LXR linux/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 * XXX: how are we excluding truncate/invalidate here? Maybe need to lock
  28 * page?
  29 */
  30static int ncp_file_mmap_fault(struct vm_area_struct *area,
  31                                        struct vm_fault *vmf)
  32{
  33        struct file *file = area->vm_file;
  34        struct dentry *dentry = file->f_path.dentry;
  35        struct inode *inode = dentry->d_inode;
  36        char *pg_addr;
  37        unsigned int already_read;
  38        unsigned int count;
  39        int bufsize;
  40        int pos; /* XXX: loff_t ? */
  41
  42        /*
  43         * ncpfs has nothing against high pages as long
  44         * as recvmsg and memset works on it
  45         */
  46        vmf->page = alloc_page(GFP_HIGHUSER);
  47        if (!vmf->page)
  48                return VM_FAULT_OOM;
  49        pg_addr = kmap(vmf->page);
  50        pos = vmf->pgoff << PAGE_SHIFT;
  51
  52        count = PAGE_SIZE;
  53        if ((unsigned long)vmf->virtual_address + PAGE_SIZE > area->vm_end) {
  54                WARN_ON(1); /* shouldn't happen? */
  55                count = area->vm_end - (unsigned long)vmf->virtual_address;
  56        }
  57        /* what we can read in one go */
  58        bufsize = NCP_SERVER(inode)->buffer_size;
  59
  60        already_read = 0;
  61        if (ncp_make_open(inode, O_RDONLY) >= 0) {
  62                while (already_read < count) {
  63                        int read_this_time;
  64                        int to_read;
  65
  66                        to_read = bufsize - (pos % bufsize);
  67
  68                        to_read = min_t(unsigned int, to_read, count - already_read);
  69
  70                        if (ncp_read_kernel(NCP_SERVER(inode),
  71                                     NCP_FINFO(inode)->file_handle,
  72                                     pos, to_read,
  73                                     pg_addr + already_read,
  74                                     &read_this_time) != 0) {
  75                                read_this_time = 0;
  76                        }
  77                        pos += read_this_time;
  78                        already_read += read_this_time;
  79
  80                        if (read_this_time < to_read) {
  81                                break;
  82                        }
  83                }
  84                ncp_inode_close(inode);
  85
  86        }
  87
  88        if (already_read < PAGE_SIZE)
  89                memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
  90        flush_dcache_page(vmf->page);
  91        kunmap(vmf->page);
  92
  93        /*
  94         * If I understand ncp_read_kernel() properly, the above always
  95         * fetches from the network, here the analogue of disk.
  96         * -- wli
  97         */
  98        count_vm_event(PGMAJFAULT);
  99        return VM_FAULT_MAJOR;
 100}
 101
 102static struct vm_operations_struct ncp_file_mmap =
 103{
 104        .fault = ncp_file_mmap_fault,
 105};
 106
 107
 108/* This is used for a general mmap of a ncp file */
 109int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 110{
 111        struct inode *inode = file->f_path.dentry->d_inode;
 112        
 113        DPRINTK("ncp_mmap: called\n");
 114
 115        if (!ncp_conn_valid(NCP_SERVER(inode)))
 116                return -EIO;
 117
 118        /* only PAGE_COW or read-only supported now */
 119        if (vma->vm_flags & VM_SHARED)
 120                return -EINVAL;
 121        /* we do not support files bigger than 4GB... We eventually 
 122           supports just 4GB... */
 123        if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff 
 124           > (1U << (32 - PAGE_SHIFT)))
 125                return -EFBIG;
 126
 127        vma->vm_ops = &ncp_file_mmap;
 128        file_accessed(file);
 129        return 0;
 130}
 131