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
24 struct 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 unsigned long *full_fds_bits;
30 struct rcu_head rcu;
31 };
32
close_on_exec(int fd,const struct fdtable * fdt)33 static inline bool close_on_exec(int fd, const struct fdtable *fdt)
34 {
35 return test_bit(fd, fdt->close_on_exec);
36 }
37
fd_is_open(int fd,const struct fdtable * fdt)38 static inline bool fd_is_open(int fd, const struct fdtable *fdt)
39 {
40 return test_bit(fd, fdt->open_fds);
41 }
42
43 /*
44 * Open file table structure
45 */
46 struct files_struct {
47 /*
48 * read mostly part
49 */
50 atomic_t count;
51 bool resize_in_progress;
52 wait_queue_head_t resize_wait;
53
54 struct fdtable __rcu *fdt;
55 struct fdtable fdtab;
56 /*
57 * written part on a separate cache line in SMP
58 */
59 spinlock_t file_lock ____cacheline_aligned_in_smp;
60 int next_fd;
61 unsigned long close_on_exec_init[1];
62 unsigned long open_fds_init[1];
63 unsigned long full_fds_bits_init[1];
64 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
65 };
66
67 struct file_operations;
68 struct vfsmount;
69 struct dentry;
70
71 #define rcu_dereference_check_fdtable(files, fdtfd) \
72 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
73
74 #define files_fdtable(files) \
75 rcu_dereference_check_fdtable((files), (files)->fdt)
76
77 /*
78 * The caller must ensure that fd table isn't shared or hold rcu or file lock
79 */
__fcheck_files(struct files_struct * files,unsigned int fd)80 static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
81 {
82 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
83
84 if (fd < fdt->max_fds)
85 return rcu_dereference_raw(fdt->fd[fd]);
86 return NULL;
87 }
88
fcheck_files(struct files_struct * files,unsigned int fd)89 static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
90 {
91 RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
92 !lockdep_is_held(&files->file_lock),
93 "suspicious rcu_dereference_check() usage");
94 return __fcheck_files(files, fd);
95 }
96
97 /*
98 * Check whether the specified fd has an open file.
99 */
100 #define fcheck(fd) fcheck_files(current->files, fd)
101
102 struct task_struct;
103
104 struct files_struct *get_files_struct(struct task_struct *);
105 void put_files_struct(struct files_struct *fs);
106 void reset_files_struct(struct files_struct *);
107 int unshare_files(struct files_struct **);
108 struct files_struct *dup_fd(struct files_struct *, int *);
109 void do_close_on_exec(struct files_struct *);
110 int iterate_fd(struct files_struct *, unsigned,
111 int (*)(const void *, struct file *, unsigned),
112 const void *);
113
114 extern int __alloc_fd(struct files_struct *files,
115 unsigned start, unsigned end, unsigned flags);
116 extern void __fd_install(struct files_struct *files,
117 unsigned int fd, struct file *file);
118 extern int __close_fd(struct files_struct *files,
119 unsigned int fd);
120
121 extern struct kmem_cache *files_cachep;
122
123 #endif /* __LINUX_FDTABLE_H */
124