SUNRPC: Cleanup of rpc_task initialisation
[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 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_clear_page_tag_locked(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_page *req;
256         int ret;
257
258         spin_lock(&inode->i_lock);
259         for(;;) {
260                 req = nfs_page_find_request_locked(page);
261                 if (req == NULL) {
262                         spin_unlock(&inode->i_lock);
263                         return 0;
264                 }
265                 if (nfs_set_page_tag_locked(req))
266                         break;
267                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
268                  *       then the call to nfs_set_page_tag_locked() will always
269                  *       succeed provided that someone hasn't already marked the
270                  *       request as dirty (in which case we don't care).
271                  */
272                 spin_unlock(&inode->i_lock);
273                 ret = nfs_wait_on_request(req);
274                 nfs_release_request(req);
275                 if (ret != 0)
276                         return ret;
277                 spin_lock(&inode->i_lock);
278         }
279         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
280                 /* This request is marked for commit */
281                 spin_unlock(&inode->i_lock);
282                 nfs_clear_page_tag_locked(req);
283                 nfs_pageio_complete(pgio);
284                 return 0;
285         }
286         if (nfs_set_page_writeback(page) != 0) {
287                 spin_unlock(&inode->i_lock);
288                 BUG();
289         }
290         spin_unlock(&inode->i_lock);
291         nfs_pageio_add_request(pgio, req);
292         return 0;
293 }
294
295 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
296 {
297         struct inode *inode = page->mapping->host;
298
299         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
300         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
301
302         nfs_pageio_cond_complete(pgio, page->index);
303         return nfs_page_async_flush(pgio, page);
304 }
305
306 /*
307  * Write an mmapped page to the server.
308  */
309 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
310 {
311         struct nfs_pageio_descriptor pgio;
312         int err;
313
314         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
315         err = nfs_do_writepage(page, wbc, &pgio);
316         nfs_pageio_complete(&pgio);
317         if (err < 0)
318                 return err;
319         if (pgio.pg_error < 0)
320                 return pgio.pg_error;
321         return 0;
322 }
323
324 int nfs_writepage(struct page *page, struct writeback_control *wbc)
325 {
326         int ret;
327
328         ret = nfs_writepage_locked(page, wbc);
329         unlock_page(page);
330         return ret;
331 }
332
333 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
334 {
335         int ret;
336
337         ret = nfs_do_writepage(page, wbc, data);
338         unlock_page(page);
339         return ret;
340 }
341
342 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
343 {
344         struct inode *inode = mapping->host;
345         struct nfs_pageio_descriptor pgio;
346         int err;
347
348         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
349
350         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
351         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
352         nfs_pageio_complete(&pgio);
353         if (err < 0)
354                 return err;
355         if (pgio.pg_error < 0)
356                 return pgio.pg_error;
357         return 0;
358 }
359
360 /*
361  * Insert a write request into an inode
362  */
363 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
364 {
365         struct nfs_inode *nfsi = NFS_I(inode);
366         int error;
367
368         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
369         BUG_ON(error == -EEXIST);
370         if (error)
371                 return error;
372         if (!nfsi->npages) {
373                 igrab(inode);
374                 if (nfs_have_delegation(inode, FMODE_WRITE))
375                         nfsi->change_attr++;
376         }
377         SetPagePrivate(req->wb_page);
378         set_page_private(req->wb_page, (unsigned long)req);
379         nfsi->npages++;
380         kref_get(&req->wb_kref);
381         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
382         return 0;
383 }
384
385 /*
386  * Remove a write request from an inode
387  */
388 static void nfs_inode_remove_request(struct nfs_page *req)
389 {
390         struct inode *inode = req->wb_context->path.dentry->d_inode;
391         struct nfs_inode *nfsi = NFS_I(inode);
392
393         BUG_ON (!NFS_WBACK_BUSY(req));
394
395         spin_lock(&inode->i_lock);
396         set_page_private(req->wb_page, 0);
397         ClearPagePrivate(req->wb_page);
398         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
399         nfsi->npages--;
400         if (!nfsi->npages) {
401                 spin_unlock(&inode->i_lock);
402                 iput(inode);
403         } else
404                 spin_unlock(&inode->i_lock);
405         nfs_clear_request(req);
406         nfs_release_request(req);
407 }
408
409 static void
410 nfs_redirty_request(struct nfs_page *req)
411 {
412         __set_page_dirty_nobuffers(req->wb_page);
413 }
414
415 /*
416  * Check if a request is dirty
417  */
418 static inline int
419 nfs_dirty_request(struct nfs_page *req)
420 {
421         struct page *page = req->wb_page;
422
423         if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
424                 return 0;
425         return !PageWriteback(req->wb_page);
426 }
427
428 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
429 /*
430  * Add a request to the inode's commit list.
431  */
432 static void
433 nfs_mark_request_commit(struct nfs_page *req)
434 {
435         struct inode *inode = req->wb_context->path.dentry->d_inode;
436         struct nfs_inode *nfsi = NFS_I(inode);
437
438         spin_lock(&inode->i_lock);
439         nfsi->ncommit++;
440         set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
441         radix_tree_tag_set(&nfsi->nfs_page_tree,
442                         req->wb_index,
443                         NFS_PAGE_TAG_COMMIT);
444         spin_unlock(&inode->i_lock);
445         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
446         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
447         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
448 }
449
450 static inline
451 int nfs_write_need_commit(struct nfs_write_data *data)
452 {
453         return data->verf.committed != NFS_FILE_SYNC;
454 }
455
456 static inline
457 int nfs_reschedule_unstable_write(struct nfs_page *req)
458 {
459         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
460                 nfs_mark_request_commit(req);
461                 return 1;
462         }
463         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
464                 nfs_redirty_request(req);
465                 return 1;
466         }
467         return 0;
468 }
469 #else
470 static inline void
471 nfs_mark_request_commit(struct nfs_page *req)
472 {
473 }
474
475 static inline
476 int nfs_write_need_commit(struct nfs_write_data *data)
477 {
478         return 0;
479 }
480
481 static inline
482 int nfs_reschedule_unstable_write(struct nfs_page *req)
483 {
484         return 0;
485 }
486 #endif
487
488 /*
489  * Wait for a request to complete.
490  *
491  * Interruptible by signals only if mounted with intr flag.
492  */
493 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
494 {
495         struct nfs_inode *nfsi = NFS_I(inode);
496         struct nfs_page *req;
497         pgoff_t idx_end, next;
498         unsigned int            res = 0;
499         int                     error;
500
501         if (npages == 0)
502                 idx_end = ~0;
503         else
504                 idx_end = idx_start + npages - 1;
505
506         next = idx_start;
507         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
508                 if (req->wb_index > idx_end)
509                         break;
510
511                 next = req->wb_index + 1;
512                 BUG_ON(!NFS_WBACK_BUSY(req));
513
514                 kref_get(&req->wb_kref);
515                 spin_unlock(&inode->i_lock);
516                 error = nfs_wait_on_request(req);
517                 nfs_release_request(req);
518                 spin_lock(&inode->i_lock);
519                 if (error < 0)
520                         return error;
521                 res++;
522         }
523         return res;
524 }
525
526 static void nfs_cancel_commit_list(struct list_head *head)
527 {
528         struct nfs_page *req;
529
530         while(!list_empty(head)) {
531                 req = nfs_list_entry(head->next);
532                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
533                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
534                                 BDI_RECLAIMABLE);
535                 nfs_list_remove_request(req);
536                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
537                 nfs_inode_remove_request(req);
538                 nfs_unlock_request(req);
539         }
540 }
541
542 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
543 /*
544  * nfs_scan_commit - Scan an inode for commit requests
545  * @inode: NFS inode to scan
546  * @dst: destination list
547  * @idx_start: lower bound of page->index to scan.
548  * @npages: idx_start + npages sets the upper bound to scan.
549  *
550  * Moves requests from the inode's 'commit' request list.
551  * The requests are *not* checked to ensure that they form a contiguous set.
552  */
553 static int
554 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
555 {
556         struct nfs_inode *nfsi = NFS_I(inode);
557         int res = 0;
558
559         if (nfsi->ncommit != 0) {
560                 res = nfs_scan_list(nfsi, dst, idx_start, npages,
561                                 NFS_PAGE_TAG_COMMIT);
562                 nfsi->ncommit -= res;
563         }
564         return res;
565 }
566 #else
567 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
568 {
569         return 0;
570 }
571 #endif
572
573 /*
574  * Try to update any existing write request, or create one if there is none.
575  * In order to match, the request's credentials must match those of
576  * the calling process.
577  *
578  * Note: Should always be called with the Page Lock held!
579  */
580 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
581                 struct page *page, unsigned int offset, unsigned int bytes)
582 {
583         struct address_space *mapping = page->mapping;
584         struct inode *inode = mapping->host;
585         struct nfs_page         *req, *new = NULL;
586         pgoff_t         rqend, end;
587
588         end = offset + bytes;
589
590         for (;;) {
591                 /* Loop over all inode entries and see if we find
592                  * A request for the page we wish to update
593                  */
594                 spin_lock(&inode->i_lock);
595                 req = nfs_page_find_request_locked(page);
596                 if (req) {
597                         if (!nfs_set_page_tag_locked(req)) {
598                                 int error;
599
600                                 spin_unlock(&inode->i_lock);
601                                 error = nfs_wait_on_request(req);
602                                 nfs_release_request(req);
603                                 if (error < 0) {
604                                         if (new)
605                                                 nfs_release_request(new);
606                                         return ERR_PTR(error);
607                                 }
608                                 continue;
609                         }
610                         spin_unlock(&inode->i_lock);
611                         if (new)
612                                 nfs_release_request(new);
613                         break;
614                 }
615
616                 if (new) {
617                         int error;
618                         nfs_lock_request_dontget(new);
619                         error = nfs_inode_add_request(inode, new);
620                         if (error) {
621                                 spin_unlock(&inode->i_lock);
622                                 nfs_unlock_request(new);
623                                 return ERR_PTR(error);
624                         }
625                         spin_unlock(&inode->i_lock);
626                         req = new;
627                         goto zero_page;
628                 }
629                 spin_unlock(&inode->i_lock);
630
631                 new = nfs_create_request(ctx, inode, page, offset, bytes);
632                 if (IS_ERR(new))
633                         return new;
634         }
635
636         /* We have a request for our page.
637          * If the creds don't match, or the
638          * page addresses don't match,
639          * tell the caller to wait on the conflicting
640          * request.
641          */
642         rqend = req->wb_offset + req->wb_bytes;
643         if (req->wb_context != ctx
644             || req->wb_page != page
645             || !nfs_dirty_request(req)
646             || offset > rqend || end < req->wb_offset) {
647                 nfs_clear_page_tag_locked(req);
648                 return ERR_PTR(-EBUSY);
649         }
650
651         /* Okay, the request matches. Update the region */
652         if (offset < req->wb_offset) {
653                 req->wb_offset = offset;
654                 req->wb_pgbase = offset;
655                 req->wb_bytes = max(end, rqend) - req->wb_offset;
656                 goto zero_page;
657         }
658
659         if (end > rqend)
660                 req->wb_bytes = end - req->wb_offset;
661
662         return req;
663 zero_page:
664         /* If this page might potentially be marked as up to date,
665          * then we need to zero any uninitalised data. */
666         if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
667                         && !PageUptodate(req->wb_page))
668                 zero_user_page(req->wb_page, req->wb_bytes,
669                                 PAGE_CACHE_SIZE - req->wb_bytes,
670                                 KM_USER0);
671         return req;
672 }
673
674 int nfs_flush_incompatible(struct file *file, struct page *page)
675 {
676         struct nfs_open_context *ctx = nfs_file_open_context(file);
677         struct nfs_page *req;
678         int do_flush, status;
679         /*
680          * Look for a request corresponding to this page. If there
681          * is one, and it belongs to another file, we flush it out
682          * before we try to copy anything into the page. Do this
683          * due to the lack of an ACCESS-type call in NFSv2.
684          * Also do the same if we find a request from an existing
685          * dropped page.
686          */
687         do {
688                 req = nfs_page_find_request(page);
689                 if (req == NULL)
690                         return 0;
691                 do_flush = req->wb_page != page || req->wb_context != ctx
692                         || !nfs_dirty_request(req);
693                 nfs_release_request(req);
694                 if (!do_flush)
695                         return 0;
696                 status = nfs_wb_page(page->mapping->host, page);
697         } while (status == 0);
698         return status;
699 }
700
701 /*
702  * Update and possibly write a cached page of an NFS file.
703  *
704  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
705  * things with a page scheduled for an RPC call (e.g. invalidate it).
706  */
707 int nfs_updatepage(struct file *file, struct page *page,
708                 unsigned int offset, unsigned int count)
709 {
710         struct nfs_open_context *ctx = nfs_file_open_context(file);
711         struct inode    *inode = page->mapping->host;
712         int             status = 0;
713
714         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
715
716         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
717                 file->f_path.dentry->d_parent->d_name.name,
718                 file->f_path.dentry->d_name.name, count,
719                 (long long)(page_offset(page) +offset));
720
721         /* If we're not using byte range locks, and we know the page
722          * is entirely in cache, it may be more efficient to avoid
723          * fragmenting write requests.
724          */
725         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
726                 count = max(count + offset, nfs_page_length(page));
727                 offset = 0;
728         }
729
730         status = nfs_writepage_setup(ctx, page, offset, count);
731         __set_page_dirty_nobuffers(page);
732
733         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
734                         status, (long long)i_size_read(inode));
735         if (status < 0)
736                 nfs_set_pageerror(page);
737         return status;
738 }
739
740 static void nfs_writepage_release(struct nfs_page *req)
741 {
742
743         if (PageError(req->wb_page)) {
744                 nfs_end_page_writeback(req->wb_page);
745                 nfs_inode_remove_request(req);
746         } else if (!nfs_reschedule_unstable_write(req)) {
747                 /* Set the PG_uptodate flag */
748                 nfs_mark_uptodate(req->wb_page, req->wb_pgbase, req->wb_bytes);
749                 nfs_end_page_writeback(req->wb_page);
750                 nfs_inode_remove_request(req);
751         } else
752                 nfs_end_page_writeback(req->wb_page);
753         nfs_clear_page_tag_locked(req);
754 }
755
756 static inline int flush_task_priority(int how)
757 {
758         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
759                 case FLUSH_HIGHPRI:
760                         return RPC_PRIORITY_HIGH;
761                 case FLUSH_LOWPRI:
762                         return RPC_PRIORITY_LOW;
763         }
764         return RPC_PRIORITY_NORMAL;
765 }
766
767 /*
768  * Set up the argument/result storage required for the RPC call.
769  */
770 static void nfs_write_rpcsetup(struct nfs_page *req,
771                 struct nfs_write_data *data,
772                 const struct rpc_call_ops *call_ops,
773                 unsigned int count, unsigned int offset,
774                 int how)
775 {
776         struct inode *inode = req->wb_context->path.dentry->d_inode;
777         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
778         struct rpc_task_setup task_setup_data = {
779                 .rpc_client = NFS_CLIENT(inode),
780                 .callback_ops = call_ops,
781                 .callback_data = data,
782                 .flags = flags,
783         };
784
785         /* Set up the RPC argument and reply structs
786          * NB: take care not to mess about with data->commit et al. */
787
788         data->req = req;
789         data->inode = inode = req->wb_context->path.dentry->d_inode;
790         data->cred = req->wb_context->cred;
791
792         data->args.fh     = NFS_FH(inode);
793         data->args.offset = req_offset(req) + offset;
794         data->args.pgbase = req->wb_pgbase + offset;
795         data->args.pages  = data->pagevec;
796         data->args.count  = count;
797         data->args.context = req->wb_context;
798
799         data->res.fattr   = &data->fattr;
800         data->res.count   = count;
801         data->res.verf    = &data->verf;
802         nfs_fattr_init(&data->fattr);
803
804         /* Set up the initial task struct.  */
805         rpc_init_task(&data->task, &task_setup_data);
806         NFS_PROTO(inode)->write_setup(data, how);
807
808         data->task.tk_priority = flush_task_priority(how);
809         data->task.tk_cookie = (unsigned long)inode;
810
811         dprintk("NFS: %5u initiated write call "
812                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
813                 data->task.tk_pid,
814                 inode->i_sb->s_id,
815                 (long long)NFS_FILEID(inode),
816                 count,
817                 (unsigned long long)data->args.offset);
818 }
819
820 static void nfs_execute_write(struct nfs_write_data *data)
821 {
822         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
823         sigset_t oldset;
824
825         rpc_clnt_sigmask(clnt, &oldset);
826         rpc_execute(&data->task);
827         rpc_clnt_sigunmask(clnt, &oldset);
828 }
829
830 /*
831  * Generate multiple small requests to write out a single
832  * contiguous dirty area on one page.
833  */
834 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
835 {
836         struct nfs_page *req = nfs_list_entry(head->next);
837         struct page *page = req->wb_page;
838         struct nfs_write_data *data;
839         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
840         unsigned int offset;
841         int requests = 0;
842         LIST_HEAD(list);
843
844         nfs_list_remove_request(req);
845
846         nbytes = count;
847         do {
848                 size_t len = min(nbytes, wsize);
849
850                 data = nfs_writedata_alloc(1);
851                 if (!data)
852                         goto out_bad;
853                 list_add(&data->pages, &list);
854                 requests++;
855                 nbytes -= len;
856         } while (nbytes != 0);
857         atomic_set(&req->wb_complete, requests);
858
859         ClearPageError(page);
860         offset = 0;
861         nbytes = count;
862         do {
863                 data = list_entry(list.next, struct nfs_write_data, pages);
864                 list_del_init(&data->pages);
865
866                 data->pagevec[0] = page;
867
868                 if (nbytes < wsize)
869                         wsize = nbytes;
870                 nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
871                                    wsize, offset, how);
872                 offset += wsize;
873                 nbytes -= wsize;
874                 nfs_execute_write(data);
875         } while (nbytes != 0);
876
877         return 0;
878
879 out_bad:
880         while (!list_empty(&list)) {
881                 data = list_entry(list.next, struct nfs_write_data, pages);
882                 list_del(&data->pages);
883                 nfs_writedata_release(data);
884         }
885         nfs_redirty_request(req);
886         nfs_end_page_writeback(req->wb_page);
887         nfs_clear_page_tag_locked(req);
888         return -ENOMEM;
889 }
890
891 /*
892  * Create an RPC task for the given write request and kick it.
893  * The page must have been locked by the caller.
894  *
895  * It may happen that the page we're passed is not marked dirty.
896  * This is the case if nfs_updatepage detects a conflicting request
897  * that has been written but not committed.
898  */
899 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
900 {
901         struct nfs_page         *req;
902         struct page             **pages;
903         struct nfs_write_data   *data;
904
905         data = nfs_writedata_alloc(npages);
906         if (!data)
907                 goto out_bad;
908
909         pages = data->pagevec;
910         while (!list_empty(head)) {
911                 req = nfs_list_entry(head->next);
912                 nfs_list_remove_request(req);
913                 nfs_list_add_request(req, &data->pages);
914                 ClearPageError(req->wb_page);
915                 *pages++ = req->wb_page;
916         }
917         req = nfs_list_entry(data->pages.next);
918
919         /* Set up the argument struct */
920         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
921
922         nfs_execute_write(data);
923         return 0;
924  out_bad:
925         while (!list_empty(head)) {
926                 req = nfs_list_entry(head->next);
927                 nfs_list_remove_request(req);
928                 nfs_redirty_request(req);
929                 nfs_end_page_writeback(req->wb_page);
930                 nfs_clear_page_tag_locked(req);
931         }
932         return -ENOMEM;
933 }
934
935 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
936                                   struct inode *inode, int ioflags)
937 {
938         int wsize = NFS_SERVER(inode)->wsize;
939
940         if (wsize < PAGE_CACHE_SIZE)
941                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
942         else
943                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
944 }
945
946 /*
947  * Handle a write reply that flushed part of a page.
948  */
949 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
950 {
951         struct nfs_write_data   *data = calldata;
952         struct nfs_page         *req = data->req;
953         struct page             *page = req->wb_page;
954
955         dprintk("NFS: write (%s/%Ld %d@%Ld)",
956                 req->wb_context->path.dentry->d_inode->i_sb->s_id,
957                 (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
958                 req->wb_bytes,
959                 (long long)req_offset(req));
960
961         if (nfs_writeback_done(task, data) != 0)
962                 return;
963
964         if (task->tk_status < 0) {
965                 nfs_set_pageerror(page);
966                 nfs_context_set_write_error(req->wb_context, task->tk_status);
967                 dprintk(", error = %d\n", task->tk_status);
968                 goto out;
969         }
970
971         if (nfs_write_need_commit(data)) {
972                 struct inode *inode = page->mapping->host;
973
974                 spin_lock(&inode->i_lock);
975                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
976                         /* Do nothing we need to resend the writes */
977                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
978                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
979                         dprintk(" defer commit\n");
980                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
981                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
982                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
983                         dprintk(" server reboot detected\n");
984                 }
985                 spin_unlock(&inode->i_lock);
986         } else
987                 dprintk(" OK\n");
988
989 out:
990         if (atomic_dec_and_test(&req->wb_complete))
991                 nfs_writepage_release(req);
992 }
993
994 static const struct rpc_call_ops nfs_write_partial_ops = {
995         .rpc_call_done = nfs_writeback_done_partial,
996         .rpc_release = nfs_writedata_release,
997 };
998
999 /*
1000  * Handle a write reply that flushes a whole page.
1001  *
1002  * FIXME: There is an inherent race with invalidate_inode_pages and
1003  *        writebacks since the page->count is kept > 1 for as long
1004  *        as the page has a write request pending.
1005  */
1006 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1007 {
1008         struct nfs_write_data   *data = calldata;
1009         struct nfs_page         *req;
1010         struct page             *page;
1011
1012         if (nfs_writeback_done(task, data) != 0)
1013                 return;
1014
1015         /* Update attributes as result of writeback. */
1016         while (!list_empty(&data->pages)) {
1017                 req = nfs_list_entry(data->pages.next);
1018                 nfs_list_remove_request(req);
1019                 page = req->wb_page;
1020
1021                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1022                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1023                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1024                         req->wb_bytes,
1025                         (long long)req_offset(req));
1026
1027                 if (task->tk_status < 0) {
1028                         nfs_set_pageerror(page);
1029                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1030                         dprintk(", error = %d\n", task->tk_status);
1031                         goto remove_request;
1032                 }
1033
1034                 if (nfs_write_need_commit(data)) {
1035                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1036                         nfs_mark_request_commit(req);
1037                         nfs_end_page_writeback(page);
1038                         dprintk(" marked for commit\n");
1039                         goto next;
1040                 }
1041                 /* Set the PG_uptodate flag? */
1042                 nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
1043                 dprintk(" OK\n");
1044 remove_request:
1045                 nfs_end_page_writeback(page);
1046                 nfs_inode_remove_request(req);
1047         next:
1048                 nfs_clear_page_tag_locked(req);
1049         }
1050 }
1051
1052 static const struct rpc_call_ops nfs_write_full_ops = {
1053         .rpc_call_done = nfs_writeback_done_full,
1054         .rpc_release = nfs_writedata_release,
1055 };
1056
1057
1058 /*
1059  * This function is called when the WRITE call is complete.
1060  */
1061 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1062 {
1063         struct nfs_writeargs    *argp = &data->args;
1064         struct nfs_writeres     *resp = &data->res;
1065         int status;
1066
1067         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1068                 task->tk_pid, task->tk_status);
1069
1070         /*
1071          * ->write_done will attempt to use post-op attributes to detect
1072          * conflicting writes by other clients.  A strict interpretation
1073          * of close-to-open would allow us to continue caching even if
1074          * another writer had changed the file, but some applications
1075          * depend on tighter cache coherency when writing.
1076          */
1077         status = NFS_PROTO(data->inode)->write_done(task, data);
1078         if (status != 0)
1079                 return status;
1080         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1081
1082 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1083         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1084                 /* We tried a write call, but the server did not
1085                  * commit data to stable storage even though we
1086                  * requested it.
1087                  * Note: There is a known bug in Tru64 < 5.0 in which
1088                  *       the server reports NFS_DATA_SYNC, but performs
1089                  *       NFS_FILE_SYNC. We therefore implement this checking
1090                  *       as a dprintk() in order to avoid filling syslog.
1091                  */
1092                 static unsigned long    complain;
1093
1094                 if (time_before(complain, jiffies)) {
1095                         dprintk("NFS: faulty NFS server %s:"
1096                                 " (committed = %d) != (stable = %d)\n",
1097                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1098                                 resp->verf->committed, argp->stable);
1099                         complain = jiffies + 300 * HZ;
1100                 }
1101         }
1102 #endif
1103         /* Is this a short write? */
1104         if (task->tk_status >= 0 && resp->count < argp->count) {
1105                 static unsigned long    complain;
1106
1107                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1108
1109                 /* Has the server at least made some progress? */
1110                 if (resp->count != 0) {
1111                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1112                         if (resp->verf->committed != NFS_UNSTABLE) {
1113                                 /* Resend from where the server left off */
1114                                 argp->offset += resp->count;
1115                                 argp->pgbase += resp->count;
1116                                 argp->count -= resp->count;
1117                         } else {
1118                                 /* Resend as a stable write in order to avoid
1119                                  * headaches in the case of a server crash.
1120                                  */
1121                                 argp->stable = NFS_FILE_SYNC;
1122                         }
1123                         rpc_restart_call(task);
1124                         return -EAGAIN;
1125                 }
1126                 if (time_before(complain, jiffies)) {
1127                         printk(KERN_WARNING
1128                                "NFS: Server wrote zero bytes, expected %u.\n",
1129                                         argp->count);
1130                         complain = jiffies + 300 * HZ;
1131                 }
1132                 /* Can't do anything about it except throw an error. */
1133                 task->tk_status = -EIO;
1134         }
1135         return 0;
1136 }
1137
1138
1139 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1140 void nfs_commit_release(void *wdata)
1141 {
1142         nfs_commit_free(wdata);
1143 }
1144
1145 /*
1146  * Set up the argument/result storage required for the RPC call.
1147  */
1148 static void nfs_commit_rpcsetup(struct list_head *head,
1149                 struct nfs_write_data *data,
1150                 int how)
1151 {
1152         struct nfs_page *first = nfs_list_entry(head->next);
1153         struct inode *inode = first->wb_context->path.dentry->d_inode;
1154         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1155         struct rpc_task_setup task_setup_data = {
1156                 .rpc_client = NFS_CLIENT(inode),
1157                 .callback_ops = &nfs_commit_ops,
1158                 .callback_data = data,
1159                 .flags = flags,
1160         };
1161
1162         /* Set up the RPC argument and reply structs
1163          * NB: take care not to mess about with data->commit et al. */
1164
1165         list_splice_init(head, &data->pages);
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         rpc_init_task(&data->task, &task_setup_data);
1181         NFS_PROTO(inode)->commit_setup(data, how);
1182
1183         data->task.tk_priority = flush_task_priority(how);
1184         data->task.tk_cookie = (unsigned long)inode;
1185         
1186         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1187 }
1188
1189 /*
1190  * Commit dirty pages
1191  */
1192 static int
1193 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1194 {
1195         struct nfs_write_data   *data;
1196         struct nfs_page         *req;
1197
1198         data = nfs_commit_alloc();
1199
1200         if (!data)
1201                 goto out_bad;
1202
1203         /* Set up the argument struct */
1204         nfs_commit_rpcsetup(head, data, how);
1205
1206         nfs_execute_write(data);
1207         return 0;
1208  out_bad:
1209         while (!list_empty(head)) {
1210                 req = nfs_list_entry(head->next);
1211                 nfs_list_remove_request(req);
1212                 nfs_mark_request_commit(req);
1213                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1214                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1215                                 BDI_RECLAIMABLE);
1216                 nfs_clear_page_tag_locked(req);
1217         }
1218         return -ENOMEM;
1219 }
1220
1221 /*
1222  * COMMIT call returned
1223  */
1224 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1225 {
1226         struct nfs_write_data   *data = calldata;
1227         struct nfs_page         *req;
1228
1229         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1230                                 task->tk_pid, task->tk_status);
1231
1232         /* Call the NFS version-specific code */
1233         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1234                 return;
1235
1236         while (!list_empty(&data->pages)) {
1237                 req = nfs_list_entry(data->pages.next);
1238                 nfs_list_remove_request(req);
1239                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
1240                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1241                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1242                                 BDI_RECLAIMABLE);
1243
1244                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1245                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1246                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1247                         req->wb_bytes,
1248                         (long long)req_offset(req));
1249                 if (task->tk_status < 0) {
1250                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1251                         nfs_inode_remove_request(req);
1252                         dprintk(", error = %d\n", task->tk_status);
1253                         goto next;
1254                 }
1255
1256                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1257                  * returned by the server against all stored verfs. */
1258                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1259                         /* We have a match */
1260                         /* Set the PG_uptodate flag */
1261                         nfs_mark_uptodate(req->wb_page, req->wb_pgbase,
1262                                         req->wb_bytes);
1263                         nfs_inode_remove_request(req);
1264                         dprintk(" OK\n");
1265                         goto next;
1266                 }
1267                 /* We have a mismatch. Write the page again */
1268                 dprintk(" mismatch\n");
1269                 nfs_redirty_request(req);
1270         next:
1271                 nfs_clear_page_tag_locked(req);
1272         }
1273 }
1274
1275 static const struct rpc_call_ops nfs_commit_ops = {
1276         .rpc_call_done = nfs_commit_done,
1277         .rpc_release = nfs_commit_release,
1278 };
1279
1280 int nfs_commit_inode(struct inode *inode, int how)
1281 {
1282         LIST_HEAD(head);
1283         int res;
1284
1285         spin_lock(&inode->i_lock);
1286         res = nfs_scan_commit(inode, &head, 0, 0);
1287         spin_unlock(&inode->i_lock);
1288         if (res) {
1289                 int error = nfs_commit_list(inode, &head, how);
1290                 if (error < 0)
1291                         return error;
1292         }
1293         return res;
1294 }
1295 #else
1296 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1297 {
1298         return 0;
1299 }
1300 #endif
1301
1302 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1303 {
1304         struct inode *inode = mapping->host;
1305         pgoff_t idx_start, idx_end;
1306         unsigned int npages = 0;
1307         LIST_HEAD(head);
1308         int nocommit = how & FLUSH_NOCOMMIT;
1309         long pages, ret;
1310
1311         /* FIXME */
1312         if (wbc->range_cyclic)
1313                 idx_start = 0;
1314         else {
1315                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1316                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1317                 if (idx_end > idx_start) {
1318                         pgoff_t l_npages = 1 + idx_end - idx_start;
1319                         npages = l_npages;
1320                         if (sizeof(npages) != sizeof(l_npages) &&
1321                                         (pgoff_t)npages != l_npages)
1322                                 npages = 0;
1323                 }
1324         }
1325         how &= ~FLUSH_NOCOMMIT;
1326         spin_lock(&inode->i_lock);
1327         do {
1328                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1329                 if (ret != 0)
1330                         continue;
1331                 if (nocommit)
1332                         break;
1333                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1334                 if (pages == 0)
1335                         break;
1336                 if (how & FLUSH_INVALIDATE) {
1337                         spin_unlock(&inode->i_lock);
1338                         nfs_cancel_commit_list(&head);
1339                         ret = pages;
1340                         spin_lock(&inode->i_lock);
1341                         continue;
1342                 }
1343                 pages += nfs_scan_commit(inode, &head, 0, 0);
1344                 spin_unlock(&inode->i_lock);
1345                 ret = nfs_commit_list(inode, &head, how);
1346                 spin_lock(&inode->i_lock);
1347
1348         } while (ret >= 0);
1349         spin_unlock(&inode->i_lock);
1350         return ret;
1351 }
1352
1353 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1354 {
1355         int ret;
1356
1357         ret = nfs_writepages(mapping, wbc);
1358         if (ret < 0)
1359                 goto out;
1360         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1361         if (ret < 0)
1362                 goto out;
1363         return 0;
1364 out:
1365         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1366         return ret;
1367 }
1368
1369 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1370 static int nfs_write_mapping(struct address_space *mapping, int how)
1371 {
1372         struct writeback_control wbc = {
1373                 .bdi = mapping->backing_dev_info,
1374                 .sync_mode = WB_SYNC_NONE,
1375                 .nr_to_write = LONG_MAX,
1376                 .for_writepages = 1,
1377                 .range_cyclic = 1,
1378         };
1379         int ret;
1380
1381         ret = __nfs_write_mapping(mapping, &wbc, how);
1382         if (ret < 0)
1383                 return ret;
1384         wbc.sync_mode = WB_SYNC_ALL;
1385         return __nfs_write_mapping(mapping, &wbc, how);
1386 }
1387
1388 /*
1389  * flush the inode to disk.
1390  */
1391 int nfs_wb_all(struct inode *inode)
1392 {
1393         return nfs_write_mapping(inode->i_mapping, 0);
1394 }
1395
1396 int nfs_wb_nocommit(struct inode *inode)
1397 {
1398         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1399 }
1400
1401 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1402 {
1403         struct nfs_page *req;
1404         loff_t range_start = page_offset(page);
1405         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1406         struct writeback_control wbc = {
1407                 .bdi = page->mapping->backing_dev_info,
1408                 .sync_mode = WB_SYNC_ALL,
1409                 .nr_to_write = LONG_MAX,
1410                 .range_start = range_start,
1411                 .range_end = range_end,
1412         };
1413         int ret = 0;
1414
1415         BUG_ON(!PageLocked(page));
1416         for (;;) {
1417                 req = nfs_page_find_request(page);
1418                 if (req == NULL)
1419                         goto out;
1420                 if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1421                         nfs_release_request(req);
1422                         break;
1423                 }
1424                 if (nfs_lock_request_dontget(req)) {
1425                         nfs_inode_remove_request(req);
1426                         /*
1427                          * In case nfs_inode_remove_request has marked the
1428                          * page as being dirty
1429                          */
1430                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1431                         nfs_unlock_request(req);
1432                         break;
1433                 }
1434                 ret = nfs_wait_on_request(req);
1435                 if (ret < 0)
1436                         goto out;
1437         }
1438         if (!PagePrivate(page))
1439                 return 0;
1440         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1441 out:
1442         return ret;
1443 }
1444
1445 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1446                                 int how)
1447 {
1448         loff_t range_start = page_offset(page);
1449         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1450         struct writeback_control wbc = {
1451                 .bdi = page->mapping->backing_dev_info,
1452                 .sync_mode = WB_SYNC_ALL,
1453                 .nr_to_write = LONG_MAX,
1454                 .range_start = range_start,
1455                 .range_end = range_end,
1456         };
1457         int ret;
1458
1459         BUG_ON(!PageLocked(page));
1460         if (clear_page_dirty_for_io(page)) {
1461                 ret = nfs_writepage_locked(page, &wbc);
1462                 if (ret < 0)
1463                         goto out;
1464         }
1465         if (!PagePrivate(page))
1466                 return 0;
1467         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1468         if (ret >= 0)
1469                 return 0;
1470 out:
1471         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1472         return ret;
1473 }
1474
1475 /*
1476  * Write back all requests on one page - we do this before reading it.
1477  */
1478 int nfs_wb_page(struct inode *inode, struct page* page)
1479 {
1480         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1481 }
1482
1483 int __init nfs_init_writepagecache(void)
1484 {
1485         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1486                                              sizeof(struct nfs_write_data),
1487                                              0, SLAB_HWCACHE_ALIGN,
1488                                              NULL);
1489         if (nfs_wdata_cachep == NULL)
1490                 return -ENOMEM;
1491
1492         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1493                                                      nfs_wdata_cachep);
1494         if (nfs_wdata_mempool == NULL)
1495                 return -ENOMEM;
1496
1497         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1498                                                       nfs_wdata_cachep);
1499         if (nfs_commit_mempool == NULL)
1500                 return -ENOMEM;
1501
1502         /*
1503          * NFS congestion size, scale with available memory.
1504          *
1505          *  64MB:    8192k
1506          * 128MB:   11585k
1507          * 256MB:   16384k
1508          * 512MB:   23170k
1509          *   1GB:   32768k
1510          *   2GB:   46340k
1511          *   4GB:   65536k
1512          *   8GB:   92681k
1513          *  16GB:  131072k
1514          *
1515          * This allows larger machines to have larger/more transfers.
1516          * Limit the default to 256M
1517          */
1518         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1519         if (nfs_congestion_kb > 256*1024)
1520                 nfs_congestion_kb = 256*1024;
1521
1522         return 0;
1523 }
1524
1525 void nfs_destroy_writepagecache(void)
1526 {
1527         mempool_destroy(nfs_commit_mempool);
1528         mempool_destroy(nfs_wdata_mempool);
1529         kmem_cache_destroy(nfs_wdata_cachep);
1530 }
1531