release/src-rt-6.x.4708/linux/linux-2.6.36/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/time.h>
  11 #include <linux/kernel.h>
  12 #include <linux/gfp.h>
  13 #include <linux/mm.h>
  14 #include <linux/shm.h>
  15 #include <linux/errno.h>
  16 #include <linux/mman.h>
  17 #include <linux/string.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 int ncp_file_mmap_fault(struct vm_area_struct *area,
  26                                         struct vm_fault *vmf)
  27 {
  28         struct file *file = area->vm_file;
  29         struct dentry *dentry = file->f_path.dentry;
  30         struct inode *inode = dentry->d_inode;
  31         char *pg_addr;
  32         unsigned int already_read;
  33         unsigned int count;
  34         int bufsize;
  35         int pos;
  36
  37         /*
  38          * ncpfs has nothing against high pages as long
  39          * as recvmsg and memset works on it
  40          */
  41         vmf->page = alloc_page(GFP_HIGHUSER);
  42         if (!vmf->page)
  43                 return VM_FAULT_OOM;
  44         pg_addr = kmap(vmf->page);
  45         pos = vmf->pgoff << PAGE_SHIFT;
  46
  47         count = PAGE_SIZE;
  48         /* what we can read in one go */
  49         bufsize = NCP_SERVER(inode)->buffer_size;
  50
  51         already_read = 0;
  52         if (ncp_make_open(inode, O_RDONLY) >= 0) {
  53                 while (already_read < count) {
  54                         int read_this_time;
  55                         int to_read;
  56
  57                         to_read = bufsize - (pos % bufsize);
  58
  59                         to_read = min_t(unsigned int, to_read, count - already_read);
  60
  61                         if (ncp_read_kernel(NCP_SERVER(inode),
  62                                      NCP_FINFO(inode)->file_handle,
  63                                      pos, to_read,
  64                                      pg_addr + already_read,
  65                                      &read_this_time) != 0) {
  66                                 read_this_time = 0;
  67                         }
  68                         pos += read_this_time;
  69                         already_read += read_this_time;
  70
  71                         if (read_this_time < to_read) {
  72                                 break;
  73                         }
  74                 }
  75                 ncp_inode_close(inode);
  76
  77         }
  78
  79         if (already_read < PAGE_SIZE)
  80                 memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
  81         flush_dcache_page(vmf->page);
  82         kunmap(vmf->page);
  83
  84         /*
  85          * If I understand ncp_read_kernel() properly, the above always
  86          * fetches from the network, here the analogue of disk.
  87          * -- wli
  88          */
  89         count_vm_event(PGMAJFAULT);
  90         return VM_FAULT_MAJOR;
  91 }
  92
  93 static const struct vm_operations_struct ncp_file_mmap =
  94 {
  95         .fault = ncp_file_mmap_fault,
  96 };
  97
  98
  99 /* This is used for a general mmap of a ncp file */
 100 int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 101 {
 102         struct inode *inode = file->f_path.dentry->d_inode;
 103
 104         DPRINTK("ncp_mmap: called\n");
 105
 106         if (!ncp_conn_valid(NCP_SERVER(inode)))
 107                 return -EIO;
 108
 109         /* only PAGE_COW or read-only supported now */
 110         if (vma->vm_flags & VM_SHARED)
 111                 return -EINVAL;
 112         /* we do not support files bigger than 4GB... We eventually
 113            supports just 4GB... */
 114         if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff
 115            > (1U << (32 - PAGE_SHIFT)))
 116                 return -EFBIG;
 117
 118         vma->vm_ops = &ncp_file_mmap;
 119         file_accessed(file);
 120         return 0;
 121 }