From: Jeff Layton <jlayton@kernel.org>
To: Alexander Aring <aahringo@redhat.com>
Cc: linux-nfs@vger.kernel.org, cluster-devel@redhat.com,
ocfs2-devel@lists.linux.dev, linux-fsdevel@vger.kernel.org,
teigland@redhat.com, rpeterso@redhat.com, agruenba@redhat.com,
trond.myklebust@hammerspace.com, anna@kernel.org,
chuck.lever@oracle.com
Subject: Re: [PATCH 6/7] dlm: use FL_SLEEP to determine blocking vs non-blocking
Date: Wed, 30 Aug 2023 09:46:26 -0400 [thread overview]
Message-ID: <35f7ca6a61b0e90a537badf2bea056b76b75cb12.camel@kernel.org> (raw)
In-Reply-To: <CAK-6q+i+j1TUmWGH+fdYHix5TwujH8_kuR5ayUv9h6Ah8OQecQ@mail.gmail.com>
On Wed, 2023-08-30 at 08:38 -0400, Alexander Aring wrote:
> Hi,
>
> On Fri, Aug 25, 2023 at 2:18 PM Jeff Layton <jlayton@kernel.org> wrote:
> >
> > On Wed, 2023-08-23 at 17:33 -0400, Alexander Aring wrote:
> > > This patch uses the FL_SLEEP flag in struct file_lock to determine if
> > > the lock request is a blocking or non-blocking request. Before dlm was
> > > using IS_SETLKW() was being used which is not usable for lock requests
> > > coming from lockd when EXPORT_OP_SAFE_ASYNC_LOCK inside the export flags
> > > is set.
> > >
> > > Signed-off-by: Alexander Aring <aahringo@redhat.com>
> > > ---
> > > fs/dlm/plock.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c
> > > index 0094fa4004cc..0c6ed5eeb840 100644
> > > --- a/fs/dlm/plock.c
> > > +++ b/fs/dlm/plock.c
> > > @@ -140,7 +140,7 @@ int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
> > > op->info.optype = DLM_PLOCK_OP_LOCK;
> > > op->info.pid = fl->fl_pid;
> > > op->info.ex = (fl->fl_type == F_WRLCK);
> > > - op->info.wait = IS_SETLKW(cmd);
> > > + op->info.wait = !!(fl->fl_flags & FL_SLEEP);
> > > op->info.fsid = ls->ls_global_id;
> > > op->info.number = number;
> > > op->info.start = fl->fl_start;
> >
> > Not sure you really need the !!, but ok...
> >
>
> The wait is a byte value and FL_SLEEP doesn't fit into it, I already
> run into problems with it. I don't think somebody does a if (foo->wait
> == 1) but it should be set to 1 or 0.
>
AIUI, any halfway decent compiler should take the result of the &, and
implicitly cast that properly to bool. Basically, any value other than 0
should be true.
If the compiler just blindly casts the lowest byte though, then you do
need the double-negative.
> An alternative would be: ((fl->fl_flags & FL_SLEEP) == FL_SLEEP). I am
> not sure what the coding style says here. I think it's more important
> what the C standard says about !!(condition), but there are other
> users of this in the Linux kernel. :-/
I don't care too much either way, but my understanding was that you
don't need to do the !! trick in most cases with modern compilers.
--
Jeff Layton <jlayton@kernel.org>
next prev parent reply other threads:[~2023-08-30 13:46 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-23 21:33 [PATCH 0/7] lockd: dlm: async lock request changes Alexander Aring
2023-08-23 21:33 ` [PATCH 1/7] lockd: introduce safe async lock op Alexander Aring
2023-08-25 17:21 ` Chuck Lever
2023-08-30 12:32 ` Alexander Aring
2023-08-30 13:45 ` Chuck Lever
2023-08-25 18:14 ` Jeff Layton
2023-08-23 21:33 ` [PATCH 2/7] lockd: don't call vfs_lock_file() for pending requests Alexander Aring
2023-08-25 18:10 ` Jeff Layton
2023-08-30 12:15 ` Alexander Aring
2023-08-23 21:33 ` [PATCH 3/7] lockd: fix race in async lock request handling Alexander Aring
2023-08-25 17:35 ` Chuck Lever
2023-08-25 18:16 ` Jeff Layton
2023-08-23 21:33 ` [PATCH 4/7] lockd: add doc to enable EXPORT_OP_SAFE_ASYNC_LOCK Alexander Aring
2023-08-25 18:17 ` Jeff Layton
2023-08-23 21:33 ` [PATCH 5/7] dlm: use fl_owner from lockd Alexander Aring
2023-08-23 21:33 ` [PATCH 6/7] dlm: use FL_SLEEP to determine blocking vs non-blocking Alexander Aring
2023-08-25 18:18 ` Jeff Layton
2023-08-30 12:38 ` Alexander Aring
2023-08-30 13:46 ` Jeff Layton [this message]
2023-08-23 21:33 ` [PATCH 7/7] dlm: implement EXPORT_OP_SAFE_ASYNC_LOCK Alexander Aring
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