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Date: Fri, 22 Sep 2023 12:04:32 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Lorenzo Bianconi <lorenzo@...nel.org>, linux-nfs@...r.kernel.org
Cc: lorenzo.bianconi@...hat.com, neilb@...e.de, chuck.lever@...cle.com,
netdev@...r.kernel.org
Subject: Re: [PATCH] NFSD: convert write_threads and write_v4_end_grace to
netlink commands
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@...nel.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!
> + -
> + 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
matter at all. Do we have to send down a value at all?
> + 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@...nel.org>
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