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 "internal.h"
 15
 16/*
 17 * mark a page as having been made dirty and thus needing writeback
 18 */
 19int afs_set_page_dirty(struct page *page)
 20{
 21	_enter("");
 22	return __set_page_dirty_nobuffers(page);
 23}
 24
 25/*
 26 * partly or wholly fill a page that's under preparation for writing
 27 */
 28static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
 29			 loff_t pos, unsigned int len, struct page *page)
 30{
 31	struct afs_read *req;
 32	size_t p;
 33	void *data;
 34	int ret;
 35
 36	_enter(",,%llu", (unsigned long long)pos);
 37
 38	if (pos >= vnode->vfs_inode.i_size) {
 39		p = pos & ~PAGE_MASK;
 40		ASSERTCMP(p + len, <=, PAGE_SIZE);
 41		data = kmap(page);
 42		memset(data + p, 0, len);
 43		kunmap(page);
 44		return 0;
 45	}
 46
 47	req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
 48	if (!req)
 49		return -ENOMEM;
 50
 51	refcount_set(&req->usage, 1);
 52	req->pos = pos;
 53	req->len = len;
 54	req->nr_pages = 1;
 55	req->pages = req->array;
 56	req->pages[0] = page;
 57	get_page(page);
 58
 59	ret = afs_fetch_data(vnode, key, req);
 60	afs_put_read(req);
 61	if (ret < 0) {
 62		if (ret == -ENOENT) {
 63			_debug("got NOENT from server"
 64			       " - marking file deleted and stale");
 65			set_bit(AFS_VNODE_DELETED, &vnode->flags);
 66			ret = -ESTALE;
 67		}
 68	}
 69
 70	_leave(" = %d", ret);
 71	return ret;
 72}
 73
 74/*
 75 * prepare to perform part of a write to a page
 76 */
 77int afs_write_begin(struct file *file, struct address_space *mapping,
 78		    loff_t pos, unsigned len, unsigned flags,
 79		    struct page **pagep, void **fsdata)
 80{
 81	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 82	struct page *page;
 83	struct key *key = afs_file_key(file);
 84	unsigned long priv;
 85	unsigned f, from = pos & (PAGE_SIZE - 1);
 86	unsigned t, to = from + len;
 87	pgoff_t index = pos >> PAGE_SHIFT;
 88	int ret;
 89
 90	_enter("{%llx:%llu},{%lx},%u,%u",
 91	       vnode->fid.vid, vnode->fid.vnode, index, from, to);
 92
 93	/* We want to store information about how much of a page is altered in
 94	 * page->private.
 95	 */
 96	BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
 97
 98	page = grab_cache_page_write_begin(mapping, index, flags);
 99	if (!page)
100		return -ENOMEM;
101
102	if (!PageUptodate(page) && len != PAGE_SIZE) {
103		ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
104		if (ret < 0) {
105			unlock_page(page);
106			put_page(page);
107			_leave(" = %d [prep]", ret);
108			return ret;
109		}
110		SetPageUptodate(page);
111	}
112
113	/* page won't leak in error case: it eventually gets cleaned off LRU */
114	*pagep = page;
115
116try_again:
117	/* See if this page is already partially written in a way that we can
118	 * merge the new write with.
119	 */
120	t = f = 0;
121	if (PagePrivate(page)) {
122		priv = page_private(page);
123		f = priv & AFS_PRIV_MAX;
124		t = priv >> AFS_PRIV_SHIFT;
125		ASSERTCMP(f, <=, t);
126	}
127
128	if (f != t) {
129		if (PageWriteback(page)) {
130			trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
131					     page->index, priv);
132			goto flush_conflicting_write;
133		}
134		/* If the file is being filled locally, allow inter-write
135		 * spaces to be merged into writes.  If it's not, only write
136		 * back what the user gives us.
137		 */
138		if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
139		    (to < f || from > t))
140			goto flush_conflicting_write;
141		if (from < f)
142			f = from;
143		if (to > t)
144			t = to;
145	} else {
146		f = from;
147		t = to;
148	}
149
150	priv = (unsigned long)t << AFS_PRIV_SHIFT;
151	priv |= f;
152	trace_afs_page_dirty(vnode, tracepoint_string("begin"),
153			     page->index, priv);
154	SetPagePrivate(page);
155	set_page_private(page, priv);
156	_leave(" = 0");
157	return 0;
158
159	/* The previous write and this write aren't adjacent or overlapping, so
160	 * flush the page out.
161	 */
162flush_conflicting_write:
163	_debug("flush conflict");
164	ret = write_one_page(page);
165	if (ret < 0) {
166		_leave(" = %d", ret);
167		return ret;
168	}
169
170	ret = lock_page_killable(page);
171	if (ret < 0) {
172		_leave(" = %d", ret);
173		return ret;
174	}
175	goto try_again;
176}
177
178/*
179 * finalise part of a write to a page
180 */
181int afs_write_end(struct file *file, struct address_space *mapping,
182		  loff_t pos, unsigned len, unsigned copied,
183		  struct page *page, void *fsdata)
184{
185	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
186	struct key *key = afs_file_key(file);
187	loff_t i_size, maybe_i_size;
188	int ret;
189
190	_enter("{%llx:%llu},{%lx}",
191	       vnode->fid.vid, vnode->fid.vnode, page->index);
192
193	maybe_i_size = pos + copied;
194
195	i_size = i_size_read(&vnode->vfs_inode);
196	if (maybe_i_size > i_size) {
197		write_seqlock(&vnode->cb_lock);
198		i_size = i_size_read(&vnode->vfs_inode);
199		if (maybe_i_size > i_size)
200			i_size_write(&vnode->vfs_inode, maybe_i_size);
201		write_sequnlock(&vnode->cb_lock);
202	}
203
204	if (!PageUptodate(page)) {
205		if (copied < len) {
206			/* Try and load any missing data from the server.  The
207			 * unmarshalling routine will take care of clearing any
208			 * bits that are beyond the EOF.
209			 */
210			ret = afs_fill_page(vnode, key, pos + copied,
211					    len - copied, page);
212			if (ret < 0)
213				goto out;
214		}
215		SetPageUptodate(page);
216	}
217
218	set_page_dirty(page);
219	if (PageDirty(page))
220		_debug("dirtied");
221	ret = copied;
222
223out:
224	unlock_page(page);
225	put_page(page);
226	return ret;
227}
228
229/*
230 * kill all the pages in the given range
231 */
232static void afs_kill_pages(struct address_space *mapping,
233			   pgoff_t first, pgoff_t last)
234{
235	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
236	struct pagevec pv;
237	unsigned count, loop;
238
239	_enter("{%llx:%llu},%lx-%lx",
240	       vnode->fid.vid, vnode->fid.vnode, first, last);
241
242	pagevec_init(&pv);
243
244	do {
245		_debug("kill %lx-%lx", first, last);
246
247		count = last - first + 1;
248		if (count > PAGEVEC_SIZE)
249			count = PAGEVEC_SIZE;
250		pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
251		ASSERTCMP(pv.nr, ==, count);
252
253		for (loop = 0; loop < count; loop++) {
254			struct page *page = pv.pages[loop];
255			ClearPageUptodate(page);
256			SetPageError(page);
257			end_page_writeback(page);
258			if (page->index >= first)
259				first = page->index + 1;
260			lock_page(page);
261			generic_error_remove_page(mapping, page);
262			unlock_page(page);
263		}
264
265		__pagevec_release(&pv);
266	} while (first <= last);
267
268	_leave("");
269}
270
271/*
272 * Redirty all the pages in a given range.
273 */
274static void afs_redirty_pages(struct writeback_control *wbc,
275			      struct address_space *mapping,
276			      pgoff_t first, pgoff_t last)
277{
278	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
279	struct pagevec pv;
280	unsigned count, loop;
281
282	_enter("{%llx:%llu},%lx-%lx",
283	       vnode->fid.vid, vnode->fid.vnode, first, last);
284
285	pagevec_init(&pv);
286
287	do {
288		_debug("redirty %lx-%lx", first, last);
289
290		count = last - first + 1;
291		if (count > PAGEVEC_SIZE)
292			count = PAGEVEC_SIZE;
293		pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
294		ASSERTCMP(pv.nr, ==, count);
295
296		for (loop = 0; loop < count; loop++) {
297			struct page *page = pv.pages[loop];
298
299			redirty_page_for_writepage(wbc, page);
300			end_page_writeback(page);
301			if (page->index >= first)
302				first = page->index + 1;
303		}
304
305		__pagevec_release(&pv);
306	} while (first <= last);
307
308	_leave("");
309}
310
311/*
312 * completion of write to server
313 */
314static void afs_pages_written_back(struct afs_vnode *vnode,
315				   pgoff_t first, pgoff_t last)
316{
317	struct pagevec pv;
318	unsigned long priv;
319	unsigned count, loop;
320
321	_enter("{%llx:%llu},{%lx-%lx}",
322	       vnode->fid.vid, vnode->fid.vnode, first, last);
323
324	pagevec_init(&pv);
325
326	do {
327		_debug("done %lx-%lx", first, last);
328
329		count = last - first + 1;
330		if (count > PAGEVEC_SIZE)
331			count = PAGEVEC_SIZE;
332		pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
333					      first, count, pv.pages);
334		ASSERTCMP(pv.nr, ==, count);
335
336		for (loop = 0; loop < count; loop++) {
337			priv = page_private(pv.pages[loop]);
338			trace_afs_page_dirty(vnode, tracepoint_string("clear"),
339					     pv.pages[loop]->index, priv);
340			set_page_private(pv.pages[loop], 0);
341			end_page_writeback(pv.pages[loop]);
342		}
343		first += count;
344		__pagevec_release(&pv);
345	} while (first <= last);
346
347	afs_prune_wb_keys(vnode);
348	_leave("");
349}
350
351/*
352 * Find a key to use for the writeback.  We cached the keys used to author the
353 * writes on the vnode.  *_wbk will contain the last writeback key used or NULL
354 * and we need to start from there if it's set.
355 */
356static int afs_get_writeback_key(struct afs_vnode *vnode,
357				 struct afs_wb_key **_wbk)
358{
359	struct afs_wb_key *wbk = NULL;
360	struct list_head *p;
361	int ret = -ENOKEY, ret2;
362
363	spin_lock(&vnode->wb_lock);
364	if (*_wbk)
365		p = (*_wbk)->vnode_link.next;
366	else
367		p = vnode->wb_keys.next;
368
369	while (p != &vnode->wb_keys) {
370		wbk = list_entry(p, struct afs_wb_key, vnode_link);
371		_debug("wbk %u", key_serial(wbk->key));
372		ret2 = key_validate(wbk->key);
373		if (ret2 == 0) {
374			refcount_inc(&wbk->usage);
375			_debug("USE WB KEY %u", key_serial(wbk->key));
376			break;
377		}
378
379		wbk = NULL;
380		if (ret == -ENOKEY)
381			ret = ret2;
382		p = p->next;
383	}
384
385	spin_unlock(&vnode->wb_lock);
386	if (*_wbk)
387		afs_put_wb_key(*_wbk);
388	*_wbk = wbk;
389	return 0;
390}
391
392static void afs_store_data_success(struct afs_operation *op)
393{
394	struct afs_vnode *vnode = op->file[0].vnode;
395
396	op->ctime = op->file[0].scb.status.mtime_client;
397	afs_vnode_commit_status(op, &op->file[0]);
398	if (op->error == 0) {
399		afs_pages_written_back(vnode, op->store.first, op->store.last);
 
400		afs_stat_v(vnode, n_stores);
401		atomic_long_add((op->store.last * PAGE_SIZE + op->store.last_to) -
402				(op->store.first * PAGE_SIZE + op->store.first_offset),
403				&afs_v2net(vnode)->n_store_bytes);
404	}
405}
406
407static const struct afs_operation_ops afs_store_data_operation = {
408	.issue_afs_rpc	= afs_fs_store_data,
409	.issue_yfs_rpc	= yfs_fs_store_data,
410	.success	= afs_store_data_success,
411};
412
413/*
414 * write to a file
415 */
416static int afs_store_data(struct address_space *mapping,
417			  pgoff_t first, pgoff_t last,
418			  unsigned offset, unsigned to)
419{
420	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
421	struct afs_operation *op;
422	struct afs_wb_key *wbk = NULL;
423	int ret;
 
424
425	_enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
426	       vnode->volume->name,
427	       vnode->fid.vid,
428	       vnode->fid.vnode,
429	       vnode->fid.unique,
430	       first, last, offset, to);
431
432	ret = afs_get_writeback_key(vnode, &wbk);
433	if (ret) {
434		_leave(" = %d [no keys]", ret);
435		return ret;
436	}
437
438	op = afs_alloc_operation(wbk->key, vnode->volume);
439	if (IS_ERR(op)) {
440		afs_put_wb_key(wbk);
441		return -ENOMEM;
442	}
443
444	afs_op_set_vnode(op, 0, vnode);
445	op->file[0].dv_delta = 1;
446	op->store.mapping = mapping;
447	op->store.first = first;
448	op->store.last = last;
449	op->store.first_offset = offset;
450	op->store.last_to = to;
451	op->mtime = vnode->vfs_inode.i_mtime;
452	op->flags |= AFS_OPERATION_UNINTR;
453	op->ops = &afs_store_data_operation;
454
455try_next_key:
456	afs_begin_vnode_operation(op);
 
 
 
 
 
457	afs_wait_for_operation(op);
458
459	switch (op->error) {
460	case -EACCES:
461	case -EPERM:
462	case -ENOKEY:
463	case -EKEYEXPIRED:
464	case -EKEYREJECTED:
465	case -EKEYREVOKED:
466		_debug("next");
467
468		ret = afs_get_writeback_key(vnode, &wbk);
469		if (ret == 0) {
470			key_put(op->key);
471			op->key = key_get(wbk->key);
472			goto try_next_key;
473		}
474		break;
475	}
476
477	afs_put_wb_key(wbk);
478	_leave(" = %d", op->error);
479	return afs_put_operation(op);
480}
481
482/*
483 * Synchronously write back the locked page and any subsequent non-locked dirty
484 * pages.
485 */
486static int afs_write_back_from_locked_page(struct address_space *mapping,
487					   struct writeback_control *wbc,
488					   struct page *primary_page,
489					   pgoff_t final_page)
490{
491	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
492	struct page *pages[8], *page;
493	unsigned long count, priv;
494	unsigned n, offset, to, f, t;
495	pgoff_t start, first, last;
496	loff_t i_size, end;
497	int loop, ret;
498
499	_enter(",%lx", primary_page->index);
500
501	count = 1;
502	if (test_set_page_writeback(primary_page))
503		BUG();
504
505	/* Find all consecutive lockable dirty pages that have contiguous
506	 * written regions, stopping when we find a page that is not
507	 * immediately lockable, is not dirty or is missing, or we reach the
508	 * end of the range.
509	 */
510	start = primary_page->index;
511	priv = page_private(primary_page);
512	offset = priv & AFS_PRIV_MAX;
513	to = priv >> AFS_PRIV_SHIFT;
514	trace_afs_page_dirty(vnode, tracepoint_string("store"),
515			     primary_page->index, priv);
516
517	WARN_ON(offset == to);
518	if (offset == to)
519		trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
520				     primary_page->index, priv);
521
522	if (start >= final_page ||
523	    (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
524		goto no_more;
525
526	start++;
527	do {
528		_debug("more %lx [%lx]", start, count);
529		n = final_page - start + 1;
530		if (n > ARRAY_SIZE(pages))
531			n = ARRAY_SIZE(pages);
532		n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
533		_debug("fgpc %u", n);
534		if (n == 0)
535			goto no_more;
536		if (pages[0]->index != start) {
537			do {
538				put_page(pages[--n]);
539			} while (n > 0);
540			goto no_more;
541		}
542
543		for (loop = 0; loop < n; loop++) {
544			page = pages[loop];
545			if (to != PAGE_SIZE &&
546			    !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
547				break;
548			if (page->index > final_page)
549				break;
550			if (!trylock_page(page))
551				break;
552			if (!PageDirty(page) || PageWriteback(page)) {
553				unlock_page(page);
554				break;
555			}
556
557			priv = page_private(page);
558			f = priv & AFS_PRIV_MAX;
559			t = priv >> AFS_PRIV_SHIFT;
560			if (f != 0 &&
561			    !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
562				unlock_page(page);
563				break;
564			}
565			to = t;
566
567			trace_afs_page_dirty(vnode, tracepoint_string("store+"),
568					     page->index, priv);
569
570			if (!clear_page_dirty_for_io(page))
571				BUG();
572			if (test_set_page_writeback(page))
573				BUG();
574			unlock_page(page);
575			put_page(page);
576		}
577		count += loop;
578		if (loop < n) {
579			for (; loop < n; loop++)
580				put_page(pages[loop]);
581			goto no_more;
582		}
583
584		start += loop;
585	} while (start <= final_page && count < 65536);
586
587no_more:
588	/* We now have a contiguous set of dirty pages, each with writeback
589	 * set; the first page is still locked at this point, but all the rest
590	 * have been unlocked.
591	 */
592	unlock_page(primary_page);
593
594	first = primary_page->index;
595	last = first + count - 1;
596
597	end = (loff_t)last * PAGE_SIZE + to;
598	i_size = i_size_read(&vnode->vfs_inode);
599
600	_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
601	if (end > i_size)
602		to = i_size & ~PAGE_MASK;
603
604	ret = afs_store_data(mapping, first, last, offset, to);
605	switch (ret) {
606	case 0:
607		ret = count;
608		break;
609
610	default:
611		pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
612		fallthrough;
613	case -EACCES:
614	case -EPERM:
615	case -ENOKEY:
616	case -EKEYEXPIRED:
617	case -EKEYREJECTED:
618	case -EKEYREVOKED:
619		afs_redirty_pages(wbc, mapping, first, last);
620		mapping_set_error(mapping, ret);
621		break;
622
623	case -EDQUOT:
624	case -ENOSPC:
625		afs_redirty_pages(wbc, mapping, first, last);
626		mapping_set_error(mapping, -ENOSPC);
627		break;
628
629	case -EROFS:
630	case -EIO:
631	case -EREMOTEIO:
632	case -EFBIG:
633	case -ENOENT:
634	case -ENOMEDIUM:
635	case -ENXIO:
636		trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
637		afs_kill_pages(mapping, first, last);
638		mapping_set_error(mapping, ret);
639		break;
640	}
641
642	_leave(" = %d", ret);
643	return ret;
 
 
 
644}
645
646/*
647 * write a page back to the server
648 * - the caller locked the page for us
649 */
650int afs_writepage(struct page *page, struct writeback_control *wbc)
651{
652	int ret;
 
653
654	_enter("{%lx},", page->index);
655
656	ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
657					      wbc->range_end >> PAGE_SHIFT);
658	if (ret < 0) {
659		_leave(" = %d", ret);
660		return 0;
661	}
662
663	wbc->nr_to_write -= ret;
664
665	_leave(" = 0");
666	return 0;
667}
668
669/*
670 * write a region of pages back to the server
 
671 */
672static int afs_writepages_region(struct address_space *mapping,
673				 struct writeback_control *wbc,
674				 pgoff_t index, pgoff_t end, pgoff_t *_next)
675{
676	struct page *page;
677	int ret, n;
678
679	_enter(",,%lx,%lx,", index, end);
680
681	do {
682		n = find_get_pages_range_tag(mapping, &index, end,
683					PAGECACHE_TAG_DIRTY, 1, &page);
684		if (!n)
685			break;
686
687		_debug("wback %lx", page->index);
688
689		/*
690		 * at this point we hold neither the i_pages lock nor the
691		 * page lock: the page may be truncated or invalidated
692		 * (changing page->mapping to NULL), or even swizzled
693		 * back from swapper_space to tmpfs file mapping
694		 */
695		ret = lock_page_killable(page);
696		if (ret < 0) {
697			put_page(page);
698			_leave(" = %d", ret);
699			return ret;
700		}
701
702		if (page->mapping != mapping || !PageDirty(page)) {
703			unlock_page(page);
704			put_page(page);
705			continue;
706		}
707
708		if (PageWriteback(page)) {
709			unlock_page(page);
710			if (wbc->sync_mode != WB_SYNC_NONE)
711				wait_on_page_writeback(page);
712			put_page(page);
713			continue;
714		}
715
716		if (!clear_page_dirty_for_io(page))
717			BUG();
718		ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
719		put_page(page);
720		if (ret < 0) {
721			_leave(" = %d", ret);
722			return ret;
723		}
724
725		wbc->nr_to_write -= ret;
726
727		cond_resched();
728	} while (index < end && wbc->nr_to_write > 0);
729
730	*_next = index;
731	_leave(" = 0 [%lx]", *_next);
732	return 0;
 
733}
734
735/*
736 * write some of the pending data back to the server
737 */
738int afs_writepages(struct address_space *mapping,
739		   struct writeback_control *wbc)
740{
741	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
742	pgoff_t start, end, next;
743	int ret;
744
745	_enter("");
746
747	/* We have to be careful as we can end up racing with setattr()
748	 * truncating the pagecache since the caller doesn't take a lock here
749	 * to prevent it.
750	 */
751	if (wbc->sync_mode == WB_SYNC_ALL)
752		down_read(&vnode->validate_lock);
753	else if (!down_read_trylock(&vnode->validate_lock))
754		return 0;
755
756	if (wbc->range_cyclic) {
757		start = mapping->writeback_index;
758		end = -1;
759		ret = afs_writepages_region(mapping, wbc, start, end, &next);
760		if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
761			ret = afs_writepages_region(mapping, wbc, 0, start,
762						    &next);
763		mapping->writeback_index = next;
764	} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
765		end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
766		ret = afs_writepages_region(mapping, wbc, 0, end, &next);
767		if (wbc->nr_to_write > 0)
768			mapping->writeback_index = next;
769	} else {
770		start = wbc->range_start >> PAGE_SHIFT;
771		end = wbc->range_end >> PAGE_SHIFT;
772		ret = afs_writepages_region(mapping, wbc, start, end, &next);
773	}
774
775	up_read(&vnode->validate_lock);
776	_leave(" = %d", ret);
777	return ret;
778}
779
780/*
781 * write to an AFS file
782 */
783ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
784{
785	struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
786	ssize_t result;
787	size_t count = iov_iter_count(from);
788
789	_enter("{%llx:%llu},{%zu},",
790	       vnode->fid.vid, vnode->fid.vnode, count);
791
792	if (IS_SWAPFILE(&vnode->vfs_inode)) {
793		printk(KERN_INFO
794		       "AFS: Attempt to write to active swap file!\n");
795		return -EBUSY;
796	}
797
798	if (!count)
799		return 0;
800
801	result = generic_file_write_iter(iocb, from);
802
803	_leave(" = %zd", result);
804	return result;
805}
806
807/*
808 * flush any dirty pages for this process, and check for write errors.
809 * - the return status from this call provides a reliable indication of
810 *   whether any write errors occurred for this process.
811 */
812int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
813{
814	struct inode *inode = file_inode(file);
815	struct afs_vnode *vnode = AFS_FS_I(inode);
 
816
817	_enter("{%llx:%llu},{n=%pD},%d",
818	       vnode->fid.vid, vnode->fid.vnode, file,
819	       datasync);
820
 
 
 
 
821	return file_write_and_wait_range(file, start, end);
822}
823
824/*
825 * notification that a previously read-only page is about to become writable
826 * - if it returns an error, the caller will deliver a bus error signal
827 */
828vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
829{
830	struct file *file = vmf->vma->vm_file;
831	struct inode *inode = file_inode(file);
832	struct afs_vnode *vnode = AFS_FS_I(inode);
833	unsigned long priv;
834
835	_enter("{{%llx:%llu}},{%lx}",
836	       vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
837
838	sb_start_pagefault(inode->i_sb);
839
840	/* Wait for the page to be written to the cache before we allow it to
841	 * be modified.  We then assume the entire page will need writing back.
842	 */
843#ifdef CONFIG_AFS_FSCACHE
844	fscache_wait_on_page_write(vnode->cache, vmf->page);
845#endif
846
847	if (PageWriteback(vmf->page) &&
848	    wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
849		return VM_FAULT_RETRY;
850
851	if (lock_page_killable(vmf->page) < 0)
852		return VM_FAULT_RETRY;
853
854	/* We mustn't change page->private until writeback is complete as that
855	 * details the portion of the page we need to write back and we might
856	 * need to redirty the page if there's a problem.
857	 */
858	wait_on_page_writeback(vmf->page);
859
860	priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
861	priv |= 0; /* From */
862	trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
863			     vmf->page->index, priv);
864	SetPagePrivate(vmf->page);
865	set_page_private(vmf->page, priv);
866	file_update_time(file);
867
868	sb_end_pagefault(inode->i_sb);
869	return VM_FAULT_LOCKED;
870}
871
872/*
873 * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
874 */
875void afs_prune_wb_keys(struct afs_vnode *vnode)
876{
877	LIST_HEAD(graveyard);
878	struct afs_wb_key *wbk, *tmp;
879
880	/* Discard unused keys */
881	spin_lock(&vnode->wb_lock);
882
883	if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
884	    !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
885		list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
886			if (refcount_read(&wbk->usage) == 1)
887				list_move(&wbk->vnode_link, &graveyard);
888		}
889	}
890
891	spin_unlock(&vnode->wb_lock);
892
893	while (!list_empty(&graveyard)) {
894		wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
895		list_del(&wbk->vnode_link);
896		afs_put_wb_key(wbk);
897	}
898}
899
900/*
901 * Clean up a page during invalidation.
902 */
903int afs_launder_page(struct page *page)
904{
905	struct address_space *mapping = page->mapping;
906	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
907	unsigned long priv;
908	unsigned int f, t;
909	int ret = 0;
910
911	_enter("{%lx}", page->index);
912
913	priv = page_private(page);
914	if (clear_page_dirty_for_io(page)) {
915		f = 0;
916		t = PAGE_SIZE;
917		if (PagePrivate(page)) {
918			f = priv & AFS_PRIV_MAX;
919			t = priv >> AFS_PRIV_SHIFT;
920		}
921
922		trace_afs_page_dirty(vnode, tracepoint_string("launder"),
923				     page->index, priv);
924		ret = afs_store_data(mapping, page->index, page->index, t, f);
925	}
926
927	trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
928			     page->index, priv);
929	set_page_private(page, 0);
930	ClearPagePrivate(page);
931
932#ifdef CONFIG_AFS_FSCACHE
933	if (PageFsCache(page)) {
934		fscache_wait_on_page_write(vnode->cache, page);
935		fscache_uncache_page(vnode->cache, page);
936	}
937#endif
938	return ret;
939}