fs/file_table.c

/* */
This source file includes following definitions.
insert_file_free
remove_file_free
put_last_free
grow_files
file_table_init
get_empty_filp
   1 /*
   2  *  linux/fs/file_table.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <linux/fs.h>
   8 #include <linux/string.h>
   9 #include <linux/mm.h>
  10 
  11 struct file * first_file;
  12 int nr_files = 0;
  13 
  14 static void insert_file_free(struct file *file)
     /*  */
  15 {
  16         file->f_next = first_file;
  17         file->f_prev = first_file->f_prev;
  18         file->f_next->f_prev = file;
  19         file->f_prev->f_next = file;
  20         first_file = file;
  21 }
  22 
  23 static void remove_file_free(struct file *file)
     /*  */
  24 {
  25         if (first_file == file)
  26                 first_file = first_file->f_next;
  27         if (file->f_next)
  28                 file->f_next->f_prev = file->f_prev;
  29         if (file->f_prev)
  30                 file->f_prev->f_next = file->f_next;
  31         file->f_next = file->f_prev = NULL;
  32 }
  33 
  34 static void put_last_free(struct file *file)
     /*  */
  35 {
  36         remove_file_free(file);
  37         file->f_prev = first_file->f_prev;
  38         file->f_prev->f_next = file;
  39         file->f_next = first_file;
  40         file->f_next->f_prev = file;
  41 }
  42 
  43 void grow_files(void)
     /*  */
  44 {
  45         struct file * file;
  46         int i;
  47 
  48         file = (struct file *) get_free_page(GFP_KERNEL);
  49 
  50         if (!file)
  51                 return;
  52 
  53         nr_files+=i= PAGE_SIZE/sizeof(struct file);
  54 
  55         if (!first_file)
  56                 file->f_next = file->f_prev = first_file = file++, i--;
  57 
  58         for (; i ; i--)
  59                 insert_file_free(file++);
  60 }
  61 
  62 unsigned long file_table_init(unsigned long start, unsigned long end)
     /*  */
  63 {
  64         first_file = NULL;
  65         return start;
  66 }
  67 
  68 struct file * get_empty_filp(void)
     /*  */
  69 {
  70         int i;
  71         struct file * f;
  72 
  73         if (!first_file)
  74                 grow_files();
  75 repeat:
  76         for (f = first_file, i=0; i < nr_files; i++, f = f->f_next)
  77                 if (!f->f_count) {
  78                         remove_file_free(f);
  79                         memset(f,0,sizeof(*f));
  80                         put_last_free(f);
  81                         f->f_count = 1;
  82                         f->f_version = ++event;
  83                         return f;
  84                 }
  85         if (nr_files < NR_FILE) {
  86                 grow_files();
  87                 goto repeat;
  88         }
  89         return NULL;
  90 }
/* */
root/fs/file_table.c

DEFINITIONS
