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
  29#include <linux/uaccess.h>
  30#include <linux/sched/mm.h>
  31
  32#include "delegation.h"
  33#include "internal.h"
  34#include "iostat.h"
  35#include "nfs4_fs.h"
  36#include "fscache.h"
  37#include "pnfs.h"
  38
  39#include "nfstrace.h"
  40
  41#define NFSDBG_FACILITY		NFSDBG_PAGECACHE
  42
  43#define MIN_POOL_WRITE		(32)
  44#define MIN_POOL_COMMIT		(4)
  45
  46struct nfs_io_completion {
  47	void (*complete)(void *data);
  48	void *data;
  49	struct kref refcount;
  50};
  51
  52/*
  53 * Local function declarations
  54 */
  55static void nfs_redirty_request(struct nfs_page *req);
  56static const struct rpc_call_ops nfs_commit_ops;
  57static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  58static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  59static const struct nfs_rw_ops nfs_rw_write_ops;
  60static void nfs_inode_remove_request(struct nfs_page *req);
  61static void nfs_clear_request_commit(struct nfs_page *req);
  62static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
  63				      struct inode *inode);
  64static struct nfs_page *
  65nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
  66						struct page *page);
  67
  68static struct kmem_cache *nfs_wdata_cachep;
  69static mempool_t *nfs_wdata_mempool;
  70static struct kmem_cache *nfs_cdata_cachep;
  71static mempool_t *nfs_commit_mempool;
  72
  73struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail)
  74{
  75	struct nfs_commit_data *p;
  76
  77	if (never_fail)
  78		p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
  79	else {
  80		/* It is OK to do some reclaim, not no safe to wait
  81		 * for anything to be returned to the pool.
  82		 * mempool_alloc() cannot handle that particular combination,
  83		 * so we need two separate attempts.
  84		 */
  85		p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
  86		if (!p)
  87			p = kmem_cache_alloc(nfs_cdata_cachep, GFP_NOIO |
  88					     __GFP_NOWARN | __GFP_NORETRY);
  89		if (!p)
  90			return NULL;
  91	}
  92
  93	memset(p, 0, sizeof(*p));
  94	INIT_LIST_HEAD(&p->pages);
  95	return p;
  96}
  97EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  98
  99void nfs_commit_free(struct nfs_commit_data *p)
 100{
 101	mempool_free(p, nfs_commit_mempool);
 102}
 103EXPORT_SYMBOL_GPL(nfs_commit_free);
 104
 105static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 106{
 107	struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_KERNEL);
 108
 109	memset(p, 0, sizeof(*p));
 110	p->rw_mode = FMODE_WRITE;
 111	return p;
 112}
 113
 114static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 115{
 116	mempool_free(hdr, nfs_wdata_mempool);
 117}
 118
 119static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
 120{
 121	return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
 122}
 123
 124static void nfs_io_completion_init(struct nfs_io_completion *ioc,
 125		void (*complete)(void *), void *data)
 126{
 127	ioc->complete = complete;
 128	ioc->data = data;
 129	kref_init(&ioc->refcount);
 130}
 131
 132static void nfs_io_completion_release(struct kref *kref)
 133{
 134	struct nfs_io_completion *ioc = container_of(kref,
 135			struct nfs_io_completion, refcount);
 136	ioc->complete(ioc->data);
 137	kfree(ioc);
 138}
 139
 140static void nfs_io_completion_get(struct nfs_io_completion *ioc)
 141{
 142	if (ioc != NULL)
 143		kref_get(&ioc->refcount);
 144}
 145
 146static void nfs_io_completion_put(struct nfs_io_completion *ioc)
 147{
 148	if (ioc != NULL)
 149		kref_put(&ioc->refcount, nfs_io_completion_release);
 150}
 151
 152static void
 153nfs_page_set_inode_ref(struct nfs_page *req, struct inode *inode)
 154{
 155	if (!test_and_set_bit(PG_INODE_REF, &req->wb_flags)) {
 156		kref_get(&req->wb_kref);
 157		atomic_long_inc(&NFS_I(inode)->nrequests);
 158	}
 159}
 160
 161static int
 162nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode)
 163{
 164	int ret;
 165
 166	if (!test_bit(PG_REMOVE, &req->wb_flags))
 167		return 0;
 168	ret = nfs_page_group_lock(req);
 169	if (ret)
 170		return ret;
 171	if (test_and_clear_bit(PG_REMOVE, &req->wb_flags))
 172		nfs_page_set_inode_ref(req, inode);
 173	nfs_page_group_unlock(req);
 174	return 0;
 175}
 176
 177static struct nfs_page *
 178nfs_page_private_request(struct page *page)
 179{
 180	if (!PagePrivate(page))
 181		return NULL;
 182	return (struct nfs_page *)page_private(page);
 183}
 184
 185/*
 186 * nfs_page_find_head_request_locked - find head request associated with @page
 187 *
 188 * must be called while holding the inode lock.
 189 *
 190 * returns matching head request with reference held, or NULL if not found.
 191 */
 192static struct nfs_page *
 193nfs_page_find_private_request(struct page *page)
 194{
 195	struct address_space *mapping = page_file_mapping(page);
 196	struct nfs_page *req;
 197
 198	if (!PagePrivate(page))
 199		return NULL;
 200	spin_lock(&mapping->private_lock);
 201	req = nfs_page_private_request(page);
 202	if (req) {
 203		WARN_ON_ONCE(req->wb_head != req);
 204		kref_get(&req->wb_kref);
 205	}
 206	spin_unlock(&mapping->private_lock);
 207	return req;
 208}
 209
 210static struct nfs_page *
 211nfs_page_find_swap_request(struct page *page)
 212{
 213	struct inode *inode = page_file_mapping(page)->host;
 214	struct nfs_inode *nfsi = NFS_I(inode);
 215	struct nfs_page *req = NULL;
 216	if (!PageSwapCache(page))
 217		return NULL;
 218	mutex_lock(&nfsi->commit_mutex);
 219	if (PageSwapCache(page)) {
 220		req = nfs_page_search_commits_for_head_request_locked(nfsi,
 221			page);
 222		if (req) {
 223			WARN_ON_ONCE(req->wb_head != req);
 224			kref_get(&req->wb_kref);
 225		}
 226	}
 227	mutex_unlock(&nfsi->commit_mutex);
 228	return req;
 229}
 230
 231/*
 232 * nfs_page_find_head_request - find head request associated with @page
 233 *
 234 * returns matching head request with reference held, or NULL if not found.
 235 */
 236static struct nfs_page *nfs_page_find_head_request(struct page *page)
 237{
 238	struct nfs_page *req;
 239
 240	req = nfs_page_find_private_request(page);
 241	if (!req)
 242		req = nfs_page_find_swap_request(page);
 243	return req;
 244}
 245
 246static struct nfs_page *nfs_find_and_lock_page_request(struct page *page)
 247{
 248	struct inode *inode = page_file_mapping(page)->host;
 249	struct nfs_page *req, *head;
 250	int ret;
 251
 252	for (;;) {
 253		req = nfs_page_find_head_request(page);
 254		if (!req)
 255			return req;
 256		head = nfs_page_group_lock_head(req);
 257		if (head != req)
 258			nfs_release_request(req);
 259		if (IS_ERR(head))
 260			return head;
 261		ret = nfs_cancel_remove_inode(head, inode);
 262		if (ret < 0) {
 263			nfs_unlock_and_release_request(head);
 264			return ERR_PTR(ret);
 265		}
 266		/* Ensure that nobody removed the request before we locked it */
 267		if (head == nfs_page_private_request(page))
 268			break;
 269		if (PageSwapCache(page))
 270			break;
 271		nfs_unlock_and_release_request(head);
 272	}
 273	return head;
 274}
 275
 276/* Adjust the file length if we're writing beyond the end */
 277static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 278{
 279	struct inode *inode = page_file_mapping(page)->host;
 280	loff_t end, i_size;
 281	pgoff_t end_index;
 282
 283	spin_lock(&inode->i_lock);
 284	i_size = i_size_read(inode);
 285	end_index = (i_size - 1) >> PAGE_SHIFT;
 286	if (i_size > 0 && page_index(page) < end_index)
 287		goto out;
 288	end = page_file_offset(page) + ((loff_t)offset+count);
 289	if (i_size >= end)
 290		goto out;
 291	i_size_write(inode, end);
 292	NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
 293	nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 294out:
 295	spin_unlock(&inode->i_lock);
 296}
 297
 298/* A writeback failed: mark the page as bad, and invalidate the page cache */
 299static void nfs_set_pageerror(struct address_space *mapping)
 300{
 301	struct inode *inode = mapping->host;
 302
 303	nfs_zap_mapping(mapping->host, mapping);
 304	/* Force file size revalidation */
 305	spin_lock(&inode->i_lock);
 306	nfs_set_cache_invalid(inode, NFS_INO_REVAL_FORCED |
 307					     NFS_INO_REVAL_PAGECACHE |
 308					     NFS_INO_INVALID_SIZE);
 309	spin_unlock(&inode->i_lock);
 310}
 311
 312static void nfs_mapping_set_error(struct page *page, int error)
 313{
 314	struct address_space *mapping = page_file_mapping(page);
 315
 316	SetPageError(page);
 317	mapping_set_error(mapping, error);
 318	nfs_set_pageerror(mapping);
 319}
 320
 321/*
 322 * nfs_page_group_search_locked
 323 * @head - head request of page group
 324 * @page_offset - offset into page
 325 *
 326 * Search page group with head @head to find a request that contains the
 327 * page offset @page_offset.
 328 *
 329 * Returns a pointer to the first matching nfs request, or NULL if no
 330 * match is found.
 331 *
 332 * Must be called with the page group lock held
 333 */
 334static struct nfs_page *
 335nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 336{
 337	struct nfs_page *req;
 338
 339	req = head;
 340	do {
 341		if (page_offset >= req->wb_pgbase &&
 342		    page_offset < (req->wb_pgbase + req->wb_bytes))
 343			return req;
 344
 345		req = req->wb_this_page;
 346	} while (req != head);
 347
 348	return NULL;
 349}
 350
 351/*
 352 * nfs_page_group_covers_page
 353 * @head - head request of page group
 354 *
 355 * Return true if the page group with head @head covers the whole page,
 356 * returns false otherwise
 357 */
 358static bool nfs_page_group_covers_page(struct nfs_page *req)
 359{
 360	struct nfs_page *tmp;
 361	unsigned int pos = 0;
 362	unsigned int len = nfs_page_length(req->wb_page);
 363
 364	nfs_page_group_lock(req);
 365
 366	for (;;) {
 367		tmp = nfs_page_group_search_locked(req->wb_head, pos);
 368		if (!tmp)
 369			break;
 370		pos = tmp->wb_pgbase + tmp->wb_bytes;
 371	}
 372
 373	nfs_page_group_unlock(req);
 374	return pos >= len;
 375}
 376
 377/* We can set the PG_uptodate flag if we see that a write request
 378 * covers the full page.
 379 */
 380static void nfs_mark_uptodate(struct nfs_page *req)
 381{
 382	if (PageUptodate(req->wb_page))
 383		return;
 384	if (!nfs_page_group_covers_page(req))
 385		return;
 386	SetPageUptodate(req->wb_page);
 387}
 388
 389static int wb_priority(struct writeback_control *wbc)
 390{
 391	int ret = 0;
 392
 393	if (wbc->sync_mode == WB_SYNC_ALL)
 394		ret = FLUSH_COND_STABLE;
 395	return ret;
 396}
 397
 398/*
 399 * NFS congestion control
 400 */
 401
 402int nfs_congestion_kb;
 403
 404#define NFS_CONGESTION_ON_THRESH 	(nfs_congestion_kb >> (PAGE_SHIFT-10))
 405#define NFS_CONGESTION_OFF_THRESH	\
 406	(NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 407
 408static void nfs_set_page_writeback(struct page *page)
 409{
 410	struct inode *inode = page_file_mapping(page)->host;
 411	struct nfs_server *nfss = NFS_SERVER(inode);
 412	int ret = test_set_page_writeback(page);
 413
 414	WARN_ON_ONCE(ret != 0);
 415
 416	if (atomic_long_inc_return(&nfss->writeback) >
 417			NFS_CONGESTION_ON_THRESH)
 418		set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 419}
 420
 421static void nfs_end_page_writeback(struct nfs_page *req)
 422{
 423	struct inode *inode = page_file_mapping(req->wb_page)->host;
 424	struct nfs_server *nfss = NFS_SERVER(inode);
 425	bool is_done;
 426
 427	is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 428	nfs_unlock_request(req);
 429	if (!is_done)
 430		return;
 431
 432	end_page_writeback(req->wb_page);
 433	if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 434		clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 435}
 436
 437/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 438 * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 439 *
 440 * @destroy_list - request list (using wb_this_page) terminated by @old_head
 441 * @old_head - the old head of the list
 442 *
 443 * All subrequests must be locked and removed from all lists, so at this point
 444 * they are only "active" in this function, and possibly in nfs_wait_on_request
 445 * with a reference held by some other context.
 446 */
 447static void
 448nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 449				 struct nfs_page *old_head,
 450				 struct inode *inode)
 451{
 452	while (destroy_list) {
 453		struct nfs_page *subreq = destroy_list;
 454
 455		destroy_list = (subreq->wb_this_page == old_head) ?
 456				   NULL : subreq->wb_this_page;
 457
 458		/* Note: lock subreq in order to change subreq->wb_head */
 459		nfs_page_set_headlock(subreq);
 460		WARN_ON_ONCE(old_head != subreq->wb_head);
 461
 462		/* make sure old group is not used */
 463		subreq->wb_this_page = subreq;
 464		subreq->wb_head = subreq;
 465
 466		clear_bit(PG_REMOVE, &subreq->wb_flags);
 467
 468		/* Note: races with nfs_page_group_destroy() */
 469		if (!kref_read(&subreq->wb_kref)) {
 470			/* Check if we raced with nfs_page_group_destroy() */
 471			if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags)) {
 472				nfs_page_clear_headlock(subreq);
 473				nfs_free_request(subreq);
 474			} else
 475				nfs_page_clear_headlock(subreq);
 476			continue;
 477		}
 478		nfs_page_clear_headlock(subreq);
 479
 480		nfs_release_request(old_head);
 481
 482		if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 483			nfs_release_request(subreq);
 484			atomic_long_dec(&NFS_I(inode)->nrequests);
 485		}
 486
 487		/* subreq is now totally disconnected from page group or any
 488		 * write / commit lists. last chance to wake any waiters */
 489		nfs_unlock_and_release_request(subreq);
 490	}
 491}
 492
 493/*
 494 * nfs_join_page_group - destroy subrequests of the head req
 495 * @head: the page used to lookup the "page group" of nfs_page structures
 496 * @inode: Inode to which the request belongs.
 
 
 497 *
 498 * This function joins all sub requests to the head request by first
 499 * locking all requests in the group, cancelling any pending operations
 500 * and finally updating the head request to cover the whole range covered by
 501 * the (former) group.  All subrequests are removed from any write or commit
 502 * lists, unlinked from the group and destroyed.
 
 
 
 
 
 503 */
 504void
 505nfs_join_page_group(struct nfs_page *head, struct inode *inode)
 506{
 507	struct nfs_page *subreq;
 
 508	struct nfs_page *destroy_list = NULL;
 509	unsigned int pgbase, off, bytes;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 510
 511	pgbase = head->wb_pgbase;
 512	bytes = head->wb_bytes;
 513	off = head->wb_offset;
 514	for (subreq = head->wb_this_page; subreq != head;
 515			subreq = subreq->wb_this_page) {
 516		/* Subrequests should always form a contiguous range */
 517		if (pgbase > subreq->wb_pgbase) {
 518			off -= pgbase - subreq->wb_pgbase;
 519			bytes += pgbase - subreq->wb_pgbase;
 520			pgbase = subreq->wb_pgbase;
 521		}
 522		bytes = max(subreq->wb_pgbase + subreq->wb_bytes
 523				- pgbase, bytes);
 524	}
 525
 526	/* Set the head request's range to cover the former page group */
 527	head->wb_pgbase = pgbase;
 528	head->wb_bytes = bytes;
 529	head->wb_offset = off;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 530
 531	/* Now that all requests are locked, make sure they aren't on any list.
 532	 * Commit list removal accounting is done after locks are dropped */
 533	subreq = head;
 534	do {
 535		nfs_clear_request_commit(subreq);
 536		subreq = subreq->wb_this_page;
 537	} while (subreq != head);
 538
 539	/* unlink subrequests from head, destroy them later */
 540	if (head->wb_this_page != head) {
 541		/* destroy list will be terminated by head */
 542		destroy_list = head->wb_this_page;
 543		head->wb_this_page = head;
 
 
 
 
 544	}
 545
 546	nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 547}
 
 
 
 
 548
 549/*
 550 * nfs_lock_and_join_requests - join all subreqs to the head req
 551 * @page: the page used to lookup the "page group" of nfs_page structures
 552 *
 553 * This function joins all sub requests to the head request by first
 554 * locking all requests in the group, cancelling any pending operations
 555 * and finally updating the head request to cover the whole range covered by
 556 * the (former) group.  All subrequests are removed from any write or commit
 557 * lists, unlinked from the group and destroyed.
 558 *
 559 * Returns a locked, referenced pointer to the head request - which after
 560 * this call is guaranteed to be the only request associated with the page.
 561 * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 562 * error was encountered.
 563 */
 564static struct nfs_page *
 565nfs_lock_and_join_requests(struct page *page)
 566{
 567	struct inode *inode = page_file_mapping(page)->host;
 568	struct nfs_page *head;
 569	int ret;
 570
 571	/*
 572	 * A reference is taken only on the head request which acts as a
 573	 * reference to the whole page group - the group will not be destroyed
 574	 * until the head reference is released.
 575	 */
 576	head = nfs_find_and_lock_page_request(page);
 577	if (IS_ERR_OR_NULL(head))
 578		return head;
 579
 580	/* lock each request in the page group */
 581	ret = nfs_page_group_lock_subrequests(head);
 582	if (ret < 0) {
 583		nfs_unlock_and_release_request(head);
 584		return ERR_PTR(ret);
 585	}
 586
 587	nfs_join_page_group(head, inode);
 588
 589	return head;
 
 
 
 
 590}
 591
 592static void nfs_write_error(struct nfs_page *req, int error)
 593{
 594	trace_nfs_write_error(req, error);
 595	nfs_mapping_set_error(req->wb_page, error);
 596	nfs_inode_remove_request(req);
 597	nfs_end_page_writeback(req);
 598	nfs_release_request(req);
 599}
 600
 601/*
 602 * Find an associated nfs write request, and prepare to flush it out
 603 * May return an error if the user signalled nfs_wait_on_request().
 604 */
 605static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 606				struct page *page)
 607{
 608	struct nfs_page *req;
 609	int ret = 0;
 610
 611	req = nfs_lock_and_join_requests(page);
 612	if (!req)
 613		goto out;
 614	ret = PTR_ERR(req);
 615	if (IS_ERR(req))
 616		goto out;
 617
 618	nfs_set_page_writeback(page);
 619	WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 620
 621	/* If there is a fatal error that covers this write, just exit */
 622	ret = pgio->pg_error;
 623	if (nfs_error_is_fatal_on_server(ret))
 624		goto out_launder;
 625
 626	ret = 0;
 627	if (!nfs_pageio_add_request(pgio, req)) {
 628		ret = pgio->pg_error;
 629		/*
 630		 * Remove the problematic req upon fatal errors on the server
 631		 */
 632		if (nfs_error_is_fatal(ret)) {
 633			if (nfs_error_is_fatal_on_server(ret))
 634				goto out_launder;
 635		} else
 636			ret = -EAGAIN;
 637		nfs_redirty_request(req);
 638		pgio->pg_error = 0;
 639	} else
 640		nfs_add_stats(page_file_mapping(page)->host,
 641				NFSIOS_WRITEPAGES, 1);
 642out:
 643	return ret;
 644out_launder:
 645	nfs_write_error(req, ret);
 646	return 0;
 647}
 648
 649static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 650			    struct nfs_pageio_descriptor *pgio)
 651{
 652	int ret;
 653
 654	nfs_pageio_cond_complete(pgio, page_index(page));
 655	ret = nfs_page_async_flush(pgio, page);
 656	if (ret == -EAGAIN) {
 657		redirty_page_for_writepage(wbc, page);
 658		ret = AOP_WRITEPAGE_ACTIVATE;
 659	}
 660	return ret;
 661}
 662
 663/*
 664 * Write an mmapped page to the server.
 665 */
 666static int nfs_writepage_locked(struct page *page,
 667				struct writeback_control *wbc)
 668{
 669	struct nfs_pageio_descriptor pgio;
 670	struct inode *inode = page_file_mapping(page)->host;
 671	int err;
 672
 673	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 674	nfs_pageio_init_write(&pgio, inode, 0,
 675				false, &nfs_async_write_completion_ops);
 676	err = nfs_do_writepage(page, wbc, &pgio);
 677	pgio.pg_error = 0;
 678	nfs_pageio_complete(&pgio);
 679	if (err < 0)
 680		return err;
 681	if (nfs_error_is_fatal(pgio.pg_error))
 682		return pgio.pg_error;
 683	return 0;
 684}
 685
 686int nfs_writepage(struct page *page, struct writeback_control *wbc)
 687{
 688	int ret;
 689
 690	ret = nfs_writepage_locked(page, wbc);
 691	if (ret != AOP_WRITEPAGE_ACTIVATE)
 692		unlock_page(page);
 693	return ret;
 694}
 695
 696static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 697{
 698	int ret;
 699
 700	ret = nfs_do_writepage(page, wbc, data);
 701	if (ret != AOP_WRITEPAGE_ACTIVATE)
 702		unlock_page(page);
 703	return ret;
 704}
 705
 706static void nfs_io_completion_commit(void *inode)
 707{
 708	nfs_commit_inode(inode, 0);
 709}
 710
 711int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 712{
 713	struct inode *inode = mapping->host;
 714	struct nfs_pageio_descriptor pgio;
 715	struct nfs_io_completion *ioc = NULL;
 716	unsigned int mntflags = NFS_SERVER(inode)->flags;
 717	int priority = 0;
 718	int err;
 719
 720	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 721
 722	if (!(mntflags & NFS_MOUNT_WRITE_EAGER) || wbc->for_kupdate ||
 723	    wbc->for_background || wbc->for_sync || wbc->for_reclaim) {
 724		ioc = nfs_io_completion_alloc(GFP_KERNEL);
 725		if (ioc)
 726			nfs_io_completion_init(ioc, nfs_io_completion_commit,
 727					       inode);
 728		priority = wb_priority(wbc);
 729	}
 730
 731	nfs_pageio_init_write(&pgio, inode, priority, false,
 732				&nfs_async_write_completion_ops);
 733	pgio.pg_io_completion = ioc;
 734	err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 735	pgio.pg_error = 0;
 736	nfs_pageio_complete(&pgio);
 737	nfs_io_completion_put(ioc);
 738
 739	if (err < 0)
 740		goto out_err;
 741	err = pgio.pg_error;
 742	if (nfs_error_is_fatal(err))
 743		goto out_err;
 744	return 0;
 745out_err:
 746	return err;
 747}
 748
 749/*
 750 * Insert a write request into an inode
 751 */
 752static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 753{
 754	struct address_space *mapping = page_file_mapping(req->wb_page);
 755	struct nfs_inode *nfsi = NFS_I(inode);
 756
 757	WARN_ON_ONCE(req->wb_this_page != req);
 758
 759	/* Lock the request! */
 760	nfs_lock_request(req);
 761
 762	/*
 763	 * Swap-space should not get truncated. Hence no need to plug the race
 764	 * with invalidate/truncate.
 765	 */
 766	spin_lock(&mapping->private_lock);
 
 
 
 767	if (likely(!PageSwapCache(req->wb_page))) {
 768		set_bit(PG_MAPPED, &req->wb_flags);
 769		SetPagePrivate(req->wb_page);
 770		set_page_private(req->wb_page, (unsigned long)req);
 771	}
 772	spin_unlock(&mapping->private_lock);
 773	atomic_long_inc(&nfsi->nrequests);
 774	/* this a head request for a page group - mark it as having an
 775	 * extra reference so sub groups can follow suit.
 776	 * This flag also informs pgio layer when to bump nrequests when
 777	 * adding subrequests. */
 778	WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 779	kref_get(&req->wb_kref);
 780}
 781
 782/*
 783 * Remove a write request from an inode
 784 */
 785static void nfs_inode_remove_request(struct nfs_page *req)
 786{
 787	struct address_space *mapping = page_file_mapping(req->wb_page);
 788	struct inode *inode = mapping->host;
 789	struct nfs_inode *nfsi = NFS_I(inode);
 790	struct nfs_page *head;
 791
 792	if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 793		head = req->wb_head;
 794
 795		spin_lock(&mapping->private_lock);
 796		if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 797			set_page_private(head->wb_page, 0);
 798			ClearPagePrivate(head->wb_page);
 799			clear_bit(PG_MAPPED, &head->wb_flags);
 800		}
 801		spin_unlock(&mapping->private_lock);
 802	}
 803
 804	if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) {
 805		nfs_release_request(req);
 806		atomic_long_dec(&nfsi->nrequests);
 807	}
 808}
 809
 810static void
 811nfs_mark_request_dirty(struct nfs_page *req)
 812{
 813	if (req->wb_page)
 814		__set_page_dirty_nobuffers(req->wb_page);
 815}
 816
 817/*
 818 * nfs_page_search_commits_for_head_request_locked
 819 *
 820 * Search through commit lists on @inode for the head request for @page.
 821 * Must be called while holding the inode (which is cinfo) lock.
 822 *
 823 * Returns the head request if found, or NULL if not found.
 824 */
 825static struct nfs_page *
 826nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 827						struct page *page)
 828{
 829	struct nfs_page *freq, *t;
 830	struct nfs_commit_info cinfo;
 831	struct inode *inode = &nfsi->vfs_inode;
 832
 833	nfs_init_cinfo_from_inode(&cinfo, inode);
 834
 835	/* search through pnfs commit lists */
 836	freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 837	if (freq)
 838		return freq->wb_head;
 839
 840	/* Linearly search the commit list for the correct request */
 841	list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 842		if (freq->wb_page == page)
 843			return freq->wb_head;
 844	}
 845
 846	return NULL;
 847}
 848
 849/**
 850 * nfs_request_add_commit_list_locked - add request to a commit list
 851 * @req: pointer to a struct nfs_page
 852 * @dst: commit list head
 853 * @cinfo: holds list lock and accounting info
 854 *
 855 * This sets the PG_CLEAN bit, updates the cinfo count of
 856 * number of outstanding requests requiring a commit as well as
 857 * the MM page stats.
 858 *
 859 * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 860 * nfs_page lock.
 861 */
 862void
 863nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 864			    struct nfs_commit_info *cinfo)
 865{
 866	set_bit(PG_CLEAN, &req->wb_flags);
 867	nfs_list_add_request(req, dst);
 868	atomic_long_inc(&cinfo->mds->ncommit);
 869}
 870EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 871
 872/**
 873 * nfs_request_add_commit_list - add request to a commit list
 874 * @req: pointer to a struct nfs_page
 875 * @cinfo: holds list lock and accounting info
 876 *
 877 * This sets the PG_CLEAN bit, updates the cinfo count of
 878 * number of outstanding requests requiring a commit as well as
 879 * the MM page stats.
 880 *
 881 * The caller must _not_ hold the cinfo->lock, but must be
 882 * holding the nfs_page lock.
 883 */
 884void
 885nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 886{
 887	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 888	nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 889	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 890	if (req->wb_page)
 891		nfs_mark_page_unstable(req->wb_page, cinfo);
 892}
 893EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 894
 895/**
 896 * nfs_request_remove_commit_list - Remove request from a commit list
 897 * @req: pointer to a nfs_page
 898 * @cinfo: holds list lock and accounting info
 899 *
 900 * This clears the PG_CLEAN bit, and updates the cinfo's count of
 901 * number of outstanding requests requiring a commit
 902 * It does not update the MM page stats.
 903 *
 904 * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 905 */
 906void
 907nfs_request_remove_commit_list(struct nfs_page *req,
 908			       struct nfs_commit_info *cinfo)
 909{
 910	if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 911		return;
 912	nfs_list_remove_request(req);
 913	atomic_long_dec(&cinfo->mds->ncommit);
 914}
 915EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 916
 917static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 918				      struct inode *inode)
 919{
 920	cinfo->inode = inode;
 921	cinfo->mds = &NFS_I(inode)->commit_info;
 922	cinfo->ds = pnfs_get_ds_info(inode);
 923	cinfo->dreq = NULL;
 924	cinfo->completion_ops = &nfs_commit_completion_ops;
 925}
 926
 927void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 928		    struct inode *inode,
 929		    struct nfs_direct_req *dreq)
 930{
 931	if (dreq)
 932		nfs_init_cinfo_from_dreq(cinfo, dreq);
 933	else
 934		nfs_init_cinfo_from_inode(cinfo, inode);
 935}
 936EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 937
 938/*
 939 * Add a request to the inode's commit list.
 940 */
 941void
 942nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 943			struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 944{
 945	if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 946		return;
 947	nfs_request_add_commit_list(req, cinfo);
 948}
 949
 950static void
 951nfs_clear_page_commit(struct page *page)
 952{
 953	dec_node_page_state(page, NR_WRITEBACK);
 954	dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 955		    WB_WRITEBACK);
 956}
 957
 958/* Called holding the request lock on @req */
 959static void
 960nfs_clear_request_commit(struct nfs_page *req)
 961{
 962	if (test_bit(PG_CLEAN, &req->wb_flags)) {
 963		struct nfs_open_context *ctx = nfs_req_openctx(req);
 964		struct inode *inode = d_inode(ctx->dentry);
 965		struct nfs_commit_info cinfo;
 966
 967		nfs_init_cinfo_from_inode(&cinfo, inode);
 968		mutex_lock(&NFS_I(inode)->commit_mutex);
 969		if (!pnfs_clear_request_commit(req, &cinfo)) {
 970			nfs_request_remove_commit_list(req, &cinfo);
 971		}
 972		mutex_unlock(&NFS_I(inode)->commit_mutex);
 973		nfs_clear_page_commit(req->wb_page);
 974	}
 975}
 976
 977int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 978{
 979	if (hdr->verf.committed == NFS_DATA_SYNC)
 980		return hdr->lseg == NULL;
 981	return hdr->verf.committed != NFS_FILE_SYNC;
 982}
 983
 984static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 985{
 986	nfs_io_completion_get(hdr->io_completion);
 987}
 988
 989static void nfs_write_completion(struct nfs_pgio_header *hdr)
 990{
 991	struct nfs_commit_info cinfo;
 992	unsigned long bytes = 0;
 993
 994	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 995		goto out;
 996	nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
 997	while (!list_empty(&hdr->pages)) {
 998		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 999
1000		bytes += req->wb_bytes;
1001		nfs_list_remove_request(req);
1002		if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1003		    (hdr->good_bytes < bytes)) {
1004			trace_nfs_comp_error(req, hdr->error);
1005			nfs_mapping_set_error(req->wb_page, hdr->error);
1006			goto remove_req;
1007		}
1008		if (nfs_write_need_commit(hdr)) {
1009			/* Reset wb_nio, since the write was successful. */
1010			req->wb_nio = 0;
1011			memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1012			nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1013				hdr->pgio_mirror_idx);
1014			goto next;
1015		}
1016remove_req:
1017		nfs_inode_remove_request(req);
1018next:
1019		nfs_end_page_writeback(req);
1020		nfs_release_request(req);
1021	}
1022out:
1023	nfs_io_completion_put(hdr->io_completion);
1024	hdr->release(hdr);
1025}
1026
1027unsigned long
1028nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1029{
1030	return atomic_long_read(&cinfo->mds->ncommit);
1031}
1032
1033/* NFS_I(cinfo->inode)->commit_mutex held by caller */
1034int
1035nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1036		     struct nfs_commit_info *cinfo, int max)
1037{
1038	struct nfs_page *req, *tmp;
1039	int ret = 0;
1040
1041restart:
1042	list_for_each_entry_safe(req, tmp, src, wb_list) {
1043		kref_get(&req->wb_kref);
1044		if (!nfs_lock_request(req)) {
1045			int status;
1046
1047			/* Prevent deadlock with nfs_lock_and_join_requests */
1048			if (!list_empty(dst)) {
1049				nfs_release_request(req);
1050				continue;
1051			}
1052			/* Ensure we make progress to prevent livelock */
1053			mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1054			status = nfs_wait_on_request(req);
1055			nfs_release_request(req);
1056			mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1057			if (status < 0)
1058				break;
1059			goto restart;
1060		}
1061		nfs_request_remove_commit_list(req, cinfo);
1062		clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1063		nfs_list_add_request(req, dst);
1064		ret++;
1065		if ((ret == max) && !cinfo->dreq)
1066			break;
1067		cond_resched();
1068	}
1069	return ret;
1070}
1071EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1072
1073/*
1074 * nfs_scan_commit - Scan an inode for commit requests
1075 * @inode: NFS inode to scan
1076 * @dst: mds destination list
1077 * @cinfo: mds and ds lists of reqs ready to commit
1078 *
1079 * Moves requests from the inode's 'commit' request list.
1080 * The requests are *not* checked to ensure that they form a contiguous set.
1081 */
1082int
1083nfs_scan_commit(struct inode *inode, struct list_head *dst,
1084		struct nfs_commit_info *cinfo)
1085{
1086	int ret = 0;
1087
1088	if (!atomic_long_read(&cinfo->mds->ncommit))
1089		return 0;
1090	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1091	if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1092		const int max = INT_MAX;
1093
1094		ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1095					   cinfo, max);
1096		ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1097	}
1098	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1099	return ret;
1100}
1101
1102/*
1103 * Search for an existing write request, and attempt to update
1104 * it to reflect a new dirty region on a given page.
1105 *
1106 * If the attempt fails, then the existing request is flushed out
1107 * to disk.
1108 */
1109static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1110		struct page *page,
1111		unsigned int offset,
1112		unsigned int bytes)
1113{
1114	struct nfs_page *req;
1115	unsigned int rqend;
1116	unsigned int end;
1117	int error;
1118
1119	end = offset + bytes;
1120
1121	req = nfs_lock_and_join_requests(page);
1122	if (IS_ERR_OR_NULL(req))
1123		return req;
1124
1125	rqend = req->wb_offset + req->wb_bytes;
1126	/*
1127	 * Tell the caller to flush out the request if
1128	 * the offsets are non-contiguous.
1129	 * Note: nfs_flush_incompatible() will already
1130	 * have flushed out requests having wrong owners.
1131	 */
1132	if (offset > rqend || end < req->wb_offset)
1133		goto out_flushme;
1134
1135	/* Okay, the request matches. Update the region */
1136	if (offset < req->wb_offset) {
1137		req->wb_offset = offset;
1138		req->wb_pgbase = offset;
1139	}
1140	if (end > rqend)
1141		req->wb_bytes = end - req->wb_offset;
1142	else
1143		req->wb_bytes = rqend - req->wb_offset;
1144	req->wb_nio = 0;
1145	return req;
1146out_flushme:
1147	/*
1148	 * Note: we mark the request dirty here because
1149	 * nfs_lock_and_join_requests() cannot preserve
1150	 * commit flags, so we have to replay the write.
1151	 */
1152	nfs_mark_request_dirty(req);
1153	nfs_unlock_and_release_request(req);
1154	error = nfs_wb_page(inode, page);
1155	return (error < 0) ? ERR_PTR(error) : NULL;
1156}
1157
1158/*
1159 * Try to update an existing write request, or create one if there is none.
1160 *
1161 * Note: Should always be called with the Page Lock held to prevent races
1162 * if we have to add a new request. Also assumes that the caller has
1163 * already called nfs_flush_incompatible() if necessary.
1164 */
1165static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1166		struct page *page, unsigned int offset, unsigned int bytes)
1167{
1168	struct inode *inode = page_file_mapping(page)->host;
1169	struct nfs_page	*req;
1170
1171	req = nfs_try_to_update_request(inode, page, offset, bytes);
1172	if (req != NULL)
1173		goto out;
1174	req = nfs_create_request(ctx, page, offset, bytes);
1175	if (IS_ERR(req))
1176		goto out;
1177	nfs_inode_add_request(inode, req);
1178out:
1179	return req;
1180}
1181
1182static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1183		unsigned int offset, unsigned int count)
1184{
1185	struct nfs_page	*req;
1186
1187	req = nfs_setup_write_request(ctx, page, offset, count);
1188	if (IS_ERR(req))
1189		return PTR_ERR(req);
1190	/* Update file length */
1191	nfs_grow_file(page, offset, count);
1192	nfs_mark_uptodate(req);
1193	nfs_mark_request_dirty(req);
1194	nfs_unlock_and_release_request(req);
1195	return 0;
1196}
1197
1198int nfs_flush_incompatible(struct file *file, struct page *page)
1199{
1200	struct nfs_open_context *ctx = nfs_file_open_context(file);
1201	struct nfs_lock_context *l_ctx;
1202	struct file_lock_context *flctx = file_inode(file)->i_flctx;
1203	struct nfs_page	*req;
1204	int do_flush, status;
1205	/*
1206	 * Look for a request corresponding to this page. If there
1207	 * is one, and it belongs to another file, we flush it out
1208	 * before we try to copy anything into the page. Do this
1209	 * due to the lack of an ACCESS-type call in NFSv2.
1210	 * Also do the same if we find a request from an existing
1211	 * dropped page.
1212	 */
1213	do {
1214		req = nfs_page_find_head_request(page);
1215		if (req == NULL)
1216			return 0;
1217		l_ctx = req->wb_lock_context;
1218		do_flush = req->wb_page != page ||
1219			!nfs_match_open_context(nfs_req_openctx(req), ctx);
1220		if (l_ctx && flctx &&
1221		    !(list_empty_careful(&flctx->flc_posix) &&
1222		      list_empty_careful(&flctx->flc_flock))) {
1223			do_flush |= l_ctx->lockowner != current->files;
1224		}
1225		nfs_release_request(req);
1226		if (!do_flush)
1227			return 0;
1228		status = nfs_wb_page(page_file_mapping(page)->host, page);
1229	} while (status == 0);
1230	return status;
1231}
1232
1233/*
1234 * Avoid buffered writes when a open context credential's key would
1235 * expire soon.
1236 *
1237 * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1238 *
1239 * Return 0 and set a credential flag which triggers the inode to flush
1240 * and performs  NFS_FILE_SYNC writes if the key will expired within
1241 * RPC_KEY_EXPIRE_TIMEO.
1242 */
1243int
1244nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1245{
1246	struct nfs_open_context *ctx = nfs_file_open_context(filp);
1247
1248	if (nfs_ctx_key_to_expire(ctx, inode) &&
1249	    !ctx->ll_cred)
1250		/* Already expired! */
1251		return -EACCES;
1252	return 0;
1253}
1254
1255/*
1256 * Test if the open context credential key is marked to expire soon.
1257 */
1258bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1259{
1260	struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1261	struct rpc_cred *cred = ctx->ll_cred;
1262	struct auth_cred acred = {
1263		.cred = ctx->cred,
1264	};
1265
1266	if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) {
1267		put_rpccred(cred);
1268		ctx->ll_cred = NULL;
1269		cred = NULL;
1270	}
1271	if (!cred)
1272		cred = auth->au_ops->lookup_cred(auth, &acred, 0);
1273	if (!cred || IS_ERR(cred))
1274		return true;
1275	ctx->ll_cred = cred;
1276	return !!(cred->cr_ops->crkey_timeout &&
1277		  cred->cr_ops->crkey_timeout(cred));
1278}
1279
1280/*
1281 * If the page cache is marked as unsafe or invalid, then we can't rely on
1282 * the PageUptodate() flag. In this case, we will need to turn off
1283 * write optimisations that depend on the page contents being correct.
1284 */
1285static bool nfs_write_pageuptodate(struct page *page, struct inode *inode,
1286				   unsigned int pagelen)
1287{
1288	struct nfs_inode *nfsi = NFS_I(inode);
1289
1290	if (nfs_have_delegated_attributes(inode))
1291		goto out;
1292	if (nfsi->cache_validity &
1293	    (NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_SIZE))
1294		return false;
1295	smp_rmb();
1296	if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags) && pagelen != 0)
1297		return false;
1298out:
1299	if (nfsi->cache_validity & NFS_INO_INVALID_DATA && pagelen != 0)
1300		return false;
1301	return PageUptodate(page) != 0;
1302}
1303
1304static bool
1305is_whole_file_wrlock(struct file_lock *fl)
1306{
1307	return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1308			fl->fl_type == F_WRLCK;
1309}
1310
1311/* If we know the page is up to date, and we're not using byte range locks (or
1312 * if we have the whole file locked for writing), it may be more efficient to
1313 * extend the write to cover the entire page in order to avoid fragmentation
1314 * inefficiencies.
1315 *
1316 * If the file is opened for synchronous writes then we can just skip the rest
1317 * of the checks.
1318 */
1319static int nfs_can_extend_write(struct file *file, struct page *page,
1320				struct inode *inode, unsigned int pagelen)
1321{
1322	int ret;
1323	struct file_lock_context *flctx = inode->i_flctx;
1324	struct file_lock *fl;
1325
1326	if (file->f_flags & O_DSYNC)
1327		return 0;
1328	if (!nfs_write_pageuptodate(page, inode, pagelen))
1329		return 0;
1330	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1331		return 1;
1332	if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1333		       list_empty_careful(&flctx->flc_posix)))
1334		return 1;
1335
1336	/* Check to see if there are whole file write locks */
1337	ret = 0;
1338	spin_lock(&flctx->flc_lock);
1339	if (!list_empty(&flctx->flc_posix)) {
1340		fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1341					fl_list);
1342		if (is_whole_file_wrlock(fl))
1343			ret = 1;
1344	} else if (!list_empty(&flctx->flc_flock)) {
1345		fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1346					fl_list);
1347		if (fl->fl_type == F_WRLCK)
1348			ret = 1;
1349	}
1350	spin_unlock(&flctx->flc_lock);
1351	return ret;
1352}
1353
1354/*
1355 * Update and possibly write a cached page of an NFS file.
1356 *
1357 * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1358 * things with a page scheduled for an RPC call (e.g. invalidate it).
1359 */
1360int nfs_updatepage(struct file *file, struct page *page,
1361		unsigned int offset, unsigned int count)
1362{
1363	struct nfs_open_context *ctx = nfs_file_open_context(file);
1364	struct address_space *mapping = page_file_mapping(page);
1365	struct inode	*inode = mapping->host;
1366	unsigned int	pagelen = nfs_page_length(page);
1367	int		status = 0;
1368
1369	nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1370
1371	dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1372		file, count, (long long)(page_file_offset(page) + offset));
1373
1374	if (!count)
1375		goto out;
1376
1377	if (nfs_can_extend_write(file, page, inode, pagelen)) {
1378		count = max(count + offset, pagelen);
1379		offset = 0;
1380	}
1381
1382	status = nfs_writepage_setup(ctx, page, offset, count);
1383	if (status < 0)
1384		nfs_set_pageerror(mapping);
1385	else
1386		__set_page_dirty_nobuffers(page);
1387out:
1388	dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1389			status, (long long)i_size_read(inode));
1390	return status;
1391}
1392
1393static int flush_task_priority(int how)
1394{
1395	switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1396		case FLUSH_HIGHPRI:
1397			return RPC_PRIORITY_HIGH;
1398		case FLUSH_LOWPRI:
1399			return RPC_PRIORITY_LOW;
1400	}
1401	return RPC_PRIORITY_NORMAL;
1402}
1403
1404static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1405			       struct rpc_message *msg,
1406			       const struct nfs_rpc_ops *rpc_ops,
1407			       struct rpc_task_setup *task_setup_data, int how)
1408{
1409	int priority = flush_task_priority(how);
1410
1411	task_setup_data->priority = priority;
1412	rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1413	trace_nfs_initiate_write(hdr);
 
1414}
1415
1416/* If a nfs_flush_* function fails, it should remove reqs from @head and
1417 * call this on each, which will prepare them to be retried on next
1418 * writeback using standard nfs.
1419 */
1420static void nfs_redirty_request(struct nfs_page *req)
1421{
1422	/* Bump the transmission count */
1423	req->wb_nio++;
1424	nfs_mark_request_dirty(req);
1425	set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1426	nfs_end_page_writeback(req);
1427	nfs_release_request(req);
1428}
1429
1430static void nfs_async_write_error(struct list_head *head, int error)
1431{
1432	struct nfs_page	*req;
1433
1434	while (!list_empty(head)) {
1435		req = nfs_list_entry(head->next);
1436		nfs_list_remove_request(req);
1437		if (nfs_error_is_fatal(error))
1438			nfs_write_error(req, error);
1439		else
1440			nfs_redirty_request(req);
1441	}
1442}
1443
1444static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1445{
1446	nfs_async_write_error(&hdr->pages, 0);
1447	filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1448			hdr->args.offset + hdr->args.count - 1);
1449}
1450
1451static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1452	.init_hdr = nfs_async_write_init,
1453	.error_cleanup = nfs_async_write_error,
1454	.completion = nfs_write_completion,
1455	.reschedule_io = nfs_async_write_reschedule_io,
1456};
1457
1458void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1459			       struct inode *inode, int ioflags, bool force_mds,
1460			       const struct nfs_pgio_completion_ops *compl_ops)
1461{
1462	struct nfs_server *server = NFS_SERVER(inode);
1463	const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1464
1465#ifdef CONFIG_NFS_V4_1
1466	if (server->pnfs_curr_ld && !force_mds)
1467		pg_ops = server->pnfs_curr_ld->pg_write_ops;
1468#endif
1469	nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1470			server->wsize, ioflags);
1471}
1472EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1473
1474void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1475{
1476	struct nfs_pgio_mirror *mirror;
1477
1478	if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1479		pgio->pg_ops->pg_cleanup(pgio);
1480
1481	pgio->pg_ops = &nfs_pgio_rw_ops;
1482
1483	nfs_pageio_stop_mirroring(pgio);
1484
1485	mirror = &pgio->pg_mirrors[0];
1486	mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1487}
1488EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1489
1490
1491void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1492{
1493	struct nfs_commit_data *data = calldata;
1494
1495	NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1496}
1497
1498/*
1499 * Special version of should_remove_suid() that ignores capabilities.
1500 */
1501static int nfs_should_remove_suid(const struct inode *inode)
1502{
1503	umode_t mode = inode->i_mode;
1504	int kill = 0;
1505
1506	/* suid always must be killed */
1507	if (unlikely(mode & S_ISUID))
1508		kill = ATTR_KILL_SUID;
1509
1510	/*
1511	 * sgid without any exec bits is just a mandatory locking mark; leave
1512	 * it alone.  If some exec bits are set, it's a real sgid; kill it.
1513	 */
1514	if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1515		kill |= ATTR_KILL_SGID;
1516
1517	if (unlikely(kill && S_ISREG(mode)))
1518		return kill;
1519
1520	return 0;
1521}
1522
1523static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1524		struct nfs_fattr *fattr)
1525{
1526	struct nfs_pgio_args *argp = &hdr->args;
1527	struct nfs_pgio_res *resp = &hdr->res;
1528	u64 size = argp->offset + resp->count;
1529
1530	if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1531		fattr->size = size;
1532	if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1533		fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1534		return;
1535	}
1536	if (size != fattr->size)
1537		return;
1538	/* Set attribute barrier */
1539	nfs_fattr_set_barrier(fattr);
1540	/* ...and update size */
1541	fattr->valid |= NFS_ATTR_FATTR_SIZE;
1542}
1543
1544void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1545{
1546	struct nfs_fattr *fattr = &hdr->fattr;
1547	struct inode *inode = hdr->inode;
1548
1549	spin_lock(&inode->i_lock);
1550	nfs_writeback_check_extend(hdr, fattr);
1551	nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1552	spin_unlock(&inode->i_lock);
1553}
1554EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1555
1556/*
1557 * This function is called when the WRITE call is complete.
1558 */
1559static int nfs_writeback_done(struct rpc_task *task,
1560			      struct nfs_pgio_header *hdr,
1561			      struct inode *inode)
1562{
1563	int status;
1564
1565	/*
1566	 * ->write_done will attempt to use post-op attributes to detect
1567	 * conflicting writes by other clients.  A strict interpretation
1568	 * of close-to-open would allow us to continue caching even if
1569	 * another writer had changed the file, but some applications
1570	 * depend on tighter cache coherency when writing.
1571	 */
1572	status = NFS_PROTO(inode)->write_done(task, hdr);
1573	if (status != 0)
1574		return status;
1575
1576	nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1577	trace_nfs_writeback_done(task, hdr);
 
1578
1579	if (hdr->res.verf->committed < hdr->args.stable &&
1580	    task->tk_status >= 0) {
1581		/* We tried a write call, but the server did not
1582		 * commit data to stable storage even though we
1583		 * requested it.
1584		 * Note: There is a known bug in Tru64 < 5.0 in which
1585		 *	 the server reports NFS_DATA_SYNC, but performs
1586		 *	 NFS_FILE_SYNC. We therefore implement this checking
1587		 *	 as a dprintk() in order to avoid filling syslog.
1588		 */
1589		static unsigned long    complain;
1590
1591		/* Note this will print the MDS for a DS write */
1592		if (time_before(complain, jiffies)) {
1593			dprintk("NFS:       faulty NFS server %s:"
1594				" (committed = %d) != (stable = %d)\n",
1595				NFS_SERVER(inode)->nfs_client->cl_hostname,
1596				hdr->res.verf->committed, hdr->args.stable);
1597			complain = jiffies + 300 * HZ;
1598		}
1599	}
1600
1601	/* Deal with the suid/sgid bit corner case */
1602	if (nfs_should_remove_suid(inode)) {
1603		spin_lock(&inode->i_lock);
1604		nfs_set_cache_invalid(inode, NFS_INO_INVALID_MODE);
1605		spin_unlock(&inode->i_lock);
1606	}
1607	return 0;
1608}
1609
1610/*
1611 * This function is called when the WRITE call is complete.
1612 */
1613static void nfs_writeback_result(struct rpc_task *task,
1614				 struct nfs_pgio_header *hdr)
1615{
1616	struct nfs_pgio_args	*argp = &hdr->args;
1617	struct nfs_pgio_res	*resp = &hdr->res;
1618
1619	if (resp->count < argp->count) {
1620		static unsigned long    complain;
1621
1622		/* This a short write! */
1623		nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1624
1625		/* Has the server at least made some progress? */
1626		if (resp->count == 0) {
1627			if (time_before(complain, jiffies)) {
1628				printk(KERN_WARNING
1629				       "NFS: Server wrote zero bytes, expected %u.\n",
1630				       argp->count);
1631				complain = jiffies + 300 * HZ;
1632			}
1633			nfs_set_pgio_error(hdr, -EIO, argp->offset);
1634			task->tk_status = -EIO;
1635			return;
1636		}
1637
1638		/* For non rpc-based layout drivers, retry-through-MDS */
1639		if (!task->tk_ops) {
1640			hdr->pnfs_error = -EAGAIN;
1641			return;
1642		}
1643
1644		/* Was this an NFSv2 write or an NFSv3 stable write? */
1645		if (resp->verf->committed != NFS_UNSTABLE) {
1646			/* Resend from where the server left off */
1647			hdr->mds_offset += resp->count;
1648			argp->offset += resp->count;
1649			argp->pgbase += resp->count;
1650			argp->count -= resp->count;
1651		} else {
1652			/* Resend as a stable write in order to avoid
1653			 * headaches in the case of a server crash.
1654			 */
1655			argp->stable = NFS_FILE_SYNC;
1656		}
1657		resp->count = 0;
1658		resp->verf->committed = 0;
1659		rpc_restart_call_prepare(task);
1660	}
1661}
1662
1663static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1664{
1665	return wait_var_event_killable(&cinfo->rpcs_out,
1666				       !atomic_read(&cinfo->rpcs_out));
1667}
1668
1669static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1670{
1671	atomic_inc(&cinfo->rpcs_out);
1672}
1673
1674static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1675{
1676	if (atomic_dec_and_test(&cinfo->rpcs_out))
1677		wake_up_var(&cinfo->rpcs_out);
1678}
1679
1680void nfs_commitdata_release(struct nfs_commit_data *data)
1681{
1682	put_nfs_open_context(data->context);
1683	nfs_commit_free(data);
1684}
1685EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1686
1687int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1688			const struct nfs_rpc_ops *nfs_ops,
1689			const struct rpc_call_ops *call_ops,
1690			int how, int flags)
1691{
1692	struct rpc_task *task;
1693	int priority = flush_task_priority(how);
1694	struct rpc_message msg = {
1695		.rpc_argp = &data->args,
1696		.rpc_resp = &data->res,
1697		.rpc_cred = data->cred,
1698	};
1699	struct rpc_task_setup task_setup_data = {
1700		.task = &data->task,
1701		.rpc_client = clnt,
1702		.rpc_message = &msg,
1703		.callback_ops = call_ops,
1704		.callback_data = data,
1705		.workqueue = nfsiod_workqueue,
1706		.flags = RPC_TASK_ASYNC | flags,
1707		.priority = priority,
1708	};
1709	/* Set up the initial task struct.  */
1710	nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1711	trace_nfs_initiate_commit(data);
1712
1713	dprintk("NFS: initiated commit call\n");
1714
1715	task = rpc_run_task(&task_setup_data);
1716	if (IS_ERR(task))
1717		return PTR_ERR(task);
1718	if (how & FLUSH_SYNC)
1719		rpc_wait_for_completion_task(task);
1720	rpc_put_task(task);
1721	return 0;
1722}
1723EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1724
1725static loff_t nfs_get_lwb(struct list_head *head)
1726{
1727	loff_t lwb = 0;
1728	struct nfs_page *req;
1729
1730	list_for_each_entry(req, head, wb_list)
1731		if (lwb < (req_offset(req) + req->wb_bytes))
1732			lwb = req_offset(req) + req->wb_bytes;
1733
1734	return lwb;
1735}
1736
1737/*
1738 * Set up the argument/result storage required for the RPC call.
1739 */
1740void nfs_init_commit(struct nfs_commit_data *data,
1741		     struct list_head *head,
1742		     struct pnfs_layout_segment *lseg,
1743		     struct nfs_commit_info *cinfo)
1744{
1745	struct nfs_page *first;
1746	struct nfs_open_context *ctx;
1747	struct inode *inode;
1748
1749	/* Set up the RPC argument and reply structs
1750	 * NB: take care not to mess about with data->commit et al. */
1751
1752	if (head)
1753		list_splice_init(head, &data->pages);
1754
1755	first = nfs_list_entry(data->pages.next);
1756	ctx = nfs_req_openctx(first);
1757	inode = d_inode(ctx->dentry);
1758
1759	data->inode	  = inode;
1760	data->cred	  = ctx->cred;
1761	data->lseg	  = lseg; /* reference transferred */
1762	/* only set lwb for pnfs commit */
1763	if (lseg)
1764		data->lwb = nfs_get_lwb(&data->pages);
1765	data->mds_ops     = &nfs_commit_ops;
1766	data->completion_ops = cinfo->completion_ops;
1767	data->dreq	  = cinfo->dreq;
1768
1769	data->args.fh     = NFS_FH(data->inode);
1770	/* Note: we always request a commit of the entire inode */
1771	data->args.offset = 0;
1772	data->args.count  = 0;
1773	data->context     = get_nfs_open_context(ctx);
1774	data->res.fattr   = &data->fattr;
1775	data->res.verf    = &data->verf;
1776	nfs_fattr_init(&data->fattr);
1777}
1778EXPORT_SYMBOL_GPL(nfs_init_commit);
1779
1780void nfs_retry_commit(struct list_head *page_list,
1781		      struct pnfs_layout_segment *lseg,
1782		      struct nfs_commit_info *cinfo,
1783		      u32 ds_commit_idx)
1784{
1785	struct nfs_page *req;
1786
1787	while (!list_empty(page_list)) {
1788		req = nfs_list_entry(page_list->next);
1789		nfs_list_remove_request(req);
1790		nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1791		if (!cinfo->dreq)
1792			nfs_clear_page_commit(req->wb_page);
1793		nfs_unlock_and_release_request(req);
1794	}
1795}
1796EXPORT_SYMBOL_GPL(nfs_retry_commit);
1797
1798static void
1799nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1800		struct nfs_page *req)
1801{
1802	__set_page_dirty_nobuffers(req->wb_page);
1803}
1804
1805/*
1806 * Commit dirty pages
1807 */
1808static int
1809nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1810		struct nfs_commit_info *cinfo)
1811{
1812	struct nfs_commit_data	*data;
1813	unsigned short task_flags = 0;
1814
1815	/* another commit raced with us */
1816	if (list_empty(head))
1817		return 0;
1818
1819	data = nfs_commitdata_alloc(true);
1820
1821	/* Set up the argument struct */
1822	nfs_init_commit(data, head, NULL, cinfo);
1823	atomic_inc(&cinfo->mds->rpcs_out);
1824	if (NFS_SERVER(inode)->nfs_client->cl_minorversion)
1825		task_flags = RPC_TASK_MOVEABLE;
1826	return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1827				   data->mds_ops, how,
1828				   RPC_TASK_CRED_NOREF | task_flags);
1829}
1830
1831/*
1832 * COMMIT call returned
1833 */
1834static void nfs_commit_done(struct rpc_task *task, void *calldata)
1835{
1836	struct nfs_commit_data	*data = calldata;
1837
1838        dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1839                                task->tk_pid, task->tk_status);
1840
1841	/* Call the NFS version-specific code */
1842	NFS_PROTO(data->inode)->commit_done(task, data);
1843	trace_nfs_commit_done(task, data);
1844}
1845
1846static void nfs_commit_release_pages(struct nfs_commit_data *data)
1847{
1848	const struct nfs_writeverf *verf = data->res.verf;
1849	struct nfs_page	*req;
1850	int status = data->task.tk_status;
1851	struct nfs_commit_info cinfo;
1852	struct nfs_server *nfss;
1853
1854	while (!list_empty(&data->pages)) {
1855		req = nfs_list_entry(data->pages.next);
1856		nfs_list_remove_request(req);
1857		if (req->wb_page)
1858			nfs_clear_page_commit(req->wb_page);
1859
1860		dprintk("NFS:       commit (%s/%llu %d@%lld)",
1861			nfs_req_openctx(req)->dentry->d_sb->s_id,
1862			(unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1863			req->wb_bytes,
1864			(long long)req_offset(req));
1865		if (status < 0) {
1866			if (req->wb_page) {
1867				trace_nfs_commit_error(req, status);
1868				nfs_mapping_set_error(req->wb_page, status);
1869				nfs_inode_remove_request(req);
1870			}
1871			dprintk_cont(", error = %d\n", status);
1872			goto next;
1873		}
1874
1875		/* Okay, COMMIT succeeded, apparently. Check the verifier
1876		 * returned by the server against all stored verfs. */
1877		if (nfs_write_match_verf(verf, req)) {
1878			/* We have a match */
1879			if (req->wb_page)
1880				nfs_inode_remove_request(req);
1881			dprintk_cont(" OK\n");
1882			goto next;
1883		}
1884		/* We have a mismatch. Write the page again */
1885		dprintk_cont(" mismatch\n");
1886		nfs_mark_request_dirty(req);
1887		set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1888	next:
1889		nfs_unlock_and_release_request(req);
1890		/* Latency breaker */
1891		cond_resched();
1892	}
1893	nfss = NFS_SERVER(data->inode);
1894	if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1895		clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1896
1897	nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1898	nfs_commit_end(cinfo.mds);
1899}
1900
1901static void nfs_commit_release(void *calldata)
1902{
1903	struct nfs_commit_data *data = calldata;
1904
1905	data->completion_ops->completion(data);
1906	nfs_commitdata_release(calldata);
1907}
1908
1909static const struct rpc_call_ops nfs_commit_ops = {
1910	.rpc_call_prepare = nfs_commit_prepare,
1911	.rpc_call_done = nfs_commit_done,
1912	.rpc_release = nfs_commit_release,
1913};
1914
1915static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1916	.completion = nfs_commit_release_pages,
1917	.resched_write = nfs_commit_resched_write,
1918};
1919
1920int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1921			    int how, struct nfs_commit_info *cinfo)
1922{
1923	int status;
1924
1925	status = pnfs_commit_list(inode, head, how, cinfo);
1926	if (status == PNFS_NOT_ATTEMPTED)
1927		status = nfs_commit_list(inode, head, how, cinfo);
1928	return status;
1929}
1930
1931static int __nfs_commit_inode(struct inode *inode, int how,
1932		struct writeback_control *wbc)
1933{
1934	LIST_HEAD(head);
1935	struct nfs_commit_info cinfo;
1936	int may_wait = how & FLUSH_SYNC;
1937	int ret, nscan;
1938
1939	nfs_init_cinfo_from_inode(&cinfo, inode);
1940	nfs_commit_begin(cinfo.mds);
1941	for (;;) {
1942		ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1943		if (ret <= 0)
1944			break;
1945		ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1946		if (ret < 0)
1947			break;
1948		ret = 0;
1949		if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1950			if (nscan < wbc->nr_to_write)
1951				wbc->nr_to_write -= nscan;
1952			else
1953				wbc->nr_to_write = 0;
1954		}
1955		if (nscan < INT_MAX)
1956			break;
1957		cond_resched();
1958	}
1959	nfs_commit_end(cinfo.mds);
1960	if (ret || !may_wait)
1961		return ret;
1962	return wait_on_commit(cinfo.mds);
1963}
1964
1965int nfs_commit_inode(struct inode *inode, int how)
1966{
1967	return __nfs_commit_inode(inode, how, NULL);
1968}
1969EXPORT_SYMBOL_GPL(nfs_commit_inode);
1970
1971int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1972{
1973	struct nfs_inode *nfsi = NFS_I(inode);
1974	int flags = FLUSH_SYNC;
1975	int ret = 0;
1976
1977	if (wbc->sync_mode == WB_SYNC_NONE) {
1978		/* no commits means nothing needs to be done */
1979		if (!atomic_long_read(&nfsi->commit_info.ncommit))
1980			goto check_requests_outstanding;
1981
1982		/* Don't commit yet if this is a non-blocking flush and there
1983		 * are a lot of outstanding writes for this mapping.
1984		 */
1985		if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1986			goto out_mark_dirty;
1987
1988		/* don't wait for the COMMIT response */
1989		flags = 0;
1990	}
1991
1992	ret = __nfs_commit_inode(inode, flags, wbc);
1993	if (!ret) {
1994		if (flags & FLUSH_SYNC)
1995			return 0;
1996	} else if (atomic_long_read(&nfsi->commit_info.ncommit))
1997		goto out_mark_dirty;
1998
1999check_requests_outstanding:
2000	if (!atomic_read(&nfsi->commit_info.rpcs_out))
2001		return ret;
2002out_mark_dirty:
2003	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
2004	return ret;
2005}
2006EXPORT_SYMBOL_GPL(nfs_write_inode);
2007
2008/*
2009 * Wrapper for filemap_write_and_wait_range()
2010 *
2011 * Needed for pNFS in order to ensure data becomes visible to the
2012 * client.
2013 */
2014int nfs_filemap_write_and_wait_range(struct address_space *mapping,
2015		loff_t lstart, loff_t lend)
2016{
2017	int ret;
2018
2019	ret = filemap_write_and_wait_range(mapping, lstart, lend);
2020	if (ret == 0)
2021		ret = pnfs_sync_inode(mapping->host, true);
2022	return ret;
2023}
2024EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2025
2026/*
2027 * flush the inode to disk.
2028 */
2029int nfs_wb_all(struct inode *inode)
2030{
2031	int ret;
2032
2033	trace_nfs_writeback_inode_enter(inode);
2034
2035	ret = filemap_write_and_wait(inode->i_mapping);
2036	if (ret)
2037		goto out;
2038	ret = nfs_commit_inode(inode, FLUSH_SYNC);
2039	if (ret < 0)
2040		goto out;
2041	pnfs_sync_inode(inode, true);
2042	ret = 0;
2043
2044out:
2045	trace_nfs_writeback_inode_exit(inode, ret);
2046	return ret;
2047}
2048EXPORT_SYMBOL_GPL(nfs_wb_all);
2049
2050int nfs_wb_page_cancel(struct inode *inode, struct page *page)
2051{
2052	struct nfs_page *req;
2053	int ret = 0;
2054
2055	wait_on_page_writeback(page);
2056
2057	/* blocking call to cancel all requests and join to a single (head)
2058	 * request */
2059	req = nfs_lock_and_join_requests(page);
2060
2061	if (IS_ERR(req)) {
2062		ret = PTR_ERR(req);
2063	} else if (req) {
2064		/* all requests from this page have been cancelled by
2065		 * nfs_lock_and_join_requests, so just remove the head
2066		 * request from the inode / page_private pointer and
2067		 * release it */
2068		nfs_inode_remove_request(req);
2069		nfs_unlock_and_release_request(req);
2070	}
2071
2072	return ret;
2073}
2074
2075/*
2076 * Write back all requests on one page - we do this before reading it.
2077 */
2078int nfs_wb_page(struct inode *inode, struct page *page)
2079{
2080	loff_t range_start = page_file_offset(page);
2081	loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2082	struct writeback_control wbc = {
2083		.sync_mode = WB_SYNC_ALL,
2084		.nr_to_write = 0,
2085		.range_start = range_start,
2086		.range_end = range_end,
2087	};
2088	int ret;
2089
2090	trace_nfs_writeback_page_enter(inode);
2091
2092	for (;;) {
2093		wait_on_page_writeback(page);
2094		if (clear_page_dirty_for_io(page)) {
2095			ret = nfs_writepage_locked(page, &wbc);
2096			if (ret < 0)
2097				goto out_error;
2098			continue;
2099		}
2100		ret = 0;
2101		if (!PagePrivate(page))
2102			break;
2103		ret = nfs_commit_inode(inode, FLUSH_SYNC);
2104		if (ret < 0)
2105			goto out_error;
2106	}
2107out_error:
2108	trace_nfs_writeback_page_exit(inode, ret);
2109	return ret;
2110}
2111
2112#ifdef CONFIG_MIGRATION
2113int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2114		struct page *page, enum migrate_mode mode)
2115{
2116	/*
2117	 * If PagePrivate is set, then the page is currently associated with
2118	 * an in-progress read or write request. Don't try to migrate it.
2119	 *
2120	 * FIXME: we could do this in principle, but we'll need a way to ensure
2121	 *        that we can safely release the inode reference while holding
2122	 *        the page lock.
2123	 */
2124	if (PagePrivate(page))
2125		return -EBUSY;
2126
2127	if (!nfs_fscache_release_page(page, GFP_KERNEL))
2128		return -EBUSY;
2129
2130	return migrate_page(mapping, newpage, page, mode);
2131}
2132#endif
2133
2134int __init nfs_init_writepagecache(void)
2135{
2136	nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2137					     sizeof(struct nfs_pgio_header),
2138					     0, SLAB_HWCACHE_ALIGN,
2139					     NULL);
2140	if (nfs_wdata_cachep == NULL)
2141		return -ENOMEM;
2142
2143	nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2144						     nfs_wdata_cachep);
2145	if (nfs_wdata_mempool == NULL)
2146		goto out_destroy_write_cache;
2147
2148	nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2149					     sizeof(struct nfs_commit_data),
2150					     0, SLAB_HWCACHE_ALIGN,
2151					     NULL);
2152	if (nfs_cdata_cachep == NULL)
2153		goto out_destroy_write_mempool;
2154
2155	nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2156						      nfs_cdata_cachep);
2157	if (nfs_commit_mempool == NULL)
2158		goto out_destroy_commit_cache;
2159
2160	/*
2161	 * NFS congestion size, scale with available memory.
2162	 *
2163	 *  64MB:    8192k
2164	 * 128MB:   11585k
2165	 * 256MB:   16384k
2166	 * 512MB:   23170k
2167	 *   1GB:   32768k
2168	 *   2GB:   46340k
2169	 *   4GB:   65536k
2170	 *   8GB:   92681k
2171	 *  16GB:  131072k
2172	 *
2173	 * This allows larger machines to have larger/more transfers.
2174	 * Limit the default to 256M
2175	 */
2176	nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2177	if (nfs_congestion_kb > 256*1024)
2178		nfs_congestion_kb = 256*1024;
2179
2180	return 0;
2181
2182out_destroy_commit_cache:
2183	kmem_cache_destroy(nfs_cdata_cachep);
2184out_destroy_write_mempool:
2185	mempool_destroy(nfs_wdata_mempool);
2186out_destroy_write_cache:
2187	kmem_cache_destroy(nfs_wdata_cachep);
2188	return -ENOMEM;
2189}
2190
2191void nfs_destroy_writepagecache(void)
2192{
2193	mempool_destroy(nfs_commit_mempool);
2194	kmem_cache_destroy(nfs_cdata_cachep);
2195	mempool_destroy(nfs_wdata_mempool);
2196	kmem_cache_destroy(nfs_wdata_cachep);
2197}
2198
2199static const struct nfs_rw_ops nfs_rw_write_ops = {
2200	.rw_alloc_header	= nfs_writehdr_alloc,
2201	.rw_free_header		= nfs_writehdr_free,
2202	.rw_done		= nfs_writeback_done,
2203	.rw_result		= nfs_writeback_result,
2204	.rw_initiate		= nfs_initiate_write,
2205};