Re: [PATCH v7 3/3] NFSD: add rpc_status netlink support

Lorenzo Bianconi
2023-08-30T18:29:30Z

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> On Wed, Aug 30, 2023 at 03:05:46PM +0200, Lorenzo Bianconi wrote:
> > Introduce rpc_status netlink support for NFSD in order to dump pending
> > RPC requests debugging information from userspace.
>
> Very good to see this update!
>
> netdev has asked that all new netlink protocols start from a yaml
> spec that resides under Documentation/netlink/specs/ That spec is
> then used to generate netlink parser code for the kernel and for
> user space tooling. You can find this all described here:
>
> https://docs.kernel.org/next/userspace-api/netlink/specs.html
>
> and here is a weak example of how this might be done:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/commit/net/handshake?id=3b3009ea8abb713b022d94fba95ec270cf6e7eae
>
> I say weak because I did that work while the yaml spec tools were
> still under development. It might not completely reflect how this
> needs to be done today.
>
> So the yaml file would be named something like:
>
> Documentation/netlink/specs/nfsd.yaml
>
> and it would generate files "fs/nfsd/netlink.[ch]". It should
> generate a lot of the parser boiler plate you've written below
> by hand, so just replace that code with calls to the generated
> code.

ack, I will look into it for v8

>
> When you post the next revision of the series, cc: netdev.

ack, will do.

Regards,
Lorenzo

>
>
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
> > fs/nfsd/nfsctl.c | 275 +++++++++++++++++++++++++++++++++++++
> > fs/nfsd/nfsd.h | 19 +++
> > fs/nfsd/nfssvc.c | 15 ++
> > fs/nfsd/state.h | 2 -
> > include/linux/sunrpc/svc.h | 1 +
> > include/uapi/linux/nfs.h | 54 ++++++++
> > 6 files changed, 364 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > index 33f80d289d63..4626a0002ceb 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -17,6 +17,9 @@
> > #include <linux/sunrpc/rpc_pipe_fs.h>
> > #include <linux/module.h>
> > #include <linux/fsnotify.h>
> > +#include <net/genetlink.h>
> > +#include <net/ip.h>
> > +#include <net/ipv6.h>
> >
> > #include "idmap.h"
> > #include "nfsd.h"
> > @@ -1495,6 +1498,273 @@ static int create_proc_exports_entry(void)
> >
> > unsigned int nfsd_net_id;
> >
> > +/* the netlink family */
> > +static struct genl_family nfsd_genl;
> > +
> > +static const struct nla_policy
> > +nfsd_rpc_status_compound_policy[NFS_ATTR_RPC_STATUS_COMPOUND_MAX + 1] = {
> > + [NFS_ATTR_RPC_STATUS_COMPOUND_OP] = { .type = NLA_STRING },
> > +};
> > +
> > +static const struct nla_policy
> > +nfsd_rpc_status_policy[NFS_ATTR_RPC_STATUS_MAX + 1] = {
> > + [NFS_ATTR_RPC_STATUS_XID] = { .type = NLA_U32 },
> > + [NFS_ATTR_RPC_STATUS_FLAGS] = { .type = NLA_U32 },
> > + [NFS_ATTR_RPC_STATUS_PC_NAME] = { .type = NLA_STRING },
> > + [NFS_ATTR_RPC_STATUS_VERSION] = { .type = NLA_U8 },
> > + [NFS_ATTR_RPC_STATUS_STIME] = { .type = NLA_S64 },
> > + [NFS_ATTR_RPC_STATUS_SADDR4] = { .len = sizeof_field(struct iphdr, saddr) },
> > + [NFS_ATTR_RPC_STATUS_DADDR4] = { .len = sizeof_field(struct iphdr, daddr) },
> > + [NFS_ATTR_RPC_STATUS_SADDR6] = { .len = sizeof_field(struct ipv6hdr, saddr) },
> > + [NFS_ATTR_RPC_STATUS_DADDR6] = { .len = sizeof_field(struct ipv6hdr, daddr) },
> > + [NFS_ATTR_RPC_STATUS_SPORT] = { .type = NLA_U16 },
> > + [NFS_ATTR_RPC_STATUS_DPORT] = { .type = NLA_U16 },
> > + [NFS_ATTR_RPC_STATUS_COMPOUND] =
> > + NLA_POLICY_NESTED_ARRAY(nfsd_rpc_status_compound_policy),
> > +};
> > +
> > +static const struct nla_policy
> > +nfsd_genl_policy[NFS_ATTR_MAX + 1] = {
> > + [NFS_ATTR_RPC_STATUS] = NLA_POLICY_NESTED_ARRAY(nfsd_rpc_status_policy),
> > +};
> > +
> > +static int nfsd_genl_rpc_status_compose_msg(struct sk_buff *skb, int index,
> > + struct nfsd_genl_rqstp *rqstp)
> > +{
> > + struct nlattr *rq_attr, *comp_attr;
> > + int i;
> > +
> > + rq_attr = nla_nest_start(skb, index);
> > + if (!rq_attr)
> > + return -ENOBUFS;
> > +
> > + if (nla_put_be32(skb, NFS_ATTR_RPC_STATUS_XID, rqstp->rq_xid) ||
> > + nla_put_u32(skb, NFS_ATTR_RPC_STATUS_FLAGS, rqstp->rq_flags) ||
> > + nla_put_string(skb, NFS_ATTR_RPC_STATUS_PC_NAME, rqstp->pc_name) ||
> > + nla_put_u8(skb, NFS_ATTR_RPC_STATUS_VERSION, rqstp->rq_vers) ||
> > + nla_put_s64(skb, NFS_ATTR_RPC_STATUS_STIME,
> > + ktime_to_us(rqstp->rq_stime), NFS_ATTR_RPC_STATUS_PAD))
> > + return -ENOBUFS;
> > +
> > + switch (rqstp->saddr.sa_family) {
> > + case AF_INET: {
> > + const struct sockaddr_in *s_in, *d_in;
> > +
> > + s_in = (const struct sockaddr_in *)&rqstp->saddr;
> > + d_in = (const struct sockaddr_in *)&rqstp->daddr;
> > + if (nla_put_in_addr(skb, NFS_ATTR_RPC_STATUS_SADDR4,
> > + s_in->sin_addr.s_addr) ||
> > + nla_put_in_addr(skb, NFS_ATTR_RPC_STATUS_DADDR4,
> > + d_in->sin_addr.s_addr) ||
> > + nla_put_be16(skb, NFS_ATTR_RPC_STATUS_SPORT,
> > + s_in->sin_port) ||
> > + nla_put_be16(skb, NFS_ATTR_RPC_STATUS_DPORT,
> > + d_in->sin_port))
> > + return -ENOBUFS;
> > + break;
> > + }
> > + case AF_INET6: {
> > + const struct sockaddr_in6 *s_in, *d_in;
> > +
> > + s_in = (const struct sockaddr_in6 *)&rqstp->saddr;
> > + d_in = (const struct sockaddr_in6 *)&rqstp->daddr;
> > + if (nla_put_in6_addr(skb, NFS_ATTR_RPC_STATUS_SADDR6,
> > + &s_in->sin6_addr) ||
> > + nla_put_in6_addr(skb, NFS_ATTR_RPC_STATUS_DADDR6,
> > + &d_in->sin6_addr) ||
> > + nla_put_be16(skb, NFS_ATTR_RPC_STATUS_SPORT,
> > + s_in->sin6_port) ||
> > + nla_put_be16(skb, NFS_ATTR_RPC_STATUS_DPORT,
> > + d_in->sin6_port))
> > + return -ENOBUFS;
> > + break;
> > + }
> > + default:
> > + break;
> > + }
> > +
> > + comp_attr = nla_nest_start(skb, NFS_ATTR_RPC_STATUS_COMPOUND);
> > + if (!comp_attr)
> > + return -ENOBUFS;
> > +
> > + for (i = 0; i < rqstp->opcnt; i++) {
> > + struct nlattr *op_attr;
> > +
> > + op_attr = nla_nest_start(skb, i);
> > + if (!op_attr)
> > + return -ENOBUFS;
> > +
> > + if (nla_put_string(skb, NFS_ATTR_RPC_STATUS_COMPOUND_OP,
> > + nfsd4_op_name(rqstp->opnum[i])))
> > + return -ENOBUFS;
> > +
> > + nla_nest_end(skb, op_attr);
> > + }
> > +
> > + nla_nest_end(skb, comp_attr);
> > + nla_nest_end(skb, rq_attr);
> > +
> > + return 0;
> > +}
> > +
> > +static int nfsd_genl_get_rpc_status(struct sk_buff *skb, struct genl_info *info)
> > +{
> > + struct nfsd_net *nn = net_generic(genl_info_net(info), nfsd_net_id);
> > + struct nlattr *rpc_attr;
> > + int i, rqstp_index = 0;
> > + struct sk_buff *msg;
> > + void *hdr;
> > +
> > + msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> > + if (!msg)
> > + return -ENOMEM;
> > +
> > + hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq, &nfsd_genl,
> > + 0, NFS_CMD_NEW_RPC_STATUS);
> > + if (!hdr) {
> > + nlmsg_free(msg);
> > + return -ENOBUFS;
> > + }
> > +
> > + rpc_attr = nla_nest_start(msg, NFS_ATTR_RPC_STATUS);
> > + if (!rpc_attr)
> > + goto nla_put_failure;
> > +
> > + rcu_read_lock();
> > +
> > + for (i = 0; i < nn->nfsd_serv->sv_nrpools; i++) {
> > + struct svc_rqst *rqstp;
> > +
> > + list_for_each_entry_rcu(rqstp,
> > + &nn->nfsd_serv->sv_pools[i].sp_all_threads,
> > + rq_all) {
> > + struct nfsd_genl_rqstp genl_rqstp;
> > + unsigned int status_counter;
> > +
> > + /*
> > + * Acquire rq_status_counter before parsing the rqst
> > + * fields. rq_status_counter is set to an odd value in
> > + * order to notify the consumers the rqstp fields are
> > + * meaningful.
> > + */
> > + status_counter =
> > + smp_load_acquire(&rqstp->rq_status_counter);
> > + if (!(status_counter & 1))
> > + continue;
> > +
> > + genl_rqstp.rq_xid = rqstp->rq_xid;
> > + genl_rqstp.rq_flags = rqstp->rq_flags;
> > + genl_rqstp.rq_vers = rqstp->rq_vers;
> > + genl_rqstp.pc_name = svc_proc_name(rqstp);
> > + genl_rqstp.rq_stime = rqstp->rq_stime;
> > + genl_rqstp.opcnt = 0;
> > + memcpy(&genl_rqstp.daddr, svc_daddr(rqstp),
> > + sizeof(struct sockaddr));
> > + memcpy(&genl_rqstp.saddr, svc_addr(rqstp),
> > + sizeof(struct sockaddr));
> > +
> > +#ifdef CONFIG_NFSD_V4
> > + if (rqstp->rq_vers == NFS4_VERSION &&
> > + rqstp->rq_proc == NFSPROC4_COMPOUND) {
> > + /* NFSv4 compund */
> > + struct nfsd4_compoundargs *args;
> > + int j;
> > +
> > + args = rqstp->rq_argp;
> > + genl_rqstp.opcnt = args->opcnt;
> > + for (j = 0; j < genl_rqstp.opcnt; j++)
> > + genl_rqstp.opnum[j] =
> > + args->ops[j].opnum;
> > + }
> > +#endif /* CONFIG_NFSD_V4 */
> > +
> > + /*
> > + * Acquire rq_status_counter before reporting the rqst
> > + * fields to the user.
> > + */
> > + if (smp_load_acquire(&rqstp->rq_status_counter) !=
> > + status_counter)
> > + continue;
> > +
> > + if (nfsd_genl_rpc_status_compose_msg(msg,
> > + rqstp_index++,
> > + &genl_rqstp))
> > + goto nla_put_failure_rcu;
> > + }
> > + }
> > +
> > + rcu_read_unlock();
> > +
> > + nla_nest_end(msg, rpc_attr);
> > + genlmsg_end(msg, hdr);
> > +
> > + return genlmsg_reply(msg, info);
> > +
> > +nla_put_failure_rcu:
> > + rcu_read_unlock();
> > +nla_put_failure:
> > + genlmsg_cancel(msg, hdr);
> > + nlmsg_free(msg);
> > +
> > + return -EMSGSIZE;
> > +}
> > +
> > +static int nfsd_genl_pre_doit(const struct genl_split_ops *ops,
> > + struct sk_buff *skb, struct genl_info *info)
> > +{
> > + struct nfsd_net *nn = net_generic(genl_info_net(info), nfsd_net_id);
> > +
> > + if (ops->internal_flags & NFSD_FLAG_NEED_REF_COUNT) {
> > + int ret = -ENODEV;
> > +
> > + mutex_lock(&nfsd_mutex);
> > + if (nn->nfsd_serv) {
> > + svc_get(nn->nfsd_serv);
> > + ret = 0;
> > + }
> > + mutex_unlock(&nfsd_mutex);
> > +
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void nfsd_genl_post_doit(const struct genl_split_ops *ops,
> > + struct sk_buff *skb, struct genl_info *info)
> > +{
> > + if (ops->internal_flags & NFSD_FLAG_NEED_REF_COUNT) {
> > + mutex_lock(&nfsd_mutex);
> > + nfsd_put(genl_info_net(info));
> > + mutex_unlock(&nfsd_mutex);
> > + }
> > +}
> > +
> > +static struct genl_small_ops nfsd_genl_ops[] = {
> > + {
> > + .cmd = NFS_CMD_GET_RPC_STATUS,
> > + .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
> > + .doit = nfsd_genl_get_rpc_status,
> > + .internal_flags = NFSD_FLAG_NEED_REF_COUNT,
> > + },
> > +};
> > +
> > +static struct genl_family nfsd_genl __ro_after_init = {
> > + .name = "nfsd_server",
> > + .version = 1,
> > + .maxattr = NFS_ATTR_MAX,
> > + .module = THIS_MODULE,
> > + .netnsok = true,
> > + .parallel_ops = true,
> > + .hdrsize = 0,
> > + .pre_doit = nfsd_genl_pre_doit,
> > + .post_doit = nfsd_genl_post_doit,
> > + .policy = nfsd_genl_policy,
> > + .small_ops = nfsd_genl_ops,
> > + .n_small_ops = ARRAY_SIZE(nfsd_genl_ops),
> > + .resv_start_op = NFS_CMD_NEW_RPC_STATUS + 1,
> > +};
> > +
> > /**
> > * nfsd_net_init - Prepare the nfsd_net portion of a new net namespace
> > * @net: a freshly-created network namespace
> > @@ -1589,6 +1859,10 @@ static int __init init_nfsd(void)
> > retval = register_filesystem(&nfsd_fs_type);
> > if (retval)
> > goto out_free_all;
> > + retval = genl_register_family(&nfsd_genl);
> > + if (retval)
> > + goto out_free_all;
> > +
> > return 0;
> > out_free_all:
> > nfsd4_destroy_laundry_wq();
> > @@ -1613,6 +1887,7 @@ static int __init init_nfsd(void)
> >
> > static void __exit exit_nfsd(void)
> > {
> > + genl_unregister_family(&nfsd_genl);
> > unregister_filesystem(&nfsd_fs_type);
> > nfsd4_destroy_laundry_wq();
> > unregister_cld_notifier();
> > diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> > index e95c3322eb9b..749c871b3291 100644
> > --- a/fs/nfsd/nfsd.h
> > +++ b/fs/nfsd/nfsd.h
> > @@ -62,6 +62,25 @@ struct readdir_cd {
> > __be32 err; /* 0, nfserr, or nfserr_eof */
> > };
> >
> > +enum nfsd_genl_internal_flag {
> > + NFSD_FLAG_NEED_REF_COUNT = BIT(0),
> > +};
> > +
> > +/* Maximum number of operations per session compound */
> > +#define NFSD_MAX_OPS_PER_COMPOUND 50
> > +
> > +struct nfsd_genl_rqstp {
> > + struct sockaddr daddr;
> > + struct sockaddr saddr;
> > + unsigned long rq_flags;
> > + const char *pc_name;
> > + ktime_t rq_stime;
> > + __be32 rq_xid;
> > + u32 rq_vers;
> > + /* NFSv4 compund */
> > + u32 opnum[NFSD_MAX_OPS_PER_COMPOUND];
> > + u16 opcnt;
> > +};
> >
> > extern struct svc_program nfsd_program;
> > extern const struct svc_version nfsd_version2, nfsd_version3, nfsd_version4;
> > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> > index 1582af33e204..fad34a7325b3 100644
> > --- a/fs/nfsd/nfssvc.c
> > +++ b/fs/nfsd/nfssvc.c
> > @@ -998,6 +998,15 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
> > if (!proc->pc_decode(rqstp, &rqstp->rq_arg_stream))
> > goto out_decode_err;
> >
> > + /*
> > + * Release rq_status_counter setting it to an odd value after the rpc
> > + * request has been properly parsed. rq_status_counter is used to
> > + * notify the consumers if the rqstp fields are stable
> > + * (rq_status_counter is odd) or not meaningful (rq_status_counter
> > + * is even).
> > + */
> > + smp_store_release(&rqstp->rq_status_counter, rqstp->rq_status_counter | 1);
> > +
> > rp = NULL;
> > switch (nfsd_cache_lookup(rqstp, &rp)) {
> > case RC_DOIT:
> > @@ -1015,6 +1024,12 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
> > if (!proc->pc_encode(rqstp, &rqstp->rq_res_stream))
> > goto out_encode_err;
> >
> > + /*
> > + * Release rq_status_counter setting it to an even value after the rpc
> > + * request has been properly processed.
> > + */
> > + smp_store_release(&rqstp->rq_status_counter, rqstp->rq_status_counter + 1);
> > +
> > nfsd_cache_update(rqstp, rp, rqstp->rq_cachetype, statp + 1);
> > out_cached_reply:
> > return 1;
> > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> > index cbddcf484dba..41bdc913fa71 100644
> > --- a/fs/nfsd/state.h
> > +++ b/fs/nfsd/state.h
> > @@ -174,8 +174,6 @@ static inline struct nfs4_delegation *delegstateid(struct nfs4_stid *s)
> >
> > /* Maximum number of slots per session. 160 is useful for long haul TCP */
> > #define NFSD_MAX_SLOTS_PER_SESSION 160
> > -/* Maximum number of operations per session compound */
> > -#define NFSD_MAX_OPS_PER_COMPOUND 50
> > /* Maximum session per slot cache size */
> > #define NFSD_SLOT_CACHE_SIZE 2048
> > /* Maximum number of NFSD_SLOT_CACHE_SIZE slots per session */
> > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
> > index dbf5b21feafe..caa20defd255 100644
> > --- a/include/linux/sunrpc/svc.h
> > +++ b/include/linux/sunrpc/svc.h
> > @@ -251,6 +251,7 @@ struct svc_rqst {
> > * net namespace
> > */
> > void ** rq_lease_breaker; /* The v4 client breaking a lease */
> > + unsigned int rq_status_counter; /* RPC processing counter */
> > };
> >
> > /* bits for rq_flags */
> > diff --git a/include/uapi/linux/nfs.h b/include/uapi/linux/nfs.h
> > index 946cb62d64b0..86a5daaaf9d9 100644
> > --- a/include/uapi/linux/nfs.h
> > +++ b/include/uapi/linux/nfs.h
> > @@ -132,4 +132,58 @@ enum nfs_ftype {
> > NFFIFO = 8
> > };
> >
> > +enum nfs_commands {
> > + NFS_CMD_UNSPEC,
> > +
> > + NFS_CMD_GET_RPC_STATUS,
> > + NFS_CMD_NEW_RPC_STATUS,
> > +
> > + /* add new commands above here */
> > +
> > + __NFS_CMD_MAX,
> > + NFS_CMD_MAX = __NFS_CMD_MAX - 1,
> > +};
> > +
> > +enum nfs_rcp_status_compound_attrs {
> > + __NFS_ATTR_RPC_STATUS_COMPOUND_UNSPEC,
> > + NFS_ATTR_RPC_STATUS_COMPOUND_OP,
> > +
> > + /* keep it last */
> > + NUM_NFS_ATTR_RPC_STATUS_COMPOUND,
> > + NFS_ATTR_RPC_STATUS_COMPOUND_MAX = NUM_NFS_ATTR_RPC_STATUS_COMPOUND - 1,
> > +};
> > +
> > +enum nfs_rpc_status_attrs {
> > + __NFS_ATTR_RPC_STATUS_UNSPEC,
> > +
> > + NFS_ATTR_RPC_STATUS_XID,
> > + NFS_ATTR_RPC_STATUS_FLAGS,
> > + NFS_ATTR_RPC_STATUS_PC_NAME,
> > + NFS_ATTR_RPC_STATUS_VERSION,
> > + NFS_ATTR_RPC_STATUS_STIME,
> > + NFS_ATTR_RPC_STATUS_SADDR4,
> > + NFS_ATTR_RPC_STATUS_DADDR4,
> > + NFS_ATTR_RPC_STATUS_SADDR6,
> > + NFS_ATTR_RPC_STATUS_DADDR6,
> > + NFS_ATTR_RPC_STATUS_SPORT,
> > + NFS_ATTR_RPC_STATUS_DPORT,
> > + NFS_ATTR_RPC_STATUS_PAD,
> > + NFS_ATTR_RPC_STATUS_COMPOUND,
> > +
> > + /* keep it last */
> > + NUM_NFS_ATTR_RPC_STATUS,
> > + NFS_ATTR_RPC_STATUS_MAX = NUM_NFS_ATTR_RPC_STATUS - 1,
> > +};
> > +
> > +enum nfs_attrs {
> > + NFS_ATTR_UNSPEC,
> > +
> > + NFS_ATTR_RPC_STATUS,
> > +
> > + /* add new attributes above here */
> > +
> > + __NFS_ATTR_MAX,
> > + NFS_ATTR_MAX = __NFS_ATTR_MAX - 1
> > +};
> > +
> > #endif /* _UAPI_LINUX_NFS_H */
> > --
> > 2.41.0
> >
>
> --
> Chuck Lever
>

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