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 <linux/uio.h>
37 #include <net/9p/9p.h>
38 #include <net/9p/client.h>
39
40 #include "v9fs.h"
41 #include "v9fs_vfs.h"
42 #include "cache.h"
43 #include "fid.h"
44
45 /**
46 * v9fs_fid_readpage - read an entire page in from 9P
47 *
48 * @fid: fid being read
49 * @page: structure to page
50 *
51 */
v9fs_fid_readpage(void * data,struct page * page)52 static int v9fs_fid_readpage(void *data, struct page *page)
53 {
54 struct p9_fid *fid = data;
55 struct inode *inode = page->mapping->host;
56 struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
57 struct iov_iter to;
58 int retval, err;
59
60 p9_debug(P9_DEBUG_VFS, "\n");
61
62 BUG_ON(!PageLocked(page));
63
64 retval = v9fs_readpage_from_fscache(inode, page);
65 if (retval == 0)
66 return retval;
67
68 iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE);
69
70 retval = p9_client_read(fid, page_offset(page), &to, &err);
71 if (err) {
72 v9fs_uncache_page(inode, page);
73 retval = err;
74 goto done;
75 }
76
77 zero_user(page, retval, PAGE_SIZE - retval);
78 flush_dcache_page(page);
79 SetPageUptodate(page);
80
81 v9fs_readpage_to_fscache(inode, page);
82 retval = 0;
83
84 done:
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
v9fs_vfs_readpage(struct file * filp,struct page * page)97 static 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
v9fs_vfs_readpages(struct file * filp,struct address_space * mapping,struct list_head * pages,unsigned nr_pages)112 static 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, v9fs_fid_readpage,
126 filp->private_data);
127 p9_debug(P9_DEBUG_VFS, " = %d\n", ret);
128 return ret;
129 }
130
131 /**
132 * v9fs_release_page - release the private state associated with a page
133 *
134 * Returns 1 if the page can be released, false otherwise.
135 */
136
v9fs_release_page(struct page * page,gfp_t gfp)137 static int v9fs_release_page(struct page *page, gfp_t gfp)
138 {
139 if (PagePrivate(page))
140 return 0;
141 return v9fs_fscache_release_page(page, gfp);
142 }
143
144 /**
145 * v9fs_invalidate_page - Invalidate a page completely or partially
146 *
147 * @page: structure to page
148 * @offset: offset in the page
149 */
150
v9fs_invalidate_page(struct page * page,unsigned int offset,unsigned int length)151 static void v9fs_invalidate_page(struct page *page, unsigned int offset,
152 unsigned int length)
153 {
154 /*
155 * If called with zero offset, we should release
156 * the private state assocated with the page
157 */
158 if (offset == 0 && length == PAGE_CACHE_SIZE)
159 v9fs_fscache_invalidate_page(page);
160 }
161
v9fs_vfs_writepage_locked(struct page * page)162 static int v9fs_vfs_writepage_locked(struct page *page)
163 {
164 struct inode *inode = page->mapping->host;
165 struct v9fs_inode *v9inode = V9FS_I(inode);
166 loff_t size = i_size_read(inode);
167 struct iov_iter from;
168 struct bio_vec bvec;
169 int err, len;
170
171 if (page->index == size >> PAGE_CACHE_SHIFT)
172 len = size & ~PAGE_CACHE_MASK;
173 else
174 len = PAGE_CACHE_SIZE;
175
176 bvec.bv_page = page;
177 bvec.bv_offset = 0;
178 bvec.bv_len = len;
179 iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len);
180
181 /* We should have writeback_fid always set */
182 BUG_ON(!v9inode->writeback_fid);
183
184 set_page_writeback(page);
185
186 p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);
187
188 end_page_writeback(page);
189 return err;
190 }
191
v9fs_vfs_writepage(struct page * page,struct writeback_control * wbc)192 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
193 {
194 int retval;
195
196 p9_debug(P9_DEBUG_VFS, "page %p\n", page);
197
198 retval = v9fs_vfs_writepage_locked(page);
199 if (retval < 0) {
200 if (retval == -EAGAIN) {
201 redirty_page_for_writepage(wbc, page);
202 retval = 0;
203 } else {
204 SetPageError(page);
205 mapping_set_error(page->mapping, retval);
206 }
207 } else
208 retval = 0;
209
210 unlock_page(page);
211 return retval;
212 }
213
214 /**
215 * v9fs_launder_page - Writeback a dirty page
216 * Returns 0 on success.
217 */
218
v9fs_launder_page(struct page * page)219 static int v9fs_launder_page(struct page *page)
220 {
221 int retval;
222 struct inode *inode = page->mapping->host;
223
224 v9fs_fscache_wait_on_page_write(inode, page);
225 if (clear_page_dirty_for_io(page)) {
226 retval = v9fs_vfs_writepage_locked(page);
227 if (retval)
228 return retval;
229 }
230 return 0;
231 }
232
233 /**
234 * v9fs_direct_IO - 9P address space operation for direct I/O
235 * @iocb: target I/O control block
236 * @pos: offset in file to begin the operation
237 *
238 * The presence of v9fs_direct_IO() in the address space ops vector
239 * allowes open() O_DIRECT flags which would have failed otherwise.
240 *
241 * In the non-cached mode, we shunt off direct read and write requests before
242 * the VFS gets them, so this method should never be called.
243 *
244 * Direct IO is not 'yet' supported in the cached mode. Hence when
245 * this routine is called through generic_file_aio_read(), the read/write fails
246 * with an error.
247 *
248 */
249 static ssize_t
v9fs_direct_IO(struct kiocb * iocb,struct iov_iter * iter,loff_t pos)250 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t pos)
251 {
252 struct file *file = iocb->ki_filp;
253 ssize_t n;
254 int err = 0;
255 if (iov_iter_rw(iter) == WRITE) {
256 n = p9_client_write(file->private_data, pos, iter, &err);
257 if (n) {
258 struct inode *inode = file_inode(file);
259 loff_t i_size = i_size_read(inode);
260 if (pos + n > i_size)
261 inode_add_bytes(inode, pos + n - i_size);
262 }
263 } else {
264 n = p9_client_read(file->private_data, pos, iter, &err);
265 }
266 return n ? n : err;
267 }
268
v9fs_write_begin(struct file * filp,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)269 static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
270 loff_t pos, unsigned len, unsigned flags,
271 struct page **pagep, void **fsdata)
272 {
273 int retval = 0;
274 struct page *page;
275 struct v9fs_inode *v9inode;
276 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
277 struct inode *inode = mapping->host;
278
279
280 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
281
282 v9inode = V9FS_I(inode);
283 start:
284 page = grab_cache_page_write_begin(mapping, index, flags);
285 if (!page) {
286 retval = -ENOMEM;
287 goto out;
288 }
289 BUG_ON(!v9inode->writeback_fid);
290 if (PageUptodate(page))
291 goto out;
292
293 if (len == PAGE_CACHE_SIZE)
294 goto out;
295
296 retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
297 page_cache_release(page);
298 if (!retval)
299 goto start;
300 out:
301 *pagep = page;
302 return retval;
303 }
304
v9fs_write_end(struct file * filp,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)305 static int v9fs_write_end(struct file *filp, struct address_space *mapping,
306 loff_t pos, unsigned len, unsigned copied,
307 struct page *page, void *fsdata)
308 {
309 loff_t last_pos = pos + copied;
310 struct inode *inode = page->mapping->host;
311
312 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
313
314 if (unlikely(copied < len)) {
315 /*
316 * zero out the rest of the area
317 */
318 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
319
320 zero_user(page, from + copied, len - copied);
321 flush_dcache_page(page);
322 }
323
324 if (!PageUptodate(page))
325 SetPageUptodate(page);
326 /*
327 * No need to use i_size_read() here, the i_size
328 * cannot change under us because we hold the i_mutex.
329 */
330 if (last_pos > inode->i_size) {
331 inode_add_bytes(inode, last_pos - inode->i_size);
332 i_size_write(inode, last_pos);
333 }
334 set_page_dirty(page);
335 unlock_page(page);
336 page_cache_release(page);
337
338 return copied;
339 }
340
341
342 const struct address_space_operations v9fs_addr_operations = {
343 .readpage = v9fs_vfs_readpage,
344 .readpages = v9fs_vfs_readpages,
345 .set_page_dirty = __set_page_dirty_nobuffers,
346 .writepage = v9fs_vfs_writepage,
347 .write_begin = v9fs_write_begin,
348 .write_end = v9fs_write_end,
349 .releasepage = v9fs_release_page,
350 .invalidatepage = v9fs_invalidate_page,
351 .launder_page = v9fs_launder_page,
352 .direct_IO = v9fs_direct_IO,
353 };
354