From: Jeff Layton <jlayton@redhat.com>
To: Trond Myklebust <trondmy@primarydata.com>
Cc: Schumaker Anna <anna.schumaker@netapp.com>,
List Linux NFS Mailing <linux-nfs@vger.kernel.org>,
Fields Bruce James <bfields@fieldses.org>
Subject: Re: [PATCH v3 2/9] nfs: check for POSIX lock capability on server even for flock locks
Date: Fri, 16 Sep 2016 17:46:02 -0400 [thread overview]
Message-ID: <1474062362.13386.13.camel@redhat.com> (raw)
In-Reply-To: <AEF00C6F-ECDD-4292-BDC2-A635D4EBB1B4@primarydata.com>
On Fri, 2016-09-16 at 21:14 +0000, Trond Myklebust wrote:
> >
> > > > On Sep 16, 2016, at 16:27, Jeff Layton <jlayton@redhat.com> wrote:
> >
> > We may end up in here with a FL_FLOCK lock request. We translate those
> > to whole-file NFSv4 locks and send them on to the server, so we need to
> > verify that the server supports them no matter what sort of lock request
> > this is.
> >
> > > > Signed-off-by: Jeff Layton <jlayton@redhat.com>
> > ---
> > fs/nfs/nfs4proc.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> > index 9d38366666f4..a0f25185c78c 100644
> > --- a/fs/nfs/nfs4proc.c
> > +++ b/fs/nfs/nfs4proc.c
> > @@ -6135,8 +6135,7 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
> > unsigned char fl_flags = request->fl_flags;
> > int status = -ENOLCK;
> >
> > > > - if ((fl_flags & FL_POSIX) &&
> > > > - !test_bit(NFS_STATE_POSIX_LOCKS, &state->flags))
> > > > + if (!test_bit(NFS_STATE_POSIX_LOCKS, &state->flags))
> > > > goto out;
> > /* Is this a delegated open? */
> > status = nfs4_set_lock_state(state, request);
> > --
> > 2.7.4
>
> The ability to support FL_FLOCK locks does not depend on the server’s
> support for POSIX locking semantics. FL_FLOCK can also use stacked
> lock semantics, precisely because they always cover the whole file.
Oh! I had always thought this flags absence basically meant "I don't
support file locking at all, so don't bother sending any LOCK
requests". Now that I look though, all RFC5661 says is:
o OPEN4_RESULT_LOCKTYPE_POSIX indicates that the server's byte-range
locking behavior supports the complete set of POSIX locking
techniques [24]. From this, the client can choose to manage byte-
range locking state in a way to handle a mismatch of byte-range
locking management.
If this flag isn't there, I guess we can't infer anything about how the
server's locks are implemented. That's just super.
So, ok. If you think this logic is more correct as-is, then I'm fine
with dropping this patch. This check gets moved in a later patch
though, so I'll need to fix that up as well.
--
Jeff Layton <jlayton@redhat.com>
next prev parent reply other threads:[~2016-09-16 21:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-16 20:27 [PATCH v3 0/9] nfs: add CB_NOTIFY_LOCK support to nfs client Jeff Layton
2016-09-16 20:27 ` [PATCH v3 1/9] nfs: eliminate pointless and confusing do_vfs_lock wrappers Jeff Layton
2016-09-16 20:27 ` [PATCH v3 2/9] nfs: check for POSIX lock capability on server even for flock locks Jeff Layton
2016-09-16 21:14 ` Trond Myklebust
2016-09-16 21:46 ` Jeff Layton [this message]
2016-09-16 21:59 ` Trond Myklebust
2016-09-16 20:27 ` [PATCH v3 3/9] nfs: use safe, interruptible sleeps when waiting to retry LOCK Jeff Layton
2016-09-16 20:27 ` [PATCH v3 4/9] nfs: add a new NFS4_OPEN_RESULT_MAY_NOTIFY_LOCK constant Jeff Layton
2016-09-16 20:27 ` [PATCH v3 5/9] nfs: track whether server sets MAY_NOTIFY_LOCK flag Jeff Layton
2016-09-16 20:27 ` [PATCH v3 6/9] nfs: add handling for CB_NOTIFY_LOCK in client Jeff Layton
2016-09-16 20:27 ` [PATCH v3 7/9] nfs: move nfs4_set_lock_state call into caller Jeff Layton
2016-09-16 20:27 ` [PATCH v3 8/9] nfs: move nfs4 lock retry attempt loop to a separate function Jeff Layton
2016-09-16 21:20 ` Trond Myklebust
2016-09-16 21:47 ` Jeff Layton
2016-09-16 20:27 ` [PATCH v3 9/9] nfs: add code to allow client to wait on lock callbacks Jeff Layton
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