blob: fbb88740634af011af6cc1be098f0a6d20aba07f [file] [log] [blame]
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;
Al Viro9f3acc32008-04-24 07:44:08 -040030};
31
David Howells1dce27c2012-02-16 17:49:42 +000032static inline bool close_on_exec(int fd, const struct fdtable *fdt)
33{
David Howells1fd36ad2012-02-16 17:49:54 +000034 return test_bit(fd, fdt->close_on_exec);
David Howells1dce27c2012-02-16 17:49:42 +000035}
36
David Howells1dce27c2012-02-16 17:49:42 +000037static inline bool fd_is_open(int fd, const struct fdtable *fdt)
38{
David Howells1fd36ad2012-02-16 17:49:54 +000039 return test_bit(fd, fdt->open_fds);
David Howells1dce27c2012-02-16 17:49:42 +000040}
41
Al Viro9f3acc32008-04-24 07:44:08 -040042/*
43 * Open file table structure
44 */
45struct files_struct {
46 /*
47 * read mostly part
48 */
49 atomic_t count;
Eric Dumazet8a812522015-06-30 15:54:08 +020050 bool resize_in_progress;
51 wait_queue_head_t resize_wait;
52
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010053 struct fdtable __rcu *fdt;
Al Viro9f3acc32008-04-24 07:44:08 -040054 struct fdtable fdtab;
55 /*
56 * written part on a separate cache line in SMP
57 */
58 spinlock_t file_lock ____cacheline_aligned_in_smp;
59 int next_fd;
David Howells1fd36ad2012-02-16 17:49:54 +000060 unsigned long close_on_exec_init[1];
61 unsigned long open_fds_init[1];
Arnd Bergmann4d2deb42010-02-24 20:01:56 +010062 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
Al Viro9f3acc32008-04-24 07:44:08 -040063};
64
Al Viro9f3acc32008-04-24 07:44:08 -040065struct file_operations;
66struct vfsmount;
67struct dentry;
68
Oleg Nesterova8d4b832014-01-11 19:19:32 +010069#define rcu_dereference_check_fdtable(files, fdtfd) \
70 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
71
72#define files_fdtable(files) \
73 rcu_dereference_check_fdtable((files), (files)->fdt)
74
75/*
76 * The caller must ensure that fd table isn't shared or hold rcu or file lock
77 */
78static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
Al Viro9f3acc32008-04-24 07:44:08 -040079{
Oleg Nesterova8d4b832014-01-11 19:19:32 +010080 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
Al Viro9f3acc32008-04-24 07:44:08 -040081
82 if (fd < fdt->max_fds)
Oleg Nesterova8d4b832014-01-11 19:19:32 +010083 return rcu_dereference_raw(fdt->fd[fd]);
84 return NULL;
85}
86
87static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
88{
89 rcu_lockdep_assert(rcu_read_lock_held() ||
90 lockdep_is_held(&files->file_lock),
91 "suspicious rcu_dereference_check() usage");
92 return __fcheck_files(files, fd);
Al Viro9f3acc32008-04-24 07:44:08 -040093}
94
95/*
96 * Check whether the specified fd has an open file.
97 */
98#define fcheck(fd) fcheck_files(current->files, fd)
99
100struct task_struct;
101
102struct files_struct *get_files_struct(struct task_struct *);
103void put_files_struct(struct files_struct *fs);
104void reset_files_struct(struct files_struct *);
105int unshare_files(struct files_struct **);
Al Viro02afc6262008-05-08 19:42:56 -0400106struct files_struct *dup_fd(struct files_struct *, int *);
Al Viro6a6d27d2012-08-21 09:56:33 -0400107void do_close_on_exec(struct files_struct *);
Al Viroc3c073f2012-08-21 22:32:06 -0400108int iterate_fd(struct files_struct *, unsigned,
109 int (*)(const void *, struct file *, unsigned),
110 const void *);
Al Viro9f3acc32008-04-24 07:44:08 -0400111
Al Virodcfadfa2012-08-12 17:27:30 -0400112extern int __alloc_fd(struct files_struct *files,
113 unsigned start, unsigned end, unsigned flags);
Al Virof869e8a2012-08-15 21:06:33 -0400114extern void __fd_install(struct files_struct *files,
115 unsigned int fd, struct file *file);
Al Viro483ce1d2012-08-19 12:04:24 -0400116extern int __close_fd(struct files_struct *files,
117 unsigned int fd);
Al Virodcfadfa2012-08-12 17:27:30 -0400118
Al Viro9f3acc32008-04-24 07:44:08 -0400119extern struct kmem_cache *files_cachep;
120
121#endif /* __LINUX_FDTABLE_H */