Re: [PATCH v5 1/3] NFSD: convert write_threads to netlink command

Chuck Lever
2023-11-29T18:31:31Z

On Wed, Nov 29, 2023 at 01:13:34PM -0500, Jeff Layton wrote:
> On Wed, 2023-11-29 at 18:12 +0100, Lorenzo Bianconi wrote:
> > Introduce write_threads netlink command similar to the ones available
> > through the procfs.
> >
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
> > Documentation/netlink/specs/nfsd.yaml | 23 +++++++
> > fs/nfsd/netlink.c | 17 +++++
> > fs/nfsd/netlink.h | 2 +
> > fs/nfsd/nfsctl.c | 58 +++++++++++++++++
> > include/uapi/linux/nfsd_netlink.h | 9 +++
> > tools/net/ynl/generated/nfsd-user.c | 92 +++++++++++++++++++++++++++
> > tools/net/ynl/generated/nfsd-user.h | 47 ++++++++++++++
> > 7 files changed, 248 insertions(+)
> >
> > diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/specs/nfsd.yaml
> > index 05acc73e2e33..c92e1425d316 100644
> > --- a/Documentation/netlink/specs/nfsd.yaml
> > +++ b/Documentation/netlink/specs/nfsd.yaml
> > @@ -62,6 +62,12 @@ attribute-sets:
> > name: compound-ops
> > type: u32
> > multi-attr: true
> > + -
> > + name: server-worker
> > + attributes:
> > + -
> > + name: threads
> > + type: u32
> >
> > operations:
> > list:
> > @@ -87,3 +93,20 @@ 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
> > + -
> > + name: threads-get
> > + doc: get the number of running threads
> > + attribute-set: server-worker
> > + do:
> > + reply:
> > + attributes:
> > + - threads
> > diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
> > index 0e1d635ec5f9..1a59a8e6c7e2 100644
> > --- a/fs/nfsd/netlink.c
> > +++ b/fs/nfsd/netlink.c
> > @@ -10,6 +10,11 @@
> >
> > #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_THREADS + 1] = {
> > + [NFSD_A_SERVER_WORKER_THREADS] = { .type = NLA_U32, },
> > +};
> > +
> > /* Ops table for nfsd */
> > static const struct genl_split_ops nfsd_nl_ops[] = {
> > {
> > @@ -19,6 +24,18 @@ 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_THREADS,
> > + .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 d6eeee149370..130b3d937a79 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -1699,6 +1699,64 @@ 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)
> > +{
> > + u32 nthreads;
> > + int ret;
> > +
> > + if (GENL_REQ_ATTR_CHECK(info, NFSD_A_SERVER_WORKER_THREADS))
> > + return -EINVAL;
> > +
> > + nthreads = nla_get_u32(info->attrs[NFSD_A_SERVER_WORKER_THREADS]);
> > + ret = nfsd_svc(nthreads, genl_info_net(info), get_current_cred());
> > +
> > + 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)
> > +{
> > + 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;
> > + }
> > +
> > + if (nla_put_u32(skb, NFSD_A_SERVER_WORKER_THREADS,
> > + nfsd_nrthreads(genl_info_net(info)))) {
> > + 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..1b6fe1f9ed0e 100644
> > --- a/include/uapi/linux/nfsd_netlink.h
> > +++ b/include/uapi/linux/nfsd_netlink.h
> > @@ -29,8 +29,17 @@ enum {
> > NFSD_A_RPC_STATUS_MAX = (__NFSD_A_RPC_STATUS_MAX - 1)
> > };
> >
> > +enum {
> > + NFSD_A_SERVER_WORKER_THREADS = 1,
> > +
> > + __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)
> > diff --git a/tools/net/ynl/generated/nfsd-user.c b/tools/net/ynl/generated/nfsd-user.c
> > index 360b6448c6e9..9768328a7751 100644
> > --- a/tools/net/ynl/generated/nfsd-user.c
> > +++ b/tools/net/ynl/generated/nfsd-user.c
> > @@ -15,6 +15,8 @@
> > /* Enums */
> > static const char * const nfsd_op_strmap[] = {
> > [NFSD_CMD_RPC_STATUS_GET] = "rpc-status-get",
> > + [NFSD_CMD_THREADS_SET] = "threads-set",
> > + [NFSD_CMD_THREADS_GET] = "threads-get",
> > };
> >
> > const char *nfsd_op_str(int op)
> > @@ -47,6 +49,15 @@ struct ynl_policy_nest nfsd_rpc_status_nest = {
> > .table = nfsd_rpc_status_policy,
> > };
> >
> > +struct ynl_policy_attr nfsd_server_worker_policy[NFSD_A_SERVER_WORKER_MAX + 1] = {
> > + [NFSD_A_SERVER_WORKER_THREADS] = { .name = "threads", .type = YNL_PT_U32, },
> > +};
> > +
> > +struct ynl_policy_nest nfsd_server_worker_nest = {
> > + .max_attr = NFSD_A_SERVER_WORKER_MAX,
> > + .table = nfsd_server_worker_policy,
> > +};
> > +
> > /* Common nested types */
> > /* ============== NFSD_CMD_RPC_STATUS_GET ============== */
> > /* NFSD_CMD_RPC_STATUS_GET - dump */
> > @@ -198,6 +209,87 @@ nfsd_rpc_status_get_dump(struct ynl_sock *ys)
> > return NULL;
> > }
> >
> > +/* ============== NFSD_CMD_THREADS_SET ============== */
> > +/* NFSD_CMD_THREADS_SET - do */
> > +void nfsd_threads_set_req_free(struct nfsd_threads_set_req *req)
> > +{
> > + free(req);
> > +}
> > +
> > +int nfsd_threads_set(struct ynl_sock *ys, struct nfsd_threads_set_req *req)
> > +{
> > + struct nlmsghdr *nlh;
> > + int err;
> > +
> > + nlh = ynl_gemsg_start_req(ys, ys->family_id, NFSD_CMD_THREADS_SET, 1);
> > + ys->req_policy = &nfsd_server_worker_nest;
> > +
> > + if (req->_present.threads)
> > + mnl_attr_put_u32(nlh, NFSD_A_SERVER_WORKER_THREADS, req->threads);
> > +
> > + err = ynl_exec(ys, nlh, NULL);
> > + if (err < 0)
> > + return -1;
> > +
> > + return 0;
> > +}
> > +
> > +/* ============== NFSD_CMD_THREADS_GET ============== */
> > +/* NFSD_CMD_THREADS_GET - do */
> > +void nfsd_threads_get_rsp_free(struct nfsd_threads_get_rsp *rsp)
> > +{
> > + free(rsp);
> > +}
> > +
> > +int nfsd_threads_get_rsp_parse(const struct nlmsghdr *nlh, void *data)
> > +{
> > + struct ynl_parse_arg *yarg = data;
> > + struct nfsd_threads_get_rsp *dst;
> > + const struct nlattr *attr;
> > +
> > + dst = yarg->data;
> > +
> > + mnl_attr_for_each(attr, nlh, sizeof(struct genlmsghdr)) {
> > + unsigned int type = mnl_attr_get_type(attr);
> > +
> > + if (type == NFSD_A_SERVER_WORKER_THREADS) {
> > + if (ynl_attr_validate(yarg, attr))
> > + return MNL_CB_ERROR;
> > + dst->_present.threads = 1;
> > + dst->threads = mnl_attr_get_u32(attr);
> > + }
> > + }
> > +
> > + return MNL_CB_OK;
> > +}
> > +
> > +struct nfsd_threads_get_rsp *nfsd_threads_get(struct ynl_sock *ys)
> > +{
> > + struct ynl_req_state yrs = { .yarg = { .ys = ys, }, };
> > + struct nfsd_threads_get_rsp *rsp;
> > + struct nlmsghdr *nlh;
> > + int err;
> > +
> > + nlh = ynl_gemsg_start_req(ys, ys->family_id, NFSD_CMD_THREADS_GET, 1);
> > + ys->req_policy = &nfsd_server_worker_nest;
> > + yrs.yarg.rsp_policy = &nfsd_server_worker_nest;
> > +
> > + rsp = calloc(1, sizeof(*rsp));
> > + yrs.yarg.data = rsp;
> > + yrs.cb = nfsd_threads_get_rsp_parse;
> > + yrs.rsp_cmd = NFSD_CMD_THREADS_GET;
> > +
> > + err = ynl_exec(ys, nlh, &yrs);
> > + if (err < 0)
> > + goto err_free;
> > +
> > + return rsp;
> > +
> > +err_free:
> > + nfsd_threads_get_rsp_free(rsp);
> > + return NULL;
> > +}
> > +
> > const struct ynl_family ynl_nfsd_family = {
> > .name = "nfsd",
> > };
> > diff --git a/tools/net/ynl/generated/nfsd-user.h b/tools/net/ynl/generated/nfsd-user.h
> > index 989c6e209ced..e162a4f20d91 100644
> > --- a/tools/net/ynl/generated/nfsd-user.h
> > +++ b/tools/net/ynl/generated/nfsd-user.h
> > @@ -64,4 +64,51 @@ nfsd_rpc_status_get_rsp_list_free(struct nfsd_rpc_status_get_rsp_list *rsp);
> > struct nfsd_rpc_status_get_rsp_list *
> > nfsd_rpc_status_get_dump(struct ynl_sock *ys);
> >
> > +/* ============== NFSD_CMD_THREADS_SET ============== */
> > +/* NFSD_CMD_THREADS_SET - do */
> > +struct nfsd_threads_set_req {
> > + struct {
> > + __u32 threads:1;
> > + } _present;
> > +
> > + __u32 threads;
> > +};
> > +
> > +static inline struct nfsd_threads_set_req *nfsd_threads_set_req_alloc(void)
> > +{
> > + return calloc(1, sizeof(struct nfsd_threads_set_req));
> > +}
> > +void nfsd_threads_set_req_free(struct nfsd_threads_set_req *req);
> > +
> > +static inline void
> > +nfsd_threads_set_req_set_threads(struct nfsd_threads_set_req *req,
> > + __u32 threads)
> > +{
> > + req->_present.threads = 1;
> > + req->threads = threads;
> > +}
> > +
> > +/*
> > + * set the number of running threads
> > + */
> > +int nfsd_threads_set(struct ynl_sock *ys, struct nfsd_threads_set_req *req);
> > +
> > +/* ============== NFSD_CMD_THREADS_GET ============== */
> > +/* NFSD_CMD_THREADS_GET - do */
> > +
> > +struct nfsd_threads_get_rsp {
> > + struct {
> > + __u32 threads:1;
> > + } _present;
> > +
> > + __u32 threads;
> > +};
> > +
> > +void nfsd_threads_get_rsp_free(struct nfsd_threads_get_rsp *rsp);
> > +
> > +/*
> > + * get the number of running threads
> > + */
> > +struct nfsd_threads_get_rsp *nfsd_threads_get(struct ynl_sock *ys);
> > +
> > #endif /* _LINUX_NFSD_GEN_H */
>
> Ok, Uncle! I'll relent on the quest for a single netlink command to
> start the server.

I think we can consider a single config/start-up command, but I
don't feel it has to happen as part of this series, unless I'm
missing something critical. It seems like a declarative mechanism
would need some deeper changes in NFSD.

> This patch looks reasonable to me.
>
> Reviewed-by: Jeff Layton <jlayton@kernel.org>

Thanks, Jeff!

Before applying these, I'd like an Acked-by from Jakub for the
tools/net/ynl modifications, and at least a fresh sanity check from
Jakub on the changes to the nfsd netlink protocol (though I don't
anything problematic so far).

--
Chuck Lever