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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/fs/nfs/file.c
4  *
5  *  Copyright (C) 1992  Rick Sladkey
6  *
7  *  Changes Copyright (C) 1994 by Florian La Roche
8  *   - Do not copy data too often around in the kernel.
9  *   - In nfs_file_read the return value of kmalloc wasn't checked.
10  *   - Put in a better version of read look-ahead buffering. Original idea
11  *     and implementation by Wai S Kok elekokws@ee.nus.sg.
12  *
13  *  Expire cache on write to a file by Wai S Kok (Oct 1994).
14  *
15  *  Total rewrite of read side for new NFS buffer cache.. Linus.
16  *
17  *  nfs regular file handling functions
18  */
19 
20 #include <linux/module.h>
21 #include <linux/time.h>
22 #include <linux/kernel.h>
23 #include <linux/errno.h>
24 #include <linux/fcntl.h>
25 #include <linux/stat.h>
26 #include <linux/nfs_fs.h>
27 #include <linux/nfs_mount.h>
28 #include <linux/mm.h>
29 #include <linux/pagemap.h>
30 #include <linux/gfp.h>
31 #include <linux/swap.h>
32 
33 #include <linux/uaccess.h>
34 
35 #include "delegation.h"
36 #include "internal.h"
37 #include "iostat.h"
38 #include "fscache.h"
39 #include "pnfs.h"
40 
41 #include "nfstrace.h"
42 
43 #define NFSDBG_FACILITY		NFSDBG_FILE
44 
45 static const struct vm_operations_struct nfs_file_vm_ops;
46 
nfs_check_flags(int flags)47 int nfs_check_flags(int flags)
48 {
49 	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
50 		return -EINVAL;
51 
52 	return 0;
53 }
54 EXPORT_SYMBOL_GPL(nfs_check_flags);
55 
56 /*
57  * Open file
58  */
59 static int
nfs_file_open(struct inode * inode,struct file * filp)60 nfs_file_open(struct inode *inode, struct file *filp)
61 {
62 	int res;
63 
64 	dprintk("NFS: open file(%pD2)\n", filp);
65 
66 	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
67 	res = nfs_check_flags(filp->f_flags);
68 	if (res)
69 		return res;
70 
71 	res = nfs_open(inode, filp);
72 	if (res == 0)
73 		filp->f_mode |= FMODE_CAN_ODIRECT;
74 	return res;
75 }
76 
77 int
nfs_file_release(struct inode * inode,struct file * filp)78 nfs_file_release(struct inode *inode, struct file *filp)
79 {
80 	dprintk("NFS: release(%pD2)\n", filp);
81 
82 	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
83 	nfs_file_clear_open_context(filp);
84 	nfs_fscache_release_file(inode, filp);
85 	return 0;
86 }
87 EXPORT_SYMBOL_GPL(nfs_file_release);
88 
89 /**
90  * nfs_revalidate_file_size - Revalidate the file size
91  * @inode: pointer to inode struct
92  * @filp: pointer to struct file
93  *
94  * Revalidates the file length. This is basically a wrapper around
95  * nfs_revalidate_inode() that takes into account the fact that we may
96  * have cached writes (in which case we don't care about the server's
97  * idea of what the file length is), or O_DIRECT (in which case we
98  * shouldn't trust the cache).
99  */
nfs_revalidate_file_size(struct inode * inode,struct file * filp)100 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
101 {
102 	struct nfs_server *server = NFS_SERVER(inode);
103 
104 	if (filp->f_flags & O_DIRECT)
105 		goto force_reval;
106 	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_SIZE))
107 		goto force_reval;
108 	return 0;
109 force_reval:
110 	return __nfs_revalidate_inode(server, inode);
111 }
112 
nfs_file_llseek(struct file * filp,loff_t offset,int whence)113 loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
114 {
115 	dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
116 			filp, offset, whence);
117 
118 	/*
119 	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
120 	 * the cached file length
121 	 */
122 	if (whence != SEEK_SET && whence != SEEK_CUR) {
123 		struct inode *inode = filp->f_mapping->host;
124 
125 		int retval = nfs_revalidate_file_size(inode, filp);
126 		if (retval < 0)
127 			return (loff_t)retval;
128 	}
129 
130 	return generic_file_llseek(filp, offset, whence);
131 }
132 EXPORT_SYMBOL_GPL(nfs_file_llseek);
133 
134 /*
135  * Flush all dirty pages, and check for write errors.
136  */
137 static int
nfs_file_flush(struct file * file,fl_owner_t id)138 nfs_file_flush(struct file *file, fl_owner_t id)
139 {
140 	struct inode	*inode = file_inode(file);
141 	errseq_t since;
142 
143 	dprintk("NFS: flush(%pD2)\n", file);
144 
145 	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
146 	if ((file->f_mode & FMODE_WRITE) == 0)
147 		return 0;
148 
149 	/* Flush writes to the server and return any errors */
150 	since = filemap_sample_wb_err(file->f_mapping);
151 	nfs_wb_all(inode);
152 	return filemap_check_wb_err(file->f_mapping, since);
153 }
154 
155 ssize_t
nfs_file_read(struct kiocb * iocb,struct iov_iter * to)156 nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
157 {
158 	struct inode *inode = file_inode(iocb->ki_filp);
159 	ssize_t result;
160 
161 	if (iocb->ki_flags & IOCB_DIRECT)
162 		return nfs_file_direct_read(iocb, to, false);
163 
164 	dprintk("NFS: read(%pD2, %zu@%lu)\n",
165 		iocb->ki_filp,
166 		iov_iter_count(to), (unsigned long) iocb->ki_pos);
167 
168 	nfs_start_io_read(inode);
169 	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
170 	if (!result) {
171 		result = generic_file_read_iter(iocb, to);
172 		if (result > 0)
173 			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
174 	}
175 	nfs_end_io_read(inode);
176 	return result;
177 }
178 EXPORT_SYMBOL_GPL(nfs_file_read);
179 
180 int
nfs_file_mmap(struct file * file,struct vm_area_struct * vma)181 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
182 {
183 	struct inode *inode = file_inode(file);
184 	int	status;
185 
186 	dprintk("NFS: mmap(%pD2)\n", file);
187 
188 	/* Note: generic_file_mmap() returns ENOSYS on nommu systems
189 	 *       so we call that before revalidating the mapping
190 	 */
191 	status = generic_file_mmap(file, vma);
192 	if (!status) {
193 		vma->vm_ops = &nfs_file_vm_ops;
194 		status = nfs_revalidate_mapping(inode, file->f_mapping);
195 	}
196 	return status;
197 }
198 EXPORT_SYMBOL_GPL(nfs_file_mmap);
199 
200 /*
201  * Flush any dirty pages for this process, and check for write errors.
202  * The return status from this call provides a reliable indication of
203  * whether any write errors occurred for this process.
204  */
205 static int
nfs_file_fsync_commit(struct file * file,int datasync)206 nfs_file_fsync_commit(struct file *file, int datasync)
207 {
208 	struct inode *inode = file_inode(file);
209 	int ret, ret2;
210 
211 	dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
212 
213 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
214 	ret = nfs_commit_inode(inode, FLUSH_SYNC);
215 	ret2 = file_check_and_advance_wb_err(file);
216 	if (ret2 < 0)
217 		return ret2;
218 	return ret;
219 }
220 
221 int
nfs_file_fsync(struct file * file,loff_t start,loff_t end,int datasync)222 nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
223 {
224 	struct inode *inode = file_inode(file);
225 	struct nfs_inode *nfsi = NFS_I(inode);
226 	long save_nredirtied = atomic_long_read(&nfsi->redirtied_pages);
227 	long nredirtied;
228 	int ret;
229 
230 	trace_nfs_fsync_enter(inode);
231 
232 	for (;;) {
233 		ret = file_write_and_wait_range(file, start, end);
234 		if (ret != 0)
235 			break;
236 		ret = nfs_file_fsync_commit(file, datasync);
237 		if (ret != 0)
238 			break;
239 		ret = pnfs_sync_inode(inode, !!datasync);
240 		if (ret != 0)
241 			break;
242 		nredirtied = atomic_long_read(&nfsi->redirtied_pages);
243 		if (nredirtied == save_nredirtied)
244 			break;
245 		save_nredirtied = nredirtied;
246 	}
247 
248 	trace_nfs_fsync_exit(inode, ret);
249 	return ret;
250 }
251 EXPORT_SYMBOL_GPL(nfs_file_fsync);
252 
253 /*
254  * Decide whether a read/modify/write cycle may be more efficient
255  * then a modify/write/read cycle when writing to a page in the
256  * page cache.
257  *
258  * Some pNFS layout drivers can only read/write at a certain block
259  * granularity like all block devices and therefore we must perform
260  * read/modify/write whenever a page hasn't read yet and the data
261  * to be written there is not aligned to a block boundary and/or
262  * smaller than the block size.
263  *
264  * The modify/write/read cycle may occur if a page is read before
265  * being completely filled by the writer.  In this situation, the
266  * page must be completely written to stable storage on the server
267  * before it can be refilled by reading in the page from the server.
268  * This can lead to expensive, small, FILE_SYNC mode writes being
269  * done.
270  *
271  * It may be more efficient to read the page first if the file is
272  * open for reading in addition to writing, the page is not marked
273  * as Uptodate, it is not dirty or waiting to be committed,
274  * indicating that it was previously allocated and then modified,
275  * that there were valid bytes of data in that range of the file,
276  * and that the new data won't completely replace the old data in
277  * that range of the file.
278  */
nfs_full_page_write(struct page * page,loff_t pos,unsigned int len)279 static bool nfs_full_page_write(struct page *page, loff_t pos, unsigned int len)
280 {
281 	unsigned int pglen = nfs_page_length(page);
282 	unsigned int offset = pos & (PAGE_SIZE - 1);
283 	unsigned int end = offset + len;
284 
285 	return !pglen || (end >= pglen && !offset);
286 }
287 
nfs_want_read_modify_write(struct file * file,struct page * page,loff_t pos,unsigned int len)288 static bool nfs_want_read_modify_write(struct file *file, struct page *page,
289 			loff_t pos, unsigned int len)
290 {
291 	/*
292 	 * Up-to-date pages, those with ongoing or full-page write
293 	 * don't need read/modify/write
294 	 */
295 	if (PageUptodate(page) || PagePrivate(page) ||
296 	    nfs_full_page_write(page, pos, len))
297 		return false;
298 
299 	if (pnfs_ld_read_whole_page(file->f_mapping->host))
300 		return true;
301 	/* Open for reading too? */
302 	if (file->f_mode & FMODE_READ)
303 		return true;
304 	return false;
305 }
306 
307 /*
308  * This does the "real" work of the write. We must allocate and lock the
309  * page to be sent back to the generic routine, which then copies the
310  * data from user space.
311  *
312  * If the writer ends up delaying the write, the writer needs to
313  * increment the page use counts until he is done with the page.
314  */
nfs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,struct page ** pagep,void ** fsdata)315 static int nfs_write_begin(struct file *file, struct address_space *mapping,
316 			loff_t pos, unsigned len,
317 			struct page **pagep, void **fsdata)
318 {
319 	int ret;
320 	pgoff_t index = pos >> PAGE_SHIFT;
321 	struct page *page;
322 	int once_thru = 0;
323 
324 	dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n",
325 		file, mapping->host->i_ino, len, (long long) pos);
326 
327 start:
328 	page = grab_cache_page_write_begin(mapping, index);
329 	if (!page)
330 		return -ENOMEM;
331 	*pagep = page;
332 
333 	ret = nfs_flush_incompatible(file, page);
334 	if (ret) {
335 		unlock_page(page);
336 		put_page(page);
337 	} else if (!once_thru &&
338 		   nfs_want_read_modify_write(file, page, pos, len)) {
339 		once_thru = 1;
340 		ret = nfs_read_folio(file, page_folio(page));
341 		put_page(page);
342 		if (!ret)
343 			goto start;
344 	}
345 	return ret;
346 }
347 
nfs_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)348 static int nfs_write_end(struct file *file, struct address_space *mapping,
349 			loff_t pos, unsigned len, unsigned copied,
350 			struct page *page, void *fsdata)
351 {
352 	unsigned offset = pos & (PAGE_SIZE - 1);
353 	struct nfs_open_context *ctx = nfs_file_open_context(file);
354 	int status;
355 
356 	dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n",
357 		file, mapping->host->i_ino, len, (long long) pos);
358 
359 	/*
360 	 * Zero any uninitialised parts of the page, and then mark the page
361 	 * as up to date if it turns out that we're extending the file.
362 	 */
363 	if (!PageUptodate(page)) {
364 		unsigned pglen = nfs_page_length(page);
365 		unsigned end = offset + copied;
366 
367 		if (pglen == 0) {
368 			zero_user_segments(page, 0, offset,
369 					end, PAGE_SIZE);
370 			SetPageUptodate(page);
371 		} else if (end >= pglen) {
372 			zero_user_segment(page, end, PAGE_SIZE);
373 			if (offset == 0)
374 				SetPageUptodate(page);
375 		} else
376 			zero_user_segment(page, pglen, PAGE_SIZE);
377 	}
378 
379 	status = nfs_updatepage(file, page, offset, copied);
380 
381 	unlock_page(page);
382 	put_page(page);
383 
384 	if (status < 0)
385 		return status;
386 	NFS_I(mapping->host)->write_io += copied;
387 
388 	if (nfs_ctx_key_to_expire(ctx, mapping->host))
389 		nfs_wb_all(mapping->host);
390 
391 	return copied;
392 }
393 
394 /*
395  * Partially or wholly invalidate a page
396  * - Release the private state associated with a page if undergoing complete
397  *   page invalidation
398  * - Called if either PG_private or PG_fscache is set on the page
399  * - Caller holds page lock
400  */
nfs_invalidate_folio(struct folio * folio,size_t offset,size_t length)401 static void nfs_invalidate_folio(struct folio *folio, size_t offset,
402 				size_t length)
403 {
404 	dfprintk(PAGECACHE, "NFS: invalidate_folio(%lu, %zu, %zu)\n",
405 		 folio->index, offset, length);
406 
407 	if (offset != 0 || length < folio_size(folio))
408 		return;
409 	/* Cancel any unstarted writes on this page */
410 	nfs_wb_folio_cancel(folio->mapping->host, folio);
411 	folio_wait_fscache(folio);
412 }
413 
414 /*
415  * Attempt to release the private state associated with a folio
416  * - Called if either private or fscache flags are set on the folio
417  * - Caller holds folio lock
418  * - Return true (may release folio) or false (may not)
419  */
nfs_release_folio(struct folio * folio,gfp_t gfp)420 static bool nfs_release_folio(struct folio *folio, gfp_t gfp)
421 {
422 	dfprintk(PAGECACHE, "NFS: release_folio(%p)\n", folio);
423 
424 	/* If the private flag is set, then the folio is not freeable */
425 	if (folio_test_private(folio))
426 		return false;
427 	return nfs_fscache_release_folio(folio, gfp);
428 }
429 
nfs_check_dirty_writeback(struct folio * folio,bool * dirty,bool * writeback)430 static void nfs_check_dirty_writeback(struct folio *folio,
431 				bool *dirty, bool *writeback)
432 {
433 	struct nfs_inode *nfsi;
434 	struct address_space *mapping = folio->mapping;
435 
436 	/*
437 	 * Check if an unstable folio is currently being committed and
438 	 * if so, have the VM treat it as if the folio is under writeback
439 	 * so it will not block due to folios that will shortly be freeable.
440 	 */
441 	nfsi = NFS_I(mapping->host);
442 	if (atomic_read(&nfsi->commit_info.rpcs_out)) {
443 		*writeback = true;
444 		return;
445 	}
446 
447 	/*
448 	 * If the private flag is set, then the folio is not freeable
449 	 * and as the inode is not being committed, it's not going to
450 	 * be cleaned in the near future so treat it as dirty
451 	 */
452 	if (folio_test_private(folio))
453 		*dirty = true;
454 }
455 
456 /*
457  * Attempt to clear the private state associated with a page when an error
458  * occurs that requires the cached contents of an inode to be written back or
459  * destroyed
460  * - Called if either PG_private or fscache is set on the page
461  * - Caller holds page lock
462  * - Return 0 if successful, -error otherwise
463  */
nfs_launder_folio(struct folio * folio)464 static int nfs_launder_folio(struct folio *folio)
465 {
466 	struct inode *inode = folio->mapping->host;
467 
468 	dfprintk(PAGECACHE, "NFS: launder_folio(%ld, %llu)\n",
469 		inode->i_ino, folio_pos(folio));
470 
471 	folio_wait_fscache(folio);
472 	return nfs_wb_page(inode, &folio->page);
473 }
474 
nfs_swap_activate(struct swap_info_struct * sis,struct file * file,sector_t * span)475 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
476 						sector_t *span)
477 {
478 	unsigned long blocks;
479 	long long isize;
480 	int ret;
481 	struct inode *inode = file_inode(file);
482 	struct rpc_clnt *clnt = NFS_CLIENT(inode);
483 	struct nfs_client *cl = NFS_SERVER(inode)->nfs_client;
484 
485 	spin_lock(&inode->i_lock);
486 	blocks = inode->i_blocks;
487 	isize = inode->i_size;
488 	spin_unlock(&inode->i_lock);
489 	if (blocks*512 < isize) {
490 		pr_warn("swap activate: swapfile has holes\n");
491 		return -EINVAL;
492 	}
493 
494 	ret = rpc_clnt_swap_activate(clnt);
495 	if (ret)
496 		return ret;
497 	ret = add_swap_extent(sis, 0, sis->max, 0);
498 	if (ret < 0) {
499 		rpc_clnt_swap_deactivate(clnt);
500 		return ret;
501 	}
502 
503 	*span = sis->pages;
504 
505 	if (cl->rpc_ops->enable_swap)
506 		cl->rpc_ops->enable_swap(inode);
507 
508 	sis->flags |= SWP_FS_OPS;
509 	return ret;
510 }
511 
nfs_swap_deactivate(struct file * file)512 static void nfs_swap_deactivate(struct file *file)
513 {
514 	struct inode *inode = file_inode(file);
515 	struct rpc_clnt *clnt = NFS_CLIENT(inode);
516 	struct nfs_client *cl = NFS_SERVER(inode)->nfs_client;
517 
518 	rpc_clnt_swap_deactivate(clnt);
519 	if (cl->rpc_ops->disable_swap)
520 		cl->rpc_ops->disable_swap(file_inode(file));
521 }
522 
523 const struct address_space_operations nfs_file_aops = {
524 	.read_folio = nfs_read_folio,
525 	.readahead = nfs_readahead,
526 	.dirty_folio = filemap_dirty_folio,
527 	.writepage = nfs_writepage,
528 	.writepages = nfs_writepages,
529 	.write_begin = nfs_write_begin,
530 	.write_end = nfs_write_end,
531 	.invalidate_folio = nfs_invalidate_folio,
532 	.release_folio = nfs_release_folio,
533 	.migrate_folio = nfs_migrate_folio,
534 	.launder_folio = nfs_launder_folio,
535 	.is_dirty_writeback = nfs_check_dirty_writeback,
536 	.error_remove_page = generic_error_remove_page,
537 	.swap_activate = nfs_swap_activate,
538 	.swap_deactivate = nfs_swap_deactivate,
539 	.swap_rw = nfs_swap_rw,
540 };
541 
542 /*
543  * Notification that a PTE pointing to an NFS page is about to be made
544  * writable, implying that someone is about to modify the page through a
545  * shared-writable mapping
546  */
nfs_vm_page_mkwrite(struct vm_fault * vmf)547 static vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf)
548 {
549 	struct page *page = vmf->page;
550 	struct file *filp = vmf->vma->vm_file;
551 	struct inode *inode = file_inode(filp);
552 	unsigned pagelen;
553 	vm_fault_t ret = VM_FAULT_NOPAGE;
554 	struct address_space *mapping;
555 
556 	dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n",
557 		filp, filp->f_mapping->host->i_ino,
558 		(long long)page_offset(page));
559 
560 	sb_start_pagefault(inode->i_sb);
561 
562 	/* make sure the cache has finished storing the page */
563 	if (PageFsCache(page) &&
564 	    wait_on_page_fscache_killable(vmf->page) < 0) {
565 		ret = VM_FAULT_RETRY;
566 		goto out;
567 	}
568 
569 	wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
570 			   nfs_wait_bit_killable,
571 			   TASK_KILLABLE|TASK_FREEZABLE_UNSAFE);
572 
573 	lock_page(page);
574 	mapping = page_file_mapping(page);
575 	if (mapping != inode->i_mapping)
576 		goto out_unlock;
577 
578 	wait_on_page_writeback(page);
579 
580 	pagelen = nfs_page_length(page);
581 	if (pagelen == 0)
582 		goto out_unlock;
583 
584 	ret = VM_FAULT_LOCKED;
585 	if (nfs_flush_incompatible(filp, page) == 0 &&
586 	    nfs_updatepage(filp, page, 0, pagelen) == 0)
587 		goto out;
588 
589 	ret = VM_FAULT_SIGBUS;
590 out_unlock:
591 	unlock_page(page);
592 out:
593 	sb_end_pagefault(inode->i_sb);
594 	return ret;
595 }
596 
597 static const struct vm_operations_struct nfs_file_vm_ops = {
598 	.fault = filemap_fault,
599 	.map_pages = filemap_map_pages,
600 	.page_mkwrite = nfs_vm_page_mkwrite,
601 };
602 
nfs_file_write(struct kiocb * iocb,struct iov_iter * from)603 ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
604 {
605 	struct file *file = iocb->ki_filp;
606 	struct inode *inode = file_inode(file);
607 	unsigned int mntflags = NFS_SERVER(inode)->flags;
608 	ssize_t result, written;
609 	errseq_t since;
610 	int error;
611 
612 	result = nfs_key_timeout_notify(file, inode);
613 	if (result)
614 		return result;
615 
616 	if (iocb->ki_flags & IOCB_DIRECT)
617 		return nfs_file_direct_write(iocb, from, false);
618 
619 	dprintk("NFS: write(%pD2, %zu@%Ld)\n",
620 		file, iov_iter_count(from), (long long) iocb->ki_pos);
621 
622 	if (IS_SWAPFILE(inode))
623 		goto out_swapfile;
624 	/*
625 	 * O_APPEND implies that we must revalidate the file length.
626 	 */
627 	if (iocb->ki_flags & IOCB_APPEND || iocb->ki_pos > i_size_read(inode)) {
628 		result = nfs_revalidate_file_size(inode, file);
629 		if (result)
630 			return result;
631 	}
632 
633 	nfs_clear_invalid_mapping(file->f_mapping);
634 
635 	since = filemap_sample_wb_err(file->f_mapping);
636 	nfs_start_io_write(inode);
637 	result = generic_write_checks(iocb, from);
638 	if (result > 0) {
639 		current->backing_dev_info = inode_to_bdi(inode);
640 		result = generic_perform_write(iocb, from);
641 		current->backing_dev_info = NULL;
642 	}
643 	nfs_end_io_write(inode);
644 	if (result <= 0)
645 		goto out;
646 
647 	written = result;
648 	iocb->ki_pos += written;
649 	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
650 
651 	if (mntflags & NFS_MOUNT_WRITE_EAGER) {
652 		result = filemap_fdatawrite_range(file->f_mapping,
653 						  iocb->ki_pos - written,
654 						  iocb->ki_pos - 1);
655 		if (result < 0)
656 			goto out;
657 	}
658 	if (mntflags & NFS_MOUNT_WRITE_WAIT) {
659 		filemap_fdatawait_range(file->f_mapping,
660 					iocb->ki_pos - written,
661 					iocb->ki_pos - 1);
662 	}
663 	result = generic_write_sync(iocb, written);
664 	if (result < 0)
665 		return result;
666 
667 out:
668 	/* Return error values */
669 	error = filemap_check_wb_err(file->f_mapping, since);
670 	switch (error) {
671 	default:
672 		break;
673 	case -EDQUOT:
674 	case -EFBIG:
675 	case -ENOSPC:
676 		nfs_wb_all(inode);
677 		error = file_check_and_advance_wb_err(file);
678 		if (error < 0)
679 			result = error;
680 	}
681 	return result;
682 
683 out_swapfile:
684 	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
685 	return -ETXTBSY;
686 }
687 EXPORT_SYMBOL_GPL(nfs_file_write);
688 
689 static int
do_getlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)690 do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
691 {
692 	struct inode *inode = filp->f_mapping->host;
693 	int status = 0;
694 	unsigned int saved_type = fl->fl_type;
695 
696 	/* Try local locking first */
697 	posix_test_lock(filp, fl);
698 	if (fl->fl_type != F_UNLCK) {
699 		/* found a conflict */
700 		goto out;
701 	}
702 	fl->fl_type = saved_type;
703 
704 	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
705 		goto out_noconflict;
706 
707 	if (is_local)
708 		goto out_noconflict;
709 
710 	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
711 out:
712 	return status;
713 out_noconflict:
714 	fl->fl_type = F_UNLCK;
715 	goto out;
716 }
717 
718 static int
do_unlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)719 do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
720 {
721 	struct inode *inode = filp->f_mapping->host;
722 	struct nfs_lock_context *l_ctx;
723 	int status;
724 
725 	/*
726 	 * Flush all pending writes before doing anything
727 	 * with locks..
728 	 */
729 	nfs_wb_all(inode);
730 
731 	l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
732 	if (!IS_ERR(l_ctx)) {
733 		status = nfs_iocounter_wait(l_ctx);
734 		nfs_put_lock_context(l_ctx);
735 		/*  NOTE: special case
736 		 * 	If we're signalled while cleaning up locks on process exit, we
737 		 * 	still need to complete the unlock.
738 		 */
739 		if (status < 0 && !(fl->fl_flags & FL_CLOSE))
740 			return status;
741 	}
742 
743 	/*
744 	 * Use local locking if mounted with "-onolock" or with appropriate
745 	 * "-olocal_lock="
746 	 */
747 	if (!is_local)
748 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
749 	else
750 		status = locks_lock_file_wait(filp, fl);
751 	return status;
752 }
753 
754 static int
do_setlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)755 do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
756 {
757 	struct inode *inode = filp->f_mapping->host;
758 	int status;
759 
760 	/*
761 	 * Flush all pending writes before doing anything
762 	 * with locks..
763 	 */
764 	status = nfs_sync_mapping(filp->f_mapping);
765 	if (status != 0)
766 		goto out;
767 
768 	/*
769 	 * Use local locking if mounted with "-onolock" or with appropriate
770 	 * "-olocal_lock="
771 	 */
772 	if (!is_local)
773 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
774 	else
775 		status = locks_lock_file_wait(filp, fl);
776 	if (status < 0)
777 		goto out;
778 
779 	/*
780 	 * Invalidate cache to prevent missing any changes.  If
781 	 * the file is mapped, clear the page cache as well so
782 	 * those mappings will be loaded.
783 	 *
784 	 * This makes locking act as a cache coherency point.
785 	 */
786 	nfs_sync_mapping(filp->f_mapping);
787 	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
788 		nfs_zap_caches(inode);
789 		if (mapping_mapped(filp->f_mapping))
790 			nfs_revalidate_mapping(inode, filp->f_mapping);
791 	}
792 out:
793 	return status;
794 }
795 
796 /*
797  * Lock a (portion of) a file
798  */
nfs_lock(struct file * filp,int cmd,struct file_lock * fl)799 int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
800 {
801 	struct inode *inode = filp->f_mapping->host;
802 	int ret = -ENOLCK;
803 	int is_local = 0;
804 
805 	dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)\n",
806 			filp, fl->fl_type, fl->fl_flags,
807 			(long long)fl->fl_start, (long long)fl->fl_end);
808 
809 	nfs_inc_stats(inode, NFSIOS_VFSLOCK);
810 
811 	if (fl->fl_flags & FL_RECLAIM)
812 		return -ENOGRACE;
813 
814 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
815 		is_local = 1;
816 
817 	if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
818 		ret = NFS_PROTO(inode)->lock_check_bounds(fl);
819 		if (ret < 0)
820 			goto out_err;
821 	}
822 
823 	if (IS_GETLK(cmd))
824 		ret = do_getlk(filp, cmd, fl, is_local);
825 	else if (fl->fl_type == F_UNLCK)
826 		ret = do_unlk(filp, cmd, fl, is_local);
827 	else
828 		ret = do_setlk(filp, cmd, fl, is_local);
829 out_err:
830 	return ret;
831 }
832 EXPORT_SYMBOL_GPL(nfs_lock);
833 
834 /*
835  * Lock a (portion of) a file
836  */
nfs_flock(struct file * filp,int cmd,struct file_lock * fl)837 int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
838 {
839 	struct inode *inode = filp->f_mapping->host;
840 	int is_local = 0;
841 
842 	dprintk("NFS: flock(%pD2, t=%x, fl=%x)\n",
843 			filp, fl->fl_type, fl->fl_flags);
844 
845 	if (!(fl->fl_flags & FL_FLOCK))
846 		return -ENOLCK;
847 
848 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
849 		is_local = 1;
850 
851 	/* We're simulating flock() locks using posix locks on the server */
852 	if (fl->fl_type == F_UNLCK)
853 		return do_unlk(filp, cmd, fl, is_local);
854 	return do_setlk(filp, cmd, fl, is_local);
855 }
856 EXPORT_SYMBOL_GPL(nfs_flock);
857 
858 const struct file_operations nfs_file_operations = {
859 	.llseek		= nfs_file_llseek,
860 	.read_iter	= nfs_file_read,
861 	.write_iter	= nfs_file_write,
862 	.mmap		= nfs_file_mmap,
863 	.open		= nfs_file_open,
864 	.flush		= nfs_file_flush,
865 	.release	= nfs_file_release,
866 	.fsync		= nfs_file_fsync,
867 	.lock		= nfs_lock,
868 	.flock		= nfs_flock,
869 	.splice_read	= generic_file_splice_read,
870 	.splice_write	= iter_file_splice_write,
871 	.check_flags	= nfs_check_flags,
872 	.setlease	= simple_nosetlease,
873 };
874 EXPORT_SYMBOL_GPL(nfs_file_operations);
875