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Date: Fri, 22 Sep 2023 16:06:44 +0000
From: Chuck Lever III <chuck.lever@...cle.com>
To: Jeff Layton <jlayton@...nel.org>
CC: Lorenzo Bianconi <lorenzo@...nel.org>,
Linux NFS Mailing List
<linux-nfs@...r.kernel.org>,
Lorenzo Bianconi <lorenzo.bianconi@...hat.com>,
Neil Brown <neilb@...e.de>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] NFSD: convert write_threads and write_v4_end_grace to
netlink commands
> On Sep 22, 2023, at 12:04 PM, Jeff Layton <jlayton@...nel.org> wrote:
>
> 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!
No argument.
But I thought you could echo a negative number of threads in /proc/fs/nfsd/threads
to reduce the thread count. Maybe this field should be an s32?
>> + -
>> + 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>
--
Chuck Lever
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