include/linux/nfslocalio.h

   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 */
  10 struct 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  */
  28 typedef 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
  35 void nfs_uuid_init(nfs_uuid_t *);
  36 bool nfs_uuid_begin(nfs_uuid_t *);
  37 void nfs_uuid_end(nfs_uuid_t *);
  38 void nfs_uuid_is_local(const uuid_t *, struct list_head *,
  39                        struct net *, struct auth_domain *, struct module *);
  40 void nfs_uuid_invalidate_clients(struct list_head *list);
  41 void nfs_uuid_invalidate_one_client(nfs_uuid_t *nfs_uuid);
  42
  43 /* localio needs to map filehandle -> struct nfsd_file */
  44 extern struct nfsd_file *
  45 nfsd_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
  49 struct 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
  62 extern void nfsd_localio_ops_init(void);
  63 extern const struct nfsd_localio_operations *nfs_to;
  64
  65 struct 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
  69 static 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
  81 static 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 */
  94 static inline void nfsd_localio_ops_init(void)
  95 {
  96 }
  97 static 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 */