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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// 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 */
38static 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
70done:
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
83static 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
98static 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
123static 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
137static 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
148static 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
178static 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
205static 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 */
234static ssize_t
235v9fs_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
255static 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);
269start:
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;
286out:
287 *pagep = page;
288 return retval;
289}
290
291static 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);
317out:
318 unlock_page(page);
319 put_page(page);
320
321 return copied;
322}
323
324
325const 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};