[net-next-2.6.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 <linux/fs.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 __rcu **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 __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;
	struct embedded_fd_set close_on_exec_init;
	struct embedded_fd_set open_fds_init;
	struct file __rcu * fd_array[NR_OPEN_DEFAULT];
};

#define rcu_dereference_check_fdtable(files, fdtfd) \
	(rcu_dereference_check((fdtfd), \
			       rcu_read_lock_held() || \
			       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 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_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 *);

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	13	#include <linux/init.h>
2c666df8	14	#include <linux/fs.h>
21e54459 IM	15
21e54459 IM	16	#include <asm/atomic.h>
9f3acc31 AV	17
	18	/*
	19	* The default fd array needs to be at least BITS_PER_LONG,
	20	* as this is the granularity returned by copy_fdset().
	21	*/
	22	#define NR_OPEN_DEFAULT BITS_PER_LONG
	23
	24	/*
	25	* The embedded_fd_set is a small fd_set,
	26	* suitable for most tasks (which open <= BITS_PER_LONG files)
	27	*/
	28	struct embedded_fd_set {
	29	unsigned long fds_bits[1];
	30	};
	31
	32	struct fdtable {
	33	unsigned int max_fds;
4d2deb40	34	struct file __rcu *fd; / current fd array */
9f3acc31 AV	35	fd_set *close_on_exec;
	36	fd_set *open_fds;
	37	struct rcu_head rcu;
	38	struct fdtable *next;
	39	};
	40
	41	/*
	42	* Open file table structure
	43	*/
	44	struct files_struct {
	45	/*
	46	* read mostly part
	47	*/
	48	atomic_t count;
4d2deb40	49	struct fdtable __rcu *fdt;
9f3acc31 AV	50	struct fdtable fdtab;
	51	/*
	52	* written part on a separate cache line in SMP
	53	*/
	54	spinlock_t file_lock ____cacheline_aligned_in_smp;
	55	int next_fd;
	56	struct embedded_fd_set close_on_exec_init;
	57	struct embedded_fd_set open_fds_init;
4d2deb40	58	struct file __rcu * fd_array[NR_OPEN_DEFAULT];
9f3acc31 AV	59	};
9f3acc31 AV	60
af61b96b PM	61	#define rcu_dereference_check_fdtable(files, fdtfd) \
af61b96b PM	62	(rcu_dereference_check((fdtfd), \
7dc52157 PM	63	rcu_read_lock_held() \|\| \
7dc52157 PM	64	lockdep_is_held(&(files)->file_lock) \|\| \
844b9a87 PM	65	atomic_read(&(files)->count) == 1 \|\| \
844b9a87 PM	66	rcu_my_thread_group_empty()))
af61b96b PM	67
	68	#define files_fdtable(files) \
	69	(rcu_dereference_check_fdtable((files), (files)->fdt))
9f3acc31	70
9f3acc31 AV	71	struct file_operations;
	72	struct vfsmount;
	73	struct dentry;
	74
	75	extern int expand_files(struct files_struct *, int nr);
	76	extern void free_fdtable_rcu(struct rcu_head *rcu);
	77	extern void __init files_defer_init(void);
	78
	79	static inline void free_fdtable(struct fdtable *fdt)
	80	{
	81	call_rcu(&fdt->rcu, free_fdtable_rcu);
	82	}
	83
	84	static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
	85	{
	86	struct file * file = NULL;
	87	struct fdtable *fdt = files_fdtable(files);
	88
	89	if (fd < fdt->max_fds)
af61b96b	90	file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
9f3acc31 AV	91	return file;
	92	}
	93
	94	/*
	95	* Check whether the specified fd has an open file.
	96	*/
	97	#define fcheck(fd) fcheck_files(current->files, fd)
	98
	99	struct task_struct;
	100
	101	struct files_struct get_files_struct(struct task_struct );
	102	void put_files_struct(struct files_struct *fs);
	103	void reset_files_struct(struct files_struct *);
	104	int unshare_files(struct files_struct **);
02afc626	105	struct files_struct dup_fd(struct files_struct , int *);
9f3acc31 AV	106
	107	extern struct kmem_cache *files_cachep;
	108
	109	#endif /* __LINUX_FDTABLE_H */