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Al Viro9f3acc32008-04-24 07:44:08 -04001/*
2 * descriptor table internals; you almost certainly want file.h instead.
3 */
4
5#ifndef __LINUX_FDTABLE_H
6#define __LINUX_FDTABLE_H
7
Al Viro9f3acc32008-04-24 07:44:08 -04008#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>
Ingo Molnar21e54452009-03-25 16:29:05 +010013#include <linux/init.h>
Paul E. McKenney2c666df2010-04-29 20:48:47 -070014#include <linux/fs.h>
Ingo Molnar21e54452009-03-25 16:29:05 +010015
Arun Sharma600634972011-07-26 16:09:06 -070016#include <linux/atomic.h>
Al Viro9f3acc32008-04-24 07:44:08 -040017
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
Al Viro9f3acc32008-04-24 07:44:08 -040024struct fdtable {
25 unsigned int max_fds;
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010026 struct file __rcu **fd; /* current fd array */
David Howells1fd36ad2012-02-16 17:49:54 +000027 unsigned long *close_on_exec;
28 unsigned long *open_fds;
Al Viro9f3acc32008-04-24 07:44:08 -040029 struct rcu_head rcu;
30 struct fdtable *next;
31};
32
David Howells1dce27c2012-02-16 17:49:42 +000033static inline bool close_on_exec(int fd, const struct fdtable *fdt)
34{
David Howells1fd36ad2012-02-16 17:49:54 +000035 return test_bit(fd, fdt->close_on_exec);
David Howells1dce27c2012-02-16 17:49:42 +000036}
37
David Howells1dce27c2012-02-16 17:49:42 +000038static inline bool fd_is_open(int fd, const struct fdtable *fdt)
39{
David Howells1fd36ad2012-02-16 17:49:54 +000040 return test_bit(fd, fdt->open_fds);
David Howells1dce27c2012-02-16 17:49:42 +000041}
42
Al Viro9f3acc32008-04-24 07:44:08 -040043/*
44 * Open file table structure
45 */
46struct files_struct {
47 /*
48 * read mostly part
49 */
50 atomic_t count;
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010051 struct fdtable __rcu *fdt;
Al Viro9f3acc32008-04-24 07:44:08 -040052 struct fdtable fdtab;
53 /*
54 * written part on a separate cache line in SMP
55 */
56 spinlock_t file_lock ____cacheline_aligned_in_smp;
57 int next_fd;
David Howells1fd36ad2012-02-16 17:49:54 +000058 unsigned long close_on_exec_init[1];
59 unsigned long open_fds_init[1];
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010060 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
Al Viro9f3acc32008-04-24 07:44:08 -040061};
62
Paul E. McKenneyaf61b962010-02-22 17:04:53 -080063#define rcu_dereference_check_fdtable(files, fdtfd) \
64 (rcu_dereference_check((fdtfd), \
Paul E. McKenney7dc52152010-02-22 17:04:52 -080065 lockdep_is_held(&(files)->file_lock) || \
Paul E. McKenney844b9a82010-07-20 13:24:34 -070066 atomic_read(&(files)->count) == 1 || \
67 rcu_my_thread_group_empty()))
Paul E. McKenneyaf61b962010-02-22 17:04:53 -080068
69#define files_fdtable(files) \
70 (rcu_dereference_check_fdtable((files), (files)->fdt))
Al Viro9f3acc32008-04-24 07:44:08 -040071
Al Viro9f3acc32008-04-24 07:44:08 -040072struct file_operations;
73struct vfsmount;
74struct dentry;
75
Al Viro9f3acc32008-04-24 07:44:08 -040076extern void __init files_defer_init(void);
77
Al Viro9f3acc32008-04-24 07:44:08 -040078static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
79{
80 struct file * file = NULL;
81 struct fdtable *fdt = files_fdtable(files);
82
83 if (fd < fdt->max_fds)
Paul E. McKenneyaf61b962010-02-22 17:04:53 -080084 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
Al Viro9f3acc32008-04-24 07:44:08 -040085 return file;
86}
87
88/*
89 * Check whether the specified fd has an open file.
90 */
91#define fcheck(fd) fcheck_files(current->files, fd)
92
93struct task_struct;
94
95struct files_struct *get_files_struct(struct task_struct *);
96void put_files_struct(struct files_struct *fs);
97void reset_files_struct(struct files_struct *);
98int unshare_files(struct files_struct **);
Al Viro02afc6262008-05-08 19:42:56 -040099struct files_struct *dup_fd(struct files_struct *, int *);
Al Viro6a6d27d2012-08-21 09:56:33 -0400100void do_close_on_exec(struct files_struct *);
Al Viroc3c073f2012-08-21 22:32:06 -0400101int iterate_fd(struct files_struct *, unsigned,
102 int (*)(const void *, struct file *, unsigned),
103 const void *);
Al Viro9f3acc32008-04-24 07:44:08 -0400104
Al Virodcfadfa2012-08-12 17:27:30 -0400105extern int __alloc_fd(struct files_struct *files,
106 unsigned start, unsigned end, unsigned flags);
Al Virof869e8a2012-08-15 21:06:33 -0400107extern void __fd_install(struct files_struct *files,
108 unsigned int fd, struct file *file);
Al Viro483ce1d2012-08-19 12:04:24 -0400109extern int __close_fd(struct files_struct *files,
110 unsigned int fd);
Al Virodcfadfa2012-08-12 17:27:30 -0400111
Al Viro9f3acc32008-04-24 07:44:08 -0400112extern struct kmem_cache *files_cachep;
113
114#endif /* __LINUX_FDTABLE_H */