fs/ncpfs/mmap.c

   1 /*
   2  *  mmap.c
   3  *
   4  *  Copyright (C) 1995, 1996 by Volker Lendecke
   5  *  Modified 1997 Peter Waltenberg, Bill Hawes, David Woodhouse for 2.1 dcache
   6  *
   7  */
   8
   9 #include <linux/stat.h>
  10 #include <linux/sched.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mm.h>
  13 #include <linux/shm.h>
  14 #include <linux/errno.h>
  15 #include <linux/mman.h>
  16 #include <linux/string.h>
  17 #include <linux/malloc.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/ncp_fs.h>
  20
  21 #include "ncplib_kernel.h"
  22 #include <asm/uaccess.h>
  23 #include <asm/system.h>
  24
  25 static inline int min(int a, int b)
  26 {
  27         return a < b ? a : b;
  28 }
  29
  30 /*
  31  * Fill in the supplied page for mmap
  32  */
  33 static unsigned long ncp_file_mmap_nopage(struct vm_area_struct *area,
  34                                      unsigned long address, int no_share)
  35 {
  36         struct file *file = area->vm_file;
  37         struct dentry *dentry = file->f_dentry;
  38         struct inode *inode = dentry->d_inode;
  39         unsigned long page;
  40         unsigned int clear;
  41         unsigned long tmp;
  42         int bufsize;
  43         int pos;
  44         mm_segment_t fs;
  45
  46         page = __get_free_page(GFP_KERNEL);
  47         if (!page)
  48                 return page;
  49         address &= PAGE_MASK;
  50         pos = address - area->vm_start + area->vm_offset;
  51
  52         clear = 0;
  53         if (address + PAGE_SIZE > area->vm_end) {
  54                 clear = address + PAGE_SIZE - area->vm_end;
  55         }
  56         /* what we can read in one go */
  57         bufsize = NCP_SERVER(inode)->buffer_size;
  58
  59         fs = get_fs();
  60         set_fs(get_ds());
  61
  62         if (ncp_make_open(inode, O_RDONLY) < 0) {
  63                 clear = PAGE_SIZE;
  64         } else {
  65                 int already_read = 0;
  66                 int count = PAGE_SIZE - clear;
  67                 int to_read;
  68
  69                 while (already_read < count) {
  70                         int read_this_time;
  71
  72                         if ((pos % bufsize) != 0) {
  73                                 to_read = bufsize - (pos % bufsize);
  74                         } else {
  75                                 to_read = bufsize;
  76                         }
  77
  78                         to_read = min(to_read, count - already_read);
  79
  80                         if (ncp_read(NCP_SERVER(inode),
  81                                      NCP_FINFO(inode)->file_handle,
  82                                      pos, to_read,
  83                                      (char *) (page + already_read),
  84                                      &read_this_time) != 0) {
  85                                 read_this_time = 0;
  86                         }
  87                         pos += read_this_time;
  88                         already_read += read_this_time;
  89
  90                         if (read_this_time < to_read) {
  91                                 break;
  92                         }
  93                 }
  94
  95         }
  96
  97         set_fs(fs);
  98
  99         tmp = page + PAGE_SIZE;
 100         while (clear--) {
 101                 *(char *) --tmp = 0;
 102         }
 103         return page;
 104 }
 105
 106 struct vm_operations_struct ncp_file_mmap =
 107 {
 108         NULL,                   /* open */
 109         NULL,                   /* close */
 110         NULL,                   /* unmap */
 111         NULL,                   /* protect */
 112         NULL,                   /* sync */
 113         NULL,                   /* advise */
 114         ncp_file_mmap_nopage,   /* nopage */
 115         NULL,                   /* wppage */
 116         NULL,                   /* swapout */
 117         NULL,                   /* swapin */
 118 };
 119
 120
 121 /* This is used for a general mmap of a ncp file */
 122 int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 123 {
 124         struct inode *inode = file->f_dentry->d_inode;
 125
 126         DPRINTK(KERN_DEBUG "ncp_mmap: called\n");
 127
 128         if (!ncp_conn_valid(NCP_SERVER(inode))) {
 129                 return -EIO;
 130         }
 131         /* only PAGE_COW or read-only supported now */
 132         if (vma->vm_flags & VM_SHARED)
 133                 return -EINVAL;
 134         if (!inode->i_sb || !S_ISREG(inode->i_mode))
 135                 return -EACCES;
 136         if (!IS_RDONLY(inode)) {
 137                 inode->i_atime = CURRENT_TIME;
 138         }
 139
 140         vma->vm_ops = &ncp_file_mmap;
 141         return 0;
 142 }