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 <asm/uaccess.h>
  22 #include <asm/system.h>
  23
  24 #include "ncp_fs.h"
  25
  26 /*
  27  * Fill in the supplied page for mmap
  28  * XXX: how are we excluding truncate/invalidate here? Maybe need to lock
  29  * page?
  30  */
  31 static int ncp_file_mmap_fault(struct vm_area_struct *area,
  32                                         struct vm_fault *vmf)
  33 {
  34         struct file *file = area->vm_file;
  35         struct dentry *dentry = file->f_path.dentry;
  36         struct inode *inode = dentry->d_inode;
  37         char *pg_addr;
  38         unsigned int already_read;
  39         unsigned int count;
  40         int bufsize;
  41         int pos; /* XXX: loff_t ? */
  42
  43         /*
  44          * ncpfs has nothing against high pages as long
  45          * as recvmsg and memset works on it
  46          */
  47         vmf->page = alloc_page(GFP_HIGHUSER);
  48         if (!vmf->page)
  49                 return VM_FAULT_OOM;
  50         pg_addr = kmap(vmf->page);
  51         pos = vmf->pgoff << PAGE_SHIFT;
  52
  53         count = PAGE_SIZE;
  54         /* what we can read in one go */
  55         bufsize = NCP_SERVER(inode)->buffer_size;
  56
  57         already_read = 0;
  58         if (ncp_make_open(inode, O_RDONLY) >= 0) {
  59                 while (already_read < count) {
  60                         int read_this_time;
  61                         int to_read;
  62
  63                         to_read = bufsize - (pos % bufsize);
  64
  65                         to_read = min_t(unsigned int, to_read, count - already_read);
  66
  67                         if (ncp_read_kernel(NCP_SERVER(inode),
  68                                      NCP_FINFO(inode)->file_handle,
  69                                      pos, to_read,
  70                                      pg_addr + already_read,
  71                                      &read_this_time) != 0) {
  72                                 read_this_time = 0;
  73                         }
  74                         pos += read_this_time;
  75                         already_read += read_this_time;
  76
  77                         if (read_this_time < to_read) {
  78                                 break;
  79                         }
  80                 }
  81                 ncp_inode_close(inode);
  82
  83         }
  84
  85         if (already_read < PAGE_SIZE)
  86                 memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
  87         flush_dcache_page(vmf->page);
  88         kunmap(vmf->page);
  89
  90         /*
  91          * If I understand ncp_read_kernel() properly, the above always
  92          * fetches from the network, here the analogue of disk.
  93          * -- wli
  94          */
  95         count_vm_event(PGMAJFAULT);
  96         mem_cgroup_count_vm_event(area->vm_mm, PGMAJFAULT);
  97         return VM_FAULT_MAJOR;
  98 }
  99
 100 static const struct vm_operations_struct ncp_file_mmap =
 101 {
 102         .fault = ncp_file_mmap_fault,
 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_path.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 }