[linux.git] / include / linux / fdtable.h

/*
 * 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 <asm/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

/*
 * 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_check((files)->fdt, \
			       rcu_read_lock_held() || \
			       lockdep_is_held(&(files)->file_lock) || \
			       atomic_read(&files->count) == 1))

struct file_operations;
struct vfsmount;
struct dentry;

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_check(fdt->fd[fd], rcu_read_lock_held() || lockdep_is_held(&files->file_lock) || atomic_read(&files->count) == 1);
	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 *);

extern struct kmem_cache *files_cachep;

#endif /* __LINUX_FDTABLE_H */
Commit	Line	Data
9f3acc31 AV	1	/*
	2	* descriptor table internals; you almost certainly want file.h instead.
	3	*/
	4
	5	#ifndef __LINUX_FDTABLE_H
	6	#define __LINUX_FDTABLE_H
	7
9f3acc31 AV	8	#include <linux/posix_types.h>
	9	#include <linux/compiler.h>
	10	#include <linux/spinlock.h>
	11	#include <linux/rcupdate.h>
	12	#include <linux/types.h>
21e54459 IM	13	#include <linux/init.h>
	14
	15	#include <asm/atomic.h>
9f3acc31 AV	16
	17	/*
	18	* The default fd array needs to be at least BITS_PER_LONG,
	19	* as this is the granularity returned by copy_fdset().
	20	*/
	21	#define NR_OPEN_DEFAULT BITS_PER_LONG
	22
	23	/*
	24	* The embedded_fd_set is a small fd_set,
	25	* suitable for most tasks (which open <= BITS_PER_LONG files)
	26	*/
	27	struct embedded_fd_set {
	28	unsigned long fds_bits[1];
	29	};
	30
	31	struct fdtable {
	32	unsigned int max_fds;
	33	struct file ** fd; /* current fd array */
	34	fd_set *close_on_exec;
	35	fd_set *open_fds;
	36	struct rcu_head rcu;
	37	struct fdtable *next;
	38	};
	39
	40	/*
	41	* Open file table structure
	42	*/
	43	struct files_struct {
	44	/*
	45	* read mostly part
	46	*/
	47	atomic_t count;
	48	struct fdtable *fdt;
	49	struct fdtable fdtab;
	50	/*
	51	* written part on a separate cache line in SMP
	52	*/
	53	spinlock_t file_lock ____cacheline_aligned_in_smp;
	54	int next_fd;
	55	struct embedded_fd_set close_on_exec_init;
	56	struct embedded_fd_set open_fds_init;
	57	struct file * fd_array[NR_OPEN_DEFAULT];
	58	};
	59
7dc52157 PM	60	#define files_fdtable(files) \
	61	(rcu_dereference_check((files)->fdt, \
	62	rcu_read_lock_held() \|\| \
	63	lockdep_is_held(&(files)->file_lock) \|\| \
	64	atomic_read(&files->count) == 1))
9f3acc31	65
9f3acc31 AV	66	struct file_operations;
	67	struct vfsmount;
	68	struct dentry;
	69
	70	extern int expand_files(struct files_struct *, int nr);
	71	extern void free_fdtable_rcu(struct rcu_head *rcu);
	72	extern void __init files_defer_init(void);
	73
	74	static inline void free_fdtable(struct fdtable *fdt)
	75	{
	76	call_rcu(&fdt->rcu, free_fdtable_rcu);
	77	}
	78
	79	static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
	80	{
	81	struct file * file = NULL;
	82	struct fdtable *fdt = files_fdtable(files);
	83
	84	if (fd < fdt->max_fds)
7dc52157	85	file = rcu_dereference_check(fdt->fd[fd], rcu_read_lock_held() \|\| lockdep_is_held(&files->file_lock) \|\| atomic_read(&files->count) == 1);
9f3acc31 AV	86	return file;
	87	}
	88
	89	/*
	90	* Check whether the specified fd has an open file.
	91	*/
	92	#define fcheck(fd) fcheck_files(current->files, fd)
	93
	94	struct task_struct;
	95
	96	struct files_struct get_files_struct(struct task_struct );
	97	void put_files_struct(struct files_struct *fs);
	98	void reset_files_struct(struct files_struct *);
	99	int unshare_files(struct files_struct **);
02afc626	100	struct files_struct dup_fd(struct files_struct , int *);
9f3acc31 AV	101
	102	extern struct kmem_cache *files_cachep;
	103
	104	#endif /* __LINUX_FDTABLE_H */