Re: [PATCH v8 2/6] NFSD: convert write_threads to netlink command

["NeilBrown" <neilb@suse.de>]

On Tue, 16 Apr 2024, Lorenzo Bianconi wrote:
> Introduce write_threads netlink command similar to the one available
> through the procfs.

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.

NeilBrown


> 
> 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(+)
> 
> diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/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
>  
>  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 @@
>  
>  #include <uapi/linux/nfsd_netlink.h>
>  
> +/* NFSD_CMD_THREADS_SET - do */
> +static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_WORKER_LEASETIME + 1] = {
> +	[NFSD_A_SERVER_WORKER_THREADS] = { .type = NLA_U32, },
> +	[NFSD_A_SERVER_WORKER_GRACETIME] = { .type = NLA_U32, },
> +	[NFSD_A_SERVER_WORKER_LEASETIME] = { .type = NLA_U32, },
> +};
> +
>  /* Ops table for nfsd */
>  static const struct genl_split_ops nfsd_nl_ops[] = {
>  	{
> @@ -19,6 +26,18 @@ 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_WORKER_LEASETIME,
> +		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
> +	},
> +	{
> +		.cmd	= NFSD_CMD_THREADS_GET,
> +		.doit	= nfsd_nl_threads_get_doit,
> +		.flags	= GENL_CMD_CAP_DO,
> +	},
>  };
>  
>  struct genl_family nfsd_nl_family __ro_after_init = {
> 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_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_threads_get_doit(struct sk_buff *skb, struct genl_info *info);
>  
>  extern struct genl_family nfsd_nl_family;
>  
> 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 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)
> +{
> +	struct net *net = genl_info_net(info);
> +	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> +	int ret = -EBUSY;
> +	u32 nthreads;
> +
> +	if (GENL_REQ_ATTR_CHECK(info, NFSD_A_SERVER_WORKER_THREADS))
> +		return -EINVAL;
> +
> +	nthreads = 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 = -EINVAL;
> +		attr = info->attrs[NFSD_A_SERVER_WORKER_GRACETIME];
> +		if (attr) {
> +			u32 gracetime = nla_get_u32(attr);
> +
> +			if (gracetime < 10 || gracetime > 3600)
> +				goto out_unlock;
> +
> +			nn->nfsd4_grace = gracetime;
> +		}
> +
> +		attr = info->attrs[NFSD_A_SERVER_WORKER_LEASETIME];
> +		if (attr) {
> +			u32 leasetime = nla_get_u32(attr);
> +
> +			if (leasetime < 10 || leasetime > 3600)
> +				goto out_unlock;
> +
> +			nn->nfsd4_lease = leasetime;
> +		}
> +	}
> +
> +	ret = nfsd_svc(nthreads, net, get_current_cred());
> +out_unlock:
> +	mutex_unlock(&nfsd_mutex);
> +
> +	return ret == 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 = genl_info_net(info);
> +	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> +	void *hdr;
> +	int err;
> +
> +	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	hdr = genlmsg_iput(skb, info);
> +	if (!hdr) {
> +		err = -EMSGSIZE;
> +		goto err_free_msg;
> +	}
> +
> +	mutex_lock(&nfsd_mutex);
> +	err = 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 = -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 namespace
>   * @net: a freshly-created network namespace
> diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_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 = (__NFSD_A_RPC_STATUS_MAX - 1)
>  };
>  
> +enum {
> +	NFSD_A_SERVER_WORKER_THREADS = 1,
> +	NFSD_A_SERVER_WORKER_GRACETIME,
> +	NFSD_A_SERVER_WORKER_LEASETIME,
> +
> +	__NFSD_A_SERVER_WORKER_MAX,
> +	NFSD_A_SERVER_WORKER_MAX = (__NFSD_A_SERVER_WORKER_MAX - 1)
> +};
> +
>  enum {
>  	NFSD_CMD_RPC_STATUS_GET = 1,
> +	NFSD_CMD_THREADS_SET,
> +	NFSD_CMD_THREADS_GET,
>  
>  	__NFSD_CMD_MAX,
>  	NFSD_CMD_MAX = (__NFSD_CMD_MAX - 1)
> -- 
> 2.44.0
> 
>