summaryrefslogtreecommitdiffstats
path: root/fs/nfs/file.c
blob: d6a9db0a854550c1df7fe208f1e61cabd0e39f37 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
/*
 *  linux/fs/nfs/file.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  Changes Copyright (C) 1994 by Florian La Roche
 *   - Do not copy data too often around in the kernel.
 *   - In nfs_file_read the return value of kmalloc wasn't checked.
 *   - Put in a better version of read look-ahead buffering. Original idea
 *     and implementation by Wai S Kok elekokws@ee.nus.sg.
 *
 *  Expire cache on write to a file by Wai S Kok (Oct 1994).
 *
 *  Total rewrite of read side for new NFS buffer cache.. Linus.
 *
 *  nfs regular file handling functions
 */

#include <linux/module.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/aio.h>
#include <linux/gfp.h>
#include <linux/swap.h>

#include <asm/uaccess.h>

#include "delegation.h"
#include "internal.h"
#include "iostat.h"
#include "fscache.h"

#include "nfstrace.h"

#define NFSDBG_FACILITY		NFSDBG_FILE

static const struct vm_operations_struct nfs_file_vm_ops;

/* Hack for future NFS swap support */
#ifndef IS_SWAPFILE
# define IS_SWAPFILE(inode)	(0)
#endif

int nfs_check_flags(int flags)
{
	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
		return -EINVAL;

	return 0;
}
EXPORT_SYMBOL_GPL(nfs_check_flags);

/*
 * Open file
 */
static int
nfs_file_open(struct inode *inode, struct file *filp)
{
	int res;

	dprintk("NFS: open file(%s/%s)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name);

	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
	res = nfs_check_flags(filp->f_flags);
	if (res)
		return res;

	res = nfs_open(inode, filp);
	return res;
}

int
nfs_file_release(struct inode *inode, struct file *filp)
{
	dprintk("NFS: release(%s/%s)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name);

	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
	return nfs_release(inode, filp);
}
EXPORT_SYMBOL_GPL(nfs_file_release);

/**
 * nfs_revalidate_size - Revalidate the file size
 * @inode - pointer to inode struct
 * @file - pointer to struct file
 *
 * Revalidates the file length. This is basically a wrapper around
 * nfs_revalidate_inode() that takes into account the fact that we may
 * have cached writes (in which case we don't care about the server's
 * idea of what the file length is), or O_DIRECT (in which case we
 * shouldn't trust the cache).
 */
static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
{
	struct nfs_server *server = NFS_SERVER(inode);
	struct nfs_inode *nfsi = NFS_I(inode);

	if (nfs_have_delegated_attributes(inode))
		goto out_noreval;

	if (filp->f_flags & O_DIRECT)
		goto force_reval;
	if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
		goto force_reval;
	if (nfs_attribute_timeout(inode))
		goto force_reval;
out_noreval:
	return 0;
force_reval:
	return __nfs_revalidate_inode(server, inode);
}

loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
{
	dprintk("NFS: llseek file(%s/%s, %lld, %d)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name,
			offset, whence);

	/*
	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
	 * the cached file length
	 */
	if (whence != SEEK_SET && whence != SEEK_CUR) {
		struct inode *inode = filp->f_mapping->host;

		int retval = nfs_revalidate_file_size(inode, filp);
		if (retval < 0)
			return (loff_t)retval;
	}

	return generic_file_llseek(filp, offset, whence);
}
EXPORT_SYMBOL_GPL(nfs_file_llseek);

/*
 * Flush all dirty pages, and check for write errors.
 */
int
nfs_file_flush(struct file *file, fl_owner_t id)
{
	struct dentry	*dentry = file->f_path.dentry;
	struct inode	*inode = dentry->d_inode;

	dprintk("NFS: flush(%s/%s)\n",
			dentry->d_parent->d_name.name,
			dentry->d_name.name);

	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
	if ((file->f_mode & FMODE_WRITE) == 0)
		return 0;

	/*
	 * If we're holding a write delegation, then just start the i/o
	 * but don't wait for completion (or send a commit).
	 */
	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
		return filemap_fdatawrite(file->f_mapping);

	/* Flush writes to the server and return any errors */
	return vfs_fsync(file, 0);
}
EXPORT_SYMBOL_GPL(nfs_file_flush);

ssize_t
nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
		unsigned long nr_segs, loff_t pos)
{
	struct dentry * dentry = iocb->ki_filp->f_path.dentry;
	struct inode * inode = dentry->d_inode;
	ssize_t result;

	if (iocb->ki_filp->f_flags & O_DIRECT)
		return nfs_file_direct_read(iocb, iov, nr_segs, pos, true);

	dprintk("NFS: read(%s/%s, %lu@%lu)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		(unsigned long) iov_length(iov, nr_segs), (unsigned long) pos);

	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
	if (!result) {
		result = generic_file_aio_read(iocb, iov, nr_segs, pos);
		if (result > 0)
			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
	}
	return result;
}
EXPORT_SYMBOL_GPL(nfs_file_read);

ssize_t
nfs_file_splice_read(struct file *filp, loff_t *ppos,
		     struct pipe_inode_info *pipe, size_t count,
		     unsigned int flags)
{
	struct dentry *dentry = filp->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	ssize_t res;

	dprintk("NFS: splice_read(%s/%s, %lu@%Lu)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		(unsigned long) count, (unsigned long long) *ppos);

	res = nfs_revalidate_mapping(inode, filp->f_mapping);
	if (!res) {
		res = generic_file_splice_read(filp, ppos, pipe, count, flags);
		if (res > 0)
			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, res);
	}
	return res;
}
EXPORT_SYMBOL_GPL(nfs_file_splice_read);

int
nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
{
	struct dentry *dentry = file->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	int	status;

	dprintk("NFS: mmap(%s/%s)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name);

	/* Note: generic_file_mmap() returns ENOSYS on nommu systems
	 *       so we call that before revalidating the mapping
	 */
	status = generic_file_mmap(file, vma);
	if (!status) {
		vma->vm_ops = &nfs_file_vm_ops;
		status = nfs_revalidate_mapping(inode, file->f_mapping);
	}
	return status;
}
EXPORT_SYMBOL_GPL(nfs_file_mmap);

/*
 * Flush any dirty pages for this process, and check for write errors.
 * The return status from this call provides a reliable indication of
 * whether any write errors occurred for this process.
 *
 * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
 * disk, but it retrieves and clears ctx->error after synching, despite
 * the two being set at the same time in nfs_context_set_write_error().
 * This is because the former is used to notify the _next_ call to
 * nfs_file_write() that a write error occurred, and hence cause it to
 * fall back to doing a synchronous write.
 */
int
nfs_file_fsync_commit(struct file *file, loff_t start, loff_t end, int datasync)
{
	struct dentry *dentry = file->f_path.dentry;
	struct nfs_open_context *ctx = nfs_file_open_context(file);
	struct inode *inode = dentry->d_inode;
	int have_error, do_resend, status;
	int ret = 0;

	dprintk("NFS: fsync file(%s/%s) datasync %d\n",
			dentry->d_parent->d_name.name, dentry->d_name.name,
			datasync);

	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
	do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
	have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
	status = nfs_commit_inode(inode, FLUSH_SYNC);
	have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
	if (have_error) {
		ret = xchg(&ctx->error, 0);
		if (ret)
			goto out;
	}
	if (status < 0) {
		ret = status;
		goto out;
	}
	do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
	if (do_resend)
		ret = -EAGAIN;
out:
	return ret;
}
EXPORT_SYMBOL_GPL(nfs_file_fsync_commit);

static int
nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
	int ret;
	struct inode *inode = file_inode(file);

	trace_nfs_fsync_enter(inode);

	do {
		ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
		if (ret != 0)
			break;
		mutex_lock(&inode->i_mutex);
		ret = nfs_file_fsync_commit(file, start, end, datasync);
		mutex_unlock(&inode->i_mutex);
		/*
		 * If nfs_file_fsync_commit detected a server reboot, then
		 * resend all dirty pages that might have been covered by
		 * the NFS_CONTEXT_RESEND_WRITES flag
		 */
		start = 0;
		end = LLONG_MAX;
	} while (ret == -EAGAIN);

	trace_nfs_fsync_exit(inode, ret);
	return ret;
}

/*
 * Decide whether a read/modify/write cycle may be more efficient
 * then a modify/write/read cycle when writing to a page in the
 * page cache.
 *
 * The modify/write/read cycle may occur if a page is read before
 * being completely filled by the writer.  In this situation, the
 * page must be completely written to stable storage on the server
 * before it can be refilled by reading in the page from the server.
 * This can lead to expensive, small, FILE_SYNC mode writes being
 * done.
 *
 * It may be more efficient to read the page first if the file is
 * open for reading in addition to writing, the page is not marked
 * as Uptodate, it is not dirty or waiting to be committed,
 * indicating that it was previously allocated and then modified,
 * that there were valid bytes of data in that range of the file,
 * and that the new data won't completely replace the old data in
 * that range of the file.
 */
static int nfs_want_read_modify_write(struct file *file, struct page *page,
			loff_t pos, unsigned len)
{
	unsigned int pglen = nfs_page_length(page);
	unsigned int offset = pos & (PAGE_CACHE_SIZE - 1);
	unsigned int end = offset + len;

	if ((file->f_mode & FMODE_READ) &&	/* open for read? */
	    !PageUptodate(page) &&		/* Uptodate? */
	    !PagePrivate(page) &&		/* i/o request already? */
	    pglen &&				/* valid bytes of file? */
	    (end < pglen || offset))		/* replace all valid bytes? */
		return 1;
	return 0;
}

/*
 * This does the "real" work of the write. We must allocate and lock the
 * page to be sent back to the generic routine, which then copies the
 * data from user space.
 *
 * If the writer ends up delaying the write, the writer needs to
 * increment the page use counts until he is done with the page.
 */
static int nfs_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
{
	int ret;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	struct page *page;
	int once_thru = 0;

	dfprintk(PAGECACHE, "NFS: write_begin(%s/%s(%ld), %u@%lld)\n",
		file->f_path.dentry->d_parent->d_name.name,
		file->f_path.dentry->d_name.name,
		mapping->host->i_ino, len, (long long) pos);

start:
	/*
	 * Prevent starvation issues if someone is doing a consistency
	 * sync-to-disk
	 */
	ret = wait_on_bit(&NFS_I(mapping->host)->flags, NFS_INO_FLUSHING,
			nfs_wait_bit_killable, TASK_KILLABLE);
	if (ret)
		return ret;

	page = grab_cache_page_write_begin(mapping, index, flags);
	if (!page)
		return -ENOMEM;
	*pagep = page;

	ret = nfs_flush_incompatible(file, page);
	if (ret) {
		unlock_page(page);
		page_cache_release(page);
	} else if (!once_thru &&
		   nfs_want_read_modify_write(file, page, pos, len)) {
		once_thru = 1;
		ret = nfs_readpage(file, page);
		page_cache_release(page);
		if (!ret)
			goto start;
	}
	return ret;
}

static int nfs_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
{
	unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
	int status;

	dfprintk(PAGECACHE, "NFS: write_end(%s/%s(%ld), %u@%lld)\n",
		file->f_path.dentry->d_parent->d_name.name,
		file->f_path.dentry->d_name.name,
		mapping->host->i_ino, len, (long long) pos);

	/*
	 * Zero any uninitialised parts of the page, and then mark the page
	 * as up to date if it turns out that we're extending the file.
	 */
	if (!PageUptodate(page)) {
		unsigned pglen = nfs_page_length(page);
		unsigned end = offset + len;

		if (pglen == 0) {
			zero_user_segments(page, 0, offset,
					end, PAGE_CACHE_SIZE);
			SetPageUptodate(page);
		} else if (end >= pglen) {
			zero_user_segment(page, end, PAGE_CACHE_SIZE);
			if (offset == 0)
				SetPageUptodate(page);
		} else
			zero_user_segment(page, pglen, PAGE_CACHE_SIZE);
	}

	status = nfs_updatepage(file, page, offset, copied);

	unlock_page(page);
	page_cache_release(page);

	if (status < 0)
		return status;
	NFS_I(mapping->host)->write_io += copied;
	return copied;
}

/*
 * Partially or wholly invalidate a page
 * - Release the private state associated with a page if undergoing complete
 *   page invalidation
 * - Called if either PG_private or PG_fscache is set on the page
 * - Caller holds page lock
 */
static void nfs_invalidate_page(struct page *page, unsigned int offset,
				unsigned int length)
{
	dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
		 page, offset, length);

	if (offset != 0 || length < PAGE_CACHE_SIZE)
		return;
	/* Cancel any unstarted writes on this page */
	nfs_wb_page_cancel(page_file_mapping(page)->host, page);

	nfs_fscache_invalidate_page(page, page->mapping->host);
}

/*
 * Attempt to release the private state associated with a page
 * - Called if either PG_private or PG_fscache is set on the page
 * - Caller holds page lock
 * - Return true (may release page) or false (may not)
 */
static int nfs_release_page(struct page *page, gfp_t gfp)
{
	struct address_space *mapping = page->mapping;

	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);

	/* Only do I/O if gfp is a superset of GFP_KERNEL, and we're not
	 * doing this memory reclaim for a fs-related allocation.
	 */
	if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL &&
	    !(current->flags & PF_FSTRANS)) {
		int how = FLUSH_SYNC;

		/* Don't let kswapd deadlock waiting for OOM RPC calls */
		if (current_is_kswapd())
			how = 0;
		nfs_commit_inode(mapping->host, how);
	}
	/* If PagePrivate() is set, then the page is not freeable */
	if (PagePrivate(page))
		return 0;
	return nfs_fscache_release_page(page, gfp);
}

static void nfs_check_dirty_writeback(struct page *page,
				bool *dirty, bool *writeback)
{
	struct nfs_inode *nfsi;
	struct address_space *mapping = page_file_mapping(page);

	if (!mapping || PageSwapCache(page))
		return;

	/*
	 * Check if an unstable page is currently being committed and
	 * if so, have the VM treat it as if the page is under writeback
	 * so it will not block due to pages that will shortly be freeable.
	 */
	nfsi = NFS_I(mapping->host);
	if (test_bit(NFS_INO_COMMIT, &nfsi->flags)) {
		*writeback = true;
		return;
	}

	/*
	 * If PagePrivate() is set, then the page is not freeable and as the
	 * inode is not being committed, it's not going to be cleaned in the
	 * near future so treat it as dirty
	 */
	if (PagePrivate(page))
		*dirty = true;
}

/*
 * Attempt to clear the private state associated with a page when an error
 * occurs that requires the cached contents of an inode to be written back or
 * destroyed
 * - Called if either PG_private or fscache is set on the page
 * - Caller holds page lock
 * - Return 0 if successful, -error otherwise
 */
static int nfs_launder_page(struct page *page)
{
	struct inode *inode = page_file_mapping(page)->host;
	struct nfs_inode *nfsi = NFS_I(inode);

	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
		inode->i_ino, (long long)page_offset(page));

	nfs_fscache_wait_on_page_write(nfsi, page);
	return nfs_wb_page(inode, page);
}

#ifdef CONFIG_NFS_SWAP
static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
						sector_t *span)
{
	*span = sis->pages;
	return xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 1);
}

static void nfs_swap_deactivate(struct file *file)
{
	xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 0);
}
#endif

const struct address_space_operations nfs_file_aops = {
	.readpage = nfs_readpage,
	.readpages = nfs_readpages,
	.set_page_dirty = __set_page_dirty_nobuffers,
	.writepage = nfs_writepage,
	.writepages = nfs_writepages,
	.write_begin = nfs_write_begin,
	.write_end = nfs_write_end,
	.invalidatepage = nfs_invalidate_page,
	.releasepage = nfs_release_page,
	.direct_IO = nfs_direct_IO,
	.migratepage = nfs_migrate_page,
	.launder_page = nfs_launder_page,
	.is_dirty_writeback = nfs_check_dirty_writeback,
	.error_remove_page = generic_error_remove_page,
#ifdef CONFIG_NFS_SWAP
	.swap_activate = nfs_swap_activate,
	.swap_deactivate = nfs_swap_deactivate,
#endif
};

/*
 * Notification that a PTE pointing to an NFS page is about to be made
 * writable, implying that someone is about to modify the page through a
 * shared-writable mapping
 */
static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct page *page = vmf->page;
	struct file *filp = vma->vm_file;
	struct dentry *dentry = filp->f_path.dentry;
	unsigned pagelen;
	int ret = VM_FAULT_NOPAGE;
	struct address_space *mapping;

	dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%s/%s(%ld), offset %lld)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		filp->f_mapping->host->i_ino,
		(long long)page_offset(page));

	/* make sure the cache has finished storing the page */
	nfs_fscache_wait_on_page_write(NFS_I(dentry->d_inode), page);

	lock_page(page);
	mapping = page_file_mapping(page);
	if (mapping != dentry->d_inode->i_mapping)
		goto out_unlock;

	wait_on_page_writeback(page);

	pagelen = nfs_page_length(page);
	if (pagelen == 0)
		goto out_unlock;

	ret = VM_FAULT_LOCKED;
	if (nfs_flush_incompatible(filp, page) == 0 &&
	    nfs_updatepage(filp, page, 0, pagelen) == 0)
		goto out;

	ret = VM_FAULT_SIGBUS;
out_unlock:
	unlock_page(page);
out:
	return ret;
}

static const struct vm_operations_struct nfs_file_vm_ops = {
	.fault = filemap_fault,
	.page_mkwrite = nfs_vm_page_mkwrite,
	.remap_pages = generic_file_remap_pages,
};

static int nfs_need_sync_write(struct file *filp, struct inode *inode)
{
	struct nfs_open_context *ctx;

	if (IS_SYNC(inode) || (filp->f_flags & O_DSYNC))
		return 1;
	ctx = nfs_file_open_context(filp);
	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
		return 1;
	return 0;
}

ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
		       unsigned long nr_segs, loff_t pos)
{
	struct dentry * dentry = iocb->ki_filp->f_path.dentry;
	struct inode * inode = dentry->d_inode;
	unsigned long written = 0;
	ssize_t result;
	size_t count = iov_length(iov, nr_segs);

	if (iocb->ki_filp->f_flags & O_DIRECT)
		return nfs_file_direct_write(iocb, iov, nr_segs, pos, true);

	dprintk("NFS: write(%s/%s, %lu@%Ld)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		(unsigned long) count, (long long) pos);

	result = -EBUSY;
	if (IS_SWAPFILE(inode))
		goto out_swapfile;
	/*
	 * O_APPEND implies that we must revalidate the file length.
	 */
	if (iocb->ki_filp->f_flags & O_APPEND) {
		result = nfs_revalidate_file_size(inode, iocb->ki_filp);
		if (result)
			goto out;
	}

	result = count;
	if (!count)
		goto out;

	result = generic_file_aio_write(iocb, iov, nr_segs, pos);
	if (result > 0)
		written = result;

	/* Return error values for O_DSYNC and IS_SYNC() */
	if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
		int err = vfs_fsync(iocb->ki_filp, 0);
		if (err < 0)
			result = err;
	}
	if (result > 0)
		nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
out:
	return result;

out_swapfile:
	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
	goto out;
}
EXPORT_SYMBOL_GPL(nfs_file_write);

ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
			      struct file *filp, loff_t *ppos,
			      size_t count, unsigned int flags)
{
	struct dentry *dentry = filp->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	unsigned long written = 0;
	ssize_t ret;

	dprintk("NFS splice_write(%s/%s, %lu@%llu)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		(unsigned long) count, (unsigned long long) *ppos);

	/*
	 * The combination of splice and an O_APPEND destination is disallowed.
	 */

	ret = generic_file_splice_write(pipe, filp, ppos, count, flags);
	if (ret > 0)
		written = ret;

	if (ret >= 0 && nfs_need_sync_write(filp, inode)) {
		int err = vfs_fsync(filp, 0);
		if (err < 0)
			ret = err;
	}
	if (ret > 0)
		nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
	return ret;
}
EXPORT_SYMBOL_GPL(nfs_file_splice_write);

static int
do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
	struct inode *inode = filp->f_mapping->host;
	int status = 0;
	unsigned int saved_type = fl->fl_type;

	/* Try local locking first */
	posix_test_lock(filp, fl);
	if (fl->fl_type != F_UNLCK) {
		/* found a conflict */
		goto out;
	}
	fl->fl_type = saved_type;

	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
		goto out_noconflict;

	if (is_local)
		goto out_noconflict;

	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
out:
	return status;
out_noconflict:
	fl->fl_type = F_UNLCK;
	goto out;
}

static int do_vfs_lock(struct file *file, struct file_lock *fl)
{
	int res = 0;
	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
		case FL_POSIX:
			res = posix_lock_file_wait(file, fl);
			break;
		case FL_FLOCK:
			res = flock_lock_file_wait(file, fl);
			break;
		default:
			BUG();
	}
	return res;
}

static int
do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
	struct inode *inode = filp->f_mapping->host;
	struct nfs_lock_context *l_ctx;
	int status;

	/*
	 * Flush all pending writes before doing anything
	 * with locks..
	 */
	nfs_sync_mapping(filp->f_mapping);

	l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
	if (!IS_ERR(l_ctx)) {
		status = nfs_iocounter_wait(&l_ctx->io_count);
		nfs_put_lock_context(l_ctx);
		if (status < 0)
			return status;
	}

	/* NOTE: special case
	 * 	If we're signalled while cleaning up locks on process exit, we
	 * 	still need to complete the unlock.
	 */
	/*
	 * Use local locking if mounted with "-onolock" or with appropriate
	 * "-olocal_lock="
	 */
	if (!is_local)
		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
	else
		status = do_vfs_lock(filp, fl);
	return status;
}

static int
is_time_granular(struct timespec *ts) {
	return ((ts->tv_sec == 0) && (ts->tv_nsec <= 1000));
}

static int
do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
	struct inode *inode = filp->f_mapping->host;
	int status;

	/*
	 * Flush all pending writes before doing anything
	 * with locks..
	 */
	status = nfs_sync_mapping(filp->f_mapping);
	if (status != 0)
		goto out;

	/*
	 * Use local locking if mounted with "-onolock" or with appropriate
	 * "-olocal_lock="
	 */
	if (!is_local)
		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
	else
		status = do_vfs_lock(filp, fl);
	if (status < 0)
		goto out;

	/*
	 * Revalidate the cache if the server has time stamps granular
	 * enough to detect subsecond changes.  Otherwise, clear the
	 * cache to prevent missing any changes.
	 *
	 * This makes locking act as a cache coherency point.
	 */
	nfs_sync_mapping(filp->f_mapping);
	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
		if (is_time_granular(&NFS_SERVER(inode)->time_delta))
			__nfs_revalidate_inode(NFS_SERVER(inode), inode);
		else
			nfs_zap_caches(inode);
	}
out:
	return status;
}

/*
 * Lock a (portion of) a file
 */
int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
{
	struct inode *inode = filp->f_mapping->host;
	int ret = -ENOLCK;
	int is_local = 0;

	dprintk("NFS: lock(%s/%s, t=%x, fl=%x, r=%lld:%lld)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name,
			fl->fl_type, fl->fl_flags,
			(long long)fl->fl_start, (long long)fl->fl_end);

	nfs_inc_stats(inode, NFSIOS_VFSLOCK);

	/* No mandatory locks over NFS */
	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
		goto out_err;

	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
		is_local = 1;

	if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
		ret = NFS_PROTO(inode)->lock_check_bounds(fl);
		if (ret < 0)
			goto out_err;
	}

	if (IS_GETLK(cmd))
		ret = do_getlk(filp, cmd, fl, is_local);
	else if (fl->fl_type == F_UNLCK)
		ret = do_unlk(filp, cmd, fl, is_local);
	else
		ret = do_setlk(filp, cmd, fl, is_local);
out_err:
	return ret;
}
EXPORT_SYMBOL_GPL(nfs_lock);

/*
 * Lock a (portion of) a file
 */
int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
{
	struct inode *inode = filp->f_mapping->host;
	int is_local = 0;

	dprintk("NFS: flock(%s/%s, t=%x, fl=%x)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name,
			fl->fl_type, fl->fl_flags);

	if (!(fl->fl_flags & FL_FLOCK))
		return -ENOLCK;

	/*
	 * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
	 * any standard. In principle we might be able to support LOCK_MAND
	 * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
	 * NFS code is not set up for it.
	 */
	if (fl->fl_type & LOCK_MAND)
		return -EINVAL;

	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
		is_local = 1;

	/* We're simulating flock() locks using posix locks on the server */
	fl->fl_owner = (fl_owner_t)filp;
	fl->fl_start = 0;
	fl->fl_end = OFFSET_MAX;

	if (fl->fl_type == F_UNLCK)
		return do_unlk(filp, cmd, fl, is_local);
	return do_setlk(filp, cmd, fl, is_local);
}
EXPORT_SYMBOL_GPL(nfs_flock);

/*
 * There is no protocol support for leases, so we have no way to implement
 * them correctly in the face of opens by other clients.
 */
int nfs_setlease(struct file *file, long arg, struct file_lock **fl)
{
	dprintk("NFS: setlease(%s/%s, arg=%ld)\n",
			file->f_path.dentry->d_parent->d_name.name,
			file->f_path.dentry->d_name.name, arg);
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(nfs_setlease);

const struct file_operations nfs_file_operations = {
	.llseek		= nfs_file_llseek,
	.read		= do_sync_read,
	.write		= do_sync_write,
	.aio_read	= nfs_file_read,
	.aio_write	= nfs_file_write,
	.mmap		= nfs_file_mmap,
	.open		= nfs_file_open,
	.flush		= nfs_file_flush,
	.release	= nfs_file_release,
	.fsync		= nfs_file_fsync,
	.lock		= nfs_lock,
	.flock		= nfs_flock,
	.splice_read	= nfs_file_splice_read,
	.splice_write	= nfs_file_splice_write,
	.check_flags	= nfs_check_flags,
	.setlease	= nfs_setlease,
};
EXPORT_SYMBOL_GPL(nfs_file_operations);
OpenPOWER on IntegriCloud