File: /usr/src/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/sched.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_nopage(struct vm_area_struct *area,
29     				     unsigned long address, int write_access)
30     {
31     	struct file *file = area->vm_file;
32     	struct dentry *dentry = file->f_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     		return page;
45     	pg_addr = kmap(page);
46     	address &= PAGE_MASK;
47     	pos = address - area->vm_start + (area->vm_pgoff << PAGE_SHIFT);
48     
49     	count = PAGE_SIZE;
50     	if (address + PAGE_SIZE > area->vm_end) {
51     		count = area->vm_end - address;
52     	}
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(page);
87     	kunmap(page);
88     	return page;
89     }
90     
91     static struct vm_operations_struct ncp_file_mmap =
92     {
93     	nopage:	ncp_file_mmap_nopage,
94     };
95     
96     
97     /* This is used for a general mmap of a ncp file */
98     int ncp_mmap(struct file *file, struct vm_area_struct *vma)
99     {
100     	struct inode *inode = file->f_dentry->d_inode;
101     	
102     	DPRINTK("ncp_mmap: called\n");
103     
104     	if (!ncp_conn_valid(NCP_SERVER(inode))) {
105     		return -EIO;
106     	}
107     	/* only PAGE_COW or read-only supported now */
108     	if (vma->vm_flags & VM_SHARED)
109     		return -EINVAL;
110     	if (!inode->i_sb || !S_ISREG(inode->i_mode))
111     		return -EACCES;
112     	/* we do not support files bigger than 4GB... We eventually 
113     	   supports just 4GB... */
114     	if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff 
115     	   > (1U << (32 - PAGE_SHIFT)))
116     		return -EFBIG;
117     	if (!IS_RDONLY(inode)) {
118     		inode->i_atime = CURRENT_TIME;
119     	}
120     
121     	vma->vm_ops = &ncp_file_mmap;
122     	return 0;
123     }
124