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/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/slab.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 /*
  26  * Fill in the supplied page for mmap
  27  */
  28 static struct page* ncp_file_mmap_nopage(struct vm_area_struct *area,
  29                                      unsigned long address, int *type)
  30 {
  31         struct file *file = area->vm_file;
  32         struct dentry *dentry = file->f_dentry;
  33         struct inode *inode = dentry->d_inode;
  34         struct page* page;
  35         char *pg_addr;
  36         unsigned int already_read;
  37         unsigned int count;
  38         int bufsize;
  39         int pos;
  40
  41         page = alloc_page(GFP_HIGHUSER); /* ncpfs has nothing against high pages
  42                    as long as recvmsg and memset works on it */
  43         if (!page)
  44                 return page;
  45         pg_addr = kmap(page);
  46         address &= PAGE_MASK;
  47         pos = address - area->vm_start + (area->vm_pgoff << PAGE_SHIFT);
  48
  49         count = PAGE_SIZE;
  50         if (address + PAGE_SIZE > area->vm_end) {
  51                 count = area->vm_end - address;
  52         }
  53         /* what we can read in one go */
  54         bufsize = NCP_SERVER(inode)->buffer_size;
  55
  56         already_read = 0;
  57         if (ncp_make_open(inode, O_RDONLY) >= 0) {
  58                 while (already_read < count) {
  59                         int read_this_time;
  60                         int to_read;
  61
  62                         to_read = bufsize - (pos % bufsize);
  63
  64                         to_read = min_t(unsigned int, to_read, count - already_read);
  65
  66                         if (ncp_read_kernel(NCP_SERVER(inode),
  67                                      NCP_FINFO(inode)->file_handle,
  68                                      pos, to_read,
  69                                      pg_addr + already_read,
  70                                      &read_this_time) != 0) {
  71                                 read_this_time = 0;
  72                         }
  73                         pos += read_this_time;
  74                         already_read += read_this_time;
  75
  76                         if (read_this_time < to_read) {
  77                                 break;
  78                         }
  79                 }
  80                 ncp_inode_close(inode);
  81
  82         }
  83
  84         if (already_read < PAGE_SIZE)
  85                 memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
  86         flush_dcache_page(page);
  87         kunmap(page);
  88
  89         /*
  90          * If I understand ncp_read_kernel() properly, the above always
  91          * fetches from the network, here the analogue of disk.
  92          * -- wli
  93          */
  94         if (type)
  95                 *type = VM_FAULT_MAJOR;
  96         count_vm_event(PGMAJFAULT);
  97         return page;
  98 }
  99
 100 static struct vm_operations_struct ncp_file_mmap =
 101 {
 102         .nopage = ncp_file_mmap_nopage,
 103 };
 104
 105
 106 /* This is used for a general mmap of a ncp file */
 107 int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 108 {
 109         struct inode *inode = file->f_dentry->d_inode;
 110
 111         DPRINTK("ncp_mmap: called\n");
 112
 113         if (!ncp_conn_valid(NCP_SERVER(inode)))
 114                 return -EIO;
 115
 116         /* only PAGE_COW or read-only supported now */
 117         if (vma->vm_flags & VM_SHARED)
 118                 return -EINVAL;
 119         /* we do not support files bigger than 4GB... We eventually
 120            supports just 4GB... */
 121         if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff
 122            > (1U << (32 - PAGE_SHIFT)))
 123                 return -EFBIG;
 124
 125         vma->vm_ops = &ncp_file_mmap;
 126         file_accessed(file);
 127         return 0;
 128 }