include/linux/file.h

   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 extern void __fput(struct file *);
   9
  10 /*
  11  * Check whether the specified task has the fd open. Since the task
  12  * may not have a files_struct, we must test for p->files != NULL.
  13  */
  14 extern inline struct file * fcheck_task(struct task_struct *p, unsigned int fd)
  15 {
  16         struct file * file = NULL;
  17
  18         if (p->files && fd < p->files->max_fds)
  19                 file = p->files->fd[fd];
  20         return file;
  21 }
  22
  23 /*
  24  * Check whether the specified fd has an open file.
  25  */
  26 extern inline struct file * fcheck(unsigned int fd)
  27 {
  28         struct file * file = NULL;
  29         struct files_struct *files = current->files;
  30
  31         read_lock(&files->file_lock);
  32         if (fd < files->max_fds)
  33                 file = files->fd[fd];
  34         read_unlock(&files->file_lock);
  35         return file;
  36 }
  37
  38 extern inline struct file * fget(unsigned int fd)
  39 {
  40         struct file * file = NULL;
  41         struct files_struct *files = current->files;
  42
  43         read_lock(&files->file_lock);
  44         if (fd < files->max_fds) {
  45                 file = files->fd[fd];
  46                 if (file)
  47                         atomic_inc(&file->f_count);
  48         }
  49         read_unlock(&files->file_lock);
  50         return file;
  51 }
  52
  53 /*
  54  * Install a file pointer in the fd array.
  55  */
  56 extern inline void fd_install(unsigned int fd, struct file * file)
  57 {
  58         struct files_struct *files = current->files;
  59
  60         write_lock(&files->file_lock);
  61         files->fd[fd] = file;
  62         write_unlock(&files->file_lock);
  63 }
  64
  65 /*
  66  * 23/12/1998 Marcin Dalecki <dalecki@cs.net.pl>:
  67  *
  68  * Since those functions where calling other functions, it was compleatly
  69  * bogous to make them all "extern inline".
  70  *
  71  * The removal of this pseudo optimization saved me scandaleous:
  72  *
  73  *              3756 (i386 arch)
  74  *
  75  * precious bytes from my kernel, even without counting all the code compiled
  76  * as module!
  77  *
  78  * I suspect there are many other similar "optimizations" across the
  79  * kernel...
  80  */
  81 extern void fput(struct file *);
  82 extern void put_filp(struct file *);
  83
  84 #endif /* __LINUX_FILE_H */