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TOMOYO Linux Cross Reference
Linux/fs/nfs/write.c

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  1 /*
  2  * linux/fs/nfs/write.c
  3  *
  4  * Write file data over NFS.
  5  *
  6  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
  7  */
  8 
  9 #include <linux/types.h>
 10 #include <linux/slab.h>
 11 #include <linux/mm.h>
 12 #include <linux/pagemap.h>
 13 #include <linux/file.h>
 14 #include <linux/writeback.h>
 15 #include <linux/swap.h>
 16 #include <linux/migrate.h>
 17 
 18 #include <linux/sunrpc/clnt.h>
 19 #include <linux/nfs_fs.h>
 20 #include <linux/nfs_mount.h>
 21 #include <linux/nfs_page.h>
 22 #include <linux/backing-dev.h>
 23 #include <linux/export.h>
 24 #include <linux/freezer.h>
 25 #include <linux/wait.h>
 26 #include <linux/iversion.h>
 27 
 28 #include <linux/uaccess.h>
 29 #include <linux/sched/mm.h>
 30 
 31 #include "delegation.h"
 32 #include "internal.h"
 33 #include "iostat.h"
 34 #include "nfs4_fs.h"
 35 #include "fscache.h"
 36 #include "pnfs.h"
 37 
 38 #include "nfstrace.h"
 39 
 40 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
 41 
 42 #define MIN_POOL_WRITE          (32)
 43 #define MIN_POOL_COMMIT         (4)
 44 
 45 struct nfs_io_completion {
 46         void (*complete)(void *data);
 47         void *data;
 48         struct kref refcount;
 49 };
 50 
 51 /*
 52  * Local function declarations
 53  */
 54 static void nfs_redirty_request(struct nfs_page *req);
 55 static const struct rpc_call_ops nfs_commit_ops;
 56 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
 57 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
 58 static const struct nfs_rw_ops nfs_rw_write_ops;
 59 static void nfs_clear_request_commit(struct nfs_page *req);
 60 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 61                                       struct inode *inode);
 62 static struct nfs_page *
 63 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 64                                                 struct page *page);
 65 
 66 static struct kmem_cache *nfs_wdata_cachep;
 67 static mempool_t *nfs_wdata_mempool;
 68 static struct kmem_cache *nfs_cdata_cachep;
 69 static mempool_t *nfs_commit_mempool;
 70 
 71 struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail)
 72 {
 73         struct nfs_commit_data *p;
 74 
 75         if (never_fail)
 76                 p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
 77         else {
 78                 /* It is OK to do some reclaim, not no safe to wait
 79                  * for anything to be returned to the pool.
 80                  * mempool_alloc() cannot handle that particular combination,
 81                  * so we need two separate attempts.
 82                  */
 83                 p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
 84                 if (!p)
 85                         p = kmem_cache_alloc(nfs_cdata_cachep, GFP_NOIO |
 86                                              __GFP_NOWARN | __GFP_NORETRY);
 87                 if (!p)
 88                         return NULL;
 89         }
 90 
 91         memset(p, 0, sizeof(*p));
 92         INIT_LIST_HEAD(&p->pages);
 93         return p;
 94 }
 95 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
 96 
 97 void nfs_commit_free(struct nfs_commit_data *p)
 98 {
 99         mempool_free(p, nfs_commit_mempool);
100 }
101 EXPORT_SYMBOL_GPL(nfs_commit_free);
102 
103 static struct nfs_pgio_header *nfs_writehdr_alloc(void)
104 {
105         struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
106 
107         memset(p, 0, sizeof(*p));
108         p->rw_mode = FMODE_WRITE;
109         return p;
110 }
111 
112 static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
113 {
114         mempool_free(hdr, nfs_wdata_mempool);
115 }
116 
117 static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
118 {
119         return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
120 }
121 
122 static void nfs_io_completion_init(struct nfs_io_completion *ioc,
123                 void (*complete)(void *), void *data)
124 {
125         ioc->complete = complete;
126         ioc->data = data;
127         kref_init(&ioc->refcount);
128 }
129 
130 static void nfs_io_completion_release(struct kref *kref)
131 {
132         struct nfs_io_completion *ioc = container_of(kref,
133                         struct nfs_io_completion, refcount);
134         ioc->complete(ioc->data);
135         kfree(ioc);
136 }
137 
138 static void nfs_io_completion_get(struct nfs_io_completion *ioc)
139 {
140         if (ioc != NULL)
141                 kref_get(&ioc->refcount);
142 }
143 
144 static void nfs_io_completion_put(struct nfs_io_completion *ioc)
145 {
146         if (ioc != NULL)
147                 kref_put(&ioc->refcount, nfs_io_completion_release);
148 }
149 
150 static struct nfs_page *
151 nfs_page_private_request(struct page *page)
152 {
153         if (!PagePrivate(page))
154                 return NULL;
155         return (struct nfs_page *)page_private(page);
156 }
157 
158 /*
159  * nfs_page_find_head_request_locked - find head request associated with @page
160  *
161  * must be called while holding the inode lock.
162  *
163  * returns matching head request with reference held, or NULL if not found.
164  */
165 static struct nfs_page *
166 nfs_page_find_private_request(struct page *page)
167 {
168         struct address_space *mapping = page_file_mapping(page);
169         struct nfs_page *req;
170 
171         if (!PagePrivate(page))
172                 return NULL;
173         spin_lock(&mapping->private_lock);
174         req = nfs_page_private_request(page);
175         if (req) {
176                 WARN_ON_ONCE(req->wb_head != req);
177                 kref_get(&req->wb_kref);
178         }
179         spin_unlock(&mapping->private_lock);
180         return req;
181 }
182 
183 static struct nfs_page *
184 nfs_page_find_swap_request(struct page *page)
185 {
186         struct inode *inode = page_file_mapping(page)->host;
187         struct nfs_inode *nfsi = NFS_I(inode);
188         struct nfs_page *req = NULL;
189         if (!PageSwapCache(page))
190                 return NULL;
191         mutex_lock(&nfsi->commit_mutex);
192         if (PageSwapCache(page)) {
193                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
194                         page);
195                 if (req) {
196                         WARN_ON_ONCE(req->wb_head != req);
197                         kref_get(&req->wb_kref);
198                 }
199         }
200         mutex_unlock(&nfsi->commit_mutex);
201         return req;
202 }
203 
204 /*
205  * nfs_page_find_head_request - find head request associated with @page
206  *
207  * returns matching head request with reference held, or NULL if not found.
208  */
209 static struct nfs_page *nfs_page_find_head_request(struct page *page)
210 {
211         struct nfs_page *req;
212 
213         req = nfs_page_find_private_request(page);
214         if (!req)
215                 req = nfs_page_find_swap_request(page);
216         return req;
217 }
218 
219 /* Adjust the file length if we're writing beyond the end */
220 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
221 {
222         struct inode *inode = page_file_mapping(page)->host;
223         loff_t end, i_size;
224         pgoff_t end_index;
225 
226         spin_lock(&inode->i_lock);
227         i_size = i_size_read(inode);
228         end_index = (i_size - 1) >> PAGE_SHIFT;
229         if (i_size > 0 && page_index(page) < end_index)
230                 goto out;
231         end = page_file_offset(page) + ((loff_t)offset+count);
232         if (i_size >= end)
233                 goto out;
234         i_size_write(inode, end);
235         NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
236         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
237 out:
238         spin_unlock(&inode->i_lock);
239 }
240 
241 /* A writeback failed: mark the page as bad, and invalidate the page cache */
242 static void nfs_set_pageerror(struct address_space *mapping)
243 {
244         nfs_zap_mapping(mapping->host, mapping);
245 }
246 
247 /*
248  * nfs_page_group_search_locked
249  * @head - head request of page group
250  * @page_offset - offset into page
251  *
252  * Search page group with head @head to find a request that contains the
253  * page offset @page_offset.
254  *
255  * Returns a pointer to the first matching nfs request, or NULL if no
256  * match is found.
257  *
258  * Must be called with the page group lock held
259  */
260 static struct nfs_page *
261 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
262 {
263         struct nfs_page *req;
264 
265         req = head;
266         do {
267                 if (page_offset >= req->wb_pgbase &&
268                     page_offset < (req->wb_pgbase + req->wb_bytes))
269                         return req;
270 
271                 req = req->wb_this_page;
272         } while (req != head);
273 
274         return NULL;
275 }
276 
277 /*
278  * nfs_page_group_covers_page
279  * @head - head request of page group
280  *
281  * Return true if the page group with head @head covers the whole page,
282  * returns false otherwise
283  */
284 static bool nfs_page_group_covers_page(struct nfs_page *req)
285 {
286         struct nfs_page *tmp;
287         unsigned int pos = 0;
288         unsigned int len = nfs_page_length(req->wb_page);
289 
290         nfs_page_group_lock(req);
291 
292         for (;;) {
293                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
294                 if (!tmp)
295                         break;
296                 pos = tmp->wb_pgbase + tmp->wb_bytes;
297         }
298 
299         nfs_page_group_unlock(req);
300         return pos >= len;
301 }
302 
303 /* We can set the PG_uptodate flag if we see that a write request
304  * covers the full page.
305  */
306 static void nfs_mark_uptodate(struct nfs_page *req)
307 {
308         if (PageUptodate(req->wb_page))
309                 return;
310         if (!nfs_page_group_covers_page(req))
311                 return;
312         SetPageUptodate(req->wb_page);
313 }
314 
315 static int wb_priority(struct writeback_control *wbc)
316 {
317         int ret = 0;
318 
319         if (wbc->sync_mode == WB_SYNC_ALL)
320                 ret = FLUSH_COND_STABLE;
321         return ret;
322 }
323 
324 /*
325  * NFS congestion control
326  */
327 
328 int nfs_congestion_kb;
329 
330 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
331 #define NFS_CONGESTION_OFF_THRESH       \
332         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
333 
334 static void nfs_set_page_writeback(struct page *page)
335 {
336         struct inode *inode = page_file_mapping(page)->host;
337         struct nfs_server *nfss = NFS_SERVER(inode);
338         int ret = test_set_page_writeback(page);
339 
340         WARN_ON_ONCE(ret != 0);
341 
342         if (atomic_long_inc_return(&nfss->writeback) >
343                         NFS_CONGESTION_ON_THRESH)
344                 set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
345 }
346 
347 static void nfs_end_page_writeback(struct nfs_page *req)
348 {
349         struct inode *inode = page_file_mapping(req->wb_page)->host;
350         struct nfs_server *nfss = NFS_SERVER(inode);
351         bool is_done;
352 
353         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
354         nfs_unlock_request(req);
355         if (!is_done)
356                 return;
357 
358         end_page_writeback(req->wb_page);
359         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
360                 clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
361 }
362 
363 /*
364  * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
365  *
366  * this is a helper function for nfs_lock_and_join_requests
367  *
368  * @inode - inode associated with request page group, must be holding inode lock
369  * @head  - head request of page group, must be holding head lock
370  * @req   - request that couldn't lock and needs to wait on the req bit lock
371  *
372  * NOTE: this must be called holding page_group bit lock
373  *       which will be released before returning.
374  *
375  * returns 0 on success, < 0 on error.
376  */
377 static void
378 nfs_unroll_locks(struct inode *inode, struct nfs_page *head,
379                           struct nfs_page *req)
380 {
381         struct nfs_page *tmp;
382 
383         /* relinquish all the locks successfully grabbed this run */
384         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
385                 if (!kref_read(&tmp->wb_kref))
386                         continue;
387                 nfs_unlock_and_release_request(tmp);
388         }
389 }
390 
391 /*
392  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
393  *
394  * @destroy_list - request list (using wb_this_page) terminated by @old_head
395  * @old_head - the old head of the list
396  *
397  * All subrequests must be locked and removed from all lists, so at this point
398  * they are only "active" in this function, and possibly in nfs_wait_on_request
399  * with a reference held by some other context.
400  */
401 static void
402 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
403                                  struct nfs_page *old_head,
404                                  struct inode *inode)
405 {
406         while (destroy_list) {
407                 struct nfs_page *subreq = destroy_list;
408 
409                 destroy_list = (subreq->wb_this_page == old_head) ?
410                                    NULL : subreq->wb_this_page;
411 
412                 WARN_ON_ONCE(old_head != subreq->wb_head);
413 
414                 /* make sure old group is not used */
415                 subreq->wb_this_page = subreq;
416 
417                 clear_bit(PG_REMOVE, &subreq->wb_flags);
418 
419                 /* Note: races with nfs_page_group_destroy() */
420                 if (!kref_read(&subreq->wb_kref)) {
421                         /* Check if we raced with nfs_page_group_destroy() */
422                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags))
423                                 nfs_free_request(subreq);
424                         continue;
425                 }
426 
427                 subreq->wb_head = subreq;
428 
429                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
430                         nfs_release_request(subreq);
431                         atomic_long_dec(&NFS_I(inode)->nrequests);
432                 }
433 
434                 /* subreq is now totally disconnected from page group or any
435                  * write / commit lists. last chance to wake any waiters */
436                 nfs_unlock_and_release_request(subreq);
437         }
438 }
439 
440 /*
441  * nfs_lock_and_join_requests - join all subreqs to the head req and return
442  *                              a locked reference, cancelling any pending
443  *                              operations for this page.
444  *
445  * @page - the page used to lookup the "page group" of nfs_page structures
446  *
447  * This function joins all sub requests to the head request by first
448  * locking all requests in the group, cancelling any pending operations
449  * and finally updating the head request to cover the whole range covered by
450  * the (former) group.  All subrequests are removed from any write or commit
451  * lists, unlinked from the group and destroyed.
452  *
453  * Returns a locked, referenced pointer to the head request - which after
454  * this call is guaranteed to be the only request associated with the page.
455  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
456  * error was encountered.
457  */
458 static struct nfs_page *
459 nfs_lock_and_join_requests(struct page *page)
460 {
461         struct inode *inode = page_file_mapping(page)->host;
462         struct nfs_page *head, *subreq;
463         struct nfs_page *destroy_list = NULL;
464         unsigned int total_bytes;
465         int ret;
466 
467 try_again:
468         /*
469          * A reference is taken only on the head request which acts as a
470          * reference to the whole page group - the group will not be destroyed
471          * until the head reference is released.
472          */
473         head = nfs_page_find_head_request(page);
474         if (!head)
475                 return NULL;
476 
477         /* lock the page head first in order to avoid an ABBA inefficiency */
478         if (!nfs_lock_request(head)) {
479                 ret = nfs_wait_on_request(head);
480                 nfs_release_request(head);
481                 if (ret < 0)
482                         return ERR_PTR(ret);
483                 goto try_again;
484         }
485 
486         /* Ensure that nobody removed the request before we locked it */
487         if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
488                 nfs_unlock_and_release_request(head);
489                 goto try_again;
490         }
491 
492         ret = nfs_page_group_lock(head);
493         if (ret < 0)
494                 goto release_request;
495 
496         /* lock each request in the page group */
497         total_bytes = head->wb_bytes;
498         for (subreq = head->wb_this_page; subreq != head;
499                         subreq = subreq->wb_this_page) {
500 
501                 if (!kref_get_unless_zero(&subreq->wb_kref)) {
502                         if (subreq->wb_offset == head->wb_offset + total_bytes)
503                                 total_bytes += subreq->wb_bytes;
504                         continue;
505                 }
506 
507                 while (!nfs_lock_request(subreq)) {
508                         /*
509                          * Unlock page to allow nfs_page_group_sync_on_bit()
510                          * to succeed
511                          */
512                         nfs_page_group_unlock(head);
513                         ret = nfs_wait_on_request(subreq);
514                         if (!ret)
515                                 ret = nfs_page_group_lock(head);
516                         if (ret < 0) {
517                                 nfs_unroll_locks(inode, head, subreq);
518                                 nfs_release_request(subreq);
519                                 goto release_request;
520                         }
521                 }
522                 /*
523                  * Subrequests are always contiguous, non overlapping
524                  * and in order - but may be repeated (mirrored writes).
525                  */
526                 if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
527                         /* keep track of how many bytes this group covers */
528                         total_bytes += subreq->wb_bytes;
529                 } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
530                             ((subreq->wb_offset + subreq->wb_bytes) >
531                              (head->wb_offset + total_bytes)))) {
532                         nfs_page_group_unlock(head);
533                         nfs_unroll_locks(inode, head, subreq);
534                         nfs_unlock_and_release_request(subreq);
535                         ret = -EIO;
536                         goto release_request;
537                 }
538         }
539 
540         /* Now that all requests are locked, make sure they aren't on any list.
541          * Commit list removal accounting is done after locks are dropped */
542         subreq = head;
543         do {
544                 nfs_clear_request_commit(subreq);
545                 subreq = subreq->wb_this_page;
546         } while (subreq != head);
547 
548         /* unlink subrequests from head, destroy them later */
549         if (head->wb_this_page != head) {
550                 /* destroy list will be terminated by head */
551                 destroy_list = head->wb_this_page;
552                 head->wb_this_page = head;
553 
554                 /* change head request to cover whole range that
555                  * the former page group covered */
556                 head->wb_bytes = total_bytes;
557         }
558 
559         /* Postpone destruction of this request */
560         if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
561                 set_bit(PG_INODE_REF, &head->wb_flags);
562                 kref_get(&head->wb_kref);
563                 atomic_long_inc(&NFS_I(inode)->nrequests);
564         }
565 
566         nfs_page_group_unlock(head);
567 
568         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
569 
570         /* Did we lose a race with nfs_inode_remove_request()? */
571         if (!(PagePrivate(page) || PageSwapCache(page))) {
572                 nfs_unlock_and_release_request(head);
573                 return NULL;
574         }
575 
576         /* still holds ref on head from nfs_page_find_head_request
577          * and still has lock on head from lock loop */
578         return head;
579 
580 release_request:
581         nfs_unlock_and_release_request(head);
582         return ERR_PTR(ret);
583 }
584 
585 static void nfs_write_error_remove_page(struct nfs_page *req)
586 {
587         nfs_end_page_writeback(req);
588         generic_error_remove_page(page_file_mapping(req->wb_page),
589                                   req->wb_page);
590         nfs_release_request(req);
591 }
592 
593 static bool
594 nfs_error_is_fatal_on_server(int err)
595 {
596         switch (err) {
597         case 0:
598         case -ERESTARTSYS:
599         case -EINTR:
600                 return false;
601         }
602         return nfs_error_is_fatal(err);
603 }
604 
605 /*
606  * Find an associated nfs write request, and prepare to flush it out
607  * May return an error if the user signalled nfs_wait_on_request().
608  */
609 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
610                                 struct page *page)
611 {
612         struct nfs_page *req;
613         int ret = 0;
614 
615         req = nfs_lock_and_join_requests(page);
616         if (!req)
617                 goto out;
618         ret = PTR_ERR(req);
619         if (IS_ERR(req))
620                 goto out;
621 
622         nfs_set_page_writeback(page);
623         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
624 
625         ret = req->wb_context->error;
626         /* If there is a fatal error that covers this write, just exit */
627         if (nfs_error_is_fatal_on_server(ret))
628                 goto out_launder;
629 
630         ret = 0;
631         if (!nfs_pageio_add_request(pgio, req)) {
632                 ret = pgio->pg_error;
633                 /*
634                  * Remove the problematic req upon fatal errors on the server
635                  */
636                 if (nfs_error_is_fatal(ret)) {
637                         nfs_context_set_write_error(req->wb_context, ret);
638                         if (nfs_error_is_fatal_on_server(ret))
639                                 goto out_launder;
640                 } else
641                         ret = -EAGAIN;
642                 nfs_redirty_request(req);
643         } else
644                 nfs_add_stats(page_file_mapping(page)->host,
645                                 NFSIOS_WRITEPAGES, 1);
646 out:
647         return ret;
648 out_launder:
649         nfs_write_error_remove_page(req);
650         return ret;
651 }
652 
653 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
654                             struct nfs_pageio_descriptor *pgio)
655 {
656         int ret;
657 
658         nfs_pageio_cond_complete(pgio, page_index(page));
659         ret = nfs_page_async_flush(pgio, page);
660         if (ret == -EAGAIN) {
661                 redirty_page_for_writepage(wbc, page);
662                 ret = 0;
663         }
664         return ret;
665 }
666 
667 /*
668  * Write an mmapped page to the server.
669  */
670 static int nfs_writepage_locked(struct page *page,
671                                 struct writeback_control *wbc)
672 {
673         struct nfs_pageio_descriptor pgio;
674         struct inode *inode = page_file_mapping(page)->host;
675         int err;
676 
677         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
678         nfs_pageio_init_write(&pgio, inode, 0,
679                                 false, &nfs_async_write_completion_ops);
680         err = nfs_do_writepage(page, wbc, &pgio);
681         nfs_pageio_complete(&pgio);
682         if (err < 0)
683                 return err;
684         if (pgio.pg_error < 0)
685                 return pgio.pg_error;
686         return 0;
687 }
688 
689 int nfs_writepage(struct page *page, struct writeback_control *wbc)
690 {
691         int ret;
692 
693         ret = nfs_writepage_locked(page, wbc);
694         unlock_page(page);
695         return ret;
696 }
697 
698 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
699 {
700         int ret;
701 
702         ret = nfs_do_writepage(page, wbc, data);
703         unlock_page(page);
704         return ret;
705 }
706 
707 static void nfs_io_completion_commit(void *inode)
708 {
709         nfs_commit_inode(inode, 0);
710 }
711 
712 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
713 {
714         struct inode *inode = mapping->host;
715         struct nfs_pageio_descriptor pgio;
716         struct nfs_io_completion *ioc;
717         unsigned int pflags = memalloc_nofs_save();
718         int err;
719 
720         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
721 
722         ioc = nfs_io_completion_alloc(GFP_NOFS);
723         if (ioc)
724                 nfs_io_completion_init(ioc, nfs_io_completion_commit, inode);
725 
726         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
727                                 &nfs_async_write_completion_ops);
728         pgio.pg_io_completion = ioc;
729         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
730         nfs_pageio_complete(&pgio);
731         nfs_io_completion_put(ioc);
732 
733         memalloc_nofs_restore(pflags);
734 
735         if (err < 0)
736                 goto out_err;
737         err = pgio.pg_error;
738         if (err < 0)
739                 goto out_err;
740         return 0;
741 out_err:
742         return err;
743 }
744 
745 /*
746  * Insert a write request into an inode
747  */
748 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
749 {
750         struct address_space *mapping = page_file_mapping(req->wb_page);
751         struct nfs_inode *nfsi = NFS_I(inode);
752 
753         WARN_ON_ONCE(req->wb_this_page != req);
754 
755         /* Lock the request! */
756         nfs_lock_request(req);
757 
758         /*
759          * Swap-space should not get truncated. Hence no need to plug the race
760          * with invalidate/truncate.
761          */
762         spin_lock(&mapping->private_lock);
763         if (!nfs_have_writebacks(inode) &&
764             NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
765                 inode_inc_iversion_raw(inode);
766         if (likely(!PageSwapCache(req->wb_page))) {
767                 set_bit(PG_MAPPED, &req->wb_flags);
768                 SetPagePrivate(req->wb_page);
769                 set_page_private(req->wb_page, (unsigned long)req);
770         }
771         spin_unlock(&mapping->private_lock);
772         atomic_long_inc(&nfsi->nrequests);
773         /* this a head request for a page group - mark it as having an
774          * extra reference so sub groups can follow suit.
775          * This flag also informs pgio layer when to bump nrequests when
776          * adding subrequests. */
777         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
778         kref_get(&req->wb_kref);
779 }
780 
781 /*
782  * Remove a write request from an inode
783  */
784 static void nfs_inode_remove_request(struct nfs_page *req)
785 {
786         struct address_space *mapping = page_file_mapping(req->wb_page);
787         struct inode *inode = mapping->host;
788         struct nfs_inode *nfsi = NFS_I(inode);
789         struct nfs_page *head;
790 
791         atomic_long_dec(&nfsi->nrequests);
792         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
793                 head = req->wb_head;
794 
795                 spin_lock(&mapping->private_lock);
796                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
797                         set_page_private(head->wb_page, 0);
798                         ClearPagePrivate(head->wb_page);
799                         clear_bit(PG_MAPPED, &head->wb_flags);
800                 }
801                 spin_unlock(&mapping->private_lock);
802         }
803 
804         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
805                 nfs_release_request(req);
806 }
807 
808 static void
809 nfs_mark_request_dirty(struct nfs_page *req)
810 {
811         if (req->wb_page)
812                 __set_page_dirty_nobuffers(req->wb_page);
813 }
814 
815 /*
816  * nfs_page_search_commits_for_head_request_locked
817  *
818  * Search through commit lists on @inode for the head request for @page.
819  * Must be called while holding the inode (which is cinfo) lock.
820  *
821  * Returns the head request if found, or NULL if not found.
822  */
823 static struct nfs_page *
824 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
825                                                 struct page *page)
826 {
827         struct nfs_page *freq, *t;
828         struct nfs_commit_info cinfo;
829         struct inode *inode = &nfsi->vfs_inode;
830 
831         nfs_init_cinfo_from_inode(&cinfo, inode);
832 
833         /* search through pnfs commit lists */
834         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
835         if (freq)
836                 return freq->wb_head;
837 
838         /* Linearly search the commit list for the correct request */
839         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
840                 if (freq->wb_page == page)
841                         return freq->wb_head;
842         }
843 
844         return NULL;
845 }
846 
847 /**
848  * nfs_request_add_commit_list_locked - add request to a commit list
849  * @req: pointer to a struct nfs_page
850  * @dst: commit list head
851  * @cinfo: holds list lock and accounting info
852  *
853  * This sets the PG_CLEAN bit, updates the cinfo count of
854  * number of outstanding requests requiring a commit as well as
855  * the MM page stats.
856  *
857  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
858  * nfs_page lock.
859  */
860 void
861 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
862                             struct nfs_commit_info *cinfo)
863 {
864         set_bit(PG_CLEAN, &req->wb_flags);
865         nfs_list_add_request(req, dst);
866         atomic_long_inc(&cinfo->mds->ncommit);
867 }
868 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
869 
870 /**
871  * nfs_request_add_commit_list - add request to a commit list
872  * @req: pointer to a struct nfs_page
873  * @cinfo: holds list lock and accounting info
874  *
875  * This sets the PG_CLEAN bit, updates the cinfo count of
876  * number of outstanding requests requiring a commit as well as
877  * the MM page stats.
878  *
879  * The caller must _not_ hold the cinfo->lock, but must be
880  * holding the nfs_page lock.
881  */
882 void
883 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
884 {
885         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
886         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
887         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
888         if (req->wb_page)
889                 nfs_mark_page_unstable(req->wb_page, cinfo);
890 }
891 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
892 
893 /**
894  * nfs_request_remove_commit_list - Remove request from a commit list
895  * @req: pointer to a nfs_page
896  * @cinfo: holds list lock and accounting info
897  *
898  * This clears the PG_CLEAN bit, and updates the cinfo's count of
899  * number of outstanding requests requiring a commit
900  * It does not update the MM page stats.
901  *
902  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
903  */
904 void
905 nfs_request_remove_commit_list(struct nfs_page *req,
906                                struct nfs_commit_info *cinfo)
907 {
908         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
909                 return;
910         nfs_list_remove_request(req);
911         atomic_long_dec(&cinfo->mds->ncommit);
912 }
913 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
914 
915 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
916                                       struct inode *inode)
917 {
918         cinfo->inode = inode;
919         cinfo->mds = &NFS_I(inode)->commit_info;
920         cinfo->ds = pnfs_get_ds_info(inode);
921         cinfo->dreq = NULL;
922         cinfo->completion_ops = &nfs_commit_completion_ops;
923 }
924 
925 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
926                     struct inode *inode,
927                     struct nfs_direct_req *dreq)
928 {
929         if (dreq)
930                 nfs_init_cinfo_from_dreq(cinfo, dreq);
931         else
932                 nfs_init_cinfo_from_inode(cinfo, inode);
933 }
934 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
935 
936 /*
937  * Add a request to the inode's commit list.
938  */
939 void
940 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
941                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
942 {
943         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
944                 return;
945         nfs_request_add_commit_list(req, cinfo);
946 }
947 
948 static void
949 nfs_clear_page_commit(struct page *page)
950 {
951         dec_node_page_state(page, NR_UNSTABLE_NFS);
952         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
953                     WB_RECLAIMABLE);
954 }
955 
956 /* Called holding the request lock on @req */
957 static void
958 nfs_clear_request_commit(struct nfs_page *req)
959 {
960         if (test_bit(PG_CLEAN, &req->wb_flags)) {
961                 struct inode *inode = d_inode(req->wb_context->dentry);
962                 struct nfs_commit_info cinfo;
963 
964                 nfs_init_cinfo_from_inode(&cinfo, inode);
965                 mutex_lock(&NFS_I(inode)->commit_mutex);
966                 if (!pnfs_clear_request_commit(req, &cinfo)) {
967                         nfs_request_remove_commit_list(req, &cinfo);
968                 }
969                 mutex_unlock(&NFS_I(inode)->commit_mutex);
970                 nfs_clear_page_commit(req->wb_page);
971         }
972 }
973 
974 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
975 {
976         if (hdr->verf.committed == NFS_DATA_SYNC)
977                 return hdr->lseg == NULL;
978         return hdr->verf.committed != NFS_FILE_SYNC;
979 }
980 
981 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
982 {
983         nfs_io_completion_get(hdr->io_completion);
984 }
985 
986 static void nfs_write_completion(struct nfs_pgio_header *hdr)
987 {
988         struct nfs_commit_info cinfo;
989         unsigned long bytes = 0;
990 
991         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
992                 goto out;
993         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
994         while (!list_empty(&hdr->pages)) {
995                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
996 
997                 bytes += req->wb_bytes;
998                 nfs_list_remove_request(req);
999                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1000                     (hdr->good_bytes < bytes)) {
1001                         nfs_set_pageerror(page_file_mapping(req->wb_page));
1002                         nfs_context_set_write_error(req->wb_context, hdr->error);
1003                         goto remove_req;
1004                 }
1005                 if (nfs_write_need_commit(hdr)) {
1006                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1007                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1008                                 hdr->pgio_mirror_idx);
1009                         goto next;
1010                 }
1011 remove_req:
1012                 nfs_inode_remove_request(req);
1013 next:
1014                 nfs_end_page_writeback(req);
1015                 nfs_release_request(req);
1016         }
1017 out:
1018         nfs_io_completion_put(hdr->io_completion);
1019         hdr->release(hdr);
1020 }
1021 
1022 unsigned long
1023 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1024 {
1025         return atomic_long_read(&cinfo->mds->ncommit);
1026 }
1027 
1028 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1029 int
1030 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1031                      struct nfs_commit_info *cinfo, int max)
1032 {
1033         struct nfs_page *req, *tmp;
1034         int ret = 0;
1035 
1036 restart:
1037         list_for_each_entry_safe(req, tmp, src, wb_list) {
1038                 kref_get(&req->wb_kref);
1039                 if (!nfs_lock_request(req)) {
1040                         int status;
1041 
1042                         /* Prevent deadlock with nfs_lock_and_join_requests */
1043                         if (!list_empty(dst)) {
1044                                 nfs_release_request(req);
1045                                 continue;
1046                         }
1047                         /* Ensure we make progress to prevent livelock */
1048                         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1049                         status = nfs_wait_on_request(req);
1050                         nfs_release_request(req);
1051                         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1052                         if (status < 0)
1053                                 break;
1054                         goto restart;
1055                 }
1056                 nfs_request_remove_commit_list(req, cinfo);
1057                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1058                 nfs_list_add_request(req, dst);
1059                 ret++;
1060                 if ((ret == max) && !cinfo->dreq)
1061                         break;
1062                 cond_resched();
1063         }
1064         return ret;
1065 }
1066 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1067 
1068 /*
1069  * nfs_scan_commit - Scan an inode for commit requests
1070  * @inode: NFS inode to scan
1071  * @dst: mds destination list
1072  * @cinfo: mds and ds lists of reqs ready to commit
1073  *
1074  * Moves requests from the inode's 'commit' request list.
1075  * The requests are *not* checked to ensure that they form a contiguous set.
1076  */
1077 int
1078 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1079                 struct nfs_commit_info *cinfo)
1080 {
1081         int ret = 0;
1082 
1083         if (!atomic_long_read(&cinfo->mds->ncommit))
1084                 return 0;
1085         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1086         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1087                 const int max = INT_MAX;
1088 
1089                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1090                                            cinfo, max);
1091                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1092         }
1093         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1094         return ret;
1095 }
1096 
1097 /*
1098  * Search for an existing write request, and attempt to update
1099  * it to reflect a new dirty region on a given page.
1100  *
1101  * If the attempt fails, then the existing request is flushed out
1102  * to disk.
1103  */
1104 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1105                 struct page *page,
1106                 unsigned int offset,
1107                 unsigned int bytes)
1108 {
1109         struct nfs_page *req;
1110         unsigned int rqend;
1111         unsigned int end;
1112         int error;
1113 
1114         end = offset + bytes;
1115 
1116         req = nfs_lock_and_join_requests(page);
1117         if (IS_ERR_OR_NULL(req))
1118                 return req;
1119 
1120         rqend = req->wb_offset + req->wb_bytes;
1121         /*
1122          * Tell the caller to flush out the request if
1123          * the offsets are non-contiguous.
1124          * Note: nfs_flush_incompatible() will already
1125          * have flushed out requests having wrong owners.
1126          */
1127         if (offset > rqend || end < req->wb_offset)
1128                 goto out_flushme;
1129 
1130         /* Okay, the request matches. Update the region */
1131         if (offset < req->wb_offset) {
1132                 req->wb_offset = offset;
1133                 req->wb_pgbase = offset;
1134         }
1135         if (end > rqend)
1136                 req->wb_bytes = end - req->wb_offset;
1137         else
1138                 req->wb_bytes = rqend - req->wb_offset;
1139         return req;
1140 out_flushme:
1141         /*
1142          * Note: we mark the request dirty here because
1143          * nfs_lock_and_join_requests() cannot preserve
1144          * commit flags, so we have to replay the write.
1145          */
1146         nfs_mark_request_dirty(req);
1147         nfs_unlock_and_release_request(req);
1148         error = nfs_wb_page(inode, page);
1149         return (error < 0) ? ERR_PTR(error) : NULL;
1150 }
1151 
1152 /*
1153  * Try to update an existing write request, or create one if there is none.
1154  *
1155  * Note: Should always be called with the Page Lock held to prevent races
1156  * if we have to add a new request. Also assumes that the caller has
1157  * already called nfs_flush_incompatible() if necessary.
1158  */
1159 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1160                 struct page *page, unsigned int offset, unsigned int bytes)
1161 {
1162         struct inode *inode = page_file_mapping(page)->host;
1163         struct nfs_page *req;
1164 
1165         req = nfs_try_to_update_request(inode, page, offset, bytes);
1166         if (req != NULL)
1167                 goto out;
1168         req = nfs_create_request(ctx, page, NULL, offset, bytes);
1169         if (IS_ERR(req))
1170                 goto out;
1171         nfs_inode_add_request(inode, req);
1172 out:
1173         return req;
1174 }
1175 
1176 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1177                 unsigned int offset, unsigned int count)
1178 {
1179         struct nfs_page *req;
1180 
1181         req = nfs_setup_write_request(ctx, page, offset, count);
1182         if (IS_ERR(req))
1183                 return PTR_ERR(req);
1184         /* Update file length */
1185         nfs_grow_file(page, offset, count);
1186         nfs_mark_uptodate(req);
1187         nfs_mark_request_dirty(req);
1188         nfs_unlock_and_release_request(req);
1189         return 0;
1190 }
1191 
1192 int nfs_flush_incompatible(struct file *file, struct page *page)
1193 {
1194         struct nfs_open_context *ctx = nfs_file_open_context(file);
1195         struct nfs_lock_context *l_ctx;
1196         struct file_lock_context *flctx = file_inode(file)->i_flctx;
1197         struct nfs_page *req;
1198         int do_flush, status;
1199         /*
1200          * Look for a request corresponding to this page. If there
1201          * is one, and it belongs to another file, we flush it out
1202          * before we try to copy anything into the page. Do this
1203          * due to the lack of an ACCESS-type call in NFSv2.
1204          * Also do the same if we find a request from an existing
1205          * dropped page.
1206          */
1207         do {
1208                 req = nfs_page_find_head_request(page);
1209                 if (req == NULL)
1210                         return 0;
1211                 l_ctx = req->wb_lock_context;
1212                 do_flush = req->wb_page != page ||
1213                         !nfs_match_open_context(req->wb_context, ctx);
1214                 if (l_ctx && flctx &&
1215                     !(list_empty_careful(&flctx->flc_posix) &&
1216                       list_empty_careful(&flctx->flc_flock))) {
1217                         do_flush |= l_ctx->lockowner != current->files;
1218                 }
1219                 nfs_release_request(req);
1220                 if (!do_flush)
1221                         return 0;
1222                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1223         } while (status == 0);
1224         return status;
1225 }
1226 
1227 /*
1228  * Avoid buffered writes when a open context credential's key would
1229  * expire soon.
1230  *
1231  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1232  *
1233  * Return 0 and set a credential flag which triggers the inode to flush
1234  * and performs  NFS_FILE_SYNC writes if the key will expired within
1235  * RPC_KEY_EXPIRE_TIMEO.
1236  */
1237 int
1238 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1239 {
1240         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1241 
1242         if (nfs_ctx_key_to_expire(ctx, inode) &&
1243             !ctx->ll_cred)
1244                 /* Already expired! */
1245                 return -EACCES;
1246         return 0;
1247 }
1248 
1249 /*
1250  * Test if the open context credential key is marked to expire soon.
1251  */
1252 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1253 {
1254         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1255         struct rpc_cred *cred = ctx->ll_cred;
1256         struct auth_cred acred = {
1257                 .cred = ctx->cred,
1258         };
1259 
1260         if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) {
1261                 put_rpccred(cred);
1262                 ctx->ll_cred = NULL;
1263                 cred = NULL;
1264         }
1265         if (!cred)
1266                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
1267         if (!cred || IS_ERR(cred))
1268                 return true;
1269         ctx->ll_cred = cred;
1270         return !!(cred->cr_ops->crkey_timeout &&
1271                   cred->cr_ops->crkey_timeout(cred));
1272 }
1273 
1274 /*
1275  * If the page cache is marked as unsafe or invalid, then we can't rely on
1276  * the PageUptodate() flag. In this case, we will need to turn off
1277  * write optimisations that depend on the page contents being correct.
1278  */
1279 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
1280 {
1281         struct nfs_inode *nfsi = NFS_I(inode);
1282 
1283         if (nfs_have_delegated_attributes(inode))
1284                 goto out;
1285         if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
1286                 return false;
1287         smp_rmb();
1288         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
1289                 return false;
1290 out:
1291         if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
1292                 return false;
1293         return PageUptodate(page) != 0;
1294 }
1295 
1296 static bool
1297 is_whole_file_wrlock(struct file_lock *fl)
1298 {
1299         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1300                         fl->fl_type == F_WRLCK;
1301 }
1302 
1303 /* If we know the page is up to date, and we're not using byte range locks (or
1304  * if we have the whole file locked for writing), it may be more efficient to
1305  * extend the write to cover the entire page in order to avoid fragmentation
1306  * inefficiencies.
1307  *
1308  * If the file is opened for synchronous writes then we can just skip the rest
1309  * of the checks.
1310  */
1311 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
1312 {
1313         int ret;
1314         struct file_lock_context *flctx = inode->i_flctx;
1315         struct file_lock *fl;
1316 
1317         if (file->f_flags & O_DSYNC)
1318                 return 0;
1319         if (!nfs_write_pageuptodate(page, inode))
1320                 return 0;
1321         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1322                 return 1;
1323         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1324                        list_empty_careful(&flctx->flc_posix)))
1325                 return 1;
1326 
1327         /* Check to see if there are whole file write locks */
1328         ret = 0;
1329         spin_lock(&flctx->flc_lock);
1330         if (!list_empty(&flctx->flc_posix)) {
1331                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1332                                         fl_list);
1333                 if (is_whole_file_wrlock(fl))
1334                         ret = 1;
1335         } else if (!list_empty(&flctx->flc_flock)) {
1336                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1337                                         fl_list);
1338                 if (fl->fl_type == F_WRLCK)
1339                         ret = 1;
1340         }
1341         spin_unlock(&flctx->flc_lock);
1342         return ret;
1343 }
1344 
1345 /*
1346  * Update and possibly write a cached page of an NFS file.
1347  *
1348  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1349  * things with a page scheduled for an RPC call (e.g. invalidate it).
1350  */
1351 int nfs_updatepage(struct file *file, struct page *page,
1352                 unsigned int offset, unsigned int count)
1353 {
1354         struct nfs_open_context *ctx = nfs_file_open_context(file);
1355         struct address_space *mapping = page_file_mapping(page);
1356         struct inode    *inode = mapping->host;
1357         int             status = 0;
1358 
1359         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1360 
1361         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1362                 file, count, (long long)(page_file_offset(page) + offset));
1363 
1364         if (!count)
1365                 goto out;
1366 
1367         if (nfs_can_extend_write(file, page, inode)) {
1368                 count = max(count + offset, nfs_page_length(page));
1369                 offset = 0;
1370         }
1371 
1372         status = nfs_writepage_setup(ctx, page, offset, count);
1373         if (status < 0)
1374                 nfs_set_pageerror(mapping);
1375         else
1376                 __set_page_dirty_nobuffers(page);
1377 out:
1378         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1379                         status, (long long)i_size_read(inode));
1380         return status;
1381 }
1382 
1383 static int flush_task_priority(int how)
1384 {
1385         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1386                 case FLUSH_HIGHPRI:
1387                         return RPC_PRIORITY_HIGH;
1388                 case FLUSH_LOWPRI:
1389                         return RPC_PRIORITY_LOW;
1390         }
1391         return RPC_PRIORITY_NORMAL;
1392 }
1393 
1394 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1395                                struct rpc_message *msg,
1396                                const struct nfs_rpc_ops *rpc_ops,
1397                                struct rpc_task_setup *task_setup_data, int how)
1398 {
1399         int priority = flush_task_priority(how);
1400 
1401         task_setup_data->priority = priority;
1402         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1403         trace_nfs_initiate_write(hdr->inode, hdr->io_start, hdr->good_bytes,
1404                                  hdr->args.stable);
1405 }
1406 
1407 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1408  * call this on each, which will prepare them to be retried on next
1409  * writeback using standard nfs.
1410  */
1411 static void nfs_redirty_request(struct nfs_page *req)
1412 {
1413         nfs_mark_request_dirty(req);
1414         set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1415         nfs_end_page_writeback(req);
1416         nfs_release_request(req);
1417 }
1418 
1419 static void nfs_async_write_error(struct list_head *head, int error)
1420 {
1421         struct nfs_page *req;
1422 
1423         while (!list_empty(head)) {
1424                 req = nfs_list_entry(head->next);
1425                 nfs_list_remove_request(req);
1426                 if (nfs_error_is_fatal(error)) {
1427                         nfs_context_set_write_error(req->wb_context, error);
1428                         if (nfs_error_is_fatal_on_server(error)) {
1429                                 nfs_write_error_remove_page(req);
1430                                 continue;
1431                         }
1432                 }
1433                 nfs_redirty_request(req);
1434         }
1435 }
1436 
1437 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1438 {
1439         nfs_async_write_error(&hdr->pages, 0);
1440         filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1441                         hdr->args.offset + hdr->args.count - 1);
1442 }
1443 
1444 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1445         .init_hdr = nfs_async_write_init,
1446         .error_cleanup = nfs_async_write_error,
1447         .completion = nfs_write_completion,
1448         .reschedule_io = nfs_async_write_reschedule_io,
1449 };
1450 
1451 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1452                                struct inode *inode, int ioflags, bool force_mds,
1453                                const struct nfs_pgio_completion_ops *compl_ops)
1454 {
1455         struct nfs_server *server = NFS_SERVER(inode);
1456         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1457 
1458 #ifdef CONFIG_NFS_V4_1
1459         if (server->pnfs_curr_ld && !force_mds)
1460                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1461 #endif
1462         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1463                         server->wsize, ioflags);
1464 }
1465 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1466 
1467 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1468 {
1469         struct nfs_pgio_mirror *mirror;
1470 
1471         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1472                 pgio->pg_ops->pg_cleanup(pgio);
1473 
1474         pgio->pg_ops = &nfs_pgio_rw_ops;
1475 
1476         nfs_pageio_stop_mirroring(pgio);
1477 
1478         mirror = &pgio->pg_mirrors[0];
1479         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1480 }
1481 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1482 
1483 
1484 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1485 {
1486         struct nfs_commit_data *data = calldata;
1487 
1488         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1489 }
1490 
1491 /*
1492  * Special version of should_remove_suid() that ignores capabilities.
1493  */
1494 static int nfs_should_remove_suid(const struct inode *inode)
1495 {
1496         umode_t mode = inode->i_mode;
1497         int kill = 0;
1498 
1499         /* suid always must be killed */
1500         if (unlikely(mode & S_ISUID))
1501                 kill = ATTR_KILL_SUID;
1502 
1503         /*
1504          * sgid without any exec bits is just a mandatory locking mark; leave
1505          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1506          */
1507         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1508                 kill |= ATTR_KILL_SGID;
1509 
1510         if (unlikely(kill && S_ISREG(mode)))
1511                 return kill;
1512 
1513         return 0;
1514 }
1515 
1516 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1517                 struct nfs_fattr *fattr)
1518 {
1519         struct nfs_pgio_args *argp = &hdr->args;
1520         struct nfs_pgio_res *resp = &hdr->res;
1521         u64 size = argp->offset + resp->count;
1522 
1523         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1524                 fattr->size = size;
1525         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1526                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1527                 return;
1528         }
1529         if (size != fattr->size)
1530                 return;
1531         /* Set attribute barrier */
1532         nfs_fattr_set_barrier(fattr);
1533         /* ...and update size */
1534         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1535 }
1536 
1537 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1538 {
1539         struct nfs_fattr *fattr = &hdr->fattr;
1540         struct inode *inode = hdr->inode;
1541 
1542         spin_lock(&inode->i_lock);
1543         nfs_writeback_check_extend(hdr, fattr);
1544         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1545         spin_unlock(&inode->i_lock);
1546 }
1547 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1548 
1549 /*
1550  * This function is called when the WRITE call is complete.
1551  */
1552 static int nfs_writeback_done(struct rpc_task *task,
1553                               struct nfs_pgio_header *hdr,
1554                               struct inode *inode)
1555 {
1556         int status;
1557 
1558         /*
1559          * ->write_done will attempt to use post-op attributes to detect
1560          * conflicting writes by other clients.  A strict interpretation
1561          * of close-to-open would allow us to continue caching even if
1562          * another writer had changed the file, but some applications
1563          * depend on tighter cache coherency when writing.
1564          */
1565         status = NFS_PROTO(inode)->write_done(task, hdr);
1566         if (status != 0)
1567                 return status;
1568 
1569         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1570         trace_nfs_writeback_done(inode, task->tk_status,
1571                                  hdr->args.offset, hdr->res.verf);
1572 
1573         if (hdr->res.verf->committed < hdr->args.stable &&
1574             task->tk_status >= 0) {
1575                 /* We tried a write call, but the server did not
1576                  * commit data to stable storage even though we
1577                  * requested it.
1578                  * Note: There is a known bug in Tru64 < 5.0 in which
1579                  *       the server reports NFS_DATA_SYNC, but performs
1580                  *       NFS_FILE_SYNC. We therefore implement this checking
1581                  *       as a dprintk() in order to avoid filling syslog.
1582                  */
1583                 static unsigned long    complain;
1584 
1585                 /* Note this will print the MDS for a DS write */
1586                 if (time_before(complain, jiffies)) {
1587                         dprintk("NFS:       faulty NFS server %s:"
1588                                 " (committed = %d) != (stable = %d)\n",
1589                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1590                                 hdr->res.verf->committed, hdr->args.stable);
1591                         complain = jiffies + 300 * HZ;
1592                 }
1593         }
1594 
1595         /* Deal with the suid/sgid bit corner case */
1596         if (nfs_should_remove_suid(inode)) {
1597                 spin_lock(&inode->i_lock);
1598                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_OTHER;
1599                 spin_unlock(&inode->i_lock);
1600         }
1601         return 0;
1602 }
1603 
1604 /*
1605  * This function is called when the WRITE call is complete.
1606  */
1607 static void nfs_writeback_result(struct rpc_task *task,
1608                                  struct nfs_pgio_header *hdr)
1609 {
1610         struct nfs_pgio_args    *argp = &hdr->args;
1611         struct nfs_pgio_res     *resp = &hdr->res;
1612 
1613         if (resp->count < argp->count) {
1614                 static unsigned long    complain;
1615 
1616                 /* This a short write! */
1617                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1618 
1619                 /* Has the server at least made some progress? */
1620                 if (resp->count == 0) {
1621                         if (time_before(complain, jiffies)) {
1622                                 printk(KERN_WARNING
1623                                        "NFS: Server wrote zero bytes, expected %u.\n",
1624                                        argp->count);
1625                                 complain = jiffies + 300 * HZ;
1626                         }
1627                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1628                         task->tk_status = -EIO;
1629                         return;
1630                 }
1631 
1632                 /* For non rpc-based layout drivers, retry-through-MDS */
1633                 if (!task->tk_ops) {
1634                         hdr->pnfs_error = -EAGAIN;
1635                         return;
1636                 }
1637 
1638                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1639                 if (resp->verf->committed != NFS_UNSTABLE) {
1640                         /* Resend from where the server left off */
1641                         hdr->mds_offset += resp->count;
1642                         argp->offset += resp->count;
1643                         argp->pgbase += resp->count;
1644                         argp->count -= resp->count;
1645                 } else {
1646                         /* Resend as a stable write in order to avoid
1647                          * headaches in the case of a server crash.
1648                          */
1649                         argp->stable = NFS_FILE_SYNC;
1650                 }
1651                 rpc_restart_call_prepare(task);
1652         }
1653 }
1654 
1655 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1656 {
1657         return wait_var_event_killable(&cinfo->rpcs_out,
1658                                        !atomic_read(&cinfo->rpcs_out));
1659 }
1660 
1661 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1662 {
1663         atomic_inc(&cinfo->rpcs_out);
1664 }
1665 
1666 static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1667 {
1668         if (atomic_dec_and_test(&cinfo->rpcs_out))
1669                 wake_up_var(&cinfo->rpcs_out);
1670 }
1671 
1672 void nfs_commitdata_release(struct nfs_commit_data *data)
1673 {
1674         put_nfs_open_context(data->context);
1675         nfs_commit_free(data);
1676 }
1677 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1678 
1679 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1680                         const struct nfs_rpc_ops *nfs_ops,
1681                         const struct rpc_call_ops *call_ops,
1682                         int how, int flags)
1683 {
1684         struct rpc_task *task;
1685         int priority = flush_task_priority(how);
1686         struct rpc_message msg = {
1687                 .rpc_argp = &data->args,
1688                 .rpc_resp = &data->res,
1689                 .rpc_cred = data->cred,
1690         };
1691         struct rpc_task_setup task_setup_data = {
1692                 .task = &data->task,
1693                 .rpc_client = clnt,
1694                 .rpc_message = &msg,
1695                 .callback_ops = call_ops,
1696                 .callback_data = data,
1697                 .workqueue = nfsiod_workqueue,
1698                 .flags = RPC_TASK_ASYNC | flags,
1699                 .priority = priority,
1700         };
1701         /* Set up the initial task struct.  */
1702         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1703         trace_nfs_initiate_commit(data);
1704 
1705         dprintk("NFS: initiated commit call\n");
1706 
1707         task = rpc_run_task(&task_setup_data);
1708         if (IS_ERR(task))
1709                 return PTR_ERR(task);
1710         if (how & FLUSH_SYNC)
1711                 rpc_wait_for_completion_task(task);
1712         rpc_put_task(task);
1713         return 0;
1714 }
1715 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1716 
1717 static loff_t nfs_get_lwb(struct list_head *head)
1718 {
1719         loff_t lwb = 0;
1720         struct nfs_page *req;
1721 
1722         list_for_each_entry(req, head, wb_list)
1723                 if (lwb < (req_offset(req) + req->wb_bytes))
1724                         lwb = req_offset(req) + req->wb_bytes;
1725 
1726         return lwb;
1727 }
1728 
1729 /*
1730  * Set up the argument/result storage required for the RPC call.
1731  */
1732 void nfs_init_commit(struct nfs_commit_data *data,
1733                      struct list_head *head,
1734                      struct pnfs_layout_segment *lseg,
1735                      struct nfs_commit_info *cinfo)
1736 {
1737         struct nfs_page *first = nfs_list_entry(head->next);
1738         struct inode *inode = d_inode(first->wb_context->dentry);
1739 
1740         /* Set up the RPC argument and reply structs
1741          * NB: take care not to mess about with data->commit et al. */
1742 
1743         list_splice_init(head, &data->pages);
1744 
1745         data->inode       = inode;
1746         data->cred        = first->wb_context->cred;
1747         data->lseg        = lseg; /* reference transferred */
1748         /* only set lwb for pnfs commit */
1749         if (lseg)
1750                 data->lwb = nfs_get_lwb(&data->pages);
1751         data->mds_ops     = &nfs_commit_ops;
1752         data->completion_ops = cinfo->completion_ops;
1753         data->dreq        = cinfo->dreq;
1754 
1755         data->args.fh     = NFS_FH(data->inode);
1756         /* Note: we always request a commit of the entire inode */
1757         data->args.offset = 0;
1758         data->args.count  = 0;
1759         data->context     = get_nfs_open_context(first->wb_context);
1760         data->res.fattr   = &data->fattr;
1761         data->res.verf    = &data->verf;
1762         nfs_fattr_init(&data->fattr);
1763 }
1764 EXPORT_SYMBOL_GPL(nfs_init_commit);
1765 
1766 void nfs_retry_commit(struct list_head *page_list,
1767                       struct pnfs_layout_segment *lseg,
1768                       struct nfs_commit_info *cinfo,
1769                       u32 ds_commit_idx)
1770 {
1771         struct nfs_page *req;
1772 
1773         while (!list_empty(page_list)) {
1774                 req = nfs_list_entry(page_list->next);
1775                 nfs_list_remove_request(req);
1776                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1777                 if (!cinfo->dreq)
1778                         nfs_clear_page_commit(req->wb_page);
1779                 nfs_unlock_and_release_request(req);
1780         }
1781 }
1782 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1783 
1784 static void
1785 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1786                 struct nfs_page *req)
1787 {
1788         __set_page_dirty_nobuffers(req->wb_page);
1789 }
1790 
1791 /*
1792  * Commit dirty pages
1793  */
1794 static int
1795 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1796                 struct nfs_commit_info *cinfo)
1797 {
1798         struct nfs_commit_data  *data;
1799 
1800         /* another commit raced with us */
1801         if (list_empty(head))
1802                 return 0;
1803 
1804         data = nfs_commitdata_alloc(true);
1805 
1806         /* Set up the argument struct */
1807         nfs_init_commit(data, head, NULL, cinfo);
1808         atomic_inc(&cinfo->mds->rpcs_out);
1809         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1810                                    data->mds_ops, how, 0);
1811 }
1812 
1813 /*
1814  * COMMIT call returned
1815  */
1816 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1817 {
1818         struct nfs_commit_data  *data = calldata;
1819 
1820         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1821                                 task->tk_pid, task->tk_status);
1822 
1823         /* Call the NFS version-specific code */
1824         NFS_PROTO(data->inode)->commit_done(task, data);
1825         trace_nfs_commit_done(data);
1826 }
1827 
1828 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1829 {
1830         struct nfs_page *req;
1831         int status = data->task.tk_status;
1832         struct nfs_commit_info cinfo;
1833         struct nfs_server *nfss;
1834 
1835         while (!list_empty(&data->pages)) {
1836                 req = nfs_list_entry(data->pages.next);
1837                 nfs_list_remove_request(req);
1838                 if (req->wb_page)
1839                         nfs_clear_page_commit(req->wb_page);
1840 
1841                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1842                         req->wb_context->dentry->d_sb->s_id,
1843                         (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)),
1844                         req->wb_bytes,
1845                         (long long)req_offset(req));
1846                 if (status < 0) {
1847                         nfs_context_set_write_error(req->wb_context, status);
1848                         if (req->wb_page)
1849                                 nfs_inode_remove_request(req);
1850                         dprintk_cont(", error = %d\n", status);
1851                         goto next;
1852                 }
1853 
1854                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1855                  * returned by the server against all stored verfs. */
1856                 if (!nfs_write_verifier_cmp(&req->wb_verf, &data->verf.verifier)) {
1857                         /* We have a match */
1858                         if (req->wb_page)
1859                                 nfs_inode_remove_request(req);
1860                         dprintk_cont(" OK\n");
1861                         goto next;
1862                 }
1863                 /* We have a mismatch. Write the page again */
1864                 dprintk_cont(" mismatch\n");
1865                 nfs_mark_request_dirty(req);
1866                 set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1867         next:
1868                 nfs_unlock_and_release_request(req);
1869                 /* Latency breaker */
1870                 cond_resched();
1871         }
1872         nfss = NFS_SERVER(data->inode);
1873         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1874                 clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1875 
1876         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1877         nfs_commit_end(cinfo.mds);
1878 }
1879 
1880 static void nfs_commit_release(void *calldata)
1881 {
1882         struct nfs_commit_data *data = calldata;
1883 
1884         data->completion_ops->completion(data);
1885         nfs_commitdata_release(calldata);
1886 }
1887 
1888 static const struct rpc_call_ops nfs_commit_ops = {
1889         .rpc_call_prepare = nfs_commit_prepare,
1890         .rpc_call_done = nfs_commit_done,
1891         .rpc_release = nfs_commit_release,
1892 };
1893 
1894 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1895         .completion = nfs_commit_release_pages,
1896         .resched_write = nfs_commit_resched_write,
1897 };
1898 
1899 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1900                             int how, struct nfs_commit_info *cinfo)
1901 {
1902         int status;
1903 
1904         status = pnfs_commit_list(inode, head, how, cinfo);
1905         if (status == PNFS_NOT_ATTEMPTED)
1906                 status = nfs_commit_list(inode, head, how, cinfo);
1907         return status;
1908 }
1909 
1910 static int __nfs_commit_inode(struct inode *inode, int how,
1911                 struct writeback_control *wbc)
1912 {
1913         LIST_HEAD(head);
1914         struct nfs_commit_info cinfo;
1915         int may_wait = how & FLUSH_SYNC;
1916         int ret, nscan;
1917 
1918         nfs_init_cinfo_from_inode(&cinfo, inode);
1919         nfs_commit_begin(cinfo.mds);
1920         for (;;) {
1921                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1922                 if (ret <= 0)
1923                         break;
1924                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1925                 if (ret < 0)
1926                         break;
1927                 ret = 0;
1928                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1929                         if (nscan < wbc->nr_to_write)
1930                                 wbc->nr_to_write -= nscan;
1931                         else
1932                                 wbc->nr_to_write = 0;
1933                 }
1934                 if (nscan < INT_MAX)
1935                         break;
1936                 cond_resched();
1937         }
1938         nfs_commit_end(cinfo.mds);
1939         if (ret || !may_wait)
1940                 return ret;
1941         return wait_on_commit(cinfo.mds);
1942 }
1943 
1944 int nfs_commit_inode(struct inode *inode, int how)
1945 {
1946         return __nfs_commit_inode(inode, how, NULL);
1947 }
1948 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1949 
1950 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1951 {
1952         struct nfs_inode *nfsi = NFS_I(inode);
1953         int flags = FLUSH_SYNC;
1954         int ret = 0;
1955 
1956         if (wbc->sync_mode == WB_SYNC_NONE) {
1957                 /* no commits means nothing needs to be done */
1958                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1959                         goto check_requests_outstanding;
1960 
1961                 /* Don't commit yet if this is a non-blocking flush and there
1962                  * are a lot of outstanding writes for this mapping.
1963                  */
1964                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1965                         goto out_mark_dirty;
1966 
1967                 /* don't wait for the COMMIT response */
1968                 flags = 0;
1969         }
1970 
1971         ret = __nfs_commit_inode(inode, flags, wbc);
1972         if (!ret) {
1973                 if (flags & FLUSH_SYNC)
1974                         return 0;
1975         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1976                 goto out_mark_dirty;
1977 
1978 check_requests_outstanding:
1979         if (!atomic_read(&nfsi->commit_info.rpcs_out))
1980                 return ret;
1981 out_mark_dirty:
1982         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1983         return ret;
1984 }
1985 EXPORT_SYMBOL_GPL(nfs_write_inode);
1986 
1987 /*
1988  * Wrapper for filemap_write_and_wait_range()
1989  *
1990  * Needed for pNFS in order to ensure data becomes visible to the
1991  * client.
1992  */
1993 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
1994                 loff_t lstart, loff_t lend)
1995 {
1996         int ret;
1997 
1998         ret = filemap_write_and_wait_range(mapping, lstart, lend);
1999         if (ret == 0)
2000                 ret = pnfs_sync_inode(mapping->host, true);
2001         return ret;
2002 }
2003 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2004 
2005 /*
2006  * flush the inode to disk.
2007  */
2008 int nfs_wb_all(struct inode *inode)
2009 {
2010         int ret;
2011 
2012         trace_nfs_writeback_inode_enter(inode);
2013 
2014         ret = filemap_write_and_wait(inode->i_mapping);
2015         if (ret)
2016                 goto out;
2017         ret = nfs_commit_inode(inode, FLUSH_SYNC);
2018         if (ret < 0)
2019                 goto out;
2020         pnfs_sync_inode(inode, true);
2021         ret = 0;
2022 
2023 out:
2024         trace_nfs_writeback_inode_exit(inode, ret);
2025         return ret;
2026 }
2027 EXPORT_SYMBOL_GPL(nfs_wb_all);
2028 
2029 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
2030 {
2031         struct nfs_page *req;
2032         int ret = 0;
2033 
2034         wait_on_page_writeback(page);
2035 
2036         /* blocking call to cancel all requests and join to a single (head)
2037          * request */
2038         req = nfs_lock_and_join_requests(page);
2039 
2040         if (IS_ERR(req)) {
2041                 ret = PTR_ERR(req);
2042         } else if (req) {
2043                 /* all requests from this page have been cancelled by
2044                  * nfs_lock_and_join_requests, so just remove the head
2045                  * request from the inode / page_private pointer and
2046                  * release it */
2047                 nfs_inode_remove_request(req);
2048                 nfs_unlock_and_release_request(req);
2049         }
2050 
2051         return ret;
2052 }
2053 
2054 /*
2055  * Write back all requests on one page - we do this before reading it.
2056  */
2057 int nfs_wb_page(struct inode *inode, struct page *page)
2058 {
2059         loff_t range_start = page_file_offset(page);
2060         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2061         struct writeback_control wbc = {
2062                 .sync_mode = WB_SYNC_ALL,
2063                 .nr_to_write = 0,
2064                 .range_start = range_start,
2065                 .range_end = range_end,
2066         };
2067         int ret;
2068 
2069         trace_nfs_writeback_page_enter(inode);
2070 
2071         for (;;) {
2072                 wait_on_page_writeback(page);
2073                 if (clear_page_dirty_for_io(page)) {
2074                         ret = nfs_writepage_locked(page, &wbc);
2075                         if (ret < 0)
2076                                 goto out_error;
2077                         continue;
2078                 }
2079                 ret = 0;
2080                 if (!PagePrivate(page))
2081                         break;
2082                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2083                 if (ret < 0)
2084                         goto out_error;
2085         }
2086 out_error:
2087         trace_nfs_writeback_page_exit(inode, ret);
2088         return ret;
2089 }
2090 
2091 #ifdef CONFIG_MIGRATION
2092 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2093                 struct page *page, enum migrate_mode mode)
2094 {
2095         /*
2096          * If PagePrivate is set, then the page is currently associated with
2097          * an in-progress read or write request. Don't try to migrate it.
2098          *
2099          * FIXME: we could do this in principle, but we'll need a way to ensure
2100          *        that we can safely release the inode reference while holding
2101          *        the page lock.
2102          */
2103         if (PagePrivate(page))
2104                 return -EBUSY;
2105 
2106         if (!nfs_fscache_release_page(page, GFP_KERNEL))
2107                 return -EBUSY;
2108 
2109         return migrate_page(mapping, newpage, page, mode);
2110 }
2111 #endif
2112 
2113 int __init nfs_init_writepagecache(void)
2114 {
2115         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2116                                              sizeof(struct nfs_pgio_header),
2117                                              0, SLAB_HWCACHE_ALIGN,
2118                                              NULL);
2119         if (nfs_wdata_cachep == NULL)
2120                 return -ENOMEM;
2121 
2122         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2123                                                      nfs_wdata_cachep);
2124         if (nfs_wdata_mempool == NULL)
2125                 goto out_destroy_write_cache;
2126 
2127         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2128                                              sizeof(struct nfs_commit_data),
2129                                              0, SLAB_HWCACHE_ALIGN,
2130                                              NULL);
2131         if (nfs_cdata_cachep == NULL)
2132                 goto out_destroy_write_mempool;
2133 
2134         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2135                                                       nfs_cdata_cachep);
2136         if (nfs_commit_mempool == NULL)
2137                 goto out_destroy_commit_cache;
2138 
2139         /*
2140          * NFS congestion size, scale with available memory.
2141          *
2142          *  64MB:    8192k
2143          * 128MB:   11585k
2144          * 256MB:   16384k
2145          * 512MB:   23170k
2146          *   1GB:   32768k
2147          *   2GB:   46340k
2148          *   4GB:   65536k
2149          *   8GB:   92681k
2150          *  16GB:  131072k
2151          *
2152          * This allows larger machines to have larger/more transfers.
2153          * Limit the default to 256M
2154          */
2155         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2156         if (nfs_congestion_kb > 256*1024)
2157                 nfs_congestion_kb = 256*1024;
2158 
2159         return 0;
2160 
2161 out_destroy_commit_cache:
2162         kmem_cache_destroy(nfs_cdata_cachep);
2163 out_destroy_write_mempool:
2164         mempool_destroy(nfs_wdata_mempool);
2165 out_destroy_write_cache:
2166         kmem_cache_destroy(nfs_wdata_cachep);
2167         return -ENOMEM;
2168 }
2169 
2170 void nfs_destroy_writepagecache(void)
2171 {
2172         mempool_destroy(nfs_commit_mempool);
2173         kmem_cache_destroy(nfs_cdata_cachep);
2174         mempool_destroy(nfs_wdata_mempool);
2175         kmem_cache_destroy(nfs_wdata_cachep);
2176 }
2177 
2178 static const struct nfs_rw_ops nfs_rw_write_ops = {
2179         .rw_alloc_header        = nfs_writehdr_alloc,
2180         .rw_free_header         = nfs_writehdr_free,
2181         .rw_done                = nfs_writeback_done,
2182         .rw_result              = nfs_writeback_result,
2183         .rw_initiate            = nfs_initiate_write,
2184 };
2185 

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