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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
4 * Copyright (C) 2024 NeilBrown <neilb@suse.de>
5 */
6#ifndef __LINUX_NFSLOCALIO_H
7#define __LINUX_NFSLOCALIO_H
8
9/* nfsd_file structure is purposely kept opaque to NFS client */
10struct nfsd_file;
11
12#if IS_ENABLED(CONFIG_NFS_LOCALIO)
13
14#include <linux/module.h>
15#include <linux/list.h>
16#include <linux/uuid.h>
17#include <linux/sunrpc/clnt.h>
18#include <linux/sunrpc/svcauth.h>
19#include <linux/nfs.h>
20#include <net/net_namespace.h>
21
22/*
23 * Useful to allow a client to negotiate if localio
24 * possible with its server.
25 *
26 * See Documentation/filesystems/nfs/localio.rst for more detail.
27 */
28typedef struct {
29 uuid_t uuid;
30 struct list_head list;
31 struct net __rcu *net; /* nfsd's network namespace */
32 struct auth_domain *dom; /* auth_domain for localio */
33} nfs_uuid_t;
34
35void nfs_uuid_init(nfs_uuid_t *);
36bool nfs_uuid_begin(nfs_uuid_t *);
37void nfs_uuid_end(nfs_uuid_t *);
38void nfs_uuid_is_local(const uuid_t *, struct list_head *,
39 struct net *, struct auth_domain *, struct module *);
40void nfs_uuid_invalidate_clients(struct list_head *list);
41void nfs_uuid_invalidate_one_client(nfs_uuid_t *nfs_uuid);
42
43/* localio needs to map filehandle -> struct nfsd_file */
44extern struct nfsd_file *
45nfsd_open_local_fh(struct net *, struct auth_domain *, struct rpc_clnt *,
46 const struct cred *, const struct nfs_fh *,
47 const fmode_t) __must_hold(rcu);
48
49struct nfsd_localio_operations {
50 bool (*nfsd_serv_try_get)(struct net *);
51 void (*nfsd_serv_put)(struct net *);
52 struct nfsd_file *(*nfsd_open_local_fh)(struct net *,
53 struct auth_domain *,
54 struct rpc_clnt *,
55 const struct cred *,
56 const struct nfs_fh *,
57 const fmode_t);
58 struct net *(*nfsd_file_put_local)(struct nfsd_file *);
59 struct file *(*nfsd_file_file)(struct nfsd_file *);
60} ____cacheline_aligned;
61
62extern void nfsd_localio_ops_init(void);
63extern const struct nfsd_localio_operations *nfs_to;
64
65struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *,
66 struct rpc_clnt *, const struct cred *,
67 const struct nfs_fh *, const fmode_t);
68
69static inline void nfs_to_nfsd_net_put(struct net *net)
70{
71 /*
72 * Once reference to nfsd_serv is dropped, NFSD could be
73 * unloaded, so ensure safe return from nfsd_file_put_local()
74 * by always taking RCU.
75 */
76 rcu_read_lock();
77 nfs_to->nfsd_serv_put(net);
78 rcu_read_unlock();
79}
80
81static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio)
82{
83 /*
84 * Must not hold RCU otherwise nfsd_file_put() can easily trigger:
85 * "Voluntary context switch within RCU read-side critical section!"
86 * by scheduling deep in underlying filesystem (e.g. XFS).
87 */
88 struct net *net = nfs_to->nfsd_file_put_local(localio);
89
90 nfs_to_nfsd_net_put(net);
91}
92
93#else /* CONFIG_NFS_LOCALIO */
94static inline void nfsd_localio_ops_init(void)
95{
96}
97static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio)
98{
99}
100#endif /* CONFIG_NFS_LOCALIO */
101
102#endif /* __LINUX_NFSLOCALIO_H */