnfs_generic_commit_release(data); > diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c > index a0dbf94d15ae..baee22929174 100644 > --- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c > +++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c > @@ -338,6 +338,25 @@ static int ff_layout_update_mirror_cred(struct nfs4_ff_layout_mirror *mirror, >   return 0; >  } >   > +static struct rpc_cred * > +ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode) > +{ > + struct rpc_cred *cred, **pcred; > + > + pcred = &mirror->cred; > + > + rcu_read_lock(); > + do { > + cred = rcu_dereference(*pcred); > + if (!cred) > + break; > + > + cred = get_rpccred_rcu(cred); > + } while(!cred); > + rcu_read_unlock(); > + return cred; > +} > + >  struct nfs_fh * >  nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx) >  { > @@ -435,10 +454,13 @@ ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx, >   struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx); >   struct rpc_cred *cred; >   > - if (mirror && mirror->cred) > - cred = mirror->cred; > - else > - cred = mdscred; > + if (mirror) { > + cred = ff_layout_get_mirror_cred(mirror, lseg->pls_range.iomode); > + if (!cred) > + cred = get_rpccred(mdscred); > + } else { > + cred = get_rpccred(mdscred); > + } >   return cred; >  } >   Oops, there's something missing in this patch. We need to fix the callers of ff_layout_get_ds_cred to check to see if they get a NULL pointer back. I'll fix that in the next version of the set. -- Jeff Layton