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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 
 25 #include <asm/uaccess.h>
 26 
 27 #include "delegation.h"
 28 #include "internal.h"
 29 #include "iostat.h"
 30 #include "nfs4_fs.h"
 31 #include "fscache.h"
 32 #include "pnfs.h"
 33 
 34 #include "nfstrace.h"
 35 
 36 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
 37 
 38 #define MIN_POOL_WRITE          (32)
 39 #define MIN_POOL_COMMIT         (4)
 40 
 41 /*
 42  * Local function declarations
 43  */
 44 static void nfs_redirty_request(struct nfs_page *req);
 45 static const struct rpc_call_ops nfs_commit_ops;
 46 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
 47 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
 48 static const struct nfs_rw_ops nfs_rw_write_ops;
 49 static void nfs_clear_request_commit(struct nfs_page *req);
 50 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 51                                       struct inode *inode);
 52 static struct nfs_page *
 53 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 54                                                 struct page *page);
 55 
 56 static struct kmem_cache *nfs_wdata_cachep;
 57 static mempool_t *nfs_wdata_mempool;
 58 static struct kmem_cache *nfs_cdata_cachep;
 59 static mempool_t *nfs_commit_mempool;
 60 
 61 struct nfs_commit_data *nfs_commitdata_alloc(void)
 62 {
 63         struct nfs_commit_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
 64 
 65         if (p) {
 66                 memset(p, 0, sizeof(*p));
 67                 INIT_LIST_HEAD(&p->pages);
 68         }
 69         return p;
 70 }
 71 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
 72 
 73 void nfs_commit_free(struct nfs_commit_data *p)
 74 {
 75         mempool_free(p, nfs_commit_mempool);
 76 }
 77 EXPORT_SYMBOL_GPL(nfs_commit_free);
 78 
 79 static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 80 {
 81         struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
 82 
 83         if (p)
 84                 memset(p, 0, sizeof(*p));
 85         return p;
 86 }
 87 
 88 static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 89 {
 90         mempool_free(hdr, nfs_wdata_mempool);
 91 }
 92 
 93 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 94 {
 95         ctx->error = error;
 96         smp_wmb();
 97         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 98 }
 99 
100 /*
101  * nfs_page_find_head_request_locked - find head request associated with @page
102  *
103  * must be called while holding the inode lock.
104  *
105  * returns matching head request with reference held, or NULL if not found.
106  */
107 static struct nfs_page *
108 nfs_page_find_head_request_locked(struct nfs_inode *nfsi, struct page *page)
109 {
110         struct nfs_page *req = NULL;
111 
112         if (PagePrivate(page))
113                 req = (struct nfs_page *)page_private(page);
114         else if (unlikely(PageSwapCache(page)))
115                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
116                         page);
117 
118         if (req) {
119                 WARN_ON_ONCE(req->wb_head != req);
120                 kref_get(&req->wb_kref);
121         }
122 
123         return req;
124 }
125 
126 /*
127  * nfs_page_find_head_request - find head request associated with @page
128  *
129  * returns matching head request with reference held, or NULL if not found.
130  */
131 static struct nfs_page *nfs_page_find_head_request(struct page *page)
132 {
133         struct inode *inode = page_file_mapping(page)->host;
134         struct nfs_page *req = NULL;
135 
136         spin_lock(&inode->i_lock);
137         req = nfs_page_find_head_request_locked(NFS_I(inode), page);
138         spin_unlock(&inode->i_lock);
139         return req;
140 }
141 
142 /* Adjust the file length if we're writing beyond the end */
143 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
144 {
145         struct inode *inode = page_file_mapping(page)->host;
146         loff_t end, i_size;
147         pgoff_t end_index;
148 
149         spin_lock(&inode->i_lock);
150         i_size = i_size_read(inode);
151         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
152         if (i_size > 0 && page_file_index(page) < end_index)
153                 goto out;
154         end = page_file_offset(page) + ((loff_t)offset+count);
155         if (i_size >= end)
156                 goto out;
157         i_size_write(inode, end);
158         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
159 out:
160         spin_unlock(&inode->i_lock);
161 }
162 
163 /* A writeback failed: mark the page as bad, and invalidate the page cache */
164 static void nfs_set_pageerror(struct page *page)
165 {
166         nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
167 }
168 
169 /*
170  * nfs_page_group_search_locked
171  * @head - head request of page group
172  * @page_offset - offset into page
173  *
174  * Search page group with head @head to find a request that contains the
175  * page offset @page_offset.
176  *
177  * Returns a pointer to the first matching nfs request, or NULL if no
178  * match is found.
179  *
180  * Must be called with the page group lock held
181  */
182 static struct nfs_page *
183 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
184 {
185         struct nfs_page *req;
186 
187         WARN_ON_ONCE(head != head->wb_head);
188         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_head->wb_flags));
189 
190         req = head;
191         do {
192                 if (page_offset >= req->wb_pgbase &&
193                     page_offset < (req->wb_pgbase + req->wb_bytes))
194                         return req;
195 
196                 req = req->wb_this_page;
197         } while (req != head);
198 
199         return NULL;
200 }
201 
202 /*
203  * nfs_page_group_covers_page
204  * @head - head request of page group
205  *
206  * Return true if the page group with head @head covers the whole page,
207  * returns false otherwise
208  */
209 static bool nfs_page_group_covers_page(struct nfs_page *req)
210 {
211         struct nfs_page *tmp;
212         unsigned int pos = 0;
213         unsigned int len = nfs_page_length(req->wb_page);
214 
215         nfs_page_group_lock(req, false);
216 
217         do {
218                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
219                 if (tmp) {
220                         /* no way this should happen */
221                         WARN_ON_ONCE(tmp->wb_pgbase != pos);
222                         pos += tmp->wb_bytes - (pos - tmp->wb_pgbase);
223                 }
224         } while (tmp && pos < len);
225 
226         nfs_page_group_unlock(req);
227         WARN_ON_ONCE(pos > len);
228         return pos == len;
229 }
230 
231 /* We can set the PG_uptodate flag if we see that a write request
232  * covers the full page.
233  */
234 static void nfs_mark_uptodate(struct nfs_page *req)
235 {
236         if (PageUptodate(req->wb_page))
237                 return;
238         if (!nfs_page_group_covers_page(req))
239                 return;
240         SetPageUptodate(req->wb_page);
241 }
242 
243 static int wb_priority(struct writeback_control *wbc)
244 {
245         int ret = 0;
246         if (wbc->for_reclaim)
247                 return FLUSH_HIGHPRI | FLUSH_STABLE;
248         if (wbc->sync_mode == WB_SYNC_ALL)
249                 ret = FLUSH_COND_STABLE;
250         if (wbc->for_kupdate || wbc->for_background)
251                 ret |= FLUSH_LOWPRI;
252         return ret;
253 }
254 
255 /*
256  * NFS congestion control
257  */
258 
259 int nfs_congestion_kb;
260 
261 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
262 #define NFS_CONGESTION_OFF_THRESH       \
263         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
264 
265 static void nfs_set_page_writeback(struct page *page)
266 {
267         struct nfs_server *nfss = NFS_SERVER(page_file_mapping(page)->host);
268         int ret = test_set_page_writeback(page);
269 
270         WARN_ON_ONCE(ret != 0);
271 
272         if (atomic_long_inc_return(&nfss->writeback) >
273                         NFS_CONGESTION_ON_THRESH) {
274                 set_bdi_congested(&nfss->backing_dev_info,
275                                         BLK_RW_ASYNC);
276         }
277 }
278 
279 static void nfs_end_page_writeback(struct nfs_page *req)
280 {
281         struct inode *inode = page_file_mapping(req->wb_page)->host;
282         struct nfs_server *nfss = NFS_SERVER(inode);
283 
284         if (!nfs_page_group_sync_on_bit(req, PG_WB_END))
285                 return;
286 
287         end_page_writeback(req->wb_page);
288         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
289                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
290 }
291 
292 
293 /* nfs_page_group_clear_bits
294  *   @req - an nfs request
295  * clears all page group related bits from @req
296  */
297 static void
298 nfs_page_group_clear_bits(struct nfs_page *req)
299 {
300         clear_bit(PG_TEARDOWN, &req->wb_flags);
301         clear_bit(PG_UNLOCKPAGE, &req->wb_flags);
302         clear_bit(PG_UPTODATE, &req->wb_flags);
303         clear_bit(PG_WB_END, &req->wb_flags);
304         clear_bit(PG_REMOVE, &req->wb_flags);
305 }
306 
307 
308 /*
309  * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
310  *
311  * this is a helper function for nfs_lock_and_join_requests
312  *
313  * @inode - inode associated with request page group, must be holding inode lock
314  * @head  - head request of page group, must be holding head lock
315  * @req   - request that couldn't lock and needs to wait on the req bit lock
316  * @nonblock - if true, don't actually wait
317  *
318  * NOTE: this must be called holding page_group bit lock and inode spin lock
319  *       and BOTH will be released before returning.
320  *
321  * returns 0 on success, < 0 on error.
322  */
323 static int
324 nfs_unroll_locks_and_wait(struct inode *inode, struct nfs_page *head,
325                           struct nfs_page *req, bool nonblock)
326         __releases(&inode->i_lock)
327 {
328         struct nfs_page *tmp;
329         int ret;
330 
331         /* relinquish all the locks successfully grabbed this run */
332         for (tmp = head ; tmp != req; tmp = tmp->wb_this_page)
333                 nfs_unlock_request(tmp);
334 
335         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
336 
337         /* grab a ref on the request that will be waited on */
338         kref_get(&req->wb_kref);
339 
340         nfs_page_group_unlock(head);
341         spin_unlock(&inode->i_lock);
342 
343         /* release ref from nfs_page_find_head_request_locked */
344         nfs_release_request(head);
345 
346         if (!nonblock)
347                 ret = nfs_wait_on_request(req);
348         else
349                 ret = -EAGAIN;
350         nfs_release_request(req);
351 
352         return ret;
353 }
354 
355 /*
356  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
357  *
358  * @destroy_list - request list (using wb_this_page) terminated by @old_head
359  * @old_head - the old head of the list
360  *
361  * All subrequests must be locked and removed from all lists, so at this point
362  * they are only "active" in this function, and possibly in nfs_wait_on_request
363  * with a reference held by some other context.
364  */
365 static void
366 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
367                                  struct nfs_page *old_head)
368 {
369         while (destroy_list) {
370                 struct nfs_page *subreq = destroy_list;
371 
372                 destroy_list = (subreq->wb_this_page == old_head) ?
373                                    NULL : subreq->wb_this_page;
374 
375                 WARN_ON_ONCE(old_head != subreq->wb_head);
376 
377                 /* make sure old group is not used */
378                 subreq->wb_head = subreq;
379                 subreq->wb_this_page = subreq;
380 
381                 /* subreq is now totally disconnected from page group or any
382                  * write / commit lists. last chance to wake any waiters */
383                 nfs_unlock_request(subreq);
384 
385                 if (!test_bit(PG_TEARDOWN, &subreq->wb_flags)) {
386                         /* release ref on old head request */
387                         nfs_release_request(old_head);
388 
389                         nfs_page_group_clear_bits(subreq);
390 
391                         /* release the PG_INODE_REF reference */
392                         if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags))
393                                 nfs_release_request(subreq);
394                         else
395                                 WARN_ON_ONCE(1);
396                 } else {
397                         WARN_ON_ONCE(test_bit(PG_CLEAN, &subreq->wb_flags));
398                         /* zombie requests have already released the last
399                          * reference and were waiting on the rest of the
400                          * group to complete. Since it's no longer part of a
401                          * group, simply free the request */
402                         nfs_page_group_clear_bits(subreq);
403                         nfs_free_request(subreq);
404                 }
405         }
406 }
407 
408 /*
409  * nfs_lock_and_join_requests - join all subreqs to the head req and return
410  *                              a locked reference, cancelling any pending
411  *                              operations for this page.
412  *
413  * @page - the page used to lookup the "page group" of nfs_page structures
414  * @nonblock - if true, don't block waiting for request locks
415  *
416  * This function joins all sub requests to the head request by first
417  * locking all requests in the group, cancelling any pending operations
418  * and finally updating the head request to cover the whole range covered by
419  * the (former) group.  All subrequests are removed from any write or commit
420  * lists, unlinked from the group and destroyed.
421  *
422  * Returns a locked, referenced pointer to the head request - which after
423  * this call is guaranteed to be the only request associated with the page.
424  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
425  * error was encountered.
426  */
427 static struct nfs_page *
428 nfs_lock_and_join_requests(struct page *page, bool nonblock)
429 {
430         struct inode *inode = page_file_mapping(page)->host;
431         struct nfs_page *head, *subreq;
432         struct nfs_page *destroy_list = NULL;
433         unsigned int total_bytes;
434         int ret;
435 
436 try_again:
437         total_bytes = 0;
438 
439         WARN_ON_ONCE(destroy_list);
440 
441         spin_lock(&inode->i_lock);
442 
443         /*
444          * A reference is taken only on the head request which acts as a
445          * reference to the whole page group - the group will not be destroyed
446          * until the head reference is released.
447          */
448         head = nfs_page_find_head_request_locked(NFS_I(inode), page);
449 
450         if (!head) {
451                 spin_unlock(&inode->i_lock);
452                 return NULL;
453         }
454 
455         /* holding inode lock, so always make a non-blocking call to try the
456          * page group lock */
457         ret = nfs_page_group_lock(head, true);
458         if (ret < 0) {
459                 spin_unlock(&inode->i_lock);
460 
461                 if (!nonblock && ret == -EAGAIN) {
462                         nfs_page_group_lock_wait(head);
463                         nfs_release_request(head);
464                         goto try_again;
465                 }
466 
467                 nfs_release_request(head);
468                 return ERR_PTR(ret);
469         }
470 
471         /* lock each request in the page group */
472         subreq = head;
473         do {
474                 /*
475                  * Subrequests are always contiguous, non overlapping
476                  * and in order. If not, it's a programming error.
477                  */
478                 WARN_ON_ONCE(subreq->wb_offset !=
479                      (head->wb_offset + total_bytes));
480 
481                 /* keep track of how many bytes this group covers */
482                 total_bytes += subreq->wb_bytes;
483 
484                 if (!nfs_lock_request(subreq)) {
485                         /* releases page group bit lock and
486                          * inode spin lock and all references */
487                         ret = nfs_unroll_locks_and_wait(inode, head,
488                                 subreq, nonblock);
489 
490                         if (ret == 0)
491                                 goto try_again;
492 
493                         return ERR_PTR(ret);
494                 }
495 
496                 subreq = subreq->wb_this_page;
497         } while (subreq != head);
498 
499         /* Now that all requests are locked, make sure they aren't on any list.
500          * Commit list removal accounting is done after locks are dropped */
501         subreq = head;
502         do {
503                 nfs_clear_request_commit(subreq);
504                 subreq = subreq->wb_this_page;
505         } while (subreq != head);
506 
507         /* unlink subrequests from head, destroy them later */
508         if (head->wb_this_page != head) {
509                 /* destroy list will be terminated by head */
510                 destroy_list = head->wb_this_page;
511                 head->wb_this_page = head;
512 
513                 /* change head request to cover whole range that
514                  * the former page group covered */
515                 head->wb_bytes = total_bytes;
516         }
517 
518         /*
519          * prepare head request to be added to new pgio descriptor
520          */
521         nfs_page_group_clear_bits(head);
522 
523         /*
524          * some part of the group was still on the inode list - otherwise
525          * the group wouldn't be involved in async write.
526          * grab a reference for the head request, iff it needs one.
527          */
528         if (!test_and_set_bit(PG_INODE_REF, &head->wb_flags))
529                 kref_get(&head->wb_kref);
530 
531         nfs_page_group_unlock(head);
532 
533         /* drop lock to clean uprequests on destroy list */
534         spin_unlock(&inode->i_lock);
535 
536         nfs_destroy_unlinked_subrequests(destroy_list, head);
537 
538         /* still holds ref on head from nfs_page_find_head_request_locked
539          * and still has lock on head from lock loop */
540         return head;
541 }
542 
543 /*
544  * Find an associated nfs write request, and prepare to flush it out
545  * May return an error if the user signalled nfs_wait_on_request().
546  */
547 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
548                                 struct page *page, bool nonblock)
549 {
550         struct nfs_page *req;
551         int ret = 0;
552 
553         req = nfs_lock_and_join_requests(page, nonblock);
554         if (!req)
555                 goto out;
556         ret = PTR_ERR(req);
557         if (IS_ERR(req))
558                 goto out;
559 
560         nfs_set_page_writeback(page);
561         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
562 
563         ret = 0;
564         if (!nfs_pageio_add_request(pgio, req)) {
565                 nfs_redirty_request(req);
566                 ret = pgio->pg_error;
567         }
568 out:
569         return ret;
570 }
571 
572 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
573 {
574         struct inode *inode = page_file_mapping(page)->host;
575         int ret;
576 
577         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
578         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
579 
580         nfs_pageio_cond_complete(pgio, page_file_index(page));
581         ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
582         if (ret == -EAGAIN) {
583                 redirty_page_for_writepage(wbc, page);
584                 ret = 0;
585         }
586         return ret;
587 }
588 
589 /*
590  * Write an mmapped page to the server.
591  */
592 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
593 {
594         struct nfs_pageio_descriptor pgio;
595         int err;
596 
597         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc),
598                                 false, &nfs_async_write_completion_ops);
599         err = nfs_do_writepage(page, wbc, &pgio);
600         nfs_pageio_complete(&pgio);
601         if (err < 0)
602                 return err;
603         if (pgio.pg_error < 0)
604                 return pgio.pg_error;
605         return 0;
606 }
607 
608 int nfs_writepage(struct page *page, struct writeback_control *wbc)
609 {
610         int ret;
611 
612         ret = nfs_writepage_locked(page, wbc);
613         unlock_page(page);
614         return ret;
615 }
616 
617 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
618 {
619         int ret;
620 
621         ret = nfs_do_writepage(page, wbc, data);
622         unlock_page(page);
623         return ret;
624 }
625 
626 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
627 {
628         struct inode *inode = mapping->host;
629         unsigned long *bitlock = &NFS_I(inode)->flags;
630         struct nfs_pageio_descriptor pgio;
631         int err;
632 
633         /* Stop dirtying of new pages while we sync */
634         err = wait_on_bit_lock_action(bitlock, NFS_INO_FLUSHING,
635                         nfs_wait_bit_killable, TASK_KILLABLE);
636         if (err)
637                 goto out_err;
638 
639         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
640 
641         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
642                                 &nfs_async_write_completion_ops);
643         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
644         nfs_pageio_complete(&pgio);
645 
646         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
647         smp_mb__after_atomic();
648         wake_up_bit(bitlock, NFS_INO_FLUSHING);
649 
650         if (err < 0)
651                 goto out_err;
652         err = pgio.pg_error;
653         if (err < 0)
654                 goto out_err;
655         return 0;
656 out_err:
657         return err;
658 }
659 
660 /*
661  * Insert a write request into an inode
662  */
663 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
664 {
665         struct nfs_inode *nfsi = NFS_I(inode);
666 
667         WARN_ON_ONCE(req->wb_this_page != req);
668 
669         /* Lock the request! */
670         nfs_lock_request(req);
671 
672         spin_lock(&inode->i_lock);
673         if (!nfsi->npages && NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
674                 inode->i_version++;
675         /*
676          * Swap-space should not get truncated. Hence no need to plug the race
677          * with invalidate/truncate.
678          */
679         if (likely(!PageSwapCache(req->wb_page))) {
680                 set_bit(PG_MAPPED, &req->wb_flags);
681                 SetPagePrivate(req->wb_page);
682                 set_page_private(req->wb_page, (unsigned long)req);
683         }
684         nfsi->npages++;
685         /* this a head request for a page group - mark it as having an
686          * extra reference so sub groups can follow suit */
687         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
688         kref_get(&req->wb_kref);
689         spin_unlock(&inode->i_lock);
690 }
691 
692 /*
693  * Remove a write request from an inode
694  */
695 static void nfs_inode_remove_request(struct nfs_page *req)
696 {
697         struct inode *inode = req->wb_context->dentry->d_inode;
698         struct nfs_inode *nfsi = NFS_I(inode);
699         struct nfs_page *head;
700 
701         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
702                 head = req->wb_head;
703 
704                 spin_lock(&inode->i_lock);
705                 if (likely(!PageSwapCache(head->wb_page))) {
706                         set_page_private(head->wb_page, 0);
707                         ClearPagePrivate(head->wb_page);
708                         smp_mb__after_atomic();
709                         wake_up_page(head->wb_page, PG_private);
710                         clear_bit(PG_MAPPED, &head->wb_flags);
711                 }
712                 nfsi->npages--;
713                 spin_unlock(&inode->i_lock);
714         }
715 
716         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
717                 nfs_release_request(req);
718 }
719 
720 static void
721 nfs_mark_request_dirty(struct nfs_page *req)
722 {
723         __set_page_dirty_nobuffers(req->wb_page);
724 }
725 
726 /*
727  * nfs_page_search_commits_for_head_request_locked
728  *
729  * Search through commit lists on @inode for the head request for @page.
730  * Must be called while holding the inode (which is cinfo) lock.
731  *
732  * Returns the head request if found, or NULL if not found.
733  */
734 static struct nfs_page *
735 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
736                                                 struct page *page)
737 {
738         struct nfs_page *freq, *t;
739         struct nfs_commit_info cinfo;
740         struct inode *inode = &nfsi->vfs_inode;
741 
742         nfs_init_cinfo_from_inode(&cinfo, inode);
743 
744         /* search through pnfs commit lists */
745         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
746         if (freq)
747                 return freq->wb_head;
748 
749         /* Linearly search the commit list for the correct request */
750         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
751                 if (freq->wb_page == page)
752                         return freq->wb_head;
753         }
754 
755         return NULL;
756 }
757 
758 /**
759  * nfs_request_add_commit_list - add request to a commit list
760  * @req: pointer to a struct nfs_page
761  * @dst: commit list head
762  * @cinfo: holds list lock and accounting info
763  *
764  * This sets the PG_CLEAN bit, updates the cinfo count of
765  * number of outstanding requests requiring a commit as well as
766  * the MM page stats.
767  *
768  * The caller must _not_ hold the cinfo->lock, but must be
769  * holding the nfs_page lock.
770  */
771 void
772 nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
773                             struct nfs_commit_info *cinfo)
774 {
775         set_bit(PG_CLEAN, &(req)->wb_flags);
776         spin_lock(cinfo->lock);
777         nfs_list_add_request(req, dst);
778         cinfo->mds->ncommit++;
779         spin_unlock(cinfo->lock);
780         if (!cinfo->dreq) {
781                 inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
782                 inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
783                              BDI_RECLAIMABLE);
784                 __mark_inode_dirty(req->wb_context->dentry->d_inode,
785                                    I_DIRTY_DATASYNC);
786         }
787 }
788 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
789 
790 /**
791  * nfs_request_remove_commit_list - Remove request from a commit list
792  * @req: pointer to a nfs_page
793  * @cinfo: holds list lock and accounting info
794  *
795  * This clears the PG_CLEAN bit, and updates the cinfo's count of
796  * number of outstanding requests requiring a commit
797  * It does not update the MM page stats.
798  *
799  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
800  */
801 void
802 nfs_request_remove_commit_list(struct nfs_page *req,
803                                struct nfs_commit_info *cinfo)
804 {
805         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
806                 return;
807         nfs_list_remove_request(req);
808         cinfo->mds->ncommit--;
809 }
810 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
811 
812 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
813                                       struct inode *inode)
814 {
815         cinfo->lock = &inode->i_lock;
816         cinfo->mds = &NFS_I(inode)->commit_info;
817         cinfo->ds = pnfs_get_ds_info(inode);
818         cinfo->dreq = NULL;
819         cinfo->completion_ops = &nfs_commit_completion_ops;
820 }
821 
822 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
823                     struct inode *inode,
824                     struct nfs_direct_req *dreq)
825 {
826         if (dreq)
827                 nfs_init_cinfo_from_dreq(cinfo, dreq);
828         else
829                 nfs_init_cinfo_from_inode(cinfo, inode);
830 }
831 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
832 
833 /*
834  * Add a request to the inode's commit list.
835  */
836 void
837 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
838                         struct nfs_commit_info *cinfo)
839 {
840         if (pnfs_mark_request_commit(req, lseg, cinfo))
841                 return;
842         nfs_request_add_commit_list(req, &cinfo->mds->list, cinfo);
843 }
844 
845 static void
846 nfs_clear_page_commit(struct page *page)
847 {
848         dec_zone_page_state(page, NR_UNSTABLE_NFS);
849         dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
850 }
851 
852 /* Called holding inode (/cinfo) lock */
853 static void
854 nfs_clear_request_commit(struct nfs_page *req)
855 {
856         if (test_bit(PG_CLEAN, &req->wb_flags)) {
857                 struct inode *inode = req->wb_context->dentry->d_inode;
858                 struct nfs_commit_info cinfo;
859 
860                 nfs_init_cinfo_from_inode(&cinfo, inode);
861                 if (!pnfs_clear_request_commit(req, &cinfo)) {
862                         nfs_request_remove_commit_list(req, &cinfo);
863                 }
864                 nfs_clear_page_commit(req->wb_page);
865         }
866 }
867 
868 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
869 {
870         if (hdr->verf.committed == NFS_DATA_SYNC)
871                 return hdr->lseg == NULL;
872         return hdr->verf.committed != NFS_FILE_SYNC;
873 }
874 
875 static void nfs_write_completion(struct nfs_pgio_header *hdr)
876 {
877         struct nfs_commit_info cinfo;
878         unsigned long bytes = 0;
879 
880         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
881                 goto out;
882         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
883         while (!list_empty(&hdr->pages)) {
884                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
885 
886                 bytes += req->wb_bytes;
887                 nfs_list_remove_request(req);
888                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
889                     (hdr->good_bytes < bytes)) {
890                         nfs_set_pageerror(req->wb_page);
891                         nfs_context_set_write_error(req->wb_context, hdr->error);
892                         goto remove_req;
893                 }
894                 if (nfs_write_need_commit(hdr)) {
895                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
896                         nfs_mark_request_commit(req, hdr->lseg, &cinfo);
897                         goto next;
898                 }
899 remove_req:
900                 nfs_inode_remove_request(req);
901 next:
902                 nfs_unlock_request(req);
903                 nfs_end_page_writeback(req);
904                 nfs_release_request(req);
905         }
906 out:
907         hdr->release(hdr);
908 }
909 
910 unsigned long
911 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
912 {
913         return cinfo->mds->ncommit;
914 }
915 
916 /* cinfo->lock held by caller */
917 int
918 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
919                      struct nfs_commit_info *cinfo, int max)
920 {
921         struct nfs_page *req, *tmp;
922         int ret = 0;
923 
924         list_for_each_entry_safe(req, tmp, src, wb_list) {
925                 if (!nfs_lock_request(req))
926                         continue;
927                 kref_get(&req->wb_kref);
928                 if (cond_resched_lock(cinfo->lock))
929                         list_safe_reset_next(req, tmp, wb_list);
930                 nfs_request_remove_commit_list(req, cinfo);
931                 nfs_list_add_request(req, dst);
932                 ret++;
933                 if ((ret == max) && !cinfo->dreq)
934                         break;
935         }
936         return ret;
937 }
938 
939 /*
940  * nfs_scan_commit - Scan an inode for commit requests
941  * @inode: NFS inode to scan
942  * @dst: mds destination list
943  * @cinfo: mds and ds lists of reqs ready to commit
944  *
945  * Moves requests from the inode's 'commit' request list.
946  * The requests are *not* checked to ensure that they form a contiguous set.
947  */
948 int
949 nfs_scan_commit(struct inode *inode, struct list_head *dst,
950                 struct nfs_commit_info *cinfo)
951 {
952         int ret = 0;
953 
954         spin_lock(cinfo->lock);
955         if (cinfo->mds->ncommit > 0) {
956                 const int max = INT_MAX;
957 
958                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
959                                            cinfo, max);
960                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
961         }
962         spin_unlock(cinfo->lock);
963         return ret;
964 }
965 
966 /*
967  * Search for an existing write request, and attempt to update
968  * it to reflect a new dirty region on a given page.
969  *
970  * If the attempt fails, then the existing request is flushed out
971  * to disk.
972  */
973 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
974                 struct page *page,
975                 unsigned int offset,
976                 unsigned int bytes)
977 {
978         struct nfs_page *req;
979         unsigned int rqend;
980         unsigned int end;
981         int error;
982 
983         if (!PagePrivate(page))
984                 return NULL;
985 
986         end = offset + bytes;
987         spin_lock(&inode->i_lock);
988 
989         for (;;) {
990                 req = nfs_page_find_head_request_locked(NFS_I(inode), page);
991                 if (req == NULL)
992                         goto out_unlock;
993 
994                 /* should be handled by nfs_flush_incompatible */
995                 WARN_ON_ONCE(req->wb_head != req);
996                 WARN_ON_ONCE(req->wb_this_page != req);
997 
998                 rqend = req->wb_offset + req->wb_bytes;
999                 /*
1000                  * Tell the caller to flush out the request if
1001                  * the offsets are non-contiguous.
1002                  * Note: nfs_flush_incompatible() will already
1003                  * have flushed out requests having wrong owners.
1004                  */
1005                 if (offset > rqend
1006                     || end < req->wb_offset)
1007                         goto out_flushme;
1008 
1009                 if (nfs_lock_request(req))
1010                         break;
1011 
1012                 /* The request is locked, so wait and then retry */
1013                 spin_unlock(&inode->i_lock);
1014                 error = nfs_wait_on_request(req);
1015                 nfs_release_request(req);
1016                 if (error != 0)
1017                         goto out_err;
1018                 spin_lock(&inode->i_lock);
1019         }
1020 
1021         /* Okay, the request matches. Update the region */
1022         if (offset < req->wb_offset) {
1023                 req->wb_offset = offset;
1024                 req->wb_pgbase = offset;
1025         }
1026         if (end > rqend)
1027                 req->wb_bytes = end - req->wb_offset;
1028         else
1029                 req->wb_bytes = rqend - req->wb_offset;
1030 out_unlock:
1031         if (req)
1032                 nfs_clear_request_commit(req);
1033         spin_unlock(&inode->i_lock);
1034         return req;
1035 out_flushme:
1036         spin_unlock(&inode->i_lock);
1037         nfs_release_request(req);
1038         error = nfs_wb_page(inode, page);
1039 out_err:
1040         return ERR_PTR(error);
1041 }
1042 
1043 /*
1044  * Try to update an existing write request, or create one if there is none.
1045  *
1046  * Note: Should always be called with the Page Lock held to prevent races
1047  * if we have to add a new request. Also assumes that the caller has
1048  * already called nfs_flush_incompatible() if necessary.
1049  */
1050 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1051                 struct page *page, unsigned int offset, unsigned int bytes)
1052 {
1053         struct inode *inode = page_file_mapping(page)->host;
1054         struct nfs_page *req;
1055 
1056         req = nfs_try_to_update_request(inode, page, offset, bytes);
1057         if (req != NULL)
1058                 goto out;
1059         req = nfs_create_request(ctx, page, NULL, offset, bytes);
1060         if (IS_ERR(req))
1061                 goto out;
1062         nfs_inode_add_request(inode, req);
1063 out:
1064         return req;
1065 }
1066 
1067 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1068                 unsigned int offset, unsigned int count)
1069 {
1070         struct nfs_page *req;
1071 
1072         req = nfs_setup_write_request(ctx, page, offset, count);
1073         if (IS_ERR(req))
1074                 return PTR_ERR(req);
1075         /* Update file length */
1076         nfs_grow_file(page, offset, count);
1077         nfs_mark_uptodate(req);
1078         nfs_mark_request_dirty(req);
1079         nfs_unlock_and_release_request(req);
1080         return 0;
1081 }
1082 
1083 int nfs_flush_incompatible(struct file *file, struct page *page)
1084 {
1085         struct nfs_open_context *ctx = nfs_file_open_context(file);
1086         struct nfs_lock_context *l_ctx;
1087         struct nfs_page *req;
1088         int do_flush, status;
1089         /*
1090          * Look for a request corresponding to this page. If there
1091          * is one, and it belongs to another file, we flush it out
1092          * before we try to copy anything into the page. Do this
1093          * due to the lack of an ACCESS-type call in NFSv2.
1094          * Also do the same if we find a request from an existing
1095          * dropped page.
1096          */
1097         do {
1098                 req = nfs_page_find_head_request(page);
1099                 if (req == NULL)
1100                         return 0;
1101                 l_ctx = req->wb_lock_context;
1102                 do_flush = req->wb_page != page || req->wb_context != ctx;
1103                 /* for now, flush if more than 1 request in page_group */
1104                 do_flush |= req->wb_this_page != req;
1105                 if (l_ctx && ctx->dentry->d_inode->i_flock != NULL) {
1106                         do_flush |= l_ctx->lockowner.l_owner != current->files
1107                                 || l_ctx->lockowner.l_pid != current->tgid;
1108                 }
1109                 nfs_release_request(req);
1110                 if (!do_flush)
1111                         return 0;
1112                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1113         } while (status == 0);
1114         return status;
1115 }
1116 
1117 /*
1118  * Avoid buffered writes when a open context credential's key would
1119  * expire soon.
1120  *
1121  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1122  *
1123  * Return 0 and set a credential flag which triggers the inode to flush
1124  * and performs  NFS_FILE_SYNC writes if the key will expired within
1125  * RPC_KEY_EXPIRE_TIMEO.
1126  */
1127 int
1128 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1129 {
1130         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1131         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1132 
1133         return rpcauth_key_timeout_notify(auth, ctx->cred);
1134 }
1135 
1136 /*
1137  * Test if the open context credential key is marked to expire soon.
1138  */
1139 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx)
1140 {
1141         return rpcauth_cred_key_to_expire(ctx->cred);
1142 }
1143 
1144 /*
1145  * If the page cache is marked as unsafe or invalid, then we can't rely on
1146  * the PageUptodate() flag. In this case, we will need to turn off
1147  * write optimisations that depend on the page contents being correct.
1148  */
1149 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
1150 {
1151         struct nfs_inode *nfsi = NFS_I(inode);
1152 
1153         if (nfs_have_delegated_attributes(inode))
1154                 goto out;
1155         if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
1156                 return false;
1157         smp_rmb();
1158         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
1159                 return false;
1160 out:
1161         if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
1162                 return false;
1163         return PageUptodate(page) != 0;
1164 }
1165 
1166 /* If we know the page is up to date, and we're not using byte range locks (or
1167  * if we have the whole file locked for writing), it may be more efficient to
1168  * extend the write to cover the entire page in order to avoid fragmentation
1169  * inefficiencies.
1170  *
1171  * If the file is opened for synchronous writes then we can just skip the rest
1172  * of the checks.
1173  */
1174 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
1175 {
1176         if (file->f_flags & O_DSYNC)
1177                 return 0;
1178         if (!nfs_write_pageuptodate(page, inode))
1179                 return 0;
1180         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1181                 return 1;
1182         if (inode->i_flock == NULL || (inode->i_flock->fl_start == 0 &&
1183                         inode->i_flock->fl_end == OFFSET_MAX &&
1184                         inode->i_flock->fl_type != F_RDLCK))
1185                 return 1;
1186         return 0;
1187 }
1188 
1189 /*
1190  * Update and possibly write a cached page of an NFS file.
1191  *
1192  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1193  * things with a page scheduled for an RPC call (e.g. invalidate it).
1194  */
1195 int nfs_updatepage(struct file *file, struct page *page,
1196                 unsigned int offset, unsigned int count)
1197 {
1198         struct nfs_open_context *ctx = nfs_file_open_context(file);
1199         struct inode    *inode = page_file_mapping(page)->host;
1200         int             status = 0;
1201 
1202         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1203 
1204         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1205                 file, count, (long long)(page_file_offset(page) + offset));
1206 
1207         if (!count)
1208                 goto out;
1209 
1210         if (nfs_can_extend_write(file, page, inode)) {
1211                 count = max(count + offset, nfs_page_length(page));
1212                 offset = 0;
1213         }
1214 
1215         status = nfs_writepage_setup(ctx, page, offset, count);
1216         if (status < 0)
1217                 nfs_set_pageerror(page);
1218         else
1219                 __set_page_dirty_nobuffers(page);
1220 out:
1221         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1222                         status, (long long)i_size_read(inode));
1223         return status;
1224 }
1225 
1226 static int flush_task_priority(int how)
1227 {
1228         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1229                 case FLUSH_HIGHPRI:
1230                         return RPC_PRIORITY_HIGH;
1231                 case FLUSH_LOWPRI:
1232                         return RPC_PRIORITY_LOW;
1233         }
1234         return RPC_PRIORITY_NORMAL;
1235 }
1236 
1237 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1238                                struct rpc_message *msg,
1239                                struct rpc_task_setup *task_setup_data, int how)
1240 {
1241         struct inode *inode = hdr->inode;
1242         int priority = flush_task_priority(how);
1243 
1244         task_setup_data->priority = priority;
1245         NFS_PROTO(inode)->write_setup(hdr, msg);
1246 
1247         nfs4_state_protect_write(NFS_SERVER(inode)->nfs_client,
1248                                  &task_setup_data->rpc_client, msg, hdr);
1249 }
1250 
1251 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1252  * call this on each, which will prepare them to be retried on next
1253  * writeback using standard nfs.
1254  */
1255 static void nfs_redirty_request(struct nfs_page *req)
1256 {
1257         nfs_mark_request_dirty(req);
1258         set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1259         nfs_unlock_request(req);
1260         nfs_end_page_writeback(req);
1261         nfs_release_request(req);
1262 }
1263 
1264 static void nfs_async_write_error(struct list_head *head)
1265 {
1266         struct nfs_page *req;
1267 
1268         while (!list_empty(head)) {
1269                 req = nfs_list_entry(head->next);
1270                 nfs_list_remove_request(req);
1271                 nfs_redirty_request(req);
1272         }
1273 }
1274 
1275 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1276         .error_cleanup = nfs_async_write_error,
1277         .completion = nfs_write_completion,
1278 };
1279 
1280 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1281                                struct inode *inode, int ioflags, bool force_mds,
1282                                const struct nfs_pgio_completion_ops *compl_ops)
1283 {
1284         struct nfs_server *server = NFS_SERVER(inode);
1285         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1286 
1287 #ifdef CONFIG_NFS_V4_1
1288         if (server->pnfs_curr_ld && !force_mds)
1289                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1290 #endif
1291         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1292                         server->wsize, ioflags);
1293 }
1294 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1295 
1296 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1297 {
1298         pgio->pg_ops = &nfs_pgio_rw_ops;
1299         pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1300 }
1301 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1302 
1303 
1304 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1305 {
1306         struct nfs_commit_data *data = calldata;
1307 
1308         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1309 }
1310 
1311 static void nfs_writeback_release_common(struct nfs_pgio_header *hdr)
1312 {
1313         /* do nothing! */
1314 }
1315 
1316 /*
1317  * Special version of should_remove_suid() that ignores capabilities.
1318  */
1319 static int nfs_should_remove_suid(const struct inode *inode)
1320 {
1321         umode_t mode = inode->i_mode;
1322         int kill = 0;
1323 
1324         /* suid always must be killed */
1325         if (unlikely(mode & S_ISUID))
1326                 kill = ATTR_KILL_SUID;
1327 
1328         /*
1329          * sgid without any exec bits is just a mandatory locking mark; leave
1330          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1331          */
1332         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1333                 kill |= ATTR_KILL_SGID;
1334 
1335         if (unlikely(kill && S_ISREG(mode)))
1336                 return kill;
1337 
1338         return 0;
1339 }
1340 
1341 /*
1342  * This function is called when the WRITE call is complete.
1343  */
1344 static int nfs_writeback_done(struct rpc_task *task,
1345                               struct nfs_pgio_header *hdr,
1346                               struct inode *inode)
1347 {
1348         int status;
1349 
1350         /*
1351          * ->write_done will attempt to use post-op attributes to detect
1352          * conflicting writes by other clients.  A strict interpretation
1353          * of close-to-open would allow us to continue caching even if
1354          * another writer had changed the file, but some applications
1355          * depend on tighter cache coherency when writing.
1356          */
1357         status = NFS_PROTO(inode)->write_done(task, hdr);
1358         if (status != 0)
1359                 return status;
1360         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1361 
1362         if (hdr->res.verf->committed < hdr->args.stable &&
1363             task->tk_status >= 0) {
1364                 /* We tried a write call, but the server did not
1365                  * commit data to stable storage even though we
1366                  * requested it.
1367                  * Note: There is a known bug in Tru64 < 5.0 in which
1368                  *       the server reports NFS_DATA_SYNC, but performs
1369                  *       NFS_FILE_SYNC. We therefore implement this checking
1370                  *       as a dprintk() in order to avoid filling syslog.
1371                  */
1372                 static unsigned long    complain;
1373 
1374                 /* Note this will print the MDS for a DS write */
1375                 if (time_before(complain, jiffies)) {
1376                         dprintk("NFS:       faulty NFS server %s:"
1377                                 " (committed = %d) != (stable = %d)\n",
1378                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1379                                 hdr->res.verf->committed, hdr->args.stable);
1380                         complain = jiffies + 300 * HZ;
1381                 }
1382         }
1383 
1384         /* Deal with the suid/sgid bit corner case */
1385         if (nfs_should_remove_suid(inode))
1386                 nfs_mark_for_revalidate(inode);
1387         return 0;
1388 }
1389 
1390 /*
1391  * This function is called when the WRITE call is complete.
1392  */
1393 static void nfs_writeback_result(struct rpc_task *task,
1394                                  struct nfs_pgio_header *hdr)
1395 {
1396         struct nfs_pgio_args    *argp = &hdr->args;
1397         struct nfs_pgio_res     *resp = &hdr->res;
1398 
1399         if (resp->count < argp->count) {
1400                 static unsigned long    complain;
1401 
1402                 /* This a short write! */
1403                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1404 
1405                 /* Has the server at least made some progress? */
1406                 if (resp->count == 0) {
1407                         if (time_before(complain, jiffies)) {
1408                                 printk(KERN_WARNING
1409                                        "NFS: Server wrote zero bytes, expected %u.\n",
1410                                        argp->count);
1411                                 complain = jiffies + 300 * HZ;
1412                         }
1413                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1414                         task->tk_status = -EIO;
1415                         return;
1416                 }
1417                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1418                 if (resp->verf->committed != NFS_UNSTABLE) {
1419                         /* Resend from where the server left off */
1420                         hdr->mds_offset += resp->count;
1421                         argp->offset += resp->count;
1422                         argp->pgbase += resp->count;
1423                         argp->count -= resp->count;
1424                 } else {
1425                         /* Resend as a stable write in order to avoid
1426                          * headaches in the case of a server crash.
1427                          */
1428                         argp->stable = NFS_FILE_SYNC;
1429                 }
1430                 rpc_restart_call_prepare(task);
1431         }
1432 }
1433 
1434 
1435 static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
1436 {
1437         int ret;
1438 
1439         if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
1440                 return 1;
1441         if (!may_wait)
1442                 return 0;
1443         ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
1444                                 NFS_INO_COMMIT,
1445                                 nfs_wait_bit_killable,
1446                                 TASK_KILLABLE);
1447         return (ret < 0) ? ret : 1;
1448 }
1449 
1450 static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
1451 {
1452         clear_bit(NFS_INO_COMMIT, &nfsi->flags);
1453         smp_mb__after_atomic();
1454         wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
1455 }
1456 
1457 void nfs_commitdata_release(struct nfs_commit_data *data)
1458 {
1459         put_nfs_open_context(data->context);
1460         nfs_commit_free(data);
1461 }
1462 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1463 
1464 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1465                         const struct rpc_call_ops *call_ops,
1466                         int how, int flags)
1467 {
1468         struct rpc_task *task;
1469         int priority = flush_task_priority(how);
1470         struct rpc_message msg = {
1471                 .rpc_argp = &data->args,
1472                 .rpc_resp = &data->res,
1473                 .rpc_cred = data->cred,
1474         };
1475         struct rpc_task_setup task_setup_data = {
1476                 .task = &data->task,
1477                 .rpc_client = clnt,
1478                 .rpc_message = &msg,
1479                 .callback_ops = call_ops,
1480                 .callback_data = data,
1481                 .workqueue = nfsiod_workqueue,
1482                 .flags = RPC_TASK_ASYNC | flags,
1483                 .priority = priority,
1484         };
1485         /* Set up the initial task struct.  */
1486         NFS_PROTO(data->inode)->commit_setup(data, &msg);
1487 
1488         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1489 
1490         nfs4_state_protect(NFS_SERVER(data->inode)->nfs_client,
1491                 NFS_SP4_MACH_CRED_COMMIT, &task_setup_data.rpc_client, &msg);
1492 
1493         task = rpc_run_task(&task_setup_data);
1494         if (IS_ERR(task))
1495                 return PTR_ERR(task);
1496         if (how & FLUSH_SYNC)
1497                 rpc_wait_for_completion_task(task);
1498         rpc_put_task(task);
1499         return 0;
1500 }
1501 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1502 
1503 static loff_t nfs_get_lwb(struct list_head *head)
1504 {
1505         loff_t lwb = 0;
1506         struct nfs_page *req;
1507 
1508         list_for_each_entry(req, head, wb_list)
1509                 if (lwb < (req_offset(req) + req->wb_bytes))
1510                         lwb = req_offset(req) + req->wb_bytes;
1511 
1512         return lwb;
1513 }
1514 
1515 /*
1516  * Set up the argument/result storage required for the RPC call.
1517  */
1518 void nfs_init_commit(struct nfs_commit_data *data,
1519                      struct list_head *head,
1520                      struct pnfs_layout_segment *lseg,
1521                      struct nfs_commit_info *cinfo)
1522 {
1523         struct nfs_page *first = nfs_list_entry(head->next);
1524         struct inode *inode = first->wb_context->dentry->d_inode;
1525 
1526         /* Set up the RPC argument and reply structs
1527          * NB: take care not to mess about with data->commit et al. */
1528 
1529         list_splice_init(head, &data->pages);
1530 
1531         data->inode       = inode;
1532         data->cred        = first->wb_context->cred;
1533         data->lseg        = lseg; /* reference transferred */
1534         /* only set lwb for pnfs commit */
1535         if (lseg)
1536                 data->lwb = nfs_get_lwb(&data->pages);
1537         data->mds_ops     = &nfs_commit_ops;
1538         data->completion_ops = cinfo->completion_ops;
1539         data->dreq        = cinfo->dreq;
1540 
1541         data->args.fh     = NFS_FH(data->inode);
1542         /* Note: we always request a commit of the entire inode */
1543         data->args.offset = 0;
1544         data->args.count  = 0;
1545         data->context     = get_nfs_open_context(first->wb_context);
1546         data->res.fattr   = &data->fattr;
1547         data->res.verf    = &data->verf;
1548         nfs_fattr_init(&data->fattr);
1549 }
1550 EXPORT_SYMBOL_GPL(nfs_init_commit);
1551 
1552 void nfs_retry_commit(struct list_head *page_list,
1553                       struct pnfs_layout_segment *lseg,
1554                       struct nfs_commit_info *cinfo)
1555 {
1556         struct nfs_page *req;
1557 
1558         while (!list_empty(page_list)) {
1559                 req = nfs_list_entry(page_list->next);
1560                 nfs_list_remove_request(req);
1561                 nfs_mark_request_commit(req, lseg, cinfo);
1562                 if (!cinfo->dreq) {
1563                         dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1564                         dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
1565                                      BDI_RECLAIMABLE);
1566                 }
1567                 nfs_unlock_and_release_request(req);
1568         }
1569 }
1570 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1571 
1572 /*
1573  * Commit dirty pages
1574  */
1575 static int
1576 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1577                 struct nfs_commit_info *cinfo)
1578 {
1579         struct nfs_commit_data  *data;
1580 
1581         data = nfs_commitdata_alloc();
1582 
1583         if (!data)
1584                 goto out_bad;
1585 
1586         /* Set up the argument struct */
1587         nfs_init_commit(data, head, NULL, cinfo);
1588         atomic_inc(&cinfo->mds->rpcs_out);
1589         return nfs_initiate_commit(NFS_CLIENT(inode), data, data->mds_ops,
1590                                    how, 0);
1591  out_bad:
1592         nfs_retry_commit(head, NULL, cinfo);
1593         cinfo->completion_ops->error_cleanup(NFS_I(inode));
1594         return -ENOMEM;
1595 }
1596 
1597 /*
1598  * COMMIT call returned
1599  */
1600 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1601 {
1602         struct nfs_commit_data  *data = calldata;
1603 
1604         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1605                                 task->tk_pid, task->tk_status);
1606 
1607         /* Call the NFS version-specific code */
1608         NFS_PROTO(data->inode)->commit_done(task, data);
1609 }
1610 
1611 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1612 {
1613         struct nfs_page *req;
1614         int status = data->task.tk_status;
1615         struct nfs_commit_info cinfo;
1616         struct nfs_server *nfss;
1617 
1618         while (!list_empty(&data->pages)) {
1619                 req = nfs_list_entry(data->pages.next);
1620                 nfs_list_remove_request(req);
1621                 nfs_clear_page_commit(req->wb_page);
1622 
1623                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1624                         req->wb_context->dentry->d_sb->s_id,
1625                         (unsigned long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1626                         req->wb_bytes,
1627                         (long long)req_offset(req));
1628                 if (status < 0) {
1629                         nfs_context_set_write_error(req->wb_context, status);
1630                         nfs_inode_remove_request(req);
1631                         dprintk(", error = %d\n", status);
1632                         goto next;
1633                 }
1634 
1635                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1636                  * returned by the server against all stored verfs. */
1637                 if (!memcmp(&req->wb_verf, &data->verf.verifier, sizeof(req->wb_verf))) {
1638                         /* We have a match */
1639                         nfs_inode_remove_request(req);
1640                         dprintk(" OK\n");
1641                         goto next;
1642                 }
1643                 /* We have a mismatch. Write the page again */
1644                 dprintk(" mismatch\n");
1645                 nfs_mark_request_dirty(req);
1646                 set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1647         next:
1648                 nfs_unlock_and_release_request(req);
1649                 /* Latency breaker */
1650                 cond_resched();
1651         }
1652         nfss = NFS_SERVER(data->inode);
1653         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1654                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
1655 
1656         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1657         if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
1658                 nfs_commit_clear_lock(NFS_I(data->inode));
1659 }
1660 
1661 static void nfs_commit_release(void *calldata)
1662 {
1663         struct nfs_commit_data *data = calldata;
1664 
1665         data->completion_ops->completion(data);
1666         nfs_commitdata_release(calldata);
1667 }
1668 
1669 static const struct rpc_call_ops nfs_commit_ops = {
1670         .rpc_call_prepare = nfs_commit_prepare,
1671         .rpc_call_done = nfs_commit_done,
1672         .rpc_release = nfs_commit_release,
1673 };
1674 
1675 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1676         .completion = nfs_commit_release_pages,
1677         .error_cleanup = nfs_commit_clear_lock,
1678 };
1679 
1680 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1681                             int how, struct nfs_commit_info *cinfo)
1682 {
1683         int status;
1684 
1685         status = pnfs_commit_list(inode, head, how, cinfo);
1686         if (status == PNFS_NOT_ATTEMPTED)
1687                 status = nfs_commit_list(inode, head, how, cinfo);
1688         return status;
1689 }
1690 
1691 int nfs_commit_inode(struct inode *inode, int how)
1692 {
1693         LIST_HEAD(head);
1694         struct nfs_commit_info cinfo;
1695         int may_wait = how & FLUSH_SYNC;
1696         int res;
1697 
1698         res = nfs_commit_set_lock(NFS_I(inode), may_wait);
1699         if (res <= 0)
1700                 goto out_mark_dirty;
1701         nfs_init_cinfo_from_inode(&cinfo, inode);
1702         res = nfs_scan_commit(inode, &head, &cinfo);
1703         if (res) {
1704                 int error;
1705 
1706                 error = nfs_generic_commit_list(inode, &head, how, &cinfo);
1707                 if (error < 0)
1708                         return error;
1709                 if (!may_wait)
1710                         goto out_mark_dirty;
1711                 error = wait_on_bit_action(&NFS_I(inode)->flags,
1712                                 NFS_INO_COMMIT,
1713                                 nfs_wait_bit_killable,
1714                                 TASK_KILLABLE);
1715                 if (error < 0)
1716                         return error;
1717         } else
1718                 nfs_commit_clear_lock(NFS_I(inode));
1719         return res;
1720         /* Note: If we exit without ensuring that the commit is complete,
1721          * we must mark the inode as dirty. Otherwise, future calls to
1722          * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
1723          * that the data is on the disk.
1724          */
1725 out_mark_dirty:
1726         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1727         return res;
1728 }
1729 
1730 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1731 {
1732         struct nfs_inode *nfsi = NFS_I(inode);
1733         int flags = FLUSH_SYNC;
1734         int ret = 0;
1735 
1736         /* no commits means nothing needs to be done */
1737         if (!nfsi->commit_info.ncommit)
1738                 return ret;
1739 
1740         if (wbc->sync_mode == WB_SYNC_NONE) {
1741                 /* Don't commit yet if this is a non-blocking flush and there
1742                  * are a lot of outstanding writes for this mapping.
1743                  */
1744                 if (nfsi->commit_info.ncommit <= (nfsi->npages >> 1))
1745                         goto out_mark_dirty;
1746 
1747                 /* don't wait for the COMMIT response */
1748                 flags = 0;
1749         }
1750 
1751         ret = nfs_commit_inode(inode, flags);
1752         if (ret >= 0) {
1753                 if (wbc->sync_mode == WB_SYNC_NONE) {
1754                         if (ret < wbc->nr_to_write)
1755                                 wbc->nr_to_write -= ret;
1756                         else
1757                                 wbc->nr_to_write = 0;
1758                 }
1759                 return 0;
1760         }
1761 out_mark_dirty:
1762         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1763         return ret;
1764 }
1765 
1766 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1767 {
1768         return nfs_commit_unstable_pages(inode, wbc);
1769 }
1770 EXPORT_SYMBOL_GPL(nfs_write_inode);
1771 
1772 /*
1773  * flush the inode to disk.
1774  */
1775 int nfs_wb_all(struct inode *inode)
1776 {
1777         struct writeback_control wbc = {
1778                 .sync_mode = WB_SYNC_ALL,
1779                 .nr_to_write = LONG_MAX,
1780                 .range_start = 0,
1781                 .range_end = LLONG_MAX,
1782         };
1783         int ret;
1784 
1785         trace_nfs_writeback_inode_enter(inode);
1786 
1787         ret = sync_inode(inode, &wbc);
1788 
1789         trace_nfs_writeback_inode_exit(inode, ret);
1790         return ret;
1791 }
1792 EXPORT_SYMBOL_GPL(nfs_wb_all);
1793 
1794 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1795 {
1796         struct nfs_page *req;
1797         int ret = 0;
1798 
1799         wait_on_page_writeback(page);
1800 
1801         /* blocking call to cancel all requests and join to a single (head)
1802          * request */
1803         req = nfs_lock_and_join_requests(page, false);
1804 
1805         if (IS_ERR(req)) {
1806                 ret = PTR_ERR(req);
1807         } else if (req) {
1808                 /* all requests from this page have been cancelled by
1809                  * nfs_lock_and_join_requests, so just remove the head
1810                  * request from the inode / page_private pointer and
1811                  * release it */
1812                 nfs_inode_remove_request(req);
1813                 /*
1814                  * In case nfs_inode_remove_request has marked the
1815                  * page as being dirty
1816                  */
1817                 cancel_dirty_page(page, PAGE_CACHE_SIZE);
1818                 nfs_unlock_and_release_request(req);
1819         }
1820 
1821         return ret;
1822 }
1823 
1824 /*
1825  * Write back all requests on one page - we do this before reading it.
1826  */
1827 int nfs_wb_page(struct inode *inode, struct page *page)
1828 {
1829         loff_t range_start = page_file_offset(page);
1830         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1831         struct writeback_control wbc = {
1832                 .sync_mode = WB_SYNC_ALL,
1833                 .nr_to_write = 0,
1834                 .range_start = range_start,
1835                 .range_end = range_end,
1836         };
1837         int ret;
1838 
1839         trace_nfs_writeback_page_enter(inode);
1840 
1841         for (;;) {
1842                 wait_on_page_writeback(page);
1843                 if (clear_page_dirty_for_io(page)) {
1844                         ret = nfs_writepage_locked(page, &wbc);
1845                         if (ret < 0)
1846                                 goto out_error;
1847                         continue;
1848                 }
1849                 ret = 0;
1850                 if (!PagePrivate(page))
1851                         break;
1852                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
1853                 if (ret < 0)
1854                         goto out_error;
1855         }
1856 out_error:
1857         trace_nfs_writeback_page_exit(inode, ret);
1858         return ret;
1859 }
1860 
1861 #ifdef CONFIG_MIGRATION
1862 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1863                 struct page *page, enum migrate_mode mode)
1864 {
1865         /*
1866          * If PagePrivate is set, then the page is currently associated with
1867          * an in-progress read or write request. Don't try to migrate it.
1868          *
1869          * FIXME: we could do this in principle, but we'll need a way to ensure
1870          *        that we can safely release the inode reference while holding
1871          *        the page lock.
1872          */
1873         if (PagePrivate(page))
1874                 return -EBUSY;
1875 
1876         if (!nfs_fscache_release_page(page, GFP_KERNEL))
1877                 return -EBUSY;
1878 
1879         return migrate_page(mapping, newpage, page, mode);
1880 }
1881 #endif
1882 
1883 int __init nfs_init_writepagecache(void)
1884 {
1885         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1886                                              sizeof(struct nfs_pgio_header),
1887                                              0, SLAB_HWCACHE_ALIGN,
1888                                              NULL);
1889         if (nfs_wdata_cachep == NULL)
1890                 return -ENOMEM;
1891 
1892         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1893                                                      nfs_wdata_cachep);
1894         if (nfs_wdata_mempool == NULL)
1895                 goto out_destroy_write_cache;
1896 
1897         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
1898                                              sizeof(struct nfs_commit_data),
1899                                              0, SLAB_HWCACHE_ALIGN,
1900                                              NULL);
1901         if (nfs_cdata_cachep == NULL)
1902                 goto out_destroy_write_mempool;
1903 
1904         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1905                                                       nfs_cdata_cachep);
1906         if (nfs_commit_mempool == NULL)
1907                 goto out_destroy_commit_cache;
1908 
1909         /*
1910          * NFS congestion size, scale with available memory.
1911          *
1912          *  64MB:    8192k
1913          * 128MB:   11585k
1914          * 256MB:   16384k
1915          * 512MB:   23170k
1916          *   1GB:   32768k
1917          *   2GB:   46340k
1918          *   4GB:   65536k
1919          *   8GB:   92681k
1920          *  16GB:  131072k
1921          *
1922          * This allows larger machines to have larger/more transfers.
1923          * Limit the default to 256M
1924          */
1925         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1926         if (nfs_congestion_kb > 256*1024)
1927                 nfs_congestion_kb = 256*1024;
1928 
1929         return 0;
1930 
1931 out_destroy_commit_cache:
1932         kmem_cache_destroy(nfs_cdata_cachep);
1933 out_destroy_write_mempool:
1934         mempool_destroy(nfs_wdata_mempool);
1935 out_destroy_write_cache:
1936         kmem_cache_destroy(nfs_wdata_cachep);
1937         return -ENOMEM;
1938 }
1939 
1940 void nfs_destroy_writepagecache(void)
1941 {
1942         mempool_destroy(nfs_commit_mempool);
1943         kmem_cache_destroy(nfs_cdata_cachep);
1944         mempool_destroy(nfs_wdata_mempool);
1945         kmem_cache_destroy(nfs_wdata_cachep);
1946 }
1947 
1948 static const struct nfs_rw_ops nfs_rw_write_ops = {
1949         .rw_mode                = FMODE_WRITE,
1950         .rw_alloc_header        = nfs_writehdr_alloc,
1951         .rw_free_header         = nfs_writehdr_free,
1952         .rw_release             = nfs_writeback_release_common,
1953         .rw_done                = nfs_writeback_done,
1954         .rw_result              = nfs_writeback_result,
1955         .rw_initiate            = nfs_initiate_write,
1956 };
1957 

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