xref: /openbmc/linux/fs/nfs/file.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/time.h>
20 #include <linux/kernel.h>
21 #include <linux/errno.h>
22 #include <linux/fcntl.h>
23 #include <linux/stat.h>
24 #include <linux/nfs_fs.h>
25 #include <linux/nfs_mount.h>
26 #include <linux/mm.h>
27 #include <linux/slab.h>
28 #include <linux/pagemap.h>
29 #include <linux/smp_lock.h>
30 
31 #include <asm/uaccess.h>
32 #include <asm/system.h>
33 
34 #include "delegation.h"
35 #include "iostat.h"
36 
37 #define NFSDBG_FACILITY		NFSDBG_FILE
38 
39 static int nfs_file_open(struct inode *, struct file *);
40 static int nfs_file_release(struct inode *, struct file *);
41 static loff_t nfs_file_llseek(struct file *file, loff_t offset, int origin);
42 static int  nfs_file_mmap(struct file *, struct vm_area_struct *);
43 static ssize_t nfs_file_sendfile(struct file *, loff_t *, size_t, read_actor_t, void *);
44 static ssize_t nfs_file_read(struct kiocb *, const struct iovec *iov,
45 				unsigned long nr_segs, loff_t pos);
46 static ssize_t nfs_file_write(struct kiocb *, const struct iovec *iov,
47 				unsigned long nr_segs, loff_t pos);
48 static int  nfs_file_flush(struct file *, fl_owner_t id);
49 static int  nfs_fsync(struct file *, struct dentry *dentry, int datasync);
50 static int nfs_check_flags(int flags);
51 static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl);
52 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl);
53 
54 const struct file_operations nfs_file_operations = {
55 	.llseek		= nfs_file_llseek,
56 	.read		= do_sync_read,
57 	.write		= do_sync_write,
58 	.aio_read	= nfs_file_read,
59 	.aio_write	= nfs_file_write,
60 	.mmap		= nfs_file_mmap,
61 	.open		= nfs_file_open,
62 	.flush		= nfs_file_flush,
63 	.release	= nfs_file_release,
64 	.fsync		= nfs_fsync,
65 	.lock		= nfs_lock,
66 	.flock		= nfs_flock,
67 	.sendfile	= nfs_file_sendfile,
68 	.check_flags	= nfs_check_flags,
69 };
70 
71 const struct inode_operations nfs_file_inode_operations = {
72 	.permission	= nfs_permission,
73 	.getattr	= nfs_getattr,
74 	.setattr	= nfs_setattr,
75 };
76 
77 #ifdef CONFIG_NFS_V3
78 const struct inode_operations nfs3_file_inode_operations = {
79 	.permission	= nfs_permission,
80 	.getattr	= nfs_getattr,
81 	.setattr	= nfs_setattr,
82 	.listxattr	= nfs3_listxattr,
83 	.getxattr	= nfs3_getxattr,
84 	.setxattr	= nfs3_setxattr,
85 	.removexattr	= nfs3_removexattr,
86 };
87 #endif  /* CONFIG_NFS_v3 */
88 
89 /* Hack for future NFS swap support */
90 #ifndef IS_SWAPFILE
91 # define IS_SWAPFILE(inode)	(0)
92 #endif
93 
94 static int nfs_check_flags(int flags)
95 {
96 	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
97 		return -EINVAL;
98 
99 	return 0;
100 }
101 
102 /*
103  * Open file
104  */
105 static int
106 nfs_file_open(struct inode *inode, struct file *filp)
107 {
108 	int res;
109 
110 	res = nfs_check_flags(filp->f_flags);
111 	if (res)
112 		return res;
113 
114 	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
115 	lock_kernel();
116 	res = NFS_PROTO(inode)->file_open(inode, filp);
117 	unlock_kernel();
118 	return res;
119 }
120 
121 static int
122 nfs_file_release(struct inode *inode, struct file *filp)
123 {
124 	/* Ensure that dirty pages are flushed out with the right creds */
125 	if (filp->f_mode & FMODE_WRITE)
126 		filemap_fdatawrite(filp->f_mapping);
127 	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
128 	return NFS_PROTO(inode)->file_release(inode, filp);
129 }
130 
131 /**
132  * nfs_revalidate_size - Revalidate the file size
133  * @inode - pointer to inode struct
134  * @file - pointer to struct file
135  *
136  * Revalidates the file length. This is basically a wrapper around
137  * nfs_revalidate_inode() that takes into account the fact that we may
138  * have cached writes (in which case we don't care about the server's
139  * idea of what the file length is), or O_DIRECT (in which case we
140  * shouldn't trust the cache).
141  */
142 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
143 {
144 	struct nfs_server *server = NFS_SERVER(inode);
145 	struct nfs_inode *nfsi = NFS_I(inode);
146 
147 	if (server->flags & NFS_MOUNT_NOAC)
148 		goto force_reval;
149 	if (filp->f_flags & O_DIRECT)
150 		goto force_reval;
151 	if (nfsi->npages != 0)
152 		return 0;
153 	if (!(nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE) && !nfs_attribute_timeout(inode))
154 		return 0;
155 force_reval:
156 	return __nfs_revalidate_inode(server, inode);
157 }
158 
159 static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
160 {
161 	/* origin == SEEK_END => we must revalidate the cached file length */
162 	if (origin == SEEK_END) {
163 		struct inode *inode = filp->f_mapping->host;
164 		int retval = nfs_revalidate_file_size(inode, filp);
165 		if (retval < 0)
166 			return (loff_t)retval;
167 	}
168 	return remote_llseek(filp, offset, origin);
169 }
170 
171 /*
172  * Flush all dirty pages, and check for write errors.
173  *
174  */
175 static int
176 nfs_file_flush(struct file *file, fl_owner_t id)
177 {
178 	struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
179 	struct inode	*inode = file->f_path.dentry->d_inode;
180 	int		status;
181 
182 	dfprintk(VFS, "nfs: flush(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
183 
184 	if ((file->f_mode & FMODE_WRITE) == 0)
185 		return 0;
186 	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
187 	lock_kernel();
188 	/* Ensure that data+attribute caches are up to date after close() */
189 	status = nfs_wb_all(inode);
190 	if (!status) {
191 		status = ctx->error;
192 		ctx->error = 0;
193 		if (!status)
194 			nfs_revalidate_inode(NFS_SERVER(inode), inode);
195 	}
196 	unlock_kernel();
197 	return status;
198 }
199 
200 static ssize_t
201 nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
202 		unsigned long nr_segs, loff_t pos)
203 {
204 	struct dentry * dentry = iocb->ki_filp->f_path.dentry;
205 	struct inode * inode = dentry->d_inode;
206 	ssize_t result;
207 	size_t count = iov_length(iov, nr_segs);
208 
209 #ifdef CONFIG_NFS_DIRECTIO
210 	if (iocb->ki_filp->f_flags & O_DIRECT)
211 		return nfs_file_direct_read(iocb, iov, nr_segs, pos);
212 #endif
213 
214 	dfprintk(VFS, "nfs: read(%s/%s, %lu@%lu)\n",
215 		dentry->d_parent->d_name.name, dentry->d_name.name,
216 		(unsigned long) count, (unsigned long) pos);
217 
218 	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
219 	nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, count);
220 	if (!result)
221 		result = generic_file_aio_read(iocb, iov, nr_segs, pos);
222 	return result;
223 }
224 
225 static ssize_t
226 nfs_file_sendfile(struct file *filp, loff_t *ppos, size_t count,
227 		read_actor_t actor, void *target)
228 {
229 	struct dentry *dentry = filp->f_path.dentry;
230 	struct inode *inode = dentry->d_inode;
231 	ssize_t res;
232 
233 	dfprintk(VFS, "nfs: sendfile(%s/%s, %lu@%Lu)\n",
234 		dentry->d_parent->d_name.name, dentry->d_name.name,
235 		(unsigned long) count, (unsigned long long) *ppos);
236 
237 	res = nfs_revalidate_mapping(inode, filp->f_mapping);
238 	if (!res)
239 		res = generic_file_sendfile(filp, ppos, count, actor, target);
240 	return res;
241 }
242 
243 static int
244 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
245 {
246 	struct dentry *dentry = file->f_path.dentry;
247 	struct inode *inode = dentry->d_inode;
248 	int	status;
249 
250 	dfprintk(VFS, "nfs: mmap(%s/%s)\n",
251 		dentry->d_parent->d_name.name, dentry->d_name.name);
252 
253 	status = nfs_revalidate_mapping(inode, file->f_mapping);
254 	if (!status)
255 		status = generic_file_mmap(file, vma);
256 	return status;
257 }
258 
259 /*
260  * Flush any dirty pages for this process, and check for write errors.
261  * The return status from this call provides a reliable indication of
262  * whether any write errors occurred for this process.
263  */
264 static int
265 nfs_fsync(struct file *file, struct dentry *dentry, int datasync)
266 {
267 	struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
268 	struct inode *inode = dentry->d_inode;
269 	int status;
270 
271 	dfprintk(VFS, "nfs: fsync(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
272 
273 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
274 	lock_kernel();
275 	status = nfs_wb_all(inode);
276 	if (!status) {
277 		status = ctx->error;
278 		ctx->error = 0;
279 	}
280 	unlock_kernel();
281 	return status;
282 }
283 
284 /*
285  * This does the "real" work of the write. The generic routine has
286  * allocated the page, locked it, done all the page alignment stuff
287  * calculations etc. Now we should just copy the data from user
288  * space and write it back to the real medium..
289  *
290  * If the writer ends up delaying the write, the writer needs to
291  * increment the page use counts until he is done with the page.
292  */
293 static int nfs_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
294 {
295 	return nfs_flush_incompatible(file, page);
296 }
297 
298 static int nfs_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to)
299 {
300 	long status;
301 
302 	lock_kernel();
303 	status = nfs_updatepage(file, page, offset, to-offset);
304 	unlock_kernel();
305 	return status;
306 }
307 
308 static void nfs_invalidate_page(struct page *page, unsigned long offset)
309 {
310 	if (offset != 0)
311 		return;
312 	/* Cancel any unstarted writes on this page */
313 	nfs_wb_page_priority(page->mapping->host, page, FLUSH_INVALIDATE);
314 }
315 
316 static int nfs_release_page(struct page *page, gfp_t gfp)
317 {
318 	/* If PagePrivate() is set, then the page is not freeable */
319 	return 0;
320 }
321 
322 static int nfs_launder_page(struct page *page)
323 {
324 	return nfs_wb_page(page->mapping->host, page);
325 }
326 
327 const struct address_space_operations nfs_file_aops = {
328 	.readpage = nfs_readpage,
329 	.readpages = nfs_readpages,
330 	.set_page_dirty = nfs_set_page_dirty,
331 	.writepage = nfs_writepage,
332 	.writepages = nfs_writepages,
333 	.prepare_write = nfs_prepare_write,
334 	.commit_write = nfs_commit_write,
335 	.invalidatepage = nfs_invalidate_page,
336 	.releasepage = nfs_release_page,
337 #ifdef CONFIG_NFS_DIRECTIO
338 	.direct_IO = nfs_direct_IO,
339 #endif
340 	.launder_page = nfs_launder_page,
341 };
342 
343 static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
344 				unsigned long nr_segs, loff_t pos)
345 {
346 	struct dentry * dentry = iocb->ki_filp->f_path.dentry;
347 	struct inode * inode = dentry->d_inode;
348 	ssize_t result;
349 	size_t count = iov_length(iov, nr_segs);
350 
351 #ifdef CONFIG_NFS_DIRECTIO
352 	if (iocb->ki_filp->f_flags & O_DIRECT)
353 		return nfs_file_direct_write(iocb, iov, nr_segs, pos);
354 #endif
355 
356 	dfprintk(VFS, "nfs: write(%s/%s(%ld), %lu@%Ld)\n",
357 		dentry->d_parent->d_name.name, dentry->d_name.name,
358 		inode->i_ino, (unsigned long) count, (long long) pos);
359 
360 	result = -EBUSY;
361 	if (IS_SWAPFILE(inode))
362 		goto out_swapfile;
363 	/*
364 	 * O_APPEND implies that we must revalidate the file length.
365 	 */
366 	if (iocb->ki_filp->f_flags & O_APPEND) {
367 		result = nfs_revalidate_file_size(inode, iocb->ki_filp);
368 		if (result)
369 			goto out;
370 	}
371 
372 	result = count;
373 	if (!count)
374 		goto out;
375 
376 	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, count);
377 	result = generic_file_aio_write(iocb, iov, nr_segs, pos);
378 	/* Return error values for O_SYNC and IS_SYNC() */
379 	if (result >= 0 && (IS_SYNC(inode) || (iocb->ki_filp->f_flags & O_SYNC))) {
380 		int err = nfs_fsync(iocb->ki_filp, dentry, 1);
381 		if (err < 0)
382 			result = err;
383 	}
384 out:
385 	return result;
386 
387 out_swapfile:
388 	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
389 	goto out;
390 }
391 
392 static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
393 {
394 	struct inode *inode = filp->f_mapping->host;
395 	int status = 0;
396 
397 	lock_kernel();
398 	/* Try local locking first */
399 	if (posix_test_lock(filp, fl)) {
400 		goto out;
401 	}
402 
403 	if (nfs_have_delegation(inode, FMODE_READ))
404 		goto out_noconflict;
405 
406 	if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)
407 		goto out_noconflict;
408 
409 	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
410 out:
411 	unlock_kernel();
412 	return status;
413 out_noconflict:
414 	fl->fl_type = F_UNLCK;
415 	goto out;
416 }
417 
418 static int do_vfs_lock(struct file *file, struct file_lock *fl)
419 {
420 	int res = 0;
421 	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
422 		case FL_POSIX:
423 			res = posix_lock_file_wait(file, fl);
424 			break;
425 		case FL_FLOCK:
426 			res = flock_lock_file_wait(file, fl);
427 			break;
428 		default:
429 			BUG();
430 	}
431 	if (res < 0)
432 		dprintk(KERN_WARNING "%s: VFS is out of sync with lock manager"
433 			" - error %d!\n",
434 				__FUNCTION__, res);
435 	return res;
436 }
437 
438 static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
439 {
440 	struct inode *inode = filp->f_mapping->host;
441 	int status;
442 
443 	/*
444 	 * Flush all pending writes before doing anything
445 	 * with locks..
446 	 */
447 	nfs_sync_mapping(filp->f_mapping);
448 
449 	/* NOTE: special case
450 	 * 	If we're signalled while cleaning up locks on process exit, we
451 	 * 	still need to complete the unlock.
452 	 */
453 	lock_kernel();
454 	/* Use local locking if mounted with "-onolock" */
455 	if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
456 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
457 	else
458 		status = do_vfs_lock(filp, fl);
459 	unlock_kernel();
460 	return status;
461 }
462 
463 static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
464 {
465 	struct inode *inode = filp->f_mapping->host;
466 	int status;
467 
468 	/*
469 	 * Flush all pending writes before doing anything
470 	 * with locks..
471 	 */
472 	status = nfs_sync_mapping(filp->f_mapping);
473 	if (status != 0)
474 		goto out;
475 
476 	lock_kernel();
477 	/* Use local locking if mounted with "-onolock" */
478 	if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)) {
479 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
480 		/* If we were signalled we still need to ensure that
481 		 * we clean up any state on the server. We therefore
482 		 * record the lock call as having succeeded in order to
483 		 * ensure that locks_remove_posix() cleans it out when
484 		 * the process exits.
485 		 */
486 		if (status == -EINTR || status == -ERESTARTSYS)
487 			do_vfs_lock(filp, fl);
488 	} else
489 		status = do_vfs_lock(filp, fl);
490 	unlock_kernel();
491 	if (status < 0)
492 		goto out;
493 	/*
494 	 * Make sure we clear the cache whenever we try to get the lock.
495 	 * This makes locking act as a cache coherency point.
496 	 */
497 	nfs_sync_mapping(filp->f_mapping);
498 	nfs_zap_caches(inode);
499 out:
500 	return status;
501 }
502 
503 /*
504  * Lock a (portion of) a file
505  */
506 static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
507 {
508 	struct inode * inode = filp->f_mapping->host;
509 
510 	dprintk("NFS: nfs_lock(f=%s/%ld, t=%x, fl=%x, r=%Ld:%Ld)\n",
511 			inode->i_sb->s_id, inode->i_ino,
512 			fl->fl_type, fl->fl_flags,
513 			(long long)fl->fl_start, (long long)fl->fl_end);
514 	nfs_inc_stats(inode, NFSIOS_VFSLOCK);
515 
516 	/* No mandatory locks over NFS */
517 	if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
518 	    fl->fl_type != F_UNLCK)
519 		return -ENOLCK;
520 
521 	if (IS_GETLK(cmd))
522 		return do_getlk(filp, cmd, fl);
523 	if (fl->fl_type == F_UNLCK)
524 		return do_unlk(filp, cmd, fl);
525 	return do_setlk(filp, cmd, fl);
526 }
527 
528 /*
529  * Lock a (portion of) a file
530  */
531 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
532 {
533 	dprintk("NFS: nfs_flock(f=%s/%ld, t=%x, fl=%x)\n",
534 			filp->f_path.dentry->d_inode->i_sb->s_id,
535 			filp->f_path.dentry->d_inode->i_ino,
536 			fl->fl_type, fl->fl_flags);
537 
538 	/*
539 	 * No BSD flocks over NFS allowed.
540 	 * Note: we could try to fake a POSIX lock request here by
541 	 * using ((u32) filp | 0x80000000) or some such as the pid.
542 	 * Not sure whether that would be unique, though, or whether
543 	 * that would break in other places.
544 	 */
545 	if (!(fl->fl_flags & FL_FLOCK))
546 		return -ENOLCK;
547 
548 	/* We're simulating flock() locks using posix locks on the server */
549 	fl->fl_owner = (fl_owner_t)filp;
550 	fl->fl_start = 0;
551 	fl->fl_end = OFFSET_MAX;
552 
553 	if (fl->fl_type == F_UNLCK)
554 		return do_unlk(filp, cmd, fl);
555 	return do_setlk(filp, cmd, fl);
556 }
557