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 struct fdtable { 30 unsigned int max_fds; 31 struct file ** fd; /* current fd array */ 32 fd_set *close_on_exec; 33 fd_set *open_fds; 34 struct rcu_head rcu; 35 struct fdtable *next; 36 }; 37 38 /* 39 * Open file table structure 40 */ 41 struct files_struct { 42 /* 43 * read mostly part 44 */ 45 atomic_t count; 46 struct fdtable *fdt; 47 struct fdtable fdtab; 48 /* 49 * written part on a separate cache line in SMP 50 */ 51 spinlock_t file_lock ____cacheline_aligned_in_smp; 52 int next_fd; 53 struct embedded_fd_set close_on_exec_init; 54 struct embedded_fd_set open_fds_init; 55 struct file * fd_array[NR_OPEN_DEFAULT]; 56 }; 57 58 #define files_fdtable(files) (rcu_dereference((files)->fdt)) 59 60 extern struct kmem_cache *filp_cachep; 61 62 extern void FASTCALL(__fput(struct file *)); 63 extern void FASTCALL(fput(struct file *)); 64 65 static inline void fput_light(struct file *file, int fput_needed) 66 { 67 if (unlikely(fput_needed)) 68 fput(file); 69 } 70 71 extern struct file * FASTCALL(fget(unsigned int fd)); 72 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed)); 73 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag)); 74 extern void put_filp(struct file *); 75 extern int get_unused_fd(void); 76 extern int get_unused_fd_flags(int flags); 77 extern void FASTCALL(put_unused_fd(unsigned int fd)); 78 struct kmem_cache; 79 80 extern int expand_files(struct files_struct *, int nr); 81 extern void free_fdtable_rcu(struct rcu_head *rcu); 82 extern void __init files_defer_init(void); 83 84 static inline void free_fdtable(struct fdtable *fdt) 85 { 86 call_rcu(&fdt->rcu, free_fdtable_rcu); 87 } 88 89 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 90 { 91 struct file * file = NULL; 92 struct fdtable *fdt = files_fdtable(files); 93 94 if (fd < fdt->max_fds) 95 file = rcu_dereference(fdt->fd[fd]); 96 return file; 97 } 98 99 /* 100 * Check whether the specified fd has an open file. 101 */ 102 #define fcheck(fd) fcheck_files(current->files, fd) 103 104 extern void FASTCALL(fd_install(unsigned int fd, struct file * file)); 105 106 struct task_struct; 107 108 struct files_struct *get_files_struct(struct task_struct *); 109 void FASTCALL(put_files_struct(struct files_struct *fs)); 110 void reset_files_struct(struct task_struct *, struct files_struct *); 111 112 extern struct kmem_cache *files_cachep; 113 114 #endif /* __LINUX_FILE_H */ 115