Linux kernel mirror (for testing)
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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
15#include <asm/atomic.h>
16
17/*
18 * The default fd array needs to be at least BITS_PER_LONG,
19 * as this is the granularity returned by copy_fdset().
20 */
21#define NR_OPEN_DEFAULT BITS_PER_LONG
22
23/*
24 * The embedded_fd_set is a small fd_set,
25 * suitable for most tasks (which open <= BITS_PER_LONG files)
26 */
27struct embedded_fd_set {
28 unsigned long fds_bits[1];
29};
30
31struct fdtable {
32 unsigned int max_fds;
33 struct file ** fd; /* current fd array */
34 fd_set *close_on_exec;
35 fd_set *open_fds;
36 struct rcu_head rcu;
37 struct fdtable *next;
38};
39
40/*
41 * Open file table structure
42 */
43struct files_struct {
44 /*
45 * read mostly part
46 */
47 atomic_t count;
48 struct fdtable *fdt;
49 struct fdtable fdtab;
50 /*
51 * written part on a separate cache line in SMP
52 */
53 spinlock_t file_lock ____cacheline_aligned_in_smp;
54 int next_fd;
55 struct embedded_fd_set close_on_exec_init;
56 struct embedded_fd_set open_fds_init;
57 struct file * fd_array[NR_OPEN_DEFAULT];
58};
59
60#define rcu_dereference_check_fdtable(files, fdtfd) \
61 (rcu_dereference_check((fdtfd), \
62 rcu_read_lock_held() || \
63 lockdep_is_held(&(files)->file_lock) || \
64 atomic_read(&(files)->count) == 1 || \
65 rcu_my_thread_group_empty()))
66
67#define files_fdtable(files) \
68 (rcu_dereference_check_fdtable((files), (files)->fdt))
69
70struct 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)
89 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
90 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 **);
104struct files_struct *dup_fd(struct files_struct *, int *);
105
106extern struct kmem_cache *files_cachep;
107
108#endif /* __LINUX_FDTABLE_H */