text: /*
   * NFS internal definitions
   */
  
  #include "nfs4_fs.h"
  #include <linux/mount.h>
  #include <linux/security.h>
  #include <linux/crc32.h>
  
  #define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
  
  struct nfs_string;
  
  /* Maximum number of readahead requests
   * FIXME: this should really be a sysctl so that users may tune it to suit
   *        their needs. People that do NFS over a slow network, might for
   *        instance want to reduce it to something closer to 1 for improved
   *        interactive response.
   */
  #define NFS_MAX_READAHEAD	(RPC_DEF_SLOT_TABLE - 1)
  
  static inline void nfs_attr_check_mountpoint(struct super_block *parent, struct nfs_fattr *fattr)
  {
  	if (!nfs_fsid_equal(&NFS_SB(parent)->fsid, &fattr->fsid))
  		fattr->valid |= NFS_ATTR_FATTR_MOUNTPOINT;
  }
  
  static inline int nfs_attr_use_mounted_on_fileid(struct nfs_fattr *fattr)
  {
  	if (((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) == 0) ||
  	    (((fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT) == 0) &&
  	     ((fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) == 0)))
  		return 0;
  
  	fattr->fileid = fattr->mounted_on_fileid;
  	return 1;
  }
  
  struct nfs_clone_mount {
  	const struct super_block *sb;
  	const struct dentry *dentry;
  	struct nfs_fh *fh;
  	struct nfs_fattr *fattr;
  	char *hostname;
  	char *mnt_path;
  	struct sockaddr *addr;
  	size_t addrlen;
  	rpc_authflavor_t authflavor;
  };
  
  /*
   * Note: RFC 1813 doesn't limit the number of auth flavors that
   * a server can return, so make something up.
   */
  #define NFS_MAX_SECFLAVORS	(12)
  
  /*
   * Value used if the user did not specify a port value.
   */
  #define NFS_UNSPEC_PORT		(-1)
  
  /*
   * Maximum number of pages that readdir can use for creating
   * a vmapped array of pages.
   */
  #define NFS_MAX_READDIR_PAGES 8
  
  struct nfs_client_initdata {
  	unsigned long init_flags;
  	const char *hostname;
  	const struct sockaddr *addr;
  	size_t addrlen;
  	struct nfs_subversion *nfs_mod;
  	int proto;
  	u32 minorversion;
  	struct net *net;
  };
  
  /*
   * In-kernel mount arguments
   */
  struct nfs_parsed_mount_data {
  	int			flags;
  	unsigned int		rsize, wsize;
  	unsigned int		timeo, retrans;
  	unsigned int		acregmin, acregmax,
  				acdirmin, acdirmax;
  	unsigned int		namlen;
  	unsigned int		options;
  	unsigned int		bsize;
  	struct nfs_auth_info	auth_info;
  	rpc_authflavor_t	selected_flavor;
  	char			*client_address;
  	unsigned int		version;
  	unsigned int		minorversion;
  	char			*fscache_uniq;
  	bool			need_mount;
  
  	struct {
  		struct sockaddr_storage	address;
  		size_t			addrlen;
  		char			*hostname;
  		u32			version;
  		int			port;
  		unsigned short		protocol;
  	} mount_server;
  
  	struct {
  		struct sockaddr_storage	address;
  		size_t			addrlen;
  		char			*hostname;
  		char			*export_path;
  		int			port;
  		unsigned short		protocol;
  	} nfs_server;
  
  	struct security_mnt_opts lsm_opts;
  	struct net		*net;
  };
  
  /* mount_clnt.c */
  struct nfs_mount_request {
  	struct sockaddr		*sap;
  	size_t			salen;
  	char			*hostname;
  	char			*dirpath;
  	u32			version;
  	unsigned short		protocol;
  	struct nfs_fh		*fh;
  	int			noresvport;
  	unsigned int		*auth_flav_len;
  	rpc_authflavor_t	*auth_flavs;
  	struct net		*net;
  };
  
  struct nfs_mount_info {
  	void (*fill_super)(struct super_block *, struct nfs_mount_info *);
  	int (*set_security)(struct super_block *, struct dentry *, struct nfs_mount_info *);
  	struct nfs_parsed_mount_data *parsed;
  	struct nfs_clone_mount *cloned;
  	struct nfs_fh *mntfh;
  };
  
  extern int nfs_mount(struct nfs_mount_request *info);
  extern void nfs_umount(const struct nfs_mount_request *info);
  
  /* client.c */
  extern const struct rpc_program nfs_program;
  extern void nfs_clients_init(struct net *net);
  extern struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *);
  int nfs_create_rpc_client(struct nfs_client *, const struct rpc_timeout *, rpc_authflavor_t);
  struct nfs_client *nfs_get_client(const struct nfs_client_initdata *,
  				  const struct rpc_timeout *, const char *,
  				  rpc_authflavor_t);
  int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *, struct nfs_fattr *);
  void nfs_server_insert_lists(struct nfs_server *);
  void nfs_server_remove_lists(struct nfs_server *);
  void nfs_init_timeout_values(struct rpc_timeout *, int, unsigned int, unsigned int);
  int nfs_init_server_rpcclient(struct nfs_server *, const struct rpc_timeout *t,
  		rpc_authflavor_t);
  struct nfs_server *nfs_alloc_server(void);
  void nfs_server_copy_userdata(struct nfs_server *, struct nfs_server *);
  
  extern void nfs_cleanup_cb_ident_idr(struct net *);
  extern void nfs_put_client(struct nfs_client *);
  extern void nfs_free_client(struct nfs_client *);
  extern struct nfs_client *nfs4_find_client_ident(struct net *, int);
  extern struct nfs_client *
  nfs4_find_client_sessionid(struct net *, const struct sockaddr *,
  				struct nfs4_sessionid *, u32);
  extern struct nfs_server *nfs_create_server(struct nfs_mount_info *,
  					struct nfs_subversion *);
  extern struct nfs_server *nfs4_create_server(
  					struct nfs_mount_info *,
  					struct nfs_subversion *);
  extern struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *,
  						      struct nfs_fh *);
  extern int nfs4_update_server(struct nfs_server *server, const char *hostname,
  					struct sockaddr *sap, size_t salen,
  					struct net *net);
  extern void nfs_free_server(struct nfs_server *server);
  extern struct nfs_server *nfs_clone_server(struct nfs_server *,
  					   struct nfs_fh *,
  					   struct nfs_fattr *,
  					   rpc_authflavor_t);
  extern int nfs_wait_client_init_complete(const struct nfs_client *clp);
  extern void nfs_mark_client_ready(struct nfs_client *clp, int state);
  extern struct nfs_client *nfs4_set_ds_client(struct nfs_client* mds_clp,
  					     const struct sockaddr *ds_addr,
  					     int ds_addrlen, int ds_proto,
  					     unsigned int ds_timeo,
  					     unsigned int ds_retrans);
  extern struct rpc_clnt *nfs4_find_or_create_ds_client(struct nfs_client *,
  						struct inode *);
  #ifdef CONFIG_PROC_FS
  extern int __init nfs_fs_proc_init(void);
  extern void nfs_fs_proc_exit(void);
  extern int nfs_fs_proc_net_init(struct net *net);
  extern void nfs_fs_proc_net_exit(struct net *net);
  #else
  static inline int nfs_fs_proc_net_init(struct net *net)
  {
  	return 0;
  }
  static inline void nfs_fs_proc_net_exit(struct net *net)
  {
  }
  static inline int nfs_fs_proc_init(void)
  {
  	return 0;
  }
  static inline void nfs_fs_proc_exit(void)
  {
  }
  #endif
  
  #ifdef CONFIG_NFS_V4_1
  int nfs_sockaddr_match_ipaddr(const struct sockaddr *, const struct sockaddr *);
  #endif
  
  /* callback_xdr.c */
  extern struct svc_version nfs4_callback_version1;
  extern struct svc_version nfs4_callback_version4;
  
  struct nfs_pageio_descriptor;
  /* pagelist.c */
  extern int __init nfs_init_nfspagecache(void);
  extern void nfs_destroy_nfspagecache(void);
  extern int __init nfs_init_readpagecache(void);
  extern void nfs_destroy_readpagecache(void);
  extern int __init nfs_init_writepagecache(void);
  extern void nfs_destroy_writepagecache(void);
  
  extern int __init nfs_init_directcache(void);
  extern void nfs_destroy_directcache(void);
  extern void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  			      struct nfs_pgio_header *hdr,
  			      void (*release)(struct nfs_pgio_header *hdr));
  void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos);
  int nfs_iocounter_wait(struct nfs_io_counter *c);
  
  extern const struct nfs_pageio_ops nfs_pgio_rw_ops;
  struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *);
  void nfs_pgio_header_free(struct nfs_pgio_header *);
  void nfs_pgio_data_destroy(struct nfs_pgio_header *);
  int nfs_generic_pgio(struct nfs_pageio_descriptor *, struct nfs_pgio_header *);
  int nfs_initiate_pgio(struct rpc_clnt *, struct nfs_pgio_header *,
  		      const struct rpc_call_ops *, int, int);
  void nfs_free_request(struct nfs_page *req);
  
  static inline void nfs_iocounter_init(struct nfs_io_counter *c)
  {
  	c->flags = 0;
  	atomic_set(&c->io_count, 0);
  }
  
  /* nfs2xdr.c */
  extern struct rpc_procinfo nfs_procedures[];
  extern int nfs2_decode_dirent(struct xdr_stream *,
  				struct nfs_entry *, int);
  
  /* nfs3xdr.c */
  extern struct rpc_procinfo nfs3_procedures[];
  extern int nfs3_decode_dirent(struct xdr_stream *,
  				struct nfs_entry *, int);
  
  /* nfs4xdr.c */
  #if IS_ENABLED(CONFIG_NFS_V4)
  extern int nfs4_decode_dirent(struct xdr_stream *,
  				struct nfs_entry *, int);
  #endif
  #ifdef CONFIG_NFS_V4_1
  extern const u32 nfs41_maxread_overhead;
  extern const u32 nfs41_maxwrite_overhead;
  extern const u32 nfs41_maxgetdevinfo_overhead;
  #endif
  
  /* nfs4proc.c */
  #if IS_ENABLED(CONFIG_NFS_V4)
  extern struct rpc_procinfo nfs4_procedures[];
  #endif
  
  #ifdef CONFIG_NFS_V4_SECURITY_LABEL
  extern struct nfs4_label *nfs4_label_alloc(struct nfs_server *server, gfp_t flags);
  static inline void nfs4_label_free(struct nfs4_label *label)
  {
  	if (label) {
  		kfree(label->label);
  		kfree(label);
  	}
  	return;
  }
  
  static inline void nfs_zap_label_cache_locked(struct nfs_inode *nfsi)
  {
  	if (nfs_server_capable(&nfsi->vfs_inode, NFS_CAP_SECURITY_LABEL))
  		nfsi->cache_validity |= NFS_INO_INVALID_LABEL;
  }
  #else
  static inline struct nfs4_label *nfs4_label_alloc(struct nfs_server *server, gfp_t flags) { return NULL; }
  static inline void nfs4_label_free(void *label) {}
  static inline void nfs_zap_label_cache_locked(struct nfs_inode *nfsi)
  {
  }
  #endif /* CONFIG_NFS_V4_SECURITY_LABEL */
  
  /* proc.c */
  void nfs_close_context(struct nfs_open_context *ctx, int is_sync);
  extern struct nfs_client *nfs_init_client(struct nfs_client *clp,
  			   const struct rpc_timeout *timeparms,
  			   const char *ip_addr);
  
  /* dir.c */
  extern void nfs_force_use_readdirplus(struct inode *dir);
  extern unsigned long nfs_access_cache_count(struct shrinker *shrink,
  					    struct shrink_control *sc);
  extern unsigned long nfs_access_cache_scan(struct shrinker *shrink,
  					   struct shrink_control *sc);
  struct dentry *nfs_lookup(struct inode *, struct dentry *, unsigned int);
  int nfs_create(struct inode *, struct dentry *, umode_t, bool);
  int nfs_mkdir(struct inode *, struct dentry *, umode_t);
  int nfs_rmdir(struct inode *, struct dentry *);
  int nfs_unlink(struct inode *, struct dentry *);
  int nfs_symlink(struct inode *, struct dentry *, const char *);
  int nfs_link(struct dentry *, struct inode *, struct dentry *);
  int nfs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
  int nfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
  
  /* file.c */
  int nfs_file_fsync_commit(struct file *, loff_t, loff_t, int);
  loff_t nfs_file_llseek(struct file *, loff_t, int);
  int nfs_file_flush(struct file *, fl_owner_t);
  ssize_t nfs_file_read(struct kiocb *, struct iov_iter *);
  ssize_t nfs_file_splice_read(struct file *, loff_t *, struct pipe_inode_info *,
  			     size_t, unsigned int);
  int nfs_file_mmap(struct file *, struct vm_area_struct *);
  ssize_t nfs_file_write(struct kiocb *, struct iov_iter *);
  int nfs_file_release(struct inode *, struct file *);
  int nfs_lock(struct file *, int, struct file_lock *);
  int nfs_flock(struct file *, int, struct file_lock *);
  int nfs_check_flags(int);
  
  /* inode.c */
  extern struct workqueue_struct *nfsiod_workqueue;
  extern struct inode *nfs_alloc_inode(struct super_block *sb);
  extern void nfs_destroy_inode(struct inode *);
  extern int nfs_write_inode(struct inode *, struct writeback_control *);
  extern int nfs_drop_inode(struct inode *);
  extern void nfs_clear_inode(struct inode *);
  extern void nfs_evict_inode(struct inode *);
  void nfs_zap_acl_cache(struct inode *inode);
  extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
  
  /* super.c */
  extern const struct super_operations nfs_sops;
  extern struct file_system_type nfs_fs_type;
  extern struct file_system_type nfs_xdev_fs_type;
  #if IS_ENABLED(CONFIG_NFS_V4)
  extern struct file_system_type nfs4_xdev_fs_type;
  extern struct file_system_type nfs4_referral_fs_type;
  #endif
  bool nfs_auth_info_match(const struct nfs_auth_info *, rpc_authflavor_t);
  struct dentry *nfs_try_mount(int, const char *, struct nfs_mount_info *,
  			struct nfs_subversion *);
  void nfs_initialise_sb(struct super_block *);
  int nfs_set_sb_security(struct super_block *, struct dentry *, struct nfs_mount_info *);
  int nfs_clone_sb_security(struct super_block *, struct dentry *, struct nfs_mount_info *);
  struct dentry *nfs_fs_mount_common(struct nfs_server *, int, const char *,
  				   struct nfs_mount_info *, struct nfs_subversion *);
  struct dentry *nfs_fs_mount(struct file_system_type *, int, const char *, void *);
  struct dentry * nfs_xdev_mount_common(struct file_system_type *, int,
  		const char *, struct nfs_mount_info *);
  void nfs_kill_super(struct super_block *);
  void nfs_fill_super(struct super_block *, struct nfs_mount_info *);
  
  extern struct rpc_stat nfs_rpcstat;
  
  extern int __init register_nfs_fs(void);
  extern void __exit unregister_nfs_fs(void);
  extern bool nfs_sb_active(struct super_block *sb);
  extern void nfs_sb_deactive(struct super_block *sb);
  
  /* namespace.c */
  #define NFS_PATH_CANONICAL 1
  extern char *nfs_path(char **p, struct dentry *dentry,
  		      char *buffer, ssize_t buflen, unsigned flags);
  extern struct vfsmount *nfs_d_automount(struct path *path);
  struct vfsmount *nfs_submount(struct nfs_server *, struct dentry *,
  			      struct nfs_fh *, struct nfs_fattr *);
  struct vfsmount *nfs_do_submount(struct dentry *, struct nfs_fh *,
  				 struct nfs_fattr *, rpc_authflavor_t);
  
  /* getroot.c */
  extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *,
  				   const char *);
  #if IS_ENABLED(CONFIG_NFS_V4)
  extern struct dentry *nfs4_get_root(struct super_block *, struct nfs_fh *,
  				    const char *);
  
  extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool);
  #endif
  
  struct nfs_pgio_completion_ops;
  /* read.c */
  extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
  			struct inode *inode, bool force_mds,
  			const struct nfs_pgio_completion_ops *compl_ops);
  extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
  extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
  
  /* super.c */
  void nfs_clone_super(struct super_block *, struct nfs_mount_info *);
  void nfs_umount_begin(struct super_block *);
  int  nfs_statfs(struct dentry *, struct kstatfs *);
  int  nfs_show_options(struct seq_file *, struct dentry *);
  int  nfs_show_devname(struct seq_file *, struct dentry *);
  int  nfs_show_path(struct seq_file *, struct dentry *);
  int  nfs_show_stats(struct seq_file *, struct dentry *);
  void nfs_put_super(struct super_block *);
  int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
  
  /* write.c */
  extern void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
  			struct inode *inode, int ioflags, bool force_mds,
  			const struct nfs_pgio_completion_ops *compl_ops);
  extern void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio);
  extern void nfs_commit_free(struct nfs_commit_data *p);
  extern void nfs_write_prepare(struct rpc_task *task, void *calldata);
  extern void nfs_commit_prepare(struct rpc_task *task, void *calldata);
  extern int nfs_initiate_commit(struct rpc_clnt *clnt,
  			       struct nfs_commit_data *data,
  			       const struct rpc_call_ops *call_ops,
  			       int how, int flags);
  extern void nfs_init_commit(struct nfs_commit_data *data,
  			    struct list_head *head,
  			    struct pnfs_layout_segment *lseg,
  			    struct nfs_commit_info *cinfo);
  int nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
  			 struct nfs_commit_info *cinfo, int max);
  unsigned long nfs_reqs_to_commit(struct nfs_commit_info *);
  int nfs_scan_commit(struct inode *inode, struct list_head *dst,
  		    struct nfs_commit_info *cinfo);
  void nfs_mark_request_commit(struct nfs_page *req,
  			     struct pnfs_layout_segment *lseg,
  			     struct nfs_commit_info *cinfo);
  int nfs_write_need_commit(struct nfs_pgio_header *);
  int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
  			    int how, struct nfs_commit_info *cinfo);
  void nfs_retry_commit(struct list_head *page_list,
  		      struct pnfs_layout_segment *lseg,
  		      struct nfs_commit_info *cinfo);
  void nfs_commitdata_release(struct nfs_commit_data *data);
  void nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
  				 struct nfs_commit_info *cinfo);
  void nfs_request_remove_commit_list(struct nfs_page *req,
  				    struct nfs_commit_info *cinfo);
  void nfs_init_cinfo(struct nfs_commit_info *cinfo,
  		    struct inode *inode,
  		    struct nfs_direct_req *dreq);
  int nfs_key_timeout_notify(struct file *filp, struct inode *inode);
  bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx);
  
  #ifdef CONFIG_MIGRATION
  extern int nfs_migrate_page(struct address_space *,
  		struct page *, struct page *, enum migrate_mode);
  #else
  #define nfs_migrate_page NULL
  #endif
  
  /* unlink.c */
  extern struct rpc_task *
  nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
  		 struct dentry *old_dentry, struct dentry *new_dentry,
  		 void (*complete)(struct rpc_task *, struct nfs_renamedata *));
  extern int nfs_sillyrename(struct inode *dir, struct dentry *dentry);
  
  /* direct.c */
  void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
  			      struct nfs_direct_req *dreq);
  static inline void nfs_inode_dio_wait(struct inode *inode)
  {
  	inode_dio_wait(inode);
  }
  extern ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq);
  
  /* nfs4proc.c */
  extern void __nfs4_read_done_cb(struct nfs_pgio_header *);
  extern struct nfs_client *nfs4_init_client(struct nfs_client *clp,
  			    const struct rpc_timeout *timeparms,
  			    const char *ip_addr);
  extern int nfs40_walk_client_list(struct nfs_client *clp,
  				struct nfs_client **result,
  				struct rpc_cred *cred);
  extern int nfs41_walk_client_list(struct nfs_client *clp,
  				struct nfs_client **result,
  				struct rpc_cred *cred);
  
  static inline struct inode *nfs_igrab_and_active(struct inode *inode)
  {
  	inode = igrab(inode);
  	if (inode != NULL && !nfs_sb_active(inode->i_sb)) {
  		iput(inode);
  		inode = NULL;
  	}
  	return inode;
  }
  
  static inline void nfs_iput_and_deactive(struct inode *inode)
  {
  	if (inode != NULL) {
  		struct super_block *sb = inode->i_sb;
  
  		iput(inode);
  		nfs_sb_deactive(sb);
  	}
  }
  
  /*
   * Determine the device name as a string
   */
  static inline char *nfs_devname(struct dentry *dentry,
  				char *buffer, ssize_t buflen)
  {
  	char *dummy;
  	return nfs_path(&dummy, dentry, buffer, buflen, NFS_PATH_CANONICAL);
  }
  
  /*
   * Determine the actual block size (and log2 thereof)
   */
  static inline
  unsigned long nfs_block_bits(unsigned long bsize, unsigned char *nrbitsp)
  {
  	/* make sure blocksize is a power of two */
  	if ((bsize & (bsize - 1)) || nrbitsp) {
  		unsigned char	nrbits;
  
  		for (nrbits = 31; nrbits && !(bsize & (1 << nrbits)); nrbits--)
  			;
  		bsize = 1 << nrbits;
  		if (nrbitsp)
  			*nrbitsp = nrbits;
  	}
  
  	return bsize;
  }
  
  /*
   * Calculate the number of 512byte blocks used.
   */
  static inline blkcnt_t nfs_calc_block_size(u64 tsize)
  {
  	blkcnt_t used = (tsize + 511) >> 9;
  	return (used > ULONG_MAX) ? ULONG_MAX : used;
  }
  
  /*
   * Compute and set NFS server blocksize
   */
  static inline
  unsigned long nfs_block_size(unsigned long bsize, unsigned char *nrbitsp)
  {
  	if (bsize < NFS_MIN_FILE_IO_SIZE)
  		bsize = NFS_DEF_FILE_IO_SIZE;
  	else if (bsize >= NFS_MAX_FILE_IO_SIZE)
  		bsize = NFS_MAX_FILE_IO_SIZE;
  
  	return nfs_block_bits(bsize, nrbitsp);
  }
  
  /*
   * Determine the maximum file size for a superblock
   */
  static inline
  void nfs_super_set_maxbytes(struct super_block *sb, __u64 maxfilesize)
  {
  	sb->s_maxbytes = (loff_t)maxfilesize;
  	if (sb->s_maxbytes > MAX_LFS_FILESIZE || sb->s_maxbytes <= 0)
  		sb->s_maxbytes = MAX_LFS_FILESIZE;
  }
  
  /*
   * Determine the number of bytes of data the page contains
   */
  static inline
  unsigned int nfs_page_length(struct page *page)
  {
  	loff_t i_size = i_size_read(page_file_mapping(page)->host);
  
  	if (i_size > 0) {
  		pgoff_t page_index = page_file_index(page);
  		pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
  		if (page_index < end_index)
  			return PAGE_CACHE_SIZE;
  		if (page_index == end_index)
  			return ((i_size - 1) & ~PAGE_CACHE_MASK) + 1;
  	}
  	return 0;
  }
  
  /*
   * Convert a umode to a dirent->d_type
   */
  static inline
  unsigned char nfs_umode_to_dtype(umode_t mode)
  {
  	return (mode >> 12) & 15;
  }
  
  /*
   * Determine the number of pages in an array of length 'len' and
   * with a base offset of 'base'
   */
  static inline
  unsigned int nfs_page_array_len(unsigned int base, size_t len)
  {
  	return ((unsigned long)len + (unsigned long)base +
  		PAGE_SIZE - 1) >> PAGE_SHIFT;
  }
  
  /*
   * Convert a struct timespec into a 64-bit change attribute
   *
   * This does approximately the same thing as timespec_to_ns(),
   * but for calculation efficiency, we multiply the seconds by
   * 1024*1024*1024.
   */
  static inline
  u64 nfs_timespec_to_change_attr(const struct timespec *ts)
  {
  	return ((u64)ts->tv_sec << 30) + ts->tv_nsec;
  }
  
  #ifdef CONFIG_CRC32
  /**
   * nfs_fhandle_hash - calculate the crc32 hash for the filehandle
   * @fh - pointer to filehandle
   *
   * returns a crc32 hash for the filehandle that is compatible with
   * the one displayed by "wireshark".
   */
  static inline u32 nfs_fhandle_hash(const struct nfs_fh *fh)
  {
  	return ~crc32_le(0xFFFFFFFF, &fh->data[0], fh->size);
  }
  #else
  static inline u32 nfs_fhandle_hash(const struct nfs_fh *fh)
  {
  	return 0;
  }
  #endif
  