Merge 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  * 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(unsigned int pagecount)
93 {
94         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, SLAB_NOFS);
95
96         if (p) {
97                 memset(p, 0, sizeof(*p));
98                 INIT_LIST_HEAD(&p->pages);
99                 if (pagecount < NFS_PAGEVEC_SIZE)
100                         p->pagevec = &p->page_array[0];
101                 else {
102                         size_t size = ++pagecount * sizeof(struct page *);
103                         p->pagevec = kmalloc(size, GFP_NOFS);
104                         if (p->pagevec) {
105                                 memset(p->pagevec, 0, size);
106                         } else {
107                                 mempool_free(p, nfs_commit_mempool);
108                                 p = NULL;
109                         }
110                 }
111         }
112         return p;
113 }
114
115 static inline void nfs_commit_free(struct nfs_write_data *p)
116 {
117         if (p && (p->pagevec != &p->page_array[0]))
118                 kfree(p->pagevec);
119         mempool_free(p, nfs_commit_mempool);
120 }
121
122 void nfs_writedata_release(void *wdata)
123 {
124         nfs_writedata_free(wdata);
125 }
126
127 /* Adjust the file length if we're writing beyond the end */
128 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
129 {
130         struct inode *inode = page->mapping->host;
131         loff_t end, i_size = i_size_read(inode);
132         unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
133
134         if (i_size > 0 && page->index < end_index)
135                 return;
136         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
137         if (i_size >= end)
138                 return;
139         i_size_write(inode, end);
140 }
141
142 /* We can set the PG_uptodate flag if we see that a write request
143  * covers the full page.
144  */
145 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
146 {
147         loff_t end_offs;
148
149         if (PageUptodate(page))
150                 return;
151         if (base != 0)
152                 return;
153         if (count == PAGE_CACHE_SIZE) {
154                 SetPageUptodate(page);
155                 return;
156         }
157
158         end_offs = i_size_read(page->mapping->host) - 1;
159         if (end_offs < 0)
160                 return;
161         /* Is this the last page? */
162         if (page->index != (unsigned long)(end_offs >> PAGE_CACHE_SHIFT))
163                 return;
164         /* This is the last page: set PG_uptodate if we cover the entire
165          * extent of the data, then zero the rest of the page.
166          */
167         if (count == (unsigned int)(end_offs & (PAGE_CACHE_SIZE - 1)) + 1) {
168                 memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
169                 SetPageUptodate(page);
170         }
171 }
172
173 /*
174  * Write a page synchronously.
175  * Offset is the data offset within the page.
176  */
177 static int nfs_writepage_sync(struct nfs_open_context *ctx, struct inode *inode,
178                 struct page *page, unsigned int offset, unsigned int count,
179                 int how)
180 {
181         unsigned int    wsize = NFS_SERVER(inode)->wsize;
182         int             result, written = 0;
183         struct nfs_write_data *wdata;
184
185         wdata = nfs_writedata_alloc(1);
186         if (!wdata)
187                 return -ENOMEM;
188
189         wdata->flags = how;
190         wdata->cred = ctx->cred;
191         wdata->inode = inode;
192         wdata->args.fh = NFS_FH(inode);
193         wdata->args.context = ctx;
194         wdata->args.pages = &page;
195         wdata->args.stable = NFS_FILE_SYNC;
196         wdata->args.pgbase = offset;
197         wdata->args.count = wsize;
198         wdata->res.fattr = &wdata->fattr;
199         wdata->res.verf = &wdata->verf;
200
201         dprintk("NFS:      nfs_writepage_sync(%s/%Ld %d@%Ld)\n",
202                 inode->i_sb->s_id,
203                 (long long)NFS_FILEID(inode),
204                 count, (long long)(page_offset(page) + offset));
205
206         set_page_writeback(page);
207         nfs_begin_data_update(inode);
208         do {
209                 if (count < wsize)
210                         wdata->args.count = count;
211                 wdata->args.offset = page_offset(page) + wdata->args.pgbase;
212
213                 result = NFS_PROTO(inode)->write(wdata);
214
215                 if (result < 0) {
216                         /* Must mark the page invalid after I/O error */
217                         ClearPageUptodate(page);
218                         goto io_error;
219                 }
220                 if (result < wdata->args.count)
221                         printk(KERN_WARNING "NFS: short write, count=%u, result=%d\n",
222                                         wdata->args.count, result);
223
224                 wdata->args.offset += result;
225                 wdata->args.pgbase += result;
226                 written += result;
227                 count -= result;
228         } while (count);
229         /* Update file length */
230         nfs_grow_file(page, offset, written);
231         /* Set the PG_uptodate flag? */
232         nfs_mark_uptodate(page, offset, written);
233
234         if (PageError(page))
235                 ClearPageError(page);
236
237 io_error:
238         nfs_end_data_update(inode);
239         end_page_writeback(page);
240         nfs_writedata_free(wdata);
241         return written ? written : result;
242 }
243
244 static int nfs_writepage_async(struct nfs_open_context *ctx,
245                 struct inode *inode, struct page *page,
246                 unsigned int offset, unsigned int count)
247 {
248         struct nfs_page *req;
249
250         req = nfs_update_request(ctx, inode, page, offset, count);
251         if (IS_ERR(req))
252                 return PTR_ERR(req);
253         /* Update file length */
254         nfs_grow_file(page, offset, count);
255         /* Set the PG_uptodate flag? */
256         nfs_mark_uptodate(page, offset, count);
257         nfs_unlock_request(req);
258         return 0;
259 }
260
261 static int wb_priority(struct writeback_control *wbc)
262 {
263         if (wbc->for_reclaim)
264                 return FLUSH_HIGHPRI;
265         if (wbc->for_kupdate)
266                 return FLUSH_LOWPRI;
267         return 0;
268 }
269
270 /*
271  * Write an mmapped page to the server.
272  */
273 int nfs_writepage(struct page *page, struct writeback_control *wbc)
274 {
275         struct nfs_open_context *ctx;
276         struct inode *inode = page->mapping->host;
277         unsigned long end_index;
278         unsigned offset = PAGE_CACHE_SIZE;
279         loff_t i_size = i_size_read(inode);
280         int inode_referenced = 0;
281         int priority = wb_priority(wbc);
282         int err;
283
284         /*
285          * Note: We need to ensure that we have a reference to the inode
286          *       if we are to do asynchronous writes. If not, waiting
287          *       in nfs_wait_on_request() may deadlock with clear_inode().
288          *
289          *       If igrab() fails here, then it is in any case safe to
290          *       call nfs_wb_page(), since there will be no pending writes.
291          */
292         if (igrab(inode) != 0)
293                 inode_referenced = 1;
294         end_index = i_size >> PAGE_CACHE_SHIFT;
295
296         /* Ensure we've flushed out any previous writes */
297         nfs_wb_page_priority(inode, page, priority);
298
299         /* easy case */
300         if (page->index < end_index)
301                 goto do_it;
302         /* things got complicated... */
303         offset = i_size & (PAGE_CACHE_SIZE-1);
304
305         /* OK, are we completely out? */
306         err = 0; /* potential race with truncate - ignore */
307         if (page->index >= end_index+1 || !offset)
308                 goto out;
309 do_it:
310         ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
311         if (ctx == NULL) {
312                 err = -EBADF;
313                 goto out;
314         }
315         lock_kernel();
316         if (!IS_SYNC(inode) && inode_referenced) {
317                 err = nfs_writepage_async(ctx, inode, page, 0, offset);
318                 if (!wbc->for_writepages)
319                         nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
320         } else {
321                 err = nfs_writepage_sync(ctx, inode, page, 0,
322                                                 offset, priority);
323                 if (err >= 0) {
324                         if (err != offset)
325                                 redirty_page_for_writepage(wbc, page);
326                         err = 0;
327                 }
328         }
329         unlock_kernel();
330         put_nfs_open_context(ctx);
331 out:
332         unlock_page(page);
333         if (inode_referenced)
334                 iput(inode);
335         return err; 
336 }
337
338 /*
339  * Note: causes nfs_update_request() to block on the assumption
340  *       that the writeback is generated due to memory pressure.
341  */
342 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
343 {
344         struct backing_dev_info *bdi = mapping->backing_dev_info;
345         struct inode *inode = mapping->host;
346         int err;
347
348         err = generic_writepages(mapping, wbc);
349         if (err)
350                 return err;
351         while (test_and_set_bit(BDI_write_congested, &bdi->state) != 0) {
352                 if (wbc->nonblocking)
353                         return 0;
354                 nfs_wait_on_write_congestion(mapping, 0);
355         }
356         err = nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
357         if (err < 0)
358                 goto out;
359         wbc->nr_to_write -= err;
360         if (!wbc->nonblocking && wbc->sync_mode == WB_SYNC_ALL) {
361                 err = nfs_wait_on_requests(inode, 0, 0);
362                 if (err < 0)
363                         goto out;
364         }
365         err = nfs_commit_inode(inode, wb_priority(wbc));
366         if (err > 0) {
367                 wbc->nr_to_write -= err;
368                 err = 0;
369         }
370 out:
371         clear_bit(BDI_write_congested, &bdi->state);
372         wake_up_all(&nfs_write_congestion);
373         return err;
374 }
375
376 /*
377  * Insert a write request into an inode
378  */
379 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
380 {
381         struct nfs_inode *nfsi = NFS_I(inode);
382         int error;
383
384         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
385         BUG_ON(error == -EEXIST);
386         if (error)
387                 return error;
388         if (!nfsi->npages) {
389                 igrab(inode);
390                 nfs_begin_data_update(inode);
391                 if (nfs_have_delegation(inode, FMODE_WRITE))
392                         nfsi->change_attr++;
393         }
394         nfsi->npages++;
395         atomic_inc(&req->wb_count);
396         return 0;
397 }
398
399 /*
400  * Insert a write request into an inode
401  */
402 static void nfs_inode_remove_request(struct nfs_page *req)
403 {
404         struct inode *inode = req->wb_context->dentry->d_inode;
405         struct nfs_inode *nfsi = NFS_I(inode);
406
407         BUG_ON (!NFS_WBACK_BUSY(req));
408
409         spin_lock(&nfsi->req_lock);
410         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
411         nfsi->npages--;
412         if (!nfsi->npages) {
413                 spin_unlock(&nfsi->req_lock);
414                 nfs_end_data_update(inode);
415                 iput(inode);
416         } else
417                 spin_unlock(&nfsi->req_lock);
418         nfs_clear_request(req);
419         nfs_release_request(req);
420 }
421
422 /*
423  * Find a request
424  */
425 static inline struct nfs_page *
426 _nfs_find_request(struct inode *inode, unsigned long index)
427 {
428         struct nfs_inode *nfsi = NFS_I(inode);
429         struct nfs_page *req;
430
431         req = (struct nfs_page*)radix_tree_lookup(&nfsi->nfs_page_tree, index);
432         if (req)
433                 atomic_inc(&req->wb_count);
434         return req;
435 }
436
437 static struct nfs_page *
438 nfs_find_request(struct inode *inode, unsigned long index)
439 {
440         struct nfs_page         *req;
441         struct nfs_inode        *nfsi = NFS_I(inode);
442
443         spin_lock(&nfsi->req_lock);
444         req = _nfs_find_request(inode, index);
445         spin_unlock(&nfsi->req_lock);
446         return req;
447 }
448
449 /*
450  * Add a request to the inode's dirty list.
451  */
452 static void
453 nfs_mark_request_dirty(struct nfs_page *req)
454 {
455         struct inode *inode = req->wb_context->dentry->d_inode;
456         struct nfs_inode *nfsi = NFS_I(inode);
457
458         spin_lock(&nfsi->req_lock);
459         radix_tree_tag_set(&nfsi->nfs_page_tree,
460                         req->wb_index, NFS_PAGE_TAG_DIRTY);
461         nfs_list_add_request(req, &nfsi->dirty);
462         nfsi->ndirty++;
463         spin_unlock(&nfsi->req_lock);
464         inc_page_state(nr_dirty);
465         mark_inode_dirty(inode);
466 }
467
468 /*
469  * Check if a request is dirty
470  */
471 static inline int
472 nfs_dirty_request(struct nfs_page *req)
473 {
474         struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
475         return !list_empty(&req->wb_list) && req->wb_list_head == &nfsi->dirty;
476 }
477
478 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
479 /*
480  * Add a request to the inode's commit list.
481  */
482 static void
483 nfs_mark_request_commit(struct nfs_page *req)
484 {
485         struct inode *inode = req->wb_context->dentry->d_inode;
486         struct nfs_inode *nfsi = NFS_I(inode);
487
488         spin_lock(&nfsi->req_lock);
489         nfs_list_add_request(req, &nfsi->commit);
490         nfsi->ncommit++;
491         spin_unlock(&nfsi->req_lock);
492         inc_page_state(nr_unstable);
493         mark_inode_dirty(inode);
494 }
495 #endif
496
497 /*
498  * Wait for a request to complete.
499  *
500  * Interruptible by signals only if mounted with intr flag.
501  */
502 static int
503 nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int npages)
504 {
505         struct nfs_inode *nfsi = NFS_I(inode);
506         struct nfs_page *req;
507         unsigned long           idx_end, next;
508         unsigned int            res = 0;
509         int                     error;
510
511         if (npages == 0)
512                 idx_end = ~0;
513         else
514                 idx_end = idx_start + npages - 1;
515
516         spin_lock(&nfsi->req_lock);
517         next = idx_start;
518         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
519                 if (req->wb_index > idx_end)
520                         break;
521
522                 next = req->wb_index + 1;
523                 BUG_ON(!NFS_WBACK_BUSY(req));
524
525                 atomic_inc(&req->wb_count);
526                 spin_unlock(&nfsi->req_lock);
527                 error = nfs_wait_on_request(req);
528                 nfs_release_request(req);
529                 if (error < 0)
530                         return error;
531                 spin_lock(&nfsi->req_lock);
532                 res++;
533         }
534         spin_unlock(&nfsi->req_lock);
535         return res;
536 }
537
538 /*
539  * nfs_scan_dirty - Scan an inode for dirty requests
540  * @inode: NFS inode to scan
541  * @dst: destination list
542  * @idx_start: lower bound of page->index to scan.
543  * @npages: idx_start + npages sets the upper bound to scan.
544  *
545  * Moves requests from the inode's dirty page list.
546  * The requests are *not* checked to ensure that they form a contiguous set.
547  */
548 static int
549 nfs_scan_dirty(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
550 {
551         struct nfs_inode *nfsi = NFS_I(inode);
552         int res = 0;
553
554         if (nfsi->ndirty != 0) {
555                 res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
556                 nfsi->ndirty -= res;
557                 sub_page_state(nr_dirty,res);
558                 if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
559                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
560         }
561         return res;
562 }
563
564 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
565 /*
566  * nfs_scan_commit - Scan an inode for commit requests
567  * @inode: NFS inode to scan
568  * @dst: destination list
569  * @idx_start: lower bound of page->index to scan.
570  * @npages: idx_start + npages sets the upper bound to scan.
571  *
572  * Moves requests from the inode's 'commit' request list.
573  * The requests are *not* checked to ensure that they form a contiguous set.
574  */
575 static int
576 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
577 {
578         struct nfs_inode *nfsi = NFS_I(inode);
579         int res = 0;
580
581         if (nfsi->ncommit != 0) {
582                 res = nfs_scan_list(&nfsi->commit, dst, idx_start, npages);
583                 nfsi->ncommit -= res;
584                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
585                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
586         }
587         return res;
588 }
589 #endif
590
591 static int nfs_wait_on_write_congestion(struct address_space *mapping, int intr)
592 {
593         struct backing_dev_info *bdi = mapping->backing_dev_info;
594         DEFINE_WAIT(wait);
595         int ret = 0;
596
597         might_sleep();
598
599         if (!bdi_write_congested(bdi))
600                 return 0;
601         if (intr) {
602                 struct rpc_clnt *clnt = NFS_CLIENT(mapping->host);
603                 sigset_t oldset;
604
605                 rpc_clnt_sigmask(clnt, &oldset);
606                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_INTERRUPTIBLE);
607                 if (bdi_write_congested(bdi)) {
608                         if (signalled())
609                                 ret = -ERESTARTSYS;
610                         else
611                                 schedule();
612                 }
613                 rpc_clnt_sigunmask(clnt, &oldset);
614         } else {
615                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_UNINTERRUPTIBLE);
616                 if (bdi_write_congested(bdi))
617                         schedule();
618         }
619         finish_wait(&nfs_write_congestion, &wait);
620         return ret;
621 }
622
623
624 /*
625  * Try to update any existing write request, or create one if there is none.
626  * In order to match, the request's credentials must match those of
627  * the calling process.
628  *
629  * Note: Should always be called with the Page Lock held!
630  */
631 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
632                 struct inode *inode, struct page *page,
633                 unsigned int offset, unsigned int bytes)
634 {
635         struct nfs_server *server = NFS_SERVER(inode);
636         struct nfs_inode *nfsi = NFS_I(inode);
637         struct nfs_page         *req, *new = NULL;
638         unsigned long           rqend, end;
639
640         end = offset + bytes;
641
642         if (nfs_wait_on_write_congestion(page->mapping, server->flags & NFS_MOUNT_INTR))
643                 return ERR_PTR(-ERESTARTSYS);
644         for (;;) {
645                 /* Loop over all inode entries and see if we find
646                  * A request for the page we wish to update
647                  */
648                 spin_lock(&nfsi->req_lock);
649                 req = _nfs_find_request(inode, page->index);
650                 if (req) {
651                         if (!nfs_lock_request_dontget(req)) {
652                                 int error;
653                                 spin_unlock(&nfsi->req_lock);
654                                 error = nfs_wait_on_request(req);
655                                 nfs_release_request(req);
656                                 if (error < 0)
657                                         return ERR_PTR(error);
658                                 continue;
659                         }
660                         spin_unlock(&nfsi->req_lock);
661                         if (new)
662                                 nfs_release_request(new);
663                         break;
664                 }
665
666                 if (new) {
667                         int error;
668                         nfs_lock_request_dontget(new);
669                         error = nfs_inode_add_request(inode, new);
670                         if (error) {
671                                 spin_unlock(&nfsi->req_lock);
672                                 nfs_unlock_request(new);
673                                 return ERR_PTR(error);
674                         }
675                         spin_unlock(&nfsi->req_lock);
676                         nfs_mark_request_dirty(new);
677                         return new;
678                 }
679                 spin_unlock(&nfsi->req_lock);
680
681                 new = nfs_create_request(ctx, inode, page, offset, bytes);
682                 if (IS_ERR(new))
683                         return new;
684         }
685
686         /* We have a request for our page.
687          * If the creds don't match, or the
688          * page addresses don't match,
689          * tell the caller to wait on the conflicting
690          * request.
691          */
692         rqend = req->wb_offset + req->wb_bytes;
693         if (req->wb_context != ctx
694             || req->wb_page != page
695             || !nfs_dirty_request(req)
696             || offset > rqend || end < req->wb_offset) {
697                 nfs_unlock_request(req);
698                 return ERR_PTR(-EBUSY);
699         }
700
701         /* Okay, the request matches. Update the region */
702         if (offset < req->wb_offset) {
703                 req->wb_offset = offset;
704                 req->wb_pgbase = offset;
705                 req->wb_bytes = rqend - req->wb_offset;
706         }
707
708         if (end > rqend)
709                 req->wb_bytes = end - req->wb_offset;
710
711         return req;
712 }
713
714 int nfs_flush_incompatible(struct file *file, struct page *page)
715 {
716         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
717         struct inode    *inode = page->mapping->host;
718         struct nfs_page *req;
719         int             status = 0;
720         /*
721          * Look for a request corresponding to this page. If there
722          * is one, and it belongs to another file, we flush it out
723          * before we try to copy anything into the page. Do this
724          * due to the lack of an ACCESS-type call in NFSv2.
725          * Also do the same if we find a request from an existing
726          * dropped page.
727          */
728         req = nfs_find_request(inode, page->index);
729         if (req) {
730                 if (req->wb_page != page || ctx != req->wb_context)
731                         status = nfs_wb_page(inode, page);
732                 nfs_release_request(req);
733         }
734         return (status < 0) ? status : 0;
735 }
736
737 /*
738  * Update and possibly write a cached page of an NFS file.
739  *
740  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
741  * things with a page scheduled for an RPC call (e.g. invalidate it).
742  */
743 int nfs_updatepage(struct file *file, struct page *page,
744                 unsigned int offset, unsigned int count)
745 {
746         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
747         struct inode    *inode = page->mapping->host;
748         struct nfs_page *req;
749         int             status = 0;
750
751         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
752                 file->f_dentry->d_parent->d_name.name,
753                 file->f_dentry->d_name.name, count,
754                 (long long)(page_offset(page) +offset));
755
756         if (IS_SYNC(inode)) {
757                 status = nfs_writepage_sync(ctx, inode, page, offset, count, 0);
758                 if (status > 0) {
759                         if (offset == 0 && status == PAGE_CACHE_SIZE)
760                                 SetPageUptodate(page);
761                         return 0;
762                 }
763                 return status;
764         }
765
766         /* If we're not using byte range locks, and we know the page
767          * is entirely in cache, it may be more efficient to avoid
768          * fragmenting write requests.
769          */
770         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
771                 loff_t end_offs = i_size_read(inode) - 1;
772                 unsigned long end_index = end_offs >> PAGE_CACHE_SHIFT;
773
774                 count += offset;
775                 offset = 0;
776                 if (unlikely(end_offs < 0)) {
777                         /* Do nothing */
778                 } else if (page->index == end_index) {
779                         unsigned int pglen;
780                         pglen = (unsigned int)(end_offs & (PAGE_CACHE_SIZE-1)) + 1;
781                         if (count < pglen)
782                                 count = pglen;
783                 } else if (page->index < end_index)
784                         count = PAGE_CACHE_SIZE;
785         }
786
787         /*
788          * Try to find an NFS request corresponding to this page
789          * and update it.
790          * If the existing request cannot be updated, we must flush
791          * it out now.
792          */
793         do {
794                 req = nfs_update_request(ctx, inode, page, offset, count);
795                 status = (IS_ERR(req)) ? PTR_ERR(req) : 0;
796                 if (status != -EBUSY)
797                         break;
798                 /* Request could not be updated. Flush it out and try again */
799                 status = nfs_wb_page(inode, page);
800         } while (status >= 0);
801         if (status < 0)
802                 goto done;
803
804         status = 0;
805
806         /* Update file length */
807         nfs_grow_file(page, offset, count);
808         /* Set the PG_uptodate flag? */
809         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
810         nfs_unlock_request(req);
811 done:
812         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
813                         status, (long long)i_size_read(inode));
814         if (status < 0)
815                 ClearPageUptodate(page);
816         return status;
817 }
818
819 static void nfs_writepage_release(struct nfs_page *req)
820 {
821         end_page_writeback(req->wb_page);
822
823 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
824         if (!PageError(req->wb_page)) {
825                 if (NFS_NEED_RESCHED(req)) {
826                         nfs_mark_request_dirty(req);
827                         goto out;
828                 } else if (NFS_NEED_COMMIT(req)) {
829                         nfs_mark_request_commit(req);
830                         goto out;
831                 }
832         }
833         nfs_inode_remove_request(req);
834
835 out:
836         nfs_clear_commit(req);
837         nfs_clear_reschedule(req);
838 #else
839         nfs_inode_remove_request(req);
840 #endif
841         nfs_clear_page_writeback(req);
842 }
843
844 static inline int flush_task_priority(int how)
845 {
846         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
847                 case FLUSH_HIGHPRI:
848                         return RPC_PRIORITY_HIGH;
849                 case FLUSH_LOWPRI:
850                         return RPC_PRIORITY_LOW;
851         }
852         return RPC_PRIORITY_NORMAL;
853 }
854
855 /*
856  * Set up the argument/result storage required for the RPC call.
857  */
858 static void nfs_write_rpcsetup(struct nfs_page *req,
859                 struct nfs_write_data *data,
860                 unsigned int count, unsigned int offset,
861                 int how)
862 {
863         struct inode            *inode;
864
865         /* Set up the RPC argument and reply structs
866          * NB: take care not to mess about with data->commit et al. */
867
868         data->req = req;
869         data->inode = inode = req->wb_context->dentry->d_inode;
870         data->cred = req->wb_context->cred;
871
872         data->args.fh     = NFS_FH(inode);
873         data->args.offset = req_offset(req) + offset;
874         data->args.pgbase = req->wb_pgbase + offset;
875         data->args.pages  = data->pagevec;
876         data->args.count  = count;
877         data->args.context = req->wb_context;
878
879         data->res.fattr   = &data->fattr;
880         data->res.count   = count;
881         data->res.verf    = &data->verf;
882         nfs_fattr_init(&data->fattr);
883
884         NFS_PROTO(inode)->write_setup(data, how);
885
886         data->task.tk_priority = flush_task_priority(how);
887         data->task.tk_cookie = (unsigned long)inode;
888
889         dprintk("NFS: %4d initiated write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
890                 data->task.tk_pid,
891                 inode->i_sb->s_id,
892                 (long long)NFS_FILEID(inode),
893                 count,
894                 (unsigned long long)data->args.offset);
895 }
896
897 static void nfs_execute_write(struct nfs_write_data *data)
898 {
899         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
900         sigset_t oldset;
901
902         rpc_clnt_sigmask(clnt, &oldset);
903         lock_kernel();
904         rpc_execute(&data->task);
905         unlock_kernel();
906         rpc_clnt_sigunmask(clnt, &oldset);
907 }
908
909 /*
910  * Generate multiple small requests to write out a single
911  * contiguous dirty area on one page.
912  */
913 static int nfs_flush_multi(struct list_head *head, struct inode *inode, int how)
914 {
915         struct nfs_page *req = nfs_list_entry(head->next);
916         struct page *page = req->wb_page;
917         struct nfs_write_data *data;
918         unsigned int wsize = NFS_SERVER(inode)->wsize;
919         unsigned int nbytes, offset;
920         int requests = 0;
921         LIST_HEAD(list);
922
923         nfs_list_remove_request(req);
924
925         nbytes = req->wb_bytes;
926         for (;;) {
927                 data = nfs_writedata_alloc(1);
928                 if (!data)
929                         goto out_bad;
930                 list_add(&data->pages, &list);
931                 requests++;
932                 if (nbytes <= wsize)
933                         break;
934                 nbytes -= wsize;
935         }
936         atomic_set(&req->wb_complete, requests);
937
938         ClearPageError(page);
939         set_page_writeback(page);
940         offset = 0;
941         nbytes = req->wb_bytes;
942         do {
943                 data = list_entry(list.next, struct nfs_write_data, pages);
944                 list_del_init(&data->pages);
945
946                 data->pagevec[0] = page;
947                 data->complete = nfs_writeback_done_partial;
948
949                 if (nbytes > wsize) {
950                         nfs_write_rpcsetup(req, data, wsize, offset, how);
951                         offset += wsize;
952                         nbytes -= wsize;
953                 } else {
954                         nfs_write_rpcsetup(req, data, nbytes, offset, how);
955                         nbytes = 0;
956                 }
957                 nfs_execute_write(data);
958         } while (nbytes != 0);
959
960         return 0;
961
962 out_bad:
963         while (!list_empty(&list)) {
964                 data = list_entry(list.next, struct nfs_write_data, pages);
965                 list_del(&data->pages);
966                 nfs_writedata_free(data);
967         }
968         nfs_mark_request_dirty(req);
969         nfs_clear_page_writeback(req);
970         return -ENOMEM;
971 }
972
973 /*
974  * Create an RPC task for the given write request and kick it.
975  * The page must have been locked by the caller.
976  *
977  * It may happen that the page we're passed is not marked dirty.
978  * This is the case if nfs_updatepage detects a conflicting request
979  * that has been written but not committed.
980  */
981 static int nfs_flush_one(struct list_head *head, struct inode *inode, int how)
982 {
983         struct nfs_page         *req;
984         struct page             **pages;
985         struct nfs_write_data   *data;
986         unsigned int            count;
987
988         if (NFS_SERVER(inode)->wsize < PAGE_CACHE_SIZE)
989                 return nfs_flush_multi(head, inode, how);
990
991         data = nfs_writedata_alloc(NFS_SERVER(inode)->wpages);
992         if (!data)
993                 goto out_bad;
994
995         pages = data->pagevec;
996         count = 0;
997         while (!list_empty(head)) {
998                 req = nfs_list_entry(head->next);
999                 nfs_list_remove_request(req);
1000                 nfs_list_add_request(req, &data->pages);
1001                 ClearPageError(req->wb_page);
1002                 set_page_writeback(req->wb_page);
1003                 *pages++ = req->wb_page;
1004                 count += req->wb_bytes;
1005         }
1006         req = nfs_list_entry(data->pages.next);
1007
1008         data->complete = nfs_writeback_done_full;
1009         /* Set up the argument struct */
1010         nfs_write_rpcsetup(req, data, count, 0, how);
1011
1012         nfs_execute_write(data);
1013         return 0;
1014  out_bad:
1015         while (!list_empty(head)) {
1016                 struct nfs_page *req = nfs_list_entry(head->next);
1017                 nfs_list_remove_request(req);
1018                 nfs_mark_request_dirty(req);
1019                 nfs_clear_page_writeback(req);
1020         }
1021         return -ENOMEM;
1022 }
1023
1024 static int
1025 nfs_flush_list(struct list_head *head, int wpages, int how)
1026 {
1027         LIST_HEAD(one_request);
1028         struct nfs_page         *req;
1029         int                     error = 0;
1030         unsigned int            pages = 0;
1031
1032         while (!list_empty(head)) {
1033                 pages += nfs_coalesce_requests(head, &one_request, wpages);
1034                 req = nfs_list_entry(one_request.next);
1035                 error = nfs_flush_one(&one_request, req->wb_context->dentry->d_inode, how);
1036                 if (error < 0)
1037                         break;
1038         }
1039         if (error >= 0)
1040                 return pages;
1041
1042         while (!list_empty(head)) {
1043                 req = nfs_list_entry(head->next);
1044                 nfs_list_remove_request(req);
1045                 nfs_mark_request_dirty(req);
1046                 nfs_clear_page_writeback(req);
1047         }
1048         return error;
1049 }
1050
1051 /*
1052  * Handle a write reply that flushed part of a page.
1053  */
1054 static void nfs_writeback_done_partial(struct nfs_write_data *data, int status)
1055 {
1056         struct nfs_page         *req = data->req;
1057         struct page             *page = req->wb_page;
1058
1059         dprintk("NFS: write (%s/%Ld %d@%Ld)",
1060                 req->wb_context->dentry->d_inode->i_sb->s_id,
1061                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1062                 req->wb_bytes,
1063                 (long long)req_offset(req));
1064
1065         if (status < 0) {
1066                 ClearPageUptodate(page);
1067                 SetPageError(page);
1068                 req->wb_context->error = status;
1069                 dprintk(", error = %d\n", status);
1070         } else {
1071 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1072                 if (data->verf.committed < NFS_FILE_SYNC) {
1073                         if (!NFS_NEED_COMMIT(req)) {
1074                                 nfs_defer_commit(req);
1075                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1076                                 dprintk(" defer commit\n");
1077                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1078                                 nfs_defer_reschedule(req);
1079                                 dprintk(" server reboot detected\n");
1080                         }
1081                 } else
1082 #endif
1083                         dprintk(" OK\n");
1084         }
1085
1086         if (atomic_dec_and_test(&req->wb_complete))
1087                 nfs_writepage_release(req);
1088 }
1089
1090 /*
1091  * Handle a write reply that flushes a whole page.
1092  *
1093  * FIXME: There is an inherent race with invalidate_inode_pages and
1094  *        writebacks since the page->count is kept > 1 for as long
1095  *        as the page has a write request pending.
1096  */
1097 static void nfs_writeback_done_full(struct nfs_write_data *data, int status)
1098 {
1099         struct nfs_page         *req;
1100         struct page             *page;
1101
1102         /* Update attributes as result of writeback. */
1103         while (!list_empty(&data->pages)) {
1104                 req = nfs_list_entry(data->pages.next);
1105                 nfs_list_remove_request(req);
1106                 page = req->wb_page;
1107
1108                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1109                         req->wb_context->dentry->d_inode->i_sb->s_id,
1110                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1111                         req->wb_bytes,
1112                         (long long)req_offset(req));
1113
1114                 if (status < 0) {
1115                         ClearPageUptodate(page);
1116                         SetPageError(page);
1117                         req->wb_context->error = status;
1118                         end_page_writeback(page);
1119                         nfs_inode_remove_request(req);
1120                         dprintk(", error = %d\n", status);
1121                         goto next;
1122                 }
1123                 end_page_writeback(page);
1124
1125 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1126                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1127                         nfs_inode_remove_request(req);
1128                         dprintk(" OK\n");
1129                         goto next;
1130                 }
1131                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1132                 nfs_mark_request_commit(req);
1133                 dprintk(" marked for commit\n");
1134 #else
1135                 nfs_inode_remove_request(req);
1136 #endif
1137         next:
1138                 nfs_clear_page_writeback(req);
1139         }
1140 }
1141
1142 /*
1143  * This function is called when the WRITE call is complete.
1144  */
1145 void nfs_writeback_done(struct rpc_task *task, void *calldata)
1146 {
1147         struct nfs_write_data   *data = calldata;
1148         struct nfs_writeargs    *argp = &data->args;
1149         struct nfs_writeres     *resp = &data->res;
1150
1151         dprintk("NFS: %4d nfs_writeback_done (status %d)\n",
1152                 task->tk_pid, task->tk_status);
1153
1154 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1155         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1156                 /* We tried a write call, but the server did not
1157                  * commit data to stable storage even though we
1158                  * requested it.
1159                  * Note: There is a known bug in Tru64 < 5.0 in which
1160                  *       the server reports NFS_DATA_SYNC, but performs
1161                  *       NFS_FILE_SYNC. We therefore implement this checking
1162                  *       as a dprintk() in order to avoid filling syslog.
1163                  */
1164                 static unsigned long    complain;
1165
1166                 if (time_before(complain, jiffies)) {
1167                         dprintk("NFS: faulty NFS server %s:"
1168                                 " (committed = %d) != (stable = %d)\n",
1169                                 NFS_SERVER(data->inode)->hostname,
1170                                 resp->verf->committed, argp->stable);
1171                         complain = jiffies + 300 * HZ;
1172                 }
1173         }
1174 #endif
1175         /* Is this a short write? */
1176         if (task->tk_status >= 0 && resp->count < argp->count) {
1177                 static unsigned long    complain;
1178
1179                 /* Has the server at least made some progress? */
1180                 if (resp->count != 0) {
1181                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1182                         if (resp->verf->committed != NFS_UNSTABLE) {
1183                                 /* Resend from where the server left off */
1184                                 argp->offset += resp->count;
1185                                 argp->pgbase += resp->count;
1186                                 argp->count -= resp->count;
1187                         } else {
1188                                 /* Resend as a stable write in order to avoid
1189                                  * headaches in the case of a server crash.
1190                                  */
1191                                 argp->stable = NFS_FILE_SYNC;
1192                         }
1193                         rpc_restart_call(task);
1194                         return;
1195                 }
1196                 if (time_before(complain, jiffies)) {
1197                         printk(KERN_WARNING
1198                                "NFS: Server wrote zero bytes, expected %u.\n",
1199                                         argp->count);
1200                         complain = jiffies + 300 * HZ;
1201                 }
1202                 /* Can't do anything about it except throw an error. */
1203                 task->tk_status = -EIO;
1204         }
1205
1206         /*
1207          * Process the nfs_page list
1208          */
1209         data->complete(data, task->tk_status);
1210 }
1211
1212
1213 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1214 void nfs_commit_release(void *wdata)
1215 {
1216         nfs_commit_free(wdata);
1217 }
1218
1219 /*
1220  * Set up the argument/result storage required for the RPC call.
1221  */
1222 static void nfs_commit_rpcsetup(struct list_head *head,
1223                 struct nfs_write_data *data, int how)
1224 {
1225         struct nfs_page         *first;
1226         struct inode            *inode;
1227
1228         /* Set up the RPC argument and reply structs
1229          * NB: take care not to mess about with data->commit et al. */
1230
1231         list_splice_init(head, &data->pages);
1232         first = nfs_list_entry(data->pages.next);
1233         inode = first->wb_context->dentry->d_inode;
1234
1235         data->inode       = inode;
1236         data->cred        = first->wb_context->cred;
1237
1238         data->args.fh     = NFS_FH(data->inode);
1239         /* Note: we always request a commit of the entire inode */
1240         data->args.offset = 0;
1241         data->args.count  = 0;
1242         data->res.count   = 0;
1243         data->res.fattr   = &data->fattr;
1244         data->res.verf    = &data->verf;
1245         nfs_fattr_init(&data->fattr);
1246         
1247         NFS_PROTO(inode)->commit_setup(data, how);
1248
1249         data->task.tk_priority = flush_task_priority(how);
1250         data->task.tk_cookie = (unsigned long)inode;
1251         
1252         dprintk("NFS: %4d initiated commit call\n", data->task.tk_pid);
1253 }
1254
1255 /*
1256  * Commit dirty pages
1257  */
1258 static int
1259 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1260 {
1261         struct nfs_write_data   *data;
1262         struct nfs_page         *req;
1263
1264         data = nfs_commit_alloc(NFS_SERVER(inode)->wpages);
1265
1266         if (!data)
1267                 goto out_bad;
1268
1269         /* Set up the argument struct */
1270         nfs_commit_rpcsetup(head, data, how);
1271
1272         nfs_execute_write(data);
1273         return 0;
1274  out_bad:
1275         while (!list_empty(head)) {
1276                 req = nfs_list_entry(head->next);
1277                 nfs_list_remove_request(req);
1278                 nfs_mark_request_commit(req);
1279                 nfs_clear_page_writeback(req);
1280         }
1281         return -ENOMEM;
1282 }
1283
1284 /*
1285  * COMMIT call returned
1286  */
1287 void nfs_commit_done(struct rpc_task *task, void *calldata)
1288 {
1289         struct nfs_write_data   *data = calldata;
1290         struct nfs_page         *req;
1291         int res = 0;
1292
1293         dprintk("NFS: %4d nfs_commit_done (status %d)\n",
1294                                 task->tk_pid, task->tk_status);
1295
1296         while (!list_empty(&data->pages)) {
1297                 req = nfs_list_entry(data->pages.next);
1298                 nfs_list_remove_request(req);
1299
1300                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1301                         req->wb_context->dentry->d_inode->i_sb->s_id,
1302                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1303                         req->wb_bytes,
1304                         (long long)req_offset(req));
1305                 if (task->tk_status < 0) {
1306                         req->wb_context->error = task->tk_status;
1307                         nfs_inode_remove_request(req);
1308                         dprintk(", error = %d\n", task->tk_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_writeback(req);
1325                 res++;
1326         }
1327         sub_page_state(nr_unstable,res);
1328 }
1329 #endif
1330
1331 static int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
1332                            unsigned int npages, int how)
1333 {
1334         struct nfs_inode *nfsi = NFS_I(inode);
1335         LIST_HEAD(head);
1336         int                     res,
1337                                 error = 0;
1338
1339         spin_lock(&nfsi->req_lock);
1340         res = nfs_scan_dirty(inode, &head, idx_start, npages);
1341         spin_unlock(&nfsi->req_lock);
1342         if (res) {
1343                 struct nfs_server *server = NFS_SERVER(inode);
1344
1345                 /* For single writes, FLUSH_STABLE is more efficient */
1346                 if (res == nfsi->npages && nfsi->npages <= server->wpages) {
1347                         if (res > 1 || nfs_list_entry(head.next)->wb_bytes <= server->wsize)
1348                                 how |= FLUSH_STABLE;
1349                 }
1350                 error = nfs_flush_list(&head, server->wpages, how);
1351         }
1352         if (error < 0)
1353                 return error;
1354         return res;
1355 }
1356
1357 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1358 int nfs_commit_inode(struct inode *inode, int how)
1359 {
1360         struct nfs_inode *nfsi = NFS_I(inode);
1361         LIST_HEAD(head);
1362         int                     res,
1363                                 error = 0;
1364
1365         spin_lock(&nfsi->req_lock);
1366         res = nfs_scan_commit(inode, &head, 0, 0);
1367         spin_unlock(&nfsi->req_lock);
1368         if (res) {
1369                 error = nfs_commit_list(inode, &head, how);
1370                 if (error < 0)
1371                         return error;
1372         }
1373         return res;
1374 }
1375 #endif
1376
1377 int nfs_sync_inode(struct inode *inode, unsigned long idx_start,
1378                   unsigned int npages, int how)
1379 {
1380         int nocommit = how & FLUSH_NOCOMMIT;
1381         int wait = how & FLUSH_WAIT;
1382         int error;
1383
1384         how &= ~(FLUSH_WAIT|FLUSH_NOCOMMIT);
1385
1386         do {
1387                 if (wait) {
1388                         error = nfs_wait_on_requests(inode, idx_start, npages);
1389                         if (error != 0)
1390                                 continue;
1391                 }
1392                 error = nfs_flush_inode(inode, idx_start, npages, how);
1393                 if (error != 0)
1394                         continue;
1395                 if (!nocommit)
1396                         error = nfs_commit_inode(inode, how);
1397         } while (error > 0);
1398         return error;
1399 }
1400
1401 int nfs_init_writepagecache(void)
1402 {
1403         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1404                                              sizeof(struct nfs_write_data),
1405                                              0, SLAB_HWCACHE_ALIGN,
1406                                              NULL, NULL);
1407         if (nfs_wdata_cachep == NULL)
1408                 return -ENOMEM;
1409
1410         nfs_wdata_mempool = mempool_create(MIN_POOL_WRITE,
1411                                            mempool_alloc_slab,
1412                                            mempool_free_slab,
1413                                            nfs_wdata_cachep);
1414         if (nfs_wdata_mempool == NULL)
1415                 return -ENOMEM;
1416
1417         nfs_commit_mempool = mempool_create(MIN_POOL_COMMIT,
1418                                            mempool_alloc_slab,
1419                                            mempool_free_slab,
1420                                            nfs_wdata_cachep);
1421         if (nfs_commit_mempool == NULL)
1422                 return -ENOMEM;
1423
1424         return 0;
1425 }
1426
1427 void nfs_destroy_writepagecache(void)
1428 {
1429         mempool_destroy(nfs_commit_mempool);
1430         mempool_destroy(nfs_wdata_mempool);
1431         if (kmem_cache_destroy(nfs_wdata_cachep))
1432                 printk(KERN_INFO "nfs_write_data: not all structures were freed\n");
1433 }
1434