blob: 09d6c5bbdddd50c9ba4248dc30e023c936c2404b [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
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 */
25struct embedded_fd_set {
26 unsigned long fds_bits[1];
27};
28
29struct 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 */
41struct 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
Al Viro9f3acc32008-04-24 07:44:08 -040060struct file_operations;
61struct vfsmount;
62struct dentry;
63
64extern int expand_files(struct files_struct *, int nr);
65extern void free_fdtable_rcu(struct rcu_head *rcu);
66extern void __init files_defer_init(void);
67
68static inline void free_fdtable(struct fdtable *fdt)
69{
70 call_rcu(&fdt->rcu, free_fdtable_rcu);
71}
72
73static 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
88struct task_struct;
89
90struct files_struct *get_files_struct(struct task_struct *);
91void put_files_struct(struct files_struct *fs);
92void reset_files_struct(struct files_struct *);
93int unshare_files(struct files_struct **);
Al Viro02afc6262008-05-08 19:42:56 -040094struct files_struct *dup_fd(struct files_struct *, int *);
Al Viro9f3acc32008-04-24 07:44:08 -040095
96extern struct kmem_cache *files_cachep;
97
98#endif /* __LINUX_FDTABLE_H */