1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* handling of writes to regular files and writing back to the server
  3 *
  4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  5 * Written by David Howells (dhowells@redhat.com)
  6 */
  7
  8#include <linux/backing-dev.h>
  9#include <linux/slab.h>
 10#include <linux/fs.h>
 11#include <linux/pagemap.h>
 12#include <linux/writeback.h>
 13#include <linux/pagevec.h>
 14#include <linux/netfs.h>
 15#include <linux/fscache.h>
 16#include "internal.h"
 17
 18/*
 19 * mark a page as having been made dirty and thus needing writeback
 20 */
 21int afs_set_page_dirty(struct page *page)
 22{
 23	_enter("");
 24	return __set_page_dirty_nobuffers(page);
 25}
 26
 27/*
 28 * prepare to perform part of a write to a page
 29 */
 30int afs_write_begin(struct file *file, struct address_space *mapping,
 31		    loff_t pos, unsigned len, unsigned flags,
 32		    struct page **_page, void **fsdata)
 33{
 34	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 35	struct page *page;
 36	unsigned long priv;
 37	unsigned f, from;
 38	unsigned t, to;
 39	pgoff_t index;
 40	int ret;
 41
 42	_enter("{%llx:%llu},%llx,%x",
 43	       vnode->fid.vid, vnode->fid.vnode, pos, len);
 44
 45	/* Prefetch area to be written into the cache if we're caching this
 46	 * file.  We need to do this before we get a lock on the page in case
 47	 * there's more than one writer competing for the same cache block.
 48	 */
 49	ret = netfs_write_begin(file, mapping, pos, len, flags, &page, fsdata,
 50				&afs_req_ops, NULL);
 51	if (ret < 0)
 52		return ret;
 53
 54	index = page->index;
 55	from = pos - index * PAGE_SIZE;
 56	to = from + len;
 57
 58try_again:
 59	/* See if this page is already partially written in a way that we can
 60	 * merge the new write with.
 61	 */
 62	if (PagePrivate(page)) {
 63		priv = page_private(page);
 64		f = afs_page_dirty_from(page, priv);
 65		t = afs_page_dirty_to(page, priv);
 66		ASSERTCMP(f, <=, t);
 67
 68		if (PageWriteback(page)) {
 69			trace_afs_page_dirty(vnode, tracepoint_string("alrdy"), page);
 70			goto flush_conflicting_write;
 71		}
 72		/* If the file is being filled locally, allow inter-write
 73		 * spaces to be merged into writes.  If it's not, only write
 74		 * back what the user gives us.
 75		 */
 76		if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
 77		    (to < f || from > t))
 78			goto flush_conflicting_write;
 79	}
 80
 81	*_page = page;
 82	_leave(" = 0");
 83	return 0;
 84
 85	/* The previous write and this write aren't adjacent or overlapping, so
 86	 * flush the page out.
 87	 */
 88flush_conflicting_write:
 89	_debug("flush conflict");
 90	ret = write_one_page(page);
 91	if (ret < 0)
 92		goto error;
 93
 94	ret = lock_page_killable(page);
 95	if (ret < 0)
 96		goto error;
 97	goto try_again;
 98
 99error:
100	put_page(page);
101	_leave(" = %d", ret);
102	return ret;
103}
104
105/*
106 * finalise part of a write to a page
107 */
108int afs_write_end(struct file *file, struct address_space *mapping,
109		  loff_t pos, unsigned len, unsigned copied,
110		  struct page *page, void *fsdata)
111{
112	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
113	unsigned long priv;
114	unsigned int f, from = pos & (thp_size(page) - 1);
115	unsigned int t, to = from + copied;
116	loff_t i_size, maybe_i_size;
117
118	_enter("{%llx:%llu},{%lx}",
119	       vnode->fid.vid, vnode->fid.vnode, page->index);
120
121	if (!PageUptodate(page)) {
122		if (copied < len) {
123			copied = 0;
124			goto out;
125		}
126
127		SetPageUptodate(page);
128	}
129
130	if (copied == 0)
131		goto out;
132
133	maybe_i_size = pos + copied;
134
135	i_size = i_size_read(&vnode->vfs_inode);
136	if (maybe_i_size > i_size) {
137		write_seqlock(&vnode->cb_lock);
138		i_size = i_size_read(&vnode->vfs_inode);
139		if (maybe_i_size > i_size)
140			afs_set_i_size(vnode, maybe_i_size);
141		write_sequnlock(&vnode->cb_lock);
142	}
143
144	if (PagePrivate(page)) {
145		priv = page_private(page);
146		f = afs_page_dirty_from(page, priv);
147		t = afs_page_dirty_to(page, priv);
148		if (from < f)
149			f = from;
150		if (to > t)
151			t = to;
152		priv = afs_page_dirty(page, f, t);
153		set_page_private(page, priv);
154		trace_afs_page_dirty(vnode, tracepoint_string("dirty+"), page);
155	} else {
156		priv = afs_page_dirty(page, from, to);
157		attach_page_private(page, (void *)priv);
158		trace_afs_page_dirty(vnode, tracepoint_string("dirty"), page);
159	}
160
161	if (set_page_dirty(page))
162		_debug("dirtied %lx", page->index);
163
164out:
165	unlock_page(page);
166	put_page(page);
167	return copied;
168}
169
170/*
171 * kill all the pages in the given range
172 */
173static void afs_kill_pages(struct address_space *mapping,
174			   loff_t start, loff_t len)
175{
176	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
177	struct pagevec pv;
178	unsigned int loop, psize;
179
180	_enter("{%llx:%llu},%llx @%llx",
181	       vnode->fid.vid, vnode->fid.vnode, len, start);
182
183	pagevec_init(&pv);
184
185	do {
186		_debug("kill %llx @%llx", len, start);
187
188		pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
189					      PAGEVEC_SIZE, pv.pages);
190		if (pv.nr == 0)
191			break;
192
193		for (loop = 0; loop < pv.nr; loop++) {
194			struct page *page = pv.pages[loop];
195
196			if (page->index * PAGE_SIZE >= start + len)
197				break;
198
199			psize = thp_size(page);
200			start += psize;
201			len -= psize;
202			ClearPageUptodate(page);
203			end_page_writeback(page);
204			lock_page(page);
205			generic_error_remove_page(mapping, page);
206			unlock_page(page);
207		}
208
209		__pagevec_release(&pv);
210	} while (len > 0);
211
212	_leave("");
213}
214
215/*
216 * Redirty all the pages in a given range.
217 */
218static void afs_redirty_pages(struct writeback_control *wbc,
219			      struct address_space *mapping,
220			      loff_t start, loff_t len)
221{
222	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
223	struct pagevec pv;
224	unsigned int loop, psize;
225
226	_enter("{%llx:%llu},%llx @%llx",
227	       vnode->fid.vid, vnode->fid.vnode, len, start);
228
229	pagevec_init(&pv);
230
231	do {
232		_debug("redirty %llx @%llx", len, start);
233
234		pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
235					      PAGEVEC_SIZE, pv.pages);
236		if (pv.nr == 0)
237			break;
238
239		for (loop = 0; loop < pv.nr; loop++) {
240			struct page *page = pv.pages[loop];
241
242			if (page->index * PAGE_SIZE >= start + len)
243				break;
244
245			psize = thp_size(page);
246			start += psize;
247			len -= psize;
248			redirty_page_for_writepage(wbc, page);
249			end_page_writeback(page);
250		}
251
252		__pagevec_release(&pv);
253	} while (len > 0);
254
255	_leave("");
256}
257
258/*
259 * completion of write to server
260 */
261static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
262{
263	struct address_space *mapping = vnode->vfs_inode.i_mapping;
264	struct page *page;
265	pgoff_t end;
266
267	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
268
269	_enter("{%llx:%llu},{%x @%llx}",
270	       vnode->fid.vid, vnode->fid.vnode, len, start);
271
272	rcu_read_lock();
273
274	end = (start + len - 1) / PAGE_SIZE;
275	xas_for_each(&xas, page, end) {
276		if (!PageWriteback(page)) {
277			kdebug("bad %x @%llx page %lx %lx", len, start, page->index, end);
278			ASSERT(PageWriteback(page));
279		}
280
281		trace_afs_page_dirty(vnode, tracepoint_string("clear"), page);
282		detach_page_private(page);
283		page_endio(page, true, 0);
284	}
285
286	rcu_read_unlock();
287
288	afs_prune_wb_keys(vnode);
289	_leave("");
290}
291
292/*
293 * Find a key to use for the writeback.  We cached the keys used to author the
294 * writes on the vnode.  *_wbk will contain the last writeback key used or NULL
295 * and we need to start from there if it's set.
296 */
297static int afs_get_writeback_key(struct afs_vnode *vnode,
298				 struct afs_wb_key **_wbk)
299{
300	struct afs_wb_key *wbk = NULL;
301	struct list_head *p;
302	int ret = -ENOKEY, ret2;
303
304	spin_lock(&vnode->wb_lock);
305	if (*_wbk)
306		p = (*_wbk)->vnode_link.next;
307	else
308		p = vnode->wb_keys.next;
309
310	while (p != &vnode->wb_keys) {
311		wbk = list_entry(p, struct afs_wb_key, vnode_link);
312		_debug("wbk %u", key_serial(wbk->key));
313		ret2 = key_validate(wbk->key);
314		if (ret2 == 0) {
315			refcount_inc(&wbk->usage);
316			_debug("USE WB KEY %u", key_serial(wbk->key));
317			break;
318		}
319
320		wbk = NULL;
321		if (ret == -ENOKEY)
322			ret = ret2;
323		p = p->next;
324	}
325
326	spin_unlock(&vnode->wb_lock);
327	if (*_wbk)
328		afs_put_wb_key(*_wbk);
329	*_wbk = wbk;
330	return 0;
331}
332
333static void afs_store_data_success(struct afs_operation *op)
334{
335	struct afs_vnode *vnode = op->file[0].vnode;
336
337	op->ctime = op->file[0].scb.status.mtime_client;
338	afs_vnode_commit_status(op, &op->file[0]);
339	if (op->error == 0) {
340		if (!op->store.laundering)
341			afs_pages_written_back(vnode, op->store.pos, op->store.size);
342		afs_stat_v(vnode, n_stores);
343		atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
344	}
345}
346
347static const struct afs_operation_ops afs_store_data_operation = {
348	.issue_afs_rpc	= afs_fs_store_data,
349	.issue_yfs_rpc	= yfs_fs_store_data,
350	.success	= afs_store_data_success,
351};
352
353/*
354 * write to a file
355 */
356static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
357			  bool laundering)
358{
359	struct afs_operation *op;
360	struct afs_wb_key *wbk = NULL;
361	loff_t size = iov_iter_count(iter), i_size;
362	int ret = -ENOKEY;
363
364	_enter("%s{%llx:%llu.%u},%llx,%llx",
365	       vnode->volume->name,
366	       vnode->fid.vid,
367	       vnode->fid.vnode,
368	       vnode->fid.unique,
369	       size, pos);
370
371	ret = afs_get_writeback_key(vnode, &wbk);
372	if (ret) {
373		_leave(" = %d [no keys]", ret);
374		return ret;
375	}
376
377	op = afs_alloc_operation(wbk->key, vnode->volume);
378	if (IS_ERR(op)) {
379		afs_put_wb_key(wbk);
380		return -ENOMEM;
381	}
382
383	i_size = i_size_read(&vnode->vfs_inode);
384
385	afs_op_set_vnode(op, 0, vnode);
386	op->file[0].dv_delta = 1;
387	op->file[0].modification = true;
388	op->store.write_iter = iter;
389	op->store.pos = pos;
390	op->store.size = size;
391	op->store.i_size = max(pos + size, i_size);
392	op->store.laundering = laundering;
393	op->mtime = vnode->vfs_inode.i_mtime;
394	op->flags |= AFS_OPERATION_UNINTR;
395	op->ops = &afs_store_data_operation;
396
397try_next_key:
398	afs_begin_vnode_operation(op);
 
 
 
 
 
399	afs_wait_for_operation(op);
400
401	switch (op->error) {
402	case -EACCES:
403	case -EPERM:
404	case -ENOKEY:
405	case -EKEYEXPIRED:
406	case -EKEYREJECTED:
407	case -EKEYREVOKED:
408		_debug("next");
409
410		ret = afs_get_writeback_key(vnode, &wbk);
411		if (ret == 0) {
412			key_put(op->key);
413			op->key = key_get(wbk->key);
414			goto try_next_key;
415		}
416		break;
417	}
418
419	afs_put_wb_key(wbk);
420	_leave(" = %d", op->error);
421	return afs_put_operation(op);
422}
423
424/*
425 * Extend the region to be written back to include subsequent contiguously
426 * dirty pages if possible, but don't sleep while doing so.
427 *
428 * If this page holds new content, then we can include filler zeros in the
429 * writeback.
430 */
431static void afs_extend_writeback(struct address_space *mapping,
432				 struct afs_vnode *vnode,
433				 long *_count,
434				 loff_t start,
435				 loff_t max_len,
436				 bool new_content,
437				 unsigned int *_len)
438{
439	struct pagevec pvec;
440	struct page *page;
441	unsigned long priv;
442	unsigned int psize, filler = 0;
443	unsigned int f, t;
444	loff_t len = *_len;
445	pgoff_t index = (start + len) / PAGE_SIZE;
446	bool stop = true;
447	unsigned int i;
448
449	XA_STATE(xas, &mapping->i_pages, index);
450	pagevec_init(&pvec);
451
452	do {
453		/* Firstly, we gather up a batch of contiguous dirty pages
454		 * under the RCU read lock - but we can't clear the dirty flags
455		 * there if any of those pages are mapped.
456		 */
457		rcu_read_lock();
458
459		xas_for_each(&xas, page, ULONG_MAX) {
460			stop = true;
461			if (xas_retry(&xas, page))
462				continue;
463			if (xa_is_value(page))
464				break;
465			if (page->index != index)
466				break;
467
468			if (!page_cache_get_speculative(page)) {
469				xas_reset(&xas);
470				continue;
471			}
472
473			/* Has the page moved or been split? */
474			if (unlikely(page != xas_reload(&xas))) {
475				put_page(page);
476				break;
477			}
478
479			if (!trylock_page(page)) {
480				put_page(page);
481				break;
482			}
483			if (!PageDirty(page) || PageWriteback(page)) {
484				unlock_page(page);
485				put_page(page);
486				break;
487			}
488
489			psize = thp_size(page);
490			priv = page_private(page);
491			f = afs_page_dirty_from(page, priv);
492			t = afs_page_dirty_to(page, priv);
493			if (f != 0 && !new_content) {
494				unlock_page(page);
495				put_page(page);
496				break;
497			}
498
499			len += filler + t;
500			filler = psize - t;
501			if (len >= max_len || *_count <= 0)
502				stop = true;
503			else if (t == psize || new_content)
504				stop = false;
505
506			index += thp_nr_pages(page);
507			if (!pagevec_add(&pvec, page))
508				break;
509			if (stop)
510				break;
511		}
512
513		if (!stop)
514			xas_pause(&xas);
515		rcu_read_unlock();
516
517		/* Now, if we obtained any pages, we can shift them to being
518		 * writable and mark them for caching.
519		 */
520		if (!pagevec_count(&pvec))
521			break;
522
523		for (i = 0; i < pagevec_count(&pvec); i++) {
524			page = pvec.pages[i];
525			trace_afs_page_dirty(vnode, tracepoint_string("store+"), page);
526
527			if (!clear_page_dirty_for_io(page))
528				BUG();
529			if (test_set_page_writeback(page))
530				BUG();
531
532			*_count -= thp_nr_pages(page);
533			unlock_page(page);
534		}
535
536		pagevec_release(&pvec);
537		cond_resched();
538	} while (!stop);
539
540	*_len = len;
541}
542
543/*
544 * Synchronously write back the locked page and any subsequent non-locked dirty
545 * pages.
546 */
547static ssize_t afs_write_back_from_locked_page(struct address_space *mapping,
548					       struct writeback_control *wbc,
549					       struct page *page,
550					       loff_t start, loff_t end)
551{
552	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
553	struct iov_iter iter;
554	unsigned long priv;
555	unsigned int offset, to, len, max_len;
556	loff_t i_size = i_size_read(&vnode->vfs_inode);
557	bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
558	long count = wbc->nr_to_write;
559	int ret;
560
561	_enter(",%lx,%llx-%llx", page->index, start, end);
562
563	if (test_set_page_writeback(page))
564		BUG();
565
566	count -= thp_nr_pages(page);
567
568	/* Find all consecutive lockable dirty pages that have contiguous
569	 * written regions, stopping when we find a page that is not
570	 * immediately lockable, is not dirty or is missing, or we reach the
571	 * end of the range.
572	 */
573	priv = page_private(page);
574	offset = afs_page_dirty_from(page, priv);
575	to = afs_page_dirty_to(page, priv);
576	trace_afs_page_dirty(vnode, tracepoint_string("store"), page);
577
578	len = to - offset;
579	start += offset;
580	if (start < i_size) {
581		/* Trim the write to the EOF; the extra data is ignored.  Also
582		 * put an upper limit on the size of a single storedata op.
583		 */
584		max_len = 65536 * 4096;
585		max_len = min_t(unsigned long long, max_len, end - start + 1);
586		max_len = min_t(unsigned long long, max_len, i_size - start);
587
588		if (len < max_len &&
589		    (to == thp_size(page) || new_content))
590			afs_extend_writeback(mapping, vnode, &count,
591					     start, max_len, new_content, &len);
592		len = min_t(loff_t, len, max_len);
593	}
594
595	/* We now have a contiguous set of dirty pages, each with writeback
596	 * set; the first page is still locked at this point, but all the rest
597	 * have been unlocked.
598	 */
599	unlock_page(page);
600
601	if (start < i_size) {
602		_debug("write back %x @%llx [%llx]", len, start, i_size);
603
604		iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
605		ret = afs_store_data(vnode, &iter, start, false);
606	} else {
607		_debug("write discard %x @%llx [%llx]", len, start, i_size);
608
609		/* The dirty region was entirely beyond the EOF. */
610		afs_pages_written_back(vnode, start, len);
611		ret = 0;
612	}
613
614	switch (ret) {
615	case 0:
616		wbc->nr_to_write = count;
617		ret = len;
618		break;
619
620	default:
621		pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
622		fallthrough;
623	case -EACCES:
624	case -EPERM:
625	case -ENOKEY:
626	case -EKEYEXPIRED:
627	case -EKEYREJECTED:
628	case -EKEYREVOKED:
629		afs_redirty_pages(wbc, mapping, start, len);
630		mapping_set_error(mapping, ret);
631		break;
632
633	case -EDQUOT:
634	case -ENOSPC:
635		afs_redirty_pages(wbc, mapping, start, len);
636		mapping_set_error(mapping, -ENOSPC);
637		break;
638
639	case -EROFS:
640	case -EIO:
641	case -EREMOTEIO:
642	case -EFBIG:
643	case -ENOENT:
644	case -ENOMEDIUM:
645	case -ENXIO:
646		trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
647		afs_kill_pages(mapping, start, len);
648		mapping_set_error(mapping, ret);
649		break;
650	}
651
652	_leave(" = %d", ret);
653	return ret;
 
 
 
654}
655
656/*
657 * write a page back to the server
658 * - the caller locked the page for us
659 */
660int afs_writepage(struct page *page, struct writeback_control *wbc)
661{
662	ssize_t ret;
663	loff_t start;
664
665	_enter("{%lx},", page->index);
666
667	start = page->index * PAGE_SIZE;
668	ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
669					      start, LLONG_MAX - start);
670	if (ret < 0) {
671		_leave(" = %zd", ret);
672		return ret;
673	}
674
675	_leave(" = 0");
676	return 0;
677}
678
679/*
680 * write a region of pages back to the server
 
681 */
682static int afs_writepages_region(struct address_space *mapping,
683				 struct writeback_control *wbc,
684				 loff_t start, loff_t end, loff_t *_next)
685{
686	struct page *page;
687	ssize_t ret;
688	int n;
689
690	_enter("%llx,%llx,", start, end);
691
692	do {
693		pgoff_t index = start / PAGE_SIZE;
694
695		n = find_get_pages_range_tag(mapping, &index, end / PAGE_SIZE,
696					     PAGECACHE_TAG_DIRTY, 1, &page);
697		if (!n)
698			break;
699
700		start = (loff_t)page->index * PAGE_SIZE; /* May regress with THPs */
701
702		_debug("wback %lx", page->index);
703
704		/* At this point we hold neither the i_pages lock nor the
705		 * page lock: the page may be truncated or invalidated
706		 * (changing page->mapping to NULL), or even swizzled
707		 * back from swapper_space to tmpfs file mapping
708		 */
709		if (wbc->sync_mode != WB_SYNC_NONE) {
710			ret = lock_page_killable(page);
711			if (ret < 0) {
712				put_page(page);
713				return ret;
714			}
715		} else {
716			if (!trylock_page(page)) {
717				put_page(page);
718				return 0;
719			}
720		}
721
722		if (page->mapping != mapping || !PageDirty(page)) {
723			start += thp_size(page);
724			unlock_page(page);
725			put_page(page);
726			continue;
727		}
728
729		if (PageWriteback(page)) {
730			unlock_page(page);
731			if (wbc->sync_mode != WB_SYNC_NONE)
732				wait_on_page_writeback(page);
733			put_page(page);
734			continue;
735		}
736
737		if (!clear_page_dirty_for_io(page))
738			BUG();
739		ret = afs_write_back_from_locked_page(mapping, wbc, page, start, end);
740		put_page(page);
741		if (ret < 0) {
742			_leave(" = %zd", ret);
743			return ret;
744		}
745
746		start += ret;
747
748		cond_resched();
749	} while (wbc->nr_to_write > 0);
750
751	*_next = start;
752	_leave(" = 0 [%llx]", *_next);
753	return 0;
754}
755
756/*
757 * write some of the pending data back to the server
758 */
759int afs_writepages(struct address_space *mapping,
760		   struct writeback_control *wbc)
761{
762	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
763	loff_t start, next;
764	int ret;
765
766	_enter("");
767
768	/* We have to be careful as we can end up racing with setattr()
769	 * truncating the pagecache since the caller doesn't take a lock here
770	 * to prevent it.
771	 */
772	if (wbc->sync_mode == WB_SYNC_ALL)
773		down_read(&vnode->validate_lock);
774	else if (!down_read_trylock(&vnode->validate_lock))
775		return 0;
776
777	if (wbc->range_cyclic) {
778		start = mapping->writeback_index * PAGE_SIZE;
779		ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX, &next);
780		if (ret == 0) {
781			mapping->writeback_index = next / PAGE_SIZE;
782			if (start > 0 && wbc->nr_to_write > 0) {
783				ret = afs_writepages_region(mapping, wbc, 0,
784							    start, &next);
785				if (ret == 0)
786					mapping->writeback_index =
787						next / PAGE_SIZE;
788			}
789		}
790	} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
791		ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX, &next);
792		if (wbc->nr_to_write > 0 && ret == 0)
793			mapping->writeback_index = next / PAGE_SIZE;
794	} else {
795		ret = afs_writepages_region(mapping, wbc,
796					    wbc->range_start, wbc->range_end, &next);
797	}
798
799	up_read(&vnode->validate_lock);
800	_leave(" = %d", ret);
801	return ret;
802}
803
804/*
805 * write to an AFS file
806 */
807ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
808{
809	struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
810	struct afs_file *af = iocb->ki_filp->private_data;
811	ssize_t result;
812	size_t count = iov_iter_count(from);
813
814	_enter("{%llx:%llu},{%zu},",
815	       vnode->fid.vid, vnode->fid.vnode, count);
816
817	if (IS_SWAPFILE(&vnode->vfs_inode)) {
818		printk(KERN_INFO
819		       "AFS: Attempt to write to active swap file!\n");
820		return -EBUSY;
821	}
822
823	if (!count)
824		return 0;
825
826	result = afs_validate(vnode, af->key);
827	if (result < 0)
828		return result;
829
830	result = generic_file_write_iter(iocb, from);
831
832	_leave(" = %zd", result);
833	return result;
834}
835
836/*
837 * flush any dirty pages for this process, and check for write errors.
838 * - the return status from this call provides a reliable indication of
839 *   whether any write errors occurred for this process.
840 */
841int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
842{
843	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
844	struct afs_file *af = file->private_data;
845	int ret;
846
847	_enter("{%llx:%llu},{n=%pD},%d",
848	       vnode->fid.vid, vnode->fid.vnode, file,
849	       datasync);
850
851	ret = afs_validate(vnode, af->key);
852	if (ret < 0)
853		return ret;
854
855	return file_write_and_wait_range(file, start, end);
856}
857
858/*
859 * notification that a previously read-only page is about to become writable
860 * - if it returns an error, the caller will deliver a bus error signal
861 */
862vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
863{
864	struct page *page = thp_head(vmf->page);
865	struct file *file = vmf->vma->vm_file;
866	struct inode *inode = file_inode(file);
867	struct afs_vnode *vnode = AFS_FS_I(inode);
868	struct afs_file *af = file->private_data;
869	unsigned long priv;
870	vm_fault_t ret = VM_FAULT_RETRY;
871
872	_enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);
873
874	afs_validate(vnode, af->key);
875
876	sb_start_pagefault(inode->i_sb);
877
878	/* Wait for the page to be written to the cache before we allow it to
879	 * be modified.  We then assume the entire page will need writing back.
880	 */
881#ifdef CONFIG_AFS_FSCACHE
882	if (PageFsCache(page) &&
883	    wait_on_page_fscache_killable(page) < 0)
884		goto out;
885#endif
886
887	if (wait_on_page_writeback_killable(page))
888		goto out;
889
890	if (lock_page_killable(page) < 0)
891		goto out;
892
893	/* We mustn't change page->private until writeback is complete as that
894	 * details the portion of the page we need to write back and we might
895	 * need to redirty the page if there's a problem.
896	 */
897	if (wait_on_page_writeback_killable(page) < 0) {
898		unlock_page(page);
899		goto out;
900	}
901
902	priv = afs_page_dirty(page, 0, thp_size(page));
903	priv = afs_page_dirty_mmapped(priv);
904	if (PagePrivate(page)) {
905		set_page_private(page, priv);
906		trace_afs_page_dirty(vnode, tracepoint_string("mkwrite+"), page);
907	} else {
908		attach_page_private(page, (void *)priv);
909		trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), page);
910	}
911	file_update_time(file);
912
913	ret = VM_FAULT_LOCKED;
914out:
915	sb_end_pagefault(inode->i_sb);
916	return ret;
917}
918
919/*
920 * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
921 */
922void afs_prune_wb_keys(struct afs_vnode *vnode)
923{
924	LIST_HEAD(graveyard);
925	struct afs_wb_key *wbk, *tmp;
926
927	/* Discard unused keys */
928	spin_lock(&vnode->wb_lock);
929
930	if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
931	    !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
932		list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
933			if (refcount_read(&wbk->usage) == 1)
934				list_move(&wbk->vnode_link, &graveyard);
935		}
936	}
937
938	spin_unlock(&vnode->wb_lock);
939
940	while (!list_empty(&graveyard)) {
941		wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
942		list_del(&wbk->vnode_link);
943		afs_put_wb_key(wbk);
944	}
945}
946
947/*
948 * Clean up a page during invalidation.
949 */
950int afs_launder_page(struct page *page)
951{
952	struct address_space *mapping = page->mapping;
953	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
954	struct iov_iter iter;
955	struct bio_vec bv[1];
956	unsigned long priv;
957	unsigned int f, t;
958	int ret = 0;
959
960	_enter("{%lx}", page->index);
961
962	priv = page_private(page);
963	if (clear_page_dirty_for_io(page)) {
964		f = 0;
965		t = thp_size(page);
966		if (PagePrivate(page)) {
967			f = afs_page_dirty_from(page, priv);
968			t = afs_page_dirty_to(page, priv);
969		}
970
971		bv[0].bv_page = page;
972		bv[0].bv_offset = f;
973		bv[0].bv_len = t - f;
974		iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
975
976		trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
977		ret = afs_store_data(vnode, &iter, page_offset(page) + f, true);
978	}
979
980	trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
981	detach_page_private(page);
982	wait_on_page_fscache(page);
983	return ret;
984}