Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[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 void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
38                                   struct inode *inode, int ioflags);
39 static void nfs_redirty_request(struct nfs_page *req);
40 static const struct rpc_call_ops nfs_write_partial_ops;
41 static const struct rpc_call_ops nfs_write_full_ops;
42 static const struct rpc_call_ops nfs_commit_ops;
43
44 static struct kmem_cache *nfs_wdata_cachep;
45 static mempool_t *nfs_wdata_mempool;
46 static mempool_t *nfs_commit_mempool;
47
48 struct nfs_write_data *nfs_commitdata_alloc(void)
49 {
50         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
51
52         if (p) {
53                 memset(p, 0, sizeof(*p));
54                 INIT_LIST_HEAD(&p->pages);
55         }
56         return p;
57 }
58
59 void nfs_commit_free(struct nfs_write_data *p)
60 {
61         if (p && (p->pagevec != &p->page_array[0]))
62                 kfree(p->pagevec);
63         mempool_free(p, nfs_commit_mempool);
64 }
65
66 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
67 {
68         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
69
70         if (p) {
71                 memset(p, 0, sizeof(*p));
72                 INIT_LIST_HEAD(&p->pages);
73                 p->npages = pagecount;
74                 if (pagecount <= ARRAY_SIZE(p->page_array))
75                         p->pagevec = p->page_array;
76                 else {
77                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
78                         if (!p->pagevec) {
79                                 mempool_free(p, nfs_wdata_mempool);
80                                 p = NULL;
81                         }
82                 }
83         }
84         return p;
85 }
86
87 static void nfs_writedata_free(struct nfs_write_data *p)
88 {
89         if (p && (p->pagevec != &p->page_array[0]))
90                 kfree(p->pagevec);
91         mempool_free(p, nfs_wdata_mempool);
92 }
93
94 void nfs_writedata_release(void *data)
95 {
96         struct nfs_write_data *wdata = data;
97
98         put_nfs_open_context(wdata->args.context);
99         nfs_writedata_free(wdata);
100 }
101
102 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
103 {
104         ctx->error = error;
105         smp_wmb();
106         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
107 }
108
109 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
110 {
111         struct nfs_page *req = NULL;
112
113         if (PagePrivate(page)) {
114                 req = (struct nfs_page *)page_private(page);
115                 if (req != NULL)
116                         kref_get(&req->wb_kref);
117         }
118         return req;
119 }
120
121 static struct nfs_page *nfs_page_find_request(struct page *page)
122 {
123         struct inode *inode = page->mapping->host;
124         struct nfs_page *req = NULL;
125
126         spin_lock(&inode->i_lock);
127         req = nfs_page_find_request_locked(page);
128         spin_unlock(&inode->i_lock);
129         return req;
130 }
131
132 /* Adjust the file length if we're writing beyond the end */
133 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
134 {
135         struct inode *inode = page->mapping->host;
136         loff_t end, i_size;
137         pgoff_t end_index;
138
139         spin_lock(&inode->i_lock);
140         i_size = i_size_read(inode);
141         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
142         if (i_size > 0 && page->index < end_index)
143                 goto out;
144         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
145         if (i_size >= end)
146                 goto out;
147         i_size_write(inode, end);
148         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
149 out:
150         spin_unlock(&inode->i_lock);
151 }
152
153 /* A writeback failed: mark the page as bad, and invalidate the page cache */
154 static void nfs_set_pageerror(struct page *page)
155 {
156         SetPageError(page);
157         nfs_zap_mapping(page->mapping->host, page->mapping);
158 }
159
160 /* We can set the PG_uptodate flag if we see that a write request
161  * covers the full page.
162  */
163 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
164 {
165         if (PageUptodate(page))
166                 return;
167         if (base != 0)
168                 return;
169         if (count != nfs_page_length(page))
170                 return;
171         SetPageUptodate(page);
172 }
173
174 static int wb_priority(struct writeback_control *wbc)
175 {
176         if (wbc->for_reclaim)
177                 return FLUSH_HIGHPRI | FLUSH_STABLE;
178         if (wbc->for_kupdate)
179                 return FLUSH_LOWPRI;
180         return 0;
181 }
182
183 /*
184  * NFS congestion control
185  */
186
187 int nfs_congestion_kb;
188
189 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
190 #define NFS_CONGESTION_OFF_THRESH       \
191         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
192
193 static int nfs_set_page_writeback(struct page *page)
194 {
195         int ret = test_set_page_writeback(page);
196
197         if (!ret) {
198                 struct inode *inode = page->mapping->host;
199                 struct nfs_server *nfss = NFS_SERVER(inode);
200
201                 if (atomic_long_inc_return(&nfss->writeback) >
202                                 NFS_CONGESTION_ON_THRESH)
203                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
204         }
205         return ret;
206 }
207
208 static void nfs_end_page_writeback(struct page *page)
209 {
210         struct inode *inode = page->mapping->host;
211         struct nfs_server *nfss = NFS_SERVER(inode);
212
213         end_page_writeback(page);
214         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
215                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
216 }
217
218 /*
219  * Find an associated nfs write request, and prepare to flush it out
220  * May return an error if the user signalled nfs_wait_on_request().
221  */
222 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
223                                 struct page *page)
224 {
225         struct inode *inode = page->mapping->host;
226         struct nfs_page *req;
227         int ret;
228
229         spin_lock(&inode->i_lock);
230         for(;;) {
231                 req = nfs_page_find_request_locked(page);
232                 if (req == NULL) {
233                         spin_unlock(&inode->i_lock);
234                         return 0;
235                 }
236                 if (nfs_set_page_tag_locked(req))
237                         break;
238                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
239                  *       then the call to nfs_set_page_tag_locked() will always
240                  *       succeed provided that someone hasn't already marked the
241                  *       request as dirty (in which case we don't care).
242                  */
243                 spin_unlock(&inode->i_lock);
244                 ret = nfs_wait_on_request(req);
245                 nfs_release_request(req);
246                 if (ret != 0)
247                         return ret;
248                 spin_lock(&inode->i_lock);
249         }
250         if (test_bit(PG_CLEAN, &req->wb_flags)) {
251                 spin_unlock(&inode->i_lock);
252                 BUG();
253         }
254         if (nfs_set_page_writeback(page) != 0) {
255                 spin_unlock(&inode->i_lock);
256                 BUG();
257         }
258         spin_unlock(&inode->i_lock);
259         if (!nfs_pageio_add_request(pgio, req)) {
260                 nfs_redirty_request(req);
261                 return pgio->pg_error;
262         }
263         return 0;
264 }
265
266 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
267 {
268         struct inode *inode = page->mapping->host;
269
270         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
271         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
272
273         nfs_pageio_cond_complete(pgio, page->index);
274         return nfs_page_async_flush(pgio, page);
275 }
276
277 /*
278  * Write an mmapped page to the server.
279  */
280 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
281 {
282         struct nfs_pageio_descriptor pgio;
283         int err;
284
285         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
286         err = nfs_do_writepage(page, wbc, &pgio);
287         nfs_pageio_complete(&pgio);
288         if (err < 0)
289                 return err;
290         if (pgio.pg_error < 0)
291                 return pgio.pg_error;
292         return 0;
293 }
294
295 int nfs_writepage(struct page *page, struct writeback_control *wbc)
296 {
297         int ret;
298
299         ret = nfs_writepage_locked(page, wbc);
300         unlock_page(page);
301         return ret;
302 }
303
304 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
305 {
306         int ret;
307
308         ret = nfs_do_writepage(page, wbc, data);
309         unlock_page(page);
310         return ret;
311 }
312
313 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
314 {
315         struct inode *inode = mapping->host;
316         struct nfs_pageio_descriptor pgio;
317         int err;
318
319         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
320
321         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
322         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
323         nfs_pageio_complete(&pgio);
324         if (err < 0)
325                 return err;
326         if (pgio.pg_error < 0)
327                 return pgio.pg_error;
328         return 0;
329 }
330
331 /*
332  * Insert a write request into an inode
333  */
334 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
335 {
336         struct nfs_inode *nfsi = NFS_I(inode);
337         int error;
338
339         error = radix_tree_preload(GFP_NOFS);
340         if (error != 0)
341                 goto out;
342
343         /* Lock the request! */
344         nfs_lock_request_dontget(req);
345
346         spin_lock(&inode->i_lock);
347         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
348         BUG_ON(error);
349         if (!nfsi->npages) {
350                 igrab(inode);
351                 if (nfs_have_delegation(inode, FMODE_WRITE))
352                         nfsi->change_attr++;
353         }
354         SetPagePrivate(req->wb_page);
355         set_page_private(req->wb_page, (unsigned long)req);
356         nfsi->npages++;
357         kref_get(&req->wb_kref);
358         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
359                                 NFS_PAGE_TAG_LOCKED);
360         spin_unlock(&inode->i_lock);
361         radix_tree_preload_end();
362 out:
363         return error;
364 }
365
366 /*
367  * Remove a write request from an inode
368  */
369 static void nfs_inode_remove_request(struct nfs_page *req)
370 {
371         struct inode *inode = req->wb_context->path.dentry->d_inode;
372         struct nfs_inode *nfsi = NFS_I(inode);
373
374         BUG_ON (!NFS_WBACK_BUSY(req));
375
376         spin_lock(&inode->i_lock);
377         set_page_private(req->wb_page, 0);
378         ClearPagePrivate(req->wb_page);
379         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
380         nfsi->npages--;
381         if (!nfsi->npages) {
382                 spin_unlock(&inode->i_lock);
383                 iput(inode);
384         } else
385                 spin_unlock(&inode->i_lock);
386         nfs_clear_request(req);
387         nfs_release_request(req);
388 }
389
390 static void
391 nfs_mark_request_dirty(struct nfs_page *req)
392 {
393         __set_page_dirty_nobuffers(req->wb_page);
394 }
395
396 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
397 /*
398  * Add a request to the inode's commit list.
399  */
400 static void
401 nfs_mark_request_commit(struct nfs_page *req)
402 {
403         struct inode *inode = req->wb_context->path.dentry->d_inode;
404         struct nfs_inode *nfsi = NFS_I(inode);
405
406         spin_lock(&inode->i_lock);
407         nfsi->ncommit++;
408         set_bit(PG_CLEAN, &(req)->wb_flags);
409         radix_tree_tag_set(&nfsi->nfs_page_tree,
410                         req->wb_index,
411                         NFS_PAGE_TAG_COMMIT);
412         spin_unlock(&inode->i_lock);
413         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
414         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
415         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
416 }
417
418 static int
419 nfs_clear_request_commit(struct nfs_page *req)
420 {
421         struct page *page = req->wb_page;
422
423         if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
424                 dec_zone_page_state(page, NR_UNSTABLE_NFS);
425                 dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
426                 return 1;
427         }
428         return 0;
429 }
430
431 static inline
432 int nfs_write_need_commit(struct nfs_write_data *data)
433 {
434         return data->verf.committed != NFS_FILE_SYNC;
435 }
436
437 static inline
438 int nfs_reschedule_unstable_write(struct nfs_page *req)
439 {
440         if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
441                 nfs_mark_request_commit(req);
442                 return 1;
443         }
444         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
445                 nfs_mark_request_dirty(req);
446                 return 1;
447         }
448         return 0;
449 }
450 #else
451 static inline void
452 nfs_mark_request_commit(struct nfs_page *req)
453 {
454 }
455
456 static inline int
457 nfs_clear_request_commit(struct nfs_page *req)
458 {
459         return 0;
460 }
461
462 static inline
463 int nfs_write_need_commit(struct nfs_write_data *data)
464 {
465         return 0;
466 }
467
468 static inline
469 int nfs_reschedule_unstable_write(struct nfs_page *req)
470 {
471         return 0;
472 }
473 #endif
474
475 /*
476  * Wait for a request to complete.
477  *
478  * Interruptible by fatal signals only.
479  */
480 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
481 {
482         struct nfs_inode *nfsi = NFS_I(inode);
483         struct nfs_page *req;
484         pgoff_t idx_end, next;
485         unsigned int            res = 0;
486         int                     error;
487
488         if (npages == 0)
489                 idx_end = ~0;
490         else
491                 idx_end = idx_start + npages - 1;
492
493         next = idx_start;
494         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
495                 if (req->wb_index > idx_end)
496                         break;
497
498                 next = req->wb_index + 1;
499                 BUG_ON(!NFS_WBACK_BUSY(req));
500
501                 kref_get(&req->wb_kref);
502                 spin_unlock(&inode->i_lock);
503                 error = nfs_wait_on_request(req);
504                 nfs_release_request(req);
505                 spin_lock(&inode->i_lock);
506                 if (error < 0)
507                         return error;
508                 res++;
509         }
510         return res;
511 }
512
513 static void nfs_cancel_commit_list(struct list_head *head)
514 {
515         struct nfs_page *req;
516
517         while(!list_empty(head)) {
518                 req = nfs_list_entry(head->next);
519                 nfs_list_remove_request(req);
520                 nfs_clear_request_commit(req);
521                 nfs_inode_remove_request(req);
522                 nfs_unlock_request(req);
523         }
524 }
525
526 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
527 /*
528  * nfs_scan_commit - Scan an inode for commit requests
529  * @inode: NFS inode to scan
530  * @dst: destination list
531  * @idx_start: lower bound of page->index to scan.
532  * @npages: idx_start + npages sets the upper bound to scan.
533  *
534  * Moves requests from the inode's 'commit' request list.
535  * The requests are *not* checked to ensure that they form a contiguous set.
536  */
537 static int
538 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
539 {
540         struct nfs_inode *nfsi = NFS_I(inode);
541         int res = 0;
542
543         if (nfsi->ncommit != 0) {
544                 res = nfs_scan_list(nfsi, dst, idx_start, npages,
545                                 NFS_PAGE_TAG_COMMIT);
546                 nfsi->ncommit -= res;
547         }
548         return res;
549 }
550 #else
551 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
552 {
553         return 0;
554 }
555 #endif
556
557 /*
558  * Search for an existing write request, and attempt to update
559  * it to reflect a new dirty region on a given page.
560  *
561  * If the attempt fails, then the existing request is flushed out
562  * to disk.
563  */
564 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
565                 struct page *page,
566                 unsigned int offset,
567                 unsigned int bytes)
568 {
569         struct nfs_page *req;
570         unsigned int rqend;
571         unsigned int end;
572         int error;
573
574         if (!PagePrivate(page))
575                 return NULL;
576
577         end = offset + bytes;
578         spin_lock(&inode->i_lock);
579
580         for (;;) {
581                 req = nfs_page_find_request_locked(page);
582                 if (req == NULL)
583                         goto out_unlock;
584
585                 rqend = req->wb_offset + req->wb_bytes;
586                 /*
587                  * Tell the caller to flush out the request if
588                  * the offsets are non-contiguous.
589                  * Note: nfs_flush_incompatible() will already
590                  * have flushed out requests having wrong owners.
591                  */
592                 if (offset > rqend
593                     || end < req->wb_offset)
594                         goto out_flushme;
595
596                 if (nfs_set_page_tag_locked(req))
597                         break;
598
599                 /* The request is locked, so wait and then retry */
600                 spin_unlock(&inode->i_lock);
601                 error = nfs_wait_on_request(req);
602                 nfs_release_request(req);
603                 if (error != 0)
604                         goto out_err;
605                 spin_lock(&inode->i_lock);
606         }
607
608         if (nfs_clear_request_commit(req))
609                 radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
610                                 req->wb_index, NFS_PAGE_TAG_COMMIT);
611
612         /* Okay, the request matches. Update the region */
613         if (offset < req->wb_offset) {
614                 req->wb_offset = offset;
615                 req->wb_pgbase = offset;
616         }
617         if (end > rqend)
618                 req->wb_bytes = end - req->wb_offset;
619         else
620                 req->wb_bytes = rqend - req->wb_offset;
621 out_unlock:
622         spin_unlock(&inode->i_lock);
623         return req;
624 out_flushme:
625         spin_unlock(&inode->i_lock);
626         nfs_release_request(req);
627         error = nfs_wb_page(inode, page);
628 out_err:
629         return ERR_PTR(error);
630 }
631
632 /*
633  * Try to update an existing write request, or create one if there is none.
634  *
635  * Note: Should always be called with the Page Lock held to prevent races
636  * if we have to add a new request. Also assumes that the caller has
637  * already called nfs_flush_incompatible() if necessary.
638  */
639 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
640                 struct page *page, unsigned int offset, unsigned int bytes)
641 {
642         struct inode *inode = page->mapping->host;
643         struct nfs_page *req;
644         int error;
645
646         req = nfs_try_to_update_request(inode, page, offset, bytes);
647         if (req != NULL)
648                 goto out;
649         req = nfs_create_request(ctx, inode, page, offset, bytes);
650         if (IS_ERR(req))
651                 goto out;
652         error = nfs_inode_add_request(inode, req);
653         if (error != 0) {
654                 nfs_release_request(req);
655                 req = ERR_PTR(error);
656         }
657 out:
658         return req;
659 }
660
661 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
662                 unsigned int offset, unsigned int count)
663 {
664         struct nfs_page *req;
665
666         req = nfs_setup_write_request(ctx, page, offset, count);
667         if (IS_ERR(req))
668                 return PTR_ERR(req);
669         /* Update file length */
670         nfs_grow_file(page, offset, count);
671         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
672         nfs_clear_page_tag_locked(req);
673         return 0;
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_release_request(req);
695                 if (!do_flush)
696                         return 0;
697                 status = nfs_wb_page(page->mapping->host, page);
698         } while (status == 0);
699         return status;
700 }
701
702 /*
703  * If the page cache is marked as unsafe or invalid, then we can't rely on
704  * the PageUptodate() flag. In this case, we will need to turn off
705  * write optimisations that depend on the page contents being correct.
706  */
707 static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
708 {
709         return PageUptodate(page) &&
710                 !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
711 }
712
713 /*
714  * Update and possibly write a cached page of an NFS file.
715  *
716  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
717  * things with a page scheduled for an RPC call (e.g. invalidate it).
718  */
719 int nfs_updatepage(struct file *file, struct page *page,
720                 unsigned int offset, unsigned int count)
721 {
722         struct nfs_open_context *ctx = nfs_file_open_context(file);
723         struct inode    *inode = page->mapping->host;
724         int             status = 0;
725
726         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
727
728         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
729                 file->f_path.dentry->d_parent->d_name.name,
730                 file->f_path.dentry->d_name.name, count,
731                 (long long)(page_offset(page) + offset));
732
733         /* If we're not using byte range locks, and we know the page
734          * is up to date, it may be more efficient to extend the write
735          * to cover the entire page in order to avoid fragmentation
736          * inefficiencies.
737          */
738         if (nfs_write_pageuptodate(page, inode) &&
739                         inode->i_flock == NULL &&
740                         !(file->f_flags & O_SYNC)) {
741                 count = max(count + offset, nfs_page_length(page));
742                 offset = 0;
743         }
744
745         status = nfs_writepage_setup(ctx, page, offset, count);
746         if (status < 0)
747                 nfs_set_pageerror(page);
748         else
749                 __set_page_dirty_nobuffers(page);
750
751         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
752                         status, (long long)i_size_read(inode));
753         return status;
754 }
755
756 static void nfs_writepage_release(struct nfs_page *req)
757 {
758
759         if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req)) {
760                 nfs_end_page_writeback(req->wb_page);
761                 nfs_inode_remove_request(req);
762         } else
763                 nfs_end_page_writeback(req->wb_page);
764         nfs_clear_page_tag_locked(req);
765 }
766
767 static int flush_task_priority(int how)
768 {
769         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
770                 case FLUSH_HIGHPRI:
771                         return RPC_PRIORITY_HIGH;
772                 case FLUSH_LOWPRI:
773                         return RPC_PRIORITY_LOW;
774         }
775         return RPC_PRIORITY_NORMAL;
776 }
777
778 /*
779  * Set up the argument/result storage required for the RPC call.
780  */
781 static int nfs_write_rpcsetup(struct nfs_page *req,
782                 struct nfs_write_data *data,
783                 const struct rpc_call_ops *call_ops,
784                 unsigned int count, unsigned int offset,
785                 int how)
786 {
787         struct inode *inode = req->wb_context->path.dentry->d_inode;
788         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
789         int priority = flush_task_priority(how);
790         struct rpc_task *task;
791         struct rpc_message msg = {
792                 .rpc_argp = &data->args,
793                 .rpc_resp = &data->res,
794                 .rpc_cred = req->wb_context->cred,
795         };
796         struct rpc_task_setup task_setup_data = {
797                 .rpc_client = NFS_CLIENT(inode),
798                 .task = &data->task,
799                 .rpc_message = &msg,
800                 .callback_ops = call_ops,
801                 .callback_data = data,
802                 .workqueue = nfsiod_workqueue,
803                 .flags = flags,
804                 .priority = priority,
805         };
806
807         /* Set up the RPC argument and reply structs
808          * NB: take care not to mess about with data->commit et al. */
809
810         data->req = req;
811         data->inode = inode = req->wb_context->path.dentry->d_inode;
812         data->cred = msg.rpc_cred;
813
814         data->args.fh     = NFS_FH(inode);
815         data->args.offset = req_offset(req) + offset;
816         data->args.pgbase = req->wb_pgbase + offset;
817         data->args.pages  = data->pagevec;
818         data->args.count  = count;
819         data->args.context = get_nfs_open_context(req->wb_context);
820         data->args.stable  = NFS_UNSTABLE;
821         if (how & FLUSH_STABLE) {
822                 data->args.stable = NFS_DATA_SYNC;
823                 if (!NFS_I(inode)->ncommit)
824                         data->args.stable = NFS_FILE_SYNC;
825         }
826
827         data->res.fattr   = &data->fattr;
828         data->res.count   = count;
829         data->res.verf    = &data->verf;
830         nfs_fattr_init(&data->fattr);
831
832         /* Set up the initial task struct.  */
833         NFS_PROTO(inode)->write_setup(data, &msg);
834
835         dprintk("NFS: %5u initiated write call "
836                 "(req %s/%lld, %u bytes @ offset %llu)\n",
837                 data->task.tk_pid,
838                 inode->i_sb->s_id,
839                 (long long)NFS_FILEID(inode),
840                 count,
841                 (unsigned long long)data->args.offset);
842
843         task = rpc_run_task(&task_setup_data);
844         if (IS_ERR(task))
845                 return PTR_ERR(task);
846         rpc_put_task(task);
847         return 0;
848 }
849
850 /* If a nfs_flush_* function fails, it should remove reqs from @head and
851  * call this on each, which will prepare them to be retried on next
852  * writeback using standard nfs.
853  */
854 static void nfs_redirty_request(struct nfs_page *req)
855 {
856         nfs_mark_request_dirty(req);
857         nfs_end_page_writeback(req->wb_page);
858         nfs_clear_page_tag_locked(req);
859 }
860
861 /*
862  * Generate multiple small requests to write out a single
863  * contiguous dirty area on one page.
864  */
865 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
866 {
867         struct nfs_page *req = nfs_list_entry(head->next);
868         struct page *page = req->wb_page;
869         struct nfs_write_data *data;
870         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
871         unsigned int offset;
872         int requests = 0;
873         int ret = 0;
874         LIST_HEAD(list);
875
876         nfs_list_remove_request(req);
877
878         nbytes = count;
879         do {
880                 size_t len = min(nbytes, wsize);
881
882                 data = nfs_writedata_alloc(1);
883                 if (!data)
884                         goto out_bad;
885                 list_add(&data->pages, &list);
886                 requests++;
887                 nbytes -= len;
888         } while (nbytes != 0);
889         atomic_set(&req->wb_complete, requests);
890
891         ClearPageError(page);
892         offset = 0;
893         nbytes = count;
894         do {
895                 int ret2;
896
897                 data = list_entry(list.next, struct nfs_write_data, pages);
898                 list_del_init(&data->pages);
899
900                 data->pagevec[0] = page;
901
902                 if (nbytes < wsize)
903                         wsize = nbytes;
904                 ret2 = nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
905                                    wsize, offset, how);
906                 if (ret == 0)
907                         ret = ret2;
908                 offset += wsize;
909                 nbytes -= wsize;
910         } while (nbytes != 0);
911
912         return ret;
913
914 out_bad:
915         while (!list_empty(&list)) {
916                 data = list_entry(list.next, struct nfs_write_data, pages);
917                 list_del(&data->pages);
918                 nfs_writedata_release(data);
919         }
920         nfs_redirty_request(req);
921         return -ENOMEM;
922 }
923
924 /*
925  * Create an RPC task for the given write request and kick it.
926  * The page must have been locked by the caller.
927  *
928  * It may happen that the page we're passed is not marked dirty.
929  * This is the case if nfs_updatepage detects a conflicting request
930  * that has been written but not committed.
931  */
932 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
933 {
934         struct nfs_page         *req;
935         struct page             **pages;
936         struct nfs_write_data   *data;
937
938         data = nfs_writedata_alloc(npages);
939         if (!data)
940                 goto out_bad;
941
942         pages = data->pagevec;
943         while (!list_empty(head)) {
944                 req = nfs_list_entry(head->next);
945                 nfs_list_remove_request(req);
946                 nfs_list_add_request(req, &data->pages);
947                 ClearPageError(req->wb_page);
948                 *pages++ = req->wb_page;
949         }
950         req = nfs_list_entry(data->pages.next);
951
952         /* Set up the argument struct */
953         return nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
954  out_bad:
955         while (!list_empty(head)) {
956                 req = nfs_list_entry(head->next);
957                 nfs_list_remove_request(req);
958                 nfs_redirty_request(req);
959         }
960         return -ENOMEM;
961 }
962
963 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
964                                   struct inode *inode, int ioflags)
965 {
966         size_t wsize = NFS_SERVER(inode)->wsize;
967
968         if (wsize < PAGE_CACHE_SIZE)
969                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
970         else
971                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
972 }
973
974 /*
975  * Handle a write reply that flushed part of a page.
976  */
977 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
978 {
979         struct nfs_write_data   *data = calldata;
980
981         dprintk("NFS: %5u write(%s/%lld %d@%lld)",
982                 task->tk_pid,
983                 data->req->wb_context->path.dentry->d_inode->i_sb->s_id,
984                 (long long)
985                   NFS_FILEID(data->req->wb_context->path.dentry->d_inode),
986                 data->req->wb_bytes, (long long)req_offset(data->req));
987
988         nfs_writeback_done(task, data);
989 }
990
991 static void nfs_writeback_release_partial(void *calldata)
992 {
993         struct nfs_write_data   *data = calldata;
994         struct nfs_page         *req = data->req;
995         struct page             *page = req->wb_page;
996         int status = data->task.tk_status;
997
998         if (status < 0) {
999                 nfs_set_pageerror(page);
1000                 nfs_context_set_write_error(req->wb_context, status);
1001                 dprintk(", error = %d\n", status);
1002                 goto out;
1003         }
1004
1005         if (nfs_write_need_commit(data)) {
1006                 struct inode *inode = page->mapping->host;
1007
1008                 spin_lock(&inode->i_lock);
1009                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
1010                         /* Do nothing we need to resend the writes */
1011                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1012                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1013                         dprintk(" defer commit\n");
1014                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1015                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
1016                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
1017                         dprintk(" server reboot detected\n");
1018                 }
1019                 spin_unlock(&inode->i_lock);
1020         } else
1021                 dprintk(" OK\n");
1022
1023 out:
1024         if (atomic_dec_and_test(&req->wb_complete))
1025                 nfs_writepage_release(req);
1026         nfs_writedata_release(calldata);
1027 }
1028
1029 static const struct rpc_call_ops nfs_write_partial_ops = {
1030         .rpc_call_done = nfs_writeback_done_partial,
1031         .rpc_release = nfs_writeback_release_partial,
1032 };
1033
1034 /*
1035  * Handle a write reply that flushes a whole page.
1036  *
1037  * FIXME: There is an inherent race with invalidate_inode_pages and
1038  *        writebacks since the page->count is kept > 1 for as long
1039  *        as the page has a write request pending.
1040  */
1041 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1042 {
1043         struct nfs_write_data   *data = calldata;
1044
1045         nfs_writeback_done(task, data);
1046 }
1047
1048 static void nfs_writeback_release_full(void *calldata)
1049 {
1050         struct nfs_write_data   *data = calldata;
1051         int status = data->task.tk_status;
1052
1053         /* Update attributes as result of writeback. */
1054         while (!list_empty(&data->pages)) {
1055                 struct nfs_page *req = nfs_list_entry(data->pages.next);
1056                 struct page *page = req->wb_page;
1057
1058                 nfs_list_remove_request(req);
1059
1060                 dprintk("NFS: %5u write (%s/%lld %d@%lld)",
1061                         data->task.tk_pid,
1062                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1063                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1064                         req->wb_bytes,
1065                         (long long)req_offset(req));
1066
1067                 if (status < 0) {
1068                         nfs_set_pageerror(page);
1069                         nfs_context_set_write_error(req->wb_context, status);
1070                         dprintk(", error = %d\n", status);
1071                         goto remove_request;
1072                 }
1073
1074                 if (nfs_write_need_commit(data)) {
1075                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1076                         nfs_mark_request_commit(req);
1077                         nfs_end_page_writeback(page);
1078                         dprintk(" marked for commit\n");
1079                         goto next;
1080                 }
1081                 dprintk(" OK\n");
1082 remove_request:
1083                 nfs_end_page_writeback(page);
1084                 nfs_inode_remove_request(req);
1085         next:
1086                 nfs_clear_page_tag_locked(req);
1087         }
1088         nfs_writedata_release(calldata);
1089 }
1090
1091 static const struct rpc_call_ops nfs_write_full_ops = {
1092         .rpc_call_done = nfs_writeback_done_full,
1093         .rpc_release = nfs_writeback_release_full,
1094 };
1095
1096
1097 /*
1098  * This function is called when the WRITE call is complete.
1099  */
1100 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1101 {
1102         struct nfs_writeargs    *argp = &data->args;
1103         struct nfs_writeres     *resp = &data->res;
1104         int status;
1105
1106         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1107                 task->tk_pid, task->tk_status);
1108
1109         /*
1110          * ->write_done will attempt to use post-op attributes to detect
1111          * conflicting writes by other clients.  A strict interpretation
1112          * of close-to-open would allow us to continue caching even if
1113          * another writer had changed the file, but some applications
1114          * depend on tighter cache coherency when writing.
1115          */
1116         status = NFS_PROTO(data->inode)->write_done(task, data);
1117         if (status != 0)
1118                 return status;
1119         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1120
1121 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1122         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1123                 /* We tried a write call, but the server did not
1124                  * commit data to stable storage even though we
1125                  * requested it.
1126                  * Note: There is a known bug in Tru64 < 5.0 in which
1127                  *       the server reports NFS_DATA_SYNC, but performs
1128                  *       NFS_FILE_SYNC. We therefore implement this checking
1129                  *       as a dprintk() in order to avoid filling syslog.
1130                  */
1131                 static unsigned long    complain;
1132
1133                 if (time_before(complain, jiffies)) {
1134                         dprintk("NFS:       faulty NFS server %s:"
1135                                 " (committed = %d) != (stable = %d)\n",
1136                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1137                                 resp->verf->committed, argp->stable);
1138                         complain = jiffies + 300 * HZ;
1139                 }
1140         }
1141 #endif
1142         /* Is this a short write? */
1143         if (task->tk_status >= 0 && resp->count < argp->count) {
1144                 static unsigned long    complain;
1145
1146                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1147
1148                 /* Has the server at least made some progress? */
1149                 if (resp->count != 0) {
1150                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1151                         if (resp->verf->committed != NFS_UNSTABLE) {
1152                                 /* Resend from where the server left off */
1153                                 argp->offset += resp->count;
1154                                 argp->pgbase += resp->count;
1155                                 argp->count -= resp->count;
1156                         } else {
1157                                 /* Resend as a stable write in order to avoid
1158                                  * headaches in the case of a server crash.
1159                                  */
1160                                 argp->stable = NFS_FILE_SYNC;
1161                         }
1162                         rpc_restart_call(task);
1163                         return -EAGAIN;
1164                 }
1165                 if (time_before(complain, jiffies)) {
1166                         printk(KERN_WARNING
1167                                "NFS: Server wrote zero bytes, expected %u.\n",
1168                                         argp->count);
1169                         complain = jiffies + 300 * HZ;
1170                 }
1171                 /* Can't do anything about it except throw an error. */
1172                 task->tk_status = -EIO;
1173         }
1174         return 0;
1175 }
1176
1177
1178 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1179 void nfs_commitdata_release(void *data)
1180 {
1181         struct nfs_write_data *wdata = data;
1182
1183         put_nfs_open_context(wdata->args.context);
1184         nfs_commit_free(wdata);
1185 }
1186
1187 /*
1188  * Set up the argument/result storage required for the RPC call.
1189  */
1190 static int nfs_commit_rpcsetup(struct list_head *head,
1191                 struct nfs_write_data *data,
1192                 int how)
1193 {
1194         struct nfs_page *first = nfs_list_entry(head->next);
1195         struct inode *inode = first->wb_context->path.dentry->d_inode;
1196         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1197         int priority = flush_task_priority(how);
1198         struct rpc_task *task;
1199         struct rpc_message msg = {
1200                 .rpc_argp = &data->args,
1201                 .rpc_resp = &data->res,
1202                 .rpc_cred = first->wb_context->cred,
1203         };
1204         struct rpc_task_setup task_setup_data = {
1205                 .task = &data->task,
1206                 .rpc_client = NFS_CLIENT(inode),
1207                 .rpc_message = &msg,
1208                 .callback_ops = &nfs_commit_ops,
1209                 .callback_data = data,
1210                 .workqueue = nfsiod_workqueue,
1211                 .flags = flags,
1212                 .priority = priority,
1213         };
1214
1215         /* Set up the RPC argument and reply structs
1216          * NB: take care not to mess about with data->commit et al. */
1217
1218         list_splice_init(head, &data->pages);
1219
1220         data->inode       = inode;
1221         data->cred        = msg.rpc_cred;
1222
1223         data->args.fh     = NFS_FH(data->inode);
1224         /* Note: we always request a commit of the entire inode */
1225         data->args.offset = 0;
1226         data->args.count  = 0;
1227         data->args.context = get_nfs_open_context(first->wb_context);
1228         data->res.count   = 0;
1229         data->res.fattr   = &data->fattr;
1230         data->res.verf    = &data->verf;
1231         nfs_fattr_init(&data->fattr);
1232
1233         /* Set up the initial task struct.  */
1234         NFS_PROTO(inode)->commit_setup(data, &msg);
1235
1236         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1237
1238         task = rpc_run_task(&task_setup_data);
1239         if (IS_ERR(task))
1240                 return PTR_ERR(task);
1241         rpc_put_task(task);
1242         return 0;
1243 }
1244
1245 /*
1246  * Commit dirty pages
1247  */
1248 static int
1249 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1250 {
1251         struct nfs_write_data   *data;
1252         struct nfs_page         *req;
1253
1254         data = nfs_commitdata_alloc();
1255
1256         if (!data)
1257                 goto out_bad;
1258
1259         /* Set up the argument struct */
1260         return nfs_commit_rpcsetup(head, data, how);
1261  out_bad:
1262         while (!list_empty(head)) {
1263                 req = nfs_list_entry(head->next);
1264                 nfs_list_remove_request(req);
1265                 nfs_mark_request_commit(req);
1266                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1267                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1268                                 BDI_RECLAIMABLE);
1269                 nfs_clear_page_tag_locked(req);
1270         }
1271         return -ENOMEM;
1272 }
1273
1274 /*
1275  * COMMIT call returned
1276  */
1277 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1278 {
1279         struct nfs_write_data   *data = calldata;
1280
1281         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1282                                 task->tk_pid, task->tk_status);
1283
1284         /* Call the NFS version-specific code */
1285         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1286                 return;
1287 }
1288
1289 static void nfs_commit_release(void *calldata)
1290 {
1291         struct nfs_write_data   *data = calldata;
1292         struct nfs_page         *req;
1293         int status = data->task.tk_status;
1294
1295         while (!list_empty(&data->pages)) {
1296                 req = nfs_list_entry(data->pages.next);
1297                 nfs_list_remove_request(req);
1298                 nfs_clear_request_commit(req);
1299
1300                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
1301                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1302                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1303                         req->wb_bytes,
1304                         (long long)req_offset(req));
1305                 if (status < 0) {
1306                         nfs_context_set_write_error(req->wb_context, status);
1307                         nfs_inode_remove_request(req);
1308                         dprintk(", error = %d\n", status);
1309                         goto next;
1310                 }
1311
1312                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1313                  * returned by the server against all stored verfs. */
1314                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1315                         /* We have a match */
1316                         nfs_inode_remove_request(req);
1317                         dprintk(" OK\n");
1318                         goto next;
1319                 }
1320                 /* We have a mismatch. Write the page again */
1321                 dprintk(" mismatch\n");
1322                 nfs_mark_request_dirty(req);
1323         next:
1324                 nfs_clear_page_tag_locked(req);
1325         }
1326         nfs_commitdata_release(calldata);
1327 }
1328
1329 static const struct rpc_call_ops nfs_commit_ops = {
1330         .rpc_call_done = nfs_commit_done,
1331         .rpc_release = nfs_commit_release,
1332 };
1333
1334 int nfs_commit_inode(struct inode *inode, int how)
1335 {
1336         LIST_HEAD(head);
1337         int res;
1338
1339         spin_lock(&inode->i_lock);
1340         res = nfs_scan_commit(inode, &head, 0, 0);
1341         spin_unlock(&inode->i_lock);
1342         if (res) {
1343                 int error = nfs_commit_list(inode, &head, how);
1344                 if (error < 0)
1345                         return error;
1346         }
1347         return res;
1348 }
1349 #else
1350 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1351 {
1352         return 0;
1353 }
1354 #endif
1355
1356 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1357 {
1358         struct inode *inode = mapping->host;
1359         pgoff_t idx_start, idx_end;
1360         unsigned int npages = 0;
1361         LIST_HEAD(head);
1362         int nocommit = how & FLUSH_NOCOMMIT;
1363         long pages, ret;
1364
1365         /* FIXME */
1366         if (wbc->range_cyclic)
1367                 idx_start = 0;
1368         else {
1369                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1370                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1371                 if (idx_end > idx_start) {
1372                         pgoff_t l_npages = 1 + idx_end - idx_start;
1373                         npages = l_npages;
1374                         if (sizeof(npages) != sizeof(l_npages) &&
1375                                         (pgoff_t)npages != l_npages)
1376                                 npages = 0;
1377                 }
1378         }
1379         how &= ~FLUSH_NOCOMMIT;
1380         spin_lock(&inode->i_lock);
1381         do {
1382                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1383                 if (ret != 0)
1384                         continue;
1385                 if (nocommit)
1386                         break;
1387                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1388                 if (pages == 0)
1389                         break;
1390                 if (how & FLUSH_INVALIDATE) {
1391                         spin_unlock(&inode->i_lock);
1392                         nfs_cancel_commit_list(&head);
1393                         ret = pages;
1394                         spin_lock(&inode->i_lock);
1395                         continue;
1396                 }
1397                 pages += nfs_scan_commit(inode, &head, 0, 0);
1398                 spin_unlock(&inode->i_lock);
1399                 ret = nfs_commit_list(inode, &head, how);
1400                 spin_lock(&inode->i_lock);
1401
1402         } while (ret >= 0);
1403         spin_unlock(&inode->i_lock);
1404         return ret;
1405 }
1406
1407 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1408 {
1409         int ret;
1410
1411         ret = nfs_writepages(mapping, wbc);
1412         if (ret < 0)
1413                 goto out;
1414         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1415         if (ret < 0)
1416                 goto out;
1417         return 0;
1418 out:
1419         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1420         return ret;
1421 }
1422
1423 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1424 static int nfs_write_mapping(struct address_space *mapping, int how)
1425 {
1426         struct writeback_control wbc = {
1427                 .bdi = mapping->backing_dev_info,
1428                 .sync_mode = WB_SYNC_NONE,
1429                 .nr_to_write = LONG_MAX,
1430                 .for_writepages = 1,
1431                 .range_cyclic = 1,
1432         };
1433         int ret;
1434
1435         ret = __nfs_write_mapping(mapping, &wbc, how);
1436         if (ret < 0)
1437                 return ret;
1438         wbc.sync_mode = WB_SYNC_ALL;
1439         return __nfs_write_mapping(mapping, &wbc, how);
1440 }
1441
1442 /*
1443  * flush the inode to disk.
1444  */
1445 int nfs_wb_all(struct inode *inode)
1446 {
1447         return nfs_write_mapping(inode->i_mapping, 0);
1448 }
1449
1450 int nfs_wb_nocommit(struct inode *inode)
1451 {
1452         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1453 }
1454
1455 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1456 {
1457         struct nfs_page *req;
1458         loff_t range_start = page_offset(page);
1459         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1460         struct writeback_control wbc = {
1461                 .bdi = page->mapping->backing_dev_info,
1462                 .sync_mode = WB_SYNC_ALL,
1463                 .nr_to_write = LONG_MAX,
1464                 .range_start = range_start,
1465                 .range_end = range_end,
1466         };
1467         int ret = 0;
1468
1469         BUG_ON(!PageLocked(page));
1470         for (;;) {
1471                 req = nfs_page_find_request(page);
1472                 if (req == NULL)
1473                         goto out;
1474                 if (test_bit(PG_CLEAN, &req->wb_flags)) {
1475                         nfs_release_request(req);
1476                         break;
1477                 }
1478                 if (nfs_lock_request_dontget(req)) {
1479                         nfs_inode_remove_request(req);
1480                         /*
1481                          * In case nfs_inode_remove_request has marked the
1482                          * page as being dirty
1483                          */
1484                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1485                         nfs_unlock_request(req);
1486                         break;
1487                 }
1488                 ret = nfs_wait_on_request(req);
1489                 if (ret < 0)
1490                         goto out;
1491         }
1492         if (!PagePrivate(page))
1493                 return 0;
1494         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1495 out:
1496         return ret;
1497 }
1498
1499 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1500                                 int how)
1501 {
1502         loff_t range_start = page_offset(page);
1503         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1504         struct writeback_control wbc = {
1505                 .bdi = page->mapping->backing_dev_info,
1506                 .sync_mode = WB_SYNC_ALL,
1507                 .nr_to_write = LONG_MAX,
1508                 .range_start = range_start,
1509                 .range_end = range_end,
1510         };
1511         int ret;
1512
1513         do {
1514                 if (clear_page_dirty_for_io(page)) {
1515                         ret = nfs_writepage_locked(page, &wbc);
1516                         if (ret < 0)
1517                                 goto out_error;
1518                 } else if (!PagePrivate(page))
1519                         break;
1520                 ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1521                 if (ret < 0)
1522                         goto out_error;
1523         } while (PagePrivate(page));
1524         return 0;
1525 out_error:
1526         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1527         return ret;
1528 }
1529
1530 /*
1531  * Write back all requests on one page - we do this before reading it.
1532  */
1533 int nfs_wb_page(struct inode *inode, struct page* page)
1534 {
1535         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1536 }
1537
1538 int __init nfs_init_writepagecache(void)
1539 {
1540         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1541                                              sizeof(struct nfs_write_data),
1542                                              0, SLAB_HWCACHE_ALIGN,
1543                                              NULL);
1544         if (nfs_wdata_cachep == NULL)
1545                 return -ENOMEM;
1546
1547         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1548                                                      nfs_wdata_cachep);
1549         if (nfs_wdata_mempool == NULL)
1550                 return -ENOMEM;
1551
1552         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1553                                                       nfs_wdata_cachep);
1554         if (nfs_commit_mempool == NULL)
1555                 return -ENOMEM;
1556
1557         /*
1558          * NFS congestion size, scale with available memory.
1559          *
1560          *  64MB:    8192k
1561          * 128MB:   11585k
1562          * 256MB:   16384k
1563          * 512MB:   23170k
1564          *   1GB:   32768k
1565          *   2GB:   46340k
1566          *   4GB:   65536k
1567          *   8GB:   92681k
1568          *  16GB:  131072k
1569          *
1570          * This allows larger machines to have larger/more transfers.
1571          * Limit the default to 256M
1572          */
1573         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1574         if (nfs_congestion_kb > 256*1024)
1575                 nfs_congestion_kb = 256*1024;
1576
1577         return 0;
1578 }
1579
1580 void nfs_destroy_writepagecache(void)
1581 {
1582         mempool_destroy(nfs_commit_mempool);
1583         mempool_destroy(nfs_wdata_mempool);
1584         kmem_cache_destroy(nfs_wdata_cachep);
1585 }
1586