Re: [PATCH] nfsd: don't create nfsv4recoverydir in nfsdfs when not used.

[Petr Vorel <pvorel@suse.cz>]

> On Wed, Apr 17, 2024 at 07:25:16AM +0200, Petr Vorel wrote:
> > Hi Neil, all,

> > > When CONFIG_NFSD_LEGACY_CLIENT_TRACKING is not set, the virtual file
> > >   /proc/fs/nfsd/nfsv4recoverydir
> > > is created but responds EINVAL to any access.
> > > This is not useful, is somewhat surprising, and it causes ltp to
> > > complain.

> > > The only known user of this file is in nfs-utils, which handles
> > > non-existence and read-failure equally well.  So there is nothing to
> > > gain from leaving the file present but inaccessible.

> > > So this patch removes the file when its content is not available - i.e.
> > > when that config option is not selected.

> > > Also remove the #ifdef which hides some of the enum values when
> > > CONFIG_NFSD_V$ not selection.  simple_fill_super() quietly ignores array
> > > entries that are not present, so having slots in the array that don't
> > > get used is perfectly acceptable.  So there is no value in this #ifdef.

> > > Reported-by: Petr Vorel <pvorel@suse.cz>
> > > Reviewed-by: Jeff Layton <jlayton@kernel.org>
> > > Fixes: 74fd48739d04 ("nfsd: new Kconfig option for legacy client tracking")
> > > Signed-off-by: NeilBrown <neilb@suse.de>
> > > ---
> > >  fs/nfsd/nfsctl.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)

> > > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > > index 93c87587e646..340c5d61f199 100644
> > > --- a/fs/nfsd/nfsctl.c
> > > +++ b/fs/nfsd/nfsctl.c
> > > @@ -48,12 +48,10 @@ enum {
> > >  	NFSD_MaxBlkSize,
> > >  	NFSD_MaxConnections,
> > >  	NFSD_Filecache,
> > > -#ifdef CONFIG_NFSD_V4
> > >  	NFSD_Leasetime,
> > >  	NFSD_Gracetime,
> > >  	NFSD_RecoveryDir,
> > >  	NFSD_V4EndGrace,
> > > -#endif
> > >  	NFSD_MaxReserved
> > >  };

> > > @@ -1360,7 +1358,9 @@ static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc)
> > >  #ifdef CONFIG_NFSD_V4
> > >  		[NFSD_Leasetime] = {"nfsv4leasetime", &transaction_ops, S_IWUSR|S_IRUSR},
> > >  		[NFSD_Gracetime] = {"nfsv4gracetime", &transaction_ops, S_IWUSR|S_IRUSR},
> > > +#ifdef CONFIG_NFSD_LEGACY_CLIENT_TRACKING
> > >  		[NFSD_RecoveryDir] = {"nfsv4recoverydir", &transaction_ops, S_IWUSR|S_IRUSR},
> > > +#endif

> > LGTM.

> > Reviewed-by: Petr Vorel <pvorel@suse.cz>

> > Kind regards,
> > Petr

> > >  		[NFSD_V4EndGrace] = {"v4_end_grace", &transaction_ops, S_IWUSR|S_IRUGO},
> > >  #endif
> > >  		/* last one */ {""}

> Thanks to you both! Applied to nfsd-next (for v6.10), unless you'd
> like this to go in sooner.

Also thanks to all for a very quick fix.

Kind regards,
Petr