diff --git a/fs/nfs_common/Makefile b/fs/nfs_common/Makefile
index e58b01bb8dda..a5e54809701e 100644
--- a/fs/nfs_common/Makefile
+++ b/fs/nfs_common/Makefile
@@ -6,6 +6,9 @@
 obj-$(CONFIG_NFS_ACL_SUPPORT) += nfs_acl.o
 nfs_acl-objs := nfsacl.o
 
+obj-$(CONFIG_NFS_COMMON_LOCALIO_SUPPORT) += nfs_localio.o
+nfs_localio-objs := nfslocalio.o
+
 obj-$(CONFIG_GRACE_PERIOD) += grace.o
 obj-$(CONFIG_NFS_V4_2_SSC_HELPER) += nfs_ssc.o
 
diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c
new file mode 100644
index 000000000000..f59167e596d3
--- /dev/null
+++ b/fs/nfs_common/nfslocalio.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
+ */
+
+#include <linux/module.h>
+#include <linux/rculist.h>
+#include <linux/nfslocalio.h>
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("NFS localio protocol bypass support");
+
+DEFINE_MUTEX(nfs_uuid_mutex);
+
+/*
+ * Global list of nfs_uuid_t instances, add/remove
+ * is protected by nfs_uuid_mutex.
+ * Reads are protected by RCU read lock (see below).
+ */
+LIST_HEAD(nfs_uuids);
+
+void nfs_uuid_begin(nfs_uuid_t *nfs_uuid)
+{
+	nfs_uuid->net = NULL;
+	nfs_uuid->dom = NULL;
+	uuid_gen(&nfs_uuid->uuid);
+
+	mutex_lock(&nfs_uuid_mutex);
+	list_add_tail_rcu(&nfs_uuid->list, &nfs_uuids);
+	mutex_unlock(&nfs_uuid_mutex);
+}
+EXPORT_SYMBOL_GPL(nfs_uuid_begin);
+
+void nfs_uuid_end(nfs_uuid_t *nfs_uuid)
+{
+	mutex_lock(&nfs_uuid_mutex);
+	list_del_rcu(&nfs_uuid->list);
+	mutex_unlock(&nfs_uuid_mutex);
+}
+EXPORT_SYMBOL_GPL(nfs_uuid_end);
+
+/* Must be called with RCU read lock held. */
+static nfs_uuid_t * nfs_uuid_lookup(const uuid_t *uuid)
+{
+	nfs_uuid_t *nfs_uuid;
+
+	list_for_each_entry_rcu(nfs_uuid, &nfs_uuids, list)
+		if (uuid_equal(&nfs_uuid->uuid, uuid))
+			return nfs_uuid;
+
+	return NULL;
+}
+
+bool nfs_uuid_is_local(const uuid_t *uuid, struct net *net, struct auth_domain *dom)
+{
+	bool is_local = false;
+	nfs_uuid_t *nfs_uuid;
+
+	rcu_read_lock();
+	nfs_uuid = nfs_uuid_lookup(uuid);
+	if (nfs_uuid) {
+		is_local = true;
+		nfs_uuid->net = net;
+		kref_get(&dom->ref);
+		nfs_uuid->dom = dom;
+	}
+	rcu_read_unlock();
+
+	return is_local;
+}
+EXPORT_SYMBOL_GPL(nfs_uuid_is_local);
+
+/*
+ * The nfs localio code needs to call into nfsd using various symbols (below),
+ * but cannot be statically linked, because that will make the nfs module
+ * depend on the nfsd module.
+ *
+ * Instead, do dynamic linking to the nfsd module (via nfs_common module). The
+ * nfs_common module will only hold a reference on nfsd when localio is in use.
+ * This allows some sanity checking, like giving up on localio if nfsd isn't loaded.
+ */
+DEFINE_MUTEX(nfs_to_nfsd_mutex);
+nfs_to_nfsd_t nfs_to;
+EXPORT_SYMBOL_GPL(nfs_to);
+
+/* Macro to define nfs_to get and put methods, avoids copy-n-paste bugs */
+#define DEFINE_NFS_TO_NFSD_SYMBOL(NFSD_SYMBOL)		\
+static nfs_to_##NFSD_SYMBOL##_t get_##NFSD_SYMBOL(void)	\
+{							\
+	return symbol_request(NFSD_SYMBOL);		\
+}							\
+static void put_##NFSD_SYMBOL(void)			\
+{							\
+	symbol_put(NFSD_SYMBOL);			\
+	nfs_to.NFSD_SYMBOL = NULL;			\
+}
+
+/* The nfs localio code needs to call into nfsd to map filehandle -> struct nfsd_file */
+extern int nfsd_open_local_fh(struct net *, struct auth_domain *, struct rpc_clnt *,
+			      const struct cred *, const struct nfs_fh *,
+			      const fmode_t, struct nfsd_file **);
+DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_open_local_fh);
+
+/* The nfs localio code needs to call into nfsd to acquire the nfsd_file */
+extern struct nfsd_file *nfsd_file_get(struct nfsd_file *nf);
+DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_file_get);
+
+/* The nfs localio code needs to call into nfsd to release the nfsd_file */
+extern void nfsd_file_put(struct nfsd_file *nf);
+DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_file_put);
+
+/* The nfs localio code needs to call into nfsd to access the nf->nf_file */
+extern struct file * nfsd_file_file(struct nfsd_file *nf);
+DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_file_file);
+#undef DEFINE_NFS_TO_NFSD_SYMBOL
+
+bool get_nfs_to_nfsd_symbols(void)
+{
+	mutex_lock(&nfs_to_nfsd_mutex);
+
+	/* Only get symbols on first reference */
+	if (refcount_read(&nfs_to.ref) == 0)
+		refcount_set(&nfs_to.ref, 1);
+	else {
+		refcount_inc(&nfs_to.ref);
+		mutex_unlock(&nfs_to_nfsd_mutex);
+		return true;
+	}
+
+	nfs_to.nfsd_open_local_fh = get_nfsd_open_local_fh();
+	if (!nfs_to.nfsd_open_local_fh)
+		goto out_nfsd_open_local_fh;
+
+	nfs_to.nfsd_file_get = get_nfsd_file_get();
+	if (!nfs_to.nfsd_file_get)
+		goto out_nfsd_file_get;
+
+	nfs_to.nfsd_file_put = get_nfsd_file_put();
+	if (!nfs_to.nfsd_file_put)
+		goto out_nfsd_file_put;
+
+	nfs_to.nfsd_file_file = get_nfsd_file_file();
+	if (!nfs_to.nfsd_file_file)
+		goto out_nfsd_file_file;
+
+	mutex_unlock(&nfs_to_nfsd_mutex);
+	return true;
+
+out_nfsd_file_file:
+	put_nfsd_file_put();
+out_nfsd_file_put:
+	put_nfsd_file_get();
+out_nfsd_file_get:
+	put_nfsd_open_local_fh();
+out_nfsd_open_local_fh:
+	mutex_unlock(&nfs_to_nfsd_mutex);
+	return false;
+}
+EXPORT_SYMBOL_GPL(get_nfs_to_nfsd_symbols);
+
+void put_nfs_to_nfsd_symbols(void)
+{
+	mutex_lock(&nfs_to_nfsd_mutex);
+
+	if (!refcount_dec_and_test(&nfs_to.ref))
+		goto out;
+
+	put_nfsd_open_local_fh();
+	put_nfsd_file_get();
+	put_nfsd_file_put();
+	put_nfsd_file_file();
+out:
+	mutex_unlock(&nfs_to_nfsd_mutex);
+}
+EXPORT_SYMBOL_GPL(put_nfs_to_nfsd_symbols);
+
+static int __init nfslocalio_init(void)
+{
+	refcount_set(&nfs_to.ref, 0);
+
+	nfs_to.nfsd_open_local_fh = NULL;
+	nfs_to.nfsd_file_get = NULL;
+	nfs_to.nfsd_file_put = NULL;
+	nfs_to.nfsd_file_file = NULL;
+
+	return 0;
+}
+
+static void __exit nfslocalio_exit(void)
+{
+}
+
+module_init(nfslocalio_init);
+module_exit(nfslocalio_exit);
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 94ecb9ed0ed1..2a79c45ca27a 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -39,6 +39,7 @@
 #include <linux/fsnotify.h>
 #include <linux/seq_file.h>
 #include <linux/rhashtable.h>
+#include <linux/nfslocalio.h>
 
 #include "vfs.h"
 #include "nfsd.h"
@@ -345,6 +346,10 @@ nfsd_file_get(struct nfsd_file *nf)
 		return nf;
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(nfsd_file_get);
+
+/* Compile time type checking, not used by anything */
+static nfs_to_nfsd_file_get_t __maybe_unused nfsd_file_get_typecheck = nfsd_file_get;
 
 /**
  * nfsd_file_put - put the reference to a nfsd_file
@@ -389,6 +394,26 @@ nfsd_file_put(struct nfsd_file *nf)
 	if (refcount_dec_and_test(&nf->nf_ref))
 		nfsd_file_free(nf);
 }
+EXPORT_SYMBOL_GPL(nfsd_file_put);
+
+/* Compile time type checking, not used by anything */
+static nfs_to_nfsd_file_put_t __maybe_unused nfsd_file_put_typecheck = nfsd_file_put;
+
+/**
+ * nfsd_file_file - get the backing file of an nfsd_file
+ * @nf: nfsd_file of which to access the backing file.
+ *
+ * Return backing file for @nf.
+ */
+struct file *
+nfsd_file_file(struct nfsd_file *nf)
+{
+	return nf->nf_file;
+}
+EXPORT_SYMBOL_GPL(nfsd_file_file);
+
+/* Compile time type checking, not used by anything */
+static nfs_to_nfsd_file_file_t __maybe_unused nfsd_file_file_typecheck = nfsd_file_file;
 
 static void
 nfsd_file_dispose_list(struct list_head *dispose)
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 6dab41f8541e..ab8a4423edd9 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -56,6 +56,7 @@ int nfsd_file_cache_start_net(struct net *net);
 void nfsd_file_cache_shutdown_net(struct net *net);
 void nfsd_file_put(struct nfsd_file *nf);
 struct nfsd_file *nfsd_file_get(struct nfsd_file *nf);
+struct file *nfsd_file_file(struct nfsd_file *nf);
 void nfsd_file_close_inode_sync(struct inode *inode);
 void nfsd_file_net_dispose(struct nfsd_net *nn);
 bool nfsd_file_is_cached(struct inode *inode);
diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h
new file mode 100644
index 000000000000..7e09ff621d93
--- /dev/null
+++ b/include/linux/nfslocalio.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
+ */
+#ifndef __LINUX_NFSLOCALIO_H
+#define __LINUX_NFSLOCALIO_H
+
+#include <linux/list.h>
+#include <linux/uuid.h>
+#include <linux/refcount.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/svcauth.h>
+#include <linux/nfs.h>
+#include <net/net_namespace.h>
+
+/*
+ * Useful to allow a client to negotiate if localio
+ * possible with its server.
+ *
+ * See Documentation/filesystems/nfs/localio.rst for more detail.
+ */
+typedef struct {
+	uuid_t uuid;
+	struct list_head list;
+	struct net *net; /* nfsd's network namespace */
+	struct auth_domain *dom; /* auth_domain for localio */
+} nfs_uuid_t;
+
+void nfs_uuid_begin(nfs_uuid_t *);
+void nfs_uuid_end(nfs_uuid_t *);
+bool nfs_uuid_is_local(const uuid_t *, struct net *, struct auth_domain *);
+
+struct nfsd_file;
+
+typedef int (*nfs_to_nfsd_open_local_fh_t)(struct net *, struct auth_domain *,
+				struct rpc_clnt *, const struct cred *,
+				const struct nfs_fh *, const fmode_t,
+				struct nfsd_file **);
+typedef struct nfsd_file * (*nfs_to_nfsd_file_get_t)(struct nfsd_file *);
+typedef void (*nfs_to_nfsd_file_put_t)(struct nfsd_file *);
+typedef struct file * (*nfs_to_nfsd_file_file_t)(struct nfsd_file *);
+
+typedef struct {
+	refcount_t			ref;
+	nfs_to_nfsd_open_local_fh_t	nfsd_open_local_fh;
+	nfs_to_nfsd_file_get_t		nfsd_file_get;
+	nfs_to_nfsd_file_put_t		nfsd_file_put;
+	nfs_to_nfsd_file_file_t		nfsd_file_file;
+} nfs_to_nfsd_t;
+
+extern nfs_to_nfsd_t nfs_to;
+
+bool get_nfs_to_nfsd_symbols(void);
+void put_nfs_to_nfsd_symbols(void);
+
+#endif  /* __LINUX_NFSLOCALIO_H */
