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 */
25 struct embedded_fd_set {
26 unsigned long fds_bits[1];
27 };
28
29 /*
30 * More than this number of fds: we use a separately allocated fd_set
31 */
32 #define EMBEDDED_FD_SET_SIZE (BITS_PER_BYTE * sizeof(struct embedded_fd_set))
33
34 struct fdtable {
35 unsigned int max_fds;
36 int max_fdset;
37 struct file ** fd; /* current fd array */
38 fd_set *close_on_exec;
39 fd_set *open_fds;
40 struct rcu_head rcu;
41 struct files_struct *free_files;
42 struct fdtable *next;
43 };
44
45 /*
46 * Open file table structure
47 */
48 struct files_struct {
49 /*
50 * read mostly part
51 */
52 atomic_t count;
53 struct fdtable *fdt;
54 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;
60 struct embedded_fd_set close_on_exec_init;
61 struct embedded_fd_set open_fds_init;
62 struct file * fd_array[NR_OPEN_DEFAULT];
63 };
64
65 #define files_fdtable(files) (rcu_dereference((files)->fdt))
66
67 extern void FASTCALL(__fput(struct file *));
68 extern void FASTCALL(fput(struct file *));
69
fput_light(struct file * file,int fput_needed)70 static inline void fput_light(struct file *file, int fput_needed)
71 {
72 if (unlikely(fput_needed))
73 fput(file);
74 }
75
76 extern struct file * FASTCALL(fget(unsigned int fd));
77 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
78 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
79 extern void put_filp(struct file *);
80 extern int get_unused_fd(void);
81 extern void FASTCALL(put_unused_fd(unsigned int fd));
82 struct kmem_cache;
83
84 extern struct file ** alloc_fd_array(int);
85 extern void free_fd_array(struct file **, int);
86
87 extern fd_set *alloc_fdset(int);
88 extern void free_fdset(fd_set *, int);
89
90 extern int expand_files(struct files_struct *, int nr);
91 extern void free_fdtable(struct fdtable *fdt);
92 extern void __init files_defer_init(void);
93
fcheck_files(struct files_struct * files,unsigned int fd)94 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
95 {
96 struct file * file = NULL;
97 struct fdtable *fdt = files_fdtable(files);
98
99 if (fd < fdt->max_fds)
100 file = rcu_dereference(fdt->fd[fd]);
101 return file;
102 }
103
104 /*
105 * Check whether the specified fd has an open file.
106 */
107 #define fcheck(fd) fcheck_files(current->files, fd)
108
109 extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
110
111 struct task_struct;
112
113 struct files_struct *get_files_struct(struct task_struct *);
114 void FASTCALL(put_files_struct(struct files_struct *fs));
115
116 #endif /* __LINUX_FILE_H */
117