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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#include "fid.h"
43
44/**
45 * v9fs_fid_readpage - read an entire page in from 9P
46 *
47 * @fid: fid being read
48 * @page: structure to page
49 *
50 */
51static int v9fs_fid_readpage(struct p9_fid *fid, 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_debug(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_fid_readn(fid, 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_readpage - read an entire page in from 9P
91 *
92 * @filp: file being read
93 * @page: structure to page
94 *
95 */
96
97static int v9fs_vfs_readpage(struct file *filp, struct page *page)
98{
99 return v9fs_fid_readpage(filp->private_data, page);
100}
101
102/**
103 * v9fs_vfs_readpages - read a set of pages from 9P
104 *
105 * @filp: file being read
106 * @mapping: the address space
107 * @pages: list of pages to read
108 * @nr_pages: count of pages to read
109 *
110 */
111
112static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
113 struct list_head *pages, unsigned nr_pages)
114{
115 int ret = 0;
116 struct inode *inode;
117
118 inode = mapping->host;
119 p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
120
121 ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
122 if (ret == 0)
123 return ret;
124
125 ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
126 p9_debug(P9_DEBUG_VFS, " = %d\n", ret);
127 return ret;
128}
129
130/**
131 * v9fs_release_page - release the private state associated with a page
132 *
133 * Returns 1 if the page can be released, false otherwise.
134 */
135
136static int v9fs_release_page(struct page *page, gfp_t gfp)
137{
138 if (PagePrivate(page))
139 return 0;
140 return v9fs_fscache_release_page(page, gfp);
141}
142
143/**
144 * v9fs_invalidate_page - Invalidate a page completely or partially
145 *
146 * @page: structure to page
147 * @offset: offset in the page
148 */
149
150static void v9fs_invalidate_page(struct page *page, unsigned long offset)
151{
152 /*
153 * If called with zero offset, we should release
154 * the private state assocated with the page
155 */
156 if (offset == 0)
157 v9fs_fscache_invalidate_page(page);
158}
159
160static int v9fs_vfs_writepage_locked(struct page *page)
161{
162 char *buffer;
163 int retval, len;
164 loff_t offset, size;
165 mm_segment_t old_fs;
166 struct v9fs_inode *v9inode;
167 struct inode *inode = page->mapping->host;
168
169 v9inode = V9FS_I(inode);
170 size = i_size_read(inode);
171 if (page->index == size >> PAGE_CACHE_SHIFT)
172 len = size & ~PAGE_CACHE_MASK;
173 else
174 len = PAGE_CACHE_SIZE;
175
176 set_page_writeback(page);
177
178 buffer = kmap(page);
179 offset = page_offset(page);
180
181 old_fs = get_fs();
182 set_fs(get_ds());
183 /* We should have writeback_fid always set */
184 BUG_ON(!v9inode->writeback_fid);
185
186 retval = v9fs_file_write_internal(inode,
187 v9inode->writeback_fid,
188 (__force const char __user *)buffer,
189 len, &offset, 0);
190 if (retval > 0)
191 retval = 0;
192
193 set_fs(old_fs);
194 kunmap(page);
195 end_page_writeback(page);
196 return retval;
197}
198
199static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
200{
201 int retval;
202
203 retval = v9fs_vfs_writepage_locked(page);
204 if (retval < 0) {
205 if (retval == -EAGAIN) {
206 redirty_page_for_writepage(wbc, page);
207 retval = 0;
208 } else {
209 SetPageError(page);
210 mapping_set_error(page->mapping, retval);
211 }
212 } else
213 retval = 0;
214
215 unlock_page(page);
216 return retval;
217}
218
219/**
220 * v9fs_launder_page - Writeback a dirty page
221 * Returns 0 on success.
222 */
223
224static int v9fs_launder_page(struct page *page)
225{
226 int retval;
227 struct inode *inode = page->mapping->host;
228
229 v9fs_fscache_wait_on_page_write(inode, page);
230 if (clear_page_dirty_for_io(page)) {
231 retval = v9fs_vfs_writepage_locked(page);
232 if (retval)
233 return retval;
234 }
235 return 0;
236}
237
238/**
239 * v9fs_direct_IO - 9P address space operation for direct I/O
240 * @rw: direction (read or write)
241 * @iocb: target I/O control block
242 * @iov: array of vectors that define I/O buffer
243 * @pos: offset in file to begin the operation
244 * @nr_segs: size of iovec array
245 *
246 * The presence of v9fs_direct_IO() in the address space ops vector
247 * allowes open() O_DIRECT flags which would have failed otherwise.
248 *
249 * In the non-cached mode, we shunt off direct read and write requests before
250 * the VFS gets them, so this method should never be called.
251 *
252 * Direct IO is not 'yet' supported in the cached mode. Hence when
253 * this routine is called through generic_file_aio_read(), the read/write fails
254 * with an error.
255 *
256 */
257static ssize_t
258v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
259 loff_t pos, unsigned long nr_segs)
260{
261 /*
262 * FIXME
263 * Now that we do caching with cache mode enabled, We need
264 * to support direct IO
265 */
266 p9_debug(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) off/no(%lld/%lu) EINVAL\n",
267 iocb->ki_filp->f_path.dentry->d_name.name,
268 (long long)pos, nr_segs);
269
270 return -EINVAL;
271}
272
273static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
274 loff_t pos, unsigned len, unsigned flags,
275 struct page **pagep, void **fsdata)
276{
277 int retval = 0;
278 struct page *page;
279 struct v9fs_inode *v9inode;
280 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
281 struct inode *inode = mapping->host;
282
283 v9inode = V9FS_I(inode);
284start:
285 page = grab_cache_page_write_begin(mapping, index, flags);
286 if (!page) {
287 retval = -ENOMEM;
288 goto out;
289 }
290 BUG_ON(!v9inode->writeback_fid);
291 if (PageUptodate(page))
292 goto out;
293
294 if (len == PAGE_CACHE_SIZE)
295 goto out;
296
297 retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
298 page_cache_release(page);
299 if (!retval)
300 goto start;
301out:
302 *pagep = page;
303 return retval;
304}
305
306static int v9fs_write_end(struct file *filp, struct address_space *mapping,
307 loff_t pos, unsigned len, unsigned copied,
308 struct page *page, void *fsdata)
309{
310 loff_t last_pos = pos + copied;
311 struct inode *inode = page->mapping->host;
312
313 if (unlikely(copied < len)) {
314 /*
315 * zero out the rest of the area
316 */
317 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
318
319 zero_user(page, from + copied, len - copied);
320 flush_dcache_page(page);
321 }
322
323 if (!PageUptodate(page))
324 SetPageUptodate(page);
325 /*
326 * No need to use i_size_read() here, the i_size
327 * cannot change under us because we hold the i_mutex.
328 */
329 if (last_pos > inode->i_size) {
330 inode_add_bytes(inode, last_pos - inode->i_size);
331 i_size_write(inode, last_pos);
332 }
333 set_page_dirty(page);
334 unlock_page(page);
335 page_cache_release(page);
336
337 return copied;
338}
339
340
341const struct address_space_operations v9fs_addr_operations = {
342 .readpage = v9fs_vfs_readpage,
343 .readpages = v9fs_vfs_readpages,
344 .set_page_dirty = __set_page_dirty_nobuffers,
345 .writepage = v9fs_vfs_writepage,
346 .write_begin = v9fs_write_begin,
347 .write_end = v9fs_write_end,
348 .releasepage = v9fs_release_page,
349 .invalidatepage = v9fs_invalidate_page,
350 .launder_page = v9fs_launder_page,
351 .direct_IO = v9fs_direct_IO,
352};