73ac992ece85d2c33a1b02c368fe917110c63410
[linux-2.6.git] / fs / nfs / write.c
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 static 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                         kref_get(&req->wb_kref);
121         }
122         return req;
123 }
124
125 static struct nfs_page *nfs_page_find_request(struct page *page)
126 {
127         struct inode *inode = page->mapping->host;
128         struct nfs_page *req = NULL;
129
130         spin_lock(&inode->i_lock);
131         req = nfs_page_find_request_locked(page);
132         spin_unlock(&inode->i_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                 zero_user_page(page, count, PAGE_CACHE_SIZE - count, KM_USER0);
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         nfs_unlock_request(req);
195         return 0;
196 }
197
198 static int wb_priority(struct writeback_control *wbc)
199 {
200         if (wbc->for_reclaim)
201                 return FLUSH_HIGHPRI | FLUSH_STABLE;
202         if (wbc->for_kupdate)
203                 return FLUSH_LOWPRI;
204         return 0;
205 }
206
207 /*
208  * NFS congestion control
209  */
210
211 int nfs_congestion_kb;
212
213 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
214 #define NFS_CONGESTION_OFF_THRESH       \
215         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
216
217 static int nfs_set_page_writeback(struct page *page)
218 {
219         int ret = test_set_page_writeback(page);
220
221         if (!ret) {
222                 struct inode *inode = page->mapping->host;
223                 struct nfs_server *nfss = NFS_SERVER(inode);
224
225                 if (atomic_long_inc_return(&nfss->writeback) >
226                                 NFS_CONGESTION_ON_THRESH)
227                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
228         }
229         return ret;
230 }
231
232 static void nfs_end_page_writeback(struct page *page)
233 {
234         struct inode *inode = page->mapping->host;
235         struct nfs_server *nfss = NFS_SERVER(inode);
236
237         end_page_writeback(page);
238         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
239                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
240                 congestion_end(WRITE);
241         }
242 }
243
244 /*
245  * Find an associated nfs write request, and prepare to flush it out
246  * Returns 1 if there was no write request, or if the request was
247  * already tagged by nfs_set_page_dirty.Returns 0 if the request
248  * was not tagged.
249  * May also return an error if the user signalled nfs_wait_on_request().
250  */
251 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
252                                 struct page *page)
253 {
254         struct inode *inode = page->mapping->host;
255         struct nfs_inode *nfsi = NFS_I(inode);
256         struct nfs_page *req;
257         int ret;
258
259         spin_lock(&inode->i_lock);
260         for(;;) {
261                 req = nfs_page_find_request_locked(page);
262                 if (req == NULL) {
263                         spin_unlock(&inode->i_lock);
264                         return 1;
265                 }
266                 if (nfs_lock_request_dontget(req))
267                         break;
268                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
269                  *       then the call to nfs_lock_request_dontget() will always
270                  *       succeed provided that someone hasn't already marked the
271                  *       request as dirty (in which case we don't care).
272                  */
273                 spin_unlock(&inode->i_lock);
274                 ret = nfs_wait_on_request(req);
275                 nfs_release_request(req);
276                 if (ret != 0)
277                         return ret;
278                 spin_lock(&inode->i_lock);
279         }
280         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
281                 /* This request is marked for commit */
282                 spin_unlock(&inode->i_lock);
283                 nfs_unlock_request(req);
284                 nfs_pageio_complete(pgio);
285                 return 1;
286         }
287         if (nfs_set_page_writeback(page) != 0) {
288                 spin_unlock(&inode->i_lock);
289                 BUG();
290         }
291         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
292                         NFS_PAGE_TAG_LOCKED);
293         ret = test_bit(PG_NEED_FLUSH, &req->wb_flags);
294         spin_unlock(&inode->i_lock);
295         nfs_pageio_add_request(pgio, req);
296         return ret;
297 }
298
299 /*
300  * Write an mmapped page to the server.
301  */
302 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
303 {
304         struct nfs_pageio_descriptor mypgio, *pgio;
305         struct nfs_open_context *ctx;
306         struct inode *inode = page->mapping->host;
307         unsigned offset;
308         int err;
309
310         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
311         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
312
313         if (wbc->for_writepages)
314                 pgio = wbc->fs_private;
315         else {
316                 nfs_pageio_init_write(&mypgio, inode, wb_priority(wbc));
317                 pgio = &mypgio;
318         }
319
320         nfs_pageio_cond_complete(pgio, page->index);
321
322         err = nfs_page_async_flush(pgio, page);
323         if (err <= 0)
324                 goto out;
325         err = 0;
326         offset = nfs_page_length(page);
327         if (!offset)
328                 goto out;
329
330         nfs_pageio_cond_complete(pgio, page->index);
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         kref_get(&req->wb_kref);
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->path.dentry->d_inode;
411         struct nfs_inode *nfsi = NFS_I(inode);
412
413         BUG_ON (!NFS_WBACK_BUSY(req));
414
415         spin_lock(&inode->i_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(&inode->i_lock);
424                 nfs_end_data_update(inode);
425                 iput(inode);
426         } else
427                 spin_unlock(&inode->i_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->path.dentry->d_inode;
459         struct nfs_inode *nfsi = NFS_I(inode);
460
461         spin_lock(&inode->i_lock);
462         nfsi->ncommit++;
463         set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
464         radix_tree_tag_set(&nfsi->nfs_page_tree,
465                         req->wb_index,
466                         NFS_PAGE_TAG_COMMIT);
467         spin_unlock(&inode->i_lock);
468         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
469         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
470 }
471
472 static inline
473 int nfs_write_need_commit(struct nfs_write_data *data)
474 {
475         return data->verf.committed != NFS_FILE_SYNC;
476 }
477
478 static inline
479 int nfs_reschedule_unstable_write(struct nfs_page *req)
480 {
481         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
482                 nfs_mark_request_commit(req);
483                 return 1;
484         }
485         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
486                 nfs_redirty_request(req);
487                 return 1;
488         }
489         return 0;
490 }
491 #else
492 static inline void
493 nfs_mark_request_commit(struct nfs_page *req)
494 {
495 }
496
497 static inline
498 int nfs_write_need_commit(struct nfs_write_data *data)
499 {
500         return 0;
501 }
502
503 static inline
504 int nfs_reschedule_unstable_write(struct nfs_page *req)
505 {
506         return 0;
507 }
508 #endif
509
510 /*
511  * Wait for a request to complete.
512  *
513  * Interruptible by signals only if mounted with intr flag.
514  */
515 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
516 {
517         struct nfs_inode *nfsi = NFS_I(inode);
518         struct nfs_page *req;
519         pgoff_t idx_end, next;
520         unsigned int            res = 0;
521         int                     error;
522
523         if (npages == 0)
524                 idx_end = ~0;
525         else
526                 idx_end = idx_start + npages - 1;
527
528         next = idx_start;
529         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
530                 if (req->wb_index > idx_end)
531                         break;
532
533                 next = req->wb_index + 1;
534                 BUG_ON(!NFS_WBACK_BUSY(req));
535
536                 kref_get(&req->wb_kref);
537                 spin_unlock(&inode->i_lock);
538                 error = nfs_wait_on_request(req);
539                 nfs_release_request(req);
540                 spin_lock(&inode->i_lock);
541                 if (error < 0)
542                         return error;
543                 res++;
544         }
545         return res;
546 }
547
548 static void nfs_cancel_commit_list(struct list_head *head)
549 {
550         struct nfs_page *req;
551
552         while(!list_empty(head)) {
553                 req = nfs_list_entry(head->next);
554                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
555                 nfs_list_remove_request(req);
556                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
557                 nfs_inode_remove_request(req);
558                 nfs_unlock_request(req);
559         }
560 }
561
562 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
563 /*
564  * nfs_scan_commit - Scan an inode for commit requests
565  * @inode: NFS inode to scan
566  * @dst: destination list
567  * @idx_start: lower bound of page->index to scan.
568  * @npages: idx_start + npages sets the upper bound to scan.
569  *
570  * Moves requests from the inode's 'commit' request list.
571  * The requests are *not* checked to ensure that they form a contiguous set.
572  */
573 static int
574 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
575 {
576         struct nfs_inode *nfsi = NFS_I(inode);
577         int res = 0;
578
579         if (nfsi->ncommit != 0) {
580                 res = nfs_scan_list(nfsi, dst, idx_start, npages,
581                                 NFS_PAGE_TAG_COMMIT);
582                 nfsi->ncommit -= res;
583         }
584         return res;
585 }
586 #else
587 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
588 {
589         return 0;
590 }
591 #endif
592
593 /*
594  * Try to update any existing write request, or create one if there is none.
595  * In order to match, the request's credentials must match those of
596  * the calling process.
597  *
598  * Note: Should always be called with the Page Lock held!
599  */
600 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
601                 struct page *page, unsigned int offset, unsigned int bytes)
602 {
603         struct address_space *mapping = page->mapping;
604         struct inode *inode = mapping->host;
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(&inode->i_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(&inode->i_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(&inode->i_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(&inode->i_lock);
642                                 nfs_unlock_request(new);
643                                 return ERR_PTR(error);
644                         }
645                         spin_unlock(&inode->i_lock);
646                         return new;
647                 }
648                 spin_unlock(&inode->i_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)) {
753                 nfs_end_page_writeback(req->wb_page);
754                 nfs_inode_remove_request(req);
755         } else if (!nfs_reschedule_unstable_write(req)) {
756                 /* Set the PG_uptodate flag */
757                 nfs_mark_uptodate(req->wb_page, req->wb_pgbase, req->wb_bytes);
758                 nfs_end_page_writeback(req->wb_page);
759                 nfs_inode_remove_request(req);
760         } else
761                 nfs_end_page_writeback(req->wb_page);
762         nfs_clear_page_tag_locked(req);
763 }
764
765 static inline int flush_task_priority(int how)
766 {
767         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
768                 case FLUSH_HIGHPRI:
769                         return RPC_PRIORITY_HIGH;
770                 case FLUSH_LOWPRI:
771                         return RPC_PRIORITY_LOW;
772         }
773         return RPC_PRIORITY_NORMAL;
774 }
775
776 /*
777  * Set up the argument/result storage required for the RPC call.
778  */
779 static void nfs_write_rpcsetup(struct nfs_page *req,
780                 struct nfs_write_data *data,
781                 const struct rpc_call_ops *call_ops,
782                 unsigned int count, unsigned int offset,
783                 int how)
784 {
785         struct inode            *inode;
786         int flags;
787
788         /* Set up the RPC argument and reply structs
789          * NB: take care not to mess about with data->commit et al. */
790
791         data->req = req;
792         data->inode = inode = req->wb_context->path.dentry->d_inode;
793         data->cred = req->wb_context->cred;
794
795         data->args.fh     = NFS_FH(inode);
796         data->args.offset = req_offset(req) + offset;
797         data->args.pgbase = req->wb_pgbase + offset;
798         data->args.pages  = data->pagevec;
799         data->args.count  = count;
800         data->args.context = req->wb_context;
801
802         data->res.fattr   = &data->fattr;
803         data->res.count   = count;
804         data->res.verf    = &data->verf;
805         nfs_fattr_init(&data->fattr);
806
807         /* Set up the initial task struct.  */
808         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
809         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
810         NFS_PROTO(inode)->write_setup(data, how);
811
812         data->task.tk_priority = flush_task_priority(how);
813         data->task.tk_cookie = (unsigned long)inode;
814
815         dprintk("NFS: %5u initiated write call "
816                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
817                 data->task.tk_pid,
818                 inode->i_sb->s_id,
819                 (long long)NFS_FILEID(inode),
820                 count,
821                 (unsigned long long)data->args.offset);
822 }
823
824 static void nfs_execute_write(struct nfs_write_data *data)
825 {
826         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
827         sigset_t oldset;
828
829         rpc_clnt_sigmask(clnt, &oldset);
830         rpc_execute(&data->task);
831         rpc_clnt_sigunmask(clnt, &oldset);
832 }
833
834 /*
835  * Generate multiple small requests to write out a single
836  * contiguous dirty area on one page.
837  */
838 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
839 {
840         struct nfs_page *req = nfs_list_entry(head->next);
841         struct page *page = req->wb_page;
842         struct nfs_write_data *data;
843         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
844         unsigned int offset;
845         int requests = 0;
846         LIST_HEAD(list);
847
848         nfs_list_remove_request(req);
849
850         nbytes = count;
851         do {
852                 size_t len = min(nbytes, wsize);
853
854                 data = nfs_writedata_alloc(1);
855                 if (!data)
856                         goto out_bad;
857                 list_add(&data->pages, &list);
858                 requests++;
859                 nbytes -= len;
860         } while (nbytes != 0);
861         atomic_set(&req->wb_complete, requests);
862
863         ClearPageError(page);
864         offset = 0;
865         nbytes = count;
866         do {
867                 data = list_entry(list.next, struct nfs_write_data, pages);
868                 list_del_init(&data->pages);
869
870                 data->pagevec[0] = page;
871
872                 if (nbytes < wsize)
873                         wsize = nbytes;
874                 nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
875                                    wsize, offset, how);
876                 offset += wsize;
877                 nbytes -= wsize;
878                 nfs_execute_write(data);
879         } while (nbytes != 0);
880
881         return 0;
882
883 out_bad:
884         while (!list_empty(&list)) {
885                 data = list_entry(list.next, struct nfs_write_data, pages);
886                 list_del(&data->pages);
887                 nfs_writedata_release(data);
888         }
889         nfs_redirty_request(req);
890         nfs_end_page_writeback(req->wb_page);
891         nfs_clear_page_tag_locked(req);
892         return -ENOMEM;
893 }
894
895 /*
896  * Create an RPC task for the given write request and kick it.
897  * The page must have been locked by the caller.
898  *
899  * It may happen that the page we're passed is not marked dirty.
900  * This is the case if nfs_updatepage detects a conflicting request
901  * that has been written but not committed.
902  */
903 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
904 {
905         struct nfs_page         *req;
906         struct page             **pages;
907         struct nfs_write_data   *data;
908
909         data = nfs_writedata_alloc(npages);
910         if (!data)
911                 goto out_bad;
912
913         pages = data->pagevec;
914         while (!list_empty(head)) {
915                 req = nfs_list_entry(head->next);
916                 nfs_list_remove_request(req);
917                 nfs_list_add_request(req, &data->pages);
918                 ClearPageError(req->wb_page);
919                 *pages++ = req->wb_page;
920         }
921         req = nfs_list_entry(data->pages.next);
922
923         /* Set up the argument struct */
924         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
925
926         nfs_execute_write(data);
927         return 0;
928  out_bad:
929         while (!list_empty(head)) {
930                 req = nfs_list_entry(head->next);
931                 nfs_list_remove_request(req);
932                 nfs_redirty_request(req);
933                 nfs_end_page_writeback(req->wb_page);
934                 nfs_clear_page_tag_locked(req);
935         }
936         return -ENOMEM;
937 }
938
939 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
940                                   struct inode *inode, int ioflags)
941 {
942         int wsize = NFS_SERVER(inode)->wsize;
943
944         if (wsize < PAGE_CACHE_SIZE)
945                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
946         else
947                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
948 }
949
950 /*
951  * Handle a write reply that flushed part of a page.
952  */
953 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
954 {
955         struct nfs_write_data   *data = calldata;
956         struct nfs_page         *req = data->req;
957         struct page             *page = req->wb_page;
958
959         dprintk("NFS: write (%s/%Ld %d@%Ld)",
960                 req->wb_context->path.dentry->d_inode->i_sb->s_id,
961                 (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
962                 req->wb_bytes,
963                 (long long)req_offset(req));
964
965         if (nfs_writeback_done(task, data) != 0)
966                 return;
967
968         if (task->tk_status < 0) {
969                 nfs_set_pageerror(page);
970                 req->wb_context->error = task->tk_status;
971                 dprintk(", error = %d\n", task->tk_status);
972                 goto out;
973         }
974
975         if (nfs_write_need_commit(data)) {
976                 struct inode *inode = page->mapping->host;
977
978                 spin_lock(&inode->i_lock);
979                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
980                         /* Do nothing we need to resend the writes */
981                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
982                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
983                         dprintk(" defer commit\n");
984                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
985                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
986                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
987                         dprintk(" server reboot detected\n");
988                 }
989                 spin_unlock(&inode->i_lock);
990         } else
991                 dprintk(" OK\n");
992
993 out:
994         if (atomic_dec_and_test(&req->wb_complete))
995                 nfs_writepage_release(req);
996 }
997
998 static const struct rpc_call_ops nfs_write_partial_ops = {
999         .rpc_call_done = nfs_writeback_done_partial,
1000         .rpc_release = nfs_writedata_release,
1001 };
1002
1003 /*
1004  * Handle a write reply that flushes a whole page.
1005  *
1006  * FIXME: There is an inherent race with invalidate_inode_pages and
1007  *        writebacks since the page->count is kept > 1 for as long
1008  *        as the page has a write request pending.
1009  */
1010 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1011 {
1012         struct nfs_write_data   *data = calldata;
1013         struct nfs_page         *req;
1014         struct page             *page;
1015
1016         if (nfs_writeback_done(task, data) != 0)
1017                 return;
1018
1019         /* Update attributes as result of writeback. */
1020         while (!list_empty(&data->pages)) {
1021                 req = nfs_list_entry(data->pages.next);
1022                 nfs_list_remove_request(req);
1023                 page = req->wb_page;
1024
1025                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1026                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1027                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1028                         req->wb_bytes,
1029                         (long long)req_offset(req));
1030
1031                 if (task->tk_status < 0) {
1032                         nfs_set_pageerror(page);
1033                         req->wb_context->error = task->tk_status;
1034                         dprintk(", error = %d\n", task->tk_status);
1035                         goto remove_request;
1036                 }
1037
1038                 if (nfs_write_need_commit(data)) {
1039                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1040                         nfs_mark_request_commit(req);
1041                         nfs_end_page_writeback(page);
1042                         dprintk(" marked for commit\n");
1043                         goto next;
1044                 }
1045                 /* Set the PG_uptodate flag? */
1046                 nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
1047                 dprintk(" OK\n");
1048 remove_request:
1049                 nfs_end_page_writeback(page);
1050                 nfs_inode_remove_request(req);
1051         next:
1052                 nfs_clear_page_tag_locked(req);
1053         }
1054 }
1055
1056 static const struct rpc_call_ops nfs_write_full_ops = {
1057         .rpc_call_done = nfs_writeback_done_full,
1058         .rpc_release = nfs_writedata_release,
1059 };
1060
1061
1062 /*
1063  * This function is called when the WRITE call is complete.
1064  */
1065 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1066 {
1067         struct nfs_writeargs    *argp = &data->args;
1068         struct nfs_writeres     *resp = &data->res;
1069         int status;
1070
1071         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1072                 task->tk_pid, task->tk_status);
1073
1074         /*
1075          * ->write_done will attempt to use post-op attributes to detect
1076          * conflicting writes by other clients.  A strict interpretation
1077          * of close-to-open would allow us to continue caching even if
1078          * another writer had changed the file, but some applications
1079          * depend on tighter cache coherency when writing.
1080          */
1081         status = NFS_PROTO(data->inode)->write_done(task, data);
1082         if (status != 0)
1083                 return status;
1084         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1085
1086 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1087         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1088                 /* We tried a write call, but the server did not
1089                  * commit data to stable storage even though we
1090                  * requested it.
1091                  * Note: There is a known bug in Tru64 < 5.0 in which
1092                  *       the server reports NFS_DATA_SYNC, but performs
1093                  *       NFS_FILE_SYNC. We therefore implement this checking
1094                  *       as a dprintk() in order to avoid filling syslog.
1095                  */
1096                 static unsigned long    complain;
1097
1098                 if (time_before(complain, jiffies)) {
1099                         dprintk("NFS: faulty NFS server %s:"
1100                                 " (committed = %d) != (stable = %d)\n",
1101                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1102                                 resp->verf->committed, argp->stable);
1103                         complain = jiffies + 300 * HZ;
1104                 }
1105         }
1106 #endif
1107         /* Is this a short write? */
1108         if (task->tk_status >= 0 && resp->count < argp->count) {
1109                 static unsigned long    complain;
1110
1111                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1112
1113                 /* Has the server at least made some progress? */
1114                 if (resp->count != 0) {
1115                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1116                         if (resp->verf->committed != NFS_UNSTABLE) {
1117                                 /* Resend from where the server left off */
1118                                 argp->offset += resp->count;
1119                                 argp->pgbase += resp->count;
1120                                 argp->count -= resp->count;
1121                         } else {
1122                                 /* Resend as a stable write in order to avoid
1123                                  * headaches in the case of a server crash.
1124                                  */
1125                                 argp->stable = NFS_FILE_SYNC;
1126                         }
1127                         rpc_restart_call(task);
1128                         return -EAGAIN;
1129                 }
1130                 if (time_before(complain, jiffies)) {
1131                         printk(KERN_WARNING
1132                                "NFS: Server wrote zero bytes, expected %u.\n",
1133                                         argp->count);
1134                         complain = jiffies + 300 * HZ;
1135                 }
1136                 /* Can't do anything about it except throw an error. */
1137                 task->tk_status = -EIO;
1138         }
1139         return 0;
1140 }
1141
1142
1143 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1144 void nfs_commit_release(void *wdata)
1145 {
1146         nfs_commit_free(wdata);
1147 }
1148
1149 /*
1150  * Set up the argument/result storage required for the RPC call.
1151  */
1152 static void nfs_commit_rpcsetup(struct list_head *head,
1153                 struct nfs_write_data *data,
1154                 int how)
1155 {
1156         struct nfs_page         *first;
1157         struct inode            *inode;
1158         int flags;
1159
1160         /* Set up the RPC argument and reply structs
1161          * NB: take care not to mess about with data->commit et al. */
1162
1163         list_splice_init(head, &data->pages);
1164         first = nfs_list_entry(data->pages.next);
1165         inode = first->wb_context->path.dentry->d_inode;
1166
1167         data->inode       = inode;
1168         data->cred        = first->wb_context->cred;
1169
1170         data->args.fh     = NFS_FH(data->inode);
1171         /* Note: we always request a commit of the entire inode */
1172         data->args.offset = 0;
1173         data->args.count  = 0;
1174         data->res.count   = 0;
1175         data->res.fattr   = &data->fattr;
1176         data->res.verf    = &data->verf;
1177         nfs_fattr_init(&data->fattr);
1178
1179         /* Set up the initial task struct.  */
1180         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1181         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1182         NFS_PROTO(inode)->commit_setup(data, how);
1183
1184         data->task.tk_priority = flush_task_priority(how);
1185         data->task.tk_cookie = (unsigned long)inode;
1186         
1187         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1188 }
1189
1190 /*
1191  * Commit dirty pages
1192  */
1193 static int
1194 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1195 {
1196         struct nfs_write_data   *data;
1197         struct nfs_page         *req;
1198
1199         data = nfs_commit_alloc();
1200
1201         if (!data)
1202                 goto out_bad;
1203
1204         /* Set up the argument struct */
1205         nfs_commit_rpcsetup(head, data, how);
1206
1207         nfs_execute_write(data);
1208         return 0;
1209  out_bad:
1210         while (!list_empty(head)) {
1211                 req = nfs_list_entry(head->next);
1212                 nfs_list_remove_request(req);
1213                 nfs_mark_request_commit(req);
1214                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1215                 nfs_clear_page_tag_locked(req);
1216         }
1217         return -ENOMEM;
1218 }
1219
1220 /*
1221  * COMMIT call returned
1222  */
1223 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1224 {
1225         struct nfs_write_data   *data = calldata;
1226         struct nfs_page         *req;
1227
1228         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1229                                 task->tk_pid, task->tk_status);
1230
1231         /* Call the NFS version-specific code */
1232         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1233                 return;
1234
1235         while (!list_empty(&data->pages)) {
1236                 req = nfs_list_entry(data->pages.next);
1237                 nfs_list_remove_request(req);
1238                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
1239                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1240
1241                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1242                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1243                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1244                         req->wb_bytes,
1245                         (long long)req_offset(req));
1246                 if (task->tk_status < 0) {
1247                         req->wb_context->error = task->tk_status;
1248                         nfs_inode_remove_request(req);
1249                         dprintk(", error = %d\n", task->tk_status);
1250                         goto next;
1251                 }
1252
1253                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1254                  * returned by the server against all stored verfs. */
1255                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1256                         /* We have a match */
1257                         /* Set the PG_uptodate flag */
1258                         nfs_mark_uptodate(req->wb_page, req->wb_pgbase,
1259                                         req->wb_bytes);
1260                         nfs_inode_remove_request(req);
1261                         dprintk(" OK\n");
1262                         goto next;
1263                 }
1264                 /* We have a mismatch. Write the page again */
1265                 dprintk(" mismatch\n");
1266                 nfs_redirty_request(req);
1267         next:
1268                 nfs_clear_page_tag_locked(req);
1269         }
1270 }
1271
1272 static const struct rpc_call_ops nfs_commit_ops = {
1273         .rpc_call_done = nfs_commit_done,
1274         .rpc_release = nfs_commit_release,
1275 };
1276
1277 int nfs_commit_inode(struct inode *inode, int how)
1278 {
1279         LIST_HEAD(head);
1280         int res;
1281
1282         spin_lock(&inode->i_lock);
1283         res = nfs_scan_commit(inode, &head, 0, 0);
1284         spin_unlock(&inode->i_lock);
1285         if (res) {
1286                 int error = nfs_commit_list(inode, &head, how);
1287                 if (error < 0)
1288                         return error;
1289         }
1290         return res;
1291 }
1292 #else
1293 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1294 {
1295         return 0;
1296 }
1297 #endif
1298
1299 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1300 {
1301         struct inode *inode = mapping->host;
1302         pgoff_t idx_start, idx_end;
1303         unsigned int npages = 0;
1304         LIST_HEAD(head);
1305         int nocommit = how & FLUSH_NOCOMMIT;
1306         long pages, ret;
1307
1308         /* FIXME */
1309         if (wbc->range_cyclic)
1310                 idx_start = 0;
1311         else {
1312                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1313                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1314                 if (idx_end > idx_start) {
1315                         pgoff_t l_npages = 1 + idx_end - idx_start;
1316                         npages = l_npages;
1317                         if (sizeof(npages) != sizeof(l_npages) &&
1318                                         (pgoff_t)npages != l_npages)
1319                                 npages = 0;
1320                 }
1321         }
1322         how &= ~FLUSH_NOCOMMIT;
1323         spin_lock(&inode->i_lock);
1324         do {
1325                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1326                 if (ret != 0)
1327                         continue;
1328                 if (nocommit)
1329                         break;
1330                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1331                 if (pages == 0)
1332                         break;
1333                 if (how & FLUSH_INVALIDATE) {
1334                         spin_unlock(&inode->i_lock);
1335                         nfs_cancel_commit_list(&head);
1336                         ret = pages;
1337                         spin_lock(&inode->i_lock);
1338                         continue;
1339                 }
1340                 pages += nfs_scan_commit(inode, &head, 0, 0);
1341                 spin_unlock(&inode->i_lock);
1342                 ret = nfs_commit_list(inode, &head, how);
1343                 spin_lock(&inode->i_lock);
1344
1345         } while (ret >= 0);
1346         spin_unlock(&inode->i_lock);
1347         return ret;
1348 }
1349
1350 /*
1351  * flush the inode to disk.
1352  */
1353 int nfs_wb_all(struct inode *inode)
1354 {
1355         struct address_space *mapping = inode->i_mapping;
1356         struct writeback_control wbc = {
1357                 .bdi = mapping->backing_dev_info,
1358                 .sync_mode = WB_SYNC_ALL,
1359                 .nr_to_write = LONG_MAX,
1360                 .for_writepages = 1,
1361                 .range_cyclic = 1,
1362         };
1363         int ret;
1364
1365         ret = nfs_writepages(mapping, &wbc);
1366         if (ret < 0)
1367                 goto out;
1368         ret = nfs_sync_mapping_wait(mapping, &wbc, 0);
1369         if (ret >= 0)
1370                 return 0;
1371 out:
1372         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1373         return ret;
1374 }
1375
1376 int nfs_sync_mapping_range(struct address_space *mapping, loff_t range_start, loff_t range_end, int how)
1377 {
1378         struct writeback_control wbc = {
1379                 .bdi = mapping->backing_dev_info,
1380                 .sync_mode = WB_SYNC_ALL,
1381                 .nr_to_write = LONG_MAX,
1382                 .range_start = range_start,
1383                 .range_end = range_end,
1384                 .for_writepages = 1,
1385         };
1386         int ret;
1387
1388         ret = nfs_writepages(mapping, &wbc);
1389         if (ret < 0)
1390                 goto out;
1391         ret = nfs_sync_mapping_wait(mapping, &wbc, how);
1392         if (ret >= 0)
1393                 return 0;
1394 out:
1395         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1396         return ret;
1397 }
1398
1399 int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
1400 {
1401         loff_t range_start = page_offset(page);
1402         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1403         struct writeback_control wbc = {
1404                 .bdi = page->mapping->backing_dev_info,
1405                 .sync_mode = WB_SYNC_ALL,
1406                 .nr_to_write = LONG_MAX,
1407                 .range_start = range_start,
1408                 .range_end = range_end,
1409         };
1410         int ret;
1411
1412         BUG_ON(!PageLocked(page));
1413         if (clear_page_dirty_for_io(page)) {
1414                 ret = nfs_writepage_locked(page, &wbc);
1415                 if (ret < 0)
1416                         goto out;
1417         }
1418         if (!PagePrivate(page))
1419                 return 0;
1420         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1421         if (ret >= 0)
1422                 return 0;
1423 out:
1424         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1425         return ret;
1426 }
1427
1428 /*
1429  * Write back all requests on one page - we do this before reading it.
1430  */
1431 int nfs_wb_page(struct inode *inode, struct page* page)
1432 {
1433         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1434 }
1435
1436 int nfs_set_page_dirty(struct page *page)
1437 {
1438         struct address_space *mapping = page->mapping;
1439         struct inode *inode;
1440         struct nfs_page *req;
1441         int ret;
1442
1443         if (!mapping)
1444                 goto out_raced;
1445         inode = mapping->host;
1446         if (!inode)
1447                 goto out_raced;
1448         spin_lock(&inode->i_lock);
1449         req = nfs_page_find_request_locked(page);
1450         if (req != NULL) {
1451                 /* Mark any existing write requests for flushing */
1452                 ret = !test_and_set_bit(PG_NEED_FLUSH, &req->wb_flags);
1453                 spin_unlock(&inode->i_lock);
1454                 nfs_release_request(req);
1455                 return ret;
1456         }
1457         ret = __set_page_dirty_nobuffers(page);
1458         spin_unlock(&inode->i_lock);
1459         return ret;
1460 out_raced:
1461         return !TestSetPageDirty(page);
1462 }
1463
1464
1465 int __init nfs_init_writepagecache(void)
1466 {
1467         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1468                                              sizeof(struct nfs_write_data),
1469                                              0, SLAB_HWCACHE_ALIGN,
1470                                              NULL, NULL);
1471         if (nfs_wdata_cachep == NULL)
1472                 return -ENOMEM;
1473
1474         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1475                                                      nfs_wdata_cachep);
1476         if (nfs_wdata_mempool == NULL)
1477                 return -ENOMEM;
1478
1479         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1480                                                       nfs_wdata_cachep);
1481         if (nfs_commit_mempool == NULL)
1482                 return -ENOMEM;
1483
1484         /*
1485          * NFS congestion size, scale with available memory.
1486          *
1487          *  64MB:    8192k
1488          * 128MB:   11585k
1489          * 256MB:   16384k
1490          * 512MB:   23170k
1491          *   1GB:   32768k
1492          *   2GB:   46340k
1493          *   4GB:   65536k
1494          *   8GB:   92681k
1495          *  16GB:  131072k
1496          *
1497          * This allows larger machines to have larger/more transfers.
1498          * Limit the default to 256M
1499          */
1500         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1501         if (nfs_congestion_kb > 256*1024)
1502                 nfs_congestion_kb = 256*1024;
1503
1504         return 0;
1505 }
1506
1507 void nfs_destroy_writepagecache(void)
1508 {
1509         mempool_destroy(nfs_commit_mempool);
1510         mempool_destroy(nfs_wdata_mempool);
1511         kmem_cache_destroy(nfs_wdata_cachep);
1512 }
1513