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 nfs_seqid_counter; 48 struct nfs4_minor_version_ops { 49 u32 minor_version; 50 unsigned init_caps; 51 52 int (*init_client)(struct nfs_client *); 53 void (*shutdown_client)(struct nfs_client *); 54 bool (*match_stateid)(const nfs4_stateid *, 55 const nfs4_stateid *); 56 int (*find_root_sec)(struct nfs_server *, struct nfs_fh *, 57 struct nfs_fsinfo *); 58 void (*free_lock_state)(struct nfs_server *, 59 struct nfs4_lock_state *); 60 struct nfs_seqid * 61 (*alloc_seqid)(struct nfs_seqid_counter *, gfp_t); 62 const struct rpc_call_ops *call_sync_ops; 63 const struct nfs4_state_recovery_ops *reboot_recovery_ops; 64 const struct nfs4_state_recovery_ops *nograce_recovery_ops; 65 const struct nfs4_state_maintenance_ops *state_renewal_ops; 66 const struct nfs4_mig_recovery_ops *mig_recovery_ops; 67 }; 68 69 #define NFS_SEQID_CONFIRMED 1 70 struct nfs_seqid_counter { 71 ktime_t create_time; 72 int owner_id; 73 int flags; 74 u32 counter; 75 spinlock_t lock; /* Protects the list */ 76 struct list_head list; /* Defines sequence of RPC calls */ 77 struct rpc_wait_queue wait; /* RPC call delay queue */ 78 }; 79 80 struct nfs_seqid { 81 struct nfs_seqid_counter *sequence; 82 struct list_head list; 83 struct rpc_task *task; 84 }; 85 86 static inline void nfs_confirm_seqid(struct nfs_seqid_counter *seqid, int status) 87 { 88 if (seqid_mutating_err(-status)) 89 seqid->flags |= NFS_SEQID_CONFIRMED; 90 } 91 92 /* 93 * NFS4 state_owners and lock_owners are simply labels for ordered 94 * sequences of RPC calls. Their sole purpose is to provide once-only 95 * semantics by allowing the server to identify replayed requests. 96 */ 97 struct nfs4_state_owner { 98 struct nfs_server *so_server; 99 struct list_head so_lru; 100 unsigned long so_expires; 101 struct rb_node so_server_node; 102 103 struct rpc_cred *so_cred; /* Associated cred */ 104 105 spinlock_t so_lock; 106 atomic_t so_count; 107 unsigned long so_flags; 108 struct list_head so_states; 109 struct nfs_seqid_counter so_seqid; 110 seqcount_t so_reclaim_seqcount; 111 struct mutex so_delegreturn_mutex; 112 }; 113 114 enum { 115 NFS_OWNER_RECLAIM_REBOOT, 116 NFS_OWNER_RECLAIM_NOGRACE 117 }; 118 119 #define NFS_LOCK_NEW 0 120 #define NFS_LOCK_RECLAIM 1 121 #define NFS_LOCK_EXPIRED 2 122 123 /* 124 * struct nfs4_state maintains the client-side state for a given 125 * (state_owner,inode) tuple (OPEN) or state_owner (LOCK). 126 * 127 * OPEN: 128 * In order to know when to OPEN_DOWNGRADE or CLOSE the state on the server, 129 * we need to know how many files are open for reading or writing on a 130 * given inode. This information too is stored here. 131 * 132 * LOCK: one nfs4_state (LOCK) to hold the lock stateid nfs4_state(OPEN) 133 */ 134 135 struct nfs4_lock_state { 136 struct list_head ls_locks; /* Other lock stateids */ 137 struct nfs4_state * ls_state; /* Pointer to open state */ 138 #define NFS_LOCK_INITIALIZED 0 139 #define NFS_LOCK_LOST 1 140 unsigned long ls_flags; 141 struct nfs_seqid_counter ls_seqid; 142 nfs4_stateid ls_stateid; 143 atomic_t ls_count; 144 fl_owner_t ls_owner; 145 }; 146 147 /* bits for nfs4_state->flags */ 148 enum { 149 LK_STATE_IN_USE, 150 NFS_DELEGATED_STATE, /* Current stateid is delegation */ 151 NFS_OPEN_STATE, /* OPEN stateid is set */ 152 NFS_O_RDONLY_STATE, /* OPEN stateid has read-only state */ 153 NFS_O_WRONLY_STATE, /* OPEN stateid has write-only state */ 154 NFS_O_RDWR_STATE, /* OPEN stateid has read/write state */ 155 NFS_STATE_RECLAIM_REBOOT, /* OPEN stateid server rebooted */ 156 NFS_STATE_RECLAIM_NOGRACE, /* OPEN stateid needs to recover state */ 157 NFS_STATE_POSIX_LOCKS, /* Posix locks are supported */ 158 NFS_STATE_RECOVERY_FAILED, /* OPEN stateid state recovery failed */ 159 }; 160 161 struct nfs4_state { 162 struct list_head open_states; /* List of states for the same state_owner */ 163 struct list_head inode_states; /* List of states for the same inode */ 164 struct list_head lock_states; /* List of subservient lock stateids */ 165 166 struct nfs4_state_owner *owner; /* Pointer to the open owner */ 167 struct inode *inode; /* Pointer to the inode */ 168 169 unsigned long flags; /* Do we hold any locks? */ 170 spinlock_t state_lock; /* Protects the lock_states list */ 171 172 seqlock_t seqlock; /* Protects the stateid/open_stateid */ 173 nfs4_stateid stateid; /* Current stateid: may be delegation */ 174 nfs4_stateid open_stateid; /* OPEN stateid */ 175 176 /* The following 3 fields are protected by owner->so_lock */ 177 unsigned int n_rdonly; /* Number of read-only references */ 178 unsigned int n_wronly; /* Number of write-only references */ 179 unsigned int n_rdwr; /* Number of read/write references */ 180 fmode_t state; /* State on the server (R,W, or RW) */ 181 atomic_t count; 182 }; 183 184 185 struct nfs4_exception { 186 struct nfs4_state *state; 187 struct inode *inode; 188 nfs4_stateid *stateid; 189 long timeout; 190 unsigned char delay : 1, 191 recovering : 1, 192 retry : 1; 193 }; 194 195 struct nfs4_state_recovery_ops { 196 int owner_flag_bit; 197 int state_flag_bit; 198 int (*recover_open)(struct nfs4_state_owner *, struct nfs4_state *); 199 int (*recover_lock)(struct nfs4_state *, struct file_lock *); 200 int (*establish_clid)(struct nfs_client *, struct rpc_cred *); 201 int (*reclaim_complete)(struct nfs_client *, struct rpc_cred *); 202 int (*detect_trunking)(struct nfs_client *, struct nfs_client **, 203 struct rpc_cred *); 204 }; 205 206 struct nfs4_state_maintenance_ops { 207 int (*sched_state_renewal)(struct nfs_client *, struct rpc_cred *, unsigned); 208 struct rpc_cred * (*get_state_renewal_cred_locked)(struct nfs_client *); 209 int (*renew_lease)(struct nfs_client *, struct rpc_cred *); 210 }; 211 212 struct nfs4_mig_recovery_ops { 213 int (*get_locations)(struct inode *, struct nfs4_fs_locations *, 214 struct page *, struct rpc_cred *); 215 int (*fsid_present)(struct inode *, struct rpc_cred *); 216 }; 217 218 extern const struct dentry_operations nfs4_dentry_operations; 219 220 /* dir.c */ 221 int nfs_atomic_open(struct inode *, struct dentry *, struct file *, 222 unsigned, umode_t, int *); 223 224 /* super.c */ 225 extern struct file_system_type nfs4_fs_type; 226 227 /* nfs4namespace.c */ 228 struct rpc_clnt *nfs4_negotiate_security(struct rpc_clnt *, struct inode *, struct qstr *); 229 struct vfsmount *nfs4_submount(struct nfs_server *, struct dentry *, 230 struct nfs_fh *, struct nfs_fattr *); 231 int nfs4_replace_transport(struct nfs_server *server, 232 const struct nfs4_fs_locations *locations); 233 234 /* nfs4proc.c */ 235 extern int nfs4_handle_exception(struct nfs_server *, int, struct nfs4_exception *); 236 extern int nfs4_call_sync(struct rpc_clnt *, struct nfs_server *, 237 struct rpc_message *, struct nfs4_sequence_args *, 238 struct nfs4_sequence_res *, int); 239 extern void nfs4_init_sequence(struct nfs4_sequence_args *, struct nfs4_sequence_res *, int); 240 extern int nfs4_proc_setclientid(struct nfs_client *, u32, unsigned short, struct rpc_cred *, struct nfs4_setclientid_res *); 241 extern int nfs4_proc_setclientid_confirm(struct nfs_client *, struct nfs4_setclientid_res *arg, struct rpc_cred *); 242 extern int nfs4_proc_get_rootfh(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *, bool); 243 extern int nfs4_proc_bind_conn_to_session(struct nfs_client *, struct rpc_cred *cred); 244 extern int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred); 245 extern int nfs4_destroy_clientid(struct nfs_client *clp); 246 extern int nfs4_init_clientid(struct nfs_client *, struct rpc_cred *); 247 extern int nfs41_init_clientid(struct nfs_client *, struct rpc_cred *); 248 extern int nfs4_do_close(struct nfs4_state *state, gfp_t gfp_mask, int wait); 249 extern int nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *fhandle); 250 extern int nfs4_proc_fs_locations(struct rpc_clnt *, struct inode *, const struct qstr *, 251 struct nfs4_fs_locations *, struct page *); 252 extern int nfs4_proc_get_locations(struct inode *, struct nfs4_fs_locations *, 253 struct page *page, struct rpc_cred *); 254 extern int nfs4_proc_fsid_present(struct inode *, struct rpc_cred *); 255 extern struct rpc_clnt *nfs4_proc_lookup_mountpoint(struct inode *, struct qstr *, 256 struct nfs_fh *, struct nfs_fattr *); 257 extern int nfs4_proc_secinfo(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *); 258 extern const struct xattr_handler *nfs4_xattr_handlers[]; 259 extern int nfs4_set_rw_stateid(nfs4_stateid *stateid, 260 const struct nfs_open_context *ctx, 261 const struct nfs_lock_context *l_ctx, 262 fmode_t fmode); 263 264 #if defined(CONFIG_NFS_V4_1) 265 static inline struct nfs4_session *nfs4_get_session(const struct nfs_server *server) 266 { 267 return server->nfs_client->cl_session; 268 } 269 270 extern int nfs41_setup_sequence(struct nfs4_session *session, 271 struct nfs4_sequence_args *args, struct nfs4_sequence_res *res, 272 struct rpc_task *task); 273 extern int nfs41_sequence_done(struct rpc_task *, struct nfs4_sequence_res *); 274 extern int nfs4_proc_create_session(struct nfs_client *, struct rpc_cred *); 275 extern int nfs4_proc_destroy_session(struct nfs4_session *, struct rpc_cred *); 276 extern int nfs4_proc_get_lease_time(struct nfs_client *clp, 277 struct nfs_fsinfo *fsinfo); 278 extern int nfs4_proc_layoutcommit(struct nfs4_layoutcommit_data *data, 279 bool sync); 280 281 static inline bool 282 is_ds_only_client(struct nfs_client *clp) 283 { 284 return (clp->cl_exchange_flags & EXCHGID4_FLAG_MASK_PNFS) == 285 EXCHGID4_FLAG_USE_PNFS_DS; 286 } 287 288 static inline bool 289 is_ds_client(struct nfs_client *clp) 290 { 291 return clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_DS; 292 } 293 294 static inline bool 295 _nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_mode, 296 struct rpc_clnt **clntp, struct rpc_message *msg) 297 { 298 struct rpc_cred *newcred = NULL; 299 rpc_authflavor_t flavor; 300 301 if (test_bit(sp4_mode, &clp->cl_sp4_flags)) { 302 spin_lock(&clp->cl_lock); 303 if (clp->cl_machine_cred != NULL) 304 /* don't call get_rpccred on the machine cred - 305 * a reference will be held for life of clp */ 306 newcred = clp->cl_machine_cred; 307 spin_unlock(&clp->cl_lock); 308 msg->rpc_cred = newcred; 309 310 flavor = clp->cl_rpcclient->cl_auth->au_flavor; 311 WARN_ON_ONCE(flavor != RPC_AUTH_GSS_KRB5I && 312 flavor != RPC_AUTH_GSS_KRB5P); 313 *clntp = clp->cl_rpcclient; 314 315 return true; 316 } 317 return false; 318 } 319 320 /* 321 * Function responsible for determining if an rpc_message should use the 322 * machine cred under SP4_MACH_CRED and if so switching the credential and 323 * authflavor (using the nfs_client's rpc_clnt which will be krb5i/p). 324 * Should be called before rpc_call_sync/rpc_call_async. 325 */ 326 static inline void 327 nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_mode, 328 struct rpc_clnt **clntp, struct rpc_message *msg) 329 { 330 _nfs4_state_protect(clp, sp4_mode, clntp, msg); 331 } 332 333 /* 334 * Special wrapper to nfs4_state_protect for write. 335 * If WRITE can use machine cred but COMMIT cannot, make sure all writes 336 * that use machine cred use NFS_FILE_SYNC. 337 */ 338 static inline void 339 nfs4_state_protect_write(struct nfs_client *clp, struct rpc_clnt **clntp, 340 struct rpc_message *msg, struct nfs_pgio_header *hdr) 341 { 342 if (_nfs4_state_protect(clp, NFS_SP4_MACH_CRED_WRITE, clntp, msg) && 343 !test_bit(NFS_SP4_MACH_CRED_COMMIT, &clp->cl_sp4_flags)) 344 hdr->args.stable = NFS_FILE_SYNC; 345 } 346 #else /* CONFIG_NFS_v4_1 */ 347 static inline struct nfs4_session *nfs4_get_session(const struct nfs_server *server) 348 { 349 return NULL; 350 } 351 352 static inline bool 353 is_ds_only_client(struct nfs_client *clp) 354 { 355 return false; 356 } 357 358 static inline bool 359 is_ds_client(struct nfs_client *clp) 360 { 361 return false; 362 } 363 364 static inline void 365 nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_flags, 366 struct rpc_clnt **clntp, struct rpc_message *msg) 367 { 368 } 369 370 static inline void 371 nfs4_state_protect_write(struct nfs_client *clp, struct rpc_clnt **clntp, 372 struct rpc_message *msg, struct nfs_pgio_header *hdr) 373 { 374 } 375 #endif /* CONFIG_NFS_V4_1 */ 376 377 extern const struct nfs4_minor_version_ops *nfs_v4_minor_ops[]; 378 379 extern const u32 nfs4_fattr_bitmap[3]; 380 extern const u32 nfs4_statfs_bitmap[3]; 381 extern const u32 nfs4_pathconf_bitmap[3]; 382 extern const u32 nfs4_fsinfo_bitmap[3]; 383 extern const u32 nfs4_fs_locations_bitmap[3]; 384 385 void nfs40_shutdown_client(struct nfs_client *); 386 void nfs41_shutdown_client(struct nfs_client *); 387 int nfs40_init_client(struct nfs_client *); 388 int nfs41_init_client(struct nfs_client *); 389 void nfs4_free_client(struct nfs_client *); 390 391 struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *); 392 393 /* nfs4renewd.c */ 394 extern void nfs4_schedule_state_renewal(struct nfs_client *); 395 extern void nfs4_renewd_prepare_shutdown(struct nfs_server *); 396 extern void nfs4_kill_renewd(struct nfs_client *); 397 extern void nfs4_renew_state(struct work_struct *); 398 399 /* nfs4state.c */ 400 struct rpc_cred *nfs4_get_clid_cred(struct nfs_client *clp); 401 struct rpc_cred *nfs4_get_machine_cred_locked(struct nfs_client *clp); 402 struct rpc_cred *nfs4_get_renew_cred_locked(struct nfs_client *clp); 403 int nfs4_discover_server_trunking(struct nfs_client *clp, 404 struct nfs_client **); 405 int nfs40_discover_server_trunking(struct nfs_client *clp, 406 struct nfs_client **, struct rpc_cred *); 407 #if defined(CONFIG_NFS_V4_1) 408 int nfs41_discover_server_trunking(struct nfs_client *clp, 409 struct nfs_client **, struct rpc_cred *); 410 extern void nfs4_schedule_session_recovery(struct nfs4_session *, int); 411 extern void nfs41_notify_server(struct nfs_client *); 412 #else 413 static inline void nfs4_schedule_session_recovery(struct nfs4_session *session, int err) 414 { 415 } 416 #endif /* CONFIG_NFS_V4_1 */ 417 418 extern struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *, struct rpc_cred *, gfp_t); 419 extern void nfs4_put_state_owner(struct nfs4_state_owner *); 420 extern void nfs4_purge_state_owners(struct nfs_server *); 421 extern struct nfs4_state * nfs4_get_open_state(struct inode *, struct nfs4_state_owner *); 422 extern void nfs4_put_open_state(struct nfs4_state *); 423 extern void nfs4_close_state(struct nfs4_state *, fmode_t); 424 extern void nfs4_close_sync(struct nfs4_state *, fmode_t); 425 extern void nfs4_state_set_mode_locked(struct nfs4_state *, fmode_t); 426 extern void nfs_inode_find_state_and_recover(struct inode *inode, 427 const nfs4_stateid *stateid); 428 extern int nfs4_state_mark_reclaim_nograce(struct nfs_client *, struct nfs4_state *); 429 extern void nfs4_schedule_lease_recovery(struct nfs_client *); 430 extern int nfs4_wait_clnt_recover(struct nfs_client *clp); 431 extern int nfs4_client_recover_expired_lease(struct nfs_client *clp); 432 extern void nfs4_schedule_state_manager(struct nfs_client *); 433 extern void nfs4_schedule_path_down_recovery(struct nfs_client *clp); 434 extern int nfs4_schedule_stateid_recovery(const struct nfs_server *, struct nfs4_state *); 435 extern int nfs4_schedule_migration_recovery(const struct nfs_server *); 436 extern void nfs4_schedule_lease_moved_recovery(struct nfs_client *); 437 extern void nfs41_handle_sequence_flag_errors(struct nfs_client *clp, u32 flags); 438 extern void nfs41_handle_server_scope(struct nfs_client *, 439 struct nfs41_server_scope **); 440 extern void nfs4_put_lock_state(struct nfs4_lock_state *lsp); 441 extern int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl); 442 extern int nfs4_select_rw_stateid(struct nfs4_state *, fmode_t, 443 const struct nfs_lockowner *, nfs4_stateid *, 444 struct rpc_cred **); 445 446 extern struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask); 447 extern int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task); 448 extern void nfs_increment_open_seqid(int status, struct nfs_seqid *seqid); 449 extern void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid); 450 extern void nfs_release_seqid(struct nfs_seqid *seqid); 451 extern void nfs_free_seqid(struct nfs_seqid *seqid); 452 extern int nfs40_setup_sequence(struct nfs4_slot_table *tbl, 453 struct nfs4_sequence_args *args, 454 struct nfs4_sequence_res *res, 455 struct rpc_task *task); 456 extern int nfs4_sequence_done(struct rpc_task *task, 457 struct nfs4_sequence_res *res); 458 459 extern void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp); 460 461 extern const nfs4_stateid zero_stateid; 462 463 /* nfs4super.c */ 464 struct nfs_mount_info; 465 extern struct nfs_subversion nfs_v4; 466 struct dentry *nfs4_try_mount(int, const char *, struct nfs_mount_info *, struct nfs_subversion *); 467 extern bool nfs4_disable_idmapping; 468 extern unsigned short max_session_slots; 469 extern unsigned short send_implementation_id; 470 extern bool recover_lost_locks; 471 472 #define NFS4_CLIENT_ID_UNIQ_LEN (64) 473 extern char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN]; 474 475 /* nfs4sysctl.c */ 476 #ifdef CONFIG_SYSCTL 477 int nfs4_register_sysctl(void); 478 void nfs4_unregister_sysctl(void); 479 #else 480 static inline int nfs4_register_sysctl(void) 481 { 482 return 0; 483 } 484 485 static inline void nfs4_unregister_sysctl(void) 486 { 487 } 488 #endif 489 490 /* nfs4xdr.c */ 491 extern struct rpc_procinfo nfs4_procedures[]; 492 493 struct nfs4_mount_data; 494 495 /* callback_xdr.c */ 496 extern struct svc_version nfs4_callback_version1; 497 extern struct svc_version nfs4_callback_version4; 498 499 static inline void nfs4_stateid_copy(nfs4_stateid *dst, const nfs4_stateid *src) 500 { 501 memcpy(dst->data, src->data, sizeof(dst->data)); 502 dst->type = src->type; 503 } 504 505 static inline bool nfs4_stateid_match(const nfs4_stateid *dst, const nfs4_stateid *src) 506 { 507 if (dst->type != src->type) 508 return false; 509 return memcmp(dst->data, src->data, sizeof(dst->data)) == 0; 510 } 511 512 static inline bool nfs4_stateid_match_other(const nfs4_stateid *dst, const nfs4_stateid *src) 513 { 514 return memcmp(dst->other, src->other, NFS4_STATEID_OTHER_SIZE) == 0; 515 } 516 517 static inline bool nfs4_stateid_is_newer(const nfs4_stateid *s1, const nfs4_stateid *s2) 518 { 519 return (s32)(be32_to_cpu(s1->seqid) - be32_to_cpu(s2->seqid)) > 0; 520 } 521 522 static inline bool nfs4_valid_open_stateid(const struct nfs4_state *state) 523 { 524 return test_bit(NFS_STATE_RECOVERY_FAILED, &state->flags) == 0; 525 } 526 527 #else 528 529 #define nfs4_close_state(a, b) do { } while (0) 530 #define nfs4_close_sync(a, b) do { } while (0) 531 #define nfs4_state_protect(a, b, c, d) do { } while (0) 532 #define nfs4_state_protect_write(a, b, c, d) do { } while (0) 533 534 #endif /* CONFIG_NFS_V4 */ 535 #endif /* __LINUX_FS_NFS_NFS4_FS.H */ 536