2 * Wrapper functions for accessing the file_struct fd array.
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>
16 * The default fd array needs to be at least BITS_PER_LONG,
17 * as this is the granularity returned by copy_fdset().
19 #define NR_OPEN_DEFAULT BITS_PER_LONG
22 * The embedded_fd_set is a small fd_set,
23 * suitable for most tasks (which open <= BITS_PER_LONG files)
25 struct embedded_fd_set {
26 unsigned long fds_bits[1];
31 struct file ** fd; /* current fd array */
32 fd_set *close_on_exec;
35 struct files_struct *free_files;
40 * Open file table structure
50 * written part on a separate cache line in SMP
52 spinlock_t file_lock ____cacheline_aligned_in_smp;
54 struct embedded_fd_set close_on_exec_init;
55 struct embedded_fd_set open_fds_init;
56 struct file * fd_array[NR_OPEN_DEFAULT];
59 #define files_fdtable(files) (rcu_dereference((files)->fdt))
61 extern struct kmem_cache *filp_cachep;
63 extern void FASTCALL(__fput(struct file *));
64 extern void FASTCALL(fput(struct file *));
66 static inline void fput_light(struct file *file, int fput_needed)
68 if (unlikely(fput_needed))
72 extern struct file * FASTCALL(fget(unsigned int fd));
73 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
74 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
75 extern void put_filp(struct file *);
76 extern int get_unused_fd(void);
77 extern void FASTCALL(put_unused_fd(unsigned int fd));
80 extern struct file ** alloc_fd_array(int);
81 extern void free_fd_array(struct file **, int);
83 extern fd_set *alloc_fdset(int);
84 extern void free_fdset(fd_set *, int);
86 extern int expand_files(struct files_struct *, int nr);
87 extern void free_fdtable(struct fdtable *fdt);
88 extern void __init files_defer_init(void);
90 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
92 struct file * file = NULL;
93 struct fdtable *fdt = files_fdtable(files);
95 if (fd < fdt->max_fds)
96 file = rcu_dereference(fdt->fd[fd]);
101 * Check whether the specified fd has an open file.
103 #define fcheck(fd) fcheck_files(current->files, fd)
105 extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
109 struct files_struct *get_files_struct(struct task_struct *);
110 void FASTCALL(put_files_struct(struct files_struct *fs));
111 void reset_files_struct(struct task_struct *, struct files_struct *);
113 extern struct kmem_cache *files_cachep;
115 #endif /* __LINUX_FILE_H */