xref: /linux/fs/9p/vfs_file.c (revision 2a2c74b2efcb1a0ca3fdcb5fbb96ad8de6a29177)
1 /*
2  *  linux/fs/9p/vfs_file.c
3  *
4  * This file contians vfs file ops for 9P2000.
5  *
6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
7  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
8  *
9  *  This program is free software; you can redistribute it and/or modify
10  *  it under the terms of the GNU General Public License version 2
11  *  as published by the Free Software Foundation.
12  *
13  *  This program is distributed in the hope that it will be useful,
14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  *  GNU General Public License for more details.
17  *
18  *  You should have received a copy of the GNU General Public License
19  *  along with this program; if not, write to:
20  *  Free Software Foundation
21  *  51 Franklin Street, Fifth Floor
22  *  Boston, MA  02111-1301  USA
23  *
24  */
25 
26 #include <linux/module.h>
27 #include <linux/errno.h>
28 #include <linux/fs.h>
29 #include <linux/sched.h>
30 #include <linux/file.h>
31 #include <linux/stat.h>
32 #include <linux/string.h>
33 #include <linux/inet.h>
34 #include <linux/list.h>
35 #include <linux/pagemap.h>
36 #include <linux/utsname.h>
37 #include <asm/uaccess.h>
38 #include <linux/idr.h>
39 #include <net/9p/9p.h>
40 #include <net/9p/client.h>
41 
42 #include "v9fs.h"
43 #include "v9fs_vfs.h"
44 #include "fid.h"
45 #include "cache.h"
46 
47 static const struct vm_operations_struct v9fs_file_vm_ops;
48 static const struct vm_operations_struct v9fs_mmap_file_vm_ops;
49 
50 /**
51  * v9fs_file_open - open a file (or directory)
52  * @inode: inode to be opened
53  * @file: file being opened
54  *
55  */
56 
57 int v9fs_file_open(struct inode *inode, struct file *file)
58 {
59 	int err;
60 	struct v9fs_inode *v9inode;
61 	struct v9fs_session_info *v9ses;
62 	struct p9_fid *fid;
63 	int omode;
64 
65 	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
66 	v9inode = V9FS_I(inode);
67 	v9ses = v9fs_inode2v9ses(inode);
68 	if (v9fs_proto_dotl(v9ses))
69 		omode = v9fs_open_to_dotl_flags(file->f_flags);
70 	else
71 		omode = v9fs_uflags2omode(file->f_flags,
72 					v9fs_proto_dotu(v9ses));
73 	fid = file->private_data;
74 	if (!fid) {
75 		fid = v9fs_fid_clone(file->f_path.dentry);
76 		if (IS_ERR(fid))
77 			return PTR_ERR(fid);
78 
79 		err = p9_client_open(fid, omode);
80 		if (err < 0) {
81 			p9_client_clunk(fid);
82 			return err;
83 		}
84 		if ((file->f_flags & O_APPEND) &&
85 			(!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
86 			generic_file_llseek(file, 0, SEEK_END);
87 	}
88 
89 	file->private_data = fid;
90 	mutex_lock(&v9inode->v_mutex);
91 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
92 	    !v9inode->writeback_fid &&
93 	    ((file->f_flags & O_ACCMODE) != O_RDONLY)) {
94 		/*
95 		 * clone a fid and add it to writeback_fid
96 		 * we do it during open time instead of
97 		 * page dirty time via write_begin/page_mkwrite
98 		 * because we want write after unlink usecase
99 		 * to work.
100 		 */
101 		fid = v9fs_writeback_fid(file->f_path.dentry);
102 		if (IS_ERR(fid)) {
103 			err = PTR_ERR(fid);
104 			mutex_unlock(&v9inode->v_mutex);
105 			goto out_error;
106 		}
107 		v9inode->writeback_fid = (void *) fid;
108 	}
109 	mutex_unlock(&v9inode->v_mutex);
110 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
111 		v9fs_cache_inode_set_cookie(inode, file);
112 	return 0;
113 out_error:
114 	p9_client_clunk(file->private_data);
115 	file->private_data = NULL;
116 	return err;
117 }
118 
119 /**
120  * v9fs_file_lock - lock a file (or directory)
121  * @filp: file to be locked
122  * @cmd: lock command
123  * @fl: file lock structure
124  *
125  * Bugs: this looks like a local only lock, we should extend into 9P
126  *       by using open exclusive
127  */
128 
129 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
130 {
131 	int res = 0;
132 	struct inode *inode = file_inode(filp);
133 
134 	p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
135 
136 	/* No mandatory locks */
137 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
138 		return -ENOLCK;
139 
140 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
141 		filemap_write_and_wait(inode->i_mapping);
142 		invalidate_mapping_pages(&inode->i_data, 0, -1);
143 	}
144 
145 	return res;
146 }
147 
148 static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
149 {
150 	struct p9_flock flock;
151 	struct p9_fid *fid;
152 	uint8_t status;
153 	int res = 0;
154 	unsigned char fl_type;
155 
156 	fid = filp->private_data;
157 	BUG_ON(fid == NULL);
158 
159 	if ((fl->fl_flags & FL_POSIX) != FL_POSIX)
160 		BUG();
161 
162 	res = posix_lock_file_wait(filp, fl);
163 	if (res < 0)
164 		goto out;
165 
166 	/* convert posix lock to p9 tlock args */
167 	memset(&flock, 0, sizeof(flock));
168 	/* map the lock type */
169 	switch (fl->fl_type) {
170 	case F_RDLCK:
171 		flock.type = P9_LOCK_TYPE_RDLCK;
172 		break;
173 	case F_WRLCK:
174 		flock.type = P9_LOCK_TYPE_WRLCK;
175 		break;
176 	case F_UNLCK:
177 		flock.type = P9_LOCK_TYPE_UNLCK;
178 		break;
179 	}
180 	flock.start = fl->fl_start;
181 	if (fl->fl_end == OFFSET_MAX)
182 		flock.length = 0;
183 	else
184 		flock.length = fl->fl_end - fl->fl_start + 1;
185 	flock.proc_id = fl->fl_pid;
186 	flock.client_id = fid->clnt->name;
187 	if (IS_SETLKW(cmd))
188 		flock.flags = P9_LOCK_FLAGS_BLOCK;
189 
190 	/*
191 	 * if its a blocked request and we get P9_LOCK_BLOCKED as the status
192 	 * for lock request, keep on trying
193 	 */
194 	for (;;) {
195 		res = p9_client_lock_dotl(fid, &flock, &status);
196 		if (res < 0)
197 			break;
198 
199 		if (status != P9_LOCK_BLOCKED)
200 			break;
201 		if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
202 			break;
203 		if (schedule_timeout_interruptible(P9_LOCK_TIMEOUT) != 0)
204 			break;
205 	}
206 
207 	/* map 9p status to VFS status */
208 	switch (status) {
209 	case P9_LOCK_SUCCESS:
210 		res = 0;
211 		break;
212 	case P9_LOCK_BLOCKED:
213 		res = -EAGAIN;
214 		break;
215 	case P9_LOCK_ERROR:
216 	case P9_LOCK_GRACE:
217 		res = -ENOLCK;
218 		break;
219 	default:
220 		BUG();
221 	}
222 
223 	/*
224 	 * incase server returned error for lock request, revert
225 	 * it locally
226 	 */
227 	if (res < 0 && fl->fl_type != F_UNLCK) {
228 		fl_type = fl->fl_type;
229 		fl->fl_type = F_UNLCK;
230 		res = posix_lock_file_wait(filp, fl);
231 		fl->fl_type = fl_type;
232 	}
233 out:
234 	return res;
235 }
236 
237 static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
238 {
239 	struct p9_getlock glock;
240 	struct p9_fid *fid;
241 	int res = 0;
242 
243 	fid = filp->private_data;
244 	BUG_ON(fid == NULL);
245 
246 	posix_test_lock(filp, fl);
247 	/*
248 	 * if we have a conflicting lock locally, no need to validate
249 	 * with server
250 	 */
251 	if (fl->fl_type != F_UNLCK)
252 		return res;
253 
254 	/* convert posix lock to p9 tgetlock args */
255 	memset(&glock, 0, sizeof(glock));
256 	glock.type  = P9_LOCK_TYPE_UNLCK;
257 	glock.start = fl->fl_start;
258 	if (fl->fl_end == OFFSET_MAX)
259 		glock.length = 0;
260 	else
261 		glock.length = fl->fl_end - fl->fl_start + 1;
262 	glock.proc_id = fl->fl_pid;
263 	glock.client_id = fid->clnt->name;
264 
265 	res = p9_client_getlock_dotl(fid, &glock);
266 	if (res < 0)
267 		return res;
268 	/* map 9p lock type to os lock type */
269 	switch (glock.type) {
270 	case P9_LOCK_TYPE_RDLCK:
271 		fl->fl_type = F_RDLCK;
272 		break;
273 	case P9_LOCK_TYPE_WRLCK:
274 		fl->fl_type = F_WRLCK;
275 		break;
276 	case P9_LOCK_TYPE_UNLCK:
277 		fl->fl_type = F_UNLCK;
278 		break;
279 	}
280 	if (glock.type != P9_LOCK_TYPE_UNLCK) {
281 		fl->fl_start = glock.start;
282 		if (glock.length == 0)
283 			fl->fl_end = OFFSET_MAX;
284 		else
285 			fl->fl_end = glock.start + glock.length - 1;
286 		fl->fl_pid = glock.proc_id;
287 	}
288 	return res;
289 }
290 
291 /**
292  * v9fs_file_lock_dotl - lock a file (or directory)
293  * @filp: file to be locked
294  * @cmd: lock command
295  * @fl: file lock structure
296  *
297  */
298 
299 static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
300 {
301 	struct inode *inode = file_inode(filp);
302 	int ret = -ENOLCK;
303 
304 	p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n",
305 		 filp, cmd, fl, filp->f_path.dentry->d_name.name);
306 
307 	/* No mandatory locks */
308 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
309 		goto out_err;
310 
311 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
312 		filemap_write_and_wait(inode->i_mapping);
313 		invalidate_mapping_pages(&inode->i_data, 0, -1);
314 	}
315 
316 	if (IS_SETLK(cmd) || IS_SETLKW(cmd))
317 		ret = v9fs_file_do_lock(filp, cmd, fl);
318 	else if (IS_GETLK(cmd))
319 		ret = v9fs_file_getlock(filp, fl);
320 	else
321 		ret = -EINVAL;
322 out_err:
323 	return ret;
324 }
325 
326 /**
327  * v9fs_file_flock_dotl - lock a file
328  * @filp: file to be locked
329  * @cmd: lock command
330  * @fl: file lock structure
331  *
332  */
333 
334 static int v9fs_file_flock_dotl(struct file *filp, int cmd,
335 	struct file_lock *fl)
336 {
337 	struct inode *inode = file_inode(filp);
338 	int ret = -ENOLCK;
339 
340 	p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n",
341 		 filp, cmd, fl, filp->f_path.dentry->d_name.name);
342 
343 	/* No mandatory locks */
344 	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
345 		goto out_err;
346 
347 	if (!(fl->fl_flags & FL_FLOCK))
348 		goto out_err;
349 
350 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
351 		filemap_write_and_wait(inode->i_mapping);
352 		invalidate_mapping_pages(&inode->i_data, 0, -1);
353 	}
354 	/* Convert flock to posix lock */
355 	fl->fl_owner = (fl_owner_t)filp;
356 	fl->fl_start = 0;
357 	fl->fl_end = OFFSET_MAX;
358 	fl->fl_flags |= FL_POSIX;
359 	fl->fl_flags ^= FL_FLOCK;
360 
361 	if (IS_SETLK(cmd) | IS_SETLKW(cmd))
362 		ret = v9fs_file_do_lock(filp, cmd, fl);
363 	else
364 		ret = -EINVAL;
365 out_err:
366 	return ret;
367 }
368 
369 /**
370  * v9fs_fid_readn - read from a fid
371  * @fid: fid to read
372  * @data: data buffer to read data into
373  * @udata: user data buffer to read data into
374  * @count: size of buffer
375  * @offset: offset at which to read data
376  *
377  */
378 ssize_t
379 v9fs_fid_readn(struct p9_fid *fid, char *data, char __user *udata, u32 count,
380 	       u64 offset)
381 {
382 	int n, total, size;
383 
384 	p9_debug(P9_DEBUG_VFS, "fid %d offset %llu count %d\n",
385 		 fid->fid, (long long unsigned)offset, count);
386 	n = 0;
387 	total = 0;
388 	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
389 	do {
390 		n = p9_client_read(fid, data, udata, offset, count);
391 		if (n <= 0)
392 			break;
393 
394 		if (data)
395 			data += n;
396 		if (udata)
397 			udata += n;
398 
399 		offset += n;
400 		count -= n;
401 		total += n;
402 	} while (count > 0 && n == size);
403 
404 	if (n < 0)
405 		total = n;
406 
407 	return total;
408 }
409 
410 /**
411  * v9fs_file_readn - read from a file
412  * @filp: file pointer to read
413  * @data: data buffer to read data into
414  * @udata: user data buffer to read data into
415  * @count: size of buffer
416  * @offset: offset at which to read data
417  *
418  */
419 ssize_t
420 v9fs_file_readn(struct file *filp, char *data, char __user *udata, u32 count,
421 	       u64 offset)
422 {
423 	return v9fs_fid_readn(filp->private_data, data, udata, count, offset);
424 }
425 
426 /**
427  * v9fs_file_read - read from a file
428  * @filp: file pointer to read
429  * @udata: user data buffer to read data into
430  * @count: size of buffer
431  * @offset: offset at which to read data
432  *
433  */
434 
435 static ssize_t
436 v9fs_file_read(struct file *filp, char __user *udata, size_t count,
437 	       loff_t * offset)
438 {
439 	int ret;
440 	struct p9_fid *fid;
441 	size_t size;
442 
443 	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
444 	fid = filp->private_data;
445 
446 	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
447 	if (count > size)
448 		ret = v9fs_file_readn(filp, NULL, udata, count, *offset);
449 	else
450 		ret = p9_client_read(fid, NULL, udata, *offset, count);
451 
452 	if (ret > 0)
453 		*offset += ret;
454 
455 	return ret;
456 }
457 
458 ssize_t
459 v9fs_file_write_internal(struct inode *inode, struct p9_fid *fid,
460 			 const char __user *data, size_t count,
461 			 loff_t *offset, int invalidate)
462 {
463 	int n;
464 	loff_t i_size;
465 	size_t total = 0;
466 	loff_t origin = *offset;
467 	unsigned long pg_start, pg_end;
468 
469 	p9_debug(P9_DEBUG_VFS, "data %p count %d offset %x\n",
470 		 data, (int)count, (int)*offset);
471 
472 	do {
473 		n = p9_client_write(fid, NULL, data+total, origin+total, count);
474 		if (n <= 0)
475 			break;
476 		count -= n;
477 		total += n;
478 	} while (count > 0);
479 
480 	if (invalidate && (total > 0)) {
481 		pg_start = origin >> PAGE_CACHE_SHIFT;
482 		pg_end = (origin + total - 1) >> PAGE_CACHE_SHIFT;
483 		if (inode->i_mapping && inode->i_mapping->nrpages)
484 			invalidate_inode_pages2_range(inode->i_mapping,
485 						      pg_start, pg_end);
486 		*offset += total;
487 		i_size = i_size_read(inode);
488 		if (*offset > i_size) {
489 			inode_add_bytes(inode, *offset - i_size);
490 			i_size_write(inode, *offset);
491 		}
492 	}
493 	if (n < 0)
494 		return n;
495 
496 	return total;
497 }
498 
499 /**
500  * v9fs_file_write - write to a file
501  * @filp: file pointer to write
502  * @data: data buffer to write data from
503  * @count: size of buffer
504  * @offset: offset at which to write data
505  *
506  */
507 static ssize_t
508 v9fs_file_write(struct file *filp, const char __user * data,
509 		size_t count, loff_t *offset)
510 {
511 	ssize_t retval = 0;
512 	loff_t origin = *offset;
513 
514 
515 	retval = generic_write_checks(filp, &origin, &count, 0);
516 	if (retval)
517 		goto out;
518 
519 	retval = -EINVAL;
520 	if ((ssize_t) count < 0)
521 		goto out;
522 	retval = 0;
523 	if (!count)
524 		goto out;
525 
526 	retval = v9fs_file_write_internal(file_inode(filp),
527 					filp->private_data,
528 					data, count, &origin, 1);
529 	/* update offset on successful write */
530 	if (retval > 0)
531 		*offset = origin;
532 out:
533 	return retval;
534 }
535 
536 
537 static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
538 			   int datasync)
539 {
540 	struct p9_fid *fid;
541 	struct inode *inode = filp->f_mapping->host;
542 	struct p9_wstat wstat;
543 	int retval;
544 
545 	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
546 	if (retval)
547 		return retval;
548 
549 	mutex_lock(&inode->i_mutex);
550 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
551 
552 	fid = filp->private_data;
553 	v9fs_blank_wstat(&wstat);
554 
555 	retval = p9_client_wstat(fid, &wstat);
556 	mutex_unlock(&inode->i_mutex);
557 
558 	return retval;
559 }
560 
561 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
562 			 int datasync)
563 {
564 	struct p9_fid *fid;
565 	struct inode *inode = filp->f_mapping->host;
566 	int retval;
567 
568 	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
569 	if (retval)
570 		return retval;
571 
572 	mutex_lock(&inode->i_mutex);
573 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
574 
575 	fid = filp->private_data;
576 
577 	retval = p9_client_fsync(fid, datasync);
578 	mutex_unlock(&inode->i_mutex);
579 
580 	return retval;
581 }
582 
583 static int
584 v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
585 {
586 	int retval;
587 
588 
589 	retval = generic_file_mmap(filp, vma);
590 	if (!retval)
591 		vma->vm_ops = &v9fs_file_vm_ops;
592 
593 	return retval;
594 }
595 
596 static int
597 v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma)
598 {
599 	int retval;
600 	struct inode *inode;
601 	struct v9fs_inode *v9inode;
602 	struct p9_fid *fid;
603 
604 	inode = file_inode(filp);
605 	v9inode = V9FS_I(inode);
606 	mutex_lock(&v9inode->v_mutex);
607 	if (!v9inode->writeback_fid &&
608 	    (vma->vm_flags & VM_WRITE)) {
609 		/*
610 		 * clone a fid and add it to writeback_fid
611 		 * we do it during mmap instead of
612 		 * page dirty time via write_begin/page_mkwrite
613 		 * because we want write after unlink usecase
614 		 * to work.
615 		 */
616 		fid = v9fs_writeback_fid(filp->f_path.dentry);
617 		if (IS_ERR(fid)) {
618 			retval = PTR_ERR(fid);
619 			mutex_unlock(&v9inode->v_mutex);
620 			return retval;
621 		}
622 		v9inode->writeback_fid = (void *) fid;
623 	}
624 	mutex_unlock(&v9inode->v_mutex);
625 
626 	retval = generic_file_mmap(filp, vma);
627 	if (!retval)
628 		vma->vm_ops = &v9fs_mmap_file_vm_ops;
629 
630 	return retval;
631 }
632 
633 static int
634 v9fs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
635 {
636 	struct v9fs_inode *v9inode;
637 	struct page *page = vmf->page;
638 	struct file *filp = vma->vm_file;
639 	struct inode *inode = file_inode(filp);
640 
641 
642 	p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n",
643 		 page, (unsigned long)filp->private_data);
644 
645 	/* Update file times before taking page lock */
646 	file_update_time(filp);
647 
648 	v9inode = V9FS_I(inode);
649 	/* make sure the cache has finished storing the page */
650 	v9fs_fscache_wait_on_page_write(inode, page);
651 	BUG_ON(!v9inode->writeback_fid);
652 	lock_page(page);
653 	if (page->mapping != inode->i_mapping)
654 		goto out_unlock;
655 	wait_for_stable_page(page);
656 
657 	return VM_FAULT_LOCKED;
658 out_unlock:
659 	unlock_page(page);
660 	return VM_FAULT_NOPAGE;
661 }
662 
663 static ssize_t
664 v9fs_direct_read(struct file *filp, char __user *udata, size_t count,
665 		 loff_t *offsetp)
666 {
667 	loff_t size, offset;
668 	struct inode *inode;
669 	struct address_space *mapping;
670 
671 	offset = *offsetp;
672 	mapping = filp->f_mapping;
673 	inode = mapping->host;
674 	if (!count)
675 		return 0;
676 	size = i_size_read(inode);
677 	if (offset < size)
678 		filemap_write_and_wait_range(mapping, offset,
679 					     offset + count - 1);
680 
681 	return v9fs_file_read(filp, udata, count, offsetp);
682 }
683 
684 /**
685  * v9fs_cached_file_read - read from a file
686  * @filp: file pointer to read
687  * @udata: user data buffer to read data into
688  * @count: size of buffer
689  * @offset: offset at which to read data
690  *
691  */
692 static ssize_t
693 v9fs_cached_file_read(struct file *filp, char __user *data, size_t count,
694 		      loff_t *offset)
695 {
696 	if (filp->f_flags & O_DIRECT)
697 		return v9fs_direct_read(filp, data, count, offset);
698 	return do_sync_read(filp, data, count, offset);
699 }
700 
701 /**
702  * v9fs_mmap_file_read - read from a file
703  * @filp: file pointer to read
704  * @udata: user data buffer to read data into
705  * @count: size of buffer
706  * @offset: offset at which to read data
707  *
708  */
709 static ssize_t
710 v9fs_mmap_file_read(struct file *filp, char __user *data, size_t count,
711 		      loff_t *offset)
712 {
713 	/* TODO: Check if there are dirty pages */
714 	return v9fs_file_read(filp, data, count, offset);
715 }
716 
717 static ssize_t
718 v9fs_direct_write(struct file *filp, const char __user * data,
719 		  size_t count, loff_t *offsetp)
720 {
721 	loff_t offset;
722 	ssize_t retval;
723 	struct inode *inode;
724 	struct address_space *mapping;
725 
726 	offset = *offsetp;
727 	mapping = filp->f_mapping;
728 	inode = mapping->host;
729 	if (!count)
730 		return 0;
731 
732 	mutex_lock(&inode->i_mutex);
733 	retval = filemap_write_and_wait_range(mapping, offset,
734 					      offset + count - 1);
735 	if (retval)
736 		goto err_out;
737 	/*
738 	 * After a write we want buffered reads to be sure to go to disk to get
739 	 * the new data.  We invalidate clean cached page from the region we're
740 	 * about to write.  We do this *before* the write so that if we fail
741 	 * here we fall back to buffered write
742 	 */
743 	if (mapping->nrpages) {
744 		pgoff_t pg_start = offset >> PAGE_CACHE_SHIFT;
745 		pgoff_t pg_end   = (offset + count - 1) >> PAGE_CACHE_SHIFT;
746 
747 		retval = invalidate_inode_pages2_range(mapping,
748 							pg_start, pg_end);
749 		/*
750 		 * If a page can not be invalidated, fall back
751 		 * to buffered write.
752 		 */
753 		if (retval) {
754 			if (retval == -EBUSY)
755 				goto buff_write;
756 			goto err_out;
757 		}
758 	}
759 	retval = v9fs_file_write(filp, data, count, offsetp);
760 err_out:
761 	mutex_unlock(&inode->i_mutex);
762 	return retval;
763 
764 buff_write:
765 	mutex_unlock(&inode->i_mutex);
766 	return do_sync_write(filp, data, count, offsetp);
767 }
768 
769 /**
770  * v9fs_cached_file_write - write to a file
771  * @filp: file pointer to write
772  * @data: data buffer to write data from
773  * @count: size of buffer
774  * @offset: offset at which to write data
775  *
776  */
777 static ssize_t
778 v9fs_cached_file_write(struct file *filp, const char __user * data,
779 		       size_t count, loff_t *offset)
780 {
781 
782 	if (filp->f_flags & O_DIRECT)
783 		return v9fs_direct_write(filp, data, count, offset);
784 	return do_sync_write(filp, data, count, offset);
785 }
786 
787 
788 /**
789  * v9fs_mmap_file_write - write to a file
790  * @filp: file pointer to write
791  * @data: data buffer to write data from
792  * @count: size of buffer
793  * @offset: offset at which to write data
794  *
795  */
796 static ssize_t
797 v9fs_mmap_file_write(struct file *filp, const char __user *data,
798 		       size_t count, loff_t *offset)
799 {
800 	/*
801 	 * TODO: invalidate mmaps on filp's inode between
802 	 * offset and offset+count
803 	 */
804 	return v9fs_file_write(filp, data, count, offset);
805 }
806 
807 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
808 {
809 	struct inode *inode;
810 
811 	struct writeback_control wbc = {
812 		.nr_to_write = LONG_MAX,
813 		.sync_mode = WB_SYNC_ALL,
814 		.range_start = vma->vm_pgoff * PAGE_SIZE,
815 		 /* absolute end, byte at end included */
816 		.range_end = vma->vm_pgoff * PAGE_SIZE +
817 			(vma->vm_end - vma->vm_start - 1),
818 	};
819 
820 
821 	p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma);
822 
823 	inode = file_inode(vma->vm_file);
824 
825 	if (!mapping_cap_writeback_dirty(inode->i_mapping))
826 		wbc.nr_to_write = 0;
827 
828 	might_sleep();
829 	sync_inode(inode, &wbc);
830 }
831 
832 
833 static const struct vm_operations_struct v9fs_file_vm_ops = {
834 	.fault = filemap_fault,
835 	.map_pages = filemap_map_pages,
836 	.page_mkwrite = v9fs_vm_page_mkwrite,
837 	.remap_pages = generic_file_remap_pages,
838 };
839 
840 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
841 	.close = v9fs_mmap_vm_close,
842 	.fault = filemap_fault,
843 	.map_pages = filemap_map_pages,
844 	.page_mkwrite = v9fs_vm_page_mkwrite,
845 	.remap_pages = generic_file_remap_pages,
846 };
847 
848 
849 const struct file_operations v9fs_cached_file_operations = {
850 	.llseek = generic_file_llseek,
851 	.read = v9fs_cached_file_read,
852 	.write = v9fs_cached_file_write,
853 	.aio_read = generic_file_aio_read,
854 	.aio_write = generic_file_aio_write,
855 	.open = v9fs_file_open,
856 	.release = v9fs_dir_release,
857 	.lock = v9fs_file_lock,
858 	.mmap = v9fs_file_mmap,
859 	.fsync = v9fs_file_fsync,
860 };
861 
862 const struct file_operations v9fs_cached_file_operations_dotl = {
863 	.llseek = generic_file_llseek,
864 	.read = v9fs_cached_file_read,
865 	.write = v9fs_cached_file_write,
866 	.aio_read = generic_file_aio_read,
867 	.aio_write = generic_file_aio_write,
868 	.open = v9fs_file_open,
869 	.release = v9fs_dir_release,
870 	.lock = v9fs_file_lock_dotl,
871 	.flock = v9fs_file_flock_dotl,
872 	.mmap = v9fs_file_mmap,
873 	.fsync = v9fs_file_fsync_dotl,
874 };
875 
876 const struct file_operations v9fs_file_operations = {
877 	.llseek = generic_file_llseek,
878 	.read = v9fs_file_read,
879 	.write = v9fs_file_write,
880 	.open = v9fs_file_open,
881 	.release = v9fs_dir_release,
882 	.lock = v9fs_file_lock,
883 	.mmap = generic_file_readonly_mmap,
884 	.fsync = v9fs_file_fsync,
885 };
886 
887 const struct file_operations v9fs_file_operations_dotl = {
888 	.llseek = generic_file_llseek,
889 	.read = v9fs_file_read,
890 	.write = v9fs_file_write,
891 	.open = v9fs_file_open,
892 	.release = v9fs_dir_release,
893 	.lock = v9fs_file_lock_dotl,
894 	.flock = v9fs_file_flock_dotl,
895 	.mmap = generic_file_readonly_mmap,
896 	.fsync = v9fs_file_fsync_dotl,
897 };
898 
899 const struct file_operations v9fs_mmap_file_operations = {
900 	.llseek = generic_file_llseek,
901 	.read = v9fs_mmap_file_read,
902 	.write = v9fs_mmap_file_write,
903 	.open = v9fs_file_open,
904 	.release = v9fs_dir_release,
905 	.lock = v9fs_file_lock,
906 	.mmap = v9fs_mmap_file_mmap,
907 	.fsync = v9fs_file_fsync,
908 };
909 
910 const struct file_operations v9fs_mmap_file_operations_dotl = {
911 	.llseek = generic_file_llseek,
912 	.read = v9fs_mmap_file_read,
913 	.write = v9fs_mmap_file_write,
914 	.open = v9fs_file_open,
915 	.release = v9fs_dir_release,
916 	.lock = v9fs_file_lock_dotl,
917 	.flock = v9fs_file_flock_dotl,
918 	.mmap = v9fs_mmap_file_mmap,
919 	.fsync = v9fs_file_fsync_dotl,
920 };
921