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  */
  30 static 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         count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
  93         return VM_FAULT_MAJOR;
  94 }
  95
  96 static 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 */
 103 int 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 }