/*
* descriptor table internals; you almost certainly want file.h instead.
*/

#ifndef __LINUX_FDTABLE_H
#define __LINUX_FDTABLE_H

#include <linux/posix_types.h>
#include <linux/compiler.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/fs.h>

#include <linux/atomic.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

struct fdtable {
unsigned int max_fds;
struct file __rcu **fd; /* current fd array */
unsigned long *close_on_exec;
unsigned long *open_fds;
struct rcu_head rcu;
};

static inline bool close_on_exec(int fd, const struct fdtable *fdt)
{
return test_bit(fd, fdt->close_on_exec);
}

static inline bool fd_is_open(int fd, const struct fdtable *fdt)
{
return test_bit(fd, fdt->open_fds);
}

/*
* Open file table structure
*/
struct files_struct {
/*
* read mostly part
*/
atomic_t count;
struct fdtable __rcu *fdt;
struct fdtable fdtab;
/*
* written part on a separate cache line in SMP
*/
spinlock_t file_lock ____cacheline_aligned_in_smp;
int next_fd;
unsigned long close_on_exec_init[1];
unsigned long open_fds_init[1];
struct file __rcu * fd_array[NR_OPEN_DEFAULT];
};

#define rcu_dereference_check_fdtable(files, fdtfd) \
(rcu_dereference_check((fdtfd), \
lockdep_is_held(&(files)->file_lock) || \
atomic_read(&(files)->count) == 1 || \
rcu_my_thread_group_empty()))

#define files_fdtable(files) \
(rcu_dereference_check_fdtable((files), (files)->fdt))

struct file_operations;
struct vfsmount;
struct dentry;

extern void __init files_defer_init(void);

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_check_fdtable(files, fdt->fd[fd]);
return file;
}

/*
* Check whether the specified fd has an open file.
*/
#define fcheck(fd) fcheck_files(current->files, fd)

struct task_struct;

struct files_struct *get_files_struct(struct task_struct *);
void put_files_struct(struct files_struct *fs);
void reset_files_struct(struct files_struct *);
int unshare_files(struct files_struct **);
struct files_struct *dup_fd(struct files_struct *, int *);
void do_close_on_exec(struct files_struct *);
int iterate_fd(struct files_struct *, unsigned,
int (*)(const void *, struct file *, unsigned),
const void *);

extern int __alloc_fd(struct files_struct *files,
unsigned start, unsigned end, unsigned flags);
extern void __fd_install(struct files_struct *files,
unsigned int fd, struct file *file);
extern int __close_fd(struct files_struct *files,
unsigned int fd);

extern struct kmem_cache *files_cachep;

#endif /* __LINUX_FDTABLE_H */