file.h revision c559cd81139f97cecad1ad91a0b2e25a5936d531
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 */ 25struct 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 34struct 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 */ 48struct 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 67extern void FASTCALL(__fput(struct file *)); 68extern void FASTCALL(fput(struct file *)); 69 70static inline void fput_light(struct file *file, int fput_needed) 71{ 72 if (unlikely(fput_needed)) 73 fput(file); 74} 75 76extern struct file * FASTCALL(fget(unsigned int fd)); 77extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed)); 78extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag)); 79extern void put_filp(struct file *); 80extern int get_unused_fd(void); 81extern void FASTCALL(put_unused_fd(unsigned int fd)); 82struct kmem_cache; 83 84extern struct file ** alloc_fd_array(int); 85extern void free_fd_array(struct file **, int); 86 87extern fd_set *alloc_fdset(int); 88extern void free_fdset(fd_set *, int); 89 90extern int expand_files(struct files_struct *, int nr); 91extern void free_fdtable(struct fdtable *fdt); 92extern void __init files_defer_init(void); 93 94static 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 109extern void FASTCALL(fd_install(unsigned int fd, struct file * file)); 110 111struct task_struct; 112 113struct files_struct *get_files_struct(struct task_struct *); 114void FASTCALL(put_files_struct(struct files_struct *fs)); 115 116#endif /* __LINUX_FILE_H */ 117