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/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/memcontrol.h>
  20
  21#include <linux/uaccess.h>
  22
  23#include "ncp_fs.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_fault *vmf)
  31{
  32        struct inode *inode = file_inode(vmf->vma->vm_file);
  33        char *pg_addr;
  34        unsigned int already_read;
  35        unsigned int count;
  36        int bufsize;
  37        int pos; /* XXX: loff_t ? */
  38
  39        /*
  40         * ncpfs has nothing against high pages as long
  41         * as recvmsg and memset works on it
  42         */
  43        vmf->page = alloc_page(GFP_HIGHUSER);
  44        if (!vmf->page)
  45                return VM_FAULT_OOM;
  46        pg_addr = kmap(vmf->page);
  47        pos = vmf->pgoff << PAGE_SHIFT;
  48
  49        count = PAGE_SIZE;
  50        /* what we can read in one go */
  51        bufsize = NCP_SERVER(inode)->buffer_size;
  52
  53        already_read = 0;
  54        if (ncp_make_open(inode, O_RDONLY) >= 0) {
  55                while (already_read < count) {
  56                        int read_this_time;
  57                        int to_read;
  58
  59                        to_read = bufsize - (pos % bufsize);
  60
  61                        to_read = min_t(unsigned int, to_read, count - already_read);
  62
  63                        if (ncp_read_kernel(NCP_SERVER(inode),
  64                                     NCP_FINFO(inode)->file_handle,
  65                                     pos, to_read,
  66                                     pg_addr + already_read,
  67                                     &read_this_time) != 0) {
  68                                read_this_time = 0;
  69                        }
  70                        pos += read_this_time;
  71                        already_read += read_this_time;
  72
  73                        if (read_this_time < to_read) {
  74                                break;
  75                        }
  76                }
  77                ncp_inode_close(inode);
  78
  79        }
  80
  81        if (already_read < PAGE_SIZE)
  82                memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
  83        flush_dcache_page(vmf->page);
  84        kunmap(vmf->page);
  85
  86        /*
  87         * If I understand ncp_read_kernel() properly, the above always
  88         * fetches from the network, here the analogue of disk.
  89         * -- nyc
  90         */
  91        count_vm_event(PGMAJFAULT);
  92        mem_cgroup_count_vm_event(vmf->vma->vm_mm, PGMAJFAULT);
  93        return VM_FAULT_MAJOR;
  94}
  95
  96static const struct vm_operations_struct ncp_file_mmap =
  97{
  98        .fault = ncp_file_mmap_fault,
  99};
 100
 101
 102/* This is used for a general mmap of a ncp file */
 103int ncp_mmap(struct file *file, struct vm_area_struct *vma)
 104{
 105        struct inode *inode = file_inode(file);
 106        
 107        ncp_dbg(1, "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        /* we do not support files bigger than 4GB... We eventually 
 116           supports just 4GB... */
 117        if (vma_pages(vma) + vma->vm_pgoff
 118           > (1U << (32 - PAGE_SHIFT)))
 119                return -EFBIG;
 120
 121        vma->vm_ops = &ncp_file_mmap;
 122        file_accessed(file);
 123        return 0;
 124}
 125