Re: [PATCH] NFSD: convert write_threads and write_v4_end_grace to netlink commands

[Lorenzo Bianconi <lorenzo.bianconi@redhat.com>]

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> On Fri, 2023-09-22 at 14:44 +0200, Lorenzo Bianconi wrote:
> > Introduce write_threads and write_v4_end_grace netlink commands similar
> > to the ones available through the procfs.
> > Introduce nfsd_nl_server_status_get_dumpit netlink command in order to
> > report global server metadata.
> > 
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
> > This patch can be tested with user-space tool reported below:
> > https://github.com/LorenzoBianconi/nfsd-netlink.git
> > ---
> >  Documentation/netlink/specs/nfsd.yaml | 33 +++++++++
> >  fs/nfsd/netlink.c                     | 30 ++++++++
> >  fs/nfsd/netlink.h                     |  5 ++
> >  fs/nfsd/nfsctl.c                      | 98 +++++++++++++++++++++++++++
> >  include/uapi/linux/nfsd_netlink.h     | 11 +++
> >  5 files changed, 177 insertions(+)
> > 
> > diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/specs/nfsd.yaml
> > index 403d3e3a04f3..fa1204892703 100644
> > --- a/Documentation/netlink/specs/nfsd.yaml
> > +++ b/Documentation/netlink/specs/nfsd.yaml
> > @@ -62,6 +62,15 @@ attribute-sets:
> >          name: compound-ops
> >          type: u32
> >          multi-attr: true
> > +  -
> > +    name: server-attr
> > +    attributes:
> > +      -
> > +        name: threads
> > +        type: u16
> 
> 65k threads ought to be enough for anybody!

maybe u8 is fine here :)

> 
> > +      -
> > +        name: v4-grace
> > +        type: u8
> >  
> >  operations:
> >    list:
> > @@ -72,3 +81,27 @@ operations:
> >        dump:
> >          pre: nfsd-nl-rpc-status-get-start
> >          post: nfsd-nl-rpc-status-get-done
> > +    -
> > +      name: threads-set
> > +      doc: set the number of running threads
> > +      attribute-set: server-attr
> > +      flags: [ admin-perm ]
> > +      do:
> > +        request:
> > +          attributes:
> > +            - threads
> > +    -
> > +      name: v4-grace-release
> > +      doc: release the grace period for nfsd's v4 lock manager
> > +      attribute-set: server-attr
> > +      flags: [ admin-perm ]
> > +      do:
> > +        request:
> > +          attributes:
> > +            - v4-grace
> > +    -
> > +      name: server-status-get
> > +      doc: dump server status info
> > +      attribute-set: server-attr
> > +      dump:
> > +        pre: nfsd-nl-server-status-get-start
> > diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
> > index 0e1d635ec5f9..783a34e69354 100644
> > --- a/fs/nfsd/netlink.c
> > +++ b/fs/nfsd/netlink.c
> > @@ -10,6 +10,16 @@
> >  
> >  #include <uapi/linux/nfsd_netlink.h>
> >  
> > +/* NFSD_CMD_THREADS_SET - do */
> > +static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_ATTR_THREADS + 1] = {
> > +	[NFSD_A_SERVER_ATTR_THREADS] = { .type = NLA_U16, },
> > +};
> > +
> > +/* NFSD_CMD_V4_GRACE_RELEASE - do */
> > +static const struct nla_policy nfsd_v4_grace_release_nl_policy[NFSD_A_SERVER_ATTR_V4_GRACE + 1] = {
> > +	[NFSD_A_SERVER_ATTR_V4_GRACE] = { .type = NLA_U8, },
> > +};
> > +
> >  /* Ops table for nfsd */
> >  static const struct genl_split_ops nfsd_nl_ops[] = {
> >  	{
> > @@ -19,6 +29,26 @@ static const struct genl_split_ops nfsd_nl_ops[] = {
> >  		.done	= nfsd_nl_rpc_status_get_done,
> >  		.flags	= GENL_CMD_CAP_DUMP,
> >  	},
> > +	{
> > +		.cmd		= NFSD_CMD_THREADS_SET,
> > +		.doit		= nfsd_nl_threads_set_doit,
> > +		.policy		= nfsd_threads_set_nl_policy,
> > +		.maxattr	= NFSD_A_SERVER_ATTR_THREADS,
> > +		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
> > +	},
> > +	{
> > +		.cmd		= NFSD_CMD_V4_GRACE_RELEASE,
> > +		.doit		= nfsd_nl_v4_grace_release_doit,
> > +		.policy		= nfsd_v4_grace_release_nl_policy,
> > +		.maxattr	= NFSD_A_SERVER_ATTR_V4_GRACE,
> > +		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
> > +	},
> > +	{
> > +		.cmd	= NFSD_CMD_SERVER_STATUS_GET,
> > +		.start	= nfsd_nl_server_status_get_start,
> > +		.dumpit	= nfsd_nl_server_status_get_dumpit,
> > +		.flags	= GENL_CMD_CAP_DUMP,
> > +	},
> >  };
> >  
> >  struct genl_family nfsd_nl_family __ro_after_init = {
> > diff --git a/fs/nfsd/netlink.h b/fs/nfsd/netlink.h
> > index d83dd6bdee92..2e98061fbb0a 100644
> > --- a/fs/nfsd/netlink.h
> > +++ b/fs/nfsd/netlink.h
> > @@ -12,10 +12,15 @@
> >  #include <uapi/linux/nfsd_netlink.h>
> >  
> >  int nfsd_nl_rpc_status_get_start(struct netlink_callback *cb);
> > +int nfsd_nl_server_status_get_start(struct netlink_callback *cb);
> >  int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb);
> >  
> >  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_v4_grace_release_doit(struct sk_buff *skb, struct genl_info *info);
> > +int nfsd_nl_server_status_get_dumpit(struct sk_buff *skb,
> > +				     struct netlink_callback *cb);
> >  
> >  extern struct genl_family nfsd_nl_family;
> >  
> > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > index b71744e355a8..c631b59b7a4f 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -1694,6 +1694,104 @@ int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb)
> >  	return 0;
> >  }
> >  
> > +/**
> > + * 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)
> > +{
> > +	u16 nthreads;
> > +	int ret;
> > +
> > +	if (!info->attrs[NFSD_A_SERVER_ATTR_THREADS])
> > +		return -EINVAL;
> > +
> > +	nthreads = nla_get_u16(info->attrs[NFSD_A_SERVER_ATTR_THREADS]);
> > +
> > +	ret = nfsd_svc(nthreads, genl_info_net(info), get_current_cred());
> > +	return ret == nthreads ? 0 : ret;
> > +}
> > +
> > +/**
> > + * nfsd_nl_v4_grace_release_doit - release the nfs4 grace period
> > + * @skb: reply buffer
> > + * @info: netlink metadata and command arguments
> > + *
> > + * Return 0 on success or a negative errno.
> > + */
> > +int nfsd_nl_v4_grace_release_doit(struct sk_buff *skb, struct genl_info *info)
> > +{
> > +#ifdef CONFIG_NFSD_V4
> > +	struct nfsd_net *nn = net_generic(genl_info_net(info), nfsd_net_id);
> > +
> > +	if (!info->attrs[NFSD_A_SERVER_ATTR_V4_GRACE])
> > +		return -EINVAL;
> > +
> > +	if (nla_get_u8(info->attrs[NFSD_A_SERVER_ATTR_V4_GRACE]))
> > +		nfsd4_end_grace(nn);
> > +
> 
> To be clear here. Issuing this with anything but 0 will end the grace
> period. A value of 0 is ignored. It might be best to make the value not

I tried to be aligned with write_v4_end_grace() here but supporting just 1 (or
any other non-zero value) and skipping 'Y/y'. If we send 0 it should skip the
release action.

> matter at all. Do we have to send down a value at all?

I am not sure if ynl supports a doit operation with a request with no parameters.
@Chuck, Jakub: any input here?

Regards,
Lorenzo

> 
> > +	return 0;
> > +#else
> > +	return -EOPNOTSUPP;
> > +#endif /* CONFIG_NFSD_V4 */
> > +}
> > +
> > +/**
> > + * nfsd_nl_server_status_get_start - Prepare server_status_get dumpit
> > + * @cb: netlink metadata and command arguments
> > + *
> > + * Return values:
> > + *   %0: The server_status_get command may proceed
> > + *   %-ENODEV: There is no NFSD running in this namespace
> > + */
> > +int nfsd_nl_server_status_get_start(struct netlink_callback *cb)
> > +{
> > +	struct nfsd_net *nn = net_generic(sock_net(cb->skb->sk), nfsd_net_id);
> > +
> > +	return nn->nfsd_serv ? 0 : -ENODEV;
> > +}
> > +
> > +/**
> > + * nfsd_nl_server_status_get_dumpit - dump server status info
> > + * @skb: reply buffer
> > + * @cb: netlink metadata and command arguments
> > + *
> > + * Returns the size of the reply or a negative errno.
> > + */
> > +int nfsd_nl_server_status_get_dumpit(struct sk_buff *skb,
> > +				     struct netlink_callback *cb)
> > +{
> > +	struct net *net = sock_net(skb->sk);
> > +#ifdef CONFIG_NFSD_V4
> > +	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> > +#endif /* CONFIG_NFSD_V4 */
> > +	void *hdr;
> > +
> > +	if (cb->args[0]) /* already consumed */
> > +		return 0;
> > +
> > +	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
> > +			  &nfsd_nl_family, NLM_F_MULTI,
> > +			  NFSD_CMD_SERVER_STATUS_GET);
> > +	if (!hdr)
> > +		return -ENOBUFS;
> > +
> > +	if (nla_put_u16(skb, NFSD_A_SERVER_ATTR_THREADS, nfsd_nrthreads(net)))
> > +		return -ENOBUFS;
> > +#ifdef CONFIG_NFSD_V4
> > +	if (nla_put_u8(skb, NFSD_A_SERVER_ATTR_V4_GRACE, !nn->grace_ended))
> > +		return -ENOBUFS;
> > +#endif /* CONFIG_NFSD_V4 */
> > +
> > +	genlmsg_end(skb, hdr);
> > +	cb->args[0] = 1;
> > +
> > +	return skb->len;
> > +}
> > +
> >  /**
> >   * nfsd_net_init - Prepare the nfsd_net portion of a new net namespace
> >   * @net: a freshly-created network namespace
> > diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_netlink.h
> > index c8ae72466ee6..b82fbc53d336 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 = (__NFSD_A_RPC_STATUS_MAX - 1)
> >  };
> >  
> > +enum {
> > +	NFSD_A_SERVER_ATTR_THREADS = 1,
> > +	NFSD_A_SERVER_ATTR_V4_GRACE,
> > +
> > +	__NFSD_A_SERVER_ATTR_MAX,
> > +	NFSD_A_SERVER_ATTR_MAX = (__NFSD_A_SERVER_ATTR_MAX - 1)
> > +};
> > +
> >  enum {
> >  	NFSD_CMD_RPC_STATUS_GET = 1,
> > +	NFSD_CMD_THREADS_SET,
> > +	NFSD_CMD_V4_GRACE_RELEASE,
> > +	NFSD_CMD_SERVER_STATUS_GET,
> >  
> >  	__NFSD_CMD_MAX,
> >  	NFSD_CMD_MAX = (__NFSD_CMD_MAX - 1)
> 
> -- 
> Jeff Layton <jlayton@kernel.org>
> 

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