linux/fs/nfs_common/nfslocalio.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2024 Mike Snitzer <[email protected]>
 * Copyright (C) 2024 NeilBrown <[email protected]>
 */

#include <linux/module.h>
#include <linux/rculist.h>
#include <linux/nfslocalio.h>
#include <net/netns/generic.h>

MODULE_LICENSE(…) …;
MODULE_DESCRIPTION(…) …;

static DEFINE_SPINLOCK(nfs_uuid_lock);

/*
 * Global list of nfs_uuid_t instances
 * that is protected by nfs_uuid_lock.
 */
static LIST_HEAD(nfs_uuids);

void nfs_uuid_begin(nfs_uuid_t *nfs_uuid)
{ … }
EXPORT_SYMBOL_GPL(…);

void nfs_uuid_end(nfs_uuid_t *nfs_uuid)
{ … }
EXPORT_SYMBOL_GPL(…);

static nfs_uuid_t * nfs_uuid_lookup_locked(const uuid_t *uuid)
{ … }

static struct module *nfsd_mod;

void nfs_uuid_is_local(const uuid_t *uuid, struct list_head *list,
		       struct net *net, struct auth_domain *dom,
		       struct module *mod)
{ … }
EXPORT_SYMBOL_GPL(…);

static void nfs_uuid_put_locked(nfs_uuid_t *nfs_uuid)
{ … }

void nfs_uuid_invalidate_clients(struct list_head *list)
{ … }
EXPORT_SYMBOL_GPL(…);

void nfs_uuid_invalidate_one_client(nfs_uuid_t *nfs_uuid)
{ … }
EXPORT_SYMBOL_GPL(…);

struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid,
		   struct rpc_clnt *rpc_clnt, const struct cred *cred,
		   const struct nfs_fh *nfs_fh, const fmode_t fmode)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * The NFS LOCALIO code needs to call into NFSD using various symbols,
 * but cannot be statically linked, because that will make the NFS
 * module always depend on the NFSD module.
 *
 * 'nfs_to' provides NFS access to NFSD functions needed for LOCALIO,
 * its lifetime is tightly coupled to the NFSD module and will always
 * be available to NFS LOCALIO because any successful client<->server
 * LOCALIO handshake results in a reference on the NFSD module (above),
 * so NFS implicitly holds a reference to the NFSD module and its
 * functions in the 'nfs_to' nfsd_localio_operations cannot disappear.
 *
 * If the last NFS client using LOCALIO disconnects (and its reference
 * on NFSD dropped) then NFSD could be unloaded, resulting in 'nfs_to'
 * functions being invalid pointers. But if NFSD isn't loaded then NFS
 * will not be able to handshake with NFSD and will have no cause to
 * try to call 'nfs_to' function pointers. If/when NFSD is reloaded it
 * will reinitialize the 'nfs_to' function pointers and make LOCALIO
 * possible.
 */
const struct nfsd_localio_operations *nfs_to;
EXPORT_SYMBOL_GPL(…);