xref: /openbmc/linux/include/linux/nfs_fs.h (revision df2634f43f5106947f3735a0b61a6527a4b278cd)
1 /*
2  *  linux/include/linux/nfs_fs.h
3  *
4  *  Copyright (C) 1992  Rick Sladkey
5  *
6  *  OS-specific nfs filesystem definitions and declarations
7  */
8 
9 #ifndef _LINUX_NFS_FS_H
10 #define _LINUX_NFS_FS_H
11 
12 #include <linux/magic.h>
13 
14 /* Default timeout values */
15 #define NFS_DEF_UDP_TIMEO	(11)
16 #define NFS_DEF_UDP_RETRANS	(3)
17 #define NFS_DEF_TCP_TIMEO	(600)
18 #define NFS_DEF_TCP_RETRANS	(2)
19 
20 #define NFS_MAX_UDP_TIMEOUT	(60*HZ)
21 #define NFS_MAX_TCP_TIMEOUT	(600*HZ)
22 
23 #define NFS_DEF_ACREGMIN	(3)
24 #define NFS_DEF_ACREGMAX	(60)
25 #define NFS_DEF_ACDIRMIN	(30)
26 #define NFS_DEF_ACDIRMAX	(60)
27 
28 /*
29  * When flushing a cluster of dirty pages, there can be different
30  * strategies:
31  */
32 #define FLUSH_SYNC		1	/* file being synced, or contention */
33 #define FLUSH_STABLE		4	/* commit to stable storage */
34 #define FLUSH_LOWPRI		8	/* low priority background flush */
35 #define FLUSH_HIGHPRI		16	/* high priority memory reclaim flush */
36 
37 #ifdef __KERNEL__
38 
39 #include <linux/in.h>
40 #include <linux/mm.h>
41 #include <linux/pagemap.h>
42 #include <linux/rbtree.h>
43 #include <linux/rwsem.h>
44 #include <linux/wait.h>
45 
46 #include <linux/sunrpc/debug.h>
47 #include <linux/sunrpc/auth.h>
48 #include <linux/sunrpc/clnt.h>
49 
50 #include <linux/nfs.h>
51 #include <linux/nfs2.h>
52 #include <linux/nfs3.h>
53 #include <linux/nfs4.h>
54 #include <linux/nfs_xdr.h>
55 #include <linux/nfs_fs_sb.h>
56 
57 #include <linux/mempool.h>
58 
59 /*
60  * These are the default flags for swap requests
61  */
62 #define NFS_RPC_SWAPFLAGS		(RPC_TASK_SWAPPER|RPC_TASK_ROOTCREDS)
63 
64 /*
65  * NFSv3/v4 Access mode cache entry
66  */
67 struct nfs_access_entry {
68 	struct rb_node		rb_node;
69 	struct list_head	lru;
70 	unsigned long		jiffies;
71 	struct rpc_cred *	cred;
72 	int			mask;
73 };
74 
75 struct nfs_lock_context {
76 	atomic_t count;
77 	struct list_head list;
78 	struct nfs_open_context *open_context;
79 	fl_owner_t lockowner;
80 	pid_t pid;
81 };
82 
83 struct nfs4_state;
84 struct nfs_open_context {
85 	struct nfs_lock_context lock_context;
86 	struct path path;
87 	struct rpc_cred *cred;
88 	struct nfs4_state *state;
89 	fmode_t mode;
90 
91 	unsigned long flags;
92 #define NFS_CONTEXT_ERROR_WRITE		(0)
93 	int error;
94 
95 	struct list_head list;
96 
97 	__u64 dir_cookie;
98 };
99 
100 /*
101  * NFSv4 delegation
102  */
103 struct nfs_delegation;
104 
105 struct posix_acl;
106 
107 /*
108  * nfs fs inode data in memory
109  */
110 struct nfs_inode {
111 	/*
112 	 * The 64bit 'inode number'
113 	 */
114 	__u64 fileid;
115 
116 	/*
117 	 * NFS file handle
118 	 */
119 	struct nfs_fh		fh;
120 
121 	/*
122 	 * Various flags
123 	 */
124 	unsigned long		flags;			/* atomic bit ops */
125 	unsigned long		cache_validity;		/* bit mask */
126 
127 	/*
128 	 * read_cache_jiffies is when we started read-caching this inode.
129 	 * attrtimeo is for how long the cached information is assumed
130 	 * to be valid. A successful attribute revalidation doubles
131 	 * attrtimeo (up to acregmax/acdirmax), a failure resets it to
132 	 * acregmin/acdirmin.
133 	 *
134 	 * We need to revalidate the cached attrs for this inode if
135 	 *
136 	 *	jiffies - read_cache_jiffies >= attrtimeo
137 	 *
138 	 * Please note the comparison is greater than or equal
139 	 * so that zero timeout values can be specified.
140 	 */
141 	unsigned long		read_cache_jiffies;
142 	unsigned long		attrtimeo;
143 	unsigned long		attrtimeo_timestamp;
144 	__u64			change_attr;		/* v4 only */
145 
146 	unsigned long		attr_gencount;
147 	/* "Generation counter" for the attribute cache. This is
148 	 * bumped whenever we update the metadata on the
149 	 * server.
150 	 */
151 	unsigned long		cache_change_attribute;
152 
153 	struct rb_root		access_cache;
154 	struct list_head	access_cache_entry_lru;
155 	struct list_head	access_cache_inode_lru;
156 #ifdef CONFIG_NFS_V3_ACL
157 	struct posix_acl	*acl_access;
158 	struct posix_acl	*acl_default;
159 #endif
160 
161 	/*
162 	 * This is the cookie verifier used for NFSv3 readdir
163 	 * operations
164 	 */
165 	__be32			cookieverf[2];
166 
167 	/*
168 	 * This is the list of dirty unwritten pages.
169 	 */
170 	struct radix_tree_root	nfs_page_tree;
171 
172 	unsigned long		npages;
173 	unsigned long		ncommit;
174 
175 	/* Open contexts for shared mmap writes */
176 	struct list_head	open_files;
177 
178 	/* Number of in-flight sillydelete RPC calls */
179 	atomic_t		silly_count;
180 	/* List of deferred sillydelete requests */
181 	struct hlist_head	silly_list;
182 	wait_queue_head_t	waitqueue;
183 
184 #ifdef CONFIG_NFS_V4
185 	struct nfs4_cached_acl	*nfs4_acl;
186         /* NFSv4 state */
187 	struct list_head	open_states;
188 	struct nfs_delegation __rcu *delegation;
189 	fmode_t			 delegation_state;
190 	struct rw_semaphore	rwsem;
191 
192 	/* pNFS layout information */
193 	struct pnfs_layout_hdr *layout;
194 #endif /* CONFIG_NFS_V4*/
195 #ifdef CONFIG_NFS_FSCACHE
196 	struct fscache_cookie	*fscache;
197 #endif
198 	struct inode		vfs_inode;
199 };
200 
201 /*
202  * Cache validity bit flags
203  */
204 #define NFS_INO_INVALID_ATTR	0x0001		/* cached attrs are invalid */
205 #define NFS_INO_INVALID_DATA	0x0002		/* cached data is invalid */
206 #define NFS_INO_INVALID_ATIME	0x0004		/* cached atime is invalid */
207 #define NFS_INO_INVALID_ACCESS	0x0008		/* cached access cred invalid */
208 #define NFS_INO_INVALID_ACL	0x0010		/* cached acls are invalid */
209 #define NFS_INO_REVAL_PAGECACHE	0x0020		/* must revalidate pagecache */
210 #define NFS_INO_REVAL_FORCED	0x0040		/* force revalidation ignoring a delegation */
211 
212 /*
213  * Bit offsets in flags field
214  */
215 #define NFS_INO_ADVISE_RDPLUS	(0)		/* advise readdirplus */
216 #define NFS_INO_STALE		(1)		/* possible stale inode */
217 #define NFS_INO_ACL_LRU_SET	(2)		/* Inode is on the LRU list */
218 #define NFS_INO_FLUSHING	(4)		/* inode is flushing out data */
219 #define NFS_INO_FSCACHE		(5)		/* inode can be cached by FS-Cache */
220 #define NFS_INO_FSCACHE_LOCK	(6)		/* FS-Cache cookie management lock */
221 #define NFS_INO_COMMIT		(7)		/* inode is committing unstable writes */
222 
223 static inline struct nfs_inode *NFS_I(const struct inode *inode)
224 {
225 	return container_of(inode, struct nfs_inode, vfs_inode);
226 }
227 
228 static inline struct nfs_server *NFS_SB(const struct super_block *s)
229 {
230 	return (struct nfs_server *)(s->s_fs_info);
231 }
232 
233 static inline struct nfs_fh *NFS_FH(const struct inode *inode)
234 {
235 	return &NFS_I(inode)->fh;
236 }
237 
238 static inline struct nfs_server *NFS_SERVER(const struct inode *inode)
239 {
240 	return NFS_SB(inode->i_sb);
241 }
242 
243 static inline struct rpc_clnt *NFS_CLIENT(const struct inode *inode)
244 {
245 	return NFS_SERVER(inode)->client;
246 }
247 
248 static inline const struct nfs_rpc_ops *NFS_PROTO(const struct inode *inode)
249 {
250 	return NFS_SERVER(inode)->nfs_client->rpc_ops;
251 }
252 
253 static inline __be32 *NFS_COOKIEVERF(const struct inode *inode)
254 {
255 	return NFS_I(inode)->cookieverf;
256 }
257 
258 static inline unsigned NFS_MINATTRTIMEO(const struct inode *inode)
259 {
260 	struct nfs_server *nfss = NFS_SERVER(inode);
261 	return S_ISDIR(inode->i_mode) ? nfss->acdirmin : nfss->acregmin;
262 }
263 
264 static inline unsigned NFS_MAXATTRTIMEO(const struct inode *inode)
265 {
266 	struct nfs_server *nfss = NFS_SERVER(inode);
267 	return S_ISDIR(inode->i_mode) ? nfss->acdirmax : nfss->acregmax;
268 }
269 
270 static inline int NFS_STALE(const struct inode *inode)
271 {
272 	return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
273 }
274 
275 static inline int NFS_FSCACHE(const struct inode *inode)
276 {
277 	return test_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
278 }
279 
280 static inline __u64 NFS_FILEID(const struct inode *inode)
281 {
282 	return NFS_I(inode)->fileid;
283 }
284 
285 static inline void set_nfs_fileid(struct inode *inode, __u64 fileid)
286 {
287 	NFS_I(inode)->fileid = fileid;
288 }
289 
290 static inline void nfs_mark_for_revalidate(struct inode *inode)
291 {
292 	struct nfs_inode *nfsi = NFS_I(inode);
293 
294 	spin_lock(&inode->i_lock);
295 	nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS;
296 	if (S_ISDIR(inode->i_mode))
297 		nfsi->cache_validity |= NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA;
298 	spin_unlock(&inode->i_lock);
299 }
300 
301 static inline int nfs_server_capable(struct inode *inode, int cap)
302 {
303 	return NFS_SERVER(inode)->caps & cap;
304 }
305 
306 static inline int NFS_USE_READDIRPLUS(struct inode *inode)
307 {
308 	return test_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
309 }
310 
311 static inline void nfs_set_verifier(struct dentry * dentry, unsigned long verf)
312 {
313 	dentry->d_time = verf;
314 }
315 
316 /**
317  * nfs_save_change_attribute - Returns the inode attribute change cookie
318  * @dir - pointer to parent directory inode
319  * The "change attribute" is updated every time we finish an operation
320  * that will result in a metadata change on the server.
321  */
322 static inline unsigned long nfs_save_change_attribute(struct inode *dir)
323 {
324 	return NFS_I(dir)->cache_change_attribute;
325 }
326 
327 /**
328  * nfs_verify_change_attribute - Detects NFS remote directory changes
329  * @dir - pointer to parent directory inode
330  * @chattr - previously saved change attribute
331  * Return "false" if the verifiers doesn't match the change attribute.
332  * This would usually indicate that the directory contents have changed on
333  * the server, and that any dentries need revalidating.
334  */
335 static inline int nfs_verify_change_attribute(struct inode *dir, unsigned long chattr)
336 {
337 	return chattr == NFS_I(dir)->cache_change_attribute;
338 }
339 
340 /*
341  * linux/fs/nfs/inode.c
342  */
343 extern int nfs_sync_mapping(struct address_space *mapping);
344 extern void nfs_zap_mapping(struct inode *inode, struct address_space *mapping);
345 extern void nfs_zap_caches(struct inode *);
346 extern void nfs_invalidate_atime(struct inode *);
347 extern struct inode *nfs_fhget(struct super_block *, struct nfs_fh *,
348 				struct nfs_fattr *);
349 extern int nfs_refresh_inode(struct inode *, struct nfs_fattr *);
350 extern int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr);
351 extern int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr);
352 extern int nfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
353 extern int nfs_permission(struct inode *, int, unsigned int);
354 extern int nfs_open(struct inode *, struct file *);
355 extern int nfs_release(struct inode *, struct file *);
356 extern int nfs_attribute_timeout(struct inode *inode);
357 extern int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode);
358 extern int __nfs_revalidate_inode(struct nfs_server *, struct inode *);
359 extern int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping);
360 extern int nfs_setattr(struct dentry *, struct iattr *);
361 extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr);
362 extern struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx);
363 extern void put_nfs_open_context(struct nfs_open_context *ctx);
364 extern struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, fmode_t mode);
365 extern struct nfs_open_context *alloc_nfs_open_context(struct path *path, struct rpc_cred *cred, fmode_t f_mode);
366 extern void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx);
367 extern struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx);
368 extern void nfs_put_lock_context(struct nfs_lock_context *l_ctx);
369 extern u64 nfs_compat_user_ino64(u64 fileid);
370 extern void nfs_fattr_init(struct nfs_fattr *fattr);
371 extern unsigned long nfs_inc_attr_generation_counter(void);
372 
373 extern struct nfs_fattr *nfs_alloc_fattr(void);
374 
375 static inline void nfs_free_fattr(const struct nfs_fattr *fattr)
376 {
377 	kfree(fattr);
378 }
379 
380 extern struct nfs_fh *nfs_alloc_fhandle(void);
381 
382 static inline void nfs_free_fhandle(const struct nfs_fh *fh)
383 {
384 	kfree(fh);
385 }
386 
387 /*
388  * linux/fs/nfs/nfsroot.c
389  */
390 extern int  nfs_root_data(char **root_device, char **root_data); /*__init*/
391 /* linux/net/ipv4/ipconfig.c: trims ip addr off front of name, too. */
392 extern __be32 root_nfs_parse_addr(char *name); /*__init*/
393 
394 /*
395  * linux/fs/nfs/file.c
396  */
397 extern const struct inode_operations nfs_file_inode_operations;
398 #ifdef CONFIG_NFS_V3
399 extern const struct inode_operations nfs3_file_inode_operations;
400 #endif /* CONFIG_NFS_V3 */
401 extern const struct file_operations nfs_file_operations;
402 extern const struct address_space_operations nfs_file_aops;
403 extern const struct address_space_operations nfs_dir_aops;
404 
405 static inline struct nfs_open_context *nfs_file_open_context(struct file *filp)
406 {
407 	return filp->private_data;
408 }
409 
410 static inline struct rpc_cred *nfs_file_cred(struct file *file)
411 {
412 	if (file != NULL) {
413 		struct nfs_open_context *ctx =
414 			nfs_file_open_context(file);
415 		if (ctx)
416 			return ctx->cred;
417 	}
418 	return NULL;
419 }
420 
421 /*
422  * linux/fs/nfs/xattr.c
423  */
424 #ifdef CONFIG_NFS_V3_ACL
425 extern ssize_t nfs3_listxattr(struct dentry *, char *, size_t);
426 extern ssize_t nfs3_getxattr(struct dentry *, const char *, void *, size_t);
427 extern int nfs3_setxattr(struct dentry *, const char *,
428 			const void *, size_t, int);
429 extern int nfs3_removexattr (struct dentry *, const char *name);
430 #else
431 # define nfs3_listxattr NULL
432 # define nfs3_getxattr NULL
433 # define nfs3_setxattr NULL
434 # define nfs3_removexattr NULL
435 #endif
436 
437 /*
438  * linux/fs/nfs/direct.c
439  */
440 extern ssize_t nfs_direct_IO(int, struct kiocb *, const struct iovec *, loff_t,
441 			unsigned long);
442 extern ssize_t nfs_file_direct_read(struct kiocb *iocb,
443 			const struct iovec *iov, unsigned long nr_segs,
444 			loff_t pos);
445 extern ssize_t nfs_file_direct_write(struct kiocb *iocb,
446 			const struct iovec *iov, unsigned long nr_segs,
447 			loff_t pos);
448 
449 /*
450  * linux/fs/nfs/dir.c
451  */
452 extern const struct inode_operations nfs_dir_inode_operations;
453 #ifdef CONFIG_NFS_V3
454 extern const struct inode_operations nfs3_dir_inode_operations;
455 #endif /* CONFIG_NFS_V3 */
456 extern const struct file_operations nfs_dir_operations;
457 extern const struct dentry_operations nfs_dentry_operations;
458 
459 extern void nfs_force_lookup_revalidate(struct inode *dir);
460 extern int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fh, struct nfs_fattr *fattr);
461 extern int nfs_may_open(struct inode *inode, struct rpc_cred *cred, int openflags);
462 extern void nfs_access_zap_cache(struct inode *inode);
463 
464 /*
465  * linux/fs/nfs/symlink.c
466  */
467 extern const struct inode_operations nfs_symlink_inode_operations;
468 
469 /*
470  * linux/fs/nfs/sysctl.c
471  */
472 #ifdef CONFIG_SYSCTL
473 extern int nfs_register_sysctl(void);
474 extern void nfs_unregister_sysctl(void);
475 #else
476 #define nfs_register_sysctl() 0
477 #define nfs_unregister_sysctl() do { } while(0)
478 #endif
479 
480 /*
481  * linux/fs/nfs/namespace.c
482  */
483 extern const struct inode_operations nfs_mountpoint_inode_operations;
484 extern const struct inode_operations nfs_referral_inode_operations;
485 extern int nfs_mountpoint_expiry_timeout;
486 extern void nfs_release_automount_timer(void);
487 
488 /*
489  * linux/fs/nfs/unlink.c
490  */
491 extern void nfs_complete_unlink(struct dentry *dentry, struct inode *);
492 extern void nfs_block_sillyrename(struct dentry *dentry);
493 extern void nfs_unblock_sillyrename(struct dentry *dentry);
494 extern int  nfs_sillyrename(struct inode *dir, struct dentry *dentry);
495 
496 /*
497  * linux/fs/nfs/write.c
498  */
499 extern int  nfs_congestion_kb;
500 extern int  nfs_writepage(struct page *page, struct writeback_control *wbc);
501 extern int  nfs_writepages(struct address_space *, struct writeback_control *);
502 extern int  nfs_flush_incompatible(struct file *file, struct page *page);
503 extern int  nfs_updatepage(struct file *, struct page *, unsigned int, unsigned int);
504 extern int nfs_writeback_done(struct rpc_task *, struct nfs_write_data *);
505 
506 /*
507  * Try to write back everything synchronously (but check the
508  * return value!)
509  */
510 extern int nfs_wb_all(struct inode *inode);
511 extern int nfs_wb_page(struct inode *inode, struct page* page);
512 extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
513 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
514 extern int  nfs_commit_inode(struct inode *, int);
515 extern struct nfs_write_data *nfs_commitdata_alloc(void);
516 extern void nfs_commit_free(struct nfs_write_data *wdata);
517 #else
518 static inline int
519 nfs_commit_inode(struct inode *inode, int how)
520 {
521 	return 0;
522 }
523 #endif
524 
525 static inline int
526 nfs_have_writebacks(struct inode *inode)
527 {
528 	return NFS_I(inode)->npages != 0;
529 }
530 
531 /*
532  * Allocate nfs_write_data structures
533  */
534 extern struct nfs_write_data *nfs_writedata_alloc(unsigned int npages);
535 extern void nfs_writedata_free(struct nfs_write_data *);
536 
537 /*
538  * linux/fs/nfs/read.c
539  */
540 extern int  nfs_readpage(struct file *, struct page *);
541 extern int  nfs_readpages(struct file *, struct address_space *,
542 		struct list_head *, unsigned);
543 extern int  nfs_readpage_result(struct rpc_task *, struct nfs_read_data *);
544 extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
545 			       struct page *);
546 
547 /*
548  * Allocate nfs_read_data structures
549  */
550 extern struct nfs_read_data *nfs_readdata_alloc(unsigned int npages);
551 extern void nfs_readdata_free(struct nfs_read_data *);
552 
553 /*
554  * linux/fs/nfs3proc.c
555  */
556 #ifdef CONFIG_NFS_V3_ACL
557 extern struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type);
558 extern int nfs3_proc_setacl(struct inode *inode, int type,
559 			    struct posix_acl *acl);
560 extern int nfs3_proc_set_default_acl(struct inode *dir, struct inode *inode,
561 		mode_t mode);
562 extern void nfs3_forget_cached_acls(struct inode *inode);
563 #else
564 static inline int nfs3_proc_set_default_acl(struct inode *dir,
565 					    struct inode *inode,
566 					    mode_t mode)
567 {
568 	return 0;
569 }
570 
571 static inline void nfs3_forget_cached_acls(struct inode *inode)
572 {
573 }
574 #endif /* CONFIG_NFS_V3_ACL */
575 
576 /*
577  * inline functions
578  */
579 
580 static inline loff_t nfs_size_to_loff_t(__u64 size)
581 {
582 	if (size > (__u64) OFFSET_MAX - 1)
583 		return OFFSET_MAX - 1;
584 	return (loff_t) size;
585 }
586 
587 static inline ino_t
588 nfs_fileid_to_ino_t(u64 fileid)
589 {
590 	ino_t ino = (ino_t) fileid;
591 	if (sizeof(ino_t) < sizeof(u64))
592 		ino ^= fileid >> (sizeof(u64)-sizeof(ino_t)) * 8;
593 	return ino;
594 }
595 
596 #define NFS_JUKEBOX_RETRY_TIME (5 * HZ)
597 
598 #endif /* __KERNEL__ */
599 
600 /*
601  * NFS debug flags
602  */
603 #define NFSDBG_VFS		0x0001
604 #define NFSDBG_DIRCACHE		0x0002
605 #define NFSDBG_LOOKUPCACHE	0x0004
606 #define NFSDBG_PAGECACHE	0x0008
607 #define NFSDBG_PROC		0x0010
608 #define NFSDBG_XDR		0x0020
609 #define NFSDBG_FILE		0x0040
610 #define NFSDBG_ROOT		0x0080
611 #define NFSDBG_CALLBACK		0x0100
612 #define NFSDBG_CLIENT		0x0200
613 #define NFSDBG_MOUNT		0x0400
614 #define NFSDBG_FSCACHE		0x0800
615 #define NFSDBG_PNFS		0x1000
616 #define NFSDBG_PNFS_LD		0x2000
617 #define NFSDBG_ALL		0xFFFF
618 
619 #ifdef __KERNEL__
620 
621 /*
622  * Enable debugging support for nfs client.
623  * Requires RPC_DEBUG.
624  */
625 #ifdef RPC_DEBUG
626 # define NFS_DEBUG
627 #endif
628 
629 # undef ifdebug
630 # ifdef NFS_DEBUG
631 #  define ifdebug(fac)		if (unlikely(nfs_debug & NFSDBG_##fac))
632 # else
633 #  define ifdebug(fac)		if (0)
634 # endif
635 #endif /* __KERNEL */
636 
637 #endif
638