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 <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 struct file_operations; 61 struct vfsmount; 62 struct dentry; 63 64 extern int expand_files(struct files_struct *, int nr); 65 extern void free_fdtable_rcu(struct rcu_head *rcu); 66 extern void __init files_defer_init(void); 67 68 static inline void free_fdtable(struct fdtable *fdt) 69 { 70 call_rcu(&fdt->rcu, free_fdtable_rcu); 71 } 72 73 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 74 { 75 struct file * file = NULL; 76 struct fdtable *fdt = files_fdtable(files); 77 78 if (fd < fdt->max_fds) 79 file = rcu_dereference(fdt->fd[fd]); 80 return file; 81 } 82 83 /* 84 * Check whether the specified fd has an open file. 85 */ 86 #define fcheck(fd) fcheck_files(current->files, fd) 87 88 struct task_struct; 89 90 struct files_struct *get_files_struct(struct task_struct *); 91 void put_files_struct(struct files_struct *fs); 92 void reset_files_struct(struct files_struct *); 93 int unshare_files(struct files_struct **); 94 struct files_struct *dup_fd(struct files_struct *, int *); 95 96 extern struct kmem_cache *files_cachep; 97 98 #endif /* __LINUX_FDTABLE_H */ 99