LXR linux/include/linux/nfs

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 *  linux/include/linux/nfs_fs.h
   4 *
   5 *  Copyright (C) 1992  Rick Sladkey
   6 *
   7 *  OS-specific nfs filesystem definitions and declarations
   8 */
   9#ifndef _LINUX_NFS_FS_H
  10#define _LINUX_NFS_FS_H
  11
  12#include <uapi/linux/nfs_fs.h>
  13
  14
  15/*
  16 * Enable dprintk() debugging support for nfs client.
  17 */
  18#ifdef CONFIG_NFS_DEBUG
  19# define NFS_DEBUG
  20#endif
  21
  22#include <linux/in.h>
  23#include <linux/mm.h>
  24#include <linux/pagemap.h>
  25#include <linux/rbtree.h>
  26#include <linux/refcount.h>
  27#include <linux/rwsem.h>
  28#include <linux/wait.h>
  29
  30#include <linux/sunrpc/debug.h>
  31#include <linux/sunrpc/auth.h>
  32#include <linux/sunrpc/clnt.h>
  33
  34#include <linux/nfs.h>
  35#include <linux/nfs2.h>
  36#include <linux/nfs3.h>
  37#include <linux/nfs4.h>
  38#include <linux/nfs_xdr.h>
  39#include <linux/nfs_fs_sb.h>
  40
  41#include <linux/mempool.h>
  42
  43/*
  44 * These are the default flags for swap requests
  45 */
  46#define NFS_RPC_SWAPFLAGS               (RPC_TASK_SWAPPER|RPC_TASK_ROOTCREDS)
  47
  48/*
  49 * Size of the NFS directory verifier
  50 */
  51#define NFS_DIR_VERIFIER_SIZE           2
  52
  53/*
  54 * NFSv3/v4 Access mode cache entry
  55 */
  56struct nfs_access_entry {
  57        struct rb_node          rb_node;
  58        struct list_head        lru;
  59        const struct cred *     cred;
  60        __u32                   mask;
  61        struct rcu_head         rcu_head;
  62};
  63
  64struct nfs_lock_context {
  65        refcount_t count;
  66        struct list_head list;
  67        struct nfs_open_context *open_context;
  68        fl_owner_t lockowner;
  69        atomic_t io_count;
  70        struct rcu_head rcu_head;
  71};
  72
  73struct nfs4_state;
  74struct nfs_open_context {
  75        struct nfs_lock_context lock_context;
  76        fl_owner_t flock_owner;
  77        struct dentry *dentry;
  78        const struct cred *cred;
  79        struct rpc_cred *ll_cred;       /* low-level cred - use to check for expiry */
  80        struct nfs4_state *state;
  81        fmode_t mode;
  82
  83        unsigned long flags;
  84#define NFS_CONTEXT_RESEND_WRITES       (1)
  85#define NFS_CONTEXT_BAD                 (2)
  86#define NFS_CONTEXT_UNLOCK      (3)
  87        int error;
  88
  89        struct list_head list;
  90        struct nfs4_threshold   *mdsthreshold;
  91        struct rcu_head rcu_head;
  92};
  93
  94struct nfs_open_dir_context {
  95        struct list_head list;
  96        unsigned long attr_gencount;
  97        __be32  verf[NFS_DIR_VERIFIER_SIZE];
  98        __u64 dir_cookie;
  99        __u64 dup_cookie;
 100        signed char duped;
 101};
 102
 103/*
 104 * NFSv4 delegation
 105 */
 106struct nfs_delegation;
 107
 108struct posix_acl;
 109
 110struct nfs4_xattr_cache;
 111
 112/*
 113 * nfs fs inode data in memory
 114 */
 115struct nfs_inode {
 116        /*
 117         * The 64bit 'inode number'
 118         */
 119        __u64 fileid;
 120
 121        /*
 122         * NFS file handle
 123         */
 124        struct nfs_fh           fh;
 125
 126        /*
 127         * Various flags
 128         */
 129        unsigned long           flags;                  /* atomic bit ops */
 130        unsigned long           cache_validity;         /* bit mask */
 131
 132        /*
 133         * read_cache_jiffies is when we started read-caching this inode.
 134         * attrtimeo is for how long the cached information is assumed
 135         * to be valid. A successful attribute revalidation doubles
 136         * attrtimeo (up to acregmax/acdirmax), a failure resets it to
 137         * acregmin/acdirmin.
 138         *
 139         * We need to revalidate the cached attrs for this inode if
 140         *
 141         *      jiffies - read_cache_jiffies >= attrtimeo
 142         *
 143         * Please note the comparison is greater than or equal
 144         * so that zero timeout values can be specified.
 145         */
 146        unsigned long           read_cache_jiffies;
 147        unsigned long           attrtimeo;
 148        unsigned long           attrtimeo_timestamp;
 149
 150        unsigned long           attr_gencount;
 151        /* "Generation counter" for the attribute cache. This is
 152         * bumped whenever we update the metadata on the
 153         * server.
 154         */
 155        unsigned long           cache_change_attribute;
 156
 157        struct rb_root          access_cache;
 158        struct list_head        access_cache_entry_lru;
 159        struct list_head        access_cache_inode_lru;
 160
 161        /*
 162         * This is the cookie verifier used for NFSv3 readdir
 163         * operations
 164         */
 165        __be32                  cookieverf[NFS_DIR_VERIFIER_SIZE];
 166
 167        atomic_long_t           nrequests;
 168        struct nfs_mds_commit_info commit_info;
 169
 170        /* Open contexts for shared mmap writes */
 171        struct list_head        open_files;
 172
 173        /* Readers: in-flight sillydelete RPC calls */
 174        /* Writers: rmdir */
 175        struct rw_semaphore     rmdir_sem;
 176        struct mutex            commit_mutex;
 177
 178        /* track last access to cached pages */
 179        unsigned long           page_index;
 180
 181#if IS_ENABLED(CONFIG_NFS_V4)
 182        struct nfs4_cached_acl  *nfs4_acl;
 183        /* NFSv4 state */
 184        struct list_head        open_states;
 185        struct nfs_delegation __rcu *delegation;
 186        struct rw_semaphore     rwsem;
 187
 188        /* pNFS layout information */
 189        struct pnfs_layout_hdr *layout;
 190#endif /* CONFIG_NFS_V4*/
 191        /* how many bytes have been written/read and how many bytes queued up */
 192        __u64 write_io;
 193        __u64 read_io;
 194#ifdef CONFIG_NFS_FSCACHE
 195        struct fscache_cookie   *fscache;
 196#endif
 197        struct inode            vfs_inode;
 198
 199#ifdef CONFIG_NFS_V4_2
 200        struct nfs4_xattr_cache *xattr_cache;
 201#endif
 202};
 203
 204struct nfs4_copy_state {
 205        struct list_head        copies;
 206        struct list_head        src_copies;
 207        nfs4_stateid            stateid;
 208        struct completion       completion;
 209        uint64_t                count;
 210        struct nfs_writeverf    verf;
 211        int                     error;
 212        int                     flags;
 213        struct nfs4_state       *parent_src_state;
 214        struct nfs4_state       *parent_dst_state;
 215};
 216
 217/*
 218 * Access bit flags
 219 */
 220#define NFS_ACCESS_READ        0x0001
 221#define NFS_ACCESS_LOOKUP      0x0002
 222#define NFS_ACCESS_MODIFY      0x0004
 223#define NFS_ACCESS_EXTEND      0x0008
 224#define NFS_ACCESS_DELETE      0x0010
 225#define NFS_ACCESS_EXECUTE     0x0020
 226#define NFS_ACCESS_XAREAD      0x0040
 227#define NFS_ACCESS_XAWRITE     0x0080
 228#define NFS_ACCESS_XALIST      0x0100
 229
 230/*
 231 * Cache validity bit flags
 232 */
 233#define NFS_INO_INVALID_DATA    BIT(1)          /* cached data is invalid */
 234#define NFS_INO_INVALID_ATIME   BIT(2)          /* cached atime is invalid */
 235#define NFS_INO_INVALID_ACCESS  BIT(3)          /* cached access cred invalid */
 236#define NFS_INO_INVALID_ACL     BIT(4)          /* cached acls are invalid */
 237#define NFS_INO_REVAL_PAGECACHE BIT(5)          /* must revalidate pagecache */
 238#define NFS_INO_REVAL_FORCED    BIT(6)          /* force revalidation ignoring a delegation */
 239#define NFS_INO_INVALID_LABEL   BIT(7)          /* cached label is invalid */
 240#define NFS_INO_INVALID_CHANGE  BIT(8)          /* cached change is invalid */
 241#define NFS_INO_INVALID_CTIME   BIT(9)          /* cached ctime is invalid */
 242#define NFS_INO_INVALID_MTIME   BIT(10)         /* cached mtime is invalid */
 243#define NFS_INO_INVALID_SIZE    BIT(11)         /* cached size is invalid */
 244#define NFS_INO_INVALID_OTHER   BIT(12)         /* other attrs are invalid */
 245#define NFS_INO_DATA_INVAL_DEFER        \
 246                                BIT(13)         /* Deferred cache invalidation */
 247#define NFS_INO_INVALID_BLOCKS  BIT(14)         /* cached blocks are invalid */
 248#define NFS_INO_INVALID_XATTR   BIT(15)         /* xattrs are invalid */
 249
 250#define NFS_INO_INVALID_ATTR    (NFS_INO_INVALID_CHANGE \
 251                | NFS_INO_INVALID_CTIME \
 252                | NFS_INO_INVALID_MTIME \
 253                | NFS_INO_INVALID_SIZE \
 254                | NFS_INO_INVALID_OTHER)        /* inode metadata is invalid */
 255
 256/*
 257 * Bit offsets in flags field
 258 */
 259#define NFS_INO_ADVISE_RDPLUS   (0)             /* advise readdirplus */
 260#define NFS_INO_STALE           (1)             /* possible stale inode */
 261#define NFS_INO_ACL_LRU_SET     (2)             /* Inode is on the LRU list */
 262#define NFS_INO_INVALIDATING    (3)             /* inode is being invalidated */
 263#define NFS_INO_FSCACHE         (5)             /* inode can be cached by FS-Cache */
 264#define NFS_INO_FSCACHE_LOCK    (6)             /* FS-Cache cookie management lock */
 265#define NFS_INO_LAYOUTCOMMIT    (9)             /* layoutcommit required */
 266#define NFS_INO_LAYOUTCOMMITTING (10)           /* layoutcommit inflight */
 267#define NFS_INO_LAYOUTSTATS     (11)            /* layoutstats inflight */
 268#define NFS_INO_ODIRECT         (12)            /* I/O setting is O_DIRECT */
 269
 270static inline struct nfs_inode *NFS_I(const struct inode *inode)
 271{
 272        return container_of(inode, struct nfs_inode, vfs_inode);
 273}
 274
 275static inline struct nfs_server *NFS_SB(const struct super_block *s)
 276{
 277        return (struct nfs_server *)(s->s_fs_info);
 278}
 279
 280static inline struct nfs_fh *NFS_FH(const struct inode *inode)
 281{
 282        return &NFS_I(inode)->fh;
 283}
 284
 285static inline struct nfs_server *NFS_SERVER(const struct inode *inode)
 286{
 287        return NFS_SB(inode->i_sb);
 288}
 289
 290static inline struct rpc_clnt *NFS_CLIENT(const struct inode *inode)
 291{
 292        return NFS_SERVER(inode)->client;
 293}
 294
 295static inline const struct nfs_rpc_ops *NFS_PROTO(const struct inode *inode)
 296{
 297        return NFS_SERVER(inode)->nfs_client->rpc_ops;
 298}
 299
 300static inline unsigned NFS_MINATTRTIMEO(const struct inode *inode)
 301{
 302        struct nfs_server *nfss = NFS_SERVER(inode);
 303        return S_ISDIR(inode->i_mode) ? nfss->acdirmin : nfss->acregmin;
 304}
 305
 306static inline unsigned NFS_MAXATTRTIMEO(const struct inode *inode)
 307{
 308        struct nfs_server *nfss = NFS_SERVER(inode);
 309        return S_ISDIR(inode->i_mode) ? nfss->acdirmax : nfss->acregmax;
 310}
 311
 312static inline int NFS_STALE(const struct inode *inode)
 313{
 314        return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
 315}
 316
 317static inline struct fscache_cookie *nfs_i_fscache(struct inode *inode)
 318{
 319#ifdef CONFIG_NFS_FSCACHE
 320        return NFS_I(inode)->fscache;
 321#else
 322        return NULL;
 323#endif
 324}
 325
 326static inline __u64 NFS_FILEID(const struct inode *inode)
 327{
 328        return NFS_I(inode)->fileid;
 329}
 330
 331static inline void set_nfs_fileid(struct inode *inode, __u64 fileid)
 332{
 333        NFS_I(inode)->fileid = fileid;
 334}
 335
 336static inline void nfs_mark_for_revalidate(struct inode *inode)
 337{
 338        struct nfs_inode *nfsi = NFS_I(inode);
 339
 340        spin_lock(&inode->i_lock);
 341        nfsi->cache_validity |= NFS_INO_REVAL_PAGECACHE
 342                | NFS_INO_INVALID_ACCESS
 343                | NFS_INO_INVALID_ACL
 344                | NFS_INO_INVALID_CHANGE
 345                | NFS_INO_INVALID_CTIME;
 346        if (S_ISDIR(inode->i_mode))
 347                nfsi->cache_validity |= NFS_INO_INVALID_DATA;
 348        spin_unlock(&inode->i_lock);
 349}
 350
 351static inline int nfs_server_capable(struct inode *inode, int cap)
 352{
 353        return NFS_SERVER(inode)->caps & cap;
 354}
 355
 356/**
 357 * nfs_save_change_attribute - Returns the inode attribute change cookie
 358 * @dir - pointer to parent directory inode
 359 * The "cache change attribute" is updated when we need to revalidate
 360 * our dentry cache after a directory was seen to change on the server.
 361 */
 362static inline unsigned long nfs_save_change_attribute(struct inode *dir)
 363{
 364        return NFS_I(dir)->cache_change_attribute;
 365}
 366
 367/*
 368 * linux/fs/nfs/inode.c
 369 */
 370extern int nfs_sync_mapping(struct address_space *mapping);
 371extern void nfs_zap_mapping(struct inode *inode, struct address_space *mapping);
 372extern void nfs_zap_caches(struct inode *);
 373extern void nfs_set_inode_stale(struct inode *inode);
 374extern void nfs_invalidate_atime(struct inode *);
 375extern struct inode *nfs_fhget(struct super_block *, struct nfs_fh *,
 376                                struct nfs_fattr *, struct nfs4_label *);
 377struct inode *nfs_ilookup(struct super_block *sb, struct nfs_fattr *, struct nfs_fh *);
 378extern int nfs_refresh_inode(struct inode *, struct nfs_fattr *);
 379extern int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr);
 380extern int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr);
 381extern int nfs_post_op_update_inode_force_wcc_locked(struct inode *inode, struct nfs_fattr *fattr);
 382extern int nfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
 383extern void nfs_access_add_cache(struct inode *, struct nfs_access_entry *);
 384extern void nfs_access_set_mask(struct nfs_access_entry *, u32);
 385extern int nfs_permission(struct inode *, int);
 386extern int nfs_open(struct inode *, struct file *);
 387extern int nfs_attribute_cache_expired(struct inode *inode);
 388extern int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode);
 389extern int __nfs_revalidate_inode(struct nfs_server *, struct inode *);
 390extern bool nfs_mapping_need_revalidate_inode(struct inode *inode);
 391extern int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping);
 392extern int nfs_revalidate_mapping_rcu(struct inode *inode);
 393extern int nfs_setattr(struct dentry *, struct iattr *);
 394extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr, struct nfs_fattr *);
 395extern void nfs_setsecurity(struct inode *inode, struct nfs_fattr *fattr,
 396                                struct nfs4_label *label);
 397extern struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx);
 398extern void put_nfs_open_context(struct nfs_open_context *ctx);
 399extern struct nfs_open_context *nfs_find_open_context(struct inode *inode, const struct cred *cred, fmode_t mode);
 400extern struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f_mode, struct file *filp);
 401extern void nfs_inode_attach_open_context(struct nfs_open_context *ctx);
 402extern void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx);
 403extern void nfs_file_clear_open_context(struct file *flip);
 404extern struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx);
 405extern void nfs_put_lock_context(struct nfs_lock_context *l_ctx);
 406extern u64 nfs_compat_user_ino64(u64 fileid);
 407extern void nfs_fattr_init(struct nfs_fattr *fattr);
 408extern void nfs_fattr_set_barrier(struct nfs_fattr *fattr);
 409extern unsigned long nfs_inc_attr_generation_counter(void);
 410
 411extern struct nfs_fattr *nfs_alloc_fattr(void);
 412
 413static inline void nfs_free_fattr(const struct nfs_fattr *fattr)
 414{
 415        kfree(fattr);
 416}
 417
 418extern struct nfs_fh *nfs_alloc_fhandle(void);
 419
 420static inline void nfs_free_fhandle(const struct nfs_fh *fh)
 421{
 422        kfree(fh);
 423}
 424
 425#ifdef NFS_DEBUG
 426extern u32 _nfs_display_fhandle_hash(const struct nfs_fh *fh);
 427static inline u32 nfs_display_fhandle_hash(const struct nfs_fh *fh)
 428{
 429        return _nfs_display_fhandle_hash(fh);
 430}
 431extern void _nfs_display_fhandle(const struct nfs_fh *fh, const char *caption);
 432#define nfs_display_fhandle(fh, caption)                        \
 433        do {                                                    \
 434                if (unlikely(nfs_debug & NFSDBG_FACILITY))      \
 435                        _nfs_display_fhandle(fh, caption);      \
 436        } while (0)
 437#else
 438static inline u32 nfs_display_fhandle_hash(const struct nfs_fh *fh)
 439{
 440        return 0;
 441}
 442static inline void nfs_display_fhandle(const struct nfs_fh *fh,
 443                                       const char *caption)
 444{
 445}
 446#endif
 447
 448/*
 449 * linux/fs/nfs/nfsroot.c
 450 */
 451extern int  nfs_root_data(char **root_device, char **root_data); /*__init*/
 452/* linux/net/ipv4/ipconfig.c: trims ip addr off front of name, too. */
 453extern __be32 root_nfs_parse_addr(char *name); /*__init*/
 454
 455/*
 456 * linux/fs/nfs/file.c
 457 */
 458extern const struct file_operations nfs_file_operations;
 459#if IS_ENABLED(CONFIG_NFS_V4)
 460extern const struct file_operations nfs4_file_operations;
 461#endif /* CONFIG_NFS_V4 */
 462extern const struct address_space_operations nfs_file_aops;
 463extern const struct address_space_operations nfs_dir_aops;
 464
 465static inline struct nfs_open_context *nfs_file_open_context(struct file *filp)
 466{
 467        return filp->private_data;
 468}
 469
 470static inline const struct cred *nfs_file_cred(struct file *file)
 471{
 472        if (file != NULL) {
 473                struct nfs_open_context *ctx =
 474                        nfs_file_open_context(file);
 475                if (ctx)
 476                        return ctx->cred;
 477        }
 478        return NULL;
 479}
 480
 481/*
 482 * linux/fs/nfs/direct.c
 483 */
 484extern ssize_t nfs_direct_IO(struct kiocb *, struct iov_iter *);
 485extern ssize_t nfs_file_direct_read(struct kiocb *iocb,
 486                        struct iov_iter *iter);
 487extern ssize_t nfs_file_direct_write(struct kiocb *iocb,
 488                        struct iov_iter *iter);
 489
 490/*
 491 * linux/fs/nfs/dir.c
 492 */
 493extern const struct file_operations nfs_dir_operations;
 494extern const struct dentry_operations nfs_dentry_operations;
 495
 496extern void nfs_force_lookup_revalidate(struct inode *dir);
 497extern void nfs_set_verifier(struct dentry * dentry, unsigned long verf);
 498#if IS_ENABLED(CONFIG_NFS_V4)
 499extern void nfs_clear_verifier_delegated(struct inode *inode);
 500#endif /* IS_ENABLED(CONFIG_NFS_V4) */
 501extern struct dentry *nfs_add_or_obtain(struct dentry *dentry,
 502                        struct nfs_fh *fh, struct nfs_fattr *fattr,
 503                        struct nfs4_label *label);
 504extern int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fh,
 505                        struct nfs_fattr *fattr, struct nfs4_label *label);
 506extern int nfs_may_open(struct inode *inode, const struct cred *cred, int openflags);
 507extern void nfs_access_zap_cache(struct inode *inode);
 508extern int nfs_access_get_cached(struct inode *inode, const struct cred *cred, struct nfs_access_entry *res,
 509                                 bool may_block);
 510
 511/*
 512 * linux/fs/nfs/symlink.c
 513 */
 514extern const struct inode_operations nfs_symlink_inode_operations;
 515
 516/*
 517 * linux/fs/nfs/sysctl.c
 518 */
 519#ifdef CONFIG_SYSCTL
 520extern int nfs_register_sysctl(void);
 521extern void nfs_unregister_sysctl(void);
 522#else
 523#define nfs_register_sysctl() 0
 524#define nfs_unregister_sysctl() do { } while(0)
 525#endif
 526
 527/*
 528 * linux/fs/nfs/namespace.c
 529 */
 530extern const struct inode_operations nfs_mountpoint_inode_operations;
 531extern const struct inode_operations nfs_referral_inode_operations;
 532extern int nfs_mountpoint_expiry_timeout;
 533extern void nfs_release_automount_timer(void);
 534
 535/*
 536 * linux/fs/nfs/unlink.c
 537 */
 538extern void nfs_complete_unlink(struct dentry *dentry, struct inode *);
 539
 540/*
 541 * linux/fs/nfs/write.c
 542 */
 543extern int  nfs_congestion_kb;
 544extern int  nfs_writepage(struct page *page, struct writeback_control *wbc);
 545extern int  nfs_writepages(struct address_space *, struct writeback_control *);
 546extern int  nfs_flush_incompatible(struct file *file, struct page *page);
 547extern int  nfs_updatepage(struct file *, struct page *, unsigned int, unsigned int);
 548
 549/*
 550 * Try to write back everything synchronously (but check the
 551 * return value!)
 552 */
 553extern int nfs_sync_inode(struct inode *inode);
 554extern int nfs_wb_all(struct inode *inode);
 555extern int nfs_wb_page(struct inode *inode, struct page *page);
 556extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
 557extern int  nfs_commit_inode(struct inode *, int);
 558extern struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail);
 559extern void nfs_commit_free(struct nfs_commit_data *data);
 560
 561static inline int
 562nfs_have_writebacks(struct inode *inode)
 563{
 564        return atomic_long_read(&NFS_I(inode)->nrequests) != 0;
 565}
 566
 567/*
 568 * linux/fs/nfs/read.c
 569 */
 570extern int  nfs_readpage(struct file *, struct page *);
 571extern int  nfs_readpages(struct file *, struct address_space *,
 572                struct list_head *, unsigned);
 573extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
 574                               struct page *);
 575
 576/*
 577 * inline functions
 578 */
 579
 580static inline loff_t nfs_size_to_loff_t(__u64 size)
 581{
 582        return min_t(u64, size, OFFSET_MAX);
 583}
 584
 585static inline ino_t
 586nfs_fileid_to_ino_t(u64 fileid)
 587{
 588        ino_t ino = (ino_t) fileid;
 589        if (sizeof(ino_t) < sizeof(u64))
 590                ino ^= fileid >> (sizeof(u64)-sizeof(ino_t)) * 8;
 591        return ino;
 592}
 593
 594#define NFS_JUKEBOX_RETRY_TIME (5 * HZ)
 595
 596
 597# undef ifdebug
 598# ifdef NFS_DEBUG
 599#  define ifdebug(fac)          if (unlikely(nfs_debug & NFSDBG_##fac))
 600#  define NFS_IFDEBUG(x)        x
 601# else
 602#  define ifdebug(fac)          if (0)
 603#  define NFS_IFDEBUG(x)
 604# endif
 605#endif
 606