Linux kernel mirror (for testing)
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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 __fput(struct file *);
63extern void fput(struct file *);
64
65struct file_operations;
66struct vfsmount;
67struct dentry;
68extern int init_file(struct file *, struct vfsmount *mnt,
69 struct dentry *dentry, mode_t mode,
70 const struct file_operations *fop);
71extern struct file *alloc_file(struct vfsmount *, struct dentry *dentry,
72 mode_t mode, const struct file_operations *fop);
73
74static inline void fput_light(struct file *file, int fput_needed)
75{
76 if (unlikely(fput_needed))
77 fput(file);
78}
79
80extern struct file *fget(unsigned int fd);
81extern struct file *fget_light(unsigned int fd, int *fput_needed);
82extern void set_close_on_exec(unsigned int fd, int flag);
83extern void put_filp(struct file *);
84extern int get_unused_fd(void);
85extern int get_unused_fd_flags(int flags);
86extern void put_unused_fd(unsigned int fd);
87struct kmem_cache;
88
89extern int expand_files(struct files_struct *, int nr);
90extern void free_fdtable_rcu(struct rcu_head *rcu);
91extern void __init files_defer_init(void);
92
93static inline void free_fdtable(struct fdtable *fdt)
94{
95 call_rcu(&fdt->rcu, free_fdtable_rcu);
96}
97
98static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
99{
100 struct file * file = NULL;
101 struct fdtable *fdt = files_fdtable(files);
102
103 if (fd < fdt->max_fds)
104 file = rcu_dereference(fdt->fd[fd]);
105 return file;
106}
107
108/*
109 * Check whether the specified fd has an open file.
110 */
111#define fcheck(fd) fcheck_files(current->files, fd)
112
113extern void fd_install(unsigned int fd, struct file *file);
114
115struct task_struct;
116
117struct files_struct *get_files_struct(struct task_struct *);
118void put_files_struct(struct files_struct *fs);
119void reset_files_struct(struct task_struct *, struct files_struct *);
120
121extern struct kmem_cache *files_cachep;
122
123#endif /* __LINUX_FILE_H */