Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 struct fdtable *next;
31};
32
33static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
34{
35 __set_bit(fd, fdt->close_on_exec);
36}
37
38static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
39{
40 __clear_bit(fd, fdt->close_on_exec);
41}
42
43static inline bool close_on_exec(int fd, const struct fdtable *fdt)
44{
45 return test_bit(fd, fdt->close_on_exec);
46}
47
48static inline void __set_open_fd(int fd, struct fdtable *fdt)
49{
50 __set_bit(fd, fdt->open_fds);
51}
52
53static inline void __clear_open_fd(int fd, struct fdtable *fdt)
54{
55 __clear_bit(fd, fdt->open_fds);
56}
57
58static inline bool fd_is_open(int fd, const struct fdtable *fdt)
59{
60 return test_bit(fd, fdt->open_fds);
61}
62
63/*
64 * Open file table structure
65 */
66struct files_struct {
67 /*
68 * read mostly part
69 */
70 atomic_t count;
71 struct fdtable __rcu *fdt;
72 struct fdtable fdtab;
73 /*
74 * written part on a separate cache line in SMP
75 */
76 spinlock_t file_lock ____cacheline_aligned_in_smp;
77 int next_fd;
78 unsigned long close_on_exec_init[1];
79 unsigned long open_fds_init[1];
80 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
81};
82
83#define rcu_dereference_check_fdtable(files, fdtfd) \
84 (rcu_dereference_check((fdtfd), \
85 lockdep_is_held(&(files)->file_lock) || \
86 atomic_read(&(files)->count) == 1 || \
87 rcu_my_thread_group_empty()))
88
89#define files_fdtable(files) \
90 (rcu_dereference_check_fdtable((files), (files)->fdt))
91
92struct file_operations;
93struct vfsmount;
94struct dentry;
95
96extern int expand_files(struct files_struct *, int nr);
97extern void free_fdtable_rcu(struct rcu_head *rcu);
98extern void __init files_defer_init(void);
99
100static inline void free_fdtable(struct fdtable *fdt)
101{
102 call_rcu(&fdt->rcu, free_fdtable_rcu);
103}
104
105static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
106{
107 struct file * file = NULL;
108 struct fdtable *fdt = files_fdtable(files);
109
110 if (fd < fdt->max_fds)
111 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
112 return file;
113}
114
115/*
116 * Check whether the specified fd has an open file.
117 */
118#define fcheck(fd) fcheck_files(current->files, fd)
119
120struct task_struct;
121
122struct files_struct *get_files_struct(struct task_struct *);
123void put_files_struct(struct files_struct *fs);
124void reset_files_struct(struct files_struct *);
125int unshare_files(struct files_struct **);
126struct files_struct *dup_fd(struct files_struct *, int *);
127
128extern struct kmem_cache *files_cachep;
129
130#endif /* __LINUX_FDTABLE_H */