linux-kernel - Re: [PATCH v2] NFSv4: try lease recovery on NFS4ERR

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <CALbTx=E=pOO1wvzigRqWDZNCyksVYrhS2R6u-8OjaV9CVKHVUA@mail.gmail.com>
Date:   Mon, 27 Jan 2020 14:46:08 +0000
From:   Robert Milkowski <rmilkowski@...il.com>
To:     Trond Myklebust <trondmy@...merspace.com>
Cc:     "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "anna.schumaker@...app.com" <anna.schumaker@...app.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "chuck.lever@...cle.com" <chuck.lever@...cle.com>
Subject: Re: [PATCH v2] NFSv4: try lease recovery on NFS4ERR_EXPIRED

On Thu, 23 Jan 2020 at 19:33, Trond Myklebust <trondmy@...merspace.com> wrote:
>
> On Wed, 2020-01-22 at 14:20 +0000, Robert Milkowski wrote:
> > > -----Original Message-----
> > > From: Trond Myklebust <trondmy@...merspace.com>
> > > Sent: 17 January 2020 17:24
> > > To: linux-nfs@...r.kernel.org; rmilkowski@...il.com
> > > Cc: anna.schumaker@...app.com; linux-kernel@...r.kernel.org;
> > > chuck.lever@...cle.com
> > > Subject: Re: [PATCH v2] NFSv4: try lease recovery on
> > > NFS4ERR_EXPIRED
> > >
> > > On Fri, 2020-01-17 at 16:12 +0000, Robert Milkowski wrote:
> > > > Anyone please?
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: Robert Milkowski <rmilkowski@...il.com>
> > > > Sent: 08 January 2020 21:48
> > > > To: linux-nfs@...r.kernel.org
> > > > Cc: 'Trond Myklebust' <trondmy@...merspace.com>; 'Chuck Lever'
> > > > <chuck.lever@...cle.com>; 'Anna Schumaker' <
> > > > anna.schumaker@...app.com
> > > > > ;
> > > > linux-kernel@...r.kernel.org
> > > > Subject: [PATCH v2] NFSv4: try lease recovery on NFS4ERR_EXPIRED
> > > >
> > > > From: Robert Milkowski <rmilkowski@...il.com>
> > > >
> > > > Currently, if an nfs server returns NFS4ERR_EXPIRED to open(),
> > > > etc.
> > > > we return EIO to applications without even trying to recover.
> > > >
> > > > Fixes: 272289a3df72 ("NFSv4: nfs4_do_handle_exception() handle
> > > > revoke/expiry of a single stateid")
> > > > Signed-off-by: Robert Milkowski <rmilkowski@...il.com>
> > > > ---
> > > >  fs/nfs/nfs4proc.c | 4 ++++
> > > >  1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index
> > > > 76d3716..2478405
> > > > 100644
> > > > --- a/fs/nfs/nfs4proc.c
> > > > +++ b/fs/nfs/nfs4proc.c
> > > > @@ -481,6 +481,10 @@ static int nfs4_do_handle_exception(struct
> > > > nfs_server *server,
> > > >                                           stateid);
> > > >                           goto wait_on_recovery;
> > > >                   }
> > > > +                 if (state == NULL) {
> > > > +                         nfs4_schedule_lease_recovery(clp);
> > > > +                         goto wait_on_recovery;
> > > > +                 }
> > > >                   /* Fall through */
> > > >           case -NFS4ERR_OPENMODE:
> > > >                   if (inode) {
> > > > --
> > > > 1.8.3.1
> > > >
> > > >
> > >
> > > Does this apply to any case other than NFS4ERR_EXPIRED in the
> > > specific
> > > case of nfs4_do_open()? I can't see that it does. It looks to me as
> > > if
> > > the open recovery routines already have their own handling of this
> > > case.
> >
> > I only observed the issue with open(). After further
> > review I think you are right and it only applies to nfs4_do_open().
> >
> >
> > > If so, why not just add it as a special case in the nfs4_do_open()
> > > error
> > > handling? Otherwise this patch will end up overriding other generic
> > > cases where we have an inode, but no open state.
> > >
> >
> > Fair point.
> > So perhaps, few lines further instead of:
> >
> >                       if (inode) {
> > ...
> >                       if (state == NULL) {
> >                                       break;
> >                       }
> >
> > There should be:
> >
> >                       if (inode) {
> > ...
> >                       if (state == NULL) {
> >                               nfs4_schedule_lease_recovery(clp);
> >                               goto wait_on_recovery;
> >                       }
> >
> >
> >
> > This way we know that inode cannot be null at this point, and it's a
> > case where both inode and state are NULL.
> > This would be a little bit more general in case we reach this point.
> >
> > But if you think it is better to move it to nfs4_do_open() then I've
> > just tested the following patch:
> >
> > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> > index 76d3716..b7c4044 100644
> > --- a/fs/nfs/nfs4proc.c
> > +++ b/fs/nfs/nfs4proc.c
> > @@ -3187,6 +3187,11 @@ static struct nfs4_state *nfs4_do_open(struct
> > inode *dir,
> >                         exception.retry = 1;
> >                         continue;
> >                 }
> > +               if (status == -NFS4ERR_EXPIRED) {
> > +                       nfs4_schedule_lease_recovery(server-
> > >nfs_client);
> > +                       exception.retry = 1;
> > +                       continue;
> > +               }
> >                 if (status == -EAGAIN) {
> >                         /* We must have found a delegation */
> >                         exception.retry = 1;
> >
>
> This looks like what I'm asking for, yes. That seems like the minimal
> patch that addresses the problem you're describing.
>

Ok, will submit later today or tomorrow.
Thanks.

-- 
Robert Milkowski