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 struct 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 */
41 struct 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
60 extern struct kmem_cache *filp_cachep;
61
62 extern void __fput(struct file *);
63 extern void fput(struct file *);
64
65 struct file_operations;
66 struct vfsmount;
67 struct dentry;
68 extern int init_file(struct file *, struct vfsmount *mnt,
69 struct dentry *dentry, mode_t mode,
70 const struct file_operations *fop);
71 extern struct file *alloc_file(struct vfsmount *, struct dentry *dentry,
72 mode_t mode, const struct file_operations *fop);
73
74 static inline void fput_light(struct file *file, int fput_needed)
75 {
76 if (unlikely(fput_needed))
77 fput(file);
78 }
79
80 extern struct file *fget(unsigned int fd);
81 extern struct file *fget_light(unsigned int fd, int *fput_needed);
82 extern void set_close_on_exec(unsigned int fd, int flag);
83 extern void put_filp(struct file *);
84 extern int get_unused_fd(void);
85 extern int get_unused_fd_flags(int flags);
86 extern void put_unused_fd(unsigned int fd);
87 struct kmem_cache;
88
89 extern int expand_files(struct files_struct *, int nr);
90 extern void free_fdtable_rcu(struct rcu_head *rcu);
91 extern void __init files_defer_init(void);
92
93 static inline void free_fdtable(struct fdtable *fdt)
94 {
95 call_rcu(&fdt->rcu, free_fdtable_rcu);
96 }
97
98 static 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
113 extern void fd_install(unsigned int fd, struct file *file);
114
115 struct task_struct;
116
117 struct files_struct *get_files_struct(struct task_struct *);
118 void put_files_struct(struct files_struct *fs);
119 void reset_files_struct(struct task_struct *, struct files_struct *);
120
121 extern struct kmem_cache *files_cachep;
122
123 #endif /* __LINUX_FILE_H */
124
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