xref: /openbmc/linux/fs/9p/vfs_file.c (revision 16b90578)
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_flags |= FL_POSIX;
356 	fl->fl_flags ^= FL_FLOCK;
357 
358 	if (IS_SETLK(cmd) | IS_SETLKW(cmd))
359 		ret = v9fs_file_do_lock(filp, cmd, fl);
360 	else
361 		ret = -EINVAL;
362 out_err:
363 	return ret;
364 }
365 
366 /**
367  * v9fs_fid_readn - read from a fid
368  * @fid: fid to read
369  * @data: data buffer to read data into
370  * @udata: user data buffer to read data into
371  * @count: size of buffer
372  * @offset: offset at which to read data
373  *
374  */
375 ssize_t
376 v9fs_fid_readn(struct p9_fid *fid, char *data, char __user *udata, u32 count,
377 	       u64 offset)
378 {
379 	int n, total, size;
380 
381 	p9_debug(P9_DEBUG_VFS, "fid %d offset %llu count %d\n",
382 		 fid->fid, (long long unsigned)offset, count);
383 	n = 0;
384 	total = 0;
385 	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
386 	do {
387 		n = p9_client_read(fid, data, udata, offset, count);
388 		if (n <= 0)
389 			break;
390 
391 		if (data)
392 			data += n;
393 		if (udata)
394 			udata += n;
395 
396 		offset += n;
397 		count -= n;
398 		total += n;
399 	} while (count > 0 && n == size);
400 
401 	if (n < 0)
402 		total = n;
403 
404 	return total;
405 }
406 
407 /**
408  * v9fs_file_readn - read from a file
409  * @filp: file pointer to read
410  * @data: data buffer to read data into
411  * @udata: user data buffer to read data into
412  * @count: size of buffer
413  * @offset: offset at which to read data
414  *
415  */
416 ssize_t
417 v9fs_file_readn(struct file *filp, char *data, char __user *udata, u32 count,
418 	       u64 offset)
419 {
420 	return v9fs_fid_readn(filp->private_data, data, udata, count, offset);
421 }
422 
423 /**
424  * v9fs_file_read - read from a file
425  * @filp: file pointer to read
426  * @udata: user data buffer to read data into
427  * @count: size of buffer
428  * @offset: offset at which to read data
429  *
430  */
431 
432 static ssize_t
433 v9fs_file_read(struct file *filp, char __user *udata, size_t count,
434 	       loff_t * offset)
435 {
436 	int ret;
437 	struct p9_fid *fid;
438 	size_t size;
439 
440 	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
441 	fid = filp->private_data;
442 
443 	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
444 	if (count > size)
445 		ret = v9fs_file_readn(filp, NULL, udata, count, *offset);
446 	else
447 		ret = p9_client_read(fid, NULL, udata, *offset, count);
448 
449 	if (ret > 0)
450 		*offset += ret;
451 
452 	return ret;
453 }
454 
455 ssize_t
456 v9fs_file_write_internal(struct inode *inode, struct p9_fid *fid,
457 			 const char __user *data, size_t count,
458 			 loff_t *offset, int invalidate)
459 {
460 	int n;
461 	loff_t i_size;
462 	size_t total = 0;
463 	loff_t origin = *offset;
464 	unsigned long pg_start, pg_end;
465 
466 	p9_debug(P9_DEBUG_VFS, "data %p count %d offset %x\n",
467 		 data, (int)count, (int)*offset);
468 
469 	do {
470 		n = p9_client_write(fid, NULL, data+total, origin+total, count);
471 		if (n <= 0)
472 			break;
473 		count -= n;
474 		total += n;
475 	} while (count > 0);
476 
477 	if (invalidate && (total > 0)) {
478 		pg_start = origin >> PAGE_CACHE_SHIFT;
479 		pg_end = (origin + total - 1) >> PAGE_CACHE_SHIFT;
480 		if (inode->i_mapping && inode->i_mapping->nrpages)
481 			invalidate_inode_pages2_range(inode->i_mapping,
482 						      pg_start, pg_end);
483 		*offset += total;
484 		i_size = i_size_read(inode);
485 		if (*offset > i_size) {
486 			inode_add_bytes(inode, *offset - i_size);
487 			i_size_write(inode, *offset);
488 		}
489 	}
490 	if (n < 0)
491 		return n;
492 
493 	return total;
494 }
495 
496 /**
497  * v9fs_file_write - write to a file
498  * @filp: file pointer to write
499  * @data: data buffer to write data from
500  * @count: size of buffer
501  * @offset: offset at which to write data
502  *
503  */
504 static ssize_t
505 v9fs_file_write(struct file *filp, const char __user * data,
506 		size_t count, loff_t *offset)
507 {
508 	ssize_t retval = 0;
509 	loff_t origin = *offset;
510 
511 
512 	retval = generic_write_checks(filp, &origin, &count, 0);
513 	if (retval)
514 		goto out;
515 
516 	retval = -EINVAL;
517 	if ((ssize_t) count < 0)
518 		goto out;
519 	retval = 0;
520 	if (!count)
521 		goto out;
522 
523 	retval = v9fs_file_write_internal(file_inode(filp),
524 					filp->private_data,
525 					data, count, &origin, 1);
526 	/* update offset on successful write */
527 	if (retval > 0)
528 		*offset = origin;
529 out:
530 	return retval;
531 }
532 
533 
534 static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
535 			   int datasync)
536 {
537 	struct p9_fid *fid;
538 	struct inode *inode = filp->f_mapping->host;
539 	struct p9_wstat wstat;
540 	int retval;
541 
542 	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
543 	if (retval)
544 		return retval;
545 
546 	mutex_lock(&inode->i_mutex);
547 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
548 
549 	fid = filp->private_data;
550 	v9fs_blank_wstat(&wstat);
551 
552 	retval = p9_client_wstat(fid, &wstat);
553 	mutex_unlock(&inode->i_mutex);
554 
555 	return retval;
556 }
557 
558 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
559 			 int datasync)
560 {
561 	struct p9_fid *fid;
562 	struct inode *inode = filp->f_mapping->host;
563 	int retval;
564 
565 	retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
566 	if (retval)
567 		return retval;
568 
569 	mutex_lock(&inode->i_mutex);
570 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
571 
572 	fid = filp->private_data;
573 
574 	retval = p9_client_fsync(fid, datasync);
575 	mutex_unlock(&inode->i_mutex);
576 
577 	return retval;
578 }
579 
580 static int
581 v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
582 {
583 	int retval;
584 
585 
586 	retval = generic_file_mmap(filp, vma);
587 	if (!retval)
588 		vma->vm_ops = &v9fs_file_vm_ops;
589 
590 	return retval;
591 }
592 
593 static int
594 v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma)
595 {
596 	int retval;
597 	struct inode *inode;
598 	struct v9fs_inode *v9inode;
599 	struct p9_fid *fid;
600 
601 	inode = file_inode(filp);
602 	v9inode = V9FS_I(inode);
603 	mutex_lock(&v9inode->v_mutex);
604 	if (!v9inode->writeback_fid &&
605 	    (vma->vm_flags & VM_WRITE)) {
606 		/*
607 		 * clone a fid and add it to writeback_fid
608 		 * we do it during mmap instead of
609 		 * page dirty time via write_begin/page_mkwrite
610 		 * because we want write after unlink usecase
611 		 * to work.
612 		 */
613 		fid = v9fs_writeback_fid(filp->f_path.dentry);
614 		if (IS_ERR(fid)) {
615 			retval = PTR_ERR(fid);
616 			mutex_unlock(&v9inode->v_mutex);
617 			return retval;
618 		}
619 		v9inode->writeback_fid = (void *) fid;
620 	}
621 	mutex_unlock(&v9inode->v_mutex);
622 
623 	retval = generic_file_mmap(filp, vma);
624 	if (!retval)
625 		vma->vm_ops = &v9fs_mmap_file_vm_ops;
626 
627 	return retval;
628 }
629 
630 static int
631 v9fs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
632 {
633 	struct v9fs_inode *v9inode;
634 	struct page *page = vmf->page;
635 	struct file *filp = vma->vm_file;
636 	struct inode *inode = file_inode(filp);
637 
638 
639 	p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n",
640 		 page, (unsigned long)filp->private_data);
641 
642 	/* Update file times before taking page lock */
643 	file_update_time(filp);
644 
645 	v9inode = V9FS_I(inode);
646 	/* make sure the cache has finished storing the page */
647 	v9fs_fscache_wait_on_page_write(inode, page);
648 	BUG_ON(!v9inode->writeback_fid);
649 	lock_page(page);
650 	if (page->mapping != inode->i_mapping)
651 		goto out_unlock;
652 	wait_for_stable_page(page);
653 
654 	return VM_FAULT_LOCKED;
655 out_unlock:
656 	unlock_page(page);
657 	return VM_FAULT_NOPAGE;
658 }
659 
660 static ssize_t
661 v9fs_direct_read(struct file *filp, char __user *udata, size_t count,
662 		 loff_t *offsetp)
663 {
664 	loff_t size, offset;
665 	struct inode *inode;
666 	struct address_space *mapping;
667 
668 	offset = *offsetp;
669 	mapping = filp->f_mapping;
670 	inode = mapping->host;
671 	if (!count)
672 		return 0;
673 	size = i_size_read(inode);
674 	if (offset < size)
675 		filemap_write_and_wait_range(mapping, offset,
676 					     offset + count - 1);
677 
678 	return v9fs_file_read(filp, udata, count, offsetp);
679 }
680 
681 /**
682  * v9fs_cached_file_read - read from a file
683  * @filp: file pointer to read
684  * @data: user data buffer to read data into
685  * @count: size of buffer
686  * @offset: offset at which to read data
687  *
688  */
689 static ssize_t
690 v9fs_cached_file_read(struct file *filp, char __user *data, size_t count,
691 		      loff_t *offset)
692 {
693 	if (filp->f_flags & O_DIRECT)
694 		return v9fs_direct_read(filp, data, count, offset);
695 	return new_sync_read(filp, data, count, offset);
696 }
697 
698 /**
699  * v9fs_mmap_file_read - read from a file
700  * @filp: file pointer to read
701  * @data: user data buffer to read data into
702  * @count: size of buffer
703  * @offset: offset at which to read data
704  *
705  */
706 static ssize_t
707 v9fs_mmap_file_read(struct file *filp, char __user *data, size_t count,
708 		      loff_t *offset)
709 {
710 	/* TODO: Check if there are dirty pages */
711 	return v9fs_file_read(filp, data, count, offset);
712 }
713 
714 static ssize_t
715 v9fs_direct_write(struct file *filp, const char __user * data,
716 		  size_t count, loff_t *offsetp)
717 {
718 	loff_t offset;
719 	ssize_t retval;
720 	struct inode *inode;
721 	struct address_space *mapping;
722 
723 	offset = *offsetp;
724 	mapping = filp->f_mapping;
725 	inode = mapping->host;
726 	if (!count)
727 		return 0;
728 
729 	mutex_lock(&inode->i_mutex);
730 	retval = filemap_write_and_wait_range(mapping, offset,
731 					      offset + count - 1);
732 	if (retval)
733 		goto err_out;
734 	/*
735 	 * After a write we want buffered reads to be sure to go to disk to get
736 	 * the new data.  We invalidate clean cached page from the region we're
737 	 * about to write.  We do this *before* the write so that if we fail
738 	 * here we fall back to buffered write
739 	 */
740 	if (mapping->nrpages) {
741 		pgoff_t pg_start = offset >> PAGE_CACHE_SHIFT;
742 		pgoff_t pg_end   = (offset + count - 1) >> PAGE_CACHE_SHIFT;
743 
744 		retval = invalidate_inode_pages2_range(mapping,
745 							pg_start, pg_end);
746 		/*
747 		 * If a page can not be invalidated, fall back
748 		 * to buffered write.
749 		 */
750 		if (retval) {
751 			if (retval == -EBUSY)
752 				goto buff_write;
753 			goto err_out;
754 		}
755 	}
756 	retval = v9fs_file_write(filp, data, count, offsetp);
757 err_out:
758 	mutex_unlock(&inode->i_mutex);
759 	return retval;
760 
761 buff_write:
762 	mutex_unlock(&inode->i_mutex);
763 	return new_sync_write(filp, data, count, offsetp);
764 }
765 
766 /**
767  * v9fs_cached_file_write - write to a file
768  * @filp: file pointer to write
769  * @data: data buffer to write data from
770  * @count: size of buffer
771  * @offset: offset at which to write data
772  *
773  */
774 static ssize_t
775 v9fs_cached_file_write(struct file *filp, const char __user * data,
776 		       size_t count, loff_t *offset)
777 {
778 
779 	if (filp->f_flags & O_DIRECT)
780 		return v9fs_direct_write(filp, data, count, offset);
781 	return new_sync_write(filp, data, count, offset);
782 }
783 
784 
785 /**
786  * v9fs_mmap_file_write - write to a file
787  * @filp: file pointer to write
788  * @data: data buffer to write data from
789  * @count: size of buffer
790  * @offset: offset at which to write data
791  *
792  */
793 static ssize_t
794 v9fs_mmap_file_write(struct file *filp, const char __user *data,
795 		       size_t count, loff_t *offset)
796 {
797 	/*
798 	 * TODO: invalidate mmaps on filp's inode between
799 	 * offset and offset+count
800 	 */
801 	return v9fs_file_write(filp, data, count, offset);
802 }
803 
804 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
805 {
806 	struct inode *inode;
807 
808 	struct writeback_control wbc = {
809 		.nr_to_write = LONG_MAX,
810 		.sync_mode = WB_SYNC_ALL,
811 		.range_start = vma->vm_pgoff * PAGE_SIZE,
812 		 /* absolute end, byte at end included */
813 		.range_end = vma->vm_pgoff * PAGE_SIZE +
814 			(vma->vm_end - vma->vm_start - 1),
815 	};
816 
817 
818 	p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma);
819 
820 	inode = file_inode(vma->vm_file);
821 
822 	if (!mapping_cap_writeback_dirty(inode->i_mapping))
823 		wbc.nr_to_write = 0;
824 
825 	might_sleep();
826 	sync_inode(inode, &wbc);
827 }
828 
829 
830 static const struct vm_operations_struct v9fs_file_vm_ops = {
831 	.fault = filemap_fault,
832 	.map_pages = filemap_map_pages,
833 	.page_mkwrite = v9fs_vm_page_mkwrite,
834 	.remap_pages = generic_file_remap_pages,
835 };
836 
837 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
838 	.close = v9fs_mmap_vm_close,
839 	.fault = filemap_fault,
840 	.map_pages = filemap_map_pages,
841 	.page_mkwrite = v9fs_vm_page_mkwrite,
842 	.remap_pages = generic_file_remap_pages,
843 };
844 
845 
846 const struct file_operations v9fs_cached_file_operations = {
847 	.llseek = generic_file_llseek,
848 	.read = v9fs_cached_file_read,
849 	.write = v9fs_cached_file_write,
850 	.read_iter = generic_file_read_iter,
851 	.write_iter = generic_file_write_iter,
852 	.open = v9fs_file_open,
853 	.release = v9fs_dir_release,
854 	.lock = v9fs_file_lock,
855 	.mmap = v9fs_file_mmap,
856 	.fsync = v9fs_file_fsync,
857 };
858 
859 const struct file_operations v9fs_cached_file_operations_dotl = {
860 	.llseek = generic_file_llseek,
861 	.read = v9fs_cached_file_read,
862 	.write = v9fs_cached_file_write,
863 	.read_iter = generic_file_read_iter,
864 	.write_iter = generic_file_write_iter,
865 	.open = v9fs_file_open,
866 	.release = v9fs_dir_release,
867 	.lock = v9fs_file_lock_dotl,
868 	.flock = v9fs_file_flock_dotl,
869 	.mmap = v9fs_file_mmap,
870 	.fsync = v9fs_file_fsync_dotl,
871 };
872 
873 const struct file_operations v9fs_file_operations = {
874 	.llseek = generic_file_llseek,
875 	.read = v9fs_file_read,
876 	.write = v9fs_file_write,
877 	.open = v9fs_file_open,
878 	.release = v9fs_dir_release,
879 	.lock = v9fs_file_lock,
880 	.mmap = generic_file_readonly_mmap,
881 	.fsync = v9fs_file_fsync,
882 };
883 
884 const struct file_operations v9fs_file_operations_dotl = {
885 	.llseek = generic_file_llseek,
886 	.read = v9fs_file_read,
887 	.write = v9fs_file_write,
888 	.open = v9fs_file_open,
889 	.release = v9fs_dir_release,
890 	.lock = v9fs_file_lock_dotl,
891 	.flock = v9fs_file_flock_dotl,
892 	.mmap = generic_file_readonly_mmap,
893 	.fsync = v9fs_file_fsync_dotl,
894 };
895 
896 const struct file_operations v9fs_mmap_file_operations = {
897 	.llseek = generic_file_llseek,
898 	.read = v9fs_mmap_file_read,
899 	.write = v9fs_mmap_file_write,
900 	.open = v9fs_file_open,
901 	.release = v9fs_dir_release,
902 	.lock = v9fs_file_lock,
903 	.mmap = v9fs_mmap_file_mmap,
904 	.fsync = v9fs_file_fsync,
905 };
906 
907 const struct file_operations v9fs_mmap_file_operations_dotl = {
908 	.llseek = generic_file_llseek,
909 	.read = v9fs_mmap_file_read,
910 	.write = v9fs_mmap_file_write,
911 	.open = v9fs_file_open,
912 	.release = v9fs_dir_release,
913 	.lock = v9fs_file_lock_dotl,
914 	.flock = v9fs_file_flock_dotl,
915 	.mmap = v9fs_mmap_file_mmap,
916 	.fsync = v9fs_file_fsync_dotl,
917 };
918