blob: 9f7c2513866f4d1a857398711f09864239b7162c [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Wrapper functions for accessing the file_struct fd array.
3 */
4
5#ifndef __LINUX_FILE_H
6#define __LINUX_FILE_H
7
8#include <asm/atomic.h>
9#include <linux/posix_types.h>
10#include <linux/compiler.h>
11#include <linux/spinlock.h>
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070012#include <linux/rcupdate.h>
Eric Dumazet0c9e63f2006-03-23 03:00:12 -080013#include <linux/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
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
Eric Dumazet0c9e63f2006-03-23 03:00:12 -080021/*
22 * The embedded_fd_set is a small fd_set,
23 * suitable for most tasks (which open <= BITS_PER_LONG files)
24 */
25struct embedded_fd_set {
26 unsigned long fds_bits[1];
27};
28
29/*
30 * More than this number of fds: we use a separately allocated fd_set
31 */
32#define EMBEDDED_FD_SET_SIZE (BITS_PER_BYTE * sizeof(struct embedded_fd_set))
33
Dipankar Sarmabadf1662005-09-09 13:04:10 -070034struct fdtable {
35 unsigned int max_fds;
36 int max_fdset;
Dipankar Sarmabadf1662005-09-09 13:04:10 -070037 struct file ** fd; /* current fd array */
38 fd_set *close_on_exec;
39 fd_set *open_fds;
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070040 struct rcu_head rcu;
41 struct files_struct *free_files;
42 struct fdtable *next;
Dipankar Sarmabadf1662005-09-09 13:04:10 -070043};
44
Linus Torvalds1da177e2005-04-16 15:20:36 -070045/*
46 * Open file table structure
47 */
48struct files_struct {
Eric Dumazet0c9e63f2006-03-23 03:00:12 -080049 /*
50 * read mostly part
51 */
Eric Dumazet95e861d2005-11-13 16:06:24 -080052 atomic_t count;
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070053 struct fdtable *fdt;
Dipankar Sarmabadf1662005-09-09 13:04:10 -070054 struct fdtable fdtab;
Eric Dumazet0c9e63f2006-03-23 03:00:12 -080055 /*
56 * written part on a separate cache line in SMP
57 */
58 spinlock_t file_lock ____cacheline_aligned_in_smp;
59 int next_fd;
60 struct embedded_fd_set close_on_exec_init;
61 struct embedded_fd_set open_fds_init;
Eric Dumazet95e861d2005-11-13 16:06:24 -080062 struct file * fd_array[NR_OPEN_DEFAULT];
Linus Torvalds1da177e2005-04-16 15:20:36 -070063};
64
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070065#define files_fdtable(files) (rcu_dereference((files)->fdt))
Dipankar Sarmabadf1662005-09-09 13:04:10 -070066
Linus Torvalds1da177e2005-04-16 15:20:36 -070067extern void FASTCALL(__fput(struct file *));
68extern void FASTCALL(fput(struct file *));
69
70static inline void fput_light(struct file *file, int fput_needed)
71{
72 if (unlikely(fput_needed))
73 fput(file);
74}
75
76extern struct file * FASTCALL(fget(unsigned int fd));
77extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
78extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
79extern void put_filp(struct file *);
80extern int get_unused_fd(void);
81extern void FASTCALL(put_unused_fd(unsigned int fd));
Pekka J Enberg2109a2d2005-11-07 00:58:01 -080082struct kmem_cache;
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
84extern struct file ** alloc_fd_array(int);
85extern void free_fd_array(struct file **, int);
86
87extern fd_set *alloc_fdset(int);
88extern void free_fdset(fd_set *, int);
89
90extern int expand_files(struct files_struct *, int nr);
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070091extern void free_fdtable(struct fdtable *fdt);
92extern void __init files_defer_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
94static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
95{
96 struct file * file = NULL;
Dipankar Sarmabadf1662005-09-09 13:04:10 -070097 struct fdtable *fdt = files_fdtable(files);
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
Dipankar Sarmabadf1662005-09-09 13:04:10 -070099 if (fd < fdt->max_fds)
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700100 file = rcu_dereference(fdt->fd[fd]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 return file;
102}
103
104/*
105 * Check whether the specified fd has an open file.
106 */
107#define fcheck(fd) fcheck_files(current->files, fd)
108
109extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
110
111struct task_struct;
112
113struct files_struct *get_files_struct(struct task_struct *);
114void FASTCALL(put_files_struct(struct files_struct *fs));
115
116#endif /* __LINUX_FILE_H */