/*
   * Wrapper functions for accessing the file_struct fd array.
   */
  
  #ifndef __LINUX_FILE_H
  #define __LINUX_FILE_H
  
  #include <asm/atomic.h>
  #include <linux/posix_types.h>
  #include <linux/compiler.h>
  #include <linux/spinlock.h>

  #include <linux/rcupdate.h>

  #include <linux/types.h>

  
  /*
   * The default fd array needs to be at least BITS_PER_LONG,
   * as this is the granularity returned by copy_fdset().
   */
  #define NR_OPEN_DEFAULT BITS_PER_LONG

  /*
   * The embedded_fd_set is a small fd_set,
   * suitable for most tasks (which open <= BITS_PER_LONG files)
   */
  struct embedded_fd_set {
  	unsigned long fds_bits[1];
  };

  struct fdtable {
  	unsigned int max_fds;

  	struct file ** fd;      /* current fd array */
  	fd_set *close_on_exec;
  	fd_set *open_fds;

  	struct rcu_head rcu;

  	struct fdtable *next;

  };

  /*
   * Open file table structure
   */
  struct files_struct {

    /*
     * read mostly part
     */

  	atomic_t count;

  	struct fdtable *fdt;

  	struct fdtable fdtab;

    /*
     * written part on a separate cache line in SMP
     */
  	spinlock_t file_lock ____cacheline_aligned_in_smp;
  	int next_fd;
  	struct embedded_fd_set close_on_exec_init;
  	struct embedded_fd_set open_fds_init;

  	struct file * fd_array[NR_OPEN_DEFAULT];

  };

  #define files_fdtable(files) (rcu_dereference((files)->fdt))

  extern struct kmem_cache *filp_cachep;

  extern void FASTCALL(__fput(struct file *));
  extern void FASTCALL(fput(struct file *));
  
  static inline void fput_light(struct file *file, int fput_needed)
  {
  	if (unlikely(fput_needed))
  		fput(file);
  }
  
  extern struct file * FASTCALL(fget(unsigned int fd));
  extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
  extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
  extern void put_filp(struct file *);
  extern int get_unused_fd(void);

  extern int get_unused_fd_flags(int flags);

  extern void FASTCALL(put_unused_fd(unsigned int fd));

  struct kmem_cache;

  extern int expand_files(struct files_struct *, int nr);

  extern void free_fdtable_rcu(struct rcu_head *rcu);

  extern void __init files_defer_init(void);

  static inline void free_fdtable(struct fdtable *fdt)
  {
  	call_rcu(&fdt->rcu, free_fdtable_rcu);
  }

  static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
  {
  	struct file * file = NULL;

  	struct fdtable *fdt = files_fdtable(files);

  	if (fd < fdt->max_fds)

  		file = rcu_dereference(fdt->fd[fd]);

  	return file;
  }
  
  /*
   * Check whether the specified fd has an open file.
   */
  #define fcheck(fd)	fcheck_files(current->files, fd)
  
  extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
  
  struct task_struct;
  
  struct files_struct *get_files_struct(struct task_struct *);
  void FASTCALL(put_files_struct(struct files_struct *fs));

  void reset_files_struct(struct task_struct *, struct files_struct *);

  extern struct kmem_cache *files_cachep;

  #endif /* __LINUX_FILE_H */