95d00f9132d093dc129b987c3aae2973f74560df
[linux-2.6.git] / fs / nfs / write.c
1 /*
2  * linux/fs/nfs/write.c
3  *
4  * Writing file data over NFS.
5  *
6  * We do it like this: When a (user) process wishes to write data to an
7  * NFS file, a write request is allocated that contains the RPC task data
8  * plus some info on the page to be written, and added to the inode's
9  * write chain. If the process writes past the end of the page, an async
10  * RPC call to write the page is scheduled immediately; otherwise, the call
11  * is delayed for a few seconds.
12  *
13  * Just like readahead, no async I/O is performed if wsize < PAGE_SIZE.
14  *
15  * Write requests are kept on the inode's writeback list. Each entry in
16  * that list references the page (portion) to be written. When the
17  * cache timeout has expired, the RPC task is woken up, and tries to
18  * lock the page. As soon as it manages to do so, the request is moved
19  * from the writeback list to the writelock list.
20  *
21  * Note: we must make sure never to confuse the inode passed in the
22  * write_page request with the one in page->inode. As far as I understand
23  * it, these are different when doing a swap-out.
24  *
25  * To understand everything that goes on here and in the NFS read code,
26  * one should be aware that a page is locked in exactly one of the following
27  * cases:
28  *
29  *  -   A write request is in progress.
30  *  -   A user process is in generic_file_write/nfs_update_page
31  *  -   A user process is in generic_file_read
32  *
33  * Also note that because of the way pages are invalidated in
34  * nfs_revalidate_inode, the following assertions hold:
35  *
36  *  -   If a page is dirty, there will be no read requests (a page will
37  *      not be re-read unless invalidated by nfs_revalidate_inode).
38  *  -   If the page is not uptodate, there will be no pending write
39  *      requests, and no process will be in nfs_update_page.
40  *
41  * FIXME: Interaction with the vmscan routines is not optimal yet.
42  * Either vmscan must be made nfs-savvy, or we need a different page
43  * reclaim concept that supports something like FS-independent
44  * buffer_heads with a b_ops-> field.
45  *
46  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
47  */
48
49 #include <linux/config.h>
50 #include <linux/types.h>
51 #include <linux/slab.h>
52 #include <linux/mm.h>
53 #include <linux/pagemap.h>
54 #include <linux/file.h>
55 #include <linux/mpage.h>
56 #include <linux/writeback.h>
57
58 #include <linux/sunrpc/clnt.h>
59 #include <linux/nfs_fs.h>
60 #include <linux/nfs_mount.h>
61 #include <linux/nfs_page.h>
62 #include <asm/uaccess.h>
63 #include <linux/smp_lock.h>
64
65 #include "delegation.h"
66
67 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
68
69 #define MIN_POOL_WRITE          (32)
70 #define MIN_POOL_COMMIT         (4)
71
72 /*
73  * Local function declarations
74  */
75 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
76                                             struct inode *,
77                                             struct page *,
78                                             unsigned int, unsigned int);
79 static void nfs_writeback_done_partial(struct nfs_write_data *, int);
80 static void nfs_writeback_done_full(struct nfs_write_data *, int);
81 static int nfs_wait_on_write_congestion(struct address_space *, int);
82 static int nfs_wait_on_requests(struct inode *, unsigned long, unsigned int);
83 static int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
84                            unsigned int npages, int how);
85
86 static kmem_cache_t *nfs_wdata_cachep;
87 mempool_t *nfs_wdata_mempool;
88 static mempool_t *nfs_commit_mempool;
89
90 static DECLARE_WAIT_QUEUE_HEAD(nfs_write_congestion);
91
92 static inline struct nfs_write_data *nfs_commit_alloc(void)
93 {
94         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, SLAB_NOFS);
95         if (p) {
96                 memset(p, 0, sizeof(*p));
97                 INIT_LIST_HEAD(&p->pages);
98         }
99         return p;
100 }
101
102 static inline void nfs_commit_free(struct nfs_write_data *p)
103 {
104         mempool_free(p, nfs_commit_mempool);
105 }
106
107 static void nfs_writedata_release(struct rpc_task *task)
108 {
109         struct nfs_write_data   *wdata = (struct nfs_write_data *)task->tk_calldata;
110         nfs_writedata_free(wdata);
111 }
112
113 /* Adjust the file length if we're writing beyond the end */
114 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
115 {
116         struct inode *inode = page->mapping->host;
117         loff_t end, i_size = i_size_read(inode);
118         unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
119
120         if (i_size > 0 && page->index < end_index)
121                 return;
122         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
123         if (i_size >= end)
124                 return;
125         i_size_write(inode, end);
126 }
127
128 /* We can set the PG_uptodate flag if we see that a write request
129  * covers the full page.
130  */
131 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
132 {
133         loff_t end_offs;
134
135         if (PageUptodate(page))
136                 return;
137         if (base != 0)
138                 return;
139         if (count == PAGE_CACHE_SIZE) {
140                 SetPageUptodate(page);
141                 return;
142         }
143
144         end_offs = i_size_read(page->mapping->host) - 1;
145         if (end_offs < 0)
146                 return;
147         /* Is this the last page? */
148         if (page->index != (unsigned long)(end_offs >> PAGE_CACHE_SHIFT))
149                 return;
150         /* This is the last page: set PG_uptodate if we cover the entire
151          * extent of the data, then zero the rest of the page.
152          */
153         if (count == (unsigned int)(end_offs & (PAGE_CACHE_SIZE - 1)) + 1) {
154                 memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
155                 SetPageUptodate(page);
156         }
157 }
158
159 /*
160  * Write a page synchronously.
161  * Offset is the data offset within the page.
162  */
163 static int nfs_writepage_sync(struct nfs_open_context *ctx, struct inode *inode,
164                 struct page *page, unsigned int offset, unsigned int count,
165                 int how)
166 {
167         unsigned int    wsize = NFS_SERVER(inode)->wsize;
168         int             result, written = 0;
169         struct nfs_write_data *wdata;
170
171         wdata = nfs_writedata_alloc();
172         if (!wdata)
173                 return -ENOMEM;
174
175         wdata->flags = how;
176         wdata->cred = ctx->cred;
177         wdata->inode = inode;
178         wdata->args.fh = NFS_FH(inode);
179         wdata->args.context = ctx;
180         wdata->args.pages = &page;
181         wdata->args.stable = NFS_FILE_SYNC;
182         wdata->args.pgbase = offset;
183         wdata->args.count = wsize;
184         wdata->res.fattr = &wdata->fattr;
185         wdata->res.verf = &wdata->verf;
186
187         dprintk("NFS:      nfs_writepage_sync(%s/%Ld %d@%Ld)\n",
188                 inode->i_sb->s_id,
189                 (long long)NFS_FILEID(inode),
190                 count, (long long)(page_offset(page) + offset));
191
192         set_page_writeback(page);
193         nfs_begin_data_update(inode);
194         do {
195                 if (count < wsize)
196                         wdata->args.count = count;
197                 wdata->args.offset = page_offset(page) + wdata->args.pgbase;
198
199                 result = NFS_PROTO(inode)->write(wdata);
200
201                 if (result < 0) {
202                         /* Must mark the page invalid after I/O error */
203                         ClearPageUptodate(page);
204                         goto io_error;
205                 }
206                 if (result < wdata->args.count)
207                         printk(KERN_WARNING "NFS: short write, count=%u, result=%d\n",
208                                         wdata->args.count, result);
209
210                 wdata->args.offset += result;
211                 wdata->args.pgbase += result;
212                 written += result;
213                 count -= result;
214         } while (count);
215         /* Update file length */
216         nfs_grow_file(page, offset, written);
217         /* Set the PG_uptodate flag? */
218         nfs_mark_uptodate(page, offset, written);
219
220         if (PageError(page))
221                 ClearPageError(page);
222
223 io_error:
224         nfs_end_data_update(inode);
225         end_page_writeback(page);
226         nfs_writedata_free(wdata);
227         return written ? written : result;
228 }
229
230 static int nfs_writepage_async(struct nfs_open_context *ctx,
231                 struct inode *inode, struct page *page,
232                 unsigned int offset, unsigned int count)
233 {
234         struct nfs_page *req;
235
236         req = nfs_update_request(ctx, inode, page, offset, count);
237         if (IS_ERR(req))
238                 return PTR_ERR(req);
239         /* Update file length */
240         nfs_grow_file(page, offset, count);
241         /* Set the PG_uptodate flag? */
242         nfs_mark_uptodate(page, offset, count);
243         nfs_unlock_request(req);
244         return 0;
245 }
246
247 static int wb_priority(struct writeback_control *wbc)
248 {
249         if (wbc->for_reclaim)
250                 return FLUSH_HIGHPRI;
251         if (wbc->for_kupdate)
252                 return FLUSH_LOWPRI;
253         return 0;
254 }
255
256 /*
257  * Write an mmapped page to the server.
258  */
259 int nfs_writepage(struct page *page, struct writeback_control *wbc)
260 {
261         struct nfs_open_context *ctx;
262         struct inode *inode = page->mapping->host;
263         unsigned long end_index;
264         unsigned offset = PAGE_CACHE_SIZE;
265         loff_t i_size = i_size_read(inode);
266         int inode_referenced = 0;
267         int priority = wb_priority(wbc);
268         int err;
269
270         /*
271          * Note: We need to ensure that we have a reference to the inode
272          *       if we are to do asynchronous writes. If not, waiting
273          *       in nfs_wait_on_request() may deadlock with clear_inode().
274          *
275          *       If igrab() fails here, then it is in any case safe to
276          *       call nfs_wb_page(), since there will be no pending writes.
277          */
278         if (igrab(inode) != 0)
279                 inode_referenced = 1;
280         end_index = i_size >> PAGE_CACHE_SHIFT;
281
282         /* Ensure we've flushed out any previous writes */
283         nfs_wb_page_priority(inode, page, priority);
284
285         /* easy case */
286         if (page->index < end_index)
287                 goto do_it;
288         /* things got complicated... */
289         offset = i_size & (PAGE_CACHE_SIZE-1);
290
291         /* OK, are we completely out? */
292         err = 0; /* potential race with truncate - ignore */
293         if (page->index >= end_index+1 || !offset)
294                 goto out;
295 do_it:
296         ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
297         if (ctx == NULL) {
298                 err = -EBADF;
299                 goto out;
300         }
301         lock_kernel();
302         if (!IS_SYNC(inode) && inode_referenced) {
303                 err = nfs_writepage_async(ctx, inode, page, 0, offset);
304                 if (!wbc->for_writepages)
305                         nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
306         } else {
307                 err = nfs_writepage_sync(ctx, inode, page, 0,
308                                                 offset, priority);
309                 if (err >= 0) {
310                         if (err != offset)
311                                 redirty_page_for_writepage(wbc, page);
312                         err = 0;
313                 }
314         }
315         unlock_kernel();
316         put_nfs_open_context(ctx);
317 out:
318         unlock_page(page);
319         if (inode_referenced)
320                 iput(inode);
321         return err; 
322 }
323
324 /*
325  * Note: causes nfs_update_request() to block on the assumption
326  *       that the writeback is generated due to memory pressure.
327  */
328 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
329 {
330         struct backing_dev_info *bdi = mapping->backing_dev_info;
331         struct inode *inode = mapping->host;
332         int err;
333
334         err = generic_writepages(mapping, wbc);
335         if (err)
336                 return err;
337         while (test_and_set_bit(BDI_write_congested, &bdi->state) != 0) {
338                 if (wbc->nonblocking)
339                         return 0;
340                 nfs_wait_on_write_congestion(mapping, 0);
341         }
342         err = nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
343         if (err < 0)
344                 goto out;
345         wbc->nr_to_write -= err;
346         if (!wbc->nonblocking && wbc->sync_mode == WB_SYNC_ALL) {
347                 err = nfs_wait_on_requests(inode, 0, 0);
348                 if (err < 0)
349                         goto out;
350         }
351         err = nfs_commit_inode(inode, wb_priority(wbc));
352         if (err > 0) {
353                 wbc->nr_to_write -= err;
354                 err = 0;
355         }
356 out:
357         clear_bit(BDI_write_congested, &bdi->state);
358         wake_up_all(&nfs_write_congestion);
359         return err;
360 }
361
362 /*
363  * Insert a write request into an inode
364  */
365 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
366 {
367         struct nfs_inode *nfsi = NFS_I(inode);
368         int error;
369
370         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
371         BUG_ON(error == -EEXIST);
372         if (error)
373                 return error;
374         if (!nfsi->npages) {
375                 igrab(inode);
376                 nfs_begin_data_update(inode);
377                 if (nfs_have_delegation(inode, FMODE_WRITE))
378                         nfsi->change_attr++;
379         }
380         nfsi->npages++;
381         atomic_inc(&req->wb_count);
382         return 0;
383 }
384
385 /*
386  * Insert a write request into an inode
387  */
388 static void nfs_inode_remove_request(struct nfs_page *req)
389 {
390         struct inode *inode = req->wb_context->dentry->d_inode;
391         struct nfs_inode *nfsi = NFS_I(inode);
392
393         BUG_ON (!NFS_WBACK_BUSY(req));
394
395         spin_lock(&nfsi->req_lock);
396         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
397         nfsi->npages--;
398         if (!nfsi->npages) {
399                 spin_unlock(&nfsi->req_lock);
400                 nfs_end_data_update(inode);
401                 iput(inode);
402         } else
403                 spin_unlock(&nfsi->req_lock);
404         nfs_clear_request(req);
405         nfs_release_request(req);
406 }
407
408 /*
409  * Find a request
410  */
411 static inline struct nfs_page *
412 _nfs_find_request(struct inode *inode, unsigned long index)
413 {
414         struct nfs_inode *nfsi = NFS_I(inode);
415         struct nfs_page *req;
416
417         req = (struct nfs_page*)radix_tree_lookup(&nfsi->nfs_page_tree, index);
418         if (req)
419                 atomic_inc(&req->wb_count);
420         return req;
421 }
422
423 static struct nfs_page *
424 nfs_find_request(struct inode *inode, unsigned long index)
425 {
426         struct nfs_page         *req;
427         struct nfs_inode        *nfsi = NFS_I(inode);
428
429         spin_lock(&nfsi->req_lock);
430         req = _nfs_find_request(inode, index);
431         spin_unlock(&nfsi->req_lock);
432         return req;
433 }
434
435 /*
436  * Add a request to the inode's dirty list.
437  */
438 static void
439 nfs_mark_request_dirty(struct nfs_page *req)
440 {
441         struct inode *inode = req->wb_context->dentry->d_inode;
442         struct nfs_inode *nfsi = NFS_I(inode);
443
444         spin_lock(&nfsi->req_lock);
445         radix_tree_tag_set(&nfsi->nfs_page_tree,
446                         req->wb_index, NFS_PAGE_TAG_DIRTY);
447         nfs_list_add_request(req, &nfsi->dirty);
448         nfsi->ndirty++;
449         spin_unlock(&nfsi->req_lock);
450         inc_page_state(nr_dirty);
451         mark_inode_dirty(inode);
452 }
453
454 /*
455  * Check if a request is dirty
456  */
457 static inline int
458 nfs_dirty_request(struct nfs_page *req)
459 {
460         struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
461         return !list_empty(&req->wb_list) && req->wb_list_head == &nfsi->dirty;
462 }
463
464 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
465 /*
466  * Add a request to the inode's commit list.
467  */
468 static void
469 nfs_mark_request_commit(struct nfs_page *req)
470 {
471         struct inode *inode = req->wb_context->dentry->d_inode;
472         struct nfs_inode *nfsi = NFS_I(inode);
473
474         spin_lock(&nfsi->req_lock);
475         nfs_list_add_request(req, &nfsi->commit);
476         nfsi->ncommit++;
477         spin_unlock(&nfsi->req_lock);
478         inc_page_state(nr_unstable);
479         mark_inode_dirty(inode);
480 }
481 #endif
482
483 /*
484  * Wait for a request to complete.
485  *
486  * Interruptible by signals only if mounted with intr flag.
487  */
488 static int
489 nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int npages)
490 {
491         struct nfs_inode *nfsi = NFS_I(inode);
492         struct nfs_page *req;
493         unsigned long           idx_end, next;
494         unsigned int            res = 0;
495         int                     error;
496
497         if (npages == 0)
498                 idx_end = ~0;
499         else
500                 idx_end = idx_start + npages - 1;
501
502         spin_lock(&nfsi->req_lock);
503         next = idx_start;
504         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
505                 if (req->wb_index > idx_end)
506                         break;
507
508                 next = req->wb_index + 1;
509                 BUG_ON(!NFS_WBACK_BUSY(req));
510
511                 atomic_inc(&req->wb_count);
512                 spin_unlock(&nfsi->req_lock);
513                 error = nfs_wait_on_request(req);
514                 nfs_release_request(req);
515                 if (error < 0)
516                         return error;
517                 spin_lock(&nfsi->req_lock);
518                 res++;
519         }
520         spin_unlock(&nfsi->req_lock);
521         return res;
522 }
523
524 /*
525  * nfs_scan_dirty - Scan an inode for dirty requests
526  * @inode: NFS inode to scan
527  * @dst: destination list
528  * @idx_start: lower bound of page->index to scan.
529  * @npages: idx_start + npages sets the upper bound to scan.
530  *
531  * Moves requests from the inode's dirty page list.
532  * The requests are *not* checked to ensure that they form a contiguous set.
533  */
534 static int
535 nfs_scan_dirty(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
536 {
537         struct nfs_inode *nfsi = NFS_I(inode);
538         int res = 0;
539
540         if (nfsi->ndirty != 0) {
541                 res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
542                 nfsi->ndirty -= res;
543                 sub_page_state(nr_dirty,res);
544                 if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
545                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
546         }
547         return res;
548 }
549
550 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
551 /*
552  * nfs_scan_commit - Scan an inode for commit requests
553  * @inode: NFS inode to scan
554  * @dst: destination list
555  * @idx_start: lower bound of page->index to scan.
556  * @npages: idx_start + npages sets the upper bound to scan.
557  *
558  * Moves requests from the inode's 'commit' request list.
559  * The requests are *not* checked to ensure that they form a contiguous set.
560  */
561 static int
562 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
563 {
564         struct nfs_inode *nfsi = NFS_I(inode);
565         int res = 0;
566
567         if (nfsi->ncommit != 0) {
568                 res = nfs_scan_list(&nfsi->commit, dst, idx_start, npages);
569                 nfsi->ncommit -= res;
570                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
571                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
572         }
573         return res;
574 }
575 #endif
576
577 static int nfs_wait_on_write_congestion(struct address_space *mapping, int intr)
578 {
579         struct backing_dev_info *bdi = mapping->backing_dev_info;
580         DEFINE_WAIT(wait);
581         int ret = 0;
582
583         might_sleep();
584
585         if (!bdi_write_congested(bdi))
586                 return 0;
587         if (intr) {
588                 struct rpc_clnt *clnt = NFS_CLIENT(mapping->host);
589                 sigset_t oldset;
590
591                 rpc_clnt_sigmask(clnt, &oldset);
592                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_INTERRUPTIBLE);
593                 if (bdi_write_congested(bdi)) {
594                         if (signalled())
595                                 ret = -ERESTARTSYS;
596                         else
597                                 schedule();
598                 }
599                 rpc_clnt_sigunmask(clnt, &oldset);
600         } else {
601                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_UNINTERRUPTIBLE);
602                 if (bdi_write_congested(bdi))
603                         schedule();
604         }
605         finish_wait(&nfs_write_congestion, &wait);
606         return ret;
607 }
608
609
610 /*
611  * Try to update any existing write request, or create one if there is none.
612  * In order to match, the request's credentials must match those of
613  * the calling process.
614  *
615  * Note: Should always be called with the Page Lock held!
616  */
617 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
618                 struct inode *inode, struct page *page,
619                 unsigned int offset, unsigned int bytes)
620 {
621         struct nfs_server *server = NFS_SERVER(inode);
622         struct nfs_inode *nfsi = NFS_I(inode);
623         struct nfs_page         *req, *new = NULL;
624         unsigned long           rqend, end;
625
626         end = offset + bytes;
627
628         if (nfs_wait_on_write_congestion(page->mapping, server->flags & NFS_MOUNT_INTR))
629                 return ERR_PTR(-ERESTARTSYS);
630         for (;;) {
631                 /* Loop over all inode entries and see if we find
632                  * A request for the page we wish to update
633                  */
634                 spin_lock(&nfsi->req_lock);
635                 req = _nfs_find_request(inode, page->index);
636                 if (req) {
637                         if (!nfs_lock_request_dontget(req)) {
638                                 int error;
639                                 spin_unlock(&nfsi->req_lock);
640                                 error = nfs_wait_on_request(req);
641                                 nfs_release_request(req);
642                                 if (error < 0)
643                                         return ERR_PTR(error);
644                                 continue;
645                         }
646                         spin_unlock(&nfsi->req_lock);
647                         if (new)
648                                 nfs_release_request(new);
649                         break;
650                 }
651
652                 if (new) {
653                         int error;
654                         nfs_lock_request_dontget(new);
655                         error = nfs_inode_add_request(inode, new);
656                         if (error) {
657                                 spin_unlock(&nfsi->req_lock);
658                                 nfs_unlock_request(new);
659                                 return ERR_PTR(error);
660                         }
661                         spin_unlock(&nfsi->req_lock);
662                         nfs_mark_request_dirty(new);
663                         return new;
664                 }
665                 spin_unlock(&nfsi->req_lock);
666
667                 new = nfs_create_request(ctx, inode, page, offset, bytes);
668                 if (IS_ERR(new))
669                         return new;
670         }
671
672         /* We have a request for our page.
673          * If the creds don't match, or the
674          * page addresses don't match,
675          * tell the caller to wait on the conflicting
676          * request.
677          */
678         rqend = req->wb_offset + req->wb_bytes;
679         if (req->wb_context != ctx
680             || req->wb_page != page
681             || !nfs_dirty_request(req)
682             || offset > rqend || end < req->wb_offset) {
683                 nfs_unlock_request(req);
684                 return ERR_PTR(-EBUSY);
685         }
686
687         /* Okay, the request matches. Update the region */
688         if (offset < req->wb_offset) {
689                 req->wb_offset = offset;
690                 req->wb_pgbase = offset;
691                 req->wb_bytes = rqend - req->wb_offset;
692         }
693
694         if (end > rqend)
695                 req->wb_bytes = end - req->wb_offset;
696
697         return req;
698 }
699
700 int nfs_flush_incompatible(struct file *file, struct page *page)
701 {
702         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
703         struct inode    *inode = page->mapping->host;
704         struct nfs_page *req;
705         int             status = 0;
706         /*
707          * Look for a request corresponding to this page. If there
708          * is one, and it belongs to another file, we flush it out
709          * before we try to copy anything into the page. Do this
710          * due to the lack of an ACCESS-type call in NFSv2.
711          * Also do the same if we find a request from an existing
712          * dropped page.
713          */
714         req = nfs_find_request(inode, page->index);
715         if (req) {
716                 if (req->wb_page != page || ctx != req->wb_context)
717                         status = nfs_wb_page(inode, page);
718                 nfs_release_request(req);
719         }
720         return (status < 0) ? status : 0;
721 }
722
723 /*
724  * Update and possibly write a cached page of an NFS file.
725  *
726  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
727  * things with a page scheduled for an RPC call (e.g. invalidate it).
728  */
729 int nfs_updatepage(struct file *file, struct page *page,
730                 unsigned int offset, unsigned int count)
731 {
732         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
733         struct inode    *inode = page->mapping->host;
734         struct nfs_page *req;
735         int             status = 0;
736
737         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
738                 file->f_dentry->d_parent->d_name.name,
739                 file->f_dentry->d_name.name, count,
740                 (long long)(page_offset(page) +offset));
741
742         if (IS_SYNC(inode)) {
743                 status = nfs_writepage_sync(ctx, inode, page, offset, count, 0);
744                 if (status > 0) {
745                         if (offset == 0 && status == PAGE_CACHE_SIZE)
746                                 SetPageUptodate(page);
747                         return 0;
748                 }
749                 return status;
750         }
751
752         /* If we're not using byte range locks, and we know the page
753          * is entirely in cache, it may be more efficient to avoid
754          * fragmenting write requests.
755          */
756         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
757                 loff_t end_offs = i_size_read(inode) - 1;
758                 unsigned long end_index = end_offs >> PAGE_CACHE_SHIFT;
759
760                 count += offset;
761                 offset = 0;
762                 if (unlikely(end_offs < 0)) {
763                         /* Do nothing */
764                 } else if (page->index == end_index) {
765                         unsigned int pglen;
766                         pglen = (unsigned int)(end_offs & (PAGE_CACHE_SIZE-1)) + 1;
767                         if (count < pglen)
768                                 count = pglen;
769                 } else if (page->index < end_index)
770                         count = PAGE_CACHE_SIZE;
771         }
772
773         /*
774          * Try to find an NFS request corresponding to this page
775          * and update it.
776          * If the existing request cannot be updated, we must flush
777          * it out now.
778          */
779         do {
780                 req = nfs_update_request(ctx, inode, page, offset, count);
781                 status = (IS_ERR(req)) ? PTR_ERR(req) : 0;
782                 if (status != -EBUSY)
783                         break;
784                 /* Request could not be updated. Flush it out and try again */
785                 status = nfs_wb_page(inode, page);
786         } while (status >= 0);
787         if (status < 0)
788                 goto done;
789
790         status = 0;
791
792         /* Update file length */
793         nfs_grow_file(page, offset, count);
794         /* Set the PG_uptodate flag? */
795         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
796         nfs_unlock_request(req);
797 done:
798         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
799                         status, (long long)i_size_read(inode));
800         if (status < 0)
801                 ClearPageUptodate(page);
802         return status;
803 }
804
805 static void nfs_writepage_release(struct nfs_page *req)
806 {
807         end_page_writeback(req->wb_page);
808
809 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
810         if (!PageError(req->wb_page)) {
811                 if (NFS_NEED_RESCHED(req)) {
812                         nfs_mark_request_dirty(req);
813                         goto out;
814                 } else if (NFS_NEED_COMMIT(req)) {
815                         nfs_mark_request_commit(req);
816                         goto out;
817                 }
818         }
819         nfs_inode_remove_request(req);
820
821 out:
822         nfs_clear_commit(req);
823         nfs_clear_reschedule(req);
824 #else
825         nfs_inode_remove_request(req);
826 #endif
827         nfs_clear_page_writeback(req);
828 }
829
830 static inline int flush_task_priority(int how)
831 {
832         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
833                 case FLUSH_HIGHPRI:
834                         return RPC_PRIORITY_HIGH;
835                 case FLUSH_LOWPRI:
836                         return RPC_PRIORITY_LOW;
837         }
838         return RPC_PRIORITY_NORMAL;
839 }
840
841 /*
842  * Set up the argument/result storage required for the RPC call.
843  */
844 static void nfs_write_rpcsetup(struct nfs_page *req,
845                 struct nfs_write_data *data,
846                 unsigned int count, unsigned int offset,
847                 int how)
848 {
849         struct inode            *inode;
850
851         /* Set up the RPC argument and reply structs
852          * NB: take care not to mess about with data->commit et al. */
853
854         data->req = req;
855         data->inode = inode = req->wb_context->dentry->d_inode;
856         data->cred = req->wb_context->cred;
857
858         data->args.fh     = NFS_FH(inode);
859         data->args.offset = req_offset(req) + offset;
860         data->args.pgbase = req->wb_pgbase + offset;
861         data->args.pages  = data->pagevec;
862         data->args.count  = count;
863         data->args.context = req->wb_context;
864
865         data->res.fattr   = &data->fattr;
866         data->res.count   = count;
867         data->res.verf    = &data->verf;
868         nfs_fattr_init(&data->fattr);
869
870         NFS_PROTO(inode)->write_setup(data, how);
871
872         data->task.tk_priority = flush_task_priority(how);
873         data->task.tk_cookie = (unsigned long)inode;
874         data->task.tk_calldata = data;
875         /* Release requests */
876         data->task.tk_release = nfs_writedata_release;
877
878         dprintk("NFS: %4d initiated write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
879                 data->task.tk_pid,
880                 inode->i_sb->s_id,
881                 (long long)NFS_FILEID(inode),
882                 count,
883                 (unsigned long long)data->args.offset);
884 }
885
886 static void nfs_execute_write(struct nfs_write_data *data)
887 {
888         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
889         sigset_t oldset;
890
891         rpc_clnt_sigmask(clnt, &oldset);
892         lock_kernel();
893         rpc_execute(&data->task);
894         unlock_kernel();
895         rpc_clnt_sigunmask(clnt, &oldset);
896 }
897
898 /*
899  * Generate multiple small requests to write out a single
900  * contiguous dirty area on one page.
901  */
902 static int nfs_flush_multi(struct list_head *head, struct inode *inode, int how)
903 {
904         struct nfs_page *req = nfs_list_entry(head->next);
905         struct page *page = req->wb_page;
906         struct nfs_write_data *data;
907         unsigned int wsize = NFS_SERVER(inode)->wsize;
908         unsigned int nbytes, offset;
909         int requests = 0;
910         LIST_HEAD(list);
911
912         nfs_list_remove_request(req);
913
914         nbytes = req->wb_bytes;
915         for (;;) {
916                 data = nfs_writedata_alloc();
917                 if (!data)
918                         goto out_bad;
919                 list_add(&data->pages, &list);
920                 requests++;
921                 if (nbytes <= wsize)
922                         break;
923                 nbytes -= wsize;
924         }
925         atomic_set(&req->wb_complete, requests);
926
927         ClearPageError(page);
928         set_page_writeback(page);
929         offset = 0;
930         nbytes = req->wb_bytes;
931         do {
932                 data = list_entry(list.next, struct nfs_write_data, pages);
933                 list_del_init(&data->pages);
934
935                 data->pagevec[0] = page;
936                 data->complete = nfs_writeback_done_partial;
937
938                 if (nbytes > wsize) {
939                         nfs_write_rpcsetup(req, data, wsize, offset, how);
940                         offset += wsize;
941                         nbytes -= wsize;
942                 } else {
943                         nfs_write_rpcsetup(req, data, nbytes, offset, how);
944                         nbytes = 0;
945                 }
946                 nfs_execute_write(data);
947         } while (nbytes != 0);
948
949         return 0;
950
951 out_bad:
952         while (!list_empty(&list)) {
953                 data = list_entry(list.next, struct nfs_write_data, pages);
954                 list_del(&data->pages);
955                 nfs_writedata_free(data);
956         }
957         nfs_mark_request_dirty(req);
958         nfs_clear_page_writeback(req);
959         return -ENOMEM;
960 }
961
962 /*
963  * Create an RPC task for the given write request and kick it.
964  * The page must have been locked by the caller.
965  *
966  * It may happen that the page we're passed is not marked dirty.
967  * This is the case if nfs_updatepage detects a conflicting request
968  * that has been written but not committed.
969  */
970 static int nfs_flush_one(struct list_head *head, struct inode *inode, int how)
971 {
972         struct nfs_page         *req;
973         struct page             **pages;
974         struct nfs_write_data   *data;
975         unsigned int            count;
976
977         if (NFS_SERVER(inode)->wsize < PAGE_CACHE_SIZE)
978                 return nfs_flush_multi(head, inode, how);
979
980         data = nfs_writedata_alloc();
981         if (!data)
982                 goto out_bad;
983
984         pages = data->pagevec;
985         count = 0;
986         while (!list_empty(head)) {
987                 req = nfs_list_entry(head->next);
988                 nfs_list_remove_request(req);
989                 nfs_list_add_request(req, &data->pages);
990                 ClearPageError(req->wb_page);
991                 set_page_writeback(req->wb_page);
992                 *pages++ = req->wb_page;
993                 count += req->wb_bytes;
994         }
995         req = nfs_list_entry(data->pages.next);
996
997         data->complete = nfs_writeback_done_full;
998         /* Set up the argument struct */
999         nfs_write_rpcsetup(req, data, count, 0, how);
1000
1001         nfs_execute_write(data);
1002         return 0;
1003  out_bad:
1004         while (!list_empty(head)) {
1005                 struct nfs_page *req = nfs_list_entry(head->next);
1006                 nfs_list_remove_request(req);
1007                 nfs_mark_request_dirty(req);
1008                 nfs_clear_page_writeback(req);
1009         }
1010         return -ENOMEM;
1011 }
1012
1013 static int
1014 nfs_flush_list(struct list_head *head, int wpages, int how)
1015 {
1016         LIST_HEAD(one_request);
1017         struct nfs_page         *req;
1018         int                     error = 0;
1019         unsigned int            pages = 0;
1020
1021         while (!list_empty(head)) {
1022                 pages += nfs_coalesce_requests(head, &one_request, wpages);
1023                 req = nfs_list_entry(one_request.next);
1024                 error = nfs_flush_one(&one_request, req->wb_context->dentry->d_inode, how);
1025                 if (error < 0)
1026                         break;
1027         }
1028         if (error >= 0)
1029                 return pages;
1030
1031         while (!list_empty(head)) {
1032                 req = nfs_list_entry(head->next);
1033                 nfs_list_remove_request(req);
1034                 nfs_mark_request_dirty(req);
1035                 nfs_clear_page_writeback(req);
1036         }
1037         return error;
1038 }
1039
1040 /*
1041  * Handle a write reply that flushed part of a page.
1042  */
1043 static void nfs_writeback_done_partial(struct nfs_write_data *data, int status)
1044 {
1045         struct nfs_page         *req = data->req;
1046         struct page             *page = req->wb_page;
1047
1048         dprintk("NFS: write (%s/%Ld %d@%Ld)",
1049                 req->wb_context->dentry->d_inode->i_sb->s_id,
1050                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1051                 req->wb_bytes,
1052                 (long long)req_offset(req));
1053
1054         if (status < 0) {
1055                 ClearPageUptodate(page);
1056                 SetPageError(page);
1057                 req->wb_context->error = status;
1058                 dprintk(", error = %d\n", status);
1059         } else {
1060 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1061                 if (data->verf.committed < NFS_FILE_SYNC) {
1062                         if (!NFS_NEED_COMMIT(req)) {
1063                                 nfs_defer_commit(req);
1064                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1065                                 dprintk(" defer commit\n");
1066                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1067                                 nfs_defer_reschedule(req);
1068                                 dprintk(" server reboot detected\n");
1069                         }
1070                 } else
1071 #endif
1072                         dprintk(" OK\n");
1073         }
1074
1075         if (atomic_dec_and_test(&req->wb_complete))
1076                 nfs_writepage_release(req);
1077 }
1078
1079 /*
1080  * Handle a write reply that flushes a whole page.
1081  *
1082  * FIXME: There is an inherent race with invalidate_inode_pages and
1083  *        writebacks since the page->count is kept > 1 for as long
1084  *        as the page has a write request pending.
1085  */
1086 static void nfs_writeback_done_full(struct nfs_write_data *data, int status)
1087 {
1088         struct nfs_page         *req;
1089         struct page             *page;
1090
1091         /* Update attributes as result of writeback. */
1092         while (!list_empty(&data->pages)) {
1093                 req = nfs_list_entry(data->pages.next);
1094                 nfs_list_remove_request(req);
1095                 page = req->wb_page;
1096
1097                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1098                         req->wb_context->dentry->d_inode->i_sb->s_id,
1099                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1100                         req->wb_bytes,
1101                         (long long)req_offset(req));
1102
1103                 if (status < 0) {
1104                         ClearPageUptodate(page);
1105                         SetPageError(page);
1106                         req->wb_context->error = status;
1107                         end_page_writeback(page);
1108                         nfs_inode_remove_request(req);
1109                         dprintk(", error = %d\n", status);
1110                         goto next;
1111                 }
1112                 end_page_writeback(page);
1113
1114 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1115                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1116                         nfs_inode_remove_request(req);
1117                         dprintk(" OK\n");
1118                         goto next;
1119                 }
1120                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1121                 nfs_mark_request_commit(req);
1122                 dprintk(" marked for commit\n");
1123 #else
1124                 nfs_inode_remove_request(req);
1125 #endif
1126         next:
1127                 nfs_clear_page_writeback(req);
1128         }
1129 }
1130
1131 /*
1132  * This function is called when the WRITE call is complete.
1133  */
1134 void nfs_writeback_done(struct rpc_task *task)
1135 {
1136         struct nfs_write_data   *data = (struct nfs_write_data *) task->tk_calldata;
1137         struct nfs_writeargs    *argp = &data->args;
1138         struct nfs_writeres     *resp = &data->res;
1139
1140         dprintk("NFS: %4d nfs_writeback_done (status %d)\n",
1141                 task->tk_pid, task->tk_status);
1142
1143 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1144         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1145                 /* We tried a write call, but the server did not
1146                  * commit data to stable storage even though we
1147                  * requested it.
1148                  * Note: There is a known bug in Tru64 < 5.0 in which
1149                  *       the server reports NFS_DATA_SYNC, but performs
1150                  *       NFS_FILE_SYNC. We therefore implement this checking
1151                  *       as a dprintk() in order to avoid filling syslog.
1152                  */
1153                 static unsigned long    complain;
1154
1155                 if (time_before(complain, jiffies)) {
1156                         dprintk("NFS: faulty NFS server %s:"
1157                                 " (committed = %d) != (stable = %d)\n",
1158                                 NFS_SERVER(data->inode)->hostname,
1159                                 resp->verf->committed, argp->stable);
1160                         complain = jiffies + 300 * HZ;
1161                 }
1162         }
1163 #endif
1164         /* Is this a short write? */
1165         if (task->tk_status >= 0 && resp->count < argp->count) {
1166                 static unsigned long    complain;
1167
1168                 /* Has the server at least made some progress? */
1169                 if (resp->count != 0) {
1170                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1171                         if (resp->verf->committed != NFS_UNSTABLE) {
1172                                 /* Resend from where the server left off */
1173                                 argp->offset += resp->count;
1174                                 argp->pgbase += resp->count;
1175                                 argp->count -= resp->count;
1176                         } else {
1177                                 /* Resend as a stable write in order to avoid
1178                                  * headaches in the case of a server crash.
1179                                  */
1180                                 argp->stable = NFS_FILE_SYNC;
1181                         }
1182                         rpc_restart_call(task);
1183                         return;
1184                 }
1185                 if (time_before(complain, jiffies)) {
1186                         printk(KERN_WARNING
1187                                "NFS: Server wrote zero bytes, expected %u.\n",
1188                                         argp->count);
1189                         complain = jiffies + 300 * HZ;
1190                 }
1191                 /* Can't do anything about it except throw an error. */
1192                 task->tk_status = -EIO;
1193         }
1194
1195         /*
1196          * Process the nfs_page list
1197          */
1198         data->complete(data, task->tk_status);
1199 }
1200
1201
1202 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1203 static void nfs_commit_release(struct rpc_task *task)
1204 {
1205         struct nfs_write_data   *wdata = (struct nfs_write_data *)task->tk_calldata;
1206         nfs_commit_free(wdata);
1207 }
1208
1209 /*
1210  * Set up the argument/result storage required for the RPC call.
1211  */
1212 static void nfs_commit_rpcsetup(struct list_head *head,
1213                 struct nfs_write_data *data, int how)
1214 {
1215         struct nfs_page         *first;
1216         struct inode            *inode;
1217
1218         /* Set up the RPC argument and reply structs
1219          * NB: take care not to mess about with data->commit et al. */
1220
1221         list_splice_init(head, &data->pages);
1222         first = nfs_list_entry(data->pages.next);
1223         inode = first->wb_context->dentry->d_inode;
1224
1225         data->inode       = inode;
1226         data->cred        = first->wb_context->cred;
1227
1228         data->args.fh     = NFS_FH(data->inode);
1229         /* Note: we always request a commit of the entire inode */
1230         data->args.offset = 0;
1231         data->args.count  = 0;
1232         data->res.count   = 0;
1233         data->res.fattr   = &data->fattr;
1234         data->res.verf    = &data->verf;
1235         nfs_fattr_init(&data->fattr);
1236         
1237         NFS_PROTO(inode)->commit_setup(data, how);
1238
1239         data->task.tk_priority = flush_task_priority(how);
1240         data->task.tk_cookie = (unsigned long)inode;
1241         data->task.tk_calldata = data;
1242         /* Release requests */
1243         data->task.tk_release = nfs_commit_release;
1244         
1245         dprintk("NFS: %4d initiated commit call\n", data->task.tk_pid);
1246 }
1247
1248 /*
1249  * Commit dirty pages
1250  */
1251 static int
1252 nfs_commit_list(struct list_head *head, int how)
1253 {
1254         struct nfs_write_data   *data;
1255         struct nfs_page         *req;
1256
1257         data = nfs_commit_alloc();
1258
1259         if (!data)
1260                 goto out_bad;
1261
1262         /* Set up the argument struct */
1263         nfs_commit_rpcsetup(head, data, how);
1264
1265         nfs_execute_write(data);
1266         return 0;
1267  out_bad:
1268         while (!list_empty(head)) {
1269                 req = nfs_list_entry(head->next);
1270                 nfs_list_remove_request(req);
1271                 nfs_mark_request_commit(req);
1272                 nfs_clear_page_writeback(req);
1273         }
1274         return -ENOMEM;
1275 }
1276
1277 /*
1278  * COMMIT call returned
1279  */
1280 void
1281 nfs_commit_done(struct rpc_task *task)
1282 {
1283         struct nfs_write_data   *data = (struct nfs_write_data *)task->tk_calldata;
1284         struct nfs_page         *req;
1285         int res = 0;
1286
1287         dprintk("NFS: %4d nfs_commit_done (status %d)\n",
1288                                 task->tk_pid, task->tk_status);
1289
1290         while (!list_empty(&data->pages)) {
1291                 req = nfs_list_entry(data->pages.next);
1292                 nfs_list_remove_request(req);
1293
1294                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1295                         req->wb_context->dentry->d_inode->i_sb->s_id,
1296                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1297                         req->wb_bytes,
1298                         (long long)req_offset(req));
1299                 if (task->tk_status < 0) {
1300                         req->wb_context->error = task->tk_status;
1301                         nfs_inode_remove_request(req);
1302                         dprintk(", error = %d\n", task->tk_status);
1303                         goto next;
1304                 }
1305
1306                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1307                  * returned by the server against all stored verfs. */
1308                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1309                         /* We have a match */
1310                         nfs_inode_remove_request(req);
1311                         dprintk(" OK\n");
1312                         goto next;
1313                 }
1314                 /* We have a mismatch. Write the page again */
1315                 dprintk(" mismatch\n");
1316                 nfs_mark_request_dirty(req);
1317         next:
1318                 nfs_clear_page_writeback(req);
1319                 res++;
1320         }
1321         sub_page_state(nr_unstable,res);
1322 }
1323 #endif
1324
1325 static int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
1326                            unsigned int npages, int how)
1327 {
1328         struct nfs_inode *nfsi = NFS_I(inode);
1329         LIST_HEAD(head);
1330         int                     res,
1331                                 error = 0;
1332
1333         spin_lock(&nfsi->req_lock);
1334         res = nfs_scan_dirty(inode, &head, idx_start, npages);
1335         spin_unlock(&nfsi->req_lock);
1336         if (res) {
1337                 struct nfs_server *server = NFS_SERVER(inode);
1338
1339                 /* For single writes, FLUSH_STABLE is more efficient */
1340                 if (res == nfsi->npages && nfsi->npages <= server->wpages) {
1341                         if (res > 1 || nfs_list_entry(head.next)->wb_bytes <= server->wsize)
1342                                 how |= FLUSH_STABLE;
1343                 }
1344                 error = nfs_flush_list(&head, server->wpages, how);
1345         }
1346         if (error < 0)
1347                 return error;
1348         return res;
1349 }
1350
1351 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1352 int nfs_commit_inode(struct inode *inode, int how)
1353 {
1354         struct nfs_inode *nfsi = NFS_I(inode);
1355         LIST_HEAD(head);
1356         int                     res,
1357                                 error = 0;
1358
1359         spin_lock(&nfsi->req_lock);
1360         res = nfs_scan_commit(inode, &head, 0, 0);
1361         spin_unlock(&nfsi->req_lock);
1362         if (res) {
1363                 error = nfs_commit_list(&head, how);
1364                 if (error < 0)
1365                         return error;
1366         }
1367         return res;
1368 }
1369 #endif
1370
1371 int nfs_sync_inode(struct inode *inode, unsigned long idx_start,
1372                   unsigned int npages, int how)
1373 {
1374         int     error,
1375                 wait;
1376
1377         wait = how & FLUSH_WAIT;
1378         how &= ~FLUSH_WAIT;
1379
1380         do {
1381                 error = 0;
1382                 if (wait)
1383                         error = nfs_wait_on_requests(inode, idx_start, npages);
1384                 if (error == 0)
1385                         error = nfs_flush_inode(inode, idx_start, npages, how);
1386 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1387                 if (error == 0)
1388                         error = nfs_commit_inode(inode, how);
1389 #endif
1390         } while (error > 0);
1391         return error;
1392 }
1393
1394 int nfs_init_writepagecache(void)
1395 {
1396         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1397                                              sizeof(struct nfs_write_data),
1398                                              0, SLAB_HWCACHE_ALIGN,
1399                                              NULL, NULL);
1400         if (nfs_wdata_cachep == NULL)
1401                 return -ENOMEM;
1402
1403         nfs_wdata_mempool = mempool_create(MIN_POOL_WRITE,
1404                                            mempool_alloc_slab,
1405                                            mempool_free_slab,
1406                                            nfs_wdata_cachep);
1407         if (nfs_wdata_mempool == NULL)
1408                 return -ENOMEM;
1409
1410         nfs_commit_mempool = mempool_create(MIN_POOL_COMMIT,
1411                                            mempool_alloc_slab,
1412                                            mempool_free_slab,
1413                                            nfs_wdata_cachep);
1414         if (nfs_commit_mempool == NULL)
1415                 return -ENOMEM;
1416
1417         return 0;
1418 }
1419
1420 void nfs_destroy_writepagecache(void)
1421 {
1422         mempool_destroy(nfs_commit_mempool);
1423         mempool_destroy(nfs_wdata_mempool);
1424         if (kmem_cache_destroy(nfs_wdata_cachep))
1425                 printk(KERN_INFO "nfs_write_data: not all structures were freed\n");
1426 }
1427