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 #define rcu_dereference_check_fdtable(files, fdtfd) \ 67 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock)) 68 69 #define files_fdtable(files) \ 70 rcu_dereference_check_fdtable((files), (files)->fdt) 71 72 /* 73 * The caller must ensure that fd table isn't shared or hold rcu or file lock 74 */ 75 static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd) 76 { 77 struct fdtable *fdt = rcu_dereference_raw(files->fdt); 78 79 if (fd < fdt->max_fds) 80 return rcu_dereference_raw(fdt->fd[fd]); 81 return NULL; 82 } 83 84 static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd) 85 { 86 rcu_lockdep_assert(rcu_read_lock_held() || 87 lockdep_is_held(&files->file_lock), 88 "suspicious rcu_dereference_check() usage"); 89 return __fcheck_files(files, fd); 90 } 91 92 /* 93 * Check whether the specified fd has an open file. 94 */ 95 #define fcheck(fd) fcheck_files(current->files, fd) 96 97 struct task_struct; 98 99 struct files_struct *get_files_struct(struct task_struct *); 100 void put_files_struct(struct files_struct *fs); 101 void reset_files_struct(struct files_struct *); 102 int unshare_files(struct files_struct **); 103 struct files_struct *dup_fd(struct files_struct *, int *); 104 void do_close_on_exec(struct files_struct *); 105 int iterate_fd(struct files_struct *, unsigned, 106 int (*)(const void *, struct file *, unsigned), 107 const void *); 108 109 extern int __alloc_fd(struct files_struct *files, 110 unsigned start, unsigned end, unsigned flags); 111 extern void __fd_install(struct files_struct *files, 112 unsigned int fd, struct file *file); 113 extern int __close_fd(struct files_struct *files, 114 unsigned int fd); 115 116 extern struct kmem_cache *files_cachep; 117 118 #endif /* __LINUX_FDTABLE_H */ 119