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 <linux/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 struct fdtable { 25 unsigned int max_fds; 26 struct file __rcu **fd; /* current fd array */ 27 unsigned long *close_on_exec; 28 unsigned long *open_fds; 29 struct rcu_head rcu; 30 struct fdtable *next; 31 }; 32 33 static inline void __set_close_on_exec(int fd, struct fdtable *fdt) 34 { 35 __set_bit(fd, fdt->close_on_exec); 36 } 37 38 static inline void __clear_close_on_exec(int fd, struct fdtable *fdt) 39 { 40 __clear_bit(fd, fdt->close_on_exec); 41 } 42 43 static inline bool close_on_exec(int fd, const struct fdtable *fdt) 44 { 45 return test_bit(fd, fdt->close_on_exec); 46 } 47 48 static inline void __set_open_fd(int fd, struct fdtable *fdt) 49 { 50 __set_bit(fd, fdt->open_fds); 51 } 52 53 static inline void __clear_open_fd(int fd, struct fdtable *fdt) 54 { 55 __clear_bit(fd, fdt->open_fds); 56 } 57 58 static inline bool fd_is_open(int fd, const struct fdtable *fdt) 59 { 60 return test_bit(fd, fdt->open_fds); 61 } 62 63 /* 64 * Open file table structure 65 */ 66 struct files_struct { 67 /* 68 * read mostly part 69 */ 70 atomic_t count; 71 struct fdtable __rcu *fdt; 72 struct fdtable fdtab; 73 /* 74 * written part on a separate cache line in SMP 75 */ 76 spinlock_t file_lock ____cacheline_aligned_in_smp; 77 int next_fd; 78 unsigned long close_on_exec_init[1]; 79 unsigned long open_fds_init[1]; 80 struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 81 }; 82 83 #define rcu_dereference_check_fdtable(files, fdtfd) \ 84 (rcu_dereference_check((fdtfd), \ 85 lockdep_is_held(&(files)->file_lock) || \ 86 atomic_read(&(files)->count) == 1 || \ 87 rcu_my_thread_group_empty())) 88 89 #define files_fdtable(files) \ 90 (rcu_dereference_check_fdtable((files), (files)->fdt)) 91 92 struct file_operations; 93 struct vfsmount; 94 struct dentry; 95 96 extern int expand_files(struct files_struct *, int nr); 97 extern void free_fdtable_rcu(struct rcu_head *rcu); 98 extern void __init files_defer_init(void); 99 100 static inline void free_fdtable(struct fdtable *fdt) 101 { 102 call_rcu(&fdt->rcu, free_fdtable_rcu); 103 } 104 105 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 106 { 107 struct file * file = NULL; 108 struct fdtable *fdt = files_fdtable(files); 109 110 if (fd < fdt->max_fds) 111 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); 112 return file; 113 } 114 115 /* 116 * Check whether the specified fd has an open file. 117 */ 118 #define fcheck(fd) fcheck_files(current->files, fd) 119 120 struct task_struct; 121 122 struct files_struct *get_files_struct(struct task_struct *); 123 void put_files_struct(struct files_struct *fs); 124 void reset_files_struct(struct files_struct *); 125 int unshare_files(struct files_struct **); 126 struct files_struct *dup_fd(struct files_struct *, int *); 127 128 extern struct kmem_cache *files_cachep; 129 130 #endif /* __LINUX_FDTABLE_H */ 131