SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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_fault(struct vm_area_struct *area,
  29                                                 struct fault_data *fdata)
  30 {
  31         struct file *file = area->vm_file;
  32         struct dentry *dentry = file->f_path.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                 fdata->type = VM_FAULT_OOM;
  45                 return NULL;
  46         }
  47         pg_addr = kmap(page);
  48         pos = fdata->pgoff << PAGE_SHIFT;
  49
  50         count = PAGE_SIZE;
  51         if (fdata->address + PAGE_SIZE > area->vm_end) {
  52                 WARN_ON(1); /* shouldn't happen? */
  53                 count = area->vm_end - fdata->address;
  54         }
  55         /* what we can read in one go */
  56         bufsize = NCP_SERVER(inode)->buffer_size;
  57
  58         already_read = 0;
  59         if (ncp_make_open(inode, O_RDONLY) >= 0) {
  60                 while (already_read < count) {
  61                         int read_this_time;
  62                         int to_read;
  63
  64                         to_read = bufsize - (pos % bufsize);
  65
  66                         to_read = min_t(unsigned int, to_read, count - already_read);
  67
  68                         if (ncp_read_kernel(NCP_SERVER(inode),
  69                                      NCP_FINFO(inode)->file_handle,
  70                                      pos, to_read,
  71                                      pg_addr + already_read,
  72                                      &read_this_time) != 0) {
  73                                 read_this_time = 0;
  74                         }
  75                         pos += read_this_time;
  76                         already_read += read_this_time;
  77
  78                         if (read_this_time < to_read) {
  79                                 break;
  80                         }
  81                 }
  82                 ncp_inode_close(inode);
  83
  84         }
  85
  86         if (already_read < PAGE_SIZE)
  87                 memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
  88         flush_dcache_page(page);
  89         kunmap(page);
  90
  91         /*
  92          * If I understand ncp_read_kernel() properly, the above always
  93          * fetches from the network, here the analogue of disk.
  94          * -- wli
  95          */
  96         fdata->type = VM_FAULT_MAJOR;
  97         count_vm_event(PGMAJFAULT);
  98         return page;
  99 }
 100
 101 static struct vm_operations_struct ncp_file_mmap =
 102 {
 103         .fault = ncp_file_mmap_fault,
 104 };
 105
 106
 107 /* This is used for a general mmap of a ncp file */
 108 int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 109 {
 110         struct inode *inode = file->f_path.dentry->d_inode;
 111
 112         DPRINTK("ncp_mmap: called\n");
 113
 114         if (!ncp_conn_valid(NCP_SERVER(inode)))
 115                 return -EIO;
 116
 117         /* only PAGE_COW or read-only supported now */
 118         if (vma->vm_flags & VM_SHARED)
 119                 return -EINVAL;
 120         /* we do not support files bigger than 4GB... We eventually
 121            supports just 4GB... */
 122         if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff
 123            > (1U << (32 - PAGE_SHIFT)))
 124                 return -EFBIG;
 125
 126         vma->vm_ops = &ncp_file_mmap;
 127         vma->vm_flags |= VM_CAN_INVALIDATE;
 128         file_accessed(file);
 129         return 0;
 130 }