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Subject: Re: [PATCH] NFSv4: Add lease_time and lease_expired to 'nfs4:' line
 of mountstats
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <1558127201-7481-1-git-send-email-dwysocha@redhat.com>
Date:   Mon, 20 May 2019 11:10:17 -0400
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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References: <1558127201-7481-1-git-send-email-dwysocha@redhat.com>
To:     Dave Wysochanski <dwysocha@redhat.com>
Sender: linux-nfs-owner@vger.kernel.org
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> On May 17, 2019, at 5:06 PM, Dave Wysochanski <dwysocha@redhat.com> =
wrote:
>=20
> On the NFS client there is no low-impact way to determine the nfs4
> lease time or whether the lease is expired, so add these to mountstats
> with times displayed in seconds.
>=20
> If the lease is not expired, display lease_expired=3D0. Otherwise,
> display lease_expired=3Dseconds_since_expired, similar to 'age:' line
> in mountstats.
>=20
> Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
> ---
> fs/nfs/super.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>=20
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index c27ac96..6e52f0c 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -730,6 +730,16 @@ int nfs_show_options(struct seq_file *m, struct =
dentry *root)
> EXPORT_SYMBOL_GPL(nfs_show_options);
>=20
> #if IS_ENABLED(CONFIG_NFS_V4)
> +static void show_lease(struct seq_file *m, struct nfs_server *server)
> +{
> +	struct nfs_client *clp =3D server->nfs_client;
> +	unsigned long expire;
> +
> +	seq_printf(m, ",lease_time=3D%ld", clp->cl_lease_time / HZ);
> +	expire =3D clp->cl_last_renewal + clp->cl_lease_time;
> +	seq_printf(m, ",lease_expired=3D%ld",
> +		   time_after(expire, jiffies) ?  0 : (jiffies - expire) =
/ HZ);
> +}
> #ifdef CONFIG_NFS_V4_1
> static void show_sessions(struct seq_file *m, struct nfs_server =
*server)
> {
> @@ -838,6 +848,7 @@ int nfs_show_stats(struct seq_file *m, struct =
dentry *root)
> 		seq_printf(m, ",acl=3D0x%x", nfss->acl_bitmask);
> 		show_sessions(m, nfss);
> 		show_pnfs(m, nfss);
> +		show_lease(m, nfss);
> 	}
> #endif
>=20
> --=20
> 1.8.3.1
>=20

I didn't look closely at the patch content, but IMO this is a good
observability enhancement.


--
Chuck Lever