blob: 82163c4b32c9fa89cd2869e369f0a5c39239c5c1 [file] [log] [blame]
Al Viro9f3acc32008-04-24 07:44:08 -04001/*
2 * descriptor table internals; you almost certainly want file.h instead.
3 */
4
5#ifndef __LINUX_FDTABLE_H
6#define __LINUX_FDTABLE_H
7
Al Viro9f3acc32008-04-24 07:44:08 -04008#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>
Ingo Molnar21e54452009-03-25 16:29:05 +010013#include <linux/init.h>
Paul E. McKenney2c666df2010-04-29 20:48:47 -070014#include <linux/fs.h>
Ingo Molnar21e54452009-03-25 16:29:05 +010015
Arun Sharma60063492011-07-26 16:09:06 -070016#include <linux/atomic.h>
Al Viro9f3acc32008-04-24 07:44:08 -040017
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 */
28struct embedded_fd_set {
29 unsigned long fds_bits[1];
30};
31
32struct fdtable {
33 unsigned int max_fds;
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010034 struct file __rcu **fd; /* current fd array */
Al Viro9f3acc32008-04-24 07:44:08 -040035 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 */
44struct files_struct {
45 /*
46 * read mostly part
47 */
48 atomic_t count;
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010049 struct fdtable __rcu *fdt;
Al Viro9f3acc32008-04-24 07:44:08 -040050 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;
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010058 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
Al Viro9f3acc32008-04-24 07:44:08 -040059};
60
Paul E. McKenneyaf61b962010-02-22 17:04:53 -080061#define rcu_dereference_check_fdtable(files, fdtfd) \
62 (rcu_dereference_check((fdtfd), \
Paul E. McKenney7dc52152010-02-22 17:04:52 -080063 lockdep_is_held(&(files)->file_lock) || \
Paul E. McKenney844b9a82010-07-20 13:24:34 -070064 atomic_read(&(files)->count) == 1 || \
65 rcu_my_thread_group_empty()))
Paul E. McKenneyaf61b962010-02-22 17:04:53 -080066
67#define files_fdtable(files) \
68 (rcu_dereference_check_fdtable((files), (files)->fdt))
Al Viro9f3acc32008-04-24 07:44:08 -040069
Al Viro9f3acc32008-04-24 07:44:08 -040070struct file_operations;
71struct vfsmount;
72struct dentry;
73
74extern int expand_files(struct files_struct *, int nr);
75extern void free_fdtable_rcu(struct rcu_head *rcu);
76extern void __init files_defer_init(void);
77
78static inline void free_fdtable(struct fdtable *fdt)
79{
80 call_rcu(&fdt->rcu, free_fdtable_rcu);
81}
82
83static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
84{
85 struct file * file = NULL;
86 struct fdtable *fdt = files_fdtable(files);
87
88 if (fd < fdt->max_fds)
Paul E. McKenneyaf61b962010-02-22 17:04:53 -080089 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
Al Viro9f3acc32008-04-24 07:44:08 -040090 return file;
91}
92
93/*
94 * Check whether the specified fd has an open file.
95 */
96#define fcheck(fd) fcheck_files(current->files, fd)
97
98struct task_struct;
99
100struct files_struct *get_files_struct(struct task_struct *);
101void put_files_struct(struct files_struct *fs);
102void reset_files_struct(struct files_struct *);
103int unshare_files(struct files_struct **);
Al Viro02afc622008-05-08 19:42:56 -0400104struct files_struct *dup_fd(struct files_struct *, int *);
Al Viro9f3acc32008-04-24 07:44:08 -0400105
106extern struct kmem_cache *files_cachep;
107
108#endif /* __LINUX_FDTABLE_H */