[mirror_ubuntu-artful-kernel.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 <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;
	unsigned long *full_fds_bits;
	struct rcu_head rcu;
};

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

static inline bool fd_is_open(unsigned 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;
	bool resize_in_progress;
	wait_queue_head_t resize_wait;

	struct fdtable __rcu *fdt;
	struct fdtable fdtab;
  /*
   * written part on a separate cache line in SMP
   */
	spinlock_t file_lock ____cacheline_aligned_in_smp;
	unsigned int next_fd;
	unsigned long close_on_exec_init[1];
	unsigned long open_fds_init[1];
	unsigned long full_fds_bits_init[1];
	struct file __rcu * fd_array[NR_OPEN_DEFAULT];
};

struct file_operations;
struct vfsmount;
struct dentry;

#define rcu_dereference_check_fdtable(files, fdtfd) \
	rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))

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

/*
 * The caller must ensure that fd table isn't shared or hold rcu or file lock
 */
static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
{
	struct fdtable *fdt = rcu_dereference_raw(files->fdt);

	if (fd < fdt->max_fds)
		return rcu_dereference_raw(fdt->fd[fd]);
	return NULL;
}

static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
{
	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
			   !lockdep_is_held(&files->file_lock),
			   "suspicious rcu_dereference_check() usage");
	return __fcheck_files(files, fd);
}

/*
 * 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 *) __latent_entropy;
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 */
Commit	Line	Data
	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 <linux/posix_types.h>
	9	#include <linux/compiler.h>
	10	#include <linux/spinlock.h>
	11	#include <linux/rcupdate.h>
	12	#include <linux/types.h>
	13	#include <linux/init.h>
	14	#include <linux/fs.h>
	15
	16	#include <linux/atomic.h>
	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	struct fdtable {
	25	unsigned int max_fds;
	26	struct file __rcu *fd; / current fd array */
	27	unsigned long *close_on_exec;
	28	unsigned long *open_fds;
	29	unsigned long *full_fds_bits;
	30	struct rcu_head rcu;
	31	};
	32
	33	static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
	34	{
	35	return test_bit(fd, fdt->close_on_exec);
	36	}
	37
	38	static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
	39	{
	40	return test_bit(fd, fdt->open_fds);
	41	}
	42
	43	/*
	44	* Open file table structure
	45	*/
	46	struct files_struct {
	47	/*
	48	* read mostly part
	49	*/
	50	atomic_t count;
	51	bool resize_in_progress;
	52	wait_queue_head_t resize_wait;
	53
	54	struct fdtable __rcu *fdt;
	55	struct fdtable fdtab;
	56	/*
	57	* written part on a separate cache line in SMP
	58	*/
	59	spinlock_t file_lock ____cacheline_aligned_in_smp;
	60	unsigned int next_fd;
	61	unsigned long close_on_exec_init[1];
	62	unsigned long open_fds_init[1];
	63	unsigned long full_fds_bits_init[1];
	64	struct file __rcu * fd_array[NR_OPEN_DEFAULT];
	65	};
	66
	67	struct file_operations;
	68	struct vfsmount;
	69	struct dentry;
	70
	71	#define rcu_dereference_check_fdtable(files, fdtfd) \
	72	rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
	73
	74	#define files_fdtable(files) \
	75	rcu_dereference_check_fdtable((files), (files)->fdt)
	76
	77	/*
	78	* The caller must ensure that fd table isn't shared or hold rcu or file lock
	79	*/
	80	static inline struct file __fcheck_files(struct files_struct files, unsigned int fd)
	81	{
	82	struct fdtable *fdt = rcu_dereference_raw(files->fdt);
	83
	84	if (fd < fdt->max_fds)
	85	return rcu_dereference_raw(fdt->fd[fd]);
	86	return NULL;
	87	}
	88
	89	static inline struct file fcheck_files(struct files_struct files, unsigned int fd)
	90	{
	91	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
	92	!lockdep_is_held(&files->file_lock),
	93	"suspicious rcu_dereference_check() usage");
	94	return __fcheck_files(files, fd);
	95	}
	96
	97	/*
	98	* Check whether the specified fd has an open file.
	99	*/
	100	#define fcheck(fd) fcheck_files(current->files, fd)
	101
	102	struct task_struct;
	103
	104	struct files_struct get_files_struct(struct task_struct );
	105	void put_files_struct(struct files_struct *fs);
	106	void reset_files_struct(struct files_struct *);
	107	int unshare_files(struct files_struct **);
	108	struct files_struct dup_fd(struct files_struct , int *) __latent_entropy;
	109	void do_close_on_exec(struct files_struct *);
	110	int iterate_fd(struct files_struct *, unsigned,
	111	int ()(const void , struct file *, unsigned),
	112	const void *);
	113
	114	extern int __alloc_fd(struct files_struct *files,
	115	unsigned start, unsigned end, unsigned flags);
	116	extern void __fd_install(struct files_struct *files,
	117	unsigned int fd, struct file *file);
	118	extern int __close_fd(struct files_struct *files,
	119	unsigned int fd);
	120
	121	extern struct kmem_cache *files_cachep;
	122
	123	#endif /* __LINUX_FDTABLE_H */