1 /* 2 * Wrapper functions for accessing the file_struct fd array. 3 */ 4 5 #ifndef __LINUX_FILE_H 6 #define __LINUX_FILE_H 7 8 #include <asm/atomic.h> 9 #include <linux/posix_types.h> 10 #include <linux/compiler.h> 11 #include <linux/spinlock.h> 12 #include <linux/rcupdate.h> 13 #include <linux/types.h> 14 15 /* 16 * The default fd array needs to be at least BITS_PER_LONG, 17 * as this is the granularity returned by copy_fdset(). 18 */ 19 #define NR_OPEN_DEFAULT BITS_PER_LONG 20 21 /* 22 * The embedded_fd_set is a small fd_set, 23 * suitable for most tasks (which open <= BITS_PER_LONG files) 24 */ 25 struct embedded_fd_set { 26 unsigned long fds_bits[1]; 27 }; 28 29 /* 30 * More than this number of fds: we use a separately allocated fd_set 31 */ 32 #define EMBEDDED_FD_SET_SIZE (BITS_PER_BYTE * sizeof(struct embedded_fd_set)) 33 34 struct fdtable { 35 unsigned int max_fds; 36 int max_fdset; 37 struct file ** fd; /* current fd array */ 38 fd_set *close_on_exec; 39 fd_set *open_fds; 40 struct rcu_head rcu; 41 struct files_struct *free_files; 42 struct fdtable *next; 43 }; 44 45 /* 46 * Open file table structure 47 */ 48 struct files_struct { 49 /* 50 * read mostly part 51 */ 52 atomic_t count; 53 struct fdtable *fdt; 54 struct fdtable fdtab; 55 /* 56 * written part on a separate cache line in SMP 57 */ 58 spinlock_t file_lock ____cacheline_aligned_in_smp; 59 int next_fd; 60 struct embedded_fd_set close_on_exec_init; 61 struct embedded_fd_set open_fds_init; 62 struct file * fd_array[NR_OPEN_DEFAULT]; 63 }; 64 65 #define files_fdtable(files) (rcu_dereference((files)->fdt)) 66 67 extern struct kmem_cache *filp_cachep; 68 69 extern void FASTCALL(__fput(struct file *)); 70 extern void FASTCALL(fput(struct file *)); 71 72 static inline void fput_light(struct file *file, int fput_needed) 73 { 74 if (unlikely(fput_needed)) 75 fput(file); 76 } 77 78 extern struct file * FASTCALL(fget(unsigned int fd)); 79 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed)); 80 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag)); 81 extern void put_filp(struct file *); 82 extern int get_unused_fd(void); 83 extern void FASTCALL(put_unused_fd(unsigned int fd)); 84 struct kmem_cache; 85 86 extern struct file ** alloc_fd_array(int); 87 extern void free_fd_array(struct file **, int); 88 89 extern fd_set *alloc_fdset(int); 90 extern void free_fdset(fd_set *, int); 91 92 extern int expand_files(struct files_struct *, int nr); 93 extern void free_fdtable(struct fdtable *fdt); 94 extern void __init files_defer_init(void); 95 96 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 97 { 98 struct file * file = NULL; 99 struct fdtable *fdt = files_fdtable(files); 100 101 if (fd < fdt->max_fds) 102 file = rcu_dereference(fdt->fd[fd]); 103 return file; 104 } 105 106 /* 107 * Check whether the specified fd has an open file. 108 */ 109 #define fcheck(fd) fcheck_files(current->files, fd) 110 111 extern void FASTCALL(fd_install(unsigned int fd, struct file * file)); 112 113 struct task_struct; 114 115 struct files_struct *get_files_struct(struct task_struct *); 116 void FASTCALL(put_files_struct(struct files_struct *fs)); 117 void reset_files_struct(struct task_struct *, struct files_struct *); 118 119 extern struct kmem_cache *files_cachep; 120 121 #endif /* __LINUX_FILE_H */ 122