[PATCH v11 19/20] nfs: implement client support for NFS_LOCALIO_PROGRAM

Mike Snitzer
2024-07-02T16:28:58Z

LOCALIOPROC_GETUUID allows a client to discover the server's uuid.

nfs_local_probe() will retrieve server's uuid via LOCALIO protocol and
verify the server with that uuid it is known to be local. This ensures
client and server 1: support localio 2: are local to each other.

All the knowledge of the LOCALIO RPC protocol is in fs/nfs/localio.c
which implements just a single version (1) that is used independently
of what NFS version is used.

Get nfsd_open_local_fh and store it in rpc_client during client
creation, put the symbol during nfs_local_disable -- which is also
called during client destruction.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
[neilb: factored out and simplified single localio protocol]
Co-developed-by: NeilBrown <neil@brown.name>
Signed-off-by: NeilBrown <neil@brown.name>
---
fs/nfs/client.c | 6 +-
fs/nfs/localio.c | 153 +++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 152 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 1300c388f971..6faa9fdc444d 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -434,8 +434,10 @@ struct nfs_client *nfs_get_client(const struct nfs_client_initdata *cl_init)
list_add_tail(&new->cl_share_link,
&nn->nfs_client_list);
spin_unlock(&nn->nfs_client_lock);
- nfs_local_probe(new);
- return rpc_ops->init_client(new, cl_init);
+ new = rpc_ops->init_client(new, cl_init);
+ if (!IS_ERR(new))
+ nfs_local_probe(new);
+ return new;
}

spin_unlock(&nn->nfs_client_lock);
diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
index 7039a181ff89..08d8f661ebe9 100644
--- a/fs/nfs/localio.c
+++ b/fs/nfs/localio.c
@@ -15,6 +15,7 @@
#include <linux/sunrpc/addr.h>
#include <linux/inetdevice.h>
#include <net/addrconf.h>
+#include <linux/nfslocalio.h>
#include <linux/module.h>
#include <linux/bvec.h>

@@ -124,18 +125,76 @@ nfs4errno(int errno)
static bool localio_enabled __read_mostly = true;
module_param(localio_enabled, bool, 0644);

+static inline bool nfs_client_is_local(const struct nfs_client *clp)
+{
+ return !!test_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
+}
+
bool nfs_server_is_local(const struct nfs_client *clp)
{
- return test_bit(NFS_CS_LOCAL_IO, &clp->cl_flags) != 0 &&
- localio_enabled;
+ return nfs_client_is_local(clp) && localio_enabled;
}
EXPORT_SYMBOL_GPL(nfs_server_is_local);

+/*
+ * GETUUID XDR functions
+ */
+
+static void localio_xdr_enc_getuuidargs(struct rpc_rqst *req,
+ struct xdr_stream *xdr,
+ const void *data)
+{
+ /* void function */
+}
+
+static int localio_xdr_dec_getuuidres(struct rpc_rqst *req,
+ struct xdr_stream *xdr,
+ void *result)
+{
+ u8 *uuid = result;
+
+ return decode_opaque_fixed(xdr, uuid, UUID_SIZE);
+}
+
+static const struct rpc_procinfo nfs_localio_procedures[] = {
+ [LOCALIOPROC_GETUUID] = {
+ .p_proc = LOCALIOPROC_GETUUID,
+ .p_encode = localio_xdr_enc_getuuidargs,
+ .p_decode = localio_xdr_dec_getuuidres,
+ .p_arglen = 0,
+ .p_replen = XDR_QUADLEN(UUID_SIZE),
+ .p_statidx = LOCALIOPROC_GETUUID,
+ .p_name = "GETUUID",
+ },
+};
+
+static unsigned int nfs_localio_counts[ARRAY_SIZE(nfs_localio_procedures)];
+const struct rpc_version nfslocalio_version1 = {
+ .number = 1,
+ .nrprocs = ARRAY_SIZE(nfs_localio_procedures),
+ .procs = nfs_localio_procedures,
+ .counts = nfs_localio_counts,
+};
+
+static const struct rpc_version *nfslocalio_version[] = {
+ [1] = &nfslocalio_version1,
+};
+
+extern const struct rpc_program nfslocalio_program;
+static struct rpc_stat nfslocalio_rpcstat = { &nfslocalio_program };
+
+const struct rpc_program nfslocalio_program = {
+ .name = "nfslocalio",
+ .number = NFS_LOCALIO_PROGRAM,
+ .nrvers = ARRAY_SIZE(nfslocalio_version),
+ .version = nfslocalio_version,
+ .stats = &nfslocalio_rpcstat,
+};
+
/*
* nfs_local_enable - enable local i/o for an nfs_client
*/
-static __maybe_unused void nfs_local_enable(struct nfs_client *clp,
- struct net *net)
+static void nfs_local_enable(struct nfs_client *clp, struct net *net)
{
if (READ_ONCE(clp->nfsd_open_local_fh)) {
set_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
@@ -151,15 +210,98 @@ void nfs_local_disable(struct nfs_client *clp)
{
if (test_and_clear_bit(NFS_CS_LOCAL_IO, &clp->cl_flags)) {
trace_nfs_local_disable(clp);
+ put_nfsd_open_local_fh();
+ clp->nfsd_open_local_fh = NULL;
+ if (!IS_ERR(clp->cl_rpcclient_localio)) {
+ rpc_shutdown_client(clp->cl_rpcclient_localio);
+ clp->cl_rpcclient_localio = ERR_PTR(-EINVAL);
+ }
clp->cl_nfssvc_net = NULL;
}
}

+/*
+ * nfs_init_localioclient - Initialise an NFS localio client connection
+ */
+static void nfs_init_localioclient(struct nfs_client *clp)
+{
+ if (unlikely(!IS_ERR(clp->cl_rpcclient_localio)))
+ goto out;
+ clp->cl_rpcclient_localio = rpc_bind_new_program(clp->cl_rpcclient,
+ &nfslocalio_program, 1);
+ if (IS_ERR(clp->cl_rpcclient_localio))
+ goto out;
+ /* No errors! Assume that localio is supported */
+ clp->nfsd_open_local_fh = get_nfsd_open_local_fh();
+ if (!clp->nfsd_open_local_fh) {
+ rpc_shutdown_client(clp->cl_rpcclient_localio);
+ clp->cl_rpcclient_localio = ERR_PTR(-EINVAL);
+ }
+out:
+ dprintk_rcu("%s: server (%s) %s NFS LOCALIO, nfsd_open_local_fh is %s.\n",
+ __func__, rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR),
+ (IS_ERR(clp->cl_rpcclient_localio) ? "does not support" : "supports"),
+ (clp->nfsd_open_local_fh ? "set" : "not set"));
+}
+
+static bool nfs_local_server_getuuid(struct nfs_client *clp, uuid_t *nfsd_uuid)
+{
+ u8 uuid[UUID_SIZE];
+ struct rpc_message msg = {
+ .rpc_resp = &uuid,
+ };
+ int status;
+
+ nfs_init_localioclient(clp);
+ if (IS_ERR(clp->cl_rpcclient_localio))
+ return false;
+
+ msg.rpc_proc = &nfs_localio_procedures[LOCALIOPROC_GETUUID];
+ status = rpc_call_sync(clp->cl_rpcclient_localio, &msg, 0);
+ dprintk("%s: NFS reply getuuid: status=%d uuid=%pU\n",
+ __func__, status, uuid);
+ if (status)
+ return false;
+
+ import_uuid(nfsd_uuid, uuid);
+
+ return true;
+}
+
/*
* nfs_local_probe - probe local i/o support for an nfs_server and nfs_client
+ * - called after alloc_client and init_client (so cl_rpcclient exists)
+ * - this function is idempotent, it can be called for old or new clients
*/
void nfs_local_probe(struct nfs_client *clp)
{
+ uuid_t uuid;
+ struct net *net = NULL;
+
+ if (!localio_enabled || clp->cl_rpcclient->cl_vers == 2)
+ goto unsupported;
+
+ if (nfs_client_is_local(clp)) {
+ /* If already enabled, disable and re-enable */
+ nfs_local_disable(clp);
+ }
+
+ /*
+ * Retrieve server's uuid via LOCALIO protocol and verify the
+ * server with that uuid is known to be local. This ensures
+ * client and server 1: support localio 2: are local to each other
+ * by verifying client's nfsd, with specified uuid, is local.
+ */
+ if (!nfs_local_server_getuuid(clp, &uuid) ||
+ !nfsd_uuid_is_local(&uuid, &net))
+ goto unsupported;
+
+ nfs_local_enable(clp, net);
+ return;
+
+unsupported:
+ /* localio not supported */
+ nfs_local_disable(clp);
}
EXPORT_SYMBOL_GPL(nfs_local_probe);

@@ -184,7 +326,8 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
trace_nfs_local_open_fh(fh, mode, status);
switch (status) {
case -ENXIO:
- nfs_local_disable(clp);
+ /* Revalidate localio, will disable if unsupported */
+ nfs_local_probe(clp);
fallthrough;
case -ETIMEDOUT:
status = -EAGAIN;
--
2.44.0