projects/linux·blob v3.15 · refs

118 lines · 3.0 KiB

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
24struct 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 struct rcu_head rcu;
30};
31
32static inline bool close_on_exec(int fd, const struct fdtable *fdt)
33{
34 return test_bit(fd, fdt->close_on_exec);
35}
36
37static inline bool fd_is_open(int fd, const struct fdtable *fdt)
38{
39 return test_bit(fd, fdt->open_fds);
40}
41
42/*
43 * Open file table structure
44 */
45struct files_struct {
46 /*
47 * read mostly part
48 */
49 atomic_t count;
50 struct fdtable __rcu *fdt;
51 struct fdtable fdtab;
52 /*
53 * written part on a separate cache line in SMP
54 */
55 spinlock_t file_lock ____cacheline_aligned_in_smp;
56 int next_fd;
57 unsigned long close_on_exec_init[1];
58 unsigned long open_fds_init[1];
59 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
60};
61
62struct file_operations;
63struct vfsmount;
64struct dentry;
65
66#define rcu_dereference_check_fdtable(files, fdtfd) \
67 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
68
69#define files_fdtable(files) \
70 rcu_dereference_check_fdtable((files), (files)->fdt)
71
72/*
73 * The caller must ensure that fd table isn't shared or hold rcu or file lock
74 */
75static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
76{
77 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
78
79 if (fd < fdt->max_fds)
80 return rcu_dereference_raw(fdt->fd[fd]);
81 return NULL;
82}
83
84static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
85{
86 rcu_lockdep_assert(rcu_read_lock_held() ||
87 lockdep_is_held(&files->file_lock),
88 "suspicious rcu_dereference_check() usage");
89 return __fcheck_files(files, fd);
90}
91
92/*
93 * Check whether the specified fd has an open file.
94 */
95#define fcheck(fd) fcheck_files(current->files, fd)
96
97struct task_struct;
98
99struct files_struct *get_files_struct(struct task_struct *);
100void put_files_struct(struct files_struct *fs);
101void reset_files_struct(struct files_struct *);
102int unshare_files(struct files_struct **);
103struct files_struct *dup_fd(struct files_struct *, int *);
104void do_close_on_exec(struct files_struct *);
105int iterate_fd(struct files_struct *, unsigned,
106 int (*)(const void *, struct file *, unsigned),
107 const void *);
108
109extern int __alloc_fd(struct files_struct *files,
110 unsigned start, unsigned end, unsigned flags);
111extern void __fd_install(struct files_struct *files,
112 unsigned int fd, struct file *file);
113extern int __close_fd(struct files_struct *files,
114 unsigned int fd);
115
116extern struct kmem_cache *files_cachep;
117
118#endif /* __LINUX_FDTABLE_H */