Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Wrapper functions for accessing the file_struct fd array.
3 */
4
5#ifndef __LINUX_FILE_H
6#define __LINUX_FILE_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
60extern struct kmem_cache *filp_cachep;
61
62extern void FASTCALL(__fput(struct file *));
63extern void FASTCALL(fput(struct file *));
64
65static inline void fput_light(struct file *file, int fput_needed)
66{
67 if (unlikely(fput_needed))
68 fput(file);
69}
70
71extern struct file * FASTCALL(fget(unsigned int fd));
72extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
73extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
74extern void put_filp(struct file *);
75extern int get_unused_fd(void);
76extern void FASTCALL(put_unused_fd(unsigned int fd));
77struct kmem_cache;
78
79extern int expand_files(struct files_struct *, int nr);
80extern void free_fdtable_rcu(struct rcu_head *rcu);
81extern void __init files_defer_init(void);
82
83static inline void free_fdtable(struct fdtable *fdt)
84{
85 call_rcu(&fdt->rcu, free_fdtable_rcu);
86}
87
88static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
89{
90 struct file * file = NULL;
91 struct fdtable *fdt = files_fdtable(files);
92
93 if (fd < fdt->max_fds)
94 file = rcu_dereference(fdt->fd[fd]);
95 return file;
96}
97
98/*
99 * Check whether the specified fd has an open file.
100 */
101#define fcheck(fd) fcheck_files(current->files, fd)
102
103extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
104
105struct task_struct;
106
107struct files_struct *get_files_struct(struct task_struct *);
108void FASTCALL(put_files_struct(struct files_struct *fs));
109void reset_files_struct(struct task_struct *, struct files_struct *);
110
111extern struct kmem_cache *files_cachep;
112
113#endif /* __LINUX_FILE_H */