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 struct page* ncp_file_mmap_nopage(struct vm_area_struct *area,
  34                                      unsigned long address, int write_access)
  35 {
  36         struct file *file = area->vm_file;
  37         struct dentry *dentry = file->f_dentry;
  38         struct inode *inode = dentry->d_inode;
  39         struct page* page;
  40         unsigned long pg_addr;
  41         unsigned int already_read;
  42         unsigned int count;
  43         int bufsize;
  44         int pos;
  45
  46         page = alloc_page(GFP_HIGHMEM); /* ncpfs has nothing against GFP_HIGHMEM
  47                    as long as recvmsg and memset works on it */
  48         if (!page)
  49                 return page;
  50         pg_addr = kmap(page);
  51         address &= PAGE_MASK;
  52         pos = address - area->vm_start + (area->vm_pgoff << PAGE_SHIFT);
  53
  54         count = PAGE_SIZE;
  55         if (address + PAGE_SIZE > area->vm_end) {
  56                 count = area->vm_end - address;
  57         }
  58         /* what we can read in one go */
  59         bufsize = NCP_SERVER(inode)->buffer_size;
  60
  61         already_read = 0;
  62         if (ncp_make_open(inode, O_RDONLY) >= 0) {
  63                 while (already_read < count) {
  64                         int read_this_time;
  65                         int to_read;
  66
  67                         to_read = bufsize - (pos % bufsize);
  68
  69                         to_read = min(to_read, count - already_read);
  70
  71                         if (ncp_read_kernel(NCP_SERVER(inode),
  72                                      NCP_FINFO(inode)->file_handle,
  73                                      pos, to_read,
  74                                      (char *) (pg_addr + already_read),
  75                                      &read_this_time) != 0) {
  76                                 read_this_time = 0;
  77                         }
  78                         pos += read_this_time;
  79                         already_read += read_this_time;
  80
  81                         if (read_this_time < to_read) {
  82                                 break;
  83                         }
  84                 }
  85                 ncp_inode_close(inode);
  86
  87         }
  88
  89         if (already_read < PAGE_SIZE)
  90                 memset((char*)(pg_addr + already_read), 0,
  91                        PAGE_SIZE - already_read);
  92         kunmap(page);
  93         return page;
  94 }
  95
  96 static struct vm_operations_struct ncp_file_mmap =
  97 {
  98         nopage: ncp_file_mmap_nopage,
  99 };
 100
 101
 102 /* This is used for a general mmap of a ncp file */
 103 int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 104 {
 105         struct inode *inode = file->f_dentry->d_inode;
 106
 107         DPRINTK("ncp_mmap: called\n");
 108
 109         if (!ncp_conn_valid(NCP_SERVER(inode))) {
 110                 return -EIO;
 111         }
 112         /* only PAGE_COW or read-only supported now */
 113         if (vma->vm_flags & VM_SHARED)
 114                 return -EINVAL;
 115         if (!inode->i_sb || !S_ISREG(inode->i_mode))
 116                 return -EACCES;
 117         /* we do not support files bigger than 4GB... We eventually
 118            supports just 4GB... */
 119         if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff
 120            > (1U << (32 - PAGE_SHIFT)))
 121                 return -EFBIG;
 122         if (!IS_RDONLY(inode)) {
 123                 inode->i_atime = CURRENT_TIME;
 124         }
 125
 126         vma->vm_ops = &ncp_file_mmap;
 127         return 0;
 128 }