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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 
47 /* Hack for future NFS swap support */
48 #ifndef IS_SWAPFILE
49 # define IS_SWAPFILE(inode)	(0)
50 #endif
51 
nfs_check_flags(int flags)52 int nfs_check_flags(int flags)
53 {
54 	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
55 		return -EINVAL;
56 
57 	return 0;
58 }
59 EXPORT_SYMBOL_GPL(nfs_check_flags);
60 
61 /*
62  * Open file
63  */
64 static int
nfs_file_open(struct inode * inode,struct file * filp)65 nfs_file_open(struct inode *inode, struct file *filp)
66 {
67 	int res;
68 
69 	dprintk("NFS: open file(%pD2)\n", filp);
70 
71 	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
72 	res = nfs_check_flags(filp->f_flags);
73 	if (res)
74 		return res;
75 
76 	res = nfs_open(inode, filp);
77 	return res;
78 }
79 
80 int
nfs_file_release(struct inode * inode,struct file * filp)81 nfs_file_release(struct inode *inode, struct file *filp)
82 {
83 	dprintk("NFS: release(%pD2)\n", filp);
84 
85 	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
86 	nfs_file_clear_open_context(filp);
87 	return 0;
88 }
89 EXPORT_SYMBOL_GPL(nfs_file_release);
90 
91 /**
92  * nfs_revalidate_size - Revalidate the file size
93  * @inode: pointer to inode struct
94  * @filp: pointer to struct file
95  *
96  * Revalidates the file length. This is basically a wrapper around
97  * nfs_revalidate_inode() that takes into account the fact that we may
98  * have cached writes (in which case we don't care about the server's
99  * idea of what the file length is), or O_DIRECT (in which case we
100  * shouldn't trust the cache).
101  */
nfs_revalidate_file_size(struct inode * inode,struct file * filp)102 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
103 {
104 	struct nfs_server *server = NFS_SERVER(inode);
105 
106 	if (filp->f_flags & O_DIRECT)
107 		goto force_reval;
108 	if (nfs_check_cache_invalid(inode, NFS_INO_REVAL_PAGECACHE))
109 		goto force_reval;
110 	return 0;
111 force_reval:
112 	return __nfs_revalidate_inode(server, inode);
113 }
114 
nfs_file_llseek(struct file * filp,loff_t offset,int whence)115 loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
116 {
117 	dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
118 			filp, offset, whence);
119 
120 	/*
121 	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
122 	 * the cached file length
123 	 */
124 	if (whence != SEEK_SET && whence != SEEK_CUR) {
125 		struct inode *inode = filp->f_mapping->host;
126 
127 		int retval = nfs_revalidate_file_size(inode, filp);
128 		if (retval < 0)
129 			return (loff_t)retval;
130 	}
131 
132 	return generic_file_llseek(filp, offset, whence);
133 }
134 EXPORT_SYMBOL_GPL(nfs_file_llseek);
135 
136 /*
137  * Flush all dirty pages, and check for write errors.
138  */
139 static int
nfs_file_flush(struct file * file,fl_owner_t id)140 nfs_file_flush(struct file *file, fl_owner_t id)
141 {
142 	struct inode	*inode = file_inode(file);
143 	errseq_t since;
144 
145 	dprintk("NFS: flush(%pD2)\n", file);
146 
147 	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
148 	if ((file->f_mode & FMODE_WRITE) == 0)
149 		return 0;
150 
151 	/* Flush writes to the server and return any errors */
152 	since = filemap_sample_wb_err(file->f_mapping);
153 	nfs_wb_all(inode);
154 	return filemap_check_wb_err(file->f_mapping, since);
155 }
156 
157 ssize_t
nfs_file_read(struct kiocb * iocb,struct iov_iter * to)158 nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
159 {
160 	struct inode *inode = file_inode(iocb->ki_filp);
161 	ssize_t result;
162 
163 	if (iocb->ki_flags & IOCB_DIRECT)
164 		return nfs_file_direct_read(iocb, to, false);
165 
166 	dprintk("NFS: read(%pD2, %zu@%lu)\n",
167 		iocb->ki_filp,
168 		iov_iter_count(to), (unsigned long) iocb->ki_pos);
169 
170 	nfs_start_io_read(inode);
171 	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
172 	if (!result) {
173 		result = generic_file_read_iter(iocb, to);
174 		if (result > 0)
175 			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
176 	}
177 	nfs_end_io_read(inode);
178 	return result;
179 }
180 EXPORT_SYMBOL_GPL(nfs_file_read);
181 
182 int
nfs_file_mmap(struct file * file,struct vm_area_struct * vma)183 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
184 {
185 	struct inode *inode = file_inode(file);
186 	int	status;
187 
188 	dprintk("NFS: mmap(%pD2)\n", file);
189 
190 	/* Note: generic_file_mmap() returns ENOSYS on nommu systems
191 	 *       so we call that before revalidating the mapping
192 	 */
193 	status = generic_file_mmap(file, vma);
194 	if (!status) {
195 		vma->vm_ops = &nfs_file_vm_ops;
196 		status = nfs_revalidate_mapping(inode, file->f_mapping);
197 	}
198 	return status;
199 }
200 EXPORT_SYMBOL_GPL(nfs_file_mmap);
201 
202 /*
203  * Flush any dirty pages for this process, and check for write errors.
204  * The return status from this call provides a reliable indication of
205  * whether any write errors occurred for this process.
206  */
207 static int
nfs_file_fsync_commit(struct file * file,int datasync)208 nfs_file_fsync_commit(struct file *file, int datasync)
209 {
210 	struct inode *inode = file_inode(file);
211 	int ret, ret2;
212 
213 	dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
214 
215 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
216 	ret = nfs_commit_inode(inode, FLUSH_SYNC);
217 	ret2 = file_check_and_advance_wb_err(file);
218 	if (ret2 < 0)
219 		return ret2;
220 	return ret;
221 }
222 
223 int
nfs_file_fsync(struct file * file,loff_t start,loff_t end,int datasync)224 nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
225 {
226 	struct nfs_open_context *ctx = nfs_file_open_context(file);
227 	struct inode *inode = file_inode(file);
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 		if (!test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags))
243 			break;
244 		/*
245 		 * If nfs_file_fsync_commit detected a server reboot, then
246 		 * resend all dirty pages that might have been covered by
247 		 * the NFS_CONTEXT_RESEND_WRITES flag
248 		 */
249 		start = 0;
250 		end = LLONG_MAX;
251 	}
252 
253 	trace_nfs_fsync_exit(inode, ret);
254 	return ret;
255 }
256 EXPORT_SYMBOL_GPL(nfs_file_fsync);
257 
258 /*
259  * Decide whether a read/modify/write cycle may be more efficient
260  * then a modify/write/read cycle when writing to a page in the
261  * page cache.
262  *
263  * Some pNFS layout drivers can only read/write at a certain block
264  * granularity like all block devices and therefore we must perform
265  * read/modify/write whenever a page hasn't read yet and the data
266  * to be written there is not aligned to a block boundary and/or
267  * smaller than the block size.
268  *
269  * The modify/write/read cycle may occur if a page is read before
270  * being completely filled by the writer.  In this situation, the
271  * page must be completely written to stable storage on the server
272  * before it can be refilled by reading in the page from the server.
273  * This can lead to expensive, small, FILE_SYNC mode writes being
274  * done.
275  *
276  * It may be more efficient to read the page first if the file is
277  * open for reading in addition to writing, the page is not marked
278  * as Uptodate, it is not dirty or waiting to be committed,
279  * indicating that it was previously allocated and then modified,
280  * that there were valid bytes of data in that range of the file,
281  * and that the new data won't completely replace the old data in
282  * that range of the file.
283  */
nfs_full_page_write(struct page * page,loff_t pos,unsigned int len)284 static bool nfs_full_page_write(struct page *page, loff_t pos, unsigned int len)
285 {
286 	unsigned int pglen = nfs_page_length(page);
287 	unsigned int offset = pos & (PAGE_SIZE - 1);
288 	unsigned int end = offset + len;
289 
290 	return !pglen || (end >= pglen && !offset);
291 }
292 
nfs_want_read_modify_write(struct file * file,struct page * page,loff_t pos,unsigned int len)293 static bool nfs_want_read_modify_write(struct file *file, struct page *page,
294 			loff_t pos, unsigned int len)
295 {
296 	/*
297 	 * Up-to-date pages, those with ongoing or full-page write
298 	 * don't need read/modify/write
299 	 */
300 	if (PageUptodate(page) || PagePrivate(page) ||
301 	    nfs_full_page_write(page, pos, len))
302 		return false;
303 
304 	if (pnfs_ld_read_whole_page(file->f_mapping->host))
305 		return true;
306 	/* Open for reading too? */
307 	if (file->f_mode & FMODE_READ)
308 		return true;
309 	return false;
310 }
311 
312 /*
313  * This does the "real" work of the write. We must allocate and lock the
314  * page to be sent back to the generic routine, which then copies the
315  * data from user space.
316  *
317  * If the writer ends up delaying the write, the writer needs to
318  * increment the page use counts until he is done with the page.
319  */
nfs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)320 static int nfs_write_begin(struct file *file, struct address_space *mapping,
321 			loff_t pos, unsigned len, unsigned flags,
322 			struct page **pagep, void **fsdata)
323 {
324 	int ret;
325 	pgoff_t index = pos >> PAGE_SHIFT;
326 	struct page *page;
327 	int once_thru = 0;
328 
329 	dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n",
330 		file, mapping->host->i_ino, len, (long long) pos);
331 
332 start:
333 	page = grab_cache_page_write_begin(mapping, index, flags);
334 	if (!page)
335 		return -ENOMEM;
336 	*pagep = page;
337 
338 	ret = nfs_flush_incompatible(file, page);
339 	if (ret) {
340 		unlock_page(page);
341 		put_page(page);
342 	} else if (!once_thru &&
343 		   nfs_want_read_modify_write(file, page, pos, len)) {
344 		once_thru = 1;
345 		ret = nfs_readpage(file, page);
346 		put_page(page);
347 		if (!ret)
348 			goto start;
349 	}
350 	return ret;
351 }
352 
nfs_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)353 static int nfs_write_end(struct file *file, struct address_space *mapping,
354 			loff_t pos, unsigned len, unsigned copied,
355 			struct page *page, void *fsdata)
356 {
357 	unsigned offset = pos & (PAGE_SIZE - 1);
358 	struct nfs_open_context *ctx = nfs_file_open_context(file);
359 	int status;
360 
361 	dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n",
362 		file, mapping->host->i_ino, len, (long long) pos);
363 
364 	/*
365 	 * Zero any uninitialised parts of the page, and then mark the page
366 	 * as up to date if it turns out that we're extending the file.
367 	 */
368 	if (!PageUptodate(page)) {
369 		unsigned pglen = nfs_page_length(page);
370 		unsigned end = offset + copied;
371 
372 		if (pglen == 0) {
373 			zero_user_segments(page, 0, offset,
374 					end, PAGE_SIZE);
375 			SetPageUptodate(page);
376 		} else if (end >= pglen) {
377 			zero_user_segment(page, end, PAGE_SIZE);
378 			if (offset == 0)
379 				SetPageUptodate(page);
380 		} else
381 			zero_user_segment(page, pglen, PAGE_SIZE);
382 	}
383 
384 	status = nfs_updatepage(file, page, offset, copied);
385 
386 	unlock_page(page);
387 	put_page(page);
388 
389 	if (status < 0)
390 		return status;
391 	NFS_I(mapping->host)->write_io += copied;
392 
393 	if (nfs_ctx_key_to_expire(ctx, mapping->host))
394 		nfs_wb_all(mapping->host);
395 
396 	return copied;
397 }
398 
399 /*
400  * Partially or wholly invalidate a page
401  * - Release the private state associated with a page if undergoing complete
402  *   page invalidation
403  * - Called if either PG_private or PG_fscache is set on the page
404  * - Caller holds page lock
405  */
nfs_invalidate_page(struct page * page,unsigned int offset,unsigned int length)406 static void nfs_invalidate_page(struct page *page, unsigned int offset,
407 				unsigned int length)
408 {
409 	dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
410 		 page, offset, length);
411 
412 	if (offset != 0 || length < PAGE_SIZE)
413 		return;
414 	/* Cancel any unstarted writes on this page */
415 	nfs_wb_page_cancel(page_file_mapping(page)->host, page);
416 
417 	nfs_fscache_invalidate_page(page, page->mapping->host);
418 }
419 
420 /*
421  * Attempt to release the private state associated with a page
422  * - Called if either PG_private or PG_fscache is set on the page
423  * - Caller holds page lock
424  * - Return true (may release page) or false (may not)
425  */
nfs_release_page(struct page * page,gfp_t gfp)426 static int nfs_release_page(struct page *page, gfp_t gfp)
427 {
428 	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
429 
430 	/* If PagePrivate() is set, then the page is not freeable */
431 	if (PagePrivate(page))
432 		return 0;
433 	return nfs_fscache_release_page(page, gfp);
434 }
435 
nfs_check_dirty_writeback(struct page * page,bool * dirty,bool * writeback)436 static void nfs_check_dirty_writeback(struct page *page,
437 				bool *dirty, bool *writeback)
438 {
439 	struct nfs_inode *nfsi;
440 	struct address_space *mapping = page_file_mapping(page);
441 
442 	if (!mapping || PageSwapCache(page))
443 		return;
444 
445 	/*
446 	 * Check if an unstable page is currently being committed and
447 	 * if so, have the VM treat it as if the page is under writeback
448 	 * so it will not block due to pages that will shortly be freeable.
449 	 */
450 	nfsi = NFS_I(mapping->host);
451 	if (atomic_read(&nfsi->commit_info.rpcs_out)) {
452 		*writeback = true;
453 		return;
454 	}
455 
456 	/*
457 	 * If PagePrivate() is set, then the page is not freeable and as the
458 	 * inode is not being committed, it's not going to be cleaned in the
459 	 * near future so treat it as dirty
460 	 */
461 	if (PagePrivate(page))
462 		*dirty = true;
463 }
464 
465 /*
466  * Attempt to clear the private state associated with a page when an error
467  * occurs that requires the cached contents of an inode to be written back or
468  * destroyed
469  * - Called if either PG_private or fscache is set on the page
470  * - Caller holds page lock
471  * - Return 0 if successful, -error otherwise
472  */
nfs_launder_page(struct page * page)473 static int nfs_launder_page(struct page *page)
474 {
475 	struct inode *inode = page_file_mapping(page)->host;
476 	struct nfs_inode *nfsi = NFS_I(inode);
477 
478 	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
479 		inode->i_ino, (long long)page_offset(page));
480 
481 	nfs_fscache_wait_on_page_write(nfsi, page);
482 	return nfs_wb_page(inode, page);
483 }
484 
nfs_swap_activate(struct swap_info_struct * sis,struct file * file,sector_t * span)485 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
486 						sector_t *span)
487 {
488 	unsigned long blocks;
489 	long long isize;
490 	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
491 	struct inode *inode = file->f_mapping->host;
492 
493 	spin_lock(&inode->i_lock);
494 	blocks = inode->i_blocks;
495 	isize = inode->i_size;
496 	spin_unlock(&inode->i_lock);
497 	if (blocks*512 < isize) {
498 		pr_warn("swap activate: swapfile has holes\n");
499 		return -EINVAL;
500 	}
501 
502 	*span = sis->pages;
503 
504 	return rpc_clnt_swap_activate(clnt);
505 }
506 
nfs_swap_deactivate(struct file * file)507 static void nfs_swap_deactivate(struct file *file)
508 {
509 	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
510 
511 	rpc_clnt_swap_deactivate(clnt);
512 }
513 
514 const struct address_space_operations nfs_file_aops = {
515 	.readpage = nfs_readpage,
516 	.readpages = nfs_readpages,
517 	.set_page_dirty = __set_page_dirty_nobuffers,
518 	.writepage = nfs_writepage,
519 	.writepages = nfs_writepages,
520 	.write_begin = nfs_write_begin,
521 	.write_end = nfs_write_end,
522 	.invalidatepage = nfs_invalidate_page,
523 	.releasepage = nfs_release_page,
524 	.direct_IO = nfs_direct_IO,
525 #ifdef CONFIG_MIGRATION
526 	.migratepage = nfs_migrate_page,
527 #endif
528 	.launder_page = nfs_launder_page,
529 	.is_dirty_writeback = nfs_check_dirty_writeback,
530 	.error_remove_page = generic_error_remove_page,
531 	.swap_activate = nfs_swap_activate,
532 	.swap_deactivate = nfs_swap_deactivate,
533 };
534 
535 /*
536  * Notification that a PTE pointing to an NFS page is about to be made
537  * writable, implying that someone is about to modify the page through a
538  * shared-writable mapping
539  */
nfs_vm_page_mkwrite(struct vm_fault * vmf)540 static vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf)
541 {
542 	struct page *page = vmf->page;
543 	struct file *filp = vmf->vma->vm_file;
544 	struct inode *inode = file_inode(filp);
545 	unsigned pagelen;
546 	vm_fault_t ret = VM_FAULT_NOPAGE;
547 	struct address_space *mapping;
548 
549 	dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n",
550 		filp, filp->f_mapping->host->i_ino,
551 		(long long)page_offset(page));
552 
553 	sb_start_pagefault(inode->i_sb);
554 
555 	/* make sure the cache has finished storing the page */
556 	nfs_fscache_wait_on_page_write(NFS_I(inode), page);
557 
558 	wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
559 			nfs_wait_bit_killable, TASK_KILLABLE);
560 
561 	lock_page(page);
562 	mapping = page_file_mapping(page);
563 	if (mapping != inode->i_mapping)
564 		goto out_unlock;
565 
566 	wait_on_page_writeback(page);
567 
568 	pagelen = nfs_page_length(page);
569 	if (pagelen == 0)
570 		goto out_unlock;
571 
572 	ret = VM_FAULT_LOCKED;
573 	if (nfs_flush_incompatible(filp, page) == 0 &&
574 	    nfs_updatepage(filp, page, 0, pagelen) == 0)
575 		goto out;
576 
577 	ret = VM_FAULT_SIGBUS;
578 out_unlock:
579 	unlock_page(page);
580 out:
581 	sb_end_pagefault(inode->i_sb);
582 	return ret;
583 }
584 
585 static const struct vm_operations_struct nfs_file_vm_ops = {
586 	.fault = filemap_fault,
587 	.map_pages = filemap_map_pages,
588 	.page_mkwrite = nfs_vm_page_mkwrite,
589 };
590 
nfs_need_check_write(struct file * filp,struct inode * inode,int error)591 static int nfs_need_check_write(struct file *filp, struct inode *inode,
592 				int error)
593 {
594 	struct nfs_open_context *ctx;
595 
596 	ctx = nfs_file_open_context(filp);
597 	if (nfs_error_is_fatal_on_server(error) ||
598 	    nfs_ctx_key_to_expire(ctx, inode))
599 		return 1;
600 	return 0;
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 long written = 0;
608 	ssize_t result;
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) {
628 		result = nfs_revalidate_file_size(inode, file);
629 		if (result)
630 			goto out;
631 	}
632 	if (iocb->ki_pos > i_size_read(inode))
633 		nfs_revalidate_mapping(inode, 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(file, from, iocb->ki_pos);
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 	result = generic_write_sync(iocb, written);
650 	if (result < 0)
651 		goto out;
652 
653 	/* Return error values */
654 	error = filemap_check_wb_err(file->f_mapping, since);
655 	if (nfs_need_check_write(file, inode, error)) {
656 		int err = nfs_wb_all(inode);
657 		if (err < 0)
658 			result = err;
659 	}
660 	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
661 out:
662 	return result;
663 
664 out_swapfile:
665 	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
666 	return -ETXTBSY;
667 }
668 EXPORT_SYMBOL_GPL(nfs_file_write);
669 
670 static int
do_getlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)671 do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
672 {
673 	struct inode *inode = filp->f_mapping->host;
674 	int status = 0;
675 	unsigned int saved_type = fl->fl_type;
676 
677 	/* Try local locking first */
678 	posix_test_lock(filp, fl);
679 	if (fl->fl_type != F_UNLCK) {
680 		/* found a conflict */
681 		goto out;
682 	}
683 	fl->fl_type = saved_type;
684 
685 	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
686 		goto out_noconflict;
687 
688 	if (is_local)
689 		goto out_noconflict;
690 
691 	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
692 out:
693 	return status;
694 out_noconflict:
695 	fl->fl_type = F_UNLCK;
696 	goto out;
697 }
698 
699 static int
do_unlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)700 do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
701 {
702 	struct inode *inode = filp->f_mapping->host;
703 	struct nfs_lock_context *l_ctx;
704 	int status;
705 
706 	/*
707 	 * Flush all pending writes before doing anything
708 	 * with locks..
709 	 */
710 	nfs_wb_all(inode);
711 
712 	l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
713 	if (!IS_ERR(l_ctx)) {
714 		status = nfs_iocounter_wait(l_ctx);
715 		nfs_put_lock_context(l_ctx);
716 		/*  NOTE: special case
717 		 * 	If we're signalled while cleaning up locks on process exit, we
718 		 * 	still need to complete the unlock.
719 		 */
720 		if (status < 0 && !(fl->fl_flags & FL_CLOSE))
721 			return status;
722 	}
723 
724 	/*
725 	 * Use local locking if mounted with "-onolock" or with appropriate
726 	 * "-olocal_lock="
727 	 */
728 	if (!is_local)
729 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
730 	else
731 		status = locks_lock_file_wait(filp, fl);
732 	return status;
733 }
734 
735 static int
do_setlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)736 do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
737 {
738 	struct inode *inode = filp->f_mapping->host;
739 	int status;
740 
741 	/*
742 	 * Flush all pending writes before doing anything
743 	 * with locks..
744 	 */
745 	status = nfs_sync_mapping(filp->f_mapping);
746 	if (status != 0)
747 		goto out;
748 
749 	/*
750 	 * Use local locking if mounted with "-onolock" or with appropriate
751 	 * "-olocal_lock="
752 	 */
753 	if (!is_local)
754 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
755 	else
756 		status = locks_lock_file_wait(filp, fl);
757 	if (status < 0)
758 		goto out;
759 
760 	/*
761 	 * Invalidate cache to prevent missing any changes.  If
762 	 * the file is mapped, clear the page cache as well so
763 	 * those mappings will be loaded.
764 	 *
765 	 * This makes locking act as a cache coherency point.
766 	 */
767 	nfs_sync_mapping(filp->f_mapping);
768 	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
769 		nfs_zap_caches(inode);
770 		if (mapping_mapped(filp->f_mapping))
771 			nfs_revalidate_mapping(inode, filp->f_mapping);
772 	}
773 out:
774 	return status;
775 }
776 
777 /*
778  * Lock a (portion of) a file
779  */
nfs_lock(struct file * filp,int cmd,struct file_lock * fl)780 int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
781 {
782 	struct inode *inode = filp->f_mapping->host;
783 	int ret = -ENOLCK;
784 	int is_local = 0;
785 
786 	dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)\n",
787 			filp, fl->fl_type, fl->fl_flags,
788 			(long long)fl->fl_start, (long long)fl->fl_end);
789 
790 	nfs_inc_stats(inode, NFSIOS_VFSLOCK);
791 
792 	/* No mandatory locks over NFS */
793 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
794 		goto out_err;
795 
796 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
797 		is_local = 1;
798 
799 	if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
800 		ret = NFS_PROTO(inode)->lock_check_bounds(fl);
801 		if (ret < 0)
802 			goto out_err;
803 	}
804 
805 	if (IS_GETLK(cmd))
806 		ret = do_getlk(filp, cmd, fl, is_local);
807 	else if (fl->fl_type == F_UNLCK)
808 		ret = do_unlk(filp, cmd, fl, is_local);
809 	else
810 		ret = do_setlk(filp, cmd, fl, is_local);
811 out_err:
812 	return ret;
813 }
814 EXPORT_SYMBOL_GPL(nfs_lock);
815 
816 /*
817  * Lock a (portion of) a file
818  */
nfs_flock(struct file * filp,int cmd,struct file_lock * fl)819 int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
820 {
821 	struct inode *inode = filp->f_mapping->host;
822 	int is_local = 0;
823 
824 	dprintk("NFS: flock(%pD2, t=%x, fl=%x)\n",
825 			filp, fl->fl_type, fl->fl_flags);
826 
827 	if (!(fl->fl_flags & FL_FLOCK))
828 		return -ENOLCK;
829 
830 	/*
831 	 * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
832 	 * any standard. In principle we might be able to support LOCK_MAND
833 	 * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
834 	 * NFS code is not set up for it.
835 	 */
836 	if (fl->fl_type & LOCK_MAND)
837 		return -EINVAL;
838 
839 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
840 		is_local = 1;
841 
842 	/* We're simulating flock() locks using posix locks on the server */
843 	if (fl->fl_type == F_UNLCK)
844 		return do_unlk(filp, cmd, fl, is_local);
845 	return do_setlk(filp, cmd, fl, is_local);
846 }
847 EXPORT_SYMBOL_GPL(nfs_flock);
848 
849 const struct file_operations nfs_file_operations = {
850 	.llseek		= nfs_file_llseek,
851 	.read_iter	= nfs_file_read,
852 	.write_iter	= nfs_file_write,
853 	.mmap		= nfs_file_mmap,
854 	.open		= nfs_file_open,
855 	.flush		= nfs_file_flush,
856 	.release	= nfs_file_release,
857 	.fsync		= nfs_file_fsync,
858 	.lock		= nfs_lock,
859 	.flock		= nfs_flock,
860 	.splice_read	= generic_file_splice_read,
861 	.splice_write	= iter_file_splice_write,
862 	.check_flags	= nfs_check_flags,
863 	.setlease	= simple_nosetlease,
864 };
865 EXPORT_SYMBOL_GPL(nfs_file_operations);
866