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 unsigned long *full_fds_bits; 30 struct rcu_head rcu; 31 }; 32 33 static inline bool close_on_exec(int fd, const struct fdtable *fdt) 34 { 35 return test_bit(fd, fdt->close_on_exec); 36 } 37 38 static inline bool fd_is_open(int fd, const struct fdtable *fdt) 39 { 40 return test_bit(fd, fdt->open_fds); 41 } 42 43 /* 44 * Open file table structure 45 */ 46 struct files_struct { 47 /* 48 * read mostly part 49 */ 50 atomic_t count; 51 bool resize_in_progress; 52 wait_queue_head_t resize_wait; 53 54 struct fdtable __rcu *fdt; 55 struct fdtable fdtab; 56 /* 57 * written part on a separate cache line in SMP 58 */ 59 spinlock_t file_lock ____cacheline_aligned_in_smp; 60 int next_fd; 61 unsigned long close_on_exec_init[1]; 62 unsigned long open_fds_init[1]; 63 unsigned long full_fds_bits_init[1]; 64 struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 65 }; 66 67 struct file_operations; 68 struct vfsmount; 69 struct dentry; 70 71 #define rcu_dereference_check_fdtable(files, fdtfd) \ 72 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock)) 73 74 #define files_fdtable(files) \ 75 rcu_dereference_check_fdtable((files), (files)->fdt) 76 77 /* 78 * The caller must ensure that fd table isn't shared or hold rcu or file lock 79 */ 80 static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd) 81 { 82 struct fdtable *fdt = rcu_dereference_raw(files->fdt); 83 84 if (fd < fdt->max_fds) 85 return rcu_dereference_raw(fdt->fd[fd]); 86 return NULL; 87 } 88 89 static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd) 90 { 91 RCU_LOCKDEP_WARN(!rcu_read_lock_held() && 92 !lockdep_is_held(&files->file_lock), 93 "suspicious rcu_dereference_check() usage"); 94 return __fcheck_files(files, fd); 95 } 96 97 /* 98 * Check whether the specified fd has an open file. 99 */ 100 #define fcheck(fd) fcheck_files(current->files, fd) 101 102 struct task_struct; 103 104 struct files_struct *get_files_struct(struct task_struct *); 105 void put_files_struct(struct files_struct *fs); 106 void reset_files_struct(struct files_struct *); 107 int unshare_files(struct files_struct **); 108 struct files_struct *dup_fd(struct files_struct *, int *); 109 void do_close_on_exec(struct files_struct *); 110 int iterate_fd(struct files_struct *, unsigned, 111 int (*)(const void *, struct file *, unsigned), 112 const void *); 113 114 extern int __alloc_fd(struct files_struct *files, 115 unsigned start, unsigned end, unsigned flags); 116 extern void __fd_install(struct files_struct *files, 117 unsigned int fd, struct file *file); 118 extern int __close_fd(struct files_struct *files, 119 unsigned int fd); 120 121 extern struct kmem_cache *files_cachep; 122 123 #endif /* __LINUX_FDTABLE_H */ 124