xref: /openbmc/linux/fs/nfs/nfs4_fs.h (revision 867a0e05)
1 /*
2  * linux/fs/nfs/nfs4_fs.h
3  *
4  * Copyright (C) 2005 Trond Myklebust
5  *
6  * NFSv4-specific filesystem definitions and declarations
7  */
8 
9 #ifndef __LINUX_FS_NFS_NFS4_FS_H
10 #define __LINUX_FS_NFS_NFS4_FS_H
11 
12 #if defined(CONFIG_NFS_V4_2)
13 #define NFS4_MAX_MINOR_VERSION 2
14 #elif defined(CONFIG_NFS_V4_1)
15 #define NFS4_MAX_MINOR_VERSION 1
16 #else
17 #define NFS4_MAX_MINOR_VERSION 0
18 #endif
19 
20 #if IS_ENABLED(CONFIG_NFS_V4)
21 
22 #define NFS4_MAX_LOOP_ON_RECOVER (10)
23 
24 #include <linux/seqlock.h>
25 
26 struct idmap;
27 
28 enum nfs4_client_state {
29 	NFS4CLNT_MANAGER_RUNNING  = 0,
30 	NFS4CLNT_CHECK_LEASE,
31 	NFS4CLNT_LEASE_EXPIRED,
32 	NFS4CLNT_RECLAIM_REBOOT,
33 	NFS4CLNT_RECLAIM_NOGRACE,
34 	NFS4CLNT_DELEGRETURN,
35 	NFS4CLNT_SESSION_RESET,
36 	NFS4CLNT_LEASE_CONFIRM,
37 	NFS4CLNT_SERVER_SCOPE_MISMATCH,
38 	NFS4CLNT_PURGE_STATE,
39 	NFS4CLNT_BIND_CONN_TO_SESSION,
40 	NFS4CLNT_MOVED,
41 	NFS4CLNT_LEASE_MOVED,
42 };
43 
44 #define NFS4_RENEW_TIMEOUT		0x01
45 #define NFS4_RENEW_DELEGATION_CB	0x02
46 
47 struct nfs4_minor_version_ops {
48 	u32	minor_version;
49 	unsigned init_caps;
50 
51 	int	(*init_client)(struct nfs_client *);
52 	void	(*shutdown_client)(struct nfs_client *);
53 	bool	(*match_stateid)(const nfs4_stateid *,
54 			const nfs4_stateid *);
55 	int	(*find_root_sec)(struct nfs_server *, struct nfs_fh *,
56 			struct nfs_fsinfo *);
57 	void	(*free_lock_state)(struct nfs_server *,
58 			struct nfs4_lock_state *);
59 	const struct rpc_call_ops *call_sync_ops;
60 	const struct nfs4_state_recovery_ops *reboot_recovery_ops;
61 	const struct nfs4_state_recovery_ops *nograce_recovery_ops;
62 	const struct nfs4_state_maintenance_ops *state_renewal_ops;
63 	const struct nfs4_mig_recovery_ops *mig_recovery_ops;
64 };
65 
66 #define NFS_SEQID_CONFIRMED 1
67 struct nfs_seqid_counter {
68 	ktime_t create_time;
69 	int owner_id;
70 	int flags;
71 	u32 counter;
72 	spinlock_t lock;		/* Protects the list */
73 	struct list_head list;		/* Defines sequence of RPC calls */
74 	struct rpc_wait_queue	wait;	/* RPC call delay queue */
75 };
76 
77 struct nfs_seqid {
78 	struct nfs_seqid_counter *sequence;
79 	struct list_head list;
80 	struct rpc_task *task;
81 };
82 
83 static inline void nfs_confirm_seqid(struct nfs_seqid_counter *seqid, int status)
84 {
85 	if (seqid_mutating_err(-status))
86 		seqid->flags |= NFS_SEQID_CONFIRMED;
87 }
88 
89 /*
90  * NFS4 state_owners and lock_owners are simply labels for ordered
91  * sequences of RPC calls. Their sole purpose is to provide once-only
92  * semantics by allowing the server to identify replayed requests.
93  */
94 struct nfs4_state_owner {
95 	struct nfs_server    *so_server;
96 	struct list_head     so_lru;
97 	unsigned long        so_expires;
98 	struct rb_node	     so_server_node;
99 
100 	struct rpc_cred	     *so_cred;	 /* Associated cred */
101 
102 	spinlock_t	     so_lock;
103 	atomic_t	     so_count;
104 	unsigned long	     so_flags;
105 	struct list_head     so_states;
106 	struct nfs_seqid_counter so_seqid;
107 	seqcount_t	     so_reclaim_seqcount;
108 	struct mutex	     so_delegreturn_mutex;
109 };
110 
111 enum {
112 	NFS_OWNER_RECLAIM_REBOOT,
113 	NFS_OWNER_RECLAIM_NOGRACE
114 };
115 
116 #define NFS_LOCK_NEW		0
117 #define NFS_LOCK_RECLAIM	1
118 #define NFS_LOCK_EXPIRED	2
119 
120 /*
121  * struct nfs4_state maintains the client-side state for a given
122  * (state_owner,inode) tuple (OPEN) or state_owner (LOCK).
123  *
124  * OPEN:
125  * In order to know when to OPEN_DOWNGRADE or CLOSE the state on the server,
126  * we need to know how many files are open for reading or writing on a
127  * given inode. This information too is stored here.
128  *
129  * LOCK: one nfs4_state (LOCK) to hold the lock stateid nfs4_state(OPEN)
130  */
131 
132 struct nfs4_lock_state {
133 	struct list_head	ls_locks;	/* Other lock stateids */
134 	struct nfs4_state *	ls_state;	/* Pointer to open state */
135 #define NFS_LOCK_INITIALIZED 0
136 #define NFS_LOCK_LOST        1
137 	unsigned long		ls_flags;
138 	struct nfs_seqid_counter	ls_seqid;
139 	nfs4_stateid		ls_stateid;
140 	atomic_t		ls_count;
141 	fl_owner_t		ls_owner;
142 };
143 
144 /* bits for nfs4_state->flags */
145 enum {
146 	LK_STATE_IN_USE,
147 	NFS_DELEGATED_STATE,		/* Current stateid is delegation */
148 	NFS_OPEN_STATE,			/* OPEN stateid is set */
149 	NFS_O_RDONLY_STATE,		/* OPEN stateid has read-only state */
150 	NFS_O_WRONLY_STATE,		/* OPEN stateid has write-only state */
151 	NFS_O_RDWR_STATE,		/* OPEN stateid has read/write state */
152 	NFS_STATE_RECLAIM_REBOOT,	/* OPEN stateid server rebooted */
153 	NFS_STATE_RECLAIM_NOGRACE,	/* OPEN stateid needs to recover state */
154 	NFS_STATE_POSIX_LOCKS,		/* Posix locks are supported */
155 	NFS_STATE_RECOVERY_FAILED,	/* OPEN stateid state recovery failed */
156 };
157 
158 struct nfs4_state {
159 	struct list_head open_states;	/* List of states for the same state_owner */
160 	struct list_head inode_states;	/* List of states for the same inode */
161 	struct list_head lock_states;	/* List of subservient lock stateids */
162 
163 	struct nfs4_state_owner *owner;	/* Pointer to the open owner */
164 	struct inode *inode;		/* Pointer to the inode */
165 
166 	unsigned long flags;		/* Do we hold any locks? */
167 	spinlock_t state_lock;		/* Protects the lock_states list */
168 
169 	seqlock_t seqlock;		/* Protects the stateid/open_stateid */
170 	nfs4_stateid stateid;		/* Current stateid: may be delegation */
171 	nfs4_stateid open_stateid;	/* OPEN stateid */
172 
173 	/* The following 3 fields are protected by owner->so_lock */
174 	unsigned int n_rdonly;		/* Number of read-only references */
175 	unsigned int n_wronly;		/* Number of write-only references */
176 	unsigned int n_rdwr;		/* Number of read/write references */
177 	fmode_t state;			/* State on the server (R,W, or RW) */
178 	atomic_t count;
179 };
180 
181 
182 struct nfs4_exception {
183 	long timeout;
184 	int retry;
185 	struct nfs4_state *state;
186 	struct inode *inode;
187 };
188 
189 struct nfs4_state_recovery_ops {
190 	int owner_flag_bit;
191 	int state_flag_bit;
192 	int (*recover_open)(struct nfs4_state_owner *, struct nfs4_state *);
193 	int (*recover_lock)(struct nfs4_state *, struct file_lock *);
194 	int (*establish_clid)(struct nfs_client *, struct rpc_cred *);
195 	int (*reclaim_complete)(struct nfs_client *, struct rpc_cred *);
196 	int (*detect_trunking)(struct nfs_client *, struct nfs_client **,
197 		struct rpc_cred *);
198 };
199 
200 struct nfs4_state_maintenance_ops {
201 	int (*sched_state_renewal)(struct nfs_client *, struct rpc_cred *, unsigned);
202 	struct rpc_cred * (*get_state_renewal_cred_locked)(struct nfs_client *);
203 	int (*renew_lease)(struct nfs_client *, struct rpc_cred *);
204 };
205 
206 struct nfs4_mig_recovery_ops {
207 	int (*get_locations)(struct inode *, struct nfs4_fs_locations *,
208 		struct page *, struct rpc_cred *);
209 	int (*fsid_present)(struct inode *, struct rpc_cred *);
210 };
211 
212 extern const struct dentry_operations nfs4_dentry_operations;
213 
214 /* dir.c */
215 int nfs_atomic_open(struct inode *, struct dentry *, struct file *,
216 		    unsigned, umode_t, int *);
217 
218 /* super.c */
219 extern struct file_system_type nfs4_fs_type;
220 
221 /* nfs4namespace.c */
222 struct rpc_clnt *nfs4_negotiate_security(struct rpc_clnt *, struct inode *, struct qstr *);
223 struct vfsmount *nfs4_submount(struct nfs_server *, struct dentry *,
224 			       struct nfs_fh *, struct nfs_fattr *);
225 int nfs4_replace_transport(struct nfs_server *server,
226 				const struct nfs4_fs_locations *locations);
227 
228 /* nfs4proc.c */
229 extern int nfs4_handle_exception(struct nfs_server *, int, struct nfs4_exception *);
230 extern int nfs4_call_sync(struct rpc_clnt *, struct nfs_server *,
231 			  struct rpc_message *, struct nfs4_sequence_args *,
232 			  struct nfs4_sequence_res *, int);
233 extern int nfs4_proc_setclientid(struct nfs_client *, u32, unsigned short, struct rpc_cred *, struct nfs4_setclientid_res *);
234 extern int nfs4_proc_setclientid_confirm(struct nfs_client *, struct nfs4_setclientid_res *arg, struct rpc_cred *);
235 extern int nfs4_proc_get_rootfh(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *, bool);
236 extern int nfs4_proc_bind_conn_to_session(struct nfs_client *, struct rpc_cred *cred);
237 extern int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred);
238 extern int nfs4_destroy_clientid(struct nfs_client *clp);
239 extern int nfs4_init_clientid(struct nfs_client *, struct rpc_cred *);
240 extern int nfs41_init_clientid(struct nfs_client *, struct rpc_cred *);
241 extern int nfs4_do_close(struct nfs4_state *state, gfp_t gfp_mask, int wait);
242 extern int nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *fhandle);
243 extern int nfs4_proc_fs_locations(struct rpc_clnt *, struct inode *, const struct qstr *,
244 				  struct nfs4_fs_locations *, struct page *);
245 extern int nfs4_proc_get_locations(struct inode *, struct nfs4_fs_locations *,
246 		struct page *page, struct rpc_cred *);
247 extern int nfs4_proc_fsid_present(struct inode *, struct rpc_cred *);
248 extern struct rpc_clnt *nfs4_proc_lookup_mountpoint(struct inode *, struct qstr *,
249 			    struct nfs_fh *, struct nfs_fattr *);
250 extern int nfs4_proc_secinfo(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *);
251 extern const struct xattr_handler *nfs4_xattr_handlers[];
252 extern int nfs4_set_rw_stateid(nfs4_stateid *stateid,
253 		const struct nfs_open_context *ctx,
254 		const struct nfs_lock_context *l_ctx,
255 		fmode_t fmode);
256 
257 #if defined(CONFIG_NFS_V4_1)
258 static inline struct nfs4_session *nfs4_get_session(const struct nfs_server *server)
259 {
260 	return server->nfs_client->cl_session;
261 }
262 
263 extern int nfs41_setup_sequence(struct nfs4_session *session,
264 		struct nfs4_sequence_args *args, struct nfs4_sequence_res *res,
265 		struct rpc_task *task);
266 extern int nfs41_sequence_done(struct rpc_task *, struct nfs4_sequence_res *);
267 extern int nfs4_proc_create_session(struct nfs_client *, struct rpc_cred *);
268 extern int nfs4_proc_destroy_session(struct nfs4_session *, struct rpc_cred *);
269 extern int nfs4_proc_get_lease_time(struct nfs_client *clp,
270 		struct nfs_fsinfo *fsinfo);
271 extern int nfs4_proc_layoutcommit(struct nfs4_layoutcommit_data *data,
272 				  bool sync);
273 
274 static inline bool
275 is_ds_only_client(struct nfs_client *clp)
276 {
277 	return (clp->cl_exchange_flags & EXCHGID4_FLAG_MASK_PNFS) ==
278 		EXCHGID4_FLAG_USE_PNFS_DS;
279 }
280 
281 static inline bool
282 is_ds_client(struct nfs_client *clp)
283 {
284 	return clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_DS;
285 }
286 
287 static inline bool
288 _nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_mode,
289 		    struct rpc_clnt **clntp, struct rpc_message *msg)
290 {
291 	struct rpc_cred *newcred = NULL;
292 	rpc_authflavor_t flavor;
293 
294 	if (test_bit(sp4_mode, &clp->cl_sp4_flags)) {
295 		spin_lock(&clp->cl_lock);
296 		if (clp->cl_machine_cred != NULL)
297 			/* don't call get_rpccred on the machine cred -
298 			 * a reference will be held for life of clp */
299 			newcred = clp->cl_machine_cred;
300 		spin_unlock(&clp->cl_lock);
301 		msg->rpc_cred = newcred;
302 
303 		flavor = clp->cl_rpcclient->cl_auth->au_flavor;
304 		WARN_ON_ONCE(flavor != RPC_AUTH_GSS_KRB5I &&
305 			     flavor != RPC_AUTH_GSS_KRB5P);
306 		*clntp = clp->cl_rpcclient;
307 
308 		return true;
309 	}
310 	return false;
311 }
312 
313 /*
314  * Function responsible for determining if an rpc_message should use the
315  * machine cred under SP4_MACH_CRED and if so switching the credential and
316  * authflavor (using the nfs_client's rpc_clnt which will be krb5i/p).
317  * Should be called before rpc_call_sync/rpc_call_async.
318  */
319 static inline void
320 nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_mode,
321 		   struct rpc_clnt **clntp, struct rpc_message *msg)
322 {
323 	_nfs4_state_protect(clp, sp4_mode, clntp, msg);
324 }
325 
326 /*
327  * Special wrapper to nfs4_state_protect for write.
328  * If WRITE can use machine cred but COMMIT cannot, make sure all writes
329  * that use machine cred use NFS_FILE_SYNC.
330  */
331 static inline void
332 nfs4_state_protect_write(struct nfs_client *clp, struct rpc_clnt **clntp,
333 			 struct rpc_message *msg, struct nfs_pgio_header *hdr)
334 {
335 	if (_nfs4_state_protect(clp, NFS_SP4_MACH_CRED_WRITE, clntp, msg) &&
336 	    !test_bit(NFS_SP4_MACH_CRED_COMMIT, &clp->cl_sp4_flags))
337 		hdr->args.stable = NFS_FILE_SYNC;
338 }
339 #else /* CONFIG_NFS_v4_1 */
340 static inline struct nfs4_session *nfs4_get_session(const struct nfs_server *server)
341 {
342 	return NULL;
343 }
344 
345 static inline bool
346 is_ds_only_client(struct nfs_client *clp)
347 {
348 	return false;
349 }
350 
351 static inline bool
352 is_ds_client(struct nfs_client *clp)
353 {
354 	return false;
355 }
356 
357 static inline void
358 nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_flags,
359 		   struct rpc_clnt **clntp, struct rpc_message *msg)
360 {
361 }
362 
363 static inline void
364 nfs4_state_protect_write(struct nfs_client *clp, struct rpc_clnt **clntp,
365 			 struct rpc_message *msg, struct nfs_pgio_header *hdr)
366 {
367 }
368 #endif /* CONFIG_NFS_V4_1 */
369 
370 extern const struct nfs4_minor_version_ops *nfs_v4_minor_ops[];
371 
372 extern const u32 nfs4_fattr_bitmap[3];
373 extern const u32 nfs4_statfs_bitmap[3];
374 extern const u32 nfs4_pathconf_bitmap[3];
375 extern const u32 nfs4_fsinfo_bitmap[3];
376 extern const u32 nfs4_fs_locations_bitmap[3];
377 
378 void nfs40_shutdown_client(struct nfs_client *);
379 void nfs41_shutdown_client(struct nfs_client *);
380 int nfs40_init_client(struct nfs_client *);
381 int nfs41_init_client(struct nfs_client *);
382 void nfs4_free_client(struct nfs_client *);
383 
384 struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *);
385 
386 /* nfs4renewd.c */
387 extern void nfs4_schedule_state_renewal(struct nfs_client *);
388 extern void nfs4_renewd_prepare_shutdown(struct nfs_server *);
389 extern void nfs4_kill_renewd(struct nfs_client *);
390 extern void nfs4_renew_state(struct work_struct *);
391 
392 /* nfs4state.c */
393 struct rpc_cred *nfs4_get_clid_cred(struct nfs_client *clp);
394 struct rpc_cred *nfs4_get_machine_cred_locked(struct nfs_client *clp);
395 struct rpc_cred *nfs4_get_renew_cred_locked(struct nfs_client *clp);
396 int nfs4_discover_server_trunking(struct nfs_client *clp,
397 			struct nfs_client **);
398 int nfs40_discover_server_trunking(struct nfs_client *clp,
399 			struct nfs_client **, struct rpc_cred *);
400 #if defined(CONFIG_NFS_V4_1)
401 int nfs41_discover_server_trunking(struct nfs_client *clp,
402 			struct nfs_client **, struct rpc_cred *);
403 extern void nfs4_schedule_session_recovery(struct nfs4_session *, int);
404 extern void nfs41_server_notify_target_slotid_update(struct nfs_client *clp);
405 extern void nfs41_server_notify_highest_slotid_update(struct nfs_client *clp);
406 
407 #else
408 static inline void nfs4_schedule_session_recovery(struct nfs4_session *session, int err)
409 {
410 }
411 #endif /* CONFIG_NFS_V4_1 */
412 
413 extern struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *, struct rpc_cred *, gfp_t);
414 extern void nfs4_put_state_owner(struct nfs4_state_owner *);
415 extern void nfs4_purge_state_owners(struct nfs_server *);
416 extern struct nfs4_state * nfs4_get_open_state(struct inode *, struct nfs4_state_owner *);
417 extern void nfs4_put_open_state(struct nfs4_state *);
418 extern void nfs4_close_state(struct nfs4_state *, fmode_t);
419 extern void nfs4_close_sync(struct nfs4_state *, fmode_t);
420 extern void nfs4_state_set_mode_locked(struct nfs4_state *, fmode_t);
421 extern void nfs_inode_find_state_and_recover(struct inode *inode,
422 		const nfs4_stateid *stateid);
423 extern int nfs4_state_mark_reclaim_nograce(struct nfs_client *, struct nfs4_state *);
424 extern void nfs4_schedule_lease_recovery(struct nfs_client *);
425 extern int nfs4_wait_clnt_recover(struct nfs_client *clp);
426 extern int nfs4_client_recover_expired_lease(struct nfs_client *clp);
427 extern void nfs4_schedule_state_manager(struct nfs_client *);
428 extern void nfs4_schedule_path_down_recovery(struct nfs_client *clp);
429 extern int nfs4_schedule_stateid_recovery(const struct nfs_server *, struct nfs4_state *);
430 extern int nfs4_schedule_migration_recovery(const struct nfs_server *);
431 extern void nfs4_schedule_lease_moved_recovery(struct nfs_client *);
432 extern void nfs41_handle_sequence_flag_errors(struct nfs_client *clp, u32 flags);
433 extern void nfs41_handle_server_scope(struct nfs_client *,
434 				      struct nfs41_server_scope **);
435 extern void nfs4_put_lock_state(struct nfs4_lock_state *lsp);
436 extern int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl);
437 extern int nfs4_select_rw_stateid(nfs4_stateid *, struct nfs4_state *,
438 		fmode_t, const struct nfs_lockowner *);
439 
440 extern struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask);
441 extern int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task);
442 extern void nfs_increment_open_seqid(int status, struct nfs_seqid *seqid);
443 extern void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid);
444 extern void nfs_release_seqid(struct nfs_seqid *seqid);
445 extern void nfs_free_seqid(struct nfs_seqid *seqid);
446 
447 extern void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp);
448 
449 extern const nfs4_stateid zero_stateid;
450 
451 /* nfs4super.c */
452 struct nfs_mount_info;
453 extern struct nfs_subversion nfs_v4;
454 struct dentry *nfs4_try_mount(int, const char *, struct nfs_mount_info *, struct nfs_subversion *);
455 extern bool nfs4_disable_idmapping;
456 extern unsigned short max_session_slots;
457 extern unsigned short send_implementation_id;
458 extern bool recover_lost_locks;
459 
460 #define NFS4_CLIENT_ID_UNIQ_LEN		(64)
461 extern char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN];
462 
463 /* nfs4sysctl.c */
464 #ifdef CONFIG_SYSCTL
465 int nfs4_register_sysctl(void);
466 void nfs4_unregister_sysctl(void);
467 #else
468 static inline int nfs4_register_sysctl(void)
469 {
470 	return 0;
471 }
472 
473 static inline void nfs4_unregister_sysctl(void)
474 {
475 }
476 #endif
477 
478 /* nfs4xdr.c */
479 extern struct rpc_procinfo nfs4_procedures[];
480 
481 struct nfs4_mount_data;
482 
483 /* callback_xdr.c */
484 extern struct svc_version nfs4_callback_version1;
485 extern struct svc_version nfs4_callback_version4;
486 
487 static inline void nfs4_stateid_copy(nfs4_stateid *dst, const nfs4_stateid *src)
488 {
489 	memcpy(dst, src, sizeof(*dst));
490 }
491 
492 static inline bool nfs4_stateid_match(const nfs4_stateid *dst, const nfs4_stateid *src)
493 {
494 	return memcmp(dst, src, sizeof(*dst)) == 0;
495 }
496 
497 static inline bool nfs4_stateid_match_other(const nfs4_stateid *dst, const nfs4_stateid *src)
498 {
499 	return memcmp(dst->other, src->other, NFS4_STATEID_OTHER_SIZE) == 0;
500 }
501 
502 static inline bool nfs4_stateid_is_newer(const nfs4_stateid *s1, const nfs4_stateid *s2)
503 {
504 	return (s32)(be32_to_cpu(s1->seqid) - be32_to_cpu(s2->seqid)) > 0;
505 }
506 
507 static inline bool nfs4_valid_open_stateid(const struct nfs4_state *state)
508 {
509 	return test_bit(NFS_STATE_RECOVERY_FAILED, &state->flags) == 0;
510 }
511 
512 #else
513 
514 #define nfs4_close_state(a, b) do { } while (0)
515 #define nfs4_close_sync(a, b) do { } while (0)
516 #define nfs4_state_protect(a, b, c, d) do { } while (0)
517 #define nfs4_state_protect_write(a, b, c, d) do { } while (0)
518 
519 #endif /* CONFIG_NFS_V4 */
520 #endif /* __LINUX_FS_NFS_NFS4_FS.H */
521