original development tree for Linux kernel GTP module; now long in mainline.
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* 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().
* 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];
* More than this number of fds: we use a separately allocated fd_set
#define EMBEDDED_FD_SET_SIZE (BITS_PER_BYTE * sizeof(struct embedded_fd_set))
struct fdtable {
unsigned int max_fds;
int max_fdset;
struct file ** fd; /* current fd array */
fd_set *close_on_exec;
fd_set *open_fds;
struct rcu_head rcu;
struct files_struct *free_files;
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 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))
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 void FASTCALL(put_unused_fd(unsigned int fd));
struct kmem_cache;
extern struct file ** alloc_fd_array(int);
extern void free_fd_array(struct file **, int);
extern fd_set *alloc_fdset(int);
extern void free_fdset(fd_set *, int);
extern int expand_files(struct files_struct *, int nr);
extern void free_fdtable(struct fdtable *fdt);
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(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 *);
#endif /* __LINUX_FILE_H */