[linux-2.6-block.git] / include / linux / fdtable.h

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

#ifndef __LINUX_FDTABLE_H
#define __LINUX_FDTABLE_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))

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