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