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 }; 31 32 static inline bool close_on_exec(int fd, const struct fdtable *fdt) 33 { 34 return test_bit(fd, fdt->close_on_exec); 35 } 36 37 static inline bool fd_is_open(int fd, const struct fdtable *fdt) 38 { 39 return test_bit(fd, fdt->open_fds); 40 } 41 42 /* 43 * Open file table structure 44 */ 45 struct files_struct { 46 /* 47 * read mostly part 48 */ 49 atomic_t count; 50 struct fdtable __rcu *fdt; 51 struct fdtable fdtab; 52 /* 53 * written part on a separate cache line in SMP 54 */ 55 spinlock_t file_lock ____cacheline_aligned_in_smp; 56 int next_fd; 57 unsigned long close_on_exec_init[1]; 58 unsigned long open_fds_init[1]; 59 struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 60 }; 61 62 struct file_operations; 63 struct vfsmount; 64 struct dentry; 65 66 extern void __init files_defer_init(void); 67 68 #define rcu_dereference_check_fdtable(files, fdtfd) \ 69 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock)) 70 71 #define files_fdtable(files) \ 72 rcu_dereference_check_fdtable((files), (files)->fdt) 73 74 /* 75 * The caller must ensure that fd table isn't shared or hold rcu or file lock 76 */ 77 static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd) 78 { 79 struct fdtable *fdt = rcu_dereference_raw(files->fdt); 80 81 if (fd < fdt->max_fds) 82 return rcu_dereference_raw(fdt->fd[fd]); 83 return NULL; 84 } 85 86 static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd) 87 { 88 rcu_lockdep_assert(rcu_read_lock_held() || 89 lockdep_is_held(&files->file_lock), 90 "suspicious rcu_dereference_check() usage"); 91 return __fcheck_files(files, fd); 92 } 93 94 /* 95 * Check whether the specified fd has an open file. 96 */ 97 #define fcheck(fd) fcheck_files(current->files, fd) 98 99 struct task_struct; 100 101 struct files_struct *get_files_struct(struct task_struct *); 102 void put_files_struct(struct files_struct *fs); 103 void reset_files_struct(struct files_struct *); 104 int unshare_files(struct files_struct **); 105 struct files_struct *dup_fd(struct files_struct *, int *); 106 void do_close_on_exec(struct files_struct *); 107 int iterate_fd(struct files_struct *, unsigned, 108 int (*)(const void *, struct file *, unsigned), 109 const void *); 110 111 extern int __alloc_fd(struct files_struct *files, 112 unsigned start, unsigned end, unsigned flags); 113 extern void __fd_install(struct files_struct *files, 114 unsigned int fd, struct file *file); 115 extern int __close_fd(struct files_struct *files, 116 unsigned int fd); 117 118 extern struct kmem_cache *files_cachep; 119 120 #endif /* __LINUX_FDTABLE_H */ 121