1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/fs/9p/vfs_addr.c
4 *
5 * This file contians vfs address (mmap) ops for 9P2000.
6 *
7 * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
8 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
9 */
10
11 #include <linux/module.h>
12 #include <linux/errno.h>
13 #include <linux/fs.h>
14 #include <linux/file.h>
15 #include <linux/stat.h>
16 #include <linux/string.h>
17 #include <linux/inet.h>
18 #include <linux/pagemap.h>
19 #include <linux/idr.h>
20 #include <linux/sched.h>
21 #include <linux/uio.h>
22 #include <linux/bvec.h>
23 #include <net/9p/9p.h>
24 #include <net/9p/client.h>
25
26 #include "v9fs.h"
27 #include "v9fs_vfs.h"
28 #include "cache.h"
29 #include "fid.h"
30
31 /**
32 * v9fs_fid_readpage - read an entire page in from 9P
33 *
34 * @fid: fid being read
35 * @page: structure to page
36 *
37 */
v9fs_fid_readpage(void * data,struct page * page)38 static int v9fs_fid_readpage(void *data, struct page *page)
39 {
40 struct p9_fid *fid = data;
41 struct inode *inode = page->mapping->host;
42 struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
43 struct iov_iter to;
44 int retval, err;
45
46 p9_debug(P9_DEBUG_VFS, "\n");
47
48 BUG_ON(!PageLocked(page));
49
50 retval = v9fs_readpage_from_fscache(inode, page);
51 if (retval == 0)
52 return retval;
53
54 iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE);
55
56 retval = p9_client_read(fid, page_offset(page), &to, &err);
57 if (err) {
58 v9fs_uncache_page(inode, page);
59 retval = err;
60 goto done;
61 }
62
63 zero_user(page, retval, PAGE_SIZE - retval);
64 flush_dcache_page(page);
65 SetPageUptodate(page);
66
67 v9fs_readpage_to_fscache(inode, page);
68 retval = 0;
69
70 done:
71 unlock_page(page);
72 return retval;
73 }
74
75 /**
76 * v9fs_vfs_readpage - read an entire page in from 9P
77 *
78 * @filp: file being read
79 * @page: structure to page
80 *
81 */
82
v9fs_vfs_readpage(struct file * filp,struct page * page)83 static int v9fs_vfs_readpage(struct file *filp, struct page *page)
84 {
85 return v9fs_fid_readpage(filp->private_data, page);
86 }
87
88 /**
89 * v9fs_vfs_readpages - read a set of pages from 9P
90 *
91 * @filp: file being read
92 * @mapping: the address space
93 * @pages: list of pages to read
94 * @nr_pages: count of pages to read
95 *
96 */
97
v9fs_vfs_readpages(struct file * filp,struct address_space * mapping,struct list_head * pages,unsigned nr_pages)98 static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
99 struct list_head *pages, unsigned nr_pages)
100 {
101 int ret = 0;
102 struct inode *inode;
103
104 inode = mapping->host;
105 p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
106
107 ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
108 if (ret == 0)
109 return ret;
110
111 ret = read_cache_pages(mapping, pages, v9fs_fid_readpage,
112 filp->private_data);
113 p9_debug(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
v9fs_release_page(struct page * page,gfp_t gfp)123 static int v9fs_release_page(struct page *page, gfp_t gfp)
124 {
125 if (PagePrivate(page))
126 return 0;
127 return v9fs_fscache_release_page(page, gfp);
128 }
129
130 /**
131 * v9fs_invalidate_page - Invalidate a page completely or partially
132 *
133 * @page: structure to page
134 * @offset: offset in the page
135 */
136
v9fs_invalidate_page(struct page * page,unsigned int offset,unsigned int length)137 static void v9fs_invalidate_page(struct page *page, unsigned int offset,
138 unsigned int length)
139 {
140 /*
141 * If called with zero offset, we should release
142 * the private state assocated with the page
143 */
144 if (offset == 0 && length == PAGE_SIZE)
145 v9fs_fscache_invalidate_page(page);
146 }
147
v9fs_vfs_writepage_locked(struct page * page)148 static int v9fs_vfs_writepage_locked(struct page *page)
149 {
150 struct inode *inode = page->mapping->host;
151 struct v9fs_inode *v9inode = V9FS_I(inode);
152 loff_t size = i_size_read(inode);
153 struct iov_iter from;
154 struct bio_vec bvec;
155 int err, len;
156
157 if (page->index == size >> PAGE_SHIFT)
158 len = size & ~PAGE_MASK;
159 else
160 len = PAGE_SIZE;
161
162 bvec.bv_page = page;
163 bvec.bv_offset = 0;
164 bvec.bv_len = len;
165 iov_iter_bvec(&from, WRITE, &bvec, 1, len);
166
167 /* We should have writeback_fid always set */
168 BUG_ON(!v9inode->writeback_fid);
169
170 set_page_writeback(page);
171
172 p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);
173
174 end_page_writeback(page);
175 return err;
176 }
177
v9fs_vfs_writepage(struct page * page,struct writeback_control * wbc)178 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
179 {
180 int retval;
181
182 p9_debug(P9_DEBUG_VFS, "page %p\n", page);
183
184 retval = v9fs_vfs_writepage_locked(page);
185 if (retval < 0) {
186 if (retval == -EAGAIN) {
187 redirty_page_for_writepage(wbc, page);
188 retval = 0;
189 } else {
190 SetPageError(page);
191 mapping_set_error(page->mapping, retval);
192 }
193 } else
194 retval = 0;
195
196 unlock_page(page);
197 return retval;
198 }
199
200 /**
201 * v9fs_launder_page - Writeback a dirty page
202 * Returns 0 on success.
203 */
204
v9fs_launder_page(struct page * page)205 static int v9fs_launder_page(struct page *page)
206 {
207 int retval;
208 struct inode *inode = page->mapping->host;
209
210 v9fs_fscache_wait_on_page_write(inode, page);
211 if (clear_page_dirty_for_io(page)) {
212 retval = v9fs_vfs_writepage_locked(page);
213 if (retval)
214 return retval;
215 }
216 return 0;
217 }
218
219 /**
220 * v9fs_direct_IO - 9P address space operation for direct I/O
221 * @iocb: target I/O control block
222 *
223 * The presence of v9fs_direct_IO() in the address space ops vector
224 * allowes open() O_DIRECT flags which would have failed otherwise.
225 *
226 * In the non-cached mode, we shunt off direct read and write requests before
227 * the VFS gets them, so this method should never be called.
228 *
229 * Direct IO is not 'yet' supported in the cached mode. Hence when
230 * this routine is called through generic_file_aio_read(), the read/write fails
231 * with an error.
232 *
233 */
234 static ssize_t
v9fs_direct_IO(struct kiocb * iocb,struct iov_iter * iter)235 v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
236 {
237 struct file *file = iocb->ki_filp;
238 loff_t pos = iocb->ki_pos;
239 ssize_t n;
240 int err = 0;
241 if (iov_iter_rw(iter) == WRITE) {
242 n = p9_client_write(file->private_data, pos, iter, &err);
243 if (n) {
244 struct inode *inode = file_inode(file);
245 loff_t i_size = i_size_read(inode);
246 if (pos + n > i_size)
247 inode_add_bytes(inode, pos + n - i_size);
248 }
249 } else {
250 n = p9_client_read(file->private_data, pos, iter, &err);
251 }
252 return n ? n : err;
253 }
254
v9fs_write_begin(struct file * filp,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)255 static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
256 loff_t pos, unsigned len, unsigned flags,
257 struct page **pagep, void **fsdata)
258 {
259 int retval = 0;
260 struct page *page;
261 struct v9fs_inode *v9inode;
262 pgoff_t index = pos >> PAGE_SHIFT;
263 struct inode *inode = mapping->host;
264
265
266 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
267
268 v9inode = V9FS_I(inode);
269 start:
270 page = grab_cache_page_write_begin(mapping, index, flags);
271 if (!page) {
272 retval = -ENOMEM;
273 goto out;
274 }
275 BUG_ON(!v9inode->writeback_fid);
276 if (PageUptodate(page))
277 goto out;
278
279 if (len == PAGE_SIZE)
280 goto out;
281
282 retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
283 put_page(page);
284 if (!retval)
285 goto start;
286 out:
287 *pagep = page;
288 return retval;
289 }
290
v9fs_write_end(struct file * filp,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)291 static int v9fs_write_end(struct file *filp, struct address_space *mapping,
292 loff_t pos, unsigned len, unsigned copied,
293 struct page *page, void *fsdata)
294 {
295 loff_t last_pos = pos + copied;
296 struct inode *inode = page->mapping->host;
297
298 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
299
300 if (!PageUptodate(page)) {
301 if (unlikely(copied < len)) {
302 copied = 0;
303 goto out;
304 } else if (len == PAGE_SIZE) {
305 SetPageUptodate(page);
306 }
307 }
308 /*
309 * No need to use i_size_read() here, the i_size
310 * cannot change under us because we hold the i_mutex.
311 */
312 if (last_pos > inode->i_size) {
313 inode_add_bytes(inode, last_pos - inode->i_size);
314 i_size_write(inode, last_pos);
315 }
316 set_page_dirty(page);
317 out:
318 unlock_page(page);
319 put_page(page);
320
321 return copied;
322 }
323
324
325 const struct address_space_operations v9fs_addr_operations = {
326 .readpage = v9fs_vfs_readpage,
327 .readpages = v9fs_vfs_readpages,
328 .set_page_dirty = __set_page_dirty_nobuffers,
329 .writepage = v9fs_vfs_writepage,
330 .write_begin = v9fs_write_begin,
331 .write_end = v9fs_write_end,
332 .releasepage = v9fs_release_page,
333 .invalidatepage = v9fs_invalidate_page,
334 .launder_page = v9fs_launder_page,
335 .direct_IO = v9fs_direct_IO,
336 };
337