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Message-ID: <4659cdbbe84d40e98cb5926885189d08c94cb2f4.camel@kernel.org>
Subject: Re: [PATCH v8 2/6] NFSD: convert write_threads to netlink command
From: Jeff Layton <jlayton@kernel.org>
To: NeilBrown <neilb@suse.de>, Lorenzo Bianconi <lorenzo@kernel.org>
Cc: linux-nfs@vger.kernel.org, lorenzo.bianconi@redhat.com, 
	chuck.lever@oracle.com, netdev@vger.kernel.org, kuba@kernel.org
Date: Wed, 17 Apr 2024 09:04:01 -0400
In-Reply-To: <4571e67647036cbd5833637aca07b6c4cc0e5e67.camel@kernel.org>
References: <cover.1713209938.git.lorenzo@kernel.org>
	 , <4ff777ebb8652e31709bd91c3af50693edf86a26.1713209938.git.lorenzo@kernel.org>
	 <171330451967.17212.2388131327788656190@noble.neil.brown.name>
	 <4571e67647036cbd5833637aca07b6c4cc0e5e67.camel@kernel.org>
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On Tue, 2024-04-16 at 18:39 -0400, Jeff Layton wrote:
> On Wed, 2024-04-17 at 07:55 +1000, NeilBrown wrote:
> > On Tue, 16 Apr 2024, Lorenzo Bianconi wrote:
> > > Introduce write_threads netlink command similar to the one available
> > > through the procfs.
> >=20
> > I think this should support write_pool_threads too.
> > i.e.  the number of threads should be an array.  If it is a singleton,
> > the it does write_threads.   If larger it does write_pool_threads.
> > I don't think we want to add a separate command later for pool_threads.
> >=20
> > NeilBrown
> >=20
>=20
> That is a very good point. We'll take a closer look at the current
> pool_threads interface and see how we can extend this one to cover that
> use case. Making it an array sounds reasonable at first blush.
>=20

Lorenzo and I had a look this morning:

Doing this properly is going to take some refactoring, I think. The
existing pool code has a weird restriction where you can't bring the
server up and down exclusively using the pool_threads interface. There
are no userland tools for it either, so it's out of scope since it's not
really part of the how rpc.nfsd works today.

I think the way forward here is to go ahead and make this interface use
an array of integers (like Neil suggests), but for now if someone tries
to send down a THREAD_SET operation and the pool_mode isn't global,
we'll just return an error of some sort (EINVAL, EOPNOTSUPP, ?).

One the new interfaces are in I'll take a look at adding support for
managing other pool_modes properly.

Does that sound ok?


> >=20
> > >=20
> > > Tested-by: Jeff Layton <jlayton@kernel.org>
> > > Reviewed-by: Jeff Layton <jlayton@kernel.org>
> > > Co-developed-by: Jeff Layton <jlayton@kernel.org>
> > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > > ---
> > >  Documentation/netlink/specs/nfsd.yaml |  33 ++++++++
> > >  fs/nfsd/netlink.c                     |  19 +++++
> > >  fs/nfsd/netlink.h                     |   2 +
> > >  fs/nfsd/nfsctl.c                      | 104 ++++++++++++++++++++++++=
++
> > >  include/uapi/linux/nfsd_netlink.h     |  11 +++
> > >  5 files changed, 169 insertions(+)
> > >=20
> > > diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/ne=
tlink/specs/nfsd.yaml
> > > index 05acc73e2e33..cbe6c5fd6c4d 100644
> > > --- a/Documentation/netlink/specs/nfsd.yaml
> > > +++ b/Documentation/netlink/specs/nfsd.yaml
> > > @@ -62,6 +62,18 @@ attribute-sets:
> > >          name: compound-ops
> > >          type: u32
> > >          multi-attr: true
> > > +  -
> > > +    name: server-worker
> > > +    attributes:
> > > +      -
> > > +        name: threads
> > > +        type: u32
> > > +      -
> > > +        name: gracetime
> > > +        type: u32
> > > +      -
> > > +        name: leasetime
> > > +        type: u32
> > > =20
> > >  operations:
> > >    list:
> > > @@ -87,3 +99,24 @@ operations:
> > >              - sport
> > >              - dport
> > >              - compound-ops
> > > +    -
> > > +      name: threads-set
> > > +      doc: set the number of running threads
> > > +      attribute-set: server-worker
> > > +      flags: [ admin-perm ]
> > > +      do:
> > > +        request:
> > > +          attributes:
> > > +            - threads
> > > +            - gracetime
> > > +            - leasetime
> > > +    -
> > > +      name: threads-get
> > > +      doc: get the number of running threads
> > > +      attribute-set: server-worker
> > > +      do:
> > > +        reply:
> > > +          attributes:
> > > +            - threads
> > > +            - gracetime
> > > +            - leasetime
> > > diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
> > > index 0e1d635ec5f9..20a646af0324 100644
> > > --- a/fs/nfsd/netlink.c
> > > +++ b/fs/nfsd/netlink.c
> > > @@ -10,6 +10,13 @@
> > > =20
> > >  #include <uapi/linux/nfsd_netlink.h>
> > > =20
> > > +/* NFSD_CMD_THREADS_SET - do */
> > > +static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SER=
VER_WORKER_LEASETIME + 1] =3D {
> > > +	[NFSD_A_SERVER_WORKER_THREADS] =3D { .type =3D NLA_U32, },
> > > +	[NFSD_A_SERVER_WORKER_GRACETIME] =3D { .type =3D NLA_U32, },
> > > +	[NFSD_A_SERVER_WORKER_LEASETIME] =3D { .type =3D NLA_U32, },
> > > +};
> > > +
> > >  /* Ops table for nfsd */
> > >  static const struct genl_split_ops nfsd_nl_ops[] =3D {
> > >  	{
> > > @@ -19,6 +26,18 @@ static const struct genl_split_ops nfsd_nl_ops[] =
=3D {
> > >  		.done	=3D nfsd_nl_rpc_status_get_done,
> > >  		.flags	=3D GENL_CMD_CAP_DUMP,
> > >  	},
> > > +	{
> > > +		.cmd		=3D NFSD_CMD_THREADS_SET,
> > > +		.doit		=3D nfsd_nl_threads_set_doit,
> > > +		.policy		=3D nfsd_threads_set_nl_policy,
> > > +		.maxattr	=3D NFSD_A_SERVER_WORKER_LEASETIME,
> > > +		.flags		=3D GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
> > > +	},
> > > +	{
> > > +		.cmd	=3D NFSD_CMD_THREADS_GET,
> > > +		.doit	=3D nfsd_nl_threads_get_doit,
> > > +		.flags	=3D GENL_CMD_CAP_DO,
> > > +	},
> > >  };
> > > =20
> > >  struct genl_family nfsd_nl_family __ro_after_init =3D {
> > > diff --git a/fs/nfsd/netlink.h b/fs/nfsd/netlink.h
> > > index d83dd6bdee92..4137fac477e4 100644
> > > --- a/fs/nfsd/netlink.h
> > > +++ b/fs/nfsd/netlink.h
> > > @@ -16,6 +16,8 @@ int nfsd_nl_rpc_status_get_done(struct netlink_call=
back *cb);
> > > =20
> > >  int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb,
> > >  				  struct netlink_callback *cb);
> > > +int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *=
info);
> > > +int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *=
info);
> > > =20
> > >  extern struct genl_family nfsd_nl_family;
> > > =20
> > > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > > index f2e442d7fe16..38a5df03981b 100644
> > > --- a/fs/nfsd/nfsctl.c
> > > +++ b/fs/nfsd/nfsctl.c
> > > @@ -1653,6 +1653,110 @@ int nfsd_nl_rpc_status_get_done(struct netlin=
k_callback *cb)
> > >  	return 0;
> > >  }
> > > =20
> > > +/**
> > > + * nfsd_nl_threads_set_doit - set the number of running threads
> > > + * @skb: reply buffer
> > > + * @info: netlink metadata and command arguments
> > > + *
> > > + * Return 0 on success or a negative errno.
> > > + */
> > > +int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *=
info)
> > > +{
> > > +	struct net *net =3D genl_info_net(info);
> > > +	struct nfsd_net *nn =3D net_generic(net, nfsd_net_id);
> > > +	int ret =3D -EBUSY;
> > > +	u32 nthreads;
> > > +
> > > +	if (GENL_REQ_ATTR_CHECK(info, NFSD_A_SERVER_WORKER_THREADS))
> > > +		return -EINVAL;
> > > +
> > > +	nthreads =3D nla_get_u32(info->attrs[NFSD_A_SERVER_WORKER_THREADS])=
;
> > > +
> > > +	mutex_lock(&nfsd_mutex);
> > > +	if (info->attrs[NFSD_A_SERVER_WORKER_GRACETIME] ||
> > > +	    info->attrs[NFSD_A_SERVER_WORKER_LEASETIME]) {
> > > +		const struct nlattr *attr;
> > > +
> > > +		if (nn->nfsd_serv && nn->nfsd_serv->sv_nrthreads)
> > > +			goto out_unlock;
> > > +
> > > +		ret =3D -EINVAL;
> > > +		attr =3D info->attrs[NFSD_A_SERVER_WORKER_GRACETIME];
> > > +		if (attr) {
> > > +			u32 gracetime =3D nla_get_u32(attr);
> > > +
> > > +			if (gracetime < 10 || gracetime > 3600)
> > > +				goto out_unlock;
> > > +
> > > +			nn->nfsd4_grace =3D gracetime;
> > > +		}
> > > +
> > > +		attr =3D info->attrs[NFSD_A_SERVER_WORKER_LEASETIME];
> > > +		if (attr) {
> > > +			u32 leasetime =3D nla_get_u32(attr);
> > > +
> > > +			if (leasetime < 10 || leasetime > 3600)
> > > +				goto out_unlock;
> > > +
> > > +			nn->nfsd4_lease =3D leasetime;
> > > +		}
> > > +	}
> > > +
> > > +	ret =3D nfsd_svc(nthreads, net, get_current_cred());
> > > +out_unlock:
> > > +	mutex_unlock(&nfsd_mutex);
> > > +
> > > +	return ret =3D=3D nthreads ? 0 : ret;
> > > +}
> > > +
> > > +/**
> > > + * nfsd_nl_threads_get_doit - get the number of running threads
> > > + * @skb: reply buffer
> > > + * @info: netlink metadata and command arguments
> > > + *
> > > + * Return 0 on success or a negative errno.
> > > + */
> > > +int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *=
info)
> > > +{
> > > +	struct net *net =3D genl_info_net(info);
> > > +	struct nfsd_net *nn =3D net_generic(net, nfsd_net_id);
> > > +	void *hdr;
> > > +	int err;
> > > +
> > > +	skb =3D genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> > > +	if (!skb)
> > > +		return -ENOMEM;
> > > +
> > > +	hdr =3D genlmsg_iput(skb, info);
> > > +	if (!hdr) {
> > > +		err =3D -EMSGSIZE;
> > > +		goto err_free_msg;
> > > +	}
> > > +
> > > +	mutex_lock(&nfsd_mutex);
> > > +	err =3D nla_put_u32(skb, NFSD_A_SERVER_WORKER_GRACETIME,
> > > +			  nn->nfsd4_grace) ||
> > > +	      nla_put_u32(skb, NFSD_A_SERVER_WORKER_LEASETIME,
> > > +			  nn->nfsd4_lease) ||
> > > +	      nla_put_u32(skb, NFSD_A_SERVER_WORKER_THREADS,
> > > +			  nn->nfsd_serv ? nn->nfsd_serv->sv_nrthreads : 0);
> > > +	mutex_unlock(&nfsd_mutex);
> > > +
> > > +	if (err) {
> > > +		err =3D -EINVAL;
> > > +		goto err_free_msg;
> > > +	}
> > > +
> > > +	genlmsg_end(skb, hdr);
> > > +
> > > +	return genlmsg_reply(skb, info);
> > > +
> > > +err_free_msg:
> > > +	nlmsg_free(skb);
> > > +
> > > +	return err;
> > > +}
> > > +
> > >  /**
> > >   * nfsd_net_init - Prepare the nfsd_net portion of a new net namespa=
ce
> > >   * @net: a freshly-created network namespace
> > > diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/n=
fsd_netlink.h
> > > index 3cd044edee5d..ccc78a5ee650 100644
> > > --- a/include/uapi/linux/nfsd_netlink.h
> > > +++ b/include/uapi/linux/nfsd_netlink.h
> > > @@ -29,8 +29,19 @@ enum {
> > >  	NFSD_A_RPC_STATUS_MAX =3D (__NFSD_A_RPC_STATUS_MAX - 1)
> > >  };
> > > =20
> > > +enum {
> > > +	NFSD_A_SERVER_WORKER_THREADS =3D 1,
> > > +	NFSD_A_SERVER_WORKER_GRACETIME,
> > > +	NFSD_A_SERVER_WORKER_LEASETIME,
> > > +
> > > +	__NFSD_A_SERVER_WORKER_MAX,
> > > +	NFSD_A_SERVER_WORKER_MAX =3D (__NFSD_A_SERVER_WORKER_MAX - 1)
> > > +};
> > > +
> > >  enum {
> > >  	NFSD_CMD_RPC_STATUS_GET =3D 1,
> > > +	NFSD_CMD_THREADS_SET,
> > > +	NFSD_CMD_THREADS_GET,
> > > =20
> > >  	__NFSD_CMD_MAX,
> > >  	NFSD_CMD_MAX =3D (__NFSD_CMD_MAX - 1)
> > > --=20
> > > 2.44.0
> > >=20
> > >=20
> >=20
>=20

--=20
Jeff Layton <jlayton@kernel.org>