1/*
2 *  linux/fs/9p/vfs_addr.c
3 *
4 * This file contians vfs address (mmap) ops for 9P2000.
5 *
6 *  Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
7 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
8 *
9 *  This program is free software; you can redistribute it and/or modify
10 *  it under the terms of the GNU General Public License version 2
11 *  as published by the Free Software Foundation.
12 *
13 *  This program is distributed in the hope that it will be useful,
14 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 *  GNU General Public License for more details.
17 *
18 *  You should have received a copy of the GNU General Public License
19 *  along with this program; if not, write to:
20 *  Free Software Foundation
21 *  51 Franklin Street, Fifth Floor
22 *  Boston, MA  02111-1301  USA
23 *
24 */
25
26#include <linux/module.h>
27#include <linux/errno.h>
28#include <linux/fs.h>
29#include <linux/file.h>
30#include <linux/stat.h>
31#include <linux/string.h>
32#include <linux/inet.h>
33#include <linux/pagemap.h>
34#include <linux/idr.h>
35#include <linux/sched.h>
36#include <net/9p/9p.h>
37#include <net/9p/client.h>
38
39#include "v9fs.h"
40#include "v9fs_vfs.h"
41#include "cache.h"
42
43/**
44 * v9fs_vfs_readpage - read an entire page in from 9P
45 *
46 * @filp: file being read
47 * @page: structure to page
48 *
49 */
50
51static int v9fs_vfs_readpage(struct file *filp, struct page *page)
52{
53	int retval;
54	loff_t offset;
55	char *buffer;
56	struct inode *inode;
57
58	inode = page->mapping->host;
59	P9_DPRINTK(P9_DEBUG_VFS, "\n");
60
61	BUG_ON(!PageLocked(page));
62
63	retval = v9fs_readpage_from_fscache(inode, page);
64	if (retval == 0)
65		return retval;
66
67	buffer = kmap(page);
68	offset = page_offset(page);
69
70	retval = v9fs_file_readn(filp, buffer, NULL, PAGE_CACHE_SIZE, offset);
71	if (retval < 0) {
72		v9fs_uncache_page(inode, page);
73		goto done;
74	}
75
76	memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
77	flush_dcache_page(page);
78	SetPageUptodate(page);
79
80	v9fs_readpage_to_fscache(inode, page);
81	retval = 0;
82
83done:
84	kunmap(page);
85	unlock_page(page);
86	return retval;
87}
88
89/**
90 * v9fs_vfs_readpages - read a set of pages from 9P
91 *
92 * @filp: file being read
93 * @mapping: the address space
94 * @pages: list of pages to read
95 * @nr_pages: count of pages to read
96 *
97 */
98
99static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
100			     struct list_head *pages, unsigned nr_pages)
101{
102	int ret = 0;
103	struct inode *inode;
104
105	inode = mapping->host;
106	P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
107
108	ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
109	if (ret == 0)
110		return ret;
111
112	ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
113	P9_DPRINTK(P9_DEBUG_VFS, "  = %d\n", ret);
114	return ret;
115}
116
117/**
118 * v9fs_release_page - release the private state associated with a page
119 *
120 * Returns 1 if the page can be released, false otherwise.
121 */
122
123static int v9fs_release_page(struct page *page, gfp_t gfp)
124{
125	if (PagePrivate(page))
126		return 0;
127
128	return v9fs_fscache_release_page(page, gfp);
129}
130
131/**
132 * v9fs_invalidate_page - Invalidate a page completely or partially
133 *
134 * @page: structure to page
135 * @offset: offset in the page
136 */
137
138static void v9fs_invalidate_page(struct page *page, unsigned long offset)
139{
140	if (offset == 0)
141		v9fs_fscache_invalidate_page(page);
142}
143
144/**
145 * v9fs_launder_page - Writeback a dirty page
146 * Since the writes go directly to the server, we simply return a 0
147 * here to indicate success.
148 *
149 * Returns 0 on success.
150 */
151
152static int v9fs_launder_page(struct page *page)
153{
154	return 0;
155}
156
157const struct address_space_operations v9fs_addr_operations = {
158      .readpage = v9fs_vfs_readpage,
159      .readpages = v9fs_vfs_readpages,
160      .releasepage = v9fs_release_page,
161      .invalidatepage = v9fs_invalidate_page,
162      .launder_page = v9fs_launder_page,
163};
164