1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* linux/fs/nfs/write.c
4	*
5	* Write file data over NFS.
6	*
7	* Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
8	*/
9
10	#include <linux/types.h>
11	#include <linux/slab.h>
12	#include <linux/mm.h>
13	#include <linux/pagemap.h>
14	#include <linux/file.h>
15	#include <linux/writeback.h>
16	#include <linux/swap.h>
17	#include <linux/migrate.h>
18
19	#include <linux/sunrpc/clnt.h>
20	#include <linux/nfs_fs.h>
21	#include <linux/nfs_mount.h>
22	#include <linux/nfs_page.h>
23	#include <linux/backing-dev.h>
24	#include <linux/export.h>
25	#include <linux/freezer.h>
26	#include <linux/wait.h>
27	#include <linux/iversion.h>
28	#include <linux/filelock.h>
29
30	#include <linux/uaccess.h>
31	#include <linux/sched/mm.h>
32
33	#include "delegation.h"
34	#include "internal.h"
35	#include "iostat.h"
36	#include "nfs4_fs.h"
37	#include "fscache.h"
38	#include "pnfs.h"
39
40	#include "nfstrace.h"
41
42	#define NFSDBG_FACILITY NFSDBG_PAGECACHE
43
44	#define MIN_POOL_WRITE (32)
45	#define MIN_POOL_COMMIT (4)
46
47	struct nfs_io_completion {
48	void (*complete)(void *data);
49	void *data;
50	struct kref refcount;
51	};
52
53	/*
54	* Local function declarations
55	*/
56	static void nfs_redirty_request(struct nfs_page *req);
57	static const struct rpc_call_ops nfs_commit_ops;
58	static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
59	static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
60	static const struct nfs_rw_ops nfs_rw_write_ops;
61	static void nfs_inode_remove_request(struct nfs_page *req);
62	static void nfs_clear_request_commit(struct nfs_commit_info *cinfo,
63	struct nfs_page *req);
64	static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
65	struct inode *inode);
66
67	static struct kmem_cache *nfs_wdata_cachep;
68	static mempool_t *nfs_wdata_mempool;
69	static struct kmem_cache *nfs_cdata_cachep;
70	static mempool_t *nfs_commit_mempool;
71
72	struct nfs_commit_data *nfs_commitdata_alloc(void)
73	{
74	struct nfs_commit_data *p;
75
76	p = kmem_cache_zalloc(nfs_cdata_cachep, nfs_io_gfp_mask());
77	if (!p) {
78	p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
79	if (!p)
80	return NULL;
81	memset(p, 0, sizeof(*p));
82	}
83	INIT_LIST_HEAD(list: &p->pages);
84	return p;
85	}
86	EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
87
88	void nfs_commit_free(struct nfs_commit_data *p)
89	{
90	mempool_free(element: p, pool: nfs_commit_mempool);
91	}
92	EXPORT_SYMBOL_GPL(nfs_commit_free);
93
94	static struct nfs_pgio_header *nfs_writehdr_alloc(void)
95	{
96	struct nfs_pgio_header *p;
97
98	p = kmem_cache_zalloc(nfs_wdata_cachep, nfs_io_gfp_mask());
99	if (!p) {
100	p = mempool_alloc(nfs_wdata_mempool, GFP_NOWAIT);
101	if (!p)
102	return NULL;
103	memset(p, 0, sizeof(*p));
104	}
105	p->rw_mode = FMODE_WRITE;
106	return p;
107	}
108
109	static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
110	{
111	mempool_free(element: hdr, pool: nfs_wdata_mempool);
112	}
113
114	static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
115	{
116	return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
117	}
118
119	static void nfs_io_completion_init(struct nfs_io_completion *ioc,
120	void (*complete)(void *), void *data)
121	{
122	ioc->complete = complete;
123	ioc->data = data;
124	kref_init(kref: &ioc->refcount);
125	}
126
127	static void nfs_io_completion_release(struct kref *kref)
128	{
129	struct nfs_io_completion *ioc = container_of(kref,
130	struct nfs_io_completion, refcount);
131	ioc->complete(ioc->data);
132	kfree(objp: ioc);
133	}
134
135	static void nfs_io_completion_get(struct nfs_io_completion *ioc)
136	{
137	if (ioc != NULL)
138	kref_get(kref: &ioc->refcount);
139	}
140
141	static void nfs_io_completion_put(struct nfs_io_completion *ioc)
142	{
143	if (ioc != NULL)
144	kref_put(kref: &ioc->refcount, release: nfs_io_completion_release);
145	}
146
147	static void
148	nfs_page_set_inode_ref(struct nfs_page *req, struct inode *inode)
149	{
150	if (!test_and_set_bit(nr: PG_INODE_REF, addr: &req->wb_flags)) {
151	kref_get(kref: &req->wb_kref);
152	atomic_long_inc(v: &NFS_I(inode)->nrequests);
153	}
154	}
155
156	static void nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode)
157	{
158	if (test_and_clear_bit(nr: PG_REMOVE, addr: &req->wb_flags))
159	nfs_page_set_inode_ref(req, inode);
160	}
161
162	/**
163	* nfs_folio_find_head_request - find head request associated with a folio
164	* @folio: pointer to folio
165	*
166	* must be called while holding the inode lock.
167	*
168	* returns matching head request with reference held, or NULL if not found.
169	*/
170	static struct nfs_page *nfs_folio_find_head_request(struct folio *folio)
171	{
172	struct address_space *mapping = folio->mapping;
173	struct nfs_page *req;
174
175	if (!folio_test_private(folio))
176	return NULL;
177	spin_lock(lock: &mapping->i_private_lock);
178	req = folio->private;
179	if (req) {
180	WARN_ON_ONCE(req->wb_head != req);
181	kref_get(kref: &req->wb_kref);
182	}
183	spin_unlock(lock: &mapping->i_private_lock);
184	return req;
185	}
186
187	/* Adjust the file length if we're writing beyond the end */
188	static void nfs_grow_file(struct folio *folio, unsigned int offset,
189	unsigned int count)
190	{
191	struct inode *inode = folio->mapping->host;
192	loff_t end, i_size;
193	pgoff_t end_index;
194
195	spin_lock(lock: &inode->i_lock);
196	i_size = i_size_read(inode);
197	end_index = ((i_size - 1) >> folio_shift(folio)) << folio_order(folio);
198	if (i_size > 0 && folio->index < end_index)
199	goto out;
200	end = folio_pos(folio) + (loff_t)offset + (loff_t)count;
201	if (i_size >= end)
202	goto out;
203	trace_nfs_size_grow(inode, new_size: end);
204	i_size_write(inode, i_size: end);
205	NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
206	nfs_inc_stats(inode, stat: NFSIOS_EXTENDWRITE);
207	out:
208	/* Atomically update timestamps if they are delegated to us. */
209	nfs_update_delegated_mtime_locked(inode);
210	spin_unlock(lock: &inode->i_lock);
211	nfs_fscache_invalidate(inode, flags: 0);
212	}
213
214	/* A writeback failed: mark the page as bad, and invalidate the page cache */
215	static void nfs_set_pageerror(struct address_space *mapping)
216	{
217	struct inode *inode = mapping->host;
218
219	nfs_zap_mapping(inode: mapping->host, mapping);
220	/* Force file size revalidation */
221	spin_lock(lock: &inode->i_lock);
222	nfs_set_cache_invalid(inode, NFS_INO_REVAL_FORCED |
223	NFS_INO_INVALID_CHANGE |
224	NFS_INO_INVALID_SIZE);
225	spin_unlock(lock: &inode->i_lock);
226	}
227
228	static void nfs_mapping_set_error(struct folio *folio, int error)
229	{
230	struct address_space *mapping = folio->mapping;
231
232	filemap_set_wb_err(mapping, err: error);
233	if (mapping->host)
234	errseq_set(eseq: &mapping->host->i_sb->s_wb_err,
235	err: error == -ENOSPC ? -ENOSPC : -EIO);
236	nfs_set_pageerror(mapping);
237	}
238
239	/*
240	* nfs_page_covers_folio
241	* @req: struct nfs_page
242	*
243	* Return true if the request covers the whole folio.
244	* Note that the caller should ensure all subrequests have been joined
245	*/
246	static bool nfs_page_group_covers_page(struct nfs_page *req)
247	{
248	unsigned int len = nfs_folio_length(folio: nfs_page_to_folio(req));
249
250	return req->wb_pgbase == 0 && req->wb_bytes == len;
251	}
252
253	/* We can set the PG_uptodate flag if we see that a write request
254	* covers the full page.
255	*/
256	static void nfs_mark_uptodate(struct nfs_page *req)
257	{
258	struct folio *folio = nfs_page_to_folio(req);
259
260	if (folio_test_uptodate(folio))
261	return;
262	if (!nfs_page_group_covers_page(req))
263	return;
264	folio_mark_uptodate(folio);
265	}
266
267	static int wb_priority(struct writeback_control *wbc)
268	{
269	int ret = 0;
270
271	if (wbc->sync_mode == WB_SYNC_ALL)
272	ret = FLUSH_COND_STABLE;
273	return ret;
274	}
275
276	/*
277	* NFS congestion control
278	*/
279
280	int nfs_congestion_kb;
281
282	#define NFS_CONGESTION_ON_THRESH (nfs_congestion_kb >> (PAGE_SHIFT-10))
283	#define NFS_CONGESTION_OFF_THRESH \
284	(NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
285
286	static void nfs_folio_set_writeback(struct folio *folio)
287	{
288	struct nfs_server *nfss = NFS_SERVER(inode: folio->mapping->host);
289
290	folio_start_writeback(folio);
291	if (atomic_long_inc_return(v: &nfss->writeback) > NFS_CONGESTION_ON_THRESH)
292	nfss->write_congested = 1;
293	}
294
295	static void nfs_folio_end_writeback(struct folio *folio)
296	{
297	struct nfs_server *nfss = NFS_SERVER(inode: folio->mapping->host);
298
299	folio_end_writeback_no_dropbehind(folio);
300	if (atomic_long_dec_return(v: &nfss->writeback) <
301	NFS_CONGESTION_OFF_THRESH) {
302	nfss->write_congested = 0;
303	wake_up_all(&nfss->write_congestion_wait);
304	}
305	}
306
307	static void nfs_page_end_writeback(struct nfs_page *req)
308	{
309	if (nfs_page_group_sync_on_bit(req, PG_WB_END)) {
310	nfs_unlock_request(req);
311	nfs_folio_end_writeback(folio: nfs_page_to_folio(req));
312	} else
313	nfs_unlock_request(req);
314	}
315
316	/*
317	* nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
318	*
319	* @destroy_list - request list (using wb_this_page) terminated by @old_head
320	* @old_head - the old head of the list
321	*
322	* All subrequests must be locked and removed from all lists, so at this point
323	* they are only "active" in this function, and possibly in nfs_wait_on_request
324	* with a reference held by some other context.
325	*/
326	static void
327	nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
328	struct nfs_page *old_head,
329	struct inode *inode)
330	{
331	while (destroy_list) {
332	struct nfs_page *subreq = destroy_list;
333
334	destroy_list = (subreq->wb_this_page == old_head) ?
335	NULL : subreq->wb_this_page;
336
337	/* Note: lock subreq in order to change subreq->wb_head */
338	nfs_page_set_headlock(req: subreq);
339	WARN_ON_ONCE(old_head != subreq->wb_head);
340
341	/* make sure old group is not used */
342	subreq->wb_this_page = subreq;
343	subreq->wb_head = subreq;
344
345	clear_bit(nr: PG_REMOVE, addr: &subreq->wb_flags);
346
347	/* Note: races with nfs_page_group_destroy() */
348	if (!kref_read(kref: &subreq->wb_kref)) {
349	/* Check if we raced with nfs_page_group_destroy() */
350	if (test_and_clear_bit(nr: PG_TEARDOWN, addr: &subreq->wb_flags)) {
351	nfs_page_clear_headlock(req: subreq);
352	nfs_free_request(req: subreq);
353	} else
354	nfs_page_clear_headlock(req: subreq);
355	continue;
356	}
357	nfs_page_clear_headlock(req: subreq);
358
359	nfs_release_request(old_head);
360
361	if (test_and_clear_bit(nr: PG_INODE_REF, addr: &subreq->wb_flags)) {
362	nfs_release_request(subreq);
363	atomic_long_dec(v: &NFS_I(inode)->nrequests);
364	}
365
366	/* subreq is now totally disconnected from page group or any
367	* write / commit lists. last chance to wake any waiters */
368	nfs_unlock_and_release_request(subreq);
369	}
370	}
371
372	/*
373	* nfs_join_page_group - destroy subrequests of the head req
374	* @head: the page used to lookup the "page group" of nfs_page structures
375	* @inode: Inode to which the request belongs.
376	*
377	* This function joins all sub requests to the head request by first
378	* locking all requests in the group, cancelling any pending operations
379	* and finally updating the head request to cover the whole range covered by
380	* the (former) group. All subrequests are removed from any write or commit
381	* lists, unlinked from the group and destroyed.
382	*/
383	void nfs_join_page_group(struct nfs_page *head, struct nfs_commit_info *cinfo,
384	struct inode *inode)
385	{
386	struct nfs_page *subreq;
387	struct nfs_page *destroy_list = NULL;
388	unsigned int pgbase, off, bytes;
389
390	pgbase = head->wb_pgbase;
391	bytes = head->wb_bytes;
392	off = head->wb_offset;
393	for (subreq = head->wb_this_page; subreq != head;
394	subreq = subreq->wb_this_page) {
395	/* Subrequests should always form a contiguous range */
396	if (pgbase > subreq->wb_pgbase) {
397	off -= pgbase - subreq->wb_pgbase;
398	bytes += pgbase - subreq->wb_pgbase;
399	pgbase = subreq->wb_pgbase;
400	}
401	bytes = max(subreq->wb_pgbase + subreq->wb_bytes
402	- pgbase, bytes);
403	}
404
405	/* Set the head request's range to cover the former page group */
406	head->wb_pgbase = pgbase;
407	head->wb_bytes = bytes;
408	head->wb_offset = off;
409
410	/* Now that all requests are locked, make sure they aren't on any list.
411	* Commit list removal accounting is done after locks are dropped */
412	subreq = head;
413	do {
414	nfs_clear_request_commit(cinfo, req: subreq);
415	subreq = subreq->wb_this_page;
416	} while (subreq != head);
417
418	/* unlink subrequests from head, destroy them later */
419	if (head->wb_this_page != head) {
420	/* destroy list will be terminated by head */
421	destroy_list = head->wb_this_page;
422	head->wb_this_page = head;
423	}
424
425	nfs_destroy_unlinked_subrequests(destroy_list, old_head: head, inode);
426	}
427
428	/**
429	* nfs_wait_on_request - Wait for a request to complete.
430	* @req: request to wait upon.
431	*
432	* Interruptible by fatal signals only.
433	* The user is responsible for holding a count on the request.
434	*/
435	static int nfs_wait_on_request(struct nfs_page *req)
436	{
437	if (!test_bit(PG_BUSY, &req->wb_flags))
438	return 0;
439	set_bit(nr: PG_CONTENDED2, addr: &req->wb_flags);
440	smp_mb__after_atomic();
441	return wait_on_bit_io(word: &req->wb_flags, bit: PG_BUSY,
442	TASK_UNINTERRUPTIBLE);
443	}
444
445	/*
446	* nfs_unroll_locks - unlock all newly locked reqs and wait on @req
447	* @head: head request of page group, must be holding head lock
448	* @req: request that couldn't lock and needs to wait on the req bit lock
449	*
450	* This is a helper function for nfs_lock_and_join_requests
451	* returns 0 on success, < 0 on error.
452	*/
453	static void
454	nfs_unroll_locks(struct nfs_page *head, struct nfs_page *req)
455	{
456	struct nfs_page *tmp;
457
458	/* relinquish all the locks successfully grabbed this run */
459	for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
460	if (!kref_read(kref: &tmp->wb_kref))
461	continue;
462	nfs_unlock_and_release_request(tmp);
463	}
464	}
465
466	/*
467	* nfs_page_group_lock_subreq - try to lock a subrequest
468	* @head: head request of page group
469	* @subreq: request to lock
470	*
471	* This is a helper function for nfs_lock_and_join_requests which
472	* must be called with the head request and page group both locked.
473	* On error, it returns with the page group unlocked.
474	*/
475	static int
476	nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
477	{
478	int ret;
479
480	if (!kref_get_unless_zero(kref: &subreq->wb_kref))
481	return 0;
482	while (!nfs_lock_request(req: subreq)) {
483	nfs_page_group_unlock(head);
484	ret = nfs_wait_on_request(req: subreq);
485	if (!ret)
486	ret = nfs_page_group_lock(head);
487	if (ret < 0) {
488	nfs_unroll_locks(head, req: subreq);
489	nfs_release_request(subreq);
490	return ret;
491	}
492	}
493	return 0;
494	}
495
496	/*
497	* nfs_lock_and_join_requests - join all subreqs to the head req
498	* @folio: the folio used to lookup the "page group" of nfs_page structures
499	*
500	* This function joins all sub requests to the head request by first
501	* locking all requests in the group, cancelling any pending operations
502	* and finally updating the head request to cover the whole range covered by
503	* the (former) group. All subrequests are removed from any write or commit
504	* lists, unlinked from the group and destroyed.
505	*
506	* Returns a locked, referenced pointer to the head request - which after
507	* this call is guaranteed to be the only request associated with the page.
508	* Returns NULL if no requests are found for @folio, or a ERR_PTR if an
509	* error was encountered.
510	*/
511	static struct nfs_page *nfs_lock_and_join_requests(struct folio *folio)
512	{
513	struct inode *inode = folio->mapping->host;
514	struct nfs_page *head, *subreq;
515	struct nfs_commit_info cinfo;
516	int ret;
517
518	/*
519	* A reference is taken only on the head request which acts as a
520	* reference to the whole page group - the group will not be destroyed
521	* until the head reference is released.
522	*/
523	retry:
524	head = nfs_folio_find_head_request(folio);
525	if (!head)
526	return NULL;
527
528	while (!nfs_lock_request(req: head)) {
529	ret = nfs_wait_on_request(req: head);
530	if (ret < 0) {
531	nfs_release_request(head);
532	return ERR_PTR(error: ret);
533	}
534	}
535
536	ret = nfs_page_group_lock(head);
537	if (ret < 0)
538	goto out_unlock;
539
540	/* Ensure that nobody removed the request before we locked it */
541	if (head != folio->private) {
542	nfs_page_group_unlock(head);
543	nfs_unlock_and_release_request(head);
544	goto retry;
545	}
546
547	nfs_cancel_remove_inode(req: head, inode);
548
549	/* lock each request in the page group */
550	for (subreq = head->wb_this_page;
551	subreq != head;
552	subreq = subreq->wb_this_page) {
553	ret = nfs_page_group_lock_subreq(head, subreq);
554	if (ret < 0)
555	goto out_unlock;
556	}
557
558	nfs_page_group_unlock(head);
559
560	nfs_init_cinfo_from_inode(cinfo: &cinfo, inode);
561	nfs_join_page_group(head, cinfo: &cinfo, inode);
562	return head;
563
564	out_unlock:
565	nfs_unlock_and_release_request(head);
566	return ERR_PTR(error: ret);
567	}
568
569	static void nfs_write_error(struct nfs_page *req, int error)
570	{
571	trace_nfs_write_error(inode: nfs_page_to_inode(req), req, error);
572	nfs_mapping_set_error(folio: nfs_page_to_folio(req), error);
573	nfs_inode_remove_request(req);
574	nfs_page_end_writeback(req);
575	nfs_release_request(req);
576	}
577
578	/*
579	* Find an associated nfs write request, and prepare to flush it out
580	* May return an error if the user signalled nfs_wait_on_request().
581	*/
582	static int nfs_do_writepage(struct folio *folio, struct writeback_control *wbc,
583	struct nfs_pageio_descriptor *pgio)
584	{
585	struct nfs_page *req;
586	int ret;
587
588	nfs_pageio_cond_complete(pgio, folio->index);
589
590	req = nfs_lock_and_join_requests(folio);
591	if (!req)
592	return 0;
593	if (IS_ERR(ptr: req))
594	return PTR_ERR(ptr: req);
595
596	trace_nfs_do_writepage(req);
597	nfs_folio_set_writeback(folio);
598	WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
599
600	/* If there is a fatal error that covers this write, just exit */
601	ret = pgio->pg_error;
602	if (nfs_error_is_fatal_on_server(err: ret))
603	goto out_launder;
604
605	if (!nfs_pageio_add_request(pgio, req)) {
606	ret = pgio->pg_error;
607	/*
608	* Remove the problematic req upon fatal errors on the server
609	*/
610	if (nfs_error_is_fatal_on_server(err: ret))
611	goto out_launder;
612	folio_redirty_for_writepage(wbc, folio);
613	nfs_redirty_request(req);
614	pgio->pg_error = 0;
615	return ret;
616	}
617
618	nfs_add_stats(inode: folio->mapping->host, stat: NFSIOS_WRITEPAGES, addend: 1);
619	return 0;
620
621	out_launder:
622	nfs_write_error(req, error: ret);
623	return 0;
624	}
625
626	/*
627	* Write an mmapped page to the server.
628	*/
629	static int nfs_writepage_locked(struct folio *folio,
630	struct writeback_control *wbc)
631	{
632	struct nfs_pageio_descriptor pgio;
633	struct inode *inode = folio->mapping->host;
634	int err;
635
636	nfs_inc_stats(inode, stat: NFSIOS_VFSWRITEPAGE);
637	nfs_pageio_init_write(pgio: &pgio, inode, ioflags: 0, force_mds: false,
638	compl_ops: &nfs_async_write_completion_ops);
639	err = nfs_do_writepage(folio, wbc, pgio: &pgio);
640	pgio.pg_error = 0;
641	nfs_pageio_complete(desc: &pgio);
642	return err;
643	}
644
645	static void nfs_io_completion_commit(void *inode)
646	{
647	nfs_commit_inode(inode, 0);
648	}
649
650	int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
651	{
652	struct inode *inode = mapping->host;
653	struct nfs_pageio_descriptor pgio;
654	struct nfs_io_completion *ioc = NULL;
655	unsigned int mntflags = NFS_SERVER(inode)->flags;
656	struct nfs_server *nfss = NFS_SERVER(inode);
657	int priority = 0;
658	int err;
659
660	trace_nfs_writepages(inode, offset: wbc->range_start, count: wbc->range_end - wbc->range_start);
661
662	/* Wait with writeback until write congestion eases */
663	if (wbc->sync_mode == WB_SYNC_NONE && nfss->write_congested) {
664	err = wait_event_killable(nfss->write_congestion_wait,
665	nfss->write_congested == 0);
666	if (err)
667	goto out_err;
668	}
669
670	nfs_inc_stats(inode, stat: NFSIOS_VFSWRITEPAGES);
671
672	if (!(mntflags & NFS_MOUNT_WRITE_EAGER) || wbc->for_kupdate ||
673	wbc->for_background || wbc->for_sync) {
674	ioc = nfs_io_completion_alloc(GFP_KERNEL);
675	if (ioc)
676	nfs_io_completion_init(ioc, complete: nfs_io_completion_commit,
677	data: inode);
678	priority = wb_priority(wbc);
679	}
680
681	do {
682	struct folio *folio = NULL;
683
684	nfs_pageio_init_write(pgio: &pgio, inode, ioflags: priority, force_mds: false,
685	compl_ops: &nfs_async_write_completion_ops);
686	pgio.pg_io_completion = ioc;
687	while ((folio = writeback_iter(mapping, wbc, folio, error: &err))) {
688	err = nfs_do_writepage(folio, wbc, pgio: &pgio);
689	folio_unlock(folio);
690	}
691	pgio.pg_error = 0;
692	nfs_pageio_complete(desc: &pgio);
693	if (err == -EAGAIN && mntflags & NFS_MOUNT_SOFTERR)
694	break;
695	} while (err < 0 && !nfs_error_is_fatal(err));
696	nfs_io_completion_put(ioc);
697
698	if (err > 0)
699	err = 0;
700	out_err:
701	trace_nfs_writepages_done(inode, offset: wbc->range_start, count: wbc->range_end - wbc->range_start, ret: err);
702	return err;
703	}
704
705	/*
706	* Insert a write request into an inode
707	*/
708	static void nfs_inode_add_request(struct nfs_page *req)
709	{
710	struct folio *folio = nfs_page_to_folio(req);
711	struct address_space *mapping = folio->mapping;
712	struct nfs_inode *nfsi = NFS_I(inode: mapping->host);
713
714	WARN_ON_ONCE(req->wb_this_page != req);
715
716	/* Lock the request! */
717	nfs_lock_request(req);
718	spin_lock(lock: &mapping->i_private_lock);
719	set_bit(nr: PG_MAPPED, addr: &req->wb_flags);
720	folio_set_private(folio);
721	folio->private = req;
722	spin_unlock(lock: &mapping->i_private_lock);
723	atomic_long_inc(v: &nfsi->nrequests);
724	/* this a head request for a page group - mark it as having an
725	* extra reference so sub groups can follow suit.
726	* This flag also informs pgio layer when to bump nrequests when
727	* adding subrequests. */
728	WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
729	kref_get(kref: &req->wb_kref);
730	}
731
732	/*
733	* Remove a write request from an inode
734	*/
735	static void nfs_inode_remove_request(struct nfs_page *req)
736	{
737	struct nfs_inode *nfsi = NFS_I(inode: nfs_page_to_inode(req));
738
739	nfs_page_group_lock(req);
740	if (nfs_page_group_sync_on_bit_locked(req, PG_REMOVE)) {
741	struct folio *folio = nfs_page_to_folio(req: req->wb_head);
742	struct address_space *mapping = folio->mapping;
743
744	spin_lock(lock: &mapping->i_private_lock);
745	if (likely(folio)) {
746	folio->private = NULL;
747	folio_clear_private(folio);
748	clear_bit(nr: PG_MAPPED, addr: &req->wb_head->wb_flags);
749	}
750	spin_unlock(lock: &mapping->i_private_lock);
751
752	folio_end_dropbehind(folio);
753	}
754	nfs_page_group_unlock(req);
755
756	if (test_and_clear_bit(nr: PG_INODE_REF, addr: &req->wb_flags)) {
757	atomic_long_dec(v: &nfsi->nrequests);
758	nfs_release_request(req);
759	}
760	}
761
762	static void nfs_mark_request_dirty(struct nfs_page *req)
763	{
764	struct folio *folio = nfs_page_to_folio(req);
765	if (folio)
766	filemap_dirty_folio(mapping: folio_mapping(folio), folio);
767	}
768
769	/**
770	* nfs_request_add_commit_list_locked - add request to a commit list
771	* @req: pointer to a struct nfs_page
772	* @dst: commit list head
773	* @cinfo: holds list lock and accounting info
774	*
775	* This sets the PG_CLEAN bit, updates the cinfo count of
776	* number of outstanding requests requiring a commit as well as
777	* the MM page stats.
778	*
779	* The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
780	* nfs_page lock.
781	*/
782	void
783	nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
784	struct nfs_commit_info *cinfo)
785	{
786	set_bit(nr: PG_CLEAN, addr: &req->wb_flags);
787	nfs_list_add_request(req, head: dst);
788	atomic_long_inc(v: &cinfo->mds->ncommit);
789	}
790	EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
791
792	/**
793	* nfs_request_add_commit_list - add request to a commit list
794	* @req: pointer to a struct nfs_page
795	* @cinfo: holds list lock and accounting info
796	*
797	* This sets the PG_CLEAN bit, updates the cinfo count of
798	* number of outstanding requests requiring a commit as well as
799	* the MM page stats.
800	*
801	* The caller must _not_ hold the cinfo->lock, but must be
802	* holding the nfs_page lock.
803	*/
804	void
805	nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
806	{
807	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
808	nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
809	mutex_unlock(lock: &NFS_I(inode: cinfo->inode)->commit_mutex);
810	nfs_folio_mark_unstable(folio: nfs_page_to_folio(req), cinfo);
811	}
812	EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
813
814	/**
815	* nfs_request_remove_commit_list - Remove request from a commit list
816	* @req: pointer to a nfs_page
817	* @cinfo: holds list lock and accounting info
818	*
819	* This clears the PG_CLEAN bit, and updates the cinfo's count of
820	* number of outstanding requests requiring a commit
821	* It does not update the MM page stats.
822	*
823	* The caller _must_ hold the cinfo->lock and the nfs_page lock.
824	*/
825	void
826	nfs_request_remove_commit_list(struct nfs_page *req,
827	struct nfs_commit_info *cinfo)
828	{
829	if (!test_and_clear_bit(nr: PG_CLEAN, addr: &(req)->wb_flags))
830	return;
831	nfs_list_remove_request(req);
832	atomic_long_dec(v: &cinfo->mds->ncommit);
833	}
834	EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
835
836	static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
837	struct inode *inode)
838	{
839	cinfo->inode = inode;
840	cinfo->mds = &NFS_I(inode)->commit_info;
841	cinfo->ds = pnfs_get_ds_info(inode);
842	cinfo->dreq = NULL;
843	cinfo->completion_ops = &nfs_commit_completion_ops;
844	}
845
846	void nfs_init_cinfo(struct nfs_commit_info *cinfo,
847	struct inode *inode,
848	struct nfs_direct_req *dreq)
849	{
850	if (dreq)
851	nfs_init_cinfo_from_dreq(cinfo, dreq);
852	else
853	nfs_init_cinfo_from_inode(cinfo, inode);
854	}
855	EXPORT_SYMBOL_GPL(nfs_init_cinfo);
856
857	/*
858	* Add a request to the inode's commit list.
859	*/
860	void
861	nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
862	struct nfs_commit_info *cinfo, u32 ds_commit_idx)
863	{
864	if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
865	return;
866	nfs_request_add_commit_list(req, cinfo);
867	}
868
869	static void nfs_folio_clear_commit(struct folio *folio)
870	{
871	if (folio) {
872	long nr = folio_nr_pages(folio);
873
874	node_stat_mod_folio(folio, item: NR_WRITEBACK, nr: -nr);
875	wb_stat_mod(wb: &inode_to_bdi(inode: folio->mapping->host)->wb,
876	item: WB_WRITEBACK, amount: -nr);
877	}
878	}
879
880	/* Called holding the request lock on @req */
881	static void nfs_clear_request_commit(struct nfs_commit_info *cinfo,
882	struct nfs_page *req)
883	{
884	if (test_bit(PG_CLEAN, &req->wb_flags)) {
885	struct nfs_open_context *ctx = nfs_req_openctx(req);
886	struct inode *inode = d_inode(dentry: ctx->dentry);
887
888	mutex_lock(&NFS_I(inode)->commit_mutex);
889	if (!pnfs_clear_request_commit(req, cinfo)) {
890	nfs_request_remove_commit_list(req, cinfo);
891	}
892	mutex_unlock(lock: &NFS_I(inode)->commit_mutex);
893	nfs_folio_clear_commit(folio: nfs_page_to_folio(req));
894	}
895	}
896
897	int nfs_write_need_commit(struct nfs_pgio_header *hdr)
898	{
899	if (hdr->verf.committed == NFS_DATA_SYNC)
900	return hdr->lseg == NULL;
901	return hdr->verf.committed != NFS_FILE_SYNC;
902	}
903
904	static void nfs_async_write_init(struct nfs_pgio_header *hdr)
905	{
906	nfs_io_completion_get(ioc: hdr->io_completion);
907	}
908
909	static void nfs_write_completion(struct nfs_pgio_header *hdr)
910	{
911	struct nfs_commit_info cinfo;
912	unsigned long bytes = 0;
913
914	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
915	goto out;
916	nfs_init_cinfo_from_inode(cinfo: &cinfo, inode: hdr->inode);
917	while (!list_empty(head: &hdr->pages)) {
918	struct nfs_page *req = nfs_list_entry(head: hdr->pages.next);
919
920	bytes += req->wb_bytes;
921	nfs_list_remove_request(req);
922	if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
923	(hdr->good_bytes < bytes)) {
924	trace_nfs_comp_error(inode: hdr->inode, req, error: hdr->error);
925	nfs_mapping_set_error(folio: nfs_page_to_folio(req),
926	error: hdr->error);
927	goto remove_req;
928	}
929	if (nfs_write_need_commit(hdr)) {
930	/* Reset wb_nio, since the write was successful. */
931	req->wb_nio = 0;
932	memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
933	nfs_mark_request_commit(req, lseg: hdr->lseg, cinfo: &cinfo,
934	ds_commit_idx: hdr->ds_commit_idx);
935	goto next;
936	}
937	remove_req:
938	nfs_inode_remove_request(req);
939	next:
940	nfs_page_end_writeback(req);
941	nfs_release_request(req);
942	}
943	out:
944	nfs_io_completion_put(ioc: hdr->io_completion);
945	hdr->release(hdr);
946	}
947
948	unsigned long
949	nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
950	{
951	return atomic_long_read(v: &cinfo->mds->ncommit);
952	}
953
954	/* NFS_I(cinfo->inode)->commit_mutex held by caller */
955	int
956	nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
957	struct nfs_commit_info *cinfo, int max)
958	{
959	struct nfs_page *req, *tmp;
960	int ret = 0;
961
962	list_for_each_entry_safe(req, tmp, src, wb_list) {
963	kref_get(kref: &req->wb_kref);
964	if (!nfs_lock_request(req)) {
965	nfs_release_request(req);
966	continue;
967	}
968	nfs_request_remove_commit_list(req, cinfo);
969	clear_bit(nr: PG_COMMIT_TO_DS, addr: &req->wb_flags);
970	nfs_list_add_request(req, head: dst);
971	ret++;
972	if ((ret == max) && !cinfo->dreq)
973	break;
974	cond_resched();
975	}
976	return ret;
977	}
978	EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
979
980	/*
981	* nfs_scan_commit - Scan an inode for commit requests
982	* @inode: NFS inode to scan
983	* @dst: mds destination list
984	* @cinfo: mds and ds lists of reqs ready to commit
985	*
986	* Moves requests from the inode's 'commit' request list.
987	* The requests are *not* checked to ensure that they form a contiguous set.
988	*/
989	int
990	nfs_scan_commit(struct inode *inode, struct list_head *dst,
991	struct nfs_commit_info *cinfo)
992	{
993	int ret = 0;
994
995	if (!atomic_long_read(v: &cinfo->mds->ncommit))
996	return 0;
997	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
998	if (atomic_long_read(v: &cinfo->mds->ncommit) > 0) {
999	const int max = INT_MAX;
1000
1001	ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1002	cinfo, max);
1003	ret += pnfs_scan_commit_lists(inode, cinfo, max: max - ret);
1004	}
1005	mutex_unlock(lock: &NFS_I(inode: cinfo->inode)->commit_mutex);
1006	return ret;
1007	}
1008
1009	/*
1010	* Search for an existing write request, and attempt to update
1011	* it to reflect a new dirty region on a given page.
1012	*
1013	* If the attempt fails, then the existing request is flushed out
1014	* to disk.
1015	*/
1016	static struct nfs_page *nfs_try_to_update_request(struct folio *folio,
1017	unsigned int offset,
1018	unsigned int bytes)
1019	{
1020	struct nfs_page *req;
1021	unsigned int rqend;
1022	unsigned int end;
1023	int error;
1024
1025	trace_nfs_try_to_update_request(inode: folio_inode(folio), offset, count: bytes);
1026	end = offset + bytes;
1027
1028	req = nfs_lock_and_join_requests(folio);
1029	if (IS_ERR_OR_NULL(ptr: req))
1030	goto out;
1031
1032	rqend = req->wb_offset + req->wb_bytes;
1033	/*
1034	* Tell the caller to flush out the request if
1035	* the offsets are non-contiguous.
1036	* Note: nfs_flush_incompatible() will already
1037	* have flushed out requests having wrong owners.
1038	*/
1039	if (offset > rqend || end < req->wb_offset)
1040	goto out_flushme;
1041
1042	/* Okay, the request matches. Update the region */
1043	if (offset < req->wb_offset) {
1044	req->wb_offset = offset;
1045	req->wb_pgbase = offset;
1046	}
1047	if (end > rqend)
1048	req->wb_bytes = end - req->wb_offset;
1049	else
1050	req->wb_bytes = rqend - req->wb_offset;
1051	req->wb_nio = 0;
1052	out:
1053	trace_nfs_try_to_update_request_done(inode: folio_inode(folio), offset, count: bytes,
1054	ret: PTR_ERR_OR_ZERO(ptr: req));
1055	return req;
1056	out_flushme:
1057	/*
1058	* Note: we mark the request dirty here because
1059	* nfs_lock_and_join_requests() cannot preserve
1060	* commit flags, so we have to replay the write.
1061	*/
1062	nfs_mark_request_dirty(req);
1063	nfs_unlock_and_release_request(req);
1064	error = nfs_wb_folio(inode: folio->mapping->host, folio);
1065	trace_nfs_try_to_update_request_done(inode: folio_inode(folio), offset, count: bytes, ret: error);
1066	return (error < 0) ? ERR_PTR(error) : NULL;
1067	}
1068
1069	/*
1070	* Try to update an existing write request, or create one if there is none.
1071	*
1072	* Note: Should always be called with the Page Lock held to prevent races
1073	* if we have to add a new request. Also assumes that the caller has
1074	* already called nfs_flush_incompatible() if necessary.
1075	*/
1076	static struct nfs_page *nfs_setup_write_request(struct nfs_open_context *ctx,
1077	struct folio *folio,
1078	unsigned int offset,
1079	unsigned int bytes)
1080	{
1081	struct nfs_page *req;
1082
1083	req = nfs_try_to_update_request(folio, offset, bytes);
1084	if (req != NULL)
1085	goto out;
1086	req = nfs_page_create_from_folio(ctx, folio, offset, count: bytes);
1087	if (IS_ERR(ptr: req))
1088	goto out;
1089	nfs_inode_add_request(req);
1090	out:
1091	return req;
1092	}
1093
1094	static int nfs_writepage_setup(struct nfs_open_context *ctx,
1095	struct folio *folio, unsigned int offset,
1096	unsigned int count)
1097	{
1098	struct nfs_page *req;
1099
1100	req = nfs_setup_write_request(ctx, folio, offset, bytes: count);
1101	if (IS_ERR(ptr: req))
1102	return PTR_ERR(ptr: req);
1103	trace_nfs_writepage_setup(req);
1104	/* Update file length */
1105	nfs_grow_file(folio, offset, count);
1106	nfs_mark_uptodate(req);
1107	nfs_mark_request_dirty(req);
1108	nfs_unlock_and_release_request(req);
1109	return 0;
1110	}
1111
1112	int nfs_flush_incompatible(struct file *file, struct folio *folio)
1113	{
1114	struct nfs_open_context *ctx = nfs_file_open_context(filp: file);
1115	struct nfs_lock_context *l_ctx;
1116	struct file_lock_context *flctx = locks_inode_context(inode: file_inode(f: file));
1117	struct nfs_page *req;
1118	int do_flush, status;
1119	/*
1120	* Look for a request corresponding to this page. If there
1121	* is one, and it belongs to another file, we flush it out
1122	* before we try to copy anything into the page. Do this
1123	* due to the lack of an ACCESS-type call in NFSv2.
1124	* Also do the same if we find a request from an existing
1125	* dropped page.
1126	*/
1127	do {
1128	req = nfs_folio_find_head_request(folio);
1129	if (req == NULL)
1130	return 0;
1131	l_ctx = req->wb_lock_context;
1132	do_flush = nfs_page_to_folio(req) != folio ||
1133	!nfs_match_open_context(ctx1: nfs_req_openctx(req), ctx2: ctx);
1134	if (l_ctx && flctx &&
1135	!(list_empty_careful(head: &flctx->flc_posix) &&
1136	list_empty_careful(head: &flctx->flc_flock))) {
1137	do_flush |= l_ctx->lockowner != current->files;
1138	}
1139	nfs_release_request(req);
1140	if (!do_flush)
1141	return 0;
1142	status = nfs_wb_folio(inode: folio->mapping->host, folio);
1143	} while (status == 0);
1144	return status;
1145	}
1146
1147	/*
1148	* Avoid buffered writes when a open context credential's key would
1149	* expire soon.
1150	*
1151	* Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1152	*
1153	* Return 0 and set a credential flag which triggers the inode to flush
1154	* and performs NFS_FILE_SYNC writes if the key will expired within
1155	* RPC_KEY_EXPIRE_TIMEO.
1156	*/
1157	int
1158	nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1159	{
1160	struct nfs_open_context *ctx = nfs_file_open_context(filp);
1161
1162	if (nfs_ctx_key_to_expire(ctx, inode) &&
1163	!rcu_access_pointer(ctx->ll_cred))
1164	/* Already expired! */
1165	return -EACCES;
1166	return 0;
1167	}
1168
1169	/*
1170	* Test if the open context credential key is marked to expire soon.
1171	*/
1172	bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1173	{
1174	struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1175	struct rpc_cred *cred, *new, *old = NULL;
1176	struct auth_cred acred = {
1177	.cred = ctx->cred,
1178	};
1179	bool ret = false;
1180
1181	rcu_read_lock();
1182	cred = rcu_dereference(ctx->ll_cred);
1183	if (cred && !(cred->cr_ops->crkey_timeout &&
1184	cred->cr_ops->crkey_timeout(cred)))
1185	goto out;
1186	rcu_read_unlock();
1187
1188	new = auth->au_ops->lookup_cred(auth, &acred, 0);
1189	if (new == cred) {
1190	put_rpccred(new);
1191	return true;
1192	}
1193	if (IS_ERR_OR_NULL(ptr: new)) {
1194	new = NULL;
1195	ret = true;
1196	} else if (new->cr_ops->crkey_timeout &&
1197	new->cr_ops->crkey_timeout(new))
1198	ret = true;
1199
1200	rcu_read_lock();
1201	old = rcu_dereference_protected(xchg(&ctx->ll_cred,
1202	RCU_INITIALIZER(new)), 1);
1203	out:
1204	rcu_read_unlock();
1205	put_rpccred(old);
1206	return ret;
1207	}
1208
1209	/*
1210	* If the page cache is marked as unsafe or invalid, then we can't rely on
1211	* the PageUptodate() flag. In this case, we will need to turn off
1212	* write optimisations that depend on the page contents being correct.
1213	*/
1214	static bool nfs_folio_write_uptodate(struct folio *folio, unsigned int pagelen)
1215	{
1216	struct inode *inode = folio->mapping->host;
1217	struct nfs_inode *nfsi = NFS_I(inode);
1218
1219	if (nfs_have_delegated_attributes(inode))
1220	goto out;
1221	if (nfsi->cache_validity &
1222	(NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_SIZE))
1223	return false;
1224	smp_rmb();
1225	if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags) && pagelen != 0)
1226	return false;
1227	out:
1228	if (nfsi->cache_validity & NFS_INO_INVALID_DATA && pagelen != 0)
1229	return false;
1230	return folio_test_uptodate(folio) != 0;
1231	}
1232
1233	static bool
1234	is_whole_file_wrlock(struct file_lock *fl)
1235	{
1236	return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1237	lock_is_write(fl);
1238	}
1239
1240	/* If we know the page is up to date, and we're not using byte range locks (or
1241	* if we have the whole file locked for writing), it may be more efficient to
1242	* extend the write to cover the entire page in order to avoid fragmentation
1243	* inefficiencies.
1244	*
1245	* If the file is opened for synchronous writes then we can just skip the rest
1246	* of the checks.
1247	*/
1248	static int nfs_can_extend_write(struct file *file, struct folio *folio,
1249	unsigned int pagelen)
1250	{
1251	struct inode *inode = file_inode(f: file);
1252	struct file_lock_context *flctx = locks_inode_context(inode);
1253	struct file_lock *fl;
1254	int ret;
1255	unsigned int mntflags = NFS_SERVER(inode)->flags;
1256
1257	if (mntflags & NFS_MOUNT_NO_ALIGNWRITE)
1258	return 0;
1259	if (file->f_flags & O_DSYNC)
1260	return 0;
1261	if (!nfs_folio_write_uptodate(folio, pagelen))
1262	return 0;
1263	if (nfs_have_write_delegation(inode))
1264	return 1;
1265	if (!flctx || (list_empty_careful(head: &flctx->flc_flock) &&
1266	list_empty_careful(head: &flctx->flc_posix)))
1267	return 1;
1268
1269	/* Check to see if there are whole file write locks */
1270	ret = 0;
1271	spin_lock(lock: &flctx->flc_lock);
1272	if (!list_empty(head: &flctx->flc_posix)) {
1273	fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1274	c.flc_list);
1275	if (is_whole_file_wrlock(fl))
1276	ret = 1;
1277	} else if (!list_empty(head: &flctx->flc_flock)) {
1278	fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1279	c.flc_list);
1280	if (lock_is_write(fl))
1281	ret = 1;
1282	}
1283	spin_unlock(lock: &flctx->flc_lock);
1284	return ret;
1285	}
1286
1287	/*
1288	* Update and possibly write a cached page of an NFS file.
1289	*
1290	* XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1291	* things with a page scheduled for an RPC call (e.g. invalidate it).
1292	*/
1293	int nfs_update_folio(struct file *file, struct folio *folio,
1294	unsigned int offset, unsigned int count)
1295	{
1296	struct nfs_open_context *ctx = nfs_file_open_context(filp: file);
1297	struct address_space *mapping = folio->mapping;
1298	struct inode *inode = mapping->host;
1299	unsigned int pagelen = nfs_folio_length(folio);
1300	int status = 0;
1301
1302	nfs_inc_stats(inode, stat: NFSIOS_VFSUPDATEPAGE);
1303
1304	trace_nfs_update_folio(inode, offset, count);
1305
1306	dprintk("NFS: nfs_update_folio(%pD2 %d@%lld)\n", file, count,
1307	(long long)(folio_pos(folio) + offset));
1308
1309	if (!count)
1310	goto out;
1311
1312	if (nfs_can_extend_write(file, folio, pagelen)) {
1313	unsigned int end = count + offset;
1314
1315	offset = round_down(offset, PAGE_SIZE);
1316	if (end < pagelen)
1317	end = min(round_up(end, PAGE_SIZE), pagelen);
1318	count = end - offset;
1319	}
1320
1321	status = nfs_writepage_setup(ctx, folio, offset, count);
1322	if (status < 0)
1323	nfs_set_pageerror(mapping);
1324	out:
1325	trace_nfs_update_folio_done(inode, offset, count, ret: status);
1326	dprintk("NFS: nfs_update_folio returns %d (isize %lld)\n",
1327	status, (long long)i_size_read(inode));
1328	return status;
1329	}
1330
1331	static int flush_task_priority(int how)
1332	{
1333	switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1334	case FLUSH_HIGHPRI:
1335	return RPC_PRIORITY_HIGH;
1336	case FLUSH_LOWPRI:
1337	return RPC_PRIORITY_LOW;
1338	}
1339	return RPC_PRIORITY_NORMAL;
1340	}
1341
1342	static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1343	struct rpc_message *msg,
1344	const struct nfs_rpc_ops *rpc_ops,
1345	struct rpc_task_setup *task_setup_data, int how)
1346	{
1347	int priority = flush_task_priority(how);
1348
1349	if (IS_SWAPFILE(hdr->inode))
1350	task_setup_data->flags |= RPC_TASK_SWAPPER;
1351	task_setup_data->priority = priority;
1352	rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1353	trace_nfs_initiate_write(hdr);
1354	}
1355
1356	/* If a nfs_flush_* function fails, it should remove reqs from @head and
1357	* call this on each, which will prepare them to be retried on next
1358	* writeback using standard nfs.
1359	*/
1360	static void nfs_redirty_request(struct nfs_page *req)
1361	{
1362	struct nfs_inode *nfsi = NFS_I(inode: nfs_page_to_inode(req));
1363
1364	/* Bump the transmission count */
1365	req->wb_nio++;
1366	nfs_mark_request_dirty(req);
1367	atomic_long_inc(v: &nfsi->redirtied_pages);
1368	nfs_page_end_writeback(req);
1369	nfs_release_request(req);
1370	}
1371
1372	static void nfs_async_write_error(struct list_head *head, int error)
1373	{
1374	struct nfs_page *req;
1375
1376	while (!list_empty(head)) {
1377	req = nfs_list_entry(head: head->next);
1378	nfs_list_remove_request(req);
1379	if (nfs_error_is_fatal_on_server(err: error))
1380	nfs_write_error(req, error);
1381	else
1382	nfs_redirty_request(req);
1383	}
1384	}
1385
1386	static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1387	{
1388	nfs_async_write_error(head: &hdr->pages, error: 0);
1389	}
1390
1391	static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1392	.init_hdr = nfs_async_write_init,
1393	.error_cleanup = nfs_async_write_error,
1394	.completion = nfs_write_completion,
1395	.reschedule_io = nfs_async_write_reschedule_io,
1396	};
1397
1398	void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1399	struct inode *inode, int ioflags, bool force_mds,
1400	const struct nfs_pgio_completion_ops *compl_ops)
1401	{
1402	struct nfs_server *server = NFS_SERVER(inode);
1403	const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1404
1405	#ifdef CONFIG_NFS_V4_1
1406	if (server->pnfs_curr_ld && !force_mds)
1407	pg_ops = server->pnfs_curr_ld->pg_write_ops;
1408	#endif
1409	nfs_pageio_init(desc: pgio, inode, pg_ops, compl_ops, rw_ops: &nfs_rw_write_ops,
1410	bsize: server->wsize, how: ioflags);
1411	}
1412	EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1413
1414	void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1415	{
1416	struct nfs_pgio_mirror *mirror;
1417
1418	if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1419	pgio->pg_ops->pg_cleanup(pgio);
1420
1421	pgio->pg_ops = &nfs_pgio_rw_ops;
1422
1423	nfs_pageio_stop_mirroring(pgio);
1424
1425	mirror = &pgio->pg_mirrors[0];
1426	mirror->pg_bsize = NFS_SERVER(inode: pgio->pg_inode)->wsize;
1427	}
1428	EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1429
1430
1431	void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1432	{
1433	struct nfs_commit_data *data = calldata;
1434
1435	NFS_PROTO(inode: data->inode)->commit_rpc_prepare(task, data);
1436	}
1437
1438	static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1439	struct nfs_fattr *fattr)
1440	{
1441	struct nfs_pgio_args *argp = &hdr->args;
1442	struct nfs_pgio_res *resp = &hdr->res;
1443	u64 size = argp->offset + resp->count;
1444
1445	if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1446	fattr->size = size;
1447	if (nfs_size_to_loff_t(size: fattr->size) < i_size_read(inode: hdr->inode)) {
1448	fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1449	return;
1450	}
1451	if (size != fattr->size)
1452	return;
1453	/* Set attribute barrier */
1454	nfs_fattr_set_barrier(fattr);
1455	/* ...and update size */
1456	fattr->valid |= NFS_ATTR_FATTR_SIZE;
1457	}
1458
1459	void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1460	{
1461	struct nfs_fattr *fattr = &hdr->fattr;
1462	struct inode *inode = hdr->inode;
1463
1464	if (nfs_have_delegated_mtime(inode)) {
1465	spin_lock(lock: &inode->i_lock);
1466	nfs_set_cache_invalid(inode, NFS_INO_INVALID_BLOCKS);
1467	spin_unlock(lock: &inode->i_lock);
1468	return;
1469	}
1470
1471	spin_lock(lock: &inode->i_lock);
1472	nfs_writeback_check_extend(hdr, fattr);
1473	nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1474	spin_unlock(lock: &inode->i_lock);
1475	}
1476	EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1477
1478	/*
1479	* This function is called when the WRITE call is complete.
1480	*/
1481	static int nfs_writeback_done(struct rpc_task *task,
1482	struct nfs_pgio_header *hdr,
1483	struct inode *inode)
1484	{
1485	int status;
1486
1487	/*
1488	* ->write_done will attempt to use post-op attributes to detect
1489	* conflicting writes by other clients. A strict interpretation
1490	* of close-to-open would allow us to continue caching even if
1491	* another writer had changed the file, but some applications
1492	* depend on tighter cache coherency when writing.
1493	*/
1494	status = NFS_PROTO(inode)->write_done(task, hdr);
1495	if (status != 0)
1496	return status;
1497
1498	nfs_add_stats(inode, stat: NFSIOS_SERVERWRITTENBYTES, addend: hdr->res.count);
1499	trace_nfs_writeback_done(task, hdr);
1500
1501	if (task->tk_status >= 0) {
1502	enum nfs3_stable_how committed = hdr->res.verf->committed;
1503
1504	if (committed == NFS_UNSTABLE) {
1505	/*
1506	* We have some uncommitted data on the server at
1507	* this point, so ensure that we keep track of that
1508	* fact irrespective of what later writes do.
1509	*/
1510	set_bit(nr: NFS_IOHDR_UNSTABLE_WRITES, addr: &hdr->flags);
1511	}
1512
1513	if (committed < hdr->args.stable) {
1514	/* We tried a write call, but the server did not
1515	* commit data to stable storage even though we
1516	* requested it.
1517	* Note: There is a known bug in Tru64 < 5.0 in which
1518	* the server reports NFS_DATA_SYNC, but performs
1519	* NFS_FILE_SYNC. We therefore implement this checking
1520	* as a dprintk() in order to avoid filling syslog.
1521	*/
1522	static unsigned long complain;
1523
1524	/* Note this will print the MDS for a DS write */
1525	if (time_before(complain, jiffies)) {
1526	dprintk("NFS: faulty NFS server %s:"
1527	" (committed = %d) != (stable = %d)\n",
1528	NFS_SERVER(inode)->nfs_client->cl_hostname,
1529	committed, hdr->args.stable);
1530	complain = jiffies + 300 * HZ;
1531	}
1532	}
1533	}
1534
1535	/* Deal with the suid/sgid bit corner case */
1536	if (nfs_should_remove_suid(inode)) {
1537	spin_lock(lock: &inode->i_lock);
1538	nfs_set_cache_invalid(inode, NFS_INO_INVALID_MODE
1539	| NFS_INO_REVAL_FORCED);
1540	spin_unlock(lock: &inode->i_lock);
1541	}
1542	return 0;
1543	}
1544
1545	/*
1546	* This function is called when the WRITE call is complete.
1547	*/
1548	static void nfs_writeback_result(struct rpc_task *task,
1549	struct nfs_pgio_header *hdr)
1550	{
1551	struct nfs_pgio_args *argp = &hdr->args;
1552	struct nfs_pgio_res *resp = &hdr->res;
1553
1554	if (resp->count < argp->count) {
1555	static unsigned long complain;
1556
1557	/* This a short write! */
1558	nfs_inc_stats(inode: hdr->inode, stat: NFSIOS_SHORTWRITE);
1559
1560	/* Has the server at least made some progress? */
1561	if (resp->count == 0) {
1562	if (time_before(complain, jiffies)) {
1563	printk(KERN_WARNING
1564	"NFS: Server wrote zero bytes, expected %u.\n",
1565	argp->count);
1566	complain = jiffies + 300 * HZ;
1567	}
1568	nfs_set_pgio_error(hdr, error: -EIO, pos: argp->offset);
1569	task->tk_status = -EIO;
1570	return;
1571	}
1572
1573	/* For non rpc-based layout drivers, retry-through-MDS */
1574	if (!task->tk_ops) {
1575	hdr->pnfs_error = -EAGAIN;
1576	return;
1577	}
1578
1579	/* Was this an NFSv2 write or an NFSv3 stable write? */
1580	if (resp->verf->committed != NFS_UNSTABLE) {
1581	/* Resend from where the server left off */
1582	hdr->mds_offset += resp->count;
1583	argp->offset += resp->count;
1584	argp->pgbase += resp->count;
1585	argp->count -= resp->count;
1586	} else {
1587	/* Resend as a stable write in order to avoid
1588	* headaches in the case of a server crash.
1589	*/
1590	argp->stable = NFS_FILE_SYNC;
1591	}
1592	resp->count = 0;
1593	resp->verf->committed = 0;
1594	rpc_restart_call_prepare(task);
1595	}
1596	}
1597
1598	static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1599	{
1600	return wait_var_event_killable(&cinfo->rpcs_out,
1601	!atomic_read(&cinfo->rpcs_out));
1602	}
1603
1604	void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1605	{
1606	atomic_inc(v: &cinfo->rpcs_out);
1607	}
1608
1609	bool nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1610	{
1611	if (atomic_dec_and_test(v: &cinfo->rpcs_out)) {
1612	wake_up_var(var: &cinfo->rpcs_out);
1613	return true;
1614	}
1615	return false;
1616	}
1617
1618	void nfs_commitdata_release(struct nfs_commit_data *data)
1619	{
1620	put_nfs_open_context(ctx: data->context);
1621	nfs_commit_free(data);
1622	}
1623	EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1624
1625	int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1626	const struct nfs_rpc_ops *nfs_ops,
1627	const struct rpc_call_ops *call_ops,
1628	int how, int flags,
1629	struct nfsd_file *localio)
1630	{
1631	struct rpc_task *task;
1632	int priority = flush_task_priority(how);
1633	struct rpc_message msg = {
1634	.rpc_argp = &data->args,
1635	.rpc_resp = &data->res,
1636	.rpc_cred = data->cred,
1637	};
1638	struct rpc_task_setup task_setup_data = {
1639	.task = &data->task,
1640	.rpc_client = clnt,
1641	.rpc_message = &msg,
1642	.callback_ops = call_ops,
1643	.callback_data = data,
1644	.workqueue = nfsiod_workqueue,
1645	.flags = RPC_TASK_ASYNC | flags,
1646	.priority = priority,
1647	};
1648
1649	if (nfs_server_capable(inode: data->inode, NFS_CAP_MOVEABLE))
1650	task_setup_data.flags |= RPC_TASK_MOVEABLE;
1651
1652	/* Set up the initial task struct. */
1653	nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1654	trace_nfs_initiate_commit(data);
1655
1656	dprintk("NFS: initiated commit call\n");
1657
1658	if (localio)
1659	return nfs_local_commit(localio, data, call_ops, how);
1660
1661	task = rpc_run_task(&task_setup_data);
1662	if (IS_ERR(ptr: task))
1663	return PTR_ERR(ptr: task);
1664	if (how & FLUSH_SYNC)
1665	rpc_wait_for_completion_task(task);
1666	rpc_put_task(task);
1667	return 0;
1668	}
1669	EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1670
1671	static loff_t nfs_get_lwb(struct list_head *head)
1672	{
1673	loff_t lwb = 0;
1674	struct nfs_page *req;
1675
1676	list_for_each_entry(req, head, wb_list)
1677	if (lwb < (req_offset(req) + req->wb_bytes))
1678	lwb = req_offset(req) + req->wb_bytes;
1679
1680	return lwb;
1681	}
1682
1683	/*
1684	* Set up the argument/result storage required for the RPC call.
1685	*/
1686	void nfs_init_commit(struct nfs_commit_data *data,
1687	struct list_head *head,
1688	struct pnfs_layout_segment *lseg,
1689	struct nfs_commit_info *cinfo)
1690	{
1691	struct nfs_page *first;
1692	struct nfs_open_context *ctx;
1693	struct inode *inode;
1694
1695	/* Set up the RPC argument and reply structs
1696	* NB: take care not to mess about with data->commit et al. */
1697
1698	if (head)
1699	list_splice_init(list: head, head: &data->pages);
1700
1701	first = nfs_list_entry(head: data->pages.next);
1702	ctx = nfs_req_openctx(req: first);
1703	inode = d_inode(dentry: ctx->dentry);
1704
1705	data->inode = inode;
1706	data->cred = ctx->cred;
1707	data->lseg = lseg; /* reference transferred */
1708	/* only set lwb for pnfs commit */
1709	if (lseg)
1710	data->lwb = nfs_get_lwb(head: &data->pages);
1711	data->mds_ops = &nfs_commit_ops;
1712	data->completion_ops = cinfo->completion_ops;
1713	data->dreq = cinfo->dreq;
1714
1715	data->args.fh = NFS_FH(inode: data->inode);
1716	/* Note: we always request a commit of the entire inode */
1717	data->args.offset = 0;
1718	data->args.count = 0;
1719	data->context = get_nfs_open_context(ctx);
1720	data->res.fattr = &data->fattr;
1721	data->res.verf = &data->verf;
1722	nfs_fattr_init(fattr: &data->fattr);
1723	nfs_commit_begin(cinfo: cinfo->mds);
1724	}
1725	EXPORT_SYMBOL_GPL(nfs_init_commit);
1726
1727	void nfs_retry_commit(struct list_head *page_list,
1728	struct pnfs_layout_segment *lseg,
1729	struct nfs_commit_info *cinfo,
1730	u32 ds_commit_idx)
1731	{
1732	struct nfs_page *req;
1733
1734	while (!list_empty(head: page_list)) {
1735	req = nfs_list_entry(head: page_list->next);
1736	nfs_list_remove_request(req);
1737	nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1738	nfs_folio_clear_commit(folio: nfs_page_to_folio(req));
1739	nfs_unlock_and_release_request(req);
1740	}
1741	}
1742	EXPORT_SYMBOL_GPL(nfs_retry_commit);
1743
1744	static void nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1745	struct nfs_page *req)
1746	{
1747	struct folio *folio = nfs_page_to_folio(req);
1748
1749	filemap_dirty_folio(mapping: folio_mapping(folio), folio);
1750	}
1751
1752	/*
1753	* Commit dirty pages
1754	*/
1755	static int
1756	nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1757	struct nfs_commit_info *cinfo)
1758	{
1759	struct nfs_commit_data *data;
1760	struct nfsd_file *localio;
1761	unsigned short task_flags = 0;
1762
1763	/* another commit raced with us */
1764	if (list_empty(head))
1765	return 0;
1766
1767	data = nfs_commitdata_alloc();
1768	if (!data) {
1769	nfs_retry_commit(head, NULL, cinfo, -1);
1770	return -ENOMEM;
1771	}
1772
1773	/* Set up the argument struct */
1774	nfs_init_commit(data, head, NULL, cinfo);
1775	if (NFS_SERVER(inode)->nfs_client->cl_minorversion)
1776	task_flags = RPC_TASK_MOVEABLE;
1777
1778	localio = nfs_local_open_fh(NFS_SERVER(inode)->nfs_client, data->cred,
1779	data->args.fh, &data->context->nfl,
1780	data->context->mode);
1781	return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1782	data->mds_ops, how,
1783	RPC_TASK_CRED_NOREF | task_flags, localio);
1784	}
1785
1786	/*
1787	* COMMIT call returned
1788	*/
1789	static void nfs_commit_done(struct rpc_task *task, void *calldata)
1790	{
1791	struct nfs_commit_data *data = calldata;
1792
1793	/* Call the NFS version-specific code */
1794	NFS_PROTO(inode: data->inode)->commit_done(task, data);
1795	trace_nfs_commit_done(task, data);
1796	}
1797
1798	static void nfs_commit_release_pages(struct nfs_commit_data *data)
1799	{
1800	const struct nfs_writeverf *verf = data->res.verf;
1801	struct nfs_page *req;
1802	int status = data->task.tk_status;
1803	struct nfs_commit_info cinfo;
1804	struct folio *folio;
1805
1806	while (!list_empty(head: &data->pages)) {
1807	req = nfs_list_entry(head: data->pages.next);
1808	nfs_list_remove_request(req);
1809	folio = nfs_page_to_folio(req);
1810	nfs_folio_clear_commit(folio);
1811
1812	dprintk("NFS: commit (%s/%llu %d@%lld)",
1813	nfs_req_openctx(req)->dentry->d_sb->s_id,
1814	(unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1815	req->wb_bytes,
1816	(long long)req_offset(req));
1817	if (status < 0) {
1818	if (folio) {
1819	trace_nfs_commit_error(inode: data->inode, req,
1820	error: status);
1821	nfs_mapping_set_error(folio, error: status);
1822	nfs_inode_remove_request(req);
1823	}
1824	dprintk(", error = %d\n", status);
1825	goto next;
1826	}
1827
1828	/* Okay, COMMIT succeeded, apparently. Check the verifier
1829	* returned by the server against all stored verfs. */
1830	if (nfs_write_match_verf(verf, req)) {
1831	/* We have a match */
1832	if (folio)
1833	nfs_inode_remove_request(req);
1834	dprintk(" OK\n");
1835	goto next;
1836	}
1837	/* We have a mismatch. Write the page again */
1838	dprintk(" mismatch\n");
1839	nfs_mark_request_dirty(req);
1840	atomic_long_inc(v: &NFS_I(inode: data->inode)->redirtied_pages);
1841	next:
1842	nfs_unlock_and_release_request(req);
1843	/* Latency breaker */
1844	cond_resched();
1845	}
1846
1847	nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1848	nfs_commit_end(cinfo: cinfo.mds);
1849	}
1850
1851	static void nfs_commit_release(void *calldata)
1852	{
1853	struct nfs_commit_data *data = calldata;
1854
1855	data->completion_ops->completion(data);
1856	nfs_commitdata_release(calldata);
1857	}
1858
1859	static const struct rpc_call_ops nfs_commit_ops = {
1860	.rpc_call_prepare = nfs_commit_prepare,
1861	.rpc_call_done = nfs_commit_done,
1862	.rpc_release = nfs_commit_release,
1863	};
1864
1865	static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1866	.completion = nfs_commit_release_pages,
1867	.resched_write = nfs_commit_resched_write,
1868	};
1869
1870	int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1871	int how, struct nfs_commit_info *cinfo)
1872	{
1873	int status;
1874
1875	status = pnfs_commit_list(inode, mds_pages: head, how, cinfo);
1876	if (status == PNFS_NOT_ATTEMPTED)
1877	status = nfs_commit_list(inode, head, how, cinfo);
1878	return status;
1879	}
1880
1881	static int __nfs_commit_inode(struct inode *inode, int how,
1882	struct writeback_control *wbc)
1883	{
1884	LIST_HEAD(head);
1885	struct nfs_commit_info cinfo;
1886	int may_wait = how & FLUSH_SYNC;
1887	int ret, nscan;
1888
1889	how &= ~FLUSH_SYNC;
1890	nfs_init_cinfo_from_inode(cinfo: &cinfo, inode);
1891	nfs_commit_begin(cinfo: cinfo.mds);
1892	for (;;) {
1893	ret = nscan = nfs_scan_commit(inode, dst: &head, cinfo: &cinfo);
1894	if (ret <= 0)
1895	break;
1896	ret = nfs_generic_commit_list(inode, head: &head, how, cinfo: &cinfo);
1897	if (ret < 0)
1898	break;
1899	ret = 0;
1900	if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1901	if (nscan < wbc->nr_to_write)
1902	wbc->nr_to_write -= nscan;
1903	else
1904	wbc->nr_to_write = 0;
1905	}
1906	if (nscan < INT_MAX)
1907	break;
1908	cond_resched();
1909	}
1910	nfs_commit_end(cinfo: cinfo.mds);
1911	if (ret || !may_wait)
1912	return ret;
1913	return wait_on_commit(cinfo: cinfo.mds);
1914	}
1915
1916	int nfs_commit_inode(struct inode *inode, int how)
1917	{
1918	return __nfs_commit_inode(inode, how, NULL);
1919	}
1920	EXPORT_SYMBOL_GPL(nfs_commit_inode);
1921
1922	int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1923	{
1924	struct nfs_inode *nfsi = NFS_I(inode);
1925	int flags = FLUSH_SYNC;
1926	int ret = 0;
1927
1928	if (wbc->sync_mode == WB_SYNC_NONE) {
1929	/* no commits means nothing needs to be done */
1930	if (!atomic_long_read(v: &nfsi->commit_info.ncommit))
1931	goto check_requests_outstanding;
1932
1933	/* Don't commit yet if this is a non-blocking flush and there
1934	* are a lot of outstanding writes for this mapping.
1935	*/
1936	if (mapping_tagged(mapping: inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1937	goto out_mark_dirty;
1938
1939	/* don't wait for the COMMIT response */
1940	flags = 0;
1941	}
1942
1943	ret = __nfs_commit_inode(inode, how: flags, wbc);
1944	if (!ret) {
1945	if (flags & FLUSH_SYNC)
1946	return 0;
1947	} else if (atomic_long_read(v: &nfsi->commit_info.ncommit))
1948	goto out_mark_dirty;
1949
1950	check_requests_outstanding:
1951	if (!atomic_read(v: &nfsi->commit_info.rpcs_out))
1952	return ret;
1953	out_mark_dirty:
1954	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1955	return ret;
1956	}
1957	EXPORT_SYMBOL_GPL(nfs_write_inode);
1958
1959	/*
1960	* Wrapper for filemap_write_and_wait_range()
1961	*
1962	* Needed for pNFS in order to ensure data becomes visible to the
1963	* client.
1964	*/
1965	int nfs_filemap_write_and_wait_range(struct address_space *mapping,
1966	loff_t lstart, loff_t lend)
1967	{
1968	int ret;
1969
1970	ret = filemap_write_and_wait_range(mapping, lstart, lend);
1971	if (ret == 0)
1972	ret = pnfs_sync_inode(inode: mapping->host, datasync: true);
1973	return ret;
1974	}
1975	EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
1976
1977	/*
1978	* flush the inode to disk.
1979	*/
1980	int nfs_wb_all(struct inode *inode)
1981	{
1982	int ret;
1983
1984	trace_nfs_writeback_inode_enter(inode);
1985
1986	ret = filemap_write_and_wait(mapping: inode->i_mapping);
1987	if (ret)
1988	goto out;
1989	ret = nfs_commit_inode(inode, FLUSH_SYNC);
1990	if (ret < 0)
1991	goto out;
1992	pnfs_sync_inode(inode, datasync: true);
1993	ret = 0;
1994
1995	out:
1996	trace_nfs_writeback_inode_exit(inode, error: ret);
1997	return ret;
1998	}
1999	EXPORT_SYMBOL_GPL(nfs_wb_all);
2000
2001	int nfs_wb_folio_cancel(struct inode *inode, struct folio *folio)
2002	{
2003	struct nfs_page *req;
2004	int ret = 0;
2005
2006	folio_wait_writeback(folio);
2007
2008	/* blocking call to cancel all requests and join to a single (head)
2009	* request */
2010	req = nfs_lock_and_join_requests(folio);
2011
2012	if (IS_ERR(ptr: req)) {
2013	ret = PTR_ERR(ptr: req);
2014	} else if (req) {
2015	/* all requests from this folio have been cancelled by
2016	* nfs_lock_and_join_requests, so just remove the head
2017	* request from the inode / page_private pointer and
2018	* release it */
2019	nfs_inode_remove_request(req);
2020	nfs_unlock_and_release_request(req);
2021	folio_cancel_dirty(folio);
2022	}
2023
2024	return ret;
2025	}
2026
2027	/**
2028	* nfs_wb_folio_reclaim - Write back all requests on one page
2029	* @inode: pointer to page
2030	* @folio: pointer to folio
2031	*
2032	* Assumes that the folio has been locked by the caller
2033	*/
2034	int nfs_wb_folio_reclaim(struct inode *inode, struct folio *folio)
2035	{
2036	loff_t range_start = folio_pos(folio);
2037	size_t len = folio_size(folio);
2038	struct writeback_control wbc = {
2039	.sync_mode = WB_SYNC_ALL,
2040	.nr_to_write = 0,
2041	.range_start = range_start,
2042	.range_end = range_start + len - 1,
2043	.for_sync = 1,
2044	};
2045	int ret;
2046
2047	if (folio_test_writeback(folio))
2048	return -EBUSY;
2049	if (folio_clear_dirty_for_io(folio)) {
2050	trace_nfs_writeback_folio_reclaim(inode, offset: range_start, count: len);
2051	ret = nfs_writepage_locked(folio, wbc: &wbc);
2052	trace_nfs_writeback_folio_reclaim_done(inode, offset: range_start, count: len,
2053	ret);
2054	return ret;
2055	}
2056	nfs_commit_inode(inode, 0);
2057	return 0;
2058	}
2059
2060	/**
2061	* nfs_wb_folio - Write back all requests on one page
2062	* @inode: pointer to page
2063	* @folio: pointer to folio
2064	*
2065	* Assumes that the folio has been locked by the caller, and will
2066	* not unlock it.
2067	*/
2068	int nfs_wb_folio(struct inode *inode, struct folio *folio)
2069	{
2070	loff_t range_start = folio_pos(folio);
2071	size_t len = folio_size(folio);
2072	struct writeback_control wbc = {
2073	.sync_mode = WB_SYNC_ALL,
2074	.nr_to_write = 0,
2075	.range_start = range_start,
2076	.range_end = range_start + len - 1,
2077	};
2078	int ret;
2079
2080	trace_nfs_writeback_folio(inode, offset: range_start, count: len);
2081
2082	for (;;) {
2083	folio_wait_writeback(folio);
2084	if (folio_clear_dirty_for_io(folio)) {
2085	ret = nfs_writepage_locked(folio, wbc: &wbc);
2086	if (ret < 0)
2087	goto out_error;
2088	continue;
2089	}
2090	ret = 0;
2091	if (!folio_test_private(folio))
2092	break;
2093	ret = nfs_commit_inode(inode, FLUSH_SYNC);
2094	if (ret < 0)
2095	goto out_error;
2096	}
2097	out_error:
2098	trace_nfs_writeback_folio_done(inode, offset: range_start, count: len, ret);
2099	return ret;
2100	}
2101
2102	#ifdef CONFIG_MIGRATION
2103	int nfs_migrate_folio(struct address_space *mapping, struct folio *dst,
2104	struct folio *src, enum migrate_mode mode)
2105	{
2106	/*
2107	* If the private flag is set, the folio is currently associated with
2108	* an in-progress read or write request. Don't try to migrate it.
2109	*
2110	* FIXME: we could do this in principle, but we'll need a way to ensure
2111	* that we can safely release the inode reference while holding
2112	* the folio lock.
2113	*/
2114	if (folio_test_private(folio: src)) {
2115	if (mode == MIGRATE_SYNC)
2116	nfs_wb_folio(inode: src->mapping->host, folio: src);
2117	if (folio_test_private(folio: src))
2118	return -EBUSY;
2119	}
2120
2121	if (folio_test_private_2(folio: src)) { /* [DEPRECATED] */
2122	if (mode == MIGRATE_ASYNC)
2123	return -EBUSY;
2124	folio_wait_private_2(folio: src);
2125	}
2126
2127	return migrate_folio(mapping, dst, src, mode);
2128	}
2129	#endif
2130
2131	int __init nfs_init_writepagecache(void)
2132	{
2133	nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2134	sizeof(struct nfs_pgio_header),
2135	0, SLAB_HWCACHE_ALIGN,
2136	NULL);
2137	if (nfs_wdata_cachep == NULL)
2138	return -ENOMEM;
2139
2140	nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2141	nfs_wdata_cachep);
2142	if (nfs_wdata_mempool == NULL)
2143	goto out_destroy_write_cache;
2144
2145	nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2146	sizeof(struct nfs_commit_data),
2147	0, SLAB_HWCACHE_ALIGN,
2148	NULL);
2149	if (nfs_cdata_cachep == NULL)
2150	goto out_destroy_write_mempool;
2151
2152	nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2153	nfs_cdata_cachep);
2154	if (nfs_commit_mempool == NULL)
2155	goto out_destroy_commit_cache;
2156
2157	/*
2158	* NFS congestion size, scale with available memory.
2159	*
2160	* 64MB: 8192k
2161	* 128MB: 11585k
2162	* 256MB: 16384k
2163	* 512MB: 23170k
2164	* 1GB: 32768k
2165	* 2GB: 46340k
2166	* 4GB: 65536k
2167	* 8GB: 92681k
2168	* 16GB: 131072k
2169	*
2170	* This allows larger machines to have larger/more transfers.
2171	* Limit the default to 256M
2172	*/
2173	nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2174	if (nfs_congestion_kb > 256*1024)
2175	nfs_congestion_kb = 256*1024;
2176
2177	return 0;
2178
2179	out_destroy_commit_cache:
2180	kmem_cache_destroy(s: nfs_cdata_cachep);
2181	out_destroy_write_mempool:
2182	mempool_destroy(pool: nfs_wdata_mempool);
2183	out_destroy_write_cache:
2184	kmem_cache_destroy(s: nfs_wdata_cachep);
2185	return -ENOMEM;
2186	}
2187
2188	void nfs_destroy_writepagecache(void)
2189	{
2190	mempool_destroy(pool: nfs_commit_mempool);
2191	kmem_cache_destroy(s: nfs_cdata_cachep);
2192	mempool_destroy(pool: nfs_wdata_mempool);
2193	kmem_cache_destroy(s: nfs_wdata_cachep);
2194	}
2195
2196	static const struct nfs_rw_ops nfs_rw_write_ops = {
2197	.rw_alloc_header = nfs_writehdr_alloc,
2198	.rw_free_header = nfs_writehdr_free,
2199	.rw_done = nfs_writeback_done,
2200	.rw_result = nfs_writeback_result,
2201	.rw_initiate = nfs_initiate_write,
2202	};
2203