xref: /openbmc/linux/fs/nfs/write.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * linux/fs/nfs/write.c
3  *
4  * Write file data over NFS.
5  *
6  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #include <linux/types.h>
10 #include <linux/slab.h>
11 #include <linux/mm.h>
12 #include <linux/pagemap.h>
13 #include <linux/file.h>
14 #include <linux/writeback.h>
15 #include <linux/swap.h>
16 
17 #include <linux/sunrpc/clnt.h>
18 #include <linux/nfs_fs.h>
19 #include <linux/nfs_mount.h>
20 #include <linux/nfs_page.h>
21 #include <linux/backing-dev.h>
22 
23 #include <asm/uaccess.h>
24 
25 #include "delegation.h"
26 #include "internal.h"
27 #include "iostat.h"
28 
29 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
30 
31 #define MIN_POOL_WRITE		(32)
32 #define MIN_POOL_COMMIT		(4)
33 
34 /*
35  * Local function declarations
36  */
37 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
38 					    struct page *,
39 					    unsigned int, unsigned int);
40 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
41 				  struct inode *inode, int ioflags);
42 static const struct rpc_call_ops nfs_write_partial_ops;
43 static const struct rpc_call_ops nfs_write_full_ops;
44 static const struct rpc_call_ops nfs_commit_ops;
45 
46 static struct kmem_cache *nfs_wdata_cachep;
47 static mempool_t *nfs_wdata_mempool;
48 static mempool_t *nfs_commit_mempool;
49 
50 struct nfs_write_data *nfs_commit_alloc(void)
51 {
52 	struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
53 
54 	if (p) {
55 		memset(p, 0, sizeof(*p));
56 		INIT_LIST_HEAD(&p->pages);
57 	}
58 	return p;
59 }
60 
61 void nfs_commit_rcu_free(struct rcu_head *head)
62 {
63 	struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
64 	if (p && (p->pagevec != &p->page_array[0]))
65 		kfree(p->pagevec);
66 	mempool_free(p, nfs_commit_mempool);
67 }
68 
69 void nfs_commit_free(struct nfs_write_data *wdata)
70 {
71 	call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
72 }
73 
74 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
75 {
76 	struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
77 
78 	if (p) {
79 		memset(p, 0, sizeof(*p));
80 		INIT_LIST_HEAD(&p->pages);
81 		p->npages = pagecount;
82 		if (pagecount <= ARRAY_SIZE(p->page_array))
83 			p->pagevec = p->page_array;
84 		else {
85 			p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
86 			if (!p->pagevec) {
87 				mempool_free(p, nfs_wdata_mempool);
88 				p = NULL;
89 			}
90 		}
91 	}
92 	return p;
93 }
94 
95 static void nfs_writedata_rcu_free(struct rcu_head *head)
96 {
97 	struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
98 	if (p && (p->pagevec != &p->page_array[0]))
99 		kfree(p->pagevec);
100 	mempool_free(p, nfs_wdata_mempool);
101 }
102 
103 static void nfs_writedata_free(struct nfs_write_data *wdata)
104 {
105 	call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
106 }
107 
108 void nfs_writedata_release(void *wdata)
109 {
110 	nfs_writedata_free(wdata);
111 }
112 
113 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
114 {
115 	struct nfs_page *req = NULL;
116 
117 	if (PagePrivate(page)) {
118 		req = (struct nfs_page *)page_private(page);
119 		if (req != NULL)
120 			atomic_inc(&req->wb_count);
121 	}
122 	return req;
123 }
124 
125 static struct nfs_page *nfs_page_find_request(struct page *page)
126 {
127 	struct nfs_page *req = NULL;
128 	spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
129 
130 	spin_lock(req_lock);
131 	req = nfs_page_find_request_locked(page);
132 	spin_unlock(req_lock);
133 	return req;
134 }
135 
136 /* Adjust the file length if we're writing beyond the end */
137 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
138 {
139 	struct inode *inode = page->mapping->host;
140 	loff_t end, i_size = i_size_read(inode);
141 	pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
142 
143 	if (i_size > 0 && page->index < end_index)
144 		return;
145 	end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
146 	if (i_size >= end)
147 		return;
148 	nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
149 	i_size_write(inode, end);
150 }
151 
152 /* A writeback failed: mark the page as bad, and invalidate the page cache */
153 static void nfs_set_pageerror(struct page *page)
154 {
155 	SetPageError(page);
156 	nfs_zap_mapping(page->mapping->host, page->mapping);
157 }
158 
159 /* We can set the PG_uptodate flag if we see that a write request
160  * covers the full page.
161  */
162 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
163 {
164 	if (PageUptodate(page))
165 		return;
166 	if (base != 0)
167 		return;
168 	if (count != nfs_page_length(page))
169 		return;
170 	if (count != PAGE_CACHE_SIZE)
171 		memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
172 	SetPageUptodate(page);
173 }
174 
175 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
176 		unsigned int offset, unsigned int count)
177 {
178 	struct nfs_page	*req;
179 	int ret;
180 
181 	for (;;) {
182 		req = nfs_update_request(ctx, page, offset, count);
183 		if (!IS_ERR(req))
184 			break;
185 		ret = PTR_ERR(req);
186 		if (ret != -EBUSY)
187 			return ret;
188 		ret = nfs_wb_page(page->mapping->host, page);
189 		if (ret != 0)
190 			return ret;
191 	}
192 	/* Update file length */
193 	nfs_grow_file(page, offset, count);
194 	/* Set the PG_uptodate flag? */
195 	nfs_mark_uptodate(page, offset, count);
196 	nfs_unlock_request(req);
197 	return 0;
198 }
199 
200 static int wb_priority(struct writeback_control *wbc)
201 {
202 	if (wbc->for_reclaim)
203 		return FLUSH_HIGHPRI | FLUSH_STABLE;
204 	if (wbc->for_kupdate)
205 		return FLUSH_LOWPRI;
206 	return 0;
207 }
208 
209 /*
210  * NFS congestion control
211  */
212 
213 int nfs_congestion_kb;
214 
215 #define NFS_CONGESTION_ON_THRESH 	(nfs_congestion_kb >> (PAGE_SHIFT-10))
216 #define NFS_CONGESTION_OFF_THRESH	\
217 	(NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
218 
219 static int nfs_set_page_writeback(struct page *page)
220 {
221 	int ret = test_set_page_writeback(page);
222 
223 	if (!ret) {
224 		struct inode *inode = page->mapping->host;
225 		struct nfs_server *nfss = NFS_SERVER(inode);
226 
227 		if (atomic_long_inc_return(&nfss->writeback) >
228 				NFS_CONGESTION_ON_THRESH)
229 			set_bdi_congested(&nfss->backing_dev_info, WRITE);
230 	}
231 	return ret;
232 }
233 
234 static void nfs_end_page_writeback(struct page *page)
235 {
236 	struct inode *inode = page->mapping->host;
237 	struct nfs_server *nfss = NFS_SERVER(inode);
238 
239 	end_page_writeback(page);
240 	if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
241 		clear_bdi_congested(&nfss->backing_dev_info, WRITE);
242 		congestion_end(WRITE);
243 	}
244 }
245 
246 /*
247  * Find an associated nfs write request, and prepare to flush it out
248  * Returns 1 if there was no write request, or if the request was
249  * already tagged by nfs_set_page_dirty.Returns 0 if the request
250  * was not tagged.
251  * May also return an error if the user signalled nfs_wait_on_request().
252  */
253 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
254 				struct page *page)
255 {
256 	struct nfs_page *req;
257 	struct nfs_inode *nfsi = NFS_I(page->mapping->host);
258 	spinlock_t *req_lock = &nfsi->req_lock;
259 	int ret;
260 
261 	spin_lock(req_lock);
262 	for(;;) {
263 		req = nfs_page_find_request_locked(page);
264 		if (req == NULL) {
265 			spin_unlock(req_lock);
266 			return 1;
267 		}
268 		if (nfs_lock_request_dontget(req))
269 			break;
270 		/* Note: If we hold the page lock, as is the case in nfs_writepage,
271 		 *	 then the call to nfs_lock_request_dontget() will always
272 		 *	 succeed provided that someone hasn't already marked the
273 		 *	 request as dirty (in which case we don't care).
274 		 */
275 		spin_unlock(req_lock);
276 		/* Prevent deadlock! */
277 		nfs_pageio_complete(pgio);
278 		ret = nfs_wait_on_request(req);
279 		nfs_release_request(req);
280 		if (ret != 0)
281 			return ret;
282 		spin_lock(req_lock);
283 	}
284 	if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
285 		/* This request is marked for commit */
286 		spin_unlock(req_lock);
287 		nfs_unlock_request(req);
288 		nfs_pageio_complete(pgio);
289 		return 1;
290 	}
291 	if (nfs_set_page_writeback(page) != 0) {
292 		spin_unlock(req_lock);
293 		BUG();
294 	}
295 	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
296 			NFS_PAGE_TAG_WRITEBACK);
297 	ret = test_bit(PG_NEED_FLUSH, &req->wb_flags);
298 	spin_unlock(req_lock);
299 	nfs_pageio_add_request(pgio, req);
300 	return ret;
301 }
302 
303 /*
304  * Write an mmapped page to the server.
305  */
306 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
307 {
308 	struct nfs_pageio_descriptor mypgio, *pgio;
309 	struct nfs_open_context *ctx;
310 	struct inode *inode = page->mapping->host;
311 	unsigned offset;
312 	int err;
313 
314 	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
315 	nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
316 
317 	if (wbc->for_writepages)
318 		pgio = wbc->fs_private;
319 	else {
320 		nfs_pageio_init_write(&mypgio, inode, wb_priority(wbc));
321 		pgio = &mypgio;
322 	}
323 
324 	err = nfs_page_async_flush(pgio, page);
325 	if (err <= 0)
326 		goto out;
327 	err = 0;
328 	offset = nfs_page_length(page);
329 	if (!offset)
330 		goto out;
331 
332 	ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
333 	if (ctx == NULL) {
334 		err = -EBADF;
335 		goto out;
336 	}
337 	err = nfs_writepage_setup(ctx, page, 0, offset);
338 	put_nfs_open_context(ctx);
339 	if (err != 0)
340 		goto out;
341 	err = nfs_page_async_flush(pgio, page);
342 	if (err > 0)
343 		err = 0;
344 out:
345 	if (!wbc->for_writepages)
346 		nfs_pageio_complete(pgio);
347 	return err;
348 }
349 
350 int nfs_writepage(struct page *page, struct writeback_control *wbc)
351 {
352 	int err;
353 
354 	err = nfs_writepage_locked(page, wbc);
355 	unlock_page(page);
356 	return err;
357 }
358 
359 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
360 {
361 	struct inode *inode = mapping->host;
362 	struct nfs_pageio_descriptor pgio;
363 	int err;
364 
365 	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
366 
367 	nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
368 	wbc->fs_private = &pgio;
369 	err = generic_writepages(mapping, wbc);
370 	nfs_pageio_complete(&pgio);
371 	if (err)
372 		return err;
373 	if (pgio.pg_error)
374 		return pgio.pg_error;
375 	return 0;
376 }
377 
378 /*
379  * Insert a write request into an inode
380  */
381 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
382 {
383 	struct nfs_inode *nfsi = NFS_I(inode);
384 	int error;
385 
386 	error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
387 	BUG_ON(error == -EEXIST);
388 	if (error)
389 		return error;
390 	if (!nfsi->npages) {
391 		igrab(inode);
392 		nfs_begin_data_update(inode);
393 		if (nfs_have_delegation(inode, FMODE_WRITE))
394 			nfsi->change_attr++;
395 	}
396 	SetPagePrivate(req->wb_page);
397 	set_page_private(req->wb_page, (unsigned long)req);
398 	if (PageDirty(req->wb_page))
399 		set_bit(PG_NEED_FLUSH, &req->wb_flags);
400 	nfsi->npages++;
401 	atomic_inc(&req->wb_count);
402 	return 0;
403 }
404 
405 /*
406  * Remove a write request from an inode
407  */
408 static void nfs_inode_remove_request(struct nfs_page *req)
409 {
410 	struct inode *inode = req->wb_context->dentry->d_inode;
411 	struct nfs_inode *nfsi = NFS_I(inode);
412 
413 	BUG_ON (!NFS_WBACK_BUSY(req));
414 
415 	spin_lock(&nfsi->req_lock);
416 	set_page_private(req->wb_page, 0);
417 	ClearPagePrivate(req->wb_page);
418 	radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
419 	if (test_and_clear_bit(PG_NEED_FLUSH, &req->wb_flags))
420 		__set_page_dirty_nobuffers(req->wb_page);
421 	nfsi->npages--;
422 	if (!nfsi->npages) {
423 		spin_unlock(&nfsi->req_lock);
424 		nfs_end_data_update(inode);
425 		iput(inode);
426 	} else
427 		spin_unlock(&nfsi->req_lock);
428 	nfs_clear_request(req);
429 	nfs_release_request(req);
430 }
431 
432 static void
433 nfs_redirty_request(struct nfs_page *req)
434 {
435 	__set_page_dirty_nobuffers(req->wb_page);
436 }
437 
438 /*
439  * Check if a request is dirty
440  */
441 static inline int
442 nfs_dirty_request(struct nfs_page *req)
443 {
444 	struct page *page = req->wb_page;
445 
446 	if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
447 		return 0;
448 	return !PageWriteback(req->wb_page);
449 }
450 
451 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
452 /*
453  * Add a request to the inode's commit list.
454  */
455 static void
456 nfs_mark_request_commit(struct nfs_page *req)
457 {
458 	struct inode *inode = req->wb_context->dentry->d_inode;
459 	struct nfs_inode *nfsi = NFS_I(inode);
460 
461 	spin_lock(&nfsi->req_lock);
462 	nfs_list_add_request(req, &nfsi->commit);
463 	nfsi->ncommit++;
464 	set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
465 	spin_unlock(&nfsi->req_lock);
466 	inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
467 	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
468 }
469 
470 static inline
471 int nfs_write_need_commit(struct nfs_write_data *data)
472 {
473 	return data->verf.committed != NFS_FILE_SYNC;
474 }
475 
476 static inline
477 int nfs_reschedule_unstable_write(struct nfs_page *req)
478 {
479 	if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
480 		nfs_mark_request_commit(req);
481 		return 1;
482 	}
483 	if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
484 		nfs_redirty_request(req);
485 		return 1;
486 	}
487 	return 0;
488 }
489 #else
490 static inline void
491 nfs_mark_request_commit(struct nfs_page *req)
492 {
493 }
494 
495 static inline
496 int nfs_write_need_commit(struct nfs_write_data *data)
497 {
498 	return 0;
499 }
500 
501 static inline
502 int nfs_reschedule_unstable_write(struct nfs_page *req)
503 {
504 	return 0;
505 }
506 #endif
507 
508 /*
509  * Wait for a request to complete.
510  *
511  * Interruptible by signals only if mounted with intr flag.
512  */
513 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
514 {
515 	struct nfs_inode *nfsi = NFS_I(inode);
516 	struct nfs_page *req;
517 	pgoff_t idx_end, next;
518 	unsigned int		res = 0;
519 	int			error;
520 
521 	if (npages == 0)
522 		idx_end = ~0;
523 	else
524 		idx_end = idx_start + npages - 1;
525 
526 	next = idx_start;
527 	while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
528 		if (req->wb_index > idx_end)
529 			break;
530 
531 		next = req->wb_index + 1;
532 		BUG_ON(!NFS_WBACK_BUSY(req));
533 
534 		atomic_inc(&req->wb_count);
535 		spin_unlock(&nfsi->req_lock);
536 		error = nfs_wait_on_request(req);
537 		nfs_release_request(req);
538 		spin_lock(&nfsi->req_lock);
539 		if (error < 0)
540 			return error;
541 		res++;
542 	}
543 	return res;
544 }
545 
546 static void nfs_cancel_commit_list(struct list_head *head)
547 {
548 	struct nfs_page *req;
549 
550 	while(!list_empty(head)) {
551 		req = nfs_list_entry(head->next);
552 		dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
553 		nfs_list_remove_request(req);
554 		clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
555 		nfs_inode_remove_request(req);
556 		nfs_unlock_request(req);
557 	}
558 }
559 
560 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
561 /*
562  * nfs_scan_commit - Scan an inode for commit requests
563  * @inode: NFS inode to scan
564  * @dst: destination list
565  * @idx_start: lower bound of page->index to scan.
566  * @npages: idx_start + npages sets the upper bound to scan.
567  *
568  * Moves requests from the inode's 'commit' request list.
569  * The requests are *not* checked to ensure that they form a contiguous set.
570  */
571 static int
572 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
573 {
574 	struct nfs_inode *nfsi = NFS_I(inode);
575 	int res = 0;
576 
577 	if (nfsi->ncommit != 0) {
578 		res = nfs_scan_list(nfsi, &nfsi->commit, dst, idx_start, npages);
579 		nfsi->ncommit -= res;
580 		if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
581 			printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
582 	}
583 	return res;
584 }
585 #else
586 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
587 {
588 	return 0;
589 }
590 #endif
591 
592 /*
593  * Try to update any existing write request, or create one if there is none.
594  * In order to match, the request's credentials must match those of
595  * the calling process.
596  *
597  * Note: Should always be called with the Page Lock held!
598  */
599 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
600 		struct page *page, unsigned int offset, unsigned int bytes)
601 {
602 	struct address_space *mapping = page->mapping;
603 	struct inode *inode = mapping->host;
604 	struct nfs_inode *nfsi = NFS_I(inode);
605 	struct nfs_page		*req, *new = NULL;
606 	pgoff_t		rqend, end;
607 
608 	end = offset + bytes;
609 
610 	for (;;) {
611 		/* Loop over all inode entries and see if we find
612 		 * A request for the page we wish to update
613 		 */
614 		spin_lock(&nfsi->req_lock);
615 		req = nfs_page_find_request_locked(page);
616 		if (req) {
617 			if (!nfs_lock_request_dontget(req)) {
618 				int error;
619 
620 				spin_unlock(&nfsi->req_lock);
621 				error = nfs_wait_on_request(req);
622 				nfs_release_request(req);
623 				if (error < 0) {
624 					if (new)
625 						nfs_release_request(new);
626 					return ERR_PTR(error);
627 				}
628 				continue;
629 			}
630 			spin_unlock(&nfsi->req_lock);
631 			if (new)
632 				nfs_release_request(new);
633 			break;
634 		}
635 
636 		if (new) {
637 			int error;
638 			nfs_lock_request_dontget(new);
639 			error = nfs_inode_add_request(inode, new);
640 			if (error) {
641 				spin_unlock(&nfsi->req_lock);
642 				nfs_unlock_request(new);
643 				return ERR_PTR(error);
644 			}
645 			spin_unlock(&nfsi->req_lock);
646 			return new;
647 		}
648 		spin_unlock(&nfsi->req_lock);
649 
650 		new = nfs_create_request(ctx, inode, page, offset, bytes);
651 		if (IS_ERR(new))
652 			return new;
653 	}
654 
655 	/* We have a request for our page.
656 	 * If the creds don't match, or the
657 	 * page addresses don't match,
658 	 * tell the caller to wait on the conflicting
659 	 * request.
660 	 */
661 	rqend = req->wb_offset + req->wb_bytes;
662 	if (req->wb_context != ctx
663 	    || req->wb_page != page
664 	    || !nfs_dirty_request(req)
665 	    || offset > rqend || end < req->wb_offset) {
666 		nfs_unlock_request(req);
667 		return ERR_PTR(-EBUSY);
668 	}
669 
670 	/* Okay, the request matches. Update the region */
671 	if (offset < req->wb_offset) {
672 		req->wb_offset = offset;
673 		req->wb_pgbase = offset;
674 		req->wb_bytes = rqend - req->wb_offset;
675 	}
676 
677 	if (end > rqend)
678 		req->wb_bytes = end - req->wb_offset;
679 
680 	return req;
681 }
682 
683 int nfs_flush_incompatible(struct file *file, struct page *page)
684 {
685 	struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
686 	struct nfs_page	*req;
687 	int do_flush, status;
688 	/*
689 	 * Look for a request corresponding to this page. If there
690 	 * is one, and it belongs to another file, we flush it out
691 	 * before we try to copy anything into the page. Do this
692 	 * due to the lack of an ACCESS-type call in NFSv2.
693 	 * Also do the same if we find a request from an existing
694 	 * dropped page.
695 	 */
696 	do {
697 		req = nfs_page_find_request(page);
698 		if (req == NULL)
699 			return 0;
700 		do_flush = req->wb_page != page || req->wb_context != ctx
701 			|| !nfs_dirty_request(req);
702 		nfs_release_request(req);
703 		if (!do_flush)
704 			return 0;
705 		status = nfs_wb_page(page->mapping->host, page);
706 	} while (status == 0);
707 	return status;
708 }
709 
710 /*
711  * Update and possibly write a cached page of an NFS file.
712  *
713  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
714  * things with a page scheduled for an RPC call (e.g. invalidate it).
715  */
716 int nfs_updatepage(struct file *file, struct page *page,
717 		unsigned int offset, unsigned int count)
718 {
719 	struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
720 	struct inode	*inode = page->mapping->host;
721 	int		status = 0;
722 
723 	nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
724 
725 	dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
726 		file->f_path.dentry->d_parent->d_name.name,
727 		file->f_path.dentry->d_name.name, count,
728 		(long long)(page_offset(page) +offset));
729 
730 	/* If we're not using byte range locks, and we know the page
731 	 * is entirely in cache, it may be more efficient to avoid
732 	 * fragmenting write requests.
733 	 */
734 	if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
735 		count = max(count + offset, nfs_page_length(page));
736 		offset = 0;
737 	}
738 
739 	status = nfs_writepage_setup(ctx, page, offset, count);
740 	__set_page_dirty_nobuffers(page);
741 
742         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
743 			status, (long long)i_size_read(inode));
744 	if (status < 0)
745 		nfs_set_pageerror(page);
746 	return status;
747 }
748 
749 static void nfs_writepage_release(struct nfs_page *req)
750 {
751 
752 	if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req)) {
753 		nfs_end_page_writeback(req->wb_page);
754 		nfs_inode_remove_request(req);
755 	} else
756 		nfs_end_page_writeback(req->wb_page);
757 	nfs_clear_page_writeback(req);
758 }
759 
760 static inline int flush_task_priority(int how)
761 {
762 	switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
763 		case FLUSH_HIGHPRI:
764 			return RPC_PRIORITY_HIGH;
765 		case FLUSH_LOWPRI:
766 			return RPC_PRIORITY_LOW;
767 	}
768 	return RPC_PRIORITY_NORMAL;
769 }
770 
771 /*
772  * Set up the argument/result storage required for the RPC call.
773  */
774 static void nfs_write_rpcsetup(struct nfs_page *req,
775 		struct nfs_write_data *data,
776 		const struct rpc_call_ops *call_ops,
777 		unsigned int count, unsigned int offset,
778 		int how)
779 {
780 	struct inode		*inode;
781 	int flags;
782 
783 	/* Set up the RPC argument and reply structs
784 	 * NB: take care not to mess about with data->commit et al. */
785 
786 	data->req = req;
787 	data->inode = inode = req->wb_context->dentry->d_inode;
788 	data->cred = req->wb_context->cred;
789 
790 	data->args.fh     = NFS_FH(inode);
791 	data->args.offset = req_offset(req) + offset;
792 	data->args.pgbase = req->wb_pgbase + offset;
793 	data->args.pages  = data->pagevec;
794 	data->args.count  = count;
795 	data->args.context = req->wb_context;
796 
797 	data->res.fattr   = &data->fattr;
798 	data->res.count   = count;
799 	data->res.verf    = &data->verf;
800 	nfs_fattr_init(&data->fattr);
801 
802 	/* Set up the initial task struct.  */
803 	flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
804 	rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
805 	NFS_PROTO(inode)->write_setup(data, how);
806 
807 	data->task.tk_priority = flush_task_priority(how);
808 	data->task.tk_cookie = (unsigned long)inode;
809 
810 	dprintk("NFS: %5u initiated write call "
811 		"(req %s/%Ld, %u bytes @ offset %Lu)\n",
812 		data->task.tk_pid,
813 		inode->i_sb->s_id,
814 		(long long)NFS_FILEID(inode),
815 		count,
816 		(unsigned long long)data->args.offset);
817 }
818 
819 static void nfs_execute_write(struct nfs_write_data *data)
820 {
821 	struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
822 	sigset_t oldset;
823 
824 	rpc_clnt_sigmask(clnt, &oldset);
825 	rpc_execute(&data->task);
826 	rpc_clnt_sigunmask(clnt, &oldset);
827 }
828 
829 /*
830  * Generate multiple small requests to write out a single
831  * contiguous dirty area on one page.
832  */
833 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
834 {
835 	struct nfs_page *req = nfs_list_entry(head->next);
836 	struct page *page = req->wb_page;
837 	struct nfs_write_data *data;
838 	size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
839 	unsigned int offset;
840 	int requests = 0;
841 	LIST_HEAD(list);
842 
843 	nfs_list_remove_request(req);
844 
845 	nbytes = count;
846 	do {
847 		size_t len = min(nbytes, wsize);
848 
849 		data = nfs_writedata_alloc(1);
850 		if (!data)
851 			goto out_bad;
852 		list_add(&data->pages, &list);
853 		requests++;
854 		nbytes -= len;
855 	} while (nbytes != 0);
856 	atomic_set(&req->wb_complete, requests);
857 
858 	ClearPageError(page);
859 	offset = 0;
860 	nbytes = count;
861 	do {
862 		data = list_entry(list.next, struct nfs_write_data, pages);
863 		list_del_init(&data->pages);
864 
865 		data->pagevec[0] = page;
866 
867 		if (nbytes < wsize)
868 			wsize = nbytes;
869 		nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
870 				   wsize, offset, how);
871 		offset += wsize;
872 		nbytes -= wsize;
873 		nfs_execute_write(data);
874 	} while (nbytes != 0);
875 
876 	return 0;
877 
878 out_bad:
879 	while (!list_empty(&list)) {
880 		data = list_entry(list.next, struct nfs_write_data, pages);
881 		list_del(&data->pages);
882 		nfs_writedata_release(data);
883 	}
884 	nfs_redirty_request(req);
885 	nfs_end_page_writeback(req->wb_page);
886 	nfs_clear_page_writeback(req);
887 	return -ENOMEM;
888 }
889 
890 /*
891  * Create an RPC task for the given write request and kick it.
892  * The page must have been locked by the caller.
893  *
894  * It may happen that the page we're passed is not marked dirty.
895  * This is the case if nfs_updatepage detects a conflicting request
896  * that has been written but not committed.
897  */
898 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
899 {
900 	struct nfs_page		*req;
901 	struct page		**pages;
902 	struct nfs_write_data	*data;
903 
904 	data = nfs_writedata_alloc(npages);
905 	if (!data)
906 		goto out_bad;
907 
908 	pages = data->pagevec;
909 	while (!list_empty(head)) {
910 		req = nfs_list_entry(head->next);
911 		nfs_list_remove_request(req);
912 		nfs_list_add_request(req, &data->pages);
913 		ClearPageError(req->wb_page);
914 		*pages++ = req->wb_page;
915 	}
916 	req = nfs_list_entry(data->pages.next);
917 
918 	/* Set up the argument struct */
919 	nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
920 
921 	nfs_execute_write(data);
922 	return 0;
923  out_bad:
924 	while (!list_empty(head)) {
925 		struct nfs_page *req = nfs_list_entry(head->next);
926 		nfs_list_remove_request(req);
927 		nfs_redirty_request(req);
928 		nfs_end_page_writeback(req->wb_page);
929 		nfs_clear_page_writeback(req);
930 	}
931 	return -ENOMEM;
932 }
933 
934 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
935 				  struct inode *inode, int ioflags)
936 {
937 	int wsize = NFS_SERVER(inode)->wsize;
938 
939 	if (wsize < PAGE_CACHE_SIZE)
940 		nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
941 	else
942 		nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
943 }
944 
945 /*
946  * Handle a write reply that flushed part of a page.
947  */
948 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
949 {
950 	struct nfs_write_data	*data = calldata;
951 	struct nfs_page		*req = data->req;
952 	struct page		*page = req->wb_page;
953 
954 	dprintk("NFS: write (%s/%Ld %d@%Ld)",
955 		req->wb_context->dentry->d_inode->i_sb->s_id,
956 		(long long)NFS_FILEID(req->wb_context->dentry->d_inode),
957 		req->wb_bytes,
958 		(long long)req_offset(req));
959 
960 	if (nfs_writeback_done(task, data) != 0)
961 		return;
962 
963 	if (task->tk_status < 0) {
964 		nfs_set_pageerror(page);
965 		req->wb_context->error = task->tk_status;
966 		dprintk(", error = %d\n", task->tk_status);
967 		goto out;
968 	}
969 
970 	if (nfs_write_need_commit(data)) {
971 		spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
972 
973 		spin_lock(req_lock);
974 		if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
975 			/* Do nothing we need to resend the writes */
976 		} else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
977 			memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
978 			dprintk(" defer commit\n");
979 		} else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
980 			set_bit(PG_NEED_RESCHED, &req->wb_flags);
981 			clear_bit(PG_NEED_COMMIT, &req->wb_flags);
982 			dprintk(" server reboot detected\n");
983 		}
984 		spin_unlock(req_lock);
985 	} else
986 		dprintk(" OK\n");
987 
988 out:
989 	if (atomic_dec_and_test(&req->wb_complete))
990 		nfs_writepage_release(req);
991 }
992 
993 static const struct rpc_call_ops nfs_write_partial_ops = {
994 	.rpc_call_done = nfs_writeback_done_partial,
995 	.rpc_release = nfs_writedata_release,
996 };
997 
998 /*
999  * Handle a write reply that flushes a whole page.
1000  *
1001  * FIXME: There is an inherent race with invalidate_inode_pages and
1002  *	  writebacks since the page->count is kept > 1 for as long
1003  *	  as the page has a write request pending.
1004  */
1005 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1006 {
1007 	struct nfs_write_data	*data = calldata;
1008 	struct nfs_page		*req;
1009 	struct page		*page;
1010 
1011 	if (nfs_writeback_done(task, data) != 0)
1012 		return;
1013 
1014 	/* Update attributes as result of writeback. */
1015 	while (!list_empty(&data->pages)) {
1016 		req = nfs_list_entry(data->pages.next);
1017 		nfs_list_remove_request(req);
1018 		page = req->wb_page;
1019 
1020 		dprintk("NFS: write (%s/%Ld %d@%Ld)",
1021 			req->wb_context->dentry->d_inode->i_sb->s_id,
1022 			(long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1023 			req->wb_bytes,
1024 			(long long)req_offset(req));
1025 
1026 		if (task->tk_status < 0) {
1027 			nfs_set_pageerror(page);
1028 			req->wb_context->error = task->tk_status;
1029 			dprintk(", error = %d\n", task->tk_status);
1030 			goto remove_request;
1031 		}
1032 
1033 		if (nfs_write_need_commit(data)) {
1034 			memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1035 			nfs_mark_request_commit(req);
1036 			nfs_end_page_writeback(page);
1037 			dprintk(" marked for commit\n");
1038 			goto next;
1039 		}
1040 		dprintk(" OK\n");
1041 remove_request:
1042 		nfs_end_page_writeback(page);
1043 		nfs_inode_remove_request(req);
1044 	next:
1045 		nfs_clear_page_writeback(req);
1046 	}
1047 }
1048 
1049 static const struct rpc_call_ops nfs_write_full_ops = {
1050 	.rpc_call_done = nfs_writeback_done_full,
1051 	.rpc_release = nfs_writedata_release,
1052 };
1053 
1054 
1055 /*
1056  * This function is called when the WRITE call is complete.
1057  */
1058 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1059 {
1060 	struct nfs_writeargs	*argp = &data->args;
1061 	struct nfs_writeres	*resp = &data->res;
1062 	int status;
1063 
1064 	dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1065 		task->tk_pid, task->tk_status);
1066 
1067 	/*
1068 	 * ->write_done will attempt to use post-op attributes to detect
1069 	 * conflicting writes by other clients.  A strict interpretation
1070 	 * of close-to-open would allow us to continue caching even if
1071 	 * another writer had changed the file, but some applications
1072 	 * depend on tighter cache coherency when writing.
1073 	 */
1074 	status = NFS_PROTO(data->inode)->write_done(task, data);
1075 	if (status != 0)
1076 		return status;
1077 	nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1078 
1079 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1080 	if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1081 		/* We tried a write call, but the server did not
1082 		 * commit data to stable storage even though we
1083 		 * requested it.
1084 		 * Note: There is a known bug in Tru64 < 5.0 in which
1085 		 *	 the server reports NFS_DATA_SYNC, but performs
1086 		 *	 NFS_FILE_SYNC. We therefore implement this checking
1087 		 *	 as a dprintk() in order to avoid filling syslog.
1088 		 */
1089 		static unsigned long    complain;
1090 
1091 		if (time_before(complain, jiffies)) {
1092 			dprintk("NFS: faulty NFS server %s:"
1093 				" (committed = %d) != (stable = %d)\n",
1094 				NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1095 				resp->verf->committed, argp->stable);
1096 			complain = jiffies + 300 * HZ;
1097 		}
1098 	}
1099 #endif
1100 	/* Is this a short write? */
1101 	if (task->tk_status >= 0 && resp->count < argp->count) {
1102 		static unsigned long    complain;
1103 
1104 		nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1105 
1106 		/* Has the server at least made some progress? */
1107 		if (resp->count != 0) {
1108 			/* Was this an NFSv2 write or an NFSv3 stable write? */
1109 			if (resp->verf->committed != NFS_UNSTABLE) {
1110 				/* Resend from where the server left off */
1111 				argp->offset += resp->count;
1112 				argp->pgbase += resp->count;
1113 				argp->count -= resp->count;
1114 			} else {
1115 				/* Resend as a stable write in order to avoid
1116 				 * headaches in the case of a server crash.
1117 				 */
1118 				argp->stable = NFS_FILE_SYNC;
1119 			}
1120 			rpc_restart_call(task);
1121 			return -EAGAIN;
1122 		}
1123 		if (time_before(complain, jiffies)) {
1124 			printk(KERN_WARNING
1125 			       "NFS: Server wrote zero bytes, expected %u.\n",
1126 					argp->count);
1127 			complain = jiffies + 300 * HZ;
1128 		}
1129 		/* Can't do anything about it except throw an error. */
1130 		task->tk_status = -EIO;
1131 	}
1132 	return 0;
1133 }
1134 
1135 
1136 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1137 void nfs_commit_release(void *wdata)
1138 {
1139 	nfs_commit_free(wdata);
1140 }
1141 
1142 /*
1143  * Set up the argument/result storage required for the RPC call.
1144  */
1145 static void nfs_commit_rpcsetup(struct list_head *head,
1146 		struct nfs_write_data *data,
1147 		int how)
1148 {
1149 	struct nfs_page		*first;
1150 	struct inode		*inode;
1151 	int flags;
1152 
1153 	/* Set up the RPC argument and reply structs
1154 	 * NB: take care not to mess about with data->commit et al. */
1155 
1156 	list_splice_init(head, &data->pages);
1157 	first = nfs_list_entry(data->pages.next);
1158 	inode = first->wb_context->dentry->d_inode;
1159 
1160 	data->inode	  = inode;
1161 	data->cred	  = first->wb_context->cred;
1162 
1163 	data->args.fh     = NFS_FH(data->inode);
1164 	/* Note: we always request a commit of the entire inode */
1165 	data->args.offset = 0;
1166 	data->args.count  = 0;
1167 	data->res.count   = 0;
1168 	data->res.fattr   = &data->fattr;
1169 	data->res.verf    = &data->verf;
1170 	nfs_fattr_init(&data->fattr);
1171 
1172 	/* Set up the initial task struct.  */
1173 	flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1174 	rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1175 	NFS_PROTO(inode)->commit_setup(data, how);
1176 
1177 	data->task.tk_priority = flush_task_priority(how);
1178 	data->task.tk_cookie = (unsigned long)inode;
1179 
1180 	dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1181 }
1182 
1183 /*
1184  * Commit dirty pages
1185  */
1186 static int
1187 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1188 {
1189 	struct nfs_write_data	*data;
1190 	struct nfs_page         *req;
1191 
1192 	data = nfs_commit_alloc();
1193 
1194 	if (!data)
1195 		goto out_bad;
1196 
1197 	/* Set up the argument struct */
1198 	nfs_commit_rpcsetup(head, data, how);
1199 
1200 	nfs_execute_write(data);
1201 	return 0;
1202  out_bad:
1203 	while (!list_empty(head)) {
1204 		req = nfs_list_entry(head->next);
1205 		nfs_list_remove_request(req);
1206 		nfs_mark_request_commit(req);
1207 		dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1208 		nfs_clear_page_writeback(req);
1209 	}
1210 	return -ENOMEM;
1211 }
1212 
1213 /*
1214  * COMMIT call returned
1215  */
1216 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1217 {
1218 	struct nfs_write_data	*data = calldata;
1219 	struct nfs_page		*req;
1220 
1221         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1222                                 task->tk_pid, task->tk_status);
1223 
1224 	/* Call the NFS version-specific code */
1225 	if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1226 		return;
1227 
1228 	while (!list_empty(&data->pages)) {
1229 		req = nfs_list_entry(data->pages.next);
1230 		nfs_list_remove_request(req);
1231 		clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
1232 		dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1233 
1234 		dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1235 			req->wb_context->dentry->d_inode->i_sb->s_id,
1236 			(long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1237 			req->wb_bytes,
1238 			(long long)req_offset(req));
1239 		if (task->tk_status < 0) {
1240 			req->wb_context->error = task->tk_status;
1241 			nfs_inode_remove_request(req);
1242 			dprintk(", error = %d\n", task->tk_status);
1243 			goto next;
1244 		}
1245 
1246 		/* Okay, COMMIT succeeded, apparently. Check the verifier
1247 		 * returned by the server against all stored verfs. */
1248 		if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1249 			/* We have a match */
1250 			nfs_inode_remove_request(req);
1251 			dprintk(" OK\n");
1252 			goto next;
1253 		}
1254 		/* We have a mismatch. Write the page again */
1255 		dprintk(" mismatch\n");
1256 		nfs_redirty_request(req);
1257 	next:
1258 		nfs_clear_page_writeback(req);
1259 	}
1260 }
1261 
1262 static const struct rpc_call_ops nfs_commit_ops = {
1263 	.rpc_call_done = nfs_commit_done,
1264 	.rpc_release = nfs_commit_release,
1265 };
1266 
1267 int nfs_commit_inode(struct inode *inode, int how)
1268 {
1269 	struct nfs_inode *nfsi = NFS_I(inode);
1270 	LIST_HEAD(head);
1271 	int res;
1272 
1273 	spin_lock(&nfsi->req_lock);
1274 	res = nfs_scan_commit(inode, &head, 0, 0);
1275 	spin_unlock(&nfsi->req_lock);
1276 	if (res) {
1277 		int error = nfs_commit_list(inode, &head, how);
1278 		if (error < 0)
1279 			return error;
1280 	}
1281 	return res;
1282 }
1283 #else
1284 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1285 {
1286 	return 0;
1287 }
1288 #endif
1289 
1290 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1291 {
1292 	struct inode *inode = mapping->host;
1293 	struct nfs_inode *nfsi = NFS_I(inode);
1294 	pgoff_t idx_start, idx_end;
1295 	unsigned int npages = 0;
1296 	LIST_HEAD(head);
1297 	int nocommit = how & FLUSH_NOCOMMIT;
1298 	long pages, ret;
1299 
1300 	/* FIXME */
1301 	if (wbc->range_cyclic)
1302 		idx_start = 0;
1303 	else {
1304 		idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1305 		idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1306 		if (idx_end > idx_start) {
1307 			pgoff_t l_npages = 1 + idx_end - idx_start;
1308 			npages = l_npages;
1309 			if (sizeof(npages) != sizeof(l_npages) &&
1310 					(pgoff_t)npages != l_npages)
1311 				npages = 0;
1312 		}
1313 	}
1314 	how &= ~FLUSH_NOCOMMIT;
1315 	spin_lock(&nfsi->req_lock);
1316 	do {
1317 		ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1318 		if (ret != 0)
1319 			continue;
1320 		if (nocommit)
1321 			break;
1322 		pages = nfs_scan_commit(inode, &head, idx_start, npages);
1323 		if (pages == 0)
1324 			break;
1325 		if (how & FLUSH_INVALIDATE) {
1326 			spin_unlock(&nfsi->req_lock);
1327 			nfs_cancel_commit_list(&head);
1328 			ret = pages;
1329 			spin_lock(&nfsi->req_lock);
1330 			continue;
1331 		}
1332 		pages += nfs_scan_commit(inode, &head, 0, 0);
1333 		spin_unlock(&nfsi->req_lock);
1334 		ret = nfs_commit_list(inode, &head, how);
1335 		spin_lock(&nfsi->req_lock);
1336 	} while (ret >= 0);
1337 	spin_unlock(&nfsi->req_lock);
1338 	return ret;
1339 }
1340 
1341 /*
1342  * flush the inode to disk.
1343  */
1344 int nfs_wb_all(struct inode *inode)
1345 {
1346 	struct address_space *mapping = inode->i_mapping;
1347 	struct writeback_control wbc = {
1348 		.bdi = mapping->backing_dev_info,
1349 		.sync_mode = WB_SYNC_ALL,
1350 		.nr_to_write = LONG_MAX,
1351 		.for_writepages = 1,
1352 		.range_cyclic = 1,
1353 	};
1354 	int ret;
1355 
1356 	ret = nfs_writepages(mapping, &wbc);
1357 	if (ret < 0)
1358 		goto out;
1359 	ret = nfs_sync_mapping_wait(mapping, &wbc, 0);
1360 	if (ret >= 0)
1361 		return 0;
1362 out:
1363 	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1364 	return ret;
1365 }
1366 
1367 int nfs_sync_mapping_range(struct address_space *mapping, loff_t range_start, loff_t range_end, int how)
1368 {
1369 	struct writeback_control wbc = {
1370 		.bdi = mapping->backing_dev_info,
1371 		.sync_mode = WB_SYNC_ALL,
1372 		.nr_to_write = LONG_MAX,
1373 		.range_start = range_start,
1374 		.range_end = range_end,
1375 		.for_writepages = 1,
1376 	};
1377 	int ret;
1378 
1379 	ret = nfs_writepages(mapping, &wbc);
1380 	if (ret < 0)
1381 		goto out;
1382 	ret = nfs_sync_mapping_wait(mapping, &wbc, how);
1383 	if (ret >= 0)
1384 		return 0;
1385 out:
1386 	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1387 	return ret;
1388 }
1389 
1390 int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
1391 {
1392 	loff_t range_start = page_offset(page);
1393 	loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1394 	struct writeback_control wbc = {
1395 		.bdi = page->mapping->backing_dev_info,
1396 		.sync_mode = WB_SYNC_ALL,
1397 		.nr_to_write = LONG_MAX,
1398 		.range_start = range_start,
1399 		.range_end = range_end,
1400 	};
1401 	int ret;
1402 
1403 	BUG_ON(!PageLocked(page));
1404 	if (clear_page_dirty_for_io(page)) {
1405 		ret = nfs_writepage_locked(page, &wbc);
1406 		if (ret < 0)
1407 			goto out;
1408 	}
1409 	if (!PagePrivate(page))
1410 		return 0;
1411 	ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1412 	if (ret >= 0)
1413 		return 0;
1414 out:
1415 	__mark_inode_dirty(inode, I_DIRTY_PAGES);
1416 	return ret;
1417 }
1418 
1419 /*
1420  * Write back all requests on one page - we do this before reading it.
1421  */
1422 int nfs_wb_page(struct inode *inode, struct page* page)
1423 {
1424 	return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1425 }
1426 
1427 int nfs_set_page_dirty(struct page *page)
1428 {
1429 	struct address_space *mapping = page->mapping;
1430 	struct inode *inode;
1431 	spinlock_t *req_lock;
1432 	struct nfs_page *req;
1433 	int ret;
1434 
1435 	if (!mapping)
1436 		goto out_raced;
1437 	inode = mapping->host;
1438 	if (!inode)
1439 		goto out_raced;
1440 	req_lock = &NFS_I(inode)->req_lock;
1441 	spin_lock(req_lock);
1442 	req = nfs_page_find_request_locked(page);
1443 	if (req != NULL) {
1444 		/* Mark any existing write requests for flushing */
1445 		ret = !test_and_set_bit(PG_NEED_FLUSH, &req->wb_flags);
1446 		spin_unlock(req_lock);
1447 		nfs_release_request(req);
1448 		return ret;
1449 	}
1450 	ret = __set_page_dirty_nobuffers(page);
1451 	spin_unlock(req_lock);
1452 	return ret;
1453 out_raced:
1454 	return !TestSetPageDirty(page);
1455 }
1456 
1457 
1458 int __init nfs_init_writepagecache(void)
1459 {
1460 	nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1461 					     sizeof(struct nfs_write_data),
1462 					     0, SLAB_HWCACHE_ALIGN,
1463 					     NULL, NULL);
1464 	if (nfs_wdata_cachep == NULL)
1465 		return -ENOMEM;
1466 
1467 	nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1468 						     nfs_wdata_cachep);
1469 	if (nfs_wdata_mempool == NULL)
1470 		return -ENOMEM;
1471 
1472 	nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1473 						      nfs_wdata_cachep);
1474 	if (nfs_commit_mempool == NULL)
1475 		return -ENOMEM;
1476 
1477 	/*
1478 	 * NFS congestion size, scale with available memory.
1479 	 *
1480 	 *  64MB:    8192k
1481 	 * 128MB:   11585k
1482 	 * 256MB:   16384k
1483 	 * 512MB:   23170k
1484 	 *   1GB:   32768k
1485 	 *   2GB:   46340k
1486 	 *   4GB:   65536k
1487 	 *   8GB:   92681k
1488 	 *  16GB:  131072k
1489 	 *
1490 	 * This allows larger machines to have larger/more transfers.
1491 	 * Limit the default to 256M
1492 	 */
1493 	nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1494 	if (nfs_congestion_kb > 256*1024)
1495 		nfs_congestion_kb = 256*1024;
1496 
1497 	return 0;
1498 }
1499 
1500 void nfs_destroy_writepagecache(void)
1501 {
1502 	mempool_destroy(nfs_commit_mempool);
1503 	mempool_destroy(nfs_wdata_mempool);
1504 	kmem_cache_destroy(nfs_wdata_cachep);
1505 }
1506 
1507