1 /*
2  *  linux/fs/nfs/file.c
3  *
4  *  Copyright (C) 1992  Rick Sladkey
5  *
6  *  Changes Copyright (C) 1994 by Florian La Roche
7  *   - Do not copy data too often around in the kernel.
8  *   - In nfs_file_read the return value of kmalloc wasn't checked.
9  *   - Put in a better version of read look-ahead buffering. Original idea
10  *     and implementation by Wai S Kok elekokws@ee.nus.sg.
11  *
12  *  Expire cache on write to a file by Wai S Kok (Oct 1994).
13  *
14  *  Total rewrite of read side for new NFS buffer cache.. Linus.
15  *
16  *  nfs regular file handling functions
17  */
18 
19 #include <linux/module.h>
20 #include <linux/time.h>
21 #include <linux/kernel.h>
22 #include <linux/errno.h>
23 #include <linux/fcntl.h>
24 #include <linux/stat.h>
25 #include <linux/nfs_fs.h>
26 #include <linux/nfs_mount.h>
27 #include <linux/mm.h>
28 #include <linux/pagemap.h>
29 #include <linux/gfp.h>
30 #include <linux/swap.h>
31 
32 #include <linux/uaccess.h>
33 
34 #include "delegation.h"
35 #include "internal.h"
36 #include "iostat.h"
37 #include "fscache.h"
38 #include "pnfs.h"
39 
40 #include "nfstrace.h"
41 
42 #define NFSDBG_FACILITY		NFSDBG_FILE
43 
44 static const struct vm_operations_struct nfs_file_vm_ops;
45 
46 /* Hack for future NFS swap support */
47 #ifndef IS_SWAPFILE
48 # define IS_SWAPFILE(inode)	(0)
49 #endif
50 
nfs_check_flags(int flags)51 int nfs_check_flags(int flags)
52 {
53 	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
54 		return -EINVAL;
55 
56 	return 0;
57 }
58 EXPORT_SYMBOL_GPL(nfs_check_flags);
59 
60 /*
61  * Open file
62  */
63 static int
nfs_file_open(struct inode * inode,struct file * filp)64 nfs_file_open(struct inode *inode, struct file *filp)
65 {
66 	int res;
67 
68 	dprintk("NFS: open file(%pD2)\n", filp);
69 
70 	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
71 	res = nfs_check_flags(filp->f_flags);
72 	if (res)
73 		return res;
74 
75 	res = nfs_open(inode, filp);
76 	return res;
77 }
78 
79 int
nfs_file_release(struct inode * inode,struct file * filp)80 nfs_file_release(struct inode *inode, struct file *filp)
81 {
82 	dprintk("NFS: release(%pD2)\n", filp);
83 
84 	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
85 	nfs_file_clear_open_context(filp);
86 	return 0;
87 }
88 EXPORT_SYMBOL_GPL(nfs_file_release);
89 
90 /**
91  * nfs_revalidate_size - Revalidate the file size
92  * @inode - pointer to inode struct
93  * @file - pointer to struct file
94  *
95  * Revalidates the file length. This is basically a wrapper around
96  * nfs_revalidate_inode() that takes into account the fact that we may
97  * have cached writes (in which case we don't care about the server's
98  * idea of what the file length is), or O_DIRECT (in which case we
99  * shouldn't trust the cache).
100  */
nfs_revalidate_file_size(struct inode * inode,struct file * filp)101 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
102 {
103 	struct nfs_server *server = NFS_SERVER(inode);
104 
105 	if (filp->f_flags & O_DIRECT)
106 		goto force_reval;
107 	if (nfs_check_cache_invalid(inode, NFS_INO_REVAL_PAGECACHE))
108 		goto force_reval;
109 	return 0;
110 force_reval:
111 	return __nfs_revalidate_inode(server, inode);
112 }
113 
nfs_file_llseek(struct file * filp,loff_t offset,int whence)114 loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
115 {
116 	dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
117 			filp, offset, whence);
118 
119 	/*
120 	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
121 	 * the cached file length
122 	 */
123 	if (whence != SEEK_SET && whence != SEEK_CUR) {
124 		struct inode *inode = filp->f_mapping->host;
125 
126 		int retval = nfs_revalidate_file_size(inode, filp);
127 		if (retval < 0)
128 			return (loff_t)retval;
129 	}
130 
131 	return generic_file_llseek(filp, offset, whence);
132 }
133 EXPORT_SYMBOL_GPL(nfs_file_llseek);
134 
135 /*
136  * Flush all dirty pages, and check for write errors.
137  */
138 static int
nfs_file_flush(struct file * file,fl_owner_t id)139 nfs_file_flush(struct file *file, fl_owner_t id)
140 {
141 	struct inode	*inode = file_inode(file);
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 	return vfs_fsync(file, 0);
151 }
152 
153 ssize_t
nfs_file_read(struct kiocb * iocb,struct iov_iter * to)154 nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
155 {
156 	struct inode *inode = file_inode(iocb->ki_filp);
157 	ssize_t result;
158 
159 	if (iocb->ki_flags & IOCB_DIRECT)
160 		return nfs_file_direct_read(iocb, to, false);
161 
162 	dprintk("NFS: read(%pD2, %zu@%lu)\n",
163 		iocb->ki_filp,
164 		iov_iter_count(to), (unsigned long) iocb->ki_pos);
165 
166 	nfs_start_io_read(inode);
167 	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
168 	if (!result) {
169 		result = generic_file_read_iter(iocb, to);
170 		if (result > 0)
171 			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
172 	}
173 	nfs_end_io_read(inode);
174 	return result;
175 }
176 EXPORT_SYMBOL_GPL(nfs_file_read);
177 
178 int
nfs_file_mmap(struct file * file,struct vm_area_struct * vma)179 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
180 {
181 	struct inode *inode = file_inode(file);
182 	int	status;
183 
184 	dprintk("NFS: mmap(%pD2)\n", file);
185 
186 	/* Note: generic_file_mmap() returns ENOSYS on nommu systems
187 	 *       so we call that before revalidating the mapping
188 	 */
189 	status = generic_file_mmap(file, vma);
190 	if (!status) {
191 		vma->vm_ops = &nfs_file_vm_ops;
192 		status = nfs_revalidate_mapping(inode, file->f_mapping);
193 	}
194 	return status;
195 }
196 EXPORT_SYMBOL_GPL(nfs_file_mmap);
197 
198 /*
199  * Flush any dirty pages for this process, and check for write errors.
200  * The return status from this call provides a reliable indication of
201  * whether any write errors occurred for this process.
202  *
203  * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
204  * disk, but it retrieves and clears ctx->error after synching, despite
205  * the two being set at the same time in nfs_context_set_write_error().
206  * This is because the former is used to notify the _next_ call to
207  * nfs_file_write() that a write error occurred, and hence cause it to
208  * fall back to doing a synchronous write.
209  */
210 static int
nfs_file_fsync_commit(struct file * file,int datasync)211 nfs_file_fsync_commit(struct file *file, int datasync)
212 {
213 	struct nfs_open_context *ctx = nfs_file_open_context(file);
214 	struct inode *inode = file_inode(file);
215 	int do_resend, status;
216 	int ret = 0;
217 
218 	dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
219 
220 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
221 	do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
222 	status = nfs_commit_inode(inode, FLUSH_SYNC);
223 	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags)) {
224 		ret = xchg(&ctx->error, 0);
225 		if (ret)
226 			goto out;
227 	}
228 	if (status < 0) {
229 		ret = status;
230 		goto out;
231 	}
232 	do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
233 	if (do_resend)
234 		ret = -EAGAIN;
235 out:
236 	return ret;
237 }
238 
239 int
nfs_file_fsync(struct file * file,loff_t start,loff_t end,int datasync)240 nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
241 {
242 	int ret;
243 	struct inode *inode = file_inode(file);
244 
245 	trace_nfs_fsync_enter(inode);
246 
247 	do {
248 		struct nfs_open_context *ctx = nfs_file_open_context(file);
249 		ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
250 		if (test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags)) {
251 			int ret2 = xchg(&ctx->error, 0);
252 			if (ret2)
253 				ret = ret2;
254 		}
255 		if (ret != 0)
256 			break;
257 		ret = nfs_file_fsync_commit(file, datasync);
258 		if (!ret)
259 			ret = pnfs_sync_inode(inode, !!datasync);
260 		/*
261 		 * If nfs_file_fsync_commit detected a server reboot, then
262 		 * resend all dirty pages that might have been covered by
263 		 * the NFS_CONTEXT_RESEND_WRITES flag
264 		 */
265 		start = 0;
266 		end = LLONG_MAX;
267 	} while (ret == -EAGAIN);
268 
269 	trace_nfs_fsync_exit(inode, ret);
270 	return ret;
271 }
272 EXPORT_SYMBOL_GPL(nfs_file_fsync);
273 
274 /*
275  * Decide whether a read/modify/write cycle may be more efficient
276  * then a modify/write/read cycle when writing to a page in the
277  * page cache.
278  *
279  * The modify/write/read cycle may occur if a page is read before
280  * being completely filled by the writer.  In this situation, the
281  * page must be completely written to stable storage on the server
282  * before it can be refilled by reading in the page from the server.
283  * This can lead to expensive, small, FILE_SYNC mode writes being
284  * done.
285  *
286  * It may be more efficient to read the page first if the file is
287  * open for reading in addition to writing, the page is not marked
288  * as Uptodate, it is not dirty or waiting to be committed,
289  * indicating that it was previously allocated and then modified,
290  * that there were valid bytes of data in that range of the file,
291  * and that the new data won't completely replace the old data in
292  * that range of the file.
293  */
nfs_want_read_modify_write(struct file * file,struct page * page,loff_t pos,unsigned len)294 static int nfs_want_read_modify_write(struct file *file, struct page *page,
295 			loff_t pos, unsigned len)
296 {
297 	unsigned int pglen = nfs_page_length(page);
298 	unsigned int offset = pos & (PAGE_SIZE - 1);
299 	unsigned int end = offset + len;
300 
301 	if (pnfs_ld_read_whole_page(file->f_mapping->host)) {
302 		if (!PageUptodate(page))
303 			return 1;
304 		return 0;
305 	}
306 
307 	if ((file->f_mode & FMODE_READ) &&	/* open for read? */
308 	    !PageUptodate(page) &&		/* Uptodate? */
309 	    !PagePrivate(page) &&		/* i/o request already? */
310 	    pglen &&				/* valid bytes of file? */
311 	    (end < pglen || offset))		/* replace all valid bytes? */
312 		return 1;
313 	return 0;
314 }
315 
316 /*
317  * This does the "real" work of the write. We must allocate and lock the
318  * page to be sent back to the generic routine, which then copies the
319  * data from user space.
320  *
321  * If the writer ends up delaying the write, the writer needs to
322  * increment the page use counts until he is done with the page.
323  */
nfs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)324 static int nfs_write_begin(struct file *file, struct address_space *mapping,
325 			loff_t pos, unsigned len, unsigned flags,
326 			struct page **pagep, void **fsdata)
327 {
328 	int ret;
329 	pgoff_t index = pos >> PAGE_SHIFT;
330 	struct page *page;
331 	int once_thru = 0;
332 
333 	dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n",
334 		file, mapping->host->i_ino, len, (long long) pos);
335 
336 start:
337 	page = grab_cache_page_write_begin(mapping, index, flags);
338 	if (!page)
339 		return -ENOMEM;
340 	*pagep = page;
341 
342 	ret = nfs_flush_incompatible(file, page);
343 	if (ret) {
344 		unlock_page(page);
345 		put_page(page);
346 	} else if (!once_thru &&
347 		   nfs_want_read_modify_write(file, page, pos, len)) {
348 		once_thru = 1;
349 		ret = nfs_readpage(file, page);
350 		put_page(page);
351 		if (!ret)
352 			goto start;
353 	}
354 	return ret;
355 }
356 
nfs_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)357 static int nfs_write_end(struct file *file, struct address_space *mapping,
358 			loff_t pos, unsigned len, unsigned copied,
359 			struct page *page, void *fsdata)
360 {
361 	unsigned offset = pos & (PAGE_SIZE - 1);
362 	struct nfs_open_context *ctx = nfs_file_open_context(file);
363 	int status;
364 
365 	dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n",
366 		file, mapping->host->i_ino, len, (long long) pos);
367 
368 	/*
369 	 * Zero any uninitialised parts of the page, and then mark the page
370 	 * as up to date if it turns out that we're extending the file.
371 	 */
372 	if (!PageUptodate(page)) {
373 		unsigned pglen = nfs_page_length(page);
374 		unsigned end = offset + copied;
375 
376 		if (pglen == 0) {
377 			zero_user_segments(page, 0, offset,
378 					end, PAGE_SIZE);
379 			SetPageUptodate(page);
380 		} else if (end >= pglen) {
381 			zero_user_segment(page, end, PAGE_SIZE);
382 			if (offset == 0)
383 				SetPageUptodate(page);
384 		} else
385 			zero_user_segment(page, pglen, PAGE_SIZE);
386 	}
387 
388 	status = nfs_updatepage(file, page, offset, copied);
389 
390 	unlock_page(page);
391 	put_page(page);
392 
393 	if (status < 0)
394 		return status;
395 	NFS_I(mapping->host)->write_io += copied;
396 
397 	if (nfs_ctx_key_to_expire(ctx, mapping->host)) {
398 		status = nfs_wb_all(mapping->host);
399 		if (status < 0)
400 			return status;
401 	}
402 
403 	return copied;
404 }
405 
406 /*
407  * Partially or wholly invalidate a page
408  * - Release the private state associated with a page if undergoing complete
409  *   page invalidation
410  * - Called if either PG_private or PG_fscache is set on the page
411  * - Caller holds page lock
412  */
nfs_invalidate_page(struct page * page,unsigned int offset,unsigned int length)413 static void nfs_invalidate_page(struct page *page, unsigned int offset,
414 				unsigned int length)
415 {
416 	dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
417 		 page, offset, length);
418 
419 	if (offset != 0 || length < PAGE_SIZE)
420 		return;
421 	/* Cancel any unstarted writes on this page */
422 	nfs_wb_page_cancel(page_file_mapping(page)->host, page);
423 
424 	nfs_fscache_invalidate_page(page, page->mapping->host);
425 }
426 
427 /*
428  * Attempt to release the private state associated with a page
429  * - Called if either PG_private or PG_fscache is set on the page
430  * - Caller holds page lock
431  * - Return true (may release page) or false (may not)
432  */
nfs_release_page(struct page * page,gfp_t gfp)433 static int nfs_release_page(struct page *page, gfp_t gfp)
434 {
435 	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
436 
437 	/* If PagePrivate() is set, then the page is not freeable */
438 	if (PagePrivate(page))
439 		return 0;
440 	return nfs_fscache_release_page(page, gfp);
441 }
442 
nfs_check_dirty_writeback(struct page * page,bool * dirty,bool * writeback)443 static void nfs_check_dirty_writeback(struct page *page,
444 				bool *dirty, bool *writeback)
445 {
446 	struct nfs_inode *nfsi;
447 	struct address_space *mapping = page_file_mapping(page);
448 
449 	if (!mapping || PageSwapCache(page))
450 		return;
451 
452 	/*
453 	 * Check if an unstable page is currently being committed and
454 	 * if so, have the VM treat it as if the page is under writeback
455 	 * so it will not block due to pages that will shortly be freeable.
456 	 */
457 	nfsi = NFS_I(mapping->host);
458 	if (atomic_read(&nfsi->commit_info.rpcs_out)) {
459 		*writeback = true;
460 		return;
461 	}
462 
463 	/*
464 	 * If PagePrivate() is set, then the page is not freeable and as the
465 	 * inode is not being committed, it's not going to be cleaned in the
466 	 * near future so treat it as dirty
467 	 */
468 	if (PagePrivate(page))
469 		*dirty = true;
470 }
471 
472 /*
473  * Attempt to clear the private state associated with a page when an error
474  * occurs that requires the cached contents of an inode to be written back or
475  * destroyed
476  * - Called if either PG_private or fscache is set on the page
477  * - Caller holds page lock
478  * - Return 0 if successful, -error otherwise
479  */
nfs_launder_page(struct page * page)480 static int nfs_launder_page(struct page *page)
481 {
482 	struct inode *inode = page_file_mapping(page)->host;
483 	struct nfs_inode *nfsi = NFS_I(inode);
484 
485 	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
486 		inode->i_ino, (long long)page_offset(page));
487 
488 	nfs_fscache_wait_on_page_write(nfsi, page);
489 	return nfs_wb_page(inode, page);
490 }
491 
nfs_swap_activate(struct swap_info_struct * sis,struct file * file,sector_t * span)492 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
493 						sector_t *span)
494 {
495 	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
496 
497 	*span = sis->pages;
498 
499 	return rpc_clnt_swap_activate(clnt);
500 }
501 
nfs_swap_deactivate(struct file * file)502 static void nfs_swap_deactivate(struct file *file)
503 {
504 	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
505 
506 	rpc_clnt_swap_deactivate(clnt);
507 }
508 
509 const struct address_space_operations nfs_file_aops = {
510 	.readpage = nfs_readpage,
511 	.readpages = nfs_readpages,
512 	.set_page_dirty = __set_page_dirty_nobuffers,
513 	.writepage = nfs_writepage,
514 	.writepages = nfs_writepages,
515 	.write_begin = nfs_write_begin,
516 	.write_end = nfs_write_end,
517 	.invalidatepage = nfs_invalidate_page,
518 	.releasepage = nfs_release_page,
519 	.direct_IO = nfs_direct_IO,
520 #ifdef CONFIG_MIGRATION
521 	.migratepage = nfs_migrate_page,
522 #endif
523 	.launder_page = nfs_launder_page,
524 	.is_dirty_writeback = nfs_check_dirty_writeback,
525 	.error_remove_page = generic_error_remove_page,
526 	.swap_activate = nfs_swap_activate,
527 	.swap_deactivate = nfs_swap_deactivate,
528 };
529 
530 /*
531  * Notification that a PTE pointing to an NFS page is about to be made
532  * writable, implying that someone is about to modify the page through a
533  * shared-writable mapping
534  */
nfs_vm_page_mkwrite(struct vm_fault * vmf)535 static vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf)
536 {
537 	struct page *page = vmf->page;
538 	struct file *filp = vmf->vma->vm_file;
539 	struct inode *inode = file_inode(filp);
540 	unsigned pagelen;
541 	vm_fault_t ret = VM_FAULT_NOPAGE;
542 	struct address_space *mapping;
543 
544 	dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n",
545 		filp, filp->f_mapping->host->i_ino,
546 		(long long)page_offset(page));
547 
548 	sb_start_pagefault(inode->i_sb);
549 
550 	/* make sure the cache has finished storing the page */
551 	nfs_fscache_wait_on_page_write(NFS_I(inode), page);
552 
553 	wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
554 			nfs_wait_bit_killable, TASK_KILLABLE);
555 
556 	lock_page(page);
557 	mapping = page_file_mapping(page);
558 	if (mapping != inode->i_mapping)
559 		goto out_unlock;
560 
561 	wait_on_page_writeback(page);
562 
563 	pagelen = nfs_page_length(page);
564 	if (pagelen == 0)
565 		goto out_unlock;
566 
567 	ret = VM_FAULT_LOCKED;
568 	if (nfs_flush_incompatible(filp, page) == 0 &&
569 	    nfs_updatepage(filp, page, 0, pagelen) == 0)
570 		goto out;
571 
572 	ret = VM_FAULT_SIGBUS;
573 out_unlock:
574 	unlock_page(page);
575 out:
576 	sb_end_pagefault(inode->i_sb);
577 	return ret;
578 }
579 
580 static const struct vm_operations_struct nfs_file_vm_ops = {
581 	.fault = filemap_fault,
582 	.map_pages = filemap_map_pages,
583 	.page_mkwrite = nfs_vm_page_mkwrite,
584 };
585 
nfs_need_check_write(struct file * filp,struct inode * inode)586 static int nfs_need_check_write(struct file *filp, struct inode *inode)
587 {
588 	struct nfs_open_context *ctx;
589 
590 	ctx = nfs_file_open_context(filp);
591 	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags) ||
592 	    nfs_ctx_key_to_expire(ctx, inode))
593 		return 1;
594 	return 0;
595 }
596 
nfs_file_write(struct kiocb * iocb,struct iov_iter * from)597 ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
598 {
599 	struct file *file = iocb->ki_filp;
600 	struct inode *inode = file_inode(file);
601 	unsigned long written = 0;
602 	ssize_t result;
603 
604 	result = nfs_key_timeout_notify(file, inode);
605 	if (result)
606 		return result;
607 
608 	if (iocb->ki_flags & IOCB_DIRECT)
609 		return nfs_file_direct_write(iocb, from, false);
610 
611 	dprintk("NFS: write(%pD2, %zu@%Ld)\n",
612 		file, iov_iter_count(from), (long long) iocb->ki_pos);
613 
614 	if (IS_SWAPFILE(inode))
615 		goto out_swapfile;
616 	/*
617 	 * O_APPEND implies that we must revalidate the file length.
618 	 */
619 	if (iocb->ki_flags & IOCB_APPEND) {
620 		result = nfs_revalidate_file_size(inode, file);
621 		if (result)
622 			goto out;
623 	}
624 	if (iocb->ki_pos > i_size_read(inode))
625 		nfs_revalidate_mapping(inode, file->f_mapping);
626 
627 	nfs_start_io_write(inode);
628 	result = generic_write_checks(iocb, from);
629 	if (result > 0) {
630 		current->backing_dev_info = inode_to_bdi(inode);
631 		result = generic_perform_write(file, from, iocb->ki_pos);
632 		current->backing_dev_info = NULL;
633 	}
634 	nfs_end_io_write(inode);
635 	if (result <= 0)
636 		goto out;
637 
638 	written = result;
639 	iocb->ki_pos += written;
640 	result = generic_write_sync(iocb, written);
641 	if (result < 0)
642 		goto out;
643 
644 	/* Return error values */
645 	if (nfs_need_check_write(file, inode)) {
646 		int err = vfs_fsync(file, 0);
647 		if (err < 0)
648 			result = err;
649 	}
650 	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
651 out:
652 	return result;
653 
654 out_swapfile:
655 	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
656 	return -EBUSY;
657 }
658 EXPORT_SYMBOL_GPL(nfs_file_write);
659 
660 static int
do_getlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)661 do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
662 {
663 	struct inode *inode = filp->f_mapping->host;
664 	int status = 0;
665 	unsigned int saved_type = fl->fl_type;
666 
667 	/* Try local locking first */
668 	posix_test_lock(filp, fl);
669 	if (fl->fl_type != F_UNLCK) {
670 		/* found a conflict */
671 		goto out;
672 	}
673 	fl->fl_type = saved_type;
674 
675 	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
676 		goto out_noconflict;
677 
678 	if (is_local)
679 		goto out_noconflict;
680 
681 	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
682 out:
683 	return status;
684 out_noconflict:
685 	fl->fl_type = F_UNLCK;
686 	goto out;
687 }
688 
689 static int
do_unlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)690 do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
691 {
692 	struct inode *inode = filp->f_mapping->host;
693 	struct nfs_lock_context *l_ctx;
694 	int status;
695 
696 	/*
697 	 * Flush all pending writes before doing anything
698 	 * with locks..
699 	 */
700 	vfs_fsync(filp, 0);
701 
702 	l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
703 	if (!IS_ERR(l_ctx)) {
704 		status = nfs_iocounter_wait(l_ctx);
705 		nfs_put_lock_context(l_ctx);
706 		/*  NOTE: special case
707 		 * 	If we're signalled while cleaning up locks on process exit, we
708 		 * 	still need to complete the unlock.
709 		 */
710 		if (status < 0 && !(fl->fl_flags & FL_CLOSE))
711 			return status;
712 	}
713 
714 	/*
715 	 * Use local locking if mounted with "-onolock" or with appropriate
716 	 * "-olocal_lock="
717 	 */
718 	if (!is_local)
719 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
720 	else
721 		status = locks_lock_file_wait(filp, fl);
722 	return status;
723 }
724 
725 static int
do_setlk(struct file * filp,int cmd,struct file_lock * fl,int is_local)726 do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
727 {
728 	struct inode *inode = filp->f_mapping->host;
729 	int status;
730 
731 	/*
732 	 * Flush all pending writes before doing anything
733 	 * with locks..
734 	 */
735 	status = nfs_sync_mapping(filp->f_mapping);
736 	if (status != 0)
737 		goto out;
738 
739 	/*
740 	 * Use local locking if mounted with "-onolock" or with appropriate
741 	 * "-olocal_lock="
742 	 */
743 	if (!is_local)
744 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
745 	else
746 		status = locks_lock_file_wait(filp, fl);
747 	if (status < 0)
748 		goto out;
749 
750 	/*
751 	 * Invalidate cache to prevent missing any changes.  If
752 	 * the file is mapped, clear the page cache as well so
753 	 * those mappings will be loaded.
754 	 *
755 	 * This makes locking act as a cache coherency point.
756 	 */
757 	nfs_sync_mapping(filp->f_mapping);
758 	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
759 		nfs_zap_caches(inode);
760 		if (mapping_mapped(filp->f_mapping))
761 			nfs_revalidate_mapping(inode, filp->f_mapping);
762 	}
763 out:
764 	return status;
765 }
766 
767 /*
768  * Lock a (portion of) a file
769  */
nfs_lock(struct file * filp,int cmd,struct file_lock * fl)770 int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
771 {
772 	struct inode *inode = filp->f_mapping->host;
773 	int ret = -ENOLCK;
774 	int is_local = 0;
775 
776 	dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)\n",
777 			filp, fl->fl_type, fl->fl_flags,
778 			(long long)fl->fl_start, (long long)fl->fl_end);
779 
780 	nfs_inc_stats(inode, NFSIOS_VFSLOCK);
781 
782 	/* No mandatory locks over NFS */
783 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
784 		goto out_err;
785 
786 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
787 		is_local = 1;
788 
789 	if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
790 		ret = NFS_PROTO(inode)->lock_check_bounds(fl);
791 		if (ret < 0)
792 			goto out_err;
793 	}
794 
795 	if (IS_GETLK(cmd))
796 		ret = do_getlk(filp, cmd, fl, is_local);
797 	else if (fl->fl_type == F_UNLCK)
798 		ret = do_unlk(filp, cmd, fl, is_local);
799 	else
800 		ret = do_setlk(filp, cmd, fl, is_local);
801 out_err:
802 	return ret;
803 }
804 EXPORT_SYMBOL_GPL(nfs_lock);
805 
806 /*
807  * Lock a (portion of) a file
808  */
nfs_flock(struct file * filp,int cmd,struct file_lock * fl)809 int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
810 {
811 	struct inode *inode = filp->f_mapping->host;
812 	int is_local = 0;
813 
814 	dprintk("NFS: flock(%pD2, t=%x, fl=%x)\n",
815 			filp, fl->fl_type, fl->fl_flags);
816 
817 	if (!(fl->fl_flags & FL_FLOCK))
818 		return -ENOLCK;
819 
820 	/*
821 	 * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
822 	 * any standard. In principle we might be able to support LOCK_MAND
823 	 * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
824 	 * NFS code is not set up for it.
825 	 */
826 	if (fl->fl_type & LOCK_MAND)
827 		return -EINVAL;
828 
829 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
830 		is_local = 1;
831 
832 	/* We're simulating flock() locks using posix locks on the server */
833 	if (fl->fl_type == F_UNLCK)
834 		return do_unlk(filp, cmd, fl, is_local);
835 	return do_setlk(filp, cmd, fl, is_local);
836 }
837 EXPORT_SYMBOL_GPL(nfs_flock);
838 
839 const struct file_operations nfs_file_operations = {
840 	.llseek		= nfs_file_llseek,
841 	.read_iter	= nfs_file_read,
842 	.write_iter	= nfs_file_write,
843 	.mmap		= nfs_file_mmap,
844 	.open		= nfs_file_open,
845 	.flush		= nfs_file_flush,
846 	.release	= nfs_file_release,
847 	.fsync		= nfs_file_fsync,
848 	.lock		= nfs_lock,
849 	.flock		= nfs_flock,
850 	.splice_read	= generic_file_splice_read,
851 	.splice_write	= iter_file_splice_write,
852 	.check_flags	= nfs_check_flags,
853 	.setlease	= simple_nosetlease,
854 };
855 EXPORT_SYMBOL_GPL(nfs_file_operations);
856