1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS filesystem file handling
3 *
4 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/fs.h>
12 #include <linux/pagemap.h>
13 #include <linux/writeback.h>
14 #include <linux/gfp.h>
15 #include <linux/task_io_accounting_ops.h>
16 #include <linux/mm.h>
17 #include "internal.h"
18
19 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
20 static int afs_readpage(struct file *file, struct page *page);
21 static void afs_invalidatepage(struct page *page, unsigned int offset,
22 unsigned int length);
23 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
24
25 static int afs_readpages(struct file *filp, struct address_space *mapping,
26 struct list_head *pages, unsigned nr_pages);
27
28 const struct file_operations afs_file_operations = {
29 .open = afs_open,
30 .release = afs_release,
31 .llseek = generic_file_llseek,
32 .read_iter = generic_file_read_iter,
33 .write_iter = afs_file_write,
34 .mmap = afs_file_mmap,
35 .splice_read = generic_file_splice_read,
36 .fsync = afs_fsync,
37 .lock = afs_lock,
38 .flock = afs_flock,
39 };
40
41 const struct inode_operations afs_file_inode_operations = {
42 .getattr = afs_getattr,
43 .setattr = afs_setattr,
44 .permission = afs_permission,
45 };
46
47 const struct address_space_operations afs_fs_aops = {
48 .readpage = afs_readpage,
49 .readpages = afs_readpages,
50 .set_page_dirty = afs_set_page_dirty,
51 .launder_page = afs_launder_page,
52 .releasepage = afs_releasepage,
53 .invalidatepage = afs_invalidatepage,
54 .write_begin = afs_write_begin,
55 .write_end = afs_write_end,
56 .writepage = afs_writepage,
57 .writepages = afs_writepages,
58 };
59
60 static const struct vm_operations_struct afs_vm_ops = {
61 .fault = filemap_fault,
62 .map_pages = filemap_map_pages,
63 .page_mkwrite = afs_page_mkwrite,
64 };
65
66 /*
67 * Discard a pin on a writeback key.
68 */
afs_put_wb_key(struct afs_wb_key * wbk)69 void afs_put_wb_key(struct afs_wb_key *wbk)
70 {
71 if (refcount_dec_and_test(&wbk->usage)) {
72 key_put(wbk->key);
73 kfree(wbk);
74 }
75 }
76
77 /*
78 * Cache key for writeback.
79 */
afs_cache_wb_key(struct afs_vnode * vnode,struct afs_file * af)80 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
81 {
82 struct afs_wb_key *wbk, *p;
83
84 wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
85 if (!wbk)
86 return -ENOMEM;
87 refcount_set(&wbk->usage, 2);
88 wbk->key = af->key;
89
90 spin_lock(&vnode->wb_lock);
91 list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
92 if (p->key == wbk->key)
93 goto found;
94 }
95
96 key_get(wbk->key);
97 list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
98 spin_unlock(&vnode->wb_lock);
99 af->wb = wbk;
100 return 0;
101
102 found:
103 refcount_inc(&p->usage);
104 spin_unlock(&vnode->wb_lock);
105 af->wb = p;
106 kfree(wbk);
107 return 0;
108 }
109
110 /*
111 * open an AFS file or directory and attach a key to it
112 */
afs_open(struct inode * inode,struct file * file)113 int afs_open(struct inode *inode, struct file *file)
114 {
115 struct afs_vnode *vnode = AFS_FS_I(inode);
116 struct afs_file *af;
117 struct key *key;
118 int ret;
119
120 _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
121
122 key = afs_request_key(vnode->volume->cell);
123 if (IS_ERR(key)) {
124 ret = PTR_ERR(key);
125 goto error;
126 }
127
128 af = kzalloc(sizeof(*af), GFP_KERNEL);
129 if (!af) {
130 ret = -ENOMEM;
131 goto error_key;
132 }
133 af->key = key;
134
135 ret = afs_validate(vnode, key);
136 if (ret < 0)
137 goto error_af;
138
139 if (file->f_mode & FMODE_WRITE) {
140 ret = afs_cache_wb_key(vnode, af);
141 if (ret < 0)
142 goto error_af;
143 }
144
145 if (file->f_flags & O_TRUNC)
146 set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
147
148 file->private_data = af;
149 _leave(" = 0");
150 return 0;
151
152 error_af:
153 kfree(af);
154 error_key:
155 key_put(key);
156 error:
157 _leave(" = %d", ret);
158 return ret;
159 }
160
161 /*
162 * release an AFS file or directory and discard its key
163 */
afs_release(struct inode * inode,struct file * file)164 int afs_release(struct inode *inode, struct file *file)
165 {
166 struct afs_vnode *vnode = AFS_FS_I(inode);
167 struct afs_file *af = file->private_data;
168 int ret = 0;
169
170 _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
171
172 if ((file->f_mode & FMODE_WRITE))
173 ret = vfs_fsync(file, 0);
174
175 file->private_data = NULL;
176 if (af->wb)
177 afs_put_wb_key(af->wb);
178 key_put(af->key);
179 kfree(af);
180 afs_prune_wb_keys(vnode);
181 _leave(" = %d", ret);
182 return ret;
183 }
184
185 /*
186 * Dispose of a ref to a read record.
187 */
afs_put_read(struct afs_read * req)188 void afs_put_read(struct afs_read *req)
189 {
190 int i;
191
192 if (refcount_dec_and_test(&req->usage)) {
193 if (req->pages) {
194 for (i = 0; i < req->nr_pages; i++)
195 if (req->pages[i])
196 put_page(req->pages[i]);
197 if (req->pages != req->array)
198 kfree(req->pages);
199 }
200 kfree(req);
201 }
202 }
203
204 #ifdef CONFIG_AFS_FSCACHE
205 /*
206 * deal with notification that a page was read from the cache
207 */
afs_file_readpage_read_complete(struct page * page,void * data,int error)208 static void afs_file_readpage_read_complete(struct page *page,
209 void *data,
210 int error)
211 {
212 _enter("%p,%p,%d", page, data, error);
213
214 /* if the read completes with an error, we just unlock the page and let
215 * the VM reissue the readpage */
216 if (!error)
217 SetPageUptodate(page);
218 unlock_page(page);
219 }
220 #endif
221
222 /*
223 * Fetch file data from the volume.
224 */
afs_fetch_data(struct afs_vnode * vnode,struct key * key,struct afs_read * desc)225 int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *desc)
226 {
227 struct afs_fs_cursor fc;
228 struct afs_status_cb *scb;
229 int ret;
230
231 _enter("%s{%llx:%llu.%u},%x,,,",
232 vnode->volume->name,
233 vnode->fid.vid,
234 vnode->fid.vnode,
235 vnode->fid.unique,
236 key_serial(key));
237
238 scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
239 if (!scb)
240 return -ENOMEM;
241
242 ret = -ERESTARTSYS;
243 if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
244 afs_dataversion_t data_version = vnode->status.data_version;
245
246 while (afs_select_fileserver(&fc)) {
247 fc.cb_break = afs_calc_vnode_cb_break(vnode);
248 afs_fs_fetch_data(&fc, scb, desc);
249 }
250
251 afs_check_for_remote_deletion(&fc, vnode);
252 afs_vnode_commit_status(&fc, vnode, fc.cb_break,
253 &data_version, scb);
254 ret = afs_end_vnode_operation(&fc);
255 }
256
257 if (ret == 0) {
258 afs_stat_v(vnode, n_fetches);
259 atomic_long_add(desc->actual_len,
260 &afs_v2net(vnode)->n_fetch_bytes);
261 }
262
263 kfree(scb);
264 _leave(" = %d", ret);
265 return ret;
266 }
267
268 /*
269 * read page from file, directory or symlink, given a key to use
270 */
afs_page_filler(void * data,struct page * page)271 int afs_page_filler(void *data, struct page *page)
272 {
273 struct inode *inode = page->mapping->host;
274 struct afs_vnode *vnode = AFS_FS_I(inode);
275 struct afs_read *req;
276 struct key *key = data;
277 int ret;
278
279 _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
280
281 BUG_ON(!PageLocked(page));
282
283 ret = -ESTALE;
284 if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
285 goto error;
286
287 /* is it cached? */
288 #ifdef CONFIG_AFS_FSCACHE
289 ret = fscache_read_or_alloc_page(vnode->cache,
290 page,
291 afs_file_readpage_read_complete,
292 NULL,
293 GFP_KERNEL);
294 #else
295 ret = -ENOBUFS;
296 #endif
297 switch (ret) {
298 /* read BIO submitted (page in cache) */
299 case 0:
300 break;
301
302 /* page not yet cached */
303 case -ENODATA:
304 _debug("cache said ENODATA");
305 goto go_on;
306
307 /* page will not be cached */
308 case -ENOBUFS:
309 _debug("cache said ENOBUFS");
310
311 /* fall through */
312 default:
313 go_on:
314 req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
315 if (!req)
316 goto enomem;
317
318 /* We request a full page. If the page is a partial one at the
319 * end of the file, the server will return a short read and the
320 * unmarshalling code will clear the unfilled space.
321 */
322 refcount_set(&req->usage, 1);
323 req->pos = (loff_t)page->index << PAGE_SHIFT;
324 req->len = PAGE_SIZE;
325 req->nr_pages = 1;
326 req->pages = req->array;
327 req->pages[0] = page;
328 get_page(page);
329
330 /* read the contents of the file from the server into the
331 * page */
332 ret = afs_fetch_data(vnode, key, req);
333 afs_put_read(req);
334
335 if (ret < 0) {
336 if (ret == -ENOENT) {
337 _debug("got NOENT from server"
338 " - marking file deleted and stale");
339 set_bit(AFS_VNODE_DELETED, &vnode->flags);
340 ret = -ESTALE;
341 }
342
343 #ifdef CONFIG_AFS_FSCACHE
344 fscache_uncache_page(vnode->cache, page);
345 #endif
346 BUG_ON(PageFsCache(page));
347
348 if (ret == -EINTR ||
349 ret == -ENOMEM ||
350 ret == -ERESTARTSYS ||
351 ret == -EAGAIN)
352 goto error;
353 goto io_error;
354 }
355
356 SetPageUptodate(page);
357
358 /* send the page to the cache */
359 #ifdef CONFIG_AFS_FSCACHE
360 if (PageFsCache(page) &&
361 fscache_write_page(vnode->cache, page, vnode->status.size,
362 GFP_KERNEL) != 0) {
363 fscache_uncache_page(vnode->cache, page);
364 BUG_ON(PageFsCache(page));
365 }
366 #endif
367 unlock_page(page);
368 }
369
370 _leave(" = 0");
371 return 0;
372
373 io_error:
374 SetPageError(page);
375 goto error;
376 enomem:
377 ret = -ENOMEM;
378 error:
379 unlock_page(page);
380 _leave(" = %d", ret);
381 return ret;
382 }
383
384 /*
385 * read page from file, directory or symlink, given a file to nominate the key
386 * to be used
387 */
afs_readpage(struct file * file,struct page * page)388 static int afs_readpage(struct file *file, struct page *page)
389 {
390 struct key *key;
391 int ret;
392
393 if (file) {
394 key = afs_file_key(file);
395 ASSERT(key != NULL);
396 ret = afs_page_filler(key, page);
397 } else {
398 struct inode *inode = page->mapping->host;
399 key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
400 if (IS_ERR(key)) {
401 ret = PTR_ERR(key);
402 } else {
403 ret = afs_page_filler(key, page);
404 key_put(key);
405 }
406 }
407 return ret;
408 }
409
410 /*
411 * Make pages available as they're filled.
412 */
afs_readpages_page_done(struct afs_read * req)413 static void afs_readpages_page_done(struct afs_read *req)
414 {
415 #ifdef CONFIG_AFS_FSCACHE
416 struct afs_vnode *vnode = req->vnode;
417 #endif
418 struct page *page = req->pages[req->index];
419
420 req->pages[req->index] = NULL;
421 SetPageUptodate(page);
422
423 /* send the page to the cache */
424 #ifdef CONFIG_AFS_FSCACHE
425 if (PageFsCache(page) &&
426 fscache_write_page(vnode->cache, page, vnode->status.size,
427 GFP_KERNEL) != 0) {
428 fscache_uncache_page(vnode->cache, page);
429 BUG_ON(PageFsCache(page));
430 }
431 #endif
432 unlock_page(page);
433 put_page(page);
434 }
435
436 /*
437 * Read a contiguous set of pages.
438 */
afs_readpages_one(struct file * file,struct address_space * mapping,struct list_head * pages)439 static int afs_readpages_one(struct file *file, struct address_space *mapping,
440 struct list_head *pages)
441 {
442 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
443 struct afs_read *req;
444 struct list_head *p;
445 struct page *first, *page;
446 struct key *key = afs_file_key(file);
447 pgoff_t index;
448 int ret, n, i;
449
450 /* Count the number of contiguous pages at the front of the list. Note
451 * that the list goes prev-wards rather than next-wards.
452 */
453 first = lru_to_page(pages);
454 index = first->index + 1;
455 n = 1;
456 for (p = first->lru.prev; p != pages; p = p->prev) {
457 page = list_entry(p, struct page, lru);
458 if (page->index != index)
459 break;
460 index++;
461 n++;
462 }
463
464 req = kzalloc(struct_size(req, array, n), GFP_NOFS);
465 if (!req)
466 return -ENOMEM;
467
468 refcount_set(&req->usage, 1);
469 req->vnode = vnode;
470 req->page_done = afs_readpages_page_done;
471 req->pos = first->index;
472 req->pos <<= PAGE_SHIFT;
473 req->pages = req->array;
474
475 /* Transfer the pages to the request. We add them in until one fails
476 * to add to the LRU and then we stop (as that'll make a hole in the
477 * contiguous run.
478 *
479 * Note that it's possible for the file size to change whilst we're
480 * doing this, but we rely on the server returning less than we asked
481 * for if the file shrank. We also rely on this to deal with a partial
482 * page at the end of the file.
483 */
484 do {
485 page = lru_to_page(pages);
486 list_del(&page->lru);
487 index = page->index;
488 if (add_to_page_cache_lru(page, mapping, index,
489 readahead_gfp_mask(mapping))) {
490 #ifdef CONFIG_AFS_FSCACHE
491 fscache_uncache_page(vnode->cache, page);
492 #endif
493 put_page(page);
494 break;
495 }
496
497 req->pages[req->nr_pages++] = page;
498 req->len += PAGE_SIZE;
499 } while (req->nr_pages < n);
500
501 if (req->nr_pages == 0) {
502 kfree(req);
503 return 0;
504 }
505
506 ret = afs_fetch_data(vnode, key, req);
507 if (ret < 0)
508 goto error;
509
510 task_io_account_read(PAGE_SIZE * req->nr_pages);
511 afs_put_read(req);
512 return 0;
513
514 error:
515 if (ret == -ENOENT) {
516 _debug("got NOENT from server"
517 " - marking file deleted and stale");
518 set_bit(AFS_VNODE_DELETED, &vnode->flags);
519 ret = -ESTALE;
520 }
521
522 for (i = 0; i < req->nr_pages; i++) {
523 page = req->pages[i];
524 if (page) {
525 #ifdef CONFIG_AFS_FSCACHE
526 fscache_uncache_page(vnode->cache, page);
527 #endif
528 SetPageError(page);
529 unlock_page(page);
530 }
531 }
532
533 afs_put_read(req);
534 return ret;
535 }
536
537 /*
538 * read a set of pages
539 */
afs_readpages(struct file * file,struct address_space * mapping,struct list_head * pages,unsigned nr_pages)540 static int afs_readpages(struct file *file, struct address_space *mapping,
541 struct list_head *pages, unsigned nr_pages)
542 {
543 struct key *key = afs_file_key(file);
544 struct afs_vnode *vnode;
545 int ret = 0;
546
547 _enter("{%d},{%lu},,%d",
548 key_serial(key), mapping->host->i_ino, nr_pages);
549
550 ASSERT(key != NULL);
551
552 vnode = AFS_FS_I(mapping->host);
553 if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
554 _leave(" = -ESTALE");
555 return -ESTALE;
556 }
557
558 /* attempt to read as many of the pages as possible */
559 #ifdef CONFIG_AFS_FSCACHE
560 ret = fscache_read_or_alloc_pages(vnode->cache,
561 mapping,
562 pages,
563 &nr_pages,
564 afs_file_readpage_read_complete,
565 NULL,
566 mapping_gfp_mask(mapping));
567 #else
568 ret = -ENOBUFS;
569 #endif
570
571 switch (ret) {
572 /* all pages are being read from the cache */
573 case 0:
574 BUG_ON(!list_empty(pages));
575 BUG_ON(nr_pages != 0);
576 _leave(" = 0 [reading all]");
577 return 0;
578
579 /* there were pages that couldn't be read from the cache */
580 case -ENODATA:
581 case -ENOBUFS:
582 break;
583
584 /* other error */
585 default:
586 _leave(" = %d", ret);
587 return ret;
588 }
589
590 while (!list_empty(pages)) {
591 ret = afs_readpages_one(file, mapping, pages);
592 if (ret < 0)
593 break;
594 }
595
596 _leave(" = %d [netting]", ret);
597 return ret;
598 }
599
600 /*
601 * invalidate part or all of a page
602 * - release a page and clean up its private data if offset is 0 (indicating
603 * the entire page)
604 */
afs_invalidatepage(struct page * page,unsigned int offset,unsigned int length)605 static void afs_invalidatepage(struct page *page, unsigned int offset,
606 unsigned int length)
607 {
608 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
609 unsigned long priv;
610
611 _enter("{%lu},%u,%u", page->index, offset, length);
612
613 BUG_ON(!PageLocked(page));
614
615 /* we clean up only if the entire page is being invalidated */
616 if (offset == 0 && length == PAGE_SIZE) {
617 #ifdef CONFIG_AFS_FSCACHE
618 if (PageFsCache(page)) {
619 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
620 fscache_wait_on_page_write(vnode->cache, page);
621 fscache_uncache_page(vnode->cache, page);
622 }
623 #endif
624
625 if (PagePrivate(page)) {
626 priv = page_private(page);
627 trace_afs_page_dirty(vnode, tracepoint_string("inval"),
628 page->index, priv);
629 set_page_private(page, 0);
630 ClearPagePrivate(page);
631 }
632 }
633
634 _leave("");
635 }
636
637 /*
638 * release a page and clean up its private state if it's not busy
639 * - return true if the page can now be released, false if not
640 */
afs_releasepage(struct page * page,gfp_t gfp_flags)641 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
642 {
643 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
644 unsigned long priv;
645
646 _enter("{{%llx:%llu}[%lu],%lx},%x",
647 vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
648 gfp_flags);
649
650 /* deny if page is being written to the cache and the caller hasn't
651 * elected to wait */
652 #ifdef CONFIG_AFS_FSCACHE
653 if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
654 _leave(" = F [cache busy]");
655 return 0;
656 }
657 #endif
658
659 if (PagePrivate(page)) {
660 priv = page_private(page);
661 trace_afs_page_dirty(vnode, tracepoint_string("rel"),
662 page->index, priv);
663 set_page_private(page, 0);
664 ClearPagePrivate(page);
665 }
666
667 /* indicate that the page can be released */
668 _leave(" = T");
669 return 1;
670 }
671
672 /*
673 * Handle setting up a memory mapping on an AFS file.
674 */
afs_file_mmap(struct file * file,struct vm_area_struct * vma)675 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
676 {
677 int ret;
678
679 ret = generic_file_mmap(file, vma);
680 if (ret == 0)
681 vma->vm_ops = &afs_vm_ops;
682 return ret;
683 }
684