Pull thermal into release branch
[linux-2.6] / 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 void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
114 {
115         ctx->error = error;
116         smp_wmb();
117         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
118 }
119
120 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
121 {
122         struct nfs_page *req = NULL;
123
124         if (PagePrivate(page)) {
125                 req = (struct nfs_page *)page_private(page);
126                 if (req != NULL)
127                         kref_get(&req->wb_kref);
128         }
129         return req;
130 }
131
132 static struct nfs_page *nfs_page_find_request(struct page *page)
133 {
134         struct inode *inode = page->mapping->host;
135         struct nfs_page *req = NULL;
136
137         spin_lock(&inode->i_lock);
138         req = nfs_page_find_request_locked(page);
139         spin_unlock(&inode->i_lock);
140         return req;
141 }
142
143 /* Adjust the file length if we're writing beyond the end */
144 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
145 {
146         struct inode *inode = page->mapping->host;
147         loff_t end, i_size = i_size_read(inode);
148         pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
149
150         if (i_size > 0 && page->index < end_index)
151                 return;
152         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
153         if (i_size >= end)
154                 return;
155         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
156         i_size_write(inode, end);
157 }
158
159 /* A writeback failed: mark the page as bad, and invalidate the page cache */
160 static void nfs_set_pageerror(struct page *page)
161 {
162         SetPageError(page);
163         nfs_zap_mapping(page->mapping->host, page->mapping);
164 }
165
166 /* We can set the PG_uptodate flag if we see that a write request
167  * covers the full page.
168  */
169 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
170 {
171         if (PageUptodate(page))
172                 return;
173         if (base != 0)
174                 return;
175         if (count != nfs_page_length(page))
176                 return;
177         SetPageUptodate(page);
178 }
179
180 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
181                 unsigned int offset, unsigned int count)
182 {
183         struct nfs_page *req;
184         int ret;
185
186         for (;;) {
187                 req = nfs_update_request(ctx, page, offset, count);
188                 if (!IS_ERR(req))
189                         break;
190                 ret = PTR_ERR(req);
191                 if (ret != -EBUSY)
192                         return ret;
193                 ret = nfs_wb_page(page->mapping->host, page);
194                 if (ret != 0)
195                         return ret;
196         }
197         /* Update file length */
198         nfs_grow_file(page, offset, count);
199         nfs_unlock_request(req);
200         return 0;
201 }
202
203 static int wb_priority(struct writeback_control *wbc)
204 {
205         if (wbc->for_reclaim)
206                 return FLUSH_HIGHPRI | FLUSH_STABLE;
207         if (wbc->for_kupdate)
208                 return FLUSH_LOWPRI;
209         return 0;
210 }
211
212 /*
213  * NFS congestion control
214  */
215
216 int nfs_congestion_kb;
217
218 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
219 #define NFS_CONGESTION_OFF_THRESH       \
220         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
221
222 static int nfs_set_page_writeback(struct page *page)
223 {
224         int ret = test_set_page_writeback(page);
225
226         if (!ret) {
227                 struct inode *inode = page->mapping->host;
228                 struct nfs_server *nfss = NFS_SERVER(inode);
229
230                 if (atomic_long_inc_return(&nfss->writeback) >
231                                 NFS_CONGESTION_ON_THRESH)
232                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
233         }
234         return ret;
235 }
236
237 static void nfs_end_page_writeback(struct page *page)
238 {
239         struct inode *inode = page->mapping->host;
240         struct nfs_server *nfss = NFS_SERVER(inode);
241
242         end_page_writeback(page);
243         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
244                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
245 }
246
247 /*
248  * Find an associated nfs write request, and prepare to flush it out
249  * May 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 0;
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 0;
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         spin_unlock(&inode->i_lock);
294         nfs_pageio_add_request(pgio, req);
295         return 0;
296 }
297
298 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
299 {
300         struct inode *inode = page->mapping->host;
301
302         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
303         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
304
305         nfs_pageio_cond_complete(pgio, page->index);
306         return nfs_page_async_flush(pgio, page);
307 }
308
309 /*
310  * Write an mmapped page to the server.
311  */
312 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
313 {
314         struct nfs_pageio_descriptor pgio;
315         int err;
316
317         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
318         err = nfs_do_writepage(page, wbc, &pgio);
319         nfs_pageio_complete(&pgio);
320         if (err < 0)
321                 return err;
322         if (pgio.pg_error < 0)
323                 return pgio.pg_error;
324         return 0;
325 }
326
327 int nfs_writepage(struct page *page, struct writeback_control *wbc)
328 {
329         int ret;
330
331         ret = nfs_writepage_locked(page, wbc);
332         unlock_page(page);
333         return ret;
334 }
335
336 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
337 {
338         int ret;
339
340         ret = nfs_do_writepage(page, wbc, data);
341         unlock_page(page);
342         return ret;
343 }
344
345 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
346 {
347         struct inode *inode = mapping->host;
348         struct nfs_pageio_descriptor pgio;
349         int err;
350
351         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
352
353         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
354         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
355         nfs_pageio_complete(&pgio);
356         if (err < 0)
357                 return err;
358         if (pgio.pg_error < 0)
359                 return pgio.pg_error;
360         return 0;
361 }
362
363 /*
364  * Insert a write request into an inode
365  */
366 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
367 {
368         struct nfs_inode *nfsi = NFS_I(inode);
369         int error;
370
371         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
372         BUG_ON(error == -EEXIST);
373         if (error)
374                 return error;
375         if (!nfsi->npages) {
376                 igrab(inode);
377                 if (nfs_have_delegation(inode, FMODE_WRITE))
378                         nfsi->change_attr++;
379         }
380         SetPagePrivate(req->wb_page);
381         set_page_private(req->wb_page, (unsigned long)req);
382         nfsi->npages++;
383         kref_get(&req->wb_kref);
384         return 0;
385 }
386
387 /*
388  * Remove a write request from an inode
389  */
390 static void nfs_inode_remove_request(struct nfs_page *req)
391 {
392         struct inode *inode = req->wb_context->path.dentry->d_inode;
393         struct nfs_inode *nfsi = NFS_I(inode);
394
395         BUG_ON (!NFS_WBACK_BUSY(req));
396
397         spin_lock(&inode->i_lock);
398         set_page_private(req->wb_page, 0);
399         ClearPagePrivate(req->wb_page);
400         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
401         nfsi->npages--;
402         if (!nfsi->npages) {
403                 spin_unlock(&inode->i_lock);
404                 iput(inode);
405         } else
406                 spin_unlock(&inode->i_lock);
407         nfs_clear_request(req);
408         nfs_release_request(req);
409 }
410
411 static void
412 nfs_redirty_request(struct nfs_page *req)
413 {
414         __set_page_dirty_nobuffers(req->wb_page);
415 }
416
417 /*
418  * Check if a request is dirty
419  */
420 static inline int
421 nfs_dirty_request(struct nfs_page *req)
422 {
423         struct page *page = req->wb_page;
424
425         if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
426                 return 0;
427         return !PageWriteback(req->wb_page);
428 }
429
430 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
431 /*
432  * Add a request to the inode's commit list.
433  */
434 static void
435 nfs_mark_request_commit(struct nfs_page *req)
436 {
437         struct inode *inode = req->wb_context->path.dentry->d_inode;
438         struct nfs_inode *nfsi = NFS_I(inode);
439
440         spin_lock(&inode->i_lock);
441         nfsi->ncommit++;
442         set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
443         radix_tree_tag_set(&nfsi->nfs_page_tree,
444                         req->wb_index,
445                         NFS_PAGE_TAG_COMMIT);
446         spin_unlock(&inode->i_lock);
447         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
448         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
449         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
450 }
451
452 static inline
453 int nfs_write_need_commit(struct nfs_write_data *data)
454 {
455         return data->verf.committed != NFS_FILE_SYNC;
456 }
457
458 static inline
459 int nfs_reschedule_unstable_write(struct nfs_page *req)
460 {
461         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
462                 nfs_mark_request_commit(req);
463                 return 1;
464         }
465         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
466                 nfs_redirty_request(req);
467                 return 1;
468         }
469         return 0;
470 }
471 #else
472 static inline void
473 nfs_mark_request_commit(struct nfs_page *req)
474 {
475 }
476
477 static inline
478 int nfs_write_need_commit(struct nfs_write_data *data)
479 {
480         return 0;
481 }
482
483 static inline
484 int nfs_reschedule_unstable_write(struct nfs_page *req)
485 {
486         return 0;
487 }
488 #endif
489
490 /*
491  * Wait for a request to complete.
492  *
493  * Interruptible by signals only if mounted with intr flag.
494  */
495 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
496 {
497         struct nfs_inode *nfsi = NFS_I(inode);
498         struct nfs_page *req;
499         pgoff_t idx_end, next;
500         unsigned int            res = 0;
501         int                     error;
502
503         if (npages == 0)
504                 idx_end = ~0;
505         else
506                 idx_end = idx_start + npages - 1;
507
508         next = idx_start;
509         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
510                 if (req->wb_index > idx_end)
511                         break;
512
513                 next = req->wb_index + 1;
514                 BUG_ON(!NFS_WBACK_BUSY(req));
515
516                 kref_get(&req->wb_kref);
517                 spin_unlock(&inode->i_lock);
518                 error = nfs_wait_on_request(req);
519                 nfs_release_request(req);
520                 spin_lock(&inode->i_lock);
521                 if (error < 0)
522                         return error;
523                 res++;
524         }
525         return res;
526 }
527
528 static void nfs_cancel_commit_list(struct list_head *head)
529 {
530         struct nfs_page *req;
531
532         while(!list_empty(head)) {
533                 req = nfs_list_entry(head->next);
534                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
535                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
536                                 BDI_RECLAIMABLE);
537                 nfs_list_remove_request(req);
538                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
539                 nfs_inode_remove_request(req);
540                 nfs_unlock_request(req);
541         }
542 }
543
544 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
545 /*
546  * nfs_scan_commit - Scan an inode for commit requests
547  * @inode: NFS inode to scan
548  * @dst: destination list
549  * @idx_start: lower bound of page->index to scan.
550  * @npages: idx_start + npages sets the upper bound to scan.
551  *
552  * Moves requests from the inode's 'commit' request list.
553  * The requests are *not* checked to ensure that they form a contiguous set.
554  */
555 static int
556 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
557 {
558         struct nfs_inode *nfsi = NFS_I(inode);
559         int res = 0;
560
561         if (nfsi->ncommit != 0) {
562                 res = nfs_scan_list(nfsi, dst, idx_start, npages,
563                                 NFS_PAGE_TAG_COMMIT);
564                 nfsi->ncommit -= res;
565         }
566         return res;
567 }
568 #else
569 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
570 {
571         return 0;
572 }
573 #endif
574
575 /*
576  * Try to update any existing write request, or create one if there is none.
577  * In order to match, the request's credentials must match those of
578  * the calling process.
579  *
580  * Note: Should always be called with the Page Lock held!
581  */
582 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
583                 struct page *page, unsigned int offset, unsigned int bytes)
584 {
585         struct address_space *mapping = page->mapping;
586         struct inode *inode = mapping->host;
587         struct nfs_page         *req, *new = NULL;
588         pgoff_t         rqend, end;
589
590         end = offset + bytes;
591
592         for (;;) {
593                 /* Loop over all inode entries and see if we find
594                  * A request for the page we wish to update
595                  */
596                 spin_lock(&inode->i_lock);
597                 req = nfs_page_find_request_locked(page);
598                 if (req) {
599                         if (!nfs_lock_request_dontget(req)) {
600                                 int error;
601
602                                 spin_unlock(&inode->i_lock);
603                                 error = nfs_wait_on_request(req);
604                                 nfs_release_request(req);
605                                 if (error < 0) {
606                                         if (new)
607                                                 nfs_release_request(new);
608                                         return ERR_PTR(error);
609                                 }
610                                 continue;
611                         }
612                         spin_unlock(&inode->i_lock);
613                         if (new)
614                                 nfs_release_request(new);
615                         break;
616                 }
617
618                 if (new) {
619                         int error;
620                         nfs_lock_request_dontget(new);
621                         error = nfs_inode_add_request(inode, new);
622                         if (error) {
623                                 spin_unlock(&inode->i_lock);
624                                 nfs_unlock_request(new);
625                                 return ERR_PTR(error);
626                         }
627                         spin_unlock(&inode->i_lock);
628                         req = new;
629                         goto zero_page;
630                 }
631                 spin_unlock(&inode->i_lock);
632
633                 new = nfs_create_request(ctx, inode, page, offset, bytes);
634                 if (IS_ERR(new))
635                         return new;
636         }
637
638         /* We have a request for our page.
639          * If the creds don't match, or the
640          * page addresses don't match,
641          * tell the caller to wait on the conflicting
642          * request.
643          */
644         rqend = req->wb_offset + req->wb_bytes;
645         if (req->wb_context != ctx
646             || req->wb_page != page
647             || !nfs_dirty_request(req)
648             || offset > rqend || end < req->wb_offset) {
649                 nfs_unlock_request(req);
650                 return ERR_PTR(-EBUSY);
651         }
652
653         /* Okay, the request matches. Update the region */
654         if (offset < req->wb_offset) {
655                 req->wb_offset = offset;
656                 req->wb_pgbase = offset;
657                 req->wb_bytes = max(end, rqend) - req->wb_offset;
658                 goto zero_page;
659         }
660
661         if (end > rqend)
662                 req->wb_bytes = end - req->wb_offset;
663
664         return req;
665 zero_page:
666         /* If this page might potentially be marked as up to date,
667          * then we need to zero any uninitalised data. */
668         if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
669                         && !PageUptodate(req->wb_page))
670                 zero_user_page(req->wb_page, req->wb_bytes,
671                                 PAGE_CACHE_SIZE - req->wb_bytes,
672                                 KM_USER0);
673         return req;
674 }
675
676 int nfs_flush_incompatible(struct file *file, struct page *page)
677 {
678         struct nfs_open_context *ctx = nfs_file_open_context(file);
679         struct nfs_page *req;
680         int do_flush, status;
681         /*
682          * Look for a request corresponding to this page. If there
683          * is one, and it belongs to another file, we flush it out
684          * before we try to copy anything into the page. Do this
685          * due to the lack of an ACCESS-type call in NFSv2.
686          * Also do the same if we find a request from an existing
687          * dropped page.
688          */
689         do {
690                 req = nfs_page_find_request(page);
691                 if (req == NULL)
692                         return 0;
693                 do_flush = req->wb_page != page || req->wb_context != ctx
694                         || !nfs_dirty_request(req);
695                 nfs_release_request(req);
696                 if (!do_flush)
697                         return 0;
698                 status = nfs_wb_page(page->mapping->host, page);
699         } while (status == 0);
700         return status;
701 }
702
703 /*
704  * Update and possibly write a cached page of an NFS file.
705  *
706  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
707  * things with a page scheduled for an RPC call (e.g. invalidate it).
708  */
709 int nfs_updatepage(struct file *file, struct page *page,
710                 unsigned int offset, unsigned int count)
711 {
712         struct nfs_open_context *ctx = nfs_file_open_context(file);
713         struct inode    *inode = page->mapping->host;
714         int             status = 0;
715
716         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
717
718         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
719                 file->f_path.dentry->d_parent->d_name.name,
720                 file->f_path.dentry->d_name.name, count,
721                 (long long)(page_offset(page) +offset));
722
723         /* If we're not using byte range locks, and we know the page
724          * is entirely in cache, it may be more efficient to avoid
725          * fragmenting write requests.
726          */
727         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
728                 count = max(count + offset, nfs_page_length(page));
729                 offset = 0;
730         }
731
732         status = nfs_writepage_setup(ctx, page, offset, count);
733         __set_page_dirty_nobuffers(page);
734
735         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
736                         status, (long long)i_size_read(inode));
737         if (status < 0)
738                 nfs_set_pageerror(page);
739         return status;
740 }
741
742 static void nfs_writepage_release(struct nfs_page *req)
743 {
744
745         if (PageError(req->wb_page)) {
746                 nfs_end_page_writeback(req->wb_page);
747                 nfs_inode_remove_request(req);
748         } else if (!nfs_reschedule_unstable_write(req)) {
749                 /* Set the PG_uptodate flag */
750                 nfs_mark_uptodate(req->wb_page, req->wb_pgbase, req->wb_bytes);
751                 nfs_end_page_writeback(req->wb_page);
752                 nfs_inode_remove_request(req);
753         } else
754                 nfs_end_page_writeback(req->wb_page);
755         nfs_clear_page_tag_locked(req);
756 }
757
758 static inline int flush_task_priority(int how)
759 {
760         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
761                 case FLUSH_HIGHPRI:
762                         return RPC_PRIORITY_HIGH;
763                 case FLUSH_LOWPRI:
764                         return RPC_PRIORITY_LOW;
765         }
766         return RPC_PRIORITY_NORMAL;
767 }
768
769 /*
770  * Set up the argument/result storage required for the RPC call.
771  */
772 static void nfs_write_rpcsetup(struct nfs_page *req,
773                 struct nfs_write_data *data,
774                 const struct rpc_call_ops *call_ops,
775                 unsigned int count, unsigned int offset,
776                 int how)
777 {
778         struct inode            *inode;
779         int flags;
780
781         /* Set up the RPC argument and reply structs
782          * NB: take care not to mess about with data->commit et al. */
783
784         data->req = req;
785         data->inode = inode = req->wb_context->path.dentry->d_inode;
786         data->cred = req->wb_context->cred;
787
788         data->args.fh     = NFS_FH(inode);
789         data->args.offset = req_offset(req) + offset;
790         data->args.pgbase = req->wb_pgbase + offset;
791         data->args.pages  = data->pagevec;
792         data->args.count  = count;
793         data->args.context = req->wb_context;
794
795         data->res.fattr   = &data->fattr;
796         data->res.count   = count;
797         data->res.verf    = &data->verf;
798         nfs_fattr_init(&data->fattr);
799
800         /* Set up the initial task struct.  */
801         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
802         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
803         NFS_PROTO(inode)->write_setup(data, how);
804
805         data->task.tk_priority = flush_task_priority(how);
806         data->task.tk_cookie = (unsigned long)inode;
807
808         dprintk("NFS: %5u initiated write call "
809                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
810                 data->task.tk_pid,
811                 inode->i_sb->s_id,
812                 (long long)NFS_FILEID(inode),
813                 count,
814                 (unsigned long long)data->args.offset);
815 }
816
817 static void nfs_execute_write(struct nfs_write_data *data)
818 {
819         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
820         sigset_t oldset;
821
822         rpc_clnt_sigmask(clnt, &oldset);
823         rpc_execute(&data->task);
824         rpc_clnt_sigunmask(clnt, &oldset);
825 }
826
827 /*
828  * Generate multiple small requests to write out a single
829  * contiguous dirty area on one page.
830  */
831 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
832 {
833         struct nfs_page *req = nfs_list_entry(head->next);
834         struct page *page = req->wb_page;
835         struct nfs_write_data *data;
836         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
837         unsigned int offset;
838         int requests = 0;
839         LIST_HEAD(list);
840
841         nfs_list_remove_request(req);
842
843         nbytes = count;
844         do {
845                 size_t len = min(nbytes, wsize);
846
847                 data = nfs_writedata_alloc(1);
848                 if (!data)
849                         goto out_bad;
850                 list_add(&data->pages, &list);
851                 requests++;
852                 nbytes -= len;
853         } while (nbytes != 0);
854         atomic_set(&req->wb_complete, requests);
855
856         ClearPageError(page);
857         offset = 0;
858         nbytes = count;
859         do {
860                 data = list_entry(list.next, struct nfs_write_data, pages);
861                 list_del_init(&data->pages);
862
863                 data->pagevec[0] = page;
864
865                 if (nbytes < wsize)
866                         wsize = nbytes;
867                 nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
868                                    wsize, offset, how);
869                 offset += wsize;
870                 nbytes -= wsize;
871                 nfs_execute_write(data);
872         } while (nbytes != 0);
873
874         return 0;
875
876 out_bad:
877         while (!list_empty(&list)) {
878                 data = list_entry(list.next, struct nfs_write_data, pages);
879                 list_del(&data->pages);
880                 nfs_writedata_release(data);
881         }
882         nfs_redirty_request(req);
883         nfs_end_page_writeback(req->wb_page);
884         nfs_clear_page_tag_locked(req);
885         return -ENOMEM;
886 }
887
888 /*
889  * Create an RPC task for the given write request and kick it.
890  * The page must have been locked by the caller.
891  *
892  * It may happen that the page we're passed is not marked dirty.
893  * This is the case if nfs_updatepage detects a conflicting request
894  * that has been written but not committed.
895  */
896 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
897 {
898         struct nfs_page         *req;
899         struct page             **pages;
900         struct nfs_write_data   *data;
901
902         data = nfs_writedata_alloc(npages);
903         if (!data)
904                 goto out_bad;
905
906         pages = data->pagevec;
907         while (!list_empty(head)) {
908                 req = nfs_list_entry(head->next);
909                 nfs_list_remove_request(req);
910                 nfs_list_add_request(req, &data->pages);
911                 ClearPageError(req->wb_page);
912                 *pages++ = req->wb_page;
913         }
914         req = nfs_list_entry(data->pages.next);
915
916         /* Set up the argument struct */
917         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
918
919         nfs_execute_write(data);
920         return 0;
921  out_bad:
922         while (!list_empty(head)) {
923                 req = nfs_list_entry(head->next);
924                 nfs_list_remove_request(req);
925                 nfs_redirty_request(req);
926                 nfs_end_page_writeback(req->wb_page);
927                 nfs_clear_page_tag_locked(req);
928         }
929         return -ENOMEM;
930 }
931
932 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
933                                   struct inode *inode, int ioflags)
934 {
935         int wsize = NFS_SERVER(inode)->wsize;
936
937         if (wsize < PAGE_CACHE_SIZE)
938                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
939         else
940                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
941 }
942
943 /*
944  * Handle a write reply that flushed part of a page.
945  */
946 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
947 {
948         struct nfs_write_data   *data = calldata;
949         struct nfs_page         *req = data->req;
950         struct page             *page = req->wb_page;
951
952         dprintk("NFS: write (%s/%Ld %d@%Ld)",
953                 req->wb_context->path.dentry->d_inode->i_sb->s_id,
954                 (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
955                 req->wb_bytes,
956                 (long long)req_offset(req));
957
958         if (nfs_writeback_done(task, data) != 0)
959                 return;
960
961         if (task->tk_status < 0) {
962                 nfs_set_pageerror(page);
963                 nfs_context_set_write_error(req->wb_context, task->tk_status);
964                 dprintk(", error = %d\n", task->tk_status);
965                 goto out;
966         }
967
968         if (nfs_write_need_commit(data)) {
969                 struct inode *inode = page->mapping->host;
970
971                 spin_lock(&inode->i_lock);
972                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
973                         /* Do nothing we need to resend the writes */
974                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
975                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
976                         dprintk(" defer commit\n");
977                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
978                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
979                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
980                         dprintk(" server reboot detected\n");
981                 }
982                 spin_unlock(&inode->i_lock);
983         } else
984                 dprintk(" OK\n");
985
986 out:
987         if (atomic_dec_and_test(&req->wb_complete))
988                 nfs_writepage_release(req);
989 }
990
991 static const struct rpc_call_ops nfs_write_partial_ops = {
992         .rpc_call_done = nfs_writeback_done_partial,
993         .rpc_release = nfs_writedata_release,
994 };
995
996 /*
997  * Handle a write reply that flushes a whole page.
998  *
999  * FIXME: There is an inherent race with invalidate_inode_pages and
1000  *        writebacks since the page->count is kept > 1 for as long
1001  *        as the page has a write request pending.
1002  */
1003 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1004 {
1005         struct nfs_write_data   *data = calldata;
1006         struct nfs_page         *req;
1007         struct page             *page;
1008
1009         if (nfs_writeback_done(task, data) != 0)
1010                 return;
1011
1012         /* Update attributes as result of writeback. */
1013         while (!list_empty(&data->pages)) {
1014                 req = nfs_list_entry(data->pages.next);
1015                 nfs_list_remove_request(req);
1016                 page = req->wb_page;
1017
1018                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1019                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1020                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1021                         req->wb_bytes,
1022                         (long long)req_offset(req));
1023
1024                 if (task->tk_status < 0) {
1025                         nfs_set_pageerror(page);
1026                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1027                         dprintk(", error = %d\n", task->tk_status);
1028                         goto remove_request;
1029                 }
1030
1031                 if (nfs_write_need_commit(data)) {
1032                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1033                         nfs_mark_request_commit(req);
1034                         nfs_end_page_writeback(page);
1035                         dprintk(" marked for commit\n");
1036                         goto next;
1037                 }
1038                 /* Set the PG_uptodate flag? */
1039                 nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
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_tag_locked(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->path.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                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1209                                 BDI_RECLAIMABLE);
1210                 nfs_clear_page_tag_locked(req);
1211         }
1212         return -ENOMEM;
1213 }
1214
1215 /*
1216  * COMMIT call returned
1217  */
1218 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1219 {
1220         struct nfs_write_data   *data = calldata;
1221         struct nfs_page         *req;
1222
1223         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1224                                 task->tk_pid, task->tk_status);
1225
1226         /* Call the NFS version-specific code */
1227         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1228                 return;
1229
1230         while (!list_empty(&data->pages)) {
1231                 req = nfs_list_entry(data->pages.next);
1232                 nfs_list_remove_request(req);
1233                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
1234                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1235                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1236                                 BDI_RECLAIMABLE);
1237
1238                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1239                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1240                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1241                         req->wb_bytes,
1242                         (long long)req_offset(req));
1243                 if (task->tk_status < 0) {
1244                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1245                         nfs_inode_remove_request(req);
1246                         dprintk(", error = %d\n", task->tk_status);
1247                         goto next;
1248                 }
1249
1250                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1251                  * returned by the server against all stored verfs. */
1252                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1253                         /* We have a match */
1254                         /* Set the PG_uptodate flag */
1255                         nfs_mark_uptodate(req->wb_page, req->wb_pgbase,
1256                                         req->wb_bytes);
1257                         nfs_inode_remove_request(req);
1258                         dprintk(" OK\n");
1259                         goto next;
1260                 }
1261                 /* We have a mismatch. Write the page again */
1262                 dprintk(" mismatch\n");
1263                 nfs_redirty_request(req);
1264         next:
1265                 nfs_clear_page_tag_locked(req);
1266         }
1267 }
1268
1269 static const struct rpc_call_ops nfs_commit_ops = {
1270         .rpc_call_done = nfs_commit_done,
1271         .rpc_release = nfs_commit_release,
1272 };
1273
1274 int nfs_commit_inode(struct inode *inode, int how)
1275 {
1276         LIST_HEAD(head);
1277         int res;
1278
1279         spin_lock(&inode->i_lock);
1280         res = nfs_scan_commit(inode, &head, 0, 0);
1281         spin_unlock(&inode->i_lock);
1282         if (res) {
1283                 int error = nfs_commit_list(inode, &head, how);
1284                 if (error < 0)
1285                         return error;
1286         }
1287         return res;
1288 }
1289 #else
1290 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1291 {
1292         return 0;
1293 }
1294 #endif
1295
1296 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1297 {
1298         struct inode *inode = mapping->host;
1299         pgoff_t idx_start, idx_end;
1300         unsigned int npages = 0;
1301         LIST_HEAD(head);
1302         int nocommit = how & FLUSH_NOCOMMIT;
1303         long pages, ret;
1304
1305         /* FIXME */
1306         if (wbc->range_cyclic)
1307                 idx_start = 0;
1308         else {
1309                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1310                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1311                 if (idx_end > idx_start) {
1312                         pgoff_t l_npages = 1 + idx_end - idx_start;
1313                         npages = l_npages;
1314                         if (sizeof(npages) != sizeof(l_npages) &&
1315                                         (pgoff_t)npages != l_npages)
1316                                 npages = 0;
1317                 }
1318         }
1319         how &= ~FLUSH_NOCOMMIT;
1320         spin_lock(&inode->i_lock);
1321         do {
1322                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1323                 if (ret != 0)
1324                         continue;
1325                 if (nocommit)
1326                         break;
1327                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1328                 if (pages == 0)
1329                         break;
1330                 if (how & FLUSH_INVALIDATE) {
1331                         spin_unlock(&inode->i_lock);
1332                         nfs_cancel_commit_list(&head);
1333                         ret = pages;
1334                         spin_lock(&inode->i_lock);
1335                         continue;
1336                 }
1337                 pages += nfs_scan_commit(inode, &head, 0, 0);
1338                 spin_unlock(&inode->i_lock);
1339                 ret = nfs_commit_list(inode, &head, how);
1340                 spin_lock(&inode->i_lock);
1341
1342         } while (ret >= 0);
1343         spin_unlock(&inode->i_lock);
1344         return ret;
1345 }
1346
1347 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1348 {
1349         int ret;
1350
1351         ret = nfs_writepages(mapping, wbc);
1352         if (ret < 0)
1353                 goto out;
1354         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1355         if (ret < 0)
1356                 goto out;
1357         return 0;
1358 out:
1359         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1360         return ret;
1361 }
1362
1363 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1364 static int nfs_write_mapping(struct address_space *mapping, int how)
1365 {
1366         struct writeback_control wbc = {
1367                 .bdi = mapping->backing_dev_info,
1368                 .sync_mode = WB_SYNC_NONE,
1369                 .nr_to_write = LONG_MAX,
1370                 .for_writepages = 1,
1371                 .range_cyclic = 1,
1372         };
1373         int ret;
1374
1375         ret = __nfs_write_mapping(mapping, &wbc, how);
1376         if (ret < 0)
1377                 return ret;
1378         wbc.sync_mode = WB_SYNC_ALL;
1379         return __nfs_write_mapping(mapping, &wbc, how);
1380 }
1381
1382 /*
1383  * flush the inode to disk.
1384  */
1385 int nfs_wb_all(struct inode *inode)
1386 {
1387         return nfs_write_mapping(inode->i_mapping, 0);
1388 }
1389
1390 int nfs_wb_nocommit(struct inode *inode)
1391 {
1392         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1393 }
1394
1395 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1396 {
1397         struct nfs_page *req;
1398         loff_t range_start = page_offset(page);
1399         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1400         struct writeback_control wbc = {
1401                 .bdi = page->mapping->backing_dev_info,
1402                 .sync_mode = WB_SYNC_ALL,
1403                 .nr_to_write = LONG_MAX,
1404                 .range_start = range_start,
1405                 .range_end = range_end,
1406         };
1407         int ret = 0;
1408
1409         BUG_ON(!PageLocked(page));
1410         for (;;) {
1411                 req = nfs_page_find_request(page);
1412                 if (req == NULL)
1413                         goto out;
1414                 if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1415                         nfs_release_request(req);
1416                         break;
1417                 }
1418                 if (nfs_lock_request_dontget(req)) {
1419                         nfs_inode_remove_request(req);
1420                         /*
1421                          * In case nfs_inode_remove_request has marked the
1422                          * page as being dirty
1423                          */
1424                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1425                         nfs_unlock_request(req);
1426                         break;
1427                 }
1428                 ret = nfs_wait_on_request(req);
1429                 if (ret < 0)
1430                         goto out;
1431         }
1432         if (!PagePrivate(page))
1433                 return 0;
1434         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1435 out:
1436         return ret;
1437 }
1438
1439 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1440                                 int how)
1441 {
1442         loff_t range_start = page_offset(page);
1443         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1444         struct writeback_control wbc = {
1445                 .bdi = page->mapping->backing_dev_info,
1446                 .sync_mode = WB_SYNC_ALL,
1447                 .nr_to_write = LONG_MAX,
1448                 .range_start = range_start,
1449                 .range_end = range_end,
1450         };
1451         int ret;
1452
1453         BUG_ON(!PageLocked(page));
1454         if (clear_page_dirty_for_io(page)) {
1455                 ret = nfs_writepage_locked(page, &wbc);
1456                 if (ret < 0)
1457                         goto out;
1458         }
1459         if (!PagePrivate(page))
1460                 return 0;
1461         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1462         if (ret >= 0)
1463                 return 0;
1464 out:
1465         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1466         return ret;
1467 }
1468
1469 /*
1470  * Write back all requests on one page - we do this before reading it.
1471  */
1472 int nfs_wb_page(struct inode *inode, struct page* page)
1473 {
1474         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1475 }
1476
1477 int __init nfs_init_writepagecache(void)
1478 {
1479         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1480                                              sizeof(struct nfs_write_data),
1481                                              0, SLAB_HWCACHE_ALIGN,
1482                                              NULL);
1483         if (nfs_wdata_cachep == NULL)
1484                 return -ENOMEM;
1485
1486         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1487                                                      nfs_wdata_cachep);
1488         if (nfs_wdata_mempool == NULL)
1489                 return -ENOMEM;
1490
1491         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1492                                                       nfs_wdata_cachep);
1493         if (nfs_commit_mempool == NULL)
1494                 return -ENOMEM;
1495
1496         /*
1497          * NFS congestion size, scale with available memory.
1498          *
1499          *  64MB:    8192k
1500          * 128MB:   11585k
1501          * 256MB:   16384k
1502          * 512MB:   23170k
1503          *   1GB:   32768k
1504          *   2GB:   46340k
1505          *   4GB:   65536k
1506          *   8GB:   92681k
1507          *  16GB:  131072k
1508          *
1509          * This allows larger machines to have larger/more transfers.
1510          * Limit the default to 256M
1511          */
1512         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1513         if (nfs_congestion_kb > 256*1024)
1514                 nfs_congestion_kb = 256*1024;
1515
1516         return 0;
1517 }
1518
1519 void nfs_destroy_writepagecache(void)
1520 {
1521         mempool_destroy(nfs_commit_mempool);
1522         mempool_destroy(nfs_wdata_mempool);
1523         kmem_cache_destroy(nfs_wdata_cachep);
1524 }
1525