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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This file contians vfs address (mmap) ops for 9P2000.
4 *
5 * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
6 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
7 */
8
9#include <linux/module.h>
10#include <linux/errno.h>
11#include <linux/fs.h>
12#include <linux/file.h>
13#include <linux/stat.h>
14#include <linux/string.h>
15#include <linux/inet.h>
16#include <linux/pagemap.h>
17#include <linux/sched.h>
18#include <linux/swap.h>
19#include <linux/uio.h>
20#include <linux/netfs.h>
21#include <net/9p/9p.h>
22#include <net/9p/client.h>
23
24#include "v9fs.h"
25#include "v9fs_vfs.h"
26#include "cache.h"
27#include "fid.h"
28
29/**
30 * v9fs_issue_read - Issue a read from 9P
31 * @subreq: The read to make
32 */
33static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
34{
35 struct netfs_io_request *rreq = subreq->rreq;
36 struct p9_fid *fid = rreq->netfs_priv;
37 struct iov_iter to;
38 loff_t pos = subreq->start + subreq->transferred;
39 size_t len = subreq->len - subreq->transferred;
40 int total, err;
41
42 iov_iter_xarray(&to, ITER_DEST, &rreq->mapping->i_pages, pos, len);
43
44 total = p9_client_read(fid, pos, &to, &err);
45
46 /* if we just extended the file size, any portion not in
47 * cache won't be on server and is zeroes */
48 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
49
50 netfs_subreq_terminated(subreq, err ?: total, false);
51}
52
53/**
54 * v9fs_init_request - Initialise a read request
55 * @rreq: The read request
56 * @file: The file being read from
57 */
58static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
59{
60 struct inode *inode = file_inode(file);
61 struct v9fs_inode *v9inode = V9FS_I(inode);
62 struct p9_fid *fid = file->private_data;
63
64 BUG_ON(!fid);
65
66 /* we might need to read from a fid that was opened write-only
67 * for read-modify-write of page cache, use the writeback fid
68 * for that */
69 if (rreq->origin == NETFS_READ_FOR_WRITE &&
70 (fid->mode & O_ACCMODE) == O_WRONLY) {
71 fid = v9inode->writeback_fid;
72 BUG_ON(!fid);
73 }
74
75 p9_fid_get(fid);
76 rreq->netfs_priv = fid;
77 return 0;
78}
79
80/**
81 * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq
82 * @rreq: The I/O request to clean up
83 */
84static void v9fs_free_request(struct netfs_io_request *rreq)
85{
86 struct p9_fid *fid = rreq->netfs_priv;
87
88 p9_fid_put(fid);
89}
90
91/**
92 * v9fs_begin_cache_operation - Begin a cache operation for a read
93 * @rreq: The read request
94 */
95static int v9fs_begin_cache_operation(struct netfs_io_request *rreq)
96{
97#ifdef CONFIG_9P_FSCACHE
98 struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode));
99
100 return fscache_begin_read_operation(&rreq->cache_resources, cookie);
101#else
102 return -ENOBUFS;
103#endif
104}
105
106const struct netfs_request_ops v9fs_req_ops = {
107 .init_request = v9fs_init_request,
108 .free_request = v9fs_free_request,
109 .begin_cache_operation = v9fs_begin_cache_operation,
110 .issue_read = v9fs_issue_read,
111};
112
113/**
114 * v9fs_release_folio - release the private state associated with a folio
115 * @folio: The folio to be released
116 * @gfp: The caller's allocation restrictions
117 *
118 * Returns true if the page can be released, false otherwise.
119 */
120
121static bool v9fs_release_folio(struct folio *folio, gfp_t gfp)
122{
123 struct inode *inode = folio_inode(folio);
124
125 if (folio_test_private(folio))
126 return false;
127#ifdef CONFIG_9P_FSCACHE
128 if (folio_test_fscache(folio)) {
129 if (current_is_kswapd() || !(gfp & __GFP_FS))
130 return false;
131 folio_wait_fscache(folio);
132 }
133#endif
134 fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode)));
135 return true;
136}
137
138static void v9fs_invalidate_folio(struct folio *folio, size_t offset,
139 size_t length)
140{
141 folio_wait_fscache(folio);
142}
143
144static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
145 bool was_async)
146{
147 struct v9fs_inode *v9inode = priv;
148 __le32 version;
149
150 if (IS_ERR_VALUE(transferred_or_error) &&
151 transferred_or_error != -ENOBUFS) {
152 version = cpu_to_le32(v9inode->qid.version);
153 fscache_invalidate(v9fs_inode_cookie(v9inode), &version,
154 i_size_read(&v9inode->netfs.inode), 0);
155 }
156}
157
158static int v9fs_vfs_write_folio_locked(struct folio *folio)
159{
160 struct inode *inode = folio_inode(folio);
161 struct v9fs_inode *v9inode = V9FS_I(inode);
162 struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode);
163 loff_t start = folio_pos(folio);
164 loff_t i_size = i_size_read(inode);
165 struct iov_iter from;
166 size_t len = folio_size(folio);
167 int err;
168
169 if (start >= i_size)
170 return 0; /* Simultaneous truncation occurred */
171
172 len = min_t(loff_t, i_size - start, len);
173
174 iov_iter_xarray(&from, ITER_SOURCE, &folio_mapping(folio)->i_pages, start, len);
175
176 /* We should have writeback_fid always set */
177 BUG_ON(!v9inode->writeback_fid);
178
179 folio_wait_fscache(folio);
180 folio_start_writeback(folio);
181
182 p9_client_write(v9inode->writeback_fid, start, &from, &err);
183
184 if (err == 0 &&
185 fscache_cookie_enabled(cookie) &&
186 test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) {
187 folio_start_fscache(folio);
188 fscache_write_to_cache(v9fs_inode_cookie(v9inode),
189 folio_mapping(folio), start, len, i_size,
190 v9fs_write_to_cache_done, v9inode,
191 true);
192 }
193
194 folio_end_writeback(folio);
195 return err;
196}
197
198static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
199{
200 struct folio *folio = page_folio(page);
201 int retval;
202
203 p9_debug(P9_DEBUG_VFS, "folio %p\n", folio);
204
205 retval = v9fs_vfs_write_folio_locked(folio);
206 if (retval < 0) {
207 if (retval == -EAGAIN) {
208 folio_redirty_for_writepage(wbc, folio);
209 retval = 0;
210 } else {
211 mapping_set_error(folio_mapping(folio), retval);
212 }
213 } else
214 retval = 0;
215
216 folio_unlock(folio);
217 return retval;
218}
219
220static int v9fs_launder_folio(struct folio *folio)
221{
222 int retval;
223
224 if (folio_clear_dirty_for_io(folio)) {
225 retval = v9fs_vfs_write_folio_locked(folio);
226 if (retval)
227 return retval;
228 }
229 folio_wait_fscache(folio);
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 * @iter: The data/buffer to use
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 */
249static ssize_t
250v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
251{
252 struct file *file = iocb->ki_filp;
253 loff_t pos = iocb->ki_pos;
254 ssize_t n;
255 int err = 0;
256
257 if (iov_iter_rw(iter) == WRITE) {
258 n = p9_client_write(file->private_data, pos, iter, &err);
259 if (n) {
260 struct inode *inode = file_inode(file);
261 loff_t i_size = i_size_read(inode);
262
263 if (pos + n > i_size)
264 inode_add_bytes(inode, pos + n - i_size);
265 }
266 } else {
267 n = p9_client_read(file->private_data, pos, iter, &err);
268 }
269 return n ? n : err;
270}
271
272static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
273 loff_t pos, unsigned int len,
274 struct page **subpagep, void **fsdata)
275{
276 int retval;
277 struct folio *folio;
278 struct v9fs_inode *v9inode = V9FS_I(mapping->host);
279
280 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
281
282 BUG_ON(!v9inode->writeback_fid);
283
284 /* Prefetch area to be written into the cache if we're caching this
285 * file. We need to do this before we get a lock on the page in case
286 * there's more than one writer competing for the same cache block.
287 */
288 retval = netfs_write_begin(&v9inode->netfs, filp, mapping, pos, len, &folio, fsdata);
289 if (retval < 0)
290 return retval;
291
292 *subpagep = &folio->page;
293 return retval;
294}
295
296static int v9fs_write_end(struct file *filp, struct address_space *mapping,
297 loff_t pos, unsigned int len, unsigned int copied,
298 struct page *subpage, void *fsdata)
299{
300 loff_t last_pos = pos + copied;
301 struct folio *folio = page_folio(subpage);
302 struct inode *inode = mapping->host;
303 struct v9fs_inode *v9inode = V9FS_I(inode);
304
305 p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
306
307 if (!folio_test_uptodate(folio)) {
308 if (unlikely(copied < len)) {
309 copied = 0;
310 goto out;
311 }
312
313 folio_mark_uptodate(folio);
314 }
315
316 /*
317 * No need to use i_size_read() here, the i_size
318 * cannot change under us because we hold the i_mutex.
319 */
320 if (last_pos > inode->i_size) {
321 inode_add_bytes(inode, last_pos - inode->i_size);
322 i_size_write(inode, last_pos);
323 fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos);
324 }
325 folio_mark_dirty(folio);
326out:
327 folio_unlock(folio);
328 folio_put(folio);
329
330 return copied;
331}
332
333#ifdef CONFIG_9P_FSCACHE
334/*
335 * Mark a page as having been made dirty and thus needing writeback. We also
336 * need to pin the cache object to write back to.
337 */
338static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio)
339{
340 struct v9fs_inode *v9inode = V9FS_I(mapping->host);
341
342 return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode));
343}
344#else
345#define v9fs_dirty_folio filemap_dirty_folio
346#endif
347
348const struct address_space_operations v9fs_addr_operations = {
349 .read_folio = netfs_read_folio,
350 .readahead = netfs_readahead,
351 .dirty_folio = v9fs_dirty_folio,
352 .writepage = v9fs_vfs_writepage,
353 .write_begin = v9fs_write_begin,
354 .write_end = v9fs_write_end,
355 .release_folio = v9fs_release_folio,
356 .invalidate_folio = v9fs_invalidate_folio,
357 .launder_folio = v9fs_launder_folio,
358 .direct_IO = v9fs_direct_IO,
359};
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_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_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_DPRINTK(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_DPRINTK(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_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
267 "off/no(%lld/%lu) EINVAL\n",
268 iocb->ki_filp->f_path.dentry->d_name.name,
269 (long long) pos, nr_segs);
270
271 return -EINVAL;
272}
273
274static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
275 loff_t pos, unsigned len, unsigned flags,
276 struct page **pagep, void **fsdata)
277{
278 int retval = 0;
279 struct page *page;
280 struct v9fs_inode *v9inode;
281 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
282 struct inode *inode = mapping->host;
283
284 v9inode = V9FS_I(inode);
285start:
286 page = grab_cache_page_write_begin(mapping, index, flags);
287 if (!page) {
288 retval = -ENOMEM;
289 goto out;
290 }
291 BUG_ON(!v9inode->writeback_fid);
292 if (PageUptodate(page))
293 goto out;
294
295 if (len == PAGE_CACHE_SIZE)
296 goto out;
297
298 retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
299 page_cache_release(page);
300 if (!retval)
301 goto start;
302out:
303 *pagep = page;
304 return retval;
305}
306
307static int v9fs_write_end(struct file *filp, struct address_space *mapping,
308 loff_t pos, unsigned len, unsigned copied,
309 struct page *page, void *fsdata)
310{
311 loff_t last_pos = pos + copied;
312 struct inode *inode = page->mapping->host;
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
342const 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};