fs/msdos/mmap.c

/* */
This source file includes following definitions.
msdos_file_mmap_nopage
msdos_mmap
   1 /*
   2  *      fs/msdos/mmap.c
   3  *
   4  *      Written by Jacques Gelinas (jacques@solucorp.qc.ca)
   5  *      Inspired by fs/nfs/mmap.c (Jon Tombs 15 Aug 1993)
   6  *
   7  *      msdos mmap handling
   8  */
   9 #ifdef MODULE
  10 #include <linux/module.h>
  11 #endif
  12 
  13 #include <linux/stat.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/shm.h>
  18 #include <linux/errno.h>
  19 #include <linux/mman.h>
  20 #include <linux/string.h>
  21 #include <linux/malloc.h>
  22 #include <asm/segment.h>
  23 #include <asm/system.h>
  24 #include <linux/msdos_fs.h>
  25 
  26 /*
  27  * Fill in the supplied page for mmap
  28  */
  29 static unsigned long msdos_file_mmap_nopage(
     /*  */
  30         struct vm_area_struct * area,
  31         unsigned long address,
  32         unsigned long page,
  33         int error_code)
  34 {
  35         struct inode * inode = area->vm_inode;
  36         unsigned int clear;
  37         int pos;
  38         long gap;       /* distance from eof to pos */
  39 
  40         address &= PAGE_MASK;
  41         pos = address - area->vm_start + area->vm_offset;
  42 
  43         clear = 0;
  44         gap = inode->i_size - pos;
  45         if (gap <= 0){
  46                 /* mmaping beyond end of file */
  47                 clear = PAGE_SIZE;
  48         }else{
  49                 int cur_read;
  50                 int need_read;
  51                 struct file filp;
  52                 if (gap < PAGE_SIZE){
  53                         clear = PAGE_SIZE - gap;
  54                 }
  55                 filp.f_reada = 0;
  56                 filp.f_pos = pos;
  57                 need_read = PAGE_SIZE - clear;
  58                 {
  59                         unsigned long cur_fs = get_fs();
  60                         set_fs (KERNEL_DS);
  61                         cur_read = msdos_file_read (inode,&filp,(char*)page
  62                                 ,need_read);
  63                         set_fs (cur_fs);
  64                 }
  65                 if (cur_read != need_read){
  66                         printk ("MSDOS: Error while reading an mmap file %d <> %d\n"
  67                                 ,cur_read,need_read);
  68                 }
  69         }
  70         if (clear > 0){
  71                 memset ((char*)page+PAGE_SIZE-clear,0,clear);
  72         }
  73         return page;
  74 }
  75 
  76 struct vm_operations_struct msdos_file_mmap = {
  77         NULL,                   /* open */
  78         NULL,                   /* close */
  79         NULL,                   /* unmap */
  80         NULL,                   /* protect */
  81         NULL,                   /* sync */
  82         NULL,                   /* advise */
  83         msdos_file_mmap_nopage, /* nopage */
  84         NULL,                   /* wppage */
  85         NULL,                   /* swapout */
  86         NULL,                   /* swapin */
  87 };
  88 
  89 /*
  90  * This is used for a general mmap of an msdos file
  91  * Returns 0 if ok, or a negative error code if not.
  92  */
  93 int msdos_mmap(struct inode * inode, struct file * file, struct vm_area_struct * vma)
     /*  */
  94 {
  95         if (vma->vm_flags & VM_SHARED)  /* only PAGE_COW or read-only supported now */
  96                 return -EINVAL;
  97         if (vma->vm_offset & (inode->i_sb->s_blocksize - 1))
  98                 return -EINVAL;
  99         if (!inode->i_sb || !S_ISREG(inode->i_mode))
 100                 return -EACCES;
 101         if (!IS_RDONLY(inode)) {
 102                 inode->i_atime = CURRENT_TIME;
 103                 inode->i_dirt = 1;
 104         }
 105 
 106         vma->vm_inode = inode;
 107         inode->i_count++;
 108         vma->vm_ops = &msdos_file_mmap;
 109         return 0;
 110 }
 111 
 112
/* */
root/fs/msdos/mmap.c

DEFINITIONS
