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 <asm/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/* 25 * The embedded_fd_set is a small fd_set, 26 * suitable for most tasks (which open <= BITS_PER_LONG files) 27 */ 28struct embedded_fd_set { 29 unsigned long fds_bits[1]; 30}; 31 32struct fdtable { 33 unsigned int max_fds; 34 struct file ** fd; /* current fd array */ 35 fd_set *close_on_exec; 36 fd_set *open_fds; 37 struct rcu_head rcu; 38 struct fdtable *next; 39}; 40 41/* 42 * Open file table structure 43 */ 44struct files_struct { 45 /* 46 * read mostly part 47 */ 48 atomic_t count; 49 struct fdtable *fdt; 50 struct fdtable fdtab; 51 /* 52 * written part on a separate cache line in SMP 53 */ 54 spinlock_t file_lock ____cacheline_aligned_in_smp; 55 int next_fd; 56 struct embedded_fd_set close_on_exec_init; 57 struct embedded_fd_set open_fds_init; 58 struct file * fd_array[NR_OPEN_DEFAULT]; 59}; 60 61#define rcu_dereference_check_fdtable(files, fdtfd) \ 62 (rcu_dereference_check((fdtfd), \ 63 rcu_read_lock_held() || \ 64 lockdep_is_held(&(files)->file_lock) || \ 65 atomic_read(&(files)->count) == 1 || \ 66 rcu_my_thread_group_empty())) 67 68#define files_fdtable(files) \ 69 (rcu_dereference_check_fdtable((files), (files)->fdt)) 70 71struct file_operations; 72struct vfsmount; 73struct dentry; 74 75extern int expand_files(struct files_struct *, int nr); 76extern void free_fdtable_rcu(struct rcu_head *rcu); 77extern void __init files_defer_init(void); 78 79static inline void free_fdtable(struct fdtable *fdt) 80{ 81 call_rcu(&fdt->rcu, free_fdtable_rcu); 82} 83 84static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 85{ 86 struct file * file = NULL; 87 struct fdtable *fdt = files_fdtable(files); 88 89 if (fd < fdt->max_fds) 90 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); 91 return file; 92} 93 94/* 95 * Check whether the specified fd has an open file. 96 */ 97#define fcheck(fd) fcheck_files(current->files, fd) 98 99struct task_struct; 100 101struct files_struct *get_files_struct(struct task_struct *); 102void put_files_struct(struct files_struct *fs); 103void reset_files_struct(struct files_struct *); 104int unshare_files(struct files_struct **); 105struct files_struct *dup_fd(struct files_struct *, int *); 106 107extern struct kmem_cache *files_cachep; 108 109#endif /* __LINUX_FDTABLE_H */ 110